#if 0 
线程结束时清理函数 
pthread_cleanup_push()，应该在线程开始的时候尽快执行初始化 
pthread_cleanup_pop()，当遇到以下三种各件会自动调用该函数，不需要PC执行到此函数 
1.调用pthread_exit() 
2.响应取消请求例如pthread_cancel() 
3.当pthread_cleanup_pop(arg)参数arg为非0时会线程退出时自动执行 
 
如果没有以上三种情况，则不会执行； 
#endif 
 
#include <pthread.h> 
#include <stdio.h> 
#include <stdlib.h> 
#include <unistd.h> 
#include <semaphore.h> 
 
sem_t sm0,sm1,sm2,sm3; //信号量定义 信号量为控制线程的执行 
 
void ret_fn(void*str)//线程退出调用的回调函数 
{ 
    fputs(str,stdout); 
} 
 
 
void thread0(void) 
{ 
    if(0 != sem_wait(&sm0))//信号量进行阻塞 
    { 
        perror("sem_wait_0"); 
    } 
     
    char *str = "thead0_return_FN is runing\n"; 
    pthread_cleanup_push(ret_fn,str);//将回调函数入栈 
    fputs("thread0 is runing\n",stdout); 
    pthread_cleanup_pop(0);//将回调函数出栈，当遇到特定的条件会自动调用，不需要PC指到此才执行 
    return; 
} 
void thread1(void) 
{ 
    if(0 != sem_wait(&sm1)) 
    { 
        perror("sem_wait_1"); 
    } 
    char *str = "thead1_return_FN is runing\n"; 
    pthread_cleanup_push(ret_fn,str); 
    fputs("thread1 is runing\n",stdout); 
    pthread_exit((void*)1); 
    pthread_cleanup_pop(0); 
} 
 
void thread2(void) 
{ 
    if(0 != sem_wait(&sm2)) 
    { 
        perror("sem_wait_2"); 
    } 
    char *str = "thead2_return_FN is runing\n"; 
    pthread_cleanup_push(ret_fn,str); 
    fputs("thread2 is runing\n",stdout); 
    pthread_cleanup_pop(1); 
    fputs("线程结束才会执行pthread_cleanup_pop\n",stdout);//线程结束才会执行pthread_cleanup_pop 
} 
void thread3(void) 
{ 
    char *str = "thead3_return_FN is runing\n"; 
    pthread_cleanup_push(ret_fn,str); 
    if(0 != sem_wait(&sm3)) 
    { 
        perror("sem_wait_3"); 
    } 
    fputs("thread3 is runing\n",stdout); 
    usleep(100);// 让主线程中的pthread_cancel可以执行 
    pthread_cleanup_pop(0); 
 
} 
 
int main(void) 
{ 
 
    pthread_t thd0,thd1,thd2,thd3; 
     
    if(0 != sem_init(&sm0,0,0))//初始化信号量 
    { 
        perror("sem_init_0"); 
        exit(1); 
    } 
    if(0 != sem_init(&sm1,0,0)) 
    { 
        perror("sem_init_0"); 
        exit(1); 
    } 
    if(0 != sem_init(&sm2,0,0)) 
    { 
        perror("sem_init_0"); 
        exit(1); 
    } 
    if(0 != sem_init(&sm3,0,0)) 
    { 
        perror("sem_init_0"); 
        exit(1); 
    } 
     
    if(0 != pthread_create(&thd0,NULL,(void*)thread0,NULL))//创建线程 
    { 
        perror("pthread_create_0\n"); 
        exit(1); 
    } 
    if(0 != pthread_create(&thd1,NULL,(void*)thread1,NULL)) 
    { 
        perror("pthread_create_1\n"); 
        exit(1); 
    } 
    if(0 != pthread_create(&thd2,NULL,(void*)thread2,NULL)) 
    { 
        perror("pthread_create_2\n"); 
        exit(1); 
    } 
    if(0 != pthread_create(&thd3,NULL,(void*)thread3,NULL)) 
    { 
        perror("pthread_create_3\n"); 
        exit(1); 
    } 
    unsigned char status = 0xF;//控制重复测试掩码 
     
    while(1) 
    { 
        fputs("请输入测试选项：0(没有调用回调函数),１(pthread_exit),2(pthread_cancel),3(参数非0 pthread_cleanup_pop)\n",stdout); 
        int in; 
        scanf("%d",&in); 
        switch(in) 
        { 
            case 0: 
                { 
                    if(!(status & 0x1)) 
                    { 
                        fputs("这个项目已测试过，请选择其它，谢谢\n",stdout); 
                        break; 
                    } 
                    if(0 != sem_post(&sm0))//激活信号量，让子线程THD0继续执行 
                    { 
                        perror("sem_post_0\n"); 
                    } 
                    status &= 0xe; 
                    break; 
                } 
            case 1: 
                { 
                    if(!(status & 0x2)) 
                    { 
                        fputs("这个项目已测试过，请选择其它，谢谢\n",stdout); 
                        break; 
                    } 
                    if(0 != sem_post(&sm1)) 
                    { 
                        perror("sem_post_1\n"); 
                    } 
                    status &= 0xc; 
                    break; 
                }        
            case 2: 
                { 
                    if(!(status & 0x4)) 
                    { 
                        fputs("这个项目已测试过，请选择其它，谢谢\n",stdout); 
                        break; 
                    } 
                    if(0 != sem_post(&sm2)) 
                    { 
                        perror("sem_post_2\n"); 
                    } 
                    status &= 0xb; 
                    break; 
                } 
            case 3: 
                { 
                    if(!(status & 0x8)) 
                    { 
                        fputs("这个项目已测试过，请选择其它，谢谢\n",stdout); 
                        break; 
                    } 
                    if(0 != sem_post(&sm3)) 
                    { 
                        perror("sem_post_3\n"); 
                    } 
                    pthread_cancel(thd3); 
                    status &= 0x7; 
                    break; 
                } 
            default: break; 
        }    
        sleep(1); 
    } 
 
     
    return 0; 
}