From 1c1734758056005413dffe9859c72604231ecd9f Mon Sep 17 00:00:00 2001
From: Ori Livneh <ori@wikimedia.org>
Date: Wed, 3 Dec 2014 23:37:56 -0800
Subject: [PATCH] Optimize how user options are delivered to the client

We currently embed the full set of user options in a <script> tag in the HTML
output of every page. This is grossly inefficient, because the full set of
options is usually largely made up of site defaults which the user hasn't
customized.

So instead of doing that, let's emit the default options using one
ResourceLoader module and then apply the user's customizations on top.

This has the effect of slightly increasing the total bytes of JavaScript code
(because options that the user has customized will be emitted twice: once with
their default value in the user.defaults module, and then again with the
customized value in user.options). But this is more than offset by the
fact that the bulk of user options code (~4 kB uncompressed on enwiki) becomes
cacheable across requests.

Bonus round:
* Varnish gets to cache 4 kB fewer per page.
* Changes to the default options don't take 30 days to propagate.

Change-Id: I5a7e258d2d69159381bf5cc363227088b8fd6019
---
 autoload.php                                  |  1 +
 includes/User.php                             | 15 ++++-
 .../ResourceLoaderUserDefaultsModule.php      | 58 +++++++++++++++++++
 .../ResourceLoaderUserOptionsModule.php       |  9 ++-
 resources/Resources.php                       |  1 +
 5 files changed, 82 insertions(+), 2 deletions(-)
 create mode 100644 includes/resourceloader/ResourceLoaderUserDefaultsModule.php

diff --git a/autoload.php b/autoload.php
index dbc28edd7b..8003284526 100644
--- a/autoload.php
+++ b/autoload.php
@@ -961,6 +961,7 @@ $wgAutoloadLocalClasses = array(
 	'ResourceLoaderUserCSSPrefsModule' => __DIR__ . '/includes/resourceloader/ResourceLoaderUserCSSPrefsModule.php',
 	'ResourceLoaderUserGroupsModule' => __DIR__ . '/includes/resourceloader/ResourceLoaderUserGroupsModule.php',
 	'ResourceLoaderUserModule' => __DIR__ . '/includes/resourceloader/ResourceLoaderUserModule.php',
+	'ResourceLoaderUserDefaultsModule' => __DIR__ . '/includes/resourceloader/ResourceLoaderUserDefaultsModule.php',
 	'ResourceLoaderUserOptionsModule' => __DIR__ . '/includes/resourceloader/ResourceLoaderUserOptionsModule.php',
 	'ResourceLoaderUserTokensModule' => __DIR__ . '/includes/resourceloader/ResourceLoaderUserTokensModule.php',
 	'ResourceLoaderWikiModule' => __DIR__ . '/includes/resourceloader/ResourceLoaderWikiModule.php',
diff --git a/includes/User.php b/includes/User.php
index 5348020089..3cbb05240f 100644
--- a/includes/User.php
+++ b/includes/User.php
@@ -58,6 +58,12 @@ class User implements IDBAccessObject {
 	 */
 	const MAX_WATCHED_ITEMS_CACHE = 100;
 
+	/**
+	 * Exclude user options that are set to their default value.
+	 * @since 1.25
+	 */
+	const GETOPTIONS_EXCLUDE_DEFAULTS = 1;
+
 	/**
 	 * @var PasswordFactory Lazily loaded factory object for passwords
 	 */
@@ -2547,9 +2553,12 @@ class User implements IDBAccessObject {
 	/**
 	 * Get all user's options
 	 *
+	 * @param int $flags Bitwise combination of:
+	 *   User::GETOPTIONS_EXCLUDE_DEFAULTS  Exclude user options that are set
+	 *                                      to the default value. (Since 1.25)
 	 * @return array
 	 */
-	public function getOptions() {
+	public function getOptions( $flags = 0 ) {
 		global $wgHiddenPrefs;
 		$this->loadOptions();
 		$options = $this->mOptions;
@@ -2566,6 +2575,10 @@ class User implements IDBAccessObject {
 			}
 		}
 
