如何实现C++中std::thread的线程暂停（挂起）功能？

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目录

一、封装Thread类

二、测试代码

一、封装Thread类

为了更好地管理线程，我们可以封装一个Thread类，基于C++11中与平台无关的线程类std::thread，并为其提供start()、stop()、pause()、resume()线程控制方法。

二、测试代码

cpp#include #include #include

class ThreadWrapper {public: ThreadWrapper() : thread(nullptr) {} ~ThreadWrapper() { stop(); }

void start() { if (thread==nullptr) { thread=new std::thread(&ThreadWrapper::run, this); } }

void stop() { if (thread !=nullptr) { pause(); thread->join(); delete thread; thread=nullptr; } }

void pause() { if (thread !=nullptr) { std::unique_lock lock(mutex); running=false; } }

void resume() { if (thread !=nullptr) { std::unique_lock lock(mutex); running=true; cond.notify_one(); } }

private: void run() { while (true) { std::unique_lock lock(mutex); cond.wait(lock, [this] { return running; }); // Perform the thread's work here std::cout << Thread is running... <

std::thread* thread; std::mutex mutex; std::condition_variable cond; bool running=true;};

int main() { ThreadWrapper tw; tw.start();

std::this_thread::sleep_for(std::chrono::seconds(5));

tw.pause(); std::cout << Thread paused... <

std::this_thread::sleep_for(std::chrono::seconds(2));

tw.resume(); std::cout << Thread resumed... <

std::this_thread::sleep_for(std::chrono::seconds(5));

tw.stop(); std::cout << Thread stopped... <

return 0;}

目录

• 一、封装Thread类
• 二、测试代码

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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