From 0725cbe9a76fb11eed382aa1d4dfaabfabb5e9b6 Mon Sep 17 00:00:00 2001
From: Stephane Bisson <sbisson@wikimedia.org>
Date: Tue, 5 Sep 2017 11:45:55 -0400
Subject: [PATCH] RCFilters: Live Update: download less data

Make ChangesListSpecialPage respect action=render
to exclude the MW chrome (header, logo, sidebar, etc).

Introduce peek=1 in ChangesListSpecialPage to skip
the form and changes list rendering and return
200 when there is new data and 304 (not modified)
where there isn't.

Together, they reduce the page size from 49.9k to 275b on polling
and eliminate most HTTP 404 console errors.

Bug: T173613
Change-Id: I0aec878ae80e22814b196b26e944db8c78a5f91a
---
 .../specialpage/ChangesListSpecialPage.php    | 21 +++++++++++++++----
 .../mw.rcfilters.Controller.js                | 14 +++++++++++--
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/includes/specialpage/ChangesListSpecialPage.php b/includes/specialpage/ChangesListSpecialPage.php
index 5f544042f9..04d03f5200 100644
--- a/includes/specialpage/ChangesListSpecialPage.php
+++ b/includes/specialpage/ChangesListSpecialPage.php
@@ -519,16 +519,25 @@ abstract class ChangesListSpecialPage extends SpecialPage {
 	public function execute( $subpage ) {
 		$this->rcSubpage = $subpage;
 
-		$this->setHeaders();
-		$this->outputHeader();
-		$this->addModules();
-
 		$rows = $this->getRows();
 		$opts = $this->getOptions();
 		if ( $rows === false ) {
 			$rows = new FakeResultWrapper( [] );
 		}
 
+		// Used by Structured UI app to get results without MW chrome
+		if ( $this->getRequest()->getVal( 'action' ) === 'render' ) {
+			$this->getOutput()->setArticleBodyOnly( true );
+		}
+
+		// Used by "live update" and "view newest" to check
+		// if there's new changes with minimal data transfer
+		if ( $this->getRequest()->getBool( 'peek' ) ) {
+			$code = $rows->numRows() > 0 ? 200 : 304;
+			$this->getOutput()->setStatusCode( $code );
+			return;
+		}
+
 		$batch = new LinkBatch;
 		foreach ( $rows as $row ) {
 			$batch->add( NS_USER, $row->rc_user_text );
@@ -542,6 +551,10 @@ abstract class ChangesListSpecialPage extends SpecialPage {
 			}
 		}
 		$batch->execute();
+
+		$this->setHeaders();
+		$this->outputHeader();
+		$this->addModules();
 		$this->webOutput( $rows, $opts );
 
 		$rows->free();
diff --git a/resources/src/mediawiki.rcfilters/mw.rcfilters.Controller.js b/resources/src/mediawiki.rcfilters/mw.rcfilters.Controller.js
index 81bfb477f0..8d0aa05bb3 100644
--- a/resources/src/mediawiki.rcfilters/mw.rcfilters.Controller.js
+++ b/resources/src/mediawiki.rcfilters/mw.rcfilters.Controller.js
@@ -561,6 +561,7 @@
 			'liveUpdate',
 			{
 				limit: 1,
+				peek: 1, // bypasses all UI
 				from: this.changesListModel.getNextFrom()
 			}
 		);
@@ -1130,6 +1131,7 @@
 
 		counterId = counterId || 'updateChangesList';
 		params = params || {};
+		params.action = 'render'; // bypasses MW chrome
 
 		uri.extend( params );
 
@@ -1149,7 +1151,7 @@
 
 		return $.ajax( uri.toString(), { contentType: 'html' } )
 			.then(
-				function ( html ) {
+				function ( html, reason ) {
 					var $parsed,
 						pieces;
 
@@ -1157,7 +1159,15 @@
 						return $.Deferred().reject();
 					}
 
-					$parsed = $( $.parseHTML( html ) );
+					if ( params.peek && reason === 'notmodified' ) {
+						return {
+							changes: 'NO_RESULTS'
+						};
+					}
+
+					// Because of action=render, the response is a list of nodes.
+					// It has to be put under a root node so it can be queried.
+					$parsed = $( '<div>' ).append( $( $.parseHTML( html ) ) );
 
 					pieces = {
 						// Changes list
-- 
2.20.1