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 MediumSpecificBagOStuff {
  32         /** @var mixed[] */
  33         protected $bag = [];
  34         /** @var int Max entries allowed */
  35         protected $maxCacheKeys;
  36
  37         /** @var string CAS token prefix for this instance */
  38         private $token;
  39
  40         /** @var int CAS token counter */
  41         private static $casCounter = 0;
  42
  43         const KEY_VAL = 0;
  44         const KEY_EXP = 1;
  45         const KEY_CAS = 2;
  46
  47         /**
  48          * @param array $params Additional parameters include:
  49          *   - maxKeys : only allow this many keys (using oldest-first eviction)
  50          * @codingStandardsIgnoreStart
  51          * @phan-param array{logger?:Psr\Log\LoggerInterface,asyncHandler?:callable,keyspace?:string,reportDupes?:bool,syncTimeout?:int,segmentationSize?:int,segmentedValueMaxSize?:int,maxKeys?:int} $params
  52          * @codingStandardsIgnoreEnd
  53          */
  54         function __construct( $params = [] ) {
  55                 $params['segmentationSize'] = $params['segmentationSize'] ?? INF;
  56                 parent::__construct( $params );
  57
  58                 $this->token = microtime( true ) . ':' . mt_rand();
  59                 $this->maxCacheKeys = $params['maxKeys'] ?? INF;
  60                 if ( $this->maxCacheKeys <= 0 ) {
  61                         throw new InvalidArgumentException( '$maxKeys parameter must be above zero' );
  62                 }
  63         }
  64
  65         protected function doGet( $key, $flags = 0, &$casToken = null ) {
  66                 $casToken = null;
  67
  68                 if ( !$this->hasKey( $key ) || $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                 $casToken = $this->bag[$key][self::KEY_CAS];
  78
  79                 return $this->bag[$key][self::KEY_VAL];
  80         }
  81
  82         protected function doSet( $key, $value, $exptime = 0, $flags = 0 ) {
  83                 // Refresh key position for maxCacheKeys eviction
  84                 unset( $this->bag[$key] );
  85                 $this->bag[$key] = [
  86                         self::KEY_VAL => $value,
  87                         self::KEY_EXP => $this->getExpirationAsTimestamp( $exptime ),
  88                         self::KEY_CAS => $this->token . ':' . ++self::$casCounter
  89                 ];
  90
  91                 if ( count( $this->bag ) > $this->maxCacheKeys ) {
  92                         reset( $this->bag );
  93                         $evictKey = key( $this->bag );
  94                         unset( $this->bag[$evictKey] );
  95                 }
  96
  97                 return true;
  98         }
  99
 100         protected function doAdd( $key, $value, $exptime = 0, $flags = 0 ) {
 101                 if ( $this->hasKey( $key ) && !$this->expire( $key ) ) {
 102                         return false; // key already set
 103                 }
 104
 105                 return $this->doSet( $key, $value, $exptime, $flags );
 106         }
 107
 108         protected function doDelete( $key, $flags = 0 ) {
 109                 unset( $this->bag[$key] );
 110
 111                 return true;
 112         }
 113
 114         public function incr( $key, $value = 1, $flags = 0 ) {
 115                 $n = $this->get( $key );
 116                 if ( $this->isInteger( $n ) ) {
 117                         $n = max( $n + (int)$value, 0 );
 118                         $this->bag[$key][self::KEY_VAL] = $n;
 119
 120                         return $n;
 121                 }
 122
 123                 return false;
 124         }
 125
 126         public function decr( $key, $value = 1, $flags = 0 ) {
 127                 return $this->incr( $key, -$value, $flags );
 128         }
 129
 130         /**
 131          * Clear all values in cache
 132          */
 133         public function clear() {
 134                 $this->bag = [];
 135         }
 136
 137         /**
 138          * @param string $key
 139          * @return bool
 140          */
 141         protected function expire( $key ) {
 142                 $et = $this->bag[$key][self::KEY_EXP];
 143                 if ( $et == self::TTL_INDEFINITE || $et > $this->getCurrentTime() ) {
 144                         return false;
 145                 }
 146
 147                 $this->doDelete( $key );
 148
 149                 return true;
 150         }
 151
 152         /**
 153          * Does this bag have a non-null value for the given key?
 154          *
 155          * @param string $key
 156          * @return bool
 157          * @since 1.27
 158          */
 159         public function hasKey( $key ) {
 160                 return isset( $this->bag[$key] );
 161         }
 162 }