目录

一、LockGuard.hpp

二、Task.hpp 

三、Thread.hpp

四、ThreadPool.hpp

一、LockGuard.hpp

#pragma once
#include <iostream>
#include <pthread.h>
class Mutex//锁的对象
{
public:Mutex(pthread_mutex_t* lock_p=nullptr):_lock_p(lock_p){}~Mutex(){}void lock(){if(_lock_p){pthread_mutex_lock(_lock_p);}}void unlock(){if(_lock_p){pthread_mutex_unlock(_lock_p);}}
private:pthread_mutex_t* _lock_p;//锁的指针
};
class LockGuard//加锁和解锁的类
{
public:LockGuard(pthread_mutex_t* mutex):_mutex(mutex){_mutex.lock();//在构造函数进行加锁}~LockGuard(){_mutex.unlock();//在析构函数进行解锁}
private:Mutex _mutex;
};

二、Task.hpp 

#pragma once
#include <iostream>
#include <functional>
#include <string>
class Task
{//using func=std::function<int(int,int,char)>;typedef std::function<int(int,int,char)> func_t;//函数对象
public:Task(){}Task(int x,int y,char op,func_t func):_x(x),_y(y),_op(op),_callBack(func){}std::string operator()()//消费者调用{int result=_callBack(_x,_y,_op);char buffer[1024];snprintf(buffer,sizeof(buffer),"%d %c %d=%d",_x,_op,_y,result);//结果字符串return buffer;}std::string toTaskString()//生产者调用{char buffer[1024];snprintf(buffer,sizeof(buffer),"%d %c %d=?",_x,_op,_y);return buffer;}
private:int _x;int _y;char _op;//加减乘除取模func_t _callBack;//回调函数
};const std::string oper = "+-*/%";
int myMath(int x, int y, char op)
{int result = 0;switch (op){case '+':result = x + y;break;case '-':result = x - y;break;case '*':result = x * y;break;case '/':{if (y == 0){std::cerr << "div zero error" << std::endl;result = -1;}elseresult = x / y;}break;case '%':{if (y == 0){std::cerr << "mod zero" << std::endl;result = -1;}elseresult = x % y;}break;default:std::cout<<"运算符输入有误"<<std::endl;break;}return result;
}

三、Thread.hpp

#pragma once
#include <iostream>
#include <pthread.h>
#include <string>
#include <functional>
#include <cassert>
namespace ThreadNs
{typedef std::function<void*(void*)> func_t;//定义一个函数对象类型，它的返回值和参数都是void*const int num = 1024;class Thread{private://因为形参有个this指针，所以弄成staticstatic void* start_routine(void* args)//这里的args就是 start()的ctx{Thread* _this=static_cast<Thread*>(args);return _this->callback();} void* callback(){return _func(_args);}public://构造函数Thread(){char nameBuffer[num];snprintf(nameBuffer,sizeof(nameBuffer),"thread-%d",threadNum++);_name=nameBuffer;}void start(func_t func,void* args=nullptr)//线程启动{_func=func;_args=args;int n=pthread_create(&_tid,nullptr,start_routine,this);assert(n==0);(void)n;}void join(){int n=pthread_join(_tid,nullptr);assert(n==0);(void)n;}std::string threadName(){return _name;}~Thread(){}private:std::string _name;//线程的名字func_t _func;//线程的回调函数void* _args;//喂给线程的参数pthread_t _tid;//线程IDstatic int threadNum;//线程编号，最好自己再加个锁};int Thread::threadNum=1;//异常和if。意料之外//assert。意料之中。99%概率为真。
}

四、ThreadPool.hpp

#pragma once
#include <vector>
#include <queue>
#include <pthread.h>
#include <unistd.h>
#include <mutex>
#include "Thread.hpp"
#include "LockGuard.hpp"
using namespace ThreadNs;
const int gnum =5;template <class T>//声明
class ThreadPool;template <class T>
struct ThreadData
{ThreadData(ThreadPool<T>* tp,const std::string& s):_threadPool(tp),_name(s){}ThreadPool<T>* _threadPool;std::string _name;
};
template <class T>
class ThreadPool
{
private://因为普通成员函数第一个参数是this指针，和回调方法不匹配，故改成static类型static void* handlerTask(void* args)//args是ThreadData对象指针{ThreadData<T>* td=static_cast<ThreadData<T>*>(args);while(1){T t;{   //RAII，出了作用域LockGuard会销毁，将析构锁LockGuard lockGuard(td->_threadPool->mutex());//加锁while(td->_threadPool->IsQueueEmpty())//如果队列为空，则等待{td->_threadPool->ThreadWait();}//线程能走到这里，说明队列一定有任务给线程t=td->_threadPool->Pop();//从队列中取出任务}std::cout<<td->_name<<"已获取任务："<<t.toTaskString()<<"处理结果是："<<t()<<std::endl;//处理任务,这个任务放到线程的外面}delete td;//析构ThreadData对象return nullptr;}ThreadPool(const int& num=gnum):_num(num){pthread_mutex_init(&_mutex,nullptr);pthread_cond_init(&_cond,nullptr);//创建线程for(int i=0;i<_num;++i){_threads.push_back(new Thread());}}ThreadPool(const ThreadPool<T>&)=delete;//禁用拷贝构造ThreadPool<T>& operator=(const ThreadPool<T>&)=delete;//禁用赋值运算符重载public://解决静态handlerTask是静态函数的问题，这几个都是偷家函数void LockQueue()   {pthread_mutex_lock(&_mutex);}void UnLockQueue() {pthread_mutex_unlock(&_mutex);}bool IsQueueEmpty(){return _taskQueue.empty();}void ThreadWait()  {pthread_cond_wait(&_cond,&_mutex);}T Pop()         {T t=_taskQueue.front();_taskQueue.pop();return t;} pthread_mutex_t* mutex(){return &_mutex;}
public: void run()//线程启动{for(const auto& t:_threads){ThreadData<T>* td=new ThreadData<T>(this,t->threadName());t->start(handlerTask,(void*)td);std::cout<<t->threadName()<<"start..."<<std::endl;}}void push(const T& in){//RAII,出了作用域，锁将会被释放LockGuard lockGuard(&_mutex);_taskQueue.push(in);pthread_cond_signal(&_cond);std::cout<<"任务发送成功"<<std::endl;}~ThreadPool(){pthread_mutex_destroy(&_mutex);pthread_cond_destroy(&_cond);for(const auto& t:_threads){delete t;}}static ThreadPool<T>* getInstance()//这里的static的作用是让这个函数只有一份，获取单例对象。tp是临界资源，需要加锁{if(nullptr==tp)//因为锁只创建一次，防止线程进来被锁阻塞{//只进来一次就够了_singletonLock.lock();if(nullptr==tp)//说明对象还没有被创建{tp=new ThreadPool<T>(); }_singletonLock.unlock();}return tp;}
private:int _num;//线程个数std::vector<Thread*> _threads;//使用vector存放线程std::queue<T> _taskQueue;//任务队列，往里面放任务，它是共享资源，需要加锁保护pthread_mutex_t _mutex;//互斥锁pthread_cond_t _cond;//条件变量static ThreadPool<T>* tp;//单例模式静态的对象指针static std::mutex _singletonLock;//获取单例对象使用的锁};
template <class T>
ThreadPool<T>* ThreadPool<T>::tp=nullptr;template <class T>
std::mutex ThreadPool<T>::_singletonLock;

1、调用getInstance时需要加锁，防止多个线程同时调用，实例化出多份对象。

2、双重if判断，避免不必要的锁竞争。