includes/historyblob/HistoryBlobStub.php
<?php
/**
* Efficient concatenated text storage.
*
* 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
*/
use MediaWiki\MediaWikiServices;
/**
* Pointer object for an item within a CGZ blob stored in the text table.
*
* WARNING: Objects of this class are serialized and permanently stored in the DB.
* Do not change the name or visibility of any property!
*
* Note: the property visibility was changed in 2020 from public to protected.
* This may cause problems in future.
*/
class HistoryBlobStub {
/**
* @var array One-step cache variable to hold base blobs; operations that
* pull multiple revisions may often pull multiple times from the same
* blob. By keeping the last-used one open, we avoid redundant
* unserialization and decompression overhead.
*/
protected static $blobCache = [];
/** @var int */
protected $mOldId;
/** @var string */
protected $mHash;
/** @var string */
protected $mRef;
/**
* @param string $hash The content hash of the text
* @param int $oldid The old_id for the CGZ object
*/
public function __construct( $hash = '', $oldid = 0 ) {
$this->mHash = $hash;
}
/**
* Sets the location (old_id) of the main object to which this object
* points
* @param int $id
*/
public function setLocation( $id ) {
$this->mOldId = $id;
}
/**
* Gets the location of the main object
* @return int
*/
public function getLocation() {
return $this->mOldId;
}
/**
* Sets the location (old_id) of the referring object
* @param string $id
*/
public function setReferrer( $id ) {
$this->mRef = $id;
}
/**
* Gets the location of the referring object
* @return string
*/
public function getReferrer() {
return $this->mRef;
}
/**
* @return string|false
*/
public function getText() {
if ( isset( self::$blobCache[$this->mOldId] ) ) {
$obj = self::$blobCache[$this->mOldId];
} else {
$dbr = MediaWikiServices::getInstance()->getConnectionProvider()->getReplicaDatabase();
$row = $dbr->newSelectQueryBuilder()
->select( [ 'old_flags', 'old_text' ] )
->from( 'text' )
->where( [ 'old_id' => $this->mOldId ] )
->caller( __METHOD__ )->fetchRow();
if ( !$row ) {
return false;
}
$flags = explode( ',', $row->old_flags );
if ( in_array( 'external', $flags ) ) {
$url = $row->old_text;
$parts = explode( '://', $url, 2 );
if ( !isset( $parts[1] ) || $parts[1] == '' ) {
return false;
}
$row->old_text = MediaWikiServices::getInstance()
->getExternalStoreAccess()
->fetchFromURL( $url );
}
if ( !in_array( 'object', $flags ) ) {
return false;
}
if ( in_array( 'gzip', $flags ) ) {
// This shouldn't happen, but a bug in the compress script
// may at times gzip-compress a HistoryBlob object row.
$obj = HistoryBlobUtils::unserialize( gzinflate( $row->old_text ), true );
} else {
$obj = HistoryBlobUtils::unserialize( $row->old_text, true );
}
// Save this item for reference; if pulling many
// items in a row we'll likely use it again.
self::$blobCache = [ $this->mOldId => $obj ];
}
if ( method_exists( $obj, 'getItem' ) ) {
return $obj->getItem( $this->mHash );
}
return false;
}
/**
* Get the content hash
*
* @return string
*/
public function getHash() {
return $this->mHash;
}
}
// Blobs generated by MediaWiki < 1.5 on PHP 4 were serialized with the
// class name coerced to lowercase. We can improve efficiency by adding
// autoload entries for the lowercase variants of these classes (T166759).
// The code below is never executed, but it is picked up by the AutoloadGenerator
// parser, which scans for class_alias() calls.
/*
class_alias( HistoryBlobStub::class, 'historyblobstub' );
*/