includes/Category/Category.php
<?php
/**
* Representation for a category.
*
* 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
* @author Simetrical
*/
namespace MediaWiki\Category;
use MediaWiki\Deferred\DeferredUpdates;
use MediaWiki\MediaWikiServices;
use MediaWiki\Page\PageIdentity;
use MediaWiki\Title\Title;
use MediaWiki\Title\TitleArrayFromResult;
use MediaWiki\Title\TitleFactory;
use RuntimeException;
use stdClass;
use Wikimedia\Rdbms\IConnectionProvider;
use Wikimedia\Rdbms\ReadOnlyMode;
/**
* Category objects are immutable, strictly speaking. If you call methods that change the database,
* like to refresh link counts, the objects will be appropriately reinitialized.
* Member variables are lazy-initialized.
*/
class Category {
/** Name of the category, normalized to DB-key form */
private $mName = null;
private $mID = null;
/**
* Category page title
* @var PageIdentity
*/
private $mPage = null;
/** Counts of membership (cat_pages, cat_subcats, cat_files) */
/** @var int */
private $mPages = 0;
/** @var int */
private $mSubcats = 0;
/** @var int */
private $mFiles = 0;
protected const LOAD_ONLY = 0;
protected const LAZY_INIT_ROW = 1;
public const ROW_COUNT_SMALL = 100;
public const COUNT_ALL_MEMBERS = 0;
public const COUNT_CONTENT_PAGES = 1;
/** @var IConnectionProvider */
private $dbProvider;
/** @var ReadOnlyMode */
private $readOnlyMode;
/** @var TitleFactory */
private $titleFactory;
private function __construct() {
$services = MediaWikiServices::getInstance();
$this->dbProvider = $services->getConnectionProvider();
$this->readOnlyMode = $services->getReadOnlyMode();
$this->titleFactory = $services->getTitleFactory();
}
/**
* Set up all member variables using a database query.
* @param int $mode One of (Category::LOAD_ONLY, Category::LAZY_INIT_ROW)
* @return bool True on success, false on failure.
*/
protected function initialize( $mode = self::LOAD_ONLY ) {
if ( $this->mName === null && $this->mID === null ) {
throw new RuntimeException( __METHOD__ . ' has both names and IDs null' );
} elseif ( $this->mID === null ) {
$where = [ 'cat_title' => $this->mName ];
} elseif ( $this->mName === null ) {
$where = [ 'cat_id' => $this->mID ];
} else {
# Already initialized
return true;
}
$row = $this->dbProvider->getReplicaDatabase()->newSelectQueryBuilder()
->select( [ 'cat_id', 'cat_title', 'cat_pages', 'cat_subcats', 'cat_files' ] )
->from( 'category' )
->where( $where )
->caller( __METHOD__ )->fetchRow();
if ( !$row ) {
# Okay, there were no contents. Nothing to initialize.
if ( $this->mPage ) {
# If there is a page object but no record in the category table,
# treat this as an empty category.
$this->mID = false;
$this->mName = $this->mPage->getDBkey();
$this->mPages = 0;
$this->mSubcats = 0;
$this->mFiles = 0;
# If the page exists, call refreshCounts to add a row for it.
if ( $mode === self::LAZY_INIT_ROW && $this->mPage->exists() ) {
DeferredUpdates::addCallableUpdate( [ $this, 'refreshCounts' ] );
}
return true;
} else {
return false; # Fail
}
}
$this->mID = $row->cat_id;
$this->mName = $row->cat_title;
$this->mPages = (int)$row->cat_pages;
$this->mSubcats = (int)$row->cat_subcats;
$this->mFiles = (int)$row->cat_files;
# (T15683) If the count is negative, then 1) it's obviously wrong
# and should not be kept, and 2) we *probably* don't have to scan many
# rows to obtain the correct figure, so let's risk a one-time recount.
if ( $this->mPages < 0 || $this->mSubcats < 0 || $this->mFiles < 0 ) {
$this->mPages = max( $this->mPages, 0 );
$this->mSubcats = max( $this->mSubcats, 0 );
$this->mFiles = max( $this->mFiles, 0 );
if ( $mode === self::LAZY_INIT_ROW ) {
DeferredUpdates::addCallableUpdate( [ $this, 'refreshCounts' ] );
}
}
return true;
}
/**
* Factory function.
