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// Copyright (c) 2026 Cloudflare, Inc.
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// Licensed under the Apache 2.0 license found in the LICENSE file or at:
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//     https://opensource.org/licenses/Apache-2.0
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import { ok } from 'node:assert';
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import timers from 'node:timers/promises';
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// Allow up to 10ms of jitter because the precise_timers compat flag
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// can introduce +/-3ms of variance in timer resolution, and coverage
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// builds add additional overhead.
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const JITTER = 10;
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// The first setTimeout was firing too early because
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// kj::Timer::now() was stale after script compilation/startup.
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// Ref: https://github.com/cloudflare/workerd/issues/6019
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export const basicAccuracy = {
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  async test() {
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    const t0 = Date.now();
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    await timers.setTimeout(100);
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    const t1 = Date.now();
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    ok(t1 - t0 >= 100 - JITTER, `Received a difference of ${t1 - t0}`);
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    await timers.setTimeout(100);
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    const t2 = Date.now();
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    ok(t2 - t1 >= 100 - JITTER, `Received a difference of ${t2 - t1}`);
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  },
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};
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// After CPU-heavy work between setTimeout calls,
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// subsequent consecutive setTimeouts must still each wait their full delay
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// rather than all firing at the same instant.
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// Ref: https://github.com/cloudflare/workerd/issues/6037
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export const accuracyAfterCpuWork = {
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  async test() {
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    await timers.setTimeout(50);
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    // Let's burn some CPU
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    for (let j = 0; j < 1e9; j++);
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    const a = Date.now();
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    await timers.setTimeout(50);
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    const b = Date.now();
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    ok(
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      b - a >= 50 - JITTER,
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      `After CPU work, first sleep: expected ~50ms, got ${b - a}ms`
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    );
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    await timers.setTimeout(50);
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    const c = Date.now();
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    ok(
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      c - b >= 50 - JITTER,
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      `After CPU work, second sleep: expected ~50ms, got ${c - b}ms`
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    );
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    await timers.setTimeout(50);
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    const d = Date.now();
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    ok(
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      d - c >= 50 - JITTER,
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      `After CPU work, third sleep: expected ~50ms, got ${d - c}ms`
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    );
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  },
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};