JS ASync

Utility library for caching.

Usage

A Cache wraps a function (both synchronous or asynchronous) to ensure that results are cached for later use.

To create a Cache object, use the createCache method:

import {createCache} from "@prodo-ai/js-caching";

const cache = createCache(
  key => key,
  async key => ({
    value: await service.getValue(key),
  }),
);

const firstResult = cache.get("first");       // Will use `service`.
const secondResult = cache.get("second");     // Will use `service`.
const firstResultAgain = cache.get("first");  // Will use the cache.

The first parameter hasher is used to create a unique string for each key. This is the hash that uniquely identifies the result in the cache.

The second parameter create is the factory method to fetch results that don't exist in the hash. The return value of this function should be an object containing the following properties:

• value - the value to store in the cache
• destroy - an optional callback that will destroy and clean-up the cached value.

For example, if your cache stores references to information stored on disk, your destroy function would delete the information from the disk. This function is only called when the value is removed from the cache.

You can also pass additional options as a third parameter to gain greater control over the cache:

• size - the number of results to store in the cache.
• expiry - a Duration (see @prodo-ai/js-timing) that determines how long to keep a result for.
• cleanupInterval - a Duration that specifies how frequently to run garbage collection.

memoize

The most simple use of a cache is to memoize a function. This can be done using the memoize helper:

import {memoize} from "@prodo-ai/js-caching";

const func = (args) => {/*...*/};
const hasher = (args) => {/* create a hash of the args */};
const memoizedFunc = memoize(hasher, func);

const firstResult = memoizedFunc("first");
const secondResult = memoizedFunc("second");
const firstResultAgain = memoizedFunc("first");  // Will use the cache.

Information

Owner: Prodo Tech Ltd

Maintainer: tdawes

License: UNLICENSED (for now)