mirror of https://github.com/grpc/grpc-dart.git
65 lines
2.4 KiB
Dart
65 lines
2.4 KiB
Dart
// Copyright (c) 2017, the gRPC project authors. Please see the AUTHORS file
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// for details. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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import 'dart:math';
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import '../shared/codec_registry.dart';
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import 'transport/http2_credentials.dart';
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const defaultIdleTimeout = Duration(minutes: 5);
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/// It seems like Google's gRPC endpoints will forcefully close the
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/// connection after precisely 1 hour. So we *proactively* refresh our
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/// connection after 50 minutes. This will avoid one failed RPC call.
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const defaultConnectionTimeOut = Duration(minutes: 50);
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const defaultUserAgent = 'dart-grpc/2.0.0';
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typedef Duration BackoffStrategy(Duration? lastBackoff);
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// Backoff algorithm from https://github.com/grpc/grpc/blob/master/doc/connection-backoff.md
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const _initialBackoff = Duration(seconds: 1);
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const _maxBackoff = Duration(seconds: 120);
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const _multiplier = 1.6;
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const _jitter = 0.2;
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final _random = Random();
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Duration defaultBackoffStrategy(Duration? lastBackoff) {
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if (lastBackoff == null) return _initialBackoff;
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final jitter = _random.nextDouble() * 2 * _jitter - _jitter;
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final nextBackoff = lastBackoff * (_multiplier + jitter);
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return nextBackoff < _maxBackoff ? nextBackoff : _maxBackoff;
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}
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/// Options controlling how connections are made on a [ClientChannel].
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class ChannelOptions {
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final ChannelCredentials credentials;
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final Duration? idleTimeout;
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final CodecRegistry? codecRegistry;
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/// The maximum time a single connection will be used for new requests.
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final Duration connectionTimeout;
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final BackoffStrategy backoffStrategy;
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final String userAgent;
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const ChannelOptions({
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this.credentials = const ChannelCredentials.secure(),
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this.idleTimeout = defaultIdleTimeout,
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this.userAgent = defaultUserAgent,
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this.backoffStrategy = defaultBackoffStrategy,
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this.connectionTimeout = defaultConnectionTimeOut,
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this.codecRegistry,
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});
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}
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