import {shortTopicUrl, topicUrlWs, topicUrlWsWithSince} from "./utils"; const retryBackoffSeconds = [5, 10, 15, 20, 30, 45]; class Connection { constructor(subscriptionId, baseUrl, topic, since, onNotification) { this.subscriptionId = subscriptionId; this.baseUrl = baseUrl; this.topic = topic; this.since = since; this.shortUrl = shortTopicUrl(baseUrl, topic); this.onNotification = onNotification; this.ws = null; this.retryCount = 0; this.retryTimeout = null; } start() { // Don't fetch old messages; we do that as a poll() when adding a subscription; // we don't want to re-trigger the main view re-render potentially hundreds of times. const wsUrl = (this.since === 0) ? topicUrlWs(this.baseUrl, this.topic) : topicUrlWsWithSince(this.baseUrl, this.topic, this.since.toString()); console.log(`[Connection, ${this.shortUrl}] Opening connection to ${wsUrl}`); this.ws = new WebSocket(wsUrl); this.ws.onopen = (event) => { console.log(`[Connection, ${this.shortUrl}] Connection established`, event); this.retryCount = 0; } this.ws.onmessage = (event) => { console.log(`[Connection, ${this.shortUrl}] Message received from server: ${event.data}`); try { const data = JSON.parse(event.data); const relevantAndValid = data.event === 'message' && 'id' in data && 'time' in data && 'message' in data; if (!relevantAndValid) { console.log(`[Connection, ${this.shortUrl}] Message irrelevant or invalid. Ignoring.`); return; } this.since = data.time + 1; // Sigh. This works because on reconnect, we wait 5+ seconds anyway. this.onNotification(this.subscriptionId, data); } catch (e) { console.log(`[Connection, ${this.shortUrl}] Error handling message: ${e}`); } }; this.ws.onclose = (event) => { if (event.wasClean) { console.log(`[Connection, ${this.shortUrl}] Connection closed cleanly, code=${event.code} reason=${event.reason}`); this.ws = null; } else { const retrySeconds = retryBackoffSeconds[Math.min(this.retryCount, retryBackoffSeconds.length-1)]; this.retryCount++; console.log(`[Connection, ${this.shortUrl}] Connection died, retrying in ${retrySeconds} seconds`); this.retryTimeout = setTimeout(() => this.start(), retrySeconds * 1000); } }; this.ws.onerror = (event) => { console.log(`[Connection, ${this.shortUrl}] Error occurred: ${event}`, event); }; } close() { console.log(`[Connection, ${this.shortUrl}] Closing connection`); const socket = this.ws; const retryTimeout = this.retryTimeout; if (socket !== null) { socket.close(); } if (retryTimeout !== null) { clearTimeout(retryTimeout); } this.retryTimeout = null; this.ws = null; } } export default Connection;