34 lines
1.2 KiB
TypeScript
34 lines
1.2 KiB
TypeScript
 
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import { useEffect, useRef } from "react";
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/** A visibility-gated interval that never overlaps its own ticks (spec §5). */
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export function useViewerPolling(intervalMs: number, tick: () => Promise<void>, enabled: boolean): void {
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const tickRef = useRef(tick);
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tickRef.current = tick;
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useEffect(() => {
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if (!enabled) return;
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let disposed = false;
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let inFlight = false;
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let timer: ReturnType<typeof setInterval> | null = null;
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const run = async () => {
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if (disposed || inFlight || document.visibilityState !== "visible") return;
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inFlight = true;
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try { await tickRef.current(); } finally { inFlight = false; }
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};
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const start = () => { if (timer === null) timer = setInterval(run, intervalMs); };
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const stop = () => { if (timer !== null) { clearInterval(timer); timer = null; } };
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const onVisibility = () => {
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if (document.visibilityState === "visible") { void run(); start(); } else { stop(); }
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};
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document.addEventListener("visibilitychange", onVisibility);
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onVisibility();
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return () => {
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disposed = true;
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stop();
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document.removeEventListener("visibilitychange", onVisibility);
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};
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}, [intervalMs, enabled]);
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}
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