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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 <iosfwd>
#include <memory>
#include <string>
#include <utility>
#include <vector>
#include "mongo/base/status.h"
#include "mongo/base/status_with.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/multi_key_path_tracker.h"
#include "mongo/db/repl/oplog_entry.h"
#include "mongo/db/service_context.h"
#include "mongo/executor/task_executor.h"
#include "mongo/platform/mutex.h"
#include "mongo/stdx/condition_variable.h"
namespace mongo {
namespace repl {
class OpTime;
class MultiApplier {
MultiApplier(const MultiApplier&) = delete;
MultiApplier& operator=(const MultiApplier&) = delete;
public:
/**
* Callback function to report final status of applying operations.
*/
using CallbackFn = unique_function<void(const Status&)>;
using MultiApplyFn =
std::function<StatusWith<OpTime>(OperationContext*, std::vector<OplogEntry>)>;
/**
* Creates MultiApplier 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.
*/
MultiApplier(executor::TaskExecutor* executor,
const std::vector<OplogEntry>& operations,
const MultiApplyFn& multiApply,
CallbackFn onCompletion);
/**
* Blocks while applier is active.
*/
virtual ~MultiApplier();
/**
* 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 startup() noexcept;
/**
* Cancels current db work request.
* Returns immediately if applier is not active.
*
* Callback function may be invoked with an ErrorCodes::CallbackCanceled status.
*/
void shutdown();
/**
* Waits for active database worker to complete.
* Returns immediately if applier is not active.
*/
void join();
// State transitions:
// PreStart --> Running --> ShuttingDown --> Complete
// It is possible to skip intermediate states. For example,
// Calling shutdown() when the cloner has not started will transition from PreStart directly
// to Complete.
// This enum class is made public for testing.
enum class State { kPreStart, kRunning, kShuttingDown, kComplete };
/**
* Returns current MultiApplier state.
* For testing only.
*/
State getState_forTest() const;
private:
bool _isActive_inlock() const;
/**
* DB worker callback function - applies all operations.
*/
void _callback(const executor::TaskExecutor::CallbackArgs& cbd);
void _finishCallback(const Status& result);
// Not owned by us.
executor::TaskExecutor* _executor;
std::vector<OplogEntry> _operations;
MultiApplyFn _multiApply;
CallbackFn _onCompletion;
// Protects member data of this MultiApplier.
mutable Mutex _mutex = MONGO_MAKE_LATCH("MultiApplier::_mutex");
stdx::condition_variable _condition;
// Current multi applier state. See comments for State enum class for details.
State _state = State::kPreStart;
executor::TaskExecutor::CallbackHandle _dbWorkCallbackHandle;
};
/**
* Insertion operator for MultiApplier::State. Formats fetcher state for output stream.
* For testing only.
*/
std::ostream& operator<<(std::ostream& os, const MultiApplier::State& state);
} // namespace repl
} // namespace mongo
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