From bd08b62c598cea900df875913ce9a64674ddddb6 Mon Sep 17 00:00:00 2001
From: Timo Tijhof <krinklemail@gmail.com>
Date: Fri, 23 Sep 2016 00:07:54 +0100
Subject: [PATCH] mw.loader: Use native Set where possible instead of string
 keys

Total time spent in sortDependencies
(Chrome Canary, unthrottled, MacBook Pro, MediaWiki-Vagrant)
* Before: 0.53ms
* After: 0.3ms

Bug: T146432
Change-Id: I65e2b0efbd080adab003b5c9605405ea0ae5380d
---
 resources/src/mediawiki/mediawiki.js | 60 ++++++++++++++--------------
 1 file changed, 30 insertions(+), 30 deletions(-)

diff --git a/resources/src/mediawiki/mediawiki.js b/resources/src/mediawiki/mediawiki.js
index 89bb83b99d..2c7343f81d 100644
--- a/resources/src/mediawiki/mediawiki.js
+++ b/resources/src/mediawiki/mediawiki.js
@@ -11,7 +11,7 @@
 ( function ( $ ) {
 	'use strict';
 
-	var mw,
+	var mw, StringSet,
 		hasOwn = Object.prototype.hasOwnProperty,
 		slice = Array.prototype.slice,
 		trackCallbacks = $.Callbacks( 'memory' ),
@@ -48,6 +48,23 @@
 		return hash;
 	}
 
+	StringSet = window.Set || ( function () {
+		/**
+		 * @private
+		 * @class
+		 */
+		function StringSet() {
+			this.set = {};
+		}
+		StringSet.prototype.add = function ( value ) {
+			this.set[ value ] = true;
+		};
+		StringSet.prototype.has = function ( value ) {
+			return this.set.hasOwnProperty( value );
+		};
+		return StringSet;
+	}() );
+
 	/**
 	 * Create an object that can be read from or written to from methods that allow
 	 * interaction both with single and multiple properties at once.
@@ -660,32 +677,16 @@
 			log.deprecate = !Object.defineProperty ? function ( obj, key, val ) {
 				obj[ key ] = val;
 			} : function ( obj, key, val, msg ) {
-				/*globals Set */
 				msg = 'Use of "' + key + '" is deprecated.' + ( msg ? ( ' ' + msg ) : '' );
-				var logged, loggedIsSet, uniqueTrace;
-				if ( window.Set ) {
-					logged = new Set();
-					loggedIsSet = true;
-				} else {
-					logged = {};
-					loggedIsSet = false;
-				}
-				uniqueTrace = function () {
+				var logged = new StringSet();
+				function uniqueTrace() {
 					var trace = new Error().stack;
-					if ( loggedIsSet ) {
-						if ( logged.has( trace ) ) {
-							return false;
-						}
-						logged.add( trace );
-						return true;
-					} else {
-						if ( logged.hasOwnProperty( trace ) ) {
-							return false;
-						}
-						logged[ trace ] = 1;
-						return true;
+					if ( logged.has( trace ) ) {
+						return false;
 					}
-				};
+					logged.add( trace );
+					return true;
+				}
 				Object.defineProperty( obj, key, {
 					configurable: true,
 					enumerable: true,
@@ -1106,8 +1107,8 @@
 			 *  dependencies, such that later modules depend on earlier modules. The array
 			 *  contains the module names. If the array contains already some module names,
 			 *  this function appends its result to the pre-existing array.
-			 * @param {Object} [unresolved] Hash used to track the current dependency
-			 *  chain; used to report loops in the dependency graph.
+			 * @param {StringSet} [unresolved] Used to track the current dependency
+			 *  chain, and to report loops in the dependency graph.
 			 * @throws {Error} If any unregistered module or a dependency loop is encountered
 			 */
 			function sortDependencies( module, resolved, unresolved ) {
@@ -1144,13 +1145,13 @@
 				}
 				// Create unresolved if not passed in
 				if ( !unresolved ) {
-					unresolved = {};
+					unresolved = new StringSet();
 				}
 				// Tracks down dependencies
 				deps = registry[ module ].dependencies;
 				for ( i = 0; i < deps.length; i++ ) {
 					if ( $.inArray( deps[ i ], resolved ) === -1 ) {
-						if ( unresolved[ deps[ i ] ] ) {
+						if ( unresolved.has( deps[ i ] ) ) {
 							throw new Error( mw.format(
 								'Circular reference detected: $1 -> $2',
 								module,
@@ -1158,8 +1159,7 @@
 							) );
 						}
 
-						// Add to unresolved
-						unresolved[ module ] = true;
+						unresolved.add(  module );
 						sortDependencies( deps[ i ], resolved, unresolved );
 					}
 				}
-- 
2.20.1