From: Aaron Schulz <aschulz@wikimedia.org>
Date: Sat, 24 Mar 2018 13:49:14 +0000 (-0700)
Subject: Use CONN_TRX_AUTO in WikiPage speculative revision ID callback
X-Git-Tag: 1.34.0-rc.0~5636^2
X-Git-Url: http://git.cyclocoop.org/%28?a=commitdiff_plain;h=766cdc944b94f56e8b7c4bc793fd7b39eceb8b65;p=lhc%2Fweb%2Fwiklou.git

Use CONN_TRX_AUTO in WikiPage speculative revision ID callback

This increases the odds of seeing newer data and not guessing a
wrong revision ID due to getting raced out between stash and save.

Change-Id: Icf0f9b9c4d559f4ddf05a4ca8679e3c4dca5620a
---

diff --git a/includes/page/WikiPage.php b/includes/page/WikiPage.php
index d4a17c82b3..cfeb331bc9 100644
--- a/includes/page/WikiPage.php
+++ b/includes/page/WikiPage.php
@@ -2117,7 +2117,12 @@ class WikiPage implements Page, IDBAccessObject {
 					: DB_REPLICA; // T154554
 
 				$edit->popts->setSpeculativeRevIdCallback( function () use ( $dbIndex ) {
-					return 1 + (int)wfGetDB( $dbIndex )->selectField(
+					$lb = MediaWikiServices::getInstance()->getDBLoadBalancer();
+					// Use a fresh connection in order to see the latest data, by avoiding
+					// stale data from REPEATABLE-READ snapshots.
+					$db = $lb->getConnectionRef( $dbIndex, [], false, $lb::CONN_TRX_AUTO );
+
+					return 1 + (int)$db->selectField(
 						'revision',
 						'MAX(rev_id)',
 						[],