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// 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
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