Re: How to close all form but not application.exit() - C# Discussion Boards

Re: How to close all form but not application.exit()

11-Feb-10 5:01

hi,

i have a main form. it has list view of items that when clicked will open up another form without closing the main form.

i did a inactivity timeout where user will be require to login again. if that happen, how do i close all current open form??

N a v a n e e t h11-Feb-10 5:06

N a v a n e e t h

11-Feb-10 5:06

You need to keep form objects that are open in a collection. When relogin requires, loop through this list and dispose everything.

Best wishes,
Navaneeth

Re: How to close all form but not application.exit()

OriginalGriff11-Feb-10 5:09

Re: How to close all form but not application.exit()

11-Feb-10 5:09

N a v a n e e t h wrote:
loop through this list and ~~dispose~~ closeeverything.

Don't use dispose on a form that is currently displayed - unpredictable things may occur!

If Barbie is so popular, why do you have to buy her friends?

Eagles may soar, but weasels don't get sucked into jet engines.

If at first you don't succeed, destroy all evidence that you tried.

N a v a n e e t h11-Feb-10 5:24

N a v a n e e t h

11-Feb-10 5:24

When I say dispose everything, I didn't meant to call Dispose() method. BTW, how it can cause unpredictable things? Confused | :confused:

Best wishes,
Navaneeth

Re: How to close all form but not application.exit()

OriginalGriff11-Feb-10 5:38

Re: How to close all form but not application.exit()

11-Feb-10 5:38

If the form has a background thread working, it could be using resources that you have disposed.

If Barbie is so popular, why do you have to buy her friends?

Eagles may soar, but weasels don't get sucked into jet engines.

If at first you don't succeed, destroy all evidence that you tried.

OriginalGriff11-Feb-10 5:08

Re: How to close all form but not application.exit()

11-Feb-10 5:08

Application.OpenForms will return a Forms[] for all open forms. You can for loop through it closing the ones you no longer need (with Form.Close(), obviously). Do not try to foreach loop through, as the Close() may remove it from the array.

If Barbie is so popular, why do you have to buy her friends?

Eagles may soar, but weasels don't get sucked into jet engines.

If at first you don't succeed, destroy all evidence that you tried.

nuttynibbles11-Feb-10 5:21

Re: How to close all form but not application.exit()

11-Feb-10 5:21

im implementing windows mobile using compact framework so there isn't application.openforms.

is there something else similar?

OriginalGriff11-Feb-10 5:32

Re: How to close all form but not application.exit()

11-Feb-10 5:32

Not unless you create it yourself - keep a copy of the form object when you do the create, chain into the FormClosing event and remove it when it closes. You can then manually Close() each open instance.

If Barbie is so popular, why do you have to buy her friends?

Eagles may soar, but weasels don't get sucked into jet engines.

If at first you don't succeed, destroy all evidence that you tried.

nuttynibbles11-Feb-10 5:46

Re: How to close all form but not application.exit()

11-Feb-10 5:46

hi OriginalGriff,

what you mean is to create a class which act as a application hub that store all created form instances??

im sorry but wat do u mean by chain into the formClosing event?

OriginalGriff11-Feb-10 5:55

Re: How to close all form but not application.exit()

11-Feb-10 5:55

Store them as part of your main form, as either an array of Form objects, or as individual YourForm references. At the moment, you do something like

YourForm yf = new YourForm();
yf.Show();

when the use clicks one of your list view entries - just move the "YourForm yf" outside the method (and give it a better name).
You then change it to

yf = new YourForm();
yf.FormClosing += new EventHandler(YourFormClosing);
yf.Show();

and add

private void YourFormClosing(object sender, EventArgs e)
   {
   yf = null;
   }

to remove it when it closes.
You can then check

if (yf != null)
   {
   yf.Close();
   }

If Barbie is so popular, why do you have to buy her friends?

Eagles may soar, but weasels don't get sucked into jet engines.

If at first you don't succeed, destroy all evidence that you tried.

nuttynibbles11-Feb-10 6:02

Re: How to close all form but not application.exit()

11-Feb-10 6:02

hmm okay i will go try it out. tks again Original Griff

#realJSOP11-Feb-10 6:00

#realJSOP

11-Feb-10 6:00

You could simply call Form.Hide() instead of closing the forms outright.

Re: How to close all form but not application.exit()

SilimSayo11-Feb-10 9:17

SilimSayo

11-Feb-10 9:17

If the forms are mdi forms,look at this http://www.codeproject.com/Messages/849885/Re-Closing-all-mdichildren-forms.aspx[^]

Using Semaphore for multiple threads....

Jacob Dixon11-Feb-10 4:45

11-Feb-10 4:45

Let me first start with what I am trying to accomplish and what I have.

I created a computer management console for active directory. You launch, it gets all computer objects from AD. When you click the computer object, some panels become visible and thre are 3 listbviews. One for Installed Applications, One for Services, and one for Hard drive information. All of that information is retrieved by WMI.

So the way I have it is when you click a computer object, it attempts to contact the computer using seperate threads for each thing (applications, services, hd info).

