ttl-cache.ts•2.99 kB
/**
* Simple TTL (Time-To-Live) Cache Implementation
*
* Provides automatic expiration of cached entries after a specified duration.
* Used for workspace-level caching of attribute metadata to reduce API calls
* while preventing stale data issues.
*/
export interface TTLCacheEntry<T> {
value: T;
expiresAt: number;
}
export class TTLCache<K, V> {
private cache: Map<K, TTLCacheEntry<V>>;
private readonly ttlMs: number;
private cleanupInterval?: NodeJS.Timeout;
/**
* Creates a new TTL cache
*
* @param ttlMs - Time-to-live in milliseconds (default: 15 minutes)
* @param cleanupIntervalMs - How often to check for expired entries (default: 5 minutes)
*/
constructor(
ttlMs: number = 15 * 60 * 1000,
cleanupIntervalMs: number = 5 * 60 * 1000
) {
this.cache = new Map();
this.ttlMs = ttlMs;
// Start periodic cleanup
this.cleanupInterval = setInterval(() => {
this.cleanup();
}, cleanupIntervalMs);
// Ensure cleanup interval doesn't keep process alive
if (this.cleanupInterval.unref) {
this.cleanupInterval.unref();
}
}
/**
* Gets a value from the cache
*
* @param key - The cache key
* @returns The cached value, or undefined if not found or expired
*/
get(key: K): V | undefined {
const entry = this.cache.get(key);
if (!entry) {
return undefined;
}
// Check if expired
if (Date.now() > entry.expiresAt) {
this.cache.delete(key);
return undefined;
}
return entry.value;
}
/**
* Sets a value in the cache with TTL
*
* @param key - The cache key
* @param value - The value to cache
*/
set(key: K, value: V): void {
this.cache.set(key, {
value,
expiresAt: Date.now() + this.ttlMs,
});
}
/**
* Checks if a key exists and is not expired
*
* @param key - The cache key
* @returns True if the key exists and is not expired
*/
has(key: K): boolean {
return this.get(key) !== undefined;
}
/**
* Removes a specific key from the cache
*
* @param key - The cache key to remove
*/
delete(key: K): boolean {
return this.cache.delete(key);
}
/**
* Clears all entries from the cache
*/
clear(): void {
this.cache.clear();
}
/**
* Returns the number of entries in the cache (including expired ones)
*/
get size(): number {
return this.cache.size;
}
/**
* Removes expired entries from the cache
* Called automatically by cleanup interval
*/
private cleanup(): void {
const now = Date.now();
for (const [key, entry] of this.cache.entries()) {
if (now > entry.expiresAt) {
this.cache.delete(key);
}
}
}
/**
* Stops the cleanup interval
* Should be called when the cache is no longer needed
*/
destroy(): void {
if (this.cleanupInterval) {
clearInterval(this.cleanupInterval);
this.cleanupInterval = undefined;
}
this.clear();
}
}