58 lines
1.7 KiB
C
58 lines
1.7 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* pgsleep.c
|
|
* Portable delay handling.
|
|
*
|
|
*
|
|
* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
|
|
*
|
|
* src/port/pgsleep.c
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#include "c.h"
|
|
|
|
#include <time.h>
|
|
|
|
/*
|
|
* In a Windows backend, we don't use this implementation, but rather
|
|
* the signal-aware version in src/backend/port/win32/signal.c.
|
|
*/
|
|
#if defined(FRONTEND) || !defined(WIN32)
|
|
|
|
/*
|
|
* pg_usleep --- delay the specified number of microseconds.
|
|
*
|
|
* NOTE: Although the delay is specified in microseconds, older Unixen and
|
|
* Windows use periodic kernel ticks to wake up, which might increase the delay
|
|
* time significantly. We've observed delay increases as large as 20
|
|
* milliseconds on supported platforms.
|
|
*
|
|
* On machines where "long" is 32 bits, the maximum delay is ~2000 seconds.
|
|
*
|
|
* CAUTION: It's not a good idea to use long sleeps in the backend. They will
|
|
* silently return early if a signal is caught, but that doesn't include
|
|
* latches being set on most OSes, and even signal handlers that set MyLatch
|
|
* might happen to run before the sleep begins, allowing the full delay.
|
|
* Better practice is to use WaitLatch() with a timeout, so that backends
|
|
* respond to latches and signals promptly.
|
|
*/
|
|
void
|
|
pg_usleep(long microsec)
|
|
{
|
|
if (microsec > 0)
|
|
{
|
|
#ifndef WIN32
|
|
struct timespec delay;
|
|
|
|
delay.tv_sec = microsec / 1000000L;
|
|
delay.tv_nsec = (microsec % 1000000L) * 1000;
|
|
(void) nanosleep(&delay, NULL);
|
|
#else
|
|
SleepEx((microsec < 500 ? 1 : (microsec + 500) / 1000), FALSE);
|
|
#endif
|
|
}
|
|
}
|
|
|
|
#endif /* defined(FRONTEND) || !defined(WIN32) */
|