Re: Threading Problem- a thread that calls two functions - C# Discussion Boards

Re: oleDB, Odbc, DataBase

18-Oct-07 4:09

If Your are using Acess it will not work !!!!!!!!!!

Try to Create A view from Access Database And the Access , will solve your problem !!!! Cool | :cool:

And now do it your self !!!!!!

Or may be try after some time by changeing your name Mad | :mad:

Very Smart !!!!! Poke tongue | ;-P

Happy Programming
-----
Abhijit

J4amieC18-Oct-07 3:54

J4amieC

18-Oct-07 3:54

Changing your name and asking the same questions doesn't mean you are going to get a different answer!

The GetSchema method returns a DataTable where each row represents the information about each element in the database. You would use this information to create queries for each of the tables - if that is the purpose.

The fact is that there is no "magic" way of getting all of the information from a database because generally this is an AWFUL idea! I have no idea why you want to do this, but i suggest you rethink why you want to do this in the first place.

---

How to get answers to your questions[^]

Re: oleDB, Odbc, DataBase

Abhijit Jana18-Oct-07 4:10

Threading Problem- a thread that calls two functions

18-Oct-07 4:10

You can Change your Name But Your Problem will remain same !!!!! Mad | :mad:

Happy Programming
-----
Abhijit

gizmokaka18-Oct-07 3:33

gizmokaka

18-Oct-07 3:33

I created a thread to which I passed two ThreadStart delegates to execute for me in the following manner.

ThreadStart myWorkerThread = (ThreadStart)Delegate.Combine(new ThreadStart(addListItemsToDisplay), new ThreadStart(checkProblematicValves));
                Thread listThread = new Thread(myWorkerThread);
                listThread.Start();

the delegate are:

public delegate void addListItemsHandler();
public delegate void checkProblematicValvesHendler();

the problem I encounter is that when executing the second function, it runs into an endless loop, only
of a reason related to the fact a different thread is running it, because if I run it from the main
thread, this doesn't occure, it simply leaves the function.

the function is:

private void checkProblematicValves()
        {
            foreach (long key in messageArr.Keys)
            {
                if (messageArr[key] != null)
                {
                    //foreach (object message in messageArr[key])
                    for (int j = 0; j < messageArr[key].Count - 1; j++ )
                    {
                        if (/*message*/messageArr[key][j] is Clusters.CSensorStatus)
                        {
                            if ((messageArr[key][j] as Clusters.CSensorStatus).valveAngDeg > 0)
                            {
                                string myKey = LongToHex(key);
                                int index = valveCheckedListBox.Items.IndexOf(myKey);
                                if (valveCheckedListBox.InvokeRequired)
                                {
                                    checkProblematicValvesHendler d = new checkProblematicValvesHendler(checkProblematicValves);
                                    valveCheckedListBox.Invoke(d);
                                }
                                valveCheckedListBox.SetItemChecked(index, true);
                            }
                        }
                    }
                    Thread.Sleep(50);
                }
            }
        }

//From here it returns to the start of the function for NO apparent reason.

Please help me!!!

thanks in advanced.

Re: Threading Problem- a thread that calls two functions

Luc Pattyn18-Oct-07 4:15

Re: Threading Problem- a thread that calls two functions

18-Oct-07 4:15

Hi,

First a comment: the line valveCheckedListBox.SetItemChecked(index, true);
should read else valveCheckedListBox.SetItemChecked(index, true);
since the SetItemChecked is not allowed by another thread.

AFAIK your thread will execute both methods once, one after the other.

The second method (checkProblematicValves) does contain an InvokeRequired/Invoke construct
which is intended to make it execute again on the thread that created valveCheckedListBox,
so yes this method may execute twice.

This construct is necessary because Controls are not thread-safe, so they should be
accessed only by the thread that created them.

Now the way you organized things is not optimal: you have several loops, and
it could happen that the InvokeRequired/Invoke construct fires multiple times,
each time causing the ENTIRE method to run again. I don't think that is what anyone would
intend.

The normal approach would be to organize the InvokeRequired/Invoke stuff outside
the first loop, hence put all the looping in the else part that I mentioned in
my first comment.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

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gizmokaka18-Oct-07 5:11

gizmokaka

18-Oct-07 5:11

Hi Luc,

The second method (checkProblematicValves) does contain an InvokeRequired/Invoke construct<br />
which is intended to make it execute again on the thread that created valveCheckedListBox,<br />
so yes this method may execute twice.

I don't understand how exactly, Invoke() works, you got me confused.
Can you please explain to me how exactly it works, what do you mean by:

<br />
causing the ENTIRE method to run again

Is the following code what you meant???

private void checkProblematicValves()
        {
            if (valveCheckedListBox.InvokeRequired)
                                {
                                    checkProblematicValvesHendler d = new checkProblematicValvesHendler(checkProblematicValves);
                                    valveCheckedListBox.Invoke(d);
                                }
            else
            {
                foreach (long key in messageArr.Keys)
                {
                    if (messageArr[key] != null)
                    {
                        foreach (object message in messageArr[key])
                        {
                            if (message is Clusters.CSensorStatus)
                            {
                                if ((message as Clusters.CSensorStatus).valveAngDeg > 0 )
                                {
                                    string myKey = LongToHex(key);
                                    int index = valveCheckedListBox.Items.IndexOf(myKey);
                                    valveCheckedListBox.SetItemChecked(index, true);
                                }
                            }
                        }
                    }
                }
            }
        }

Re: Threading Problem- a thread that calls two functions

Luc Pattyn18-Oct-07 5:27

Re: Threading Problem- a thread that calls two functions

18-Oct-07 5:27

Hi,

I have not checked all the details, but it looks pretty close, yes.

