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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <boost/optional.hpp>
#include <memory>
#include "mongo/db/repl/oplog_buffer.h"
#include "mongo/platform/mutex.h"
namespace mongo {
namespace repl {
class StorageInterface;
/**
* Oplog buffer proxy that caches front and back (most recently pushed) oplog entries in the target
* oplog buffer.
*/
class OplogBufferProxy : public OplogBuffer {
OplogBufferProxy(const OplogBufferProxy&) = delete;
OplogBufferProxy& operator=(const OplogBufferProxy&) = delete;
public:
explicit OplogBufferProxy(std::unique_ptr<OplogBuffer> target);
/**
* Returns target oplog buffer.
*/
OplogBuffer* getTarget() const;
void startup(OperationContext* opCtx) override;
void shutdown(OperationContext* opCtx) override;
void push(OperationContext* opCtx,
Batch::const_iterator begin,
Batch::const_iterator end) override;
void waitForSpace(OperationContext* opCtx, std::size_t size) override;
bool isEmpty() const override;
std::size_t getMaxSize() const override;
std::size_t getSize() const override;
std::size_t getCount() const override;
void clear(OperationContext* opCtx) override;
bool tryPop(OperationContext* opCtx, Value* value) override;
bool waitForDataFor(Milliseconds waitDuration, Interruptible* interruptible) override;
bool waitForDataUntil(Date_t deadline, Interruptible* interruptible) override;
bool peek(OperationContext* opCtx, Value* value) override;
boost::optional<Value> lastObjectPushed(OperationContext* opCtx) const override;
// ---- Testing API ----
boost::optional<Value> getLastPeeked_forTest() const;
private:
// Target oplog buffer. Owned by us.
std::unique_ptr<OplogBuffer> _target;
// If both mutexes have to be acquired, acquire _lastPushedMutex first.
mutable Mutex _lastPushedMutex = MONGO_MAKE_LATCH("OplogBufferProxy::_lastPushedMutex");
boost::optional<Value> _lastPushed;
mutable Mutex _lastPeekedMutex = MONGO_MAKE_LATCH("OplogBufferProxy::_lastPeekedMutex");
boost::optional<Value> _lastPeeked;
};
} // namespace repl
} // namespace mongo
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