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rocksdb/include/rocksdb/utilities/transaction_db_mutex.h

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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 "rocksdb/status.h"
namespace rocksdb {
// TransactionDBMutex and TransactionDBCondVar APIs allows applications to
// implement custom mutexes and condition variables to be used by a
// TransactionDB when locking keys.
//
// To open a TransactionDB with a custom TransactionDBMutexFactory, set
// TransactionDBOptions.custom_mutex_factory.
class TransactionDBMutex {
public:
virtual ~TransactionDBMutex() {}
// Attempt to acquire lock. Return OK on success, or other Status on failure.
// If returned status is OK, TransactionDB will eventually call UnLock().
virtual Status Lock() = 0;
// Attempt to acquire lock. If timeout is non-negative, operation may be
// failed after this many microseconds.
// Returns OK on success,
// TimedOut if timed out,
// or other Status on failure.
// If returned status is OK, TransactionDB will eventually call UnLock().
virtual Status TryLockFor(int64_t timeout_time) = 0;
// Unlock Mutex that was successfully locked by Lock() or TryLockUntil()
virtual void UnLock() = 0;
};
class TransactionDBCondVar {
public:
virtual ~TransactionDBCondVar() {}
// Block current thread until condition variable is notified by a call to
// Notify() or NotifyAll(). Wait() will be called with mutex locked.
// Returns OK if notified.
// Returns non-OK if TransactionDB should stop waiting and fail the operation.
// May return OK spuriously even if not notified.
virtual Status Wait(std::shared_ptr<TransactionDBMutex> mutex) = 0;
// Block current thread until condition variable is notified by a call to
// Notify() or NotifyAll(), or if the timeout is reached.
// Wait() will be called with mutex locked.
//
// If timeout is non-negative, operation should be failed after this many
// microseconds.
// If implementing a custom version of this class, the implementation may
// choose to ignore the timeout.
//
// Returns OK if notified.
// Returns TimedOut if timeout is reached.
// Returns other status if TransactionDB should otherwis stop waiting and
// fail the operation.
// May return OK spuriously even if not notified.
virtual Status WaitFor(std::shared_ptr<TransactionDBMutex> mutex,
int64_t timeout_time) = 0;
// If any threads are waiting on *this, unblock at least one of the
// waiting threads.
virtual void Notify() = 0;
// Unblocks all threads waiting on *this.
virtual void NotifyAll() = 0;
};
// Factory class that can allocate mutexes and condition variables.
class TransactionDBMutexFactory {
public:
// Create a TransactionDBMutex object.
virtual std::shared_ptr<TransactionDBMutex> AllocateMutex() = 0;
// Create a TransactionDBCondVar object.
virtual std::shared_ptr<TransactionDBCondVar> AllocateCondVar() = 0;
virtual ~TransactionDBMutexFactory() {}
};
} // namespace rocksdb
#endif // ROCKSDB_LITE