race-cancellation
Version:
Utilities for using Promise.race([task, cancellation]) for async/await code.
90 lines • 3.04 kB
TypeScript
/**
* An async function.
* @public
*/
export declare type AsyncFn<TResult> = () => PromiseLike<TResult>;
/**
* A function that builds a race against a cancel rejection.
*
* @remarks
* If the task is a function, the expectation is it will not be called
* if already in a cancelled state. Thus it should not close over any
* floating promises, in general it should just create a new promise,
* if it uses a cached promise it should have been already chained
* to something that handles its rejection.
*
* This method can also take a promise and it will always race it even
* if already in a cancelled state so if the promise fails it will not
* cause an unhandled rejection.
*
* Calling this function is infallible (it wont fail to return a Promise
* to be awaited).
*
* @param asyncFnOrPromise - a {@link AsyncFn} function to start an async operation or a promise.
* @public
*/
export declare type RaceCancelFn = <TResult>(asyncFnOrPromise: AsyncFn<TResult> | PromiseLike<TResult>) => Promise<TResult>;
/**
* The Error interface for cancellation rejection.
* @public
*/
export interface CancelError<TName extends string = "CancelError"> extends Error {
name: TName;
isCancelled: true;
}
/**
* The Error interface for {@link withTimeout} if the timeout wins the race.
* @public
*/
export interface TimeoutError<TName extends string = "TimeoutError"> extends CancelError<TName> {
isTimeout: true;
}
/**
* A cancellable async function.
* @param raceCancel - a {@link RaceCancelFn}.
* @public
*/
export declare type CancellableAsyncFn<TResult> = (raceCancel: RaceCancelFn) => Promise<TResult>;
/**
* A cleanup function that should be idempotent and infallible.
* @public
*/
export declare type DisposeFn = () => void;
/**
* A promise executor that returns a {@link DisposeFn} function.
*
* @remarks
*
* For example, if it is the promise of a setTimeout, should call clearTimeout.
*
* If it resolves on an event listener, it should uninstall the event listener.
* @public
*/
export declare type DisposableExecutorFn<TResult> = (resolve: (value?: TResult | PromiseLike<TResult>) => void, reject: (reason?: unknown) => void) => DisposeFn;
/**
* A {@link CancelError} or `string` that is the cancellation reason.
* @public
*/
export declare type CancelReason = CancelError<string> | string;
/**
* A function that resolves the cancellation for deferCancel or withCancel.
* @public
*/
export declare type ResolveCancelFn = (reason?: CancelReason) => void;
/**
* A executor function for the cancellation concern that can resolve with a reason
* and can return a cleanup function.
* @public
*/
export declare type DisposableCancelExecutorFn = (resolve: ResolveCancelFn) => DisposeFn;
/**
* An accessor function for checking cancelled state.
* @public
*/
export declare type IsCancelledFn = () => boolean;
/**
* A executor function for the cancellation.
* @public
*/
export declare type CancelExecutorFn = (resolve: () => void) => void;
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