libumem/common/umem_update_thread.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include "umem_base.h"
#include "vmem_base.h"

#include <signal.h>

/*ARGSUSED*/
static void *
umem_update_thread(void *arg)
{
    struct timeval now;
    int in_update = 0;

    (void) mutex_lock(&umem_update_lock);

    ASSERT(umem_update_thr == thr_self());
    ASSERT(umem_st_update_thr == 0);

    for (;;) {
        umem_process_updates();

        if (in_update) {
            in_update = 0;
            /*
             * we wait until now to set the next update time
             * so that the updates are self-throttling
             */
            (void) gettimeofday(&umem_update_next, NULL);
            umem_update_next.tv_sec += umem_reap_interval;
        }

        switch (umem_reaping) {
        case UMEM_REAP_DONE:
        case UMEM_REAP_ADDING:
            break;

        case UMEM_REAP_ACTIVE:
            umem_reap_next = gethrtime() +
                (hrtime_t)umem_reap_interval * NANOSEC;
            umem_reaping = UMEM_REAP_DONE;
            break;

        default:
            ASSERT(umem_reaping == UMEM_REAP_DONE ||
                umem_reaping == UMEM_REAP_ADDING ||
                umem_reaping == UMEM_REAP_ACTIVE);
            break;
        }

        (void) gettimeofday(&now, NULL);
        if (now.tv_sec > umem_update_next.tv_sec ||
            (now.tv_sec == umem_update_next.tv_sec &&
            now.tv_usec >= umem_update_next.tv_usec)) {
            /*
             * Time to run an update
             */
            (void) mutex_unlock(&umem_update_lock);

            vmem_update(NULL);
            /*
             * umem_cache_update can use umem_add_update to
             * request further work.  The update is not complete
             * until all such work is finished.
             */
            umem_cache_applyall(umem_cache_update);

            (void) mutex_lock(&umem_update_lock);
            in_update = 1;
            continue;   /* start processing immediately */
        }

        /*
         * if there is no work to do, we wait until it is time for
         * next update, or someone wakes us.
         */
        if (umem_null_cache.cache_unext == &umem_null_cache) {
            int cancel_state;
            timespec_t abs_time;
            abs_time.tv_sec = umem_update_next.tv_sec;
            abs_time.tv_nsec = umem_update_next.tv_usec * 1000;

            (void) pthread_setcancelstate(PTHREAD_CANCEL_DISABLE,
                &cancel_state);
            (void) cond_timedwait(&umem_update_cv,
                &umem_update_lock, &abs_time);
            (void) pthread_setcancelstate(cancel_state, NULL);
        }
    }
    /* LINTED no return statement */
}

int
umem_create_update_thread(void)
{
    sigset_t sigmask, oldmask;
    thread_t newthread;

    ASSERT(MUTEX_HELD(&umem_update_lock));
    ASSERT(umem_update_thr == 0);

    /*
     * The update thread handles no signals
     */
    (void) sigfillset(&sigmask);
    (void) thr_sigsetmask(SIG_BLOCK, &sigmask, &oldmask);

    /*
     * drop the umem_update_lock; we cannot hold locks acquired in
     * pre-fork handler while calling thr_create or thr_continue().
     */

    (void) mutex_unlock(&umem_update_lock);

    if (thr_create(NULL, NULL, umem_update_thread, NULL,
        THR_BOUND | THR_DAEMON | THR_DETACHED | THR_SUSPENDED,
        &newthread) == 0) {
        (void) thr_sigsetmask(SIG_SETMASK, &oldmask, NULL);

        (void) mutex_lock(&umem_update_lock);
        /*
         * due to the locking in umem_reap(), only one thread can
         * ever call umem_create_update_thread() at a time.  This
         * must be the case for this code to work.
         */

        ASSERT(umem_update_thr == 0);
        umem_update_thr = newthread;
        (void) mutex_unlock(&umem_update_lock);
        (void) thr_continue(newthread);
        (void) mutex_lock(&umem_update_lock);

        return (1);
    } else { /* thr_create failed */
        (void) thr_sigsetmask(SIG_SETMASK, &oldmask, NULL);
        (void) mutex_lock(&umem_update_lock);
    }
    return (0);
}