From c4c501d9bbcf44baf72efe7c0ee343d699fb76fd Mon Sep 17 00:00:00 2001
From: =?utf8?q?Gerg=C5=91=20Tisza?= <gtisza@wikimedia.org>
Date: Thu, 18 Feb 2016 02:10:31 +0000
Subject: [PATCH] Do not unauthenticate if autocreation fails due to a race

Bug: T70012
Change-Id: I523ee94744ac943ede78af59ab381b65ae26e672
---
 includes/session/SessionManager.php | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/includes/session/SessionManager.php b/includes/session/SessionManager.php
index 5573ec7af3..e7a5e2ea49 100644
--- a/includes/session/SessionManager.php
+++ b/includes/session/SessionManager.php
@@ -475,12 +475,21 @@ final class SessionManager implements SessionManagerInterface {
 			$status = $user->addToDatabase();
 			if ( !$status->isOK() ) {
 				// @codeCoverageIgnoreStart
-				$logger->error( __METHOD__ . ': failed with message ' . $status->getWikiText(),
-					[
-						'username' => $userName,
-				] );
-				$user->setId( 0 );
-				$user->loadFromId();
+				// double-check for a race condition (T70012)
+				$id = User::idFromName( $user->getName(), User::READ_LATEST );
+				if ( $id ) {
+					$logger->info( __METHOD__ . ': tried to autocreate existing user',
+						[
+							'username' => $userName,
+						] );
+				} else {
+					$logger->error( __METHOD__ . ': failed with message ' . $status->getWikiText(),
+						[
+							'username' => $userName,
+						] );
+				}
+				$user->setId( $id );
+				$user->loadFromId( User::READ_LATEST );
 				return false;
 				// @codeCoverageIgnoreEnd
 			}
-- 
2.20.1