IAsyncResult not signaled in case of Session Error

[EricGarnier]

The IAsyncResult returned by Command.BeginExecute is not signaled in case of session error. Like for exemple a remote host rebooting during the command execution.
This prevent the use of .net async/await pattern like
await Task.Factory.FromAsync(command.BeginExecute, command.EndExecute, null);

To reproduce 👍 again a linux host, try this
using (var sshClient = new SshClient(connectionInfo))
{
sshClient.Connect();
using (var command = sshClient.CreateCommand(@"sleep 100000"))
{
command.CommandTimeout = TimeSpan.FromMinutes(1);
try
{
await Task.Factory.FromAsync(command.BeginExecute, command.EndExecute, null);
}
catch (Exception ex2)
{
Console.Write("Exception 1");
Console.Write(ex2.ToString());
}
}
}

While the program wait in the sleep, reboot the host.
The exception is never throw.

If you repeat this with a
command.Execute();
an exception in throw.

My analyze is that the wait handle used for session exception is not the same than the one in the IAsyncResult.

[patgauvingeek]

Salut Éric,

Even without rebooting, I can't have it to throw a SshOperationTimeoutException with FromAsync.

I used StartNewwith SshCommand.Execute to fix it. The TaskCreationOptions.LongRunning prevents a threadpool starvation situation. I don't think this option is required in all situations.

private static Task<String> ExecuteAsync(this SshCommand command)
{
  return Task<String>.Factory.StartNew(command.Execute, TaskCreationOptions.LongRunning);
}

I would really like having async/await support on SSH.Net.

[EricGarnier]

Salut Patrick Nice workaround. I already finish using the synchronous version, but your wrapper is clearly better.

[Rob-Hague]

Hi @EricGarnier, I also noticed this when working on a different problem and fixed it at the same time (#1423). It did not cross my mind that the issue had long been addressed already. I'm sorry that you went through 2 PRs without any response. I will close them out now.