Current File : /www/varak.net/wiki.varak.net/includes/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
*/
/**
* 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.
*
* @todo Move some stuff from CategoryPage.php to here, and use that.
*/
class Category {
/** Name of the category, normalized to DB-key form */
private $mName = null;
private $mID = null;
/**
* Category page title
* @var Title
*/
private $mTitle = null;
/** Counts of membership (cat_pages, cat_subcats, cat_files) */
private $mPages = null, $mSubcats = null, $mFiles = null;
const LOAD_ONLY = 0;
const LAZY_INIT_ROW = 1;
private function __construct() {
}
/**
* Set up all member variables using a database query.
* @param int $mode One of (Category::LOAD_ONLY, Category::LAZY_INIT_ROW)
* @throws MWException
* @return bool True on success, false on failure.
*/
protected function initialize( $mode = self::LOAD_ONLY ) {
if ( $this->mName === null && $this->mID === null ) {
throw new MWException( __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;
}
$dbr = wfGetDB( DB_REPLICA );
$row = $dbr->selectRow(
'category',
[ 'cat_id', 'cat_title', 'cat_pages', 'cat_subcats', 'cat_files' ],
$where,
__METHOD__
);
if ( !$row ) {
# Okay, there were no contents. Nothing to initialize.
if ( $this->mTitle ) {
# If there is a title object but no record in the category table,
# treat this as an empty category.
$this->mID = false;
$this->mName = $this->mTitle->getDBkey();
$this->mPages = 0;
$this->mSubcats = 0;
$this->mFiles = 0;
# If the title exists, call refreshCounts to add a row for it.
if ( $mode === self::LAZY_INIT_ROW && $this->mTitle->exists() ) {
DeferredUpdates::addCallableUpdate( [ $this, 'refreshCounts' ] );
}
return true;
} else {
return false; # Fail
}
}
$this->mID = $row->cat_id;
$this->mName = $row->cat_title;
$this->mPages = $row->cat_pages;
$this->mSubcats = $row->cat_subcats;
$this->mFiles = $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->mTitle = $title;
$cat->mName = $title->getDBkey();
return $cat;
}
/**
* Factory function.
*
* @param Title $title Title for the category page
* @return Category|bool On a totally invalid name
*/
public static function newFromTitle( $title ) {
$cat = new self();
$cat->mTitle = $title;
$cat->mName = $title->getDBkey();
return $cat;
}
/**
* Factory function.
*
* @param int $id A category id
* @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 object $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 title object was given. If the fields are null and no
* title was given, this method fails and returns false.
* @param Title|null $title Optional title object for the category represented by
* the given row. May be provided if it is already known, to avoid having
* to re-create a title object later.
* @return Category|false
*/
public static function newFromRow( $row, $title = null ) {
$cat = new self();
$cat->mTitle = $title;
# 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 ( $title === 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 title object, fetch the category name from there
$cat->mName = $title->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 = $row->cat_subcats;
$cat->mPages = $row->cat_pages;
$cat->mFiles = $row->cat_files;
}
return $cat;
}
/**
* @return mixed DB key name, or false on failure
*/
public function getName() {
return $this->getX( 'mName' );
}
/**
* @return mixed Category ID, or false on failure
*/
public function getID() {
return $this->getX( 'mID' );
}
/**
* @return mixed Total number of member pages, or false on failure
*/
public function getPageCount() {
return $this->getX( 'mPages' );
}
/**
* @return mixed Number of subcategories, or false on failure
*/
public function getSubcatCount() {
return $this->getX( 'mSubcats' );
}
/**
* @return mixed Number of member files, or false on failure
*/
public function getFileCount() {
return $this->getX( 'mFiles' );
}
/**
* @return Title|bool Title for this category, or false on failure.
*/
public function getTitle() {
if ( $this->mTitle ) {
return $this->mTitle;
}
if ( !$this->initialize( self::LAZY_INIT_ROW ) ) {
return false;
}
$this->mTitle = Title::makeTitleSafe( NS_CATEGORY, $this->mName );
return $this->mTitle;
}
/**
* Fetch a TitleArray of up to $limit category members, beginning after the
* category sort key $offset.
