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 use MediaWiki\Linker\LinkTarget;
  24 use MediaWiki\MediaWikiServices;
  25
  26 /**
  27  * Cache for article titles (prefixed DB keys) and ids linked from one source
  28  *
  29  * @ingroup Cache
  30  */
  31 class LinkCache {
  32         /**
  33          * @var HashBagOStuff
  34          */
  35         private $mGoodLinks;
  36         /**
  37          * @var HashBagOStuff
  38          */
  39         private $mBadLinks;
  40         private $mForUpdate = false;
  41
  42         /**
  43          * @var TitleFormatter
  44          */
  45         private $titleFormatter;
  46
  47         /**
  48          * How many Titles to store. There are two caches, so the amount actually
  49          * stored in memory can be up to twice this.
  50          */
  51         const MAX_SIZE = 10000;
  52
  53         /**
  54          * @var LinkCache
  55          */
  56         protected static $instance;
  57
  58         public function __construct( TitleFormatter $titleFormatter ) {
  59                 $this->mGoodLinks = new HashBagOStuff( [ 'maxKeys' => self::MAX_SIZE ] );
  60                 $this->mBadLinks = new HashBagOStuff( [ 'maxKeys' => self::MAX_SIZE ] );
  61                 $this->titleFormatter = $titleFormatter;
  62         }
  63
  64         /**
  65          * Get an instance of this class.
  66          *
  67          * @return LinkCache
  68          * @deprecated since 1.28, use MediaWikiServices instead
  69          */
  70         public static function singleton() {
  71                 return MediaWikiServices::getInstance()->getLinkCache();
  72         }
  73
  74         /**
  75          * General accessor to get/set whether the master DB should be used
  76          *
  77          * This used to also set the FOR UPDATE option (locking the rows read
  78          * in order to avoid link table inconsistency), which was later removed
  79          * for performance on wikis with a high edit rate.
  80          *
  81          * @param bool $update
  82          * @return bool
  83          */
  84         public function forUpdate( $update = null ) {
  85                 return wfSetVar( $this->mForUpdate, $update );
  86         }
  87
  88         /**
  89          * @param string $title Prefixed DB key
  90          * @return int Page ID or zero
  91          */
  92         public function getGoodLinkID( $title ) {
  93                 $info = $this->mGoodLinks->get( $title );
  94                 if ( !$info ) {
  95                         return 0;
  96                 }
  97                 return $info['id'];
  98         }
  99
 100         /**
 101          * Get a field of a title object from cache.
 102          * If this link is not a cached good title, it will return NULL.
 103          * @param LinkTarget $target
 104          * @param string $field ('length','redirect','revision','model')
 105          * @return string|int|null
 106          */
 107         public function getGoodLinkFieldObj( LinkTarget $target, $field ) {
 108                 $dbkey = $this->titleFormatter->getPrefixedDBkey( $target );
 109                 $info = $this->mGoodLinks->get( $dbkey );
 110                 if ( !$info ) {
 111                         return null;
 112                 }
 113                 return $info[$field];
 114         }
 115
 116         /**
 117          * @param string $title Prefixed DB key
 118          * @return bool
 119          */
 120         public function isBadLink( $title ) {
 121                 // Use get() to ensure it records as used for LRU.
 122                 return $this->mBadLinks->get( $title ) !== false;
 123         }
 124
 125         /**
 126          * Add a link for the title to the link cache
 127          *
 128          * @param int $id Page's ID
 129          * @param LinkTarget $target
 130          * @param int $len Text's length
 131          * @param int $redir Whether the page is a redirect
 132          * @param int $revision Latest revision's ID
 133          * @param string|null $model Latest revision's content model ID
 134          * @param string|null $lang Language code of the page, if not the content language
 135          */
 136         public function addGoodLinkObj( $id, LinkTarget $target, $len = -1, $redir = null,
 137                 $revision = 0, $model = null, $lang = null
 138         ) {
 139                 $dbkey = $this->titleFormatter->getPrefixedDBkey( $target );
 140                 $this->mGoodLinks->set( $dbkey, [
 141                         'id' => (int)$id,
 142                         'length' => (int)$len,
 143                         'redirect' => (int)$redir,
 144                         'revision' => (int)$revision,
 145                         'model' => $model ? (string)$model : null,
 146                         'lang' => $lang ? (string)$lang : null,
 147                 ] );
 148         }
 149
 150         /**
 151          * Same as above with better interface.
