Merge "rdbms: avoid lag estimates in getLagFromPtHeartbeat ruined by snapshots"

[lhc/web/wiklou.git] / includes / libs / rdbms / database / DatabaseMysqlBase.php

diff --git a/includes/libs/rdbms/database/DatabaseMysqlBase.php b/includes/libs/rdbms/database/DatabaseMysqlBase.php
index b0fcade..e6acaa9 100644 (file)
--- a/includes/libs/rdbms/database/DatabaseMysqlBase.php
+++ b/includes/libs/rdbms/database/DatabaseMysqlBase.php
@@ -763,6 +763,17 @@ abstract class DatabaseMysqlBase extends Database {
        protected function getLagFromPtHeartbeat() {
                $options = $this->lagDetectionOptions;
 
+               if ( $this->trxLevel ) {
+                       // Avoid returning higher and higher lag value due to snapshot age
+                       // given that the isolation level will typically be REPEATABLE-READ
+                       $this->queryLogger->warning(
+                               "Using cached lag value for {db_server} due to active transaction",
+                               $this->getLogContext( [ 'method' => __METHOD__ ] )
+                       );
+
+                       return $this->getTransactionLagStatus()['lag'];
+               }
+
                if ( isset( $options['conds'] ) ) {
                        // Best method for multi-DC setups: use logical channel names
                        $data = $this->getHeartbeatData( $options['conds'] );