private static CirceComConnection TryCreateOpenedConnection([NotNull] string portName,
[CanBeNull] Action<CirceComConnection> attachHandlersCallback,
[CanBeNull] Action<CirceComConnection> detachHandlersCallback)
{
CirceComConnection connection = null;
Exception error;
try
{
connection = new CirceComConnection(portName);
attachHandlersCallback?.Invoke(connection);
connection.Open();
return connection;
}
catch (InvalidOperationException ex)
{
// This may happen when you unplug the serial port cable while writing to the port.
// The exception indicates that the port has been closed, so writing fails.
error = ex;
}
catch (UnauthorizedAccessException ex)
{
error = ex;
}
catch (SecurityException ex)
{
error = ex;
}
catch (IOException ex)
{
error = ex;
}
Log.Debug($"Failed to open port {portName}: {error.GetType()}: {error.Message}");
if (connection != null)
{
detachHandlersCallback?.Invoke(connection);
connection.Dispose();
}
return null;
}
private void CreateSession()
{
Log.Debug("Entering CreateSession.");
// Block until we have successfully sent a Login operation.
Exception connectError;
CirceComConnection newConnection;
do
{
// Block until we have obtained a COM port.
bool raisedWaitEvent = false;
Log.Debug("Entering wait loop until at least one port found.");
#if DEBUGGING_HACKS
string comPortName = "COM3"; // Force single COM port
#else
string comPortName = portRotator.GetNextPortName();
#endif
while (comPortName == null)
{
if (disposeRequestedWaitHandle.IsSet)
{
Log.Debug("CreateSession: Disposal has been requested while scanning for ports.");
OnStateChanged(ControllerConnectionState.Disconnected, null);
return;
}
if (!raisedWaitEvent)
{
OnStateChanged(ControllerConnectionState.WaitingForComPort, null);
raisedWaitEvent = true;
}
Thread.Sleep(TryNextComPortDelayInMilliseconds);
comPortName = portRotator.GetNextPortName();
}
if (disposeRequestedWaitHandle.IsSet)
{
Log.Debug("CreateSession: Disposal has been requested after port detection.");
OnStateChanged(ControllerConnectionState.Disconnected, null);
return;
}
OnStateChanged(ControllerConnectionState.Connecting, comPortName);
seenProtocolVersionMismatch.Value = null;
newConnection = new CirceComConnection(comPortName);
newConnection.PacketSending += NewConnectionOnPacketSending;
newConnection.PacketReceived += NewConnectionOnPacketReceived;
newConnection.OperationReceived += NewConnectionOnOperationReceived;
// The caller has closed a previous connection and paused the outgoing queue. So we
// are guaranteed to be the only thread that is writing to the port. So locking
// for exclusive write access is not needed here.
if (TryDirectSend(newConnection, true, new LoginOperation(), out connectError))
{
// A KeepAlive response should be received shortly, so we'll set the lifetime to one
// second in the past, which leaves a single second for the mediator to respond.
lastRefreshTimeInUtc.Value = SystemContext.UtcNow().AddSeconds(-1);
}
if (connectError != null)
{
Log.Warn($"Failed to open port {comPortName} and send Login operation.", connectError);
// Because the lifetime of this instance is longer than the lifetime of a connection, it
// is critical to detach event handlers so the garbage collector can run. Failing to detach
// event handlers will cause a memory leak that increases at each reconnect.
newConnection.PacketSending -= NewConnectionOnPacketSending;
newConnection.PacketReceived -= NewConnectionOnPacketReceived;
newConnection.OperationReceived -= NewConnectionOnOperationReceived;
newConnection.Dispose();
OnStateChanged(ControllerConnectionState.Disconnected, comPortName);
}
}
while (connectError != null);
activeConnection.Value = newConnection;
}