多线程四pthread_cleanup_push和pop

来源：互联网发布：真实魔鬼游戏知乎编辑：程序博客网时间：2024/05/02 16:19

http://blog.sina.com.cn/s/blog_6572515e0100y4l5.html

#include <pthread.h>
void pthread_cleanup_push(void (*rtn)(void *),void *arg);rtn是清理函数，arg是调用参数
void pthread_cleanup_pop(int execute);
    在前面讲过线程的终止方式，是正常终止还是非正常终止，都会存在一个资源释放的问题，在posix中提供了一组，就是我们上面看的函数进行线程退出的处理函数，有些像在进程中的atexit函数。释放的方式是指pthread_cleanup_push的调用点到pthread_cleanup_pop之间程序段进行终止。
    pthread_cleanup_push()/pthread_cleanup_pop采用先入后出的方式的栈的管理方式，void *rtn(void *),在执行pthread_cleanup_push()时压入函数栈，多次执行pthread_cleanup_push()形成一个函数链，在执行这个函数链的时候会以反方向弹出，即先入后出。execute参数表识，是否执行弹出清理函数，当execute=0时不进行弹出清理函数，非零的时候弹出处理函数。
    例程9
    程序目的：实现在正常结束线程的时候，进行函数处理
    程序名称：pthread_clean.c
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
void *clean(void *arg)
{
    printf("cleanup :%s  \n",(char *)arg);
    return (void *)0;
}
void *thr_fn1(void *arg)
{
    printf("thread 1 start  \n");
    pthread_cleanup_push( (void*)clean,"thread 1 first handler");
    pthread_cleanup_push( (void*)clean,"thread 1 second hadler");
    printf("thread 1 push complete  \n");
    if(arg)
    {
        return((void *)1);
    }
    pthread_cleanup_pop(0);
    pthread_cleanup_pop(0);
    return (void *)1;
}
void *thr_fn2(void *arg)
{
    printf("thread 2 start  \n");
    pthread_cleanup_push( (void*)clean,"thread 2 first handler");
    pthread_cleanup_push( (void*)clean,"thread 2 second handler");
    printf("thread 2 push complete  \n");
    if(arg)
    {
        pthread_exit((void *)2);
    }
    pthread_cleanup_pop(0);
    pthread_cleanup_pop(0);
    pthread_exit((void *)2);
}
int main(void)
{
    int err;
    pthread_t tid1,tid2;
    void *tret;

    err=pthread_create(&tid1,NULL,thr_fn1,(void *)1);
    if(err!=0)
    {
        printf("error .... \n");
        return -1;
    }
    err=pthread_create(&tid2,NULL,thr_fn2,(void *)1);

    if(err!=0)
    {
        printf("error .... \n");
        return -1;
    }
    err=pthread_join(tid1,&tret);
    if(err!=0)
    {
        printf("error .... \n");
        return -1;
    }
    printf("thread 1 exit code %d  \n",(int)tret);

    err=pthread_join(tid2,&tret);
    if(err!=0)
    {
        printf("error .... ");
        return -1;
    }
    printf("thread 2 exit code %d  \n",(int)tret);
    return 1;
}
执行结果：
thread 1 start
thread 1 push complete
thread 1 exit code 1
thread 2 start
thread 2 push complete
cleanup :thread 2 second handler
cleanup :thread 2 first handler
thread 2 exit code 2

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