Re: Displaying a message while executing a function - C# Discussion Boards

Steve Messer14-Dec-05 12:02

Steve Messer

14-Dec-05 12:02

Thanks I will try that directly

WillemM14-Dec-05 9:20

WillemM

14-Dec-05 9:20

Sounds rather complex, let me think:

Every process should have some kind of semaphore. GetData2 should call wait on the semaphore of GetData1. GetData1 should call signal on the semaphore it has, so that GetData2 continues. GetData3 should call wait on the semaphore of GetData2 and GetData2 should call signal on the semaphore it has, to let GetData3 continue.

This should work just fine and you dont have to worry about a lot of the synchronisation here Smile | :)

There are other ways to do this, but this is by far the simplest solution I can think of.

WM.

What about weapons of mass-construction?

-- modified at 15:21 Wednesday 14th December, 2005 (Fixed some minor spelling issues Poke tongue | ;-P

)

Robert Rohde14-Dec-05 10:43

Robert Rohde

14-Dec-05 10:43

Although it seems you already found a solution just another question:
If those three threads get executed sequentially (one after the other) why don't you just call all three methods in a single thread?

Steve Messer14-Dec-05 11:17

Steve Messer

14-Dec-05 11:17

Worth a look, thanks

Displaying a message while executing a function

Steve Messer14-Dec-05 16:40

Steve Messer

14-Dec-05 16:40

I used a combination of both tips

ThreadStart method1 = new ThreadStart(DoRequests); 
AsyncCallback callback = new AsyncCallback(MyCallbackFunction);
method1.BeginInvoke(callback, null);

void DoRequests()
{
   RequestVehicles();
   RequestCustomers();
   RequestServiceSales();
}

void MyCallbackFunction(IAsyncResult result)
{
   if( result.IsCompleted )
   {
      // All data received add to database or whatever
   }
}

Thanks All

apoc50314-Dec-05 9:00

Re: Displaying a message while executing a function

14-Dec-05 9:00

I made a windows form app that executes a query to an Oracle database. It takes about 5 seconds for the query to execute. If a user presses the button and it takes 5 seconds, they might think its not working.

I want to display a message while it executes the query. The whole query is wrapped up in a function called “ConnectToOracle()”. Obviously it is of type void. I tried to make a while loop that did this…

ConnectToOracle();<br />
<br />
While (ConnectToOracle)<br />
<br />
{<br />
<br />
            Label1.visible = true;      <br />
<br />
}

It gave me an error that said cannot implicitly convert type ‘void’ to ‘bool’.

Is there anyway I can do this??

Thank you!

Apoc

Dan Neely14-Dec-05 9:08

Dan Neely

14-Dec-05 9:08

Alternately put the label display calls inside ConnectToOracle() on either side of the db operations. You should consider doing this in a seperate thread though so it doesn't lock the GUI.

<br />
void ConnectAndShowWait()<br />
{<br />
Label1.visible = true;<br />
<br />
ConnectToOracle();<br />
<br />
Label1.visible = false;<br />
}

Re: Displaying a message while executing a function

Judah Gabriel Himango14-Dec-05 9:09

Judah Gabriel Himango

14-Dec-05 9:09

A while clause expects a boolean value. while(somethingIsTrueOrFalse). Since ConnectToOracle is returning void, while won't work.

What you need is a seperate thread of execution to connect to the database, keeping your UI thread alive and functional. To do this:

using System.Threading;

// Right now we're on the UI thread. Let's start another thread of execution that goes over to Oracle and reads the data.
ThreadStart methodToExecute = new ThreadStart(ConnectToOracle);
Thread oracleReaderThread = new Thread(methodToExecute);
oracleReaderThread.Start();

This will keep your UI thread responsive because it's not actually doing anything. The background oracleReaderThread will begin executing in the background.

Tech, life, family, faith: Give me a visit.
I'm currently blogging about: Bought a House!
Judah Himango

Re: Displaying a message while executing a function

apoc50314-Dec-05 10:24

Re: Displaying a message while executing a function

14-Dec-05 10:24

Wow! That made a huge difference! Thanks so much!

Apoc

Judah Gabriel Himango14-Dec-05 10:43

Judah Gabriel Himango

14-Dec-05 10:43

Don't be fooled about speed difference. It will still take just as long (in fact, probably longer on a single-processor machine) to read the data from the database. It's just that the reading won't block your UI thread, which makes everything appear responsive & fast. Users like this. Just beware that multithreading can get very hairy; threads sharing states, threads accessing the same resource, locking & deadlocks, doing UI stuff on background threads, all are difficulties you'll run into if you use threads. I suggest you do some reading[^] on the subject.

