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c++实现简单线程池代码


目录

  • ​​完整代码​​
  • ​​TaskPool.cpp​​
  • ​​TaskPool.h​​
  • ​​main.cpp​​


完整代码

TaskPool.cpp

//
// Created by LENOVO on 2021/10/25.
//

#include "TaskPool.h"
#include <functional>

std::mutex printMutex;

TaskPool::TaskPool() : m_bRunning(false)
{

}

TaskPool::~TaskPool()
{
removeAllTasks();
}

void TaskPool::init(int threadNum/*= 5*/)
{
if (threadNum <= 0)
threadNum = 5;
m_bRunning = true;

for (int i = 0; i < threadNum; i++) {
std::shared_ptr<std::thread> spThread;
// 这个bind含义是啥
spThread.reset(new std::thread(std::bind(&TaskPool::threadFunc, this)));
{
std::lock_guard<std::mutex> guard(printMutex);
std::cout << "Init a thread, id: "<< spThread->get_id() << std::endl;
}
m_threads.push_back(spThread);
}
}

void TaskPool::stop()
{
m_bRunning = false;
// 通知所有线程,不运行了
m_cv.notify_all();

// 等待所有线程退出
for (auto& it : m_threads) {
if (it->joinable())
it->join();
}
}

void TaskPool::addTask(Task *task)
{
std::shared_ptr<Task> spTask;
spTask.reset(task);

{// 将task加入队列是互斥的
std::lock_guard<std::mutex> guard(m_mutexList);
m_taskList.push_back(spTask);
}

{
std::lock_guard<std::mutex> guard(printMutex);
std::cout << "add a Task, id: " << spTask->getID() << ", thread id is: " << std::this_thread::get_id() << std::endl;
}
// 通知一个线程的threadFunc
m_cv.notify_one();
}

void TaskPool::removeAllTasks()
{
{// 需要先互斥地将指向taskList的ptr重置,然后将整个taskList资源clead
std::lock_guard<std::mutex> guard(m_mutexList);
for (auto& it : m_taskList) {
it.reset();
}
m_taskList.clear();
}
}

void TaskPool::threadFunc()
{
std::shared_ptr<Task> spTask;
while (true) {
// 获取task的过程是互斥的
{ // 减少锁的粒度
std::unique_lock<std::mutex> guard(m_mutexList);
// 如果任务队列为空,那么就一直wait,等待线程被唤醒加入到队列中
while (m_taskList.empty()) {
if (!m_bRunning)
break;
// 如果获得了互斥锁,但是条件不满足
// wait()会释放锁,挂起当前线程
// 条件变量发生变化的时候,wait()将环型挂起的线程并获得锁
m_cv.wait(guard);
}

if (!m_bRunning)
break;
// 获取队头task
spTask = m_taskList.front();
m_taskList.pop_front();
}
// 如果队列为空,则重新进行尝试获取
if (spTask == NULL)
continue;
// 否则,执行task任务
spTask->doIt();
// 完成之后,将指针重置
spTask.reset();
}
std::lock_guard<std::mutex> guard(printMutex);
std::cout << "exit thread , threadID:" << std::this_thread::get_id() << std::endl;
}

TaskPool.h

//
// Created by LENOVO on 2021/10/25.
//

#ifndef UNTITLED_TASKPOOL_H
#define UNTITLED_TASKPOOL_H

#include<thread>
#include<mutex>
#include<condition_variable>
#include<list>
#include<vector>
#include<memory>
#include<iostream>

extern std::mutex printMutex;

class Task{
private:
unsigned int id;
public:
Task(unsigned int ID)
{
id = ID;
}
virtual void doIt()
{
std::lock_guard<std::mutex> guard(printMutex);
std::cout << "handle a task ,TaskID is: "<< id << ", thradID is:" << std::this_thread::get_id() << std::endl;
}
virtual ~Task()
{
std::lock_guard<std::mutex> guard(printMutex);
std::cout << "a task destructed , TaskID is: "<< id << ", thradID is:" << std::this_thread::get_id() << std::endl;
}
unsigned int getID()
{
return id;
}
};

class TaskPool final{
public:
TaskPool();
~TaskPool();
TaskPool(const TaskPool& rhs) = delete;
TaskPool& operator=(const TaskPool& rhs) = delete;

public:
// 初始化线程
void init(int threadNum = 5);
// 通知所有线程结束运行,并等待所有线程运行结束
void stop();

void addTask(Task* task);
void removeAllTasks();

private:
void threadFunc();

private:
std::list<std::shared_ptr<Task>> m_taskList;
std::mutex m_mutexList;
std::condition_variable m_cv;
bool m_bRunning;
std::vector<std::shared_ptr<std::thread>> m_threads;
};

#endif //UNTITLED_TASKPOOL_H

main.cpp

#include<chrono>
#include "TaskPool.h"

int main()
{
TaskPool threadPool;
threadPool.init();
Task* task = NULL;
for (int i = 0; i < 10; i++) {
task = new Task(i);
threadPool.addTask(task);
}
std::this_thread::sleep_for(std::chrono::seconds(5));

threadPool.stop();

return 0;
}


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