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21 lines
502 B
TypeScript
21 lines
502 B
TypeScript
interface CachedPromises<T> {
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[name: string]: Promise<T>
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}
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export type LockedFunc<T> = (key: string, fn: () => Promise<T>) => Promise<T>
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/**
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* Save promises for later
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*/
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export default function lock<T> (): LockedFunc<T> {
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const locks: CachedPromises<T> = {}
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return async (key: string, fn: () => Promise<T>): Promise<T> => {
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if (locks[key] != null) return locks[key]
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locks[key] = fn()
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fn()
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.then(() => delete locks[key], () => delete locks[key])
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return locks[key]
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}
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}
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