2012-04-27 00:22:06 -07:00
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<!DOCTYPE HTML>
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<html>
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<head>
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<title>Test for High Resolution Timer</title>
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<script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
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<script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
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<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
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</head>
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<body>
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<script>
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2012-05-07 08:44:26 -07:00
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ok(window.performance, "Performance object should exist.");
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ok(typeof window.performance.now == 'function', "Performance object should have a 'now' method.");
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var n = window.performance.now(), d = Date.now();
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ok(n >= 0, "The value of now() should be equal to or greater than 0.");
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ok(window.performance.now() >= n, "The value of now() should monotonically increase.");
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2012-04-27 00:22:06 -07:00
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SimpleTest.waitForExplicitFinish();
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2012-05-07 08:44:26 -07:00
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2013-03-04 21:17:11 -08:00
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// The spec says performance.now() should have micro-second resolution, but allows 1ms if the platform doesn't support it.
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// Our implementation does provide micro-second resolution, except for windows XP combined with some HW properties
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// where we can't use QueryPerformanceCounters (see comments at mozilla-central/xpcom/ds/TimeStamp_windows.cpp).
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// This XP-low-res case results in about 15ms resolutions, and can be identified when perf.now() returns only integers.
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//
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// Since setTimeout might return too early/late, our goal is that perf.now() changed within 2ms
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// (or 25ms for XP-low-res), rather than specific number of setTimeout(N) invocations.
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// See bug 749894 (intermittent failures of this test)
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var platformPossiblyLowRes = navigator.oscpu.indexOf("Windows NT 5.1") == 0; // XP only
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var allInts = (n % 1) == 0; // Indicator of limited HW resolution.
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2012-05-07 08:44:26 -07:00
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var checks = 0;
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2013-03-04 21:17:11 -08:00
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2012-05-07 08:44:26 -07:00
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function checkAfterTimeout() {
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checks++;
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var d2 = Date.now();
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2013-03-04 21:17:11 -08:00
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var n2 = window.performance.now();
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allInts = allInts && (n2 % 1) == 0;
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var lowResCounter = platformPossiblyLowRes && allInts;
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if ( n2 == n && checks < 50 && // 50 is just a failsafe. Our real goals are 2ms or 25ms.
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( (d2 - d) < 2 // The spec allows 1ms resolution. We allow up to measured 2ms to ellapse.
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||
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lowResCounter &&
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(d2 - d) < 25
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)
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) {
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setTimeout(checkAfterTimeout, 1);
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2012-05-07 08:44:26 -07:00
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return;
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}
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2013-03-04 21:17:11 -08:00
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// Loose spec: 1ms resolution, or 15ms resolution for the XP-low-res case.
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// We shouldn't test that dt is actually within 2/25ms since the iterations break if it isn't, and timeout could be late.
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ok(n2 > n, "Loose - the value of now() should increase within 2ms (or 25ms if low-res counter) (delta now(): " + (n2 - n) + " ms).");
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// Strict spec: if it's not the XP-low-res case, while the spec allows 1ms resolution, it prefers microseconds, which we provide.
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// Since the fastest setTimeout return which I observed was ~500 microseconds, a microseconds counter should change in 1 iteretion.
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ok(n2 > n && (lowResCounter || checks == 1),
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"Strict - [if high-res counter] the value of now() should increase after one setTimeout (hi-res: " + (!lowResCounter) +
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", iters: " + checks +
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", dt: " + (d2 - d) +
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", now(): " + n2 + ").");
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2012-04-27 00:22:06 -07:00
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SimpleTest.finish();
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2012-05-07 08:44:26 -07:00
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};
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2013-03-04 21:17:11 -08:00
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setTimeout(checkAfterTimeout, 1);
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2012-04-27 00:22:06 -07:00
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</script>
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</body>
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</html>
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