Adding upstream version 18.2.2.upstream/18.2.2

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

59 files changed, 15426 insertions, 0 deletions

diff --git a/src/rocksdb/utilities/transactions/lock/lock_manager.cc b/src/rocksdb/utilities/transactions/lock/lock_manager.cc
new file mode 100644
index 000000000..df16b32ad
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/lock_manager.cc
@@ -0,0 +1,29 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+
+#ifndef ROCKSDB_LITE
+
+#include "utilities/transactions/lock/lock_manager.h"
+
+#include "utilities/transactions/lock/point/point_lock_manager.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+std::shared_ptr<LockManager> NewLockManager(PessimisticTransactionDB* db,
+                                            const TransactionDBOptions& opt) {
+  assert(db);
+  if (opt.lock_mgr_handle) {
+    // A custom lock manager was provided in options
+    auto mgr = opt.lock_mgr_handle->getLockManager();
+    return std::shared_ptr<LockManager>(opt.lock_mgr_handle, mgr);
+  } else {
+    // Use a point lock manager by default
+    return std::shared_ptr<LockManager>(new PointLockManager(db, opt));
+  }
+}
+
+}  // namespace ROCKSDB_NAMESPACE
+
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/lock_manager.h b/src/rocksdb/utilities/transactions/lock/lock_manager.h
new file mode 100644
index 000000000..a5ce1948c
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/lock_manager.h
@@ -0,0 +1,82 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+#ifndef ROCKSDB_LITE
+
+#include "rocksdb/types.h"
+#include "rocksdb/utilities/transaction.h"
+#include "rocksdb/utilities/transaction_db.h"
+#include "utilities/transactions/lock/lock_tracker.h"
+#include "utilities/transactions/pessimistic_transaction.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class PessimisticTransactionDB;
+
+class LockManager {
+ public:
+  virtual ~LockManager() {}
+
+  // Whether supports locking a specific key.
+  virtual bool IsPointLockSupported() const = 0;
+
+  // Whether supports locking a range of keys.
+  virtual bool IsRangeLockSupported() const = 0;
+
+  // Locks acquired through this LockManager should be tracked by
+  // the LockTrackers created through the returned factory.
+  virtual const LockTrackerFactory& GetLockTrackerFactory() const = 0;
+
+  // Enable locking for the specified column family.
+  // Caller should guarantee that this column family is not already enabled.
+  virtual void AddColumnFamily(const ColumnFamilyHandle* cf) = 0;
+
+  // Disable locking for the specified column family.
+  // Caller should guarantee that this column family is no longer used.
+  virtual void RemoveColumnFamily(const ColumnFamilyHandle* cf) = 0;
+
+  // Attempt to lock a key or a key range.  If OK status is returned, the caller
+  // is responsible for calling UnLock() on this key.
+  virtual Status TryLock(PessimisticTransaction* txn,
+                         ColumnFamilyId column_family_id,
+                         const std::string& key, Env* env, bool exclusive) = 0;
+  // The range [start, end] are inclusive at both sides.
+  virtual Status TryLock(PessimisticTransaction* txn,
+                         ColumnFamilyId column_family_id, const Endpoint& start,
+                         const Endpoint& end, Env* env, bool exclusive) = 0;
+
+  // Unlock a key or a range locked by TryLock().  txn must be the same
+  // Transaction that locked this key.
+  virtual void UnLock(PessimisticTransaction* txn, const LockTracker& tracker,
+                      Env* env) = 0;
+  virtual void UnLock(PessimisticTransaction* txn,
+                      ColumnFamilyId column_family_id, const std::string& key,
+                      Env* env) = 0;
+  virtual void UnLock(PessimisticTransaction* txn,
+                      ColumnFamilyId column_family_id, const Endpoint& start,
+                      const Endpoint& end, Env* env) = 0;
+
+  using PointLockStatus = std::unordered_multimap<ColumnFamilyId, KeyLockInfo>;
+  virtual PointLockStatus GetPointLockStatus() = 0;
+
+  using RangeLockStatus =
+      std::unordered_multimap<ColumnFamilyId, RangeLockInfo>;
+  virtual RangeLockStatus GetRangeLockStatus() = 0;
+
+  virtual std::vector<DeadlockPath> GetDeadlockInfoBuffer() = 0;
+
+  virtual void Resize(uint32_t new_size) = 0;
+};
+
+// LockManager should always be constructed through this factory method,
+// instead of constructing through concrete implementations' constructor.
+// Caller owns the returned pointer.
+std::shared_ptr<LockManager> NewLockManager(PessimisticTransactionDB* db,
+                                            const TransactionDBOptions& opt);
+
+}  // namespace ROCKSDB_NAMESPACE
+
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/lock_tracker.h b/src/rocksdb/utilities/transactions/lock/lock_tracker.h
new file mode 100644
index 000000000..5fa228a82
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/lock_tracker.h
@@ -0,0 +1,209 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+#ifndef ROCKSDB_LITE
+
+#include <memory>
+
+#include "rocksdb/rocksdb_namespace.h"
+#include "rocksdb/status.h"
+#include "rocksdb/types.h"
+#include "rocksdb/utilities/transaction_db.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+// Request for locking a single key.
+struct PointLockRequest {
+  // The id of the key's column family.
+  ColumnFamilyId column_family_id = 0;
+  // The key to lock.
+  std::string key;
+  // The sequence number from which there is no concurrent update to key.
+  SequenceNumber seq = 0;
+  // Whether the lock is acquired only for read.
+  bool read_only = false;
+  // Whether the lock is in exclusive mode.
+  bool exclusive = true;
+};
+
+// Request for locking a range of keys.
+struct RangeLockRequest {
+  // The id of the key's column family.
+  ColumnFamilyId column_family_id;
+
+  // The range to be locked
+  Endpoint start_endp;
+  Endpoint end_endp;
+};
+
+struct PointLockStatus {
+  // Whether the key is locked.
+  bool locked = false;
+  // Whether the key is locked in exclusive mode.
+  bool exclusive = true;
+  // The sequence number in the tracked PointLockRequest.
+  SequenceNumber seq = 0;
+};
+
+// Return status when calling LockTracker::Untrack.
+enum class UntrackStatus {
+  // The lock is not tracked at all, so no lock to untrack.
+  NOT_TRACKED,
+  // The lock is untracked but not removed from the tracker.
+  UNTRACKED,
+  // The lock is removed from the tracker.
+  REMOVED,
+};
+
+// Tracks the lock requests.
+// In PessimisticTransaction, it tracks the locks acquired through LockMgr;
+// In OptimisticTransaction, since there is no LockMgr, it tracks the lock
+// intention. Not thread-safe.
+class LockTracker {
+ public:
+  virtual ~LockTracker() {}
+
+  // Whether supports locking a specific key.
+  virtual bool IsPointLockSupported() const = 0;
+
+  // Whether supports locking a range of keys.
+  virtual bool IsRangeLockSupported() const = 0;
+
+  // Tracks the acquirement of a lock on key.
+  //
+  // If this method is not supported, leave it as a no-op.
+  virtual void Track(const PointLockRequest& /*lock_request*/) = 0;
+
+  // Untracks the lock on a key.
+  // seq and exclusive in lock_request are not used.
+  //
+  // If this method is not supported, leave it as a no-op and
+  // returns NOT_TRACKED.
+  virtual UntrackStatus Untrack(const PointLockRequest& /*lock_request*/) = 0;
+
+  // Counterpart of Track(const PointLockRequest&) for RangeLockRequest.
+  virtual void Track(const RangeLockRequest& /*lock_request*/) = 0;
+
+  // Counterpart of Untrack(const PointLockRequest&) for RangeLockRequest.
+  virtual UntrackStatus Untrack(const RangeLockRequest& /*lock_request*/) = 0;
+
+  // Merges lock requests tracked in the specified tracker into the current
+  // tracker.
+  //
+  // E.g. for point lock, if a key in tracker is not yet tracked,
+  // track this new key; otherwise, merge the tracked information of the key
+  // such as lock's exclusiveness, read/write statistics.
+  //
+  // If this method is not supported, leave it as a no-op.
+  //
+  // REQUIRED: the specified tracker must be of the same concrete class type as
+  // the current tracker.
+  virtual void Merge(const LockTracker& /*tracker*/) = 0;
+
+  // This is a reverse operation of Merge.
+  //
+  // E.g. for point lock, if a key exists in both current and the sepcified
+  // tracker, then subtract the information (such as read/write statistics) of
+  // the key in the specified tracker from the current tracker.
+  //
+  // If this method is not supported, leave it as a no-op.
+  //
+  // REQUIRED:
+  // The specified tracker must be of the same concrete class type as
+  // the current tracker.
+  // The tracked locks in the specified tracker must be a subset of those
+  // tracked by the current tracker.
+  virtual void Subtract(const LockTracker& /*tracker*/) = 0;
+
+  // Clears all tracked locks.
+  virtual void Clear() = 0;
+
+  // Gets the new locks (excluding the locks that have been tracked before the
+  // save point) tracked since the specified save point, the result is stored
+  // in an internally constructed LockTracker and returned.
+  //
+  // save_point_tracker is the tracker used by a SavePoint to track locks
+  // tracked after creating the SavePoint.
+  //
+  // The implementation should document whether point lock, or range lock, or
+  // both are considered in this method.
+  // If this method is not supported, returns nullptr.
+  //
+  // REQUIRED:
+  // The save_point_tracker must be of the same concrete class type as the
+  // current tracker.
+  // The tracked locks in the specified tracker must be a subset of those
+  // tracked by the current tracker.
+  virtual LockTracker* GetTrackedLocksSinceSavePoint(
+      const LockTracker& /*save_point_tracker*/) const = 0;
+
+  // Gets lock related information of the key.
+  //
+  // If point lock is not supported, always returns LockStatus with
+  // locked=false.
+  virtual PointLockStatus GetPointLockStatus(
+      ColumnFamilyId /*column_family_id*/,
+      const std::string& /*key*/) const = 0;
+
+  // Gets number of tracked point locks.
+  //
+  // If point lock is not supported, always returns 0.
+  virtual uint64_t GetNumPointLocks() const = 0;
+
+  class ColumnFamilyIterator {
+   public:
+    virtual ~ColumnFamilyIterator() {}
+
+    // Whether there are remaining column families.
+    virtual bool HasNext() const = 0;
+
+    // Gets next column family id.
+    //
+    // If HasNext is false, calling this method has undefined behavior.
+    virtual ColumnFamilyId Next() = 0;
+  };
+
+  // Gets an iterator for column families.
+  //
+  // Returned iterator must not be nullptr.
+  // If there is no column family to iterate,
+  // returns an empty non-null iterator.
+  // Caller owns the returned pointer.
+  virtual ColumnFamilyIterator* GetColumnFamilyIterator() const = 0;
+
+  class KeyIterator {
+   public:
+    virtual ~KeyIterator() {}
+
+    // Whether there are remaining keys.
+    virtual bool HasNext() const = 0;
+
+    // Gets the next key.
+    //
+    // If HasNext is false, calling this method has undefined behavior.
+    virtual const std::string& Next() = 0;
+  };
+
+  // Gets an iterator for keys with tracked point locks in the column family.
+  //
+  // The column family must exist.
+  // Returned iterator must not be nullptr.
+  // Caller owns the returned pointer.
+  virtual KeyIterator* GetKeyIterator(
+      ColumnFamilyId /*column_family_id*/) const = 0;
+};
+
+// LockTracker should always be constructed through this factory.
+// Each LockManager owns a LockTrackerFactory.
+class LockTrackerFactory {
+ public:
+  // Caller owns the returned pointer.
+  virtual LockTracker* Create() const = 0;
+  virtual ~LockTrackerFactory() {}
+};
+
+}  // namespace ROCKSDB_NAMESPACE
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/point/point_lock_manager.cc b/src/rocksdb/utilities/transactions/lock/point/point_lock_manager.cc
new file mode 100644
index 000000000..b362a164d
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/point/point_lock_manager.cc
@@ -0,0 +1,721 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#ifndef ROCKSDB_LITE
+
+#include "utilities/transactions/lock/point/point_lock_manager.h"
+
+#include <algorithm>
+#include <cinttypes>
+#include <mutex>
+
+#include "monitoring/perf_context_imp.h"
+#include "rocksdb/slice.h"
+#include "rocksdb/utilities/transaction_db_mutex.h"
+#include "test_util/sync_point.h"
+#include "util/cast_util.h"
+#include "util/hash.h"
+#include "util/thread_local.h"
+#include "utilities/transactions/pessimistic_transaction_db.h"
+#include "utilities/transactions/transaction_db_mutex_impl.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+struct LockInfo {
+  bool exclusive;
+  autovector<TransactionID> txn_ids;
+
+  // Transaction locks are not valid after this time in us
+  uint64_t expiration_time;
+
+  LockInfo(TransactionID id, uint64_t time, bool ex)
+      : exclusive(ex), expiration_time(time) {
+    txn_ids.push_back(id);
+  }
+  LockInfo(const LockInfo& lock_info)
+      : exclusive(lock_info.exclusive),
+        txn_ids(lock_info.txn_ids),
+        expiration_time(lock_info.expiration_time) {}
+  void operator=(const LockInfo& lock_info) {
+    exclusive = lock_info.exclusive;
+    txn_ids = lock_info.txn_ids;
+    expiration_time = lock_info.expiration_time;
+  }
+  DECLARE_DEFAULT_MOVES(LockInfo);
+};
+
+struct LockMapStripe {
+  explicit LockMapStripe(std::shared_ptr<TransactionDBMutexFactory> factory) {
+    stripe_mutex = factory->AllocateMutex();
+    stripe_cv = factory->AllocateCondVar();
+    assert(stripe_mutex);
+    assert(stripe_cv);
+  }
+
+  // Mutex must be held before modifying keys map
+  std::shared_ptr<TransactionDBMutex> stripe_mutex;
+
+  // Condition Variable per stripe for waiting on a lock
+  std::shared_ptr<TransactionDBCondVar> stripe_cv;
+
+  // Locked keys mapped to the info about the transactions that locked them.
+  // TODO(agiardullo): Explore performance of other data structures.
+  UnorderedMap<std::string, LockInfo> keys;
+};
+
+// Map of #num_stripes LockMapStripes
+struct LockMap {
+  explicit LockMap(size_t num_stripes,
+                   std::shared_ptr<TransactionDBMutexFactory> factory)
+      : num_stripes_(num_stripes) {
+    lock_map_stripes_.reserve(num_stripes);
+    for (size_t i = 0; i < num_stripes; i++) {
+      LockMapStripe* stripe = new LockMapStripe(factory);
+      lock_map_stripes_.push_back(stripe);
+    }
+  }
+
+  ~LockMap() {
+    for (auto stripe : lock_map_stripes_) {
+      delete stripe;
+    }
+  }
+
+  // Number of sepearate LockMapStripes to create, each with their own Mutex
+  const size_t num_stripes_;
+
+  // Count of keys that are currently locked in this column family.
+  // (Only maintained if PointLockManager::max_num_locks_ is positive.)
+  std::atomic<int64_t> lock_cnt{0};
+
+  std::vector<LockMapStripe*> lock_map_stripes_;
+
+  size_t GetStripe(const std::string& key) const;
+};
+
+namespace {
+void UnrefLockMapsCache(void* ptr) {
+  // Called when a thread exits or a ThreadLocalPtr gets destroyed.
+  auto lock_maps_cache =
+      static_cast<UnorderedMap<uint32_t, std::shared_ptr<LockMap>>*>(ptr);
+  delete lock_maps_cache;
+}
+}  // anonymous namespace
+
+PointLockManager::PointLockManager(PessimisticTransactionDB* txn_db,
+                                   const TransactionDBOptions& opt)
+    : txn_db_impl_(txn_db),
+      default_num_stripes_(opt.num_stripes),
+      max_num_locks_(opt.max_num_locks),
+      lock_maps_cache_(new ThreadLocalPtr(&UnrefLockMapsCache)),
+      dlock_buffer_(opt.max_num_deadlocks),
+      mutex_factory_(opt.custom_mutex_factory
+                         ? opt.custom_mutex_factory
+                         : std::make_shared<TransactionDBMutexFactoryImpl>()) {}
+
+size_t LockMap::GetStripe(const std::string& key) const {
+  assert(num_stripes_ > 0);
+  return FastRange64(GetSliceNPHash64(key), num_stripes_);
+}
+
+void PointLockManager::AddColumnFamily(const ColumnFamilyHandle* cf) {
+  InstrumentedMutexLock l(&lock_map_mutex_);
+
+  if (lock_maps_.find(cf->GetID()) == lock_maps_.end()) {
+    lock_maps_.emplace(cf->GetID(), std::make_shared<LockMap>(
+                                        default_num_stripes_, mutex_factory_));
+  } else {
+    // column_family already exists in lock map
+    assert(false);
+  }
+}
+
+void PointLockManager::RemoveColumnFamily(const ColumnFamilyHandle* cf) {
+  // Remove lock_map for this column family.  Since the lock map is stored
+  // as a shared ptr, concurrent transactions can still keep using it
+  // until they release their references to it.
+  {
+    InstrumentedMutexLock l(&lock_map_mutex_);
+
+    auto lock_maps_iter = lock_maps_.find(cf->GetID());
+    if (lock_maps_iter == lock_maps_.end()) {
+      return;
+    }
+
+    lock_maps_.erase(lock_maps_iter);
+  }  // lock_map_mutex_
+
+  // Clear all thread-local caches
+  autovector<void*> local_caches;
+  lock_maps_cache_->Scrape(&local_caches, nullptr);
+  for (auto cache : local_caches) {
+    delete static_cast<LockMaps*>(cache);
+  }
+}
+
+// Look up the LockMap std::shared_ptr for a given column_family_id.
+// Note:  The LockMap is only valid as long as the caller is still holding on
+//   to the returned std::shared_ptr.
+std::shared_ptr<LockMap> PointLockManager::GetLockMap(
+    ColumnFamilyId column_family_id) {
+  // First check thread-local cache
+  if (lock_maps_cache_->Get() == nullptr) {
+    lock_maps_cache_->Reset(new LockMaps());
+  }
+
+  auto lock_maps_cache = static_cast<LockMaps*>(lock_maps_cache_->Get());
+
+  auto lock_map_iter = lock_maps_cache->find(column_family_id);
+  if (lock_map_iter != lock_maps_cache->end()) {
+    // Found lock map for this column family.
+    return lock_map_iter->second;
+  }
+
+  // Not found in local cache, grab mutex and check shared LockMaps
+  InstrumentedMutexLock l(&lock_map_mutex_);
+
+  lock_map_iter = lock_maps_.find(column_family_id);
+  if (lock_map_iter == lock_maps_.end()) {
+    return std::shared_ptr<LockMap>(nullptr);
+  } else {
+    // Found lock map.  Store in thread-local cache and return.
+    std::shared_ptr<LockMap>& lock_map = lock_map_iter->second;
+    lock_maps_cache->insert({column_family_id, lock_map});
+
+    return lock_map;
+  }
+}
+
+// Returns true if this lock has expired and can be acquired by another
+// transaction.
+// If false, sets *expire_time to the expiration time of the lock according
+// to Env->GetMicros() or 0 if no expiration.
+bool PointLockManager::IsLockExpired(TransactionID txn_id,
+                                     const LockInfo& lock_info, Env* env,
+                                     uint64_t* expire_time) {
+  if (lock_info.expiration_time == 0) {
+    *expire_time = 0;
+    return false;
+  }
+
+  auto now = env->NowMicros();
+  bool expired = lock_info.expiration_time <= now;
+  if (!expired) {
+    // return how many microseconds until lock will be expired
+    *expire_time = lock_info.expiration_time;
+  } else {
+    for (auto id : lock_info.txn_ids) {
+      if (txn_id == id) {
+        continue;
+      }
+
+      bool success = txn_db_impl_->TryStealingExpiredTransactionLocks(id);
+      if (!success) {
+        expired = false;
+        *expire_time = 0;
+        break;
+      }
+    }
+  }
+
+  return expired;
+}
+
+Status PointLockManager::TryLock(PessimisticTransaction* txn,
+                                 ColumnFamilyId column_family_id,
+                                 const std::string& key, Env* env,
+                                 bool exclusive) {
+  // Lookup lock map for this column family id
+  std::shared_ptr<LockMap> lock_map_ptr = GetLockMap(column_family_id);
+  LockMap* lock_map = lock_map_ptr.get();
+  if (lock_map == nullptr) {
+    char msg[255];
+    snprintf(msg, sizeof(msg), "Column family id not found: %" PRIu32,
+             column_family_id);
+
+    return Status::InvalidArgument(msg);
+  }
+
+  // Need to lock the mutex for the stripe that this key hashes to
+  size_t stripe_num = lock_map->GetStripe(key);
+  assert(lock_map->lock_map_stripes_.size() > stripe_num);
+  LockMapStripe* stripe = lock_map->lock_map_stripes_.at(stripe_num);
+
+  LockInfo lock_info(txn->GetID(), txn->GetExpirationTime(), exclusive);
+  int64_t timeout = txn->GetLockTimeout();
+
+  return AcquireWithTimeout(txn, lock_map, stripe, column_family_id, key, env,
+                            timeout, lock_info);
+}
+
+// Helper function for TryLock().
+Status PointLockManager::AcquireWithTimeout(
+    PessimisticTransaction* txn, LockMap* lock_map, LockMapStripe* stripe,
+    ColumnFamilyId column_family_id, const std::string& key, Env* env,
+    int64_t timeout, const LockInfo& lock_info) {
+  Status result;
+  uint64_t end_time = 0;
+
+  if (timeout > 0) {
+    uint64_t start_time = env->NowMicros();
+    end_time = start_time + timeout;
+  }
+
+  if (timeout < 0) {
+    // If timeout is negative, we wait indefinitely to acquire the lock
+    result = stripe->stripe_mutex->Lock();
+  } else {
+    result = stripe->stripe_mutex->TryLockFor(timeout);
+  }
+
+  if (!result.ok()) {
+    // failed to acquire mutex
+    return result;
+  }
+
+  // Acquire lock if we are able to
+  uint64_t expire_time_hint = 0;
+  autovector<TransactionID> wait_ids;
+  result = AcquireLocked(lock_map, stripe, key, env, lock_info,
+                         &expire_time_hint, &wait_ids);
+
+  if (!result.ok() && timeout != 0) {
+    PERF_TIMER_GUARD(key_lock_wait_time);
+    PERF_COUNTER_ADD(key_lock_wait_count, 1);
+    // If we weren't able to acquire the lock, we will keep retrying as long
+    // as the timeout allows.
+    bool timed_out = false;
+    do {
+      // Decide how long to wait
+      int64_t cv_end_time = -1;
+      if (expire_time_hint > 0 && end_time > 0) {
+        cv_end_time = std::min(expire_time_hint, end_time);
+      } else if (expire_time_hint > 0) {
+        cv_end_time = expire_time_hint;
+      } else if (end_time > 0) {
+        cv_end_time = end_time;
+      }
+
+      assert(result.IsBusy() || wait_ids.size() != 0);
+
+      // We are dependent on a transaction to finish, so perform deadlock
+      // detection.
+      if (wait_ids.size() != 0) {
+        if (txn->IsDeadlockDetect()) {
+          if (IncrementWaiters(txn, wait_ids, key, column_family_id,
+                               lock_info.exclusive, env)) {
+            result = Status::Busy(Status::SubCode::kDeadlock);
+            stripe->stripe_mutex->UnLock();
+            return result;
+          }
+        }
+        txn->SetWaitingTxn(wait_ids, column_family_id, &key);
+      }
+
+      TEST_SYNC_POINT("PointLockManager::AcquireWithTimeout:WaitingTxn");
+      if (cv_end_time < 0) {
+        // Wait indefinitely
+        result = stripe->stripe_cv->Wait(stripe->stripe_mutex);
+      } else {
+        uint64_t now = env->NowMicros();
+        if (static_cast<uint64_t>(cv_end_time) > now) {
+          result = stripe->stripe_cv->WaitFor(stripe->stripe_mutex,
+                                              cv_end_time - now);
+        }
+      }
+
+      if (wait_ids.size() != 0) {
+        txn->ClearWaitingTxn();
+        if (txn->IsDeadlockDetect()) {
+          DecrementWaiters(txn, wait_ids);
+        }
+      }
+
+      if (result.IsTimedOut()) {
+        timed_out = true;
+        // Even though we timed out, we will still make one more attempt to
+        // acquire lock below (it is possible the lock expired and we
+        // were never signaled).
+      }
+
+      if (result.ok() || result.IsTimedOut()) {
+        result = AcquireLocked(lock_map, stripe, key, env, lock_info,
+                               &expire_time_hint, &wait_ids);
+      }
+    } while (!result.ok() && !timed_out);
+  }
+
+  stripe->stripe_mutex->UnLock();
+
+  return result;
+}
+
+void PointLockManager::DecrementWaiters(
+    const PessimisticTransaction* txn,
+    const autovector<TransactionID>& wait_ids) {
+  std::lock_guard<std::mutex> lock(wait_txn_map_mutex_);
+  DecrementWaitersImpl(txn, wait_ids);
+}
+
+void PointLockManager::DecrementWaitersImpl(
+    const PessimisticTransaction* txn,
+    const autovector<TransactionID>& wait_ids) {
+  auto id = txn->GetID();
+  assert(wait_txn_map_.Contains(id));
+  wait_txn_map_.Delete(id);
+
+  for (auto wait_id : wait_ids) {
+    rev_wait_txn_map_.Get(wait_id)--;
+    if (rev_wait_txn_map_.Get(wait_id) == 0) {
+      rev_wait_txn_map_.Delete(wait_id);
+    }
+  }
+}
+
+bool PointLockManager::IncrementWaiters(
+    const PessimisticTransaction* txn,
+    const autovector<TransactionID>& wait_ids, const std::string& key,
+    const uint32_t& cf_id, const bool& exclusive, Env* const env) {
+  auto id = txn->GetID();
+  std::vector<int> queue_parents(
+      static_cast<size_t>(txn->GetDeadlockDetectDepth()));
+  std::vector<TransactionID> queue_values(
+      static_cast<size_t>(txn->GetDeadlockDetectDepth()));
+  std::lock_guard<std::mutex> lock(wait_txn_map_mutex_);
+  assert(!wait_txn_map_.Contains(id));
+
+  wait_txn_map_.Insert(id, {wait_ids, cf_id, exclusive, key});
+
+  for (auto wait_id : wait_ids) {
+    if (rev_wait_txn_map_.Contains(wait_id)) {
+      rev_wait_txn_map_.Get(wait_id)++;
+    } else {
+      rev_wait_txn_map_.Insert(wait_id, 1);
+    }
+  }
+
+  // No deadlock if nobody is waiting on self.
+  if (!rev_wait_txn_map_.Contains(id)) {
+    return false;
+  }
+
+  const auto* next_ids = &wait_ids;
+  int parent = -1;
+  int64_t deadlock_time = 0;
+  for (int tail = 0, head = 0; head < txn->GetDeadlockDetectDepth(); head++) {
+    int i = 0;
+    if (next_ids) {
+      for (; i < static_cast<int>(next_ids->size()) &&
+             tail + i < txn->GetDeadlockDetectDepth();
+           i++) {
+        queue_values[tail + i] = (*next_ids)[i];
+        queue_parents[tail + i] = parent;
+      }
+      tail += i;
+    }
+
+    // No more items in the list, meaning no deadlock.
+    if (tail == head) {
+      return false;
+    }
+
+    auto next = queue_values[head];
+    if (next == id) {
+      std::vector<DeadlockInfo> path;
+      while (head != -1) {
+        assert(wait_txn_map_.Contains(queue_values[head]));
+
+        auto extracted_info = wait_txn_map_.Get(queue_values[head]);
+        path.push_back({queue_values[head], extracted_info.m_cf_id,
+                        extracted_info.m_exclusive,
+                        extracted_info.m_waiting_key});
+        head = queue_parents[head];
+      }
+      if (!env->GetCurrentTime(&deadlock_time).ok()) {
+        /*
+          TODO(AR) this preserves the current behaviour whilst checking the
+          status of env->GetCurrentTime to ensure that ASSERT_STATUS_CHECKED
+          passes. Should we instead raise an error if !ok() ?
+        */
+        deadlock_time = 0;
+      }
+      std::reverse(path.begin(), path.end());
+      dlock_buffer_.AddNewPath(DeadlockPath(path, deadlock_time));
+      deadlock_time = 0;
+      DecrementWaitersImpl(txn, wait_ids);
+      return true;
+    } else if (!wait_txn_map_.Contains(next)) {
+      next_ids = nullptr;
+      continue;
+    } else {
+      parent = head;
+      next_ids = &(wait_txn_map_.Get(next).m_neighbors);
+    }
+  }
+
+  // Wait cycle too big, just assume deadlock.
+  if (!env->GetCurrentTime(&deadlock_time).ok()) {
+    /*
+      TODO(AR) this preserves the current behaviour whilst checking the status
+      of env->GetCurrentTime to ensure that ASSERT_STATUS_CHECKED passes.
+      Should we instead raise an error if !ok() ?
+    */
+    deadlock_time = 0;
+  }
+  dlock_buffer_.AddNewPath(DeadlockPath(deadlock_time, true));
+  DecrementWaitersImpl(txn, wait_ids);
+  return true;
+}
+
+// Try to lock this key after we have acquired the mutex.
+// Sets *expire_time to the expiration time in microseconds
+//  or 0 if no expiration.
+// REQUIRED:  Stripe mutex must be held.
+Status PointLockManager::AcquireLocked(LockMap* lock_map, LockMapStripe* stripe,
+                                       const std::string& key, Env* env,
+                                       const LockInfo& txn_lock_info,
+                                       uint64_t* expire_time,
+                                       autovector<TransactionID>* txn_ids) {
+  assert(txn_lock_info.txn_ids.size() == 1);
+
+  Status result;
+  // Check if this key is already locked
+  auto stripe_iter = stripe->keys.find(key);
+  if (stripe_iter != stripe->keys.end()) {
+    // Lock already held
+    LockInfo& lock_info = stripe_iter->second;
+    assert(lock_info.txn_ids.size() == 1 || !lock_info.exclusive);
+
+    if (lock_info.exclusive || txn_lock_info.exclusive) {
+      if (lock_info.txn_ids.size() == 1 &&
+          lock_info.txn_ids[0] == txn_lock_info.txn_ids[0]) {
+        // The list contains one txn and we're it, so just take it.
+        lock_info.exclusive = txn_lock_info.exclusive;
+        lock_info.expiration_time = txn_lock_info.expiration_time;
+      } else {
+        // Check if it's expired. Skips over txn_lock_info.txn_ids[0] in case
+        // it's there for a shared lock with multiple holders which was not
+        // caught in the first case.
+        if (IsLockExpired(txn_lock_info.txn_ids[0], lock_info, env,
+                          expire_time)) {
+          // lock is expired, can steal it
+          lock_info.txn_ids = txn_lock_info.txn_ids;
+          lock_info.exclusive = txn_lock_info.exclusive;
+          lock_info.expiration_time = txn_lock_info.expiration_time;
+          // lock_cnt does not change
+        } else {
+          result = Status::TimedOut(Status::SubCode::kLockTimeout);
+          *txn_ids = lock_info.txn_ids;
+        }
+      }
+    } else {
+      // We are requesting shared access to a shared lock, so just grant it.
+      lock_info.txn_ids.push_back(txn_lock_info.txn_ids[0]);
+      // Using std::max means that expiration time never goes down even when
+      // a transaction is removed from the list. The correct solution would be
+      // to track expiry for every transaction, but this would also work for
+      // now.
+      lock_info.expiration_time =
+          std::max(lock_info.expiration_time, txn_lock_info.expiration_time);
+    }
+  } else {  // Lock not held.
+    // Check lock limit
+    if (max_num_locks_ > 0 &&
+        lock_map->lock_cnt.load(std::memory_order_acquire) >= max_num_locks_) {
+      result = Status::Busy(Status::SubCode::kLockLimit);
+    } else {
+      // acquire lock
+      stripe->keys.emplace(key, txn_lock_info);
+
+      // Maintain lock count if there is a limit on the number of locks
+      if (max_num_locks_) {
+        lock_map->lock_cnt++;
+      }
+    }
+  }
+
+  return result;
+}
+
+void PointLockManager::UnLockKey(PessimisticTransaction* txn,
+                                 const std::string& key, LockMapStripe* stripe,
+                                 LockMap* lock_map, Env* env) {
+#ifdef NDEBUG
+  (void)env;
+#endif
+  TransactionID txn_id = txn->GetID();
+
+  auto stripe_iter = stripe->keys.find(key);
+  if (stripe_iter != stripe->keys.end()) {
+    auto& txns = stripe_iter->second.txn_ids;
+    auto txn_it = std::find(txns.begin(), txns.end(), txn_id);
+    // Found the key we locked.  unlock it.
+    if (txn_it != txns.end()) {
+      if (txns.size() == 1) {
+        stripe->keys.erase(stripe_iter);
+      } else {
+        auto last_it = txns.end() - 1;
+        if (txn_it != last_it) {
+          *txn_it = *last_it;
+        }
+        txns.pop_back();
+      }
+
+      if (max_num_locks_ > 0) {
+        // Maintain lock count if there is a limit on the number of locks.
+        assert(lock_map->lock_cnt.load(std::memory_order_relaxed) > 0);
+        lock_map->lock_cnt--;
+      }
+    }
+  } else {
+    // This key is either not locked or locked by someone else.  This should
+    // only happen if the unlocking transaction has expired.
+    assert(txn->GetExpirationTime() > 0 &&
+           txn->GetExpirationTime() < env->NowMicros());
+  }
+}
+
+void PointLockManager::UnLock(PessimisticTransaction* txn,
+                              ColumnFamilyId column_family_id,
+                              const std::string& key, Env* env) {
+  std::shared_ptr<LockMap> lock_map_ptr = GetLockMap(column_family_id);
+  LockMap* lock_map = lock_map_ptr.get();
+  if (lock_map == nullptr) {
+    // Column Family must have been dropped.
+    return;
+  }
+
+  // Lock the mutex for the stripe that this key hashes to
+  size_t stripe_num = lock_map->GetStripe(key);
+  assert(lock_map->lock_map_stripes_.size() > stripe_num);
+  LockMapStripe* stripe = lock_map->lock_map_stripes_.at(stripe_num);
+
+  stripe->stripe_mutex->Lock().PermitUncheckedError();
+  UnLockKey(txn, key, stripe, lock_map, env);
+  stripe->stripe_mutex->UnLock();
+
+  // Signal waiting threads to retry locking
+  stripe->stripe_cv->NotifyAll();
+}
+
+void PointLockManager::UnLock(PessimisticTransaction* txn,
+                              const LockTracker& tracker, Env* env) {
+  std::unique_ptr<LockTracker::ColumnFamilyIterator> cf_it(
+      tracker.GetColumnFamilyIterator());
+  assert(cf_it != nullptr);
+  while (cf_it->HasNext()) {
+    ColumnFamilyId cf = cf_it->Next();
+    std::shared_ptr<LockMap> lock_map_ptr = GetLockMap(cf);
+    LockMap* lock_map = lock_map_ptr.get();
+    if (!lock_map) {
+      // Column Family must have been dropped.
+      return;
+    }
+
+    // Bucket keys by lock_map_ stripe
+    UnorderedMap<size_t, std::vector<const std::string*>> keys_by_stripe(
+        lock_map->num_stripes_);
+    std::unique_ptr<LockTracker::KeyIterator> key_it(
+        tracker.GetKeyIterator(cf));
+    assert(key_it != nullptr);
+    while (key_it->HasNext()) {
+      const std::string& key = key_it->Next();
+      size_t stripe_num = lock_map->GetStripe(key);
+      keys_by_stripe[stripe_num].push_back(&key);
+    }
+
+    // For each stripe, grab the stripe mutex and unlock all keys in this stripe
+    for (auto& stripe_iter : keys_by_stripe) {
+      size_t stripe_num = stripe_iter.first;
+      auto& stripe_keys = stripe_iter.second;
+
+      assert(lock_map->lock_map_stripes_.size() > stripe_num);
+      LockMapStripe* stripe = lock_map->lock_map_stripes_.at(stripe_num);
+
+      stripe->stripe_mutex->Lock().PermitUncheckedError();
+
+      for (const std::string* key : stripe_keys) {
+        UnLockKey(txn, *key, stripe, lock_map, env);
+      }
+
+      stripe->stripe_mutex->UnLock();
+
+      // Signal waiting threads to retry locking
+      stripe->stripe_cv->NotifyAll();
+    }
+  }
+}
+
+PointLockManager::PointLockStatus PointLockManager::GetPointLockStatus() {
+  PointLockStatus data;
+  // Lock order here is important. The correct order is lock_map_mutex_, then
+  // for every column family ID in ascending order lock every stripe in
+  // ascending order.
+  InstrumentedMutexLock l(&lock_map_mutex_);
+
+  std::vector<uint32_t> cf_ids;
+  for (const auto& map : lock_maps_) {
+    cf_ids.push_back(map.first);
+  }
+  std::sort(cf_ids.begin(), cf_ids.end());
+
+  for (auto i : cf_ids) {
+    const auto& stripes = lock_maps_[i]->lock_map_stripes_;
+    // Iterate and lock all stripes in ascending order.
+    for (const auto& j : stripes) {
+      j->stripe_mutex->Lock().PermitUncheckedError();
+      for (const auto& it : j->keys) {
+        struct KeyLockInfo info;
+        info.exclusive = it.second.exclusive;
+        info.key = it.first;
+        for (const auto& id : it.second.txn_ids) {
+          info.ids.push_back(id);
+        }
+        data.insert({i, info});
+      }
+    }
+  }
+
+  // Unlock everything. Unlocking order is not important.
+  for (auto i : cf_ids) {
+    const auto& stripes = lock_maps_[i]->lock_map_stripes_;
+    for (const auto& j : stripes) {
+      j->stripe_mutex->UnLock();
+    }
+  }
+
+  return data;
+}
+
+std::vector<DeadlockPath> PointLockManager::GetDeadlockInfoBuffer() {
+  return dlock_buffer_.PrepareBuffer();
+}
+
+void PointLockManager::Resize(uint32_t target_size) {
+  dlock_buffer_.Resize(target_size);
+}
+
+PointLockManager::RangeLockStatus PointLockManager::GetRangeLockStatus() {
+  return {};
+}
+
+Status PointLockManager::TryLock(PessimisticTransaction* /* txn */,
+                                 ColumnFamilyId /* cf_id */,
+                                 const Endpoint& /* start */,
+                                 const Endpoint& /* end */, Env* /* env */,
+                                 bool /* exclusive */) {
+  return Status::NotSupported(
+      "PointLockManager does not support range locking");
+}
+
+void PointLockManager::UnLock(PessimisticTransaction* /* txn */,
+                              ColumnFamilyId /* cf_id */,
+                              const Endpoint& /* start */,
+                              const Endpoint& /* end */, Env* /* env */) {
+  // no-op
+}
+
+}  // namespace ROCKSDB_NAMESPACE
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/point/point_lock_manager.h b/src/rocksdb/utilities/transactions/lock/point/point_lock_manager.h
new file mode 100644
index 000000000..eeb34f3be
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/point/point_lock_manager.h
@@ -0,0 +1,224 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+#ifndef ROCKSDB_LITE
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+#include <utility>
+#include <vector>
+
+#include "monitoring/instrumented_mutex.h"
+#include "rocksdb/utilities/transaction.h"
+#include "util/autovector.h"
+#include "util/hash_containers.h"
+#include "util/hash_map.h"
+#include "util/thread_local.h"
+#include "utilities/transactions/lock/lock_manager.h"
+#include "utilities/transactions/lock/point/point_lock_tracker.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class ColumnFamilyHandle;
+struct LockInfo;
+struct LockMap;
+struct LockMapStripe;
+
+template <class Path>
+class DeadlockInfoBufferTempl {
+ private:
+  std::vector<Path> paths_buffer_;
+  uint32_t buffer_idx_;
+  std::mutex paths_buffer_mutex_;
+
+  std::vector<Path> Normalize() {
+    auto working = paths_buffer_;
+
+    if (working.empty()) {
+      return working;
+    }
+
+    // Next write occurs at a nonexistent path's slot
+    if (paths_buffer_[buffer_idx_].empty()) {
+      working.resize(buffer_idx_);
+    } else {
+      std::rotate(working.begin(), working.begin() + buffer_idx_,
+                  working.end());
+    }
+
+    return working;
+  }
+
+ public:
+  explicit DeadlockInfoBufferTempl(uint32_t n_latest_dlocks)
+      : paths_buffer_(n_latest_dlocks), buffer_idx_(0) {}
+
+  void AddNewPath(Path path) {
+    std::lock_guard<std::mutex> lock(paths_buffer_mutex_);
+
+    if (paths_buffer_.empty()) {
+      return;
+    }
+
+    paths_buffer_[buffer_idx_] = std::move(path);
+    buffer_idx_ = (buffer_idx_ + 1) % paths_buffer_.size();
+  }
+
+  void Resize(uint32_t target_size) {
+    std::lock_guard<std::mutex> lock(paths_buffer_mutex_);
+
+    paths_buffer_ = Normalize();
+
+    // Drop the deadlocks that will no longer be needed ater the normalize
+    if (target_size < paths_buffer_.size()) {
+      paths_buffer_.erase(
+          paths_buffer_.begin(),
+          paths_buffer_.begin() + (paths_buffer_.size() - target_size));
+      buffer_idx_ = 0;
+    }
+    // Resize the buffer to the target size and restore the buffer's idx
+    else {
+      auto prev_size = paths_buffer_.size();
+      paths_buffer_.resize(target_size);
+      buffer_idx_ = (uint32_t)prev_size;
+    }
+  }
+
+  std::vector<Path> PrepareBuffer() {
+    std::lock_guard<std::mutex> lock(paths_buffer_mutex_);
+
+    // Reversing the normalized vector returns the latest deadlocks first
+    auto working = Normalize();
+    std::reverse(working.begin(), working.end());
+
+    return working;
+  }
+};
+
+using DeadlockInfoBuffer = DeadlockInfoBufferTempl<DeadlockPath>;
+
+struct TrackedTrxInfo {
+  autovector<TransactionID> m_neighbors;
+  uint32_t m_cf_id;
+  bool m_exclusive;
+  std::string m_waiting_key;
+};
+
+class PointLockManager : public LockManager {
+ public:
+  PointLockManager(PessimisticTransactionDB* db,
+                   const TransactionDBOptions& opt);
+  // No copying allowed
+  PointLockManager(const PointLockManager&) = delete;
+  PointLockManager& operator=(const PointLockManager&) = delete;
+
+  ~PointLockManager() override {}
+
+  bool IsPointLockSupported() const override { return true; }
+
+  bool IsRangeLockSupported() const override { return false; }
+
+  const LockTrackerFactory& GetLockTrackerFactory() const override {
+    return PointLockTrackerFactory::Get();
+  }
+
+  // Creates a new LockMap for this column family.  Caller should guarantee
+  // that this column family does not already exist.
+  void AddColumnFamily(const ColumnFamilyHandle* cf) override;
+  // Deletes the LockMap for this column family.  Caller should guarantee that
+  // this column family is no longer in use.
+  void RemoveColumnFamily(const ColumnFamilyHandle* cf) override;
+
+  Status TryLock(PessimisticTransaction* txn, ColumnFamilyId column_family_id,
+                 const std::string& key, Env* env, bool exclusive) override;
+  Status TryLock(PessimisticTransaction* txn, ColumnFamilyId column_family_id,
+                 const Endpoint& start, const Endpoint& end, Env* env,
+                 bool exclusive) override;
+
+  void UnLock(PessimisticTransaction* txn, const LockTracker& tracker,
+              Env* env) override;
+  void UnLock(PessimisticTransaction* txn, ColumnFamilyId column_family_id,
+              const std::string& key, Env* env) override;
+  void UnLock(PessimisticTransaction* txn, ColumnFamilyId column_family_id,
+              const Endpoint& start, const Endpoint& end, Env* env) override;
+
+  PointLockStatus GetPointLockStatus() override;
+
+  RangeLockStatus GetRangeLockStatus() override;
+
+  std::vector<DeadlockPath> GetDeadlockInfoBuffer() override;
+
+  void Resize(uint32_t new_size) override;
+
+ private:
+  PessimisticTransactionDB* txn_db_impl_;
+
+  // Default number of lock map stripes per column family
+  const size_t default_num_stripes_;
+
+  // Limit on number of keys locked per column family
+  const int64_t max_num_locks_;
+
+  // The following lock order must be satisfied in order to avoid deadlocking
+  // ourselves.
+  //   - lock_map_mutex_
+  //   - stripe mutexes in ascending cf id, ascending stripe order
+  //   - wait_txn_map_mutex_
+  //
+  // Must be held when accessing/modifying lock_maps_.
+  InstrumentedMutex lock_map_mutex_;
+
+  // Map of ColumnFamilyId to locked key info
+  using LockMaps = UnorderedMap<uint32_t, std::shared_ptr<LockMap>>;
+  LockMaps lock_maps_;
+
+  // Thread-local cache of entries in lock_maps_.  This is an optimization
+  // to avoid acquiring a mutex in order to look up a LockMap
+  std::unique_ptr<ThreadLocalPtr> lock_maps_cache_;
+
+  // Must be held when modifying wait_txn_map_ and rev_wait_txn_map_.
+  std::mutex wait_txn_map_mutex_;
+
+  // Maps from waitee -> number of waiters.
+  HashMap<TransactionID, int> rev_wait_txn_map_;
+  // Maps from waiter -> waitee.
+  HashMap<TransactionID, TrackedTrxInfo> wait_txn_map_;
+  DeadlockInfoBuffer dlock_buffer_;
+
+  // Used to allocate mutexes/condvars to use when locking keys
+  std::shared_ptr<TransactionDBMutexFactory> mutex_factory_;
+
+  bool IsLockExpired(TransactionID txn_id, const LockInfo& lock_info, Env* env,
+                     uint64_t* wait_time);
+
+  std::shared_ptr<LockMap> GetLockMap(uint32_t column_family_id);
+
+  Status AcquireWithTimeout(PessimisticTransaction* txn, LockMap* lock_map,
+                            LockMapStripe* stripe, uint32_t column_family_id,
+                            const std::string& key, Env* env, int64_t timeout,
+                            const LockInfo& lock_info);
+
+  Status AcquireLocked(LockMap* lock_map, LockMapStripe* stripe,
+                       const std::string& key, Env* env,
+                       const LockInfo& lock_info, uint64_t* wait_time,
+                       autovector<TransactionID>* txn_ids);
+
+  void UnLockKey(PessimisticTransaction* txn, const std::string& key,
+                 LockMapStripe* stripe, LockMap* lock_map, Env* env);
+
+  bool IncrementWaiters(const PessimisticTransaction* txn,
+                        const autovector<TransactionID>& wait_ids,
+                        const std::string& key, const uint32_t& cf_id,
+                        const bool& exclusive, Env* const env);
+  void DecrementWaiters(const PessimisticTransaction* txn,
+                        const autovector<TransactionID>& wait_ids);
+  void DecrementWaitersImpl(const PessimisticTransaction* txn,
+                            const autovector<TransactionID>& wait_ids);
+};
+
+}  // namespace ROCKSDB_NAMESPACE
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/point/point_lock_manager_test.cc b/src/rocksdb/utilities/transactions/lock/point/point_lock_manager_test.cc
new file mode 100644
index 000000000..525fdea71
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/point/point_lock_manager_test.cc
@@ -0,0 +1,181 @@
+//  Copyright (c) 2020-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#ifndef ROCKSDB_LITE
+
+#include "utilities/transactions/lock/point/point_lock_manager_test.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+// This test is not applicable for Range Lock manager as Range Lock Manager
+// operates on Column Families, not their ids.
+TEST_F(PointLockManagerTest, LockNonExistingColumnFamily) {
+  MockColumnFamilyHandle cf(1024);
+  locker_->RemoveColumnFamily(&cf);
+  auto txn = NewTxn();
+  auto s = locker_->TryLock(txn, 1024, "k", env_, true);
+  ASSERT_TRUE(s.IsInvalidArgument());
+  ASSERT_STREQ(s.getState(), "Column family id not found: 1024");
+  delete txn;
+}
+
+TEST_F(PointLockManagerTest, LockStatus) {
+  MockColumnFamilyHandle cf1(1024), cf2(2048);
+  locker_->AddColumnFamily(&cf1);
+  locker_->AddColumnFamily(&cf2);
+
+  auto txn1 = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn1, 1024, "k1", env_, true));
+  ASSERT_OK(locker_->TryLock(txn1, 2048, "k1", env_, true));
+
+  auto txn2 = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn2, 1024, "k2", env_, false));
+  ASSERT_OK(locker_->TryLock(txn2, 2048, "k2", env_, false));
+
+  auto s = locker_->GetPointLockStatus();
+  ASSERT_EQ(s.size(), 4u);
+  for (uint32_t cf_id : {1024, 2048}) {
+    ASSERT_EQ(s.count(cf_id), 2u);
+    auto range = s.equal_range(cf_id);
+    for (auto it = range.first; it != range.second; it++) {
+      ASSERT_TRUE(it->second.key == "k1" || it->second.key == "k2");
+      if (it->second.key == "k1") {
+        ASSERT_EQ(it->second.exclusive, true);
+        ASSERT_EQ(it->second.ids.size(), 1u);
+        ASSERT_EQ(it->second.ids[0], txn1->GetID());
+      } else if (it->second.key == "k2") {
+        ASSERT_EQ(it->second.exclusive, false);
+        ASSERT_EQ(it->second.ids.size(), 1u);
+        ASSERT_EQ(it->second.ids[0], txn2->GetID());
+      }
+    }
+  }
+
+  // Cleanup
+  locker_->UnLock(txn1, 1024, "k1", env_);
+  locker_->UnLock(txn1, 2048, "k1", env_);
+  locker_->UnLock(txn2, 1024, "k2", env_);
+  locker_->UnLock(txn2, 2048, "k2", env_);
+
+  delete txn1;
+  delete txn2;
+}
+
+TEST_F(PointLockManagerTest, UnlockExclusive) {
+  MockColumnFamilyHandle cf(1);
+  locker_->AddColumnFamily(&cf);
+
+  auto txn1 = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn1, 1, "k", env_, true));
+  locker_->UnLock(txn1, 1, "k", env_);
+
+  auto txn2 = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn2, 1, "k", env_, true));
+
+  // Cleanup
+  locker_->UnLock(txn2, 1, "k", env_);
+
+  delete txn1;
+  delete txn2;
+}
+
+TEST_F(PointLockManagerTest, UnlockShared) {
+  MockColumnFamilyHandle cf(1);
+  locker_->AddColumnFamily(&cf);
+
+  auto txn1 = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn1, 1, "k", env_, false));
+  locker_->UnLock(txn1, 1, "k", env_);
+
+  auto txn2 = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn2, 1, "k", env_, true));
+
+  // Cleanup
+  locker_->UnLock(txn2, 1, "k", env_);
+
+  delete txn1;
+  delete txn2;
+}
+
+// This test doesn't work with Range Lock Manager, because Range Lock Manager
+// doesn't support deadlock_detect_depth.
+
+TEST_F(PointLockManagerTest, DeadlockDepthExceeded) {
+  // Tests that when detecting deadlock, if the detection depth is exceeded,
+  // it's also viewed as deadlock.
+  MockColumnFamilyHandle cf(1);
+  locker_->AddColumnFamily(&cf);
+  TransactionOptions txn_opt;
+  txn_opt.deadlock_detect = true;
+  txn_opt.deadlock_detect_depth = 1;
+  txn_opt.lock_timeout = 1000000;
+  auto txn1 = NewTxn(txn_opt);
+  auto txn2 = NewTxn(txn_opt);
+  auto txn3 = NewTxn(txn_opt);
+  auto txn4 = NewTxn(txn_opt);
+  // "a ->(k) b" means transaction a is waiting for transaction b to release
+  // the held lock on key k.
+  // txn4 ->(k3) -> txn3 ->(k2) txn2 ->(k1) txn1
+  // txn3's deadlock detection will exceed the detection depth 1,
+  // which will be viewed as a deadlock.
+  // NOTE:
+  // txn4 ->(k3) -> txn3 must be set up before
+  // txn3 ->(k2) -> txn2, because to trigger deadlock detection for txn3,
+  // it must have another txn waiting on it, which is txn4 in this case.
+  ASSERT_OK(locker_->TryLock(txn1, 1, "k1", env_, true));
+
+  port::Thread t1 = BlockUntilWaitingTxn(wait_sync_point_name_, [&]() {
+    ASSERT_OK(locker_->TryLock(txn2, 1, "k2", env_, true));
+    // block because txn1 is holding a lock on k1.
+    locker_->TryLock(txn2, 1, "k1", env_, true);
+  });
+
+  ASSERT_OK(locker_->TryLock(txn3, 1, "k3", env_, true));
+
+  port::Thread t2 = BlockUntilWaitingTxn(wait_sync_point_name_, [&]() {
+    // block because txn3 is holding a lock on k1.
+    locker_->TryLock(txn4, 1, "k3", env_, true);
+  });
+
+  auto s = locker_->TryLock(txn3, 1, "k2", env_, true);
+  ASSERT_TRUE(s.IsBusy());
+  ASSERT_EQ(s.subcode(), Status::SubCode::kDeadlock);
+
+  std::vector<DeadlockPath> deadlock_paths = locker_->GetDeadlockInfoBuffer();
+  ASSERT_EQ(deadlock_paths.size(), 1u);
+  ASSERT_TRUE(deadlock_paths[0].limit_exceeded);
+
+  locker_->UnLock(txn1, 1, "k1", env_);
+  locker_->UnLock(txn3, 1, "k3", env_);
+  t1.join();
+  t2.join();
+
+  delete txn4;
+  delete txn3;
+  delete txn2;
+  delete txn1;
+}
+
+INSTANTIATE_TEST_CASE_P(PointLockManager, AnyLockManagerTest,
+                        ::testing::Values(nullptr));
+
+}  // namespace ROCKSDB_NAMESPACE
+
+int main(int argc, char** argv) {
+  ROCKSDB_NAMESPACE::port::InstallStackTraceHandler();
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}
+
+#else
+#include <stdio.h>
+
+int main(int /*argc*/, char** /*argv*/) {
+  fprintf(stderr,
+          "SKIPPED because Transactions are not supported in ROCKSDB_LITE\n");
+  return 0;
+}
+
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/point/point_lock_manager_test.h b/src/rocksdb/utilities/transactions/lock/point/point_lock_manager_test.h
new file mode 100644
index 000000000..ca9f46bf9
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/point/point_lock_manager_test.h
@@ -0,0 +1,324 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include "file/file_util.h"
+#include "port/port.h"
+#include "port/stack_trace.h"
+#include "rocksdb/utilities/transaction_db.h"
+#include "test_util/testharness.h"
+#include "test_util/testutil.h"
+#include "utilities/transactions/lock/point/point_lock_manager.h"
+#include "utilities/transactions/pessimistic_transaction_db.h"
+#include "utilities/transactions/transaction_db_mutex_impl.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class MockColumnFamilyHandle : public ColumnFamilyHandle {
+ public:
+  explicit MockColumnFamilyHandle(ColumnFamilyId cf_id) : cf_id_(cf_id) {}
+
+  ~MockColumnFamilyHandle() override {}
+
+  const std::string& GetName() const override { return name_; }
+
+  ColumnFamilyId GetID() const override { return cf_id_; }
+
+  Status GetDescriptor(ColumnFamilyDescriptor*) override {
+    return Status::OK();
+  }
+
+  const Comparator* GetComparator() const override {
+    return BytewiseComparator();
+  }
+
+ private:
+  ColumnFamilyId cf_id_;
+  std::string name_ = "MockCF";
+};
+
+class PointLockManagerTest : public testing::Test {
+ public:
+  void SetUp() override {
+    env_ = Env::Default();
+    db_dir_ = test::PerThreadDBPath("point_lock_manager_test");
+    ASSERT_OK(env_->CreateDir(db_dir_));
+
+    Options opt;
+    opt.create_if_missing = true;
+    TransactionDBOptions txn_opt;
+    txn_opt.transaction_lock_timeout = 0;
+
+    ASSERT_OK(TransactionDB::Open(opt, txn_opt, db_dir_, &db_));
+
+    // CAUTION: This test creates a separate lock manager object (right, NOT
+    // the one that the TransactionDB is using!), and runs tests on it.
+    locker_.reset(new PointLockManager(
+        static_cast<PessimisticTransactionDB*>(db_), txn_opt));
+
+    wait_sync_point_name_ = "PointLockManager::AcquireWithTimeout:WaitingTxn";
+  }
+
+  void TearDown() override {
+    delete db_;
+    EXPECT_OK(DestroyDir(env_, db_dir_));
+  }
+
+  PessimisticTransaction* NewTxn(
+      TransactionOptions txn_opt = TransactionOptions()) {
+    Transaction* txn = db_->BeginTransaction(WriteOptions(), txn_opt);
+    return reinterpret_cast<PessimisticTransaction*>(txn);
+  }
+
+ protected:
+  Env* env_;
+  std::shared_ptr<LockManager> locker_;
+  const char* wait_sync_point_name_;
+  friend void PointLockManagerTestExternalSetup(PointLockManagerTest*);
+
+ private:
+  std::string db_dir_;
+  TransactionDB* db_;
+};
+
+using init_func_t = void (*)(PointLockManagerTest*);
+
+class AnyLockManagerTest : public PointLockManagerTest,
+                           public testing::WithParamInterface<init_func_t> {
+ public:
+  void SetUp() override {
+    // If a custom setup function was provided, use it. Otherwise, use what we
+    // have inherited.
+    auto init_func = GetParam();
+    if (init_func)
+      (*init_func)(this);
+    else
+      PointLockManagerTest::SetUp();
+  }
+};
+
+TEST_P(AnyLockManagerTest, ReentrantExclusiveLock) {
+  // Tests that a txn can acquire exclusive lock on the same key repeatedly.
+  MockColumnFamilyHandle cf(1);
+  locker_->AddColumnFamily(&cf);
+  auto txn = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn, 1, "k", env_, true));
+  ASSERT_OK(locker_->TryLock(txn, 1, "k", env_, true));
+
+  // Cleanup
+  locker_->UnLock(txn, 1, "k", env_);
+
+  delete txn;
+}
+
+TEST_P(AnyLockManagerTest, ReentrantSharedLock) {
+  // Tests that a txn can acquire shared lock on the same key repeatedly.
