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 = 4;
  33
  34         private $mGoodLinks = array();
  35         private $mGoodLinkFields = array();
  36         private $mBadLinks = array();
  37         private $mForUpdate = false;
  38
  39         /**
  40          * Get an instance of this class
  41          *
  42          * @return LinkCache
  43          */
  44         static function &singleton() {
  45                 static $instance;
  46                 if ( !isset( $instance ) ) {
  47                         $instance = new LinkCache;
  48                 }
  49                 return $instance;
  50         }
  51
  52         /**
  53          * General accessor to get/set whether SELECT FOR UPDATE should be used
  54          *
  55          * @return bool
  56          */
  57         public function forUpdate( $update = null ) {
  58                 return wfSetVar( $this->mForUpdate, $update );
  59         }
  60
  61         /**
  62          * @param $title
  63          * @return array|int
  64          */
  65         public function getGoodLinkID( $title ) {
  66                 if ( array_key_exists( $title, $this->mGoodLinks ) ) {
  67                         return $this->mGoodLinks[$title];
  68                 } else {
  69                         return 0;
  70                 }
  71         }
  72
  73         /**
  74          * Get a field of a title object from cache.
  75          * If this link is not good, it will return NULL.
  76          * @param $title Title
  77          * @param string $field ('length','redirect','revision','model')
  78          * @return mixed
  79          */
  80         public function getGoodLinkFieldObj( $title, $field ) {
  81                 $dbkey = $title->getPrefixedDBkey();
  82                 if ( array_key_exists( $dbkey, $this->mGoodLinkFields ) ) {
  83                         return $this->mGoodLinkFields[$dbkey][$field];
  84                 } else {
  85                         return null;
  86                 }
  87         }
  88
  89         /**
  90          * @param $title
  91          * @return bool
  92          */
  93         public function isBadLink( $title ) {
  94                 return array_key_exists( $title, $this->mBadLinks );
  95         }
  96
  97         /**
  98          * Add a link for the title to the link cache
  99          *
 100          * @param $id Integer: page's ID
 101          * @param $title Title object
 102          * @param $len Integer: text's length
 103          * @param $redir Integer: whether the page is a redirect
 104          * @param $revision Integer: latest revision's ID
 105          * @param $model Integer: latest revision's content model ID
 106          */
 107         public function addGoodLinkObj( $id, $title, $len = -1, $redir = null, $revision = false, $model = false ) {
 108                 $dbkey = $title->getPrefixedDBkey();
 109                 $this->mGoodLinks[$dbkey] = intval( $id );
 110                 $this->mGoodLinkFields[$dbkey] = array(
 111                         'length' => intval( $len ),
 112                         'redirect' => intval( $redir ),
 113                         'revision' => intval( $revision ),
 114                         'model' => intval( $model ) );
 115         }
 116
 117         /**
 118          * Same as above with better interface.
 119          * @since 1.19
 120          * @param $title Title
 121          * @param $row object which has the fields page_id, page_is_redirect,
 122          *  page_latest and page_content_model
 123          */
 124         public function addGoodLinkObjFromRow( $title, $row ) {
 125                 $dbkey = $title->getPrefixedDBkey();
 126                 $this->mGoodLinks[$dbkey] = intval( $row->page_id );
 127                 $this->mGoodLinkFields[$dbkey] = array(
 128                         'length' => intval( $row->page_len ),
 129                         'redirect' => intval( $row->page_is_redirect ),
 130                         'revision' => intval( $row->page_latest ),
 131                         'model' => !empty( $row->page_content_model ) ? strval( $row->page_content_model ) : null,
 132                 );
 133         }
 134
 135         /**
 136          * @param $title Title
 137          */
 138         public function addBadLinkObj( $title ) {
 139                 $dbkey = $title->getPrefixedDBkey();
 140                 if ( !$this->isBadLink( $dbkey ) ) {
 141                         $this->mBadLinks[$dbkey] = 1;
 142                 }
 143         }
 144
 145         public function clearBadLink( $title ) {
 146                 unset( $this->mBadLinks[$title] );
 147         }
 148
 149         /**
 150          * @param $title Title
 151          */
 152         public function clearLink( $title ) {
 153                 $dbkey = $title->getPrefixedDBkey();
 154                 unset( $this->mBadLinks[$dbkey] );
 155                 unset( $this->mGoodLinks[$dbkey] );
 156                 unset( $this->mGoodLinkFields[$dbkey] );
 157         }
 158
 159         public function getGoodLinks() {
 160                 return $this->mGoodLinks;
 161         }
 162
 163         public function getBadLinks() {
 164                 return array_keys( $this->mBadLinks );
 165         }
 166
 167         /**
 168          * Add a title to the link cache, return the page_id or zero if non-existent
 169          *
 170          * @param string $title title to add
 171          * @return Integer
 172          */
 173         public function addLink( $title ) {
 174                 $nt = Title::newFromDBkey( $title );
 175                 if ( $nt ) {
 176                         return $this->addLinkObj( $nt );
 177                 } else {
 178                         return 0;
 179                 }
 180         }
 181
 182         /**
 183          * Add a title to the link cache, return the page_id or zero if non-existent
 184          *
 185          * @param $nt Title object to add
 186          * @return Integer
 187          */
 188         public function addLinkObj( $nt ) {
 189                 global $wgAntiLockFlags, $wgContentHandlerUseDB;
 190
 191                 wfProfileIn( __METHOD__ );
 192
 193                 $key = $nt->getPrefixedDBkey();
 194                 if ( $this->isBadLink( $key ) || $nt->isExternal() ) {
 195                         wfProfileOut( __METHOD__ );
 196                         return 0;
 197                 }
 198                 $id = $this->getGoodLinkID( $key );
 199                 if ( $id != 0 ) {
 200                         wfProfileOut( __METHOD__ );
 201                         return $id;
 202                 }
 203
 204                 if ( $key === '' ) {
 205                         wfProfileOut( __METHOD__ );
 206                         return 0;
 207                 }
 208
 209                 # Some fields heavily used for linking...
 210                 if ( $this->mForUpdate ) {
 211                         $db = wfGetDB( DB_MASTER );
 212                         if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
 213                                 $options = array( 'FOR UPDATE' );
 214                         } else {
 215                                 $options = array();
 216                         }
 217                 } else {
 218                         $db = wfGetDB( DB_SLAVE );
 219                         $options = array();
 220                 }
 221
 222                 $f = array( 'page_id', 'page_len', 'page_is_redirect', 'page_latest' );
 223                 if ( $wgContentHandlerUseDB ) {
 224                         $f[] = 'page_content_model';
 225                 }
 226
 227                 $s = $db->selectRow( 'page', $f,
 228                         array( 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ),
 229                         __METHOD__, $options );
 230                 # Set fields...
 231                 if ( $s !== false ) {
 232                         $this->addGoodLinkObjFromRow( $nt, $s );
 233                         $id = intval( $s->page_id );
 234                 } else {
 235                         $this->addBadLinkObj( $nt );
 236                         $id = 0;
 237                 }
 238
 239                 wfProfileOut( __METHOD__ );
 240                 return $id;
 241         }
 242
 243         /**
 244          * Clears cache
 245          */
 246         public function clear() {
 247                 $this->mGoodLinks = array();
 248                 $this->mGoodLinkFields = array();
 249                 $this->mBadLinks = array();
 250         }
 251 }