. namespace core\lock; use coding_exception; /** * 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; // Track where the lock was raised, so we can report un-released locks in a helpful way. $this->caller = format_backtrace(debug_backtrace(), true); } /** * Sets the lock factory that owns a lock. This function should not be called under normal use. * It is intended only for cases like {@see timing_wrapper_lock_factory} where we wrap a lock * factory. * * When used, it should be called immediately after constructing the lock. * * @param lock_factory $factory New lock factory that owns this lock */ public function init_factory(lock_factory $factory): void { $this->factory = $factory; } /** * Return the unique key representing this lock. * @return string|int lock key. */ public function get_key() { return $this->key; } /** * 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; } /** * Release a lock if it has not already been released. * * @param bool $withexception If true, throw an exception if the lock has not been released. * @throws \coding_exception */ public function release_if_not_released(bool $withexception = false): void { if (!$this->released) { $key = $this->key; $this->release(); if ($withexception) { throw new \core\exception\coding_exception(<<caller} Code should look like: \$factory = \core\lock\lock_config::get_lock_factory('type'); \$lock = \$factory->get_lock($key); \$lock->release(); // Locks must ALWAYS be released like this. EOF); } } } /** * Print debugging if this lock falls out of scope before being released. */ public function __destruct() { global $CFG; $this->release_if_not_released(defined('BEHAT_SITE_RUNNING') || PHPUNIT_TEST || $CFG->debugdeveloper); } }