+  MockColumnFamilyHandle cf(1);
+  locker_->AddColumnFamily(&cf);
+  auto txn = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn, 1, "k", env_, false));
+  ASSERT_OK(locker_->TryLock(txn, 1, "k", env_, false));
+
+  // Cleanup
+  locker_->UnLock(txn, 1, "k", env_);
+
+  delete txn;
+}
+
+TEST_P(AnyLockManagerTest, LockUpgrade) {
+  // Tests that a txn can upgrade from a shared lock to an exclusive lock.
+  MockColumnFamilyHandle cf(1);
+  locker_->AddColumnFamily(&cf);
+  auto txn = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn, 1, "k", env_, false));
+  ASSERT_OK(locker_->TryLock(txn, 1, "k", env_, true));
+
+  // Cleanup
+  locker_->UnLock(txn, 1, "k", env_);
+  delete txn;
+}
+
+TEST_P(AnyLockManagerTest, LockDowngrade) {
+  // Tests that a txn can acquire a shared lock after acquiring an exclusive
+  // lock on the same key.
+  MockColumnFamilyHandle cf(1);
+  locker_->AddColumnFamily(&cf);
+  auto txn = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn, 1, "k", env_, true));
+  ASSERT_OK(locker_->TryLock(txn, 1, "k", env_, false));
+
+  // Cleanup
+  locker_->UnLock(txn, 1, "k", env_);
+  delete txn;
+}
+
+TEST_P(AnyLockManagerTest, LockConflict) {
+  // Tests that lock conflicts lead to lock timeout.
+  MockColumnFamilyHandle cf(1);
+  locker_->AddColumnFamily(&cf);
+  auto txn1 = NewTxn();
+  auto txn2 = NewTxn();
+
+  {
+    // exclusive-exclusive conflict.
+    ASSERT_OK(locker_->TryLock(txn1, 1, "k1", env_, true));
+    auto s = locker_->TryLock(txn2, 1, "k1", env_, true);
+    ASSERT_TRUE(s.IsTimedOut());
+  }
+
+  {
+    // exclusive-shared conflict.
+    ASSERT_OK(locker_->TryLock(txn1, 1, "k2", env_, true));
+    auto s = locker_->TryLock(txn2, 1, "k2", env_, false);
+    ASSERT_TRUE(s.IsTimedOut());
+  }
+
+  {
+    // shared-exclusive conflict.
+    ASSERT_OK(locker_->TryLock(txn1, 1, "k2", env_, false));
+    auto s = locker_->TryLock(txn2, 1, "k2", env_, true);
+    ASSERT_TRUE(s.IsTimedOut());
+  }
+
+  // Cleanup
+  locker_->UnLock(txn1, 1, "k1", env_);
+  locker_->UnLock(txn1, 1, "k2", env_);
+
+  delete txn1;
+  delete txn2;
+}
+
+port::Thread BlockUntilWaitingTxn(const char* sync_point_name,
+                                  std::function<void()> f) {
+  std::atomic<bool> reached(false);
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
+      sync_point_name, [&](void* /*arg*/) { reached.store(true); });
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing();
+
+  port::Thread t(f);
+
+  while (!reached.load()) {
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  }
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->DisableProcessing();
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->ClearAllCallBacks();
+
+  return t;
+}
+
+TEST_P(AnyLockManagerTest, SharedLocks) {
+  // Tests that shared locks can be concurrently held by multiple transactions.
+  MockColumnFamilyHandle cf(1);
+  locker_->AddColumnFamily(&cf);
+  auto txn1 = NewTxn();
+  auto txn2 = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn1, 1, "k", env_, false));
+  ASSERT_OK(locker_->TryLock(txn2, 1, "k", env_, false));
+
+  // Cleanup
+  locker_->UnLock(txn1, 1, "k", env_);
+  locker_->UnLock(txn2, 1, "k", env_);
+
+  delete txn1;
+  delete txn2;
+}
+
+TEST_P(AnyLockManagerTest, Deadlock) {
+  // Tests that deadlock can be detected.
+  // Deadlock scenario:
+  // txn1 exclusively locks k1, and wants to lock k2;
+  // txn2 exclusively locks k2, and wants to lock k1.
+  MockColumnFamilyHandle cf(1);
+  locker_->AddColumnFamily(&cf);
+  TransactionOptions txn_opt;
+  txn_opt.deadlock_detect = true;
+  txn_opt.lock_timeout = 1000000;
+  auto txn1 = NewTxn(txn_opt);
+  auto txn2 = NewTxn(txn_opt);
+
+  ASSERT_OK(locker_->TryLock(txn1, 1, "k1", env_, true));
+  ASSERT_OK(locker_->TryLock(txn2, 1, "k2", env_, true));
+
+  // txn1 tries to lock k2, will block forever.
+  port::Thread t = BlockUntilWaitingTxn(wait_sync_point_name_, [&]() {
+    // block because txn2 is holding a lock on k2.
+    locker_->TryLock(txn1, 1, "k2", env_, true);
+  });
+
+  auto s = locker_->TryLock(txn2, 1, "k1", env_, true);
+  ASSERT_TRUE(s.IsBusy());
+  ASSERT_EQ(s.subcode(), Status::SubCode::kDeadlock);
+
+  std::vector<DeadlockPath> deadlock_paths = locker_->GetDeadlockInfoBuffer();
+  ASSERT_EQ(deadlock_paths.size(), 1u);
+  ASSERT_FALSE(deadlock_paths[0].limit_exceeded);
+
+  std::vector<DeadlockInfo> deadlocks = deadlock_paths[0].path;
+  ASSERT_EQ(deadlocks.size(), 2u);
+
+  ASSERT_EQ(deadlocks[0].m_txn_id, txn1->GetID());
+  ASSERT_EQ(deadlocks[0].m_cf_id, 1u);
+  ASSERT_TRUE(deadlocks[0].m_exclusive);
+  ASSERT_EQ(deadlocks[0].m_waiting_key, "k2");
+
+  ASSERT_EQ(deadlocks[1].m_txn_id, txn2->GetID());
+  ASSERT_EQ(deadlocks[1].m_cf_id, 1u);
+  ASSERT_TRUE(deadlocks[1].m_exclusive);
+  ASSERT_EQ(deadlocks[1].m_waiting_key, "k1");
+
+  locker_->UnLock(txn2, 1, "k2", env_);
+  t.join();
+
+  // Cleanup
+  locker_->UnLock(txn1, 1, "k1", env_);
+  locker_->UnLock(txn1, 1, "k2", env_);
+  delete txn2;
+  delete txn1;
+}
+
+TEST_P(AnyLockManagerTest, GetWaitingTxns_MultipleTxns) {
+  MockColumnFamilyHandle cf(1);
+  locker_->AddColumnFamily(&cf);
+
+  auto txn1 = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn1, 1, "k", env_, false));
+
+  auto txn2 = NewTxn();
+  ASSERT_OK(locker_->TryLock(txn2, 1, "k", env_, false));
+
+  auto txn3 = NewTxn();
+  txn3->SetLockTimeout(10000);
+  port::Thread t1 = BlockUntilWaitingTxn(wait_sync_point_name_, [&]() {
+    ASSERT_OK(locker_->TryLock(txn3, 1, "k", env_, true));
+    locker_->UnLock(txn3, 1, "k", env_);
+  });
+
+  // Ok, now txn3 is waiting for lock on "k", which is owned by two
+  // transactions. Check that GetWaitingTxns reports this correctly
+  uint32_t wait_cf_id;
+  std::string wait_key;
+  auto waiters = txn3->GetWaitingTxns(&wait_cf_id, &wait_key);
+
+  ASSERT_EQ(wait_cf_id, 1u);
+  ASSERT_EQ(wait_key, "k");
+  ASSERT_EQ(waiters.size(), 2);
+  bool waits_correct =
+      (waiters[0] == txn1->GetID() && waiters[1] == txn2->GetID()) ||
+      (waiters[1] == txn1->GetID() && waiters[0] == txn2->GetID());
+  ASSERT_EQ(waits_correct, true);
+
+  // Release locks so txn3 can proceed with execution
+  locker_->UnLock(txn1, 1, "k", env_);
+  locker_->UnLock(txn2, 1, "k", env_);
+
+  // Wait until txn3 finishes
+  t1.join();
+
+  delete txn1;
+  delete txn2;
+  delete txn3;
+}
+
+}  // namespace ROCKSDB_NAMESPACE
diff --git a/src/rocksdb/utilities/transactions/lock/point/point_lock_tracker.cc b/src/rocksdb/utilities/transactions/lock/point/point_lock_tracker.cc
new file mode 100644
index 000000000..6204a8f02
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/point/point_lock_tracker.cc
@@ -0,0 +1,257 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+
+#ifndef ROCKSDB_LITE
+
+#include "utilities/transactions/lock/point/point_lock_tracker.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+namespace {
+
+class TrackedKeysColumnFamilyIterator
+    : public LockTracker::ColumnFamilyIterator {
+ public:
+  explicit TrackedKeysColumnFamilyIterator(const TrackedKeys& keys)
+      : tracked_keys_(keys), it_(keys.begin()) {}
+
+  bool HasNext() const override { return it_ != tracked_keys_.end(); }
+
+  ColumnFamilyId Next() override { return (it_++)->first; }
+
+ private:
+  const TrackedKeys& tracked_keys_;
+  TrackedKeys::const_iterator it_;
+};
+
+class TrackedKeysIterator : public LockTracker::KeyIterator {
+ public:
+  TrackedKeysIterator(const TrackedKeys& keys, ColumnFamilyId id)
+      : key_infos_(keys.at(id)), it_(key_infos_.begin()) {}
+
+  bool HasNext() const override { return it_ != key_infos_.end(); }
+
+  const std::string& Next() override { return (it_++)->first; }
+
+ private:
+  const TrackedKeyInfos& key_infos_;
+  TrackedKeyInfos::const_iterator it_;
+};
+
+}  // namespace
+
+void PointLockTracker::Track(const PointLockRequest& r) {
+  auto& keys = tracked_keys_[r.column_family_id];
+  auto result = keys.try_emplace(r.key, r.seq);
+  auto it = result.first;
+  if (!result.second && r.seq < it->second.seq) {
+    // Now tracking this key with an earlier sequence number
+    it->second.seq = r.seq;
+  }
+  // else we do not update the seq. The smaller the tracked seq, the stronger it
+  // the guarantee since it implies from the seq onward there has not been a
+  // concurrent update to the key. So we update the seq if it implies stronger
+  // guarantees, i.e., if it is smaller than the existing tracked seq.
+
+  if (r.read_only) {
+    it->second.num_reads++;
+  } else {
+    it->second.num_writes++;
+  }
+
+  it->second.exclusive = it->second.exclusive || r.exclusive;
+}
+
+UntrackStatus PointLockTracker::Untrack(const PointLockRequest& r) {
+  auto cf_keys = tracked_keys_.find(r.column_family_id);
+  if (cf_keys == tracked_keys_.end()) {
+    return UntrackStatus::NOT_TRACKED;
+  }
+
+  auto& keys = cf_keys->second;
+  auto it = keys.find(r.key);
+  if (it == keys.end()) {
+    return UntrackStatus::NOT_TRACKED;
+  }
+
+  bool untracked = false;
+  auto& info = it->second;
+  if (r.read_only) {
+    if (info.num_reads > 0) {
+      info.num_reads--;
+      untracked = true;
+    }
+  } else {
+    if (info.num_writes > 0) {
+      info.num_writes--;
+      untracked = true;
+    }
+  }
+
+  bool removed = false;
+  if (info.num_reads == 0 && info.num_writes == 0) {
+    keys.erase(it);
+    if (keys.empty()) {
+      tracked_keys_.erase(cf_keys);
+    }
+    removed = true;
+  }
+
+  if (removed) {
+    return UntrackStatus::REMOVED;
+  }
+  if (untracked) {
+    return UntrackStatus::UNTRACKED;
+  }
+  return UntrackStatus::NOT_TRACKED;
+}
+
+void PointLockTracker::Merge(const LockTracker& tracker) {
+  const PointLockTracker& t = static_cast<const PointLockTracker&>(tracker);
+  for (const auto& cf_keys : t.tracked_keys_) {
+    ColumnFamilyId cf = cf_keys.first;
+    const auto& keys = cf_keys.second;
+
+    auto current_cf_keys = tracked_keys_.find(cf);
+    if (current_cf_keys == tracked_keys_.end()) {
+      tracked_keys_.emplace(cf_keys);
+    } else {
+      auto& current_keys = current_cf_keys->second;
+      for (const auto& key_info : keys) {
+        const std::string& key = key_info.first;
+        const TrackedKeyInfo& info = key_info.second;
+        // If key was not previously tracked, just copy the whole struct over.
+        // Otherwise, some merging needs to occur.
+        auto current_info = current_keys.find(key);
+        if (current_info == current_keys.end()) {
+          current_keys.emplace(key_info);
+        } else {
+          current_info->second.Merge(info);
+        }
+      }
+    }
+  }
+}
+
+void PointLockTracker::Subtract(const LockTracker& tracker) {
+  const PointLockTracker& t = static_cast<const PointLockTracker&>(tracker);
+  for (const auto& cf_keys : t.tracked_keys_) {
+    ColumnFamilyId cf = cf_keys.first;
+    const auto& keys = cf_keys.second;
+
+    auto& current_keys = tracked_keys_.at(cf);
+    for (const auto& key_info : keys) {
+      const std::string& key = key_info.first;
+      const TrackedKeyInfo& info = key_info.second;
+      uint32_t num_reads = info.num_reads;
+      uint32_t num_writes = info.num_writes;
+
+      auto current_key_info = current_keys.find(key);
+      assert(current_key_info != current_keys.end());
+
+      // Decrement the total reads/writes of this key by the number of
+      // reads/writes done since the last SavePoint.
+      if (num_reads > 0) {
+        assert(current_key_info->second.num_reads >= num_reads);
+        current_key_info->second.num_reads -= num_reads;
+      }
+      if (num_writes > 0) {
+        assert(current_key_info->second.num_writes >= num_writes);
+        current_key_info->second.num_writes -= num_writes;
+      }
+      if (current_key_info->second.num_reads == 0 &&
+          current_key_info->second.num_writes == 0) {
+        current_keys.erase(current_key_info);
+      }
+    }
+  }
+}
+
+LockTracker* PointLockTracker::GetTrackedLocksSinceSavePoint(
+    const LockTracker& save_point_tracker) const {
+  // Examine the number of reads/writes performed on all keys written
+  // since the last SavePoint and compare to the total number of reads/writes
+  // for each key.
+  LockTracker* t = new PointLockTracker();
+  const PointLockTracker& save_point_t =
+      static_cast<const PointLockTracker&>(save_point_tracker);
+  for (const auto& cf_keys : save_point_t.tracked_keys_) {
+    ColumnFamilyId cf = cf_keys.first;
+    const auto& keys = cf_keys.second;
+
+    auto& current_keys = tracked_keys_.at(cf);
+    for (const auto& key_info : keys) {
+      const std::string& key = key_info.first;
+      const TrackedKeyInfo& info = key_info.second;
+      uint32_t num_reads = info.num_reads;
+      uint32_t num_writes = info.num_writes;
+
+      auto current_key_info = current_keys.find(key);
+      assert(current_key_info != current_keys.end());
+      assert(current_key_info->second.num_reads >= num_reads);
+      assert(current_key_info->second.num_writes >= num_writes);
+
+      if (current_key_info->second.num_reads == num_reads &&
+          current_key_info->second.num_writes == num_writes) {
+        // All the reads/writes to this key were done in the last savepoint.
+        PointLockRequest r;
+        r.column_family_id = cf;
+        r.key = key;
+        r.seq = info.seq;
+        r.read_only = (num_writes == 0);
+        r.exclusive = info.exclusive;
+        t->Track(r);
+      }
+    }
+  }
+  return t;
+}
+
+PointLockStatus PointLockTracker::GetPointLockStatus(
+    ColumnFamilyId column_family_id, const std::string& key) const {
+  assert(IsPointLockSupported());
+  PointLockStatus status;
+  auto it = tracked_keys_.find(column_family_id);
+  if (it == tracked_keys_.end()) {
+    return status;
+  }
+
+  const auto& keys = it->second;
+  auto key_it = keys.find(key);
+  if (key_it == keys.end()) {
+    return status;
+  }
+
+  const TrackedKeyInfo& key_info = key_it->second;
+  status.locked = true;
+  status.exclusive = key_info.exclusive;
+  status.seq = key_info.seq;
+  return status;
+}
+
+uint64_t PointLockTracker::GetNumPointLocks() const {
+  uint64_t num_keys = 0;
+  for (const auto& cf_keys : tracked_keys_) {
+    num_keys += cf_keys.second.size();
+  }
+  return num_keys;
+}
+
+LockTracker::ColumnFamilyIterator* PointLockTracker::GetColumnFamilyIterator()
+    const {
+  return new TrackedKeysColumnFamilyIterator(tracked_keys_);
+}
+
+LockTracker::KeyIterator* PointLockTracker::GetKeyIterator(
+    ColumnFamilyId column_family_id) const {
+  assert(tracked_keys_.find(column_family_id) != tracked_keys_.end());
+  return new TrackedKeysIterator(tracked_keys_, column_family_id);
+}
+
+void PointLockTracker::Clear() { tracked_keys_.clear(); }
+
+}  // namespace ROCKSDB_NAMESPACE
+
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/point/point_lock_tracker.h b/src/rocksdb/utilities/transactions/lock/point/point_lock_tracker.h
new file mode 100644
index 000000000..daf6f9aa2
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/point/point_lock_tracker.h
@@ -0,0 +1,99 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+#ifndef ROCKSDB_LITE
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+
+#include "utilities/transactions/lock/lock_tracker.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+struct TrackedKeyInfo {
+  // Earliest sequence number that is relevant to this transaction for this key
+  SequenceNumber seq;
+
+  uint32_t num_writes;
+  uint32_t num_reads;
+
+  bool exclusive;
+
+  explicit TrackedKeyInfo(SequenceNumber seq_no)
+      : seq(seq_no), num_writes(0), num_reads(0), exclusive(false) {}
+
+  void Merge(const TrackedKeyInfo& info) {
+    assert(seq <= info.seq);
+    num_reads += info.num_reads;
+    num_writes += info.num_writes;
+    exclusive = exclusive || info.exclusive;
+  }
+};
+
+using TrackedKeyInfos = std::unordered_map<std::string, TrackedKeyInfo>;
+
+using TrackedKeys = std::unordered_map<ColumnFamilyId, TrackedKeyInfos>;
+
+// Tracks point locks on single keys.
+class PointLockTracker : public LockTracker {
+ public:
+  PointLockTracker() = default;
+
+  PointLockTracker(const PointLockTracker&) = delete;
+  PointLockTracker& operator=(const PointLockTracker&) = delete;
+
+  bool IsPointLockSupported() const override { return true; }
+
+  bool IsRangeLockSupported() const override { return false; }
+
+  void Track(const PointLockRequest& lock_request) override;
+
+  UntrackStatus Untrack(const PointLockRequest& lock_request) override;
+
+  void Track(const RangeLockRequest& /*lock_request*/) override {}
+
+  UntrackStatus Untrack(const RangeLockRequest& /*lock_request*/) override {
+    return UntrackStatus::NOT_TRACKED;
+  }
+
+  void Merge(const LockTracker& tracker) override;
+
+  void Subtract(const LockTracker& tracker) override;
+
+  void Clear() override;
+
+  virtual LockTracker* GetTrackedLocksSinceSavePoint(
+      const LockTracker& save_point_tracker) const override;
+
+  PointLockStatus GetPointLockStatus(ColumnFamilyId column_family_id,
+                                     const std::string& key) const override;
+
+  uint64_t GetNumPointLocks() const override;
+
+  ColumnFamilyIterator* GetColumnFamilyIterator() const override;
+
+  KeyIterator* GetKeyIterator(ColumnFamilyId column_family_id) const override;
+
+ private:
+  TrackedKeys tracked_keys_;
+};
+
+class PointLockTrackerFactory : public LockTrackerFactory {
+ public:
+  static const PointLockTrackerFactory& Get() {
+    static const PointLockTrackerFactory instance;
+    return instance;
+  }
+
+  LockTracker* Create() const override { return new PointLockTracker(); }
+
+ private:
+  PointLockTrackerFactory() {}
+};
+
+}  // namespace ROCKSDB_NAMESPACE
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_lock_manager.h b/src/rocksdb/utilities/transactions/lock/range/range_lock_manager.h
new file mode 100644
index 000000000..01899542e
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_lock_manager.h
@@ -0,0 +1,36 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+//
+// Generic definitions for a Range-based Lock Manager
+//
+#pragma once
+#ifndef ROCKSDB_LITE
+
+#include "utilities/transactions/lock/lock_manager.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+/*
+  A base class for all Range-based lock managers
+
+  See also class RangeLockManagerHandle in
+  include/rocksdb/utilities/transaction_db.h
+*/
+class RangeLockManagerBase : public LockManager {
+ public:
+  // Geting a point lock is reduced to getting a range lock on a single-point
+  // range
+  using LockManager::TryLock;
+  Status TryLock(PessimisticTransaction* txn, ColumnFamilyId column_family_id,
+                 const std::string& key, Env* env, bool exclusive) override {
+    Endpoint endp(key.data(), key.size(), false);
+    return TryLock(txn, column_family_id, endp, endp, env, exclusive);
+  }
+};
+
+}  // namespace ROCKSDB_NAMESPACE
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_locking_test.cc b/src/rocksdb/utilities/transactions/lock/range/range_locking_test.cc
new file mode 100644
index 000000000..bce66c1f3
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_locking_test.cc
@@ -0,0 +1,459 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+
+#include <algorithm>
+#include <functional>
+#include <string>
+#include <thread>
+
+#include "db/db_impl/db_impl.h"
+#include "port/port.h"
+#include "rocksdb/db.h"
+#include "rocksdb/options.h"
+#include "rocksdb/perf_context.h"
+#include "rocksdb/utilities/transaction.h"
+#include "rocksdb/utilities/transaction_db.h"
+#include "utilities/transactions/lock/point/point_lock_manager_test.h"
+#include "utilities/transactions/pessimistic_transaction_db.h"
+#include "utilities/transactions/transaction_test.h"
+
+using std::string;
+
+namespace ROCKSDB_NAMESPACE {
+
+class RangeLockingTest : public ::testing::Test {
+ public:
+  TransactionDB* db;
+  std::string dbname;
+  Options options;
+
+  std::shared_ptr<RangeLockManagerHandle> range_lock_mgr;
+  TransactionDBOptions txn_db_options;
+
+  RangeLockingTest() : db(nullptr) {
+    options.create_if_missing = true;
+    dbname = test::PerThreadDBPath("range_locking_testdb");
+
+    EXPECT_OK(DestroyDB(dbname, options));
+
+    range_lock_mgr.reset(NewRangeLockManager(nullptr));
+    txn_db_options.lock_mgr_handle = range_lock_mgr;
+
+    auto s = TransactionDB::Open(options, txn_db_options, dbname, &db);
+    assert(s.ok());
+  }
+
+  ~RangeLockingTest() {
+    delete db;
+    db = nullptr;
+    // This is to skip the assert statement in FaultInjectionTestEnv. There
+    // seems to be a bug in btrfs that the makes readdir return recently
+    // unlink-ed files. By using the default fs we simply ignore errors resulted
+    // from attempting to delete such files in DestroyDB.
+    EXPECT_OK(DestroyDB(dbname, options));
+  }
+
+  PessimisticTransaction* NewTxn(
+      TransactionOptions txn_opt = TransactionOptions()) {
+    Transaction* txn = db->BeginTransaction(WriteOptions(), txn_opt);
+    return reinterpret_cast<PessimisticTransaction*>(txn);
+  }
+};
+
+// TODO: set a smaller lock wait timeout so that the test runs faster.
+TEST_F(RangeLockingTest, BasicRangeLocking) {
+  WriteOptions write_options;
+  TransactionOptions txn_options;
+  std::string value;
+  ReadOptions read_options;
+  auto cf = db->DefaultColumnFamily();
+
+  Transaction* txn0 = db->BeginTransaction(write_options, txn_options);
+  Transaction* txn1 = db->BeginTransaction(write_options, txn_options);
+
+  // Get a range lock
+  ASSERT_OK(txn0->GetRangeLock(cf, Endpoint("a"), Endpoint("c")));
+
+  // Check that range Lock inhibits an overlapping range lock
+  {
+    auto s = txn1->GetRangeLock(cf, Endpoint("b"), Endpoint("z"));
+    ASSERT_TRUE(s.IsTimedOut());
+  }
+
+  // Check that range Lock inhibits an overlapping point lock
+  {
+    auto s = txn1->GetForUpdate(read_options, cf, Slice("b"), &value);
+    ASSERT_TRUE(s.IsTimedOut());
+  }
+
+  // Get a point lock, check that it inhibits range locks
+  ASSERT_OK(txn0->Put(cf, Slice("n"), Slice("value")));
+  {
+    auto s = txn1->GetRangeLock(cf, Endpoint("m"), Endpoint("p"));
+    ASSERT_TRUE(s.IsTimedOut());
+  }
+
+  ASSERT_OK(txn0->Commit());
+  txn1->Rollback();
+
+  delete txn0;
+  delete txn1;
+}
+
+TEST_F(RangeLockingTest, MyRocksLikeUpdate) {
+  WriteOptions write_options;
+  TransactionOptions txn_options;
+  Transaction* txn0 = db->BeginTransaction(write_options, txn_options);
+  auto cf = db->DefaultColumnFamily();
+  Status s;
+
+  // Get a range lock for the range we are about to update
+  ASSERT_OK(txn0->GetRangeLock(cf, Endpoint("a"), Endpoint("c")));
+
+  bool try_range_lock_called = false;
+
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
+      "RangeTreeLockManager::TryRangeLock:enter",
+      [&](void* /*arg*/) { try_range_lock_called = true; });
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing();
+
+  // For performance reasons, the following must NOT call lock_mgr->TryLock():
+  // We verify that by checking the value of try_range_lock_called.
+  ASSERT_OK(txn0->Put(cf, Slice("b"), Slice("value"),
+                      /*assume_tracked=*/true));
+
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->DisableProcessing();
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->ClearAllCallBacks();
+  ASSERT_FALSE(try_range_lock_called);
+
+  txn0->Rollback();
+
+  delete txn0;
+}
+
+TEST_F(RangeLockingTest, UpgradeLockAndGetConflict) {
+  WriteOptions write_options;
+  TransactionOptions txn_options;
+  auto cf = db->DefaultColumnFamily();
+  Status s;
+  std::string value;
+  txn_options.lock_timeout = 10;
+
+  Transaction* txn0 = db->BeginTransaction(write_options, txn_options);
+  Transaction* txn1 = db->BeginTransaction(write_options, txn_options);
+
+  // Get the shared lock in txn0
+  s = txn0->GetForUpdate(ReadOptions(), cf, Slice("a"), &value,
+                         false /*exclusive*/);
+  ASSERT_TRUE(s.IsNotFound());
+
+  // Get the shared lock on the same key in txn1
+  s = txn1->GetForUpdate(ReadOptions(), cf, Slice("a"), &value,
+                         false /*exclusive*/);
+  ASSERT_TRUE(s.IsNotFound());
+
+  // Now, try getting an exclusive lock that overlaps with the above
+  s = txn0->GetRangeLock(cf, Endpoint("a"), Endpoint("b"));
+  ASSERT_TRUE(s.IsTimedOut());
+
+  txn0->Rollback();
+  txn1->Rollback();
+
+  delete txn0;
+  delete txn1;
+}
+
+TEST_F(RangeLockingTest, SnapshotValidation) {
+  Status s;
+  Slice key_slice = Slice("k");
+  ColumnFamilyHandle* cfh = db->DefaultColumnFamily();
+
+  auto txn0 = NewTxn();
+  txn0->Put(key_slice, Slice("initial"));
+  txn0->Commit();
+
+  // txn1
+  auto txn1 = NewTxn();
+  txn1->SetSnapshot();
+  std::string val1;
+  ASSERT_OK(txn1->Get(ReadOptions(), cfh, key_slice, &val1));
+  ASSERT_EQ(val1, "initial");
+  val1 = val1 + std::string("-txn1");
+
+  ASSERT_OK(txn1->Put(cfh, key_slice, Slice(val1)));
+
+  // txn2
+  auto txn2 = NewTxn();
+  txn2->SetSnapshot();
+  std::string val2;
+  // This will see the original value as nothing is committed
+  // This is also Get, so it is doesn't acquire any locks.
+  ASSERT_OK(txn2->Get(ReadOptions(), cfh, key_slice, &val2));
+  ASSERT_EQ(val2, "initial");
+
+  // txn1
+  ASSERT_OK(txn1->Commit());
+
+  // txn2
+  val2 = val2 + std::string("-txn2");
+  // Now, this call should do Snapshot Validation and fail:
+  s = txn2->Put(cfh, key_slice, Slice(val2));
+  ASSERT_TRUE(s.IsBusy());
+
+  ASSERT_OK(txn2->Commit());
+
+  delete txn0;
+  delete txn1;
+  delete txn2;
+}
+
+TEST_F(RangeLockingTest, MultipleTrxLockStatusData) {
+  WriteOptions write_options;
+  TransactionOptions txn_options;
+  auto cf = db->DefaultColumnFamily();
+
+  Transaction* txn0 = db->BeginTransaction(write_options, txn_options);
+  Transaction* txn1 = db->BeginTransaction(write_options, txn_options);
+
+  // Get a range lock
+  ASSERT_OK(txn0->GetRangeLock(cf, Endpoint("z"), Endpoint("z")));
+  ASSERT_OK(txn1->GetRangeLock(cf, Endpoint("b"), Endpoint("e")));
+
+  auto s = range_lock_mgr->GetRangeLockStatusData();
+  ASSERT_EQ(s.size(), 2);
+  for (auto it = s.begin(); it != s.end(); ++it) {
+    ASSERT_EQ(it->first, cf->GetID());
+    auto val = it->second;
+    ASSERT_FALSE(val.start.inf_suffix);
+    ASSERT_FALSE(val.end.inf_suffix);
+    ASSERT_TRUE(val.exclusive);
+    ASSERT_EQ(val.ids.size(), 1);
+    if (val.ids[0] == txn0->GetID()) {
+      ASSERT_EQ(val.start.slice, "z");
+      ASSERT_EQ(val.end.slice, "z");
+    } else if (val.ids[0] == txn1->GetID()) {
+      ASSERT_EQ(val.start.slice, "b");
+      ASSERT_EQ(val.end.slice, "e");
+    } else {
+      FAIL();  // Unknown transaction ID.
+    }
+  }
+
+  delete txn0;
+  delete txn1;
+}
+
+#if defined(__has_feature)
+#if __has_feature(thread_sanitizer)
+#define SKIP_LOCK_ESCALATION_TEST 1
+#endif
+#else
+#define SKIP_LOCK_ESCALATION_TEST 1
+#endif
+
+#ifndef SKIP_LOCK_ESCALATION_TEST
+TEST_F(RangeLockingTest, BasicLockEscalation) {
+  auto cf = db->DefaultColumnFamily();
+
+  auto counters = range_lock_mgr->GetStatus();
+
+  // Initially not using any lock memory
+  ASSERT_EQ(counters.current_lock_memory, 0);
+  ASSERT_EQ(counters.escalation_count, 0);
+
+  ASSERT_EQ(0, range_lock_mgr->SetMaxLockMemory(2000));
+
+  // Insert until we see lock escalations
+  auto txn = NewTxn();
+
+  // Get the locks until we hit an escalation
+  for (int i = 0; i < 2020; i++) {
+    std::ostringstream buf;
+    buf << std::setw(8) << std::setfill('0') << i;
+    std::string buf_str = buf.str();
+    ASSERT_OK(txn->GetRangeLock(cf, Endpoint(buf_str), Endpoint(buf_str)));
+  }
+  counters = range_lock_mgr->GetStatus();
+  ASSERT_GT(counters.escalation_count, 0);
+  ASSERT_LE(counters.current_lock_memory, 2000);
+
+  delete txn;
+}
+
+// An escalation barrier function. Allow escalation iff the first two bytes are
+// identical.
+static bool escalation_barrier(const Endpoint& a, const Endpoint& b) {
+  assert(a.slice.size() > 2);
+  assert(b.slice.size() > 2);
+  if (memcmp(a.slice.data(), b.slice.data(), 2)) {
+    return true;  // This is a barrier
+  } else {
+    return false;  // No barrier
+  }
+}
+
+TEST_F(RangeLockingTest, LockEscalationBarrier) {
+  auto cf = db->DefaultColumnFamily();
+
+  auto counters = range_lock_mgr->GetStatus();
+
+  // Initially not using any lock memory
+  ASSERT_EQ(counters.escalation_count, 0);
+
+  range_lock_mgr->SetMaxLockMemory(8000);
+  range_lock_mgr->SetEscalationBarrierFunc(escalation_barrier);
+
+  // Insert enough locks to cause lock escalations to happen
+  auto txn = NewTxn();
+  const int N = 2000;
+  for (int i = 0; i < N; i++) {
+    std::ostringstream buf;
+    buf << std::setw(4) << std::setfill('0') << i;
+    std::string buf_str = buf.str();
+    ASSERT_OK(txn->GetRangeLock(cf, Endpoint(buf_str), Endpoint(buf_str)));
+  }
+  counters = range_lock_mgr->GetStatus();
+  ASSERT_GT(counters.escalation_count, 0);
+
+  // Check that lock escalation was not performed across escalation barriers:
+  // Use another txn to acquire locks near the barriers.
+  auto txn2 = NewTxn();
+  range_lock_mgr->SetMaxLockMemory(500000);
+  for (int i = 100; i < N; i += 100) {
+    std::ostringstream buf;
+    buf << std::setw(4) << std::setfill('0') << i - 1 << "-a";
+    std::string buf_str = buf.str();
+    // Check that we CAN get a lock near the escalation barrier
+    ASSERT_OK(txn2->GetRangeLock(cf, Endpoint(buf_str), Endpoint(buf_str)));
+  }
+
+  txn->Rollback();
+  txn2->Rollback();
+  delete txn;
+  delete txn2;
+}
+
+#endif
+
+TEST_F(RangeLockingTest, LockWaitCount) {
+  TransactionOptions txn_options;
+  auto cf = db->DefaultColumnFamily();
+  txn_options.lock_timeout = 50;
+  Transaction* txn0 = db->BeginTransaction(WriteOptions(), txn_options);
+  Transaction* txn1 = db->BeginTransaction(WriteOptions(), txn_options);
+
+  // Get a range lock
+  ASSERT_OK(txn0->GetRangeLock(cf, Endpoint("a"), Endpoint("c")));
+
+  uint64_t lock_waits1 = range_lock_mgr->GetStatus().lock_wait_count;
+  // Attempt to get a conflicting lock
+  auto s = txn1->GetRangeLock(cf, Endpoint("b"), Endpoint("z"));
+  ASSERT_TRUE(s.IsTimedOut());
+
+  // Check that the counter was incremented
+  uint64_t lock_waits2 = range_lock_mgr->GetStatus().lock_wait_count;
+  ASSERT_EQ(lock_waits1 + 1, lock_waits2);
+
+  txn0->Rollback();
+  txn1->Rollback();
+
+  delete txn0;
+  delete txn1;
+}
+
+TEST_F(RangeLockingTest, LockWaiteeAccess) {
+  TransactionOptions txn_options;
+  auto cf = db->DefaultColumnFamily();
+  txn_options.lock_timeout = 60;
+  Transaction* txn0 = db->BeginTransaction(WriteOptions(), txn_options);
+  Transaction* txn1 = db->BeginTransaction(WriteOptions(), txn_options);
+
+  // Get a range lock
+  ASSERT_OK(txn0->GetRangeLock(cf, Endpoint("a"), Endpoint("c")));
+
+  std::atomic<bool> reached(false);
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
+      "RangeTreeLockManager::TryRangeLock:EnterWaitingTxn", [&](void* /*arg*/) {
+        reached.store(true);
+        std::this_thread::sleep_for(std::chrono::milliseconds(2000));
+      });
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing();
+
+  port::Thread t([&]() {
+    // Attempt to get a conflicting lock
+    auto s = txn1->GetRangeLock(cf, Endpoint("b"), Endpoint("z"));
+    ASSERT_TRUE(s.ok());
+    txn1->Rollback();
+  });
+
+  while (!reached.load()) {
+    std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  }
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->DisableProcessing();
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->ClearAllCallBacks();
+
+  // Release locks and free the transaction
+  txn0->Rollback();
+  delete txn0;
+
+  t.join();
+
+  delete txn1;
+}
+
+void PointLockManagerTestExternalSetup(PointLockManagerTest* self) {
+  self->env_ = Env::Default();
+  self->db_dir_ = test::PerThreadDBPath("point_lock_manager_test");
+  ASSERT_OK(self->env_->CreateDir(self->db_dir_));
+
+  Options opt;
+  opt.create_if_missing = true;
+  TransactionDBOptions txn_opt;
+  txn_opt.transaction_lock_timeout = 0;
+
+  auto mutex_factory = std::make_shared<TransactionDBMutexFactoryImpl>();
+  self->locker_.reset(NewRangeLockManager(mutex_factory)->getLockManager());
+  std::shared_ptr<RangeLockManagerHandle> range_lock_mgr =
+      std::dynamic_pointer_cast<RangeLockManagerHandle>(self->locker_);
+  txn_opt.lock_mgr_handle = range_lock_mgr;
+
+  ASSERT_OK(TransactionDB::Open(opt, txn_opt, self->db_dir_, &self->db_));
+  self->wait_sync_point_name_ = "RangeTreeLockManager::TryRangeLock:WaitingTxn";
+}
+
+INSTANTIATE_TEST_CASE_P(RangeLockManager, AnyLockManagerTest,
+                        ::testing::Values(PointLockManagerTestExternalSetup));
+
+}  // namespace ROCKSDB_NAMESPACE
+
+int main(int argc, char** argv) {
+  ROCKSDB_NAMESPACE::port::InstallStackTraceHandler();
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}
+
+#else  // OS_WIN
+
+#include <stdio.h>
+int main(int /*argc*/, char** /*argv*/) {
+  fprintf(stderr, "skipped as Range Locking is not supported on Windows\n");
+  return 0;
+}
+
+#endif  // OS_WIN
+
+#else
+#include <stdio.h>
+
+int main(int /*argc*/, char** /*argv*/) {
+  fprintf(stderr,
+          "skipped as transactions are not supported in rocksdb_lite\n");
+  return 0;
+}
+
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/COPYING.AGPLv3 b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/COPYING.AGPLv3
new file mode 100644
index 000000000..dba13ed2d
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/COPYING.AGPLv3
@@ -0,0 +1,661 @@
+                    GNU AFFERO GENERAL PUBLIC LICENSE
+                       Version 3, 19 November 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <http://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
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+software and other kinds of works, specifically designed to ensure
+cooperation with the community in the case of network server software.
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diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/COPYING.APACHEv2 b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/COPYING.APACHEv2
new file mode 100644
index 000000000..ecbfc770f
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/COPYING.APACHEv2
@@ -0,0 +1,174 @@
+Apache License
+                           Version 2.0, January 2004
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+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
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diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/COPYING.GPLv2 b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/COPYING.GPLv2
new file mode 100644
index 000000000..d511905c1
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/COPYING.GPLv2
@@ -0,0 +1,339 @@
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+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+  9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Program
+specifies a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+			    NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+		     END OF TERMS AND CONDITIONS
+
+	    How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/README b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/README
new file mode 100644
index 000000000..2ea86bf46
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/README
@@ -0,0 +1,13 @@
+The files in this directory originally come from
+https://github.com/percona/PerconaFT/.
+
+This directory only includes the "locktree" part of PerconaFT, and its
+dependencies.
+
+The following modifications were made:
+- Make locktree usable outside of PerconaFT library
+- Add shared read-only lock support
+
+The files named *_subst.* are substitutes of the PerconaFT's files, they
+contain replacements of PerconaFT's functionality.
+
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/db.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/db.h
new file mode 100644
index 000000000..5aa826c8e
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/db.h
@@ -0,0 +1,76 @@
+#ifndef _DB_H
+#define _DB_H
+
+#include <stdint.h>
+#include <sys/types.h>
+
+typedef struct __toku_dbt DBT;
+
+// port: this is currently not used
+struct simple_dbt {
+  uint32_t len;
+  void *data;
+};
+
+// engine status info
+// engine status is passed to handlerton as an array of
+// TOKU_ENGINE_STATUS_ROW_S[]
+typedef enum {
+  STATUS_FS_STATE = 0,  // interpret as file system state (redzone) enum
+  STATUS_UINT64,        // interpret as uint64_t
+  STATUS_CHARSTR,       // interpret as char *
+  STATUS_UNIXTIME,      // interpret as time_t
+  STATUS_TOKUTIME,      // interpret as tokutime_t
+  STATUS_PARCOUNT,      // interpret as PARTITIONED_COUNTER
+  STATUS_DOUBLE         // interpret as double
+} toku_engine_status_display_type;
+
+typedef enum {
+  TOKU_ENGINE_STATUS = (1ULL << 0),  // Include when asking for engine status
+  TOKU_GLOBAL_STATUS =
+      (1ULL << 1),  // Include when asking for information_schema.global_status
+} toku_engine_status_include_type;
+
+typedef struct __toku_engine_status_row {
+  const char *keyname;  // info schema key, should not change across revisions
+                        // without good reason
+  const char
+      *columnname;  // column for mysql, e.g. information_schema.global_status.
+                    // TOKUDB_ will automatically be prefixed.
+  const char *legend;  // the text that will appear at user interface
+  toku_engine_status_display_type type;  // how to interpret the value
+  toku_engine_status_include_type
+      include;  // which kinds of callers should get read this row?
+  union {
+    double dnum;
+    uint64_t num;
+    const char *str;
+    char datebuf[26];
+    struct partitioned_counter *parcount;
+  } value;
+} * TOKU_ENGINE_STATUS_ROW, TOKU_ENGINE_STATUS_ROW_S;
+
+#define DB_BUFFER_SMALL -30999
+#define DB_LOCK_DEADLOCK -30995
+#define DB_LOCK_NOTGRANTED -30994
+#define DB_NOTFOUND -30989
+#define DB_KEYEXIST -30996
+#define DB_DBT_MALLOC 8
+#define DB_DBT_REALLOC 64
+#define DB_DBT_USERMEM 256
+
+/* PerconaFT specific error codes */
+#define TOKUDB_OUT_OF_LOCKS -100000
+
+typedef void (*lock_wait_callback)(void *arg, uint64_t requesting_txnid,
+                                   uint64_t blocking_txnid);
+
+struct __toku_dbt {
+  void *data;
+  size_t size;
+  size_t ulen;
+  // One of DB_DBT_XXX flags
+  uint32_t flags;
+};
+
+#endif
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/ft/comparator.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/ft/comparator.h
new file mode 100644
index 000000000..718efc623
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/ft/comparator.h
@@ -0,0 +1,138 @@
+/* -*- mode: C; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include <string.h>
+
+#include "../db.h"
+#include "../portability/memory.h"
+#include "../util/dbt.h"
+
+typedef int (*ft_compare_func)(void *arg, const DBT *a, const DBT *b);
+
+int toku_keycompare(const void *key1, size_t key1len, const void *key2,
+                    size_t key2len);
+
+int toku_builtin_compare_fun(const DBT *, const DBT *)
+    __attribute__((__visibility__("default")));
+
+namespace toku {
+
+// a comparator object encapsulates the data necessary for
+// comparing two keys in a fractal tree. it further understands
+// that points may be positive or negative infinity.
+
+class comparator {
+  void init(ft_compare_func cmp, void *cmp_arg, uint8_t memcmp_magic) {
+    _cmp = cmp;
+    _cmp_arg = cmp_arg;
+    _memcmp_magic = memcmp_magic;
+  }
+
+ public:
+  // This magic value is reserved to mean that the magic has not been set.
+  static const uint8_t MEMCMP_MAGIC_NONE = 0;
+
+  void create(ft_compare_func cmp, void *cmp_arg,
+              uint8_t memcmp_magic = MEMCMP_MAGIC_NONE) {
+    init(cmp, cmp_arg, memcmp_magic);
+  }
+
+  // inherit the attributes of another comparator, but keep our own
+  // copy of fake_db that is owned separately from the one given.
+  void inherit(const comparator &cmp) {
+    invariant_notnull(cmp._cmp);
+    init(cmp._cmp, cmp._cmp_arg, cmp._memcmp_magic);
+  }
+
+  // like inherit, but doesn't require that the this comparator
+  // was already created
+  void create_from(const comparator &cmp) { inherit(cmp); }
+
+  void destroy() {}
+
+  ft_compare_func get_compare_func() const { return _cmp; }
+
+  uint8_t get_memcmp_magic() const { return _memcmp_magic; }
+
+  bool valid() const { return _cmp != nullptr; }
+
+  inline bool dbt_has_memcmp_magic(const DBT *dbt) const {
+    return *reinterpret_cast<const char *>(dbt->data) == _memcmp_magic;
+  }
+
+  int operator()(const DBT *a, const DBT *b) const {
+    if (__builtin_expect(toku_dbt_is_infinite(a) || toku_dbt_is_infinite(b),
+                         0)) {
+      return toku_dbt_infinite_compare(a, b);
+    } else if (_memcmp_magic != MEMCMP_MAGIC_NONE
+               // If `a' has the memcmp magic..
+               && dbt_has_memcmp_magic(a)
+               // ..then we expect `b' to also have the memcmp magic
+               && __builtin_expect(dbt_has_memcmp_magic(b), 1)) {
+      assert(0);  // psergey: this branch should not be taken.
+      return toku_builtin_compare_fun(a, b);
+    } else {
+      // yikes, const sadness here
+      return _cmp(_cmp_arg, a, b);
+    }
+  }
+
+ private:
+  ft_compare_func _cmp;
+  void *_cmp_arg;
+
+  uint8_t _memcmp_magic;
+};
+
+} /* namespace toku */
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/ft/ft-status.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/ft/ft-status.h
new file mode 100644
index 000000000..1b4511172
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/ft/ft-status.h
@@ -0,0 +1,102 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include "../db.h"
+#include "../portability/toku_race_tools.h"
+#include "../util/status.h"
+
+//
+// Lock Tree Manager statistics
+//
+class LTM_STATUS_S {
+ public:
+  enum {
+    LTM_SIZE_CURRENT = 0,
+    LTM_SIZE_LIMIT,
+    LTM_ESCALATION_COUNT,
+    LTM_ESCALATION_TIME,
+    LTM_ESCALATION_LATEST_RESULT,
+    LTM_NUM_LOCKTREES,
+    LTM_LOCK_REQUESTS_PENDING,
+    LTM_STO_NUM_ELIGIBLE,
+    LTM_STO_END_EARLY_COUNT,
+    LTM_STO_END_EARLY_TIME,
+    LTM_WAIT_COUNT,
+    LTM_WAIT_TIME,
+    LTM_LONG_WAIT_COUNT,
+    LTM_LONG_WAIT_TIME,
+    LTM_TIMEOUT_COUNT,
+    LTM_WAIT_ESCALATION_COUNT,
+    LTM_WAIT_ESCALATION_TIME,
+    LTM_LONG_WAIT_ESCALATION_COUNT,
+    LTM_LONG_WAIT_ESCALATION_TIME,
+    LTM_STATUS_NUM_ROWS  // must be last
+  };
+
+  void init(void);
+  void destroy(void);
+
+  TOKU_ENGINE_STATUS_ROW_S status[LTM_STATUS_NUM_ROWS];
+
+ private:
+  bool m_initialized = false;
+};
+typedef LTM_STATUS_S* LTM_STATUS;
+extern LTM_STATUS_S ltm_status;
+
+#define LTM_STATUS_VAL(x) ltm_status.status[LTM_STATUS_S::x].value.num
+
+void toku_status_init(void);     // just call ltm_status.init();
+void toku_status_destroy(void);  // just call ltm_status.destroy();
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/concurrent_tree.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/concurrent_tree.cc
new file mode 100644
index 000000000..5110cd482
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/concurrent_tree.cc
@@ -0,0 +1,139 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include "concurrent_tree.h"
+
+// PORT #include <toku_assert.h>
+namespace toku {
+
+void concurrent_tree::create(const comparator *cmp) {
+  // start with an empty root node. we do this instead of
+  // setting m_root to null so there's always a root to lock
+  m_root.create_root(cmp);
+}
+
+void concurrent_tree::destroy(void) { m_root.destroy_root(); }
+
+bool concurrent_tree::is_empty(void) { return m_root.is_empty(); }
+
+uint64_t concurrent_tree::get_insertion_memory_overhead(void) {
+  return sizeof(treenode);
+}
+
+void concurrent_tree::locked_keyrange::prepare(concurrent_tree *tree) {
+  // the first step in acquiring a locked keyrange is locking the root
+  treenode *const root = &tree->m_root;
+  m_tree = tree;
+  m_subtree = root;
+  m_range = keyrange::get_infinite_range();
+  root->mutex_lock();
+}
+
+void concurrent_tree::locked_keyrange::acquire(const keyrange &range) {
+  treenode *const root = &m_tree->m_root;
+
+  treenode *subtree;
+  if (root->is_empty() || root->range_overlaps(range)) {
+    subtree = root;
+  } else {
+    // we do not have a precomputed comparison hint, so pass null
+    const keyrange::comparison *cmp_hint = nullptr;
+    subtree = root->find_node_with_overlapping_child(range, cmp_hint);
+  }
+
+  // subtree is locked. it will be unlocked when this is release()'d
+  invariant_notnull(subtree);
+  m_range = range;
+  m_subtree = subtree;
+}
+
+bool concurrent_tree::locked_keyrange::add_shared_owner(const keyrange &range,
+                                                        TXNID new_owner) {
+  return m_subtree->insert(range, new_owner, /*is_shared*/ true);
+}
+
+void concurrent_tree::locked_keyrange::release(void) {
+  m_subtree->mutex_unlock();
+}
+
+void concurrent_tree::locked_keyrange::insert(const keyrange &range,
+                                              TXNID txnid, bool is_shared) {
+  // empty means no children, and only the root should ever be empty
+  if (m_subtree->is_empty()) {
+    m_subtree->set_range_and_txnid(range, txnid, is_shared);
+  } else {
+    m_subtree->insert(range, txnid, is_shared);
+  }
+}
+
+void concurrent_tree::locked_keyrange::remove(const keyrange &range,
+                                              TXNID txnid) {
+  invariant(!m_subtree->is_empty());
+  treenode *new_subtree = m_subtree->remove(range, txnid);
+  // if removing range changed the root of the subtree,
+  // then the subtree must be the root of the entire tree.
+  if (new_subtree == nullptr) {
+    invariant(m_subtree->is_root());
+    invariant(m_subtree->is_empty());
+  }
+}
+
+void concurrent_tree::locked_keyrange::remove_all(void) {
+  m_subtree->recursive_remove();
+}
+
+} /* namespace toku */
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/concurrent_tree.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/concurrent_tree.h
new file mode 100644
index 000000000..e1bfb86c5
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/concurrent_tree.h
@@ -0,0 +1,174 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=2:softtabstop=2:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include "../ft/comparator.h"
+#include "keyrange.h"
+#include "treenode.h"
+
+namespace toku {
+
+// A concurrent_tree stores non-overlapping ranges.
+// Access to disjoint parts of the tree usually occurs concurrently.
+
+class concurrent_tree {
+ public:
+  // A locked_keyrange gives you exclusive access to read and write
+  // operations that occur on any keys in that range. You only have
+  // the right to operate on keys in that range or keys that were read
+  // from the keyrange using iterate()
+  //
+  // Access model:
+  // - user prepares a locked keyrange. all threads serialize behind prepare().
+  // - user breaks the serialzation point by acquiring a range, or releasing.
+  // - one thread operates on a certain locked_keyrange object at a time.
+  // - when the thread is finished, it releases
+
+  class locked_keyrange {
+   public:
+    // effect: prepare to acquire a locked keyrange over the given
+    //         concurrent_tree, preventing other threads from preparing
+    //         until this thread either does acquire() or release().
+    // note: operations performed on a prepared keyrange are equivalent
+    //         to ones performed on an acquired keyrange over -inf, +inf.
+    // rationale: this provides the user with a serialization point for
+    // descending
+    //            or modifying the the tree. it also proives a convenient way of
+    //            doing serializable operations on the tree.
+    // There are two valid sequences of calls:
+    //  - prepare, acquire, [operations], release
+    //  - prepare, [operations],release
+    void prepare(concurrent_tree *tree);
+
+    // requires: the locked keyrange was prepare()'d
+    // effect: acquire a locked keyrange over the given concurrent_tree.
+    //         the locked keyrange represents the range of keys overlapped
+    //         by the given range
+    void acquire(const keyrange &range);
+
+    // effect: releases a locked keyrange and the mutex it holds
+    void release(void);
+
+    // effect: iterate over each range this locked_keyrange represents,
+    //         calling function->fn() on each node's keyrange and txnid
+    //         until there are no more or the function returns false
+    template <class F>
+    void iterate(F *function) const {
+      // if the subtree is non-empty, traverse it by calling the given
+      // function on each range, txnid pair found that overlaps.
+      if (!m_subtree->is_empty()) {
+        m_subtree->traverse_overlaps(m_range, function);
+      }
+    }
+
+    // Adds another owner to the lock on the specified keyrange.
+    // requires: the keyrange contains one treenode whose bounds are
+    //           exactly equal to the specifed range (no sub/supersets)
+    bool add_shared_owner(const keyrange &range, TXNID new_owner);
+
+    // inserts the given range into the tree, with an associated txnid.
+    // requires: range does not overlap with anything in this locked_keyrange
+    // rationale: caller is responsible for only inserting unique ranges
+    void insert(const keyrange &range, TXNID txnid, bool is_shared);
+
+    // effect: removes the given range from the tree.
+    //         - txnid=TXNID_ANY means remove the range no matter what its
+    //           owners are
+    //         - Other value means remove the specified txnid from
+    //           ownership (if the range has other owners, it will remain
+    //           in the tree)
+    // requires: range exists exactly in this locked_keyrange
+    // rationale: caller is responsible for only removing existing ranges
+    void remove(const keyrange &range, TXNID txnid);
+
+    // effect: removes all of the keys represented by this locked keyrange
+    // rationale: we'd like a fast way to empty out a tree
+    void remove_all(void);
+
+   private:
+    // the concurrent tree this locked keyrange is for
+    concurrent_tree *m_tree;
+
+    // the range of keys this locked keyrange represents
+    keyrange m_range;
+
+    // the subtree under which all overlapping ranges exist
+    treenode *m_subtree;
+
+    friend class concurrent_tree_unit_test;
+  };
+
+  // effect: initialize the tree to an empty state
+  void create(const comparator *cmp);
+
+  // effect: destroy the tree.
+  // requires: tree is empty
+  void destroy(void);
+
+  // returns: true iff the tree is empty
+  bool is_empty(void);
+
+  // returns: the memory overhead of a single insertion into the tree
+  static uint64_t get_insertion_memory_overhead(void);
+
+ private:
+  // the root needs to always exist so there's a lock to grab
+  // even if the tree is empty. that's why we store a treenode
+  // here and not a pointer to one.
+  treenode m_root;
+
+  friend class concurrent_tree_unit_test;
+};
+
+} /* namespace toku */
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/keyrange.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/keyrange.cc
new file mode 100644
index 000000000..e50ace5a9
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/keyrange.cc
@@ -0,0 +1,222 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include "keyrange.h"
+
+#include "../util/dbt.h"
+
+namespace toku {
+
+// create a keyrange by borrowing the left and right dbt
+// pointers. no memory is copied. no checks for infinity needed.
+void keyrange::create(const DBT *left, const DBT *right) {
+  init_empty();
+  m_left_key = left;
+  m_right_key = right;
+}
+
+// destroy the key copies. if they were never set, then destroy does nothing.
+void keyrange::destroy(void) {
+  toku_destroy_dbt(&m_left_key_copy);
+  toku_destroy_dbt(&m_right_key_copy);
+}
+
+// create a keyrange by copying the keys from the given range.
+void keyrange::create_copy(const keyrange &range) {
+  // start with an initialized, empty range
+  init_empty();
+
+  // optimize the case where the left and right keys are the same.
+  // we'd like to only have one copy of the data.
+  if (toku_dbt_equals(range.get_left_key(), range.get_right_key())) {
+    set_both_keys(range.get_left_key());
+  } else {
+    // replace our empty left and right keys with
+    // copies of the range's left and right keys
+    replace_left_key(range.get_left_key());
+    replace_right_key(range.get_right_key());
+  }
+}
+
+// extend this keyrange by choosing the leftmost and rightmost
+// endpoints between this range and the given. replaced keys
+// in this range are freed and inherited keys are copied.
+void keyrange::extend(const comparator &cmp, const keyrange &range) {
+  const DBT *range_left = range.get_left_key();
+  const DBT *range_right = range.get_right_key();
+  if (cmp(range_left, get_left_key()) < 0) {
+    replace_left_key(range_left);
+  }
+  if (cmp(range_right, get_right_key()) > 0) {
+    replace_right_key(range_right);
+  }
+}
+
+// how much memory does this keyrange take?
+// - the size of the left and right keys
+// --- ignore the fact that we may have optimized the point case.
+//     it complicates things for little gain.
+// - the size of the keyrange class itself
+uint64_t keyrange::get_memory_size(void) const {
+  const DBT *left_key = get_left_key();
+  const DBT *right_key = get_right_key();
+  return left_key->size + right_key->size + sizeof(keyrange);
+}
+
+// compare ranges.
+keyrange::comparison keyrange::compare(const comparator &cmp,
+                                       const keyrange &range) const {
+  if (cmp(get_right_key(), range.get_left_key()) < 0) {
+    return comparison::LESS_THAN;
+  } else if (cmp(get_left_key(), range.get_right_key()) > 0) {
+    return comparison::GREATER_THAN;
+  } else if (cmp(get_left_key(), range.get_left_key()) == 0 &&
+             cmp(get_right_key(), range.get_right_key()) == 0) {
+    return comparison::EQUALS;
+  } else {
+    return comparison::OVERLAPS;
+  }
+}
+
+bool keyrange::overlaps(const comparator &cmp, const keyrange &range) const {
+  // equality is a stronger form of overlapping.
