Devon Carew
b8f4b252ef
Change-Id: I75130cc8d5964ef0f95a672858da8bbce8ffd78c Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/200520 Commit-Queue: Devon Carew <devoncarew@google.com> Reviewed-by: Phil Quitslund <pquitslund@google.com>
45 lines
1.4 KiB
Dart
45 lines
1.4 KiB
Dart
// Copyright (c) 2019, 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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import 'dart:math' as math;
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/// A throttling algorithm. This models the throttling after a bucket with
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/// water dripping into it at the rate of 1 drop per replenish duration. If the
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/// bucket has water when an operation is requested, 1 drop of water is removed
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/// and the operation is performed. If not the operation is skipped. This
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/// algorithm lets operations be performed in bursts without throttling, but
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/// holds the overall average rate of operations to 1 per replenish duration.
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class ThrottlingBucket {
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final int bucketSize;
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final Duration replenishDuration;
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late int _drops = bucketSize;
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late int _lastReplenish = DateTime.now().millisecondsSinceEpoch;
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ThrottlingBucket(this.bucketSize, this.replenishDuration);
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bool removeDrop() {
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_checkReplenish();
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if (_drops <= 0) {
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return false;
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} else {
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_drops--;
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return true;
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}
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}
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void _checkReplenish() {
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int now = DateTime.now().millisecondsSinceEpoch;
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int replenishMillis = replenishDuration.inMilliseconds;
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if (_lastReplenish + replenishMillis >= now) {
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int inc = (now - _lastReplenish) ~/ replenishMillis;
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_drops = math.min(_drops + inc, bucketSize);
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_lastReplenish += (replenishMillis * inc);
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}
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}
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}
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