*
* @param string $name A category name (no "Category:" prefix). It need
* not be normalized, with spaces replaced by underscores.
* @return Category|bool Category, or false on a totally invalid name
*/
public static function newFromName( $name ) {
$cat = new self();
$title = Title::makeTitleSafe( NS_CATEGORY, $name );
if ( !is_object( $title ) ) {
return false;
}
$cat->mPage = $title;
$cat->mName = $title->getDBkey();
return $cat;
}
/**
* Factory function.
*
* @param PageIdentity $page Category page. Warning, no validation is performed!
* @return Category
*/
public static function newFromTitle( PageIdentity $page ): self {
$cat = new self();
$cat->mPage = $page;
$cat->mName = $page->getDBkey();
return $cat;
}
/**
* Factory function.
*
* @param int $id A category id. Warning, no validation is performed!
* @return Category
*/
public static function newFromID( $id ) {
$cat = new self();
$cat->mID = intval( $id );
return $cat;
}
/**
* Factory function, for constructing a Category object from a result set
*
* @param stdClass $row Result set row, must contain the cat_xxx fields. If the fields are
* null, the resulting Category object will represent an empty category if a page object was
* given. If the fields are null and no PageIdentity was given, this method fails and returns
* false.
* @param PageIdentity|null $page This must be provided if there is no cat_title field in $row.
* @return Category|false
*/
public static function newFromRow( stdClass $row, ?PageIdentity $page = null ) {
$cat = new self();
$cat->mPage = $page;
# NOTE: the row often results from a LEFT JOIN on categorylinks. This may result in
# all the cat_xxx fields being null, if the category page exists, but nothing
# was ever added to the category. This case should be treated link an empty
# category, if possible.
if ( $row->cat_title === null ) {
if ( $page === null ) {
# the name is probably somewhere in the row, for example as page_title,
# but we can't know that here...
return false;
} else {
# if we have a PageIdentity object, fetch the category name from there
$cat->mName = $page->getDBkey();
}
$cat->mID = false;
$cat->mSubcats = 0;
$cat->mPages = 0;
$cat->mFiles = 0;
} else {
$cat->mName = $row->cat_title;
$cat->mID = $row->cat_id;
$cat->mSubcats = (int)$row->cat_subcats;
$cat->mPages = (int)$row->cat_pages;
$cat->mFiles = (int)$row->cat_files;
}
return $cat;
}
/**
* @return string|false DB key name, or false on failure
*/
public function getName() {
return $this->getX( 'mName' );
}
/**
* @return string|false Category ID, or false on failure
*/
public function getID() {
return $this->getX( 'mID' );
}
/**
* @return int Total number of members count (sum of subcats, files and pages)
*/
public function getMemberCount(): int {
$this->initialize( self::LAZY_INIT_ROW );
return $this->mPages;
}
/**
* @param int $type One of self::COUNT_ALL_MEMBERS and self::COUNT_CONTENT_PAGES
* @return int Total number of member count or content page count
*/
public function getPageCount( $type = self::COUNT_ALL_MEMBERS ): int {
$allCount = $this->getMemberCount();
if ( $type === self::COUNT_CONTENT_PAGES ) {
return $allCount - ( $this->getSubcatCount() + $this->getFileCount() );
}
return $allCount;
}
/**
* @return int Number of subcategories
*/
public function getSubcatCount(): int {
return $this->getX( 'mSubcats' );
}
/**
* @return int Number of member files
*/
public function getFileCount(): int {
return $this->getX( 'mFiles' );
}
/**
* @since 1.37
* @return ?PageIdentity the page associated with this category, or null on failure. NOTE: This
* returns null on failure, unlike getTitle() which returns false.
*/
public function getPage(): ?PageIdentity {
if ( $this->mPage ) {
return $this->mPage;
}
if ( !$this->initialize( self::LAZY_INIT_ROW ) ) {
return null;
}
$this->mPage = Title::makeTitleSafe( NS_CATEGORY, $this->mName );
return $this->mPage;
}
/**
* @deprecated since 1.37, use getPage() instead.
