analytics/webcontent/bi/js/dashboard-analytics/features/dashboard/metadata/MetadataLoader.js

'use strict';

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

/**
 * Licensed Materials - Property of IBM
 * IBM Cognos Products: BI Cloud (C) Copyright IBM Corp. 2019
 * US Government Users Restricted Rights - Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp.
 */
define(['../../../lib/@waca/dashboard-common/dist/core/APIFactory'], function (APIFactory) {
	'use strict';

	var MetadataLoader = function () {

		/*
  	The MetadataLoader will improve performance by starting to load metadata as soon as possible in the dashboard life cycle
  	The feature will also prevent hogging all network connections by leveraging a queue which only allows up to 3 metadata requests at once
  */

		function MetadataLoader(options) {
			_classCallCheck(this, MetadataLoader);

			this.options = options;
			this.API = options.features.API;
		}

		MetadataLoader.prototype.initialize = function initialize() {
			var dataSources = this.API.getFeature('DataSources').getDataSourceList();
			this.loadMetadata(dataSources);
		};

		MetadataLoader.prototype.getAPI = function getAPI() {
			return APIFactory.createAPI(this, []);
		};

		MetadataLoader.prototype.loadMetadata = function loadMetadata(dataSources) {
			var loaderPromises = [];
			dataSources.forEach(function (dataSource) {
				return loaderPromises.push(dataSource.loadMetadata);
			});
			var MAX_WORKERS = 3; //Avoid hogging all network connections by only allowing up to 3 concurrent metadata requests

			var promiseResults = [];
			var workerCount = 0;
			var promiseIdx = 0;
			return new Promise(function (done) {
				var getNextLoaderPromise = function getNextLoaderPromise() {
					if (workerCount < MAX_WORKERS && promiseIdx < loaderPromises.length) {
						loaderPromises[promiseIdx]().then(onSettlePromise).fail(onSettlePromise);
						promiseIdx++;
						workerCount++;
						getNextLoaderPromise();
					} else if (workerCount === 0 && promiseIdx === loaderPromises.length) {
						done(promiseResults);
					}
				};

				var onSettlePromise = function onSettlePromise(result) {
					promiseResults.push(result);
					workerCount--;
					getNextLoaderPromise();
				};

				getNextLoaderPromise();
			});
		};

		return MetadataLoader;
	}();

	return MetadataLoader;
});
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