1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/dom/tests/mochitest/general/test_performance_now.html Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,65 @@
1.4 +<!DOCTYPE HTML>
1.5 +<html>
1.6 +<head>
1.7 + <title>Test for High Resolution Timer</title>
1.8 + <script type="text/javascript" src="/MochiKit/MochiKit.js"></script>
1.9 + <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
1.10 + <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
1.11 +</head>
1.12 +<body>
1.13 + <script>
1.14 + ok(window.performance, "Performance object should exist.");
1.15 + ok(typeof window.performance.now == 'function', "Performance object should have a 'now' method.");
1.16 + var n = window.performance.now(), d = Date.now();
1.17 + ok(n >= 0, "The value of now() should be equal to or greater than 0.");
1.18 + ok(window.performance.now() >= n, "The value of now() should monotonically increase.");
1.19 + SimpleTest.waitForExplicitFinish();
1.20 +
1.21 + // The spec says performance.now() should have micro-second resolution, but allows 1ms if the platform doesn't support it.
1.22 + // Our implementation does provide micro-second resolution, except for windows XP combined with some HW properties
1.23 + // where we can't use QueryPerformanceCounters (see comments at mozilla-central/xpcom/ds/TimeStamp_windows.cpp).
1.24 + // This XP-low-res case results in about 15ms resolutions, and can be identified when perf.now() returns only integers.
1.25 + //
1.26 + // Since setTimeout might return too early/late, our goal is that perf.now() changed within 2ms
1.27 + // (or 25ms for XP-low-res), rather than specific number of setTimeout(N) invocations.
1.28 + // See bug 749894 (intermittent failures of this test)
1.29 + var platformPossiblyLowRes = navigator.oscpu.indexOf("Windows NT 5.1") == 0; // XP only
1.30 + var allInts = (n % 1) == 0; // Indicator of limited HW resolution.
1.31 + var checks = 0;
1.32 +
1.33 + function checkAfterTimeout() {
1.34 + checks++;
1.35 + var d2 = Date.now();
1.36 + var n2 = window.performance.now();
1.37 +
1.38 + allInts = allInts && (n2 % 1) == 0;
1.39 + var lowResCounter = platformPossiblyLowRes && allInts;
1.40 +
1.41 + if ( n2 == n && checks < 50 && // 50 is just a failsafe. Our real goals are 2ms or 25ms.
1.42 + ( (d2 - d) < 2 // The spec allows 1ms resolution. We allow up to measured 2ms to ellapse.
1.43 + ||
1.44 + lowResCounter &&
1.45 + (d2 - d) < 25
1.46 + )
1.47 + ) {
1.48 + setTimeout(checkAfterTimeout, 1);
1.49 + return;
1.50 + }
1.51 +
1.52 + // Loose spec: 1ms resolution, or 15ms resolution for the XP-low-res case.
1.53 + // We shouldn't test that dt is actually within 2/25ms since the iterations break if it isn't, and timeout could be late.
1.54 + ok(n2 > n, "Loose - the value of now() should increase within 2ms (or 25ms if low-res counter) (delta now(): " + (n2 - n) + " ms).");
1.55 +
1.56 + // Strict spec: if it's not the XP-low-res case, while the spec allows 1ms resolution, it prefers microseconds, which we provide.
1.57 + // Since the fastest setTimeout return which I observed was ~500 microseconds, a microseconds counter should change in 1 iteretion.
1.58 + ok(n2 > n && (lowResCounter || checks == 1),
1.59 + "Strict - [if high-res counter] the value of now() should increase after one setTimeout (hi-res: " + (!lowResCounter) +
1.60 + ", iters: " + checks +
1.61 + ", dt: " + (d2 - d) +
1.62 + ", now(): " + n2 + ").");
1.63 + SimpleTest.finish();
1.64 + };
1.65 + setTimeout(checkAfterTimeout, 1);
1.66 + </script>
1.67 +</body>
1.68 +</html>
