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/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2016, Fairview 5 Engineering, LLC
*
* George Joseph <george.joseph@fairview5.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 Named Locks
*
* \author George Joseph <george.joseph@fairview5.com>
*/
#ifndef INCLUDE_ASTERISK_NAMED_LOCKS_H_
#define INCLUDE_ASTERISK_NAMED_LOCKS_H_
#include "asterisk/astobj2.h"
/*!
* \defgroup named_locks Named mutex and read-write locks
* @{
* \page NamedLocks Named mutex and read-write locks
* \since 13.9.0
*
* Locking some objects like sorcery objects can be tricky because the underlying
* ao2 object may not be the same for all callers. For instance, two threads that
* call ast_sorcery_retrieve_by_id on the same aor name might actually get 2 different
* ao2 objects if the underlying wizard had to rehydrate the aor from a database.
* Locking one ao2 object doesn't have any effect on the other even if those objects
* had locks in the first place
*
* Named locks allow access control by name. Now an aor named "1000" can be locked and
* any other thread attempting to lock the aor named "1000" will wait regardless of whether
* the underlying ao2 object is the same or not.
*
* To use a named lock:
* Call ast_named_lock_get with the appropriate keyspace and key.
* Use the standard ao2 lock/unlock functions as needed.
* Call ao2_cleanup when you're finished with it.
*/
/*!
* \brief Which type of lock to request.
*/
enum ast_named_lock_type {
/*! Request a named mutex. */
AST_NAMED_LOCK_TYPE_MUTEX = AO2_ALLOC_OPT_LOCK_MUTEX,
/*! Request a named read/write lock. */
AST_NAMED_LOCK_TYPE_RWLOCK = AO2_ALLOC_OPT_LOCK_RWLOCK,
};
struct ast_named_lock;
struct ast_named_lock *__ast_named_lock_get(const char *filename, int lineno, const char *func,
enum ast_named_lock_type lock_type, const char *keyspace, const char *key);
/*!
* \brief Geta named lock handle
* \since 13.9.0
*
* \param lock_type One of ast_named_lock_type
* \param keyspace
* \param key
* \retval A pointer to an ast_named_lock structure
* \retval NULL on error
*
* \note
* keyspace and key can be anything. For sorcery objects, keyspace could be the object type
* and key could be the object id.
*/
#define ast_named_lock_get(lock_type, keyspace, key) \
__ast_named_lock_get(__FILE__, __LINE__, __PRETTY_FUNCTION__, lock_type, \
keyspace, key)
/*!
* \brief Put a named lock handle away
* \since 13.9.0
*
* \param lock The pointer to the ast_named_lock structure returned by ast_named_lock_get
*/
#define ast_named_lock_put(lock) ao2_cleanup(lock)
/*!
* @}
*/
#endif /* INCLUDE_ASTERISK_NAMED_LOCKS_H_ */
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