* @param int|bool $limit
* @param string $offset
* @return TitleArray TitleArray object for category members.
*/
public function getMembers( $limit = false, $offset = '' ) {
$dbr = wfGetDB( DB_REPLICA );
$conds = [ 'cl_to' => $this->getName(), 'cl_from = page_id' ];
$options = [ 'ORDER BY' => 'cl_sortkey' ];
if ( $limit ) {
$options['LIMIT'] = $limit;
}
if ( $offset !== '' ) {
$conds[] = 'cl_sortkey > ' . $dbr->addQuotes( $offset );
}
$result = TitleArray::newFromResult(
$dbr->select(
[ 'page', 'categorylinks' ],
[ 'page_id', 'page_namespace', 'page_title', 'page_len',
'page_is_redirect', 'page_latest' ],
$conds,
__METHOD__,
$options
)
);
return $result;
}
/**
* Generic accessor
* @param string $key
* @return bool
*/
private function getX( $key ) {
if ( !$this->initialize( self::LAZY_INIT_ROW ) ) {
return false;
}
return $this->{$key};
}
/**
* Refresh the counts for this category.
*
* @return bool True on success, false on failure
*/
public function refreshCounts() {
if ( wfReadOnly() ) {
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 = wfGetDB( DB_MASTER );
# 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 locking `categorylinks` rows to try
// to avoid deadlocks with LinksDeletionUpdate (T195397)
$dbw->lockForUpdate( 'category', [ 'cat_title' => $this->mName ], __METHOD__ );
// Lock all the `categorylinks` records and gaps for this category;
// this is a separate query due to postgres/oracle limitations
$dbw->selectRowCount(
[ 'categorylinks', 'page' ],
'*',
[ 'cl_to' => $this->mName, 'page_id = cl_from' ],
__METHOD__,
[ 'LOCK IN SHARE MODE' ]
);
// 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 = $dbw->selectRow(
[ 'categorylinks', 'page' ],
[
'pages' => 'COUNT(*)',
'subcats' => "COUNT($catCond)",
'files' => "COUNT($fileCond)"
],
[ 'cl_to' => $this->mName, 'page_id = cl_from' ],
__METHOD__
);
$shouldExist = $result->pages > 0 || $this->getTitle()->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->update(
'category',
[
'cat_pages' => $result->pages,
'cat_subcats' => $result->subcats,
'cat_files' => $result->files
],
[ 'cat_title' => $this->mName ],
__METHOD__
);
} else {
# The category is empty and has no description page, delete it
$dbw->delete(
'category',
[ 'cat_title' => $this->mName ],
__METHOD__
);
$this->mID = false;
}
} elseif ( $shouldExist ) {
# The category row doesn't exist but should, so create it. Use
# upsert in case of races.
$dbw->upsert(
'category',
[
'cat_title' => $this->mName,
'cat_pages' => $result->pages,
'cat_subcats' => $result->subcats,
'cat_files' => $result->files
],
[ 'cat_title' ],
[
'cat_pages' => $result->pages,
'cat_subcats' => $result->subcats,
'cat_files' => $result->files
],
__METHOD__
);
// @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 = $result->pages;
$this->mSubcats = $result->subcats;
$this->mFiles = $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() {
$dbw = wfGetDB( DB_MASTER );
$hasLink = $dbw->selectField(
'categorylinks',
'1',
[ 'cl_to' => $this->getName() ],
__METHOD__
);
if ( !$hasLink ) {
$this->refreshCounts(); // delete any category table entry
return true;
}
$hasBadRow = $dbw->selectField(
'category',
'1',
[ 'cat_title' => $this->getName(), 'cat_pages <= 0' ],
__METHOD__
);
if ( $hasBadRow ) {
$this->refreshCounts(); // clean up this row
return true;
}
return false;
}
}
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