ThreadManager.h

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/* Copyright 2013-2019 Homegear GmbH
 *
 * libhomegear-base is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * libhomegear-base 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 Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with libhomegear-base.  If not, see
 * <http://www.gnu.org/licenses/>.
 * 
 * In addition, 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 two.
 * You must obey the GNU Lesser General Public License in all respects
 * for all of the code used other than OpenSSL.  If you modify
 * file(s) with this exception, you may extend this exception to your
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*/

#ifndef THREADS_H_
#define THREADS_H_

#include "../Exception.h"
#include "../Output/Output.h"
#include <mutex>
#include <thread>

namespace BaseLib
{

class SharedObjects;

class ThreadManager
{
public:
    ThreadManager();
    virtual ~ThreadManager();
    void init(BaseLib::SharedObjects* baseLib, bool testMaxThreadCount);

    static int32_t getThreadPolicyFromString(std::string policy);
    static int32_t parseThreadPriority(int32_t priority, int32_t policy);
    void setThreadPriority(pthread_t thread, int32_t priority, int32_t policy = SCHED_FIFO);

    template<typename Function, typename... Args>
    bool start(std::thread& thread, bool highPriority, Function&& function, Args&&... args)
    {
        if(!checkThreadCount(highPriority)) return false;
        join(thread);
        thread = std::thread(function, args...);
        registerThread();
        return true;
    }

    template<typename Function, typename... Args>
    bool start(std::thread& thread, bool highPriority, int32_t priority, int32_t policy, Function&& function, Args&&... args)
    {
        if(!checkThreadCount(highPriority)) return false;
        join(thread);
        thread = std::thread(function, args...);
        setThreadPriority(thread.native_handle(), priority, policy);
        registerThread();
        return true;
    }

    void join(std::thread& thread);

    void registerThread();
    void unregisterThread();
    void setMaxThreadCount(uint32_t value);
    uint32_t getMaxThreadCount();
    int32_t getCurrentThreadCount();
    uint32_t getMaxRegisteredThreadCount();
    void testMaxThreadCount();
protected:
    SharedObjects* _bl = nullptr;
    std::mutex _threadCountMutex;
    uint32_t _maxRegisteredThreadCount = 0;
    uint32_t _maxThreadCount = 0;
    volatile int32_t _currentThreadCount = 0;

    bool checkThreadCount(bool highPriority);
private:
    ThreadManager(const ThreadManager&) = delete;
    ThreadManager& operator=(const ThreadManager&) = delete;
};

}
#endif