Make RecentChangesUpdateJob::updateActiveUsers more robust

Do work we can outside of the lock (purge no longer active users)
and fail more gracefully if the lock is taken (if this is the case,
we're probably on a high traffic wiki, so this job is going to
run very often anyway, so no need to warn).

Given this is an asynchronous job people can't expect this to be
always fully consistent with the actual state of the RC table anyway.

Note: This will still sometimes log the warning (if we have a race
between Database::lockIsFree and Database::lock), but that should be
negligible.

Bug: T156638
Change-Id: I2e49a8e12bc64156d64a32ccf54911a76087346a

diff --git a/includes/jobqueue/jobs/RecentChangesUpdateJob.php b/includes/jobqueue/jobs/RecentChangesUpdateJob.php
index 0e90674..5c73308 100644 (file)
--- a/includes/jobqueue/jobs/RecentChangesUpdateJob.php
+++ b/includes/jobqueue/jobs/RecentChangesUpdateJob.php
@@ -128,8 +128,10 @@ class RecentChangesUpdateJob extends Job {
                                $dbw->setSessionOptions( [ 'connTimeout' => 900 ] );
 
                                $lockKey = wfWikiID() . '-activeusers';
-                               if ( !$dbw->lock( $lockKey, __METHOD__, 1 ) ) {
-                                       return; // exclusive update (avoids duplicate entries)
+                               if ( !$dbw->lockIsFree( $lockKey, __METHOD__ ) || !$dbw->lock( $lockKey, __METHOD__, 1 ) ) {
+                                       // Exclusive update (avoids duplicate entries)… it's usually fine to just drop out here,
+                                       // if the Job is already running.
+                                       return;
                                }
 
                                $nowUnix = time();
@@ -168,15 +170,6 @@ class RecentChangesUpdateJob extends Job {
                                        $names[$row->rc_user_text] = $row->lastedittime;
                                }
 
-                               // Rotate out users that have not edited in too long (according to old data set)
-                               $dbw->delete( 'querycachetwo',
-                                       [
-                                               'qcc_type' => 'activeusers',
-                                               'qcc_value < ' . $dbw->addQuotes( $nowUnix - $days * 86400 ) // TS_UNIX
-                                       ],
-                                       __METHOD__
-                               );
-
                                // Find which of the recently active users are already accounted for
                                if ( count( $names ) ) {
                                        $res = $dbw->select( 'querycachetwo',
@@ -184,9 +177,13 @@ class RecentChangesUpdateJob extends Job {
                                                [
                                                        'qcc_type' => 'activeusers',
                                                        'qcc_namespace' => NS_USER,
-                                                       'qcc_title' => array_keys( $names ) ],
+                                                       'qcc_title' => array_keys( $names ),
+                                                       'qcc_value >= ' . $dbw->addQuotes( $nowUnix - $days * 86400 ), // TS_UNIX
+                                                ],
                                                __METHOD__
                                        );
+                                       // Note: In order for this to be actually consistent, we would need
+                                       // to update these rows with the new lastedittime.
                                        foreach ( $res as $row ) {
                                                unset( $names[$row->user_name] );
                                        }
@@ -224,6 +221,16 @@ class RecentChangesUpdateJob extends Job {
                                );
 
                                $dbw->unlock( $lockKey, __METHOD__ );
+
+                               // Rotate out users that have not edited in too long (according to old data set)
+                               $dbw->delete( 'querycachetwo',
+                                       [
+                                               'qcc_type' => 'activeusers',
+                                               'qcc_value < ' . $dbw->addQuotes( $nowUnix - $days * 86400 ) // TS_UNIX
+                                       ],
+                                       __METHOD__
+                               );
+
                        },
                        __METHOD__
                );