async-cache-dedupe

async-cache-dedupe

async-cache-dedupe is a cache for asynchronous fetching of resources with full deduplication, i.e. the same resource is only asked once at any given time.

Install

npm i async-cache-dedupe

Example

import { Cache } from 'async-cache-dedupe'

const cache = new Cache({
  ttl: 5 // seconds
})

cache.define('fetchSomething', async (k) => {
  console.log('query', k)
  // query 42
  // query 24

  return { k }
})

const p1 = cache.fetchSomething(42)
const p2 = cache.fetchSomething(24)
const p3 = cache.fetchSomething(42)

const res = await Promise.all([p1, p2, p3])

console.log(res)
// [
//   { k: 42 },
//   { k: 24 }
//   { k: 42 }
// ]

Commonjs/require is also supported.

API

new Cache(opts)

Creates a new cache.

Options:

• tll: the maximum time a cache entry can live, default 0; if 0, an element is removed from the cache as soon as as the promise resolves.
• cacheSize: the maximum amount of entries to fit in the cache for each defined method, default 1024.

cache.define(name[, opts], original(arg, cacheKey))

Define a new function to cache of the given name.

Options:

• tll: the maximum time a cache entry can live, default as defined in the cache.
• cacheSize: the maximum amount of entries to fit in the cache for each defined method, default as defined in the cache.
• serialize: a function to convert the given argument into a serializable object (or string).
• onHit: a function that is called every time there is a hit in the cache.

The define method adds a cache[name] function that will call the original function if the result is not present in the cache. The cache key for arg is computed using safe-stable-stringify and it is passed as the cacheKey argument to the original function.

cache.clear([name], [arg])

Clear the cache. If name is specified, all the cache entries from the function defined with that name are cleared. If arg is specified, only the elements cached with the given name and arg are cleared.

License

MIT