+		if ( $flags & self::GETOPTIONS_EXCLUDE_DEFAULTS ) {
+			$options = array_diff_assoc( $options, self::getDefaultOptions() );
+		}
+
 		return $options;
 	}
 
diff --git a/includes/resourceloader/ResourceLoaderUserDefaultsModule.php b/includes/resourceloader/ResourceLoaderUserDefaultsModule.php
new file mode 100644
index 0000000000..1249cf84d6
--- /dev/null
+++ b/includes/resourceloader/ResourceLoaderUserDefaultsModule.php
@@ -0,0 +1,58 @@
+<?php
+/**
+ * Resource loader module for default user preferences.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @author Ori Livneh
+ */
+
+/**
+ * Module for default user preferences.
+ */
+class ResourceLoaderUserDefaultsModule extends ResourceLoaderModule {
+
+	/* Protected Members */
+
+	protected $targets = array( 'desktop', 'mobile' );
+
+	/* Methods */
+
+	/**
+	 * @param ResourceLoaderContext $context
+	 * @return string Hash
+	 */
+	public function getModifiedHash( ResourceLoaderContext $context ) {
+		return md5( serialize( User::getDefaultOptions() ) );
+	}
+
+	/**
+	 * @param ResourceLoaderContext $context
+	 * @return array|int|mixed
+	 */
+	public function getModifiedTime( ResourceLoaderContext $context ) {
+		return $this->getHashMtime( $context );
+	}
+
+	/**
+	 * @param ResourceLoaderContext $context
+	 * @return string
+	 */
+	public function getScript( ResourceLoaderContext $context ) {
+		return Xml::encodeJsCall( 'mw.user.options.set', array( User::getDefaultOptions() ) );
+	}
+}
diff --git a/includes/resourceloader/ResourceLoaderUserOptionsModule.php b/includes/resourceloader/ResourceLoaderUserOptionsModule.php
index e6b07c1c09..a1847fb8c4 100644
--- a/includes/resourceloader/ResourceLoaderUserOptionsModule.php
+++ b/includes/resourceloader/ResourceLoaderUserOptionsModule.php
@@ -37,6 +37,13 @@ class ResourceLoaderUserOptionsModule extends ResourceLoaderModule {
 
 	/* Methods */
 
+	/**
+	 * @return array List of module names as strings
+	 */
+	public function getDependencies() {
+		return array( 'user.defaults' );
+	}
+
 	/**
 	 * @param ResourceLoaderContext $context
 	 * @return array|int|mixed
@@ -56,7 +63,7 @@ class ResourceLoaderUserOptionsModule extends ResourceLoaderModule {
 	 */
 	public function getScript( ResourceLoaderContext $context ) {
 		return Xml::encodeJsCall( 'mw.user.options.set',
-			array( $context->getUserObj()->getOptions() ),
+			array( $context->getUserObj()->getOptions( User::GETOPTIONS_EXCLUDE_DEFAULTS ) ),
 			ResourceLoader::inDebugMode()
 		);
 	}
diff --git a/resources/Resources.php b/resources/Resources.php
index d6a3181559..9c43987890 100644
--- a/resources/Resources.php
+++ b/resources/Resources.php
@@ -44,6 +44,7 @@ return array(
 	'user.cssprefs' => array( 'class' => 'ResourceLoaderUserCSSPrefsModule' ),
 
 	// Populate mediawiki.user placeholders with information about the current user
+	'user.defaults' => array( 'class' => 'ResourceLoaderUserDefaultsModule' ),
 	'user.options' => array( 'class' => 'ResourceLoaderUserOptionsModule' ),
 	'user.tokens' => array( 'class' => 'ResourceLoaderUserTokensModule' ),
 
-- 
2.20.1