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pwnall/clocks.html

Created November 28, 2013 03:02
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Experiment that measures the drift between the V8 clock and the Blink clock.
Raw
clocks.html
<!DOCTYPE html>
<script>
// Maximum difference between Blink's clock and V8's.
var maxDelta = 0;
// Measure clock differences for 30 seconds.
//
// Browsers will stop our JavaScript if it runs for too long without returning
// control to the event loop.
var smallTest = function() {
var startTime = Date.now();
var oldNow = startTime;
while (true) {
var blinkTime = (new File([], 'x.txt')).lastModifiedDate.valueOf();
var v8Time = Date.now();
var clocksDelta = Math.abs(blinkTime - v8Time);
if (maxDelta < clocksDelta) {
maxDelta = clocksDelta;
console.log("maxDelta increased to " + maxDelta);
}
if (v8Time - startTime > 30 * 1000) {
break; // Stop after 30 seconds.
}
}
};
// Call smallTest() 10 times, with 30-second breaks in between.
//
// This means the test will run for 10 minutes.
var largeTest = function() {
var runsLeft = 10;
var oneRun = function () {
smallTest();
runsLeft -= 1;
if (runsLeft === 0) {
console.log("Done");
return;
}
setTimeout(oneRun, 10);
};
oneRun();
};
largeTest();
</script>
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