+  // so two ranges "overlap" if they're either equal or just overlapping.
+  comparison c = compare(cmp, range);
+  return c == comparison::EQUALS || c == comparison::OVERLAPS;
+}
+
+keyrange keyrange::get_infinite_range(void) {
+  keyrange range;
+  range.create(toku_dbt_negative_infinity(), toku_dbt_positive_infinity());
+  return range;
+}
+
+void keyrange::init_empty(void) {
+  m_left_key = nullptr;
+  m_right_key = nullptr;
+  toku_init_dbt(&m_left_key_copy);
+  toku_init_dbt(&m_right_key_copy);
+  m_point_range = false;
+}
+
+const DBT *keyrange::get_left_key(void) const {
+  if (m_left_key) {
+    return m_left_key;
+  } else {
+    return &m_left_key_copy;
+  }
+}
+
+const DBT *keyrange::get_right_key(void) const {
+  if (m_right_key) {
+    return m_right_key;
+  } else {
+    return &m_right_key_copy;
+  }
+}
+
+// copy the given once and set both the left and right pointers.
+// optimization for point ranges, so the left and right ranges
+// are not copied twice.
+void keyrange::set_both_keys(const DBT *key) {
+  if (toku_dbt_is_infinite(key)) {
+    m_left_key = key;
+    m_right_key = key;
+  } else {
+    toku_clone_dbt(&m_left_key_copy, *key);
+    toku_copyref_dbt(&m_right_key_copy, m_left_key_copy);
+  }
+  m_point_range = true;
+}
+
+// destroy the current left key. set and possibly copy the new one
+void keyrange::replace_left_key(const DBT *key) {
+  // a little magic:
+  //
+  // if this is a point range, then the left and right keys share
+  // one copy of the data, and it lives in the left key copy. so
+  // if we're replacing the left key, move the real data to the
+  // right key copy instead of destroying it. now, the memory is
+  // owned by the right key and the left key may be replaced.
+  if (m_point_range) {
+    m_right_key_copy = m_left_key_copy;
+  } else {
+    toku_destroy_dbt(&m_left_key_copy);
+  }
+
+  if (toku_dbt_is_infinite(key)) {
+    m_left_key = key;
+  } else {
+    toku_clone_dbt(&m_left_key_copy, *key);
+    m_left_key = nullptr;
+  }
+  m_point_range = false;
+}
+
+// destroy the current right key. set and possibly copy the new one
+void keyrange::replace_right_key(const DBT *key) {
+  toku_destroy_dbt(&m_right_key_copy);
+  if (toku_dbt_is_infinite(key)) {
+    m_right_key = key;
+  } else {
+    toku_clone_dbt(&m_right_key_copy, *key);
+    m_right_key = nullptr;
+  }
+  m_point_range = false;
+}
+
+} /* namespace toku */
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/keyrange.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/keyrange.h
new file mode 100644
index 000000000..f9aeea0c4
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/keyrange.h
@@ -0,0 +1,141 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include "../ft/comparator.h"
+
+namespace toku {
+
+// A keyrange has a left and right key as endpoints.
+//
+// When a keyrange is created it owns no memory, but when it copies
+// or extends another keyrange, it copies memory as necessary. This
+// means it is cheap in the common case.
+
+class keyrange {
+ public:
+  // effect: constructor that borrows left and right key pointers.
+  //         no memory is allocated or copied.
+  void create(const DBT *left_key, const DBT *right_key);
+
+  // effect: constructor that allocates and copies another keyrange's points.
+  void create_copy(const keyrange &range);
+
+  // effect: destroys the keyrange, freeing any allocated memory
+  void destroy(void);
+
+  // effect: extends the keyrange by choosing the leftmost and rightmost
+  //         endpoints from this range and the given range.
+  //         replaced keys in this range are freed, new keys are copied.
+  void extend(const comparator &cmp, const keyrange &range);
+
+  // returns: the amount of memory this keyrange takes. does not account
+  //          for point optimizations or malloc overhead.
+  uint64_t get_memory_size(void) const;
+
+  // returns: pointer to the left key of this range
+  const DBT *get_left_key(void) const;
+
+  // returns: pointer to the right key of this range
+  const DBT *get_right_key(void) const;
+
+  // two ranges are either equal, lt, gt, or overlapping
+  enum comparison { EQUALS, LESS_THAN, GREATER_THAN, OVERLAPS };
+
+  // effect: compares this range to the given range
+  // returns: LESS_THAN    if given range is strictly to the left
+  //          GREATER_THAN if given range is strictly to the right
+  //          EQUALS       if given range has the same left and right endpoints
+  //          OVERLAPS     if at least one of the given range's endpoints falls
+  //                       between this range's endpoints
+  comparison compare(const comparator &cmp, const keyrange &range) const;
+
+  // returns: true if the range and the given range are equal or overlapping
+  bool overlaps(const comparator &cmp, const keyrange &range) const;
+
+  // returns: a keyrange representing -inf, +inf
+  static keyrange get_infinite_range(void);
+
+ private:
+  // some keys should be copied, some keys should not be.
+  //
+  // to support both, we use two DBTs for copies and two pointers
+  // for temporaries. the access rule is:
+  // - if a pointer is non-null, then it reprsents the key.
+  // - otherwise the pointer is null, and the key is in the copy.
+  DBT m_left_key_copy;
+  DBT m_right_key_copy;
+  const DBT *m_left_key;
+  const DBT *m_right_key;
+
+  // if this range is a point range, then m_left_key == m_right_key
+  // and the actual data is stored exactly once in m_left_key_copy.
+  bool m_point_range;
+
+  // effect: initializes a keyrange to be empty
+  void init_empty(void);
+
+  // effect: copies the given key once into the left key copy
+  //         and sets the right key copy to share the left.
+  // rationale: optimization for point ranges to only do one malloc
+  void set_both_keys(const DBT *key);
+
+  // effect: destroys the current left key. sets and copies the new one.
+  void replace_left_key(const DBT *key);
+
+  // effect: destroys the current right key. sets and copies the new one.
+  void replace_right_key(const DBT *key);
+};
+
+} /* namespace toku */
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/lock_request.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/lock_request.cc
new file mode 100644
index 000000000..3d217be70
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/lock_request.cc
@@ -0,0 +1,527 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=2:softtabstop=2:
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include "lock_request.h"
+
+#include "../portability/toku_race_tools.h"
+#include "../portability/txn_subst.h"
+#include "../util/dbt.h"
+#include "locktree.h"
+
+namespace toku {
+
+// initialize a lock request's internals
+void lock_request::create(toku_external_mutex_factory_t mutex_factory) {
+  m_txnid = TXNID_NONE;
+  m_conflicting_txnid = TXNID_NONE;
+  m_start_time = 0;
+  m_left_key = nullptr;
+  m_right_key = nullptr;
+  toku_init_dbt(&m_left_key_copy);
+  toku_init_dbt(&m_right_key_copy);
+
+  m_type = type::UNKNOWN;
+  m_lt = nullptr;
+
+  m_complete_r = 0;
+  m_state = state::UNINITIALIZED;
+  m_info = nullptr;
+
+  // psergey-todo: this condition is for interruptible wait
+  // note: moved to here from lock_request::create:
+  toku_external_cond_init(mutex_factory, &m_wait_cond);
+
+  m_start_test_callback = nullptr;
+  m_start_before_pending_test_callback = nullptr;
+  m_retry_test_callback = nullptr;
+}
+
+// destroy a lock request.
+void lock_request::destroy(void) {
+  invariant(m_state != state::PENDING);
+  invariant(m_state != state::DESTROYED);
+  m_state = state::DESTROYED;
+  toku_destroy_dbt(&m_left_key_copy);
+  toku_destroy_dbt(&m_right_key_copy);
+  toku_external_cond_destroy(&m_wait_cond);
+}
+
+// set the lock request parameters. this API allows a lock request to be reused.
+void lock_request::set(locktree *lt, TXNID txnid, const DBT *left_key,
+                       const DBT *right_key, lock_request::type lock_type,
+                       bool big_txn, void *extra) {
+  invariant(m_state != state::PENDING);
+  m_lt = lt;
+
+  m_txnid = txnid;
+  m_left_key = left_key;
+  m_right_key = right_key;
+  toku_destroy_dbt(&m_left_key_copy);
+  toku_destroy_dbt(&m_right_key_copy);
+  m_type = lock_type;
+  m_state = state::INITIALIZED;
+  m_info = lt ? lt->get_lock_request_info() : nullptr;
+  m_big_txn = big_txn;
+  m_extra = extra;
+}
+
+// get rid of any stored left and right key copies and
+// replace them with copies of the given left and right key
+void lock_request::copy_keys() {
+  if (!toku_dbt_is_infinite(m_left_key)) {
+    toku_clone_dbt(&m_left_key_copy, *m_left_key);
+    m_left_key = &m_left_key_copy;
+  }
+  if (!toku_dbt_is_infinite(m_right_key)) {
+    toku_clone_dbt(&m_right_key_copy, *m_right_key);
+    m_right_key = &m_right_key_copy;
+  }
+}
+
+// what are the conflicts for this pending lock request?
+void lock_request::get_conflicts(txnid_set *conflicts) {
+  invariant(m_state == state::PENDING);
+  const bool is_write_request = m_type == type::WRITE;
+  m_lt->get_conflicts(is_write_request, m_txnid, m_left_key, m_right_key,
+                      conflicts);
+}
+
+// build a wait-for-graph for this lock request and the given conflict set
+// for each transaction B that blocks A's lock request
+//     if B is blocked then
+//         add (A,T) to the WFG and if B is new, fill in the WFG from B
+void lock_request::build_wait_graph(wfg *wait_graph,
+                                    const txnid_set &conflicts) {
+  uint32_t num_conflicts = conflicts.size();
+  for (uint32_t i = 0; i < num_conflicts; i++) {
+    TXNID conflicting_txnid = conflicts.get(i);
+    lock_request *conflicting_request = find_lock_request(conflicting_txnid);
+    invariant(conflicting_txnid != m_txnid);
+    invariant(conflicting_request != this);
+    if (conflicting_request) {
+      bool already_exists = wait_graph->node_exists(conflicting_txnid);
+      wait_graph->add_edge(m_txnid, conflicting_txnid);
+      if (!already_exists) {
+        // recursively build the wait for graph rooted at the conflicting
+        // request, given its set of lock conflicts.
+        txnid_set other_conflicts;
+        other_conflicts.create();
+        conflicting_request->get_conflicts(&other_conflicts);
+        conflicting_request->build_wait_graph(wait_graph, other_conflicts);
+        other_conflicts.destroy();
+      }
+    }
+  }
+}
+
+// returns: true if the current set of lock requests contains
+//          a deadlock, false otherwise.
+bool lock_request::deadlock_exists(const txnid_set &conflicts) {
+  wfg wait_graph;
+  wait_graph.create();
+
+  build_wait_graph(&wait_graph, conflicts);
+
+  std::function<void(TXNID)> reporter;
+  if (m_deadlock_cb) {
+    reporter = [this](TXNID a) {
+      lock_request *req = find_lock_request(a);
+      if (req) {
+        m_deadlock_cb(req->m_txnid, (req->m_type == lock_request::WRITE),
+                      req->m_left_key, req->m_right_key);
+      }
+    };
+  }
+
+  bool deadlock = wait_graph.cycle_exists_from_txnid(m_txnid, reporter);
+  wait_graph.destroy();
+  return deadlock;
+}
+
+// try to acquire a lock described by this lock request.
+int lock_request::start(void) {
+  int r;
+
+  txnid_set conflicts;
+  conflicts.create();
+  if (m_type == type::WRITE) {
+    r = m_lt->acquire_write_lock(m_txnid, m_left_key, m_right_key, &conflicts,
+                                 m_big_txn);
+  } else {
+    invariant(m_type == type::READ);
+    r = m_lt->acquire_read_lock(m_txnid, m_left_key, m_right_key, &conflicts,
+                                m_big_txn);
+  }
+
+  // if the lock is not granted, save it to the set of lock requests
+  // and check for a deadlock. if there is one, complete it as failed
+  if (r == DB_LOCK_NOTGRANTED) {
+    copy_keys();
+    m_state = state::PENDING;
+    m_start_time = toku_current_time_microsec() / 1000;
+    m_conflicting_txnid = conflicts.get(0);
+    if (m_start_before_pending_test_callback)
+      m_start_before_pending_test_callback();
+    toku_external_mutex_lock(&m_info->mutex);
+    insert_into_lock_requests();
+    if (deadlock_exists(conflicts)) {
+      remove_from_lock_requests();
+      r = DB_LOCK_DEADLOCK;
+    }
+    toku_external_mutex_unlock(&m_info->mutex);
+    if (m_start_test_callback) m_start_test_callback();  // test callback
+  }
+
+  if (r != DB_LOCK_NOTGRANTED) {
+    complete(r);
+  }
+
+  conflicts.destroy();
+  return r;
+}
+
+// sleep on the lock request until it becomes resolved or the wait time has
+// elapsed.
+int lock_request::wait(uint64_t wait_time_ms) {
+  return wait(wait_time_ms, 0, nullptr);
+}
+
+int lock_request::wait(uint64_t wait_time_ms, uint64_t killed_time_ms,
+                       int (*killed_callback)(void),
+                       void (*lock_wait_callback)(void *, lock_wait_infos *),
+                       void *callback_arg) {
+  uint64_t t_now = toku_current_time_microsec();
+  uint64_t t_start = t_now;
+  uint64_t t_end = t_start + wait_time_ms * 1000;
+
+  toku_external_mutex_lock(&m_info->mutex);
+
+  // check again, this time locking out other retry calls
+  if (m_state == state::PENDING) {
+    lock_wait_infos conflicts_collector;
+    retry(&conflicts_collector);
+    if (m_state == state::PENDING) {
+      report_waits(&conflicts_collector, lock_wait_callback, callback_arg);
+    }
+  }
+
+  while (m_state == state::PENDING) {
+    // check if this thread is killed
+    if (killed_callback && killed_callback()) {
+      remove_from_lock_requests();
+      complete(DB_LOCK_NOTGRANTED);
+      continue;
+    }
+
+    // compute the time until we should wait
+    uint64_t t_wait;
+    if (killed_time_ms == 0) {
+      t_wait = t_end;
+    } else {
+      t_wait = t_now + killed_time_ms * 1000;
+      if (t_wait > t_end) t_wait = t_end;
+    }
+
+    int r = toku_external_cond_timedwait(&m_wait_cond, &m_info->mutex,
+                                         (int64_t)(t_wait - t_now));
+    invariant(r == 0 || r == ETIMEDOUT);
+
+    t_now = toku_current_time_microsec();
+    if (m_state == state::PENDING && (t_now >= t_end)) {
+      m_info->counters.timeout_count += 1;
+
+      // if we're still pending and we timed out, then remove our
+      // request from the set of lock requests and fail.
+      remove_from_lock_requests();
+
+      // complete sets m_state to COMPLETE, breaking us out of the loop
+      complete(DB_LOCK_NOTGRANTED);
+    }
+  }
+
+  uint64_t t_real_end = toku_current_time_microsec();
+  uint64_t duration = t_real_end - t_start;
+  m_info->counters.wait_count += 1;
+  m_info->counters.wait_time += duration;
+  if (duration >= 1000000) {
+    m_info->counters.long_wait_count += 1;
+    m_info->counters.long_wait_time += duration;
+  }
+  toku_external_mutex_unlock(&m_info->mutex);
+
+  invariant(m_state == state::COMPLETE);
+  return m_complete_r;
+}
+
+// complete this lock request with the given return value
+void lock_request::complete(int complete_r) {
+  m_complete_r = complete_r;
+  m_state = state::COMPLETE;
+}
+
+const DBT *lock_request::get_left_key(void) const { return m_left_key; }
+
+const DBT *lock_request::get_right_key(void) const { return m_right_key; }
+
+TXNID lock_request::get_txnid(void) const { return m_txnid; }
+
+uint64_t lock_request::get_start_time(void) const { return m_start_time; }
+
+TXNID lock_request::get_conflicting_txnid(void) const {
+  return m_conflicting_txnid;
+}
+
+int lock_request::retry(lock_wait_infos *conflicts_collector) {
+  invariant(m_state == state::PENDING);
+  int r;
+  txnid_set conflicts;
+  conflicts.create();
+
+  if (m_type == type::WRITE) {
+    r = m_lt->acquire_write_lock(m_txnid, m_left_key, m_right_key, &conflicts,
+                                 m_big_txn);
+  } else {
+    r = m_lt->acquire_read_lock(m_txnid, m_left_key, m_right_key, &conflicts,
+                                m_big_txn);
+  }
+
+  // if the acquisition succeeded then remove ourselves from the
+  // set of lock requests, complete, and signal the waiting thread.
+  if (r == 0) {
+    remove_from_lock_requests();
+    complete(r);
+    if (m_retry_test_callback) m_retry_test_callback();  // test callback
+    toku_external_cond_broadcast(&m_wait_cond);
+  } else {
+    m_conflicting_txnid = conflicts.get(0);
+    add_conflicts_to_waits(&conflicts, conflicts_collector);
+  }
+  conflicts.destroy();
+
+  return r;
+}
+
+void lock_request::retry_all_lock_requests(
+    locktree *lt, void (*lock_wait_callback)(void *, lock_wait_infos *),
+    void *callback_arg, void (*after_retry_all_test_callback)(void)) {
+  lt_lock_request_info *info = lt->get_lock_request_info();
+
+  // if there are no pending lock requests than there is nothing to do
+  // the unlocked data race on pending_is_empty is OK since lock requests
+  // are retried after added to the pending set.
+  if (info->pending_is_empty) return;
+
+  // get my retry generation (post increment of retry_want)
+  unsigned long long my_retry_want = (info->retry_want += 1);
+
+  toku_mutex_lock(&info->retry_mutex);
+
+  // here is the group retry algorithm.
+  // get the latest retry_want count and use it as the generation number of
+  // this retry operation. if this retry generation is > the last retry
+  // generation, then do the lock retries.  otherwise, no lock retries
+  // are needed.
+  if ((my_retry_want - 1) == info->retry_done) {
+    for (;;) {
+      if (!info->running_retry) {
+        info->running_retry = true;
+        info->retry_done = info->retry_want;
+        toku_mutex_unlock(&info->retry_mutex);
+        retry_all_lock_requests_info(info, lock_wait_callback, callback_arg);
+        if (after_retry_all_test_callback) after_retry_all_test_callback();
+        toku_mutex_lock(&info->retry_mutex);
+        info->running_retry = false;
+        toku_cond_broadcast(&info->retry_cv);
+        break;
+      } else {
+        toku_cond_wait(&info->retry_cv, &info->retry_mutex);
+      }
+    }
+  }
+  toku_mutex_unlock(&info->retry_mutex);
+}
+
+void lock_request::retry_all_lock_requests_info(
+    lt_lock_request_info *info,
+    void (*lock_wait_callback)(void *, lock_wait_infos *), void *callback_arg) {
+  toku_external_mutex_lock(&info->mutex);
+  // retry all of the pending lock requests.
+  lock_wait_infos conflicts_collector;
+  for (uint32_t i = 0; i < info->pending_lock_requests.size();) {
+    lock_request *request;
+    int r = info->pending_lock_requests.fetch(i, &request);
+    invariant_zero(r);
+
+    // retry the lock request. if it didn't succeed,
+    // move on to the next lock request. otherwise
+    // the request is gone from the list so we may
+    // read the i'th entry for the next one.
+    r = request->retry(&conflicts_collector);
+    if (r != 0) {
+      i++;
+    }
+  }
+
+  // call report_waits while holding the pending queue lock since
+  // the waiter object is still valid while it's in the queue
+  report_waits(&conflicts_collector, lock_wait_callback, callback_arg);
+
+  // future threads should only retry lock requests if some still exist
+  info->should_retry_lock_requests = info->pending_lock_requests.size() > 0;
+  toku_external_mutex_unlock(&info->mutex);
+}
+
+void lock_request::add_conflicts_to_waits(txnid_set *conflicts,
+                                          lock_wait_infos *wait_conflicts) {
+  wait_conflicts->push_back({m_lt, get_txnid(), m_extra, {}});
+  uint32_t num_conflicts = conflicts->size();
+  for (uint32_t i = 0; i < num_conflicts; i++) {
+    wait_conflicts->back().waitees.push_back(conflicts->get(i));
+  }
+}
+
+void lock_request::report_waits(lock_wait_infos *wait_conflicts,
+                                void (*lock_wait_callback)(void *,
+                                                           lock_wait_infos *),
+                                void *callback_arg) {
+  if (lock_wait_callback) (*lock_wait_callback)(callback_arg, wait_conflicts);
+}
+
+void *lock_request::get_extra(void) const { return m_extra; }
+
+void lock_request::kill_waiter(void) {
+  remove_from_lock_requests();
+  complete(DB_LOCK_NOTGRANTED);
+  toku_external_cond_broadcast(&m_wait_cond);
+}
+
+void lock_request::kill_waiter(locktree *lt, void *extra) {
+  lt_lock_request_info *info = lt->get_lock_request_info();
+  toku_external_mutex_lock(&info->mutex);
+  for (uint32_t i = 0; i < info->pending_lock_requests.size(); i++) {
+    lock_request *request;
+    int r = info->pending_lock_requests.fetch(i, &request);
+    if (r == 0 && request->get_extra() == extra) {
+      request->kill_waiter();
+      break;
+    }
+  }
+  toku_external_mutex_unlock(&info->mutex);
+}
+
+// find another lock request by txnid. must hold the mutex.
+lock_request *lock_request::find_lock_request(const TXNID &txnid) {
+  lock_request *request;
+  int r = m_info->pending_lock_requests.find_zero<TXNID, find_by_txnid>(
+      txnid, &request, nullptr);
+  if (r != 0) {
+    request = nullptr;
+  }
+  return request;
+}
+
+// insert this lock request into the locktree's set. must hold the mutex.
+void lock_request::insert_into_lock_requests(void) {
+  uint32_t idx;
+  lock_request *request;
+  int r = m_info->pending_lock_requests.find_zero<TXNID, find_by_txnid>(
+      m_txnid, &request, &idx);
+  invariant(r == DB_NOTFOUND);
+  r = m_info->pending_lock_requests.insert_at(this, idx);
+  invariant_zero(r);
+  m_info->pending_is_empty = false;
+}
+
+// remove this lock request from the locktree's set. must hold the mutex.
+void lock_request::remove_from_lock_requests(void) {
+  uint32_t idx;
+  lock_request *request;
+  int r = m_info->pending_lock_requests.find_zero<TXNID, find_by_txnid>(
+      m_txnid, &request, &idx);
+  invariant_zero(r);
+  invariant(request == this);
+  r = m_info->pending_lock_requests.delete_at(idx);
+  invariant_zero(r);
+  if (m_info->pending_lock_requests.size() == 0)
+    m_info->pending_is_empty = true;
+}
+
+int lock_request::find_by_txnid(lock_request *const &request,
+                                const TXNID &txnid) {
+  TXNID request_txnid = request->m_txnid;
+  if (request_txnid < txnid) {
+    return -1;
+  } else if (request_txnid == txnid) {
+    return 0;
+  } else {
+    return 1;
+  }
+}
+
+void lock_request::set_start_test_callback(void (*f)(void)) {
+  m_start_test_callback = f;
+}
+
+void lock_request::set_start_before_pending_test_callback(void (*f)(void)) {
+  m_start_before_pending_test_callback = f;
+}
+
+void lock_request::set_retry_test_callback(void (*f)(void)) {
+  m_retry_test_callback = f;
+}
+
+} /* namespace toku */
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/lock_request.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/lock_request.h
new file mode 100644
index 000000000..d30e1e2ca
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/lock_request.h
@@ -0,0 +1,255 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=2:softtabstop=2:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include "../db.h"
+#include "../ft/comparator.h"
+#include "../portability/toku_pthread.h"
+#include "locktree.h"
+#include "txnid_set.h"
+#include "wfg.h"
+
+namespace toku {
+
+// Information about a lock wait
+struct lock_wait_info {
+  locktree *ltree;  // the tree where wait happens
+  TXNID waiter;     // the waiting transaction
+  void *m_extra;    // lock_request's m_extra
+
+  // The transactions that are waited for.
+  std::vector<TXNID> waitees;
+};
+
+typedef std::vector<lock_wait_info> lock_wait_infos;
+
+// A lock request contains the db, the key range, the lock type, and
+// the transaction id that describes a potential row range lock.
+//
+// the typical use case is:
+// - initialize a lock request
+// - start to try to acquire the lock
+// - do something else
+// - wait for the lock request to be resolved on a timed condition
+// - destroy the lock request
+// a lock request is resolved when its state is no longer pending, or
+// when it becomes granted, or timedout, or deadlocked. when resolved, the
+// state of the lock request is changed and any waiting threads are awakened.
+
+class lock_request {
+ public:
+  enum type { UNKNOWN, READ, WRITE };
+
+  // effect: Initializes a lock request.
+  void create(toku_external_mutex_factory_t mutex_factory);
+
+  // effect: Destroys a lock request.
+  void destroy(void);
+
+  // effect: Resets the lock request parameters, allowing it to be reused.
+  // requires: Lock request was already created at some point
+  void set(locktree *lt, TXNID txnid, const DBT *left_key, const DBT *right_key,
+           type lock_type, bool big_txn, void *extra = nullptr);
+
+  // effect: Tries to acquire a lock described by this lock request.
+  // returns: The return code of locktree::acquire_[write,read]_lock()
+  //          or DB_LOCK_DEADLOCK if this request would end up deadlocked.
+  int start(void);
+
+  // effect: Sleeps until either the request is granted or the wait time
+  // expires. returns: The return code of locktree::acquire_[write,read]_lock()
+  //          or simply DB_LOCK_NOTGRANTED if the wait time expired.
+  int wait(uint64_t wait_time_ms);
+  int wait(uint64_t wait_time_ms, uint64_t killed_time_ms,
+           int (*killed_callback)(void),
+           void (*lock_wait_callback)(void *, lock_wait_infos *) = nullptr,
+           void *callback_arg = nullptr);
+
+  // return: left end-point of the lock range
+  const DBT *get_left_key(void) const;
+
+  // return: right end-point of the lock range
+  const DBT *get_right_key(void) const;
+
+  // return: the txnid waiting for a lock
+  TXNID get_txnid(void) const;
+
+  // return: when this lock request started, as milliseconds from epoch
+  uint64_t get_start_time(void) const;
+
+  // return: which txnid is blocking this request (there may be more, though)
+  TXNID get_conflicting_txnid(void) const;
+
+  // effect: Retries all of the lock requests for the given locktree.
+  //         Any lock requests successfully restarted is completed and woken
+  //         up.
+  //         The rest remain pending.
+  static void retry_all_lock_requests(
+      locktree *lt,
+      void (*lock_wait_callback)(void *, lock_wait_infos *) = nullptr,
+      void *callback_arg = nullptr,
+      void (*after_retry_test_callback)(void) = nullptr);
+  static void retry_all_lock_requests_info(
+      lt_lock_request_info *info,
+      void (*lock_wait_callback)(void *, lock_wait_infos *),
+      void *callback_arg);
+
+  void set_start_test_callback(void (*f)(void));
+  void set_start_before_pending_test_callback(void (*f)(void));
+  void set_retry_test_callback(void (*f)(void));
+
+  void *get_extra(void) const;
+
+  void kill_waiter(void);
+  static void kill_waiter(locktree *lt, void *extra);
+
+ private:
+  enum state {
+    UNINITIALIZED,
+    INITIALIZED,
+    PENDING,
+    COMPLETE,
+    DESTROYED,
+  };
+
+  // The keys for a lock request are stored "unowned" in m_left_key
+  // and m_right_key. When the request is about to go to sleep, it
+  // copies these keys and stores them in m_left_key_copy etc and
+  // sets the temporary pointers to null.
+  TXNID m_txnid;
+  TXNID m_conflicting_txnid;
+  uint64_t m_start_time;
+  const DBT *m_left_key;
+  const DBT *m_right_key;
+  DBT m_left_key_copy;
+  DBT m_right_key_copy;
+
+  // The lock request type and associated locktree
+  type m_type;
+  locktree *m_lt;
+
+  // If the lock request is in the completed state, then its
+  // final return value is stored in m_complete_r
+  int m_complete_r;
+  state m_state;
+
+  toku_external_cond_t m_wait_cond;
+
+  bool m_big_txn;
+
+  // the lock request info state stored in the
+  // locktree that this lock request is for.
+  struct lt_lock_request_info *m_info;
+
+  void *m_extra;
+
+  // effect: tries again to acquire the lock described by this lock request
+  // returns: 0 if retrying the request succeeded and is now complete
+  int retry(lock_wait_infos *collector);
+
+  void complete(int complete_r);
+
+  // effect: Finds another lock request by txnid.
+  // requires: The lock request info mutex is held
+  lock_request *find_lock_request(const TXNID &txnid);
+
+  // effect: Insert this lock request into the locktree's set.
+  // requires: the locktree's mutex is held
+  void insert_into_lock_requests(void);
+
+  // effect: Removes this lock request from the locktree's set.
+  // requires: The lock request info mutex is held
+  void remove_from_lock_requests(void);
+
+  // effect: Asks this request's locktree which txnids are preventing
+  //         us from getting the lock described by this request.
+  // returns: conflicts is populated with the txnid's that this request
+  //          is blocked on
+  void get_conflicts(txnid_set *conflicts);
+
+  // effect: Builds a wait-for-graph for this lock request and the given
+  // conflict set
+  void build_wait_graph(wfg *wait_graph, const txnid_set &conflicts);
+
+  // returns: True if this lock request is in deadlock with the given conflicts
+  // set
+  bool deadlock_exists(const txnid_set &conflicts);
+
+  void copy_keys(void);
+
+  static int find_by_txnid(lock_request *const &request, const TXNID &txnid);
+
+  // Report list of conflicts to lock wait callback.
+  static void report_waits(lock_wait_infos *wait_conflicts,
+                           void (*lock_wait_callback)(void *,
+                                                      lock_wait_infos *),
+                           void *callback_arg);
+  void add_conflicts_to_waits(txnid_set *conflicts,
+                              lock_wait_infos *wait_conflicts);
+
+  void (*m_start_test_callback)(void);
+  void (*m_start_before_pending_test_callback)(void);
+  void (*m_retry_test_callback)(void);
+
+ public:
+  std::function<void(TXNID, bool, const DBT *, const DBT *)> m_deadlock_cb;
+
+  friend class lock_request_unit_test;
+};
+// PORT: lock_request is not a POD anymore due to use of toku_external_cond_t
+//  This is ok as the PODness is not really required: lock_request objects are
+//  not moved in memory or anything.
+// ENSURE_POD(lock_request);
+
+} /* namespace toku */
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/locktree.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/locktree.cc
new file mode 100644
index 000000000..3d6a590c7
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/locktree.cc
@@ -0,0 +1,1023 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=2:softtabstop=2:
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include "locktree.h"
+
+#include <memory.h>
+
+#include "../portability/toku_pthread.h"
+#include "../portability/toku_time.h"
+#include "../util/growable_array.h"
+#include "range_buffer.h"
+
+// including the concurrent_tree here expands the templates
+// and "defines" the implementation, so we do it here in
+// the locktree source file instead of the header.
+#include "concurrent_tree.h"
+
+namespace toku {
+// A locktree represents the set of row locks owned by all transactions
+// over an open dictionary. Read and write ranges are represented as
+// a left and right key which are compared with the given descriptor
+// and comparison fn.
+//
+// Each locktree has a reference count which it manages
+// but does nothing based on the value of the reference count - it is
+// up to the user of the locktree to destroy it when it sees fit.
+
+void locktree::create(locktree_manager *mgr, DICTIONARY_ID dict_id,
+                      const comparator &cmp,
+                      toku_external_mutex_factory_t mutex_factory) {
+  m_mgr = mgr;
+  m_dict_id = dict_id;
+
+  m_cmp.create_from(cmp);
+  m_reference_count = 1;
+  m_userdata = nullptr;
+
+  XCALLOC(m_rangetree);
+  m_rangetree->create(&m_cmp);
+
+  m_sto_txnid = TXNID_NONE;
+  m_sto_buffer.create();
+  m_sto_score = STO_SCORE_THRESHOLD;
+  m_sto_end_early_count = 0;
+  m_sto_end_early_time = 0;
+
+  m_escalation_barrier = [](const DBT *, const DBT *, void *) -> bool {
+    return false;
+  };
+
+  m_lock_request_info.init(mutex_factory);
+}
+
+void locktree::set_escalation_barrier_func(
+    lt_escalation_barrier_check_func func, void *extra) {
+  m_escalation_barrier = func;
+  m_escalation_barrier_arg = extra;
+}
+
+void lt_lock_request_info::init(toku_external_mutex_factory_t mutex_factory) {
+  pending_lock_requests.create();
+  pending_is_empty = true;
+  toku_external_mutex_init(mutex_factory, &mutex);
+  retry_want = retry_done = 0;
+  ZERO_STRUCT(counters);
+  ZERO_STRUCT(retry_mutex);
+  toku_mutex_init(locktree_request_info_retry_mutex_key, &retry_mutex, nullptr);
+  toku_cond_init(locktree_request_info_retry_cv_key, &retry_cv, nullptr);
+  running_retry = false;
+
+  TOKU_VALGRIND_HG_DISABLE_CHECKING(&pending_is_empty,
+                                    sizeof(pending_is_empty));
+  TOKU_DRD_IGNORE_VAR(pending_is_empty);
+}
+
+void locktree::destroy(void) {
+  invariant(m_reference_count == 0);
+  invariant(m_lock_request_info.pending_lock_requests.size() == 0);
+  m_cmp.destroy();
+  m_rangetree->destroy();
+  toku_free(m_rangetree);
+  m_sto_buffer.destroy();
+  m_lock_request_info.destroy();
+}
+
+void lt_lock_request_info::destroy(void) {
+  pending_lock_requests.destroy();
+  toku_external_mutex_destroy(&mutex);
+  toku_mutex_destroy(&retry_mutex);
+  toku_cond_destroy(&retry_cv);
+}
+
+void locktree::add_reference(void) {
+  (void)toku_sync_add_and_fetch(&m_reference_count, 1);
+}
+
+uint32_t locktree::release_reference(void) {
+  return toku_sync_sub_and_fetch(&m_reference_count, 1);
+}
+
+uint32_t locktree::get_reference_count(void) { return m_reference_count; }
+
+// a container for a range/txnid pair
+struct row_lock {
+  keyrange range;
+  TXNID txnid;
+  bool is_shared;
+  TxnidVector *owners;
+};
+
+// iterate over a locked keyrange and copy out all of the data,
+// storing each row lock into the given growable array. the
+// caller does not own the range inside the returned row locks,
+// so remove from the tree with care using them as keys.
+static void iterate_and_get_overlapping_row_locks(
+    const concurrent_tree::locked_keyrange *lkr,
+    GrowableArray<row_lock> *row_locks) {
+  struct copy_fn_obj {
+    GrowableArray<row_lock> *row_locks;
+    bool fn(const keyrange &range, TXNID txnid, bool is_shared,
+            TxnidVector *owners) {
+      row_lock lock = {.range = range,
+                       .txnid = txnid,
+                       .is_shared = is_shared,
+                       .owners = owners};
+      row_locks->push(lock);
+      return true;
+    }
+  } copy_fn;
+  copy_fn.row_locks = row_locks;
+  lkr->iterate(&copy_fn);
+}
+
+// given a txnid and a set of overlapping row locks, determine
+// which txnids are conflicting, and store them in the conflicts
+// set, if given.
+static bool determine_conflicting_txnids(
+    const GrowableArray<row_lock> &row_locks, const TXNID &txnid,
+    txnid_set *conflicts) {
+  bool conflicts_exist = false;
+  const size_t num_overlaps = row_locks.get_size();
+  for (size_t i = 0; i < num_overlaps; i++) {
+    const row_lock lock = row_locks.fetch_unchecked(i);
+    const TXNID other_txnid = lock.txnid;
+    if (other_txnid != txnid) {
+      if (conflicts) {
+        if (other_txnid == TXNID_SHARED) {
+          // Add all shared lock owners, except this transaction.
+          for (TXNID shared_id : *lock.owners) {
+            if (shared_id != txnid) conflicts->add(shared_id);
+          }
+        } else {
+          conflicts->add(other_txnid);
+        }
+      }
+      conflicts_exist = true;
+    }
+  }
+  return conflicts_exist;
+}
+
+// how much memory does a row lock take up in a concurrent tree?
+static uint64_t row_lock_size_in_tree(const row_lock &lock) {
+  const uint64_t overhead = concurrent_tree::get_insertion_memory_overhead();
+  return lock.range.get_memory_size() + overhead;
+}
+
+// remove and destroy the given row lock from the locked keyrange,
+// then notify the memory tracker of the newly freed lock.
+static void remove_row_lock_from_tree(concurrent_tree::locked_keyrange *lkr,
+                                      const row_lock &lock, TXNID txnid,
+                                      locktree_manager *mgr) {
+  const uint64_t mem_released = row_lock_size_in_tree(lock);
+  lkr->remove(lock.range, txnid);
+  if (mgr != nullptr) {
+    mgr->note_mem_released(mem_released);
+  }
+}
+
+// insert a row lock into the locked keyrange, then notify
+// the memory tracker of this newly acquired lock.
+static void insert_row_lock_into_tree(concurrent_tree::locked_keyrange *lkr,
+                                      const row_lock &lock,
+                                      locktree_manager *mgr) {
+  uint64_t mem_used = row_lock_size_in_tree(lock);
+  lkr->insert(lock.range, lock.txnid, lock.is_shared);
+  if (mgr != nullptr) {
+    mgr->note_mem_used(mem_used);
+  }
+}
+
+void locktree::sto_begin(TXNID txnid) {
+  invariant(m_sto_txnid == TXNID_NONE);
+  invariant(m_sto_buffer.is_empty());
+  m_sto_txnid = txnid;
+}
+
+void locktree::sto_append(const DBT *left_key, const DBT *right_key,
+                          bool is_write_request) {
+  uint64_t buffer_mem, delta;
+
+  // psergey: the below two lines do not make any sense
+  // (and it's the same in upstream TokuDB)
+  keyrange range;
+  range.create(left_key, right_key);
+
+  buffer_mem = m_sto_buffer.total_memory_size();
+  m_sto_buffer.append(left_key, right_key, is_write_request);
+  delta = m_sto_buffer.total_memory_size() - buffer_mem;
+  if (m_mgr != nullptr) {
+    m_mgr->note_mem_used(delta);
+  }
+}
+
+void locktree::sto_end(void) {
+  uint64_t mem_size = m_sto_buffer.total_memory_size();
+  if (m_mgr != nullptr) {
+    m_mgr->note_mem_released(mem_size);
+  }
+  m_sto_buffer.destroy();
+  m_sto_buffer.create();
+  m_sto_txnid = TXNID_NONE;
+}
+
+void locktree::sto_end_early_no_accounting(void *prepared_lkr) {
+  sto_migrate_buffer_ranges_to_tree(prepared_lkr);
+  sto_end();
+  toku_unsafe_set(m_sto_score, 0);
+}
+
+void locktree::sto_end_early(void *prepared_lkr) {
+  m_sto_end_early_count++;
+
+  tokutime_t t0 = toku_time_now();
+  sto_end_early_no_accounting(prepared_lkr);
+  tokutime_t t1 = toku_time_now();
+
+  m_sto_end_early_time += (t1 - t0);
+}
+
+void locktree::sto_migrate_buffer_ranges_to_tree(void *prepared_lkr) {
+  // There should be something to migrate, and nothing in the rangetree.
+  invariant(!m_sto_buffer.is_empty());
+  invariant(m_rangetree->is_empty());
+
+  concurrent_tree sto_rangetree;
+  concurrent_tree::locked_keyrange sto_lkr;
+  sto_rangetree.create(&m_cmp);
+
+  // insert all of the ranges from the single txnid buffer into a new rangtree
+  range_buffer::iterator iter(&m_sto_buffer);
+  range_buffer::iterator::record rec;
+  while (iter.current(&rec)) {
+    sto_lkr.prepare(&sto_rangetree);
+    int r = acquire_lock_consolidated(&sto_lkr, m_sto_txnid, rec.get_left_key(),
+                                      rec.get_right_key(),
+                                      rec.get_exclusive_flag(), nullptr);
+    invariant_zero(r);
+    sto_lkr.release();
+    iter.next();
+  }
+
+  // Iterate the newly created rangetree and insert each range into the
+  // locktree's rangetree, on behalf of the old single txnid.
+  struct migrate_fn_obj {
+    concurrent_tree::locked_keyrange *dst_lkr;
+    bool fn(const keyrange &range, TXNID txnid, bool is_shared,
+            TxnidVector *owners) {
+      // There can't be multiple owners in STO mode
+      invariant_zero(owners);
+      dst_lkr->insert(range, txnid, is_shared);
+      return true;
+    }
+  } migrate_fn;
+  migrate_fn.dst_lkr =
+      static_cast<concurrent_tree::locked_keyrange *>(prepared_lkr);
+  sto_lkr.prepare(&sto_rangetree);
+  sto_lkr.iterate(&migrate_fn);
+  sto_lkr.remove_all();
+  sto_lkr.release();
+  sto_rangetree.destroy();
+  invariant(!m_rangetree->is_empty());
+}
+
+bool locktree::sto_try_acquire(void *prepared_lkr, TXNID txnid,
+                               const DBT *left_key, const DBT *right_key,
+                               bool is_write_request) {
+  if (m_rangetree->is_empty() && m_sto_buffer.is_empty() &&
+      toku_unsafe_fetch(m_sto_score) >= STO_SCORE_THRESHOLD) {
+    // We can do the optimization because the rangetree is empty, and
+    // we know its worth trying because the sto score is big enough.
+    sto_begin(txnid);
+  } else if (m_sto_txnid != TXNID_NONE) {
+    // We are currently doing the optimization. Check if we need to cancel
+    // it because a new txnid appeared, or if the current single txnid has
+    // taken too many locks already.
+    if (m_sto_txnid != txnid ||
+        m_sto_buffer.get_num_ranges() > STO_BUFFER_MAX_SIZE) {
+      sto_end_early(prepared_lkr);
+    }
+  }
+
+  // At this point the sto txnid is properly set. If it is valid, then
+  // this txnid can append its lock to the sto buffer successfully.
+  if (m_sto_txnid != TXNID_NONE) {
+    invariant(m_sto_txnid == txnid);
+    sto_append(left_key, right_key, is_write_request);
+    return true;
+  } else {
+    invariant(m_sto_buffer.is_empty());
+    return false;
+  }
+}
+
+/*
+  Do the same as iterate_and_get_overlapping_row_locks does, but also check for
+  this:
+    The set of overlapping rows locks consists of just one read-only shared
+    lock with the same endpoints as specified (in that case, we can just add
+    ourselves into that list)
+
+  @return true - One compatible shared lock
+         false - Otherwise
+*/
+static bool iterate_and_get_overlapping_row_locks2(
+    const concurrent_tree::locked_keyrange *lkr, const DBT *left_key,
+    const DBT *right_key, comparator *cmp, TXNID,
+    GrowableArray<row_lock> *row_locks) {
+  struct copy_fn_obj {
+    GrowableArray<row_lock> *row_locks;
+    bool first_call = true;
+    bool matching_lock_found = false;
+    const DBT *left_key, *right_key;
+    comparator *cmp;
+
+    bool fn(const keyrange &range, TXNID txnid, bool is_shared,
+            TxnidVector *owners) {
+      if (first_call) {
+        first_call = false;
+        if (is_shared && !(*cmp)(left_key, range.get_left_key()) &&
+            !(*cmp)(right_key, range.get_right_key())) {
+          matching_lock_found = true;
+        }
+      } else {
+        // if we see multiple matching locks, it doesn't matter whether
+        // the first one was matching.
+        matching_lock_found = false;
+      }
+      row_lock lock = {.range = range,
+                       .txnid = txnid,
+                       .is_shared = is_shared,
+                       .owners = owners};
+      row_locks->push(lock);
+      return true;
+    }
+  } copy_fn;
+  copy_fn.row_locks = row_locks;
+  copy_fn.left_key = left_key;
+  copy_fn.right_key = right_key;
+  copy_fn.cmp = cmp;
+  lkr->iterate(&copy_fn);
+  return copy_fn.matching_lock_found;
+}
+
+// try to acquire a lock and consolidate it with existing locks if possible
+// param: lkr, a prepared locked keyrange
+// return: 0 on success, DB_LOCK_NOTGRANTED if conflicting locks exist.
+int locktree::acquire_lock_consolidated(void *prepared_lkr, TXNID txnid,
+                                        const DBT *left_key,
+                                        const DBT *right_key,
+                                        bool is_write_request,
+                                        txnid_set *conflicts) {
+  int r = 0;
+  concurrent_tree::locked_keyrange *lkr;
+
+  keyrange requested_range;
+  requested_range.create(left_key, right_key);
+  lkr = static_cast<concurrent_tree::locked_keyrange *>(prepared_lkr);
+  lkr->acquire(requested_range);
+
+  // copy out the set of overlapping row locks.
+  GrowableArray<row_lock> overlapping_row_locks;
+  overlapping_row_locks.init();
+  bool matching_shared_lock_found = false;
+
+  if (is_write_request)
+    iterate_and_get_overlapping_row_locks(lkr, &overlapping_row_locks);
+  else {
+    matching_shared_lock_found = iterate_and_get_overlapping_row_locks2(
+        lkr, left_key, right_key, &m_cmp, txnid, &overlapping_row_locks);
+    // psergey-todo: what to do now? So, we have figured we have just one
+    // shareable lock. Need to add us into it as an owner but the lock
+    // pointer cannot be kept?
+    // A: use find_node_with_overlapping_child(key_range, nullptr);
+    //  then, add ourselves to the owner list.
+    // Dont' foreget to release the subtree after that.
+  }
+
+  if (matching_shared_lock_found) {
+    // there is just one non-confliting matching shared lock.
+    //  we are hilding a lock on it (see acquire() call above).
+    //  we need to modify it to indicate there is another locker...
+    if (lkr->add_shared_owner(requested_range, txnid)) {
+      // Pretend shared lock uses as much memory.
+      row_lock new_lock = {.range = requested_range,
+                           .txnid = txnid,
+                           .is_shared = false,
+                           .owners = nullptr};
+      uint64_t mem_used = row_lock_size_in_tree(new_lock);
+      if (m_mgr) {
+        m_mgr->note_mem_used(mem_used);
+      }
+    }
+    requested_range.destroy();
+    overlapping_row_locks.deinit();
+    return 0;
+  }
+
+  size_t num_overlapping_row_locks = overlapping_row_locks.get_size();
+
+  // if any overlapping row locks conflict with this request, bail out.
+
+  bool conflicts_exist =
+      determine_conflicting_txnids(overlapping_row_locks, txnid, conflicts);
+  if (!conflicts_exist) {
+    // there are no conflicts, so all of the overlaps are for the requesting
+    // txnid. so, we must consolidate all existing overlapping ranges and the
+    // requested range into one dominating range. then we insert the dominating
+    // range.
+    bool all_shared = !is_write_request;
+    for (size_t i = 0; i < num_overlapping_row_locks; i++) {
+      row_lock overlapping_lock = overlapping_row_locks.fetch_unchecked(i);
+      invariant(overlapping_lock.txnid == txnid);
+      requested_range.extend(m_cmp, overlapping_lock.range);
+      remove_row_lock_from_tree(lkr, overlapping_lock, TXNID_ANY, m_mgr);
+      all_shared = all_shared && overlapping_lock.is_shared;
+    }
+
+    row_lock new_lock = {.range = requested_range,
+                         .txnid = txnid,
+                         .is_shared = all_shared,
+                         .owners = nullptr};
+    insert_row_lock_into_tree(lkr, new_lock, m_mgr);
+  } else {
+    r = DB_LOCK_NOTGRANTED;
+  }
+
+  requested_range.destroy();
+  overlapping_row_locks.deinit();
+  return r;
+}
+
+// acquire a lock in the given key range, inclusive. if successful,
+// return 0. otherwise, populate the conflicts txnid_set with the set of
+// transactions that conflict with this request.
+int locktree::acquire_lock(bool is_write_request, TXNID txnid,
+                           const DBT *left_key, const DBT *right_key,
+                           txnid_set *conflicts) {
+  int r = 0;
+
+  // we are only supporting write locks for simplicity
+  // invariant(is_write_request);
+
+  // acquire and prepare a locked keyrange over the requested range.
+  // prepare is a serialzation point, so we take the opportunity to
+  // try the single txnid optimization first.
+  concurrent_tree::locked_keyrange lkr;
+  lkr.prepare(m_rangetree);
+
+  bool acquired =
+      sto_try_acquire(&lkr, txnid, left_key, right_key, is_write_request);
+  if (!acquired) {
+    r = acquire_lock_consolidated(&lkr, txnid, left_key, right_key,
+                                  is_write_request, conflicts);
+  }
+
+  lkr.release();
+  return r;
+}
+
+int locktree::try_acquire_lock(bool is_write_request, TXNID txnid,
+                               const DBT *left_key, const DBT *right_key,
+                               txnid_set *conflicts, bool big_txn) {
+  // All ranges in the locktree must have left endpoints <= right endpoints.
+  // Range comparisons rely on this fact, so we make a paranoid invariant here.
+  paranoid_invariant(m_cmp(left_key, right_key) <= 0);
+  int r = m_mgr == nullptr ? 0 : m_mgr->check_current_lock_constraints(big_txn);
+  if (r == 0) {
+    r = acquire_lock(is_write_request, txnid, left_key, right_key, conflicts);
+  }
+  return r;
+}
+
+// the locktree silently upgrades read locks to write locks for simplicity
+int locktree::acquire_read_lock(TXNID txnid, const DBT *left_key,
+                                const DBT *right_key, txnid_set *conflicts,
+                                bool big_txn) {
+  return try_acquire_lock(false, txnid, left_key, right_key, conflicts,
+                          big_txn);
+}
+
+int locktree::acquire_write_lock(TXNID txnid, const DBT *left_key,
+                                 const DBT *right_key, txnid_set *conflicts,
+                                 bool big_txn) {
+  return try_acquire_lock(true, txnid, left_key, right_key, conflicts, big_txn);
+}
+
+// typedef void (*dump_callback)(void *cdata, const DBT *left, const DBT *right,
+// TXNID txnid);
+void locktree::dump_locks(void *cdata, dump_callback cb) {
+  concurrent_tree::locked_keyrange lkr;
+  keyrange range;
+  range.create(toku_dbt_negative_infinity(), toku_dbt_positive_infinity());
+
+  lkr.prepare(m_rangetree);
+  lkr.acquire(range);
+
+  TXNID sto_txn;
+  if ((sto_txn = toku_unsafe_fetch(m_sto_txnid)) != TXNID_NONE) {
+    // insert all of the ranges from the single txnid buffer into a new rangtree
+    range_buffer::iterator iter(&m_sto_buffer);
+    range_buffer::iterator::record rec;
+    while (iter.current(&rec)) {
+      (*cb)(cdata, rec.get_left_key(), rec.get_right_key(), sto_txn,
+            !rec.get_exclusive_flag(), nullptr);
+      iter.next();
+    }
+  } else {
+    GrowableArray<row_lock> all_locks;
+    all_locks.init();
+    iterate_and_get_overlapping_row_locks(&lkr, &all_locks);
+
+    const size_t n_locks = all_locks.get_size();
+    for (size_t i = 0; i < n_locks; i++) {
+      const row_lock lock = all_locks.fetch_unchecked(i);
+      (*cb)(cdata, lock.range.get_left_key(), lock.range.get_right_key(),
+            lock.txnid, lock.is_shared, lock.owners);
+    }
+    all_locks.deinit();
+  }
+  lkr.release();
+  range.destroy();
+}
+
+void locktree::get_conflicts(bool is_write_request, TXNID txnid,
+                             const DBT *left_key, const DBT *right_key,
+                             txnid_set *conflicts) {
+  // because we only support write locks, ignore this bit for now.
+  (void)is_write_request;
+
+  // preparing and acquire a locked keyrange over the range
+  keyrange range;
+  range.create(left_key, right_key);
+  concurrent_tree::locked_keyrange lkr;
+  lkr.prepare(m_rangetree);
+  lkr.acquire(range);
+
+  // copy out the set of overlapping row locks and determine the conflicts
+  GrowableArray<row_lock> overlapping_row_locks;
+  overlapping_row_locks.init();
+  iterate_and_get_overlapping_row_locks(&lkr, &overlapping_row_locks);
+
+  // we don't care if conflicts exist. we just want the conflicts set populated.
+  (void)determine_conflicting_txnids(overlapping_row_locks, txnid, conflicts);
+
+  lkr.release();
+  overlapping_row_locks.deinit();
+  range.destroy();
+}
+
+// Effect:
+//  For each range in the lock tree that overlaps the given range and has
+//  the given txnid, remove it.
+// Rationale:
+//  In the common case, there is only the range [left_key, right_key] and
+//  it is associated with txnid, so this is a single tree delete.
+//
+//  However, consolidation and escalation change the objects in the tree
+//  without telling the txn anything.  In this case, the txn may own a
+//  large range lock that represents its ownership of many smaller range
+//  locks.  For example, the txn may think it owns point locks on keys 1,
+//  2, and 3, but due to escalation, only the object [1,3] exists in the
+//  tree.
+//
+//  The first call for a small lock will remove the large range lock, and
+//  the rest of the calls should do nothing.  After the first release,
+//  another thread can acquire one of the locks that the txn thinks it
+//  still owns.  That's ok, because the txn doesn't want it anymore (it
+//  unlocks everything at once), but it may find a lock that it does not
+//  own.
+//
+//  In our example, the txn unlocks key 1, which actually removes the
+//  whole lock [1,3].  Now, someone else can lock 2 before our txn gets
+//  around to unlocking 2, so we should not remove that lock.
+void locktree::remove_overlapping_locks_for_txnid(TXNID txnid,
+                                                  const DBT *left_key,
+                                                  const DBT *right_key) {
+  keyrange release_range;
+  release_range.create(left_key, right_key);
+
+  // acquire and prepare a locked keyrange over the release range
+  concurrent_tree::locked_keyrange lkr;
+  lkr.prepare(m_rangetree);
+  lkr.acquire(release_range);
+
+  // copy out the set of overlapping row locks.
+  GrowableArray<row_lock> overlapping_row_locks;
+  overlapping_row_locks.init();
+  iterate_and_get_overlapping_row_locks(&lkr, &overlapping_row_locks);
+  size_t num_overlapping_row_locks = overlapping_row_locks.get_size();
+
+  for (size_t i = 0; i < num_overlapping_row_locks; i++) {
+    row_lock lock = overlapping_row_locks.fetch_unchecked(i);
+    // If this isn't our lock, that's ok, just don't remove it.
+    // See rationale above.
+    // psergey-todo: for shared locks, just remove ourselves from the
+    //               owners.
+    if (lock.txnid == txnid || (lock.owners && lock.owners->contains(txnid))) {
+      remove_row_lock_from_tree(&lkr, lock, txnid, m_mgr);
+    }
+  }
+
+  lkr.release();
+  overlapping_row_locks.deinit();
+  release_range.destroy();
+}
+
+bool locktree::sto_txnid_is_valid_unsafe(void) const {
+  return toku_unsafe_fetch(m_sto_txnid) != TXNID_NONE;
+}
+
+int locktree::sto_get_score_unsafe(void) const {
+  return toku_unsafe_fetch(m_sto_score);
+}
+
+bool locktree::sto_try_release(TXNID txnid) {
+  bool released = false;
+  if (toku_unsafe_fetch(m_sto_txnid) != TXNID_NONE) {
+    // check the bit again with a prepared locked keyrange,
+    // which protects the optimization bits and rangetree data
+    concurrent_tree::locked_keyrange lkr;
+    lkr.prepare(m_rangetree);
+    if (m_sto_txnid != TXNID_NONE) {
+      // this txnid better be the single txnid on this locktree,
+      // or else we are in big trouble (meaning the logic is broken)
+      invariant(m_sto_txnid == txnid);
+      invariant(m_rangetree->is_empty());
+      sto_end();
+      released = true;
+    }
+    lkr.release();
+  }
+  return released;
+}
+
+// release all of the locks for a txnid whose endpoints are pairs
+// in the given range buffer.
+void locktree::release_locks(TXNID txnid, const range_buffer *ranges,
+                             bool all_trx_locks_hint) {
+  // try the single txn optimization. if it worked, then all of the
+  // locks are already released, otherwise we need to do it here.
+  bool released;
+  if (all_trx_locks_hint) {
+    // This will release all of the locks the transaction is holding
+    released = sto_try_release(txnid);
+  } else {
+    /*
+      psergey: we are asked to release *Some* of the locks the transaction
+      is holding.
+      We could try doing that without leaving the STO mode, but right now,
+      the easiest way is to exit the STO mode and let the non-STO code path
+      handle it.
+    */
+    if (toku_unsafe_fetch(m_sto_txnid) != TXNID_NONE) {
+      // check the bit again with a prepared locked keyrange,
+      // which protects the optimization bits and rangetree data
+      concurrent_tree::locked_keyrange lkr;
+      lkr.prepare(m_rangetree);
+      if (m_sto_txnid != TXNID_NONE) {
+        sto_end_early(&lkr);
+      }
+      lkr.release();
+    }
+    released = false;
+  }
+  if (!released) {
+    range_buffer::iterator iter(ranges);
+    range_buffer::iterator::record rec;
+    while (iter.current(&rec)) {
+      const DBT *left_key = rec.get_left_key();
+      const DBT *right_key = rec.get_right_key();
+      // All ranges in the locktree must have left endpoints <= right endpoints.
+      // Range comparisons rely on this fact, so we make a paranoid invariant
+      // here.
+      paranoid_invariant(m_cmp(left_key, right_key) <= 0);
+      remove_overlapping_locks_for_txnid(txnid, left_key, right_key);
+      iter.next();
+    }
+    // Increase the sto score slightly. Eventually it will hit
+    // the threshold and we'll try the optimization again. This
+    // is how a previously multithreaded system transitions into
+    // a single threaded system that benefits from the optimization.
