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131baf70d6
This allows standard ao2 functions to be used to release references to an ast_named_lock. This change can cause less frequent locking of the global named_locks container. The container is no longer locked when a named_lock reference is being release except when this causes the named_lock to be destroyed. Change-Id: I644e39c6d83a153d71b3fae77ec05599d725e7e6
100 lines
3.0 KiB
C
100 lines
3.0 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2016, Fairview 5 Engineering, LLC
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*
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* George Joseph <george.joseph@fairview5.com>
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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*
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* \brief Named Locks
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*
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* \author George Joseph <george.joseph@fairview5.com>
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*/
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#ifndef INCLUDE_ASTERISK_NAMED_LOCKS_H_
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#define INCLUDE_ASTERISK_NAMED_LOCKS_H_
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#include "asterisk/astobj2.h"
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/*!
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* \defgroup named_locks Named mutex and read-write locks
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* @{
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* \page NamedLocks Named mutex and read-write locks
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* \since 13.9.0
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*
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* Locking some objects like sorcery objects can be tricky because the underlying
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* ao2 object may not be the same for all callers. For instance, two threads that
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* call ast_sorcery_retrieve_by_id on the same aor name might actually get 2 different
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* ao2 objects if the underlying wizard had to rehydrate the aor from a database.
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* Locking one ao2 object doesn't have any effect on the other even if those objects
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* had locks in the first place
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*
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* Named locks allow access control by name. Now an aor named "1000" can be locked and
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* any other thread attempting to lock the aor named "1000" will wait regardless of whether
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* the underlying ao2 object is the same or not.
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*
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* To use a named lock:
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* Call ast_named_lock_get with the appropriate keyspace and key.
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* Use the standard ao2 lock/unlock functions as needed.
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* Call ao2_cleanup when you're finished with it.
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*/
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/*!
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* \brief Which type of lock to request.
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*/
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enum ast_named_lock_type {
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/*! Request a named mutex. */
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AST_NAMED_LOCK_TYPE_MUTEX = AO2_ALLOC_OPT_LOCK_MUTEX,
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/*! Request a named read/write lock. */
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AST_NAMED_LOCK_TYPE_RWLOCK = AO2_ALLOC_OPT_LOCK_RWLOCK,
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};
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struct ast_named_lock;
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struct ast_named_lock *__ast_named_lock_get(const char *filename, int lineno, const char *func,
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enum ast_named_lock_type lock_type, const char *keyspace, const char *key);
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/*!
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* \brief Geta named lock handle
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* \since 13.9.0
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*
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* \param lock_type One of ast_named_lock_type
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* \param keyspace
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* \param key
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* \retval A pointer to an ast_named_lock structure
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* \retval NULL on error
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*
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* \note
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* keyspace and key can be anything. For sorcery objects, keyspace could be the object type
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* and key could be the object id.
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*/
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#define ast_named_lock_get(lock_type, keyspace, key) \
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__ast_named_lock_get(__FILE__, __LINE__, __PRETTY_FUNCTION__, lock_type, \
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keyspace, key)
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/*!
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* \brief Put a named lock handle away
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* \since 13.9.0
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*
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* \param lock The pointer to the ast_named_lock structure returned by ast_named_lock_get
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*/
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#define ast_named_lock_put(lock) ao2_cleanup(lock)
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/*!
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* @}
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*/
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#endif /* INCLUDE_ASTERISK_NAMED_LOCKS_H_ */
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