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diff --git a/src/rocksdb/utilities/transactions/pessimistic_transaction.h b/src/rocksdb/utilities/transactions/pessimistic_transaction.h
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+++ b/src/rocksdb/utilities/transactions/pessimistic_transaction.h
@@ -0,0 +1,313 @@
+// 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 <algorithm>
+#include <atomic>
+#include <mutex>
+#include <stack>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "db/write_callback.h"
+#include "rocksdb/db.h"
+#include "rocksdb/slice.h"
+#include "rocksdb/snapshot.h"
+#include "rocksdb/status.h"
+#include "rocksdb/types.h"
+#include "rocksdb/utilities/transaction.h"
+#include "rocksdb/utilities/transaction_db.h"
+#include "rocksdb/utilities/write_batch_with_index.h"
+#include "util/autovector.h"
+#include "utilities/transactions/transaction_base.h"
+#include "utilities/transactions/transaction_util.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class PessimisticTransactionDB;
+
+// A transaction under pessimistic concurrency control. This class implements
+// the locking API and interfaces with the lock manager as well as the
+// pessimistic transactional db.
+class PessimisticTransaction : public TransactionBaseImpl {
+ public:
+  PessimisticTransaction(TransactionDB* db, const WriteOptions& write_options,
+                         const TransactionOptions& txn_options,
+                         const bool init = true);
+  // No copying allowed
+  PessimisticTransaction(const PessimisticTransaction&) = delete;
+  void operator=(const PessimisticTransaction&) = delete;
+
+  ~PessimisticTransaction() override;
+
+  void Reinitialize(TransactionDB* txn_db, const WriteOptions& write_options,
+                    const TransactionOptions& txn_options);
+
+  Status Prepare() override;
+
+  Status Commit() override;
+
+  // It is basically Commit without going through Prepare phase. The write batch
+  // is also directly provided instead of expecting txn to gradually batch the
+  // transactions writes to an internal write batch.
+  Status CommitBatch(WriteBatch* batch);
+
+  Status Rollback() override;
+
+  Status RollbackToSavePoint() override;
+
+  Status SetName(const TransactionName& name) override;
+
+  // Generate a new unique transaction identifier
+  static TransactionID GenTxnID();
+
+  TransactionID GetID() const override { return txn_id_; }
+
+  std::vector<TransactionID> GetWaitingTxns(uint32_t* column_family_id,
+                                            std::string* key) const override {
+    std::lock_guard<std::mutex> lock(wait_mutex_);
+    std::vector<TransactionID> ids(waiting_txn_ids_.size());
+    if (key) *key = waiting_key_ ? *waiting_key_ : "";
+    if (column_family_id) *column_family_id = waiting_cf_id_;
+    std::copy(waiting_txn_ids_.begin(), waiting_txn_ids_.end(), ids.begin());
+    return ids;
+  }
+
+  void SetWaitingTxn(autovector<TransactionID> ids, uint32_t column_family_id,
+                     const std::string* key) {
+    std::lock_guard<std::mutex> lock(wait_mutex_);
+    waiting_txn_ids_ = ids;
+    waiting_cf_id_ = column_family_id;
+    waiting_key_ = key;
+  }
+
+  void ClearWaitingTxn() {
+    std::lock_guard<std::mutex> lock(wait_mutex_);
+    waiting_txn_ids_.clear();
+    waiting_cf_id_ = 0;
+    waiting_key_ = nullptr;
+  }
+
+  // Returns the time (in microseconds according to Env->GetMicros())
+  // that this transaction will be expired.  Returns 0 if this transaction does
+  // not expire.
+  uint64_t GetExpirationTime() const { return expiration_time_; }
+
+  // returns true if this transaction has an expiration_time and has expired.
+  bool IsExpired() const;
+
+  // Returns the number of microseconds a transaction can wait on acquiring a
+  // lock or -1 if there is no timeout.
+  int64_t GetLockTimeout() const { return lock_timeout_; }
+  void SetLockTimeout(int64_t timeout) override {
+    lock_timeout_ = timeout * 1000;
+  }
+
+  // Returns true if locks were stolen successfully, false otherwise.
