Add a new lock API: apr_global_mutex_t

This is analog to the APR_LOCKALL method of apr_lock_t, and provides
cross-process AND cross-thread mutual exclusion.

I have provided a simple test (based on testprocmutex.c) and stubs
for non-Unix platforms.


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@63001 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 164 insertions, 0 deletions

diff --git a/include/apr_global_mutex.h b/include/apr_global_mutex.h
new file mode 100644
index 000000000..56e39bad4
--- /dev/null
+++ b/include/apr_global_mutex.h
@@ -0,0 +1,164 @@
+/* ====================================================================
+ * 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_GLOBAL_MUTEX_H
+#define APR_GLOBAL_MUTEX_H
+
+#include "apr.h"
+#include "apr_lock.h"    /* only for apr_lockmech_e_np */
+#include "apr_pools.h"
+#include "apr_errno.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/**
+ * @file apr_global_mutex.h
+ * @brief APR Global Locking Routines
+ */
+
+/**
+ * @defgroup APR_GlobalMutex Global Locking Routines
+ * @ingroup APR
+ * @{
+ */
+
+typedef struct apr_global_mutex_t apr_global_mutex_t;
+
+/*   Function definitions */
+
+/**
+ * Create and initialize a mutex that can be used to synchronize both
+ * processes and threads. Note: There is considerable overhead in using
+ * this API if only cross-process or cross-thread mutual exclusion is
+ * required. See apr_proc_mutex.h and apr_thread_mutex.h for more
+ * specialized lock routines.
+ * @param mutex the memory address where the newly created mutex will be
+ *        stored.
+ * @param fname A file name to use if the lock mechanism requires one.  This
+ *        argument should always be provided.  The lock code itself will
+ *        determine if it should be used.
+ * @param mech The mechanism to use for the interprocess lock, if any; one of
+ * <PRE>
+ *            APR_LOCK_FCNTL
+ *            APR_LOCK_FLOCK
+ *            APR_LOCK_SYSVSEM
+ *            APR_LOCK_PROC_PTHREAD
+ *            APR_LOCK_DEFAULT     pick the default mechanism for the platform
+ * </PRE>
+ * @param pool the pool from which to allocate the mutex.
+ * @warning Check APR_HAS_foo_SERIALIZE defines to see if the platform supports
+ *          APR_LOCK_foo.  Only APR_LOCK_DEFAULT is portable.
+ */
+APR_DECLARE(apr_status_t) apr_global_mutex_create(apr_global_mutex_t **mutex,
+                                                  const char *fname,
+                                                  apr_lockmech_e mech,
+                                                  apr_pool_t *pool);
+
+/**
+ * Re-open a mutex in a child process.
+ * @param mutex The newly re-opened mutex structure.
+ * @param fname A file name to use if the mutex mechanism requires one.  This
+ *              argument should always be provided.  The mutex code itself will
+ *              determine if it should be used.  This filename should be the 
+ *              same one that was passed to apr_global_mutex_create().
+ * @param pool The pool to operate on.
+ * @remark This function must be called to maintain portability, even
+ *         if the underlying lock mechanism does not require it.
+ */
+APR_DECLARE(apr_status_t) apr_global_mutex_child_init(
+                              apr_global_mutex_t **mutex,
+                              const char *fname,
+                              apr_pool_t *pool);
+
+/**
+ * Acquire the lock for the given mutex. If the mutex is already locked,
+ * the current thread will be put to sleep until the lock becomes available.
+ * @param mutex the mutex on which to acquire the lock.
+ */
+APR_DECLARE(apr_status_t) apr_global_mutex_lock(apr_global_mutex_t *mutex);
+
+/**
+ * Attempt to acquire the lock for the given mutex. If the mutex has already
+ * been acquired, the call returns immediately with 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 mutex the mutex on which to attempt the lock acquiring.
+ */
+APR_DECLARE(apr_status_t) apr_global_mutex_trylock(apr_global_mutex_t *mutex);
+
+/**
+ * Release the lock for the given mutex.
+ * @param mutex the mutex from which to release the lock.
+ */
+APR_DECLARE(apr_status_t) apr_global_mutex_unlock(apr_global_mutex_t *mutex);
+
+/**
+ * Destroy the mutex and free the memory associated with the lock.
+ * @param mutex the mutex to destroy.
+ */
+APR_DECLARE(apr_status_t) apr_global_mutex_destroy(apr_global_mutex_t *mutex);
+
+/**
+ * Get the pool used by this global_mutex.
+ * @return apr_pool_t the pool
+ */
+APR_POOL_DECLARE_ACCESSOR(global_mutex);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* ndef APR_GLOBAL_MUTEX_H */