关于一个有3个线程的线程池相关操作(用作备忘)

这个线程池的代码是从网上淘到的，经亲测是可以使用的。

#include <stdio.h> 

#include <stdlib.h> 
#include <unistd.h> 
#include <sys/types.h> 
#include <pthread.h> 
#include <assert.h> 


/* 
*线程池里所有运行和等待的任务都是一个CThread_worker 
*由于所有任务都在链表里，所以是一个链表结构 
*/ 
typedef struct worker 
{ 
    /*回调函数，任务运行时会调用此函数，注意也可声明成其它形式*/ 
    void *(*process) (void *arg); 
    void *arg;/*回调函数的参数*/ 
    struct worker *next; 


} CThread_worker; 




/*线程池结构*/ 
typedef struct 
{ 
    pthread_mutex_t queue_lock; 
    pthread_cond_t queue_ready; 


    /*链表结构，线程池中所有等待任务*/ 
    CThread_worker *queue_head; 


    /*是否销毁线程池*/ 
    int shutdown; 
    pthread_t *threadid; 
    /*线程池中允许的活动线程数目*/ 
    int max_thread_num; 
    /*当前等待队列的任务数目*/ 
    int cur_queue_size; 


} CThread_pool; 




int pool_add_worker (void *(*process) (void *arg), void *arg); 
void *thread_routine (void *arg); 




static CThread_pool *pool = NULL; 
void pool_init (int max_thread_num) 
{ 
int i = 0;
    pool = (CThread_pool *) malloc (sizeof (CThread_pool)); 


    pthread_mutex_init (&(pool->queue_lock), NULL); 
    pthread_cond_init (&(pool->queue_ready), NULL); 


    pool->queue_head = NULL; 


    pool->max_thread_num = max_thread_num; 
    pool->cur_queue_size = 0; 


    pool->shutdown = 0; 


    pool->threadid = 
        (pthread_t *) malloc (max_thread_num * sizeof (pthread_t)); 
     
    for (i = 0; i < max_thread_num; i++) 
    {  
        pthread_create (&(pool->threadid[i]), NULL, thread_routine, 
                NULL); 
    } 
} 






/*向线程池中加入任务*/ 
int pool_add_worker (void *(*process) (void *arg), void *arg) 
{ 
    /*构造一个新任务*/ 
    CThread_worker *newworker = 
        (CThread_worker *) malloc (sizeof (CThread_worker)); 
    newworker->process = process; 
    newworker->arg = arg; 
    newworker->next = NULL;/*别忘置空*/ 


    pthread_mutex_lock (&(pool->queue_lock)); 
    /*将任务加入到等待队列中*/ 
    CThread_worker *member = pool->queue_head; 
    if (member != NULL) 
    { 
        while (member->next != NULL) 
            member = member->next; 
        member->next = newworker; 
    } 
    else 
    { 
        pool->queue_head = newworker; 
    } 


    assert (pool->queue_head != NULL); 


    pool->cur_queue_size++; 
    pthread_mutex_unlock (&(pool->queue_lock)); 
    /*好了，等待队列中有任务了，唤醒一个等待线程； 
    注意如果所有线程都在忙碌，这句没有任何作用*/ 
    pthread_cond_signal (&(pool->queue_ready)); 
    return 0; 
} 






/*销毁线程池，等待队列中的任务不会再被执行，但是正在运行的线程会一直 
把任务运行完后再退出*/ 
int pool_destroy () 
{ 
    if (pool->shutdown) 
        return -1;/*防止两次调用*/ 
    pool->shutdown = 1; 


    /*唤醒所有等待线程，线程池要销毁了*/ 
    pthread_cond_broadcast (&(pool->queue_ready)); 


    /*阻塞等待线程退出，否则就成僵尸了*/ 
    int i; 
    for (i = 0; i < pool->max_thread_num; i++) 
        pthread_join (pool->threadid[i], NULL); 
    free (pool->threadid); 


    /*销毁等待队列*/ 
    CThread_worker *head = NULL; 
    while (pool->queue_head != NULL) 
    { 
        head = pool->queue_head; 
        pool->queue_head = pool->queue_head->next; 
        free (head); 
    } 
    /*条件变量和互斥量也别忘了销毁*/ 
    pthread_mutex_destroy(&(pool->queue_lock)); 
    pthread_cond_destroy(&(pool->queue_ready)); 
     
    free (pool); 
    /*销毁后指针置空是个好习惯*/ 
    pool=NULL; 
    return 0; 
} 






void *thread_routine (void *arg) 
{ 
    printf ("starting thread 0x%x\n", (int)pthread_self()); 
    while (1) 
    { 
        pthread_mutex_lock (&(pool->queue_lock)); 
        /*如果等待队列为0并且不销毁线程池，则处于阻塞状态; 注意 
        pthread_cond_wait是一个原子操作，等待前会解锁，唤醒后会加锁*/ 
        while (pool->cur_queue_size == 0 && !pool->shutdown) 
        { 
            printf ("thread 0x%x is waiting\n", (int)pthread_self ()); 
            pthread_cond_wait (&(pool->queue_ready), &(pool->queue_lock)); 
        } 


        /*线程池要销毁了*/ 
        if (pool->shutdown) 
        { 
            /*遇到break,continue,return等跳转语句，千万不要忘记先解锁*/ 
            pthread_mutex_unlock (&(pool->queue_lock)); 
            printf ("thread 0x%x will exit\n", (int)pthread_self ()); 
            pthread_exit (NULL); 
        } 


        printf ("thread 0x%x is starting to work\n", (int)pthread_self ()); 


        /*assert是调试的好帮手*/ 
        assert (pool->cur_queue_size != 0); 
        assert (pool->queue_head != NULL); 
         
        /*等待队列长度减去1，并取出链表中的头元素*/ 
        pool->cur_queue_size--; 
        CThread_worker *worker = pool->queue_head; 
        pool->queue_head = worker->next; 
        pthread_mutex_unlock (&(pool->queue_lock)); 


        /*调用回调函数，执行任务*/ 
        (*(worker->process)) (worker->arg); 
        free (worker); 
        worker = NULL; 
    } 
    /*这一句应该是不可达的*/ 
    pthread_exit (NULL); 
} 


    //下面是测试代码


void *myprocess (void *arg) 
{ 
    printf ("threadid is 0x%x, working on task %d\n", (int)pthread_self (),*(int *) arg); 
    sleep (1);/*休息一秒，延长任务的执行时间*/ 
    return NULL; 
} 


int main (int argc, char **argv) 
{ 
    pool_init (3);/*线程池中最多三个活动线程*/ 
     
    /*连续向池中投入10个任务*/ 
    int *workingnum = (int *) malloc (sizeof (int) * 10); 
    int i; 
    for (i = 0; i < 10; i++) 
    { 
        workingnum[i] = i; 
        pool_add_worker (myprocess, &workingnum[i]); 
    } 
    /*等待所有任务完成*/ 
    sleep (5); 
    /*销毁线程池*/ 
    pool_destroy (); 


    free (workingnum); 
    return 0; 
}