apr-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Aaron Bannert <aa...@clove.org>
Subject [PATCH] apr_thread_rwlock_t new API and implementation
Date Wed, 05 Sep 2001 20:50:34 GMT
This is the second patch in a series that each implement a piece of the
new APR lock API. This particular patch implements thread-based read/write
locks. Like the previous similar patch, two things must happen to apply:
1) apply the attached "patch", and 2) add the files in the attached tar
file (again, this was done to preserve the file structure, since many
of the filenames are the same).


I've included inline the "important" files for UNIX that implement this,
as the other files are stubs (to keep us building on other platforms). This
will also allow public review/discussion on the proposed patch.

-aaron


------------------------------------------------------------
Public Header: apr_thread_rwlock.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_RWLOCK_H
#define APR_THREAD_RWLOCK_H

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

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

#if APR_HAS_THREADS

/**
 * @file apr_lock.h
 * @brief APR Thread RWLock Routines
 */

/**
 * @defgroup APR_ThreadRWLock Thread RWLock Routines
 * @ingroup APR
 * @{
 */

typedef struct apr_thread_rwlock_t apr_thread_rwlock_t;

/**
 * Create and initialize a read-write lock that can be used to synchronize
 * threads.
 * @param rwlock the memory address where the newly created readwrite lock
 *        will be stored.
 * @param pool the pool from which to allocate the mutex.
 */
APR_DECLARE(apr_status_t) apr_thread_rwlock_create(apr_thread_rwlock_t **rwlock,
                                                   apr_pool_t *pool);
/**
 * Acquire a shared-read lock on the given read-write lock. This will allow
 * multiple threads to enter the same critical section while they have acquired
 * the read lock.
 * @param rwlock the read-write lock on which to acquire the shared read.
 */
APR_DECLARE(apr_status_t) apr_thread_rwlock_rdlock(apr_thread_rwlock_t *rwlock);

/**
 * Attempt to acquire the shread-read lock on the given read-write lock. This
 * is the same as apr_thread_rwlock_rdlock(), only that the funtion fails
 * if there is another thread holding the write lock, or if there are any
 * write threads blocking on the lock. If the function failes for this case,
 * APR_EBUSY will be returned. Note: it is important that the
 * APR_STATUS_IS_EBUSY(s) macro be used to determine if the return value was
 * APR_EBUSY, for portability reasons.
 * @param rwlock the rwlock on which to attempt the shared read.
 */
APR_DECLARE(apr_status_t) apr_thread_rwlock_tryrdlock(apr_thread_rwlock_t *rwlock);

/**
 * Acquire an exclusive-write lock on the given read-write lock. This will
 * allow only one single thread to enter the critical sections. If there
 * are any threads currently holding thee read-lock, this thread is put to
 * sleep until it can have exclusive access to the lock.
 * @param rwlock the read-write lock on which to acquire the exclusive write.
 */
APR_DECLARE(apr_status_t) apr_thread_rwlock_wrlock(apr_thread_rwlock_t *rwlock);

/**
 * Attempt to acquire the exclusive-write lock on the given read-write lock. 
 * This is the same as apr_thread_rwlock_wrlock(), only that the funtion fails
 * if there is any other thread holding the lock (for reading or writing),
 * in which case the function will return APR_EBUSY. Note: it is important
 * that the APR_STATUS_IS_EBUSY(s) macro be used to determine if the return
 * value was APR_EBUSY, for portability reasons.
 * @param rwlock the rwlock on which to attempt the exclusive write.
 */
APR_DECLARE(apr_status_t) apr_thread_rwlock_trywrlock(apr_thread_rwlock_t *rwlock);

/**
 * Release either the read or write lock currently held by the calling thread
 * associated with the given read-write lock.
 * @param rwlock the read-write lock rom which to release the lock.
 */
APR_DECLARE(apr_status_t) apr_thread_rwlock_unlock(apr_thread_rwlock_t *rwlock);

/**
 * Destroy the read-write lock and free the associated memory.
 * @param rwlock the rwlock to destroy.
 */
APR_DECLARE(apr_status_t) apr_thread_rwlock_destroy(apr_thread_rwlock_t *rwlock);

#endif  /* APR_HAS_THREADS */

#ifdef __cplusplus
}
#endif

#endif  /* ! APR_THREAD_RWLOCK_H */




------------------------------------------------------------
Private Header (for UNIX): thread_rwlock.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_RWLOCK_H
#define THREAD_RWLOCK_H

