线程池的核心实现

一句话总结：用队列实现，生产者添加任务，消费者执行任务；注意原子性操作。

#include <iostream>#include <boost/bind.hpp>#include <boost/function.hpp>#include <pthread.h>#include <queue>using namespace std;#define THREAD_NUM 3#define QUEUE_SIZE 3typedef boost::function<void ()> Task;queue<Task> queueTask;pthread_mutex_t g_mutex = PTHREAD_MUTEX_INITIALIZER;pthread_cond_t g_cond = PTHREAD_COND_INITIALIZER;Task take(){pthread_mutex_lock(&g_mutex);if(queueTask.empty())cout <<"queue task is empty" <<endl;while (queueTask.empty()){pthread_cond_wait(&g_cond, &g_mutex);}Task task;if(!queueTask.empty())cout <<"queue task is not empty" <<endl;if (!queueTask.empty()){task = queueTask.front();queueTask.pop();pthread_cond_signal(&g_cond);}pthread_mutex_unlock(&g_mutex);return task;}void add(Task& task){pthread_mutex_lock(&g_mutex);if(queueTask.size() >= QUEUE_SIZE)cout <<"queue task is full" <<endl;while(queueTask.size() >= QUEUE_SIZE){pthread_cond_wait(&g_cond, &g_mutex);}queueTask.push(task);pthread_cond_signal(&g_cond);pthread_mutex_unlock(&g_mutex);return;}void* func(void* arg){while (1){Task task(take());if (task){cout << "run task........."<<endl;task();}}}void print(){cout<<"execute thread pool task............" <<endl;}int main(){cout<<"test thread pool, pool size is 3" <<endl;pthread_t thread[THREAD_NUM];for (int i = 0; i < THREAD_NUM; ++i){int ret = pthread_create(&thread[i], NULL, func, NULL);if (ret != 0){return 1;}}boost::function<void()> fp = boost::bind(print);int cnt = 0;cout <<"add 5 tasks " <<endl;while(cnt < 5){add(fp);++cnt;}sleep(3);cout <<"=================add another task==============="<<endl;sleep(3);add(fp);for(int i=0; i<THREAD_NUM; ++i){pthread_join(thread[i], NULL);}add(fp);return 0;}