Current File : //www/varak.net/wiki.varak.net/includes/cache/LinkCache.php
<?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
*/
use Wikimedia\Rdbms\Database;
use Wikimedia\Rdbms\IDatabase;
use MediaWiki\Linker\LinkTarget;
use MediaWiki\MediaWikiServices;
/**
* Cache for article titles (prefixed DB keys) and ids linked from one source
*
* @ingroup Cache
*/
class LinkCache {
/** @var MapCacheLRU */
private $goodLinks;
/** @var MapCacheLRU */
private $badLinks;
/** @var WANObjectCache */
private $wanCache;
/** @var bool */
private $mForUpdate = false;
/** @var TitleFormatter */
private $titleFormatter;
/**
* How many Titles to store. There are two caches, so the amount actually
* stored in memory can be up to twice this.
*/
const MAX_SIZE = 10000;
public function __construct( TitleFormatter $titleFormatter, WANObjectCache $cache ) {
$this->goodLinks = new MapCacheLRU( self::MAX_SIZE );
$this->badLinks = new MapCacheLRU( self::MAX_SIZE );
$this->wanCache = $cache;
$this->titleFormatter = $titleFormatter;
}
/**
* Get an instance of this class.
*
* @return LinkCache
* @deprecated since 1.28, use MediaWikiServices instead
*/
public static function singleton() {
return MediaWikiServices::getInstance()->getLinkCache();
}
/**
* General accessor to get/set whether the master DB should be used
*
* This used to also set the FOR UPDATE option (locking the rows read
* in order to avoid link table inconsistency), which was later removed
* for performance on wikis with a high edit rate.
*
* @param bool|null $update
* @return bool
*/
public function forUpdate( $update = null ) {
return wfSetVar( $this->mForUpdate, $update );
}
/**
* @param string $title Prefixed DB key
* @return int Page ID or zero
*/
public function getGoodLinkID( $title ) {
$info = $this->goodLinks->get( $title );
if ( !$info ) {
return 0;
}
return $info['id'];
}
/**
* Get a field of a title object from cache.
* If this link is not a cached good title, it will return NULL.
* @param LinkTarget $target
* @param string $field ('length','redirect','revision','model')
* @return string|int|null
*/
public function getGoodLinkFieldObj( LinkTarget $target, $field ) {
$dbkey = $this->titleFormatter->getPrefixedDBkey( $target );
$info = $this->goodLinks->get( $dbkey );
if ( !$info ) {
return null;
}
return $info[$field];
}
/**
* @param string $title Prefixed DB key
* @return bool
*/
public function isBadLink( $title ) {
// Use get() to ensure it records as used for LRU.
return $this->badLinks->has( $title );
}
/**
* Add a link for the title to the link cache
*
* @param int $id Page's ID
* @param LinkTarget $target
* @param int $len Text's length
* @param int|null $redir Whether the page is a redirect
* @param int $revision Latest revision's ID
* @param string|null $model Latest revision's content model ID
* @param string|null $lang Language code of the page, if not the content language
*/
public function addGoodLinkObj( $id, LinkTarget $target, $len = -1, $redir = null,
$revision = 0, $model = null, $lang = null
) {
$dbkey = $this->titleFormatter->getPrefixedDBkey( $target );
$this->goodLinks->set( $dbkey, [
'id' => (int)$id,
'length' => (int)$len,
'redirect' => (int)$redir,
'revision' => (int)$revision,
'model' => $model ? (string)$model : null,
'lang' => $lang ? (string)$lang : null,
] );
}
/**
* Same as above with better interface.
