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Differences Between: [Versions 310 and 403] [Versions 311 and 403] [Versions 39 and 403] [Versions 400 and 403] [Versions 401 and 403] [Versions 402 and 403]

   1  <?php
   2  // This file is part of Moodle - http://moodle.org/
   3  //
   4  // Moodle is free software: you can redistribute it and/or modify
   5  // it under the terms of the GNU General Public License as published by
   6  // the Free Software Foundation, either version 3 of the License, or
   7  // (at your option) any later version.
   8  //
   9  // Moodle is distributed in the hope that it will be useful,
  10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  // GNU General Public License for more details.
  13  //
  14  // You should have received a copy of the GNU General Public License
  15  // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16  
  17  namespace core\lock;
  18  
  19  use coding_exception;
  20  
  21  /**
  22   * Class representing a lock
  23   *
  24   * The methods available for a specific lock type are only known by it's factory.
  25   *
  26   * @package   core
  27   * @category  lock
  28   * @copyright Damyon Wiese 2013
  29   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  30   */
  31  class lock {
  32  
  33      /** @var string|int $key A unique key representing a held lock */
  34      protected $key = '';
  35  
  36      /** @var lock_factory $factory The factory that generated this lock */
  37      protected $factory;
  38  
  39      /** @var bool $released Has this lock been released? If a lock falls out of scope without being released - show a warning. */
  40      protected $released;
  41  
  42      /** @var string $caller Where was this called from? Stored for when a warning is shown */
  43      protected $caller = 'unknown';
  44  
  45      /**
  46       * Construct a lock containing the unique key required to release it.
  47       * @param mixed $key - The lock key. The type of this is up to the lock_factory being used.
  48       *      For file locks this is a file handle. For MySQL this is a string.
  49       * @param lock_factory $factory - The factory that generated this lock.
  50       */
  51      public function __construct($key, $factory) {
  52          $this->factory = $factory;
  53          $this->key = $key;
  54          $this->released = false;
  55          $caller = debug_backtrace(true, 2)[1];
  56          if ($caller && array_key_exists('file', $caller ) ) {
  57              $this->caller = $caller['file'] . ' on line ' . $caller['line'];
  58          } else if ($caller && array_key_exists('class', $caller)) {
  59              $this->caller = $caller['class'] . $caller['type'] . $caller['function'];
  60          }
  61      }
  62  
  63      /**
  64       * Sets the lock factory that owns a lock. This function should not be called under normal use.
  65       * It is intended only for cases like {@see timing_wrapper_lock_factory} where we wrap a lock
  66       * factory.
  67       *
  68       * When used, it should be called immediately after constructing the lock.
  69       *
  70       * @param lock_factory $factory New lock factory that owns this lock
  71       */
  72      public function init_factory(lock_factory $factory): void {
  73          $this->factory = $factory;
  74      }
  75  
  76      /**
  77       * Return the unique key representing this lock.
  78       * @return string|int lock key.
  79       */
  80      public function get_key() {
  81          return $this->key;
  82      }
  83  
  84      /**
  85       * @deprecated since Moodle 3.10.
  86       */
  87      public function extend() {
  88          throw new coding_exception('The function extend() has been removed, please do not use it anymore.');
  89      }
  90  
  91      /**
  92       * Release this lock
  93       * @return bool
  94       */
  95      public function release() {
  96          $this->released = true;
  97          if (empty($this->factory)) {
  98              return false;
  99          }
 100          $result = $this->factory->release_lock($this);
 101          // Release any held references to the factory.
 102          unset($this->factory);
 103          $this->factory = null;
 104          $this->key = '';
 105          return $result;
 106      }
 107  
 108      /**
 109       * Print debugging if this lock falls out of scope before being released.
 110       */
 111      public function __destruct() {
 112          if (!$this->released && defined('PHPUNIT_TEST')) {
 113              $key = $this->key;
 114              $this->release();
 115              throw new \coding_exception("A lock was created but not released at:\n" .
 116                                          $this->caller . "\n\n" .
 117                                          " Code should look like:\n\n" .
 118                                          " \$factory = \core\lock\lock_config::get_lock_factory('type');\n" .
 119                                          " \$lock = \$factory->get_lock($key);\n" .
 120                                          " \$lock->release();  // Locks must ALWAYS be released like this.\n\n");
 121          }
 122      }
 123  
 124  }