[HTML5] PWA service worker prefers cached version.

Use an offline first approach, where we prefer the cached version over
the network one.
This forces games using PWA to always re-export the project and not just
the PCK, so that the service worker version gets updated correctly, and
the end-user cache is correctly cleared on update.

misc/dist/html/service-worker.js

@@ -4,7 +4,8 @@
 // Incrementing CACHE_VERSION will kick off the install event and force
 // previously cached resources to be updated from the network.
 const CACHE_VERSION = "@GODOT_VERSION@";
-const CACHE_NAME = "@GODOT_NAME@-cache";
+const CACHE_PREFIX = "@GODOT_NAME@-sw-cache-";
+const CACHE_NAME = CACHE_PREFIX + CACHE_VERSION;
 const OFFLINE_URL = "@GODOT_OFFLINE_PAGE@";
 // Files that will be cached on load.
 const CACHED_FILES = @GODOT_CACHE@;
@@ -13,26 +14,35 @@ const CACHABLE_FILES = @GODOT_OPT_CACHE@;
 const FULL_CACHE = CACHED_FILES.concat(CACHABLE_FILES);
 
 self.addEventListener("install", (event) => {
-	event.waitUntil(async function () {
-		const cache = await caches.open(CACHE_NAME);
-		// Clear old cache (including optionals).
-		await Promise.all(FULL_CACHE.map(path => cache.delete(path)));
-		// Insert new one.
-		const done = await cache.addAll(CACHED_FILES);
-		return done;
-	}());
+	event.waitUntil(caches.open(CACHE_NAME).then(cache => cache.addAll(CACHED_FILES)));
 });
 
 self.addEventListener("activate", (event) => {
-	event.waitUntil(async function () {
-		if ("navigationPreload" in self.registration) {
-			await self.registration.navigationPreload.enable();
-		}
-	}());
-	// Tell the active service worker to take control of the page immediately.
-	self.clients.claim();
+	event.waitUntil(caches.keys().then(
+		function (keys) {
+			// Remove old caches.
+			return Promise.all(keys.filter(key => key.startsWith(CACHE_PREFIX) && key != CACHE_NAME).map(key => caches.delete(key)));
+		}).then(function() {
+			// Enable navigation preload if available.
+			return ("navigationPreload" in self.registration) ? self.registration.navigationPreload.enable() : Promise.resolve();
+		})
+	);
 });
 
