Refresh service workers when new versions of sw.js come in

- Check once a minute
- When a new sw is here, skip waiting around for the old ones to die and claim the clients

NB: On Chrome, this results in a 2 minute wait with lost connectivity before logout. Refresh to
immediately use the new sw.

NBB: On Firefox, this automatically logs you out without needing to refresh.

src/vector/app.js

@@ -176,7 +176,28 @@ export async function loadApp() {
         window.addEventListener('load', ()=>{
             navigator.serviceWorker.register(window.vector_dendrite_worker_script, { scope: "/" }).then(function(registration) {
                 // Registration was successful
-                console.log('ServiceWorker registration successful with scope: ', registration.scope)
+                console.log('ServiceWorker sw.js registration successful with scope: ', registration.scope);
+                /* const currWorker = registration.active;
+                currWorker.addEventListener('statechange', () => {
+                    console.log("Current sw.js state: ", currWorker.state)
+                }); */
+
+                registration.addEventListener('updatefound', () => {
+                    console.log("New dendrite sw.js found!")
+                    const newWorker = registration.installing;
+                    if (!newWorker) {
+                        return;
+                    }
+                    newWorker.addEventListener('statechange', () => {
+                        console.log("New sw.js state: ", newWorker.state)
+                    });
+                })
+
+                console.log("sw.js listening for new updates...");
+                // periodically check for updates
+                setInterval(function() {
+                    registration.update();
+                }, 1000 * 60) // once a minute
             }, (err)=>{
                 // registration failed :(
                 console.log('ServiceWorker registration failed: ', err)

src/vector/dendrite-sw.js

@@ -16,16 +16,21 @@
 
 const bundle_path = self.location.href.replace("/dendrite_sw.js", "")
 
+const version = "0.0.2"
+
 self.importScripts(`${bundle_path}/wasm_exec.js`,
                    `${bundle_path}/go_http_bridge.js`,
                    `${bundle_path}/sqlite_bridge.js`)
 
 self.addEventListener('install', function(event) {
-    console.log("installing SW")
+    console.log(`dendrite-sw.js: v${version} SW install`)
+    // Tell the browser to kill old sw's running in other tabs and replace them with this one
+    // This may cause spontaneous logouts.
+    self.skipWaiting();
 })
 
 self.addEventListener('activate', function(event) {
-    console.log("SW activated")
+    console.log(`dendrite-sw.js: v${version} SW activate`)
     global.process = {
         pid: 1,
         env: {
@@ -44,11 +49,13 @@ self.addEventListener('activate', function(event) {
 
     event.waitUntil(
         sqlite_bridge.init(config).then(()=>{
+            console.log(`dendrite-sw.js: v${version} starting dendrite.wasm...`)
             const go = new Go()
             WebAssembly.instantiateStreaming(fetch(`${bundle_path}/../../dendrite.wasm`), go.importObject).then((result) => {
                 go.run(result.instance)
                 // make fetch calls go through this sw - notably if a page registers a sw, it does NOT go through any sw by default
                 // unless you refresh or call this function.
+                console.log(`dendrite-sw.js: v${version} claiming open browser tabs`)
                 self.clients.claim()
             });
         })
@@ -57,16 +64,27 @@ self.addEventListener('activate', function(event) {
 
 
 self.addEventListener('fetch', function(event) {
+    event.respondWith((async () => {
+        // If this is a page refresh for the current page, then shunt in the new sw
+        // https://github.com/w3c/ServiceWorker/issues/1238
+        if (event.request.mode === "navigate" && event.request.method === "GET" && registration.waiting && (await clients.matchAll()).length < 2) {
+            console.log("Forcing new sw.js into page")
+            registration.waiting.postMessage('skipWaiting');
+            return new Response("", {headers: {"Refresh": "0"}});
+        }
+
         if (event.request.url.match(/\/_matrix\/client/)) {
             if (global.fetchListener) {
-            console.log("Forwarding " + event.request.url);
-            event.respondWith(global.fetchListener.onFetch(event));
+                console.log(`dendrite-sw.js: v${version} Forwarding ${event.request.url}`);
+                const response = await global.fetchListener.onFetch(event);
+                return response;
             }
             else {
-            console.log("no fetch listener present for " + event.request.url);
+                console.log(`dendrite-sw.js: v${version} no fetch listener present for ${event.request.url}`);
             }
         }
         else {
             return fetch(event.request);
         }
+    })());
 })