#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <string.h>

void cleanup(void *arg)
{
printf("cleanup: %s\n",(char *)arg);
}

void *thr_fn1(void *arg)
{
printf("thread 1 start\n");
pthread_cleanup_push(cleanup,"thread 1 first handler");
pthread_cleanup_push(cleanup,"thread 1 second handler");
printf("thread 1 push complete\n");
if(arg)
return ((void *)1);
pthread_cleanup_pop(1);
pthread_cleanup_pop(1);
return ((void *)1);
}

void *thr_fn2(void *arg)
{
printf("thread 2 start\n");
pthread_cleanup_push(cleanup,"thread 2 first handler");
pthread_cleanup_push(cleanup,"thread 2 second handler");
printf("thread 2 push complete\n");

if(arg)
{
pthread_exit((void *)2);
}
pthread_cleanup_pop(0); //取消第一个线程处理程序

pthread_cleanup_pop(0); //取消第二个线程处理程序

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)
{
fprintf(stderr,"create thread1 failed: %s",strerror(err));
exit(1);
}

err = pthread_create(&tid2,NULL,thr_fn2,(void *)2);
if(err != 0){
fprintf(stderr,"create thread 2 failed: %s",strerror(err));
exit(1);
}

err = pthread_join(tid1,&tret);
if(err != 0){
fprintf(stderr,"thread1 join failed: %s",strerror(err));
exit(1);
}
printf("thread 1 exit code %d\n",(int)tret);
err = pthread_join(tid2,&tret);
if(err != 0){
fprintf(stderr,"thread2 join failed: %s",strerror(err));
exit(1);
}
printf("thread 2 exit code %d\n",(int) tret);
exit(0);
}

//为什么需要出现两个线程清理函数：

pthread_cleanup_push(cleanup,"thread 2 first handler"); 
pthread_cleanup_push(cleanup,"thread 2 second handler");