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/**
* Copyright (C) 2020-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 "mongo/platform/mutex.h"
#include "mongo/stdx/condition_variable.h"
#include "mongo/util/background.h"
namespace mongo {
class KVEngine;
class OperationContext;
class ServiceContext;
class Timestamp;
class Checkpointer : public BackgroundJob {
public:
Checkpointer()
: BackgroundJob(false /* deleteSelf */),
_shuttingDown(false),
_shutdownReason(Status::OK()),
_hasTriggeredFirstStableCheckpoint(false),
_triggerCheckpoint(false) {}
static Checkpointer* get(ServiceContext* serviceCtx);
static Checkpointer* get(OperationContext* opCtx);
static void set(ServiceContext* serviceCtx, std::unique_ptr<Checkpointer> newCheckpointer);
std::string name() const override {
return "Checkpointer";
}
/**
* Starts the checkpoint thread that runs every storageGlobalParams.syncdelay seconds.
*/
void run() override;
/**
* Triggers taking the first stable checkpoint if the stable timestamp has advanced past the
* initial data timestamp.
*
* The checkpoint thread runs automatically every storageGlobalParams.syncdelay seconds. This
* function avoids potentially waiting that full duration for a stable checkpoint, initiating
* one immediately.
*
* Do not call this function if hasTriggeredFirstStableCheckpoint() returns true.
*/
void triggerFirstStableCheckpoint(Timestamp prevStable,
Timestamp initialData,
Timestamp currStable);
/**
* Returns whether the first stable checkpoint has already been triggered.
*/
bool hasTriggeredFirstStableCheckpoint();
/**
* Blocks until the checkpoint thread has been fully shutdown.
*/
void shutdown(const Status& reason);
private:
// Protects the state below.
Mutex _mutex = MONGO_MAKE_LATCH("Checkpointer::_mutex");
// The checkpoint thread idles on this condition variable for a particular time duration between
// taking checkpoints. It can be triggered early to expedite either: immediate checkpointing if
// _triggerCheckpoint is set; or shutdown cleanup if _shuttingDown is set.
stdx::condition_variable _sleepCV;
bool _shuttingDown;
Status _shutdownReason;
// This flag ensures the first stable checkpoint is only triggered once.
bool _hasTriggeredFirstStableCheckpoint;
// This flag allows the checkpoint thread to wake up early when _sleepCV is signaled.
bool _triggerCheckpoint;
};
} // namespace mongo
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