From 916997d6f65f4bb1d65fe44305cfe3db8ac4a0d8 Mon Sep 17 00:00:00 2001
From: Tim Starling <tstarling@users.mediawiki.org>
Date: Sun, 22 Apr 2007 21:17:10 +0000
Subject: [PATCH] maxlag hidden parameter. Allows client-side bots to throttle
 under slave lag conditions, just like server-side maintenance scripts.

---
 includes/Wiki.php | 14 ++++++++++++++
 index.php         |  7 +++++++
 2 files changed, 21 insertions(+)

diff --git a/includes/Wiki.php b/includes/Wiki.php
index 9437ce40f9..51a88693fa 100644
--- a/includes/Wiki.php
+++ b/includes/Wiki.php
@@ -56,6 +56,20 @@ class MediaWiki {
 		return $article;
 	}
 
+	function checkMaxLag( $maxLag ) {
+		global $wgLoadBalancer;
+		list( $host, $lag ) = $wgLoadBalancer->getMaxLag();
+		if ( $lag > $maxLag ) {
+			header( 'HTTP/1.1 500 Internal server error' );
+			header( 'Content-Type: text/plain' );
+			echo "Waiting for $host: $lag seconds lagged\n";
+			return false;
+		} else {
+			return true;
+		}
+	}
+
+
 	/**
 	 * Checks some initial queries
 	 * Note that $title here is *not* a Title object, but a string!
diff --git a/index.php b/index.php
index 6b4cab0558..959fe7ff4c 100644
--- a/index.php
+++ b/index.php
@@ -44,6 +44,13 @@ $mediaWiki = new MediaWiki();
 wfProfileIn( 'main-misc-setup' );
 OutputPage::setEncodings(); # Not really used yet
 
+$maxLag = $wgRequest->getVal( 'maxlag' );
+if ( !is_null( $maxLag ) ) {
+	if ( !$mediaWiki->checkMaxLag( $maxLag ) ) {
+		exit;
+	}
+}
+
 # Query string fields
 $action = $wgRequest->getVal( 'action', 'view' );
 $title = $wgRequest->getVal( 'title' );
-- 
2.20.1