isaacs
commented
1 year ago This class does not enforce a singleton, no, that would be a bad idea, since you might need to cache multiple different sorts of things!
But modules in node are singletons.
So, for example, this is probably what you want to do:
// in src/routes/api.ts or something
import LRUCache from 'lru-cache'
// only create one fooCache for this _module_, which is a singleton
const fooCache = new LRUCache<string, Foo>({
max: 10000,
ttl: 1000 * 60 * 60, // 1hr
fetchMethod: async (key) => await getNewFoo(key),
})
export const getFoo = async (params) => {
const foo = await fooCache.fetch(params.foo).catch(er => {
console.error('foo error', params, er)
return new Response(JSON.stringify({ message: 'error fetching foo' }, 500))
})
return new Response(JSON.stringify(foo))
}Then if you had another file that did something like this:
// src/routes/other.ts
import { getFoo } from './api'
import { otherThing } from './other-thing'
export const otherEndpoint = async (params) => {
if (params.foo) {
return getFoo(params)
} else {
return otherThing(params)
}
}then it'll still always use the module-local fooCache.
However, this would almost certainly not be what you want:
// in src/routes/api.ts or something
import LRUCache from 'lru-cache'
export const getFoo = async (params) => {
// oh no! We're not actually caching anything, because
// we throw the cache away and create a new one on
// each API request! That's no good!
const fooCache = new LRUCache<string, Foo>({
max: 10000,
ttl: 1000 * 60 * 60, // 1hr
fetchMethod: async (key) => await getNewFoo(key),
})
const foo = await fooCache.fetch(params.foo).catch(er => {
console.error('foo error', params, er)
return new Response(JSON.stringify({ message: 'error fetching foo' }, 500))
})
return new Response(JSON.stringify(foo))
}Hope that helps.
TannerS
So what i mean is, if I create an instance of LRU cache in a file, and that file gets called multiple times for multiple api request, is that instance re-created (basically re-creating the initial cache or will it remember it was created in prior api call and use the data from there?