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<?php
/**
* Page existence cache.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @ingroup Cache
*/
/**
* Cache for article titles (prefixed DB keys) and ids linked from one source
*
* @ingroup Cache
*/
class LinkCache {
// Increment $mClassVer whenever old serialized versions of this class
// becomes incompatible with the new version.
private $mClassVer = 4;
private $mGoodLinks = array();
private $mGoodLinkFields = array();
private $mBadLinks = array();
private $mForUpdate = false;
/**
* Get an instance of this class
*
* @return LinkCache
*/
static function &singleton() {
static $instance;
if ( !isset( $instance ) ) {
$instance = new LinkCache;
}
return $instance;
}
/**
* General accessor to get/set whether SELECT FOR UPDATE should be used
*
* @return bool
*/
public function forUpdate( $update = null ) {
return wfSetVar( $this->mForUpdate, $update );
}
/**
* @param $title
* @return array|int
*/
public function getGoodLinkID( $title ) {
if ( array_key_exists( $title, $this->mGoodLinks ) ) {
return $this->mGoodLinks[$title];
} else {
return 0;
}
}
/**
* Get a field of a title object from cache.
* If this link is not good, it will return NULL.
* @param $title Title
* @param string $field ('length','redirect','revision','model')
* @return mixed
*/
public function getGoodLinkFieldObj( $title, $field ) {
$dbkey = $title->getPrefixedDBkey();
if ( array_key_exists( $dbkey, $this->mGoodLinkFields ) ) {
return $this->mGoodLinkFields[$dbkey][$field];
} else {
return null;
}
}
/**
* @param $title
* @return bool
*/
public function isBadLink( $title ) {
return array_key_exists( $title, $this->mBadLinks );
}
/**
* Add a link for the title to the link cache
*
* @param $id Integer: page's ID
* @param $title Title object
* @param $len Integer: text's length
* @param $redir Integer: whether the page is a redirect
* @param $revision Integer: latest revision's ID
* @param $model Integer: latest revision's content model ID
*/
public function addGoodLinkObj( $id, $title, $len = -1, $redir = null, $revision = false, $model = false ) {
$dbkey = $title->getPrefixedDBkey();
$this->mGoodLinks[$dbkey] = intval( $id );
$this->mGoodLinkFields[$dbkey] = array(
'length' => intval( $len ),
'redirect' => intval( $redir ),
'revision' => intval( $revision ),
'model' => intval( $model ) );
}
/**
* Same as above with better interface.
* @since 1.19
* @param $title Title
* @param $row object which has the fields page_id, page_is_redirect,
* page_latest and page_content_model
*/
public function addGoodLinkObjFromRow( $title, $row ) {
$dbkey = $title->getPrefixedDBkey();
$this->mGoodLinks[$dbkey] = intval( $row->page_id );
$this->mGoodLinkFields[$dbkey] = array(
'length' => intval( $row->page_len ),
'redirect' => intval( $row->page_is_redirect ),
'revision' => intval( $row->page_latest ),
'model' => !empty( $row->page_content_model ) ? strval( $row->page_content_model ) : null,
);
}
/**
* @param $title Title
*/
public function addBadLinkObj( $title ) {
$dbkey = $title->getPrefixedDBkey();
if ( !$this->isBadLink( $dbkey ) ) {
$this->mBadLinks[$dbkey] = 1;
}
}
public function clearBadLink( $title ) {
unset( $this->mBadLinks[$title] );
}
/**
* @param $title Title
*/
public function clearLink( $title ) {
$dbkey = $title->getPrefixedDBkey();
unset( $this->mBadLinks[$dbkey] );
unset( $this->mGoodLinks[$dbkey] );
unset( $this->mGoodLinkFields[$dbkey] );
}
public function getGoodLinks() { return $this->mGoodLinks; }
public function getBadLinks() { return array_keys( $this->mBadLinks ); }
/**
* Add a title to the link cache, return the page_id or zero if non-existent
*
* @param string $title title to add
* @return Integer
*/
public function addLink( $title ) {
$nt = Title::newFromDBkey( $title );
if( $nt ) {
return $this->addLinkObj( $nt );
} else {
return 0;
}
}
/**
* Add a title to the link cache, return the page_id or zero if non-existent
*
* @param $nt Title object to add
* @return Integer
*/
public function addLinkObj( $nt ) {
global $wgAntiLockFlags, $wgContentHandlerUseDB;
wfProfileIn( __METHOD__ );
$key = $nt->getPrefixedDBkey();
if ( $this->isBadLink( $key ) || $nt->isExternal() ) {
wfProfileOut( __METHOD__ );
return 0;
}
$id = $this->getGoodLinkID( $key );
if ( $id != 0 ) {
wfProfileOut( __METHOD__ );
return $id;
}
if ( $key === '' ) {
wfProfileOut( __METHOD__ );
return 0;
}
# Some fields heavily used for linking...
if ( $this->mForUpdate ) {
$db = wfGetDB( DB_MASTER );
if ( !( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) ) {
$options = array( 'FOR UPDATE' );
} else {
$options = array();
}
} else {
$db = wfGetDB( DB_SLAVE );
$options = array();
}
$f = array( 'page_id', 'page_len', 'page_is_redirect', 'page_latest' );
if ( $wgContentHandlerUseDB ) $f[] = 'page_content_model';
$s = $db->selectRow( 'page', $f,
array( 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ),
__METHOD__, $options );
# Set fields...
if ( $s !== false ) {
$this->addGoodLinkObjFromRow( $nt, $s );
$id = intval( $s->page_id );
} else {
$this->addBadLinkObj( $nt );
$id = 0;
}
wfProfileOut( __METHOD__ );
return $id;
}
/**
* Clears cache
*/
public function clear() {
$this->mGoodLinks = array();
$this->mGoodLinkFields = array();
$this->mBadLinks = array();
}
}