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. 😉)