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<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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namespace core\lock;
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use coding_exception;
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/**
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* Class representing a lock
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*
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* The methods available for a specific lock type are only known by it's factory.
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*
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* @package core
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* @category lock
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* @copyright Damyon Wiese 2013
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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class lock {
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/** @var string|int $key A unique key representing a held lock */
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protected $key = '';
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/** @var lock_factory $factory The factory that generated this lock */
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protected $factory;
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/** @var bool $released Has this lock been released? If a lock falls out of scope without being released - show a warning. */
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protected $released;
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/** @var string $caller Where was this called from? Stored for when a warning is shown */
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protected $caller = 'unknown';
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/**
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* Construct a lock containing the unique key required to release it.
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* @param mixed $key - The lock key. The type of this is up to the lock_factory being used.
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* For file locks this is a file handle. For MySQL this is a string.
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* @param lock_factory $factory - The factory that generated this lock.
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*/
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public function __construct($key, $factory) {
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$this->factory = $factory;
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$this->key = $key;
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$this->released = false;
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$caller = debug_backtrace(true, 2)[1];
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if ($caller && array_key_exists('file', $caller ) ) {
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$this->caller = $caller['file'] . ' on line ' . $caller['line'];
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} else if ($caller && array_key_exists('class', $caller)) {
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$this->caller = $caller['class'] . $caller['type'] . $caller['function'];
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}
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}
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/**
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* Sets the lock factory that owns a lock. This function should not be called under normal use.
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* It is intended only for cases like {@see timing_wrapper_lock_factory} where we wrap a lock
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* factory.
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*
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* When used, it should be called immediately after constructing the lock.
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*
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* @param lock_factory $factory New lock factory that owns this lock
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*/
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public function init_factory(lock_factory $factory): void {
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$this->factory = $factory;
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}
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/**
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* Return the unique key representing this lock.
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* @return string|int lock key.
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*/
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public function get_key() {
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return $this->key;
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}
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/**
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* @deprecated since Moodle 3.10.
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*/
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public function extend() {
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throw new coding_exception('The function extend() has been removed, please do not use it anymore.');
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}
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/**
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* Release this lock
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* @return bool
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*/
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public function release() {
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$this->released = true;
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if (empty($this->factory)) {
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return false;
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}
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$result = $this->factory->release_lock($this);
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// Release any held references to the factory.
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unset($this->factory);
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$this->factory = null;
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$this->key = '';
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return $result;
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}
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/**
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* Print debugging if this lock falls out of scope before being released.
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*/
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public function __destruct() {
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if (!$this->released && defined('PHPUNIT_TEST')) {
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$key = $this->key;
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$this->release();
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throw new \coding_exception("A lock was created but not released at:\n" .
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$this->caller . "\n\n" .
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" Code should look like:\n\n" .
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" \$factory = \core\lock\lock_config::get_lock_factory('type');\n" .
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" \$lock = \$factory->get_lock($key);\n" .
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" \$lock->release(); // Locks must ALWAYS be released like this.\n\n");
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}
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}
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}
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