Summary: Prototype of API to allow MyRocks to override default Mutex/CondVar used by transactions with their own implementations. They would simply need to pass their own implementations of Mutex/CondVar to the templated TransactionDB::Open(). Default implementation of TransactionDBMutex/TransactionDBCondVar provided (but the code is not currently changed to use this). Let me know if this API makes sense or if it should be changed Test Plan: n/a Reviewers: yhchiang, rven, igor, sdong, spetrunia Reviewed By: spetrunia Subscribers: maykov, dhruba, leveldb Differential Revision: https://reviews.facebook.net/D43761main
agiardullo
9 years ago
parent
0ccf2db385
commit
5e94f68f35
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// Copyright (c) 2015, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#pragma once |
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#ifndef ROCKSDB_LITE |
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#include <memory> |
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#include "rocksdb/status.h" |
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namespace rocksdb { |
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// TransactionDBMutex and TransactionDBCondVar APIs allows applications to
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// implement custom mutexes and condition variables to be used by a
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// TransactionDB when locking keys.
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//
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// To open a TransactionDB with a custom TransactionDBMutexFactory, set
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// TransactionDBOptions.custom_mutex_factory.
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class TransactionDBMutex { |
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public: |
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virtual ~TransactionDBMutex() {} |
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// Attempt to acquire lock. Return OK on success, or other Status on failure.
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// If returned status is OK, TransactionDB will eventually call UnLock().
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virtual Status Lock() = 0; |
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// Attempt to acquire lock. If timeout is non-negative, operation should be
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// failed after this many microseconds.
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// Returns OK on success,
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// TimedOut if timed out,
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// or other Status on failure.
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// If returned status is OK, TransactionDB will eventually call UnLock().
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virtual Status TryLockFor(int64_t timeout_time) = 0; |
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// Unlock Mutex that was successfully locked by Lock() or TryLockUntil()
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virtual void UnLock() = 0; |
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}; |
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class TransactionDBCondVar { |
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public: |
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virtual ~TransactionDBCondVar() {} |
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// Block current thread until condition variable is notified by a call to
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// Notify() or NotifyAll(). Wait() will be called with mutex locked.
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// Returns OK if notified.
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// Returns non-OK if TransactionDB should stop waiting and fail the operation.
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// May return OK spuriously even if not notified.
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virtual Status Wait(std::shared_ptr<TransactionDBMutex> mutex) = 0; |
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// Block current thread until condition variable is notified by a call to
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// Notify() or NotifyAll(), or if the timeout is reached.
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// Wait() will be called with mutex locked.
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//
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// If timeout is non-negative, operation should be failed after this many
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// microseconds.
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// If implementing a custom version of this class, the implementation may
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// choose to ignore the timeout.
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//
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// Returns OK if notified.
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// Returns TimedOut if timeout is reached.
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// Returns other status if TransactionDB should otherwis stop waiting and
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// fail the operation.
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// May return OK spuriously even if not notified.
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virtual Status WaitFor(std::shared_ptr<TransactionDBMutex> mutex, |
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int64_t timeout_time) = 0; |
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// If any threads are waiting on *this, unblock at least one of the
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// waiting threads.
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virtual void Notify() = 0; |
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// Unblocks all threads waiting on *this.
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virtual void NotifyAll() = 0; |
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}; |
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// Factory class that can allocate mutexes and condition variables.
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class TransactionDBMutexFactory { |
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public: |
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// Create a TransactionDBMutex object.
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virtual std::shared_ptr<TransactionDBMutex> AllocateMutex() = 0; |
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// Create a TransactionDBCondVar object.
