src/port/pgsleep.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * pgsleep.c
   4  *         Portable delay handling.
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   8  *
   9  * $PostgreSQL$
  10  *
  11  *-------------------------------------------------------------------------
  12  */
  13 #include "c.h"
  14
  15 #include <unistd.h>
  16 #include <sys/time.h>
  17
  18 /*
  19  * In a Windows backend, we don't use this implementation, but rather
  20  * the signal-aware version in src/backend/port/win32/signal.c.
  21  */
  22 #if defined(FRONTEND) || !defined(WIN32)
  23
  24 /*
  25  * pg_usleep --- delay the specified number of microseconds.
  26  *
  27  * NOTE: although the delay is specified in microseconds, the effective
  28  * resolution is only 1/HZ, or 10 milliseconds, on most Unixen.  Expect
  29  * the requested delay to be rounded up to the next resolution boundary.
  30  *
  31  * On machines where "long" is 32 bits, the maximum delay is ~2000 seconds.
  32  */
  33 void
  34 pg_usleep(long microsec)
  35 {
  36         if (microsec > 0)
  37         {
  38 #ifndef WIN32
  39                 struct timeval delay;
  40
  41                 delay.tv_sec = microsec / 1000000L;
  42                 delay.tv_usec = microsec % 1000000L;
  43                 (void) select(0, NULL, NULL, NULL, &delay);
  44 #else
  45                 SleepEx((microsec < 500 ? 1 : (microsec + 500) / 1000), FALSE);
  46 #endif
  47         }
  48 }
  49
  50 #endif   /* defined(FRONTEND) || !defined(WIN32) */