48 lines
1.4 KiB
TypeScript
48 lines
1.4 KiB
TypeScript
/** What is left of a budget, in the shape a wait takes it: 0 waits forever. */
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export function leftOf(deadline: number): number {
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return deadline === 0 ? 0 : Math.max(1, deadline - Date.now());
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}
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/** Everything waiting for a count to fall to zero, and how such a wait is cut short. */
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export class IdleWaiters {
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private readonly waiting: (() => void)[] = [];
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/** Wakes everything waiting, whatever the count reads now. */
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settle(): void {
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for (const resolve of this.waiting.splice(0)) {
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resolve();
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}
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}
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/**
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* Resolves 0 once nothing is left, or with what still is when the timeout or the signal cuts the
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* wait short. A timeout of 0 waits forever.
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*/
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wait(remaining: () => number, timeout: number, signal: AbortSignal | undefined): Promise<number> {
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if (remaining() === 0) return Promise.resolve(0);
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if (signal?.aborted === true) return Promise.resolve(remaining());
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return new Promise<number>(resolve => {
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let timer: NodeJS.Timeout | undefined = undefined;
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const done = (): void => {
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const index = this.waiting.indexOf(done);
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if (timer) clearTimeout(timer);
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if (index !== -1) this.waiting.splice(index, 1);
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signal?.removeEventListener('abort', done);
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resolve(remaining());
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};
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if (timeout > 0) {
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timer = setTimeout(done, timeout);
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timer.unref();
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}
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signal?.addEventListener('abort', done, { once: true });
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this.waiting.push(done);
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});
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}
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}
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