[RESOLVED] Strange UDP Issue

[Shaggy Hiker]

Here's a UDP class:

Public Class UDPCommon
    Implements IDisposable
 
    'The UDP listening components.
    Private WithEvents locUDP As System.Net.Sockets.Socket
    Private WithEvents locUDPOut As System.Net.Sockets.UdpClient
    Private ThreadListen As New Threading.Thread(AddressOf WaitForPending)
    Private timeCount As Integer
    Private broad As System.Net.IPEndPoint
 
 
    'The dataQueue
    Private dgList As Queue(Of DataGramReceiver)
 
    'The result
    Private disposedValue As Boolean = False        ' To detect redundant calls
 
    'Synchronization.
    Private Shared myContext As System.Threading.SynchronizationContext
 
#Region "Constructors and Destructors"
 
    Public Sub New()
        'Set up the queue.
        dgList = New Queue(Of DataGramReceiver)
        locUDPOut = New Net.Sockets.UdpClient(11013)
        locUDP = New Net.Sockets.Socket(Net.Sockets.AddressFamily.InterNetwork, Net.Sockets.SocketType.Dgram, Net.Sockets.ProtocolType.Udp)
        locUDP.SetSocketOption(Net.Sockets.SocketOptionLevel.Socket, Net.Sockets.SocketOptionName.ReuseAddress, True)
        locUDP.Bind((New Net.IPEndPoint(Net.IPAddress.Any, 11013)))
 
        locUDPOut.EnableBroadcast = True
 
        broad = New System.Net.IPEndPoint(System.Net.IPAddress.Broadcast, 11013)
 
        myContext = System.Threading.SynchronizationContext.Current
 
        'Start listening.
        ThreadListen.Name = "Listening Thread"
        ThreadListen.Start()
    End Sub
 
    ' IDisposable
    Protected Overridable Sub Dispose(ByVal disposing As Boolean)
        If Not Me.disposedValue Then
            If disposing Then
                ThreadListen.Abort()
                locUDP.Close()
                locUDPOut.Close()
            End If
 
            ' TODO: free shared unmanaged resources
        End If
        Me.disposedValue = True
    End Sub
 
#Region " IDisposable Support "
    ' This code added by Visual Basic to correctly implement the disposable pattern.
    Public Sub Dispose() Implements IDisposable.Dispose
        ' Do not change this code.  Put cleanup code in Dispose(ByVal disposing As Boolean) above.
        Dispose(True)
        GC.SuppressFinalize(Me)
    End Sub
#End Region
 
#End Region
 
#Region "Properties and Events"
 
    Public Event MessageIn()
 
    Public ReadOnly Property MessageCount() As Integer
        Get
            Return dgList.Count
        End Get
    End Property
 
    Public ReadOnly Property NextMessage() As DataGramReceiver
        Get
            Return dgList.Dequeue
        End Get
    End Property
 
#End Region
 
#Region "Public Functions"
 
    'This will get the next DGR from the queue.
    Public Function GetNext() As DataGramReceiver
        Dim dgRet As New DataGramReceiver
 
        Threading.Monitor.Enter(Me)
        Try
            If dgList.Count > 0 Then
                dgRet = New DataGramReceiver(dgList.Dequeue)
            End If
        Catch ex As Exception
            Windows.Forms.MessageBox.Show(ex.Message, "Error Getting DataGramReceiver", MessageBoxButtons.OK, MessageBoxIcon.Error)
        Finally
            Threading.Monitor.Exit(Me)
        End Try
 
        'It may be the default, or it may not, either way it is a good local copy in the calling thread, return it.
        Return dgRet
 
    End Function
 
    'Empties the queue
    Public Sub Flush()
        Threading.Monitor.Enter(Me)
        Try
            dgList.Clear()
        Finally
            Threading.Monitor.Exit(Me)
        End Try
    End Sub
 
    Public Sub SendMessage(ByVal btArr() As Byte, ByVal toWho As Byte, ByVal what As Byte)
        Dim lBtArr(btArr.Length + 2) As Byte
 
        lBtArr(0) = 100 'This is the OL ID.
        lBtArr(1) = toWho
        lBtArr(2) = what
 
        System.Array.Copy(btArr, 0, lBtArr, 3, btArr.Length)
        'NOTE: NEED TO CHECK THAT THIS IS DOING AS IT SHOULD.
 
        locUDP.SendTo(lBtArr, lBtArr.Length, Net.Sockets.SocketFlags.Broadcast, broad)
 
    End Sub
 
#End Region
 
#Region "Private Functions"
 
    Private Sub WaitForPending()
        Dim bHolder(511) As Byte
        Dim numIn As Integer
        Dim dgRec As DataGramReceiver
        Dim bTrans() As Byte
 
        While True
            If CBool(locUDP.Available) Then
                numIn = locUDP.Receive(bHolder, 512, Net.Sockets.SocketFlags.None)
                If numIn > 4 Then
                    If bHolder(1) = 0 OrElse bHolder(1) = 100 Then
                        'Set the holder up to the right size.
                        ReDim bTrans(numIn)
                        Array.Copy(bHolder, 3, bTrans, 0, numIn - 3)
                        dgRec = New DataGramReceiver(128, bHolder(2), bTrans)
                        Add(dgRec)
                    End If
                End If
            End If
        End While
    End Sub
 
    'Adds one DGR to the queue
    Private Sub Add(ByVal dgR As DataGramReceiver)
        'Set the monitor.
        Threading.Monitor.Enter(Me)
        Try
            dgList.Enqueue(dgR) 'That's all that happens.
        Finally
            Threading.Monitor.Exit(Me)
        End Try
        myContext.Post(AddressOf GotData, Nothing)
    End Sub
 
    'This is invoked by the other thread.
    Private Sub GotData(ByVal state As Object)
        RaiseEvent MessageIn()
    End Sub
 
 
#End Region
 
End Class

The intention for this class is that it will be included in multiple modules on multiple computers. I have tried it on two different computers, but not in talking to each other, I haven't gotten that far. On both computers I have projects that have an instance of this class along with an instance of a class that is similar, but uses two ports rather than one, because that other class will have only one module writing to one port and listening to the other port, while all the other modules will listen to the first port and write to the second. That was working fine with two modules...now we'll see, but not yet.

Therefore, on both systems there is one instance of this class, and one instance of the class with two ports. On the system running XP Home (I have no idea whether or not that matters), if I step through the two lines that create the instances of the two classes, the first class is created pretty much instantly, while the class posted above takes a tiny fraction of a second. There is a hesitation, but it is very brief.

On the system running XP Pro, the two port class is also created instantly. Both classes are in Try blocks for various reasons, but the first class is created without any issues. When I step over the line that creates the class posted above, there is a pause of a second or two (which is an ENORMOUS length of time), then the next line highlighted is a function in the catch block, but the function isn't executed, and no exception was actually raised. I've NEVER seen this happen before, where VS will incorrectly highlight the next line.

If I run this without adding a breakpoint, the form takes up to five seconds to be displayed. Since there is nothing else that takes any time, I assume the entire issue is the class posted above. Frankly, I've tinkered around with this class so many times by now that I forget whether it is even actually valid now, but it throws no exceptions.

If I step through the creation of the class, there are a few minor pauses, such as when the constructor starts the listener thread, but the pauses are minor. The delay occurs after the New sub returns, and the execution highlight is, again, taken to the first line in the catch block, though no exception was raised, and the line in the catch block is not actually executed.

Any suggestions? Any alternatives? The key is to have a class that can read and write to a single port using UDP, and created such that there could be multiple instances of the class in different modules, all running simultaneously on the same system.