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Diffstat (limited to 'includes/SqlDataUpdate.php')
| -rw-r--r-- | includes/SqlDataUpdate.php | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/includes/SqlDataUpdate.php b/includes/SqlDataUpdate.php new file mode 100644 index 00000000..52c9be00 --- /dev/null +++ b/includes/SqlDataUpdate.php @@ -0,0 +1,150 @@ +<?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 ) { + $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 ( !count( $dbkeys ) ) { + 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 ( !count( $ids ) ) { + 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__ + ); + } + +} |