includes/libs/lockmanager/ScopedLock.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  *
  18  * @file
  19  */
  20
  21 /**
  22  * Self-releasing locks.
  23  *
  24  * Helper for consumers of LockManager, to create locks that automatically
  25  * release when an object is destroyed or goes out of scope.
  26  *
  27  * @ingroup LockManager
  28  * @since 1.19
  29  */
  30 class ScopedLock {
  31         /** @var LockManager */
  32         protected $manager;
  33         /** @var StatusValue */
  34         protected $status;
  35         /** @var array Map of lock types to resource paths */
  36         protected $pathsByType;
  37
  38         /**
  39          * @param LockManager $manager
  40          * @param array $pathsByType Map of lock types to path lists
  41          * @param StatusValue $status
  42          */
  43         protected function __construct(
  44                 LockManager $manager, array $pathsByType, StatusValue $status
  45         ) {
  46                 $this->manager = $manager;
  47                 $this->pathsByType = $pathsByType;
  48                 $this->status = $status;
  49         }
  50
  51         /**
  52          * Get a ScopedLock object representing a lock on resource paths.
  53          * Any locks are released once this object goes out of scope.
  54          * The StatusValue object is updated with any errors or warnings.
  55          *
  56          * @param LockManager $manager
  57          * @param array $paths List of storage paths or map of lock types to path lists
  58          * @param int|string $type LockManager::LOCK_* constant or "mixed" and $paths
  59          *   can be a map of types to paths (since 1.22). Otherwise $type should be an
  60          *   integer and $paths should be a list of paths.
  61          * @param StatusValue $status
  62          * @param int $timeout Timeout in seconds (0 means non-blocking) (since 1.22)
  63          * @return ScopedLock|null Returns null on failure
  64          */
  65         public static function factory(
  66                 LockManager $manager, array $paths, $type, StatusValue $status, $timeout = 0
  67         ) {
  68                 $pathsByType = is_int( $type ) ? [ $type => $paths ] : $paths;
  69                 $lockStatus = $manager->lockByType( $pathsByType, $timeout );
  70                 $status->merge( $lockStatus );
  71                 if ( $lockStatus->isOK() ) {
  72                         return new self( $manager, $pathsByType, $status );
  73                 }
  74
  75                 return null;
  76         }
  77
  78         /**
  79          * Release a scoped lock and set any errors in the attached StatusValue object.
  80          * This is useful for early release of locks before function scope is destroyed.
  81          * This is the same as setting the lock object to null.
  82          *
  83          * @param ScopedLock|null &$lock
  84          * @since 1.21
  85          */
  86         public static function release( ?ScopedLock &$lock = null ) {
  87                 $lock = null;
  88         }
  89
  90         /**
  91          * Release the locks when this goes out of scope
  92          */
  93         public function __destruct() {
  94                 $wasOk = $this->status->isOK();
  95                 $this->status->merge( $this->manager->unlockByType( $this->pathsByType ) );
  96                 if ( $wasOk ) {
  97                         // Make sure StatusValue is OK, despite any unlockFiles() fatals
  98                         $this->status->setResult( true, $this->status->value );
  99                 }
 100         }
 101 }