perf(pwa): ⚡ add in memory storage to reduce fs and network access

src/serviceworker/mod.ts

@@ -8,20 +8,37 @@ import type { JsonValue } from '$std/json/common.ts'
 // Force load service worker types
 const self = globalThis as unknown as ServiceWorkerGlobalScope
 
+// global RAM cache
+const memory = new Map()
+
 // Pseudo storage API for SW
 const swStorage = {
+	__memory: new Map<string, JsonValue | null>(),
 	async getItem<T extends JsonValue>(key: string): Promise<T | null> {
+		// RAM cache
+		if (this.__memory.has(key)) {
+			return this.__memory.get(key) as T
+		}
+
+		// FS cache
 		const cache = await caches.open('$SW_STORAGE')
 		const request = new Request(`http://null/${encodeURIComponent(key)}`)
 		const response = await cache.match(request)
 
 		if (response !== undefined) {
-			return response.json()
+			const item = await response.json()
+			this.__memory.set(key, item)
+			return item
 		}
 
+		this.__memory.set(key, null)
 		return null
 	},
 	async setItem<T extends JsonValue>(key: string, item: T): Promise<void> {
+		// RAM cache
+		this.__memory.set(key, item)
+
+		// FS Cache
 		const cache = await caches.open('$SW_STORAGE')
 		const request = new Request(`http://null/${encodeURIComponent(key)}`)
 		const response = Response.json(item)
@@ -42,12 +59,22 @@ async function getPreCachedUrls(): Promise<string[]> {
 
 async function getPreCache(): Promise<Cache> {
 	const version = await swStorage.getItem<string>('$sw.pre-cache.version')
+
+	// Get "cache" from ram
+	if (memory.has(version)) {
+		return memory.get(version) as Cache
+	}
+
 	// Get cache from server
 	if (version === null) {
 		await openPreCache()
 		return getPreCache()
 	}
-	return caches.open(version)
+
+	// Get "cache" from fs
+	const cache = await caches.open(version)
+	memory.set(version, cache)
+	return cache
 }
 
 const IS_SW = 'onpushsubscriptionchange' in self
@@ -132,8 +159,17 @@ async function fetchHandler(event: FetchEvent) {
 	// Network only
 	return fetch(event.request)
 }
+
 async function getDynCache(): Promise<Cache> {
+	const lifeTime = 1 * 24 * 3_600 * 1000 //1 day
+	const now = Date.now()
 	const version = await swStorage.getItem<number>('$sw.dyn-cache.version')
+
+	// Get "cache" from ram
+	if (memory.has(version)) {
+		return memory.get(version)
+	}
+
 	// Create cache
 	if (version === null) {
 		await swStorage.setItem<number>('$sw.dyn-cache.version', now + lifeTime)
@@ -147,11 +183,21 @@ async function getDynCache(): Promise<Cache> {
 		return getDynCache()
 	}
 
+	// Get "cache" from fs
+	const cache = await caches.open(version.toString())
+
+	memory.set(version, cache)
 	return cache
 }
 
-	// Network only
+async function updatePreCache(): Promise<void> {
-	return fetch(event.request)
+	const lifeTime = Date.now() + 1 * 24 * 3_600 * 1000 // 1 day
+	const now = Date.now()
+	const memoryKey = 'last-update-pre-cache'
+
+	// Refresh on sw start or 1 times / day
+	if (memory.get(memoryKey) > now) {
+		return
 	}
 
 	const serverVersion = await getServerPreCacheVersion()
@@ -164,6 +210,8 @@ async function getDynCache(): Promise<Cache> {
 	await openPreCache()
 	// Delete old pre-cache
 	caches.delete(clientVersion)
+	// Update memory
+	memory.set(memoryKey, lifeTime)
 }
 
 async function getServerPreCacheVersion(): Promise<string | undefined> {