From ac202927d4ea104124fb50ca0b9fdd588cf45111 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Thu, 25 May 2017 12:37:08 -0700
Subject: [PATCH] Add $wgMaxJobDBWriteDuration setting for avoiding replication
 lag

This is similar to $wgMaxUserDBWriteDuration except for jobs.

Also use the Config class in JobRunner instead of globals.

Bug: T95501
Change-Id: I4949bb99c26451429c7acf82ecc4444bf9fb835f
---
 includes/DefaultSettings.php    |  9 ++++++++
 includes/jobqueue/JobRunner.php | 37 +++++++++++++++++++++------------
 2 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/includes/DefaultSettings.php b/includes/DefaultSettings.php
index 19c585d14c..5b833477a6 100644
--- a/includes/DefaultSettings.php
+++ b/includes/DefaultSettings.php
@@ -8560,6 +8560,15 @@ $wgPopularPasswordFile = __DIR__ . '/../serialized/commonpasswords.cdb';
  */
 $wgMaxUserDBWriteDuration = false;
 
+/*
+ * Max time (in seconds) a job-generated transaction can spend in writes.
+ * If exceeded, the transaction is rolled back with an error instead of being committed.
+ *
+ * @var int|bool Disabled if false
+ * @since 1.30
+ */
+$wgMaxJobDBWriteDuration = false;
+
 /**
  * Mapping of event channels (or channel categories) to EventRelayer configuration.
  *
diff --git a/includes/jobqueue/JobRunner.php b/includes/jobqueue/JobRunner.php
index 6415533508..18cabc5df1 100644
--- a/includes/jobqueue/JobRunner.php
+++ b/includes/jobqueue/JobRunner.php
@@ -38,6 +38,8 @@ use Wikimedia\Rdbms\DBReplicationWaitError;
  * @since 1.24
  */
 class JobRunner implements LoggerAwareInterface {
+	/** @var Config */
+	protected $config;
 	/** @var callable|null Debug output handler */
 	protected $debug;
 
@@ -74,6 +76,7 @@ class JobRunner implements LoggerAwareInterface {
 			$logger = LoggerFactory::getInstance( 'runJobs' );
 		}
 		$this->setLogger( $logger );
+		$this->config = MediaWikiServices::getInstance()->getMainConfig();
 	}
 
 	/**
@@ -101,7 +104,8 @@ class JobRunner implements LoggerAwareInterface {
 	 * @return array Summary response that can easily be JSON serialized
 	 */
 	public function run( array $options ) {
-		global $wgJobClasses, $wgTrxProfilerLimits;
+		$jobClasses = $this->config->get( 'JobClasses' );
+		$profilerLimits = $this->config->get( 'TrxProfilerLimits' );
 
 		$response = [ 'jobs' => [], 'reached' => 'none-ready' ];
 
@@ -111,7 +115,7 @@ class JobRunner implements LoggerAwareInterface {
 		$noThrottle = isset( $options['throttle'] ) && !$options['throttle'];
 
 		// Bail if job type is invalid
-		if ( $type !== false && !isset( $wgJobClasses[$type] ) ) {
+		if ( $type !== false && !isset( $jobClasses[$type] ) ) {
 			$response['reached'] = 'none-possible';
 			return $response;
 		}
@@ -136,7 +140,7 @@ class JobRunner implements LoggerAwareInterface {
 		// Catch huge single updates that lead to replica DB lag
 		$trxProfiler = Profiler::instance()->getTransactionProfiler();
 		$trxProfiler->setLogger( LoggerFactory::getInstance( 'DBPerformance' ) );
-		$trxProfiler->setExpectations( $wgTrxProfilerLimits['JobRunner'], __METHOD__ );
+		$trxProfiler->setExpectations( $profilerLimits['JobRunner'], __METHOD__ );
 
 		// Some jobs types should not run until a certain timestamp
 		$backoffs = []; // map of (type => UNIX expiry)
@@ -360,15 +364,13 @@ class JobRunner implements LoggerAwareInterface {
 	 * @see $wgJobBackoffThrottling
 	 */
 	private function getBackoffTimeToWait( Job $job ) {
-		global $wgJobBackoffThrottling;
+		$throttling = $this->config->get( 'JobBackoffThrottling' );
 
-		if ( !isset( $wgJobBackoffThrottling[$job->getType()] ) ||
-			$job instanceof DuplicateJob // no work was done
-		) {
+		if ( !isset( $throttling[$job->getType()] ) || $job instanceof DuplicateJob ) {
 			return 0; // not throttled
 		}
 
-		$itemsPerSecond = $wgJobBackoffThrottling[$job->getType()];
+		$itemsPerSecond = $throttling[$job->getType()];
 		if ( $itemsPerSecond <= 0 ) {
 			return 0; // not throttled
 		}
@@ -516,17 +518,17 @@ class JobRunner implements LoggerAwareInterface {
 	 * @throws DBError
 	 */
 	private function commitMasterChanges( LBFactory $lbFactory, Job $job, $fnameTrxOwner ) {
-		global $wgJobSerialCommitThreshold;
+		$syncThreshold = $this->config->get( 'JobSerialCommitThreshold' );
 
 		$time = false;
 		$lb = $lbFactory->getMainLB( wfWikiID() );
-		if ( $wgJobSerialCommitThreshold !== false && $lb->getServerCount() > 1 ) {
+		if ( $syncThreshold !== false && $lb->getServerCount() > 1 ) {
 			// Generally, there is one master connection to the local DB
 			$dbwSerial = $lb->getAnyOpenConnection( $lb->getWriterIndex() );
 			// We need natively blocking fast locks
 			if ( $dbwSerial && $dbwSerial->namedLocksEnqueue() ) {
 				$time = $dbwSerial->pendingWriteQueryDuration( $dbwSerial::ESTIMATE_DB_APPLY );
-				if ( $time < $wgJobSerialCommitThreshold ) {
+				if ( $time < $syncThreshold ) {
 					$dbwSerial = false;
 				}
 			} else {
@@ -538,7 +540,12 @@ class JobRunner implements LoggerAwareInterface {
 		}
 
 		if ( !$dbwSerial ) {
-			$lbFactory->commitMasterChanges( $fnameTrxOwner );
+			$lbFactory->commitMasterChanges(
+				$fnameTrxOwner,
+				// Abort if any transaction was too big
+				[ 'maxWriteDuration' => $this->config->get( 'MaxJobDBWriteDuration' ) ]
+			);
+
 			return;
 		}
 
@@ -563,7 +570,11 @@ class JobRunner implements LoggerAwareInterface {
 		}
 
 		// Actually commit the DB master changes
-		$lbFactory->commitMasterChanges( $fnameTrxOwner );
+		$lbFactory->commitMasterChanges(
+			$fnameTrxOwner,
+			// Abort if any transaction was too big
+			[ 'maxWriteDuration' => $this->config->get( 'MaxJobDBWriteDuration' ) ]
+		);
 		ScopedCallback::consume( $unlocker );
 	}
 }
-- 
2.20.1