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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 <chrono>
#include <string>
#include <unordered_map>
#include <memory>
#include <utility>
#include <vector>
#include "monitoring/instrumented_mutex.h"
#include "rocksdb/utilities/transaction.h"
#include "util/autovector.h"
#include "util/hash_map.h"
#include "util/thread_local.h"
#include "utilities/transactions/pessimistic_transaction.h"
namespace ROCKSDB_NAMESPACE {
class ColumnFamilyHandle;
struct LockInfo;
struct LockMap;
struct LockMapStripe;
struct DeadlockInfoBuffer {
private:
std::vector<DeadlockPath> paths_buffer_;
uint32_t buffer_idx_;
std::mutex paths_buffer_mutex_;
std::vector<DeadlockPath> Normalize();
public:
explicit DeadlockInfoBuffer(uint32_t n_latest_dlocks)
: paths_buffer_(n_latest_dlocks), buffer_idx_(0) {}
void AddNewPath(DeadlockPath path);
void Resize(uint32_t target_size);
std::vector<DeadlockPath> PrepareBuffer();
};
struct TrackedTrxInfo {
autovector<TransactionID> m_neighbors;
uint32_t m_cf_id;
bool m_exclusive;
std::string m_waiting_key;
};
class Slice;
class PessimisticTransactionDB;
class TransactionLockMgr {
public:
TransactionLockMgr(TransactionDB* txn_db, size_t default_num_stripes,
int64_t max_num_locks, uint32_t max_num_deadlocks,
std::shared_ptr<TransactionDBMutexFactory> factory);
// No copying allowed
TransactionLockMgr(const TransactionLockMgr&) = delete;
void operator=(const TransactionLockMgr&) = delete;
~TransactionLockMgr();
// Creates a new LockMap for this column family. Caller should guarantee
// that this column family does not already exist.
void AddColumnFamily(uint32_t column_family_id);
// Deletes the LockMap for this column family. Caller should guarantee that
// this column family is no longer in use.
void RemoveColumnFamily(uint32_t column_family_id);
// Attempt to lock key. If OK status is returned, the caller is responsible
// for calling UnLock() on this key.
Status TryLock(PessimisticTransaction* txn, uint32_t column_family_id,
const std::string& key, Env* env, bool exclusive);
// Unlock a key locked by TryLock(). txn must be the same Transaction that
// locked this key.
void UnLock(const PessimisticTransaction* txn, const TransactionKeyMap* keys,
Env* env);
void UnLock(PessimisticTransaction* txn, uint32_t column_family_id,
const std::string& key, Env* env);
using LockStatusData = std::unordered_multimap<uint32_t, KeyLockInfo>;
LockStatusData GetLockStatusData();
std::vector<DeadlockPath> GetDeadlockInfoBuffer();
void Resize(uint32_t);
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 = std::unordered_map<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,
LockInfo&& lock_info);
Status AcquireLocked(LockMap* lock_map, LockMapStripe* stripe,
const std::string& key, Env* env,
LockInfo&& lock_info, uint64_t* wait_time,
autovector<TransactionID>* txn_ids);
void UnLockKey(const 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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