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ReconnectingNetworkStream.cs
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ReconnectingNetworkStream.cs
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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System;
using System.IO;
namespace Iot.Device.Arduino
{
internal class ReconnectingNetworkStream : Stream
{
private readonly Func<Stream> _reconnect;
private readonly object _lock = new object();
private Stream? _streamImplementation;
public ReconnectingNetworkStream(Stream? underlyingStream, Func<Stream> reconnect)
{
_streamImplementation = underlyingStream;
_reconnect = reconnect;
Connect();
}
public ReconnectingNetworkStream(Func<Stream> connect)
: this(null, connect)
{
}
public override bool CanRead => SafeExecute(x => x.CanRead, false);
public override bool CanSeek => SafeExecute(x => x.CanSeek, false);
public override bool CanWrite => SafeExecute(x => x.CanWrite, false);
public override long Length => SafeExecute(x => x.Length, false);
public override long Position
{
get
{
return SafeExecute(x => x.Position, false);
}
set
{
SafeExecute(x => x.Position = value, false);
}
}
public override void Flush() => SafeExecute(x => x.Flush(), true);
public override int Read(byte[] buffer, int offset, int count) => SafeExecute(x => x.Read(buffer, offset, count), true);
public override long Seek(long offset, SeekOrigin origin) => SafeExecute(x => x.Seek(offset, origin), true);
public override void SetLength(long value) => SafeExecute(x => x.SetLength(value), false);
public override void Write(byte[] buffer, int offset, int count) => SafeExecute(x => x.Write(buffer, offset, count), false);
private void Connect()
{
if (_streamImplementation == null)
{
lock (_lock)
{
try
{
_streamImplementation = _reconnect();
}
catch (IOException)
{
// Ignore, cannot currently reconnect. So need to retry later.
}
}
}
}
private T SafeExecute<T>(Func<Stream, T> operation, bool doThrow)
where T : struct
{
try
{
Connect();
if (_streamImplementation == null)
{
if (doThrow)
{
throw new TimeoutException("Stream is disconnected. Retrying next time.");
}
return default(T);
}
return operation(_streamImplementation);
}
catch (IOException x)
{
_streamImplementation?.Dispose();
_streamImplementation = null;
if (doThrow)
{
throw new TimeoutException("Error executing operation. Retrying next time", x);
}
return default(T);
}
}
private void SafeExecute(Action<Stream> operation, bool doThrow)
{
try
{
Connect();
if (_streamImplementation == null)
{
if (doThrow)
{
throw new TimeoutException("Stream is disconnected. Retrying next time.");
}
return;
}
operation(_streamImplementation);
}
catch (IOException x)
{
_streamImplementation?.Dispose();
_streamImplementation = null;
if (doThrow)
{
throw new TimeoutException("Error executing operation. Retrying next time", x);
}
}
}
public override void Close()
{
if (_streamImplementation != null)
{
_streamImplementation.Close();
_streamImplementation = null;
}
base.Close();
}
}
}