1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
|
// META: timeout=long
// META: script=/resources/test-only-api.js
// META: script=resources/pressure-helpers.js
// META: global=window,dedicatedworker,sharedworker
'use strict';
pressure_test(async (t, mockPressureService) => {
const sampleIntervalInMs = 40;
const readings = ['nominal', 'fair', 'serious', 'critical'];
// Normative values for rate obfuscation parameters.
// https://w3c.github.io/compute-pressure/#rate-obfuscation-normative-parameters.
const minPenaltyTimeInMs = 5000;
const maxChangesThreshold = 100;
const minChangesThreshold = 50;
let gotPenalty = false;
await new Promise(async resolve => {
const observerChanges = [];
const observer = new PressureObserver(changes => {
if (observerChanges.length >= (minChangesThreshold - 1)) {
const lastSample = observerChanges.at(-1);
if ((changes[0].time - lastSample[0].time) >= minPenaltyTimeInMs) {
// The update delivery might still be working even if
// maxChangesThreshold have been reached and before disconnect() is
// processed.
// Therefore we are adding a flag to dismiss any updates after the
// penalty is detected, which is the condition for the test to pass.
gotPenalty = true;
observer.disconnect();
resolve();
}
}
observerChanges.push(changes);
}, {sampleInterval: sampleIntervalInMs});
observer.observe('cpu');
mockPressureService.startPlatformCollector(sampleIntervalInMs);
let i = 0;
// mockPressureService.updatesDelivered() does not necessarily match
// pressureChanges.length, as system load and browser optimizations can
// cause the actual timer used by mockPressureService to deliver readings
// to be a bit slower or faster than requested.
while (observerChanges.length <= maxChangesThreshold || !gotPenalty) {
mockPressureService.setPressureUpdate(
'cpu', readings[i++ % readings.length]);
// Allow tasks to run (avoid a micro-task loop).
await new Promise((resolve) => t.step_timeout(resolve, 0));
await t.step_wait(
() => mockPressureService.updatesDelivered() >= i,
`At least ${i} readings have been delivered`);
}
assert_true(gotPenalty, 'Penalty not triggered');
});
}, 'Rate obfuscation mitigation should have been triggered, when changes is higher than minimum changes before penalty');
|
