Asterisk - The Open Source Telephony Project  GIT-master-a24979a
named_locks.h
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1 /*
2  * Asterisk -- An open source telephony toolkit.
3  *
4  * Copyright (C) 2016, Fairview 5 Engineering, LLC
5  *
6  * George Joseph <george.joseph@fairview5.com>
7  *
8  * See http://www.asterisk.org for more information about
9  * the Asterisk project. Please do not directly contact
10  * any of the maintainers of this project for assistance;
11  * the project provides a web site, mailing lists and IRC
12  * channels for your use.
13  *
14  * This program is free software, distributed under the terms of
15  * the GNU General Public License Version 2. See the LICENSE file
16  * at the top of the source tree.
17  */
18 
19 /*! \file
20  *
21  * \brief Named Locks
22  *
23  * \author George Joseph <george.joseph@fairview5.com>
24  */
25 
26 #ifndef INCLUDE_ASTERISK_NAMED_LOCKS_H_
27 #define INCLUDE_ASTERISK_NAMED_LOCKS_H_
28 
29 #include "asterisk/astobj2.h"
30 
31 /*!
32  * \defgroup named_locks Named mutex and read-write locks
33  * @{
34  * \page NamedLocks Named mutex and read-write locks
35  * \since 13.9.0
36  *
37  * Locking some objects like sorcery objects can be tricky because the underlying
38  * ao2 object may not be the same for all callers. For instance, two threads that
39  * call ast_sorcery_retrieve_by_id on the same aor name might actually get 2 different
40  * ao2 objects if the underlying wizard had to rehydrate the aor from a database.
41  * Locking one ao2 object doesn't have any effect on the other even if those objects
42  * had locks in the first place
43  *
44  * Named locks allow access control by name. Now an aor named "1000" can be locked and
45  * any other thread attempting to lock the aor named "1000" will wait regardless of whether
46  * the underlying ao2 object is the same or not.
47  *
48  * To use a named lock:
49  * Call ast_named_lock_get with the appropriate keyspace and key.
50  * Use the standard ao2 lock/unlock functions as needed.
51  * Call ao2_cleanup when you're finished with it.
52  */
53 
54 /*!
55  * \brief Which type of lock to request.
56  */
58  /*! Request a named mutex. */
60  /*! Request a named read/write lock. */
62 };
63 
64 struct ast_named_lock;
65 
66 struct ast_named_lock *__ast_named_lock_get(const char *filename, int lineno, const char *func,
67  enum ast_named_lock_type lock_type, const char *keyspace, const char *key);
68 
69 /*!
70  * \brief Geta named lock handle
71  * \since 13.9.0
72  *
73  * \param lock_type One of ast_named_lock_type
74  * \param keyspace
75  * \param key
76  * \retval A pointer to an ast_named_lock structure
77  * \retval NULL on error
78  *
79  * \note
80  * keyspace and key can be anything. For sorcery objects, keyspace could be the object type
81  * and key could be the object id.
82  */
83 #define ast_named_lock_get(lock_type, keyspace, key) \
84  __ast_named_lock_get(__FILE__, __LINE__, __PRETTY_FUNCTION__, lock_type, \
85  keyspace, key)
86 
87 /*!
88  * \brief Put a named lock handle away
89  * \since 13.9.0
90  *
91  * \param lock The pointer to the ast_named_lock structure returned by ast_named_lock_get
92  */
93 #define ast_named_lock_put(lock) ao2_cleanup(lock)
94 
95 /*!
96  * @}
97  */
98 
99 #endif /* INCLUDE_ASTERISK_NAMED_LOCKS_H_ */
@ AO2_ALLOC_OPT_LOCK_RWLOCK
Definition: astobj2.h:365
@ AO2_ALLOC_OPT_LOCK_MUTEX
Definition: astobj2.h:363
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)
Definition: named_locks.c:70
ast_named_lock_type
Which type of lock to request.
Definition: named_locks.h:57
@ AST_NAMED_LOCK_TYPE_RWLOCK
Definition: named_locks.h:61
@ AST_NAMED_LOCK_TYPE_MUTEX
Definition: named_locks.h:59