io_service_thread_pool.h

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// Copyright (C) 2022 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
#ifndef IOSERVICE_THREAD_POOL_H
#define IOSERVICE_THREAD_POOL_H
 
#include <asiolink/io_service.h>
#include <util/unlock_guard.h>
 
#include <boost/shared_ptr.hpp>
 
#include <condition_variable>
#include <list>
#include <mutex>
#include <thread>
 
namespace isc {
namespace asiolink {
 
class IoServiceThreadPool {
public:
    enum class State {
        STOPPED,    
        RUNNING,    
        PAUSED,     
    };
 
    IoServiceThreadPool(asiolink::IOServicePtr io_service, size_t pool_size,
                   bool defer_start = false);
 
    ~IoServiceThreadPool();
 
    void run();
 
    void pause();
 
    void stop();
 
    bool isRunning() {
        return (getState() == State::RUNNING);
    }
 
    bool isPaused() {
        return (getState() == State::PAUSED);
    }
 
    bool isStopped() {
        return (getState() == State::STOPPED);
    }
 
    void checkPausePermissions();
 
private:
    void checkPermissions(State state);
 
    bool checkThreadId(std::thread::id id);
 
    void setState(State state);
 
    State getState();
 
    bool validateStateChange(State state) const;
 
    static std::string stateToText(State state);
 
    void threadWork();
 
public:
    asiolink::IOServicePtr getIOService() const;
 
    uint16_t getPoolSize() const;
 
    uint16_t getThreadCount() const;
 
private:
    size_t pool_size_;
 
    asiolink::IOServicePtr io_service_;
 
    State run_state_;
 
    std::mutex mutex_;
 
    std::condition_variable thread_cv_;
 
    std::condition_variable main_cv_;
 
    size_t paused_;
 
    size_t running_;
 
    size_t exited_;
 
    std::list<boost::shared_ptr<std::thread> > threads_;
};
 
typedef boost::shared_ptr<IoServiceThreadPool> IoServiceThreadPoolPtr;
 
} // end of namespace isc::asiolink
} // end of namespace isc
 
#endif