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51fa4aaac8
Address comments from Lasse in https://dart-review.googlesource.com/c/sdk/+/331210. Namely: * Use 100ms for the interval, so avoid overlap with the safety-margin of 40ms * Rewrite comment to only discuss the safety margin in terms of an early dispatch * Only use the safety margin on web backends. Unlike timer_test, I am using the presence of `dart.library.js` instead. Going forward it's possible that dart2wasm hits this issue if it relies on browser's timers. I also copied the changes to lib_2 since flakiness is seen there too. Change-Id: I71b6365346cccc7667dbe3da809b1bfd192ff38a Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/333057 Reviewed-by: Lasse Nielsen <lrn@google.com> Commit-Queue: Sigmund Cherem <sigmund@google.com>
55 lines
1.7 KiB
Dart
55 lines
1.7 KiB
Dart
// Copyright (c) 2011, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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library timer_test;
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import 'dart:async';
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import 'package:expect/expect.dart';
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import 'package:async_helper/async_helper.dart';
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const ms = const Duration(milliseconds: 1);
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expectGTE(min, actual, msg) {
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if (actual >= min) return;
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Expect.fail(msg.replaceAll('{0}', "$min").replaceAll('{1}', "$actual"));
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}
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main() {
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int interval = 100;
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// Most browsers can trigger timers too early. Test data shows instances where
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// timers fire even 15ms early. We add a safety margin to prevent flakiness
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// when running this test on affected platforms.
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int safetyMargin = const bool.fromEnvironment('dart.library.js') ? 40 : 0;
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asyncStart();
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var sw = new Stopwatch()..start();
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int nextTick = 1;
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bool running = true;
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var timer = new Timer.periodic(ms * interval, (t) {
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expectGTE(nextTick, t.tick, "tick {1} before expect next tick {0}.");
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nextTick += 1;
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int time = sw.elapsedMilliseconds;
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int minTime = interval * t.tick - safetyMargin;
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expectGTE(minTime, time, "Actual time {1} before {0} at tick ${t.tick}");
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if (t.tick > 20) {
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running = false;
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t.cancel();
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asyncEnd();
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}
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});
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/// Test that ticks still happen when the rest of the system is slow.
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delay() {
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int time = new DateTime.now().millisecondsSinceEpoch;
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int limit = time + 3 * interval;
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while (new DateTime.now().millisecondsSinceEpoch < limit) {
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// Idle.
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}
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nextTick = timer.tick + 2; // At least increment by two, probably more.
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if (running) Timer.run(delay);
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}
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Timer.run(delay);
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}
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