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