+async function fetchAndCache(event, cache, isCachable) {
+	// Use the preloaded response, if it's there
+	let response = await event.preloadResponse;
+	if (!response) {
+		// Or, go over network.
+		response = await self.fetch(event.request);
+	}
+	if (isCachable) {
+		// And update the cache
+		cache.put(event.request, response.clone());
+	}
+	return response;
+}
+
 self.addEventListener("fetch", (event) => {
 	const isNavigate = event.request.mode === "navigate";
 	const url = event.request.url || "";
@@ -42,32 +52,54 @@ self.addEventListener("fetch", (event) => {
 	const isCachable = FULL_CACHE.some(v => v === local) || (base === referrer && base.endsWith(CACHED_FILES[0]));
 	if (isNavigate || isCachable) {
 		event.respondWith(async function () {
-			try {
-				// Use the preloaded response, if it's there
-				let request = event.request.clone();
-				let response = await event.preloadResponse;
-				if (!response) {
-					// Or, go over network.
-					response = await fetch(event.request);
-				}
-				if (isCachable) {
-					// Update the cache
-					const cache = await caches.open(CACHE_NAME);
-					cache.put(request, response.clone());
-				}
-				return response;
-			} catch (error) {
-				const cache = await caches.open(CACHE_NAME);
-				if (event.request.mode === "navigate") {
-					// Check if we have full cache.
-					const cached = await Promise.all(FULL_CACHE.map(name => cache.match(name)));
-					const missing = cached.some(v => v === undefined);
-					const cachedResponse = missing ? await caches.match(OFFLINE_URL) : await caches.match(CACHED_FILES[0]);
-					return cachedResponse;
+			// Try to use cache first
+			const cache = await caches.open(CACHE_NAME);
+			if (event.request.mode === "navigate") {
+				// Check if we have full cache during HTML page request.
+				const fullCache = await Promise.all(FULL_CACHE.map(name => cache.match(name)));
+				const missing = fullCache.some(v => v === undefined);
+				if (missing) {
+					try {
+						// Try network if some cached file is missing (so we can display offline page in case).
+						return await fetchAndCache(event, cache, isCachable);
+					} catch (e) {
+						// And return the hopefully always cached offline page in case of network failure.
+						console.error("Network error: ", e);
+						return await caches.match(OFFLINE_URL);
+					}
 				}
-				const cachedResponse = await caches.match(event.request);
-				return cachedResponse;
+			}
+			const cached = await cache.match(event.request);
+			if (cached) {
+				return cached;
+			} else {
+				// Try network if don't have it in cache.
+				return await fetchAndCache(event, cache, isCachable);
 			}
 		}());
 	}
 });
+
+self.addEventListener("message", (event) => {
+	// No cross origin
+	if (event.origin != self.origin) {
+		return;
+	}
+	const id = event.source.id || "";
+	const msg = event.data || "";
+	// Ensure it's one of our clients.
+	self.clients.get(id).then(function (client) {
+		if (!client) {
+			return; // Not a valid client.
+		}
+		if (msg === "claim") {
+			self.skipWaiting().then(() => self.clients.claim());
+		} else if (msg === "clear") {
+			caches.delete(CACHE_NAME);
+		} else if (msg === "update") {
+			self.skipWaiting().then(() => self.clients.claim()).then(() => self.clients.matchAll()).then(all => all.forEach(c => c.navigate(c.url)));
+		} else {
+			onClientMessage(event);
+		}
+	});
+});

platform/javascript/export/export_plugin.cpp

@@ -139,8 +139,7 @@ void EditorExportPlatformJavaScript::_fix_html(Vector<uint8_t> &p_html, const Re
 	}
 	if (p_preset->get("progressive_web_app/enabled")) {
 		head_include += "<link rel='manifest' href='" + p_name + ".manifest.json'>\n";
-		head_include += "<script type='application/javascript'>window.addEventListener('load', () => {if ('serviceWorker' in navigator) {navigator.serviceWorker.register('" +
-				p_name + ".service.worker.js');}});</script>\n";
+		config["serviceWorker"] = p_name + ".service.worker.js";
 	}
 
 	// Replaces HTML string
@@ -188,35 +187,46 @@ Error EditorExportPlatformJavaScript::_add_manifest_icon(const String &p_path, c
 }
 
