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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1997-2009 Oracle. All rights reserved.
*
* $Id$
*/
#include "db_config.h"
#define __INCLUDE_SELECT_H 1
#include "db_int.h"
#if defined(HAVE_SYSTEM_INCLUDE_FILES) && defined(HAVE_SCHED_YIELD)
#include <sched.h>
#endif
static void __os_sleep __P((ENV *, u_long, u_long));
/*
* __os_yield --
* Yield the processor, optionally pausing until running again.
*
* PUBLIC: void __os_yield __P((ENV *, u_long, u_long));
*/
void
__os_yield(env, secs, usecs)
ENV *env;
u_long secs, usecs; /* Seconds and microseconds. */
{
/*
* Don't require the values be normalized (some operating systems
* return an error if the usecs argument to select is too large).
*/
for (; usecs >= US_PER_SEC; usecs -= US_PER_SEC)
++secs;
if (DB_GLOBAL(j_yield) != NULL) {
(void)DB_GLOBAL(j_yield)(secs, usecs);
return;
}
/*
* Yield the processor so other processes or threads can run. Use
* the local yield call if not pausing, otherwise call the select
* function.
*/
if (secs != 0 || usecs != 0)
__os_sleep(env, secs, usecs);
else {
#if defined(HAVE_MUTEX_UI_THREADS)
thr_yield();
#elif defined(HAVE_PTHREAD_YIELD)
pthread_yield();
#elif defined(HAVE_SCHED_YIELD)
(void)sched_yield();
#elif defined(HAVE_YIELD)
yield();
#else
__os_sleep(env, 0, 0);
#endif
}
}
/*
* __os_sleep --
* Pause the thread of control.
*/
static void
__os_sleep(env, secs, usecs)
ENV *env;
u_long secs, usecs; /* Seconds and microseconds. */
{
struct timeval t;
int ret;
/*
* Sheer raving paranoia -- don't select for 0 time, in case some
* implementation doesn't yield the processor in that case.
*/
t.tv_sec = (long)secs;
t.tv_usec = (long)usecs + 1;
/*
* We don't catch interrupts and restart the system call here, unlike
* other Berkeley DB system calls. This may be a user attempting to
* interrupt a sleeping DB utility (for example, db_checkpoint), and
* we want the utility to see the signal and quit. This assumes it's
* always OK for DB to sleep for less time than originally scheduled.
*/
if (select(0, NULL, NULL, NULL, &t) == -1) {
ret = __os_get_syserr();
if (__os_posix_err(ret) != EINTR)
__db_syserr(env, ret, "select");
}
}
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