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Differences Between: [Versions 39 and 310] [Versions 39 and 311] [Versions 39 and 400] [Versions 39 and 401] [Versions 39 and 402] [Versions 39 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  /**
  18   * Class representing a lock
  19   *
  20   * The methods available for a specific lock type are only known by it's factory.
  21   *
  22   * @package    core
  23   * @copyright  Damyon Wiese 2013
  24   * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  25   */
  26  
  27  namespace core\lock;
  28  
  29  defined('MOODLE_INTERNAL') || die();
  30  
  31  /**
  32   * Class representing a lock
  33   *
  34   * The methods available for a specific lock type are only known by it's factory.
  35   *
  36   * @package   core
  37   * @category  lock
  38   * @copyright Damyon Wiese 2013
  39   * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  40   */
  41  class lock {
  42  
  43      /** @var string|int $key A unique key representing a held lock */
  44      protected $key = '';
  45  
  46      /** @var lock_factory $factory The factory that generated this lock */
  47      protected $factory;
  48  
  49      /** @var bool $released Has this lock been released? If a lock falls out of scope without being released - show a warning. */
  50      protected $released;
  51  
  52      /** @var string $caller Where was this called from? Stored for when a warning is shown */
  53      protected $caller = 'unknown';
  54  
  55      /**
  56       * Construct a lock containing the unique key required to release it.
  57       * @param mixed $key - The lock key. The type of this is up to the lock_factory being used.
  58       *      For file locks this is a file handle. For MySQL this is a string.
  59       * @param lock_factory $factory - The factory that generated this lock.
  60       */
  61      public function __construct($key, $factory) {
  62          $this->factory = $factory;
  63          $this->key = $key;
  64          $this->released = false;
  65          $caller = debug_backtrace(true, 2)[1];
  66          if ($caller && array_key_exists('file', $caller ) ) {
  67              $this->caller = $caller['file'] . ' on line ' . $caller['line'];
  68          } else if ($caller && array_key_exists('class', $caller)) {
  69              $this->caller = $caller['class'] . $caller['type'] . $caller['function'];
  70          }
  71      }
  72  
  73      /**
  74       * Return the unique key representing this lock.
  75       * @return string|int lock key.
  76       */
  77      public function get_key() {
  78          return $this->key;
  79      }
  80  
  81      /**
  82       * Extend the lifetime of this lock. Not supported by all factories.
  83       * @param int $maxlifetime - the new lifetime for the lock (in seconds).
  84       * @return bool
  85       */
  86      public function extend($maxlifetime = 86400) {
  87          if ($this->factory) {
  88              return $this->factory->extend_lock($this, $maxlifetime);
  89          }
  90          return false;
  91      }
  92  
  93      /**
  94       * Release this lock
  95       * @return bool
  96       */
  97      public function release() {
  98          $this->released = true;
  99          if (empty($this->factory)) {
 100              return false;
 101          }
 102          $result = $this->factory->release_lock($this);
 103          // Release any held references to the factory.
 104          unset($this->factory);
 105          $this->factory = null;
 106          $this->key = '';
 107          return $result;
 108      }
 109  
 110      /**
 111       * Print debugging if this lock falls out of scope before being released.
 112       */
 113      public function __destruct() {
 114          if (!$this->released && defined('PHPUNIT_TEST')) {
 115              $key = $this->key;
 116              $this->release();
 117              throw new \coding_exception("A lock was created but not released at:\n" .
 118                                          $this->caller . "\n\n" .
 119                                          " Code should look like:\n\n" .
 120                                          " \$factory = \core\lock\lock_config::get_lock_factory('type');\n" .
 121                                          " \$lock = \$factory->get_lock($key);\n" .
 122                                          " \$lock->release();  // Locks must ALWAYS be released like this.\n\n");
 123          }
 124      }
 125  
 126  }