 152          * @since 1.19
 153          * @param LinkTarget $target
 154          * @param stdClass $row Object which has the fields page_id, page_is_redirect,
 155          *  page_latest and page_content_model
 156          */
 157         public function addGoodLinkObjFromRow( LinkTarget $target, $row ) {
 158                 $dbkey = $this->titleFormatter->getPrefixedDBkey( $target );
 159                 $this->mGoodLinks->set( $dbkey, [
 160                         'id' => intval( $row->page_id ),
 161                         'length' => intval( $row->page_len ),
 162                         'redirect' => intval( $row->page_is_redirect ),
 163                         'revision' => intval( $row->page_latest ),
 164                         'model' => !empty( $row->page_content_model ) ? strval( $row->page_content_model ) : null,
 165                         'lang' => !empty( $row->page_lang ) ? strval( $row->page_lang ) : null,
 166                 ] );
 167         }
 168
 169         /**
 170          * @param LinkTarget $target
 171          */
 172         public function addBadLinkObj( LinkTarget $target ) {
 173                 $dbkey = $this->titleFormatter->getPrefixedDBkey( $target );
 174                 if ( !$this->isBadLink( $dbkey ) ) {
 175                         $this->mBadLinks->set( $dbkey, 1 );
 176                 }
 177         }
 178
 179         /**
 180          * @param string $title Prefixed DB key
 181          */
 182         public function clearBadLink( $title ) {
 183                 $this->mBadLinks->delete( $title );
 184         }
 185
 186         /**
 187          * @param LinkTarget $target
 188          */
 189         public function clearLink( LinkTarget $target ) {
 190                 $dbkey = $this->titleFormatter->getPrefixedDBkey( $target );
 191                 $this->mBadLinks->delete( $dbkey );
 192                 $this->mGoodLinks->delete( $dbkey );
 193         }
 194
 195         /**
 196          * Add a title to the link cache, return the page_id or zero if non-existent
 197          *
 198          * @deprecated since 1.27, unused
 199          * @param string $title Prefixed DB key
 200          * @return int Page ID or zero
 201          */
 202         public function addLink( $title ) {
 203                 $nt = Title::newFromDBkey( $title );
 204                 if ( !$nt ) {
 205                         return 0;
 206                 }
 207                 return $this->addLinkObj( $nt );
 208         }
 209
 210         /**
 211          * Add a title to the link cache, return the page_id or zero if non-existent
 212          *
 213          * @param LinkTarget $nt LinkTarget object to add
 214          * @return int Page ID or zero
 215          */
 216         public function addLinkObj( LinkTarget $nt ) {
 217                 global $wgContentHandlerUseDB, $wgPageLanguageUseDB;
 218
 219                 $key = $this->titleFormatter->getPrefixedDBkey( $nt );
 220                 if ( $this->isBadLink( $key ) || $nt->isExternal() ) {
 221                         return 0;
 222                 }
 223                 $id = $this->getGoodLinkID( $key );
 224                 if ( $id != 0 ) {
 225                         return $id;
 226                 }
 227
 228                 if ( $key === '' ) {
 229                         return 0;
 230                 }
 231
 232                 // Some fields heavily used for linking...
 233                 $db = $this->mForUpdate ? wfGetDB( DB_MASTER ) : wfGetDB( DB_SLAVE );
 234
 235                 $fields = [ 'page_id', 'page_len', 'page_is_redirect', 'page_latest' ];
 236                 if ( $wgContentHandlerUseDB ) {
 237                         $fields[] = 'page_content_model';
 238                 }
 239                 if ( $wgPageLanguageUseDB ) {
 240                         $fields[] = 'page_lang';
 241                 }
 242
 243                 $row = $db->selectRow( 'page', $fields,
 244                         [ 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ],
 245                         __METHOD__
 246                 );
 247
 248                 if ( $row !== false ) {
 249                         $this->addGoodLinkObjFromRow( $nt, $row );
 250                         $id = intval( $row->page_id );
 251                 } else {
 252                         $this->addBadLinkObj( $nt );
 253                         $id = 0;
 254                 }
 255
 256                 return $id;
 257         }
 258
 259         /**
 260          * Clears cache
 261          */
 262         public function clear() {
 263                 $this->mGoodLinks->clear();
 264                 $this->mBadLinks->clear();
 265         }
 266 }