gistfile1.php

/**
 * Maintenance script that populates the event_page_id column of echo_event
 *
 * @ingroup Maintenance
 */
class updateEchoSchemaForSuppression extends Maintenance {

	public function __construct() {
		parent::__construct();
		$this->mBatchSize = 500;
	}

	protected function createReader() {
		$reader = new EchoBatchRowIterator(
			MWEchoDbFactory::getDB( DB_SLAVE ),
			'echo_event',
			'event_id',
			$this->mBatchSize
		);
		$reader->addCondition( "event_page_title IS NOT NULL" );
		$reader->addCondition( "event_page_id IS NULL" );

		return $reader;
	}

	protected function createWriter() {
		return new EchoBatchRowWriter(
			MWEchoDbFactory::getDB( DB_MASTER ),
			$wgEchoCluster,
			'echo_event',
			'event_id'
		);
	}

	protected function createUpdateGenerator() {
		return new EchoSuppressionRowUpdateGenerator;
	}

	public function execute() {
		$update = new EchoSchemaUpdate(
			$this->createReader(),
			$this->createWriter(),
			$this->createUpdateGenerator()
		);

		$self = $this;
		$update->setOutput( function( $text ) use( $self ) {
			$self->__outputInternal( $text );
		} );

		$update->execute();
	}

	/**
	 * Internal use only, exists because 5.3 Closures have no access to protected methods
	 */
	public function __outputInternal( $text ) {
		$this->output( $text );
	}
}


class EchoSchemaUpdate {
	public function __construct( EchoBatchRowIterator $reader, EchoBatchRowWriter $writer, EchoRowUpdateGenerator $generator ) {
		$this->reader = $reader;
		$this->writer = $writer;
		$this->generator = $generator;
		$this->output = function() {}; // noop
	}

	protected function output( $text ) {
		$output = $this->output;
		$output( $text );
	}

	public function setOutput( Closure $output ) {
		$this->output = $output;
	}

	public function execute() {
		foreach ( $this->reader as $rows ) {
			$updates = array();
			foreach ( $rows as $row ) {
				list( $id, $update ) = $this->generator->generateUpdateForRow( $row );
				if ( $update ) {
					$updates[$id] = $update;
				}
			}

			if ( $updates ) {
				$this->output( "Processing " . count($update) . " rows\n" );
				$this->writer->write( $updates );
			}
		}

		$this->output( "Completed\n" );
	}
}

class EchoBatchRowWriter {
	public function __construct( DatabaseType $db, $clusterName, $table, $idField ) {
		$this->db = $db;
		$this->clusterName = $clusterName;
		$this->table = $table;
		$this->idField = $idField;
	}

	public function write( array $updates ) {
		$this->db->begin();

		foreach ( $updates as $id => $update ) {
			$this->db->update(
				$this->table
				$update,
				array( $this->idField => $id ),
				__METHOD__
			);
		}

		$this->db->commit();
		wfWaitForSlaves( false, false, $this->clusterName );
	}
}

class EchoBatchRowIterator implements Iterator {

	protected $db;
	protected $table;
	protected $idField;
	protected $batchSize;

	protected $conditions = array();
	protected $maxId = 0;

	public function __construct( DatabaseType $db, $table, $idField, $batchSize ) {
		$this->db = $db;
		$this->table = $table;
		$this->idField = $idField;
		$this->batchSize = $batchSize;
	}

	public function addCondition( $condition ) {
		$this->conditions = $condition;
	}

	public function current() {
		return $this->current;
	}

	public function key() {
		return $this->maxId;
	}

	public function rewind() {
		$this->maxId = 0;
		$this->next();
	}

	public function valid() {
		return count($this->current) > 0;
	}

	public function next() {
		$conditions = $this->conditions;
		$conditions[] = "{$this->idField} > {$this->maxId}";

		$res = $this->db->select(
			$this->table,
			array( '*' ),
			$conditions,
			__METHOD__,
			array(
				'LIMIT' => $this->batchSize,
				"ORDER BY {$this->idField} ASC",
			)
		);

		$this->current = iterator_to_array( $res );

		// If $this->current is empty then self::valid() will return false
		// so no need to handle edge case
		if ( $this->current) {
			$row = end( $res );
			$this->maxId = $row->{$this->idField};
		}
	}
}

interface EchoRowUpdateGenerator {
	function generateRowUpdate( $row );
}

class EchoSuppressionRowUpdateGenerator implements EchoRowUpdateGenerator
{
	/**
	 * Given a database row, generate an update array suitible for schema update
	 *
	 * @param $row object Database row from echo_event table
	 * @return [int, array] The row id to update and an associative array of column upates
	 */
	public function generateRowUpdate( $row ) {
		$update = $this->updatePageIdFromTitle( $row );
		if ( $row->event_extra !== null && $row->event_type === 'page-linked' ) {
			$update = $this->updatePageLinkedExtraData( $row, $update );
		}

		return array( $row->event_id, $update );
	}

	protected function updatePageIdFromTitle( $row ) {
		$update = array();
		$title = Title::newFromText( $row->event_page_title, $row->event_page_namespace );
		if ( $title !== null ) {
			$pageId = $title->getArticleId();
			if ( $pageId ) {
				// If the title has a proper id from the database, store it
				$update['event_page_id'] = $pageId;
			} else {
				// For titles that do not refer to a WikiPage stored in the database
				// move the title/namespace into event_extra
				$extra = $row->event_extra ? unserialize( $row->event_extra ) : array();
				$extra['page_title'] = $row->event_page_title;
				$extra['page_namespace'] = $row->event_page_namespace;

				$update['event_extra'] = serialize( $extra );
			}
		}

		return $update;
	}

	protected function updatePageLinkedExtraData( $row, array $update ) {
		$extra = array();
		if ( isset( $update['extra'] ) ) {
			$extra = unserialize( $update['extra'] );
		} elseif ( $row->event_extra ) {
			$extra = unserialize( $row->event_extra );
		}

		if ( isset( $extra['link-from-title'], $extra['link-from-namespace'] ) ) {
			$title = Title::newFromText( $extra['link-from-title'], $extra['link-from-namespace'] );
			unset( $extra['link-from-title'], $extra['link-from-namespace'] );
			// Link from page is always from a content page, if null or no article id it was
			// somehow invalid
			if ( $title !== null && $title->getArticleId() ) {
				$extra['link-from-page-id'] = $title->getArticleId();
			}

			$update['event_extra'] = serialize( $extra );
		}

		return $update;
	}
}