greenplumn pgsleep 源码
greenplumn pgsleep 代码
文件路径：/src/port/pgsleep.c
/*-------------------------------------------------------------------------
*
* pgsleep.c
* Portable delay handling.
*
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
*
* src/port/pgsleep.c
*
*-------------------------------------------------------------------------
*/
#include "c.h"
#include <unistd.h>
#include <sys/time.h>
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
/*
* 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, the effective
* resolution is only 1/HZ, or 10 milliseconds, on most Unixen. Expect
* the requested delay to be rounded up to the next resolution boundary.
*
* On machines where "long" is 32 bits, the maximum delay is ~2000 seconds.
*
* CAUTION: the behavior when a signal arrives during the sleep is platform
* dependent. On most Unix-ish platforms, a signal does not terminate the
* sleep; but on some, it will (the Windows implementation also allows signals
* to terminate pg_usleep). And there are platforms where not only does a
* signal not terminate the sleep, but it actually resets the timeout counter
* so that the sleep effectively starts over! It is therefore rather hazardous
* to use this for long sleeps; a continuing stream of signal events could
* prevent the sleep from ever terminating. Better practice for long sleeps
* is to use WaitLatch() with a timeout.
*/
void
pg_usleep(long microsec)
{
if (microsec > 0)
{
#ifndef WIN32
struct timeval delay;
delay.tv_sec = microsec / 1000000L;
delay.tv_usec = microsec % 1000000L;
(void) select(0, NULL, NULL, NULL, &delay);
#else
SleepEx((microsec < 500 ? 1 : (microsec + 500) / 1000), FALSE);
#endif
}
}
#endif /* defined(FRONTEND) || !defined(WIN32) */
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