Sleep, usleep function delay problem

Sleep, usleep function delay problem

problem

In a multi-process and multi-threaded environment, the thread is expected to sleep usleep (500*1000). In fact, the sleep function will be awakened immediately due to interrupts, system calls, etc.

[Note] POSIX.1-2001 has marked usleep as obsolete, and POSIX.1-2008 has deleted usleep. You should use nanosleep instead of usleep ( sleep, usleep, nanosleep, poll and select in Linux )

API

• API

  #include <unistd.h>
  int usleep(useconds_t usec);
  

• return value

  returns 0 on success.  On error, -1 is returned, with errno set to indicate the cause of the error.
  

• ERRORS

  EINTR  Interrupted by a signal; see signal(7).
  EINVAL usec is greater than or equal to 1000000.
  

solve

int microsleep(unsigned int microseconds)
{
    
    
  unsigned int eclipsed = 0;
  struct timeval bgn,end;
  gettimeofday(&bgn,0);
  do {
    
    
    while (microseconds > eclipsed && usleep(microseconds - eclipsed) < 0 && errno == EINTR);
    gettimeofday(&end,0);
    eclipsed = (end.tv_sec - bgn.tv_sec) * 1000 + (end.tv_usec - bgn.tv_usec) / 1000;
  } while (eclipsed < microseconds);
  return 0;
}

reference

• Sleep, usleep, nanosleep, poll and select in Linux (http://blog.chinaunix.net/uid-20682147-id-5817666.html)
• In-depth understanding of short delay under linux: nanosleep, sleep (https://www.jianshu.com/p/42abcc2c9e50)