Lightweight Cache

cache.ts

export class LighweightCache {
  entries: CacheEntry[];
  size: number;
  ttl: number;
  constructor(size: number, ttl: number) {
    this.entries = [];
    this.size = size;
    this.ttl = ttl;
  }

  add(entry) {
    if (this.entries.length >= this.size) {
      this.entries.shift();
    }
    this.entries.push(entry);
  }

  clear() {
    this.entries = [];
  }
  check(url: string): CacheResponse {
    const now = Date.now();
    const chachedEntry = this.entries.find(
      (entry) => entry.url === url && entry.responseCode === 200 && now < entry.eol
    );
    if (chachedEntry) {
      return new CacheResponse(true, chachedEntry);
    } else {
      /// return a new entry to insert a response into
      const newEntry = new CacheEntry(url, this.ttl);
      this.add(newEntry);
      return new CacheResponse(false, newEntry);
    }
  }
}

class CacheEntry {
  url: string;
  eol: number;
  responseCode: number;
  responseData: Promise<object>;
  constructor(url: string, ttl: number) {
    this.url = url;
    this.eol = Date.now() + ttl;
    this.responseData = null;
    this.responseCode = null;
  }
}

class CacheResponse {
  cached: boolean;
  cacheEntry: CacheEntry;
  constructor(cached: boolean, cacheEntry: CacheEntry) {
    this.cached = cached;
    this.cacheEntry = cacheEntry;
  }
}