+    if (toku_unsafe_fetch(m_sto_score) < STO_SCORE_THRESHOLD) {
+      toku_sync_fetch_and_add(&m_sto_score, 1);
+    }
+  }
+}
+
+// iterate over a locked keyrange and extract copies of the first N
+// row locks, storing each one into the given array of size N,
+// then removing each extracted lock from the locked keyrange.
+static int extract_first_n_row_locks(concurrent_tree::locked_keyrange *lkr,
+                                     locktree_manager *mgr, row_lock *row_locks,
+                                     int num_to_extract) {
+  struct extract_fn_obj {
+    int num_extracted;
+    int num_to_extract;
+    row_lock *row_locks;
+    bool fn(const keyrange &range, TXNID txnid, bool is_shared,
+            TxnidVector *owners) {
+      if (num_extracted < num_to_extract) {
+        row_lock lock;
+        lock.range.create_copy(range);
+        lock.txnid = txnid;
+        lock.is_shared = is_shared;
+        // deep-copy the set of owners:
+        if (owners)
+          lock.owners = new TxnidVector(*owners);
+        else
+          lock.owners = nullptr;
+        row_locks[num_extracted++] = lock;
+        return true;
+      } else {
+        return false;
+      }
+    }
+  } extract_fn;
+
+  extract_fn.row_locks = row_locks;
+  extract_fn.num_to_extract = num_to_extract;
+  extract_fn.num_extracted = 0;
+  lkr->iterate(&extract_fn);
+
+  // now that the ranges have been copied out, complete
+  // the extraction by removing the ranges from the tree.
+  // use remove_row_lock_from_tree() so we properly track the
+  // amount of memory and number of locks freed.
+  int num_extracted = extract_fn.num_extracted;
+  invariant(num_extracted <= num_to_extract);
+  for (int i = 0; i < num_extracted; i++) {
+    remove_row_lock_from_tree(lkr, row_locks[i], TXNID_ANY, mgr);
+  }
+
+  return num_extracted;
+}
+
+// Store each newly escalated lock in a range buffer for appropriate txnid.
+// We'll rebuild the locktree by iterating over these ranges, and then we
+// can pass back each txnid/buffer pair individually through a callback
+// to notify higher layers that locks have changed.
+struct txnid_range_buffer {
+  TXNID txnid;
+  range_buffer buffer;
+
+  static int find_by_txnid(struct txnid_range_buffer *const &other_buffer,
+                           const TXNID &txnid) {
+    if (txnid < other_buffer->txnid) {
+      return -1;
+    } else if (other_buffer->txnid == txnid) {
+      return 0;
+    } else {
+      return 1;
+    }
+  }
+};
+
+// escalate the locks in the locktree by merging adjacent
+// locks that have the same txnid into one larger lock.
+//
+// if there's only one txnid in the locktree then this
+// approach works well. if there are many txnids and each
+// has locks in a random/alternating order, then this does
+// not work so well.
+void locktree::escalate(lt_escalate_cb after_escalate_callback,
+                        void *after_escalate_callback_extra) {
+  omt<struct txnid_range_buffer *, struct txnid_range_buffer *> range_buffers;
+  range_buffers.create();
+
+  // prepare and acquire a locked keyrange on the entire locktree
+  concurrent_tree::locked_keyrange lkr;
+  keyrange infinite_range = keyrange::get_infinite_range();
+  lkr.prepare(m_rangetree);
+  lkr.acquire(infinite_range);
+
+  // if we're in the single txnid optimization, simply call it off.
+  // if you have to run escalation, you probably don't care about
+  // the optimization anyway, and this makes things easier.
+  if (m_sto_txnid != TXNID_NONE) {
+    // We are already accounting for this escalation time and
+    // count, so don't do it for sto_end_early too.
+    sto_end_early_no_accounting(&lkr);
+  }
+
+  // extract and remove batches of row locks from the locktree
+  int num_extracted;
+  const int num_row_locks_per_batch = 128;
+  row_lock *XCALLOC_N(num_row_locks_per_batch, extracted_buf);
+
+  // we always remove the "first" n because we are removing n
+  // each time we do an extraction. so this loops until its empty.
+  while ((num_extracted = extract_first_n_row_locks(
+              &lkr, m_mgr, extracted_buf, num_row_locks_per_batch)) > 0) {
+    int current_index = 0;
+    while (current_index < num_extracted) {
+      // every batch of extracted locks is in range-sorted order. search
+      // through them and merge adjacent locks with the same txnid into
+      // one dominating lock and save it to a set of escalated locks.
+      //
+      // first, find the index of the next row lock that
+      //  - belongs to a different txnid, or
+      //  - belongs to several txnids, or
+      //  - is a shared lock (we could potentially merge those but
+      //    currently we don't), or
+      //  - is across a lock escalation barrier.
+      int next_txnid_index = current_index + 1;
+
+      while (next_txnid_index < num_extracted &&
+             (extracted_buf[current_index].txnid ==
+              extracted_buf[next_txnid_index].txnid) &&
+             !extracted_buf[next_txnid_index].is_shared &&
+             !extracted_buf[next_txnid_index].owners &&
+             !m_escalation_barrier(
+                 extracted_buf[current_index].range.get_right_key(),
+                 extracted_buf[next_txnid_index].range.get_left_key(),
+                 m_escalation_barrier_arg)) {
+        next_txnid_index++;
+      }
+
+      // Create an escalated range for the current txnid that dominates
+      // each range between the current indext and the next txnid's index.
+      // const TXNID current_txnid = extracted_buf[current_index].txnid;
+      const DBT *escalated_left_key =
+          extracted_buf[current_index].range.get_left_key();
+      const DBT *escalated_right_key =
+          extracted_buf[next_txnid_index - 1].range.get_right_key();
+
+      // Try to find a range buffer for the current txnid. Create one if it
+      // doesn't exist. Then, append the new escalated range to the buffer. (If
+      // a lock is shared by multiple txnids, append it each of txnid's lists)
+      TxnidVector *owners_ptr;
+      TxnidVector singleton_owner;
+      if (extracted_buf[current_index].owners)
+        owners_ptr = extracted_buf[current_index].owners;
+      else {
+        singleton_owner.insert(extracted_buf[current_index].txnid);
+        owners_ptr = &singleton_owner;
+      }
+
+      for (auto cur_txnid : *owners_ptr) {
+        uint32_t idx;
+        struct txnid_range_buffer *existing_range_buffer;
+        int r =
+            range_buffers.find_zero<TXNID, txnid_range_buffer::find_by_txnid>(
+                cur_txnid, &existing_range_buffer, &idx);
+        if (r == DB_NOTFOUND) {
+          struct txnid_range_buffer *XMALLOC(new_range_buffer);
+          new_range_buffer->txnid = cur_txnid;
+          new_range_buffer->buffer.create();
+          new_range_buffer->buffer.append(
+              escalated_left_key, escalated_right_key,
+              !extracted_buf[current_index].is_shared);
+          range_buffers.insert_at(new_range_buffer, idx);
+        } else {
+          invariant_zero(r);
+          invariant(existing_range_buffer->txnid == cur_txnid);
+          existing_range_buffer->buffer.append(
+              escalated_left_key, escalated_right_key,
+              !extracted_buf[current_index].is_shared);
+        }
+      }
+
+      current_index = next_txnid_index;
+    }
+
+    // destroy the ranges copied during the extraction
+    for (int i = 0; i < num_extracted; i++) {
+      delete extracted_buf[i].owners;
+      extracted_buf[i].range.destroy();
+    }
+  }
+  toku_free(extracted_buf);
+
+  // Rebuild the locktree from each range in each range buffer,
+  // then notify higher layers that the txnid's locks have changed.
+  //
+  // (shared locks: if a lock was initially shared between transactions TRX1,
+  //  TRX2, etc, we will now try to acquire it acting on behalf on TRX1, on
+  //  TRX2, etc.  This will succeed and an identical shared lock will be
+  //  constructed)
+
+  invariant(m_rangetree->is_empty());
+  const uint32_t num_range_buffers = range_buffers.size();
+  for (uint32_t i = 0; i < num_range_buffers; i++) {
+    struct txnid_range_buffer *current_range_buffer;
+    int r = range_buffers.fetch(i, &current_range_buffer);
+    invariant_zero(r);
+    if (r == EINVAL)  // Shouldn't happen, avoid compiler warning
+      continue;
+
+    const TXNID current_txnid = current_range_buffer->txnid;
+    range_buffer::iterator iter(&current_range_buffer->buffer);
+    range_buffer::iterator::record rec;
+    while (iter.current(&rec)) {
+      keyrange range;
+      range.create(rec.get_left_key(), rec.get_right_key());
+      row_lock lock = {.range = range,
+                       .txnid = current_txnid,
+                       .is_shared = !rec.get_exclusive_flag(),
+                       .owners = nullptr};
+      insert_row_lock_into_tree(&lkr, lock, m_mgr);
+      iter.next();
+    }
+
+    // Notify higher layers that locks have changed for the current txnid
+    if (after_escalate_callback) {
+      after_escalate_callback(current_txnid, this, current_range_buffer->buffer,
+                              after_escalate_callback_extra);
+    }
+    current_range_buffer->buffer.destroy();
+  }
+
+  while (range_buffers.size() > 0) {
+    struct txnid_range_buffer *buffer;
+    int r = range_buffers.fetch(0, &buffer);
+    invariant_zero(r);
+    r = range_buffers.delete_at(0);
+    invariant_zero(r);
+    toku_free(buffer);
+  }
+  range_buffers.destroy();
+
+  lkr.release();
+}
+
+void *locktree::get_userdata(void) const { return m_userdata; }
+
+void locktree::set_userdata(void *userdata) { m_userdata = userdata; }
+
+struct lt_lock_request_info *locktree::get_lock_request_info(void) {
+  return &m_lock_request_info;
+}
+
+void locktree::set_comparator(const comparator &cmp) { m_cmp.inherit(cmp); }
+
+locktree_manager *locktree::get_manager(void) const { return m_mgr; }
+
+int locktree::compare(const locktree *lt) const {
+  if (m_dict_id.dictid < lt->m_dict_id.dictid) {
+    return -1;
+  } else if (m_dict_id.dictid == lt->m_dict_id.dictid) {
+    return 0;
+  } else {
+    return 1;
+  }
+}
+
+DICTIONARY_ID locktree::get_dict_id() const { return m_dict_id; }
+
+} /* namespace toku */
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/locktree.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/locktree.h
new file mode 100644
index 000000000..f0f4b042d
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/locktree.h
@@ -0,0 +1,580 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include <atomic>
+
+#include "../db.h"
+#include "../ft/comparator.h"
+#include "../portability/toku_external_pthread.h"
+#include "../portability/toku_pthread.h"
+#include "../portability/toku_time.h"
+// PORT #include <ft/ft-ops.h>  // just for DICTIONARY_ID..
+// PORT: ft-status for LTM_STATUS:
+#include "../ft/ft-status.h"
+
+struct DICTIONARY_ID {
+  uint64_t dictid;
+};
+
+#include "../util/omt.h"
+#include "range_buffer.h"
+#include "txnid_set.h"
+#include "wfg.h"
+
+namespace toku {
+
+class locktree;
+class locktree_manager;
+class lock_request;
+class concurrent_tree;
+
+typedef int (*lt_create_cb)(locktree *lt, void *extra);
+typedef void (*lt_destroy_cb)(locktree *lt);
+typedef void (*lt_escalate_cb)(TXNID txnid, const locktree *lt,
+                               const range_buffer &buffer, void *extra);
+
+typedef bool (*lt_escalation_barrier_check_func)(const DBT *a, const DBT *b,
+                                                 void *extra);
+
+struct lt_counters {
+  uint64_t wait_count, wait_time;
+  uint64_t long_wait_count, long_wait_time;
+  uint64_t timeout_count;
+
+  void add(const lt_counters &rhs) {
+    wait_count += rhs.wait_count;
+    wait_time += rhs.wait_time;
+    long_wait_count += rhs.long_wait_count;
+    long_wait_time += rhs.long_wait_time;
+    timeout_count += rhs.timeout_count;
+  }
+};
+
+// Lock request state for some locktree
+struct lt_lock_request_info {
+  omt<lock_request *> pending_lock_requests;
+  std::atomic_bool pending_is_empty;
+  toku_external_mutex_t mutex;
+  bool should_retry_lock_requests;
+  lt_counters counters;
+  std::atomic_ullong retry_want;
+  unsigned long long retry_done;
+  toku_mutex_t retry_mutex;
+  toku_cond_t retry_cv;
+  bool running_retry;
+
+  void init(toku_external_mutex_factory_t mutex_factory);
+  void destroy(void);
+};
+
+// The locktree manager manages a set of locktrees, one for each open
+// dictionary. Locktrees are retrieved from the manager. When they are no
+// longer needed, they are be released by the user.
+class locktree_manager {
+ public:
+  // param: create_cb, called just after a locktree is first created.
+  //        destroy_cb, called just before a locktree is destroyed.
+  //        escalate_cb, called after a locktree is escalated (with extra
+  //        param)
+  void create(lt_create_cb create_cb, lt_destroy_cb destroy_cb,
+              lt_escalate_cb escalate_cb, void *extra,
+              toku_external_mutex_factory_t mutex_factory_arg);
+
+  void destroy(void);
+
+  size_t get_max_lock_memory(void);
+
+  int set_max_lock_memory(size_t max_lock_memory);
+
+  // effect: Get a locktree from the manager. If a locktree exists with the
+  // given
+  //         dict_id, it is referenced and then returned. If one did not exist,
+  //         it is created. It will use the comparator for comparing keys. The
+  //         on_create callback (passed to locktree_manager::create()) will be
+  //         called with the given extra parameter.
+  locktree *get_lt(DICTIONARY_ID dict_id, const comparator &cmp,
+                   void *on_create_extra);
+
+  void reference_lt(locktree *lt);
+
+  // effect: Releases one reference on a locktree. If the reference count
+  // transitions
+  //         to zero, the on_destroy callback is called before it gets
+  //         destroyed.
+  void release_lt(locktree *lt);
+
+  void get_status(LTM_STATUS status);
+
+  // effect: calls the iterate function on each pending lock request
+  // note: holds the manager's mutex
+  typedef int (*lock_request_iterate_callback)(DICTIONARY_ID dict_id,
+                                               TXNID txnid, const DBT *left_key,
+                                               const DBT *right_key,
+                                               TXNID blocking_txnid,
+                                               uint64_t start_time,
+                                               void *extra);
+  int iterate_pending_lock_requests(lock_request_iterate_callback cb,
+                                    void *extra);
+
+  // effect: Determines if too many locks or too much memory is being used,
+  //         Runs escalation on the manager if so.
+  // param: big_txn, if the current transaction is 'big' (has spilled rollback
+  // logs) returns: 0 if there enough resources to create a new lock, or
+  // TOKUDB_OUT_OF_LOCKS
+  //          if there are not enough resources and lock escalation failed to
+  //          free up enough resources for a new lock.
+  int check_current_lock_constraints(bool big_txn);
+
+  bool over_big_threshold(void);
+
+  void note_mem_used(uint64_t mem_used);
+
+  void note_mem_released(uint64_t mem_freed);
+
+  bool out_of_locks(void) const;
+
+  // Escalate all locktrees
+  void escalate_all_locktrees(void);
+
+  // Escalate a set of locktrees
+  void escalate_locktrees(locktree **locktrees, int num_locktrees);
+
+  // effect: calls the private function run_escalation(), only ok to
+  //         do for tests.
+  // rationale: to get better stress test coverage, we want a way to
+  //            deterministicly trigger lock escalation.
+  void run_escalation_for_test(void);
+  void run_escalation(void);
+
+  // Add time t to the escalator's wait time statistics
+  void add_escalator_wait_time(uint64_t t);
+
+  void kill_waiter(void *extra);
+
+ private:
+  static const uint64_t DEFAULT_MAX_LOCK_MEMORY = 64L * 1024 * 1024;
+
+  // tracks the current number of locks and lock memory
+  uint64_t m_max_lock_memory;
+  uint64_t m_current_lock_memory;
+
+  struct lt_counters m_lt_counters;
+
+  // the create and destroy callbacks for the locktrees
+  lt_create_cb m_lt_create_callback;
+  lt_destroy_cb m_lt_destroy_callback;
+  lt_escalate_cb m_lt_escalate_callback;
+  void *m_lt_escalate_callback_extra;
+
+  omt<locktree *> m_locktree_map;
+
+  toku_external_mutex_factory_t mutex_factory;
+
+  // the manager's mutex protects the locktree map
+  toku_mutex_t m_mutex;
+
+  void mutex_lock(void);
+
+  void mutex_unlock(void);
+
+  // Manage the set of open locktrees
+  locktree *locktree_map_find(const DICTIONARY_ID &dict_id);
+  void locktree_map_put(locktree *lt);
+  void locktree_map_remove(locktree *lt);
+
+  static int find_by_dict_id(locktree *const &lt, const DICTIONARY_ID &dict_id);
+
+  void escalator_init(void);
+  void escalator_destroy(void);
+
+  // statistics about lock escalation.
+  toku_mutex_t m_escalation_mutex;
+  uint64_t m_escalation_count;
+  tokutime_t m_escalation_time;
+  uint64_t m_escalation_latest_result;
+  uint64_t m_wait_escalation_count;
+  uint64_t m_wait_escalation_time;
+  uint64_t m_long_wait_escalation_count;
+  uint64_t m_long_wait_escalation_time;
+
+  // the escalator coordinates escalation on a set of locktrees for a bunch of
+  // threads
+  class locktree_escalator {
+   public:
+    void create(void);
+    void destroy(void);
+    void run(locktree_manager *mgr, void (*escalate_locktrees_fun)(void *extra),
+             void *extra);
+
+   private:
+    toku_mutex_t m_escalator_mutex;
+    toku_cond_t m_escalator_done;
+    bool m_escalator_running;
+  };
+
+  locktree_escalator m_escalator;
+
+  friend class manager_unit_test;
+};
+
+// A locktree represents the set of row locks owned by all transactions
+// over an open dictionary. Read and write ranges are represented as
+// a left and right key which are compared with the given comparator
+//
+// Locktrees are not created and destroyed by the user. Instead, they are
+// referenced and released using the locktree manager.
+//
+// A sample workflow looks like this:
+// - Create a manager.
+// - Get a locktree by dictionaroy id from the manager.
+// - Perform read/write lock acquision on the locktree, add references to
+//   the locktree using the manager, release locks, release references, etc.
+// - ...
+// - Release the final reference to the locktree. It will be destroyed.
+// - Destroy the manager.
+class locktree {
+ public:
+  // effect: Creates a locktree
+  void create(locktree_manager *mgr, DICTIONARY_ID dict_id,
+              const comparator &cmp,
+              toku_external_mutex_factory_t mutex_factory);
+
+  void destroy(void);
+
+  // For thread-safe, external reference counting
+  void add_reference(void);
+
+  // requires: the reference count is > 0
+  // returns: the reference count, after decrementing it by one
+  uint32_t release_reference(void);
+
+  // returns: the current reference count
+  uint32_t get_reference_count(void);
+
+  // effect: Attempts to grant a read lock for the range of keys between
+  // [left_key, right_key]. returns: If the lock cannot be granted, return
+  // DB_LOCK_NOTGRANTED, and populate the
+  //          given conflicts set with the txnids that hold conflicting locks in
+  //          the range. If the locktree cannot create more locks, return
+  //          TOKUDB_OUT_OF_LOCKS.
+  // note: Read locks cannot be shared between txnids, as one would expect.
+  //       This is for simplicity since read locks are rare in MySQL.
+  int acquire_read_lock(TXNID txnid, const DBT *left_key, const DBT *right_key,
+                        txnid_set *conflicts, bool big_txn);
+
+  // effect: Attempts to grant a write lock for the range of keys between
+  // [left_key, right_key]. returns: If the lock cannot be granted, return
+  // DB_LOCK_NOTGRANTED, and populate the
+  //          given conflicts set with the txnids that hold conflicting locks in
+  //          the range. If the locktree cannot create more locks, return
+  //          TOKUDB_OUT_OF_LOCKS.
+  int acquire_write_lock(TXNID txnid, const DBT *left_key, const DBT *right_key,
+                         txnid_set *conflicts, bool big_txn);
+
+  // effect: populate the conflicts set with the txnids that would preventing
+  //         the given txnid from getting a lock on [left_key, right_key]
+  void get_conflicts(bool is_write_request, TXNID txnid, const DBT *left_key,
+                     const DBT *right_key, txnid_set *conflicts);
+
+  // effect: Release all of the lock ranges represented by the range buffer for
+  // a txnid.
+  void release_locks(TXNID txnid, const range_buffer *ranges,
+                     bool all_trx_locks_hint = false);
+
+  // effect: Runs escalation on this locktree
+  void escalate(lt_escalate_cb after_escalate_callback, void *extra);
+
+  // returns: The userdata associated with this locktree, or null if it has not
+  // been set.
+  void *get_userdata(void) const;
+
+  void set_userdata(void *userdata);
+
+  locktree_manager *get_manager(void) const;
+
+  void set_comparator(const comparator &cmp);
+
+  // Set the user-provided Lock Escalation Barrier check function and its
+  // argument
+  //
+  // Lock Escalation Barrier limits the scope of Lock Escalation.
+  // For two keys A and B (such that A < B),
+  // escalation_barrier_check_func(A, B)==true means that there's a lock
+  // escalation barrier between A and B, and lock escalation is not allowed to
+  // bridge the gap between A and B.
+  //
+  // This method sets the user-provided barrier check function and its
+  // parameter.
+  void set_escalation_barrier_func(lt_escalation_barrier_check_func func,
+                                   void *extra);
+
+  int compare(const locktree *lt) const;
+
+  DICTIONARY_ID get_dict_id() const;
+
+  // Private info struct for storing pending lock request state.
+  // Only to be used by lock requests. We store it here as
+  // something less opaque than usual to strike a tradeoff between
+  // abstraction and code complexity. It is still fairly abstract
+  // since the lock_request object is opaque
+  struct lt_lock_request_info *get_lock_request_info(void);
+
+  typedef void (*dump_callback)(void *cdata, const DBT *left, const DBT *right,
+                                TXNID txnid, bool is_shared,
+                                TxnidVector *owners);
+  void dump_locks(void *cdata, dump_callback cb);
+
+ private:
+  locktree_manager *m_mgr;
+  DICTIONARY_ID m_dict_id;
+  uint32_t m_reference_count;
+
+  // Since the memory referenced by this comparator is not owned by the
+  // locktree, the user must guarantee it will outlive the locktree.
+  //
+  // The ydb API accomplishes this by opening an ft_handle in the on_create
+  // callback, which will keep the underlying FT (and its descriptor) in memory
+  // for as long as the handle is open. The ft_handle is stored opaquely in the
+  // userdata pointer below. see locktree_manager::get_lt w/ on_create_extra
+  comparator m_cmp;
+
+  lt_escalation_barrier_check_func m_escalation_barrier;
+  void *m_escalation_barrier_arg;
+
+  concurrent_tree *m_rangetree;
+
+  void *m_userdata;
+  struct lt_lock_request_info m_lock_request_info;
+
+  // psergey-todo:
+  //  Each transaction also keeps a list of ranges it has locked.
+  //  So, when a transaction is running in STO mode, two identical
+  //  lists are kept: the STO lock list and transaction's owned locks
+  //  list. Why can't we do with just one list?
+
+  // The following fields and members prefixed with "sto_" are for
+  // the single txnid optimization, intended to speed up the case
+  // when only one transaction is using the locktree. If we know
+  // the locktree has only one transaction, then acquiring locks
+  // takes O(1) work and releasing all locks takes O(1) work.
+  //
+  // How do we know that the locktree only has a single txnid?
+  // What do we do if it does?
+  //
+  // When a txn with txnid T requests a lock:
+  // - If the tree is empty, the optimization is possible. Set the single
+  // txnid to T, and insert the lock range into the buffer.
+  // - If the tree is not empty, check if the single txnid is T. If so,
+  // append the lock range to the buffer. Otherwise, migrate all of
+  // the locks in the buffer into the rangetree on behalf of txnid T,
+  // and invalid the single txnid.
+  //
+  // When a txn with txnid T releases its locks:
+  // - If the single txnid is valid, it must be for T. Destroy the buffer.
+  // - If it's not valid, release locks the normal way in the rangetree.
+  //
+  // To carry out the optimization we need to record a single txnid
+  // and a range buffer for each locktree, each protected by the root
+  // lock of the locktree's rangetree. The root lock for a rangetree
+  // is grabbed by preparing a locked keyrange on the rangetree.
+  TXNID m_sto_txnid;
+  range_buffer m_sto_buffer;
+
+  // The single txnid optimization speeds up the case when only one
+  // transaction is using the locktree. But it has the potential to
+  // hurt the case when more than one txnid exists.
+  //
+  // There are two things we need to do to make the optimization only
+  // optimize the case we care about, and not hurt the general case.
+  //
+  // Bound the worst-case latency for lock migration when the
+  // optimization stops working:
+  // - Idea: Stop the optimization and migrate immediate if we notice
+  // the single txnid has takes many locks in the range buffer.
+  // - Implementation: Enforce a max size on the single txnid range buffer.
+  // - Analysis: Choosing the perfect max value, M, is difficult to do
+  // without some feedback from the field. Intuition tells us that M should
+  // not be so small that the optimization is worthless, and it should not
+  // be so big that it's unreasonable to have to wait behind a thread doing
+  // the work of converting M buffer locks into rangetree locks.
+  //
+  // Prevent concurrent-transaction workloads from trying the optimization
+  // in vain:
+  // - Idea: Don't even bother trying the optimization if we think the
+  // system is in a concurrent-transaction state.
+  // - Implementation: Do something even simpler than detecting whether the
+  // system is in a concurent-transaction state. Just keep a "score" value
+  // and some threshold. If at any time the locktree is eligible for the
+  // optimization, only do it if the score is at this threshold. When you
+  // actually do the optimization but someone has to migrate locks in the buffer
+  // (expensive), then reset the score back to zero. Each time a txn
+  // releases locks, the score is incremented by 1.
+  // - Analysis: If you let the threshold be "C", then at most 1 / C txns will
+  // do the optimization in a concurrent-transaction system. Similarly, it
+  // takes at most C txns to start using the single txnid optimzation, which
+  // is good when the system transitions from multithreaded to single threaded.
+  //
+  // STO_BUFFER_MAX_SIZE:
+  //
+  // We choose the max value to be 1 million since most transactions are smaller
+  // than 1 million and we can create a rangetree of 1 million elements in
+  // less than a second. So we can be pretty confident that this threshold
+  // enables the optimization almost always, and prevents super pathological
+  // latency issues for the first lock taken by a second thread.
+  //
+  // STO_SCORE_THRESHOLD:
+  //
+  // A simple first guess at a good value for the score threshold is 100.
+  // By our analysis, we'd end up doing the optimization in vain for
+  // around 1% of all transactions, which seems reasonable. Further,
+  // if the system goes single threaded, it ought to be pretty quick
+  // for 100 transactions to go by, so we won't have to wait long before
+  // we start doing the single txind optimzation again.
+  static const int STO_BUFFER_MAX_SIZE = 50 * 1024;
+  static const int STO_SCORE_THRESHOLD = 100;
+  int m_sto_score;
+
+  // statistics about time spent ending the STO early
+  uint64_t m_sto_end_early_count;
+  tokutime_t m_sto_end_early_time;
+
+  // effect: begins the single txnid optimizaiton, setting m_sto_txnid
+  //         to the given txnid.
+  // requires: m_sto_txnid is invalid
+  void sto_begin(TXNID txnid);
+
+  // effect: append a range to the sto buffer
+  // requires: m_sto_txnid is valid
+  void sto_append(const DBT *left_key, const DBT *right_key,
+                  bool is_write_request);
+
+  // effect: ends the single txnid optimization, releaseing any memory
+  //         stored in the sto buffer, notifying the tracker, and
+  //         invalidating m_sto_txnid.
+  // requires: m_sto_txnid is valid
+  void sto_end(void);
+
+  // params: prepared_lkr is a void * to a prepared locked keyrange. see below.
+  // effect: ends the single txnid optimization early, migrating buffer locks
+  //         into the rangetree, calling sto_end(), and then setting the
+  //         sto_score back to zero.
+  // requires: m_sto_txnid is valid
+  void sto_end_early(void *prepared_lkr);
+  void sto_end_early_no_accounting(void *prepared_lkr);
+
+  // params: prepared_lkr is a void * to a prepared locked keyrange. we can't
+  // use
+  //         the real type because the compiler won't allow us to forward
+  //         declare concurrent_tree::locked_keyrange without including
+  //         concurrent_tree.h, which we cannot do here because it is a template
+  //         implementation.
+  // requires: the prepared locked keyrange is for the locktree's rangetree
+  // requires: m_sto_txnid is valid
+  // effect: migrates each lock in the single txnid buffer into the locktree's
+  //         rangetree, notifying the memory tracker as necessary.
+  void sto_migrate_buffer_ranges_to_tree(void *prepared_lkr);
+
+  // effect: If m_sto_txnid is valid, then release the txnid's locks
+  //         by ending the optimization.
+  // requires: If m_sto_txnid is valid, it is equal to the given txnid
+  // returns: True if locks were released for this txnid
+  bool sto_try_release(TXNID txnid);
+
+  // params: prepared_lkr is a void * to a prepared locked keyrange. see above.
+  // requires: the prepared locked keyrange is for the locktree's rangetree
+  // effect: If m_sto_txnid is valid and equal to the given txnid, then
+  // append a range onto the buffer. Otherwise, if m_sto_txnid is valid
+  //        but not equal to this txnid, then migrate the buffer's locks
+  //        into the rangetree and end the optimization, setting the score
+  //        back to zero.
+  // returns: true if the lock was acquired for this txnid
+  bool sto_try_acquire(void *prepared_lkr, TXNID txnid, const DBT *left_key,
+                       const DBT *right_key, bool is_write_request);
+
+  // Effect:
+  //  Provides a hook for a helgrind suppression.
+  // Returns:
+  //  true if m_sto_txnid is not TXNID_NONE
+  bool sto_txnid_is_valid_unsafe(void) const;
+
+  // Effect:
+  //  Provides a hook for a helgrind suppression.
+  // Returns:
+  //  m_sto_score
+  int sto_get_score_unsafe(void) const;
+
+  void remove_overlapping_locks_for_txnid(TXNID txnid, const DBT *left_key,
+                                          const DBT *right_key);
+
+  int acquire_lock_consolidated(void *prepared_lkr, TXNID txnid,
+                                const DBT *left_key, const DBT *right_key,
+                                bool is_write_request, txnid_set *conflicts);
+
+  int acquire_lock(bool is_write_request, TXNID txnid, const DBT *left_key,
+                   const DBT *right_key, txnid_set *conflicts);
+
+  int try_acquire_lock(bool is_write_request, TXNID txnid, const DBT *left_key,
+                       const DBT *right_key, txnid_set *conflicts,
+                       bool big_txn);
+
+  friend class locktree_unit_test;
+  friend class manager_unit_test;
+  friend class lock_request_unit_test;
+
+  // engine status reaches into the locktree to read some stats
+  friend void locktree_manager::get_status(LTM_STATUS status);
+};
+
+} /* namespace toku */
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/manager.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/manager.cc
new file mode 100644
index 000000000..4186182be
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/manager.cc
@@ -0,0 +1,527 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "../portability/toku_pthread.h"
+#include "../util/status.h"
+#include "lock_request.h"
+#include "locktree.h"
+
+namespace toku {
+
+void locktree_manager::create(lt_create_cb create_cb, lt_destroy_cb destroy_cb,
+                              lt_escalate_cb escalate_cb, void *escalate_extra,
+                              toku_external_mutex_factory_t mutex_factory_arg) {
+  mutex_factory = mutex_factory_arg;
+  m_max_lock_memory = DEFAULT_MAX_LOCK_MEMORY;
+  m_current_lock_memory = 0;
+
+  m_locktree_map.create();
+  m_lt_create_callback = create_cb;
+  m_lt_destroy_callback = destroy_cb;
+  m_lt_escalate_callback = escalate_cb;
+  m_lt_escalate_callback_extra = escalate_extra;
+  ZERO_STRUCT(m_mutex);
+  toku_mutex_init(manager_mutex_key, &m_mutex, nullptr);
+
+  ZERO_STRUCT(m_lt_counters);
+
+  escalator_init();
+}
+
+void locktree_manager::destroy(void) {
+  escalator_destroy();
+  invariant(m_current_lock_memory == 0);
+  invariant(m_locktree_map.size() == 0);
+  m_locktree_map.destroy();
+  toku_mutex_destroy(&m_mutex);
+}
+
+void locktree_manager::mutex_lock(void) { toku_mutex_lock(&m_mutex); }
+
+void locktree_manager::mutex_unlock(void) { toku_mutex_unlock(&m_mutex); }
+
+size_t locktree_manager::get_max_lock_memory(void) { return m_max_lock_memory; }
+
+int locktree_manager::set_max_lock_memory(size_t max_lock_memory) {
+  int r = 0;
+  mutex_lock();
+  if (max_lock_memory < m_current_lock_memory) {
+    r = EDOM;
+  } else {
+    m_max_lock_memory = max_lock_memory;
+  }
+  mutex_unlock();
+  return r;
+}
+
+int locktree_manager::find_by_dict_id(locktree *const &lt,
+                                      const DICTIONARY_ID &dict_id) {
+  if (lt->get_dict_id().dictid < dict_id.dictid) {
+    return -1;
+  } else if (lt->get_dict_id().dictid == dict_id.dictid) {
+    return 0;
+  } else {
+    return 1;
+  }
+}
+
+locktree *locktree_manager::locktree_map_find(const DICTIONARY_ID &dict_id) {
+  locktree *lt;
+  int r = m_locktree_map.find_zero<DICTIONARY_ID, find_by_dict_id>(dict_id, &lt,
+                                                                   nullptr);
+  return r == 0 ? lt : nullptr;
+}
+
+void locktree_manager::locktree_map_put(locktree *lt) {
+  int r = m_locktree_map.insert<DICTIONARY_ID, find_by_dict_id>(
+      lt, lt->get_dict_id(), nullptr);
+  invariant_zero(r);
+}
+
+void locktree_manager::locktree_map_remove(locktree *lt) {
+  uint32_t idx;
+  locktree *found_lt;
+  int r = m_locktree_map.find_zero<DICTIONARY_ID, find_by_dict_id>(
+      lt->get_dict_id(), &found_lt, &idx);
+  invariant_zero(r);
+  invariant(found_lt == lt);
+  r = m_locktree_map.delete_at(idx);
+  invariant_zero(r);
+}
+
+locktree *locktree_manager::get_lt(DICTIONARY_ID dict_id, const comparator &cmp,
+                                   void *on_create_extra) {
+  // hold the mutex around searching and maybe
+  // inserting into the locktree map
+  mutex_lock();
+
+  locktree *lt = locktree_map_find(dict_id);
+  if (lt == nullptr) {
+    XCALLOC(lt);
+    lt->create(this, dict_id, cmp, mutex_factory);
+
+    // new locktree created - call the on_create callback
+    // and put it in the locktree map
+    if (m_lt_create_callback) {
+      int r = m_lt_create_callback(lt, on_create_extra);
+      if (r != 0) {
+        lt->release_reference();
+        lt->destroy();
+        toku_free(lt);
+        lt = nullptr;
+      }
+    }
+    if (lt) {
+      locktree_map_put(lt);
+    }
+  } else {
+    reference_lt(lt);
+  }
+
+  mutex_unlock();
+
+  return lt;
+}
+
+void locktree_manager::reference_lt(locktree *lt) {
+  // increment using a sync fetch and add.
+  // the caller guarantees that the lt won't be
+  // destroyed while we increment the count here.
+  //
+  // the caller can do this by already having an lt
+  // reference or by holding the manager mutex.
+  //
+  // if the manager's mutex is held, it is ok for the
+  // reference count to transition from 0 to 1 (no race),
+  // since we're serialized with other opens and closes.
+  lt->add_reference();
+}
+
+void locktree_manager::release_lt(locktree *lt) {
+  bool do_destroy = false;
+  DICTIONARY_ID dict_id = lt->get_dict_id();
+
+  // Release a reference on the locktree. If the count transitions to zero,
+  // then we *may* need to do the cleanup.
+  //
+  // Grab the manager's mutex and look for a locktree with this locktree's
+  // dictionary id. Since dictionary id's never get reused, any locktree
+  // found must be the one we just released a reference on.
+  //
+  // At least two things could have happened since we got the mutex:
+  // - Another thread gets a locktree with the same dict_id, increments
+  // the reference count. In this case, we shouldn't destroy it.
+  // - Another thread gets a locktree with the same dict_id and then
+  // releases it quickly, transitioning the reference count from zero to
+  // one and back to zero. In this case, only one of us should destroy it.
+  // It doesn't matter which. We originally missed this case, see #5776.
+  //
+  // After 5776, the high level rule for release is described below.
+  //
+  // If a thread releases a locktree and notices the reference count transition
+  // to zero, then that thread must immediately:
+  // - assume the locktree object is invalid
+  // - grab the manager's mutex
+  // - search the locktree map for a locktree with the same dict_id and remove
+  // it, if it exists. the destroy may be deferred.
+  // - release the manager's mutex
+  //
+  // This way, if many threads transition the same locktree's reference count
+  // from 1 to zero and wait behind the manager's mutex, only one of them will
+  // do the actual destroy and the others will happily do nothing.
+  uint32_t refs = lt->release_reference();
+  if (refs == 0) {
+    mutex_lock();
+    // lt may not have already been destroyed, so look it up.
+    locktree *find_lt = locktree_map_find(dict_id);
+    if (find_lt != nullptr) {
+      // A locktree is still in the map with that dict_id, so it must be
+      // equal to lt. This is true because dictionary ids are never reused.
+      // If the reference count is zero, it's our responsibility to remove
+      // it and do the destroy. Otherwise, someone still wants it.
+      // If the locktree is still valid then check if it should be deleted.
+      if (find_lt == lt) {
+        if (lt->get_reference_count() == 0) {
+          locktree_map_remove(lt);
+          do_destroy = true;
+        }
+        m_lt_counters.add(lt->get_lock_request_info()->counters);
+      }
+    }
+    mutex_unlock();
+  }
+
+  // if necessary, do the destroy without holding the mutex
+  if (do_destroy) {
+    if (m_lt_destroy_callback) {
+      m_lt_destroy_callback(lt);
+    }
+    lt->destroy();
+    toku_free(lt);
+  }
+}
+
+void locktree_manager::run_escalation(void) {
+  struct escalation_fn {
+    static void run(void *extra) {
+      locktree_manager *mgr = (locktree_manager *)extra;
+      mgr->escalate_all_locktrees();
+    };
+  };
+  m_escalator.run(this, escalation_fn::run, this);
+}
+
+// test-only version of lock escalation
+void locktree_manager::run_escalation_for_test(void) { run_escalation(); }
+
+void locktree_manager::escalate_all_locktrees(void) {
+  uint64_t t0 = toku_current_time_microsec();
+
+  // get all locktrees
+  mutex_lock();
+  int num_locktrees = m_locktree_map.size();
+  locktree **locktrees = new locktree *[num_locktrees];
+  for (int i = 0; i < num_locktrees; i++) {
+    int r = m_locktree_map.fetch(i, &locktrees[i]);
+    invariant_zero(r);
+    reference_lt(locktrees[i]);
+  }
+  mutex_unlock();
+
+  // escalate them
+  escalate_locktrees(locktrees, num_locktrees);
+
+  delete[] locktrees;
+
+  uint64_t t1 = toku_current_time_microsec();
+  add_escalator_wait_time(t1 - t0);
+}
+
+void locktree_manager::note_mem_used(uint64_t mem_used) {
+  (void)toku_sync_fetch_and_add(&m_current_lock_memory, mem_used);
+}
+
+void locktree_manager::note_mem_released(uint64_t mem_released) {
+  uint64_t old_mem_used =
+      toku_sync_fetch_and_sub(&m_current_lock_memory, mem_released);
+  invariant(old_mem_used >= mem_released);
+}
+
+bool locktree_manager::out_of_locks(void) const {
+  return m_current_lock_memory >= m_max_lock_memory;
+}
+
+bool locktree_manager::over_big_threshold(void) {
+  return m_current_lock_memory >= m_max_lock_memory / 2;
+}
+
+int locktree_manager::iterate_pending_lock_requests(
+    lock_request_iterate_callback callback, void *extra) {
+  mutex_lock();
+  int r = 0;
+  uint32_t num_locktrees = m_locktree_map.size();
+  for (uint32_t i = 0; i < num_locktrees && r == 0; i++) {
+    locktree *lt;
+    r = m_locktree_map.fetch(i, &lt);
+    invariant_zero(r);
+    if (r == EINVAL)  // Shouldn't happen, avoid compiler warning
+      continue;
+
+    struct lt_lock_request_info *info = lt->get_lock_request_info();
+    toku_external_mutex_lock(&info->mutex);
+
+    uint32_t num_requests = info->pending_lock_requests.size();
+    for (uint32_t k = 0; k < num_requests && r == 0; k++) {
+      lock_request *req;
+      r = info->pending_lock_requests.fetch(k, &req);
+      invariant_zero(r);
+      if (r == EINVAL) /* Shouldn't happen, avoid compiler warning */
+        continue;
+      r = callback(lt->get_dict_id(), req->get_txnid(), req->get_left_key(),
+                   req->get_right_key(), req->get_conflicting_txnid(),
+                   req->get_start_time(), extra);
+    }
+
+    toku_external_mutex_unlock(&info->mutex);
+  }
+  mutex_unlock();
+  return r;
+}
+
+int locktree_manager::check_current_lock_constraints(bool big_txn) {
+  int r = 0;
+  if (big_txn && over_big_threshold()) {
+    run_escalation();
+    if (over_big_threshold()) {
+      r = TOKUDB_OUT_OF_LOCKS;
+    }
+  }
+  if (r == 0 && out_of_locks()) {
+    run_escalation();
+    if (out_of_locks()) {
+      // return an error if we're still out of locks after escalation.
+      r = TOKUDB_OUT_OF_LOCKS;
+    }
+  }
+  return r;
+}
+
+void locktree_manager::escalator_init(void) {
+  ZERO_STRUCT(m_escalation_mutex);
+  toku_mutex_init(manager_escalation_mutex_key, &m_escalation_mutex, nullptr);
+  m_escalation_count = 0;
+  m_escalation_time = 0;
+  m_wait_escalation_count = 0;
+  m_wait_escalation_time = 0;
+  m_long_wait_escalation_count = 0;
+  m_long_wait_escalation_time = 0;
+  m_escalation_latest_result = 0;
+  m_escalator.create();
+}
+
+void locktree_manager::escalator_destroy(void) {
+  m_escalator.destroy();
+  toku_mutex_destroy(&m_escalation_mutex);
+}
+
+void locktree_manager::add_escalator_wait_time(uint64_t t) {
+  toku_mutex_lock(&m_escalation_mutex);
+  m_wait_escalation_count += 1;
+  m_wait_escalation_time += t;
+  if (t >= 1000000) {
+    m_long_wait_escalation_count += 1;
+    m_long_wait_escalation_time += t;
+  }
+  toku_mutex_unlock(&m_escalation_mutex);
+}
+
+void locktree_manager::escalate_locktrees(locktree **locktrees,
+                                          int num_locktrees) {
+  // there are too many row locks in the system and we need to tidy up.
+  //
+  // a simple implementation of escalation does not attempt
+  // to reduce the memory foot print of each txn's range buffer.
+  // doing so would require some layering hackery (or a callback)
+  // and more complicated locking. for now, just escalate each
+  // locktree individually, in-place.
+  tokutime_t t0 = toku_time_now();
+  for (int i = 0; i < num_locktrees; i++) {
+    locktrees[i]->escalate(m_lt_escalate_callback,
+                           m_lt_escalate_callback_extra);
+    release_lt(locktrees[i]);
+  }
+  tokutime_t t1 = toku_time_now();
+
+  toku_mutex_lock(&m_escalation_mutex);
+  m_escalation_count++;
+  m_escalation_time += (t1 - t0);
+  m_escalation_latest_result = m_current_lock_memory;
+  toku_mutex_unlock(&m_escalation_mutex);
+}
+
+struct escalate_args {
+  locktree_manager *mgr;
+  locktree **locktrees;
+  int num_locktrees;
+};
+
+void locktree_manager::locktree_escalator::create(void) {
+  ZERO_STRUCT(m_escalator_mutex);
+  toku_mutex_init(manager_escalator_mutex_key, &m_escalator_mutex, nullptr);
+  toku_cond_init(manager_m_escalator_done_key, &m_escalator_done, nullptr);
+  m_escalator_running = false;
+}
+
+void locktree_manager::locktree_escalator::destroy(void) {
+  toku_cond_destroy(&m_escalator_done);
+  toku_mutex_destroy(&m_escalator_mutex);
+}
+
+void locktree_manager::locktree_escalator::run(
+    locktree_manager *mgr, void (*escalate_locktrees_fun)(void *extra),
+    void *extra) {
+  uint64_t t0 = toku_current_time_microsec();
+  toku_mutex_lock(&m_escalator_mutex);
+  if (!m_escalator_running) {
+    // run escalation on this thread
+    m_escalator_running = true;
+    toku_mutex_unlock(&m_escalator_mutex);
+    escalate_locktrees_fun(extra);
+    toku_mutex_lock(&m_escalator_mutex);
+    m_escalator_running = false;
+    toku_cond_broadcast(&m_escalator_done);
+  } else {
+    toku_cond_wait(&m_escalator_done, &m_escalator_mutex);
+  }
+  toku_mutex_unlock(&m_escalator_mutex);
+  uint64_t t1 = toku_current_time_microsec();
+  mgr->add_escalator_wait_time(t1 - t0);
+}
+
+void locktree_manager::get_status(LTM_STATUS statp) {
+  ltm_status.init();
+  LTM_STATUS_VAL(LTM_SIZE_CURRENT) = m_current_lock_memory;
+  LTM_STATUS_VAL(LTM_SIZE_LIMIT) = m_max_lock_memory;
+  LTM_STATUS_VAL(LTM_ESCALATION_COUNT) = m_escalation_count;
+  LTM_STATUS_VAL(LTM_ESCALATION_TIME) = m_escalation_time;
+  LTM_STATUS_VAL(LTM_ESCALATION_LATEST_RESULT) = m_escalation_latest_result;
+  LTM_STATUS_VAL(LTM_WAIT_ESCALATION_COUNT) = m_wait_escalation_count;
+  LTM_STATUS_VAL(LTM_WAIT_ESCALATION_TIME) = m_wait_escalation_time;
+  LTM_STATUS_VAL(LTM_LONG_WAIT_ESCALATION_COUNT) = m_long_wait_escalation_count;
+  LTM_STATUS_VAL(LTM_LONG_WAIT_ESCALATION_TIME) = m_long_wait_escalation_time;
+
+  uint64_t lock_requests_pending = 0;
+  uint64_t sto_num_eligible = 0;
+  uint64_t sto_end_early_count = 0;
+  tokutime_t sto_end_early_time = 0;
+  uint32_t num_locktrees = 0;
+  struct lt_counters lt_counters;
+  ZERO_STRUCT(lt_counters);  // PORT: instead of ={}.
+
+  if (toku_mutex_trylock(&m_mutex) == 0) {
+    lt_counters = m_lt_counters;
+    num_locktrees = m_locktree_map.size();
+    for (uint32_t i = 0; i < num_locktrees; i++) {
+      locktree *lt;
+      int r = m_locktree_map.fetch(i, &lt);
+      invariant_zero(r);
+      if (r == EINVAL)  // Shouldn't happen, avoid compiler warning
+        continue;
+      if (toku_external_mutex_trylock(&lt->m_lock_request_info.mutex) == 0) {
+        lock_requests_pending +=
+            lt->m_lock_request_info.pending_lock_requests.size();
+        lt_counters.add(lt->get_lock_request_info()->counters);
+        toku_external_mutex_unlock(&lt->m_lock_request_info.mutex);
+      }
+      sto_num_eligible += lt->sto_txnid_is_valid_unsafe() ? 1 : 0;
+      sto_end_early_count += lt->m_sto_end_early_count;
+      sto_end_early_time += lt->m_sto_end_early_time;
+    }
+    mutex_unlock();
+  }
+
+  LTM_STATUS_VAL(LTM_NUM_LOCKTREES) = num_locktrees;
+  LTM_STATUS_VAL(LTM_LOCK_REQUESTS_PENDING) = lock_requests_pending;
+  LTM_STATUS_VAL(LTM_STO_NUM_ELIGIBLE) = sto_num_eligible;
+  LTM_STATUS_VAL(LTM_STO_END_EARLY_COUNT) = sto_end_early_count;
+  LTM_STATUS_VAL(LTM_STO_END_EARLY_TIME) = sto_end_early_time;
+  LTM_STATUS_VAL(LTM_WAIT_COUNT) = lt_counters.wait_count;
+  LTM_STATUS_VAL(LTM_WAIT_TIME) = lt_counters.wait_time;
+  LTM_STATUS_VAL(LTM_LONG_WAIT_COUNT) = lt_counters.long_wait_count;
+  LTM_STATUS_VAL(LTM_LONG_WAIT_TIME) = lt_counters.long_wait_time;
+  LTM_STATUS_VAL(LTM_TIMEOUT_COUNT) = lt_counters.timeout_count;
+  *statp = ltm_status;
+}
+
+void locktree_manager::kill_waiter(void *extra) {
+  mutex_lock();
+  int r = 0;
+  uint32_t num_locktrees = m_locktree_map.size();
+  for (uint32_t i = 0; i < num_locktrees; i++) {
+    locktree *lt;
+    r = m_locktree_map.fetch(i, &lt);
+    invariant_zero(r);
+    if (r) continue;  // Get rid of "may be used uninitialized" warning
+    lock_request::kill_waiter(lt, extra);
+  }
+  mutex_unlock();
+}
+
+} /* namespace toku */
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/range_buffer.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/range_buffer.cc
new file mode 100644
index 000000000..1e1d23ef8
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/range_buffer.cc
@@ -0,0 +1,265 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include "range_buffer.h"
+
+#include <string.h>
+
+#include "../portability/memory.h"
+#include "../util/dbt.h"
+
+namespace toku {
+
+bool range_buffer::record_header::left_is_infinite(void) const {
+  return left_neg_inf || left_pos_inf;
+}
+
+bool range_buffer::record_header::right_is_infinite(void) const {
+  return right_neg_inf || right_pos_inf;
+}
+
+void range_buffer::record_header::init(const DBT *left_key,
+                                       const DBT *right_key,
+                                       bool is_exclusive) {
+  is_exclusive_lock = is_exclusive;
+  left_neg_inf = left_key == toku_dbt_negative_infinity();
+  left_pos_inf = left_key == toku_dbt_positive_infinity();
+  left_key_size = toku_dbt_is_infinite(left_key) ? 0 : left_key->size;
+  if (right_key) {
+    right_neg_inf = right_key == toku_dbt_negative_infinity();
+    right_pos_inf = right_key == toku_dbt_positive_infinity();
+    right_key_size = toku_dbt_is_infinite(right_key) ? 0 : right_key->size;
+  } else {
+    right_neg_inf = left_neg_inf;
+    right_pos_inf = left_pos_inf;
+    right_key_size = 0;
+  }
+}
+
+const DBT *range_buffer::iterator::record::get_left_key(void) const {
+  if (_header.left_neg_inf) {
+    return toku_dbt_negative_infinity();
+  } else if (_header.left_pos_inf) {
+    return toku_dbt_positive_infinity();
+  } else {
+    return &_left_key;
+  }
+}
+
+const DBT *range_buffer::iterator::record::get_right_key(void) const {
+  if (_header.right_neg_inf) {
+    return toku_dbt_negative_infinity();
+  } else if (_header.right_pos_inf) {
+    return toku_dbt_positive_infinity();
+  } else {
+    return &_right_key;
+  }
+}
+
+size_t range_buffer::iterator::record::size(void) const {
+  return sizeof(record_header) + _header.left_key_size + _header.right_key_size;
+}
+
+void range_buffer::iterator::record::deserialize(const char *buf) {
+  size_t current = 0;
+
+  // deserialize the header
+  memcpy(&_header, buf, sizeof(record_header));
+  current += sizeof(record_header);
+
+  // deserialize the left key if necessary
+  if (!_header.left_is_infinite()) {
+    // point the left DBT's buffer into ours
+    toku_fill_dbt(&_left_key, buf + current, _header.left_key_size);
+    current += _header.left_key_size;
+  }
+
+  // deserialize the right key if necessary
+  if (!_header.right_is_infinite()) {
+    if (_header.right_key_size == 0) {
+      toku_copyref_dbt(&_right_key, _left_key);
+    } else {
+      toku_fill_dbt(&_right_key, buf + current, _header.right_key_size);
+    }
+  }
+}
+
+toku::range_buffer::iterator::iterator()
+    : _ma_chunk_iterator(nullptr),
+      _current_chunk_base(nullptr),
+      _current_chunk_offset(0),
+      _current_chunk_max(0),
+      _current_rec_size(0) {}
+
+toku::range_buffer::iterator::iterator(const range_buffer *buffer)
+    : _ma_chunk_iterator(&buffer->_arena),
+      _current_chunk_base(nullptr),
+      _current_chunk_offset(0),
+      _current_chunk_max(0),
+      _current_rec_size(0) {
+  reset_current_chunk();
+}
+
+void range_buffer::iterator::reset_current_chunk() {
+  _current_chunk_base = _ma_chunk_iterator.current(&_current_chunk_max);
+  _current_chunk_offset = 0;
+}
+
+bool range_buffer::iterator::current(record *rec) {
+  if (_current_chunk_offset < _current_chunk_max) {
+    const char *buf = reinterpret_cast<const char *>(_current_chunk_base);
+    rec->deserialize(buf + _current_chunk_offset);
+    _current_rec_size = rec->size();
+    return true;
+  } else {
+    return false;
+  }
+}
+
+// move the iterator to the next record in the buffer
+void range_buffer::iterator::next(void) {
+  invariant(_current_chunk_offset < _current_chunk_max);
+  invariant(_current_rec_size > 0);
+
+  // the next record is _current_rec_size bytes forward
+  _current_chunk_offset += _current_rec_size;
+  // now, we don't know how big the current is, set it to 0.
+  _current_rec_size = 0;
+
+  if (_current_chunk_offset >= _current_chunk_max) {
+    // current chunk is exhausted, try moving to the next one
+    if (_ma_chunk_iterator.more()) {
+      _ma_chunk_iterator.next();
+      reset_current_chunk();
+    }
+  }
+}
+
+void range_buffer::create(void) {
+  // allocate buffer space lazily instead of on creation. this way,
+  // no malloc/free is done if the transaction ends up taking no locks.
+  _arena.create(0);
+  _num_ranges = 0;
+}
+
+void range_buffer::append(const DBT *left_key, const DBT *right_key,
+                          bool is_write_request) {
+  // if the keys are equal, then only one copy is stored.
+  if (toku_dbt_equals(left_key, right_key)) {
+    invariant(left_key->size <= MAX_KEY_SIZE);
+    append_point(left_key, is_write_request);
+  } else {
+    invariant(left_key->size <= MAX_KEY_SIZE);
+    invariant(right_key->size <= MAX_KEY_SIZE);
+    append_range(left_key, right_key, is_write_request);
+  }
+  _num_ranges++;
+}
+
+bool range_buffer::is_empty(void) const { return total_memory_size() == 0; }
+
+uint64_t range_buffer::total_memory_size(void) const {
+  return _arena.total_size_in_use();
+}
+
+int range_buffer::get_num_ranges(void) const { return _num_ranges; }
+
+void range_buffer::destroy(void) { _arena.destroy(); }
+
+void range_buffer::append_range(const DBT *left_key, const DBT *right_key,
+                                bool is_exclusive) {
+  size_t record_length =
+      sizeof(record_header) + left_key->size + right_key->size;
+  char *buf = reinterpret_cast<char *>(_arena.malloc_from_arena(record_length));
+
+  record_header h;
+  h.init(left_key, right_key, is_exclusive);
+
+  // serialize the header
+  memcpy(buf, &h, sizeof(record_header));
+  buf += sizeof(record_header);
+
+  // serialize the left key if necessary
+  if (!h.left_is_infinite()) {
+    memcpy(buf, left_key->data, left_key->size);
+    buf += left_key->size;
+  }
+
+  // serialize the right key if necessary
+  if (!h.right_is_infinite()) {
+    memcpy(buf, right_key->data, right_key->size);
+  }
+}
+
+void range_buffer::append_point(const DBT *key, bool is_exclusive) {
+  size_t record_length = sizeof(record_header) + key->size;
+  char *buf = reinterpret_cast<char *>(_arena.malloc_from_arena(record_length));
+
+  record_header h;
+  h.init(key, nullptr, is_exclusive);
+
+  // serialize the header
+  memcpy(buf, &h, sizeof(record_header));
+  buf += sizeof(record_header);
+
+  // serialize the key if necessary
+  if (!h.left_is_infinite()) {
+    memcpy(buf, key->data, key->size);
+  }
+}
+
+} /* namespace toku */
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/range_buffer.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/range_buffer.h
new file mode 100644
index 000000000..76e28d747
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/range_buffer.h
@@ -0,0 +1,178 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include <inttypes.h>
+#include <stdint.h>
+
+#include "../util/dbt.h"
+#include "../util/memarena.h"
+
+namespace toku {
+
+// a key range buffer represents a set of key ranges that can
+// be stored, iterated over, and then destroyed all at once.
+class range_buffer {
+ private:
+  // the key range buffer is a bunch of records in a row.
+  // each record has the following header, followed by the
+  // left key and right key data payload, if applicable.
+  // we limit keys to be 2^16, since we store lengths as 2 bytes.
+  static const size_t MAX_KEY_SIZE = 1 << 16;
+
+  struct record_header {
+    bool left_neg_inf;
+    bool left_pos_inf;
+    bool right_pos_inf;
+    bool right_neg_inf;
+    uint16_t left_key_size;
+    uint16_t right_key_size;
+    bool is_exclusive_lock;
+
+    bool left_is_infinite(void) const;
+
+    bool right_is_infinite(void) const;
+
+    void init(const DBT *left_key, const DBT *right_key, bool is_exclusive);
+  };
+  // PORT static_assert(sizeof(record_header) == 8, "record header format is
+  // off");
+
+ public:
+  // the iterator abstracts reading over a buffer of variable length
+  // records one by one until there are no more left.
