51 lines
1.2 KiB
TypeScript
51 lines
1.2 KiB
TypeScript
export interface RateLimitedPublisher {
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request: () => void;
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cancel: () => void;
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dispose: () => void;
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}
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/**
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* Coalesces bursty state updates while preserving an immediate leading publish.
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* The trailing publish always contains current state because `publish` reads it
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* when the timer fires.
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*/
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export function createRateLimitedPublisher(
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publish: () => void,
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intervalMs: number,
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now: () => number = () => performance.now(),
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): RateLimitedPublisher {
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let lastPublishedAt = Number.NEGATIVE_INFINITY;
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let timer: ReturnType<typeof setTimeout> | null = null;
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let disposed = false;
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const run = () => {
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timer = null;
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if (disposed) return;
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lastPublishedAt = now();
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publish();
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};
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const cancel = () => {
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if (timer !== null) clearTimeout(timer);
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timer = null;
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};
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return {
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request: () => {
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if (disposed) return;
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const remaining = intervalMs - (now() - lastPublishedAt);
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if (remaining <= 0) {
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if (timer !== null) clearTimeout(timer);
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run();
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return;
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}
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if (timer === null) timer = setTimeout(run, remaining);
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},
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cancel,
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dispose: () => {
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disposed = true;
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cancel();
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},
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};
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}
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