includes/cache/LinkCache.php

   1 <?php
   2 /**
   3  * Page existence cache.
   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  * Cache for article titles (prefixed DB keys) and ids linked from one source
  26  *
  27  * @ingroup Cache
  28  */
  29 class LinkCache {
  30         // Increment $mClassVer whenever old serialized versions of this class
  31         // becomes incompatible with the new version.
  32         private $mClassVer = 5;
  33
  34         /**
  35          * @var MapCacheLRU
  36          */
  37         private $mGoodLinks;
  38         /**
  39          * @var MapCacheLRU
  40          */
  41         private $mBadLinks;
  42         private $mForUpdate = false;
  43
  44         /**
  45          * How many Titles to store. There are two caches, so the amount actually
  46          * stored in memory can be up to twice this.
  47          */
  48         const MAX_SIZE = 10000;
  49
  50         /**
  51          * @var LinkCache
  52          */
  53         protected static $instance;
  54
  55         public function __construct() {
  56                 $this->mGoodLinks = new MapCacheLRU( self::MAX_SIZE );
  57                 $this->mBadLinks = new MapCacheLRU( self::MAX_SIZE );
  58         }
  59
  60         /**
  61          * Get an instance of this class.
  62          *
  63          * @return LinkCache
  64          */
  65         static function &singleton() {
  66                 if ( self::$instance ) {
  67                         return self::$instance;
  68                 }
  69                 self::$instance = new LinkCache;
  70
  71                 return self::$instance;
  72         }
  73
  74         /**
  75          * Destroy the singleton instance, a new one will be created next time
  76          * singleton() is called.
  77          * @since 1.22
  78          */
  79         static function destroySingleton() {
  80                 self::$instance = null;
  81         }
  82
  83         /**
  84          * Set the singleton instance to a given object.
  85          * Since we do not have an interface for LinkCache, you have to be sure the
  86          * given object implements all the LinkCache public methods.
  87          * @param LinkCache $instance
  88          * @since 1.22
  89          */
  90         static function setSingleton( LinkCache $instance ) {
  91                 self::$instance = $instance;
  92         }
  93
  94         /**
  95          * General accessor to get/set whether SELECT FOR UPDATE should be used
  96          *
  97          * @param bool $update
  98          * @return bool
  99          */
 100         public function forUpdate( $update = null ) {
 101                 return wfSetVar( $this->mForUpdate, $update );
 102         }
 103
 104         /**
 105          * @param string $title
 106          * @return int
 107          */
 108         public function getGoodLinkID( $title ) {
 109                 if ( $this->mGoodLinks->has( $title ) ) {
 110                         $info = $this->mGoodLinks->get( $title );
 111                         return $info['id'];
 112                 } else {
 113                         return 0;
 114                 }
 115         }
 116
 117         /**
 118          * Get a field of a title object from cache.
 119          * If this link is not good, it will return NULL.
 120          * @param Title $title
 121          * @param string $field ('length','redirect','revision','model')
 122          * @return string|null
 123          */
 124         public function getGoodLinkFieldObj( $title, $field ) {
 125                 $dbkey = $title->getPrefixedDBkey();
 126                 if ( $this->mGoodLinks->has( $dbkey ) ) {
 127                         $info = $this->mGoodLinks->get( $dbkey );
 128                         return $info[$field];
 129                 } else {
 130                         return null;
 131                 }
 132         }
 133
 134         /**
 135          * @param string $title
 136          * @return bool
 137          */
 138         public function isBadLink( $title ) {
 139                 // We need to use get here since has will not call ping.
 140                 return $this->mBadLinks->get( $title ) !== null;
 141         }
 142
 143         /**
 144          * Add a link for the title to the link cache
 145          *
 146          * @param int $id Page's ID
 147          * @param Title $title
 148          * @param int $len Text's length
 149          * @param int $redir Whether the page is a redirect
 150          * @param int $revision Latest revision's ID
 151          * @param string|null $model Latest revision's content model ID
 152          */
 153         public function addGoodLinkObj( $id, $title, $len = -1, $redir = null,
 154                 $revision = 0, $model = null
 155         ) {
 156                 $dbkey = $title->getPrefixedDBkey();
 157                 $this->mGoodLinks->set( $dbkey, array(
 158                         'id' => (int)$id,
 159                         'length' => (int)$len,
 160                         'redirect' => (int)$redir,
 161                         'revision' => (int)$revision,
 162                         'model' => $model ? (string)$model : null,
 163                 ) );
 164         }
 165
 166         /**
 167          * Same as above with better interface.
