perf(session): ttl

components/login/libs/session-cache.ts

@@ -0,0 +1,96 @@
+const SESSION_CACHE_TTL_MS = 5000
+
+type SessionCacheSource = "memory" | "shared" | "redis"
+
+interface SessionCacheEntry<T> {
+  data: T
+  expiresAt: number
+}
+
+const sessionCache = new Map<string, SessionCacheEntry<any>>()
+const inflightSessionLoads = new Map<string, Promise<any | null>>()
+
+const getNow = () => Date.now()
+
+const getValidCachedSession = <T>(redisKey: string) => {
+  const cacheEntry = sessionCache.get(redisKey)
+
+  if (!cacheEntry) {
+    return null
+  }
+
+  if (cacheEntry.expiresAt <= getNow()) {
+    sessionCache.delete(redisKey)
+    return null
+  }
+
+  return cacheEntry.data as T
+}
+
+export const getCachedSession = <T>(redisKey: string) =>
+  getValidCachedSession<T>(redisKey)
+
+export const setCachedSession = <T>(redisKey: string, data: T) => {
+  sessionCache.set(redisKey, {
+    data,
+    expiresAt: getNow() + SESSION_CACHE_TTL_MS,
+  })
+}
+
+export const deleteCachedSession = (redisKey: string) => {
+  sessionCache.delete(redisKey)
+  inflightSessionLoads.delete(redisKey)
+}
+
+export const getSessionCacheTtlMs = () => SESSION_CACHE_TTL_MS
+
+export const getOrLoadSession = async <T>(
+  redisKey: string,
+  loader: () => Promise<T | null>
+): Promise<{
+  data: T | null
+  source: SessionCacheSource
+}> => {
+  const cachedData = getValidCachedSession<T>(redisKey)
+
+  if (cachedData) {
+    return {
+      data: cachedData,
+      source: "memory",
+    }
+  }
+
+  const inflightLoad = inflightSessionLoads.get(redisKey)
+
+  if (inflightLoad) {
+    return {
+      data: (await inflightLoad) as T | null,
+      source: "shared",
+    }
+  }
+
+  const loadPromise = (async () => {
+    const loadedData = await loader()
+
+    if (loadedData) {
+      setCachedSession(redisKey, loadedData)
+    } else {
+      deleteCachedSession(redisKey)
+    }
+
+    return loadedData
+  })()
+
+  inflightSessionLoads.set(redisKey, loadPromise)
+
+  try {
+    return {
+      data: await loadPromise,
+      source: "redis",
+    }
+  } finally {
+    if (inflightSessionLoads.get(redisKey) === loadPromise) {
+      inflightSessionLoads.delete(redisKey)
+    }
+  }
+}