线程清理函数pthread_cleanup_push / pthread_cleanup_pop

小鱼儿 2022-08-13 10:29 69阅读 0赞

线程可以安排它退出时需要调用的函数，这样的函数称为线程清理处理程序，线程可以建立多个清理处理程序。处理程序记录在栈中，也就是说它们的执行顺序与它们注册时的顺序相反。

pthread\_cleanup\_push来注册清理函数rtn,这个函数有一个参数arg。在以下三种情形之一发生时，注册的清理函数被执行：  
1）调用pthread\_exit。  
2）作为对取消线程请求(pthread\_cancel)的响应。  
3）以非0参数调用pthread\_cleanup\_pop。  
注意：

1）如果线程只是由于简单的返回而终止的，则清除函数不会被调用。

2）如果pthread\_cleanup\_pop被传递0参数，则清除函数不会被调用，但是会清除处于栈顶的清理函数。

<table style="color:rgb(51,51,51); font-family:Arial; font-size:14px; line-height:26px; margin:auto 6.75pt; border-collapse:collapse"> 
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 <td style="padding:0cm 5.4pt; width:96.05pt; height:15.5pt; border:1pt solid windowtext; background-color:transparent"> 名称： </td> 
 <td style="border-color:windowtext windowtext windowtext rgb(236,233,216); border-bottom-width:1pt; border-bottom-style:solid; padding:0cm 5.4pt; width:333.05pt; height:15.5pt; border-top-width:1pt; border-top-style:solid; border-right-width:1pt; border-right-style:solid; background-color:transparent"> pthread_cleanup_push / pthread_cleanup_pop </td> 
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 <td style="border-color:rgb(236,233,216) windowtext windowtext; border-bottom-width:1pt; border-bottom-style:solid; border-left-width:1pt; border-left-style:solid; padding:0cm 5.4pt; width:96.05pt; height:14.75pt; border-right-width:1pt; border-right-style:solid; background-color:transparent"> 功能： </td> 
 <td style="border-color:rgb(236,233,216) windowtext windowtext rgb(236,233,216); border-bottom-width:1pt; border-bottom-style:solid; padding:0cm 5.4pt; width:333.05pt; height:14.75pt; border-right-width:1pt; border-right-style:solid; background-color:transparent"> 线程清理处理程序 </td> 
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 <tr style="height:15.5pt"> 
 <td style="border-color:rgb(236,233,216) windowtext windowtext; border-bottom-width:1pt; border-bottom-style:solid; border-left-width:1pt; border-left-style:solid; padding:0cm 5.4pt; width:96.05pt; height:15.5pt; border-right-width:1pt; border-right-style:solid; background-color:transparent"> 头文件： </td> 
 <td style="border-color:rgb(236,233,216) windowtext windowtext rgb(236,233,216); border-bottom-width:1pt; border-bottom-style:solid; padding:0cm 5.4pt; width:333.05pt; height:15.5pt; border-right-width:1pt; border-right-style:solid; background-color:transparent"> #include &lt;pthread.h&gt; </td> 
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 <td style="border-color:rgb(236,233,216) windowtext windowtext; border-bottom-width:1pt; border-bottom-style:solid; border-left-width:1pt; border-left-style:solid; padding:0cm 5.4pt; width:96.05pt; height:12.1pt; border-right-width:1pt; border-right-style:solid; background-color:transparent"> 函数原形： </td> 
 <td style="border-color:rgb(236,233,216) windowtext windowtext rgb(236,233,216); border-bottom-width:1pt; border-bottom-style:solid; padding:0cm 5.4pt; width:333.05pt; height:12.1pt; border-right-width:1pt; border-right-style:solid; background-color:transparent"> void pthread_cleanup_push(void (*rtn)(void *)，void *arg); void pthread_cleanup_pop(int execute); </td> 
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 <td style="border-color:rgb(236,233,216) windowtext windowtext; border-bottom-width:1pt; border-bottom-style:solid; border-left-width:1pt; border-left-style:solid; padding:0cm 5.4pt; width:96.05pt; height:10.95pt; border-right-width:1pt; border-right-style:solid; background-color:transparent"> 参数： </td> 
 <td style="border-color:rgb(236,233,216) windowtext windowtext rgb(236,233,216); border-bottom-width:1pt; border-bottom-style:solid; padding:0cm 5.4pt; width:333.05pt; height:10.95pt; border-right-width:1pt; border-right-style:solid; background-color:transparent"> rtn&nbsp;处理程序入口地址 arg&nbsp;传递给处理函数的参数 </td> 
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 <td style="border-color:rgb(236,233,216) windowtext windowtext; border-bottom-width:1pt; border-bottom-style:solid; border-left-width:1pt; border-left-style:solid; padding:0cm 5.4pt; width:96.05pt; height:15.5pt; border-right-width:1pt; border-right-style:solid; background-color:transparent"> 返回值： </td> 
 <td style="border-color:rgb(236,233,216) windowtext windowtext rgb(236,233,216); border-bottom-width:1pt; border-bottom-style:solid; padding:0cm 5.4pt; width:333.05pt; height:15.5pt; border-right-width:1pt; border-right-style:solid; background-color:transparent"> 无 </td> 
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#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); 
 }