Merge "Enable module storage for 0.05% of visitors w/storage-capable browsers"

diff --git a/resources/mediawiki/mediawiki.js b/resources/mediawiki/mediawiki.js
index 328ba83..8a8215d 100644 (file)
--- a/resources/mediawiki/mediawiki.js
+++ b/resources/mediawiki/mediawiki.js
@@ -1749,6 +1749,38 @@ var mw = ( function ( $, undefined ) {
                                        // Cache hit stats
                                        stats: { hits: 0, misses: 0, expired: 0 },
 
+                                       // Experiment data
+                                       experiment: ( function () {
+                                               var start = ( new Date() ).getTime(), id = 0, seed = 0;
+
+                                               try {
+                                                       id = JSON.parse( localStorage.getItem( 'moduleStorageExperiment' ) );
+                                                       if ( typeof id !== 'number' ) {
+                                                               id = Math.floor( Math.random() * Math.random() * 1e16 );
+                                                               localStorage.setItem( 'moduleStorageExperiment', id );
+                                                       }
+                                                       seed = id % 2000;
+                                               } catch ( e ) {}
+
+                                               return {
+                                                       // Unique identifier for this browser. This allows us to group all
+                                                       // datapoints generated by a particular browser, which in turn allows us
+                                                       // to see how the initial load compares to subsequent page loads.
+                                                       id: id,
+
+                                                       // Group assignment may be 0 (not in experiment), 1 (control group), or 2
+                                                       // (experimental group). Browsers that don't implement all the prerequisite APIs
+                                                       // (JSON and Web Storage) are ineligible. Eligible browsers have a 0.1% chance
+                                                       // of being included in the experiment, in which case they are equally likely to
+                                                       // be assigned to either the experimental or control group.
+                                                       group: seed === 1 ? 1 : ( seed === 2 ? 2 : 0 ),
+
+                                                       // Assess module storage performance by measuring the time between this
+                                                       // reference point and the window load event.
+                                                       start: start
+                                               };
+                                       }() ),
+
                                        /**
                                         * Construct a JSON-serializable object representing the content of the store.
                                         * @return {Object} Module store contents.
@@ -1799,20 +1831,19 @@ var mw = ( function ( $, undefined ) {
                                         * code for a full account of why we need a try / catch: <http://git.io/4NEwKg>.
                                         */
                                        init: function () {
-                                               var raw, data, optedIn;
+                                               var raw, data;
 
                                                if ( mw.loader.store.enabled !== null ) {
                                                        // #init already ran.
                                                        return;
                                                }
 
-                                               // Temporarily allow users to opt-in during mw.loader.store test phase by
-                                               // manually setting a cookie (bug 56397).
-                                               optedIn = /ResourceLoaderStorageEnabled=1/.test( document.cookie );
-
-                                               if ( !( mw.config.get( 'wgResourceLoaderStorageEnabled' ) || optedIn ) || mw.config.get( 'debug' ) ) {
-                                                       // Disabled by configuration, or because debug mode is set.
-                                                       mw.loader.store.enabled = false;
+                                               if (
+                                                       // We're in debug mode
+                                                       mw.config.get( 'debug' ) ||
+                                                       // Module storage is neither enabled by default, nor enabled for this user's group.
+                                                       !( mw.config.get( 'wgResourceLoaderStorageEnabled' ) || mw.loader.store.experiment.group === 2 )
+                                               ) {
                                                        return;
                                                }