* @since 1.19
* @param LinkTarget $target
* @param stdClass $row Object which has the fields page_id, page_is_redirect,
* page_latest and page_content_model
*/
public function addGoodLinkObjFromRow( LinkTarget $target, $row ) {
$dbkey = $this->titleFormatter->getPrefixedDBkey( $target );
$this->goodLinks->set( $dbkey, [
'id' => intval( $row->page_id ),
'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,
'lang' => !empty( $row->page_lang ) ? strval( $row->page_lang ) : null,
] );
}
/**
* @param LinkTarget $target
*/
public function addBadLinkObj( LinkTarget $target ) {
$dbkey = $this->titleFormatter->getPrefixedDBkey( $target );
if ( !$this->isBadLink( $dbkey ) ) {
$this->badLinks->set( $dbkey, 1 );
}
}
/**
* @param string $title Prefixed DB key
*/
public function clearBadLink( $title ) {
$this->badLinks->clear( $title );
}
/**
* @param LinkTarget $target
*/
public function clearLink( LinkTarget $target ) {
$dbkey = $this->titleFormatter->getPrefixedDBkey( $target );
$this->badLinks->clear( $dbkey );
$this->goodLinks->clear( $dbkey );
}
/**
* Add a title to the link cache, return the page_id or zero if non-existent
*
* @deprecated since 1.27, unused
* @param string $title Prefixed DB key
* @return int Page ID or zero
*/
public function addLink( $title ) {
$nt = Title::newFromDBkey( $title );
if ( !$nt ) {
return 0;
}
return $this->addLinkObj( $nt );
}
/**
* Fields that LinkCache needs to select
*
* @since 1.28
* @return array
*/
public static function getSelectFields() {
global $wgContentHandlerUseDB, $wgPageLanguageUseDB;
$fields = [ 'page_id', 'page_len', 'page_is_redirect', 'page_latest' ];
if ( $wgContentHandlerUseDB ) {
$fields[] = 'page_content_model';
}
if ( $wgPageLanguageUseDB ) {
$fields[] = 'page_lang';
}
return $fields;
}
/**
* Add a title to the link cache, return the page_id or zero if non-existent
*
* @param LinkTarget $nt LinkTarget object to add
* @return int Page ID or zero
*/
public function addLinkObj( LinkTarget $nt ) {
$key = $this->titleFormatter->getPrefixedDBkey( $nt );
if ( $this->isBadLink( $key ) || $nt->isExternal()
|| $nt->inNamespace( NS_SPECIAL )
) {
return 0;
}
$id = $this->getGoodLinkID( $key );
if ( $id != 0 ) {
return $id;
}
if ( $key === '' ) {
return 0;
}
// Cache template/file pages as they are less often viewed but heavily used
if ( $this->mForUpdate ) {
$row = $this->fetchPageRow( wfGetDB( DB_MASTER ), $nt );
} elseif ( $this->isCacheable( $nt ) ) {
// These pages are often transcluded heavily, so cache them
$cache = $this->wanCache;
$row = $cache->getWithSetCallback(
$cache->makeKey( 'page', $nt->getNamespace(), sha1( $nt->getDBkey() ) ),
$cache::TTL_DAY,
function ( $curValue, &$ttl, array &$setOpts ) use ( $cache, $nt ) {
$dbr = wfGetDB( DB_REPLICA );
$setOpts += Database::getCacheSetOptions( $dbr );
$row = $this->fetchPageRow( $dbr, $nt );
$mtime = $row ? wfTimestamp( TS_UNIX, $row->page_touched ) : false;
$ttl = $cache->adaptiveTTL( $mtime, $ttl );
return $row;
}
);
} else {
$row = $this->fetchPageRow( wfGetDB( DB_REPLICA ), $nt );
}
if ( $row ) {
$this->addGoodLinkObjFromRow( $nt, $row );
$id = intval( $row->page_id );
} else {
$this->addBadLinkObj( $nt );
$id = 0;
}
return $id;
}
/**
* @param WANObjectCache $cache
* @param LinkTarget $t
* @return string[]
* @since 1.28
*/
public function getMutableCacheKeys( WANObjectCache $cache, LinkTarget $t ) {
if ( $this->isCacheable( $t ) ) {
return [ $cache->makeKey( 'page', $t->getNamespace(), sha1( $t->getDBkey() ) ) ];
}
return [];
}
private function isCacheable( LinkTarget $title ) {
return ( $title->inNamespace( NS_TEMPLATE ) || $title->inNamespace( NS_FILE ) );
}
private function fetchPageRow( IDatabase $db, LinkTarget $nt ) {
$fields = self::getSelectFields();
if ( $this->isCacheable( $nt ) ) {
$fields[] = 'page_touched';
}
return $db->selectRow(
'page',
$fields,
[ 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ],
__METHOD__
);
}
/**
* Purge the link cache for a title
*
* @param LinkTarget $title
* @since 1.28
*/
public function invalidateTitle( LinkTarget $title ) {
if ( $this->isCacheable( $title ) ) {
$cache = $this->wanCache;
$cache->delete(
$cache->makeKey( 'page', $title->getNamespace(), sha1( $title->getDBkey() ) )
);
}
}
/**
* Clears cache
*/
public function clear() {
$this->goodLinks->clear();
$this->badLinks->clear();
}
}
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