1 files changed, 118 insertions, 0 deletions
diff --git a/www/wiki/includes/jobqueue/jobs/ClearUserWatchlistJob.php b/www/wiki/includes/jobqueue/jobs/ClearUserWatchlistJob.php
new file mode 100644
index 00000000..77adfa1a
--- /dev/null
+++ b/www/wiki/includes/jobqueue/jobs/ClearUserWatchlistJob.php
@@ -0,0 +1,118 @@
+<?php
+
+use MediaWiki\MediaWikiServices;
+
+/**
+ * Job to clear a users watchlist in batches.
+ *
+ * @author Addshore
+ *
+ * @ingroup JobQueue
+ * @since 1.31
+ */
+class ClearUserWatchlistJob extends Job {
+
+	/**
+	 * @param User $user User to clear the watchlist for.
+	 * @param int $maxWatchlistId The maximum wl_id at the time the job was first created.
+	 *
+	 * @return ClearUserWatchlistJob
+	 */
+	public static function newForUser( User $user, $maxWatchlistId ) {
+		return new self(
+			null,
+			[ 'userId' => $user->getId(), 'maxWatchlistId' => $maxWatchlistId ]
+		);
+	}
+
+	/**
+	 * @param Title|null $title Not used by this job.
+	 * @param array $params
+	 *  - userId,         The ID for the user whose watchlist is being cleared.
+	 *  - maxWatchlistId, The maximum wl_id at the time the job was first created,
+	 */
+	public function __construct( Title $title = null, array $params ) {
+		parent::__construct(
+			'clearUserWatchlist',
+			SpecialPage::getTitleFor( 'EditWatchlist', 'clear' ),
+			$params
+		);
+
+		$this->removeDuplicates = true;
+	}
+
+	public function run() {
+		global $wgUpdateRowsPerQuery;
+		$userId = $this->params['userId'];
+		$maxWatchlistId = $this->params['maxWatchlistId'];
+		$batchSize = $wgUpdateRowsPerQuery;
+
+		$loadBalancer = MediaWikiServices::getInstance()->getDBLoadBalancer();
+		$dbw = $loadBalancer->getConnection( DB_MASTER );
+		$dbr = $loadBalancer->getConnection( DB_REPLICA, [ 'watchlist' ] );
+
+		// Wait before lock to try to reduce time waiting in the lock.
+		if ( !$loadBalancer->safeWaitForMasterPos( $dbr ) ) {
+			$this->setLastError( 'Timed out waiting for replica to catch up before lock' );
+			return false;
+		}
+
+		// Use a named lock so that jobs for this user see each others' changes
+		$lockKey = "ClearUserWatchlistJob:$userId";
+		$scopedLock = $dbw->getScopedLockAndFlush( $lockKey, __METHOD__, 10 );
+		if ( !$scopedLock ) {
+			$this->setLastError( "Could not acquire lock '$lockKey'" );
+			return false;
+		}
+
+		if ( !$loadBalancer->safeWaitForMasterPos( $dbr ) ) {
+			$this->setLastError( 'Timed out waiting for replica to catch up within lock' );
+			return false;
+		}
+
+		// Clear any stale REPEATABLE-READ snapshot
+		$dbr->flushSnapshot( __METHOD__ );
+
+		$watchlistIds = $dbr->selectFieldValues(
+			'watchlist',
+			'wl_id',
+			[
+				'wl_user' => $userId,
+				'wl_id <= ' . $maxWatchlistId
+			],
+			__METHOD__,
+			[
+				'ORDER BY' => 'wl_id ASC',
+				'LIMIT' => $batchSize,
+			]
+		);
+
+		if ( count( $watchlistIds ) == 0 ) {
+			return true;
+		}
+
+		$dbw->delete( 'watchlist', [ 'wl_id' => $watchlistIds ], __METHOD__ );
+
+		// Commit changes and remove lock before inserting next job.
+		$lbf = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
+		$lbf->commitMasterChanges( __METHOD__ );
+		unset( $scopedLock );
+
+		if ( count( $watchlistIds ) === (int)$batchSize ) {
+			// Until we get less results than the limit, recursively push
+			// the same job again.
+			JobQueueGroup::singleton()->push( new self( $this->getTitle(), $this->getParams() ) );
+		}
+
+		return true;
+	}
+
+	public function getDeduplicationInfo() {
+		$info = parent::getDeduplicationInfo();
+		// This job never has a namespace or title so we can't use it for deduplication
+		unset( $info['namespace'] );
+		unset( $info['title'] );
+		return $info;
+	}
+
+}