From ec55299c8b2c8e0fd5bb3004406b71d3fdc1178e Mon Sep 17 00:00:00 2001
From: Tom Moor <tom.moor@gmail.com>
Date: Thu, 20 Aug 2020 20:37:54 -0700
Subject: [PATCH] fix: Improve websocket reliability (#1470)

* check connection on page visibility change

* fix: SocketPresence account for socket changing
---
 app/components/SocketProvider.js              | 40 ++++++++++++++-----
 .../Document/components/SocketPresence.js     |  2 +-
 app/utils/pageVisibility.js                   | 25 ++++++++++++
 3 files changed, 56 insertions(+), 11 deletions(-)
 create mode 100644 app/utils/pageVisibility.js

diff --git a/app/components/SocketProvider.js b/app/components/SocketProvider.js
index 3538a7da7..373617628 100644
--- a/app/components/SocketProvider.js
+++ b/app/components/SocketProvider.js
@@ -3,7 +3,7 @@ import { find } from "lodash";
 import { observable } from "mobx";
 import { inject, observer } from "mobx-react";
 import * as React from "react";
-import io from "socket.io-client";
+import io, { Socket } from "socket.io-client";
 import AuthStore from "stores/AuthStore";
 import CollectionsStore from "stores/CollectionsStore";
 import DocumentPresenceStore from "stores/DocumentPresenceStore";
@@ -13,6 +13,7 @@ import MembershipsStore from "stores/MembershipsStore";
 import PoliciesStore from "stores/PoliciesStore";
 import UiStore from "stores/UiStore";
 import ViewsStore from "stores/ViewsStore";
+import { getVisibilityListener, getPageVisible } from "utils/pageVisibility";
 
 export const SocketContext: any = React.createContext();
 
@@ -31,9 +32,35 @@ type Props = {
 
 @observer
 class SocketProvider extends React.Component<Props> {
-  @observable socket;
+  @observable socket: Socket;
 
   componentDidMount() {
+    this.createConnection();
+
+    document.addEventListener(getVisibilityListener(), this.checkConnection);
+  }
+
+  componentWillUnmount() {
+    if (this.socket) {
+      this.socket.authenticated = false;
+      this.socket.disconnect();
+    }
+
+    document.removeEventListener(getVisibilityListener(), this.checkConnection);
+  }
+
+  checkConnection = () => {
+    if (this.socket && this.socket.disconnected && getPageVisible()) {
+      // null-ifying this reference is important, do not remove. Without it
+      // references to old sockets are potentially held in context
+      this.socket.close();
+      this.socket = null;
+
+      this.createConnection();
+    }
+  };
+
+  createConnection = () => {
     this.socket = io(window.location.origin, {
       path: "/realtime",
       transports: ["websocket"],
@@ -264,14 +291,7 @@ class SocketProvider extends React.Component<Props> {
     this.socket.on("user.presence", (event) => {
       presence.touch(event.documentId, event.userId, event.isEditing);
     });
-  }
-
-  componentWillUnmount() {
-    if (this.socket) {
-      this.socket.disconnect();
-      this.socket.authenticated = false;
-    }
-  }
+  };
 
   render() {
     return (
diff --git a/app/scenes/Document/components/SocketPresence.js b/app/scenes/Document/components/SocketPresence.js
index fe077cb30..d919e26be 100644
--- a/app/scenes/Document/components/SocketPresence.js
+++ b/app/scenes/Document/components/SocketPresence.js
@@ -41,7 +41,7 @@ export default class SocketPresence extends React.Component<Props> {
   }
 
   setupOnce = () => {
-    if (this.context && !this.previousContext) {
+    if (this.context && this.context !== this.previousContext) {
       this.previousContext = this.context;
 
       if (this.context.authenticated) {
diff --git a/app/utils/pageVisibility.js b/app/utils/pageVisibility.js
new file mode 100644
index 000000000..512b3eb38
--- /dev/null
+++ b/app/utils/pageVisibility.js
@@ -0,0 +1,25 @@
+// @flow
+let hidden = "hidden";
+let visibilityChange = "visibilitychange";
+
+if ("hidden" in document) {
+  hidden = "hidden";
+  visibilityChange = "visibilitychange";
+} else if ("mozHidden" in document) {
+  // Firefox up to v17
+  hidden = "mozHidden";
+  visibilityChange = "mozvisibilitychange";
+} else if ("webkitHidden" in document) {
+  // Chrome up to v32, Android up to v4.4, Blackberry up to v10
+  hidden = "webkitHidden";
+  visibilityChange = "webkitvisibilitychange";
+}
+
+export function getVisibilityListener(): string {
+  return visibilityChange;
+}
+
+export function getPageVisible(): boolean {
+  // $FlowFixMe
+  return !document[hidden];
+}