export async function fetchWithTimeout (resource, { timeout = 1000, ...options } = {}) { const controller = new AbortController() const id = setTimeout(() => controller.abort(), timeout) const response = await fetch(resource, { ...options, signal: controller.signal }) clearTimeout(id) return response } class LRUCache { constructor (maxSize = 100) { this.maxSize = maxSize this.cache = new Map() } get (key) { if (!this.cache.has(key)) return undefined const value = this.cache.get(key) // refresh the entry this.cache.delete(key) this.cache.set(key, value) return value } set (key, value) { if (this.cache.has(key)) this.cache.delete(key) else if (this.cache.size >= this.maxSize) { // Remove the least recently used item this.cache.delete(this.cache.keys().next().value) } this.cache.set(key, value) } } function createDebugLogger (name, cache, debug) { const noop = () => {} if (!debug) { return { log: noop, errorLog: noop, startPeriodicLogging: noop, stopPeriodicLogging: noop, incrementTotalFetches: noop, incrementCacheHits: noop, incrementCacheMisses: noop, incrementBackgroundRefreshes: noop } } let totalFetches = 0 let cacheMisses = 0 let cacheHits = 0 let backgroundRefreshes = 0 let intervalId = null const log = (message) => console.log(`[CACHE:${name}] ${message}`) const errorLog = (message, error) => console.error(`[CACHE:${name}] ${message}`, error) function estimateCacheSize () { let size = 0 for (const [key, value] of cache.cache) { size += key.length * 2 size += JSON.stringify(value).length * 2 } return size } function startPeriodicLogging () { if (intervalId) return // Prevent multiple intervals intervalId = setInterval(() => { const cacheSize = cache.cache.size const memorySizeBytes = estimateCacheSize() log(`Stats: total=${totalFetches}, hits=${cacheHits}, misses=${cacheMisses}, backgroundRefreshes=${backgroundRefreshes}, cacheSize=${cacheSize}, memoryFootprint=${memorySizeBytes} bytes`) }, 60000) } function stopPeriodicLogging () { if (intervalId) { clearInterval(intervalId) intervalId = null } } return { log, errorLog, startPeriodicLogging, stopPeriodicLogging, incrementTotalFetches: () => totalFetches++, incrementCacheHits: () => cacheHits++, incrementCacheMisses: () => cacheMisses++, incrementBackgroundRefreshes: () => backgroundRefreshes++ } } export function cachedFetcher (fetcher, { maxSize = 100, cacheExpiry, forceRefreshThreshold, keyGenerator, debug = false }) { const cache = new LRUCache(maxSize) const name = fetcher.name || fetcher.toString().slice(0, 20).replace(/\s+/g, '_') const logger = createDebugLogger(name, cache, debug) logger.log(`initializing with maxSize=${maxSize}, cacheExpiry=${cacheExpiry}, forceRefreshThreshold=${forceRefreshThreshold}`) logger.startPeriodicLogging() if (!keyGenerator) { throw new Error('keyGenerator is required') } const cachedFetch = async function (...args) { const key = keyGenerator(...args) const now = Date.now() logger.incrementTotalFetches() async function fetchAndCache () { logger.log(`Fetching data for key: ${key}`) const result = await fetcher(...args) cache.set(key, { data: result, createdAt: now }) logger.log(`Data fetched and cached for key: ${key}`) return result } const cached = cache.get(key) if (cached) { const age = now - cached.createdAt if (cacheExpiry === 0 || age < cacheExpiry) { logger.incrementCacheHits() logger.log(`Cache hit for key: ${key}, age: ${age}ms`) return cached.data } else if (forceRefreshThreshold === 0 || age < forceRefreshThreshold) { if (cached.pendingPromise) { logger.log(`Already background refreshing key: ${key}`) return cached.data } logger.incrementBackgroundRefreshes() logger.log(`Background refresh for key: ${key}, age: ${age}ms`) cached.pendingPromise = fetchAndCache().catch(error => { logger.errorLog(`Background refresh failed for key: ${key}`, error) return cached.data }).finally(() => { logger.log(`Background refresh completed for key: ${key}`) delete cached.pendingPromise }) return cached.data } if (cached.pendingPromise) { logger.log(`Waiting for pending force refresh for key: ${key}`) return await cached.pendingPromise } } logger.incrementCacheMisses() logger.log(`Cache miss for key: ${key}`) const entry = { createdAt: now, pendingPromise: fetchAndCache() } cache.set(key, entry) try { entry.data = await entry.pendingPromise return entry.data } catch (error) { logger.errorLog(`Error fetching data for key: ${key}`, error) cache.delete(key) throw error } finally { logger.log(`Fetch completed for key: ${key}`) delete entry.pendingPromise } } // Attach the stopPeriodicLogging method to the returned function cachedFetch.stopPeriodicLogging = logger.stopPeriodicLogging return cachedFetch }