mastercache/src/cache/cache-entry/cache-entry.ts

Multi-tier cache module for Node.js. Redis, Upstash, CloudfareKV, File, in-memory and others drivers

import { JsonSerializer } from '../../serializers/json';

/**
 * Represents a cache entry stored inside a cache driver.
 */
export class CacheEntry {
  /**
   * The key of the cache item.
   */
  #key: string;

  /**
   * The value of the item.
   */
  #value: any;

  /**
   * The logical expiration is the time in miliseconds when the item
   * will be considered expired. But, if grace period is enabled,
   * the item will still be available for a while.
   */
  #logicalExpiration: number;

  #earlyExpiration: number;

  static #serializer = new JsonSerializer();

  constructor(key: string, item: Record<string, any>) {
    this.#key = key;
    this.#value = item.value;
    this.#logicalExpiration = item.logicalExpiration;
    this.#earlyExpiration = item.earlyExpiration;
  }

  getValue() {
    return this.#value;
  }

  getKey() {
    return this.#key;
  }

  getLogicalExpiration() {
    return this.#logicalExpiration;
  }

  getEarlyExpiration() {
    return this.#earlyExpiration;
  }

  isLogicallyExpired() {
    return Date.now() >= this.#logicalExpiration;
  }

  isEarlyExpired() {
    if (!this.#earlyExpiration) {
      return false;
    }

    if (this.isLogicallyExpired()) {
      return false;
    }

    return Date.now() >= this.#earlyExpiration;
  }

  static fromDriver(key: string, item: string) {
    return new CacheEntry(key, this.#serializer.deserialize(item));
  }

  applyFallbackDuration(duration: number) {
    this.#logicalExpiration += duration;
    this.#earlyExpiration = 0;
    return this;
  }

  expire() {
    this.#logicalExpiration = Date.now() - 100;
    this.#earlyExpiration = 0;
    return this;
  }

  serialize() {
    return CacheEntry.#serializer.serialize({
      value: this.#value,
      logicalExpiration: this.#logicalExpiration,
      earlyExpiration: this.#earlyExpiration,
    });
  }
}