+  class iterator {
+   public:
+    iterator();
+    iterator(const range_buffer *buffer);
+
+    // a record represents the user-view of a serialized key range.
+    // it handles positive and negative infinity and the optimized
+    // point range case, where left and right points share memory.
+    class record {
+     public:
+      // get a read-only pointer to the left key of this record's range
+      const DBT *get_left_key(void) const;
+
+      // get a read-only pointer to the right key of this record's range
+      const DBT *get_right_key(void) const;
+
+      // how big is this record? this tells us where the next record is
+      size_t size(void) const;
+
+      bool get_exclusive_flag() const { return _header.is_exclusive_lock; }
+
+      // populate a record header and point our DBT's
+      // buffers into ours if they are not infinite.
+      void deserialize(const char *buf);
+
+     private:
+      record_header _header;
+      DBT _left_key;
+      DBT _right_key;
+    };
+
+    // populate the given record object with the current
+    // the memory referred to by record is valid for only
+    // as long as the record exists.
+    bool current(record *rec);
+
+    // move the iterator to the next record in the buffer
+    void next(void);
+
+   private:
+    void reset_current_chunk();
+
+    // the key range buffer we are iterating over, the current
+    // offset in that buffer, and the size of the current record.
+    memarena::chunk_iterator _ma_chunk_iterator;
+    const void *_current_chunk_base;
+    size_t _current_chunk_offset;
+    size_t _current_chunk_max;
+    size_t _current_rec_size;
+  };
+
+  // allocate buffer space lazily instead of on creation. this way,
+  // no malloc/free is done if the transaction ends up taking no locks.
+  void create(void);
+
+  // append a left/right key range to the buffer.
+  // if the keys are equal, then only one copy is stored.
+  void append(const DBT *left_key, const DBT *right_key,
+              bool is_write_request = false);
+
+  // is this range buffer empty?
+  bool is_empty(void) const;
+
+  // how much memory is being used by this range buffer?
+  uint64_t total_memory_size(void) const;
+
+  // how many ranges are stored in this range buffer?
+  int get_num_ranges(void) const;
+
+  void destroy(void);
+
+ private:
+  memarena _arena;
+  int _num_ranges;
+
+  void append_range(const DBT *left_key, const DBT *right_key,
+                    bool is_write_request);
+
+  // append a point to the buffer. this is the space/time saving
+  // optimization for key ranges where left == right.
+  void append_point(const DBT *key, bool is_write_request);
+};
+
+} /* namespace toku */
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/treenode.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/treenode.cc
new file mode 100644
index 000000000..8997f634b
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/treenode.cc
@@ -0,0 +1,520 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include "treenode.h"
+
+#include "../portability/toku_race_tools.h"
+
+namespace toku {
+
+// TODO: source location info might have to be pulled up one caller
+// to be useful
+void treenode::mutex_lock(void) { toku_mutex_lock(&m_mutex); }
+
+void treenode::mutex_unlock(void) { toku_mutex_unlock(&m_mutex); }
+
+void treenode::init(const comparator *cmp) {
+  m_txnid = TXNID_NONE;
+  m_is_root = false;
+  m_is_empty = true;
+  m_cmp = cmp;
+
+  m_is_shared = false;
+  m_owners = nullptr;
+
+  // use an adaptive mutex at each node since we expect the time the
+  // lock is held to be relatively short compared to a context switch.
+  // indeed, this improves performance at high thread counts considerably.
+  memset(&m_mutex, 0, sizeof(toku_mutex_t));
+  toku_pthread_mutexattr_t attr;
+  toku_mutexattr_init(&attr);
+  toku_mutexattr_settype(&attr, TOKU_MUTEX_ADAPTIVE);
+  toku_mutex_init(treenode_mutex_key, &m_mutex, &attr);
+  toku_mutexattr_destroy(&attr);
+  m_left_child.set(nullptr);
+  m_right_child.set(nullptr);
+}
+
+void treenode::create_root(const comparator *cmp) {
+  init(cmp);
+  m_is_root = true;
+}
+
+void treenode::destroy_root(void) {
+  invariant(is_root());
+  invariant(is_empty());
+  toku_mutex_destroy(&m_mutex);
+  m_cmp = nullptr;
+}
+
+void treenode::set_range_and_txnid(const keyrange &range, TXNID txnid,
+                                   bool is_shared) {
+  // allocates a new copy of the range for this node
+  m_range.create_copy(range);
+  m_txnid = txnid;
+  m_is_shared = is_shared;
+  m_is_empty = false;
+}
+
+bool treenode::is_root(void) { return m_is_root; }
+
+bool treenode::is_empty(void) { return m_is_empty; }
+
+bool treenode::range_overlaps(const keyrange &range) {
+  return m_range.overlaps(*m_cmp, range);
+}
+
+treenode *treenode::alloc(const comparator *cmp, const keyrange &range,
+                          TXNID txnid, bool is_shared) {
+  treenode *XCALLOC(node);
+  node->init(cmp);
+  node->set_range_and_txnid(range, txnid, is_shared);
+  return node;
+}
+
+void treenode::swap_in_place(treenode *node1, treenode *node2) {
+  keyrange tmp_range = node1->m_range;
+  TXNID tmp_txnid = node1->m_txnid;
+  node1->m_range = node2->m_range;
+  node1->m_txnid = node2->m_txnid;
+  node2->m_range = tmp_range;
+  node2->m_txnid = tmp_txnid;
+
+  bool tmp_is_shared = node1->m_is_shared;
+  node1->m_is_shared = node2->m_is_shared;
+  node2->m_is_shared = tmp_is_shared;
+
+  auto tmp_m_owners = node1->m_owners;
+  node1->m_owners = node2->m_owners;
+  node2->m_owners = tmp_m_owners;
+}
+
+bool treenode::add_shared_owner(TXNID txnid) {
+  assert(m_is_shared);
+  if (txnid == m_txnid)
+    return false;  // acquiring a lock on the same range by the same trx
+
+  if (m_txnid != TXNID_SHARED) {
+    m_owners = new TxnidVector;
+    m_owners->insert(m_txnid);
+    m_txnid = TXNID_SHARED;
+  }
+  m_owners->insert(txnid);
+  return true;
+}
+
+void treenode::free(treenode *node) {
+  // destroy the range, freeing any copied keys
+  node->m_range.destroy();
+
+  if (node->m_owners) {
+    delete node->m_owners;
+    node->m_owners = nullptr;  // need this?
+  }
+
+  // the root is simply marked as empty.
+  if (node->is_root()) {
+    // PORT toku_mutex_assert_locked(&node->m_mutex);
+    node->m_is_empty = true;
+  } else {
+    // PORT toku_mutex_assert_unlocked(&node->m_mutex);
+    toku_mutex_destroy(&node->m_mutex);
+    toku_free(node);
+  }
+}
+
+uint32_t treenode::get_depth_estimate(void) const {
+  const uint32_t left_est = m_left_child.depth_est;
+  const uint32_t right_est = m_right_child.depth_est;
+  return (left_est > right_est ? left_est : right_est) + 1;
+}
+
+treenode *treenode::find_node_with_overlapping_child(
+    const keyrange &range, const keyrange::comparison *cmp_hint) {
+  // determine which child to look at based on a comparison. if we were
+  // given a comparison hint, use that. otherwise, compare them now.
+  keyrange::comparison c =
+      cmp_hint ? *cmp_hint : range.compare(*m_cmp, m_range);
+
+  treenode *child;
+  if (c == keyrange::comparison::LESS_THAN) {
+    child = lock_and_rebalance_left();
+  } else {
+    // The caller (locked_keyrange::acquire) handles the case where
+    // the root of the locked_keyrange is the node that overlaps.
+    // range is guaranteed not to overlap this node.
+    invariant(c == keyrange::comparison::GREATER_THAN);
+    child = lock_and_rebalance_right();
+  }
+
+  // if the search would lead us to an empty subtree (child == nullptr),
+  // or the child overlaps, then we know this node is the parent we want.
+  // otherwise we need to recur into that child.
+  if (child == nullptr) {
+    return this;
+  } else {
+    c = range.compare(*m_cmp, child->m_range);
+    if (c == keyrange::comparison::EQUALS ||
+        c == keyrange::comparison::OVERLAPS) {
+      child->mutex_unlock();
+      return this;
+    } else {
+      // unlock this node before recurring into the locked child,
+      // passing in a comparison hint since we just comapred range
+      // to the child's range.
+      mutex_unlock();
+      return child->find_node_with_overlapping_child(range, &c);
+    }
+  }
+}
+
+bool treenode::insert(const keyrange &range, TXNID txnid, bool is_shared) {
+  int rc = true;
+  // choose a child to check. if that child is null, then insert the new node
+  // there. otherwise recur down that child's subtree
+  keyrange::comparison c = range.compare(*m_cmp, m_range);
+  if (c == keyrange::comparison::LESS_THAN) {
+    treenode *left_child = lock_and_rebalance_left();
+    if (left_child == nullptr) {
+      left_child = treenode::alloc(m_cmp, range, txnid, is_shared);
+      m_left_child.set(left_child);
+    } else {
+      left_child->insert(range, txnid, is_shared);
+      left_child->mutex_unlock();
+    }
+  } else if (c == keyrange::comparison::GREATER_THAN) {
+    // invariant(c == keyrange::comparison::GREATER_THAN);
+    treenode *right_child = lock_and_rebalance_right();
+    if (right_child == nullptr) {
+      right_child = treenode::alloc(m_cmp, range, txnid, is_shared);
+      m_right_child.set(right_child);
+    } else {
+      right_child->insert(range, txnid, is_shared);
+      right_child->mutex_unlock();
+    }
+  } else if (c == keyrange::comparison::EQUALS) {
+    invariant(is_shared);
+    invariant(m_is_shared);
+    rc = add_shared_owner(txnid);
+  } else {
+    invariant(0);
+  }
+  return rc;
+}
+
+treenode *treenode::find_child_at_extreme(int direction, treenode **parent) {
+  treenode *child =
+      direction > 0 ? m_right_child.get_locked() : m_left_child.get_locked();
+
+  if (child) {
+    *parent = this;
+    treenode *child_extreme = child->find_child_at_extreme(direction, parent);
+    child->mutex_unlock();
+    return child_extreme;
+  } else {
+    return this;
+  }
+}
+
+treenode *treenode::find_leftmost_child(treenode **parent) {
+  return find_child_at_extreme(-1, parent);
+}
+
+treenode *treenode::find_rightmost_child(treenode **parent) {
+  return find_child_at_extreme(1, parent);
+}
+
+treenode *treenode::remove_root_of_subtree() {
+  // if this node has no children, just free it and return null
+  if (m_left_child.ptr == nullptr && m_right_child.ptr == nullptr) {
+    // treenode::free requires that non-root nodes are unlocked
+    if (!is_root()) {
+      mutex_unlock();
+    }
+    treenode::free(this);
+    return nullptr;
+  }
+
+  // we have a child, so get either the in-order successor or
+  // predecessor of this node to be our replacement.
+  // replacement_parent is updated by the find functions as
+  // they recur down the tree, so initialize it to this.
+  treenode *child, *replacement;
+  treenode *replacement_parent = this;
+  if (m_left_child.ptr != nullptr) {
+    child = m_left_child.get_locked();
+    replacement = child->find_rightmost_child(&replacement_parent);
+    invariant(replacement == child || replacement_parent != this);
+
+    // detach the replacement from its parent
+    if (replacement_parent == this) {
+      m_left_child = replacement->m_left_child;
+    } else {
+      replacement_parent->m_right_child = replacement->m_left_child;
+    }
+  } else {
+    child = m_right_child.get_locked();
+    replacement = child->find_leftmost_child(&replacement_parent);
+    invariant(replacement == child || replacement_parent != this);
+
+    // detach the replacement from its parent
+    if (replacement_parent == this) {
+      m_right_child = replacement->m_right_child;
+    } else {
+      replacement_parent->m_left_child = replacement->m_right_child;
+    }
+  }
+  child->mutex_unlock();
+
+  // swap in place with the detached replacement, then destroy it
+  treenode::swap_in_place(replacement, this);
+  treenode::free(replacement);
+
+  return this;
+}
+
+void treenode::recursive_remove(void) {
+  treenode *left = m_left_child.ptr;
+  if (left) {
+    left->recursive_remove();
+  }
+  m_left_child.set(nullptr);
+
+  treenode *right = m_right_child.ptr;
+  if (right) {
+    right->recursive_remove();
+  }
+  m_right_child.set(nullptr);
+
+  // we do not take locks on the way down, so we know non-root nodes
+  // are unlocked here and the caller is required to pass a locked
+  // root, so this free is correct.
+  treenode::free(this);
+}
+
+void treenode::remove_shared_owner(TXNID txnid) {
+  assert(m_owners->size() > 1);
+  m_owners->erase(txnid);
+  assert(m_owners->size() > 0);
+  /* if there is just one owner left, move it to m_txnid */
+  if (m_owners->size() == 1) {
+    m_txnid = *m_owners->begin();
+    delete m_owners;
+    m_owners = nullptr;
+  }
+}
+
+treenode *treenode::remove(const keyrange &range, TXNID txnid) {
+  treenode *child;
+  // if the range is equal to this node's range, then just remove
+  // the root of this subtree. otherwise search down the tree
+  // in either the left or right children.
+  keyrange::comparison c = range.compare(*m_cmp, m_range);
+  switch (c) {
+    case keyrange::comparison::EQUALS: {
+      // if we are the only owners, remove. Otherwise, just remove
+      // us from the owners list.
+      if (txnid != TXNID_ANY && has_multiple_owners()) {
+        remove_shared_owner(txnid);
+        return this;
+      } else {
+        return remove_root_of_subtree();
+      }
+    }
+    case keyrange::comparison::LESS_THAN:
+      child = m_left_child.get_locked();
+      invariant_notnull(child);
+      child = child->remove(range, txnid);
+
+      // unlock the child if there still is one.
+      // regardless, set the right child pointer
+      if (child) {
+        child->mutex_unlock();
+      }
+      m_left_child.set(child);
+      break;
+    case keyrange::comparison::GREATER_THAN:
+      child = m_right_child.get_locked();
+      invariant_notnull(child);
+      child = child->remove(range, txnid);
+
+      // unlock the child if there still is one.
+      // regardless, set the right child pointer
+      if (child) {
+        child->mutex_unlock();
+      }
+      m_right_child.set(child);
+      break;
+    case keyrange::comparison::OVERLAPS:
+      // shouldn't be overlapping, since the tree is
+      // non-overlapping and this range must exist
+      abort();
+  }
+
+  return this;
+}
+
+bool treenode::left_imbalanced(int threshold) const {
+  uint32_t left_depth = m_left_child.depth_est;
+  uint32_t right_depth = m_right_child.depth_est;
+  return m_left_child.ptr != nullptr && left_depth > threshold + right_depth;
+}
+
+bool treenode::right_imbalanced(int threshold) const {
+  uint32_t left_depth = m_left_child.depth_est;
+  uint32_t right_depth = m_right_child.depth_est;
+  return m_right_child.ptr != nullptr && right_depth > threshold + left_depth;
+}
+
+// effect: rebalances the subtree rooted at this node
+//         using AVL style O(1) rotations. unlocks this
+//         node if it is not the new root of the subtree.
+// requires: node is locked by this thread, children are not
+// returns: locked root node of the rebalanced tree
+treenode *treenode::maybe_rebalance(void) {
+  // if we end up not rotating at all, the new root is this
+  treenode *new_root = this;
+  treenode *child = nullptr;
+
+  if (left_imbalanced(IMBALANCE_THRESHOLD)) {
+    child = m_left_child.get_locked();
+    if (child->right_imbalanced(0)) {
+      treenode *grandchild = child->m_right_child.get_locked();
+
+      child->m_right_child = grandchild->m_left_child;
+      grandchild->m_left_child.set(child);
+
+      m_left_child = grandchild->m_right_child;
+      grandchild->m_right_child.set(this);
+
+      new_root = grandchild;
+    } else {
+      m_left_child = child->m_right_child;
+      child->m_right_child.set(this);
+      new_root = child;
+    }
+  } else if (right_imbalanced(IMBALANCE_THRESHOLD)) {
+    child = m_right_child.get_locked();
+    if (child->left_imbalanced(0)) {
+      treenode *grandchild = child->m_left_child.get_locked();
+
+      child->m_left_child = grandchild->m_right_child;
+      grandchild->m_right_child.set(child);
+
+      m_right_child = grandchild->m_left_child;
+      grandchild->m_left_child.set(this);
+
+      new_root = grandchild;
+    } else {
+      m_right_child = child->m_left_child;
+      child->m_left_child.set(this);
+      new_root = child;
+    }
+  }
+
+  // up to three nodes may be locked.
+  // - this
+  // - child
+  // - grandchild (but if it is locked, its the new root)
+  //
+  // one of them is the new root. we unlock everything except the new root.
+  if (child && child != new_root) {
+    TOKU_VALGRIND_RESET_MUTEX_ORDERING_INFO(&child->m_mutex);
+    child->mutex_unlock();
+  }
+  if (this != new_root) {
+    TOKU_VALGRIND_RESET_MUTEX_ORDERING_INFO(&m_mutex);
+    mutex_unlock();
+  }
+  TOKU_VALGRIND_RESET_MUTEX_ORDERING_INFO(&new_root->m_mutex);
+  return new_root;
+}
+
+treenode *treenode::lock_and_rebalance_left(void) {
+  treenode *child = m_left_child.get_locked();
+  if (child) {
+    treenode *new_root = child->maybe_rebalance();
+    m_left_child.set(new_root);
+    child = new_root;
+  }
+  return child;
+}
+
+treenode *treenode::lock_and_rebalance_right(void) {
+  treenode *child = m_right_child.get_locked();
+  if (child) {
+    treenode *new_root = child->maybe_rebalance();
+    m_right_child.set(new_root);
+    child = new_root;
+  }
+  return child;
+}
+
+void treenode::child_ptr::set(treenode *node) {
+  ptr = node;
+  depth_est = ptr ? ptr->get_depth_estimate() : 0;
+}
+
+treenode *treenode::child_ptr::get_locked(void) {
+  if (ptr) {
+    ptr->mutex_lock();
+    depth_est = ptr->get_depth_estimate();
+  }
+  return ptr;
+}
+
+} /* namespace toku */
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/treenode.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/treenode.h
new file mode 100644
index 000000000..ec25a8c58
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/treenode.h
@@ -0,0 +1,302 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=2:softtabstop=2:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include <string.h>
+
+#include "../ft/comparator.h"
+#include "../portability/memory.h"
+#include "../portability/toku_pthread.h"
+// PORT: we need LTM_STATUS
+#include "../ft/ft-status.h"
+#include "../portability/txn_subst.h"
+#include "keyrange.h"
+
+namespace toku {
+
+// a node in a tree with its own mutex
+// - range is the "key" of this node
+// - txnid is the single txnid associated with this node
+// - left and right children may be null
+//
+// to build a tree on top of this abstraction, the user:
+// - provides memory for a root node, initializes it via create_root()
+// - performs tree operations on the root node. memory management
+//   below the root node is handled by the abstraction, not the user.
+// this pattern:
+// - guaruntees a root node always exists.
+// - does not allow for rebalances on the root node
+
+class treenode {
+ public:
+  // every treenode function has some common requirements:
+  // - node is locked and children are never locked
+  // - node may be unlocked if no other thread has visibility
+
+  // effect: create the root node
+  void create_root(const comparator *cmp);
+
+  // effect: destroys the root node
+  void destroy_root(void);
+
+  // effect: sets the txnid and copies the given range for this node
+  void set_range_and_txnid(const keyrange &range, TXNID txnid, bool is_shared);
+
+  // returns: true iff this node is marked as empty
+  bool is_empty(void);
+
+  // returns: true if this is the root node, denoted by a null parent
+  bool is_root(void);
+
+  // returns: true if the given range overlaps with this node's range
+  bool range_overlaps(const keyrange &range);
+
+  // effect: locks the node
+  void mutex_lock(void);
+
+  // effect: unlocks the node
+  void mutex_unlock(void);
+
+  // return: node whose child overlaps, or a child that is empty
+  //         and would contain range if it existed
+  // given: if cmp_hint is non-null, then it is a precomputed
+  //        comparison of this node's range to the given range.
+  treenode *find_node_with_overlapping_child(
+      const keyrange &range, const keyrange::comparison *cmp_hint);
+
+  // effect: performs an in-order traversal of the ranges that overlap the
+  //         given range, calling function->fn() on each node that does
+  // requires: function signature is: bool fn(const keyrange &range, TXNID
+  // txnid) requires: fn returns true to keep iterating, false to stop iterating
+  // requires: fn does not attempt to use any ranges read out by value
+  //           after removing a node with an overlapping range from the tree.
+  template <class F>
+  void traverse_overlaps(const keyrange &range, F *function) {
+    keyrange::comparison c = range.compare(*m_cmp, m_range);
+    if (c == keyrange::comparison::EQUALS) {
+      // Doesn't matter if fn wants to keep going, there
+      // is nothing left, so return.
+      function->fn(m_range, m_txnid, m_is_shared, m_owners);
+      return;
+    }
+
+    treenode *left = m_left_child.get_locked();
+    if (left) {
+      if (c != keyrange::comparison::GREATER_THAN) {
+        // Target range is less than this node, or it overlaps this
+        // node.  There may be something on the left.
+        left->traverse_overlaps(range, function);
+      }
+      left->mutex_unlock();
+    }
+
+    if (c == keyrange::comparison::OVERLAPS) {
+      bool keep_going = function->fn(m_range, m_txnid, m_is_shared, m_owners);
+      if (!keep_going) {
+        return;
+      }
+    }
+
+    treenode *right = m_right_child.get_locked();
+    if (right) {
+      if (c != keyrange::comparison::LESS_THAN) {
+        // Target range is greater than this node, or it overlaps this
+        // node.  There may be something on the right.
+        right->traverse_overlaps(range, function);
+      }
+      right->mutex_unlock();
+    }
+  }
+
+  // effect: inserts the given range and txnid into a subtree, recursively
+  // requires: range does not overlap with any node below the subtree
+  bool insert(const keyrange &range, TXNID txnid, bool is_shared);
+
+  // effect: removes the given range from the subtree
+  // requires: range exists in the subtree
+  // returns: the root of the resulting subtree
+  treenode *remove(const keyrange &range, TXNID txnid);
+
+  // effect: removes this node and all of its children, recursively
+  // requires: every node at and below this node is unlocked
+  void recursive_remove(void);
+
+ private:
+  // the child_ptr is a light abstraction for the locking of
+  // a child and the maintenence of its depth estimate.
+
+  struct child_ptr {
+    // set the child pointer
+    void set(treenode *node);
+
+    // get and lock this child if it exists
+    treenode *get_locked(void);
+
+    treenode *ptr;
+    uint32_t depth_est;
+  };
+
+  // the balance factor at which a node is considered imbalanced
+  static const int32_t IMBALANCE_THRESHOLD = 2;
+
+  // node-level mutex
+  toku_mutex_t m_mutex;
+
+  // the range and txnid for this node. the range contains a copy
+  // of the keys originally inserted into the tree. nodes may
+  // swap ranges. but at the end of the day, when a node is
+  // destroyed, it frees the memory associated with whatever range
+  // it has at the time of destruction.
+  keyrange m_range;
+
+  void remove_shared_owner(TXNID txnid);
+
+  bool has_multiple_owners() { return (m_txnid == TXNID_SHARED); }
+
+ private:
+  // Owner transaction id.
+  // A value of TXNID_SHARED means this node has multiple owners
+  TXNID m_txnid;
+
+  // If true, this lock is a non-exclusive lock, and it can have either
+  // one or several owners.
+  bool m_is_shared;
+
+  // List of the owners, or nullptr if there's just one owner.
+  TxnidVector *m_owners;
+
+  // two child pointers
+  child_ptr m_left_child;
+  child_ptr m_right_child;
+
+  // comparator for ranges
+  // psergey-todo: Is there any sense to store the comparator in each tree
+  // node?
+  const comparator *m_cmp;
+
+  // marked for the root node. the root node is never free()'d
+  // when removed, but instead marked as empty.
+  bool m_is_root;
+
+  // marked for an empty node. only valid for the root.
+  bool m_is_empty;
+
+  // effect: initializes an empty node with the given comparator
+  void init(const comparator *cmp);
+
+  // requires: this is a shared node (m_is_shared==true)
+  // effect: another transaction is added as an owner.
+  // returns: true <=> added another owner
+  //          false <=> this transaction is already an owner
+  bool add_shared_owner(TXNID txnid);
+
+  // requires: *parent is initialized to something meaningful.
+  // requires: subtree is non-empty
+  // returns: the leftmost child of the given subtree
+  // returns: a pointer to the parent of said child in *parent, only
+  //          if this function recurred, otherwise it is untouched.
+  treenode *find_leftmost_child(treenode **parent);
+
+  // requires: *parent is initialized to something meaningful.
+  // requires: subtree is non-empty
+  // returns: the rightmost child of the given subtree
+  // returns: a pointer to the parent of said child in *parent, only
+  //          if this function recurred, otherwise it is untouched.
+  treenode *find_rightmost_child(treenode **parent);
+
+  // effect: remove the root of this subtree, destroying the old root
+  // returns: the new root of the subtree
+  treenode *remove_root_of_subtree(void);
+
+  // requires: subtree is non-empty, direction is not 0
+  // returns: the child of the subtree at either the left or rightmost extreme
+  treenode *find_child_at_extreme(int direction, treenode **parent);
+
+  // effect: retrieves and possibly rebalances the left child
+  // returns: a locked left child, if it exists
+  treenode *lock_and_rebalance_left(void);
+
+  // effect: retrieves and possibly rebalances the right child
+  // returns: a locked right child, if it exists
+  treenode *lock_and_rebalance_right(void);
+
+  // returns: the estimated depth of this subtree
+  uint32_t get_depth_estimate(void) const;
+
+  // returns: true iff left subtree depth is sufficiently less than the right
+  bool left_imbalanced(int threshold) const;
+
+  // returns: true iff right subtree depth is sufficiently greater than the left
+  bool right_imbalanced(int threshold) const;
+
+  // effect: performs an O(1) rebalance, which will "heal" an imbalance by at
+  // most 1. effect: if the new root is not this node, then this node is
+  // unlocked. returns: locked node representing the new root of the rebalanced
+  // subtree
+  treenode *maybe_rebalance(void);
+
+  // returns: allocated treenode populated with a copy of the range and txnid
+  static treenode *alloc(const comparator *cmp, const keyrange &range,
+                         TXNID txnid, bool is_shared);
+
+  // requires: node is a locked root node, or an unlocked non-root node
+  static void free(treenode *node);
+
+  // effect: swaps the range/txnid pairs for node1 and node2.
+  static void swap_in_place(treenode *node1, treenode *node2);
+
+  friend class concurrent_tree_unit_test;
+};
+
+} /* namespace toku */
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/txnid_set.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/txnid_set.cc
new file mode 100644
index 000000000..4caf1e26f
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/txnid_set.cc
@@ -0,0 +1,120 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include "txnid_set.h"
+
+#include "../db.h"
+
+namespace toku {
+
+int find_by_txnid(const TXNID &txnid_a, const TXNID &txnid_b);
+int find_by_txnid(const TXNID &txnid_a, const TXNID &txnid_b) {
+  if (txnid_a < txnid_b) {
+    return -1;
+  } else if (txnid_a == txnid_b) {
+    return 0;
+  } else {
+    return 1;
+  }
+}
+
+void txnid_set::create(void) {
+  // lazily allocate the underlying omt, since it is common
+  // to create a txnid set and never put anything in it.
+  m_txnids.create_no_array();
+}
+
+void txnid_set::destroy(void) { m_txnids.destroy(); }
+
+// Return true if the given transaction id is a member of the set.
+// Otherwise, return false.
+bool txnid_set::contains(TXNID txnid) const {
+  TXNID find_txnid;
+  int r = m_txnids.find_zero<TXNID, find_by_txnid>(txnid, &find_txnid, nullptr);
+  return r == 0 ? true : false;
+}
+
+// Add a given txnid to the set
+void txnid_set::add(TXNID txnid) {
+  int r = m_txnids.insert<TXNID, find_by_txnid>(txnid, txnid, nullptr);
+  invariant(r == 0 || r == DB_KEYEXIST);
+}
+
+// Delete a given txnid from the set.
+void txnid_set::remove(TXNID txnid) {
+  uint32_t idx;
+  int r = m_txnids.find_zero<TXNID, find_by_txnid>(txnid, nullptr, &idx);
+  if (r == 0) {
+    r = m_txnids.delete_at(idx);
+    invariant_zero(r);
+  }
+}
+
+// Return the size of the set
+uint32_t txnid_set::size(void) const { return m_txnids.size(); }
+
+// Get the ith id in the set, assuming that the set is sorted.
+TXNID txnid_set::get(uint32_t i) const {
+  TXNID txnid;
+  int r = m_txnids.fetch(i, &txnid);
+  if (r == EINVAL) /* Shouldn't happen, avoid compiler warning */
+    return TXNID_NONE;
+  invariant_zero(r);
+  return txnid;
+}
+
+} /* namespace toku */
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/txnid_set.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/txnid_set.h
new file mode 100644
index 000000000..d79c24fb0
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/txnid_set.h
@@ -0,0 +1,92 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include "../portability/txn_subst.h"
+#include "../util/omt.h"
+
+namespace toku {
+
+class txnid_set {
+ public:
+  // effect: Creates an empty set. Does not malloc space for
+  //         any entries yet. That is done lazily on add().
+  void create(void);
+
+  // effect: Destroy the set's internals.
+  void destroy(void);
+
+  // returns: True if the given txnid is a member of the set.
+  bool contains(TXNID id) const;
+
+  // effect: Adds a given txnid to the set if it did not exist
+  void add(TXNID txnid);
+
+  // effect: Deletes a txnid from the set if it exists.
+  void remove(TXNID txnid);
+
+  // returns: Size of the set
+  uint32_t size(void) const;
+
+  // returns: The "i'th" id in the set, as if it were sorted.
+  TXNID get(uint32_t i) const;
+
+ private:
+  toku::omt<TXNID> m_txnids;
+
+  friend class txnid_set_unit_test;
+};
+ENSURE_POD(txnid_set);
+
+} /* namespace toku */
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/wfg.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/wfg.cc
new file mode 100644
index 000000000..24536c88e
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/wfg.cc
@@ -0,0 +1,213 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include "../db.h"
+#include "../portability/memory.h"
+// PORT #include <toku_assert.h>
+#include <memory.h>
+#include <string.h>
+
+#include "txnid_set.h"
+#include "wfg.h"
+
+namespace toku {
+
+// Create a lock request graph
+void wfg::create(void) { m_nodes.create(); }
+
+// Destroy the internals of the lock request graph
+void wfg::destroy(void) {
+  uint32_t n_nodes = m_nodes.size();
+  for (uint32_t i = 0; i < n_nodes; i++) {
+    node *n;
+    int r = m_nodes.fetch(i, &n);
+    invariant_zero(r);
+    invariant_notnull(n);
+    if (r) continue;  // Get rid of "may be used uninitialized" warning
+    node::free(n);
+  }
+  m_nodes.destroy();
+}
+
+// Add an edge (a_id, b_id) to the graph
+void wfg::add_edge(TXNID a_txnid, TXNID b_txnid) {
+  node *a_node = find_create_node(a_txnid);
+  node *b_node = find_create_node(b_txnid);
+  a_node->edges.add(b_node->txnid);
+}
+
+// Return true if a node with the given transaction id exists in the graph.
+// Return false otherwise.
+bool wfg::node_exists(TXNID txnid) {
+  node *n = find_node(txnid);
+  return n != NULL;
+}
+
+bool wfg::cycle_exists_from_node(node *target, node *head,
+                                 std::function<void(TXNID)> reporter) {
+  bool cycle_found = false;
+  head->visited = true;
+  uint32_t n_edges = head->edges.size();
+  for (uint32_t i = 0; i < n_edges && !cycle_found; i++) {
+    TXNID edge_id = head->edges.get(i);
+    if (target->txnid == edge_id) {
+      cycle_found = true;
+      if (reporter) reporter(edge_id);
+    } else {
+      node *new_head = find_node(edge_id);
+      if (new_head && !new_head->visited) {
+        cycle_found = cycle_exists_from_node(target, new_head, reporter);
+        if (cycle_found && reporter) reporter(edge_id);
+      }
+    }
+  }
+  head->visited = false;
+  return cycle_found;
+}
+
+// Return true if there exists a cycle from a given transaction id in the graph.
+// Return false otherwise.
+bool wfg::cycle_exists_from_txnid(TXNID txnid,
+                                  std::function<void(TXNID)> reporter) {
+  node *a_node = find_node(txnid);
+  bool cycles_found = false;
+  if (a_node) {
+    cycles_found = cycle_exists_from_node(a_node, a_node, reporter);
+  }
+  return cycles_found;
+}
+
+// Apply a given function f to all of the nodes in the graph.  The apply
+// function returns when the function f is called for all of the nodes in the
+// graph, or the function f returns non-zero.
+void wfg::apply_nodes(int (*fn)(TXNID id, void *extra), void *extra) {
+  int r = 0;
+  uint32_t n_nodes = m_nodes.size();
+  for (uint32_t i = 0; i < n_nodes && r == 0; i++) {
+    node *n;
+    r = m_nodes.fetch(i, &n);
+    invariant_zero(r);
+    if (r) continue;  // Get rid of "may be used uninitialized" warning
+    r = fn(n->txnid, extra);
+  }
+}
+
+// Apply a given function f to all of the edges whose origin is a given node id.
+// The apply function returns when the function f is called for all edges in the
+// graph rooted at node id, or the function f returns non-zero.
+void wfg::apply_edges(TXNID txnid,
+                      int (*fn)(TXNID txnid, TXNID edge_txnid, void *extra),
+                      void *extra) {
+  node *n = find_node(txnid);
+  if (n) {
+    int r = 0;
+    uint32_t n_edges = n->edges.size();
+    for (uint32_t i = 0; i < n_edges && r == 0; i++) {
+      r = fn(txnid, n->edges.get(i), extra);
+    }
+  }
+}
+
+// find node by id
+wfg::node *wfg::find_node(TXNID txnid) {
+  node *n = nullptr;
+  int r = m_nodes.find_zero<TXNID, find_by_txnid>(txnid, &n, nullptr);
+  invariant(r == 0 || r == DB_NOTFOUND);
+  return n;
+}
+
+// this is the omt comparison function
+// nodes are compared by their txnid.
+int wfg::find_by_txnid(node *const &node_a, const TXNID &txnid_b) {
+  TXNID txnid_a = node_a->txnid;
+  if (txnid_a < txnid_b) {
+    return -1;
+  } else if (txnid_a == txnid_b) {
+    return 0;
+  } else {
+    return 1;
+  }
+}
+
+// insert a new node
+wfg::node *wfg::find_create_node(TXNID txnid) {
+  node *n;
+  uint32_t idx;
+  int r = m_nodes.find_zero<TXNID, find_by_txnid>(txnid, &n, &idx);
+  if (r == DB_NOTFOUND) {
+    n = node::alloc(txnid);
+    r = m_nodes.insert_at(n, idx);
+    invariant_zero(r);
+  }
+  invariant_notnull(n);
+  return n;
+}
+
+wfg::node *wfg::node::alloc(TXNID txnid) {
+  node *XCALLOC(n);
+  n->txnid = txnid;
+  n->visited = false;
+  n->edges.create();
+  return n;
+}
+
+void wfg::node::free(wfg::node *n) {
+  n->edges.destroy();
+  toku_free(n);
+}
+
+} /* namespace toku */
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/wfg.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/wfg.h
new file mode 100644
index 000000000..804202170
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/locktree/wfg.h
@@ -0,0 +1,124 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include <functional>
+
+#include "../util/omt.h"
+#include "txnid_set.h"
+
+namespace toku {
+
+// A wfg is a 'wait-for' graph. A directed edge in represents one
+// txn waiting for another to finish before it can acquire a lock.
+
+class wfg {
+ public:
+  // Create a lock request graph
+  void create(void);
+
+  // Destroy the internals of the lock request graph
+  void destroy(void);
+
+  // Add an edge (a_id, b_id) to the graph
+  void add_edge(TXNID a_txnid, TXNID b_txnid);
+
+  // Return true if a node with the given transaction id exists in the graph.
+  // Return false otherwise.
+  bool node_exists(TXNID txnid);
+
+  // Return true if there exists a cycle from a given transaction id in the
+  // graph. Return false otherwise.
+  bool cycle_exists_from_txnid(TXNID txnid,
+                               std::function<void(TXNID)> reporter);
+
+  // Apply a given function f to all of the nodes in the graph.  The apply
+  // function returns when the function f is called for all of the nodes in the
+  // graph, or the function f returns non-zero.
+  void apply_nodes(int (*fn)(TXNID txnid, void *extra), void *extra);
+
+  // Apply a given function f to all of the edges whose origin is a given node
+  // id. The apply function returns when the function f is called for all edges
+  // in the graph rooted at node id, or the function f returns non-zero.
+  void apply_edges(TXNID txnid,
+                   int (*fn)(TXNID txnid, TXNID edge_txnid, void *extra),
+                   void *extra);
+
+ private:
+  struct node {
+    // txnid for this node and the associated set of edges
+    TXNID txnid;
+    txnid_set edges;
+    bool visited;
+
+    static node *alloc(TXNID txnid);
+
+    static void free(node *n);
+  };
+  ENSURE_POD(node);
+
+  toku::omt<node *> m_nodes;
+
+  node *find_node(TXNID txnid);
+
+  node *find_create_node(TXNID txnid);
+
+  bool cycle_exists_from_node(node *target, node *head,
+                              std::function<void(TXNID)> reporter);
+
+  static int find_by_txnid(node *const &node_a, const TXNID &txnid_b);
+};
+ENSURE_POD(wfg);
+
+} /* namespace toku */
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/memory.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/memory.h
new file mode 100644
index 000000000..0a621f8e0
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/memory.h
@@ -0,0 +1,215 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include <stdlib.h>
+
+#include "toku_portability.h"
+
+/* Percona memory allocation functions and macros.
+ * These are functions for malloc and free */
+
+int toku_memory_startup(void) __attribute__((constructor));
+void toku_memory_shutdown(void) __attribute__((destructor));
+
+/* Generally: errno is set to 0 or a value to indicate problems. */
+
+// Everything should call toku_malloc() instead of malloc(), and toku_calloc()
+// instead of calloc() That way the tests can can, e.g.,  replace the malloc
+// function using toku_set_func_malloc().
+void *toku_calloc(size_t nmemb, size_t size)
+    __attribute__((__visibility__("default")));
+void *toku_xcalloc(size_t nmemb, size_t size)
+    __attribute__((__visibility__("default")));
+void *toku_malloc(size_t size) __attribute__((__visibility__("default")));
+void *toku_malloc_aligned(size_t alignment, size_t size)
+    __attribute__((__visibility__("default")));
+
+// xmalloc aborts instead of return NULL if we run out of memory
+void *toku_xmalloc(size_t size) __attribute__((__visibility__("default")));
+void *toku_xrealloc(void *, size_t size)
+    __attribute__((__visibility__("default")));
+void *toku_xmalloc_aligned(size_t alignment, size_t size)
+    __attribute__((__visibility__("default")));
+// Effect: Perform a os_malloc_aligned(size) with the additional property that
+// the returned pointer is a multiple of ALIGNMENT.
+//  Fail with a resource_assert if the allocation fails (don't return an error
+//  code). If the alloc_aligned function has been set then call it instead.
+// Requires: alignment is a power of two.
+
+void toku_free(void *) __attribute__((__visibility__("default")));
+
+size_t toku_malloc_usable_size(void *p)
+    __attribute__((__visibility__("default")));
+
+/* MALLOC is a macro that helps avoid a common error:
+ * Suppose I write
+ *    struct foo *x = malloc(sizeof(struct foo));
+ * That works fine.  But if I change it to this, I've probably made an mistake:
+ *    struct foo *x = malloc(sizeof(struct bar));
+ * It can get worse, since one might have something like
+ *    struct foo *x = malloc(sizeof(struct foo *))
+ * which looks reasonable, but it allocoates enough to hold a pointer instead of
+ * the amount needed for the struct. So instead, write struct foo *MALLOC(x);
+ * and you cannot go wrong.
+ */
+#define MALLOC(v) CAST_FROM_VOIDP(v, toku_malloc(sizeof(*v)))
+/* MALLOC_N is like calloc(Except no 0ing of data):  It makes an array.  Write
+ *   int *MALLOC_N(5,x);
+ * to make an array of 5 integers.
+ */
+#define MALLOC_N(n, v) CAST_FROM_VOIDP(v, toku_malloc((n) * sizeof(*v)))
+#define MALLOC_N_ALIGNED(align, n, v) \
+  CAST_FROM_VOIDP(v, toku_malloc_aligned((align), (n) * sizeof(*v)))
+
+// CALLOC_N is like calloc with auto-figuring out size of members
+#define CALLOC_N(n, v) CAST_FROM_VOIDP(v, toku_calloc((n), sizeof(*v)))
+
+#define CALLOC(v) CALLOC_N(1, v)
+
+// XMALLOC macros are like MALLOC except they abort if the operation fails
+#define XMALLOC(v) CAST_FROM_VOIDP(v, toku_xmalloc(sizeof(*v)))
+#define XMALLOC_N(n, v) CAST_FROM_VOIDP(v, toku_xmalloc((n) * sizeof(*v)))
+#define XCALLOC_N(n, v) CAST_FROM_VOIDP(v, toku_xcalloc((n), (sizeof(*v))))
+#define XCALLOC(v) XCALLOC_N(1, v)
+#define XREALLOC(v, s) CAST_FROM_VOIDP(v, toku_xrealloc(v, s))
+#define XREALLOC_N(n, v) CAST_FROM_VOIDP(v, toku_xrealloc(v, (n) * sizeof(*v)))
+
+#define XMALLOC_N_ALIGNED(align, n, v) \
+  CAST_FROM_VOIDP(v, toku_xmalloc_aligned((align), (n) * sizeof(*v)))
+
+#define XMEMDUP(dst, src) CAST_FROM_VOIDP(dst, toku_xmemdup(src, sizeof(*src)))
+#define XMEMDUP_N(dst, src, len) CAST_FROM_VOIDP(dst, toku_xmemdup(src, len))
+
+// ZERO_ARRAY writes zeroes to a stack-allocated array
+#define ZERO_ARRAY(o)          \
+  do {                         \
+    memset((o), 0, sizeof(o)); \
+  } while (0)
+// ZERO_STRUCT writes zeroes to a stack-allocated struct
+#define ZERO_STRUCT(o)          \
+  do {                          \
+    memset(&(o), 0, sizeof(o)); \
+  } while (0)
+
+/* Copy memory.  Analogous to strdup() */
+void *toku_memdup(const void *v, size_t len);
+/* Toku-version of strdup.  Use this so that it calls toku_malloc() */
+char *toku_strdup(const char *s) __attribute__((__visibility__("default")));
+/* Toku-version of strndup.  Use this so that it calls toku_malloc() */
+char *toku_strndup(const char *s, size_t n)
+    __attribute__((__visibility__("default")));
+/* Copy memory.  Analogous to strdup() Crashes instead of returning NULL */
+void *toku_xmemdup(const void *v, size_t len)
+    __attribute__((__visibility__("default")));
+/* Toku-version of strdup.  Use this so that it calls toku_xmalloc()  Crashes
+ * instead of returning NULL */
+char *toku_xstrdup(const char *s) __attribute__((__visibility__("default")));
+
+void toku_malloc_cleanup(
+    void); /* Before exiting, call this function to free up any internal data
+              structures from toku_malloc.  Otherwise valgrind will complain of
+              memory leaks. */
+
+/* Check to see if everything malloc'd was free.  Might be a no-op depending on
+ * how memory.c is configured. */
+void toku_memory_check_all_free(void);
+/* Check to see if memory is "sane".  Might be a no-op.  Probably better to
+ * simply use valgrind. */
+void toku_do_memory_check(void);
+
+typedef void *(*malloc_fun_t)(size_t);
+typedef void (*free_fun_t)(void *);
+typedef void *(*realloc_fun_t)(void *, size_t);
+typedef void *(*malloc_aligned_fun_t)(size_t /*alignment*/, size_t /*size*/);
+typedef void *(*realloc_aligned_fun_t)(size_t /*alignment*/, void * /*pointer*/,
+                                       size_t /*size*/);
+
+void toku_set_func_malloc(malloc_fun_t f);
+void toku_set_func_xmalloc_only(malloc_fun_t f);
+void toku_set_func_malloc_only(malloc_fun_t f);
+void toku_set_func_realloc(realloc_fun_t f);
+void toku_set_func_xrealloc_only(realloc_fun_t f);
+void toku_set_func_realloc_only(realloc_fun_t f);
+void toku_set_func_free(free_fun_t f);
+
+typedef struct memory_status {
+  uint64_t malloc_count;   // number of malloc operations
+  uint64_t free_count;     // number of free operations
+  uint64_t realloc_count;  // number of realloc operations
+  uint64_t malloc_fail;    // number of malloc operations that failed
+  uint64_t realloc_fail;   // number of realloc operations that failed
+  uint64_t requested;      // number of bytes requested
+  uint64_t used;   // number of bytes used (requested + overhead), obtained from
+                   // malloc_usable_size()
+  uint64_t freed;  // number of bytes freed;
+  uint64_t max_requested_size;  // largest attempted allocation size
+  uint64_t last_failed_size;    // size of the last failed allocation attempt
+  volatile uint64_t
+      max_in_use;  // maximum memory footprint (used - freed), approximate (not
+                   // worth threadsafety overhead for exact)
+  const char *mallocator_version;
+  uint64_t mmap_threshold;
+} LOCAL_MEMORY_STATUS_S, *LOCAL_MEMORY_STATUS;
+
+void toku_memory_get_status(LOCAL_MEMORY_STATUS s);
+
+// Effect: Like toku_memory_footprint, except instead of passing p,
+//   we pass toku_malloc_usable_size(p).
+size_t toku_memory_footprint_given_usable_size(size_t touched, size_t usable);
+
+// Effect: Return an estimate how how much space an object is using, possibly by
+//   using toku_malloc_usable_size(p).
+//   If p is NULL then returns 0.
+size_t toku_memory_footprint(void *p, size_t touched);
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_assert_subst.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_assert_subst.h
new file mode 100644
index 000000000..af47800fb
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_assert_subst.h
@@ -0,0 +1,39 @@
+//
+// A replacement for toku_assert.h
+//
+#pragma once
+
+#include <assert.h>
+#include <errno.h>
+
+#ifdef NDEBUG
+
+#define assert_zero(a) ((void)(a))
+#define invariant(a) ((void)(a))
+#define invariant_notnull(a) ((void)(a))
+#define invariant_zero(a) ((void)(a))
+
+#else
+
+#define assert_zero(a) assert((a) == 0)
+#define invariant(a) assert(a)
+#define invariant_notnull(a) assert(a)
+#define invariant_zero(a) assert_zero(a)
+
+#endif
+
+#define lazy_assert_zero(a) assert_zero(a)
+
+#define paranoid_invariant_zero(a) assert_zero(a)
+#define paranoid_invariant_notnull(a) assert(a)
+#define paranoid_invariant(a) assert(a)
+
+#define ENSURE_POD(type)                                                    \
+  static_assert(                                                            \
+      std::is_standard_layout<type>::value && std::is_trivial<type>::value, \
+      #type "isn't POD")
+
+inline int get_error_errno(void) {
+  invariant(errno);
+  return errno;
+}
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_atomic.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_atomic.h
new file mode 100644
index 000000000..aaa2298fa
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_atomic.h
@@ -0,0 +1,130 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+// PORT2: #include <portability/toku_config.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "toku_assert_subst.h"
+
+__attribute__((const, always_inline)) static inline intptr_t which_cache_line(
+    intptr_t addr) {
+  static const size_t assumed_cache_line_size = 64;
+  return addr / assumed_cache_line_size;
+}
+template <typename T>
+__attribute__((const, always_inline)) static inline bool crosses_boundary(
+    T *addr, size_t width) {
+  const intptr_t int_addr = reinterpret_cast<intptr_t>(addr);
+  const intptr_t last_byte = int_addr + width - 1;
+  return which_cache_line(int_addr) != which_cache_line(last_byte);
+}
+
+template <typename T, typename U>
+__attribute__((always_inline)) static inline T toku_sync_fetch_and_add(T *addr,
+                                                                       U diff) {
+  paranoid_invariant(!crosses_boundary(addr, sizeof *addr));
+  return __sync_fetch_and_add(addr, diff);
+}
+template <typename T, typename U>
+__attribute__((always_inline)) static inline T toku_sync_add_and_fetch(T *addr,
+                                                                       U diff) {
+  paranoid_invariant(!crosses_boundary(addr, sizeof *addr));
+  return __sync_add_and_fetch(addr, diff);
+}
+template <typename T, typename U>
+__attribute__((always_inline)) static inline T toku_sync_fetch_and_sub(T *addr,
+                                                                       U diff) {
+  paranoid_invariant(!crosses_boundary(addr, sizeof *addr));
+  return __sync_fetch_and_sub(addr, diff);
+}
+template <typename T, typename U>
+__attribute__((always_inline)) static inline T toku_sync_sub_and_fetch(T *addr,
+                                                                       U diff) {
+  paranoid_invariant(!crosses_boundary(addr, sizeof *addr));
+  return __sync_sub_and_fetch(addr, diff);
+}
+template <typename T, typename U, typename V>
+__attribute__((always_inline)) static inline T toku_sync_val_compare_and_swap(
+    T *addr, U oldval, V newval) {
+  paranoid_invariant(!crosses_boundary(addr, sizeof *addr));
+  return __sync_val_compare_and_swap(addr, oldval, newval);
+}
+template <typename T, typename U, typename V>
+__attribute__((always_inline)) static inline bool
+toku_sync_bool_compare_and_swap(T *addr, U oldval, V newval) {
+  paranoid_invariant(!crosses_boundary(addr, sizeof *addr));
+  return __sync_bool_compare_and_swap(addr, oldval, newval);
+}
+
+// in case you include this but not toku_portability.h
+#pragma GCC poison __sync_fetch_and_add
+#pragma GCC poison __sync_fetch_and_sub
+#pragma GCC poison __sync_fetch_and_or
+#pragma GCC poison __sync_fetch_and_and
+#pragma GCC poison __sync_fetch_and_xor
+#pragma GCC poison __sync_fetch_and_nand
+#pragma GCC poison __sync_add_and_fetch
+#pragma GCC poison __sync_sub_and_fetch
+#pragma GCC poison __sync_or_and_fetch
+#pragma GCC poison __sync_and_and_fetch
+#pragma GCC poison __sync_xor_and_fetch
+#pragma GCC poison __sync_nand_and_fetch
+#pragma GCC poison __sync_bool_compare_and_swap
+#pragma GCC poison __sync_val_compare_and_swap
+#pragma GCC poison __sync_synchronize
+#pragma GCC poison __sync_lock_test_and_set
+#pragma GCC poison __sync_release
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_external_pthread.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_external_pthread.h
new file mode 100644
index 000000000..eb8291c1d
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_external_pthread.h
@@ -0,0 +1,83 @@
+/*
+  A wrapper around ROCKSDB_NAMESPACE::TransactionDBMutexFactory-provided
+  condition and mutex that provides toku_pthread_*-like interface. The functions
+  are named
+
+    toku_external_{mutex|cond}_XXX
+
+  Lock Tree uses this mutex and condition for interruptible (long) lock waits.
+
+  (It also still uses toku_pthread_XXX calls for mutexes/conditions for
+   shorter waits on internal objects)
+*/
+
+#pragma once
+
+#include <pthread.h>
+#include <stdint.h>
+#include <time.h>
+
+#include "rocksdb/utilities/transaction_db.h"
+#include "rocksdb/utilities/transaction_db_mutex.h"
+#include "toku_portability.h"
+
+using ROCKSDB_NAMESPACE::TransactionDBCondVar;
+using ROCKSDB_NAMESPACE::TransactionDBMutex;
+
+typedef std::shared_ptr<ROCKSDB_NAMESPACE::TransactionDBMutexFactory>
+    toku_external_mutex_factory_t;
+
+typedef std::shared_ptr<TransactionDBMutex> toku_external_mutex_t;
+typedef std::shared_ptr<TransactionDBCondVar> toku_external_cond_t;
+
+static inline void toku_external_cond_init(
+    toku_external_mutex_factory_t mutex_factory, toku_external_cond_t *cond) {
+  *cond = mutex_factory->AllocateCondVar();
+}
+
+inline void toku_external_cond_destroy(toku_external_cond_t *cond) {
+  cond->reset();  // this will destroy the managed object
+}
+
+inline void toku_external_cond_signal(toku_external_cond_t *cond) {
+  (*cond)->Notify();
+}
+
+inline void toku_external_cond_broadcast(toku_external_cond_t *cond) {
+  (*cond)->NotifyAll();
+}
+
+inline int toku_external_cond_timedwait(toku_external_cond_t *cond,
+                                        toku_external_mutex_t *mutex,
+                                        int64_t timeout_microsec) {
+  auto res = (*cond)->WaitFor(*mutex, timeout_microsec);
+  if (res.ok())
+    return 0;
+  else
+    return ETIMEDOUT;
+}
+
+inline void toku_external_mutex_init(toku_external_mutex_factory_t factory,
+                                     toku_external_mutex_t *mutex) {
+  // Use placement new: the memory has been allocated but constructor wasn't
+  // called
+  new (mutex) toku_external_mutex_t;
+  *mutex = factory->AllocateMutex();
+}
+
+inline void toku_external_mutex_lock(toku_external_mutex_t *mutex) {
+  (*mutex)->Lock();
+}
+
+inline int toku_external_mutex_trylock(toku_external_mutex_t *mutex) {
+  (*mutex)->Lock();
+  return 0;
+}
+
+inline void toku_external_mutex_unlock(toku_external_mutex_t *mutex) {
+  (*mutex)->UnLock();
+}
+
+inline void toku_external_mutex_destroy(toku_external_mutex_t *mutex) {
+  mutex->reset();  // this will destroy the managed object
+}
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_instrumentation.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_instrumentation.h
new file mode 100644
index 000000000..c967e7177
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_instrumentation.h
@@ -0,0 +1,286 @@
+/*======
+This file is part of PerconaFT.
