98 lines
2.3 KiB
C
98 lines
2.3 KiB
C
/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1997,2008 Oracle. All rights reserved.
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*
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* $Id: os_yield.c 63573 2008-05-23 21:43:21Z trent.nelson $
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*/
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#include "db_config.h"
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#define __INCLUDE_SELECT_H 1
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#include "db_int.h"
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#if defined(HAVE_SYSTEM_INCLUDE_FILES) && defined(HAVE_SCHED_YIELD)
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#include <sched.h>
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#endif
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static void __os_sleep __P((ENV *, u_long, u_long));
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/*
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* __os_yield --
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* Yield the processor, optionally pausing until running again.
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*
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* PUBLIC: void __os_yield __P((ENV *, u_long, u_long));
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*/
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void
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__os_yield(env, secs, usecs)
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ENV *env;
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u_long secs, usecs; /* Seconds and microseconds. */
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{
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/*
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* Don't require the values be normalized (some operating systems
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* return an error if the usecs argument to select is too large).
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*/
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for (; usecs >= US_PER_SEC; usecs -= US_PER_SEC)
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++secs;
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if (DB_GLOBAL(j_yield) != NULL) {
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(void)DB_GLOBAL(j_yield)(secs, usecs);
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return;
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}
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/*
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* Yield the processor so other processes or threads can run. Use
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* the local yield call if not pausing, otherwise call the select
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* function.
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*/
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if (secs != 0 || usecs != 0)
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__os_sleep(env, secs, usecs);
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else {
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#if defined(HAVE_MUTEX_UI_THREADS)
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thr_yield();
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#elif defined(HAVE_PTHREAD_YIELD) && \
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(defined(HAVE_MUTEX_PTHREADS) || defined(HAVE_PTHREAD_API))
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pthread_yield();
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#elif defined(HAVE_SCHED_YIELD)
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(void)sched_yield();
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#elif defined(HAVE_YIELD)
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yield();
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#else
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__os_sleep(dbenv, 0, 0);
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#endif
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}
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}
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/*
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* __os_sleep --
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* Pause the thread of control.
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*/
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static void
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__os_sleep(env, secs, usecs)
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ENV *env;
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u_long secs, usecs; /* Seconds and microseconds. */
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{
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struct timeval t;
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int ret;
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/*
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* Sheer raving paranoia -- don't select for 0 time, in case some
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* implementation doesn't yield the processor in that case.
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*/
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t.tv_sec = (long)secs;
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t.tv_usec = (long)usecs + 1;
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/*
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* We don't catch interrupts and restart the system call here, unlike
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* other Berkeley DB system calls. This may be a user attempting to
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* interrupt a sleeping DB utility (for example, db_checkpoint), and
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* we want the utility to see the signal and quit. This assumes it's
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* always OK for DB to sleep for less time than originally scheduled.
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*/
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if (select(0, NULL, NULL, NULL, &t) == -1) {
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ret = __os_get_syserr();
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if (__os_posix_err(ret) != EINTR)
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__db_syserr(env, ret, "select");
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}
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}
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