61 lines
1.9 KiB
C
61 lines
1.9 KiB
C
/*-------------------------------------------------------------------------
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*
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* pgsleep.c
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* Portable delay handling.
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*
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*
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* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
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*
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* src/port/pgsleep.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "c.h"
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#include <unistd.h>
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#include <sys/time.h>
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/*
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* In a Windows backend, we don't use this implementation, but rather
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* the signal-aware version in src/backend/port/win32/signal.c.
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*/
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#if defined(FRONTEND) || !defined(WIN32)
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/*
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* pg_usleep --- delay the specified number of microseconds.
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*
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* NOTE: although the delay is specified in microseconds, the effective
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* resolution is only 1/HZ, or 10 milliseconds, on most Unixen. Expect
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* the requested delay to be rounded up to the next resolution boundary.
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*
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* On machines where "long" is 32 bits, the maximum delay is ~2000 seconds.
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*
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* CAUTION: the behavior when a signal arrives during the sleep is platform
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* dependent. On most Unix-ish platforms, a signal does not terminate the
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* sleep; but on some, it will (the Windows implementation also allows signals
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* to terminate pg_usleep). And there are platforms where not only does a
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* signal not terminate the sleep, but it actually resets the timeout counter
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* so that the sleep effectively starts over! It is therefore rather hazardous
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* to use this for long sleeps; a continuing stream of signal events could
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* prevent the sleep from ever terminating. Better practice for long sleeps
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* is to use WaitLatch() with a timeout.
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*/
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void
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pg_usleep(long microsec)
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{
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if (microsec > 0)
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{
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#ifndef WIN32
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struct timeval delay;
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delay.tv_sec = microsec / 1000000L;
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delay.tv_usec = microsec % 1000000L;
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(void) select(0, NULL, NULL, NULL, &delay);
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#else
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SleepEx((microsec < 500 ? 1 : (microsec + 500) / 1000), FALSE);
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#endif
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}
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}
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#endif /* defined(FRONTEND) || !defined(WIN32) */
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