os_sleep.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1997-2005
 *      Sleepycat Software.  All rights reserved.
 *
 * $Id: os_sleep.c,v 12.2 2005/08/10 15:47:27 bostic Exp $
 */

#include "db_config.h"

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>

#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif

#ifdef HAVE_VXWORKS
#include <sys/times.h>
#include <time.h>
#include <selectLib.h>
#else
#if TIME_WITH_SYS_TIME
#include <sys/time.h>
#include <time.h>
#else
#if HAVE_SYS_TIME_H
#include <sys/time.h>
#else
#include <time.h>
#endif /* HAVE_SYS_TIME_H */
#endif /* TIME_WITH SYS_TIME */
#endif /* HAVE_VXWORKS */

#include <string.h>
#endif

#include "db_int.h"

/*
 * __os_sleep --
 *      Yield the processor for a period of time.
 *
 * PUBLIC: void __os_sleep __P((DB_ENV *, u_long, u_long));
 */
void
__os_sleep(dbenv, secs, usecs)
        DB_ENV *dbenv;
        u_long secs, usecs;             /* Seconds and microseconds. */
{
        struct timeval t;
        int ret;

        /* Don't require that the values be normalized. */
        for (; usecs >= 1000000; usecs -= 1000000)
                ++secs;

        if (DB_GLOBAL(j_sleep) != NULL) {
                (void)DB_GLOBAL(j_sleep)(secs, usecs);
                return;
        }

        /*
         * It's important that we yield the processor here so that other
         * processes or threads are permitted to run.
         *
         * Sheer raving paranoia -- don't select for 0 time.
         */
        t.tv_sec = (long)secs;
        if (secs == 0 && usecs == 0)
                t.tv_usec = 1;
        else
                t.tv_usec = (long)usecs;

        /*
         * 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)
                 if ((ret = __os_get_errno()) != EINTR)
                        __db_err(dbenv, "select: %s", strerror(ret));
}

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