/**
* Simple in-memory cache with TTL support
*/
interface CacheEntry<T> {
value: T;
expiresAt: number;
}
export class Cache<T> {
private store: Map<string, CacheEntry<T>> = new Map();
private defaultTtl: number;
/**
* Create a new cache instance
* @param defaultTtl Default time-to-live in milliseconds (default: 30 minutes)
*/
constructor(defaultTtl: number = 30 * 60 * 1000) {
this.defaultTtl = defaultTtl;
}
/**
* Get a value from cache
*/
get(key: string): T | undefined {
const entry = this.store.get(key);
if (!entry) return undefined;
if (Date.now() > entry.expiresAt) {
this.store.delete(key);
return undefined;
}
return entry.value;
}
/**
* Set a value in cache
*/
set(key: string, value: T, ttl?: number): void {
const expiresAt = Date.now() + (ttl ?? this.defaultTtl);
this.store.set(key, { value, expiresAt });
}
/**
* Check if key exists and is not expired
*/
has(key: string): boolean {
const entry = this.store.get(key);
if (!entry) return false;
if (Date.now() > entry.expiresAt) {
this.store.delete(key);
return false;
}
return true;
}
/**
* Delete a specific key
*/
delete(key: string): boolean {
return this.store.delete(key);
}
/**
* Clear all cached values
*/
clear(): void {
this.store.clear();
}
/**
* Get or set pattern - fetch from cache or compute and cache
*/
async getOrSet(key: string, factory: () => Promise<T>, ttl?: number): Promise<T> {
const cached = this.get(key);
if (cached !== undefined) {
return cached;
}
const value = await factory();
this.set(key, value, ttl);
return value;
}
/**
* Clean expired entries
*/
cleanup(): number {
let cleaned = 0;
const now = Date.now();
for (const [key, entry] of this.store.entries()) {
if (now > entry.expiresAt) {
this.store.delete(key);
cleaned++;
}
}
return cleaned;
}
/**
* Get cache statistics
*/
stats(): { size: number; validEntries: number } {
this.cleanup();
return {
size: this.store.size,
validEntries: this.store.size,
};
}
}
// Global cache instances
export const versionCache = new Cache<string>(60 * 60 * 1000); // 1 hour
export const metadataCache = new Cache<unknown>(30 * 60 * 1000); // 30 minutes
