includes/libs/objectcache/APCBagOStuff.php

   1 <?php
   2 /**
   3  * Object caching using PHP's APC accelerator.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Cache
  22  */
  23
  24 /**
  25  * This is a wrapper for APC's shared memory functions
  26  *
  27  * Use PHP serialization to avoid bugs and easily create CAS tokens.
  28  * APCu has a memory corruption bug when the serializer is set to 'default'.
  29  * See T120267, and upstream bug reports:
  30  *  - https://github.com/krakjoe/apcu/issues/38
  31  *  - https://github.com/krakjoe/apcu/issues/35
  32  *  - https://github.com/krakjoe/apcu/issues/111
  33  *
  34  * @ingroup Cache
  35  */
  36 class APCBagOStuff extends BagOStuff {
  37         /**
  38          * @var string String to append to each APC key. This may be changed
  39          *  whenever the handling of values is changed, to prevent existing code
  40          *  from encountering older values which it cannot handle.
  41          */
  42         const KEY_SUFFIX = ':3';
  43
  44         protected function doGet( $key, $flags = 0, &$casToken = null ) {
  45                 $casToken = null;
  46
  47                 $blob = apc_fetch( $key . self::KEY_SUFFIX );
  48                 $value = $this->unserialize( $blob );
  49                 if ( $value !== false ) {
  50                         $casToken = $blob; // don't bother hashing this
  51                 }
  52
  53                 return $value;
  54         }
  55
  56         public function set( $key, $value, $exptime = 0, $flags = 0 ) {
  57                 apc_store(
  58                         $key . self::KEY_SUFFIX,
  59                         $this->serialize( $value ),
  60                         $exptime
  61                 );
  62
  63                 return true;
  64         }
  65
  66         public function add( $key, $value, $exptime = 0, $flags = 0 ) {
  67                 return apc_add(
  68                         $key . self::KEY_SUFFIX,
  69                         $this->serialize( $value ),
  70                         $exptime
  71                 );
  72         }
  73
  74         public function delete( $key, $flags = 0 ) {
  75                 apc_delete( $key . self::KEY_SUFFIX );
  76
  77                 return true;
  78         }
  79
  80         public function incr( $key, $value = 1 ) {
  81                 return apc_inc( $key . self::KEY_SUFFIX, $value );
  82         }
  83
  84         public function decr( $key, $value = 1 ) {
  85                 return apc_dec( $key . self::KEY_SUFFIX, $value );
  86         }
  87
  88         protected function serialize( $value ) {
  89                 return $this->isInteger( $value ) ? (int)$value : serialize( $value );
  90         }
  91
  92         protected function unserialize( $value ) {
  93                 return $this->isInteger( $value ) ? (int)$value : unserialize( $value );
  94         }
  95 }