delay sending data

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ZeroEffect

Junior Contributor
Joined
Oct 24, 2004
Messages
204
Location
Detroit, MI
I am trying to implement a delay when send data. Because of this delay I will need to queue any data received while waiting for the delay to expire. I have everything set up I am using System.collections Queue for holding the data received while the delay is active. Once the delay has expired I check the queue and then process that data. I have all of this working. To create the delay I am processsing the data in a new thread then inside that thread I am using that thread sleep function. This works too but while this thread is sleeping then main thread sleeps too.

here is my test code.

Visual Basic: 
Imports System.Threading
Imports System.Collections

Public Class Form1
    Private Delegate Sub tbCall(ByVal tb As TextBox)

    Dim rp1Q As Queue
    Dim tRP1 As Thread
    Dim blntRP1 As Boolean = False

    Shared Sub Main()
        Application.Run(New Form1())
    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        rp1Q = New Queue(10)
        wsRecData.Bind()
    End Sub

    Private Sub wsRecData_DataArrival(ByVal sender As Object, ByVal e As AxMSWinsockLib.DMSWinsockControlEvents_DataArrivalEvent) Handles wsRecData.DataArrival
        Dim strData As Object
        wsRecData.GetData(strData)
        TextBox2.AppendText(Now & vbTab & BuildString(strData) & vbCrLf)
        ProcessData(BuildString(strData))
    End Sub

    Private Function BuildString(ByVal strData As Array) As String
        Dim temp As Long, mString As String
        mString = ""
        For temp = 0 To UBound(strData)
            mString &= Chr(strData(temp))
        Next
        Return mString
    End Function

    Private Sub ProcessData(ByVal tempData As String)
        tempData = Replace(tempData, "|", "") 'Remove Pipe
        tempData = Replace(tempData, "^", "") 'Remove Carot

        'add to cue and start processing
        'if data is to be forwarded.
        'if port is enabled cue data and start processing.
        rp1Q.Enqueue(tempData)
        If blntRP1 = False Then
            tRP1 = New Thread(AddressOf processRP1)
            tRP1.IsBackground = True
            tRP1.Start()
        End If

    End Sub

    Private Sub processRP1()
        Dim tempData As String
        blntRP1 = True
        If TextBox1.InvokeRequired Then
            Dim LogsafeSub As New tbCall(AddressOf processRP1)
            TextBox1.Invoke(LogsafeSub, TextBox1)
        Else
            Do While rp1Q.Count > 0
                'pause if there is a delay
                tRP1.Sleep(7000)

                tempData = rp1Q.Dequeue()

                wsSendData.SendData(Now & vbTab & tempData & vbCrLf)
            Loop
            blntRP1 = False
        End If
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        TextBox1.Clear()
        TextBox2.Clear()
    End Sub
End Class

Data from this application is sent correctly it is delayed 7 seconds for each item in the queue. but durring this time the main application is frozen.

Any thoughts?

Thanks

ZeroEffect

yes I will be switching to sockets when move away from the test application.
 
Re: delay sending data *update*

So for the heck of it I added this line to my project to see what happened.

Visual Basic: 
Control.CheckForIllegalCrossThreadCalls = False

and everything worked like I wanted it to. It looks like my issue has to due with haveing to use delagates and the [controlname].invoke for cross thread access to the controls and when the thread sleeps the whole thing sleeps. I know it is not a good coding to not check for these cross thread calls does anyone have a better solution?

Thanks for your help,

ZeroEffect
 
This code
Visual Basic: 
If TextBox1.InvokeRequired Then
    Dim LogsafeSub As New tbCall(AddressOf processRP1)
    TextBox1.Invoke(LogsafeSub, TextBox1)        
Else

Is making the sub processRP1 execute on the same thread that TextBox1 was created (the UI thread).
 
After many months of other projects I am able to com back to this. I was able to solve my problem by using a background worker. Now I have another seemingly sime issue and this has to do with time. I need to delay the data "x" amount of time from when it is received. sound simple. eh?

let say I have a delay of 7 seconds converted to milliseconds (7000)

data is received at 00:00:20 data out at 00:00:27

if any data is received durring the delay time it is added to a cue to be processed after the delayed data is over. In a perfect world there should be no data receieved durring the delay.

if any data came in between 00:00:20 and 00:00:27 the delay would be 7 seconds from the time it was received and not 7 second from the last time data was sent.

I am looking for suggestions for getting this delay and coverting it into the correct milliseconds.

I was thinking (#seconds to delay - ([time in] - [current time])) * 1000)

First event might look like this

(7 - (00:00:20 - 00:00:20) ) * 1000
(7 - 0) * 1000
7 * 1000 = 7000

I should not be doing math when I am tired LOL

Thanks for your thoughts.

ZeroEffect
 
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