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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 <memory>
#include <string>
#include "mongo/db/request_execution_context.h"
#include "mongo/util/concurrency/thread_pool.h"
#include "mongo/util/future.h"
namespace mongo {
/**
* The base class for constructing command-specific asynchronous executors.
* Requests (i.e., instances of `RequestExecutionContext`) are scheduled on a thread-pool, and
* passed to the command-specific implementation of `handleRequest`.
*/
class AsyncRequestExecutor {
public:
AsyncRequestExecutor(AsyncRequestExecutor&&) = delete;
AsyncRequestExecutor(const AsyncRequestExecutor&) = delete;
explicit AsyncRequestExecutor(std::string name);
/**
* Wrap the startup and shutdown interfaces provided by `_pool` and delegate the concurrency
* control to corresponding member functions of `ThreadPool`.
*/
void start();
void stop();
/**
* Runs the command-specific code to handle the request.
* Must only access the request on the corresponding client thread.
*/
virtual Status handleRequest(std::shared_ptr<RequestExecutionContext>) = 0;
/**
* Schedules the request on a thread pool (i.e., `_pool`) and calls into `handleRequest` to
* asynchronously execute the command. Note that the scheduled tasks run inline during shutdown.
*/
Future<void> schedule(std::shared_ptr<RequestExecutionContext> rec);
static constexpr auto kDiagnosticLogLevel = 4;
private:
const std::string _name;
std::unique_ptr<ThreadPool> _pool;
};
} // namespace mongo
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