37 lines
1.3 KiB
Dart
37 lines
1.3 KiB
Dart
// Copyright (C) 2022 WYATT GROUP
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// Please see the AUTHORS file for details.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <https://www.gnu.org/licenses/>.
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import 'dart:core';
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import 'dart:math';
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abstract class Delay {
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static Duration getRetryDelay(int attempt) {
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assert(attempt >= 0, 'attempt cannot be negative');
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if (attempt <= 0) {
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return Duration.zero;
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}
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final rand = Random();
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const Duration delayFactor = Duration(milliseconds: 200);
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const double randomizationFactor = 0.25;
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const Duration maxDelay = Duration(seconds: 30);
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final rf = randomizationFactor * (rand.nextDouble() * 2 - 1) + 1;
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final exp = min(attempt, 31); // prevent overflows.
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final delay = delayFactor * pow(2.0, exp) * rf;
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return delay < maxDelay ? delay : maxDelay;
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}
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}
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