Page MenuHomeWickedGov Phorge
Files F5992495

ChangeTagsCondition.php
No OneTemporary
Actions

Size
4 KB
Referenced Files
None
Subscribers
None

ChangeTagsCondition.php
View Options

<?php
namespace MediaWiki\RecentChanges\ChangesListQuery;
use MediaWiki\ChangeTags\ChangeTagsStore;
use Psr\Log\LoggerInterface;
use stdClass;
use Wikimedia\Rdbms\IReadableDatabase;
class ChangeTagsCondition extends ChangesListConditionBase {
private float|int $denseRcSizeThreshold = 10000;
private ?int $limit = null;
private bool $densityThresholdReached = true;
public function __construct(
private ChangeTagsStore $changeTagsStore,
private TableStatsProvider $rcStats,
private LoggerInterface $logger,
private bool $miserMode,
) {
}
/**
* Set the query limit to be used for density heuristics
*
* @param int $limit
*/
public function setLimit( int $limit ) {
$this->limit = $limit;
}
/**
* @param bool $reached Whether the query density is high enough to apply
* heuristics for a straight join
*/
public function setDensityThresholdReached( bool $reached ) {
$this->densityThresholdReached = $reached;
}
/**
* Set the minimum size of the recentchanges table at which change tag
* queries will be conditionally modified based on estimated density.
*
* @param float|int $threshold
*/
public function setDenseRcSizeThreshold( $threshold ) {
$this->denseRcSizeThreshold = $threshold;
}
/** @inheritDoc */
public function validateValue( $value ) {
if ( !is_scalar( $value ) ) {
throw new \InvalidArgumentException( "Change tag must be string-like" );
}
return (string)$value;
}
/** @inheritDoc */
public function evaluate( stdClass $row, $value ): bool {
if ( !$row->ts_tags ) {
return false;
}
return in_array( $value, explode( ',', $row->ts_tags ), true );
}
/** @inheritDoc */
protected function prepareCapture( IReadableDatabase $dbr, QueryBackend $query ) {
$query->fields( [
'ts_tags' => $this->changeTagsStore->makeTagSummarySubquery( 'recentchanges' )
] );
}
/** @inheritDoc */
protected function prepareConds( IReadableDatabase $dbr, QueryBackend $query ) {
[ $required, $excluded ] = $this->getUniqueValues();
if ( $required === [] ) {
$query->forceEmptySet();
} elseif ( $required ) {
$ids = array_values( $this->changeTagsStore->getTagIdsFromNames( $required ) );
if ( !$ids ) {
// All tags were invalid, return nothing
$query->forceEmptySet();
return;
}
$join = $query->joinForConds( 'change_tag' );
// Workaround for T298225: MySQL's lack of awareness of LIMIT when
// choosing the join order.
if ( $this->isDenseTagFilter( $dbr, $ids ) ) {
$join->straight();
} else {
$join->reorderable();
}
$query->where( $dbr->expr( 'changetagdisplay.ct_tag_id', '=', $ids ) );
if ( count( $ids ) > 1 ) {
$query->distinct();
}
} elseif ( $excluded ) {
$ids = array_values( $this->changeTagsStore->getTagIdsFromNames( $excluded ) );
if ( !$ids ) {
// No valid tags were excluded
return;
}
$query->joinForConds( 'change_tag' )->left()
->on( $dbr->expr( 'changetagdisplay.ct_tag_id', '=', $ids ) );
$query->where( $dbr->expr( 'changetagdisplay.ct_tag_id', '=', null ) );
}
}
/**
* Determine whether a tag filter matches a high proportion of the rows in
* recentchanges. If so, it is more efficient to scan recentchanges,
* filtering out non-matching rows, rather than scanning change_tag and
* then filesorting on rc_timestamp. MySQL is especially bad at making this
* judgement (T298225).
*
* @param IReadableDatabase $dbr
* @param int[] $tagIds
* @return bool
*/
protected function isDenseTagFilter( IReadableDatabase $dbr, array $tagIds ) {
if ( !$tagIds
// Only on RecentChanges or similar
|| !$this->densityThresholdReached
// Need a limit
|| !$this->limit
// This is a MySQL-specific hack
|| $dbr->getType() !== 'mysql'
// Unnecessary for small wikis
|| !$this->miserMode
) {
return false;
}
$rcSize = $this->rcStats->getIdDelta();
if ( $rcSize < $this->denseRcSizeThreshold ) {
// RC is too small to worry about
return false;
}
$tagCount = $dbr->newSelectQueryBuilder()
->table( 'change_tag' )
->where( [
$dbr->expr( 'ct_rc_id', '>=', $this->rcStats->getMinId() ),
'ct_tag_id' => $tagIds
] )
->caller( __METHOD__ )
->estimateRowCount();
// If we scan recentchanges first, the number of rows examined will be
// approximately the limit divided by the proportion of tagged rows,
// i.e. $limit / ( $tagCount / $rcSize ). If that's less than $tagCount,
// use a straight join. The inequality below is rearranged for
// simplicity and to avoid division by zero.
$isDense = $this->limit * $rcSize < $tagCount * $tagCount;
$this->logger->debug( __METHOD__ .
": rcSize = $rcSize, tagCount = $tagCount, limit = {$this->limit} => " .
( $isDense ? 'dense' : 'sparse' ) );
return $isDense;
}
}

File Metadata

Mime Type
text/x-php
Expires
Oct 4 2026, 02:19 (5 w, 1 d ago)
Storage Engine
local-disk
Storage Format
Raw Data
Storage Handle
7b/b3/801068386938981fa8fdb9635129
Default Alt Text
ChangeTagsCondition.php (4 KB)

Event Timeline