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          * @return mixed Returns false on failure
  60          */
  61         abstract public function get( $key );
  62
  63         /**
  64          * Get an associative array containing the item for each of the given keys.
  65          * Each item will be false if it does not exist.
  66          * @param $keys Array List of strings
  67          * @return Array
  68          */
  69         public function getBatch( array $keys ) {
  70                 $res = array();
  71                 foreach ( $keys as $key ) {
  72                         $res[$key] = $this->get( $key );
  73                 }
  74                 return $res;
  75         }
  76
  77         /**
  78          * Set an item.
  79          * @param $key string
  80          * @param $value mixed
  81          * @param $exptime int Either an interval in seconds or a unix timestamp for expiry
  82          * @return bool success
  83          */
  84         abstract public function set( $key, $value, $exptime = 0 );
  85
  86         /**
  87          * Delete an item.
  88          * @param $key string
  89          * @param $time int Amount of time to delay the operation (mostly memcached-specific)
  90          * @return bool success
  91          */
  92         abstract public function delete( $key, $time = 0 );
  93
  94         /**
  95          * @param $key string
  96          * @param $timeout integer
  97          * @return bool success
  98          */
  99         public function lock( $key, $timeout = 0 ) {
 100                 /* stub */
 101                 return true;
 102         }
 103
 104         /**
 105          * @param $key string
 106          * @return bool success
 107          */
 108         public function unlock( $key ) {
 109                 /* stub */
 110                 return true;
 111         }
 112
 113         /**
 114          * @todo: what is this?
 115          * @return Array
 116          */
 117         public function keys() {
 118                 /* stub */
 119                 return array();
 120         }
 121
 122         /**
 123          * Delete all objects expiring before a certain date.
 124          * @param $date string The reference date in MW format
 125          * @param $progressCallback callback|bool Optional, a function which will be called
 126          *     regularly during long-running operations with the percentage progress
 127          *     as the first parameter.
 128          *
 129          * @return bool on success, false if unimplemented
 130          */
 131         public function deleteObjectsExpiringBefore( $date, $progressCallback = false ) {
 132                 // stub
 133                 return false;
 134         }
 135
 136         /* *** Emulated functions *** */
 137
 138         /**
 139          * @param $key string
 140          * @param $value mixed
 141          * @param $exptime integer
 142          * @return bool success
 143          */
 144         public function add( $key, $value, $exptime = 0 ) {
 145                 if ( !$this->get( $key ) ) {
 146                         return $this->set( $key, $value, $exptime );
 147                 }
 148                 return true;
 149         }
 150
 151         /**
 152          * @param $key string
 153          * @param $value mixed
 154          * @return bool success
 155          */
 156         public function replace( $key, $value, $exptime = 0 ) {
 157                 if ( $this->get( $key ) !== false ) {
 158                         return $this->set( $key, $value, $exptime );
 159                 }
 160                 return true;
 161         }
 162
 163         /**
 164          * @param $key String: Key to increase
 165          * @param $value Integer: Value to add to $key (Default 1)
 166          * @return null if lock is not possible else $key value increased by $value
 167          * @return success
 168          */
 169         public function incr( $key, $value = 1 ) {
 170                 if ( !$this->lock( $key ) ) {
 171                         return null;
 172                 }
 173
 174                 $value = intval( $value );
 175
 176                 if ( ( $n = $this->get( $key ) ) !== false ) {
 177                         $n += $value;
 178                         $this->set( $key, $n ); // exptime?
 179                 }
 180                 $this->unlock( $key );
 181
 182                 return $n;
 183         }
 184
 185         /**
 186          * @param $key String
 187          * @param $value Integer
 188          * @return bool success
 189          */
 190         public function decr( $key, $value = 1 ) {
 191                 return $this->incr( $key, - $value );
 192         }
 193
 194         /**
 195          * @param $text string
 196          */
 197         public function debug( $text ) {
 198                 if ( $this->debugMode ) {
 199                         $class = get_class( $this );
 200                         wfDebug( "$class debug: $text\n" );
 201                 }
 202         }
 203
 204         /**
 205          * Convert an optionally relative time to an absolute time
 206          * @param $exptime integer
 207          * @return int
 208          */
 209         protected function convertExpiry( $exptime ) {
 210                 if ( ( $exptime != 0 ) && ( $exptime < 86400 * 3650 /* 10 years */ ) ) {
 211                         return time() + $exptime;
 212                 } else {
 213                         return $exptime;
 214                 }
 215         }
 216 }