I have something like this:

// Threading for getting WMI information
Thread m_workerThread1;
Thread m_workerThread2;
Thread m_workerThread3;
Semaphore resourceLock;

When you click comp:

if (m_workerThread1 != null && m_workerThread1.IsAlive)
    m_workerThread1.Abort();

if (m_workerThread2 != null && m_workerThread2.IsAlive)
    m_workerThread2.Abort();

if (m_workerThread3 != null && m_workerThread3.IsAlive)
    m_workerThread3.Abort();

lstServices.BeginUpdate();
lstServices.Items.Clear();

m_workerThread1 = new Thread(new ParameterizedThreadStart(GetRunningServices));
m_workerThread1.IsBackground = true;
m_workerThread1.Start(comp.DnsHostName);

lstApplications.BeginUpdate();
lstApplications.Items.Clear();

m_workerThread2 = new Thread(new ParameterizedThreadStart(GetInstalledApps));
m_workerThread2.IsBackground = true;
m_workerThread2.Start(comp.DnsHostName);

lstDiskDrives.BeginUpdate();
lstDiskDrives.Items.Clear();

m_workerThread3 = new Thread(new ParameterizedThreadStart(GetCompInfo));
m_workerThread3.IsBackground = true;
m_workerThread3.Start(comp.DnsHostName);

And under each method (you see I am calling three different ones) I am using the resourceLock.WaitOne(); and under a try catch finally (in the finally) I am releasing it.

You might be wondering why I call abort. This is because I really couldn't think of a better way to abort the current operation if the user clicks another computer. Having it wait until its done before letting the user choose another computer really isn't an option (because WMI can take a while sometimes).

My problem is if you close the form while these threads are running. Right now I forgot to include anything for it and it causes teh app to crash.

Is there a good way to abort these and then close? Like without displaying a message for the user to wait and try again until it aborts? What is the "best practice" for handling something like this? Or did I just mess the whole system up the way I did it?

N a v a n e e t h11-Feb-10 5:22

N a v a n e e t h

11-Feb-10 5:22

Looks like you are not clear about what a Semaphore does. I haven't got why you are using it here.

Jacob Dixon wrote:
You might be wondering why I call abort. This is because I really couldn't think of a better way to abort the current operation if the user clicks another computer. Having it wait until its done before letting the user choose another computer really isn't an option (because WMI can take a while sometimes).

Whole point of using threads is to allow users to do things in parallel. This means that, user should be able to browse multiple computer details and each should open in it's on windows. So user don't have to wait until an operation finishes and you don't have to abort threads forcefully. Also, I don't see any reason to create new threads each time. Queuing the tasks into ThreadPool should be good enough. ThreadPool threads are background threads.

Jacob Dixon wrote:
My problem is if you close the form while these threads are running. Right now I forgot to include anything for it and it causes teh app to crash.

A background thread should get aborted automatically when the main thread exits. Are you sure the main thread exits correctly? I guess the WaitOne call on Semaphore is blocking main thread and screwing up something.

Jacob Dixon wrote:
What is the "best practice" for handling something like this?

IMO, allow users to view details of multiple computers. Clicking each computer will queue a job to the worker thread and open a new window (or tab?) to show the details. So user can view computer details while other requests gets processed in the background. Avoid calling Abort(), avoid creating your own threads instead use a ThreadPool. Also make sure your main thread is not blocked.

Smile | :)

Best wishes,
Navaneeth

Jacob Dixon11-Feb-10 5:37

11-Feb-10 5:37

I created three threads and didn't want more than 3 running at one time. Thats why I used the semaphore. I haven't used a Threadpool before (new to threading as you might can tell lol). Let me read some on it and see what I can do with it.

Duh yeah opening in new windows would be more practical. Don't ask me why I didn't do that. I had a treeview on the left with the computers and on the right the listvies that displayed the info on the cmoputers. Im going to go with the new window suggestion lol.

Covean11-Feb-10 5:25

Covean

11-Feb-10 5:25

I would try to use async WMI calls.

ManagementObjectSearcher query = new ManagementObjectSearcher(managementScope, new ObjectQuery(szSelectStatement));
ManagementOperationObserver observer = new ManagementOperationObserver();
observer.CompletedEventHandler += /*someHandler...*/;
ManagementObjectCollection queryCollection = query.Get(observer);

Now you should wait for 2 events in your threads. The first event signals that your
query is completed. And the second event should signal that the thread should cancel
the query (observer.Cancel()).

Now you can sync your threads without having the need of abort them.

Greetings
Covean

Jacob Dixon11-Feb-10 5:40

11-Feb-10 5:40

I have never had any luck with ManagementOperationObserver. I have posted on multiple forums (incluiding Microsoft) of why it fails.

If I'm correct you can use that for installing applications. Using it allows you to view detailed information about the install running (like what it is doing). I've only been able to get it to work on local machine and not when doing remote instaleld with WMI.

Jacob Dixon11-Feb-10 5:42

11-Feb-10 5:42

Here is my post in the past about the Observer:

http://www.codeproject.com/Messages/3296363/WMI-Uninstall-application-on-remote-computer-The-R.aspx[^]