#include "apr.h"
#include "apr_private.h"
#include "apr_general.h"
#include "apr_thread_rwlock.h"
#include "apr_pools.h"

#if APR_HAVE_PTHREAD_H
/* this gives us pthread_rwlock_t */
#include <pthread.h>
#endif

#if APR_HAS_THREADS
struct apr_thread_rwlock_t {
    apr_pool_t *pool;
    pthread_rwlock_t *rwlock;
};
#endif

#endif  /* THREAD_RWLOCK_H */



------------------------------------------------------------
Private Implementation (for UNIX): thread_rwlock.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_rwlock.h"

#if APR_HAS_THREADS

static apr_status_t thread_rwlock_cleanup(void *data)
{
    apr_thread_rwlock_t *rwlock = (apr_thread_rwlock_t *)data;
    apr_status_t stat;

    pthread_rwlock_unlock(rwlock->rwlock);
    stat = pthread_rwlock_destroy(rwlock->rwlock);
#ifdef PTHREAD_SETS_ERRNO
    if (stat) {
        stat = errno;
    }
#endif
    return stat;
} 

APR_DECLARE(apr_status_t) apr_thread_rwlock_create(apr_thread_rwlock_t **rwlock,
                                                   apr_pool_t *pool)
{
    apr_thread_rwlock_t *new_rwlock;
    apr_status_t stat;

    new_rwlock = (apr_thread_rwlock_t *)apr_pcalloc(pool,
                                                  sizeof(apr_thread_rwlock_t));

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

    new_rwlock->pool = pool;
    new_rwlock->rwlock = (pthread_rwlock_t *)apr_palloc(pool, 
                                                     sizeof(pthread_rwlock_t));

    if (new_rwlock->rwlock == NULL) {
        return APR_ENOMEM;
    }

    if ((stat = pthread_rwlock_init(new_rwlock->rwlock, NULL))) {
#ifdef PTHREAD_SETS_ERRNO
        stat = errno;
#endif
        thread_rwlock_cleanup(new_rwlock);
        return stat;
    }

    apr_pool_cleanup_register(new_rwlock->pool,
                              (void *)new_rwlock, thread_rwlock_cleanup,
                              apr_pool_cleanup_null);

    *rwlock = new_rwlock;
    return APR_SUCCESS;
}

APR_DECLARE(apr_status_t) apr_thread_rwlock_rdlock(apr_thread_rwlock_t *rwlock)
{
    apr_status_t stat;

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

APR_DECLARE(apr_status_t) apr_thread_rwlock_tryrdlock(apr_thread_rwlock_t *rwlock)
{
    apr_status_t stat;

    stat = pthread_rwlock_tryrdlock(rwlock->rwlock);
#ifdef PTHREAD_SETS_ERRNO
    if (stat) {
        stat = errno;
    }
#endif
    /* Normalize the return code. */
    if (stat == EBUSY)
        stat = APR_EBUSY;
    return stat;
}

APR_DECLARE(apr_status_t) apr_thread_rwlock_wrlock(apr_thread_rwlock_t *rwlock)
{
    apr_status_t stat;

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

APR_DECLARE(apr_status_t) apr_thread_rwlock_trywrlock(apr_thread_rwlock_t *rwlock)
{
    apr_status_t stat;

    stat = pthread_rwlock_trywrlock(rwlock->rwlock);
#ifdef PTHREAD_SETS_ERRNO
    if (stat) {
        stat = errno;
    }
#endif
    /* Normalize the return code. */
    if (stat == EBUSY)
        stat = APR_EBUSY;
    return stat;
}

APR_DECLARE(apr_status_t) apr_thread_rwlock_unlock(apr_thread_rwlock_t *rwlock)
{
    apr_status_t stat;

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

APR_DECLARE(apr_status_t) apr_thread_rwlock_destroy(apr_thread_rwlock_t *rwlock)
{
    apr_status_t stat;
    if ((stat = thread_rwlock_cleanup(rwlock)) == APR_SUCCESS) {
        apr_pool_cleanup_kill(rwlock->pool, rwlock, thread_rwlock_cleanup);
        return APR_SUCCESS;
    }
    return stat;
}

#endif /* APR_HAS_THREADS */

Mime
View raw message