includes/objectcache/BagOStuff.php

   1 <?php
   2 /**
   3  * Classes to cache objects in PHP accelerators, SQL database or DBA files
   4  *
   5  * Copyright © 2003-2004 Brion Vibber <brion@pobox.com>
   6  * http://www.mediawiki.org/
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Cache
  25  */
  26
  27 /**
  28  * @defgroup Cache Cache
  29  */
  30
  31 /**
  32  * interface is intended to be more or less compatible with
  33  * the PHP memcached client.
  34  *
  35  * backends for local hash array and SQL table included:
  36  * <code>
  37  *   $bag = new HashBagOStuff();
  38  *   $bag = new SqlBagOStuff(); # connect to db first
  39  * </code>
  40  *
  41  * @ingroup Cache
  42  */
  43 abstract class BagOStuff {
  44         private $debugMode = false;
  45
  46         public function setDebug( $bool ) {
  47                 $this->debugMode = $bool;
  48         }
  49
  50         /* *** THE GUTS OF THE OPERATION *** */
  51         /* Override these with functional things in subclasses */
  52
  53         /**
  54          * Get an item with the given key. Returns false if it does not exist.
  55          * @param $key string
  56          */
  57         abstract public function get( $key );
  58
  59         /**
  60          * Set an item.
  61          * @param $key string
  62          * @param $value mixed
  63          * @param $exptime int Either an interval in seconds or a unix timestamp for expiry
  64          */
  65         abstract public function set( $key, $value, $exptime = 0 );
  66
  67         /**
  68          * Delete an item.
  69          * @param $key string
  70          * @param $time int Amount of time to delay the operation (mostly memcached-specific)
  71          */
  72         abstract public function delete( $key, $time = 0 );
  73
  74         public function lock( $key, $timeout = 0 ) {
  75                 /* stub */
  76                 return true;
  77         }
  78
  79         public function unlock( $key ) {
  80                 /* stub */
  81                 return true;
  82         }
  83
  84         public function keys() {
  85                 /* stub */
  86                 return array();
  87         }
  88
  89         /* *** Emulated functions *** */
  90
  91         public function add( $key, $value, $exptime = 0 ) {
  92                 if ( !$this->get( $key ) ) {
  93                         $this->set( $key, $value, $exptime );
  94
  95                         return true;
  96                 }
  97         }
  98
  99         public function replace( $key, $value, $exptime = 0 ) {
 100                 if ( $this->get( $key ) !== false ) {
 101                         $this->set( $key, $value, $exptime );
 102                 }
 103         }
 104
 105         /**
 106          * @param $key String: Key to increase
 107          * @param $value Integer: Value to add to $key (Default 1)
 108          * @return null if lock is not possible else $key value increased by $value
 109          */
 110         public function incr( $key, $value = 1 ) {
 111                 if ( !$this->lock( $key ) ) {
 112                         return null;
 113                 }
 114
 115                 $value = intval( $value );
 116
 117                 if ( ( $n = $this->get( $key ) ) !== false ) {
 118                         $n += $value;
 119                         $this->set( $key, $n ); // exptime?
 120                 }
 121                 $this->unlock( $key );
 122
 123                 return $n;
 124         }
 125
 126         public function decr( $key, $value = 1 ) {
 127                 return $this->incr( $key, - $value );
 128         }
 129
 130         public function debug( $text ) {
 131                 if ( $this->debugMode ) {
 132                         $class = get_class( $this );
 133                         wfDebug( "$class debug: $text\n" );
 134                 }
 135         }
 136
 137         /**
 138          * Convert an optionally relative time to an absolute time
 139          */
 140         protected function convertExpiry( $exptime ) {
 141                 if ( ( $exptime != 0 ) && ( $exptime < 86400 * 3650 /* 10 years */ ) ) {
 142                         return time() + $exptime;
 143                 } else {
 144                         return $exptime;
 145                 }
 146         }
 147 }
 148
 149