Function createPdfCache

examples/pdf-server/server.ts:708–889

(
  maxTotalBytes: number = CACHE_MAX_TOTAL_BYTES,
)

 * - CACHE_MAX_LIFETIME_MS from creation (absolute timeout)
 */
export function createPdfCache(
  maxTotalBytes: number = CACHE_MAX_TOTAL_BYTES,
): PdfCache {
  const cache = new Map<string, CacheEntry>();
  let totalBytes = 0;

  /** Delete a cache entry and clear its timers */
  function deleteCacheEntry(url: string): void {
    const entry = cache.get(url);
    if (entry) {
      clearTimeout(entry.inactivityTimer);
      clearTimeout(entry.maxLifetimeTimer);
      totalBytes -= entry.data.length;
      cache.delete(url);
    }
  }

  /** Get cached data and refresh the inactivity timer */
  function getCacheEntry(url: string): Uint8Array | undefined {
    const entry = cache.get(url);
    if (!entry) return undefined;

    // Refresh inactivity timer on access
    clearTimeout(entry.inactivityTimer);
    entry.inactivityTimer = setTimeout(() => {
      deleteCacheEntry(url);
    }, CACHE_INACTIVITY_TIMEOUT_MS);

    // Move to end of insertion order so size-cap eviction is LRU.
    cache.delete(url);
    cache.set(url, entry);

    return entry.data;
  }

  /** Add data to cache with both inactivity and max lifetime timers */
  function setCacheEntry(url: string, data: Uint8Array): void {
    // Clear any existing entry first
    deleteCacheEntry(url);

    // Evict least-recently-used entries until under the byte cap.
    for (const oldest of cache.keys()) {
      if (totalBytes + data.length <= maxTotalBytes) break;
      deleteCacheEntry(oldest);
    }

    const entry: CacheEntry = {
      data,
      createdAt: Date.now(),
      inactivityTimer: setTimeout(() => {
        deleteCacheEntry(url);
      }, CACHE_INACTIVITY_TIMEOUT_MS),
      maxLifetimeTimer: setTimeout(() => {
        deleteCacheEntry(url);
      }, CACHE_MAX_LIFETIME_MS),
    };

    cache.set(url, entry);