Re: Displaying a message while executing a function

Robert Rohde14-Dec-05 10:46

Robert Rohde

14-Dec-05 10:46

You could also display a wait cursor:

try {
Cursor.Current = Cursor.Wait;
ConnectToOracle();
} finally {
Cursor.Current = Cursor.Default;
}

Re: Displaying a message while executing a function

apoc50314-Dec-05 11:09

Re: Displaying a message while executing a function

14-Dec-05 11:09

I tried that and it said it did not recognize Wait and Default. Am I using an old version of .net? Is this only for 2.0?

Apoc

Robert Rohde14-Dec-05 11:47

Robert Rohde

14-Dec-05 11:47

No i was a just a bit too quick:

try  {
   Cursor.Current = Cursors.WaitCursor;
   ConnectToOracle();
} 
finally {
   Cursor.Current = Cursors.Default;
}

Now it should compile Smile | :)

Re: Displaying a message while executing a function

apoc50314-Dec-05 11:50

Re: Displaying a message while executing a function

14-Dec-05 11:50

Ah.. that worked!

Thanks!

Apoc

User 665814-Dec-05 13:20

User 6658

14-Dec-05 13:20

Visual Studio's intellisense function would actually have shown you other cursor-options in a listbox. Use it! Smile | :)

modified 12-Sep-18 21:01pm.

Re: Displaying a message while executing a function

MudkiSekhon14-Dec-05 23:32

MudkiSekhon

14-Dec-05 23:32

You can show a Progress bar to the user which increments its value by 20 for every second. When 5 seconds will complete, the progress bar will reach 100 i.e. maximum. By this way the user will be assured that something is going on and he will be satisfied

Regards
Sandeep
+919891027854

A student knows little about a lot.
A professor knows a lot about little.
I know everything about nothing.

File delete on browser close

chinky singh14-Dec-05 7:49

14-Dec-05 7:49

Hi

I am working in ASP.net and C#. I have a result.aspx page. I have to delete a file if the result.aspx page is closed or even if the user just moves from result.aspx page and goes to another page in the application. Could somebody please suggest some solution to this problem.

Any help would be appreciated.

Thanks
Chinky

enjoycrack14-Dec-05 8:36

enjoycrack

14-Dec-05 8:36

Hi there,

In the Page_Unload event....

<< >>

chinky singh14-Dec-05 9:12

14-Dec-05 9:12

Hi
Page_UnLoad event is not called when I close the browser. I am not able to delete file in the Page_UnLoad event.

WillemM14-Dec-05 9:25

WillemM

14-Dec-05 9:25

You can detect when the session ends in Global.asax
But it depends on how you work with the file, is it per session or per page?

WM.

What about weapons of mass-construction?

enjoycrack14-Dec-05 10:25

enjoycrack

14-Dec-05 10:25

In this case, you have to implement some js code in the onUnload event at client-side...
This link OnUnload event might help u...

<< >>

chinky singh15-Dec-05 3:45

15-Dec-05 3:45

I have never worked with javascript. Is their a way to delete a file in javascript.

I have tried the following in javascript:

var fso = new ActiveXObject("Scripting.FileSystemObject");
fso.DeleteFile(filepath + filename, true);

But this didnt delete a file.

chinky singh15-Dec-05 3:59

15-Dec-05 3:59

is their anyway to call an aspx page from javascript.

chinky singh15-Dec-05 5:59

15-Dec-05 5:59

Hi

I am able to catch the browser closing event using javascript. Then I am redirecting the user to another aspx page, which has a code to delete the files.

// default.aspx: javascript function being called at onunload event.
function deleteFile()
{
window.open("test.aspx");
}

// test.aspx page
File.Delete("C:\\test.txt); // delete the file
// close the test.aspx page
string strscript = "window.top.close();";
if (!Page.IsStartupScriptRegistered("clientScript"))
{
Page.RegisterStartupScript("clientScript", strscript);
}

This method opens the test.aspx page for few seconds, deletes the file and closes the page.

Is their anyway that I can hide the test.aspx page so that the user cannot see that but still file gets deleted ?

And what if the javascipt is disabled at the user's browser. In that case no files will be deleted.

Any suggestions??