includes/libs/objectcache/HashBagOStuff.php

   1 <?php
   2 /**
   3  * Per-process memory cache for storing items.
   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 use Wikimedia\Assert\Assert;
  24
  25 /**
  26  * Simple store for keeping values in an associative array for the current process.
  27  *
  28  * Data will not persist and is not shared with other processes.
  29  *
  30  * @ingroup Cache
  31  */
  32 class HashBagOStuff extends BagOStuff {
  33         /** @var mixed[] */
  34         protected $bag = array();
  35         /** @var integer Max entries allowed */
  36         protected $maxCacheKeys;
  37
  38         const KEY_VAL = 0;
  39         const KEY_EXP = 1;
  40
  41         /**
  42          * @param array $params Additional parameters include:
  43          *   - maxKeys : only allow this many keys (using oldest-first eviction)
  44          */
  45         function __construct( $params = array() ) {
  46                 parent::__construct( $params );
  47
  48                 $this->maxCacheKeys = isset( $params['maxKeys'] ) ? $params['maxKeys'] : INF;
  49                 Assert::parameter( $this->maxCacheKeys > 0, 'maxKeys', 'must be above zero' );
  50         }
  51
  52         protected function expire( $key ) {
  53                 $et = $this->bag[$key][self::KEY_EXP];
  54                 if ( $et == self::TTL_INDEFINITE || $et > time() ) {
  55                         return false;
  56                 }
  57
  58                 $this->delete( $key );
  59
  60                 return true;
  61         }
  62
  63         protected function doGet( $key, $flags = 0 ) {
  64                 if ( !isset( $this->bag[$key] ) ) {
  65                         return false;
  66                 }
  67
  68                 if ( $this->expire( $key ) ) {
  69                         return false;
  70                 }
  71
  72                 // Refresh key position for maxCacheKeys eviction
  73                 $temp = $this->bag[$key];
  74                 unset( $this->bag[$key] );
  75                 $this->bag[$key] = $temp;
  76
  77                 return $this->bag[$key][self::KEY_VAL];
  78         }
  79
  80         public function set( $key, $value, $exptime = 0, $flags = 0 ) {
  81                 // Refresh key position for maxCacheKeys eviction
  82                 unset( $this->bag[$key] );
  83                 $this->bag[$key] = array(
  84                         self::KEY_VAL => $value,
  85                         self::KEY_EXP => $this->convertExpiry( $exptime )
  86                 );
  87
  88                 if ( count( $this->bag ) > $this->maxCacheKeys ) {
  89                         reset( $this->bag );
  90                         $evictKey = key( $this->bag );
  91                         unset( $this->bag[$evictKey] );
  92                 }
  93
  94                 return true;
  95         }
  96
  97         public function delete( $key ) {
  98                 unset( $this->bag[$key] );
  99
 100                 return true;
 101         }
 102
 103         public function clear() {
 104                 $this->bag = array();
 105         }
 106 }