Age         Owner                    Branch data    TLA  Line data    Source code

                                  1                 :                : /*-------------------------------------------------------------------------
                                  2                 :                :  *
                                  3                 :                :  * pgsleep.c
                                  4                 :                :  *     Portable delay handling.
                                  5                 :                :  *
                                  6                 :                :  *
                                  7                 :                :  * Portions Copyright (c) 1996-2024, 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
 7369 tgl@sss.pgh.pa.us          41                 :CBC        5806 : pg_usleep(long microsec)
                                 42                 :                : {
                                 43         [ +  - ]:           5806 :     if (microsec > 0)
                                 44                 :                :     {
                                 45                 :                : #ifndef WIN32
                                 46                 :                :         struct timespec delay;
                                 47                 :                : 
                                 48                 :           5806 :         delay.tv_sec = microsec / 1000000L;
  396 tmunro@postgresql.or       49                 :           5806 :         delay.tv_nsec = (microsec % 1000000L) * 1000;
                                 50                 :           5806 :         (void) nanosleep(&delay, NULL);
                                 51                 :                : #else
                                 52                 :                :         SleepEx((microsec < 500 ? 1 : (microsec + 500) / 1000), FALSE);
                                 53                 :                : #endif
                                 54                 :                :     }
 7369 tgl@sss.pgh.pa.us          55                 :           5803 : }
                                 56                 :                : 
                                 57                 :                : #endif                          /* defined(FRONTEND) || !defined(WIN32) */