用线程池实现多线程调用并使用回调函数实现函数调用_回调函数放在多线程

* 创建线程或者进程的开销是很大的
* 为了防止频繁的创建、销毁线程，提高程序的运行效率
* 往往会建立一个线程池用于多线程程序的调度
* 下面的程序就是完整的线程池实现
*
* 主要通过互斥量和条件变量实现同步

threadpool.h

#ifndef _THREADPOOL_H_
#define _THREADPOOL_H_
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
 
/* 线程体数据结构*/
typedef struct runner
{
    void (*callback)(void *arg);//回调函数指针
    void *arg;                //回调函数参数
    struct runner *next;
}thread_runner;
 
/* 线程池数据结构*/
typedef struct pool
{
    pthread_mutex_t mutex;      //互斥量
    pthread_cond_t cond;        //条件变量
    thread_runner* runner_head; //线程池中所有等待任务的头指针
    thread_runner* runner_tail; //线程池中所有等待任务的尾指针
    int shutdown;              //线程池是否销毁,0没有注销，1注销
    pthread_t* threads;        //所有线程
    int max_thread_size;       //线程池中允许的活动线程数目
}thread_pool;
 
void run(void *arg);
void threadpool_init(thread_pool *pool, int max_thread_size);
void threadpool_add_runner(thread_pool *pool, void (*callback)(void *arg), void *arg);
void threadpool_destroy(thread_pool **ppool);
 
#endif  //_THREADPOOL_H_

threadpool.c

//======================= threadpool.c ===========================
#include "threadpool.h"
 
/**********************************************************
* 初始化线程
* 参数：
* pool：指向线程池结构有效地址的动态指针
* max_thread_size：最大的线程数
**********************************************************/
void threadpool_init(thread_pool *pool, int max_thread_size)
{
    int iLoop = 0;
 
    /*线程池初始化操作*/
    pthread_mutex_init(&(pool->mutex), NULL);                              //初始化互斥量
    pthread_cond_init(&(pool->cond), NULL);                                //初始化条件变量
    pool->shutdown = 0;                                                  //线程池默认没有注销
    pool->threads = (pthread_t *)malloc(max_thread_size * sizeof(pthread_t)); //创建所有分离线程
    pool->runner_head = NULL;
    pool->runner_tail = NULL;
    pool->max_thread_size = max_thread_size;
 
    /*创建线程操作*/
    for(iLoop; iLoop < max_thread_size; iLoop++)
    {
        pthread_attr_t attr;                                                  //定义线程对象
        pthread_attr_init(&attr);                                              //初始化线程的属性
        pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);              //设置脱离状态的属性(决定这个线程在终止时是否可以被结合)
        pthread_create(&(pool->threads[iLoop]), &attr, (void *)run, (void *)pool); /*threads[i] 动态创建线程；
                                                                                   *第一个参数为指向线程标识符的指针。
                                                                                   *第二个参数用来设置线程属性。
                                                                                   *第三个参数是线程运行函数的起始地址。
                                                                                   *最后一个参数是运行函数的参数。*/
    } 
    printf("threadpool_init-> create %d detached thread\n");
}
 
/**********************************************************
* 线程体,创建线程后调用的函数
* 参数：
* arg：接收创建线程后传递的参数
**********************************************************/
void run(void *arg)
{
    thread_pool *pool = (thread_pool *)arg;
 
    while(1)
    {
        pthread_mutex_lock(&(pool->mutex));               //加锁
        printf("run-> locked!\n");
 
        /*如果等待队列为0并且线程池未销毁,则处于阻塞状态 */
        while(pool->runner_head == NULL && !pool->shutdown)
        {
            pthread_cond_wait(&(pool->cond), &(pool->mutex));
        }
 
