Merge "lock: Add named lock capability"

include/asterisk/_private.h

@@ -39,6 +39,7 @@ int ast_dns_system_resolver_init(void); /*!< Provided by dns_system_resolver.c *
 void threadstorage_init(void);		/*!< Provided by threadstorage.c */
 int ast_device_state_engine_init(void);	/*!< Provided by devicestate.c */
 int astobj2_init(void);			/*!< Provided by astobj2.c */
+int ast_named_locks_init(void);		/*!< Provided by named_locks.c */
 int ast_file_init(void);		/*!< Provided by file.c */
 int ast_features_init(void);            /*!< Provided by features.c */
 void ast_autoservice_init(void);	/*!< Provided by autoservice.c */

include/asterisk/named_locks.h

@@ -0,0 +1,105 @@
+/*
+ * 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 ast_named_lock_put 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);
+
+int __ast_named_lock_put(const char *filename, int lineno, const char *func,
+	struct ast_named_lock *lock);
+
+/*!
+ * \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
+ * \retval 0 Success
+ * \retval -1 Failure
+ */
+#define ast_named_lock_put(lock) \
+	__ast_named_lock_put(__FILE__, __LINE__, __PRETTY_FUNCTION__, lock)
+
+/*!
+ * @}
+ */
+
+#endif /* INCLUDE_ASTERISK_NAMED_LOCKS_H_ */