Question

我是Linux新手。我正在尝试使用clock_nanosleep实现一个简单的任务。问题是，clock_nanosleep在被信号中断后没有将errno设置为EINTR。我试过重置SA_RESTART标志。但是，没有成功。这是我的代码。感谢。

void signalHandler( int signum )
{
    printf("Interrupt signal received.\n");
}

void *periodic_thread (void *param)
{
struct itimerspec its;
struct sigevent sig;
struct timespec next, period;
sigset_t blocked;

siginfo_t si;
timer_t mytimer;
int i, j;

/* create a timer that will be used to periodically send a signal */
sig.sigev_notify = SIGEV_SIGNAL;
sig.sigev_signo = SIGUSR1;
sig.sigev_value.sival_ptr = &sig;

timer_create(CLOCK_REALTIME, &sig, &mytimer);

struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = &signalHandler;
sigaction(SIGUSR1, &sa, NULL);

/* set the periodic timer */
its.it_value.tv_sec = 8;
its.it_value.tv_nsec = 00000000; 
its.it_interval.tv_sec = 0;
its.it_interval.tv_nsec = 0; ;
period.tv_sec = 5;
period.tv_nsec = 00000000; 

timer_settime(mytimer, 0, &its, NULL); 

printf("periodic thread started...\n");

j=1;

i = clock_gettime(CLOCK_MONOTONIC, &next);
while(1)
{
  next.tv_sec = next.tv_sec + period.tv_sec;
  next.tv_nsec = next.tv_nsec + period.tv_nsec;
  i = clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &next, 0);  
  printf("I am done \n");
  if((i == -1) && (errno == EINTR))
  break;
}

printf("...periodic thread end!\n");

timer_delete(mytimer);
return NULL;
}

int main()
{

  pthread_t mythread;
  pthread_attr_t myattr;

  //struct sched_param myparam;
  void *returnvalue;
  sigset_t blocked;


  /* initializes the thread attribute */
  pthread_attr_init(&myattr);


  printf("starting a periodic thread...\n");

  pthread_create(&mythread, &myattr, periodic_thread, NULL);

  pthread_attr_destroy(&myattr);

  /* wait the end of the thread we just created */
  pthread_join(mythread, &returnvalue);

  printf("ending main...\n");

return 0;
}

输出＆GT;＆GT;

  starting a periodic thread...
  periodic thread started...
  I am done 
  Interrupt signal received.
  I am done 
  I am done
  continues.. (Does not break the while(1))

Answer 1

我弄明白了这个问题，

问题：主线程被信号中断而不是包含clock_nanosleep的子线程。

解决方案1：使用“pthread_sigmask（SIG_BLOCK，＆amp; blocked，NULL）”在主线程中阻止SIGUSR1

解决方案2：使用“sigev_notify = SIGEV_THREAD_ID”生成线程特定事件。（适用于计时器）

谢谢

Answer 2

与大多数传统系统调用不同，clock_nanosleep在失败时不返回-1。根据{{3}}：

如果clock_nanosleep（）函数返回，因为它已经返回被信号中断后，应返回相应的错误值。

因此，请尝试检查它是否返回EINTR。

（较新的POSIX接口倾向于返回错误代码而不是依赖于errno。有人认为更现代和线程安全，我猜。最终结果只是一团糟，但是，IMO。）

clock_nanosleep不返回-1 / set errno EINTR - LINUX

2 个答案: