import Service, { inject as service } from '@ember/service'; import MultiMap from 'mnemonist/multi-map'; // TODO: Expose sizes of things via env vars // caches cursors and previous events when the EventSources are destroyed let cache; // keeps a record of currently in use EventSources let sources; // keeps a count of currently in use EventSources let usage; export default Service.extend({ dom: service('dom'), consul: service('data-source/protocols/http'), settings: service('data-source/protocols/local-storage'), init: function() { this._super(...arguments); cache = new Map(); sources = new Map(); usage = new MultiMap(Set); this._listeners = this.dom.listeners(); }, willDestroy: function() { this._listeners.remove(); Object.entries(sources || {}).forEach(function([key, item]) { item.close(); }); cache = null; sources = null; usage = null; }, open: function(uri, ref) { let source; // Check the cache for an EventSource that is already being used // for this uri. If we don't have one, set one up. if (uri.indexOf('://') === -1) { uri = `consul://${uri}`; } if (!sources.has(uri)) { let [providerName, pathname] = uri.split('://'); const provider = this[providerName]; let configuration = {}; if (cache.has(uri)) { configuration = cache.get(uri); } source = provider.source(pathname, configuration); this._listeners.add(source, { close: e => { const source = e.target; source.removeEventListener('close', close); cache.set(uri, { currentEvent: source.getCurrentEvent(), cursor: source.configuration.cursor, }); // the data is cached delete the EventSource sources.delete(uri); }, }); sources.set(uri, source); } else { source = sources.get(uri); } // set/increase the usage counter usage.set(source, ref); source.open(); return source; }, close: function(source, ref) { if (source) { // decrease the usage counter usage.remove(source, ref); // if the EventSource is no longer being used // close it (data caching is dealt with by the above 'close' event listener) if (!usage.has(source)) { source.close(); } } }, });