49 lines
2.1 KiB
TypeScript
49 lines
2.1 KiB
TypeScript
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import './polyfill-promise-with-resolvers';
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import type { SchedulerFn } from '../server/lib/schedule-on-next-tick';
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type CacheKeyFn<K, C extends string | number | null> = (key: K) => PromiseLike<C> | C;
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type BatcherOptions<K, C extends string | number | null> = {
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cacheKeyFn?: CacheKeyFn<K, C>;
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schedulerFn?: SchedulerFn<void>;
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};
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type WorkFn<V, C> = (key: C, resolve: (value: V | PromiseLike<V>) => void) => Promise<V>;
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/**
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* A wrapper for a function that will only allow one call to the function to
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* execute at a time.
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*/
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export declare class Batcher<K, V, C extends string | number | null> {
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private readonly cacheKeyFn?;
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/**
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* A function that will be called to schedule the wrapped function to be
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* executed. This defaults to a function that will execute the function
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* immediately.
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*/
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private readonly schedulerFn;
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private readonly pending;
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protected constructor(cacheKeyFn?: CacheKeyFn<K, C> | undefined,
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/**
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* A function that will be called to schedule the wrapped function to be
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* executed. This defaults to a function that will execute the function
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* immediately.
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*/
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schedulerFn?: SchedulerFn<void>);
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/**
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* Creates a new instance of PendingWrapper. If the key extends a string or
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* number, the key will be used as the cache key. If the key is an object, a
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* cache key function must be provided.
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*/
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static create<K extends string | number | null, V>(options?: BatcherOptions<K, K>): Batcher<K, V, K>;
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static create<K, V, C extends string | number | null>(options: BatcherOptions<K, C> & Required<Pick<BatcherOptions<K, C>, 'cacheKeyFn'>>): Batcher<K, V, C>;
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/**
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* Wraps a function in a promise that will be resolved or rejected only once
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* for a given key. This will allow multiple calls to the function to be
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* made, but only one will be executed at a time. The result of the first
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* call will be returned to all callers.
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*
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* @param key the key to use for the cache
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* @param fn the function to wrap
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* @returns a promise that resolves to the result of the function
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*/
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batch(key: K, fn: WorkFn<V, C>): Promise<V>;
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}
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export {};
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