 168          * @since 1.19
 169          * @param Title $title
 170          * @param stdClass $row Object which has the fields page_id, page_is_redirect,
 171          *  page_latest and page_content_model
 172          */
 173         public function addGoodLinkObjFromRow( $title, $row ) {
 174                 $dbkey = $title->getPrefixedDBkey();
 175                 $this->mGoodLinks->set( $dbkey, array(
 176                         'id' => intval( $row->page_id ),
 177                         'length' => intval( $row->page_len ),
 178                         'redirect' => intval( $row->page_is_redirect ),
 179                         'revision' => intval( $row->page_latest ),
 180                         'model' => !empty( $row->page_content_model ) ? strval( $row->page_content_model ) : null,
 181                 ) );
 182         }
 183
 184         /**
 185          * @param Title $title
 186          */
 187         public function addBadLinkObj( $title ) {
 188                 $dbkey = $title->getPrefixedDBkey();
 189                 if ( !$this->isBadLink( $dbkey ) ) {
 190                         $this->mBadLinks->set( $dbkey, 1 );
 191                 }
 192         }
 193
 194         public function clearBadLink( $title ) {
 195                 $this->mBadLinks->clear( array( $title ) );
 196         }
 197
 198         /**
 199          * @param Title $title
 200          */
 201         public function clearLink( $title ) {
 202                 $dbkey = $title->getPrefixedDBkey();
 203                 $this->mBadLinks->clear( array( $dbkey ) );
 204                 $this->mGoodLinks->clear( array( $dbkey ) );
 205         }
 206
 207
 208         /**
 209          * @deprecated since 1.26
 210          * @return array
 211          */
 212         public function getGoodLinks() {
 213                 wfDeprecated( __METHOD__, '1.26' );
 214                 $links = array();
 215                 foreach ( $this->mGoodLinks->getAllKeys() as $key ) {
 216                         $info = $this->mGoodLinks->get( $key );
 217                         $links[$key] = $info['id'];
 218                 }
 219
 220                 return $links;
 221         }
 222
 223         /**
 224          * @deprecated since 1.26
 225          * @return array
 226          */
 227         public function getBadLinks() {
 228                 wfDeprecated( __METHOD__, '1.26' );
 229                 return $this->mBadLinks->getAllKeys();
 230         }
 231
 232         /**
 233          * Add a title to the link cache, return the page_id or zero if non-existent
 234          *
 235          * @param string $title Title to add
 236          * @return int
 237          */
 238         public function addLink( $title ) {
 239                 $nt = Title::newFromDBkey( $title );
 240                 if ( $nt ) {
 241                         return $this->addLinkObj( $nt );
 242                 } else {
 243                         return 0;
 244                 }
 245         }
 246
 247         /**
 248          * Add a title to the link cache, return the page_id or zero if non-existent
 249          *
 250          * @param Title $nt Title object to add
 251          * @return int
 252          */
 253         public function addLinkObj( $nt ) {
 254                 global $wgContentHandlerUseDB;
 255
 256                 $key = $nt->getPrefixedDBkey();
 257                 if ( $this->isBadLink( $key ) || $nt->isExternal() ) {
 258                         return 0;
 259                 }
 260                 $id = $this->getGoodLinkID( $key );
 261                 if ( $id != 0 ) {
 262                         return $id;
 263                 }
 264
 265                 if ( $key === '' ) {
 266                         return 0;
 267                 }
 268
 269                 # Some fields heavily used for linking...
 270                 if ( $this->mForUpdate ) {
 271                         $db = wfGetDB( DB_MASTER );
 272                 } else {
 273                         $db = wfGetDB( DB_SLAVE );
 274                 }
 275
 276                 $f = array( 'page_id', 'page_len', 'page_is_redirect', 'page_latest' );
 277                 if ( $wgContentHandlerUseDB ) {
 278                         $f[] = 'page_content_model';
 279                 }
 280
 281                 $s = $db->selectRow( 'page', $f,
 282                         array( 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ),
 283                         __METHOD__ );
 284                 # Set fields...
 285                 if ( $s !== false ) {
 286                         $this->addGoodLinkObjFromRow( $nt, $s );
 287                         $id = intval( $s->page_id );
 288                 } else {
 289                         $this->addBadLinkObj( $nt );
 290                         $id = 0;
 291                 }
 292
 293                 return $id;
 294         }
 295
 296         /**
 297          * Clears cache
 298          */
 299         public function clear() {
 300                 $this->mGoodLinks->clear();
 301                 $this->mBadLinks->clear();
 302         }
 303 }