* @return Title|bool Title for this category, or false on failure.
*/
public function getTitle() {
return Title::castFromPageIdentity( $this->getPage() ) ?? false;
}
/**
* Fetch a TitleArray of up to $limit category members, beginning after the
* category sort key $offset.
* @param int|false $limit
* @param string $offset
* @return TitleArrayFromResult Title objects for category members.
*/
public function getMembers( $limit = false, $offset = '' ) {
$dbr = $this->dbProvider->getReplicaDatabase();
$queryBuilder = $dbr->newSelectQueryBuilder();
$queryBuilder->select( [ 'page_id', 'page_namespace', 'page_title', 'page_len',
'page_is_redirect', 'page_latest' ] )
->from( 'categorylinks' )
->join( 'page', null, [ 'cl_from = page_id' ] )
->where( [ 'cl_to' => $this->getName() ] )
->orderBy( 'cl_sortkey' );
if ( $limit ) {
$queryBuilder->limit( $limit );
}
if ( $offset !== '' ) {
$queryBuilder->andWhere( $dbr->expr( 'cl_sortkey', '>', $offset ) );
}
return $this->titleFactory->newTitleArrayFromResult(
$queryBuilder->caller( __METHOD__ )->fetchResultSet()
);
}
/**
* Generic accessor
* @param string $key
* @return mixed
*/
private function getX( $key ) {
$this->initialize( self::LAZY_INIT_ROW );
return $this->{$key} ?? false;
}
/**
* Refresh the counts for this category.
*
* @return bool True on success, false on failure
*/
public function refreshCounts() {
if ( $this->readOnlyMode->isReadOnly() ) {
return false;
}
# If we have just a category name, find out whether there is an
# existing row. Or if we have just an ID, get the name, because
# that's what categorylinks uses.
if ( !$this->initialize( self::LOAD_ONLY ) ) {
return false;
}
$dbw = $this->dbProvider->getPrimaryDatabase();
# Avoid excess contention on the same category (T162121)
$name = __METHOD__ . ':' . md5( $this->mName );
$scopedLock = $dbw->getScopedLockAndFlush( $name, __METHOD__, 0 );
if ( !$scopedLock ) {
return false;
}
$dbw->startAtomic( __METHOD__ );
// Lock the `category` row before potentially locking `categorylinks` rows to try
// to avoid deadlocks with LinksDeletionUpdate (T195397)
$dbw->newSelectQueryBuilder()
->from( 'category' )
->where( [ 'cat_title' => $this->mName ] )
->caller( __METHOD__ )
->forUpdate()
->acquireRowLocks();
$rowCount = $dbw->newSelectQueryBuilder()
->select( '*' )
->from( 'categorylinks' )
->join( 'page', null, 'page_id = cl_from' )
->where( [ 'cl_to' => $this->mName ] )
->limit( 110 )
->caller( __METHOD__ )->fetchRowCount();
// Only lock if there are below 100 rows (T352628)
if ( $rowCount < 100 ) {
// Lock all the `categorylinks` records and gaps for this category;
// this is a separate query due to postgres limitations
$dbw->newSelectQueryBuilder()
->select( '*' )
->from( 'categorylinks' )
->join( 'page', null, 'page_id = cl_from' )
->where( [ 'cl_to' => $this->mName ] )
->lockInShareMode()
->caller( __METHOD__ )
->acquireRowLocks();
}
// Get the aggregate `categorylinks` row counts for this category
$catCond = $dbw->conditional( [ 'page_namespace' => NS_CATEGORY ], '1', 'NULL' );
$fileCond = $dbw->conditional( [ 'page_namespace' => NS_FILE ], '1', 'NULL' );
$result = $dbw->newSelectQueryBuilder()
->select( [
'pages' => 'COUNT(*)',
'subcats' => "COUNT($catCond)",
'files' => "COUNT($fileCond)"
] )
->from( 'categorylinks' )
->join( 'page', null, 'page_id = cl_from' )
->where( [ 'cl_to' => $this->mName ] )
->caller( __METHOD__ )->fetchRow();
$shouldExist = $result->pages > 0 || $this->getPage()->exists();
