22 lines
456 B
TypeScript
22 lines
456 B
TypeScript
export class PromiseCache <A, R> {
|
|
private readonly running = new Map<string, Promise<R>>()
|
|
|
|
constructor (
|
|
private readonly fn: (arg: A) => Promise<R>,
|
|
private readonly keyBuilder: (arg: A) => string
|
|
) {
|
|
}
|
|
|
|
run (arg: A) {
|
|
const key = this.keyBuilder(arg)
|
|
|
|
if (this.running.has(key)) return this.running.get(key)
|
|
|
|
const p = this.fn(arg)
|
|
|
|
this.running.set(key, p)
|
|
|
|
return p.finally(() => this.running.delete(key))
|
|
}
|
|
}
|