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          * @suppress PhanTypeInvalidDimOffset
  54          */
  55         function __construct( $params = [] ) {
  56                 $params['segmentationSize'] = $params['segmentationSize'] ?? INF;
  57                 parent::__construct( $params );
  58
  59                 $this->token = microtime( true ) . ':' . mt_rand();
  60                 $this->maxCacheKeys = $params['maxKeys'] ?? INF;
  61                 if ( $this->maxCacheKeys <= 0 ) {
  62                         throw new InvalidArgumentException( '$maxKeys parameter must be above zero' );
  63                 }
  64         }
  65
  66         protected function doGet( $key, $flags = 0, &$casToken = null ) {
  67                 $casToken = null;
  68
  69                 if ( !$this->hasKey( $key ) || $this->expire( $key ) ) {
  70                         return false;
  71                 }
  72
  73                 // Refresh key position for maxCacheKeys eviction
  74                 $temp = $this->bag[$key];
  75                 unset( $this->bag[$key] );
  76                 $this->bag[$key] = $temp;
  77
  78                 $casToken = $this->bag[$key][self::KEY_CAS];
  79
  80                 return $this->bag[$key][self::KEY_VAL];
  81         }
  82
  83         protected function doSet( $key, $value, $exptime = 0, $flags = 0 ) {
  84                 // Refresh key position for maxCacheKeys eviction
  85                 unset( $this->bag[$key] );
  86                 $this->bag[$key] = [
  87                         self::KEY_VAL => $value,
  88                         self::KEY_EXP => $this->getExpirationAsTimestamp( $exptime ),
  89                         self::KEY_CAS => $this->token . ':' . ++self::$casCounter
  90                 ];
  91
  92                 if ( count( $this->bag ) > $this->maxCacheKeys ) {
  93                         reset( $this->bag );
  94                         $evictKey = key( $this->bag );
  95                         unset( $this->bag[$evictKey] );
  96                 }
  97
  98                 return true;
  99         }
 100
 101         protected function doAdd( $key, $value, $exptime = 0, $flags = 0 ) {
 102                 if ( $this->hasKey( $key ) && !$this->expire( $key ) ) {
 103                         return false; // key already set
 104                 }
 105
 106                 return $this->doSet( $key, $value, $exptime, $flags );
 107         }
 108
 109         protected function doDelete( $key, $flags = 0 ) {
 110                 unset( $this->bag[$key] );
 111
 112                 return true;
 113         }
 114
 115         public function incr( $key, $value = 1, $flags = 0 ) {
 116                 $n = $this->get( $key );
 117                 if ( $this->isInteger( $n ) ) {
 118                         $n = max( $n + (int)$value, 0 );
 119                         $this->bag[$key][self::KEY_VAL] = $n;
 120
 121                         return $n;
 122                 }
 123
 124                 return false;
 125         }
 126
 127         public function decr( $key, $value = 1, $flags = 0 ) {
 128                 return $this->incr( $key, -$value, $flags );
 129         }
 130
 131         /**
 132          * Clear all values in cache
 133          */
 134         public function clear() {
 135                 $this->bag = [];
 136         }
 137
 138         /**
 139          * @param string $key
 140          * @return bool
 141          */
 142         protected function expire( $key ) {
 143                 $et = $this->bag[$key][self::KEY_EXP];
 144                 if ( $et == self::TTL_INDEFINITE || $et > $this->getCurrentTime() ) {
 145                         return false;
 146                 }
 147
 148                 $this->doDelete( $key );
 149
 150                 return true;
 151         }
 152
 153         /**
 154          * Does this bag have a non-null value for the given key?
 155          *
 156          * @param string $key
 157          * @return bool
 158          * @since 1.27
 159          */
 160         public function hasKey( $key ) {
 161                 return isset( $this->bag[$key] );
 162         }
 163 }