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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 <functional>
#include "mongo/db/repl/optime.h"
#include "mongo/platform/mutex.h"
#include "mongo/util/time_support.h"
namespace mongo {
namespace repl {
/**
* Once scheduled, the NoopWriter will periodically write a noop to the oplog if the replication
* coordinator's optime has not changed since the last time it did a write.
*/
class NoopWriter {
NoopWriter(const NoopWriter&) = delete;
NoopWriter& operator=(const NoopWriter&) = delete;
public:
NoopWriter(Seconds waitTime);
~NoopWriter();
Status startWritingPeriodicNoops(OpTime lastKnownOpTime);
void stopWritingPeriodicNoops();
private:
class PeriodicNoopRunner;
void _writeNoop(OperationContext*);
/**
* NoopWriter will write a noop to the oplog every _writeInterval seconds.
*/
const Seconds _writeInterval;
/**
* The last optime that has been seen by the noop writer.
*/
OpTime _lastKnownOpTime;
/**
* Protects member data of this class during start and stop. There is no need to synchronize
* access once its running because its run by a one thread only.
*/
mutable Mutex _mutex = MONGO_MAKE_LATCH("NoopWriter::_mutex");
std::unique_ptr<PeriodicNoopRunner> _noopRunner;
};
} // namespace repl
} // namespace mongo
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