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#pragma once
+
+#include <stdio.h>  // FILE
+
+// Performance instrumentation object identifier type
+typedef unsigned int pfs_key_t;
+
+enum class toku_instr_object_type { mutex, rwlock, cond, thread, file };
+
+struct PSI_file;
+
+struct TOKU_FILE {
+  /** The real file. */
+  FILE *file;
+  struct PSI_file *key;
+  TOKU_FILE() : file(nullptr), key(nullptr) {}
+};
+
+struct PSI_mutex;
+struct PSI_cond;
+struct PSI_rwlock;
+
+struct toku_mutex_t;
+struct toku_cond_t;
+struct toku_pthread_rwlock_t;
+
+class toku_instr_key;
+
+class toku_instr_probe_empty {
+ public:
+  explicit toku_instr_probe_empty(UU(const toku_instr_key &key)) {}
+
+  void start_with_source_location(UU(const char *src_file), UU(int src_line)) {}
+
+  void stop() {}
+};
+
+#define TOKU_PROBE_START(p) p->start_with_source_location(__FILE__, __LINE__)
+#define TOKU_PROBE_STOP(p) p->stop
+
+extern toku_instr_key toku_uninstrumented;
+
+#ifndef MYSQL_TOKUDB_ENGINE
+
+#include <pthread.h>
+
+class toku_instr_key {
+ public:
+  toku_instr_key(UU(toku_instr_object_type type), UU(const char *group),
+                 UU(const char *name)) {}
+
+  explicit toku_instr_key(UU(pfs_key_t key_id)) {}
+  // No-instrumentation constructor:
+  toku_instr_key() {}
+  ~toku_instr_key() {}
+};
+
+typedef toku_instr_probe_empty toku_instr_probe;
+
+enum class toku_instr_file_op {
+  file_stream_open,
+  file_create,
+  file_open,
+  file_delete,
+  file_rename,
+  file_read,
+  file_write,
+  file_sync,
+  file_stream_close,
+  file_close,
+  file_stat
+};
+
+struct PSI_file {};
+struct PSI_mutex {};
+
+struct toku_io_instrumentation {};
+
+inline int toku_pthread_create(UU(const toku_instr_key &key), pthread_t *thread,
+                               const pthread_attr_t *attr,
+                               void *(*start_routine)(void *), void *arg) {
+  return pthread_create(thread, attr, start_routine, arg);
+}
+
+inline void toku_instr_register_current_thread() {}
+
+inline void toku_instr_delete_current_thread() {}
+
+// Instrument file creation, opening, closing, and renaming
+inline void toku_instr_file_open_begin(UU(toku_io_instrumentation &io_instr),
+                                       UU(const toku_instr_key &key),
+                                       UU(toku_instr_file_op op),
+                                       UU(const char *name),
+                                       UU(const char *src_file),
+                                       UU(int src_line)) {}
+
+inline void toku_instr_file_stream_open_end(
+    UU(toku_io_instrumentation &io_instr), UU(TOKU_FILE &file)) {}
+
+inline void toku_instr_file_open_end(UU(toku_io_instrumentation &io_instr),
+                                     UU(int fd)) {}
+
+inline void toku_instr_file_name_close_begin(
+    UU(toku_io_instrumentation &io_instr), UU(const toku_instr_key &key),
+    UU(toku_instr_file_op op), UU(const char *name), UU(const char *src_file),
+    UU(int src_line)) {}
+
+inline void toku_instr_file_stream_close_begin(
+    UU(toku_io_instrumentation &io_instr), UU(toku_instr_file_op op),
+    UU(TOKU_FILE &file), UU(const char *src_file), UU(int src_line)) {}
+
+inline void toku_instr_file_fd_close_begin(
+    UU(toku_io_instrumentation &io_instr), UU(toku_instr_file_op op),
+    UU(int fd), UU(const char *src_file), UU(int src_line)) {}
+
+inline void toku_instr_file_close_end(UU(toku_io_instrumentation &io_instr),
+                                      UU(int result)) {}
+
+inline void toku_instr_file_io_begin(UU(toku_io_instrumentation &io_instr),
+                                     UU(toku_instr_file_op op), UU(int fd),
+                                     UU(unsigned int count),
+                                     UU(const char *src_file),
+                                     UU(int src_line)) {}
+
+inline void toku_instr_file_name_io_begin(
+    UU(toku_io_instrumentation &io_instr), UU(const toku_instr_key &key),
+    UU(toku_instr_file_op op), UU(const char *name), UU(unsigned int count),
+    UU(const char *src_file), UU(int src_line)) {}
+
+inline void toku_instr_file_stream_io_begin(
+    UU(toku_io_instrumentation &io_instr), UU(toku_instr_file_op op),
+    UU(TOKU_FILE &file), UU(unsigned int count), UU(const char *src_file),
+    UU(int src_line)) {}
+
+inline void toku_instr_file_io_end(UU(toku_io_instrumentation &io_instr),
+                                   UU(unsigned int count)) {}
+
+struct toku_mutex_t;
+
+struct toku_mutex_instrumentation {};
+
+inline PSI_mutex *toku_instr_mutex_init(UU(const toku_instr_key &key),
+                                        UU(toku_mutex_t &mutex)) {
+  return nullptr;
+}
+
+inline void toku_instr_mutex_destroy(UU(PSI_mutex *&mutex_instr)) {}
+
+inline void toku_instr_mutex_lock_start(
+    UU(toku_mutex_instrumentation &mutex_instr), UU(toku_mutex_t &mutex),
+    UU(const char *src_file), UU(int src_line)) {}
+
+inline void toku_instr_mutex_trylock_start(
+    UU(toku_mutex_instrumentation &mutex_instr), UU(toku_mutex_t &mutex),
+    UU(const char *src_file), UU(int src_line)) {}
+
+inline void toku_instr_mutex_lock_end(
+    UU(toku_mutex_instrumentation &mutex_instr),
+    UU(int pthread_mutex_lock_result)) {}
+
+inline void toku_instr_mutex_unlock(UU(PSI_mutex *mutex_instr)) {}
+
+struct toku_cond_instrumentation {};
+
+enum class toku_instr_cond_op {
+  cond_wait,
+  cond_timedwait,
+};
+
+inline PSI_cond *toku_instr_cond_init(UU(const toku_instr_key &key),
+                                      UU(toku_cond_t &cond)) {
+  return nullptr;
+}
+
+inline void toku_instr_cond_destroy(UU(PSI_cond *&cond_instr)) {}
+
+inline void toku_instr_cond_wait_start(
+    UU(toku_cond_instrumentation &cond_instr), UU(toku_instr_cond_op op),
+    UU(toku_cond_t &cond), UU(toku_mutex_t &mutex), UU(const char *src_file),
+    UU(int src_line)) {}
+
+inline void toku_instr_cond_wait_end(UU(toku_cond_instrumentation &cond_instr),
+                                     UU(int pthread_cond_wait_result)) {}
+
+inline void toku_instr_cond_signal(UU(toku_cond_t &cond)) {}
+
+inline void toku_instr_cond_broadcast(UU(toku_cond_t &cond)) {}
+
+#if 0
+// rw locks are not used 
+// rwlock instrumentation
+struct toku_rwlock_instrumentation {};
+
+inline PSI_rwlock *toku_instr_rwlock_init(UU(const toku_instr_key &key),
+                                          UU(toku_pthread_rwlock_t &rwlock)) {
+    return nullptr;
+}
+
+inline void toku_instr_rwlock_destroy(UU(PSI_rwlock *&rwlock_instr)) {}
+
+inline void toku_instr_rwlock_rdlock_wait_start(
+    UU(toku_rwlock_instrumentation &rwlock_instr),
+    UU(toku_pthread_rwlock_t &rwlock),
+    UU(const char *src_file),
+    UU(int src_line)) {}
+
+inline void toku_instr_rwlock_wrlock_wait_start(
+    UU(toku_rwlock_instrumentation &rwlock_instr),
+    UU(toku_pthread_rwlock_t &rwlock),
+    UU(const char *src_file),
+    UU(int src_line)) {}
+
+inline void toku_instr_rwlock_rdlock_wait_end(
+    UU(toku_rwlock_instrumentation &rwlock_instr),
+    UU(int pthread_rwlock_wait_result)) {}
+
+inline void toku_instr_rwlock_wrlock_wait_end(
+    UU(toku_rwlock_instrumentation &rwlock_instr),
+    UU(int pthread_rwlock_wait_result)) {}
+
+inline void toku_instr_rwlock_unlock(UU(toku_pthread_rwlock_t &rwlock)) {}
+#endif
+
+#else  // MYSQL_TOKUDB_ENGINE
+// There can be not only mysql but also mongodb or any other PFS stuff
+#include <toku_instr_mysql.h>
+#endif  // MYSQL_TOKUDB_ENGINE
+
+// Mutexes
+extern toku_instr_key manager_escalation_mutex_key;
+extern toku_instr_key manager_escalator_mutex_key;
+extern toku_instr_key manager_mutex_key;
+extern toku_instr_key treenode_mutex_key;
+extern toku_instr_key locktree_request_info_mutex_key;
+extern toku_instr_key locktree_request_info_retry_mutex_key;
+
+// condition vars
+extern toku_instr_key lock_request_m_wait_cond_key;
+extern toku_instr_key locktree_request_info_retry_cv_key;
+extern toku_instr_key manager_m_escalator_done_key;  // unused
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_portability.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_portability.h
new file mode 100644
index 000000000..9a95b38bd
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_portability.h
@@ -0,0 +1,87 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#if defined(__clang__)
+#define constexpr_static_assert(a, b)
+#else
+#define constexpr_static_assert(a, b) static_assert(a, b)
+#endif
+
+// include here, before they get deprecated
+#include <inttypes.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "toku_atomic.h"
+
+#if defined(__cplusplus)
+#include <type_traits>
+#endif
+
+#if defined(__cplusplus)
+// decltype() here gives a reference-to-pointer instead of just a pointer,
+// just use __typeof__
+#define CAST_FROM_VOIDP(name, value) name = static_cast<__typeof__(name)>(value)
+#else
+#define CAST_FROM_VOIDP(name, value) name = cast_to_typeof(name)(value)
+#endif
+
+#define UU(x) x __attribute__((__unused__))
+
+#include "toku_instrumentation.h"
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_pthread.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_pthread.h
new file mode 100644
index 000000000..571b950e1
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_pthread.h
@@ -0,0 +1,520 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include <pthread.h>
+#include <stdint.h>
+#include <time.h>
+
+#include "toku_portability.h"
+// PORT2: #include "toku_assert.h"
+
+// TODO: some things moved toku_instrumentation.h, not necessarily the best
+// place
+typedef pthread_attr_t toku_pthread_attr_t;
+typedef pthread_t toku_pthread_t;
+typedef pthread_mutex_t toku_pthread_mutex_t;
+typedef pthread_condattr_t toku_pthread_condattr_t;
+typedef pthread_cond_t toku_pthread_cond_t;
+typedef pthread_rwlockattr_t toku_pthread_rwlockattr_t;
+typedef pthread_key_t toku_pthread_key_t;
+typedef struct timespec toku_timespec_t;
+
+// TODO: break this include loop
+#include <pthread.h>
+typedef pthread_mutexattr_t toku_pthread_mutexattr_t;
+
+struct toku_mutex_t {
+  pthread_mutex_t pmutex;
+  struct PSI_mutex *psi_mutex; /* The performance schema instrumentation hook */
+#if defined(TOKU_PTHREAD_DEBUG)
+  pthread_t owner;  // = pthread_self(); // for debugging
+  bool locked;
+  bool valid;
+  pfs_key_t instr_key_id;
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+};
+
+struct toku_cond_t {
+  pthread_cond_t pcond;
+  struct PSI_cond *psi_cond;
+#if defined(TOKU_PTHREAD_DEBUG)
+  pfs_key_t instr_key_id;
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+};
+
+#if defined(TOKU_PTHREAD_DEBUG)
+#define TOKU_COND_INITIALIZER \
+  { .pcond = PTHREAD_COND_INITIALIZER, .psi_cond = nullptr, .instr_key_id = 0 }
+#else
+#define TOKU_COND_INITIALIZER \
+  { .pcond = PTHREAD_COND_INITIALIZER, .psi_cond = nullptr }
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+
+struct toku_pthread_rwlock_t {
+  pthread_rwlock_t rwlock;
+  struct PSI_rwlock *psi_rwlock;
+#if defined(TOKU_PTHREAD_DEBUG)
+  pfs_key_t instr_key_id;
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+};
+
+typedef struct toku_mutex_aligned {
+  toku_mutex_t aligned_mutex __attribute__((__aligned__(64)));
+} toku_mutex_aligned_t;
+
+// Initializing with {} will fill in a struct with all zeros.
+// But you may also need a pragma to suppress the warnings, as follows
+//
+//   #pragma GCC diagnostic push
+//   #pragma GCC diagnostic ignored "-Wmissing-field-initializers"
+//   toku_mutex_t foo = ZERO_MUTEX_INITIALIZER;
+//   #pragma GCC diagnostic pop
+//
+// In general it will be a lot of busy work to make this codebase compile
+// cleanly with -Wmissing-field-initializers
+
+#define ZERO_MUTEX_INITIALIZER \
+  {}
+
+#if defined(TOKU_PTHREAD_DEBUG)
+#define TOKU_MUTEX_INITIALIZER                                             \
+  {                                                                        \
+    .pmutex = PTHREAD_MUTEX_INITIALIZER, .psi_mutex = nullptr, .owner = 0, \
+    .locked = false, .valid = true, .instr_key_id = 0                      \
+  }
+#else
+#define TOKU_MUTEX_INITIALIZER \
+  { .pmutex = PTHREAD_MUTEX_INITIALIZER, .psi_mutex = nullptr }
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+
+// Darwin doesn't provide adaptive mutexes
+#if defined(__APPLE__)
+#define TOKU_MUTEX_ADAPTIVE PTHREAD_MUTEX_DEFAULT
+#if defined(TOKU_PTHREAD_DEBUG)
+#define TOKU_ADAPTIVE_MUTEX_INITIALIZER                                    \
+  {                                                                        \
+    .pmutex = PTHREAD_MUTEX_INITIALIZER, .psi_mutex = nullptr, .owner = 0, \
+    .locked = false, .valid = true, .instr_key_id = 0                      \
+  }
+#else
+#define TOKU_ADAPTIVE_MUTEX_INITIALIZER \
+  { .pmutex = PTHREAD_MUTEX_INITIALIZER, .psi_mutex = nullptr }
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+#else   // __FreeBSD__, __linux__, at least
+#if defined(__GLIBC__)
+#define TOKU_MUTEX_ADAPTIVE PTHREAD_MUTEX_ADAPTIVE_NP
+#else
+// not all libc (e.g. musl) implement NP (Non-POSIX) attributes
+#define TOKU_MUTEX_ADAPTIVE PTHREAD_MUTEX_DEFAULT
+#endif
+#if defined(TOKU_PTHREAD_DEBUG)
+#define TOKU_ADAPTIVE_MUTEX_INITIALIZER                                    \
+  {                                                                        \
+    .pmutex = PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP, .psi_mutex = nullptr, \
+    .owner = 0, .locked = false, .valid = true, .instr_key_id = 0          \
+  }
+#else
+#define TOKU_ADAPTIVE_MUTEX_INITIALIZER \
+  { .pmutex = PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP, .psi_mutex = nullptr }
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+#endif  // defined(__APPLE__)
+
+// Different OSes implement mutexes as different amounts of nested structs.
+// C++ will fill out all missing values with zeroes if you provide at least one
+// zero, but it needs the right amount of nesting.
+#if defined(__FreeBSD__)
+#define ZERO_COND_INITIALIZER \
+  { 0 }
+#elif defined(__APPLE__)
+#define ZERO_COND_INITIALIZER \
+  {                           \
+    { 0 }                     \
+  }
+#else  // __linux__, at least
+#define ZERO_COND_INITIALIZER \
+  {}
+#endif
+
+static inline void toku_mutexattr_init(toku_pthread_mutexattr_t *attr) {
+  int r = pthread_mutexattr_init(attr);
+  assert_zero(r);
+}
+
+static inline void toku_mutexattr_settype(toku_pthread_mutexattr_t *attr,
+                                          int type) {
+  int r = pthread_mutexattr_settype(attr, type);
+  assert_zero(r);
+}
+
+static inline void toku_mutexattr_destroy(toku_pthread_mutexattr_t *attr) {
+  int r = pthread_mutexattr_destroy(attr);
+  assert_zero(r);
+}
+
+#if defined(TOKU_PTHREAD_DEBUG)
+static inline void toku_mutex_assert_locked(const toku_mutex_t *mutex) {
+  invariant(mutex->locked);
+  invariant(mutex->owner == pthread_self());
+}
+#else
+static inline void toku_mutex_assert_locked(const toku_mutex_t *mutex
+                                            __attribute__((unused))) {}
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+
+// asserting that a mutex is unlocked only makes sense
+// if the calling thread can guaruntee that no other threads
+// are trying to lock this mutex at the time of the assertion
+//
+// a good example of this is a tree with mutexes on each node.
+// when a node is locked the caller knows that no other threads
+// can be trying to lock its childrens' mutexes. the children
+// are in one of two fixed states: locked or unlocked.
+#if defined(TOKU_PTHREAD_DEBUG)
+static inline void toku_mutex_assert_unlocked(toku_mutex_t *mutex) {
+  invariant(mutex->owner == 0);
+  invariant(!mutex->locked);
+}
+#else
+static inline void toku_mutex_assert_unlocked(toku_mutex_t *mutex
+                                              __attribute__((unused))) {}
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+
+#define toku_mutex_lock(M) \
+  toku_mutex_lock_with_source_location(M, __FILE__, __LINE__)
+
+static inline void toku_cond_init(toku_cond_t *cond,
+                                  const toku_pthread_condattr_t *attr) {
+  int r = pthread_cond_init(&cond->pcond, attr);
+  assert_zero(r);
+}
+
+#define toku_mutex_trylock(M) \
+  toku_mutex_trylock_with_source_location(M, __FILE__, __LINE__)
+
+inline void toku_mutex_unlock(toku_mutex_t *mutex) {
+#if defined(TOKU_PTHREAD_DEBUG)
+  invariant(mutex->owner == pthread_self());
+  invariant(mutex->valid);
+  invariant(mutex->locked);
+  mutex->locked = false;
+  mutex->owner = 0;
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+  toku_instr_mutex_unlock(mutex->psi_mutex);
+  int r = pthread_mutex_unlock(&mutex->pmutex);
+  assert_zero(r);
+}
+
+inline void toku_mutex_lock_with_source_location(toku_mutex_t *mutex,
+                                                 const char *src_file,
+                                                 int src_line) {
+  toku_mutex_instrumentation mutex_instr;
+  toku_instr_mutex_lock_start(mutex_instr, *mutex, src_file, src_line);
+
+  const int r = pthread_mutex_lock(&mutex->pmutex);
+  toku_instr_mutex_lock_end(mutex_instr, r);
+
+  assert_zero(r);
+#if defined(TOKU_PTHREAD_DEBUG)
+  invariant(mutex->valid);
+  invariant(!mutex->locked);
+  invariant(mutex->owner == 0);
+  mutex->locked = true;
+  mutex->owner = pthread_self();
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+}
+
+inline int toku_mutex_trylock_with_source_location(toku_mutex_t *mutex,
+                                                   const char *src_file,
+                                                   int src_line) {
+  toku_mutex_instrumentation mutex_instr;
+  toku_instr_mutex_trylock_start(mutex_instr, *mutex, src_file, src_line);
+
+  const int r = pthread_mutex_lock(&mutex->pmutex);
+  toku_instr_mutex_lock_end(mutex_instr, r);
+
+#if defined(TOKU_PTHREAD_DEBUG)
+  if (r == 0) {
+    invariant(mutex->valid);
+    invariant(!mutex->locked);
+    invariant(mutex->owner == 0);
+    mutex->locked = true;
+    mutex->owner = pthread_self();
+  }
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+  return r;
+}
+
+#define toku_cond_wait(C, M) \
+  toku_cond_wait_with_source_location(C, M, __FILE__, __LINE__)
+
+#define toku_cond_timedwait(C, M, W) \
+  toku_cond_timedwait_with_source_location(C, M, W, __FILE__, __LINE__)
+
+inline void toku_cond_init(const toku_instr_key &key, toku_cond_t *cond,
+                           const pthread_condattr_t *attr) {
+  toku_instr_cond_init(key, *cond);
+  int r = pthread_cond_init(&cond->pcond, attr);
+  assert_zero(r);
+}
+
+inline void toku_cond_destroy(toku_cond_t *cond) {
+  toku_instr_cond_destroy(cond->psi_cond);
+  int r = pthread_cond_destroy(&cond->pcond);
+  assert_zero(r);
+}
+
+inline void toku_cond_wait_with_source_location(toku_cond_t *cond,
+                                                toku_mutex_t *mutex,
+                                                const char *src_file,
+                                                int src_line) {
+#if defined(TOKU_PTHREAD_DEBUG)
+  invariant(mutex->locked);
+  mutex->locked = false;
+  mutex->owner = 0;
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+
+  /* Instrumentation start */
+  toku_cond_instrumentation cond_instr;
+  toku_instr_cond_wait_start(cond_instr, toku_instr_cond_op::cond_wait, *cond,
+                             *mutex, src_file, src_line);
+
+  /* Instrumented code */
+  const int r = pthread_cond_wait(&cond->pcond, &mutex->pmutex);
+
+  /* Instrumentation end */
+  toku_instr_cond_wait_end(cond_instr, r);
+
+  assert_zero(r);
+#if defined(TOKU_PTHREAD_DEBUG)
+  invariant(!mutex->locked);
+  mutex->locked = true;
+  mutex->owner = pthread_self();
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+}
+
+inline int toku_cond_timedwait_with_source_location(toku_cond_t *cond,
+                                                    toku_mutex_t *mutex,
+                                                    toku_timespec_t *wakeup_at,
+                                                    const char *src_file,
+                                                    int src_line) {
+#if defined(TOKU_PTHREAD_DEBUG)
+  invariant(mutex->locked);
+  mutex->locked = false;
+  mutex->owner = 0;
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+
+  /* Instrumentation start */
+  toku_cond_instrumentation cond_instr;
+  toku_instr_cond_wait_start(cond_instr, toku_instr_cond_op::cond_timedwait,
+                             *cond, *mutex, src_file, src_line);
+
+  /* Instrumented code */
+  const int r = pthread_cond_timedwait(&cond->pcond, &mutex->pmutex, wakeup_at);
+
+  /* Instrumentation end */
+  toku_instr_cond_wait_end(cond_instr, r);
+
+#if defined(TOKU_PTHREAD_DEBUG)
+  invariant(!mutex->locked);
+  mutex->locked = true;
+  mutex->owner = pthread_self();
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+  return r;
+}
+
+inline void toku_cond_signal(toku_cond_t *cond) {
+  toku_instr_cond_signal(*cond);
+  const int r = pthread_cond_signal(&cond->pcond);
+  assert_zero(r);
+}
+
+inline void toku_cond_broadcast(toku_cond_t *cond) {
+  toku_instr_cond_broadcast(*cond);
+  const int r = pthread_cond_broadcast(&cond->pcond);
+  assert_zero(r);
+}
+
+inline void toku_mutex_init(const toku_instr_key &key, toku_mutex_t *mutex,
+                            const toku_pthread_mutexattr_t *attr) {
+#if defined(TOKU_PTHREAD_DEBUG)
+  mutex->valid = true;
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+  toku_instr_mutex_init(key, *mutex);
+  const int r = pthread_mutex_init(&mutex->pmutex, attr);
+  assert_zero(r);
+#if defined(TOKU_PTHREAD_DEBUG)
+  mutex->locked = false;
+  invariant(mutex->valid);
+  mutex->valid = true;
+  mutex->owner = 0;
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+}
+
+inline void toku_mutex_destroy(toku_mutex_t *mutex) {
+#if defined(TOKU_PTHREAD_DEBUG)
+  invariant(mutex->valid);
+  mutex->valid = false;
+  invariant(!mutex->locked);
+#endif  // defined(TOKU_PTHREAD_DEBUG)
+  toku_instr_mutex_destroy(mutex->psi_mutex);
+  int r = pthread_mutex_destroy(&mutex->pmutex);
+  assert_zero(r);
+}
+
+#define toku_pthread_rwlock_rdlock(RW) \
+  toku_pthread_rwlock_rdlock_with_source_location(RW, __FILE__, __LINE__)
+
+#define toku_pthread_rwlock_wrlock(RW) \
+  toku_pthread_rwlock_wrlock_with_source_location(RW, __FILE__, __LINE__)
+
+#if 0
+inline void toku_pthread_rwlock_init(
+    const toku_instr_key &key,
+    toku_pthread_rwlock_t *__restrict rwlock,
+    const toku_pthread_rwlockattr_t *__restrict attr) {
+    toku_instr_rwlock_init(key, *rwlock);
+    int r = pthread_rwlock_init(&rwlock->rwlock, attr);
+    assert_zero(r);
+}
+
+inline void toku_pthread_rwlock_destroy(toku_pthread_rwlock_t *rwlock) {
+    toku_instr_rwlock_destroy(rwlock->psi_rwlock);
+    int r = pthread_rwlock_destroy(&rwlock->rwlock);
+    assert_zero(r);
+}
+
+inline void toku_pthread_rwlock_rdlock_with_source_location(
+    toku_pthread_rwlock_t *rwlock,
+    const char *src_file,
+    uint src_line) {
+
+    /* Instrumentation start */
+    toku_rwlock_instrumentation rwlock_instr;
+    toku_instr_rwlock_rdlock_wait_start(
+        rwlock_instr, *rwlock, src_file, src_line);
+    /* Instrumented code */
+    const int r = pthread_rwlock_rdlock(&rwlock->rwlock);
+
+    /* Instrumentation end */
+    toku_instr_rwlock_rdlock_wait_end(rwlock_instr, r);
+
+    assert_zero(r);
+}
+
+inline void toku_pthread_rwlock_wrlock_with_source_location(
+    toku_pthread_rwlock_t *rwlock,
+    const char *src_file,
+    uint src_line) {
+
+    /* Instrumentation start */
+    toku_rwlock_instrumentation rwlock_instr;
+    toku_instr_rwlock_wrlock_wait_start(
+        rwlock_instr, *rwlock, src_file, src_line);
+    /* Instrumented code */
+    const int r = pthread_rwlock_wrlock(&rwlock->rwlock);
+
+    /* Instrumentation end */
+    toku_instr_rwlock_wrlock_wait_end(rwlock_instr, r);
+
+    assert_zero(r);
+}
+
+inline void toku_pthread_rwlock_rdunlock(toku_pthread_rwlock_t *rwlock) {
+    toku_instr_rwlock_unlock(*rwlock);
+    const int r = pthread_rwlock_unlock(&rwlock->rwlock);
+    assert_zero(r);
+}
+
+inline void toku_pthread_rwlock_wrunlock(toku_pthread_rwlock_t *rwlock) {
+    toku_instr_rwlock_unlock(*rwlock);
+    const int r = pthread_rwlock_unlock(&rwlock->rwlock);
+    assert_zero(r);
+}
+#endif
+
+static inline int toku_pthread_join(toku_pthread_t thread, void **value_ptr) {
+  return pthread_join(thread, value_ptr);
+}
+
+static inline int toku_pthread_detach(toku_pthread_t thread) {
+  return pthread_detach(thread);
+}
+
+static inline int toku_pthread_key_create(toku_pthread_key_t *key,
+                                          void (*destroyf)(void *)) {
+  return pthread_key_create(key, destroyf);
+}
+
+static inline int toku_pthread_key_delete(toku_pthread_key_t key) {
+  return pthread_key_delete(key);
+}
+
+static inline void *toku_pthread_getspecific(toku_pthread_key_t key) {
+  return pthread_getspecific(key);
+}
+
+static inline int toku_pthread_setspecific(toku_pthread_key_t key, void *data) {
+  return pthread_setspecific(key, data);
+}
+
+int toku_pthread_yield(void) __attribute__((__visibility__("default")));
+
+static inline toku_pthread_t toku_pthread_self(void) { return pthread_self(); }
+
+static inline void *toku_pthread_done(void *exit_value) {
+  toku_instr_delete_current_thread();
+  pthread_exit(exit_value);
+  return nullptr;  // Avoid compiler warning
+}
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_race_tools.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_race_tools.h
new file mode 100644
index 000000000..3cb5b5790
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_race_tools.h
@@ -0,0 +1,179 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+// PORT2: #include <portability/toku_config.h>
+
+#ifdef HAVE_valgrind
+#undef USE_VALGRIND
+#define USE_VALGRIND 1
+#endif
+
+#if defined(__linux__) && USE_VALGRIND
+
+#include <valgrind/drd.h>
+#include <valgrind/helgrind.h>
+
+#define TOKU_ANNOTATE_NEW_MEMORY(p, size) ANNOTATE_NEW_MEMORY(p, size)
+#define TOKU_VALGRIND_HG_ENABLE_CHECKING(p, size) \
+  VALGRIND_HG_ENABLE_CHECKING(p, size)
+#define TOKU_VALGRIND_HG_DISABLE_CHECKING(p, size) \
+  VALGRIND_HG_DISABLE_CHECKING(p, size)
+#define TOKU_DRD_IGNORE_VAR(v) DRD_IGNORE_VAR(v)
+#define TOKU_DRD_STOP_IGNORING_VAR(v) DRD_STOP_IGNORING_VAR(v)
+#define TOKU_ANNOTATE_IGNORE_READS_BEGIN() ANNOTATE_IGNORE_READS_BEGIN()
+#define TOKU_ANNOTATE_IGNORE_READS_END() ANNOTATE_IGNORE_READS_END()
+#define TOKU_ANNOTATE_IGNORE_WRITES_BEGIN() ANNOTATE_IGNORE_WRITES_BEGIN()
+#define TOKU_ANNOTATE_IGNORE_WRITES_END() ANNOTATE_IGNORE_WRITES_END()
+
+/*
+ * How to make helgrind happy about tree rotations and new mutex orderings:
+ *
+ * // Tell helgrind that we unlocked it so that the next call doesn't get a
+ * "destroyed a locked mutex" error.
+ * // Tell helgrind that we destroyed the mutex.
+ * VALGRIND_HG_MUTEX_UNLOCK_PRE(&locka);
+ * VALGRIND_HG_MUTEX_DESTROY_PRE(&locka);
+ *
+ * // And recreate it.  It would be better to simply be able to say that the
+ * order on these two can now be reversed, because this code forgets all the
+ * ordering information for this mutex.
+ * // Then tell helgrind that we have locked it again.
+ * VALGRIND_HG_MUTEX_INIT_POST(&locka, 0);
+ * VALGRIND_HG_MUTEX_LOCK_POST(&locka);
+ *
+ * When the ordering of two locks changes, we don't need tell Helgrind about do
+ * both locks.  Just one is good enough.
+ */
+
+#define TOKU_VALGRIND_RESET_MUTEX_ORDERING_INFO(mutex) \
+  VALGRIND_HG_MUTEX_UNLOCK_PRE(mutex);                 \
+  VALGRIND_HG_MUTEX_DESTROY_PRE(mutex);                \
+  VALGRIND_HG_MUTEX_INIT_POST(mutex, 0);               \
+  VALGRIND_HG_MUTEX_LOCK_POST(mutex);
+
+#else  // !defined(__linux__) || !USE_VALGRIND
+
+#define NVALGRIND 1
+#define TOKU_ANNOTATE_NEW_MEMORY(p, size) ((void)0)
+#define TOKU_VALGRIND_HG_ENABLE_CHECKING(p, size) ((void)0)
+#define TOKU_VALGRIND_HG_DISABLE_CHECKING(p, size) ((void)0)
+#define TOKU_DRD_IGNORE_VAR(v)
+#define TOKU_DRD_STOP_IGNORING_VAR(v)
+#define TOKU_ANNOTATE_IGNORE_READS_BEGIN() ((void)0)
+#define TOKU_ANNOTATE_IGNORE_READS_END() ((void)0)
+#define TOKU_ANNOTATE_IGNORE_WRITES_BEGIN() ((void)0)
+#define TOKU_ANNOTATE_IGNORE_WRITES_END() ((void)0)
+#define TOKU_VALGRIND_RESET_MUTEX_ORDERING_INFO(mutex)
+#undef RUNNING_ON_VALGRIND
+#define RUNNING_ON_VALGRIND (0U)
+#endif
+
+// Valgrind 3.10.1 (and previous versions).
+// Problems with VALGRIND_HG_DISABLE_CHECKING and VALGRIND_HG_ENABLE_CHECKING.
+// Helgrind's implementation of disable and enable checking causes false races
+// to be reported.  In addition, the race report does not include ANY
+// information about the code that uses the helgrind disable and enable
+// functions.  Therefore, it is very difficult to figure out the cause of the
+// race. DRD does implement the disable and enable functions.
+
+// Problems with ANNOTATE_IGNORE_READS.
+// Helgrind does not implement ignore reads.
+// Annotate ignore reads is the way to inform DRD to ignore racy reads.
+
+// FT code uses unsafe reads in several places.  These unsafe reads have been
+// noted as valid since they use the toku_unsafe_fetch function. Unfortunately,
+// this causes helgrind to report erroneous data races which makes use of
+// helgrind problematic.
+
+// Unsafely fetch and return a `T' from src, telling drd to ignore
+// racey access to src for the next sizeof(*src) bytes
+template <typename T>
+T toku_unsafe_fetch(T *src) {
+  if (0)
+    TOKU_VALGRIND_HG_DISABLE_CHECKING(src,
+                                      sizeof *src);  // disabled, see comment
+  TOKU_ANNOTATE_IGNORE_READS_BEGIN();
+  T r = *src;
+  TOKU_ANNOTATE_IGNORE_READS_END();
+  if (0)
+    TOKU_VALGRIND_HG_ENABLE_CHECKING(src,
+                                     sizeof *src);  // disabled, see comment
+  return r;
+}
+
+template <typename T>
+T toku_unsafe_fetch(T &src) {
+  return toku_unsafe_fetch(&src);
+}
+
+// Unsafely set a `T' value into *dest from src, telling drd to ignore
+// racey access to dest for the next sizeof(*dest) bytes
+template <typename T>
+void toku_unsafe_set(T *dest, const T src) {
+  if (0)
+    TOKU_VALGRIND_HG_DISABLE_CHECKING(dest,
+                                      sizeof *dest);  // disabled, see comment
+  TOKU_ANNOTATE_IGNORE_WRITES_BEGIN();
+  *dest = src;
+  TOKU_ANNOTATE_IGNORE_WRITES_END();
+  if (0)
+    TOKU_VALGRIND_HG_ENABLE_CHECKING(dest,
+                                     sizeof *dest);  // disabled, see comment
+}
+
+template <typename T>
+void toku_unsafe_set(T &dest, const T src) {
+  toku_unsafe_set(&dest, src);
+}
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_time.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_time.h
new file mode 100644
index 000000000..46111e7f0
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/toku_time.h
@@ -0,0 +1,193 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+// PORT2: #include "toku_config.h"
+
+#include <stdint.h>
+#include <sys/time.h>
+#include <time.h>
+#if defined(__powerpc__)
+#include <sys/platform/ppc.h>
+#endif
+
+#if 0
+static inline float toku_tdiff (struct timeval *a, struct timeval *b) {
+    return (float)((a->tv_sec - b->tv_sec) + 1e-6 * (a->tv_usec - b->tv_usec));
+}
+// PORT2: temporary:
+#define HAVE_CLOCK_REALTIME
+#if !defined(HAVE_CLOCK_REALTIME)
+// OS X does not have clock_gettime, we fake clockid_t for the interface, and we'll implement it with clock_get_time.
+typedef int clockid_t;
+// just something bogus, it doesn't matter, we just want to make sure we're
+// only supporting this mode because we're not sure we can support other modes
+// without a real clock_gettime()
+#define CLOCK_REALTIME 0x01867234
+#endif
+int toku_clock_gettime(clockid_t clk_id, struct timespec *ts) __attribute__((__visibility__("default")));
+#endif
+
+// *************** Performance timers ************************
+// What do you really want from a performance timer:
+//  (1) Can determine actual time of day from the performance time.
+//  (2) Time goes forward, never backward.
+//  (3) Same time on different processors (or even different machines).
+//  (4) Time goes forward at a constant rate (doesn't get faster and slower)
+//  (5) Portable.
+//  (6) Getting the time is cheap.
+// Unfortuately it seems tough to get Properties 1-5.  So we go for Property 6,,
+// but we abstract it. We offer a type tokutime_t which can hold the time. This
+// type can be subtracted to get a time difference. We can get the present time
+// cheaply. We can convert this type to seconds (but that can be expensive). The
+// implementation is to use RDTSC (hence we lose property 3: not portable).
+// Recent machines have constant_tsc in which case we get property (4).
+// Recent OSs on recent machines (that have RDTSCP) fix the per-processor clock
+// skew, so we get property (3). We get property 2 with RDTSC (as long as
+// there's not any skew). We don't even try to get propety 1, since we don't
+// need it. The decision here is that these times are really accurate only on
+// modern machines with modern OSs.
+typedef uint64_t tokutime_t;  // Time type used in by tokutek timers.
+
+#if 0
+// The value of tokutime_t is not specified here. 
+// It might be microseconds since 1/1/1970 (if gettimeofday() is
+// used), or clock cycles since boot (if rdtsc is used).  Or something
+// else.
+// Two tokutime_t values can be subtracted to get a time difference.
+// Use tokutime_to_seconds to that convert difference  to seconds.
+// We want get_tokutime() to be fast, but don't care so much about tokutime_to_seconds();
+//
+// For accurate time calculations do the subtraction in the right order:
+//   Right:  tokutime_to_seconds(t1-t2);
+//   Wrong   tokutime_to_seconds(t1)-toku_time_to_seconds(t2);
+// Doing it the wrong way is likely to result in loss of precision.
+// A double can hold numbers up to about 53 bits.  RDTSC which uses about 33 bits every second, so that leaves
+// 2^20 seconds from booting (about 2 weeks) before the RDTSC value cannot be represented accurately as a double.
+//
+double tokutime_to_seconds(tokutime_t)  __attribute__((__visibility__("default"))); // Convert tokutime to seconds.
+
+#endif
+
+// Get the value of tokutime for right now.  We want this to be fast, so we
+// expose the implementation as RDTSC.
+static inline tokutime_t toku_time_now(void) {
+#if defined(__x86_64__) || defined(__i386__)
+  uint32_t lo, hi;
+  __asm__ __volatile__("rdtsc" : "=a"(lo), "=d"(hi));
+  return (uint64_t)hi << 32 | lo;
+#elif defined(__aarch64__)
+  uint64_t result;
+  __asm __volatile__("mrs %[rt], cntvct_el0" : [rt] "=r"(result));
+  return result;
+#elif defined(__powerpc__)
+  return __ppc_get_timebase();
+#elif defined(__s390x__)
+  uint64_t result;
+  asm volatile("stckf %0" : "=Q"(result) : : "cc");
+  return result;
+#elif defined(__riscv) && __riscv_xlen == 32
+  uint32_t cycles_lo, cycles_hi0, cycles_hi1;
+  // Implemented in assembly because Clang insisted on branching.
+  asm volatile(
+      "rdcycleh %0\n"
+      "rdcycle %1\n"
+      "rdcycleh %2\n"
+      "sub %0, %0, %2\n"
+      "seqz %0, %0\n"
+      "sub %0, zero, %0\n"
+      "and %1, %1, %0\n"
+      : "=r"(cycles_hi0), "=r"(cycles_lo), "=r"(cycles_hi1));
+  return (static_cast<uint64_t>(cycles_hi1) << 32) | cycles_lo;
+#elif defined(__riscv) && __riscv_xlen == 64
+  uint64_t cycles;
+  asm volatile("rdcycle %0" : "=r"(cycles));
+  return cycles;
+#else
+#error No timer implementation for this platform
+#endif
+}
+
+static inline uint64_t toku_current_time_microsec(void) {
+  struct timeval t;
+  gettimeofday(&t, NULL);
+  return t.tv_sec * (1UL * 1000 * 1000) + t.tv_usec;
+}
+
+#if 0
+// sleep microseconds
+static inline void toku_sleep_microsec(uint64_t ms) {
+    struct timeval  t;
+
+    t.tv_sec = ms / 1000000;
+    t.tv_usec = ms % 1000000;
+
+    select(0, NULL, NULL, NULL, &t);
+}
+#endif
+
+/*
+  PORT: Usage of this file:
+
+  uint64_t toku_current_time_microsec()   // uses gettimeoday
+      is used to track how much time various operations took (for example, lock
+      escalation). (TODO: it is not clear why these operations are tracked with
+      microsecond precision while others use nanoseconds)
+
+  tokutime_t toku_time_now() // uses rdtsc
+      seems to be used for a very similar purpose. This has greater precision
+
+  RocksDB environment provides Env::Default()->NowMicros() and NowNanos() which
+  should be adequate substitutes.
+*/
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/txn_subst.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/txn_subst.h
new file mode 100644
index 000000000..803914862
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/portability/txn_subst.h
@@ -0,0 +1,27 @@
+//
+// A substitute for ft/txn/txn.h
+//
+#pragma once
+
+#include <set>
+
+#include "../util/omt.h"
+
+typedef uint64_t TXNID;
+#define TXNID_NONE ((TXNID)0)
+
+// A set of transactions
+//  (TODO: consider using class toku::txnid_set. The reason for using STL
+//   container was that its API is easier)
+class TxnidVector : public std::set<TXNID> {
+ public:
+  bool contains(TXNID txnid) { return find(txnid) != end(); }
+};
+
+// A value for lock structures with a meaning "the lock is owned by multiple
+// transactions (and one has to check the TxnidVector to get their ids)
+#define TXNID_SHARED (TXNID(-1))
+
+// Auxiliary value meaning "any transaction id will do".  No real transaction
+// may have this is as id.
+#define TXNID_ANY (TXNID(-2))
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/standalone_port.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/standalone_port.cc
new file mode 100644
index 000000000..50dc879ce
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/standalone_port.cc
@@ -0,0 +1,132 @@
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+/*
+  This is a dump ground to make Lock Tree work without the rest of TokuDB.
+*/
+#include <string.h>
+
+#include "db.h"
+#include "ft/ft-status.h"
+#include "portability/memory.h"
+#include "util/dbt.h"
+
+// portability/os_malloc.cc
+
+void toku_free(void *p) { free(p); }
+
+void *toku_xmalloc(size_t size) { return malloc(size); }
+
+void *toku_xrealloc(void *v, size_t size) { return realloc(v, size); }
+
+void *toku_xmemdup(const void *v, size_t len) {
+  void *p = toku_xmalloc(len);
+  memcpy(p, v, len);
+  return p;
+}
+
+// TODO: what are the X-functions? Xcalloc, Xrealloc?
+void *toku_xcalloc(size_t nmemb, size_t size) { return calloc(nmemb, size); }
+
+// ft-ft-opts.cc:
+
+// locktree
+toku_instr_key lock_request_m_wait_cond_key;
+toku_instr_key manager_m_escalator_done_key;
+toku_instr_key locktree_request_info_mutex_key;
+toku_instr_key locktree_request_info_retry_mutex_key;
+toku_instr_key locktree_request_info_retry_cv_key;
+
+toku_instr_key treenode_mutex_key;
+toku_instr_key manager_mutex_key;
+toku_instr_key manager_escalation_mutex_key;
+toku_instr_key manager_escalator_mutex_key;
+
+// portability/memory.cc
+size_t toku_memory_footprint(void *, size_t touched) { return touched; }
+
+// ft/ft-status.c
+// PORT2: note: the @c parameter to TOKUFT_STATUS_INIT must not start with
+//   "TOKU"
+LTM_STATUS_S ltm_status;
+void LTM_STATUS_S::init() {
+  if (m_initialized) return;
+#define LTM_STATUS_INIT(k, c, t, l)                    \
+  TOKUFT_STATUS_INIT((*this), k, c, t, "locktree: " l, \
+                     TOKU_ENGINE_STATUS | TOKU_GLOBAL_STATUS)
+  LTM_STATUS_INIT(LTM_SIZE_CURRENT, LOCKTREE_MEMORY_SIZE, STATUS_UINT64,
+                  "memory size");
+  LTM_STATUS_INIT(LTM_SIZE_LIMIT, LOCKTREE_MEMORY_SIZE_LIMIT, STATUS_UINT64,
+                  "memory size limit");
+  LTM_STATUS_INIT(LTM_ESCALATION_COUNT, LOCKTREE_ESCALATION_NUM, STATUS_UINT64,
+                  "number of times lock escalation ran");
+  LTM_STATUS_INIT(LTM_ESCALATION_TIME, LOCKTREE_ESCALATION_SECONDS,
+                  STATUS_TOKUTIME, "time spent running escalation (seconds)");
+  LTM_STATUS_INIT(LTM_ESCALATION_LATEST_RESULT,
+                  LOCKTREE_LATEST_POST_ESCALATION_MEMORY_SIZE, STATUS_UINT64,
+                  "latest post-escalation memory size");
+  LTM_STATUS_INIT(LTM_NUM_LOCKTREES, LOCKTREE_OPEN_CURRENT, STATUS_UINT64,
+                  "number of locktrees open now");
+  LTM_STATUS_INIT(LTM_LOCK_REQUESTS_PENDING, LOCKTREE_PENDING_LOCK_REQUESTS,
+                  STATUS_UINT64, "number of pending lock requests");
+  LTM_STATUS_INIT(LTM_STO_NUM_ELIGIBLE, LOCKTREE_STO_ELIGIBLE_NUM,
+                  STATUS_UINT64, "number of locktrees eligible for the STO");
+  LTM_STATUS_INIT(LTM_STO_END_EARLY_COUNT, LOCKTREE_STO_ENDED_NUM,
+                  STATUS_UINT64,
+                  "number of times a locktree ended the STO early");
+  LTM_STATUS_INIT(LTM_STO_END_EARLY_TIME, LOCKTREE_STO_ENDED_SECONDS,
+                  STATUS_TOKUTIME, "time spent ending the STO early (seconds)");
+  LTM_STATUS_INIT(LTM_WAIT_COUNT, LOCKTREE_WAIT_COUNT, STATUS_UINT64,
+                  "number of wait locks");
+  LTM_STATUS_INIT(LTM_WAIT_TIME, LOCKTREE_WAIT_TIME, STATUS_UINT64,
+                  "time waiting for locks");
+  LTM_STATUS_INIT(LTM_LONG_WAIT_COUNT, LOCKTREE_LONG_WAIT_COUNT, STATUS_UINT64,
+                  "number of long wait locks");
+  LTM_STATUS_INIT(LTM_LONG_WAIT_TIME, LOCKTREE_LONG_WAIT_TIME, STATUS_UINT64,
+                  "long time waiting for locks");
+  LTM_STATUS_INIT(LTM_TIMEOUT_COUNT, LOCKTREE_TIMEOUT_COUNT, STATUS_UINT64,
+                  "number of lock timeouts");
+  LTM_STATUS_INIT(LTM_WAIT_ESCALATION_COUNT, LOCKTREE_WAIT_ESCALATION_COUNT,
+                  STATUS_UINT64, "number of waits on lock escalation");
+  LTM_STATUS_INIT(LTM_WAIT_ESCALATION_TIME, LOCKTREE_WAIT_ESCALATION_TIME,
+                  STATUS_UINT64, "time waiting on lock escalation");
+  LTM_STATUS_INIT(LTM_LONG_WAIT_ESCALATION_COUNT,
+                  LOCKTREE_LONG_WAIT_ESCALATION_COUNT, STATUS_UINT64,
+                  "number of long waits on lock escalation");
+  LTM_STATUS_INIT(LTM_LONG_WAIT_ESCALATION_TIME,
+                  LOCKTREE_LONG_WAIT_ESCALATION_TIME, STATUS_UINT64,
+                  "long time waiting on lock escalation");
+
+  m_initialized = true;
+#undef LTM_STATUS_INIT
+}
+void LTM_STATUS_S::destroy() {
+  if (!m_initialized) return;
+  for (int i = 0; i < LTM_STATUS_NUM_ROWS; ++i) {
+    if (status[i].type == STATUS_PARCOUNT) {
+      // PORT: TODO?? destroy_partitioned_counter(status[i].value.parcount);
+    }
+  }
+}
+
+int toku_keycompare(const void *key1, size_t key1len, const void *key2,
+                    size_t key2len) {
+  size_t comparelen = key1len < key2len ? key1len : key2len;
+  int c = memcmp(key1, key2, comparelen);
+  if (__builtin_expect(c != 0, 1)) {
+    return c;
+  } else {
+    if (key1len < key2len) {
+      return -1;
+    } else if (key1len > key2len) {
+      return 1;
+    } else {
+      return 0;
+    }
+  }
+}
+
+int toku_builtin_compare_fun(const DBT *a, const DBT *b) {
+  return toku_keycompare(a->data, a->size, b->data, b->size);
+}
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/dbt.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/dbt.cc
new file mode 100644
index 000000000..63cc3a267
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/dbt.cc
@@ -0,0 +1,153 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include "dbt.h"
+
+#include <string.h>
+
+#include "../db.h"
+#include "../portability/memory.h"
+
+DBT *toku_init_dbt(DBT *dbt) {
+  memset(dbt, 0, sizeof(*dbt));
+  return dbt;
+}
+
+DBT toku_empty_dbt(void) {
+  static const DBT empty_dbt = {.data = 0, .size = 0, .ulen = 0, .flags = 0};
+  return empty_dbt;
+}
+
+DBT *toku_init_dbt_flags(DBT *dbt, uint32_t flags) {
+  toku_init_dbt(dbt);
+  dbt->flags = flags;
+  return dbt;
+}
+
+void toku_destroy_dbt(DBT *dbt) {
+  switch (dbt->flags) {
+    case DB_DBT_MALLOC:
+    case DB_DBT_REALLOC:
+      toku_free(dbt->data);
+      toku_init_dbt(dbt);
+      break;
+  }
+}
+
+DBT *toku_fill_dbt(DBT *dbt, const void *k, size_t len) {
+  toku_init_dbt(dbt);
+  dbt->size = len;
+  dbt->data = (char *)k;
+  return dbt;
+}
+
+DBT *toku_memdup_dbt(DBT *dbt, const void *k, size_t len) {
+  toku_init_dbt_flags(dbt, DB_DBT_MALLOC);
+  dbt->size = len;
+  dbt->data = toku_xmemdup(k, len);
+  return dbt;
+}
+
+DBT *toku_copyref_dbt(DBT *dst, const DBT src) {
+  dst->flags = 0;
+  dst->ulen = 0;
+  dst->size = src.size;
+  dst->data = src.data;
+  return dst;
+}
+
+DBT *toku_clone_dbt(DBT *dst, const DBT &src) {
+  return toku_memdup_dbt(dst, src.data, src.size);
+}
+
+void toku_sdbt_cleanup(struct simple_dbt *sdbt) {
+  if (sdbt->data) toku_free(sdbt->data);
+  memset(sdbt, 0, sizeof(*sdbt));
+}
+
+const DBT *toku_dbt_positive_infinity(void) {
+  static DBT positive_infinity_dbt = {
+      .data = 0, .size = 0, .ulen = 0, .flags = 0};  // port
+  return &positive_infinity_dbt;
+}
+
+const DBT *toku_dbt_negative_infinity(void) {
+  static DBT negative_infinity_dbt = {
+      .data = 0, .size = 0, .ulen = 0, .flags = 0};  // port
+  return &negative_infinity_dbt;
+}
+
+bool toku_dbt_is_infinite(const DBT *dbt) {
+  return dbt == toku_dbt_positive_infinity() ||
+         dbt == toku_dbt_negative_infinity();
+}
+
+bool toku_dbt_is_empty(const DBT *dbt) {
+  // can't have a null data field with a non-zero size
+  paranoid_invariant(dbt->data != nullptr || dbt->size == 0);
+  return dbt->data == nullptr;
+}
+
+int toku_dbt_infinite_compare(const DBT *a, const DBT *b) {
+  if (a == b) {
+    return 0;
+  } else if (a == toku_dbt_positive_infinity()) {
+    return 1;
+  } else if (b == toku_dbt_positive_infinity()) {
+    return -1;
+  } else if (a == toku_dbt_negative_infinity()) {
+    return -1;
+  } else {
+    invariant(b == toku_dbt_negative_infinity());
+    return 1;
+  }
+}
+
+bool toku_dbt_equals(const DBT *a, const DBT *b) {
+  if (!toku_dbt_is_infinite(a) && !toku_dbt_is_infinite(b)) {
+    return a->data == b->data && a->size == b->size;
+  } else {
+    // a or b is infinite, so they're equal if they are the same infinite
+    return a == b ? true : false;
+  }
+}
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/dbt.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/dbt.h
new file mode 100644
index 000000000..d86c440f8
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/dbt.h
@@ -0,0 +1,98 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include "../db.h"
+
+// TODO: John
+// Document this API a little better so that DBT
+// memory management can be morm widely understood.
+
+DBT *toku_init_dbt(DBT *);
+
+// returns: an initialized but empty dbt (for which toku_dbt_is_empty() is true)
+DBT toku_empty_dbt(void);
+
+DBT *toku_init_dbt_flags(DBT *, uint32_t flags);
+
+void toku_destroy_dbt(DBT *);
+
+DBT *toku_fill_dbt(DBT *dbt, const void *k, size_t len);
+
+DBT *toku_memdup_dbt(DBT *dbt, const void *k, size_t len);
+
+DBT *toku_copyref_dbt(DBT *dst, const DBT src);
+
+DBT *toku_clone_dbt(DBT *dst, const DBT &src);
+
+void toku_sdbt_cleanup(struct simple_dbt *sdbt);
+
+// returns: special DBT pointer representing positive infinity
+const DBT *toku_dbt_positive_infinity(void);
+
+// returns: special DBT pointer representing negative infinity
+const DBT *toku_dbt_negative_infinity(void);
+
+// returns: true if the given dbt is either positive or negative infinity
+bool toku_dbt_is_infinite(const DBT *dbt);
+
+// returns: true if the given dbt has no data (ie: dbt->data == nullptr)
+bool toku_dbt_is_empty(const DBT *dbt);
+
+// effect: compares two potentially infinity-valued dbts
+// requires: at least one is infinite (assert otherwise)
+int toku_dbt_infinite_compare(const DBT *a, const DBT *b);
+
+// returns: true if the given dbts have the same data pointer and size
+bool toku_dbt_equals(const DBT *a, const DBT *b);
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/growable_array.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/growable_array.h
new file mode 100644
index 000000000..158750fdb
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/growable_array.h
@@ -0,0 +1,144 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include <memory.h>
+
+//******************************************************************************
+//
+// Overview: A growable array is a little bit like std::vector except that
+//  it doesn't have constructors (hence can be used in static constructs, since
+//  the google style guide says no constructors), and it's a little simpler.
+// Operations:
+//   init and deinit (we don't have constructors and destructors).
+//   fetch_unchecked to get values out.
+//   store_unchecked to put values in.
+//   push to add an element at the end
+//   get_size to find out the size
+//   get_memory_size to find out how much memory the data stucture is using.
+//
+//******************************************************************************
+
+namespace toku {
+
+template <typename T>
+class GrowableArray {
+ public:
+  void init(void)
+  // Effect: Initialize the array to contain no elements.
+  {
+    m_array = NULL;
+    m_size = 0;
+    m_size_limit = 0;
+  }
+
+  void deinit(void)
+  // Effect: Deinitialize the array (freeing any memory it uses, for example).
+  {
+    toku_free(m_array);
+    m_array = NULL;
+    m_size = 0;
+    m_size_limit = 0;
+  }
+
+  T fetch_unchecked(size_t i) const
+  // Effect: Fetch the ith element.  If i is out of range, the system asserts.
+  {
+    return m_array[i];
+  }
+
+  void store_unchecked(size_t i, T v)
+  // Effect: Store v in the ith element.  If i is out of range, the system
+  // asserts.
+  {
+    paranoid_invariant(i < m_size);
+    m_array[i] = v;
+  }
+
+  void push(T v)
+  // Effect: Add v to the end of the array (increasing the size).  The amortized
+  // cost of this operation is constant. Implementation hint:  Double the size
+  // of the array when it gets too big so that the amortized cost stays
+  // constant.
+  {
+    if (m_size >= m_size_limit) {
+      if (m_array == NULL) {
+        m_size_limit = 1;
+      } else {
+        m_size_limit *= 2;
+      }
+      XREALLOC_N(m_size_limit, m_array);
+    }
+    m_array[m_size++] = v;
+  }
+
+  size_t get_size(void) const
+  // Effect: Return the number of elements in the array.
+  {
+    return m_size;
+  }
+  size_t memory_size(void) const
+  // Effect: Return the size (in bytes) that the array occupies in memory.  This
+  // is really only an estimate.
+  {
+    return sizeof(*this) + sizeof(T) * m_size_limit;
+  }
+
+ private:
+  T *m_array;
+  size_t m_size;
+  size_t m_size_limit;  // How much space is allocated in array.
+};
+
+}  // namespace toku
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/memarena.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/memarena.cc
new file mode 100644
index 000000000..0e7a9880b
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/memarena.cc
@@ -0,0 +1,201 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include "memarena.h"
+
+#include <string.h>
+
+#include <algorithm>
+
+#include "../portability/memory.h"
+
+void memarena::create(size_t initial_size) {
+  _current_chunk = arena_chunk();
+  _other_chunks = nullptr;
+  _size_of_other_chunks = 0;
+  _footprint_of_other_chunks = 0;
+  _n_other_chunks = 0;
+
+  _current_chunk.size = initial_size;
+  if (_current_chunk.size > 0) {
+    XMALLOC_N(_current_chunk.size, _current_chunk.buf);
+  }
+}
+
+void memarena::destroy(void) {
+  if (_current_chunk.buf) {
+    toku_free(_current_chunk.buf);
+  }
+  for (int i = 0; i < _n_other_chunks; i++) {
+    toku_free(_other_chunks[i].buf);
+  }
+  if (_other_chunks) {
+    toku_free(_other_chunks);
+  }
+  _current_chunk = arena_chunk();
+  _other_chunks = nullptr;
+  _n_other_chunks = 0;
+}
+
+static size_t round_to_page(size_t size) {
+  const size_t page_size = 4096;
+  const size_t r = page_size + ((size - 1) & ~(page_size - 1));
+  assert((r & (page_size - 1)) == 0);  // make sure it's aligned
+  assert(r >= size);                   // make sure it's not too small
+  assert(r <
+         size + page_size);  // make sure we didn't grow by more than a page.
+  return r;
+}
+
+static const size_t MEMARENA_MAX_CHUNK_SIZE = 64 * 1024 * 1024;
+
+void *memarena::malloc_from_arena(size_t size) {
+  if (_current_chunk.buf == nullptr ||
+      _current_chunk.size < _current_chunk.used + size) {
+    // The existing block isn't big enough.
+    // Add the block to the vector of blocks.
+    if (_current_chunk.buf) {
+      invariant(_current_chunk.size > 0);
+      int old_n = _n_other_chunks;
+      XREALLOC_N(old_n + 1, _other_chunks);
+      _other_chunks[old_n] = _current_chunk;
+      _n_other_chunks = old_n + 1;
+      _size_of_other_chunks += _current_chunk.size;
+      _footprint_of_other_chunks +=
+          toku_memory_footprint(_current_chunk.buf, _current_chunk.used);
+    }
+
+    // Make a new one. Grow the buffer size exponentially until we hit
+    // the max chunk size, but make it at least `size' bytes so the
+    // current allocation always fit.
+    size_t new_size =
+        std::min(MEMARENA_MAX_CHUNK_SIZE, 2 * _current_chunk.size);
+    if (new_size < size) {
+      new_size = size;
+    }
+    new_size = round_to_page(
+        new_size);  // at least size, but round to the next page size
+    XMALLOC_N(new_size, _current_chunk.buf);
+    _current_chunk.used = 0;
+    _current_chunk.size = new_size;
+  }
+  invariant(_current_chunk.buf != nullptr);
+
+  // allocate in the existing block.
+  char *p = _current_chunk.buf + _current_chunk.used;
+  _current_chunk.used += size;
+  return p;
+}
+
+void memarena::move_memory(memarena *dest) {
+  // Move memory to dest
+  XREALLOC_N(dest->_n_other_chunks + _n_other_chunks + 1, dest->_other_chunks);
+  dest->_size_of_other_chunks += _size_of_other_chunks + _current_chunk.size;
+  dest->_footprint_of_other_chunks +=
+      _footprint_of_other_chunks +
+      toku_memory_footprint(_current_chunk.buf, _current_chunk.used);
+  for (int i = 0; i < _n_other_chunks; i++) {
+    dest->_other_chunks[dest->_n_other_chunks++] = _other_chunks[i];
+  }
+  dest->_other_chunks[dest->_n_other_chunks++] = _current_chunk;
+
+  // Clear out this memarena's memory
+  toku_free(_other_chunks);
+  _current_chunk = arena_chunk();
+  _other_chunks = nullptr;
+  _size_of_other_chunks = 0;
+  _footprint_of_other_chunks = 0;
+  _n_other_chunks = 0;
+}
+
+size_t memarena::total_memory_size(void) const {
+  return sizeof(*this) + total_size_in_use() +
+         _n_other_chunks * sizeof(*_other_chunks);
+}
+
+size_t memarena::total_size_in_use(void) const {
+  return _size_of_other_chunks + _current_chunk.used;
+}
+
+size_t memarena::total_footprint(void) const {
+  return sizeof(*this) + _footprint_of_other_chunks +
+         toku_memory_footprint(_current_chunk.buf, _current_chunk.used) +
+         _n_other_chunks * sizeof(*_other_chunks);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+const void *memarena::chunk_iterator::current(size_t *used) const {
+  if (_chunk_idx < 0) {
+    *used = _ma->_current_chunk.used;
+    return _ma->_current_chunk.buf;
+  } else if (_chunk_idx < _ma->_n_other_chunks) {
+    *used = _ma->_other_chunks[_chunk_idx].used;
+    return _ma->_other_chunks[_chunk_idx].buf;
+  }
+  *used = 0;
+  return nullptr;
+}
+
+void memarena::chunk_iterator::next() { _chunk_idx++; }
+
+bool memarena::chunk_iterator::more() const {
+  if (_chunk_idx < 0) {
+    return _ma->_current_chunk.buf != nullptr;
+  }
+  return _chunk_idx < _ma->_n_other_chunks;
+}
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/memarena.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/memarena.h
new file mode 100644
index 000000000..ddcc1144f
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/memarena.h
@@ -0,0 +1,141 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include <stdlib.h>
+
+/*
+ * A memarena is used to efficiently store a collection of objects that never
+ * move The pattern is allocate more and more stuff and free all of the items at
+ * once. The underlying memory will store 1 or more objects per chunk. Each
+ * chunk is contiguously laid out in memory but chunks are not necessarily
+ * contiguous with each other.
