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
  24 /**
  25  * Simple store for keeping values in an associative array for the current process.
  26  *
  27  * Data will not persist and is not shared with other processes.
  28  *
  29  * @ingroup Cache
  30  */
  31 class HashBagOStuff extends BagOStuff {
  32         /** @var mixed[] */
  33         protected $bag = [];
  34         /** @var int Max entries allowed */
  35         protected $maxCacheKeys;
  36
  37         const KEY_VAL = 0;
  38         const KEY_EXP = 1;
  39
  40         /**
  41          * @param array $params Additional parameters include:
  42          *   - maxKeys : only allow this many keys (using oldest-first eviction)
  43          */
  44         function __construct( $params = [] ) {
  45                 parent::__construct( $params );
  46
  47                 $this->maxCacheKeys = isset( $params['maxKeys'] ) ? $params['maxKeys'] : INF;
  48                 if ( $this->maxCacheKeys <= 0 ) {
  49                         throw new InvalidArgumentException( '$maxKeys parameter must be above zero' );
  50                 }
  51         }
  52
  53         protected function expire( $key ) {
  54                 $et = $this->bag[$key][self::KEY_EXP];
  55                 if ( $et == self::TTL_INDEFINITE || $et > $this->getCurrentTime() ) {
  56                         return false;
  57                 }
  58
  59                 $this->delete( $key );
  60
  61                 return true;
  62         }
  63
  64         /**
  65          * Does this bag have a non-null value for the given key?
  66          *
  67          * @param string $key
  68          * @return bool
  69          * @since 1.27
  70          */
  71         protected function hasKey( $key ) {
  72                 return isset( $this->bag[$key] );
  73         }
  74
  75         protected function doGet( $key, $flags = 0 ) {
  76                 if ( !$this->hasKey( $key ) ) {
  77                         return false;
  78                 }
  79
  80                 if ( $this->expire( $key ) ) {
  81                         return false;
  82                 }
  83
  84                 // Refresh key position for maxCacheKeys eviction
  85                 $temp = $this->bag[$key];
  86                 unset( $this->bag[$key] );
  87                 $this->bag[$key] = $temp;
  88
  89                 return $this->bag[$key][self::KEY_VAL];
  90         }
  91
  92         public function set( $key, $value, $exptime = 0, $flags = 0 ) {
  93                 // Refresh key position for maxCacheKeys eviction
  94                 unset( $this->bag[$key] );
  95                 $this->bag[$key] = [
  96                         self::KEY_VAL => $value,
  97                         self::KEY_EXP => $this->convertExpiry( $exptime )
  98                 ];
  99
 100                 if ( count( $this->bag ) > $this->maxCacheKeys ) {
 101                         reset( $this->bag );
 102                         $evictKey = key( $this->bag );
 103                         unset( $this->bag[$evictKey] );
 104                 }
 105
 106                 return true;
 107         }
 108
 109         public function delete( $key ) {
 110                 unset( $this->bag[$key] );
 111
 112                 return true;
 113         }
 114
 115         public function clear() {
 116                 $this->bag = [];
 117         }
 118
 119         protected function getCurrentTime() {
 120                 return time();
 121         }
 122 }