@dr.pogodin/react-utils/build/web/server/Cache.js

Collection of generic ReactJS components and utils

/**
 * Implements the static cache.
 */
export default class Cache {
  items = {};
  size = 0;
  constructor(maxSize) {
    this.maxSize = maxSize;
  }

  /**
   * Cache lookup.
   * @param key Item key to look for.
   * @param [maxage=Number.MAX_VALUE] Optional. The maximum age of
   *  cached item to serve. Default to infinite.
   * @returns Cached item, or null if the item is absent in cache,
   *  or stale.
   */
  get({
    key,
    maxage = Number.MAX_VALUE
  }) {
    const item = this.items[key];
    return item && Date.now() - item.timestamp < maxage ? item.data : null;
  }

  /**
   * Adds item to cache.
   * @param data Item to add.
   * @param key Key to store the item at.
   * @param size Byte size of the item.
   */
  add(data, key, size) {
    const cached = this.items[key];
    if (cached) this.size -= cached.size;
    this.items[key] = {
      data,
      size,
      timestamp: Date.now()
    };
    this.size += size;
    if (this.size > this.maxSize) {
      const entries = Object.entries(this.items);
      entries.sort((a, b) => a[1].timestamp - b[1].timestamp);
      for (const entry of entries) {
        const [itemKey, item] = entry;
        delete this.items[itemKey];
        this.size -= item.size;
        if (this.size < this.maxSize / 2) break;
      }
    }
  }
}
//# sourceMappingURL=Cache.js.map