Allow setting max execution time to several special pages

These special pages and their counter-part APIs are:
 - Special:RecentChanges
 - Special:Watchlist
 - Special:Log
 - Special:Contributions

This also changes the way MAX_EXECUTION_TIME works from taking the value
as milliseconds, it takes seconds which is more intuitive for users.

Bug: T297708
Depends-On: I126e7181422d8da1a63afc3717faa4f72a687dd9
Change-Id: I3ff78751c3df3b6342f1865d35c2075f4415185d

includes/DefaultSettings.php

@@ -2370,6 +2370,13 @@ $wgDatabaseReplicaLagWarning = 10;
  */
 $wgDatabaseReplicaLagCritical = 30;
 
+/**
+ * Max execution time for queries of several expensive special pages such as RecentChanges
+ * in milliseconds.
+ * @since 1.38
+ */
+$wgMaxExecutionTimeForExpensiveQueries = 0;
+
 /**
  * RevisionStore table schema migration stage (content, slots, content_models & slot_roles tables).
  * Use the SCHEMA_COMPAT_XXX flags. Supported values:

includes/ServiceWiring.php

@@ -1877,7 +1877,8 @@ return [
 			$services->getCommentStore(),
 			$services->getWatchedItemStore(),
 			$services->getHookContainer(),
-			$services->getMainConfig()->get( 'WatchlistExpiry' )
+			$services->getMainConfig()->get( 'WatchlistExpiry' ),
+			$services->getMainConfig()->get( 'MaxExecutionTimeForExpensiveQueries' )
 		);
 	},
 

includes/api/ApiQueryLogEvents.php

@@ -259,6 +259,11 @@ class ApiQueryLogEvents extends ApiQueryBase {
 			$this->addOption( 'STRAIGHT_JOIN' );
 		}
 
+		$this->addOption(
+			'MAX_EXECUTION_TIME',
+			$this->getConfig()->get( 'MaxExecutionTimeForExpensiveQueries' )
+		);
+
 		$count = 0;
 		$res = $this->select( __METHOD__ );
 

includes/api/ApiQueryRecentChanges.php

@@ -416,6 +416,10 @@ class ApiQueryRecentChanges extends ApiQueryGeneratorBase {
 		}
 
 		$this->addOption( 'LIMIT', $params['limit'] + 1 );
+		$this->addOption(
+			'MAX_EXECUTION_TIME',
+			$this->getConfig()->get( 'MaxExecutionTimeForExpensiveQueries' )
+		);
 
 		$hookData = [];
 		$count = 0;

includes/api/ApiQueryUserContribs.php

@@ -486,6 +486,10 @@ class ApiQueryUserContribs extends ApiQueryBase {
 				$this->addWhere( '1=0' );
 			}
 		}
+		$this->addOption(
+			'MAX_EXECUTION_TIME',
+			$this->getConfig()->get( 'MaxExecutionTimeForExpensiveQueries' )
+		);
 	}
 
 	/**

includes/libs/rdbms/querybuilder/SelectQueryBuilder.php

@@ -388,6 +388,17 @@ class SelectQueryBuilder extends JoinGroupBase {
 		return $this;
 	}
 
+	/**
+	 * Set MAX_EXECUTION_TIME for queries.
+	 *
+	 * @param int $time maximum allowed time in milliseconds
+	 * @return $this
+	 */
+	public function setMaxExecutionTime( int $time ) {
+		$this->options['MAX_EXECUTION_TIME'] = $time;
+		return $this;
+	}
+
 	/**
 	 * Add a GROUP BY clause. May be either an SQL fragment string naming a
 	 * field or expression to group by, or an array of such SQL fragments.

includes/logging/LogPager.php

@@ -380,6 +380,8 @@ class LogPager extends ReverseChronologicalPager {
 			$options[] = 'STRAIGHT_JOIN';
 		}
 
