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comparison: dom/tests/mochitest/general/test_performance_now.html
dom/tests/mochitest/general/test_performance_now.html
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| -1:000000000000 | 0:02b8a1d6f2fa |
|---|---|
| 1 <!DOCTYPE HTML> | |
| 2 <html> | |
| 3 <head> | |
| 4 <title>Test for High Resolution Timer</title> | |
| 5 <script type="text/javascript" src="/MochiKit/MochiKit.js"></script> | |
| 6 <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script> | |
| 7 <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" /> | |
| 8 </head> | |
| 9 <body> | |
| 10 <script> | |
| 11 ok(window.performance, "Performance object should exist."); | |
| 12 ok(typeof window.performance.now == 'function', "Performance object should have a 'now' method."); | |
| 13 var n = window.performance.now(), d = Date.now(); | |
| 14 ok(n >= 0, "The value of now() should be equal to or greater than 0."); | |
| 15 ok(window.performance.now() >= n, "The value of now() should monotonically increase."); | |
| 16 SimpleTest.waitForExplicitFinish(); | |
| 17 | |
| 18 // The spec says performance.now() should have micro-second resolution, but allows 1ms if the platform doesn't support it. | |
| 19 // Our implementation does provide micro-second resolution, except for windows XP combined with some HW properties | |
| 20 // where we can't use QueryPerformanceCounters (see comments at mozilla-central/xpcom/ds/TimeStamp_windows.cpp). | |
| 21 // This XP-low-res case results in about 15ms resolutions, and can be identified when perf.now() returns only integers. | |
| 22 // | |
| 23 // Since setTimeout might return too early/late, our goal is that perf.now() changed within 2ms | |
| 24 // (or 25ms for XP-low-res), rather than specific number of setTimeout(N) invocations. | |
| 25 // See bug 749894 (intermittent failures of this test) | |
| 26 var platformPossiblyLowRes = navigator.oscpu.indexOf("Windows NT 5.1") == 0; // XP only | |
| 27 var allInts = (n % 1) == 0; // Indicator of limited HW resolution. | |
| 28 var checks = 0; | |
| 29 | |
| 30 function checkAfterTimeout() { | |
| 31 checks++; | |
| 32 var d2 = Date.now(); | |
| 33 var n2 = window.performance.now(); | |
| 34 | |
| 35 allInts = allInts && (n2 % 1) == 0; | |
| 36 var lowResCounter = platformPossiblyLowRes && allInts; | |
| 37 | |
| 38 if ( n2 == n && checks < 50 && // 50 is just a failsafe. Our real goals are 2ms or 25ms. | |
| 39 ( (d2 - d) < 2 // The spec allows 1ms resolution. We allow up to measured 2ms to ellapse. | |
| 40 || | |
| 41 lowResCounter && | |
| 42 (d2 - d) < 25 | |
| 43 ) | |
| 44 ) { | |
| 45 setTimeout(checkAfterTimeout, 1); | |
| 46 return; | |
| 47 } | |
| 48 | |
| 49 // Loose spec: 1ms resolution, or 15ms resolution for the XP-low-res case. | |
| 50 // We shouldn't test that dt is actually within 2/25ms since the iterations break if it isn't, and timeout could be late. | |
| 51 ok(n2 > n, "Loose - the value of now() should increase within 2ms (or 25ms if low-res counter) (delta now(): " + (n2 - n) + " ms)."); | |
| 52 | |
| 53 // Strict spec: if it's not the XP-low-res case, while the spec allows 1ms resolution, it prefers microseconds, which we provide. | |
| 54 // Since the fastest setTimeout return which I observed was ~500 microseconds, a microseconds counter should change in 1 iteretion. | |
| 55 ok(n2 > n && (lowResCounter || checks == 1), | |
| 56 "Strict - [if high-res counter] the value of now() should increase after one setTimeout (hi-res: " + (!lowResCounter) + | |
| 57 ", iters: " + checks + | |
| 58 ", dt: " + (d2 - d) + | |
| 59 ", now(): " + n2 + ")."); | |
| 60 SimpleTest.finish(); | |
| 61 }; | |
| 62 setTimeout(checkAfterTimeout, 1); | |
| 63 </script> | |
| 64 </body> | |
| 65 </html> |
