--- /dev/null
+/* jshint bitwise:false */
+( function ( mw, $ ) {
+
+ var CONTROL_BUCKET = 'control',
+ MAX_INT32_UNSIGNED = 4294967295;
+
+ /**
+ * An implementation of Jenkins' one-at-a-time hash.
+ *
+ * @see http://en.wikipedia.org/wiki/Jenkins_hash_function
+ *
+ * @param {String} string String to hash
+ * @return {Number} The hash as a 32-bit unsigned integer
+ * @ignore
+ *
+ * @author Ori Livneh <ori@wikimedia.org>
+ * @see http://jsbin.com/kejewi/4/watch?js,console
+ */
+ function hashString( string ) {
+ var hash = 0,
+ i = string.length;
+
+ while ( i-- ) {
+ hash += string.charCodeAt( i );
+ hash += ( hash << 10 );
+ hash ^= ( hash >> 6 );
+ }
+ hash += ( hash << 3 );
+ hash ^= ( hash >> 11 );
+ hash += ( hash << 15 );
+
+ return hash >>> 0;
+ }
+
+ /**
+ * Provides an API for bucketing users in experiments.
+ *
+ * @class mw.experiments
+ * @singleton
+ */
+ mw.experiments = {
+
+ /**
+ * Gets the bucket for the experiment given the token.
+ *
+ * The name of the experiment and the token are hashed. The hash is converted
+ * to a number which is then used to get a bucket.
+ *
+ * Consider the following experiment specification:
+ *
+ * ```
+ * {
+ * name: 'My first experiment',
+ * enabled: true,
+ * buckets: {
+ * control: 0.5
+ * A: 0.25,
+ * B: 0.25
+ * }
+ * }
+ * ```
+ *
+ * The experiment has three buckets: control, A, and B. The user has a 50%
+ * chance of being assigned to the control bucket, and a 25% chance of being
+ * assigned to either the A or B buckets. If the experiment were disabled,
+ * then the user would always be assigned to the control bucket.
+ *
+ * This function is based on the deprecated `mw.user.bucket` function.
+ *
+ * @param {Object} experiment
+ * @param {String} experiment.name The name of the experiment
+ * @param {Boolean} experiment.enabled Whether or not the experiment is
+ * enabled. If the experiment is disabled, then the user is always assigned
+ * to the control bucket
+ * @param {Object} experiment.buckets A map of bucket name to probability
+ * that the user will be assigned to that bucket
+ * @param {String} token A token that uniquely identifies the user for the
+ * duration of the experiment
+ * @returns {String} The bucket
+ */
+ getBucket: function ( experiment, token ) {
+ var buckets = experiment.buckets,
+ key,
+ range = 0,
+ hash,
+ max,
+ acc = 0;
+
+ if ( !experiment.enabled || $.isEmptyObject( experiment.buckets ) ) {
+ return CONTROL_BUCKET;
+ }
+
+ for ( key in buckets ) {
+ range += buckets[key];
+ }
+
+ hash = hashString( experiment.name + ':' + token );
+ max = ( hash / MAX_INT32_UNSIGNED ) * range;
+
+ for ( key in buckets ) {
+ acc += buckets[key];
+
+ if ( max <= acc ) {
+ return key;
+ }
+ }
+ }
+ };
+
+}( mediaWiki, jQuery ) );
--- /dev/null
+( function ( mw ) {
+
+ var getBucket = mw.experiments.getBucket;
+
+ function createExperiment() {
+ return {
+ name: 'experiment',
+ enabled: true,
+ buckets: {
+ control: 0.25,
+ A: 0.25,
+ B: 0.25,
+ C: 0.25
+ }
+ };
+ }
+
+ QUnit.module( 'mediawiki.experiments' );
+
+ QUnit.test( 'getBucket( experiment, token )', 4, function ( assert ) {
+ var experiment = createExperiment(),
+ token = '123457890';
+
+ assert.equal(
+ getBucket( experiment, token ),
+ getBucket( experiment, token ),
+ 'It returns the same bucket for the same experiment-token pair.'
+ );
+
+ // --------
+ experiment = createExperiment();
+ experiment.buckets = {
+ A: 0.314159265359
+ };
+
+ assert.equal(
+ 'A',
+ getBucket( experiment, token ),
+ 'It returns the bucket if only one is defined.'
+ );
+
+ // --------
+ experiment = createExperiment();
+ experiment.enabled = false;
+
+ assert.equal(
+ 'control',
+ getBucket( experiment, token ),
+ 'It returns "control" if the experiment is disabled.'
+ );
+
+ // --------
+ experiment = createExperiment();
+ experiment.buckets = {};
+
+ assert.equal(
+ 'control',
+ getBucket( experiment, token ),
+ 'It returns "control" if the experiment doesn\'t have any buckets.'
+ );
+ } );
+
+}( mediaWiki ) );
dépôts / lhc / web / wiklou.git / commitdiff