 Error EditorExportPlatformJavaScript::_build_pwa(const Ref<EditorExportPreset> &p_preset, const String p_path, const Vector<SharedObject> &p_shared_objects) {
+	String proj_name = ProjectSettings::get_singleton()->get_setting("application/config/name");
+	if (proj_name.is_empty()) {
+		proj_name = "Godot Game";
+	}
+
 	// Service worker
 	const String dir = p_path.get_base_dir();
 	const String name = p_path.get_file().get_basename();
 	const ExportMode mode = (ExportMode)(int)p_preset->get("variant/export_type");
 	Map<String, String> replaces;
-	replaces["@GODOT_VERSION@"] = "1";
-	replaces["@GODOT_NAME@"] = name;
+	replaces["@GODOT_VERSION@"] = String::num_int64(OS::get_singleton()->get_unix_time()) + "|" + String::num_int64(OS::get_singleton()->get_ticks_usec());
+	replaces["@GODOT_NAME@"] = proj_name.substr(0, 16);
 	replaces["@GODOT_OFFLINE_PAGE@"] = name + ".offline.html";
-	Array files;
-	replaces["@GODOT_OPT_CACHE@"] = Variant(files).to_json_string();
-	files.push_back(name + ".html");
-	files.push_back(name + ".js");
-	files.push_back(name + ".wasm");
-	files.push_back(name + ".pck");
-	files.push_back(name + ".offline.html");
+
+	// Files cached during worker install.
+	Array cache_files;
+	cache_files.push_back(name + ".html");
+	cache_files.push_back(name + ".js");
+	cache_files.push_back(name + ".offline.html");
 	if (p_preset->get("html/export_icon")) {
-		files.push_back(name + ".icon.png");
-		files.push_back(name + ".apple-touch-icon.png");
+		cache_files.push_back(name + ".icon.png");
+		cache_files.push_back(name + ".apple-touch-icon.png");
 	}
 	if (mode == EXPORT_MODE_THREADS) {
-		files.push_back(name + ".worker.js");
-		files.push_back(name + ".audio.worklet.js");
-	} else if (mode == EXPORT_MODE_GDNATIVE) {
-		files.push_back(name + ".side.wasm");
+		cache_files.push_back(name + ".worker.js");
+		cache_files.push_back(name + ".audio.worklet.js");
+	}
+	replaces["@GODOT_CACHE@"] = Variant(cache_files).to_json_string();
+
+	// Heavy files that are cached on demand.
+	Array opt_cache_files;
+	opt_cache_files.push_back(name + ".wasm");
+	opt_cache_files.push_back(name + ".pck");
+	if (mode == EXPORT_MODE_GDNATIVE) {
+		opt_cache_files.push_back(name + ".side.wasm");
 		for (int i = 0; i < p_shared_objects.size(); i++) {
-			files.push_back(p_shared_objects[i].path.get_file());
+			opt_cache_files.push_back(p_shared_objects[i].path.get_file());
 		}
 	}
-	replaces["@GODOT_CACHE@"] = Variant(files).to_json_string();
+	replaces["@GODOT_OPT_CACHE@"] = Variant(opt_cache_files).to_json_string();
 
 	const String sw_path = dir.plus_file(name + ".service.worker.js");
 	Vector<uint8_t> sw;
@@ -256,10 +266,6 @@ Error EditorExportPlatformJavaScript::_build_pwa(const Ref<EditorExportPreset> &
 	const int orientation = CLAMP(int(p_preset->get("progressive_web_app/orientation")), 0, 3);
 
 	Dictionary manifest;
-	String proj_name = ProjectSettings::get_singleton()->get_setting("application/config/name");
-	if (proj_name.is_empty()) {
-		proj_name = "Godot Game";
-	}
 	manifest["name"] = proj_name;
 	manifest["start_url"] = "./" + name + ".html";
 	manifest["display"] = String::utf8(modes[display]);

platform/javascript/js/engine/config.js

@@ -106,6 +106,13 @@ const InternalConfig = function (initConfig) { // eslint-disable-line no-unused-
 		 * @default
 		 */
 		experimentalVK: false,
+		/**
+		 * The progressive web app service worker to install.
+		 * @memberof EngineConfig
+		 * @default
+		 * @type {string}
+		 */
+		serviceWorker: '',
 		/**
 		 * @ignore
 		 * @type {Array.<string>}
@@ -249,6 +256,7 @@ const InternalConfig = function (initConfig) { // eslint-disable-line no-unused-
 		this.persistentDrops = parse('persistentDrops', this.persistentDrops);
 		this.experimentalVK = parse('experimentalVK', this.experimentalVK);
 		this.focusCanvas = parse('focusCanvas', this.focusCanvas);
+		this.serviceWorker = parse('serviceWorker', this.serviceWorker);
 		this.gdnativeLibs = parse('gdnativeLibs', this.gdnativeLibs);
 		this.fileSizes = parse('fileSizes', this.fileSizes);
 		this.args = parse('args', this.args);

platform/javascript/js/engine/engine.js

@@ -189,6 +189,9 @@ const Engine = (function () {
 							preloader.preloadedFiles.length = 0; // Clear memory
 							me.rtenv['callMain'](me.config.args);
 							initPromise = null;
+							if (me.config.serviceWorker && 'serviceWorker' in navigator) {
+								navigator.serviceWorker.register(me.config.serviceWorker);
+							}
 							resolve();
 						});
 					});