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          * Set an item.
  65          * @param $key string
  66          * @param $value mixed
  67          * @param $exptime int Either an interval in seconds or a unix timestamp for expiry
  68          * @return bool success
  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          * @return bool True if the item was deleted or not found, false on failure
  77          */
  78         abstract public function delete( $key, $time = 0 );
  79
  80         /**
  81          * @param $key string
  82          * @param $timeout integer
  83          * @return bool success
  84          */
  85         public function lock( $key, $timeout = 0 ) {
  86                 /* stub */
  87                 return true;
  88         }
  89
  90         /**
  91          * @param $key string
  92          * @return bool success
  93          */
  94         public function unlock( $key ) {
  95                 /* stub */
  96                 return true;
  97         }
  98
  99         /**
 100          * @todo: what is this?
 101          * @return Array
 102          */
 103         public function keys() {
 104                 /* stub */
 105                 return array();
 106         }
 107
 108         /**
 109          * Delete all objects expiring before a certain date.
 110          * @param $date string The reference date in MW format
 111          * @param $progressCallback callback|bool Optional, a function which will be called
 112          *     regularly during long-running operations with the percentage progress
 113          *     as the first parameter.
 114          *
 115          * @return bool on success, false if unimplemented
 116          */
 117         public function deleteObjectsExpiringBefore( $date, $progressCallback = false ) {
 118                 // stub
 119                 return false;
 120         }
 121
 122         /* *** Emulated functions *** */
 123
 124         /**
 125          * Get an associative array containing the item for each of the keys that have items.
 126          * @param $keys Array List of strings
 127          * @return Array
 128          */
 129         public function getMulti( array $keys ) {
 130                 $res = array();
 131                 foreach ( $keys as $key ) {
 132                         $val = $this->get( $key );
 133                         if ( $val !== false ) {
 134                                 $res[$key] = $val;
 135                         }
 136                 }
 137                 return $res;
 138         }
 139
 140         /**
 141          * @param $key string
 142          * @param $value mixed
 143          * @param $exptime integer
 144          * @return bool success
 145          */
 146         public function add( $key, $value, $exptime = 0 ) {
 147                 if ( $this->get( $key ) === false ) {
 148                         return $this->set( $key, $value, $exptime );
 149                 }
 150                 return false; // key already set
 151         }
 152
 153         /**
 154          * @param $key string
 155          * @param $value mixed
 156          * @param $exptime int
 157          * @return bool success
 158          */
 159         public function replace( $key, $value, $exptime = 0 ) {
 160                 if ( $this->get( $key ) !== false ) {
 161                         return $this->set( $key, $value, $exptime );
 162                 }
 163                 return false; // key not already set
 164         }
 165
 166         /**
 167          * @param $key String: Key to increase
 168          * @param $value Integer: Value to add to $key (Default 1)
 169          * @return null if lock is not possible else $key value increased by $value
 170          * @return bool success
 171          */
 172         public function incr( $key, $value = 1 ) {
 173                 if ( !$this->lock( $key ) ) {
 174                         return null;
 175                 }
 176
 177                 $value = intval( $value );
 178
 179                 if ( ( $n = $this->get( $key ) ) !== false ) {
 180                         $n += $value;
 181                         $this->set( $key, $n ); // exptime?
 182                 }
 183                 $this->unlock( $key );
 184
 185                 return $n;
 186         }
 187
 188         /**
 189          * @param $key String
 190          * @param $value Integer
 191          * @return bool success
 192          */
 193         public function decr( $key, $value = 1 ) {
 194                 return $this->incr( $key, - $value );
 195         }
 196
 197         /**
 198          * @param $text string
 199          */
 200         public function debug( $text ) {
 201                 if ( $this->debugMode ) {
 202                         $class = get_class( $this );
 203                         wfDebug( "$class debug: $text\n" );
 204                 }
 205         }
 206
 207         /**
 208          * Convert an optionally relative time to an absolute time
 209          * @param $exptime integer
 210          * @return int
 211          */
 212         protected function convertExpiry( $exptime ) {
 213                 if ( ( $exptime != 0 ) && ( $exptime < 86400 * 3650 /* 10 years */ ) ) {
 214                         return time() + $exptime;
 215                 } else {
 216                         return $exptime;
 217                 }
 218         }
 219
 220         /**
 221          * Convert an optionally absolute expiry time to a relative time. If an
 222          * absolute time is specified which is in the past, use a short expiry time.
 223          *
 224          * @param $exptime integer
 225          * @return integer
 226          */
 227         protected function convertToRelative( $exptime ) {
 228                 if ( $exptime >= 86400 * 3650 /* 10 years */ ) {
 229                         $exptime -= time();
 230                         if ( $exptime <= 0 ) {
 231                                 $exptime = 1;
 232                         }
 233                         return $exptime;
 234                 } else {
 235                         return $exptime;
 236                 }
 237         }
 238 }