+  bool TryStealingLocks();
+
+  bool IsDeadlockDetect() const override { return deadlock_detect_; }
+
+  int64_t GetDeadlockDetectDepth() const { return deadlock_detect_depth_; }
+
+  virtual Status GetRangeLock(ColumnFamilyHandle* column_family,
+                              const Endpoint& start_key,
+                              const Endpoint& end_key) override;
+
+ protected:
+  // Refer to
+  // TransactionOptions::use_only_the_last_commit_time_batch_for_recovery
+  bool use_only_the_last_commit_time_batch_for_recovery_ = false;
+  // Refer to
+  // TransactionOptions::skip_prepare
+  bool skip_prepare_ = false;
+
+  virtual Status PrepareInternal() = 0;
+
+  virtual Status CommitWithoutPrepareInternal() = 0;
+
+  // batch_cnt if non-zero is the number of sub-batches. A sub-batch is a batch
+  // with no duplicate keys. If zero, then the number of sub-batches is unknown.
+  virtual Status CommitBatchInternal(WriteBatch* batch,
+                                     size_t batch_cnt = 0) = 0;
+
+  virtual Status CommitInternal() = 0;
+
+  virtual Status RollbackInternal() = 0;
+
+  virtual void Initialize(const TransactionOptions& txn_options);
+
+  Status LockBatch(WriteBatch* batch, LockTracker* keys_to_unlock);
+
+  Status TryLock(ColumnFamilyHandle* column_family, const Slice& key,
+                 bool read_only, bool exclusive, const bool do_validate = true,
+                 const bool assume_tracked = false) override;
+
+  void Clear() override;
+
+  PessimisticTransactionDB* txn_db_impl_;
+  DBImpl* db_impl_;
+
+  // If non-zero, this transaction should not be committed after this time (in
+  // microseconds according to Env->NowMicros())
+  uint64_t expiration_time_;
+
+  // Timestamp used by the transaction to perform all GetForUpdate.
+  // Use this timestamp for conflict checking.
+  // read_timestamp_ == kMaxTxnTimestamp means this transaction has not
+  // performed any GetForUpdate. It is possible that the transaction has
+  // performed blind writes or Get, though.
+  TxnTimestamp read_timestamp_{kMaxTxnTimestamp};
+  TxnTimestamp commit_timestamp_{kMaxTxnTimestamp};
+
+ private:
+  friend class TransactionTest_ValidateSnapshotTest_Test;
+  // Used to create unique ids for transactions.
+  static std::atomic<TransactionID> txn_id_counter_;
+
+  // Unique ID for this transaction
+  TransactionID txn_id_;
+
+  // IDs for the transactions that are blocking the current transaction.
+  //
+  // empty if current transaction is not waiting.
+  autovector<TransactionID> waiting_txn_ids_;
+
+  // The following two represents the (cf, key) that a transaction is waiting
+  // on.
+  //
+  // If waiting_key_ is not null, then the pointer should always point to
+  // a valid string object. The reason is that it is only non-null when the
+  // transaction is blocked in the PointLockManager::AcquireWithTimeout
+  // function. At that point, the key string object is one of the function
+  // parameters.
+  uint32_t waiting_cf_id_;
+  const std::string* waiting_key_;
+
+  // Mutex protecting waiting_txn_ids_, waiting_cf_id_ and waiting_key_.
+  mutable std::mutex wait_mutex_;
+
+  // Timeout in microseconds when locking a key or -1 if there is no timeout.
+  int64_t lock_timeout_;
+
+  // Whether to perform deadlock detection or not.
+  bool deadlock_detect_;
+
+  // Whether to perform deadlock detection or not.
