Add func_lock, which creates dialplan mutexes, and note that the Macro apps are now deprecated.

(Closes issue #10264)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@77834 65c4cc65-6c06-0410-ace0-fbb531ad65f3

UPGRADE.txt

@@ -71,6 +71,11 @@ Applications:
 * DISA()'s fifth argument is now an options argument.  If you have previously
   used 'NOANSWER' in this argument, you'll need to convert that to the new
   option 'n'.
+* Macro() is now deprecated.  If you need subroutines, you should use the
+  Gosub()/Return() applications.  To replace MacroExclusive(), we have
+  introduced dialplan functions LOCK(), TRYLOCK(), and UNLOCK().  You may use
+  these functions in any location where you desire to ensure that only one
+  channel is executing that path at any one time.
 
 CDR:
 

funcs/func_lock.c

@@ -0,0 +1,247 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2007, Tilghman Lesher
+ *
+ * Tilghman Lesher <func_lock_2007@the-tilghman.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ *
+ * \brief Dialplan mutexes
+ *
+ * \author Tilghman Lesher <func_lock_2007@the-tilghman.com>
+ *
+ * \ingroup functions
+ * 
+ */
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "asterisk/lock.h"
+#include "asterisk/file.h"
+#include "asterisk/logger.h"
+#include "asterisk/options.h"
+#include "asterisk/channel.h"
+#include "asterisk/pbx.h"
+#include "asterisk/module.h"
+#include "asterisk/options.h"
+#include "asterisk/linkedlists.h"
+
+AST_LIST_HEAD_STATIC(locklist, lock_frame);
+
+static void lock_free(void *data);
+static int unloading = 0;
+
+static struct ast_datastore_info lock_info = {
+	.type = "MUTEX",
+	.destroy = lock_free,
+};
+
+struct lock_frame {
+	AST_LIST_ENTRY(lock_frame) entries;
+	ast_mutex_t mutex;
+	struct ast_channel *channel;
+	char name[0];
+};
+
+static void lock_free(void *data)
+{
+	struct lock_frame *frame = data;
+	if (!frame)
+		return;
+	frame->channel = NULL;
+	ast_mutex_unlock(&frame->mutex);
+}
+
+static int get_lock(struct ast_channel *chan, char *lockname, int try)
+{
+	struct ast_datastore *lock_store = ast_channel_datastore_find(chan, &lock_info, NULL);
+	struct lock_frame *current;
+	int res;
+
+	if (!lock_store) {
+		ast_debug(1, "Channel %s has no lock datastore, so we're allocating one.\n", chan->name);
+		lock_store = ast_channel_datastore_alloc(&lock_info, NULL);
+		if (!lock_store) {
+			ast_log(LOG_ERROR, "Unable to allocate new datastore.  No locks will be obtained.\n");
+			return -1;
+		}
+		ast_channel_datastore_add(chan, lock_store);
+	}
+
+	/* If the channel already has a lock, then free the existing lock */
+	if (lock_store->data) {
+		struct lock_frame *old = lock_store->data;
+		old->channel = NULL;
+		ast_mutex_unlock(&old->mutex);
+	}
+
+	/* Lock already exist? */
+	AST_LIST_LOCK(&locklist);
+	AST_LIST_TRAVERSE(&locklist, current, entries) {
+		if (strcmp(current->name, lockname) == 0) {
+			break;
+		}
+	}
+
+	if (!current) {
+		if (unloading) {
+			/* Don't bother */
+			AST_LIST_UNLOCK(&locklist);
+			return -1;
+		}
+
+		/* Create new lock entry */
+		current = ast_calloc(1, sizeof(*current) + strlen(lockname) + 1);
+		if (!current) {
+			AST_LIST_UNLOCK(&locklist);
+			return -1;
+		}
+
+		strcpy((char *)current + sizeof(*current), lockname);
+		ast_mutex_init(&current->mutex);
+		AST_LIST_INSERT_TAIL(&locklist, current, entries);
+	}
+
+	res = try ? ast_mutex_trylock(&current->mutex) : ast_mutex_lock(&current->mutex);
+	if (res == 0) {
+		lock_store->data = current;
+		current->channel = chan;
+	}
+
+	AST_LIST_UNLOCK(&locklist);
