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From Aaron Bannert <aa...@clove.org>
Subject [PATCH] add condition variables to APR
Date Mon, 10 Sep 2001 18:57:48 GMT
This patch adds the new condition variable API to APR, a UNIX implementation
of the new API, and stub implementations on other platforms to keep us
compiling. As always with these patches lately, in order to apply one must
1) apply the attached patch (simple makefile updates), and 2) add the
files from the attached tar file.

I have included the interesting files inline for public reviewal. I will
follow this post up shortly with changes to testlock that verify the
new API implementation.

-aaron

------------------------------------------------------------
Public Header: apr_thread_cond.h


/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000-2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

#ifndef APR_THREAD_COND_H
#define APR_THREAD_COND_H

#include "apr.h"
#include "apr_pools.h"
#include "apr_errno.h"
#include "apr_thread_mutex.h"

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/**
 * @file apr_thread_cond.h
 * @brief APR Condition Variable Routines
 */

/**
 * @defgroup APR_Cond Condition Variable Routines
 * @ingroup APR
 * @{
 */

typedef struct apr_thread_cond_t apr_thread_cond_t;

/*   Function definitions */

/**
 * Create and initialize a condition variable that can be used to signal
 * and schedule threads in a single process.
 * @param cond the memory address where the newly created condition variable
 *        will be stored.
 * @param pool the pool from which to allocate the mutex.
 */
APR_DECLARE(apr_status_t) apr_thread_cond_create(apr_thread_cond_t **cond,
                                                 apr_pool_t *pool);
/**
 * Put the active calling thread to sleep until signaled to wake up. Each
 * condition variable must be associated with a mutex, and that mutex must
 * be locked before  calling this function, or the behavior will be
 * undefined. As the calling thread is put to sleep, the given mutex
 * will be simultaneously released; and as this thread wakes up the lock
 * is again simultaneously acquired.
 * @param cond the condition variable on which to block.
 * @param mutex the mutex that must be locked upon entering this function,
 *        is released while the thread is asleep, and is again acquired before
 *        returning from this function.
 */
APR_DECLARE(apr_status_t) apr_thread_cond_wait(apr_thread_cond_t *cond,
                                               apr_thread_mutex_t *mutex);

/* XXX: Should we add apr_thread_cond_timedwait()? Can it be done on all
 *      platforms? -aaron */

/**
 * Signals a singla thread, if one exists, that is blocking on the given
 * condition variable. That thread is then scheduled to wake up and acquire
 * the associated mutex. Although it is not required, if predictible schedule
 * is desired, that mutex must be locked while calling this function.
 * @param cond the condition variable on which to produce the signal.
 */
APR_DECLARE(apr_status_t) apr_thread_cond_signal(apr_thread_cond_t *cond);
/**
 * Signals all threads blocking on the given condition variable.
 * Each thread that was signaled is then schedule to wake up and acquire
 * the associated mutex. This will happen in a serialized manner.
 * @param cond the condition variable on which to produce the broadcast.
 */
APR_DECLARE(apr_status_t) apr_thread_cond_broadcast(apr_thread_cond_t *cond);

/**
 * Destroy the condition variable and free the associated memory.
 * @param cond the condition variable to destroy.
 */
APR_DECLARE(apr_status_t) apr_thread_cond_destroy(apr_thread_cond_t *cond);


#ifdef __cplusplus
}
#endif

#endif  /* ! APR_THREAD_COND_H */

------------------------------------------------------------
Private Header (UNIX): thread_cond.h


/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000-2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

#ifndef THREAD_COND_H
#define THREAD_COND_H

#include "apr.h"
#include "apr_private.h"
#include "apr_general.h"
#include "apr_lib.h"
#include "apr_thread_mutex.h"
#include "apr_thread_cond.h"
#include "apr_pools.h"

#if APR_HAVE_PTHREAD_H
#include <pthread.h>
#endif

/* XXX: Should we have a better autoconf search, something like
 * APR_HAS_PTHREAD_COND? -aaron */
#if APR_HAS_THREADS
struct apr_thread_cond_t {
    apr_pool_t *pool;
    pthread_cond_t *cond;
};
#endif

#endif  /* THREAD_COND_H */


------------------------------------------------------------
Private Implementation (UNIX): thread_cond.c



/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000-2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

#include "thread_mutex.h"
#include "thread_cond.h"

#if APR_HAS_THREADS


static apr_status_t thread_cond_cleanup(void *data)
{
    apr_thread_cond_t *cond = (apr_thread_cond_t *)data;
    apr_status_t stat;

    stat = pthread_cond_destroy(cond->cond);
#ifdef PTHREAD_SETS_ERRNO
    if (stat) {
        stat = errno;
    }
#endif
    return stat;
} 

APR_DECLARE(apr_status_t) apr_thread_cond_create(apr_thread_cond_t **cond,
                                                 apr_pool_t *pool)
{
    apr_thread_cond_t *new_cond;
    apr_status_t stat;

    new_cond = (apr_thread_cond_t *)apr_pcalloc(pool,
                                                sizeof(apr_thread_cond_t));

    if (new_cond == NULL) {
        return APR_ENOMEM;
    }

    new_cond->pool = pool;
    new_cond->cond = (pthread_cond_t *)apr_palloc(pool, 
                                                  sizeof(pthread_cond_t));

    if (new_cond->cond == NULL) {
        return APR_ENOMEM;
    }

    if ((stat = pthread_cond_init(new_cond->cond, NULL))) {
#ifdef PTHREAD_SETS_ERRNO
        stat = errno;
#endif
        thread_cond_cleanup(new_cond);
        return stat;
    }

    apr_pool_cleanup_register(new_cond->pool,
                              (void *)new_cond, thread_cond_cleanup,
                              apr_pool_cleanup_null);

    *cond = new_cond;
    return APR_SUCCESS;
}

APR_DECLARE(apr_status_t) apr_thread_cond_wait(apr_thread_cond_t *cond,
                                               apr_thread_mutex_t *mutex)
{
    apr_status_t stat;

    stat = pthread_cond_wait(cond->cond, &mutex->mutex);
#ifdef PTHREAD_SETS_ERRNO
    if (stat) {
        stat = errno;
    }
#endif
    return stat;
}

APR_DECLARE(apr_status_t) apr_thread_cond_signal(apr_thread_cond_t *cond)
{
    apr_status_t stat;

    stat = pthread_cond_signal(cond->cond);
#ifdef PTHREAD_SETS_ERRNO
    if (stat) {
        stat = errno;
    }
#endif
    return stat;
}

APR_DECLARE(apr_status_t) apr_thread_cond_broadcast(apr_thread_cond_t *cond)
{
    apr_status_t stat;

    stat = pthread_cond_broadcast(cond->cond);
#ifdef PTHREAD_SETS_ERRNO
    if (stat) {
        stat = errno;
    }
#endif
    return stat;
}

APR_DECLARE(apr_status_t) apr_thread_cond_destroy(apr_thread_cond_t *cond)
{
    apr_status_t stat;
    if ((stat = thread_cond_cleanup(cond)) == APR_SUCCESS) {
        apr_pool_cleanup_kill(cond->pool, cond, thread_cond_cleanup);
        return APR_SUCCESS;
    }
    return stat;
}


#endif /* APR_HAS_THREADS */

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