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<?php
/**
* Base code for update jobs that put some secondary data extracted
* from article content into the database.
*
* 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
*/
/**
* Abstract base class for update jobs that put some secondary data extracted
* from article content into the database.
*
* @note: subclasses should NOT start or commit transactions in their doUpdate() method,
* a transaction will automatically be wrapped around the update. Starting another
* one would break the outer transaction bracket. If need be, subclasses can override
* the beginTransaction() and commitTransaction() methods.
*/
abstract class SqlDataUpdate extends DataUpdate {
protected $mDb; //!< Database connection reference
protected $mOptions; //!< SELECT options to be used (array)
private $mHasTransaction; //!< bool whether a transaction is open on this object (internal use only!)
protected $mUseTransaction; //!< bool whether this update should be wrapped in a transaction
/**
* Constructor
*
* @param bool $withTransaction whether this update should be wrapped in a transaction (default: true).
* A transaction is only started if no transaction is already in progress,
* see beginTransaction() for details.
**/
public function __construct( $withTransaction = true ) {
global $wgAntiLockFlags;
parent::__construct();
if ( $wgAntiLockFlags & ALF_NO_LINK_LOCK ) {
$this->mOptions = array();
} else {
$this->mOptions = array( 'FOR UPDATE' );
}
// @todo get connection only when it's needed? make sure that doesn't break anything, especially transactions!
$this->mDb = wfGetDB( DB_MASTER );
$this->mWithTransaction = $withTransaction;
$this->mHasTransaction = false;
}
/**
* Begin a database transaction, if $withTransaction was given as true in the constructor for this SqlDataUpdate.
*
* Because nested transactions are not supported by the Database class, this implementation
* checks Database::trxLevel() and only opens a transaction if none is already active.
*/
public function beginTransaction() {
if ( !$this->mWithTransaction ) {
return;
}
// NOTE: nested transactions are not supported, only start a transaction if none is open
if ( $this->mDb->trxLevel() === 0 ) {
$this->mDb->begin( get_class( $this ) . '::beginTransaction' );
$this->mHasTransaction = true;
}
}
/**
* Commit the database transaction started via beginTransaction (if any).
*/
public function commitTransaction() {
if ( $this->mHasTransaction ) {
$this->mDb->commit( get_class( $this ) . '::commitTransaction' );
$this->mHasTransaction = false;
}
}
/**
* Abort the database transaction started via beginTransaction (if any).
*/
public function abortTransaction() {
if ( $this->mHasTransaction ) { //XXX: actually... maybe always?
$this->mDb->rollback( get_class( $this ) . '::abortTransaction' );
$this->mHasTransaction = false;
}
}
/**
* Invalidate the cache of a list of pages from a single namespace.
* This is intended for use by subclasses.
*
* @param $namespace Integer
* @param $dbkeys Array
*/
protected function invalidatePages( $namespace, array $dbkeys ) {
if ( $dbkeys === array() ) {
return;
}
/**
* Determine which pages need to be updated
* This is necessary to prevent the job queue from smashing the DB with
* large numbers of concurrent invalidations of the same page
*/
$now = $this->mDb->timestamp();
$ids = array();
$res = $this->mDb->select( 'page', array( 'page_id' ),
array(
'page_namespace' => $namespace,
'page_title' => $dbkeys,
'page_touched < ' . $this->mDb->addQuotes( $now )
), __METHOD__
);
foreach ( $res as $row ) {
$ids[] = $row->page_id;
}
if ( $ids === array() ) {
return;
}
/**
* Do the update
* We still need the page_touched condition, in case the row has changed since
* the non-locking select above.
*/
$this->mDb->update( 'page', array( 'page_touched' => $now ),
array(
'page_id' => $ids,
'page_touched < ' . $this->mDb->addQuotes( $now )
), __METHOD__
);
}
}
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