C++11中std::thread线程实现暂停(挂起)功能
作者:百里杨
本文主要介绍了C++11中std::thread线程实现暂停(挂起)功能,文中通过示例代码介绍的非常详细,对大家的学习或者工作具有一定的参考学习价值,需要的朋友们下面随着小编来一起学习学习吧
一、封装Thread类
我们基于C++11中与平台无关的线程类std::thread,封装Thread类,并提供start()、stop()、pause()、resume()线程控制方法。
为了让线程在暂停期间,处于休眠,不消耗CPU,我们使用C++11提供的锁和条件变量来实现。
- std::mutex
- std::condition_variable
Thread.h
#ifndef THREAD_H #define THREAD_H #include <thread> #include <atomic> #include <mutex> #include <condition_variable> class Thread { public: Thread(); virtual ~Thread(); enum State { Stoped, ///<停止状态,包括从未启动过和启动后被停止 Running, ///<运行状态 Paused ///<暂停状态 }; State state() const; void start(); void stop(); void pause(); void resume(); protected: virtual void process() = 0; private: void run(); private: std::thread* _thread; std::mutex _mutex; std::condition_variable _condition; std::atomic_bool _pauseFlag; ///<暂停标识 std::atomic_bool _stopFlag; ///<停止标识 State _state; }; #endif // THREAD_H
Thread.cpp
#include "Thread.h" #include <iostream> using namespace std; Thread::Thread() : _thread(nullptr), _pauseFlag(false), _stopFlag(false), _state(Stoped) { } Thread::~Thread() { stop(); } Thread::State Thread::state() const { return _state; } void Thread::start() { if (_thread == nullptr) { _thread = new thread(&Thread::run, this); _pauseFlag = false; _stopFlag = false; _state = Running; } } void Thread::stop() { if (_thread != nullptr) { _pauseFlag = false; _stopFlag = true; _condition.notify_all(); // Notify one waiting thread, if there is one. _thread->join(); // wait for thread finished delete _thread; _thread = nullptr; _state = Stoped; } } void Thread::pause() { if (_thread != nullptr) { _pauseFlag = true; _state = Paused; } } void Thread::resume() { if (_thread != nullptr) { _pauseFlag = false; _condition.notify_all(); _state = Running; } } void Thread::run() { cout << "enter thread:" << this_thread::get_id() << endl; while (!_stopFlag) { process(); if (_pauseFlag) { unique_lock<mutex> locker(_mutex); while (_pauseFlag) { _condition.wait(locker); // Unlock _mutex and wait to be notified } locker.unlock(); } } _pauseFlag = false; _stopFlag = false; cout << "exit thread:" << this_thread::get_id() << endl; }
二、测试代码
main.cpp
#include <QCoreApplication> #include <iostream> #include "Thread.h" using namespace std; void mySleep(int s) { std::this_thread::sleep_for(std::chrono::duration<double>(s)); } class MyThread : public Thread { protected: virtual void process() override { cout << "do my something" << endl; mySleep(1); } }; int main(int argc, char *argv[]) { QCoreApplication a(argc, argv); MyThread thread; cout << "start thread" << endl; thread.start(); cout << "thread state:" << thread.state() << endl; mySleep(3); cout << "pause thread" << endl; thread.pause(); cout << "thread state:" << thread.state() << endl; mySleep(3); cout << "resume thread" << endl; thread.resume(); cout << "thread state:" << thread.state() << endl; mySleep(3); cout << "stop thread" << endl; thread.stop(); cout << "thread state:" << thread.state() << endl; mySleep(3); return a.exec(); }
运行结果:
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