Codex
41 lines
1.3 KiB
JavaScript
41 lines
1.3 KiB
JavaScript
let messageChannelYield;
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let cooperativeTurn = 0;
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export const COOPERATIVE_TIMER_TURN_INTERVAL = 8;
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function createMessageChannelYield() {
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if (typeof globalThis.MessageChannel !== "function") return undefined;
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const channel = new globalThis.MessageChannel();
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const queue = [];
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channel.port1.onmessage = () => queue.shift()?.();
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channel.port1.unref?.();
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channel.port2.unref?.();
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return () => new Promise((resolve) => {
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queue.push(resolve);
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channel.port2.postMessage(0);
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});
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}
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/**
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* Yield one cooperative task without relying on nested zero-delay timers.
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* scheduler.yield() is preferred when the host implements it; MessageChannel
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* keeps the fallback task-based and avoids browser timer clamping.
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*/
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export function cooperativeYield() {
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cooperativeTurn += 1;
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if (cooperativeTurn % COOPERATIVE_TIMER_TURN_INTERVAL === 0) {
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return new Promise((resolve) => setTimeout(resolve, 0));
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}
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const hostScheduler = globalThis.scheduler;
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if (typeof hostScheduler?.yield === "function") {
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try {
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return hostScheduler.yield();
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} catch {
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// A partial scheduler implementation must not make computation unusable.
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}
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}
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messageChannelYield ??= createMessageChannelYield();
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if (messageChannelYield) return messageChannelYield();
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return new Promise((resolve) => setTimeout(resolve, 0));
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}
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