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See Release Notes

  • Bug fixes for general core bugs in 4.3.x will end 7 October 2024 (12 months).
  • Bug fixes for security issues in 4.3.x will end 21 April 2025 (18 months).
  • PHP version: minimum PHP 8.0.0 Note: minimum PHP version has increased since Moodle 4.1. PHP 8.2.x is supported too.
<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

< /** < * MySQL / MariaDB locking factory. < * < * @package core < * @category lock < * @copyright Brendan Heywood <brendan@catalyst-au.net> < * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later < */ <
namespace core\lock;
< defined('MOODLE_INTERNAL') || die();
> use coding_exception;
/** * MySQL / MariaDB locking factory. * * @package core * @category lock * @copyright Brendan Heywood <brendan@catalyst-au.net> * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later */ class mysql_lock_factory implements lock_factory { /** @var string $dbprefix - used as a namespace for these types of locks */ protected $dbprefix = ''; /** @var \moodle_database $db Hold a reference to the global $DB */ protected $db; /** @var array $openlocks - List of held locks - used by auto-release */ protected $openlocks = []; /** * Return a unique prefix based on the database name and prefix. * @param string $type - Used to prefix lock keys.
< * @return string.
> * @return string
*/ protected function get_unique_db_prefix($type) { global $CFG; $prefix = $CFG->dbname . ':'; if (isset($CFG->prefix)) { $prefix .= $CFG->prefix; } $prefix .= '_' . $type . '_'; return $prefix; } /** * Lock constructor. * @param string $type - Used to prefix lock keys. */ public function __construct($type) { global $DB; $this->dbprefix = $this->get_unique_db_prefix($type); // Save a reference to the global $DB so it will not be released while we still have open locks. $this->db = $DB; \core_shutdown_manager::register_function([$this, 'auto_release']); } /** * Is available. * @return boolean - True if this lock type is available in this environment. */ public function is_available() { return $this->db->get_dbfamily() === 'mysql'; } /** * Return information about the blocking behaviour of the lock type on this platform. * @return boolean - Defer to the DB driver. */ public function supports_timeout() { return true; } /** * Will this lock type will be automatically released when a process ends. * * @return boolean - Via shutdown handler. */ public function supports_auto_release() { return true; } /**
< * Multiple locks for the same resource can NOT be held by a single process. < * < * Hard coded to false and workaround inconsistent support in different < * versions of MySQL / MariaDB. < *
* @deprecated since Moodle 3.10.
< * @return boolean - false
*/ public function supports_recursion() {
< debugging('The function supports_recursion() is deprecated, please do not use it anymore.', < DEBUG_DEVELOPER); < return false;
> throw new coding_exception('The function supports_recursion() has been removed, please do not use it anymore.');
} /** * 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 $maxlifetime - Unused by this lock type. * @return boolean - true if a lock was obtained. */ public function get_lock($resource, $timeout, $maxlifetime = 86400) { // We sha1 to avoid long key names hitting the mysql str limit. $resourcekey = sha1($this->dbprefix . $resource); // Even though some versions of MySQL and MariaDB can support stacked locks // just never stack them and always fail fast. if (isset($this->openlocks[$resourcekey])) { return false; } $params = [ 'resourcekey' => $resourcekey, 'timeout' => $timeout ]; $result = $this->db->get_record_sql('SELECT GET_LOCK(:resourcekey, :timeout) AS locked', $params); $locked = $result->locked == 1; if ($locked) { $this->openlocks[$resourcekey] = 1; return new lock($resourcekey, $this); } return false; } /** * 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). */ public function release_lock(lock $lock) { $params = [ 'resourcekey' => $lock->get_key() ]; $result = $this->db->get_record_sql('SELECT RELEASE_LOCK(:resourcekey) AS unlocked', $params); $result = $result->unlocked == 1; if ($result) { unset($this->openlocks[$lock->get_key()]); } return $result; } /**
< * Extend a lock that was previously obtained with @lock. < *
* @deprecated since Moodle 3.10.
< * @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.
*/
< public function extend_lock(lock $lock, $maxlifetime = 86400) { < debugging('The function extend_lock() is deprecated, please do not use it anymore.', < DEBUG_DEVELOPER); < // Not supported by this factory. < return false;
> public function extend_lock() { > throw new coding_exception('The function extend_lock() has been removed, please do not use it anymore.');
} /** * Auto release any open locks on shutdown. * This is required, because we may be using persistent DB connections. */ public function auto_release() { // Called from the shutdown handler. Must release all open locks. foreach ($this->openlocks as $key => $unused) { $lock = new lock($key, $this); $lock->release(); } } }