/// <summary>
/// Connect to the pipe for a given directory and return it.
/// Throws on cancellation.
/// </summary>
/// <param name="pipeName">Name of the named pipe to connect to.</param>
/// <param name="timeoutMs">Timeout to allow in connecting to process.</param>
/// <param name="cancellationToken">Cancellation token to cancel connection to server.</param>
/// <returns>
/// An open <see cref="NamedPipeClientStream"/> to the server process or null on failure.
/// </returns>
internal static async Task <NamedPipeClientStream> TryConnectToServerAsync(
string pipeName,
int timeoutMs,
CancellationToken cancellationToken)
{
NamedPipeClientStream pipeStream;
try
{
// If the pipe path would be too long, there cannot be a server at the other end.
// We're not using a saved temp path here because pipes are created with
// Path.GetTempPath() in corefx NamedPipeClientStream and we want to replicate that behavior.
if (IsPipePathTooLong(pipeName, Path.GetTempPath()))
{
return(null);
}
// Machine-local named pipes are named "\\.\pipe\<pipename>".
// We use the SHA1 of the directory the compiler exes live in as the pipe name.
// The NamedPipeClientStream class handles the "\\.\pipe\" part for us.
Log("Attempt to open named pipe '{0}'", pipeName);
pipeStream = NamedPipeUtil.CreateClient(".", pipeName, PipeDirection.InOut, PipeOptions.Asynchronous);
cancellationToken.ThrowIfCancellationRequested();
Log("Attempt to connect named pipe '{0}'", pipeName);
try
{
await pipeStream.ConnectAsync(timeoutMs, cancellationToken).ConfigureAwait(false);
}
catch (Exception e) when(e is IOException || e is TimeoutException)
{
// Note: IOException can also indicate timeout. From docs:
// TimeoutException: Could not connect to the server within the
// specified timeout period.
// IOException: The server is connected to another client and the
// time-out period has expired.
Log($"Connecting to server timed out after {timeoutMs} ms");
return(null);
}
Log("Named pipe '{0}' connected", pipeName);
cancellationToken.ThrowIfCancellationRequested();
// Verify that we own the pipe.
if (!NamedPipeUtil.CheckPipeConnectionOwnership(pipeStream))
{
Log("Owner of named pipe is incorrect");
return(null);
}
return(pipeStream);
}
catch (Exception e) when(!(e is TaskCanceledException || e is OperationCanceledException))
{
LogException(e, "Exception while connecting to process");
return(null);
}
}
/// <summary>
/// Connect to the pipe for a given directory and return it.
/// Throws on cancellation.
/// </summary>
/// <param name="pipeName">Name of the named pipe to connect to.</param>
/// <param name="timeoutMs">Timeout to allow in connecting to process.</param>
/// <param name="cancellationToken">Cancellation token to cancel connection to server.</param>
/// <returns>
/// An open <see cref="NamedPipeClientStream"/> to the server process or null on failure.
/// </returns>
internal static async Task <NamedPipeClientStream> TryConnectToServerAsync(
string pipeName,
int timeoutMs,
CancellationToken cancellationToken)
{
NamedPipeClientStream pipeStream;
try
{
// Machine-local named pipes are named "\\.\pipe\<pipename>".
// We use the SHA1 of the directory the compiler exes live in as the pipe name.
// The NamedPipeClientStream class handles the "\\.\pipe\" part for us.
Log("Attempt to open named pipe '{0}'", pipeName);
pipeStream = NamedPipeUtil.CreateClient(".", pipeName, PipeDirection.InOut, PipeOptions.Asynchronous);
cancellationToken.ThrowIfCancellationRequested();
Log("Attempt to connect named pipe '{0}'", pipeName);
try
{
// NamedPipeClientStream.ConnectAsync on the "full" framework has a bug where it
// tries to move potentially expensive work (actually connecting to the pipe) to
// a background thread with Task.Factory.StartNew. However, that call will merely
// queue the work onto the TaskScheduler associated with the "current" Task which
// does not guarantee it will be processed on a background thread and this could
// lead to a hang.
// To avoid this, we first force ourselves to a background thread using Task.Run.
// This ensures that the Task created by ConnectAsync will run on the default
// TaskScheduler (i.e., on a threadpool thread) which was the intent all along.
await Task.Run(() => pipeStream.ConnectAsync(timeoutMs, cancellationToken)).ConfigureAwait(false);
}
catch (Exception e) when(e is IOException || e is TimeoutException)
{
// Note: IOException can also indicate timeout. From docs:
// TimeoutException: Could not connect to the server within the
// specified timeout period.
// IOException: The server is connected to another client and the
// time-out period has expired.
Log($"Connecting to server timed out after {timeoutMs} ms");
return(null);
}
Log("Named pipe '{0}' connected", pipeName);
cancellationToken.ThrowIfCancellationRequested();
// Verify that we own the pipe.
if (!NamedPipeUtil.CheckPipeConnectionOwnership(pipeStream))
{
Log("Owner of named pipe is incorrect");
return(null);
}
return(pipeStream);
}
catch (Exception e) when(!(e is TaskCanceledException || e is OperationCanceledException))
{
LogException(e, "Exception while connecting to process");
return(null);
}
}