5、可暂停的线程控制模型

一、需求

在做播放器的时候，很多的模块会创建一个线程，然后在这个线程上跑单独的功能，同时，需要对这个线程进行控制，比如暂停，继续等，如播放器的解码，解封装等，都需要对对应的线程进行控制，那么为了方便的进行控制，所以引入单独的thread封装，并且导出对应的回调接口。

二、实现

1. com_thread.h

#pragma once#include <thread>
#include <atomic>class IThreadSink
{
public:virtual ~IThreadSink() {}virtual void onThreadCreate() = 0;virtual void onThreadDestroy() = 0;virtual void onThreadRun() = 0;virtual void onThreadPause() = 0;virtual void onThreadTask() = 0;
};class IThread
{typedef enum{STAT_WAIT,STAT_RUN,STAT_PAUSE,STAT_QUIT}ThreadStat;public:virtual ~IThread() {}IThread(IThreadSink* _sink);void threadCreate();void threadDestroy();void run();void pause();
private:std::atomic<int> _stat_cur;std::atomic<int> _stat_set;std::thread _thread;IThreadSink* _sink;bool _is_init;void _threadTaskInternal();void _setStat(ThreadStat stat);
};

2. com_thread.c

#include "com_thread.h"IThread::IThread(IThreadSink* sink):_stat_cur(STAT_WAIT),_stat_set(STAT_WAIT),_sink(NULL),_is_init(false)
{_sink = static_cast<IThreadSink*>(sink);
}void IThread::threadCreate()
{if (_is_init){return;}_thread = std::thread(&IThread::_threadTaskInternal, this);_is_init = true;
}
void IThread::threadDestroy()
{if (!_is_init){return;}_setStat(STAT_QUIT);_thread.join();_is_init = false;
}
void IThread::run()
{if (!_is_init){return;}if (_stat_cur == STAT_WAIT || _stat_cur == STAT_PAUSE){_setStat(STAT_RUN);if (_sink){_sink->onThreadRun();}}
}
void IThread::pause()
{if (!_is_init){return;}if (_stat_cur == STAT_RUN){_setStat(STAT_PAUSE);if (_sink){_sink->onThreadPause();}}
}void IThread::_threadTaskInternal()
{if (_sink){_sink->onThreadCreate();}while (1){if ((_stat_cur == STAT_WAIT || _stat_cur == STAT_PAUSE) && _stat_cur == _stat_set){std::this_thread::sleep_for(std::chrono::milliseconds(1));continue;}if (_stat_cur != _stat_set){_stat_cur = _stat_set.load();}if (STAT_QUIT == _stat_cur){break;}if (STAT_WAIT == _stat_cur || STAT_PAUSE == _stat_cur){continue;}if (STAT_RUN == _stat_cur){_sink->onThreadTask();}}if (_sink){_sink->onThreadDestroy();}
}
void IThread::_setStat(ThreadStat stat)
{_stat_set = stat;while (_stat_cur == stat){std::this_thread::sleep_for(std::chrono::milliseconds(1));}
}

3. demo.cpp

#include <iostream>
#include "com_thread.h"class ThreadTestDemo :public IThreadSink
{
public:virtual void onThreadCreate() override{std::cout << "Create" << std::endl;}virtual void onThreadDestroy() override{std::cout << "Destroy" << std::endl;}virtual void onThreadRun() override{std::cout << "Run" << std::endl;}virtual void onThreadPause() override{std::cout << "Pause" << std::endl;}virtual void onThreadTask() override{std::this_thread::sleep_for(std::chrono::milliseconds(100));std::cout << "do task!!!" << std::endl;}void test(){IThread* _thread = new IThread(this);_thread->threadCreate();std::this_thread::sleep_for(std::chrono::milliseconds(1000));for (int i = 0; i < 3; i++){_thread->run();std::this_thread::sleep_for(std::chrono::milliseconds(1000));_thread->pause();std::this_thread::sleep_for(std::chrono::milliseconds(2000));}_thread->threadDestroy();delete _thread;}
};