if ( $this->mID ) {
if ( $shouldExist ) {
# The category row already exists, so do a plain UPDATE instead
# of INSERT...ON DUPLICATE KEY UPDATE to avoid creating a gap
# in the cat_id sequence. The row may or may not be "affected".
$dbw->newUpdateQueryBuilder()
->update( 'category' )
->set( [
'cat_pages' => $result->pages,
'cat_subcats' => $result->subcats,
'cat_files' => $result->files
] )
->where( [ 'cat_title' => $this->mName ] )
->caller( __METHOD__ )->execute();
} else {
# The category is empty and has no description page, delete it
$dbw->newDeleteQueryBuilder()
->deleteFrom( 'category' )
->where( [ 'cat_title' => $this->mName ] )
->caller( __METHOD__ )->execute();
$this->mID = false;
}
} elseif ( $shouldExist ) {
# The category row doesn't exist but should, so create it. Use
# upsert in case of races.
$dbw->newInsertQueryBuilder()
->insertInto( 'category' )
->row( [
'cat_title' => $this->mName,
'cat_pages' => $result->pages,
'cat_subcats' => $result->subcats,
'cat_files' => $result->files
] )
->onDuplicateKeyUpdate()
->uniqueIndexFields( [ 'cat_title' ] )
->set( [
'cat_pages' => $result->pages,
'cat_subcats' => $result->subcats,
'cat_files' => $result->files
] )
->caller( __METHOD__ )->execute();
// @todo: Should we update $this->mID here? Or not since Category
// objects tend to be short lived enough to not matter?
}
$dbw->endAtomic( __METHOD__ );
# Now we should update our local counts.
$this->mPages = (int)$result->pages;
$this->mSubcats = (int)$result->subcats;
$this->mFiles = (int)$result->files;
return true;
}
/**
* Call refreshCounts() if there are no entries in the categorylinks table
* or if the category table has a row that states that there are no entries
*
* Due to lock errors or other failures, the precomputed counts can get out of sync,
* making it hard to know when to delete the category row without checking the
* categorylinks table.
*
* @return bool Whether links were refreshed
* @since 1.32
*/
public function refreshCountsIfEmpty() {
return $this->refreshCountsIfSmall( 0 );
}
/**
* Call refreshCounts() if there are few entries in the categorylinks table
*
* Due to lock errors or other failures, the precomputed counts can get out of sync,
* making it hard to know when to delete the category row without checking the
* categorylinks table.
*
* This method will do a non-locking select first to reduce contention.
*
* @param int $maxSize Only refresh if there are this or less many backlinks
* @return bool Whether links were refreshed
* @since 1.34
*/
public function refreshCountsIfSmall( $maxSize = self::ROW_COUNT_SMALL ) {
$dbw = $this->dbProvider->getPrimaryDatabase();
$dbw->startAtomic( __METHOD__ );
$typeOccurances = $dbw->newSelectQueryBuilder()
->select( 'cl_type' )
->from( 'categorylinks' )
->where( [ 'cl_to' => $this->getName() ] )
->limit( $maxSize + 1 )
->caller( __METHOD__ )->fetchFieldValues();
if ( !$typeOccurances ) {
$doRefresh = true; // delete any category table entry
} elseif ( count( $typeOccurances ) <= $maxSize ) {
$countByType = array_count_values( $typeOccurances );
$doRefresh = !$dbw->newSelectQueryBuilder()
->select( '1' )
->from( 'category' )
->where( [
'cat_title' => $this->getName(),
'cat_pages' => $countByType['page'] ?? 0,
'cat_subcats' => $countByType['subcat'] ?? 0,
'cat_files' => $countByType['file'] ?? 0
] )
->caller( __METHOD__ )->fetchField();
} else {
$doRefresh = false; // category is too big
}
$dbw->endAtomic( __METHOD__ );
if ( $doRefresh ) {
$this->refreshCounts(); // update the row
return true;
}
return false;
}
}
/** @deprecated class alias since 1.40 */
class_alias( Category::class, 'Category' );