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/**
* Copyright (C) 2019-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/base/status.h"
#include "mongo/executor/task_executor.h"
#include "mongo/stdx/condition_variable.h"
#include "mongo/stdx/mutex.h"
#include "mongo/stdx/unordered_map.h"
#include "mongo/util/fail_point_service.h"
namespace mongo {
class OperationContext;
namespace executor {
/**
* Implements a scoped task executor which collects all callback handles it receives as part of
* running operations and cancels any outstanding ones on destruction.
*
* The intent is that you can use this type with arbitrary task executor taking functions and allow
* this object's destruction to clean up any methods which returned callback handles.
*
* Note that while this type provides access to a TaskExecutor*, certain methods are illegal to
* call:
* - startup()
* - appendDiagnosticBSON()
* - appendConnectionStats()
*
* And certain other methods only pass through this class to the underlying executor:
* - makeEvent()
* will return a not-ok status after shutdown, but does not otherwise instrument the event
* - signalEvent()
* always signals
* - waitForEvent()
* always waits for the event
* - cancel()
* always cancels the task
* - wait()
* always waits for the task
* - now()
* always returns the time
*
* This leaves the various callback handle returning methods + join/shutdown. These methods, rather
* than performing a passthrough, address only tasks dispatched through this executor, rather than
* passing through to the underlying executor.
*
* Also note that this type DOES NOT call join in its dtor. I.e. all tasks are cancelled, but all
* callbacks may not have run when this object goes away. You must call join() if you want that
* guarantee.
*/
class ScopedTaskExecutor {
public:
explicit ScopedTaskExecutor(std::shared_ptr<TaskExecutor> executor);
// Delete all move/copy-ability
ScopedTaskExecutor(TaskExecutor&&) = delete;
~ScopedTaskExecutor();
operator TaskExecutor*() const {
return _executor.get();
}
const std::shared_ptr<TaskExecutor>& operator*() const {
return _executor;
}
TaskExecutor* operator->() const {
return _executor.get();
}
private:
class Impl;
std::shared_ptr<TaskExecutor> _executor;
};
extern FailPoint ScopedTaskExecutorHangBeforeSchedule;
extern FailPoint ScopedTaskExecutorHangExitBeforeSchedule;
extern FailPoint ScopedTaskExecutorHangAfterSchedule;
} // namespace executor
} // namespace mongo
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