+		$options['MAX_EXECUTION_TIME'] = $this->getConfig()->get( 'MaxExecutionTimeForExpensiveQueries' );
+
 		$info = [
 			'tables' => $tables,
 			'fields' => $fields,

includes/specials/SpecialRecentChanges.php

@@ -398,6 +398,7 @@ class SpecialRecentChanges extends ChangesListSpecialPage {
 		// MediaWiki 1.26 this used to use the plus operator instead, which meant
 		// that extensions weren't able to change these conditions
 		$query_options = array_merge( $orderByAndLimit, $query_options );
+		$query_options['MAX_EXECUTION_TIME'] = $this->getConfig()->get( 'MaxExecutionTimeForExpensiveQueries' );
 		$rows = $dbr->select(
 			$tables,
 			$fields,

includes/specials/SpecialRecentChangesLinked.php

@@ -249,7 +249,6 @@ class SpecialRecentChangesLinked extends SpecialRecentChanges {
 				' ORDER BY rc_timestamp DESC';
 			$sql = $dbr->limitResult( $sql, $limit, false );
 		}
-
 		return $dbr->query( $sql, __METHOD__ );
 	}
 

includes/specials/SpecialWatchlist.php

@@ -459,6 +459,7 @@ class SpecialWatchlist extends ChangesListSpecialPage {
 		// array_merge() is used intentionally here so that hooks can, should
 		// they so desire, override the ORDER BY / LIMIT condition(s)
 		$query_options = array_merge( $orderByAndLimit, $query_options );
+		$query_options['MAX_EXECUTION_TIME'] = $this->getConfig()->get( 'MaxExecutionTimeForExpensiveQueries' );
 
 		return $dbr->select(
 			$tables,

includes/specials/pagers/ContribsPager.php

@@ -276,6 +276,7 @@ class ContribsPager extends RangeChronologicalPager {
 			$order
 		);
 
+		$options['MAX_EXECUTION_TIME'] = $this->getConfig()->get( 'MaxExecutionTimeForExpensiveQueries' );
 		/*
 		 * This hook will allow extensions to add in additional queries, so they can get their data
 		 * in My Contributions as well. Extensions should append their results to the $data array.

includes/watcheditem/WatchedItemQueryService.php

@@ -78,18 +78,25 @@ class WatchedItemQueryService {
 	 */
 	private $expiryEnabled;
 
+	/**
+	 * @var int Max query execution time
+	 */
+	private $maxQueryExecutionTime;
+
 	public function __construct(
 		ILoadBalancer $loadBalancer,
 		CommentStore $commentStore,
 		WatchedItemStoreInterface $watchedItemStore,
 		HookContainer $hookContainer,
-		bool $expiryEnabled = false
+		bool $expiryEnabled = false,
+		int $maxQueryExecutionTime = 0
 	) {
 		$this->loadBalancer = $loadBalancer;
 		$this->commentStore = $commentStore;
 		$this->watchedItemStore = $watchedItemStore;
 		$this->hookRunner = new HookRunner( $hookContainer );
 		$this->expiryEnabled = $expiryEnabled;
+		$this->maxQueryExecutionTime = $maxQueryExecutionTime;
 	}
 
 	/**
@@ -712,7 +719,9 @@ class WatchedItemQueryService {
 		if ( array_key_exists( 'limit', $options ) ) {
 			$dbOptions['LIMIT'] = (int)$options['limit'] + 1;
 		}
-
+		if ( $this->maxQueryExecutionTime ) {
+			$dbOptions['MAX_EXECUTION_TIME'] = $this->maxQueryExecutionTime;
+		}
 		return $dbOptions;
 	}
 
@@ -730,6 +739,9 @@ class WatchedItemQueryService {
 		if ( array_key_exists( 'limit', $options ) ) {
 			$dbOptions['LIMIT'] = (int)$options['limit'];
 		}
+		if ( $this->maxQueryExecutionTime ) {
+			$dbOptions['MAX_EXECUTION_TIME'] = $this->maxQueryExecutionTime;
+		}
 		return $dbOptions;
 	}