How did you come to use InvokeRequired/Invoke without really understanding it?
I suggest you read some documentation on it if you feel the need to know more.

BTW: there is one optimization you might consider; if chances are nothing needs to be done,
then there is no need to do the Invoke stuff, so you might want to duplicate the looping
stuff in front of everything and rather than invoking itself or calling SetItemChecked, just
set a bool to true to indicate the existing code should be executed.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

this months tips:
- use PRE tags to preserve formatting when showing multi-line code snippets
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gizmokaka18-Oct-07 5:48

gizmokaka

18-Oct-07 5:48

I do not understand what you meant to tell me.
I am supposed to check each and every object in the messageArr List<object> for the certain condition
and if it is true, I have to check the relevant Item in the CheckedListBox.
therefor the code must be executed any way for the best of my knowledge.
Is there something I am missing here?
do you see a situation where nothing needs to be done?
please enlighten me and tell me of which situation you speak.
how am I supposed to check the Item without calling Invoke?

Re: Threading Problem- a thread that calls two functions

Luc Pattyn18-Oct-07 6:58

Any idea about how to work with IM?

18-Oct-07 6:58

Hi,

1.
your code seems OK.
I trust you have it working?

2.
what I meant to tell you was maybe your code runs even at times that there are
no messages, or all tests (valveAngDeg > 0) will fail, so nothing needs to be changed
in the GUI. If so, there was no need to let the GUI thread execute the function,
so if that is relevant you could do something like this (in pseudo-code):

void checkProblematicValvesNew() {
    bool GuiChangeNeeded=false;
    foreach(thing to be checked) {
        if (GUI indeed needs a change) GuiChangeNeeded=true;
    }
    if (GuiChangeNeeded) {
        checkProblematicValves();  // call the existing method
    }
}

but probably it is not really worth the effort...

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

this months tips:
- use PRE tags to preserve formatting when showing multi-line code snippets
- before you ask a question here, search CodeProject, then Google

baburman18-Oct-07 3:33

baburman

18-Oct-07 3:33

Hi guys,

Anybody knows how to work with the currently opened IM chat sessions (both msn and yahoo)? I need to develop a windows application, most probably in C# or VC, in which the messages coming in and out from the IM sessions need to be grabbed and recorded. This is required to be done in the backend. Please help me if anybody has worked on such or similar thing before.

Reference to any article or site which helps in this connection will also be appreciated.

Thankyou,

bABURmAN

Abhijit Jana18-Oct-07 3:51

18-Oct-07 3:51

Hope This link will help You !!!!
http://www.devcity.net/Articles/41/1/msn_msngr.aspx[^]
Or u can also check this one
http://www.codeproject.com/dotnet/msgaddin.asp[^]

Happy Programming
-----
Abhijit

baburman18-Oct-07 6:36

baburman

18-Oct-07 6:36

Lots of Thanks Abhijit. These are good examples of getting the status or text etc. I just went through them but didn't yet run them on my machine. I hope they will run ok but here i need to control like

1- if a user can start IM session,
2- a use can send/receive files,
3- a user can have a chat session with certain user(s).

Similarly i need to have a log of how much time a session was continued etc. Is it possible through this interface?

bABURmAN

User 665818-Oct-07 3:56

User 6658

18-Oct-07 3:56

Basically, you have three choices:

1) write a network packet sniffer and capture the packets that are necessary for you
2) use the official APIs of these messengers, if available
3) using some P/Invoke you can find the message windows using FindWindow(Ex) and grab the text using WM_GETTEXT or other techniques

regards

modified 12-Sep-18 21:01pm.

Abhijit Jana18-Oct-07 4:51

18-Oct-07 4:51

Hi Greeeg,
Could u kindly explain in details ???

Thanks in advance !!! Rose | [Rose]

Happy Programming
-----
Abhijit

gloabal variable

kabutar18-Oct-07 3:18

kabutar

18-Oct-07 3:18

hi ,
in this code i dont want to declare the result as a static gloabl variable..why are doing so and how can i avoid doing that...

class Program
{
static int result;

public int add(int x,int y)
{
result = x+y;
return result;
}

static void Main(string[] args)
{
Program obj = new Program();
int sum = obj.add(10, 20);

Console.WriteLine("{0}", result);

Console.WriteLine("{0}", sum);
Console.ReadLine();

}
}
}
thanks

Abhijit Jana18-Oct-07 3:43

18-Oct-07 3:43

I thing from the output of your code you will get your ans Sigh | :sigh:

Happy Programming
-----
Abhijit

kabutar18-Oct-07 3:51

kabutar

18-Oct-07 3:51

am sorry but i didnot understand what u said abhijith
am a beginner and can u explain tis to me plzz
thansk

rajansethi18-Oct-07 4:52

rajansethi

18-Oct-07 4:52

just replace add method with

public int add(int x,int y)
{
return x+y;
}

And remove the global variable result from the code

Luc Pattyn18-Oct-07 4:02