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#region Copyright notice and license
// Copyright 2016, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#endregion
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using Google.Protobuf;
using Grpc.Core;
using Grpc.Core.Utils;
using Grpc.Testing;
namespace Grpc.IntegrationTesting
{
public interface IInterarrivalTimer
{
void WaitForNext();
Task WaitForNextAsync();
}
/// <summary>
/// Interarrival timer that doesn't wait at all.
/// </summary>
public class ClosedLoopInterarrivalTimer : IInterarrivalTimer
{
public ClosedLoopInterarrivalTimer()
{
}
public void WaitForNext()
{
// NOP
}
public Task WaitForNextAsync()
{
return TaskUtils.CompletedTask;
}
}
/// <summary>
/// Interarrival timer that generates Poisson process load.
/// </summary>
public class PoissonInterarrivalTimer : IInterarrivalTimer
{
readonly ExponentialDistribution exponentialDistribution;
DateTime? lastEventTime;
public PoissonInterarrivalTimer(double offeredLoad)
{
this.exponentialDistribution = new ExponentialDistribution(new Random(), offeredLoad);
this.lastEventTime = DateTime.UtcNow;
}
public void WaitForNext()
{
var waitDuration = GetNextWaitDuration();
int millisTimeout = (int) Math.Round(waitDuration.TotalMilliseconds);
if (millisTimeout > 0)
{
// TODO(jtattermusch): probably only works well for a relatively low interarrival rate
Thread.Sleep(millisTimeout);
}
}
public async Task WaitForNextAsync()
{
var waitDuration = GetNextWaitDuration();
int millisTimeout = (int) Math.Round(waitDuration.TotalMilliseconds);
if (millisTimeout > 0)
{
// TODO(jtattermusch): probably only works well for a relatively low interarrival rate
await Task.Delay(millisTimeout);
}
}
private TimeSpan GetNextWaitDuration()
{
if (!lastEventTime.HasValue)
{
this.lastEventTime = DateTime.Now;
}
var origLastEventTime = this.lastEventTime.Value;
this.lastEventTime = origLastEventTime + TimeSpan.FromSeconds(exponentialDistribution.Next());
return this.lastEventTime.Value - origLastEventTime;
}
/// <summary>
/// Exp generator.
/// </summary>
private class ExponentialDistribution
{
readonly Random random;
readonly double lambda;
readonly double lambdaReciprocal;
public ExponentialDistribution(Random random, double lambda)
{
this.random = random;
this.lambda = lambda;
this.lambdaReciprocal = 1.0 / lambda;
}
public double Next()
{
double uniform = random.NextDouble();
// Use 1.0-uni above to avoid NaN if uni is 0
return lambdaReciprocal * (-Math.Log(1.0 - uniform));
}
}
}
}