From e9c7e1d34e4785c171f70bb4702a1312307b9773 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Sun, 14 May 2017 16:56:04 -0700
Subject: [PATCH] Avoid DB_MASTER queries in User::newSystemUser() when
 possible

Bug: T92357
Change-Id: I1c90fef9b4f3acc658f4911a8db6f985e7cc7c83
---
 includes/user/User.php | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/includes/user/User.php b/includes/user/User.php
index 5dd4be1b4d..ce6bbc300d 100644
--- a/includes/user/User.php
+++ b/includes/user/User.php
@@ -693,19 +693,31 @@ class User implements IDBAccessObject {
 			return null;
 		}
 
-		$fields = self::selectFields();
-
-		$dbw = wfGetDB( DB_MASTER );
-		$row = $dbw->selectRow(
+		$dbr = wfGetDB( DB_REPLICA );
+		$row = $dbr->selectRow(
 			'user',
-			$fields,
+			self::selectFields(),
 			[ 'user_name' => $name ],
 			__METHOD__
 		);
+		if ( !$row ) {
+			// Try the master database...
+			$dbw = wfGetDB( DB_MASTER );
+			$row = $dbw->selectRow(
+				'user',
+				self::selectFields(),
+				[ 'user_name' => $name ],
+				__METHOD__
+			);
+		}
+
 		if ( !$row ) {
 			// No user. Create it?
-			return $options['create'] ? self::createNew( $name, [ 'token' => self::INVALID_TOKEN ] ) : null;
+			return $options['create']
+				? self::createNew( $name, [ 'token' => self::INVALID_TOKEN ] )
+				: null;
 		}
+
 		$user = self::newFromRow( $row );
 
 		// A user is considered to exist as a non-system user if it can
-- 
2.20.1