        /*如果线程已经销毁*/
        if(pool->shutdown)
        {
            pthread_mutex_unlock(&(pool->mutex));          //解锁
            printf("run-> unlock and thread exit!\n");
            pthread_exit(NULL);
        }
        thread_runner *runner = pool->runner_head;         //取链表的头元素
        pool->runner_head = runner->next;
        pthread_mutex_unlock(&(pool->mutex));              //解锁
        printf("run-> unlocked!\n");
        (runner->callback)(runner->arg);                  //调用回调函数，执行任务
        free(runner);                                   //释放线程操作
        runner = NULL;
        printf("run-> runned and free runner!\n");
    }
    pthread_exit(NULL);
}
 
/**********************************************************
* 向线程池加入任务
* 参数：
* pool：指向线程池结构有效地址的动态指针
* callback：线程回调函数
* arg：回调函数参数
**********************************************************/
void threadpool_add_runner(thread_pool *pool, void(*callback)(void *arg), void *arg)
{  
    thread_runner *newrunner = (thread_runner *)malloc(sizeof(thread_runner));//构建一个新任务
    newrunner->callback = callback;
    newrunner->arg = arg;
    newrunner->next = NULL;
 
    pthread_mutex_lock(&(pool->mutex));                    //加锁
    printf("threadpool_add_runner-> locked\n");
 
    /*将新任务加入到等待队列中,如果等待队列为空，直接运行当前的线程 */
    if(pool->runner_head != NULL)
    {
        pool->runner_tail->next = newrunner;
        pool->runner_tail = newrunner;
    }
    else
    {
        pool->runner_head = newrunner; 
        pool->runner_tail = newrunner;
    }
    pthread_mutex_unlock(&(pool->mutex));                  //解锁
    printf("threadpool_add_runner-> unlocked\n");
    pthread_cond_signal(&(pool->cond));                    //唤醒一个等待线程
    printf("threadpool_add_runner-> add a runner and wakeup a waiting thread\n");
}
 
/**********************************************************
* 销毁线程池
* 参数：
* ppool：指向线程池结构有效地址的动态指针地址(二级指针)
**********************************************************/
void threadpool_destroy(thread_pool **ppool)
{
    thread_pool *pool = *ppool;
 
    /*判断线程池是否注销,防止二次销毁*/
    if(!pool->shutdown)
    {
        pool->shutdown = 1; 
        pthread_cond_broadcast(&(pool->cond));    //唤醒所有的等待线程，线程池要销毁了
        sleep(1);                              //等待所有的线程终止
        printf("threadpool_destroy-> wakeup all waitting threads\n");  
        free(pool->threads);                    //回收空间
 
        /*销毁等待队列*/
        thread_runner *head = NULL;
        while(pool->runner_head != NULL)
        {
            head = pool->runner_head;
            pool->runner_head = pool->runner_head->next;
            free(head);
        }
        printf("thread_destroy-> all runners freed\n");
 
        pthread_mutex_destroy(&(pool->mutex));    //销毁条件变量
        pthread_cond_destroy(&(pool->cond));      //销毁互斥量
        printf("thread_destroy-> mutex and cond destroyed\n");
        free(pool);
        pool = NULL;
        (*ppool) = NULL;
        printf("threadpool_destroy-> pool freed\n");
    }
}
//======================= end threadpool.c ===========================

main.c

#include "threadpool.h"
 
 
void threadrun(void *arg)
{
    int i = *(int *)arg;
    printf("threadrun result == %d\n", i);
}
 
int main(int argc, char *argv[])
{
    thread_pool *pool = (thread_pool *)malloc(sizeof(thread_pool));
    threadpool_init(pool, 9);
    int i;
    int tmp[10];
    for(i = 0; i < 10; i++)
    {
        tmp[i] = i;
        threadpool_add_runner(pool, threadrun, &tmp[i]);
    }
    sleep(1);
    threadpool_destroy(&pool);
    printf("main-> %p\n", pool);
    printf("main-> test over\n");
    return 0;
}

Makefile

#Makefile
main: mian.o threadpool.o
	gcc -o main test.o threadpool.o -lpthread
mian.o: threadpool.h
	gcc -c main.c -lpthread
hreadpool.o: threadpool.h
	gcc -c threadpool.c -lpthread
 
.PHONY:clean
clean:
	rm -f *.o main