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  * @ingroup Cache
  28  */
  29 class APCBagOStuff extends BagOStuff {
  30
  31         /**
  32          * @var bool If true, trust the APC implementation to serialize and
  33          * deserialize objects correctly. If false, (de-)serialize in PHP.
  34          */
  35         protected $nativeSerialize;
  36
  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 = ':2';
  43
  44         /**
  45          * Available parameters are:
  46          *   - nativeSerialize:     If true, pass objects to apc_store(), and trust it
  47          *                          to serialize them correctly. If false, serialize
  48          *                          all values in PHP.
  49          *
  50          * @param array $params
  51          */
  52         public function __construct( array $params = [] ) {
  53                 parent::__construct( $params );
  54
  55                 if ( isset( $params['nativeSerialize'] ) ) {
  56                         $this->nativeSerialize = $params['nativeSerialize'];
  57                 } elseif ( extension_loaded( 'apcu' ) && ini_get( 'apc.serializer' ) === 'default' ) {
  58                         // APCu has a memory corruption bug when the serializer is set to 'default'.
  59                         // See T120267, and upstream bug reports:
  60                         //  - https://github.com/krakjoe/apcu/issues/38
  61                         //  - https://github.com/krakjoe/apcu/issues/35
  62                         //  - https://github.com/krakjoe/apcu/issues/111
  63                         $this->logger->warning(
  64                                 'The APCu extension is loaded and the apc.serializer INI setting ' .
  65                                 'is set to "default". This can cause memory corruption! ' .
  66                                 'You should change apc.serializer to "php" instead. ' .
  67                                 'See <https://github.com/krakjoe/apcu/issues/38>.'
  68                         );
  69                         $this->nativeSerialize = false;
  70                 } else {
  71                         $this->nativeSerialize = true;
  72                 }
  73         }
  74
  75         protected function doGet( $key, $flags = 0 ) {
  76                 return $this->unserialize( apc_fetch( $key . self::KEY_SUFFIX ) );
  77         }
  78
  79         protected function getWithToken( $key, &$casToken, $flags = 0 ) {
  80                 $casToken = null;
  81
  82                 $blob = apc_fetch( $key . self::KEY_SUFFIX );
  83                 $value = $this->unserialize( $blob );
  84                 if ( $value !== false ) {
  85                         $casToken = $blob; // don't bother hashing this
  86                 }
  87
  88                 return $value;
  89         }
  90
  91         public function set( $key, $value, $exptime = 0, $flags = 0 ) {
  92                 apc_store(
  93                         $key . self::KEY_SUFFIX,
  94                         $this->serialize( $value ),
  95                         $exptime
  96                 );
  97
  98                 return true;
  99         }
 100
 101         public function add( $key, $value, $exptime = 0, $flags = 0 ) {
 102                 return apc_add(
 103                         $key . self::KEY_SUFFIX,
 104                         $this->serialize( $value ),
 105                         $exptime
 106                 );
 107         }
 108
 109         public function delete( $key, $flags = 0 ) {
 110                 apc_delete( $key . self::KEY_SUFFIX );
 111
 112                 return true;
 113         }
 114
 115         public function incr( $key, $value = 1 ) {
 116                 return apc_inc( $key . self::KEY_SUFFIX, $value );
 117         }
 118
 119         public function decr( $key, $value = 1 ) {
 120                 return apc_dec( $key . self::KEY_SUFFIX, $value );
 121         }
 122
 123         protected function serialize( $value ) {
 124                 if ( !$this->nativeSerialize && !$this->isInteger( $value ) ) {
 125                         $value = serialize( $value );
 126                 }
 127                 return $value;
 128         }
 129
 130         protected function unserialize( $value ) {
 131                 if ( is_string( $value ) && !$this->nativeSerialize ) {
 132                         $value = $this->isInteger( $value )
 133                                 ? intval( $value )
 134                                 : unserialize( $value );
 135                 }
 136                 return $value;
 137         }
 138 }