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/**
* Copyright (C) 2015 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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 <memory>
#include <string>
#include <utility>
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/base/status.h"
#include "mongo/base/status_with.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/repl/replication_executor.h"
#include "mongo/stdx/condition_variable.h"
#include "mongo/stdx/functional.h"
#include "mongo/stdx/mutex.h"
namespace mongo {
namespace repl {
class Applier {
MONGO_DISALLOW_COPYING(Applier);
public:
/**
* Operations sorted by timestamp in ascending order.
*/
using Operations = std::vector<BSONObj>;
/**
* Callback function to report final status of applying operations along with
* list of operations (if applicable) that were not successfully applied.
* On success, returns the timestamp of the last operation applied together with an empty
* list of operations.
*/
using CallbackFn = stdx::function<void(const StatusWith<Timestamp>&, const Operations&)>;
/**
* Type of function to to apply a single operation. In production, this function
* would have the same outcome as calling SyncTail::syncApply() ('convertUpdatesToUpserts'
* value will be embedded in the function implementation).
*/
using ApplyOperationFn = stdx::function<Status(OperationContext*, const BSONObj&)>;
/**
* Creates Applier in inactive state.
*
* Accepts list of oplog entries to apply in 'operations'.
*
* The callback function will be invoked (after schedule()) when the applied has
* successfully applied all the operations or encountered a failure. Failures may occur if
* we failed to apply an operation; or if the underlying scheduled work item
* on the replication executor was canceled.
*
* It is an error for 'operations' to be empty but individual oplog entries
* contained in 'operations' are not validated.
*/
Applier(ReplicationExecutor* executor,
const Operations& operations,
const ApplyOperationFn& applyOperation,
const CallbackFn& onCompletion);
/**
* Blocks while applier is active.
*/
virtual ~Applier();
/**
* Returns diagnostic information.
*/
std::string getDiagnosticString() const;
/**
* Returns true if the applier has been started (but has not completed).
*/
bool isActive() const;
/**
* Starts applier by scheduling initial db work to be run by the executor.
*/
Status start();
/**
* Cancels current db work request.
* Returns immediately if applier is not active.
*
* Callback function may be invoked with an ErrorCodes::CallbackCanceled status.
*/
void cancel();
/**
* Waits for active database worker to complete.
* Returns immediately if applier is not active.
*/
void wait();
private:
/**
* DB worker callback function - applies all operations.
*/
void _callback(const ReplicationExecutor::CallbackArgs& cbd);
void _finishCallback(const StatusWith<Timestamp>& result, const Operations& operations);
// Not owned by us.
ReplicationExecutor* _executor;
Operations _operations;
ApplyOperationFn _applyOperation;
CallbackFn _onCompletion;
// Protects member data of this Applier.
mutable stdx::mutex _mutex;
stdx::condition_variable _condition;
// _active is true when Applier is scheduled to be run by the executor.
bool _active;
ReplicationExecutor::CallbackHandle _dbWorkCallbackHandle;
};
/**
* Applies operations (sorted by timestamp) up to and including 'lastTimestampToApply'.
* If 'lastTimestampToApply' is found in 'operations':
* - The applier will be given a subset of 'operations' (includes 'lastTimestampToApply').
* - On success, the applier will invoke the 'pause' function just before reporting
* completion status.
* Otherwise, all entries in 'operations' before 'lastTimestampToApply' will be forwarded to
* the applier and the 'pause' function will be ignored.
* If the applier is successfully created, returns the applier and a list of operations that
* are skipped (operations with 'ts' field value after 'lastTimestampToApply).
*/
using PauseDataReplicatorFn = stdx::function<void()>;
StatusWith<std::pair<std::unique_ptr<Applier>, Applier::Operations>> applyUntilAndPause(
ReplicationExecutor* executor,
const Applier::Operations& operations,
const Applier::ApplyOperationFn& applyOperation,
const Timestamp& lastTimestampToApply,
const PauseDataReplicatorFn& pauseDataReplicator,
const Applier::CallbackFn& onCompletion);
} // namespace repl
} // namespace mongo
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