diff options
| -rw-r--r-- | UPGRADE.txt | 5 | ||||
| -rw-r--r-- | funcs/func_lock.c | 247 |
2 files changed, 252 insertions, 0 deletions
diff --git a/UPGRADE.txt b/UPGRADE.txt index 16b177783..034ecaf30 100644 --- a/UPGRADE.txt +++ b/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: diff --git a/funcs/func_lock.c b/funcs/func_lock.c new file mode 100644 index 000000000..477f1c1aa --- /dev/null +++ b/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(¤t->mutex); + AST_LIST_INSERT_TAIL(&locklist, current, entries); + } + + res = try ? ast_mutex_trylock(¤t->mutex) : ast_mutex_lock(¤t->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(¤t->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(¤t->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"); |