Add condition variables to the APR set of locking functions.

This does Unix, and provides stubs for all other platforms.

Submitted by:	Aaron Bannert <aaron@clove.org>


git-svn-id: http://svn.apache.org/repos/asf/apr/apr/trunk@62317 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 136 insertions, 0 deletions

diff --git a/include/apr_thread_cond.h b/include/apr_thread_cond.h
new file mode 100644
index 000000000..9a12e4f1a
--- /dev/null
+++ b/include/apr_thread_cond.h
@@ -0,0 +1,136 @@
+/* ====================================================================
+ * 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
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+ *    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 */