base websocket

lib/src/external/websocket/websocket.dart

@@ -0,0 +1,155 @@
+/* eslint-env browser */
+
+/**
+ * Tiny websocket connection handler.
+ *
+ * Implements exponential backoff reconnects, ping/pong, and a nice event system using [lib0/observable].
+ *
+ * @module websocket
+ */
+
+import { Observable } from './observable.js'
+import * as time from './time.js'
+import * as math from './math.js'
+
+const reconnectTimeoutBase = 1200
+const maxReconnectTimeout = 2500
+// @todo - this should depend on awareness.outdatedTime
+const messageReconnectTimeout = 30000
+
+/**
+ * @param {WebsocketClient} wsclient
+ */
+const setupWS = (wsclient) => {
+  if (wsclient.shouldConnect && wsclient.ws === null) {
+    const websocket = new WebSocket(wsclient.url)
+    const binaryType = wsclient.binaryType
+    /**
+     * @type {any}
+     */
+    let pingTimeout = null
+    if (binaryType) {
+      websocket.binaryType = binaryType
+    }
+    wsclient.ws = websocket
+    wsclient.connecting = true
+    wsclient.connected = false
+    websocket.onmessage = event => {
+      wsclient.lastMessageReceived = time.getUnixTime()
+      const data = event.data
+      const message = typeof data === 'string' ? JSON.parse(data) : data
+      if (message && message.type === 'pong') {
+        clearTimeout(pingTimeout)
+        pingTimeout = setTimeout(sendPing, messageReconnectTimeout / 2)
+      }
+      wsclient.emit('message', [message, wsclient])
+    }
+    /**
+     * @param {any} error
+     */
+    const onclose = error => {
+      if (wsclient.ws !== null) {
+        wsclient.ws = null
+        wsclient.connecting = false
+        if (wsclient.connected) {
+          wsclient.connected = false
+          wsclient.emit('disconnect', [{ type: 'disconnect', error }, wsclient])
+        } else {
+          wsclient.unsuccessfulReconnects++
+        }
+        // Start with no reconnect timeout and increase timeout by
+        // log10(wsUnsuccessfulReconnects).
+        // The idea is to increase reconnect timeout slowly and have no reconnect
+        // timeout at the beginning (log(1) = 0)
+        setTimeout(setupWS, math.min(math.log10(wsclient.unsuccessfulReconnects + 1) * reconnectTimeoutBase, maxReconnectTimeout), wsclient)
+      }
+      clearTimeout(pingTimeout)
+    }
+    const sendPing = () => {
+      if (wsclient.ws === websocket) {
+        wsclient.send({
+          type: 'ping'
+        })
+      }
+    }
+    websocket.onclose = () => onclose(null)
+    websocket.onerror = error => onclose(error)
+    websocket.onopen = () => {
+      wsclient.lastMessageReceived = time.getUnixTime()
+      wsclient.connecting = false
+      wsclient.connected = true
+      wsclient.unsuccessfulReconnects = 0
+      wsclient.emit('connect', [{ type: 'connect' }, wsclient])
+      // set ping
+      pingTimeout = setTimeout(sendPing, messageReconnectTimeout / 2)
+    }
+  }
+}
+
+/**
+ * @extends Observable<string>
+ */
+export class WebsocketClient extends Observable {
+  /**
+   * @param {string} url
+   * @param {object} [opts]
+   * @param {'arraybuffer' | 'blob' | null} [opts.binaryType] Set `ws.binaryType`
+   */
+  constructor (url, { binaryType } = {}) {
+    super()
+    this.url = url
+    /**
+     * @type {WebSocket?}
+     */
+    this.ws = null
+    this.binaryType = binaryType || null
+    this.connected = false
+    this.connecting = false
+    this.unsuccessfulReconnects = 0
+    this.lastMessageReceived = 0
+    /**
+     * Whether to connect to other peers or not
+     * @type {boolean}
+     */
+    this.shouldConnect = true
+    this._checkInterval = setInterval(() => {
+      if (this.connected && messageReconnectTimeout < time.getUnixTime() - this.lastMessageReceived) {
+        // no message received in a long time - not even your own awareness
+        // updates (which are updated every 15 seconds)
+        /** @type {WebSocket} */ (this.ws).close()
+      }
+    }, messageReconnectTimeout / 2)
+    setupWS(this)
+  }
+
+  /**
+   * @param {any} message
+   */
+  send (message) {
+    if (this.ws) {
+      this.ws.send(JSON.stringify(message))
+    }
+  }
+
+  destroy () {
+    clearInterval(this._checkInterval)
+    this.disconnect()
+    super.destroy()
+  }
+
+  disconnect () {
+    this.shouldConnect = false
+    if (this.ws !== null) {
+      this.ws.close()
+    }
+  }
+
+  connect () {
+    this.shouldConnect = true
+    if (!this.connected && this.ws === null) {
+      setupWS(this)
+    }
+  }
+}
+
+// commit: 34444947ddbeca45d93e1420b0b9dc06440919e7