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         /**
  47          * @param $bool bool
  48          */
  49         public function setDebug( $bool ) {
  50                 $this->debugMode = $bool;
  51         }
  52
  53         /* *** THE GUTS OF THE OPERATION *** */
  54         /* Override these with functional things in subclasses */
  55
  56         /**
  57          * Get an item with the given key. Returns false if it does not exist.
  58          * @param $key string
  59          *
  60          * @return bool|Object
  61          */
  62         abstract public function get( $key );
  63
  64         /**
  65          * Set an item.
  66          * @param $key string
  67          * @param $value mixed
  68          * @param $exptime int Either an interval in seconds or a unix timestamp for expiry
  69          */
  70         abstract public function set( $key, $value, $exptime = 0 );
  71
  72         /**
  73          * Delete an item.
  74          * @param $key string
  75          * @param $time int Amount of time to delay the operation (mostly memcached-specific)
  76          */
  77         abstract public function delete( $key, $time = 0 );
  78
  79         public function lock( $key, $timeout = 0 ) {
  80                 /* stub */
  81                 return true;
  82         }
  83
  84         public function unlock( $key ) {
  85                 /* stub */
  86                 return true;
  87         }
  88
  89         public function keys() {
  90                 /* stub */
  91                 return array();
  92         }
  93
  94         /**
  95          * Delete all objects expiring before a certain date.
  96          *
  97          * @return true on success, false if unimplemented
  98          */
  99         public function deleteObjectsExpiringBefore( $date ) {
 100                 // stub
 101                 return false;
 102         }
 103
 104         /* *** Emulated functions *** */
 105
 106         public function add( $key, $value, $exptime = 0 ) {
 107                 if ( !$this->get( $key ) ) {
 108                         $this->set( $key, $value, $exptime );
 109
 110                         return true;
 111                 }
 112         }
 113
 114         public function replace( $key, $value, $exptime = 0 ) {
 115                 if ( $this->get( $key ) !== false ) {
 116                         $this->set( $key, $value, $exptime );
 117                 }
 118         }
 119
 120         /**
 121          * @param $key String: Key to increase
 122          * @param $value Integer: Value to add to $key (Default 1)
 123          * @return null if lock is not possible else $key value increased by $value
 124          */
 125         public function incr( $key, $value = 1 ) {
 126                 if ( !$this->lock( $key ) ) {
 127                         return null;
 128                 }
 129
 130                 $value = intval( $value );
 131
 132                 if ( ( $n = $this->get( $key ) ) !== false ) {
 133                         $n += $value;
 134                         $this->set( $key, $n ); // exptime?
 135                 }
 136                 $this->unlock( $key );
 137
 138                 return $n;
 139         }
 140
 141         public function decr( $key, $value = 1 ) {
 142                 return $this->incr( $key, - $value );
 143         }
 144
 145         public function debug( $text ) {
 146                 if ( $this->debugMode ) {
 147                         $class = get_class( $this );
 148                         wfDebug( "$class debug: $text\n" );
 149                 }
 150         }
 151
 152         /**
 153          * Convert an optionally relative time to an absolute time
 154          */
 155         protected function convertExpiry( $exptime ) {
 156                 if ( ( $exptime != 0 ) && ( $exptime < 86400 * 3650 /* 10 years */ ) ) {
 157                         return time() + $exptime;
 158                 } else {
 159                         return $exptime;
 160                 }
 161         }
 162 }
 163
 164