includes/linker/LinkTargetStore.php
<?php
/**
* 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
*/
namespace MediaWiki\Linker;
use BagOStuff;
use InvalidArgumentException;
use MediaWiki\Title\TitleValue;
use RuntimeException;
use stdClass;
use WANObjectCache;
use Wikimedia\Rdbms\IConnectionProvider;
use Wikimedia\Rdbms\IDatabase;
/**
* Service for retrieving and storing link targets.
*
* @since 1.38
*/
class LinkTargetStore implements LinkTargetLookup {
/** @var IConnectionProvider */
private $dbProvider;
/** @var BagOStuff */
private $localCache;
/** @var WANObjectCache */
private $wanObjectCache;
/** @var array<int, LinkTarget> */
private $byIdCache;
/** @var array<string, int> */
private $byTitleCache;
/**
* @param IConnectionProvider $dbProvider
* @param BagOStuff $localCache
* @param WANObjectCache $WanObjectCache
*/
public function __construct(
IConnectionProvider $dbProvider,
BagOStuff $localCache,
WANObjectCache $WanObjectCache
) {
$this->dbProvider = $dbProvider;
$this->localCache = $localCache;
$this->wanObjectCache = $WanObjectCache;
$this->byIdCache = [];
$this->byTitleCache = [];
}
/**
* @inheritDoc
*/
public function newLinkTargetFromRow( stdClass $row ): LinkTarget {
$ltId = (int)$row->lt_id;
if ( $ltId === 0 ) {
throw new InvalidArgumentException(
"LinkTarget ID is 0 for {$row->lt_title} (ns: {$row->lt_namespace})"
);
}
$titlevalue = new TitleValue( (int)$row->lt_namespace, $row->lt_title );
$this->addToClassCache( $ltId, $titlevalue );
return $titlevalue;
}
/**
* Find a link target by $id.
*
* @param int $linkTargetId
* @return LinkTarget|null Returns null if no link target with this $linkTargetId exists in the database.
*/
public function getLinkTargetById( int $linkTargetId ): ?LinkTarget {
if ( !$linkTargetId ) {
return null;
}
if ( isset( $this->byIdCache[$linkTargetId] ) ) {
return $this->byIdCache[$linkTargetId];
}
$value = $this->dbProvider->getReplicaDatabase()->newSelectQueryBuilder()
->caller( __METHOD__ )
->table( 'linktarget' )
->conds( [ 'lt_id' => $linkTargetId ] )
->fields( [ 'lt_id', 'lt_namespace', 'lt_title' ] )
->fetchRow();
if ( !$value ) {
return null;
}
// TODO: Use local and wan cache when writing read new code.
$linkTarget = $this->newLinkTargetFromRow( $value );
$this->addToClassCache( $linkTargetId, $linkTarget );
return $linkTarget;
}
/**
* Return link target id if exists
*
* @param LinkTarget $linkTarget
* @return int|null linktarget ID greater then 0, null if not found
*/
public function getLinkTargetId( LinkTarget $linkTarget ): ?int {
// allow cache to be used, because if it is in the cache, it already has a linktarget id
return $this->getLinkTargetIdFromCache( $linkTarget ) ?: null;
}
/**
* Attempt to assign a link target ID to the given $linkTarget. If it is already assigned,
* return the existing ID.
*
* @note If called within a transaction, the returned ID might become invalid
* if the transaction is rolled back, so it should not be passed outside of the
* transaction context.
*
* @param LinkTarget $linkTarget
* @param IDatabase $dbw The database connection to acquire the ID from.
* @return int linktarget ID greater then 0
* @throws RuntimeException if no linktarget ID has been assigned to this $linkTarget
*/
public function acquireLinkTargetId( LinkTarget $linkTarget, IDatabase $dbw ): int {
// allow cache to be used, because if it is in the cache, it already has a linktarget id
$existingLinktargetId = $this->getLinkTargetIdFromCache( $linkTarget );
if ( $existingLinktargetId ) {
return $existingLinktargetId;
}
// Checking primary when it doesn't exist in replica is not that useful but given
// the fact that failed inserts waste an auto_increment id better to avoid that.
