cmd/nscd/nscd_wait.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 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

/*
 * routines to wait and wake up a client waiting on a list for a
 * name service request
 */
#include "cache.h"

int
nscd_wait(nsc_ctx_t *ctx, nsc_db_t *nscdb, nsc_entry_t *entry)
{
    waiter_t    mywait;
    waiter_t    *wchan = &nscdb->db_wait;

    (void) cond_init(&(mywait.w_waitcv), USYNC_THREAD, 0);
    mywait.w_key = entry;
    mywait.w_signaled = 0;
    mywait.w_next = wchan->w_next;
    mywait.w_prev = wchan;
    if (mywait.w_next)
        mywait.w_next->w_prev = &mywait;
    wchan->w_next = &mywait;

    (void) mutex_lock(&ctx->stats_mutex);
    ctx->stats.wait_count++;
    (void) mutex_unlock(&ctx->stats_mutex);

    while (!mywait.w_signaled)
        (void) cond_wait(&(mywait.w_waitcv), &nscdb->db_mutex);
    if (mywait.w_prev)
        mywait.w_prev->w_next = mywait.w_next;
    if (mywait.w_next)
        mywait.w_next->w_prev = mywait.w_prev;
    return (0);
}

int
nscd_signal(nsc_ctx_t *ctx, nsc_db_t *nscdb, nsc_entry_t *entry)
{
    int     c = 0;
    waiter_t    *wchan = &nscdb->db_wait;
    waiter_t    *tmp = wchan->w_next;

    while (tmp) {
        if (tmp->w_key == entry) {
            (void) cond_signal(&(tmp->w_waitcv));
            tmp->w_signaled = 1;

            (void) mutex_lock(&ctx->stats_mutex);
            ctx->stats.wait_count--;
            (void) mutex_unlock(&ctx->stats_mutex);
            c++;
        }
        tmp = tmp->w_next;
    }

    return (c);
}