+  int64_t deadlock_detect_depth_;
+
+  // Refer to TransactionOptions::skip_concurrency_control
+  bool skip_concurrency_control_;
+
+  virtual Status ValidateSnapshot(ColumnFamilyHandle* column_family,
+                                  const Slice& key,
+                                  SequenceNumber* tracked_at_seq);
+
+  void UnlockGetForUpdate(ColumnFamilyHandle* column_family,
+                          const Slice& key) override;
+};
+
+class WriteCommittedTxn : public PessimisticTransaction {
+ public:
+  WriteCommittedTxn(TransactionDB* db, const WriteOptions& write_options,
+                    const TransactionOptions& txn_options);
+  // No copying allowed
+  WriteCommittedTxn(const WriteCommittedTxn&) = delete;
+  void operator=(const WriteCommittedTxn&) = delete;
+
+  ~WriteCommittedTxn() override {}
+
+  using TransactionBaseImpl::GetForUpdate;
+  Status GetForUpdate(const ReadOptions& read_options,
+                      ColumnFamilyHandle* column_family, const Slice& key,
+                      std::string* value, bool exclusive,
+                      const bool do_validate) override;
+  Status GetForUpdate(const ReadOptions& read_options,
+                      ColumnFamilyHandle* column_family, const Slice& key,
+                      PinnableSlice* pinnable_val, bool exclusive,
+                      const bool do_validate) override;
+
+  using TransactionBaseImpl::Put;
+  // `key` does NOT include timestamp even when it's enabled.
+  Status Put(ColumnFamilyHandle* column_family, const Slice& key,
+             const Slice& value, const bool assume_tracked = false) override;
+  Status Put(ColumnFamilyHandle* column_family, const SliceParts& key,
+             const SliceParts& value,
+             const bool assume_tracked = false) override;
+
+  using TransactionBaseImpl::PutUntracked;
+  Status PutUntracked(ColumnFamilyHandle* column_family, const Slice& key,
+                      const Slice& value) override;
+  Status PutUntracked(ColumnFamilyHandle* column_family, const SliceParts& key,
+                      const SliceParts& value) override;
+
+  using TransactionBaseImpl::Delete;
+  // `key` does NOT include timestamp even when it's enabled.
+  Status Delete(ColumnFamilyHandle* column_family, const Slice& key,
+                const bool assume_tracked = false) override;
+  Status Delete(ColumnFamilyHandle* column_family, const SliceParts& key,
+                const bool assume_tracked = false) override;
+
+  using TransactionBaseImpl::DeleteUntracked;
+  Status DeleteUntracked(ColumnFamilyHandle* column_family,
+                         const Slice& key) override;
+  Status DeleteUntracked(ColumnFamilyHandle* column_family,
+                         const SliceParts& key) override;
+
+  using TransactionBaseImpl::SingleDelete;
+  // `key` does NOT include timestamp even when it's enabled.
+  Status SingleDelete(ColumnFamilyHandle* column_family, const Slice& key,
+                      const bool assume_tracked = false) override;
+  Status SingleDelete(ColumnFamilyHandle* column_family, const SliceParts& key,
+                      const bool assume_tracked = false) override;
+
+  using TransactionBaseImpl::SingleDeleteUntracked;
+  Status SingleDeleteUntracked(ColumnFamilyHandle* column_family,
+                               const Slice& key) override;
+
+  using TransactionBaseImpl::Merge;
+  Status Merge(ColumnFamilyHandle* column_family, const Slice& key,
+               const Slice& value, const bool assume_tracked = false) override;
+
+  Status SetReadTimestampForValidation(TxnTimestamp ts) override;
+  Status SetCommitTimestamp(TxnTimestamp ts) override;
+  TxnTimestamp GetCommitTimestamp() const override { return commit_timestamp_; }
+
+ private:
+  template <typename TValue>
+  Status GetForUpdateImpl(const ReadOptions& read_options,
+                          ColumnFamilyHandle* column_family, const Slice& key,
+                          TValue* value, bool exclusive,
+                          const bool do_validate);
+
+  template <typename TKey, typename TOperation>
+  Status Operate(ColumnFamilyHandle* column_family, const TKey& key,
+                 const bool do_validate, const bool assume_tracked,
+                 TOperation&& operation);
+
+  Status PrepareInternal() override;
+
+  Status CommitWithoutPrepareInternal() override;
+
+  Status CommitBatchInternal(WriteBatch* batch, size_t batch_cnt) override;
+
+  Status CommitInternal() override;
+
+  Status RollbackInternal() override;
+
+  // Column families that enable timestamps and whose data are written when
+  // indexing_enabled_ is false. If a key is written when indexing_enabled_ is
+  // true, then the corresponding column family is not added to cfs_with_ts
+  // even if it enables timestamp.
+  std::unordered_set<uint32_t> cfs_with_ts_tracked_when_indexing_disabled_;
+};
+
+}  // namespace ROCKSDB_NAMESPACE
+
+#endif  // ROCKSDB_LITE