$linkTargetId = $this->fetchIdFromDbPrimary( $linkTarget );
if ( $linkTargetId ) {
$this->addToClassCache( $linkTargetId, $linkTarget );
return $linkTargetId;
}
$ns = $linkTarget->getNamespace();
$title = $linkTarget->getDBkey();
$dbw->newInsertQueryBuilder()
->insertInto( 'linktarget' )
->ignore()
->row( [ 'lt_namespace' => $ns, 'lt_title' => $title ] )
->caller( __METHOD__ )->execute();
if ( $dbw->affectedRows() ) {
$linkTargetId = $dbw->insertId();
} else {
// Use LOCK IN SHARE MODE to bypass any MySQL REPEATABLE-READ snapshot.
$linkTargetId = $this->fetchIdFromDbPrimary( $linkTarget, true );
if ( !$linkTargetId ) {
throw new RuntimeException(
"Failed to create link target ID for " .
"lt_namespace={$ns} lt_title=\"{$title}\""
);
}
}
$this->addToClassCache( $linkTargetId, $linkTarget );
return $linkTargetId;
}
/**
* Find lt_id of the given $linkTarget
*
* @param LinkTarget $linkTarget
* @param bool $lockInShareMode
* @return int|null
*/
private function fetchIdFromDbPrimary(
LinkTarget $linkTarget,
bool $lockInShareMode = false
): ?int {
$queryBuilder = $this->dbProvider->getPrimaryDatabase()->newSelectQueryBuilder()
->select( [ 'lt_id', 'lt_namespace', 'lt_title' ] )
->from( 'linktarget' )
->where( [ 'lt_namespace' => $linkTarget->getNamespace(), 'lt_title' => $linkTarget->getDBkey() ] );
if ( $lockInShareMode ) {
$queryBuilder->lockInShareMode();
}
$row = $queryBuilder->caller( __METHOD__ )->fetchRow();
if ( !$row || !$row->lt_id ) {
return null;
}
$this->addToClassCache( (int)$row->lt_id, $linkTarget );
return (int)$row->lt_id;
}
private function addToClassCache( int $id, LinkTarget $linkTarget ) {
$this->byIdCache[$id] = $linkTarget;
$this->byTitleCache[(string)$linkTarget] = $id;
}
/*
* @internal use by tests only
*/
public function clearClassCache() {
$this->byIdCache = [];
$this->byTitleCache = [];
}
/**
* @param LinkTarget $linkTarget
* @return int|false
*/
private function getLinkTargetIdFromCache( LinkTarget $linkTarget ) {
$linkTargetString = (string)$linkTarget;
if ( isset( $this->byTitleCache[$linkTargetString] ) ) {
return $this->byTitleCache[$linkTargetString];
}
$fname = __METHOD__;
$res = $this->localCache->getWithSetCallback(
$this->localCache->makeKey(
'linktargetstore-id',
$linkTargetString
),
$this->localCache::TTL_HOUR,
function () use ( $linkTarget, $fname ) {
return $this->wanObjectCache->getWithSetCallback(
$this->wanObjectCache->makeKey(
'linktargetstore-id',
(string)$linkTarget
),
WANObjectCache::TTL_DAY,
function () use ( $linkTarget, $fname ) {
$row = $this->dbProvider->getReplicaDatabase()->newSelectQueryBuilder()
->select( [ 'lt_id', 'lt_namespace', 'lt_title' ] )
->from( 'linktarget' )
->where( [
'lt_namespace' => $linkTarget->getNamespace(),
'lt_title' => $linkTarget->getDBkey()
] )
->caller( $fname )->fetchRow();
return $row && $row->lt_id ? (int)$row->lt_id : false;
}
);
}
);
if ( $res ) {
$this->addToClassCache( $res, $linkTarget );
}
return $res;
}
}