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With a nanosecond tick counter, the elapsedMicroseconds getter could overflow if a stopwatch runs for only ~2.5 hours. Change-Id: I10cb54bba928713a3127a6bfbd19346b01d775b0 Reviewed-on: https://dart-review.googlesource.com/c/94381 Commit-Queue: Lasse R.H. Nielsen <lrn@google.com> Reviewed-by: Peter von der Ahé <ahe@google.com>
57 lines
1.8 KiB
Dart
57 lines
1.8 KiB
Dart
// Copyright (c) 2012, 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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// part of "core_patch.dart";
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@patch
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class Stopwatch {
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static const _maxInt = 0x7FFFFFFFFFFFFFFF;
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@patch
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static void _initTicker() {
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if (_frequency == null) {
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_frequency = _computeFrequency();
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}
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}
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// Returns the current clock tick.
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@patch
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static int _now() native "Stopwatch_now";
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// Returns the frequency of clock ticks in Hz.
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static int _computeFrequency() native "Stopwatch_frequency";
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@patch
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int get elapsedMicroseconds {
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int ticks = elapsedTicks;
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// Special case the more likely frequencies to avoid division,
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// or divide by a known value.
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if (_frequency == 1000000000) return ticks ~/ 1000;
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if (_frequency == 1000000) return ticks;
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if (_frequency == 1000) return ticks * 1000;
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if (ticks <= (_maxInt ~/ 1000000)) {
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return (ticks * 1000000) ~/ _frequency;
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}
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// Multiplication would have overflowed.
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int ticksPerSecond = ticks ~/ _frequency;
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int remainingTicks = ticks.remainder(_frequency);
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return ticksPerSecond * 1000000 + (remainingTicks * 1000000) ~/ _frequency;
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}
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@patch
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int get elapsedMilliseconds {
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int ticks = elapsedTicks;
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if (_frequency == 1000000000) return ticks ~/ 1000000;
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if (_frequency == 1000000) return ticks ~/ 1000;
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if (_frequency == 1000) return ticks;
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if (ticks <= (_maxInt ~/ 1000)) {
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return (ticks * 1000) ~/ _frequency;
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}
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// Multiplication would have overflowed.
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int ticksPerSecond = ticks ~/ _frequency;
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int remainingTicks = ticks.remainder(_frequency);
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return ticksPerSecond * 1000 + (remainingTicks * 1000) ~/ _frequency;
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}
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}
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