+ */
+class memarena {
+ public:
+  memarena()
+      : _current_chunk(arena_chunk()),
+        _other_chunks(nullptr),
+        _n_other_chunks(0),
+        _size_of_other_chunks(0),
+        _footprint_of_other_chunks(0) {}
+
+  // Effect: Create a memarena with the specified initial size
+  void create(size_t initial_size);
+
+  void destroy(void);
+
+  // Effect: Allocate some memory.  The returned value remains valid until the
+  // memarena is cleared or closed.
+  //  In case of ENOMEM, aborts.
+  void *malloc_from_arena(size_t size);
+
+  // Effect: Move all the memory from this memarena into DEST.
+  //         When SOURCE is closed the memory won't be freed.
+  //         When DEST is closed, the memory will be freed, unless DEST moves
+  //         its memory to another memarena...
+  void move_memory(memarena *dest);
+
+  // Effect: Calculate the amount of memory used by a memory arena.
+  size_t total_memory_size(void) const;
+
+  // Effect: Calculate the used space of the memory arena (ie: excludes unused
+  // space)
+  size_t total_size_in_use(void) const;
+
+  // Effect: Calculate the amount of memory used, according to
+  // toku_memory_footprint(),
+  //         which is a more expensive but more accurate count of memory used.
+  size_t total_footprint(void) const;
+
+  // iterator over the underlying chunks that store objects in the memarena.
+  // a chunk is represented by a pointer to const memory and a usable byte
+  // count.
+  class chunk_iterator {
+   public:
+    chunk_iterator(const memarena *ma) : _ma(ma), _chunk_idx(-1) {}
+
+    // returns: base pointer to the current chunk
+    //          *used set to the number of usable bytes
+    //          if more() is false, returns nullptr and *used = 0
+    const void *current(size_t *used) const;
+
+    // requires: more() is true
+    void next();
+
+    bool more() const;
+
+   private:
+    // -1 represents the 'initial' chunk in a memarena, ie: ma->_current_chunk
+    // >= 0 represents the i'th chunk in the ma->_other_chunks array
+    const memarena *_ma;
+    int _chunk_idx;
+  };
+
+ private:
+  struct arena_chunk {
+    arena_chunk() : buf(nullptr), used(0), size(0) {}
+    char *buf;
+    size_t used;
+    size_t size;
+  };
+
+  struct arena_chunk _current_chunk;
+  struct arena_chunk *_other_chunks;
+  int _n_other_chunks;
+  size_t _size_of_other_chunks;       // the buf_size of all the other chunks.
+  size_t _footprint_of_other_chunks;  // the footprint of all the other chunks.
+
+  friend class memarena_unit_test;
+};
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/omt.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/omt.h
new file mode 100644
index 000000000..f208002d3
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/omt.h
@@ -0,0 +1,794 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include <memory.h>
+#include <stdint.h>
+
+#include "../portability/toku_portability.h"
+#include "../portability/toku_race_tools.h"
+#include "growable_array.h"
+
+namespace toku {
+
+/**
+ * Order Maintenance Tree (OMT)
+ *
+ * Maintains a collection of totally ordered values, where each value has an
+ * integer weight. The OMT is a mutable datatype.
+ *
+ * The Abstraction:
+ *
+ * An OMT is a vector of values, $V$, where $|V|$ is the length of the vector.
+ * The vector is numbered from $0$ to $|V|-1$.
+ * Each value has a weight.  The weight of the $i$th element is denoted
+ * $w(V_i)$.
+ *
+ * We can create a new OMT, which is the empty vector.
+ *
+ * We can insert a new element $x$ into slot $i$, changing $V$ into $V'$ where
+ *  $|V'|=1+|V|$       and
+ *
+ *   V'_j = V_j       if $j<i$
+ *          x         if $j=i$
+ *          V_{j-1}   if $j>i$.
+ *
+ * We can specify $i$ using a kind of function instead of as an integer.
+ * Let $b$ be a function mapping from values to nonzero integers, such that
+ * the signum of $b$ is monotically increasing.
+ * We can specify $i$ as the minimum integer such that $b(V_i)>0$.
+ *
+ * We look up a value using its index, or using a Heaviside function.
+ * For lookups, we allow $b$ to be zero for some values, and again the signum of
+ * $b$ must be monotonically increasing. When lookup up values, we can look up
+ *  $V_i$ where $i$ is the minimum integer such that $b(V_i)=0$.   (With a
+ * special return code if no such value exists.) (Rationale:  Ordinarily we want
+ * $i$ to be unique.  But for various reasons we want to allow multiple zeros,
+ * and we want the smallest $i$ in that case.) $V_i$ where $i$ is the minimum
+ * integer such that $b(V_i)>0$.   (Or an indication that no such value exists.)
+ *  $V_i$ where $i$ is the maximum integer such that $b(V_i)<0$.   (Or an
+ * indication that no such value exists.)
+ *
+ * When looking up a value using a Heaviside function, we get the value and its
+ * index.
+ *
+ * We can also split an OMT into two OMTs, splitting the weight of the values
+ * evenly. Find a value $j$ such that the values to the left of $j$ have about
+ * the same total weight as the values to the right of $j$. The resulting two
+ * OMTs contain the values to the left of $j$ and the values to the right of $j$
+ * respectively. All of the values from the original OMT go into one of the new
+ * OMTs. If the weights of the values don't split exactly evenly, then the
+ * implementation has the freedom to choose whether the new left OMT or the new
+ * right OMT is larger.
+ *
+ * Performance:
+ *  Insertion and deletion should run with $O(\log |V|)$ time and $O(\log |V|)$
+ * calls to the Heaviside function. The memory required is O(|V|).
+ *
+ * Usage:
+ *  The omt is templated by two parameters:
+ *   - omtdata_t is what will be stored within the omt.  These could be pointers
+ * or real data types (ints, structs).
+ *   - omtdataout_t is what will be returned by find and related functions.  By
+ * default, it is the same as omtdata_t, but you can set it to (omtdata_t *). To
+ * create an omt which will store "TXNID"s, for example, it is a good idea to
+ * typedef the template: typedef omt<TXNID> txnid_omt_t; If you are storing
+ * structs, you may want to be able to get a pointer to the data actually stored
+ * in the omt (see find_zero).  To do this, use the second template parameter:
+ *   typedef omt<struct foo, struct foo *> foo_omt_t;
+ */
+
+namespace omt_internal {
+
+template <bool subtree_supports_marks>
+class subtree_templated {
+ private:
+  uint32_t m_index;
+
+ public:
+  static const uint32_t NODE_NULL = UINT32_MAX;
+  inline void set_to_null(void) { m_index = NODE_NULL; }
+
+  inline bool is_null(void) const { return NODE_NULL == this->get_index(); }
+
+  inline uint32_t get_index(void) const { return m_index; }
+
+  inline void set_index(uint32_t index) {
+    paranoid_invariant(index != NODE_NULL);
+    m_index = index;
+  }
+} __attribute__((__packed__, aligned(4)));
+
+template <>
+class subtree_templated<true> {
+ private:
+  uint32_t m_bitfield;
+  static const uint32_t MASK_INDEX = ~(((uint32_t)1) << 31);
+  static const uint32_t MASK_BIT = ((uint32_t)1) << 31;
+
+  inline void set_index_internal(uint32_t new_index) {
+    m_bitfield = (m_bitfield & MASK_BIT) | new_index;
+  }
+
+ public:
+  static const uint32_t NODE_NULL = INT32_MAX;
+  inline void set_to_null(void) { this->set_index_internal(NODE_NULL); }
+
+  inline bool is_null(void) const { return NODE_NULL == this->get_index(); }
+
+  inline uint32_t get_index(void) const {
+    TOKU_DRD_IGNORE_VAR(m_bitfield);
+    const uint32_t bits = m_bitfield;
+    TOKU_DRD_STOP_IGNORING_VAR(m_bitfield);
+    return bits & MASK_INDEX;
+  }
+
+  inline void set_index(uint32_t index) {
+    paranoid_invariant(index < NODE_NULL);
+    this->set_index_internal(index);
+  }
+
+  inline bool get_bit(void) const {
+    TOKU_DRD_IGNORE_VAR(m_bitfield);
+    const uint32_t bits = m_bitfield;
+    TOKU_DRD_STOP_IGNORING_VAR(m_bitfield);
+    return (bits & MASK_BIT) != 0;
+  }
+
+  inline void enable_bit(void) {
+    // These bits may be set by a thread with a write lock on some
+    // leaf, and the index can be read by another thread with a (read
+    // or write) lock on another thread.  Also, the has_marks_below
+    // bit can be set by two threads simultaneously.  Neither of these
+    // are real races, so if we are using DRD we should tell it to
+    // ignore these bits just while we set this bit.  If there were a
+    // race in setting the index, that would be a real race.
+    TOKU_DRD_IGNORE_VAR(m_bitfield);
+    m_bitfield |= MASK_BIT;
+    TOKU_DRD_STOP_IGNORING_VAR(m_bitfield);
+  }
+
+  inline void disable_bit(void) { m_bitfield &= MASK_INDEX; }
+} __attribute__((__packed__));
+
+template <typename omtdata_t, bool subtree_supports_marks>
+class omt_node_templated {
+ public:
+  omtdata_t value;
+  uint32_t weight;
+  subtree_templated<subtree_supports_marks> left;
+  subtree_templated<subtree_supports_marks> right;
+
+  // this needs to be in both implementations because we don't have
+  // a "static if" the caller can use
+  inline void clear_stolen_bits(void) {}
+};  // note: originally this class had __attribute__((__packed__, aligned(4)))
+
+template <typename omtdata_t>
+class omt_node_templated<omtdata_t, true> {
+ public:
+  omtdata_t value;
+  uint32_t weight;
+  subtree_templated<true> left;
+  subtree_templated<true> right;
+  inline bool get_marked(void) const { return left.get_bit(); }
+  inline void set_marked_bit(void) { return left.enable_bit(); }
+  inline void unset_marked_bit(void) { return left.disable_bit(); }
+
+  inline bool get_marks_below(void) const { return right.get_bit(); }
+  inline void set_marks_below_bit(void) {
+    // This function can be called by multiple threads.
+    // Checking first reduces cache invalidation.
+    if (!this->get_marks_below()) {
+      right.enable_bit();
+    }
+  }
+  inline void unset_marks_below_bit(void) { right.disable_bit(); }
+
+  inline void clear_stolen_bits(void) {
+    this->unset_marked_bit();
+    this->unset_marks_below_bit();
+  }
+};  // note: originally this class had __attribute__((__packed__, aligned(4)))
+
+}  // namespace omt_internal
+
+template <typename omtdata_t, typename omtdataout_t = omtdata_t,
+          bool supports_marks = false>
+class omt {
+ public:
+  /**
+   * Effect: Create an empty OMT.
+   * Performance: constant time.
+   */
+  void create(void);
+
+  /**
+   * Effect: Create an empty OMT with no internal allocated space.
+   * Performance: constant time.
+   * Rationale: In some cases we need a valid omt but don't want to malloc.
+   */
+  void create_no_array(void);
+
+  /**
+   * Effect: Create a OMT containing values.  The number of values is in
+   * numvalues. Stores the new OMT in *omtp. Requires: this has not been created
+   * yet Requires: values != NULL Requires: values is sorted Performance:
+   * time=O(numvalues) Rationale:    Normally to insert N values takes O(N lg N)
+   * amortized time. If the N values are known in advance, are sorted, and the
+   * structure is empty, we can batch insert them much faster.
+   */
+  __attribute__((nonnull)) void create_from_sorted_array(
+      const omtdata_t *const values, const uint32_t numvalues);
+
+  /**
+   * Effect: Create an OMT containing values.  The number of values is in
+   * numvalues. On success the OMT takes ownership of *values array, and sets
+   * values=NULL. Requires: this has not been created yet Requires: values !=
+   * NULL Requires: *values is sorted Requires: *values was allocated with
+   * toku_malloc Requires: Capacity of the *values array is <= new_capacity
+   * Requires: On success, *values may not be accessed again by the caller.
+   * Performance:  time=O(1)
+   * Rational:     create_from_sorted_array takes O(numvalues) time.
+   *               By taking ownership of the array, we save a malloc and
+   * memcpy, and possibly a free (if the caller is done with the array).
+   */
+  void create_steal_sorted_array(omtdata_t **const values,
+                                 const uint32_t numvalues,
+                                 const uint32_t new_capacity);
+
+  /**
+   * Effect: Create a new OMT, storing it in *newomt.
+   *  The values to the right of index (starting at index) are moved to *newomt.
+   * Requires: newomt != NULL
+   * Returns
+   *    0             success,
+   *    EINVAL        if index > toku_omt_size(omt)
+   * On nonzero return, omt and *newomt are unmodified.
+   * Performance: time=O(n)
+   * Rationale:  We don't need a split-evenly operation.  We need to split items
+   * so that their total sizes are even, and other similar splitting criteria.
+   * It's easy to split evenly by calling size(), and dividing by two.
+   */
+  __attribute__((nonnull)) int split_at(omt *const newomt, const uint32_t idx);
+
+  /**
+   * Effect: Appends leftomt and rightomt to produce a new omt.
+   *  Creates this as the new omt.
+   *  leftomt and rightomt are destroyed.
+   * Performance: time=O(n) is acceptable, but one can imagine implementations
+   * that are O(\log n) worst-case.
+   */
+  __attribute__((nonnull)) void merge(omt *const leftomt, omt *const rightomt);
+
+  /**
+   * Effect: Creates a copy of an omt.
+   *  Creates this as the clone.
+   *  Each element is copied directly.  If they are pointers, the underlying
+   * data is not duplicated. Performance: O(n) or the running time of
+   * fill_array_with_subtree_values()
+   */
+  void clone(const omt &src);
+
+  /**
+   * Effect: Set the tree to be empty.
+   *  Note: Will not reallocate or resize any memory.
+   * Performance: time=O(1)
+   */
+  void clear(void);
+
+  /**
+   * Effect:  Destroy an OMT, freeing all its memory.
+   *   If the values being stored are pointers, their underlying data is not
+   * freed.  See free_items() Those values may be freed before or after calling
+   * toku_omt_destroy. Rationale: Returns no values since free() cannot fail.
+   * Rationale: Does not free the underlying pointers to reduce complexity.
+   * Performance:  time=O(1)
+   */
+  void destroy(void);
+
+  /**
+   * Effect: return |this|.
+   * Performance:  time=O(1)
+   */
+  uint32_t size(void) const;
+
+  /**
+   * Effect:  Insert value into the OMT.
+   *   If there is some i such that $h(V_i, v)=0$ then returns DB_KEYEXIST.
+   *   Otherwise, let i be the minimum value such that $h(V_i, v)>0$.
+   *      If no such i exists, then let i be |V|
+   *   Then this has the same effect as
+   *    insert_at(tree, value, i);
+   *   If idx!=NULL then i is stored in *idx
+   * Requires:  The signum of h must be monotonically increasing.
+   * Returns:
+   *    0            success
+   *    DB_KEYEXIST  the key is present (h was equal to zero for some value)
+   * On nonzero return, omt is unchanged.
+   * Performance: time=O(\log N) amortized.
+   * Rationale: Some future implementation may be O(\log N) worst-case time, but
+   * O(\log N) amortized is good enough for now.
+   */
+  template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+  int insert(const omtdata_t &value, const omtcmp_t &v, uint32_t *const idx);
+
+  /**
+   * Effect: Increases indexes of all items at slot >= idx by 1.
+   *         Insert value into the position at idx.
+   * Returns:
+   *   0         success
+   *   EINVAL    if idx > this->size()
+   * On error, omt is unchanged.
+   * Performance: time=O(\log N) amortized time.
+   * Rationale: Some future implementation may be O(\log N) worst-case time, but
+   * O(\log N) amortized is good enough for now.
+   */
+  int insert_at(const omtdata_t &value, const uint32_t idx);
+
+  /**
+   * Effect:  Replaces the item at idx with value.
+   * Returns:
+   *   0       success
+   *   EINVAL  if idx>=this->size()
+   * On error, omt is unchanged.
+   * Performance: time=O(\log N)
+   * Rationale: The FT needs to be able to replace a value with another copy of
+   * the same value (allocated in a different location)
+   *
+   */
+  int set_at(const omtdata_t &value, const uint32_t idx);
+
+  /**
+   * Effect: Delete the item in slot idx.
+   *         Decreases indexes of all items at slot > idx by 1.
+   * Returns
+   *     0            success
+   *     EINVAL       if idx>=this->size()
+   * On error, omt is unchanged.
+   * Rationale: To delete an item, first find its index using find or find_zero,
+   * then delete it. Performance: time=O(\log N) amortized.
+   */
+  int delete_at(const uint32_t idx);
+
+  /**
+   * Effect:  Iterate over the values of the omt, from left to right, calling f
+   * on each value. The first argument passed to f is a ref-to-const of the
+   * value stored in the omt. The second argument passed to f is the index of
+   * the value. The third argument passed to f is iterate_extra. The indices run
+   * from 0 (inclusive) to this->size() (exclusive). Requires: f != NULL
+   * Returns:
+   *  If f ever returns nonzero, then the iteration stops, and the value
+   * returned by f is returned by iterate. If f always returns zero, then
+   * iterate returns 0. Requires:  Don't modify the omt while running.  (E.g., f
+   * may not insert or delete values from the omt.) Performance: time=O(i+\log
+   * N) where i is the number of times f is called, and N is the number of
+   * elements in the omt. Rationale: Although the functional iterator requires
+   * defining another function (as opposed to C++ style iterator), it is much
+   * easier to read. Rationale: We may at some point use functors, but for now
+   * this is a smaller change from the old OMT.
+   */
+  template <typename iterate_extra_t,
+            int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+  int iterate(iterate_extra_t *const iterate_extra) const;
+
+  /**
+   * Effect:  Iterate over the values of the omt, from left to right, calling f
+   * on each value. The first argument passed to f is a ref-to-const of the
+   * value stored in the omt. The second argument passed to f is the index of
+   * the value. The third argument passed to f is iterate_extra. The indices run
+   * from 0 (inclusive) to this->size() (exclusive). We will iterate only over
+   * [left,right)
+   *
+   * Requires: left <= right
+   * Requires: f != NULL
+   * Returns:
+   *  EINVAL  if right > this->size()
+   *  If f ever returns nonzero, then the iteration stops, and the value
+   * returned by f is returned by iterate_on_range. If f always returns zero,
+   * then iterate_on_range returns 0. Requires:  Don't modify the omt while
+   * running.  (E.g., f may not insert or delete values from the omt.)
+   * Performance: time=O(i+\log N) where i is the number of times f is called,
+   * and N is the number of elements in the omt. Rational: Although the
+   * functional iterator requires defining another function (as opposed to C++
+   * style iterator), it is much easier to read.
+   */
+  template <typename iterate_extra_t,
+            int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+  int iterate_on_range(const uint32_t left, const uint32_t right,
+                       iterate_extra_t *const iterate_extra) const;
+
+  /**
+   * Effect: Iterate over the values of the omt, and mark the nodes that are
+   * visited. Other than the marks, this behaves the same as iterate_on_range.
+   * Requires: supports_marks == true
+   * Performance: time=O(i+\log N) where i is the number of times f is called,
+   * and N is the number of elements in the omt. Notes: This function MAY be
+   * called concurrently by multiple threads, but not concurrently with any
+   * other non-const function.
+   */
+  template <typename iterate_extra_t,
+            int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+  int iterate_and_mark_range(const uint32_t left, const uint32_t right,
+                             iterate_extra_t *const iterate_extra);
+
+  /**
+   * Effect: Iterate over the values of the omt, from left to right, calling f
+   * on each value whose node has been marked. Other than the marks, this
+   * behaves the same as iterate. Requires: supports_marks == true Performance:
+   * time=O(i+\log N) where i is the number of times f is called, and N is the
+   * number of elements in the omt.
+   */
+  template <typename iterate_extra_t,
+            int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+  int iterate_over_marked(iterate_extra_t *const iterate_extra) const;
+
+  /**
+   * Effect: Delete all elements from the omt, whose nodes have been marked.
+   * Requires: supports_marks == true
+   * Performance: time=O(N + i\log N) where i is the number of marked elements,
+   * {c,sh}ould be faster
+   */
+  void delete_all_marked(void);
+
+  /**
+   * Effect: Verify that the internal state of the marks in the tree are
+   * self-consistent. Crashes the system if the marks are in a bad state.
+   * Requires: supports_marks == true
+   * Performance: time=O(N)
+   * Notes:
+   *  Even though this is a const function, it requires exclusive access.
+   * Rationale:
+   *  The current implementation of the marks relies on a sort of
+   *  "cache" bit representing the state of bits below it in the tree.
+   *  This allows glass-box testing that these bits are correct.
+   */
+  void verify_marks_consistent(void) const;
+
+  /**
+   * Effect: None
+   * Returns whether there are any marks in the tree.
+   */
+  bool has_marks(void) const;
+
+  /**
+   * Effect:  Iterate over the values of the omt, from left to right, calling f
+   * on each value. The first argument passed to f is a pointer to the value
+   * stored in the omt. The second argument passed to f is the index of the
+   * value. The third argument passed to f is iterate_extra. The indices run
+   * from 0 (inclusive) to this->size() (exclusive). Requires: same as for
+   * iterate() Returns: same as for iterate() Performance: same as for iterate()
+   * Rationale: In general, most iterators should use iterate() since they
+   * should not modify the data stored in the omt.  This function is for
+   * iterators which need to modify values (for example, free_items). Rationale:
+   * We assume if you are transforming the data in place, you want to do it to
+   * everything at once, so there is not yet an iterate_on_range_ptr (but there
+   * could be).
+   */
+  template <typename iterate_extra_t,
+            int (*f)(omtdata_t *, const uint32_t, iterate_extra_t *const)>
+  void iterate_ptr(iterate_extra_t *const iterate_extra);
+
+  /**
+   * Effect: Set *value=V_idx
+   * Returns
+   *    0             success
+   *    EINVAL        if index>=toku_omt_size(omt)
+   * On nonzero return, *value is unchanged
+   * Performance: time=O(\log N)
+   */
+  int fetch(const uint32_t idx, omtdataout_t *const value) const;
+
+  /**
+   * Effect:  Find the smallest i such that h(V_i, extra)>=0
+   *  If there is such an i and h(V_i,extra)==0 then set *idxp=i, set *value =
+   * V_i, and return 0. If there is such an i and h(V_i,extra)>0  then set
+   * *idxp=i and return DB_NOTFOUND. If there is no such i then set
+   * *idx=this->size() and return DB_NOTFOUND. Note: value is of type
+   * omtdataout_t, which may be of type (omtdata_t) or (omtdata_t *) but is
+   * fixed by the instantiation. If it is the value type, then the value is
+   * copied out (even if the value type is a pointer to something else) If it is
+   * the pointer type, then *value is set to a pointer to the data within the
+   * omt. This is determined by the type of the omt as initially declared. If
+   * the omt is declared as omt<foo_t>, then foo_t's will be stored and foo_t's
+   * will be returned by find and related functions. If the omt is declared as
+   * omt<foo_t, foo_t *>, then foo_t's will be stored, and pointers to the
+   * stored items will be returned by find and related functions. Rationale:
+   *  Structs too small for malloc should be stored directly in the omt.
+   *  These structs may need to be edited as they exist inside the omt, so we
+   * need a way to get a pointer within the omt. Using separate functions for
+   * returning pointers and values increases code duplication and reduces
+   * type-checking. That also reduces the ability of the creator of a data
+   * structure to give advice to its future users. Slight overloading in this
+   * case seemed to provide a better API and better type checking.
+   */
+  template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+  int find_zero(const omtcmp_t &extra, omtdataout_t *const value,
+                uint32_t *const idxp) const;
+
+  /**
+   *   Effect:
+   *    If direction >0 then find the smallest i such that h(V_i,extra)>0.
+   *    If direction <0 then find the largest  i such that h(V_i,extra)<0.
+   *    (Direction may not be equal to zero.)
+   *    If value!=NULL then store V_i in *value
+   *    If idxp!=NULL then store i in *idxp.
+   *   Requires: The signum of h is monotically increasing.
+   *   Returns
+   *      0             success
+   *      DB_NOTFOUND   no such value is found.
+   *   On nonzero return, *value and *idxp are unchanged
+   *   Performance: time=O(\log N)
+   *   Rationale:
+   *     Here's how to use the find function to find various things
+   *       Cases for find:
+   *        find first value:         ( h(v)=+1, direction=+1 )
+   *        find last value           ( h(v)=-1, direction=-1 )
+   *        find first X              ( h(v)=(v< x) ? -1 : 1    direction=+1 )
+   *        find last X               ( h(v)=(v<=x) ? -1 : 1    direction=-1 )
+   *        find X or successor to X  ( same as find first X. )
+   *
+   *   Rationale: To help understand heaviside functions and behavor of find:
+   *    There are 7 kinds of heaviside functions.
+   *    The signus of the h must be monotonically increasing.
+   *    Given a function of the following form, A is the element
+   *    returned for direction>0, B is the element returned
+   *    for direction<0, C is the element returned for
+   *    direction==0 (see find_zero) (with a return of 0), and D is the element
+   *    returned for direction==0 (see find_zero) with a return of DB_NOTFOUND.
+   *    If any of A, B, or C are not found, then asking for the
+   *    associated direction will return DB_NOTFOUND.
+   *    See find_zero for more information.
+   *
+   *    Let the following represent the signus of the heaviside function.
+   *
+   *    -...-
+   *        A
+   *         D
+   *
+   *    +...+
+   *    B
+   *    D
+   *
+   *    0...0
+   *    C
+   *
+   *    -...-0...0
+   *        AC
+   *
+   *    0...0+...+
+   *    C    B
+   *
+   *    -...-+...+
+   *        AB
+   *         D
+   *
+   *    -...-0...0+...+
+   *        AC    B
+   */
+  template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+  int find(const omtcmp_t &extra, int direction, omtdataout_t *const value,
+           uint32_t *const idxp) const;
+
+  /**
+   * Effect: Return the size (in bytes) of the omt, as it resides in main
+   * memory.  If the data stored are pointers, don't include the size of what
+   * they all point to.
+   */
+  size_t memory_size(void);
+
+ private:
+  typedef uint32_t node_idx;
+  typedef omt_internal::subtree_templated<supports_marks> subtree;
+  typedef omt_internal::omt_node_templated<omtdata_t, supports_marks> omt_node;
+  ENSURE_POD(subtree);
+
+  struct omt_array {
+    uint32_t start_idx;
+    uint32_t num_values;
+    omtdata_t *values;
+  };
+
+  struct omt_tree {
+    subtree root;
+    uint32_t free_idx;
+    omt_node *nodes;
+  };
+
+  bool is_array;
+  uint32_t capacity;
+  union {
+    struct omt_array a;
+    struct omt_tree t;
+  } d;
+
+  __attribute__((nonnull)) void unmark(const subtree &subtree,
+                                       const uint32_t index,
+                                       GrowableArray<node_idx> *const indexes);
+
+  void create_internal_no_array(const uint32_t new_capacity);
+
+  void create_internal(const uint32_t new_capacity);
+
+  uint32_t nweight(const subtree &subtree) const;
+
+  node_idx node_malloc(void);
+
+  void node_free(const node_idx idx);
+
+  void maybe_resize_array(const uint32_t n);
+
+  __attribute__((nonnull)) void fill_array_with_subtree_values(
+      omtdata_t *const array, const subtree &subtree) const;
+
+  void convert_to_array(void);
+
+  __attribute__((nonnull)) void rebuild_from_sorted_array(
+      subtree *const subtree, const omtdata_t *const values,
+      const uint32_t numvalues);
+
+  void convert_to_tree(void);
+
+  void maybe_resize_or_convert(const uint32_t n);
+
+  bool will_need_rebalance(const subtree &subtree, const int leftmod,
+                           const int rightmod) const;
+
+  __attribute__((nonnull)) void insert_internal(
+      subtree *const subtreep, const omtdata_t &value, const uint32_t idx,
+      subtree **const rebalance_subtree);
+
+  void set_at_internal_array(const omtdata_t &value, const uint32_t idx);
+
+  void set_at_internal(const subtree &subtree, const omtdata_t &value,
+                       const uint32_t idx);
+
+  void delete_internal(subtree *const subtreep, const uint32_t idx,
+                       omt_node *const copyn,
+                       subtree **const rebalance_subtree);
+
+  template <typename iterate_extra_t,
+            int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+  int iterate_internal_array(const uint32_t left, const uint32_t right,
+                             iterate_extra_t *const iterate_extra) const;
+
+  template <typename iterate_extra_t,
+            int (*f)(omtdata_t *, const uint32_t, iterate_extra_t *const)>
+  void iterate_ptr_internal(const uint32_t left, const uint32_t right,
+                            const subtree &subtree, const uint32_t idx,
+                            iterate_extra_t *const iterate_extra);
+
+  template <typename iterate_extra_t,
+            int (*f)(omtdata_t *, const uint32_t, iterate_extra_t *const)>
+  void iterate_ptr_internal_array(const uint32_t left, const uint32_t right,
+                                  iterate_extra_t *const iterate_extra);
+
+  template <typename iterate_extra_t,
+            int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+  int iterate_internal(const uint32_t left, const uint32_t right,
+                       const subtree &subtree, const uint32_t idx,
+                       iterate_extra_t *const iterate_extra) const;
+
+  template <typename iterate_extra_t,
+            int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+  int iterate_and_mark_range_internal(const uint32_t left, const uint32_t right,
+                                      const subtree &subtree,
+                                      const uint32_t idx,
+                                      iterate_extra_t *const iterate_extra);
+
+  template <typename iterate_extra_t,
+            int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+  int iterate_over_marked_internal(const subtree &subtree, const uint32_t idx,
+                                   iterate_extra_t *const iterate_extra) const;
+
+  uint32_t verify_marks_consistent_internal(const subtree &subtree,
+                                            const bool allow_marks) const;
+
+  void fetch_internal_array(const uint32_t i, omtdataout_t *const value) const;
+
+  void fetch_internal(const subtree &subtree, const uint32_t i,
+                      omtdataout_t *const value) const;
+
+  __attribute__((nonnull)) void fill_array_with_subtree_idxs(
+      node_idx *const array, const subtree &subtree) const;
+
+  __attribute__((nonnull)) void rebuild_subtree_from_idxs(
+      subtree *const subtree, const node_idx *const idxs,
+      const uint32_t numvalues);
+
+  __attribute__((nonnull)) void rebalance(subtree *const subtree);
+
+  __attribute__((nonnull)) static void copyout(omtdata_t *const out,
+                                               const omt_node *const n);
+
+  __attribute__((nonnull)) static void copyout(omtdata_t **const out,
+                                               omt_node *const n);
+
+  __attribute__((nonnull)) static void copyout(
+      omtdata_t *const out, const omtdata_t *const stored_value_ptr);
+
+  __attribute__((nonnull)) static void copyout(
+      omtdata_t **const out, omtdata_t *const stored_value_ptr);
+
+  template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+  int find_internal_zero_array(const omtcmp_t &extra, omtdataout_t *const value,
+                               uint32_t *const idxp) const;
+
+  template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+  int find_internal_zero(const subtree &subtree, const omtcmp_t &extra,
+                         omtdataout_t *const value, uint32_t *const idxp) const;
+
+  template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+  int find_internal_plus_array(const omtcmp_t &extra, omtdataout_t *const value,
+                               uint32_t *const idxp) const;
+
+  template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+  int find_internal_plus(const subtree &subtree, const omtcmp_t &extra,
+                         omtdataout_t *const value, uint32_t *const idxp) const;
+
+  template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+  int find_internal_minus_array(const omtcmp_t &extra,
+                                omtdataout_t *const value,
+                                uint32_t *const idxp) const;
+
+  template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+  int find_internal_minus(const subtree &subtree, const omtcmp_t &extra,
+                          omtdataout_t *const value,
+                          uint32_t *const idxp) const;
+};
+
+}  // namespace toku
+
+// include the implementation here
+#include "omt_impl.h"
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/omt_impl.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/omt_impl.h
new file mode 100644
index 000000000..e77986716
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/omt_impl.h
@@ -0,0 +1,1295 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#include <string.h>
+
+#include "../db.h"
+#include "../portability/memory.h"
+
+namespace toku {
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::create(void) {
+  this->create_internal(2);
+  if (supports_marks) {
+    this->convert_to_tree();
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::create_no_array(void) {
+  if (!supports_marks) {
+    this->create_internal_no_array(0);
+  } else {
+    this->is_array = false;
+    this->capacity = 0;
+    this->d.t.nodes = nullptr;
+    this->d.t.root.set_to_null();
+    this->d.t.free_idx = 0;
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::create_from_sorted_array(
+    const omtdata_t *const values, const uint32_t numvalues) {
+  this->create_internal(numvalues);
+  memcpy(this->d.a.values, values, numvalues * (sizeof values[0]));
+  this->d.a.num_values = numvalues;
+  if (supports_marks) {
+    this->convert_to_tree();
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::create_steal_sorted_array(
+    omtdata_t **const values, const uint32_t numvalues,
+    const uint32_t new_capacity) {
+  paranoid_invariant_notnull(values);
+  this->create_internal_no_array(new_capacity);
+  this->d.a.num_values = numvalues;
+  this->d.a.values = *values;
+  *values = nullptr;
+  if (supports_marks) {
+    this->convert_to_tree();
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+int omt<omtdata_t, omtdataout_t, supports_marks>::split_at(omt *const newomt,
+                                                           const uint32_t idx) {
+  barf_if_marked(*this);
+  paranoid_invariant_notnull(newomt);
+  if (idx > this->size()) {
+    return EINVAL;
+  }
+  this->convert_to_array();
+  const uint32_t newsize = this->size() - idx;
+  newomt->create_from_sorted_array(&this->d.a.values[this->d.a.start_idx + idx],
+                                   newsize);
+  this->d.a.num_values = idx;
+  this->maybe_resize_array(idx);
+  if (supports_marks) {
+    this->convert_to_tree();
+  }
+  return 0;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::merge(omt *const leftomt,
+                                                         omt *const rightomt) {
+  barf_if_marked(*this);
+  paranoid_invariant_notnull(leftomt);
+  paranoid_invariant_notnull(rightomt);
+  const uint32_t leftsize = leftomt->size();
+  const uint32_t rightsize = rightomt->size();
+  const uint32_t newsize = leftsize + rightsize;
+
+  if (leftomt->is_array) {
+    if (leftomt->capacity -
+            (leftomt->d.a.start_idx + leftomt->d.a.num_values) >=
+        rightsize) {
+      this->create_steal_sorted_array(
+          &leftomt->d.a.values, leftomt->d.a.num_values, leftomt->capacity);
+      this->d.a.start_idx = leftomt->d.a.start_idx;
+    } else {
+      this->create_internal(newsize);
+      memcpy(&this->d.a.values[0], &leftomt->d.a.values[leftomt->d.a.start_idx],
+             leftomt->d.a.num_values * (sizeof this->d.a.values[0]));
+    }
+  } else {
+    this->create_internal(newsize);
+    leftomt->fill_array_with_subtree_values(&this->d.a.values[0],
+                                            leftomt->d.t.root);
+  }
+  leftomt->destroy();
+  this->d.a.num_values = leftsize;
+
+  if (rightomt->is_array) {
+    memcpy(&this->d.a.values[this->d.a.start_idx + this->d.a.num_values],
+           &rightomt->d.a.values[rightomt->d.a.start_idx],
+           rightomt->d.a.num_values * (sizeof this->d.a.values[0]));
+  } else {
+    rightomt->fill_array_with_subtree_values(
+        &this->d.a.values[this->d.a.start_idx + this->d.a.num_values],
+        rightomt->d.t.root);
+  }
+  rightomt->destroy();
+  this->d.a.num_values += rightsize;
+  paranoid_invariant(this->size() == newsize);
+  if (supports_marks) {
+    this->convert_to_tree();
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::clone(const omt &src) {
+  barf_if_marked(*this);
+  this->create_internal(src.size());
+  if (src.is_array) {
+    memcpy(&this->d.a.values[0], &src.d.a.values[src.d.a.start_idx],
+           src.d.a.num_values * (sizeof this->d.a.values[0]));
+  } else {
+    src.fill_array_with_subtree_values(&this->d.a.values[0], src.d.t.root);
+  }
+  this->d.a.num_values = src.size();
+  if (supports_marks) {
+    this->convert_to_tree();
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::clear(void) {
+  if (this->is_array) {
+    this->d.a.start_idx = 0;
+    this->d.a.num_values = 0;
+  } else {
+    this->d.t.root.set_to_null();
+    this->d.t.free_idx = 0;
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::destroy(void) {
+  this->clear();
+  this->capacity = 0;
+  if (this->is_array) {
+    if (this->d.a.values != nullptr) {
+      toku_free(this->d.a.values);
+    }
+    this->d.a.values = nullptr;
+  } else {
+    if (this->d.t.nodes != nullptr) {
+      toku_free(this->d.t.nodes);
+    }
+    this->d.t.nodes = nullptr;
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+uint32_t omt<omtdata_t, omtdataout_t, supports_marks>::size(void) const {
+  if (this->is_array) {
+    return this->d.a.num_values;
+  } else {
+    return this->nweight(this->d.t.root);
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::insert(const omtdata_t &value,
+                                                         const omtcmp_t &v,
+                                                         uint32_t *const idx) {
+  int r;
+  uint32_t insert_idx;
+
+  r = this->find_zero<omtcmp_t, h>(v, nullptr, &insert_idx);
+  if (r == 0) {
+    if (idx) *idx = insert_idx;
+    return DB_KEYEXIST;
+  }
+  if (r != DB_NOTFOUND) return r;
+
+  if ((r = this->insert_at(value, insert_idx))) return r;
+  if (idx) *idx = insert_idx;
+
+  return 0;
+}
+
+// The following 3 functions implement a static if for us.
+template <typename omtdata_t, typename omtdataout_t>
+static void barf_if_marked(const omt<omtdata_t, omtdataout_t, false> &UU(omt)) {
+}
+
+template <typename omtdata_t, typename omtdataout_t>
+static void barf_if_marked(const omt<omtdata_t, omtdataout_t, true> &omt) {
+  invariant(!omt.has_marks());
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+bool omt<omtdata_t, omtdataout_t, supports_marks>::has_marks(void) const {
+  static_assert(supports_marks, "Does not support marks");
+  if (this->d.t.root.is_null()) {
+    return false;
+  }
+  const omt_node &node = this->d.t.nodes[this->d.t.root.get_index()];
+  return node.get_marks_below() || node.get_marked();
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+int omt<omtdata_t, omtdataout_t, supports_marks>::insert_at(
+    const omtdata_t &value, const uint32_t idx) {
+  barf_if_marked(*this);
+  if (idx > this->size()) {
+    return EINVAL;
+  }
+
+  this->maybe_resize_or_convert(this->size() + 1);
+  if (this->is_array && idx != this->d.a.num_values &&
+      (idx != 0 || this->d.a.start_idx == 0)) {
+    this->convert_to_tree();
+  }
+  if (this->is_array) {
+    if (idx == this->d.a.num_values) {
+      this->d.a.values[this->d.a.start_idx + this->d.a.num_values] = value;
+    } else {
+      this->d.a.values[--this->d.a.start_idx] = value;
+    }
+    this->d.a.num_values++;
+  } else {
+    subtree *rebalance_subtree = nullptr;
+    this->insert_internal(&this->d.t.root, value, idx, &rebalance_subtree);
+    if (rebalance_subtree != nullptr) {
+      this->rebalance(rebalance_subtree);
+    }
+  }
+  return 0;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+int omt<omtdata_t, omtdataout_t, supports_marks>::set_at(const omtdata_t &value,
+                                                         const uint32_t idx) {
+  barf_if_marked(*this);
+  if (idx >= this->size()) {
+    return EINVAL;
+  }
+
+  if (this->is_array) {
+    this->set_at_internal_array(value, idx);
+  } else {
+    this->set_at_internal(this->d.t.root, value, idx);
+  }
+  return 0;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+int omt<omtdata_t, omtdataout_t, supports_marks>::delete_at(
+    const uint32_t idx) {
+  barf_if_marked(*this);
+  if (idx >= this->size()) {
+    return EINVAL;
+  }
+
+  this->maybe_resize_or_convert(this->size() - 1);
+  if (this->is_array && idx != 0 && idx != this->d.a.num_values - 1) {
+    this->convert_to_tree();
+  }
+  if (this->is_array) {
+    // Testing for 0 does not rule out it being the last entry.
+    // Test explicitly for num_values-1
+    if (idx != this->d.a.num_values - 1) {
+      this->d.a.start_idx++;
+    }
+    this->d.a.num_values--;
+  } else {
+    subtree *rebalance_subtree = nullptr;
+    this->delete_internal(&this->d.t.root, idx, nullptr, &rebalance_subtree);
+    if (rebalance_subtree != nullptr) {
+      this->rebalance(rebalance_subtree);
+    }
+  }
+  return 0;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename iterate_extra_t,
+          int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::iterate(
+    iterate_extra_t *const iterate_extra) const {
+  return this->iterate_on_range<iterate_extra_t, f>(0, this->size(),
+                                                    iterate_extra);
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename iterate_extra_t,
+          int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::iterate_on_range(
+    const uint32_t left, const uint32_t right,
+    iterate_extra_t *const iterate_extra) const {
+  if (right > this->size()) {
+    return EINVAL;
+  }
+  if (left == right) {
+    return 0;
+  }
+  if (this->is_array) {
+    return this->iterate_internal_array<iterate_extra_t, f>(left, right,
+                                                            iterate_extra);
+  }
+  return this->iterate_internal<iterate_extra_t, f>(left, right, this->d.t.root,
+                                                    0, iterate_extra);
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename iterate_extra_t,
+          int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::iterate_and_mark_range(
+    const uint32_t left, const uint32_t right,
+    iterate_extra_t *const iterate_extra) {
+  static_assert(supports_marks, "does not support marks");
+  if (right > this->size()) {
+    return EINVAL;
+  }
+  if (left == right) {
+    return 0;
+  }
+  paranoid_invariant(!this->is_array);
+  return this->iterate_and_mark_range_internal<iterate_extra_t, f>(
+      left, right, this->d.t.root, 0, iterate_extra);
+}
+
+// TODO: We can optimize this if we steal 3 bits.  1 bit: this node is
+// marked.  1 bit: left subtree has marks. 1 bit: right subtree has marks.
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename iterate_extra_t,
+          int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::iterate_over_marked(
+    iterate_extra_t *const iterate_extra) const {
+  static_assert(supports_marks, "does not support marks");
+  paranoid_invariant(!this->is_array);
+  return this->iterate_over_marked_internal<iterate_extra_t, f>(
+      this->d.t.root, 0, iterate_extra);
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::unmark(
+    const subtree &st, const uint32_t index,
+    GrowableArray<node_idx> *const indexes) {
+  if (st.is_null()) {
+    return;
+  }
+  omt_node &n = this->d.t.nodes[st.get_index()];
+  const uint32_t index_root = index + this->nweight(n.left);
+
+  const bool below = n.get_marks_below();
+  if (below) {
+    this->unmark(n.left, index, indexes);
+  }
+  if (n.get_marked()) {
+    indexes->push(index_root);
+  }
+  n.clear_stolen_bits();
+  if (below) {
+    this->unmark(n.right, index_root + 1, indexes);
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::delete_all_marked(void) {
+  static_assert(supports_marks, "does not support marks");
+  if (!this->has_marks()) {
+    return;
+  }
+  paranoid_invariant(!this->is_array);
+  GrowableArray<node_idx> marked_indexes;
+  marked_indexes.init();
+
+  // Remove all marks.
+  // We need to delete all the stolen bits before calling delete_at to
+  // prevent barfing.
+  this->unmark(this->d.t.root, 0, &marked_indexes);
+
+  for (uint32_t i = 0; i < marked_indexes.get_size(); i++) {
+    // Delete from left to right, shift by number already deleted.
+    // Alternative is delete from right to left.
+    int r = this->delete_at(marked_indexes.fetch_unchecked(i) - i);
+    lazy_assert_zero(r);
+  }
+  marked_indexes.deinit();
+  barf_if_marked(*this);
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+uint32_t
+omt<omtdata_t, omtdataout_t, supports_marks>::verify_marks_consistent_internal(
+    const subtree &st, const bool UU(allow_marks)) const {
+  if (st.is_null()) {
+    return 0;
+  }
+  const omt_node &node = this->d.t.nodes[st.get_index()];
+  uint32_t num_marks =
+      verify_marks_consistent_internal(node.left, node.get_marks_below());
+  num_marks +=
+      verify_marks_consistent_internal(node.right, node.get_marks_below());
+  if (node.get_marks_below()) {
+    paranoid_invariant(allow_marks);
+    paranoid_invariant(num_marks > 0);
+  } else {
+    // redundant with invariant below, but nice to have explicitly
+    paranoid_invariant(num_marks == 0);
+  }
+  if (node.get_marked()) {
+    paranoid_invariant(allow_marks);
+    ++num_marks;
+  }
+  return num_marks;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::verify_marks_consistent(
+    void) const {
+  static_assert(supports_marks, "does not support marks");
+  paranoid_invariant(!this->is_array);
+  this->verify_marks_consistent_internal(this->d.t.root, true);
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename iterate_extra_t,
+          int (*f)(omtdata_t *, const uint32_t, iterate_extra_t *const)>
+void omt<omtdata_t, omtdataout_t, supports_marks>::iterate_ptr(
+    iterate_extra_t *const iterate_extra) {
+  if (this->is_array) {
+    this->iterate_ptr_internal_array<iterate_extra_t, f>(0, this->size(),
+                                                         iterate_extra);
+  } else {
+    this->iterate_ptr_internal<iterate_extra_t, f>(
+        0, this->size(), this->d.t.root, 0, iterate_extra);
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+int omt<omtdata_t, omtdataout_t, supports_marks>::fetch(
+    const uint32_t idx, omtdataout_t *const value) const {
+  if (idx >= this->size()) {
+    return EINVAL;
+  }
+  if (this->is_array) {
+    this->fetch_internal_array(idx, value);
+  } else {
+    this->fetch_internal(this->d.t.root, idx, value);
+  }
+  return 0;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::find_zero(
+    const omtcmp_t &extra, omtdataout_t *const value,
+    uint32_t *const idxp) const {
+  uint32_t tmp_index;
+  uint32_t *const child_idxp = (idxp != nullptr) ? idxp : &tmp_index;
+  int r;
+  if (this->is_array) {
+    r = this->find_internal_zero_array<omtcmp_t, h>(extra, value, child_idxp);
+  } else {
+    r = this->find_internal_zero<omtcmp_t, h>(this->d.t.root, extra, value,
+                                              child_idxp);
+  }
+  return r;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::find(
+    const omtcmp_t &extra, int direction, omtdataout_t *const value,
+    uint32_t *const idxp) const {
+  uint32_t tmp_index;
+  uint32_t *const child_idxp = (idxp != nullptr) ? idxp : &tmp_index;
+  paranoid_invariant(direction != 0);
+  if (direction < 0) {
+    if (this->is_array) {
+      return this->find_internal_minus_array<omtcmp_t, h>(extra, value,
+                                                          child_idxp);
+    } else {
+      return this->find_internal_minus<omtcmp_t, h>(this->d.t.root, extra,
+                                                    value, child_idxp);
+    }
+  } else {
+    if (this->is_array) {
+      return this->find_internal_plus_array<omtcmp_t, h>(extra, value,
+                                                         child_idxp);
+    } else {
+      return this->find_internal_plus<omtcmp_t, h>(this->d.t.root, extra, value,
+                                                   child_idxp);
+    }
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+size_t omt<omtdata_t, omtdataout_t, supports_marks>::memory_size(void) {
+  if (this->is_array) {
+    return (sizeof *this) + this->capacity * (sizeof this->d.a.values[0]);
+  }
+  return (sizeof *this) + this->capacity * (sizeof this->d.t.nodes[0]);
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::create_internal_no_array(
+    const uint32_t new_capacity) {
+  this->is_array = true;
+  this->d.a.start_idx = 0;
+  this->d.a.num_values = 0;
+  this->d.a.values = nullptr;
+  this->capacity = new_capacity;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::create_internal(
+    const uint32_t new_capacity) {
+  this->create_internal_no_array(new_capacity);
+  XMALLOC_N(this->capacity, this->d.a.values);
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+uint32_t omt<omtdata_t, omtdataout_t, supports_marks>::nweight(
+    const subtree &st) const {
+  if (st.is_null()) {
+    return 0;
+  } else {
+    return this->d.t.nodes[st.get_index()].weight;
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+typename omt<omtdata_t, omtdataout_t, supports_marks>::node_idx
+omt<omtdata_t, omtdataout_t, supports_marks>::node_malloc(void) {
+  paranoid_invariant(this->d.t.free_idx < this->capacity);
+  omt_node &n = this->d.t.nodes[this->d.t.free_idx];
+  n.clear_stolen_bits();
+  return this->d.t.free_idx++;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::node_free(
+    const node_idx UU(idx)) {
+  paranoid_invariant(idx < this->capacity);
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::maybe_resize_array(
+    const uint32_t n) {
+  const uint32_t new_size = n <= 2 ? 4 : 2 * n;
+  const uint32_t room = this->capacity - this->d.a.start_idx;
+
+  if (room < n || this->capacity / 2 >= new_size) {
+    omtdata_t *XMALLOC_N(new_size, tmp_values);
+    if (this->d.a.num_values) {
+      memcpy(tmp_values, &this->d.a.values[this->d.a.start_idx],
+             this->d.a.num_values * (sizeof tmp_values[0]));
+    }
+    this->d.a.start_idx = 0;
+    this->capacity = new_size;
+    toku_free(this->d.a.values);
+    this->d.a.values = tmp_values;
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t,
+         supports_marks>::fill_array_with_subtree_values(omtdata_t *const array,
+                                                         const subtree &st)
+    const {
+  if (st.is_null()) return;
+  const omt_node &tree = this->d.t.nodes[st.get_index()];
+  this->fill_array_with_subtree_values(&array[0], tree.left);
+  array[this->nweight(tree.left)] = tree.value;
+  this->fill_array_with_subtree_values(&array[this->nweight(tree.left) + 1],
+                                       tree.right);
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::convert_to_array(void) {
+  if (!this->is_array) {
+    const uint32_t num_values = this->size();
+    uint32_t new_size = 2 * num_values;
+    new_size = new_size < 4 ? 4 : new_size;
+
+    omtdata_t *XMALLOC_N(new_size, tmp_values);
+    this->fill_array_with_subtree_values(tmp_values, this->d.t.root);
+    toku_free(this->d.t.nodes);
+    this->is_array = true;
+    this->capacity = new_size;
+    this->d.a.num_values = num_values;
+    this->d.a.values = tmp_values;
+    this->d.a.start_idx = 0;
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::rebuild_from_sorted_array(
+    subtree *const st, const omtdata_t *const values,
+    const uint32_t numvalues) {
+  if (numvalues == 0) {
+    st->set_to_null();
+  } else {
+    const uint32_t halfway = numvalues / 2;
+    const node_idx newidx = this->node_malloc();
+    omt_node *const newnode = &this->d.t.nodes[newidx];
+    newnode->weight = numvalues;
+    newnode->value = values[halfway];
+    st->set_index(newidx);
+    // update everything before the recursive calls so the second call
+    // can be a tail call.
+    this->rebuild_from_sorted_array(&newnode->left, &values[0], halfway);
+    this->rebuild_from_sorted_array(&newnode->right, &values[halfway + 1],
+                                    numvalues - (halfway + 1));
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::convert_to_tree(void) {
+  if (this->is_array) {
+    const uint32_t num_nodes = this->size();
+    uint32_t new_size = num_nodes * 2;
+    new_size = new_size < 4 ? 4 : new_size;
+
+    omt_node *XMALLOC_N(new_size, new_nodes);
+    omtdata_t *const values = this->d.a.values;
+    omtdata_t *const tmp_values = &values[this->d.a.start_idx];
+    this->is_array = false;
+    this->d.t.nodes = new_nodes;
+    this->capacity = new_size;
+    this->d.t.free_idx = 0;
+    this->d.t.root.set_to_null();
+    this->rebuild_from_sorted_array(&this->d.t.root, tmp_values, num_nodes);
+    toku_free(values);
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::maybe_resize_or_convert(
+    const uint32_t n) {
+  if (this->is_array) {
+    this->maybe_resize_array(n);
+  } else {
+    const uint32_t new_size = n <= 2 ? 4 : 2 * n;
+    const uint32_t num_nodes = this->nweight(this->d.t.root);
+    if ((this->capacity / 2 >= new_size) ||
+        (this->d.t.free_idx >= this->capacity && num_nodes < n) ||
+        (this->capacity < n)) {
+      this->convert_to_array();
+      // if we had a free list, the "supports_marks" version could
+      // just resize, as it is now, we have to convert to and back
+      // from an array.
+      if (supports_marks) {
+        this->convert_to_tree();
+      }
+    }
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+bool omt<omtdata_t, omtdataout_t, supports_marks>::will_need_rebalance(
+    const subtree &st, const int leftmod, const int rightmod) const {
+  if (st.is_null()) {
+    return false;
+  }
+  const omt_node &n = this->d.t.nodes[st.get_index()];
+  // one of the 1's is for the root.
