init

src/y-websocket.js

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+/*
+Unlike stated in the LICENSE file, it is not necessary to include the copyright notice and permission notice when you copy code from this file.
+*/
+
+/**
+ * @module provider/websocket
+ */
+
+/* eslint-env browser */
+
+import * as Y from 'yjs'
+import * as bc from 'lib0/broadcastchannel.js'
+import * as encoding from 'lib0/encoding.js'
+import * as decoding from 'lib0/decoding.js'
+import * as syncProtocol from 'y-protocols/sync.js'
+import * as authProtocol from 'y-protocols/auth.js'
+import * as awarenessProtocol from 'y-protocols/awareness.js'
+import * as mutex from 'lib0/mutex.js'
+
+const messageSync = 0
+const messageAwareness = 1
+const messageAuth = 2
+
+const reconnectTimeout = 3000
+
+/**
+ * @param {WebsocketsSharedDocument} doc
+ * @param {string} reason
+ */
+const permissionDeniedHandler = (doc, reason) => console.warn(`Permission denied to access ${doc.url}.\n${reason}`)
+
+/**
+ * @param {WebsocketsSharedDocument} doc
+ * @param {ArrayBuffer} buf
+ * @return {encoding.Encoder}
+ */
+const readMessage = (doc, buf) => {
+  const decoder = decoding.createDecoder(buf)
+  const encoder = encoding.createEncoder()
+  const messageType = decoding.readVarUint(decoder)
+  switch (messageType) {
+    case messageSync:
+      encoding.writeVarUint(encoder, messageSync)
+      doc.mux(() =>
+        syncProtocol.readSyncMessage(decoder, encoder, doc)
+      )
+      break
+    case messageAwareness:
+      awarenessProtocol.readAwarenessMessage(decoder, doc)
+      break
+    case messageAuth:
+      authProtocol.readAuthMessage(decoder, doc, permissionDeniedHandler)
+  }
+  return encoder
+}
+
+const setupWS = (doc, url) => {
+  const websocket = new WebSocket(url)
+  websocket.binaryType = 'arraybuffer'
+  doc.ws = websocket
+  websocket.onmessage = event => {
+    const encoder = readMessage(doc, event.data)
+    if (encoding.length(encoder) > 1) {
+      websocket.send(encoding.toBuffer(encoder))
+    }
+  }
+  websocket.onclose = () => {
+    doc.ws = null
+    doc.wsconnected = false
+    // update awareness (all users left)
+    const removed = []
+    doc.getAwarenessInfo().forEach((_, userid) => {
+      removed.push(userid)
+    })
+    doc.awareness = new Map()
+    doc.emit('awareness', [{
+      added: [], updated: [], removed
+    }])
+    doc.emit('status', [{
+      status: 'disconnected'
+    }])
+    setTimeout(setupWS, reconnectTimeout, doc, url)
+  }
+  websocket.onopen = () => {
+    doc.wsconnected = true
+    doc.emit('status', [{
+      status: 'connected'
+    }])
+    // always send sync step 1 when connected
+    const encoder = encoding.createEncoder()
+    encoding.writeVarUint(encoder, messageSync)
+    syncProtocol.writeSyncStep1(encoder, doc)
+    websocket.send(encoding.toBuffer(encoder))
+    // force send stored awareness info
+    doc.setAwarenessField(null, null)
+  }
+}
+
+const broadcastUpdate = (y, transaction) => {
+  if (transaction.encodedStructsLen > 0) {
+    y.mux(() => {
+      const encoder = encoding.createEncoder()
+      encoding.writeVarUint(encoder, messageSync)
+      syncProtocol.writeUpdate(encoder, transaction.encodedStructsLen, transaction.encodedStructs)
+      const buf = encoding.toBuffer(encoder)
+      if (y.wsconnected) {
+        y.ws.send(buf)
+      }
+      bc.publish(y.url, buf)
+    })
+  }
+}
+
+class WebsocketsSharedDocument extends Y.Y {
+  constructor (url, opts) {
+    super(opts)
+    this.url = url
+    this.wsconnected = false
+    this.mux = mutex.createMutex()
+    this.ws = null
+    this._localAwarenessState = {}
+    this.awareness = new Map()
+    this.awarenessClock = new Map()
+    setupWS(this, url)
+    this.on('afterTransaction', broadcastUpdate)
+    this._bcSubscriber = data => {
+      const encoder = readMessage(this, data) // already muxed
+      this.mux(() => {
+        if (encoding.length(encoder) > 1) {
+          bc.publish(url, encoding.toBuffer(encoder))
+        }
+      })
+    }
+    bc.subscribe(url, this._bcSubscriber)
+    // send sync step1 to bc
+    this.mux(() => {
+      const encoder = encoding.createEncoder()
+      encoding.writeVarUint(encoder, messageSync)
+      syncProtocol.writeSyncStep1(encoder, this)
+      bc.publish(url, encoding.toBuffer(encoder))
+    })
+  }
+  getLocalAwarenessInfo () {
+    return this._localAwarenessState
+  }
+  getAwarenessInfo () {
+    return this.awareness
+  }
+  setAwarenessField (field, value) {
+    if (field !== null) {
+      this._localAwarenessState[field] = value
+    }
+    if (this.wsconnected) {
+      const clock = (this.awarenessClock.get(this.userID) || 0) + 1
+      this.awarenessClock.set(this.userID, clock)
+      const encoder = encoding.createEncoder()
+      encoding.writeVarUint(encoder, messageAwareness)
+      awarenessProtocol.writeUsersStateChange(encoder, [{ userID: this.userID, state: this._localAwarenessState, clock }])
+      const buf = encoding.toBuffer(encoder)
+      this.ws.send(buf)
+    }
+  }
+}
+
+/**
+ * Websocket Provider for Yjs. Creates a single websocket connection to each document.
+ * The document name is attached to the provided url. I.e. the following example
+ * creates a websocket connection to http://localhost:1234/my-document-name
+ *
+ * @example
+ *   import { WebsocketProvider } from 'yjs/provider/websocket/client.js'
+ *   const provider = new WebsocketProvider('http://localhost:1234')
+ *   const ydocument = provider.get('my-document-name')
+ */
+export class WebsocketProvider {
+  constructor (url) {
+    // ensure that url is always ends with /
+    while (url[url.length - 1] === '/') {
+      url = url.slice(0, url.length - 1)
+    }
+    this.url = url + '/'
+    /**
+     * @type {Map<string, WebsocketsSharedDocument>}
+     */
+    this.docs = new Map()
+  }
+  /**
+   * @param {string} name
+   * @return {WebsocketsSharedDocument}
+   */
+  get (name, opts) {
+    let doc = this.docs.get(name)
+    if (doc === undefined) {
+      doc = new WebsocketsSharedDocument(this.url + name, opts)
+    }
+    return doc
+  }
+}