simple-async-memo

A minimalistic, reasonably fast (see alternatives below) memoization library with lazy cache renewal specifically for Promise-based usage.

Rejection is generally considered an unacceptable result. Hence, whenever calling the function to be memoized is required (either the initial call or on cache expiration - see maxAge), simple-async-memo will retry on every call (but you can also customize the interval at which this happens - see rejectRetryDelay).

If the initial call results in rejection, this will still be returned though.

Installation

yarn add simple-async-memo

Example

const {memoize} = require('simple-async-memo');
 
function fn(arg1, arg2) {
    return fetch('...');
}
 
const memoized = memoize(fn); // fn HAS to return a Promise!
 
memoized('foo', 'bar')
    .then(...)
    .catch(...);
memoized('foo', 'bar')
    .then(...)
    .catch(...);

Options

maxAge

Default: MAX_SAFE_INTEGER * 0.5

So by default, the cache doesn't expire.

rejectRetryDelay

Default: 10000 ms

This does not mean that simple-async-memo keeps retrying by itself. Instead, if you e.g. call a function regularly every 200 ms and you set this delay to 500 ms, if the initial call failed, simple-async-memo will not retry for the first 2 calls but only the 3rd. IF that one succeeds, the cache will be updated lazily - meaning, only the 4th call will get the resolved value.

matchesKey: (any[], any[]) => boolean

Default: shallow comparison of all array elements

Benchmark & Alternatives

You can run the benchmark by cloning this repo and doing npm run benchmark.

The basis is a function that takes two arguments and returns a Promise. For those libraries that support it, the "promise" flag was set.

Name	Ops/sec.	Relative margin of error	Sample size
moize	11,354,469	± 1.04%	81
simple-async-memo	5,717,515	± 0.65%	85
memoizee	1,707,028	± 1.83%	79
fast-memoize	971,844	± 0.74%	86

Moize offers great performance and has async options but unfortunately no lazy cache renewal. And its architecture is structured in a way that doesn't allow for contributing such a feature easily. (If this changes, let me know. 😉)