From 0477d11be6c00fef699f4105005a997ccdf7d9c7 Mon Sep 17 00:00:00 2001
From: Aaron Schulz <aschulz@wikimedia.org>
Date: Tue, 20 Oct 2015 17:27:27 -0700
Subject: [PATCH] Send X-Database-Lagged header to help with debugging

Change-Id: Ib654c49a61a1279091c5da92a2bef2ad1f992d23
---
 includes/MediaWiki.php | 1 +
 1 file changed, 1 insertion(+)

diff --git a/includes/MediaWiki.php b/includes/MediaWiki.php
index 3399790c20..7ae7c35b64 100644
--- a/includes/MediaWiki.php
+++ b/includes/MediaWiki.php
@@ -515,6 +515,7 @@ class MediaWiki {
 		if ( $factory->laggedSlaveUsed() ) {
 			$maxAge = $this->config->get( 'CdnMaxageLagged' );
 			$this->context->getOutput()->lowerCdnMaxage( $maxAge );
+			$request->response()->header( "X-Database-Lagged: true" );
 			wfDebugLog( 'replication', "Lagged DB used; CDN cache TTL limited to $maxAge seconds" );
 		}
 	}
-- 
2.20.1