+  // the other is to take ceil(n/2)
+  const uint32_t weight_left = this->nweight(n.left) + leftmod;
+  const uint32_t weight_right = this->nweight(n.right) + rightmod;
+  return ((1 + weight_left < (1 + 1 + weight_right) / 2) ||
+          (1 + weight_right < (1 + 1 + weight_left) / 2));
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::insert_internal(
+    subtree *const subtreep, const omtdata_t &value, const uint32_t idx,
+    subtree **const rebalance_subtree) {
+  if (subtreep->is_null()) {
+    paranoid_invariant_zero(idx);
+    const node_idx newidx = this->node_malloc();
+    omt_node *const newnode = &this->d.t.nodes[newidx];
+    newnode->weight = 1;
+    newnode->left.set_to_null();
+    newnode->right.set_to_null();
+    newnode->value = value;
+    subtreep->set_index(newidx);
+  } else {
+    omt_node &n = this->d.t.nodes[subtreep->get_index()];
+    n.weight++;
+    if (idx <= this->nweight(n.left)) {
+      if (*rebalance_subtree == nullptr &&
+          this->will_need_rebalance(*subtreep, 1, 0)) {
+        *rebalance_subtree = subtreep;
+      }
+      this->insert_internal(&n.left, value, idx, rebalance_subtree);
+    } else {
+      if (*rebalance_subtree == nullptr &&
+          this->will_need_rebalance(*subtreep, 0, 1)) {
+        *rebalance_subtree = subtreep;
+      }
+      const uint32_t sub_index = idx - this->nweight(n.left) - 1;
+      this->insert_internal(&n.right, value, sub_index, rebalance_subtree);
+    }
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::set_at_internal_array(
+    const omtdata_t &value, const uint32_t idx) {
+  this->d.a.values[this->d.a.start_idx + idx] = value;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::set_at_internal(
+    const subtree &st, const omtdata_t &value, const uint32_t idx) {
+  paranoid_invariant(!st.is_null());
+  omt_node &n = this->d.t.nodes[st.get_index()];
+  const uint32_t leftweight = this->nweight(n.left);
+  if (idx < leftweight) {
+    this->set_at_internal(n.left, value, idx);
+  } else if (idx == leftweight) {
+    n.value = value;
+  } else {
+    this->set_at_internal(n.right, value, idx - leftweight - 1);
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::delete_internal(
+    subtree *const subtreep, const uint32_t idx, omt_node *const copyn,
+    subtree **const rebalance_subtree) {
+  paranoid_invariant_notnull(subtreep);
+  paranoid_invariant_notnull(rebalance_subtree);
+  paranoid_invariant(!subtreep->is_null());
+  omt_node &n = this->d.t.nodes[subtreep->get_index()];
+  const uint32_t leftweight = this->nweight(n.left);
+  if (idx < leftweight) {
+    n.weight--;
+    if (*rebalance_subtree == nullptr &&
+        this->will_need_rebalance(*subtreep, -1, 0)) {
+      *rebalance_subtree = subtreep;
+    }
+    this->delete_internal(&n.left, idx, copyn, rebalance_subtree);
+  } else if (idx == leftweight) {
+    if (n.left.is_null()) {
+      const uint32_t oldidx = subtreep->get_index();
+      *subtreep = n.right;
+      if (copyn != nullptr) {
+        copyn->value = n.value;
+      }
+      this->node_free(oldidx);
+    } else if (n.right.is_null()) {
+      const uint32_t oldidx = subtreep->get_index();
+      *subtreep = n.left;
+      if (copyn != nullptr) {
+        copyn->value = n.value;
+      }
+      this->node_free(oldidx);
+    } else {
+      if (*rebalance_subtree == nullptr &&
+          this->will_need_rebalance(*subtreep, 0, -1)) {
+        *rebalance_subtree = subtreep;
+      }
+      // don't need to copy up value, it's only used by this
+      // next call, and when that gets to the bottom there
+      // won't be any more recursion
+      n.weight--;
+      this->delete_internal(&n.right, 0, &n, rebalance_subtree);
+    }
+  } else {
+    n.weight--;
+    if (*rebalance_subtree == nullptr &&
+        this->will_need_rebalance(*subtreep, 0, -1)) {
+      *rebalance_subtree = subtreep;
+    }
+    this->delete_internal(&n.right, idx - leftweight - 1, copyn,
+                          rebalance_subtree);
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename iterate_extra_t,
+          int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::iterate_internal_array(
+    const uint32_t left, const uint32_t right,
+    iterate_extra_t *const iterate_extra) const {
+  int r;
+  for (uint32_t i = left; i < right; ++i) {
+    r = f(this->d.a.values[this->d.a.start_idx + i], i, iterate_extra);
+    if (r != 0) {
+      return r;
+    }
+  }
+  return 0;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename iterate_extra_t,
+          int (*f)(omtdata_t *, const uint32_t, iterate_extra_t *const)>
+void omt<omtdata_t, omtdataout_t, supports_marks>::iterate_ptr_internal(
+    const uint32_t left, const uint32_t right, const subtree &st,
+    const uint32_t idx, iterate_extra_t *const iterate_extra) {
+  if (!st.is_null()) {
+    omt_node &n = this->d.t.nodes[st.get_index()];
+    const uint32_t idx_root = idx + this->nweight(n.left);
+    if (left < idx_root) {
+      this->iterate_ptr_internal<iterate_extra_t, f>(left, right, n.left, idx,
+                                                     iterate_extra);
+    }
+    if (left <= idx_root && idx_root < right) {
+      int r = f(&n.value, idx_root, iterate_extra);
+      lazy_assert_zero(r);
+    }
+    if (idx_root + 1 < right) {
+      this->iterate_ptr_internal<iterate_extra_t, f>(
+          left, right, n.right, idx_root + 1, iterate_extra);
+    }
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename iterate_extra_t,
+          int (*f)(omtdata_t *, const uint32_t, iterate_extra_t *const)>
+void omt<omtdata_t, omtdataout_t, supports_marks>::iterate_ptr_internal_array(
+    const uint32_t left, const uint32_t right,
+    iterate_extra_t *const iterate_extra) {
+  for (uint32_t i = left; i < right; ++i) {
+    int r = f(&this->d.a.values[this->d.a.start_idx + i], i, iterate_extra);
+    lazy_assert_zero(r);
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename iterate_extra_t,
+          int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::iterate_internal(
+    const uint32_t left, const uint32_t right, const subtree &st,
+    const uint32_t idx, iterate_extra_t *const iterate_extra) const {
+  if (st.is_null()) {
+    return 0;
+  }
+  int r;
+  const omt_node &n = this->d.t.nodes[st.get_index()];
+  const uint32_t idx_root = idx + this->nweight(n.left);
+  if (left < idx_root) {
+    r = this->iterate_internal<iterate_extra_t, f>(left, right, n.left, idx,
+                                                   iterate_extra);
+    if (r != 0) {
+      return r;
+    }
+  }
+  if (left <= idx_root && idx_root < right) {
+    r = f(n.value, idx_root, iterate_extra);
+    if (r != 0) {
+      return r;
+    }
+  }
+  if (idx_root + 1 < right) {
+    return this->iterate_internal<iterate_extra_t, f>(
+        left, right, n.right, idx_root + 1, iterate_extra);
+  }
+  return 0;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename iterate_extra_t,
+          int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::
+    iterate_and_mark_range_internal(const uint32_t left, const uint32_t right,
+                                    const subtree &st, const uint32_t idx,
+                                    iterate_extra_t *const iterate_extra) {
+  paranoid_invariant(!st.is_null());
+  int r;
+  omt_node &n = this->d.t.nodes[st.get_index()];
+  const uint32_t idx_root = idx + this->nweight(n.left);
+  if (left < idx_root && !n.left.is_null()) {
+    n.set_marks_below_bit();
+    r = this->iterate_and_mark_range_internal<iterate_extra_t, f>(
+        left, right, n.left, idx, iterate_extra);
+    if (r != 0) {
+      return r;
+    }
+  }
+  if (left <= idx_root && idx_root < right) {
+    n.set_marked_bit();
+    r = f(n.value, idx_root, iterate_extra);
+    if (r != 0) {
+      return r;
+    }
+  }
+  if (idx_root + 1 < right && !n.right.is_null()) {
+    n.set_marks_below_bit();
+    return this->iterate_and_mark_range_internal<iterate_extra_t, f>(
+        left, right, n.right, idx_root + 1, iterate_extra);
+  }
+  return 0;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename iterate_extra_t,
+          int (*f)(const omtdata_t &, const uint32_t, iterate_extra_t *const)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::iterate_over_marked_internal(
+    const subtree &st, const uint32_t idx,
+    iterate_extra_t *const iterate_extra) const {
+  if (st.is_null()) {
+    return 0;
+  }
+  int r;
+  const omt_node &n = this->d.t.nodes[st.get_index()];
+  const uint32_t idx_root = idx + this->nweight(n.left);
+  if (n.get_marks_below()) {
+    r = this->iterate_over_marked_internal<iterate_extra_t, f>(n.left, idx,
+                                                               iterate_extra);
+    if (r != 0) {
+      return r;
+    }
+  }
+  if (n.get_marked()) {
+    r = f(n.value, idx_root, iterate_extra);
+    if (r != 0) {
+      return r;
+    }
+  }
+  if (n.get_marks_below()) {
+    return this->iterate_over_marked_internal<iterate_extra_t, f>(
+        n.right, idx_root + 1, iterate_extra);
+  }
+  return 0;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::fetch_internal_array(
+    const uint32_t i, omtdataout_t *const value) const {
+  if (value != nullptr) {
+    copyout(value, &this->d.a.values[this->d.a.start_idx + i]);
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::fetch_internal(
+    const subtree &st, const uint32_t i, omtdataout_t *const value) const {
+  omt_node &n = this->d.t.nodes[st.get_index()];
+  const uint32_t leftweight = this->nweight(n.left);
+  if (i < leftweight) {
+    this->fetch_internal(n.left, i, value);
+  } else if (i == leftweight) {
+    if (value != nullptr) {
+      copyout(value, &n);
+    }
+  } else {
+    this->fetch_internal(n.right, i - leftweight - 1, value);
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::fill_array_with_subtree_idxs(
+    node_idx *const array, const subtree &st) const {
+  if (!st.is_null()) {
+    const omt_node &tree = this->d.t.nodes[st.get_index()];
+    this->fill_array_with_subtree_idxs(&array[0], tree.left);
+    array[this->nweight(tree.left)] = st.get_index();
+    this->fill_array_with_subtree_idxs(&array[this->nweight(tree.left) + 1],
+                                       tree.right);
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::rebuild_subtree_from_idxs(
+    subtree *const st, const node_idx *const idxs, const uint32_t numvalues) {
+  if (numvalues == 0) {
+    st->set_to_null();
+  } else {
+    uint32_t halfway = numvalues / 2;
+    st->set_index(idxs[halfway]);
+    // node_idx newidx = idxs[halfway];
+    omt_node &newnode = this->d.t.nodes[st->get_index()];
+    newnode.weight = numvalues;
+    // value is already in there.
+    this->rebuild_subtree_from_idxs(&newnode.left, &idxs[0], halfway);
+    this->rebuild_subtree_from_idxs(&newnode.right, &idxs[halfway + 1],
+                                    numvalues - (halfway + 1));
+    // n_idx = newidx;
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::rebalance(
+    subtree *const st) {
+  node_idx idx = st->get_index();
+  if (idx == this->d.t.root.get_index()) {
+    // Try to convert to an array.
+    // If this fails, (malloc) nothing will have changed.
+    // In the failure case we continue on to the standard rebalance
+    // algorithm.
+    this->convert_to_array();
+    if (supports_marks) {
+      this->convert_to_tree();
+    }
+  } else {
+    const omt_node &n = this->d.t.nodes[idx];
+    node_idx *tmp_array;
+    size_t mem_needed = n.weight * (sizeof tmp_array[0]);
+    size_t mem_free =
+        (this->capacity - this->d.t.free_idx) * (sizeof this->d.t.nodes[0]);
+    bool malloced;
+    if (mem_needed <= mem_free) {
+      // There is sufficient free space at the end of the nodes array
+      // to hold enough node indexes to rebalance.
+      malloced = false;
+      tmp_array =
+          reinterpret_cast<node_idx *>(&this->d.t.nodes[this->d.t.free_idx]);
+    } else {
+      malloced = true;
+      XMALLOC_N(n.weight, tmp_array);
+    }
+    this->fill_array_with_subtree_idxs(tmp_array, *st);
+    this->rebuild_subtree_from_idxs(st, tmp_array, n.weight);
+    if (malloced) toku_free(tmp_array);
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::copyout(
+    omtdata_t *const out, const omt_node *const n) {
+  *out = n->value;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::copyout(
+    omtdata_t **const out, omt_node *const n) {
+  *out = &n->value;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::copyout(
+    omtdata_t *const out, const omtdata_t *const stored_value_ptr) {
+  *out = *stored_value_ptr;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+void omt<omtdata_t, omtdataout_t, supports_marks>::copyout(
+    omtdata_t **const out, omtdata_t *const stored_value_ptr) {
+  *out = stored_value_ptr;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::find_internal_zero_array(
+    const omtcmp_t &extra, omtdataout_t *const value,
+    uint32_t *const idxp) const {
+  paranoid_invariant_notnull(idxp);
+  uint32_t min = this->d.a.start_idx;
+  uint32_t limit = this->d.a.start_idx + this->d.a.num_values;
+  uint32_t best_pos = subtree::NODE_NULL;
+  uint32_t best_zero = subtree::NODE_NULL;
+
+  while (min != limit) {
+    uint32_t mid = (min + limit) / 2;
+    int hv = h(this->d.a.values[mid], extra);
+    if (hv < 0) {
+      min = mid + 1;
+    } else if (hv > 0) {
+      best_pos = mid;
+      limit = mid;
+    } else {
+      best_zero = mid;
+      limit = mid;
+    }
+  }
+  if (best_zero != subtree::NODE_NULL) {
+    // Found a zero
+    if (value != nullptr) {
+      copyout(value, &this->d.a.values[best_zero]);
+    }
+    *idxp = best_zero - this->d.a.start_idx;
+    return 0;
+  }
+  if (best_pos != subtree::NODE_NULL)
+    *idxp = best_pos - this->d.a.start_idx;
+  else
+    *idxp = this->d.a.num_values;
+  return DB_NOTFOUND;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::find_internal_zero(
+    const subtree &st, const omtcmp_t &extra, omtdataout_t *const value,
+    uint32_t *const idxp) const {
+  paranoid_invariant_notnull(idxp);
+  if (st.is_null()) {
+    *idxp = 0;
+    return DB_NOTFOUND;
+  }
+  omt_node &n = this->d.t.nodes[st.get_index()];
+  int hv = h(n.value, extra);
+  if (hv < 0) {
+    int r = this->find_internal_zero<omtcmp_t, h>(n.right, extra, value, idxp);
+    *idxp += this->nweight(n.left) + 1;
+    return r;
+  } else if (hv > 0) {
+    return this->find_internal_zero<omtcmp_t, h>(n.left, extra, value, idxp);
+  } else {
+    int r = this->find_internal_zero<omtcmp_t, h>(n.left, extra, value, idxp);
+    if (r == DB_NOTFOUND) {
+      *idxp = this->nweight(n.left);
+      if (value != nullptr) {
+        copyout(value, &n);
+      }
+      r = 0;
+    }
+    return r;
+  }
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::find_internal_plus_array(
+    const omtcmp_t &extra, omtdataout_t *const value,
+    uint32_t *const idxp) const {
+  paranoid_invariant_notnull(idxp);
+  uint32_t min = this->d.a.start_idx;
+  uint32_t limit = this->d.a.start_idx + this->d.a.num_values;
+  uint32_t best = subtree::NODE_NULL;
+
+  while (min != limit) {
+    const uint32_t mid = (min + limit) / 2;
+    const int hv = h(this->d.a.values[mid], extra);
+    if (hv > 0) {
+      best = mid;
+      limit = mid;
+    } else {
+      min = mid + 1;
+    }
+  }
+  if (best == subtree::NODE_NULL) {
+    return DB_NOTFOUND;
+  }
+  if (value != nullptr) {
+    copyout(value, &this->d.a.values[best]);
+  }
+  *idxp = best - this->d.a.start_idx;
+  return 0;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::find_internal_plus(
+    const subtree &st, const omtcmp_t &extra, omtdataout_t *const value,
+    uint32_t *const idxp) const {
+  paranoid_invariant_notnull(idxp);
+  if (st.is_null()) {
+    return DB_NOTFOUND;
+  }
+  omt_node *const n = &this->d.t.nodes[st.get_index()];
+  int hv = h(n->value, extra);
+  int r;
+  if (hv > 0) {
+    r = this->find_internal_plus<omtcmp_t, h>(n->left, extra, value, idxp);
+    if (r == DB_NOTFOUND) {
+      *idxp = this->nweight(n->left);
+      if (value != nullptr) {
+        copyout(value, n);
+      }
+      r = 0;
+    }
+  } else {
+    r = this->find_internal_plus<omtcmp_t, h>(n->right, extra, value, idxp);
+    if (r == 0) {
+      *idxp += this->nweight(n->left) + 1;
+    }
+  }
+  return r;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::find_internal_minus_array(
+    const omtcmp_t &extra, omtdataout_t *const value,
+    uint32_t *const idxp) const {
+  paranoid_invariant_notnull(idxp);
+  uint32_t min = this->d.a.start_idx;
+  uint32_t limit = this->d.a.start_idx + this->d.a.num_values;
+  uint32_t best = subtree::NODE_NULL;
+
+  while (min != limit) {
+    const uint32_t mid = (min + limit) / 2;
+    const int hv = h(this->d.a.values[mid], extra);
+    if (hv < 0) {
+      best = mid;
+      min = mid + 1;
+    } else {
+      limit = mid;
+    }
+  }
+  if (best == subtree::NODE_NULL) {
+    return DB_NOTFOUND;
+  }
+  if (value != nullptr) {
+    copyout(value, &this->d.a.values[best]);
+  }
+  *idxp = best - this->d.a.start_idx;
+  return 0;
+}
+
+template <typename omtdata_t, typename omtdataout_t, bool supports_marks>
+template <typename omtcmp_t, int (*h)(const omtdata_t &, const omtcmp_t &)>
+int omt<omtdata_t, omtdataout_t, supports_marks>::find_internal_minus(
+    const subtree &st, const omtcmp_t &extra, omtdataout_t *const value,
+    uint32_t *const idxp) const {
+  paranoid_invariant_notnull(idxp);
+  if (st.is_null()) {
+    return DB_NOTFOUND;
+  }
+  omt_node *const n = &this->d.t.nodes[st.get_index()];
+  int hv = h(n->value, extra);
+  if (hv < 0) {
+    int r =
+        this->find_internal_minus<omtcmp_t, h>(n->right, extra, value, idxp);
+    if (r == 0) {
+      *idxp += this->nweight(n->left) + 1;
+    } else if (r == DB_NOTFOUND) {
+      *idxp = this->nweight(n->left);
+      if (value != nullptr) {
+        copyout(value, n);
+      }
+      r = 0;
+    }
+    return r;
+  } else {
+    return this->find_internal_minus<omtcmp_t, h>(n->left, extra, value, idxp);
+  }
+}
+}  // namespace toku
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/partitioned_counter.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/partitioned_counter.h
new file mode 100644
index 000000000..f20eeedf2
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/partitioned_counter.h
@@ -0,0 +1,165 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+// Overview: A partitioned_counter provides a counter that can be incremented
+// and the running sum can be read at any time.
+//  We assume that increments are frequent, whereas reading is infrequent.
+// Implementation hint: Use thread-local storage so each thread increments its
+// own data.  The increment does not require a lock or atomic operation.
+//  Reading the data can be performed by iterating over the thread-local
+//  versions, summing them up. The data structure also includes a sum for all
+//  the threads that have died. Use a pthread_key to create the thread-local
+//  versions.  When a thread finishes, the system calls pthread_key destructor
+//  which can add that thread's copy into the sum_of_dead counter.
+// Rationale: For statistics such as are found in engine status, we need a
+// counter that requires no cache misses to increment.  We've seen significant
+//  performance speedups by removing certain counters.  Rather than removing
+//  those statistics, we would like to just make the counter fast. We generally
+//  increment the counters frequently, and want to fetch the values
+//  infrequently. The counters are monotonic. The counters can be split into
+//  many counters, which can be summed up at the end. We don't care if we get
+//  slightly out-of-date counter sums when we read the counter.  We don't care
+//  if there is a race on reading the a counter
+//   variable and incrementing.
+//  See tests/test_partitioned_counter.c for some performance measurements.
+// Operations:
+//   create_partitioned_counter    Create a counter initialized to zero.
+//   destroy_partitioned_counter   Destroy it.
+//   increment_partitioned_counter Increment it.  This is the frequent
+//   operation. read_partitioned_counter      Get the current value.  This is
+//   infrequent.
+// See partitioned_counter.cc for the abstraction function and representation
+// invariant.
+//
+// The google style guide says to avoid using constructors, and it appears that
+// constructors may have broken all the tests, because they called
+// pthread_key_create before the key was actually created.  So the google style
+// guide may have some wisdom there...
+//
+// This version does not use constructors, essentially reverrting to the google
+// C++ style guide.
+//
+
+// The old C interface.  This required a bunch of explicit
+// ___attribute__((__destructor__)) functions to remember to destroy counters at
+// the end.
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+typedef struct partitioned_counter *PARTITIONED_COUNTER;
+PARTITIONED_COUNTER create_partitioned_counter(void);
+// Effect: Create a counter, initialized to zero.
+
+void destroy_partitioned_counter(PARTITIONED_COUNTER);
+// Effect: Destroy the counter.  No operations on that counter are permitted
+// after this.
+
+void increment_partitioned_counter(PARTITIONED_COUNTER, uint64_t amount);
+// Effect: Increment the counter by amount.
+// Requires: No overflows.  This is a 64-bit unsigned counter.
+
+uint64_t read_partitioned_counter(PARTITIONED_COUNTER)
+    __attribute__((__visibility__("default")));
+// Effect: Return the current value of the counter.
+
+void partitioned_counters_init(void);
+// Effect: Initialize any partitioned counters data structures that must be set
+// up before any partitioned counters run.
+
+void partitioned_counters_destroy(void);
+// Effect: Destroy any partitioned counters data structures.
+
+#if defined(__cplusplus)
+};
+#endif
+
+#if 0
+#include <pthread.h>
+
+#include "fttypes.h"
+
+// Used inside the PARTITIONED_COUNTER.
+struct linked_list_head {
+    struct linked_list_element *first;
+};
+
+
+class PARTITIONED_COUNTER {
+public:
+    PARTITIONED_COUNTER(void);
+    // Effect: Construct a counter, initialized to zero.
+
+    ~PARTITIONED_COUNTER(void);
+    // Effect: Destruct the counter.
+
+    void increment(uint64_t amount);
+    // Effect: Increment the counter by amount.  This is a 64-bit unsigned counter, and if you overflow it, you will get overflowed results (that is mod 2^64).
+    // Requires: Don't use this from a static constructor or destructor.
+
+    uint64_t read(void);
+    // Effect: Read the sum.
+    // Requires: Don't use this from a static constructor or destructor.
+
+private:
+    uint64_t       _sum_of_dead;             // The sum of all thread-local counts from threads that have terminated.
+    pthread_key_t   _key;                     // The pthread_key which gives us the hook to construct and destruct thread-local storage.
+    struct linked_list_head _ll_counter_head; // A linked list of all the thread-local information for this counter.
+    
+    // This function is used to destroy the thread-local part of the state when a thread terminates.
+    // But it's not the destructor for the local part of the counter, it's a destructor on a "dummy" key just so that we get a notification when a thread ends.
+    friend void destroy_thread_local_part_of_partitioned_counters (void *);
+};
+#endif
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/status.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/status.h
new file mode 100644
index 000000000..3fd0095d0
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/lib/util/status.h
@@ -0,0 +1,76 @@
+/* -*- mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+// vim: ft=cpp:expandtab:ts=8:sw=4:softtabstop=4:
+#ident "$Id$"
+/*======
+This file is part of PerconaFT.
+
+
+Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved.
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License, version 2,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+    PerconaFT is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License, version 3,
+    as published by the Free Software Foundation.
+
+    PerconaFT is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Affero General Public License for more details.
+
+    You should have received a copy of the GNU Affero General Public License
+    along with PerconaFT.  If not, see <http://www.gnu.org/licenses/>.
+
+----------------------------------------
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+======= */
+
+#ident \
+    "Copyright (c) 2006, 2015, Percona and/or its affiliates. All rights reserved."
+
+#pragma once
+
+#include "partitioned_counter.h"
+// PORT2: #include <util/constexpr.h>
+
+#define TOKUFT_STATUS_INIT(array, k, c, t, l, inc)                    \
+  do {                                                                \
+    array.status[k].keyname = #k;                                     \
+    array.status[k].columnname = #c;                                  \
+    array.status[k].type = t;                                         \
+    array.status[k].legend = l;                                       \
+    constexpr_static_assert(                                          \
+        strcmp(#c, "NULL") && strcmp(#c, "0"),                        \
+        "Use nullptr for no column name instead of NULL, 0, etc..."); \
+    constexpr_static_assert(                                          \
+        (inc) == TOKU_ENGINE_STATUS || strcmp(#c, "nullptr"),         \
+        "Missing column name.");                                      \
+    array.status[k].include =                                         \
+        static_cast<toku_engine_status_include_type>(inc);            \
+    if (t == STATUS_PARCOUNT) {                                       \
+      array.status[k].value.parcount = create_partitioned_counter();  \
+    }                                                                 \
+  } while (0)
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_manager.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_manager.cc
new file mode 100644
index 000000000..531165dea
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_manager.cc
@@ -0,0 +1,503 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+
+#include "utilities/transactions/lock/range/range_tree/range_tree_lock_manager.h"
+
+#include <algorithm>
+#include <cinttypes>
+#include <mutex>
+
+#include "monitoring/perf_context_imp.h"
+#include "rocksdb/slice.h"
+#include "rocksdb/utilities/transaction_db_mutex.h"
+#include "test_util/sync_point.h"
+#include "util/cast_util.h"
+#include "util/hash.h"
+#include "util/thread_local.h"
+#include "utilities/transactions/lock/range/range_tree/range_tree_lock_tracker.h"
+#include "utilities/transactions/pessimistic_transaction_db.h"
+#include "utilities/transactions/transaction_db_mutex_impl.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+RangeLockManagerHandle* NewRangeLockManager(
+    std::shared_ptr<TransactionDBMutexFactory> mutex_factory) {
+  std::shared_ptr<TransactionDBMutexFactory> use_factory;
+
+  if (mutex_factory) {
+    use_factory = mutex_factory;
+  } else {
+    use_factory.reset(new TransactionDBMutexFactoryImpl());
+  }
+  return new RangeTreeLockManager(use_factory);
+}
+
+static const char SUFFIX_INFIMUM = 0x0;
+static const char SUFFIX_SUPREMUM = 0x1;
+
+// Convert Endpoint into an internal format used for storing it in locktree
+// (DBT structure is used for passing endpoints to locktree and getting back)
+void serialize_endpoint(const Endpoint& endp, std::string* buf) {
+  buf->push_back(endp.inf_suffix ? SUFFIX_SUPREMUM : SUFFIX_INFIMUM);
+  buf->append(endp.slice.data(), endp.slice.size());
+}
+
+// Decode the endpoint from the format it is stored in the locktree (DBT) to
+// the one used outside: either Endpoint or EndpointWithString
+template <typename EndpointStruct>
+void deserialize_endpoint(const DBT* dbt, EndpointStruct* endp) {
+  assert(dbt->size >= 1);
+  const char* dbt_data = (const char*)dbt->data;
+  char suffix = dbt_data[0];
+  assert(suffix == SUFFIX_INFIMUM || suffix == SUFFIX_SUPREMUM);
+  endp->inf_suffix = (suffix == SUFFIX_SUPREMUM);
+  endp->slice = decltype(EndpointStruct::slice)(dbt_data + 1, dbt->size - 1);
+}
+
+// Get a range lock on [start_key; end_key] range
+Status RangeTreeLockManager::TryLock(PessimisticTransaction* txn,
+                                     uint32_t column_family_id,
+                                     const Endpoint& start_endp,
+                                     const Endpoint& end_endp, Env*,
+                                     bool exclusive) {
+  toku::lock_request request;
+  request.create(mutex_factory_);
+  DBT start_key_dbt, end_key_dbt;
+
+  TEST_SYNC_POINT("RangeTreeLockManager::TryRangeLock:enter");
+  std::string start_key;
+  std::string end_key;
+  serialize_endpoint(start_endp, &start_key);
+  serialize_endpoint(end_endp, &end_key);
+
+  toku_fill_dbt(&start_key_dbt, start_key.data(), start_key.size());
+  toku_fill_dbt(&end_key_dbt, end_key.data(), end_key.size());
+
+  auto lt = GetLockTreeForCF(column_family_id);
+
+  // Put the key waited on into request's m_extra. See
+  // wait_callback_for_locktree for details.
+  std::string wait_key(start_endp.slice.data(), start_endp.slice.size());
+
+  request.set(lt.get(), (TXNID)txn, &start_key_dbt, &end_key_dbt,
+              exclusive ? toku::lock_request::WRITE : toku::lock_request::READ,
+              false /* not a big txn */, &wait_key);
+
+  // This is for "periodically wake up and check if the wait is killed" feature
+  // which we are not using.
+  uint64_t killed_time_msec = 0;
+  uint64_t wait_time_msec = txn->GetLockTimeout();
+
+  if (wait_time_msec == static_cast<uint64_t>(-1)) {
+    // The transaction has no wait timeout. lock_request::wait doesn't support
+    // this, it needs a number of milliseconds to wait. Pass it one year to
+    // be safe.
+    wait_time_msec = uint64_t(1000) * 60 * 60 * 24 * 365;
+  } else {
+    // convert microseconds to milliseconds
+    wait_time_msec = (wait_time_msec + 500) / 1000;
+  }
+
+  std::vector<RangeDeadlockInfo> di_path;
+  request.m_deadlock_cb = [&](TXNID txnid, bool is_exclusive,
+                              const DBT* start_dbt, const DBT* end_dbt) {
+    EndpointWithString start;
+    EndpointWithString end;
+    deserialize_endpoint(start_dbt, &start);
+    deserialize_endpoint(end_dbt, &end);
+
+    di_path.push_back({txnid, column_family_id, is_exclusive, std::move(start),
+                       std::move(end)});
+  };
+
+  request.start();
+
+  const int r = request.wait(wait_time_msec, killed_time_msec,
+                             nullptr,  // killed_callback
+                             wait_callback_for_locktree, nullptr);
+
+  // Inform the txn that we are no longer waiting:
+  txn->ClearWaitingTxn();
+
+  request.destroy();
+  switch (r) {
+    case 0:
+      break;  // fall through
+    case DB_LOCK_NOTGRANTED:
+      return Status::TimedOut(Status::SubCode::kLockTimeout);
+    case TOKUDB_OUT_OF_LOCKS:
+      return Status::Busy(Status::SubCode::kLockLimit);
+    case DB_LOCK_DEADLOCK: {
+      std::reverse(di_path.begin(), di_path.end());
+      dlock_buffer_.AddNewPath(
+          RangeDeadlockPath(di_path, request.get_start_time()));
+      return Status::Busy(Status::SubCode::kDeadlock);
+    }
+    default:
+      assert(0);
+      return Status::Busy(Status::SubCode::kLockLimit);
+  }
+
+  return Status::OK();
+}
+
+// Wait callback that locktree library will call to inform us about
+// the lock waits that are in progress.
+void wait_callback_for_locktree(void*, toku::lock_wait_infos* infos) {
+  TEST_SYNC_POINT("RangeTreeLockManager::TryRangeLock:EnterWaitingTxn");
+  for (auto wait_info : *infos) {
+    // As long as we hold the lock on the locktree's pending request queue
+    // this should be safe.
+    auto txn = (PessimisticTransaction*)wait_info.waiter;
+    auto cf_id = (ColumnFamilyId)wait_info.ltree->get_dict_id().dictid;
+
+    autovector<TransactionID> waitee_ids;
+    for (auto waitee : wait_info.waitees) {
+      waitee_ids.push_back(waitee);
+    }
+    txn->SetWaitingTxn(waitee_ids, cf_id, (std::string*)wait_info.m_extra);
+  }
+
+  // Here we can assume that the locktree code will now wait for some lock
+  TEST_SYNC_POINT("RangeTreeLockManager::TryRangeLock:WaitingTxn");
+}
+
+void RangeTreeLockManager::UnLock(PessimisticTransaction* txn,
+                                  ColumnFamilyId column_family_id,
+                                  const std::string& key, Env*) {
+  auto locktree = GetLockTreeForCF(column_family_id);
+  std::string endp_image;
+  serialize_endpoint({key.data(), key.size(), false}, &endp_image);
+
+  DBT key_dbt;
+  toku_fill_dbt(&key_dbt, endp_image.data(), endp_image.size());
+
+  toku::range_buffer range_buf;
+  range_buf.create();
+  range_buf.append(&key_dbt, &key_dbt);
+
+  locktree->release_locks((TXNID)txn, &range_buf);
+  range_buf.destroy();
+
+  toku::lock_request::retry_all_lock_requests(
+      locktree.get(), wait_callback_for_locktree, nullptr);
+}
+
+void RangeTreeLockManager::UnLock(PessimisticTransaction* txn,
+                                  const LockTracker& tracker, Env*) {
+  const RangeTreeLockTracker* range_tracker =
+      static_cast<const RangeTreeLockTracker*>(&tracker);
+
+  RangeTreeLockTracker* range_trx_tracker =
+      static_cast<RangeTreeLockTracker*>(&txn->GetTrackedLocks());
+  bool all_keys = (range_trx_tracker == range_tracker);
+
+  // tracked_locks_->range_list may hold nullptr if the transaction has never
+  // acquired any locks.
+  ((RangeTreeLockTracker*)range_tracker)->ReleaseLocks(this, txn, all_keys);
+}
+
+int RangeTreeLockManager::CompareDbtEndpoints(void* arg, const DBT* a_key,
+                                              const DBT* b_key) {
+  const char* a = (const char*)a_key->data;
+  const char* b = (const char*)b_key->data;
+
+  size_t a_len = a_key->size;
+  size_t b_len = b_key->size;
+
+  size_t min_len = std::min(a_len, b_len);
+
+  // Compare the values. The first byte encodes the endpoint type, its value
+  // is either SUFFIX_INFIMUM or SUFFIX_SUPREMUM.
+  Comparator* cmp = (Comparator*)arg;
+  int res = cmp->Compare(Slice(a + 1, min_len - 1), Slice(b + 1, min_len - 1));
+  if (!res) {
+    if (b_len > min_len) {
+      // a is shorter;
+      if (a[0] == SUFFIX_INFIMUM) {
+        return -1;  //"a is smaller"
+      } else {
+        // a is considered padded with 0xFF:FF:FF:FF...
+        return 1;  // "a" is bigger
+      }
+    } else if (a_len > min_len) {
+      // the opposite of the above: b is shorter.
+      if (b[0] == SUFFIX_INFIMUM) {
+        return 1;  //"b is smaller"
+      } else {
+        // b is considered padded with 0xFF:FF:FF:FF...
+        return -1;  // "b" is bigger
+      }
+    } else {
+      // the lengths are equal (and the key values, too)
+      if (a[0] < b[0]) {
+        return -1;
+      } else if (a[0] > b[0]) {
+        return 1;
+      } else {
+        return 0;
+      }
+    }
+  } else {
+    return res;
+  }
+}
+
+namespace {
+void UnrefLockTreeMapsCache(void* ptr) {
+  // Called when a thread exits or a ThreadLocalPtr gets destroyed.
+  auto lock_tree_map_cache = static_cast<
+      std::unordered_map<ColumnFamilyId, std::shared_ptr<toku::locktree>>*>(
+      ptr);
+  delete lock_tree_map_cache;
+}
+}  // anonymous namespace
+
+RangeTreeLockManager::RangeTreeLockManager(
+    std::shared_ptr<TransactionDBMutexFactory> mutex_factory)
+    : mutex_factory_(mutex_factory),
+      ltree_lookup_cache_(new ThreadLocalPtr(&UnrefLockTreeMapsCache)),
+      dlock_buffer_(10) {
+  ltm_.create(on_create, on_destroy, on_escalate, nullptr, mutex_factory_);
+}
+
+int RangeTreeLockManager::on_create(toku::locktree* lt, void* arg) {
+  // arg is a pointer to RangeTreeLockManager
+  lt->set_escalation_barrier_func(&OnEscalationBarrierCheck, arg);
+  return 0;
+}
+
+bool RangeTreeLockManager::OnEscalationBarrierCheck(const DBT* a, const DBT* b,
+                                                    void* extra) {
+  Endpoint a_endp, b_endp;
+  deserialize_endpoint(a, &a_endp);
+  deserialize_endpoint(b, &b_endp);
+  auto self = static_cast<RangeTreeLockManager*>(extra);
+  return self->barrier_func_(a_endp, b_endp);
+}
+
+void RangeTreeLockManager::SetRangeDeadlockInfoBufferSize(
+    uint32_t target_size) {
+  dlock_buffer_.Resize(target_size);
+}
+
+void RangeTreeLockManager::Resize(uint32_t target_size) {
+  SetRangeDeadlockInfoBufferSize(target_size);
+}
+
+std::vector<RangeDeadlockPath>
+RangeTreeLockManager::GetRangeDeadlockInfoBuffer() {
+  return dlock_buffer_.PrepareBuffer();
+}
+
+std::vector<DeadlockPath> RangeTreeLockManager::GetDeadlockInfoBuffer() {
+  std::vector<DeadlockPath> res;
+  std::vector<RangeDeadlockPath> data = GetRangeDeadlockInfoBuffer();
+  // report left endpoints
+  for (auto it = data.begin(); it != data.end(); ++it) {
+    std::vector<DeadlockInfo> path;
+
+    for (auto it2 = it->path.begin(); it2 != it->path.end(); ++it2) {
+      path.push_back(
+          {it2->m_txn_id, it2->m_cf_id, it2->m_exclusive, it2->m_start.slice});
+    }
+    res.push_back(DeadlockPath(path, it->deadlock_time));
+  }
+  return res;
+}
+
+// @brief  Lock Escalation Callback function
+//
+// @param txnid   Transaction whose locks got escalated
+// @param lt      Lock Tree where escalation is happening
+// @param buffer  Escalation result: list of locks that this transaction now
+//                owns in this lock tree.
+// @param void*   Callback context
+void RangeTreeLockManager::on_escalate(TXNID txnid, const toku::locktree* lt,
+                                       const toku::range_buffer& buffer,
+                                       void*) {
+  auto txn = (PessimisticTransaction*)txnid;
+  ((RangeTreeLockTracker*)&txn->GetTrackedLocks())->ReplaceLocks(lt, buffer);
+}
+
+RangeTreeLockManager::~RangeTreeLockManager() {
+  autovector<void*> local_caches;
+  ltree_lookup_cache_->Scrape(&local_caches, nullptr);
+  for (auto cache : local_caches) {
+    delete static_cast<LockTreeMap*>(cache);
+  }
+  ltree_map_.clear();  // this will call release_lt() for all locktrees
+  ltm_.destroy();
+}
+
+RangeLockManagerHandle::Counters RangeTreeLockManager::GetStatus() {
+  LTM_STATUS_S ltm_status_test;
+  ltm_.get_status(&ltm_status_test);
+  Counters res;
+
+  // Searching status variable by its string name is how Toku's unit tests
+  // do it (why didn't they make LTM_ESCALATION_COUNT constant visible?)
+  // lookup keyname in status
+  for (int i = 0; i < LTM_STATUS_S::LTM_STATUS_NUM_ROWS; i++) {
+    TOKU_ENGINE_STATUS_ROW status = &ltm_status_test.status[i];
+    if (strcmp(status->keyname, "LTM_ESCALATION_COUNT") == 0) {
+      res.escalation_count = status->value.num;
+      continue;
+    }
+    if (strcmp(status->keyname, "LTM_WAIT_COUNT") == 0) {
+      res.lock_wait_count = status->value.num;
+      continue;
+    }
+    if (strcmp(status->keyname, "LTM_SIZE_CURRENT") == 0) {
+      res.current_lock_memory = status->value.num;
+    }
+  }
+  return res;
+}
+
+std::shared_ptr<toku::locktree> RangeTreeLockManager::MakeLockTreePtr(
+    toku::locktree* lt) {
+  toku::locktree_manager* ltm = &ltm_;
+  return std::shared_ptr<toku::locktree>(
+      lt, [ltm](toku::locktree* p) { ltm->release_lt(p); });
+}
+
+void RangeTreeLockManager::AddColumnFamily(const ColumnFamilyHandle* cfh) {
+  uint32_t column_family_id = cfh->GetID();
+
+  InstrumentedMutexLock l(&ltree_map_mutex_);
+  if (ltree_map_.find(column_family_id) == ltree_map_.end()) {
+    DICTIONARY_ID dict_id = {.dictid = column_family_id};
+    toku::comparator cmp;
+    cmp.create(CompareDbtEndpoints, (void*)cfh->GetComparator());
+    toku::locktree* ltree =
+        ltm_.get_lt(dict_id, cmp,
+                    /* on_create_extra*/ static_cast<void*>(this));
+    // This is ok to because get_lt has copied the comparator:
+    cmp.destroy();
+
+    ltree_map_.insert({column_family_id, MakeLockTreePtr(ltree)});
+  }
+}
+
+void RangeTreeLockManager::RemoveColumnFamily(const ColumnFamilyHandle* cfh) {
+  uint32_t column_family_id = cfh->GetID();
+  // Remove lock_map for this column family.  Since the lock map is stored
+  // as a shared ptr, concurrent transactions can still keep using it
+  // until they release their references to it.
+
+  // TODO what if one drops a column family while transaction(s) still have
+  // locks in it?
+  // locktree uses column family'c Comparator* as the criteria to do tree
+  // ordering. If the comparator is gone, we won't even be able to remove the
+  // elements from the locktree.
+  // A possible solution might be to remove everything right now:
+  //  - wait until everyone traversing the locktree are gone
+  //  - remove everything from the locktree.
+  //  - some transactions may have acquired locks in their LockTracker objects.
+  //    Arrange something so we don't blow up when they try to release them.
+  //  - ...
+  // This use case (drop column family while somebody is using it) doesn't seem
+  // the priority, though.
+
+  {
+    InstrumentedMutexLock l(&ltree_map_mutex_);
+
+    auto lock_maps_iter = ltree_map_.find(column_family_id);
+    assert(lock_maps_iter != ltree_map_.end());
+    ltree_map_.erase(lock_maps_iter);
+  }  // lock_map_mutex_
+
+  autovector<void*> local_caches;
+  ltree_lookup_cache_->Scrape(&local_caches, nullptr);
+  for (auto cache : local_caches) {
+    delete static_cast<LockTreeMap*>(cache);
+  }
+}
+
+std::shared_ptr<toku::locktree> RangeTreeLockManager::GetLockTreeForCF(
+    ColumnFamilyId column_family_id) {
+  // First check thread-local cache
+  if (ltree_lookup_cache_->Get() == nullptr) {
+    ltree_lookup_cache_->Reset(new LockTreeMap());
+  }
+
+  auto ltree_map_cache = static_cast<LockTreeMap*>(ltree_lookup_cache_->Get());
+
+  auto it = ltree_map_cache->find(column_family_id);
+  if (it != ltree_map_cache->end()) {
+    // Found lock map for this column family.
+    return it->second;
+  }
+
+  // Not found in local cache, grab mutex and check shared LockMaps
+  InstrumentedMutexLock l(&ltree_map_mutex_);
+
+  it = ltree_map_.find(column_family_id);
+  if (it == ltree_map_.end()) {
+    return nullptr;
+  } else {
+    // Found lock map.  Store in thread-local cache and return.
+    ltree_map_cache->insert({column_family_id, it->second});
+    return it->second;
+  }
+}
+
+struct LOCK_PRINT_CONTEXT {
+  RangeLockManagerHandle::RangeLockStatus* data;  // Save locks here
+  uint32_t cfh_id;  // Column Family whose tree we are traversing
+};
+
+// Report left endpoints of the acquired locks
+LockManager::PointLockStatus RangeTreeLockManager::GetPointLockStatus() {
+  PointLockStatus res;
+  LockManager::RangeLockStatus data = GetRangeLockStatus();
+  // report left endpoints
+  for (auto it = data.begin(); it != data.end(); ++it) {
+    auto& val = it->second;
+    res.insert({it->first, {val.start.slice, val.ids, val.exclusive}});
+  }
+  return res;
+}
+
+static void push_into_lock_status_data(void* param, const DBT* left,
+                                       const DBT* right, TXNID txnid_arg,
+                                       bool is_shared, TxnidVector* owners) {
+  struct LOCK_PRINT_CONTEXT* ctx = (LOCK_PRINT_CONTEXT*)param;
+  struct RangeLockInfo info;
+
+  info.exclusive = !is_shared;
+
+  deserialize_endpoint(left, &info.start);
+  deserialize_endpoint(right, &info.end);
+
+  if (txnid_arg != TXNID_SHARED) {
+    info.ids.push_back(txnid_arg);
+  } else {
+    for (auto it : *owners) {
+      info.ids.push_back(it);
+    }
+  }
+  ctx->data->insert({ctx->cfh_id, info});
+}
+
+LockManager::RangeLockStatus RangeTreeLockManager::GetRangeLockStatus() {
+  LockManager::RangeLockStatus data;
+  {
+    InstrumentedMutexLock l(&ltree_map_mutex_);
+    for (auto it : ltree_map_) {
+      LOCK_PRINT_CONTEXT ctx = {&data, it.first};
+      it.second->dump_locks((void*)&ctx, push_into_lock_status_data);
+    }
+  }
+  return data;
+}
+
+}  // namespace ROCKSDB_NAMESPACE
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_manager.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_manager.h
new file mode 100644
index 000000000..e4236d600
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_manager.h
@@ -0,0 +1,137 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+
+// For DeadlockInfoBuffer:
+#include "util/thread_local.h"
+#include "utilities/transactions/lock/point/point_lock_manager.h"
+#include "utilities/transactions/lock/range/range_lock_manager.h"
+
+// Lock Tree library:
+#include "utilities/transactions/lock/range/range_tree/lib/locktree/lock_request.h"
+#include "utilities/transactions/lock/range/range_tree/lib/locktree/locktree.h"
+#include "utilities/transactions/lock/range/range_tree/range_tree_lock_tracker.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+typedef DeadlockInfoBufferTempl<RangeDeadlockPath> RangeDeadlockInfoBuffer;
+
+// A Range Lock Manager that uses PerconaFT's locktree library
+class RangeTreeLockManager : public RangeLockManagerBase,
+                             public RangeLockManagerHandle {
+ public:
+  LockManager* getLockManager() override { return this; }
+
+  void AddColumnFamily(const ColumnFamilyHandle* cfh) override;
+  void RemoveColumnFamily(const ColumnFamilyHandle* cfh) override;
+
+  void Resize(uint32_t) override;
+  std::vector<DeadlockPath> GetDeadlockInfoBuffer() override;
+
+  std::vector<RangeDeadlockPath> GetRangeDeadlockInfoBuffer() override;
+  void SetRangeDeadlockInfoBufferSize(uint32_t target_size) override;
+
+  // Get a lock on a range
+  //  @note only exclusive locks are currently supported (requesting a
+  //  non-exclusive lock will get an exclusive one)
+  using LockManager::TryLock;
+  Status TryLock(PessimisticTransaction* txn, ColumnFamilyId column_family_id,
+                 const Endpoint& start_endp, const Endpoint& end_endp, Env* env,
+                 bool exclusive) override;
+
+  void UnLock(PessimisticTransaction* txn, const LockTracker& tracker,
+              Env* env) override;
+  void UnLock(PessimisticTransaction* txn, ColumnFamilyId column_family_id,
+              const std::string& key, Env* env) override;
+  void UnLock(PessimisticTransaction*, ColumnFamilyId, const Endpoint&,
+              const Endpoint&, Env*) override {
+    // TODO: range unlock does nothing...
+  }
+
+  explicit RangeTreeLockManager(
+      std::shared_ptr<TransactionDBMutexFactory> mutex_factory);
+
+  ~RangeTreeLockManager() override;
+
+  int SetMaxLockMemory(size_t max_lock_memory) override {
+    return ltm_.set_max_lock_memory(max_lock_memory);
+  }
+
+  size_t GetMaxLockMemory() override { return ltm_.get_max_lock_memory(); }
+
+  Counters GetStatus() override;
+
+  bool IsPointLockSupported() const override {
+    // One could have acquired a point lock (it is reduced to range lock)
+    return true;
+  }
+
+  PointLockStatus GetPointLockStatus() override;
+
+  // This is from LockManager
+  LockManager::RangeLockStatus GetRangeLockStatus() override;
+
+  // This has the same meaning as GetRangeLockStatus but is from
+  // RangeLockManagerHandle
+  RangeLockManagerHandle::RangeLockStatus GetRangeLockStatusData() override {
+    return GetRangeLockStatus();
+  }
+
+  bool IsRangeLockSupported() const override { return true; }
+
+  const LockTrackerFactory& GetLockTrackerFactory() const override {
+    return RangeTreeLockTrackerFactory::Get();
+  }
+
+  // Get the locktree which stores locks for the Column Family with given cf_id
+  std::shared_ptr<toku::locktree> GetLockTreeForCF(ColumnFamilyId cf_id);
+
+  void SetEscalationBarrierFunc(EscalationBarrierFunc func) override {
+    barrier_func_ = func;
+  }
+
+ private:
+  toku::locktree_manager ltm_;
+
+  EscalationBarrierFunc barrier_func_ =
+      [](const Endpoint&, const Endpoint&) -> bool { return false; };
+
+  std::shared_ptr<TransactionDBMutexFactory> mutex_factory_;
+
+  // Map from cf_id to locktree*. Can only be accessed while holding the
+  // ltree_map_mutex_. Must use a custom deleter that calls ltm_.release_lt
+  using LockTreeMap =
+      std::unordered_map<ColumnFamilyId, std::shared_ptr<toku::locktree>>;
+  LockTreeMap ltree_map_;
+
+  InstrumentedMutex ltree_map_mutex_;
+
+  // Per-thread cache of ltree_map_.
+  // (uses the same approach as TransactionLockMgr::lock_maps_cache_)
+  std::unique_ptr<ThreadLocalPtr> ltree_lookup_cache_;
+
+  RangeDeadlockInfoBuffer dlock_buffer_;
+
+  std::shared_ptr<toku::locktree> MakeLockTreePtr(toku::locktree* lt);
+  static int CompareDbtEndpoints(void* arg, const DBT* a_key, const DBT* b_key);
+
+  // Callbacks
+  static int on_create(toku::locktree*, void*);
+  static void on_destroy(toku::locktree*) {}
+  static void on_escalate(TXNID txnid, const toku::locktree* lt,
+                          const toku::range_buffer& buffer, void* extra);
+
+  static bool OnEscalationBarrierCheck(const DBT* a, const DBT* b, void* extra);
+};
+
+void serialize_endpoint(const Endpoint& endp, std::string* buf);
+void wait_callback_for_locktree(void* cdata, toku::lock_wait_infos* infos);
+
+}  // namespace ROCKSDB_NAMESPACE
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_tracker.cc b/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_tracker.cc
new file mode 100644
index 000000000..be1e1478b
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_tracker.cc
@@ -0,0 +1,156 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#ifndef ROCKSDB_LITE
+#ifndef OS_WIN
+
+#include "utilities/transactions/lock/range/range_tree/range_tree_lock_tracker.h"
+
+#include "utilities/transactions/lock/range/range_tree/range_tree_lock_manager.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+RangeLockList *RangeTreeLockTracker::getOrCreateList() {
+  if (range_list_) return range_list_.get();
+
+  // Doesn't exist, create
+  range_list_.reset(new RangeLockList());
+  return range_list_.get();
+}
+
+void RangeTreeLockTracker::Track(const PointLockRequest &lock_req) {
+  DBT key_dbt;
+  std::string key;
+  serialize_endpoint(Endpoint(lock_req.key, false), &key);
+  toku_fill_dbt(&key_dbt, key.data(), key.size());
+  RangeLockList *rl = getOrCreateList();
+  rl->Append(lock_req.column_family_id, &key_dbt, &key_dbt);
+}
+
+void RangeTreeLockTracker::Track(const RangeLockRequest &lock_req) {
+  DBT start_dbt, end_dbt;
+  std::string start_key, end_key;
+
+  serialize_endpoint(lock_req.start_endp, &start_key);
+  serialize_endpoint(lock_req.end_endp, &end_key);
+
+  toku_fill_dbt(&start_dbt, start_key.data(), start_key.size());
+  toku_fill_dbt(&end_dbt, end_key.data(), end_key.size());
+
+  RangeLockList *rl = getOrCreateList();
+  rl->Append(lock_req.column_family_id, &start_dbt, &end_dbt);
+}
+
+PointLockStatus RangeTreeLockTracker::GetPointLockStatus(
+    ColumnFamilyId /*cf_id*/, const std::string & /*key*/) const {
+  // This function is not expected to be called as RangeTreeLockTracker::
+  // IsPointLockSupported() returns false. Return the status which indicates
+  // the point is not locked.
+  PointLockStatus p;
+  p.locked = false;
+  p.exclusive = true;
+  p.seq = 0;
+  return p;
+}
+
+void RangeTreeLockTracker::Clear() { range_list_.reset(); }
+
+void RangeLockList::Append(ColumnFamilyId cf_id, const DBT *left_key,
+                           const DBT *right_key) {
+  MutexLock l(&mutex_);
+  // Only the transaction owner thread calls this function.
+  // The same thread does the lock release, so we can be certain nobody is
+  // releasing the locks concurrently.
+  assert(!releasing_locks_.load());
+  auto it = buffers_.find(cf_id);
+  if (it == buffers_.end()) {
+    // create a new one
+    it = buffers_.emplace(cf_id, std::make_shared<toku::range_buffer>()).first;
+    it->second->create();
+  }
+  it->second->append(left_key, right_key);
+}
+
+void RangeLockList::ReleaseLocks(RangeTreeLockManager *mgr,
+                                 PessimisticTransaction *txn,
+                                 bool all_trx_locks) {
+  {
+    MutexLock l(&mutex_);
+    // The lt->release_locks() call below will walk range_list->buffer_. We
+    // need to prevent lock escalation callback from replacing
+    // range_list->buffer_ while we are doing that.
+    //
+    // Additional complication here is internal mutex(es) in the locktree
+    // (let's call them latches):
+    // - Lock escalation first obtains latches on the lock tree
+    // - Then, it calls RangeTreeLockManager::on_escalate to replace
+    // transaction's range_list->buffer_. = Access to that buffer must be
+    // synchronized, so it will want to acquire the range_list->mutex_.
+    //
+    // While in this function we would want to do the reverse:
+    // - Acquire range_list->mutex_ to prevent access to the range_list.
+    // - Then, lt->release_locks() call will walk through the range_list
+    // - and acquire latches on parts of the lock tree to remove locks from
+    //   it.
+    //
+    // How do we avoid the deadlock? The idea is that here we set
+    // releasing_locks_=true, and release the mutex.
+    // All other users of the range_list must:
+    // - Acquire the mutex, then check that releasing_locks_=false.
+    //   (the code in this function doesnt do that as there's only one thread
+    //    that releases transaction's locks)
+    releasing_locks_.store(true);
+  }
+
+  for (auto it : buffers_) {
+    // Don't try to call release_locks() if the buffer is empty! if we are
+    //  not holding any locks, the lock tree might be in the STO-mode with
+    //  another transaction, and our attempt to release an empty set of locks
+    //  will cause an assertion failure.
+    if (it.second->get_num_ranges()) {
+      auto lt_ptr = mgr->GetLockTreeForCF(it.first);
+      toku::locktree *lt = lt_ptr.get();
+
+      lt->release_locks((TXNID)txn, it.second.get(), all_trx_locks);
+
+      it.second->destroy();
+      it.second->create();
+
+      toku::lock_request::retry_all_lock_requests(lt,
+                                                  wait_callback_for_locktree);
+    }
+  }
+
+  Clear();
+  releasing_locks_.store(false);
+}
+
+void RangeLockList::ReplaceLocks(const toku::locktree *lt,
+                                 const toku::range_buffer &buffer) {
+  MutexLock l(&mutex_);
+  if (releasing_locks_.load()) {
+    // Do nothing. The transaction is releasing its locks, so it will not care
+    // about having a correct list of ranges. (In TokuDB,
+    // toku_db_txn_escalate_callback() makes use of this property, too)
+    return;
+  }
+
+  ColumnFamilyId cf_id = (ColumnFamilyId)lt->get_dict_id().dictid;
+
+  auto it = buffers_.find(cf_id);
+  it->second->destroy();
+  it->second->create();
+
+  toku::range_buffer::iterator iter(&buffer);
+  toku::range_buffer::iterator::record rec;
+  while (iter.current(&rec)) {
+    it->second->append(rec.get_left_key(), rec.get_right_key());
+    iter.next();
+  }
+}
+
+}  // namespace ROCKSDB_NAMESPACE
+#endif  // OS_WIN
+#endif  // ROCKSDB_LITE
diff --git a/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_tracker.h b/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_tracker.h
new file mode 100644
index 000000000..4ef48d252
--- /dev/null
+++ b/src/rocksdb/utilities/transactions/lock/range/range_tree/range_tree_lock_tracker.h
@@ -0,0 +1,146 @@
+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+// This source code is licensed under both the GPLv2 (found in the
+// COPYING file in the root directory) and Apache 2.0 License
+// (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+
+#include "util/mutexlock.h"
+#include "utilities/transactions/lock/lock_tracker.h"
+#include "utilities/transactions/pessimistic_transaction.h"
+
+// Range Locking:
+#include "lib/locktree/lock_request.h"
+#include "lib/locktree/locktree.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class RangeTreeLockManager;
+
+// Storage for locks that are currently held by a transaction.
+//
+// Locks are kept in toku::range_buffer because toku::locktree::release_locks()
+// accepts that as an argument.
+//
+// Note: the list of locks may differ slighly from the contents of the lock
+// tree, due to concurrency between lock acquisition, lock release, and lock
+// escalation. See MDEV-18227 and RangeTreeLockManager::UnLock for details.
+// This property is currently harmless.
+//
+// Append() and ReleaseLocks() are not thread-safe, as they are expected to be
+// called only by the owner transaction. ReplaceLocks() is safe to call from
+// other threads.
+class RangeLockList {
+ public:
+  ~RangeLockList() { Clear(); }
+
+  RangeLockList() : releasing_locks_(false) {}
+
+  void Append(ColumnFamilyId cf_id, const DBT* left_key, const DBT* right_key);
+  void ReleaseLocks(RangeTreeLockManager* mgr, PessimisticTransaction* txn,
+                    bool all_trx_locks);
+  void ReplaceLocks(const toku::locktree* lt, const toku::range_buffer& buffer);
+
+ private:
+  void Clear() {
+    for (auto it : buffers_) {
+      it.second->destroy();
+    }
+    buffers_.clear();
+  }
+
+  std::unordered_map<ColumnFamilyId, std::shared_ptr<toku::range_buffer>>
+      buffers_;
+  port::Mutex mutex_;
+  std::atomic<bool> releasing_locks_;
+};
+
+// A LockTracker-based object that is used together with RangeTreeLockManager.
+class RangeTreeLockTracker : public LockTracker {
+ public:
+  RangeTreeLockTracker() : range_list_(nullptr) {}
+
+  RangeTreeLockTracker(const RangeTreeLockTracker&) = delete;
+  RangeTreeLockTracker& operator=(const RangeTreeLockTracker&) = delete;
+
+  void Track(const PointLockRequest&) override;
+  void Track(const RangeLockRequest&) override;
+
+  bool IsPointLockSupported() const override {
+    // This indicates that we don't implement GetPointLockStatus()
+    return false;
+  }
+  bool IsRangeLockSupported() const override { return true; }
+
+  // a Not-supported dummy implementation.
+  UntrackStatus Untrack(const RangeLockRequest& /*lock_request*/) override {
+    return UntrackStatus::NOT_TRACKED;
+  }
+
+  UntrackStatus Untrack(const PointLockRequest& /*lock_request*/) override {
+    return UntrackStatus::NOT_TRACKED;
+  }
+
+  // "If this method is not supported, leave it as a no-op."
+  void Merge(const LockTracker&) override {}
+
+  // "If this method is not supported, leave it as a no-op."
+  void Subtract(const LockTracker&) override {}
+
+  void Clear() override;
+
+  // "If this method is not supported, returns nullptr."
+  virtual LockTracker* GetTrackedLocksSinceSavePoint(
+      const LockTracker&) const override {
+    return nullptr;
+  }
+
+  PointLockStatus GetPointLockStatus(ColumnFamilyId column_family_id,
+                                     const std::string& key) const override;
+
+  // The return value is only used for tests
+  uint64_t GetNumPointLocks() const override { return 0; }
+
+  ColumnFamilyIterator* GetColumnFamilyIterator() const override {
+    return nullptr;
+  }
+
+  KeyIterator* GetKeyIterator(
+      ColumnFamilyId /*column_family_id*/) const override {
+    return nullptr;
+  }
+
+  void ReleaseLocks(RangeTreeLockManager* mgr, PessimisticTransaction* txn,
+                    bool all_trx_locks) {
+    if (range_list_) range_list_->ReleaseLocks(mgr, txn, all_trx_locks);
+  }
+
+  void ReplaceLocks(const toku::locktree* lt,
+                    const toku::range_buffer& buffer) {
+    // range_list_ cannot be NULL here
+    range_list_->ReplaceLocks(lt, buffer);
+  }
+
+ private:
+  RangeLockList* getOrCreateList();
+  std::unique_ptr<RangeLockList> range_list_;
+};
+
+class RangeTreeLockTrackerFactory : public LockTrackerFactory {
+ public:
+  static const RangeTreeLockTrackerFactory& Get() {
+    static const RangeTreeLockTrackerFactory instance;
+    return instance;
+  }
+
+  LockTracker* Create() const override { return new RangeTreeLockTracker(); }
+
+ private:
+  RangeTreeLockTrackerFactory() {}
+};
+
+}  // namespace ROCKSDB_NAMESPACE