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/lib/classes/lock/ -> postgres_lock_factory.php (source)
Differences Between: [Versions 39 and 402] [Versions 402 and 403]
Postgres advisory locking factory.
| Copyright: | Damyon Wiese 2013 |
| License: | http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later |
| File Size: | 233 lines (8 kb) |
| Included or required: | 0 times |
| Referenced: | 0 times |
| Includes or requires: | 0 files |
Defines 1 class
postgres_lock_factory:: (11 methods):
get_unique_db_instance_id()
__construct()
is_available()
supports_timeout()
supports_auto_release()
supports_recursion()
get_index_from_key()
get_lock()
release_lock()
extend_lock()
auto_release()
Class: postgres_lock_factory - X-Ref
Postgres advisory locking factory.Postgres locking implementation using advisory locks. Some important points. Postgres has
2 different forms of lock functions, some accepting a single int, and some accepting 2 ints. This implementation
uses the 2 int version so that it uses a separate namespace from the session locking. The second note,
is because postgres uses integer keys for locks, we first need to map strings to a unique integer. This is done
using a prefix of a sha1 hash converted to an integer.
| get_unique_db_instance_id() X-Ref |
| Calculate a unique instance id based on the database name and prefix. return: int. |
| __construct($type) X-Ref |
| Almighty constructor. param: string $type - Used to prefix lock keys. |
| is_available() X-Ref |
| Is available. return: boolean - True if this lock type is available in this environment. |
| supports_timeout() X-Ref |
| Return information about the blocking behaviour of the lock type on this platform. return: boolean - Defer to the DB driver. |
| supports_auto_release() X-Ref |
| Will this lock type will be automatically released when a process ends. return: boolean - Via shutdown handler. |
| supports_recursion() X-Ref |
| Multiple locks for the same resource can NOT be held by a single process. return: boolean - false. |
| get_index_from_key($key) X-Ref |
| This function generates the unique index for a specific lock key using a sha1 prefix converted to decimal. param: string $key return: int |
| get_lock($resource, $timeout, $maxlifetime = 86400) X-Ref |
| Create and get a lock param: string $resource - The identifier for the lock. Should use frankenstyle prefix. param: int $timeout - The number of seconds to wait for a lock before giving up. param: int $maxlifetime - Unused by this lock type. return: boolean - true if a lock was obtained. |
| release_lock(lock $lock) X-Ref |
| Release a lock that was previously obtained with @lock. param: lock $lock - a lock obtained from this factory. return: boolean - true if the lock is no longer held (including if it was never held). |
| extend_lock(lock $lock, $maxlifetime = 86400) X-Ref |
| Extend a lock that was previously obtained with @lock. param: lock $lock - a lock obtained from this factory. param: int $maxlifetime - the new lifetime for the lock (in seconds). return: boolean - true if the lock was extended. |
| auto_release() X-Ref |
| Auto release any open locks on shutdown. This is required, because we may be using persistent DB connections. |