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virtual std::shared_ptr<TransactionDBCondVar> AllocateCondVar() = 0; |
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virtual ~TransactionDBMutexFactory() {} |
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}; |
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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// Copyright (c) 2015, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#ifndef ROCKSDB_LITE |
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#include "utilities/transactions/transaction_db_mutex_impl.h" |
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#include <chrono> |
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#include <condition_variable> |
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#include <functional> |
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#include <mutex> |
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#include "rocksdb/utilities/transaction_db_mutex.h" |
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namespace rocksdb { |
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class TransactionDBMutexImpl : public TransactionDBMutex { |
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public: |
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TransactionDBMutexImpl() {} |
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~TransactionDBMutexImpl() {} |
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Status Lock() override; |
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Status TryLockFor(int64_t timeout_time) override; |
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void UnLock() override { mutex_.unlock(); } |
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friend class TransactionDBCondVarImpl; |
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private: |
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std::timed_mutex mutex_; |
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}; |
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class TransactionDBCondVarImpl : public TransactionDBCondVar { |
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public: |
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TransactionDBCondVarImpl() {} |
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~TransactionDBCondVarImpl() {} |
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Status Wait(std::shared_ptr<TransactionDBMutex> mutex) override; |
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Status WaitFor(std::shared_ptr<TransactionDBMutex> mutex, |
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int64_t timeout_time) override; |
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void Notify() override { cv_.notify_one(); } |
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void NotifyAll() override { cv_.notify_all(); } |
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private: |
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std::condition_variable_any cv_; |
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}; |
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std::shared_ptr<TransactionDBMutex> |
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TransactionDBMutexFactoryImpl::AllocateMutex() { |
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return std::shared_ptr<TransactionDBMutex>(new TransactionDBMutexImpl()); |
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} |
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std::shared_ptr<TransactionDBCondVar> |
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TransactionDBMutexFactoryImpl::AllocateCondVar() { |
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return std::shared_ptr<TransactionDBCondVar>(new TransactionDBCondVarImpl()); |
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} |
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Status TransactionDBMutexImpl::Lock() { |
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mutex_.lock(); |
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return Status::OK(); |
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} |
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Status TransactionDBMutexImpl::TryLockFor(int64_t timeout_time) { |
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bool locked = true; |
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if (timeout_time < 0) { |
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// If timeout is negative, we wait indefinitely to acquire the lock
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mutex_.lock(); |
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} else if (timeout_time == 0) { |
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locked = mutex_.try_lock(); |
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} else { |
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// Attempt to acquire the lock unless we timeout
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auto duration = std::chrono::microseconds(timeout_time); |
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locked = mutex_.try_lock_for(duration); |
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} |
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if (!locked) { |
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// timeout acquiring mutex
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return Status::TimedOut(Status::SubCode::kMutexTimeout); |
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} |
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return Status::OK(); |
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} |
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Status TransactionDBCondVarImpl::Wait( |
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std::shared_ptr<TransactionDBMutex> mutex) { |
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auto mutex_impl = reinterpret_cast<TransactionDBMutexImpl*>(mutex.get()); |
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cv_.wait(mutex_impl->mutex_); |
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return Status::OK(); |
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} |
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Status TransactionDBCondVarImpl::WaitFor( |
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std::shared_ptr<TransactionDBMutex> mutex, int64_t timeout_time) { |
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auto mutex_impl = reinterpret_cast<TransactionDBMutexImpl*>(mutex.get()); |
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if (timeout_time < 0) { |
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// If timeout is negative, do not use a timeout
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cv_.wait(mutex_impl->mutex_); |
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} else { |
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auto duration = std::chrono::microseconds(timeout_time); |
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auto cv_status = cv_.wait_for(mutex_impl->mutex_, duration); |
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// Check if the wait stopped due to timing out.
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if (cv_status == std::cv_status::timeout) { |
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return Status::TimedOut(Status::SubCode::kMutexTimeout); |
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} |
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} |
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// CV was signaled, or we spuriously woke up (but didn't time out)
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return Status::OK(); |
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} |
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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@ -0,0 +1,26 @@ |
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// Copyright (c) 2015, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#pragma once |
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#ifndef ROCKSDB_LITE |
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#include "rocksdb/utilities/transaction_db_mutex.h" |
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namespace rocksdb { |
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class TransactionDBMutex; |
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class TransactionDBCondVar; |
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// Default implementation of TransactionDBMutexFactory. May be overridden
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// by TransactionDBOptions.custom_mutex_factory.
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class TransactionDBMutexFactoryImpl : public TransactionDBMutexFactory { |
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public: |
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std::shared_ptr<TransactionDBMutex> AllocateMutex() override; |
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std::shared_ptr<TransactionDBCondVar> AllocateCondVar() override; |
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}; |
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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