@arcjet/cache

Arcjet cache interface and implementations.

• npm package (@arcjet/cache)
• GitHub source code (cache/ in arcjet/arcjet-js)

Installation

npm install -S @arcjet/cache

API

Caches implement the Cache interface over a specific type:

interface Cache<T = unknown> {
  /**
   * Attempts to retrieve a value from the cache. If a value exists, it will be
   * returned with the remaining time-to-live (in seconds).
   *
   * @param namespace A isolated segement of the cache where keys are tracked.
   * @param key The identifier used to retrieve the value.
   * @returns A promise for a 2-element tuple containing the value and TTL in
   * seconds. If no value is retrieved, the value will be `undefined` and the
   * TTL will be `0`.
   */
  get(namespace: string, key: string): Promise<[T | undefined, number]>;
  /**
   * If the cache implementation supports storing values, `set` makes a best
   * attempt at storing the value provided until the time-to-live specified.
   *
   * @param namespace A isolated segement of the cache where keys are tracked.
   * @param key The identifier used to store the value.
   * @param value The value to be stored under the key.
   * @param ttl The amount of seconds the value stays valid in the cache.
   */
  set(namespace: string, key: string, value: T, ttl: number): void;
}

One such implementation is provided as MemoryCache:

MemoryCache#constructor()

Instantiate the MemoryCache using new MemoryCache() without any arguments.

MemoryCache#get(namespace: string, key: string): Promise<[T | undefined, number]>

Attempts to retrieve a value from the cache. If a value exists, it will be returned with the remaining time-to-live (in seconds).

Non-string arguments will cause the returned promise to reject.

MemoryCache#set(namespace: string, key: string, value: T, ttl: number): void

Makes a best attempt at storing the value provided until the time-to-live specified.

Non-string arguments will cause the function to throw.

Example

import { MemoryCache } from "@arcjet/cache";

const cache = new MemoryCache();

const namespace = "myNamespace";
const key = "myKey";

const ttlSeconds = 60; // seconds

const valueToCache = 1;

cache.set(namespace, key, valueToCache, ttlSeconds);

const [cachedValue, ttl] = await cache.get(namespace, key);
if (cachedValue && ttl > 0) {
  // do something with cached value
}

License

Licensed under the Apache License, Version 2.0.