134 lines
3.9 KiB
C#
134 lines
3.9 KiB
C#
#region Copyright notice and license
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// Copyright 2016 gRPC authors.
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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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#endregion
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.IO;
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using System.Linq;
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using System.Text.RegularExpressions;
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using System.Threading;
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using System.Threading.Tasks;
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using Google.Protobuf;
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using Grpc.Core;
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using Grpc.Core.Utils;
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using Grpc.Testing;
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namespace Grpc.IntegrationTesting
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{
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public interface IInterarrivalTimer
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{
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void WaitForNext();
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Task WaitForNextAsync();
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}
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/// <summary>
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/// Interarrival timer that doesn't wait at all.
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/// </summary>
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public class ClosedLoopInterarrivalTimer : IInterarrivalTimer
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{
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public ClosedLoopInterarrivalTimer()
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{
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}
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public void WaitForNext()
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{
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// NOP
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}
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public Task WaitForNextAsync()
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{
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return TaskUtils.CompletedTask;
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}
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}
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/// <summary>
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/// Interarrival timer that generates Poisson process load.
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/// </summary>
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public class PoissonInterarrivalTimer : IInterarrivalTimer
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{
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readonly ExponentialDistribution exponentialDistribution;
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DateTime? lastEventTime;
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public PoissonInterarrivalTimer(double offeredLoad)
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{
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this.exponentialDistribution = new ExponentialDistribution(new Random(), offeredLoad);
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this.lastEventTime = DateTime.UtcNow;
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}
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public void WaitForNext()
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{
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var waitDuration = GetNextWaitDuration();
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int millisTimeout = (int) Math.Round(waitDuration.TotalMilliseconds);
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if (millisTimeout > 0)
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{
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// TODO(jtattermusch): probably only works well for a relatively low interarrival rate
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Thread.Sleep(millisTimeout);
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}
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}
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public async Task WaitForNextAsync()
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{
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var waitDuration = GetNextWaitDuration();
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int millisTimeout = (int) Math.Round(waitDuration.TotalMilliseconds);
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if (millisTimeout > 0)
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{
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// TODO(jtattermusch): probably only works well for a relatively low interarrival rate
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await Task.Delay(millisTimeout);
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}
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}
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private TimeSpan GetNextWaitDuration()
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{
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if (!lastEventTime.HasValue)
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{
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this.lastEventTime = DateTime.Now;
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}
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var origLastEventTime = this.lastEventTime.Value;
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this.lastEventTime = origLastEventTime + TimeSpan.FromSeconds(exponentialDistribution.Next());
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return this.lastEventTime.Value - origLastEventTime;
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}
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/// <summary>
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/// Exp generator.
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/// </summary>
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private class ExponentialDistribution
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{
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readonly Random random;
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readonly double lambda;
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readonly double lambdaReciprocal;
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public ExponentialDistribution(Random random, double lambda)
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{
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this.random = random;
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this.lambda = lambda;
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this.lambdaReciprocal = 1.0 / lambda;
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}
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public double Next()
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{
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double uniform = random.NextDouble();
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// Use 1.0-uni above to avoid NaN if uni is 0
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return lambdaReciprocal * (-Math.Log(1.0 - uniform));
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}
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}
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}
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}
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