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See Release Notes

  • Bug fixes for general core bugs in 4.2.x will end 22 April 2024 (12 months).
  • Bug fixes for security issues in 4.2.x will end 7 October 2024 (18 months).
  • PHP version: minimum PHP 8.0.0 Note: minimum PHP version has increased since Moodle 4.1. PHP 8.1.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/>.

/**
 * Class representing a lock
 *
 * The methods available for a specific lock type are only known by it's factory.
 *
 * @package    core
 * @copyright  Damyon Wiese 2013
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

namespace core\lock;

defined('MOODLE_INTERNAL') || die();

/**
 * Class representing a lock
 *
 * The methods available for a specific lock type are only known by it's factory.
 *
 * @package   core
 * @category  lock
 * @copyright Damyon Wiese 2013
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class lock {

    /** @var string|int $key A unique key representing a held lock */
    protected $key = '';

    /** @var lock_factory $factory The factory that generated this lock */
    protected $factory;

    /** @var bool $released Has this lock been released? If a lock falls out of scope without being released - show a warning. */
    protected $released;

    /** @var string $caller Where was this called from? Stored for when a warning is shown */
    protected $caller = 'unknown';

    /**
     * Construct a lock containing the unique key required to release it.
     * @param mixed $key - The lock key. The type of this is up to the lock_factory being used.
     *      For file locks this is a file handle. For MySQL this is a string.
     * @param lock_factory $factory - The factory that generated this lock.
     */
    public function __construct($key, $factory) {
        $this->factory = $factory;
        $this->key = $key;
        $this->released = false;
        $caller = debug_backtrace(true, 2)[1];
        if ($caller && array_key_exists('file', $caller ) ) {
            $this->caller = $caller['file'] . ' on line ' . $caller['line'];
        } else if ($caller && array_key_exists('class', $caller)) {
            $this->caller = $caller['class'] . $caller['type'] . $caller['function'];
        }
    }

    /**
> * Sets the lock factory that owns a lock. This function should not be called under normal use. * Return the unique key representing this lock. > * It is intended only for cases like {@see timing_wrapper_lock_factory} where we wrap a lock * @return string|int lock key. > * factory. */ > * public function get_key() { > * When used, it should be called immediately after constructing the lock. return $this->key; > * } > * @param lock_factory $factory New lock factory that owns this lock > */ /** > public function init_factory(lock_factory $factory): void { * Extend the lifetime of this lock. Not supported by all factories. > $this->factory = $factory; * > } * @deprecated since Moodle 3.10. > * @param int $maxlifetime - the new lifetime for the lock (in seconds). > /**
* @return bool */ public function extend($maxlifetime = 86400) { debugging('The function extend() is deprecated, please do not use it anymore.', DEBUG_DEVELOPER); if ($this->factory) { return $this->factory->extend_lock($this, $maxlifetime); } return false; } /** * Release this lock * @return bool */ public function release() { $this->released = true; if (empty($this->factory)) { return false; } $result = $this->factory->release_lock($this); // Release any held references to the factory. unset($this->factory); $this->factory = null; $this->key = ''; return $result; } /** * Print debugging if this lock falls out of scope before being released. */ public function __destruct() { if (!$this->released && defined('PHPUNIT_TEST')) { $key = $this->key; $this->release(); throw new \coding_exception("A lock was created but not released at:\n" . $this->caller . "\n\n" . " Code should look like:\n\n" . " \$factory = \core\lock\lock_config::get_lock_factory('type');\n" . " \$lock = \$factory->get_lock($key);\n" . " \$lock->release(); // Locks must ALWAYS be released like this.\n\n"); } } }