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       1                 :             : /*-------------------------------------------------------------------------
       2                 :             :  *
       3                 :             :  * pgsleep.c
       4                 :             :  *         Portable delay handling.
       5                 :             :  *
       6                 :             :  *
       7                 :             :  * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
       8                 :             :  *
       9                 :             :  * src/port/pgsleep.c
      10                 :             :  *
      11                 :             :  *-------------------------------------------------------------------------
      12                 :             :  */
      13                 :             : #include "c.h"
      14                 :             : 
      15                 :             : #include <time.h>
      16                 :             : 
      17                 :             : /*
      18                 :             :  * In a Windows backend, we don't use this implementation, but rather
      19                 :             :  * the signal-aware version in src/backend/port/win32/signal.c.
      20                 :             :  */
      21                 :             : #if defined(FRONTEND) || !defined(WIN32)
      22                 :             : 
      23                 :             : /*
      24                 :             :  * pg_usleep --- delay the specified number of microseconds.
      25                 :             :  *
      26                 :             :  * NOTE: Although the delay is specified in microseconds, older Unixen and
      27                 :             :  * Windows use periodic kernel ticks to wake up, which might increase the delay
      28                 :             :  * time significantly.  We've observed delay increases as large as 20
      29                 :             :  * milliseconds on supported platforms.
      30                 :             :  *
      31                 :             :  * On machines where "long" is 32 bits, the maximum delay is ~2000 seconds.
      32                 :             :  *
      33                 :             :  * CAUTION: It's not a good idea to use long sleeps in the backend.  They will
      34                 :             :  * silently return early if a signal is caught, but that doesn't include
      35                 :             :  * latches being set on most OSes, and even signal handlers that set MyLatch
      36                 :             :  * might happen to run before the sleep begins, allowing the full delay.
      37                 :             :  * Better practice is to use WaitLatch() with a timeout, so that backends
      38                 :             :  * respond to latches and signals promptly.
      39                 :             :  */
      40                 :             : void
      41                 :          28 : pg_usleep(long microsec)
      42                 :             : {
      43         [ -  + ]:          28 :         if (microsec > 0)
      44                 :             :         {
      45                 :             : #ifndef WIN32
      46                 :          28 :                 struct timespec delay;
      47                 :             : 
      48                 :          28 :                 delay.tv_sec = microsec / 1000000L;
      49                 :          28 :                 delay.tv_nsec = (microsec % 1000000L) * 1000;
      50                 :          28 :                 (void) nanosleep(&delay, NULL);
      51                 :             : #else
      52                 :             :                 SleepEx((microsec < 500 ? 1 : (microsec + 500) / 1000), FALSE);
      53                 :             : #endif
      54                 :          28 :         }
      55                 :          28 : }
      56                 :             : 
      57                 :             : #endif                                                  /* defined(FRONTEND) || !defined(WIN32) */