+	return res;
+}
+
+static int unlock_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
+{
+	struct ast_datastore *lock_store = ast_channel_datastore_find(chan, &lock_info, NULL);
+	struct lock_frame *current;
+
+	if (!lock_store) {
+		ast_log(LOG_WARNING, "No datastore for dialplan locks.  Nothing was ever locked!\n");
+		ast_copy_string(buf, "0", len);
+		return 0;
+	}
+
+	current = lock_store->data;
+
+	if (!current) {
+		ast_copy_string(buf, "0", len);
+		return 0;
+	}
+
+	current->channel = NULL;
+	ast_mutex_unlock(&current->mutex);
+	ast_copy_string(buf, "1", len);
+	return 0;
+}
+
+static int lock_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
+{
+	ast_copy_string(buf, get_lock(chan, data, 0) ? "0" : "1", len);
+	return 0;
+}
+
+static int trylock_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
+{
+	ast_copy_string(buf, get_lock(chan, data, 1) ? "0" : "1", len);
+	return 0;
+}
+
+static struct ast_custom_function lock_function = {
+	.name = "LOCK",
+	.synopsis = "Attempt to obtain a named mutex",
+	.desc =
+"Attempts to grab a named lock exclusively, and prevents other channels\n"
+"from obtaining the same lock.  LOCK will wait for the lock to become\n"
+"available.  Returns 1 if the lock was obtained or 0 on error.\n\n"
+"Note: to avoid the possibility of a deadlock, LOCK will only attempt to\n"
+"grab a single lock.  If you have a lock already and you attempt to lock\n"
+"another name, LOCK will unlock the first name before attempting to lock\n"
+"the second name.\n",
+	.syntax = "LOCK(<lockname>)",
+	.read = lock_read,
+};
+
+static struct ast_custom_function trylock_function = {
+	.name = "TRYLOCK",
+	.synopsis = "Attempt to obtain a named mutex",
+	.desc =
+"Attempts to grab a named lock exclusively, and prevents other channels\n"
+"from obtaining the same lock.  Returns 1 if the lock was available or 0\n"
+"otherwise.\n\n"
+"Note: to avoid the possibility of a deadlock, TRYLOCK will only attempt to\n"
+"grab a single lock.  If you have a lock already and you attempt to lock\n"
+"another name, TRYLOCK will unlock the first name before attempting to lock\n"
+"the second name.\n",
+	.syntax = "TRYLOCK(<lockname>)",
+	.read = trylock_read,
+};
+
+static struct ast_custom_function unlock_function = {
+	.name = "UNLOCK",
+	.synopsis = "Unlocks a named mutex",
+	.desc =
+"Unlocks a previously locked mutex.  Returns 1 if the channel had a lock\n"
+"or 0 otherwise.\n",
+	.syntax = "UNLOCK()",
+	.read = unlock_read,
+};
+
+static int unload_module(void)
+{
+	struct lock_frame *current;
+
+	/* Module flag */
+	unloading = 1;
+
+	AST_LIST_LOCK(&locklist);
+	while ((current = AST_LIST_REMOVE_HEAD(&locklist, entries))) {
+		/* If any locks are currently in use, then we cannot unload this module */
+		if (current->channel) {
+			/* Put it back */
+			AST_LIST_INSERT_HEAD(&locklist, current, entries);
+			AST_LIST_UNLOCK(&locklist);
+			unloading = 0;
+			return -1;
+		}
+		ast_mutex_destroy(&current->mutex);
+		ast_free(current);
+	}
+
+	/* No locks left, unregister functions */
+	ast_custom_function_unregister(&lock_function);
+	ast_custom_function_unregister(&trylock_function);
+	ast_custom_function_unregister(&unlock_function);
+
+	AST_LIST_UNLOCK(&locklist);
+	return 0;
+}
+
+static int load_module(void)
+{
+	int res = ast_custom_function_register(&lock_function);
+	res |= ast_custom_function_register(&trylock_function);
+	res |= ast_custom_function_register(&unlock_function);
+	return res;
+}
+
+AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Dialplan mutexes");