I have a GUI that is for all intents and purposes really basic. A listview, an html form, and that's really it.
I want the user to have the following behavioral ability:
1 - Click a checkbox that says "Real-time". When clicked, a background thread will run once every 10 seconds.
2 - If there is a new file created (this is easy, to observe a new file) I want an alert displayed in my main gui. Where it is displayed for now is arbitrary (in a label, for example).
The main issue is I cannot figure out how to do this in a multi-threaded example. My goal is exactly in line with multithreading: do tasks 1 and 2, without locking task 1. Meaning, while the update check is running, the user can interact with the GUI as if nothing was going on in the background.
If you need more details to better answer this please let me know.
Thanks!
Here are a couple sites I found useful for implementing a background worker when I needed to perform database operations while still allowing the GUI to be responsive:
http://msdn.microsoft.com/en-us/library/zw97wx20.aspx
http://www.codeproject.com/KB/cs/AsynchronousCodeBlocks.aspx
Use events from the thread to tell the UI that something's changed:
// Just detected that that a new file has been created
if (this.FileCreated_Event != null)
{
this.FileCreate_Event(this, new FileEventArgs(newFileName));
}
where FileCreated_Event and FileEventArgs are declared appropriately.
Then in the UI when you receive the event you have the following:
this.fileChecker.FileCreated_Event += this.FileCreated_Event;
and:
private void FileCreated_Event(object sender, TrackStatusEventArgs e)
{
if ((sender as Control).InvokeRequired)
{
(sender as Control).Invoke(action);
}
else
{
action();
}
}
where action is the thing you want to do.
Try this tutorial. At the end I'm sure you'll be able to use threads. You must be careful though, because you'll have to manage those threads which can be a daunting task. I've never met a programmer who liked to debug multiple threads...
Related
I am writing a Windows Forms app in C# with Visual Studio 2022 on a Windows 10 machine. The app connects to an Azure database, which works fine. My issue is that sometimes it takes several seconds to connect (maybe 10 or so), or if there is an error it goes all the way to the timeout limit (usually 20 to 30 seconds) before coming back with whatever error message there is.
I am trying to provide some visual feedback to the user during this time, but the application does not appear to be processing any events, so whatever type of feedback I'm trying to send does not get done until the operation completes (at which point it is moot).
Any ideas on how to deal with this? Do I need to open the database on a different thread, and if so, will that be an issue throughout the rest of the app whenever I use the database object opened on a different thread?
I'm trying something simple, like gradually adding a row of dots, like so:
private void InitCloudDatabase()
{
Boolean success = true;
WorkingTimer.Enabled = true;
WorkingTimer.Start();
try
{
AzureAgDatabase db = new AzureAgDatabase();
db.OpenConnection();
}
catch
{
success = false;
}
WorkingTimer.Stop();
pbCloudResult.Image = (success) ? Properties.Resources.icons8_done_96 :
Properties.Resources.Red_X___Fail;
}
private void WorkingTimer_Tick(object sender, EventArgs e)
{
lblCloud.Text += " .";
if (lblCloud.Text.Contains(" . . . . . . . . . . ."))
{
lblCloud.Text = "Database Connection (Cloud)";
}
}
I haven't really worked with Windows Forms before, but in most UI based applications, you should reserve the UI Thread for just UI operations and move all time consuming tasks (Compute or I/O) to a different thread to ensure that the UI is still responsive.
In the case of Windows Forms, looks like you have a BackgroundWorker class that you can use to offload the DB operations into. Here is a walkthrough in the official docs that you can refer to.
Another approach would be to use the Task class to run your database code asynchronously, with lesser code compared to the first approach. You would simply wrap statements that take time in a Task.Run call and have follow up statements in a continuation task.
I have spent the past few days working on bot for an MMO. It runs in one big loop, with 1-2 other smaller loops inside. So far its going great. When its running it is set to update a richtextbox with what it is currently doing, just so I can easily troubleshoot later.
My problem is while its active and looping it does not auto update the textbox until it has finished everything it is doing. Which is hard when its set in an infinite loop. I would like to be able to run the bot with the main program window on the other monitor giving me updates as it goes along.
The whole program seems to freeze up and I cant interact with it at all while running. This also causes problems when I want it to stop. The only way I have of stopping it at the minute is to click Stop in visual studio.
I have tried searching around, but I have no idea what to search for. I hope I explained it well enough.
Thanks in advance.
This would be a nice read :
http://www.beingdeveloper.com/use-dispatcher-in-wpf-to-build-responsive-applications/
To summaries
You can send in a delegate fx, which is responsible for a formatter or writter. In you implemetation it would be the one which does AppendText. and make sure the Richtextbox.AppendText is within Dispatcher.Invoke()
Code Sample
class BotRand
{
//Write Event is delegate
public execute(WriteEvent writeFx)
{
//Crawl
writeFx("message");
}
}
class MainWindow : Window
{
void WriteFunc(object message, EventArgs outline)
{
Dispatcher.Invoke(new Action(() => richText.AppendText(message));
}
}
This should help you start your search more effectively.
Thanks,
I have a c# form, and the initialization time takes a while (its getting information from a server, and populating a TreeView). Right now, the code looks similar to this:
public class myForm : Form
{
InitializeComponent();
List<Location> locations = getServerLocations(); // Server call
foreach( Location loc in locations )
{
List<POI> POIs = loc.getLocationPOIs(); // Server call
foreach( POI poi in POIs )
{
List<POIDetails> = poi.getPOIDetails(); // Server call
....
}
}
}
you get the point I think ... So there is a large tree, and I know I can not make the calls all the way down until the user expands the tree. But the intent is I just want the Form to display, with a 'loading...' or something on a tool strip while all the processing and server gets are happening.
Right now, it seems as if I haven't loaded the application yet because nothing will show to the user until all the calls are complete.
You shouldn't do any long running processing on the UI thread - instead move this to another thread i.e using a BackgroundWorker. You can initially show the "Loading" screen and, once the background worker completes, update your UI with your tree structure.
You should work with multi threading process, so that you can separate the process that takes time from the rest of the process. Here is a blog that may help you. .NET 4.0 and System.Threading.Tasks
Running your initialization on a separate thread is the preferred way. But if you're constrained to run it on the UI thread then try calling Application.DoEvents() right after your call to .Show() or .ShowDialog() of your form.
If the form shows up, it will still be unresponsive to user actions until the initialization is completed. So running the initialization on a separate thread is the better solution.
I built a little web application that displays charts. I was thinking that it might be useful for the superuser of the app to do a complete data refresh, however this process takes around 10 minutes to complete. I was thinking perhaps the user could click a button that would start off a new thread to do a data refresh and subsequent clicks would kill the thread and restart the data population process. The user would then be free to browse about the site and view the charts as their data is populated.
Is there a simple method of accomplishing something like this?
You can twist ASP.NET to do this sort of thing, but it violates a few good general rules for ASP.NET development -- and could really cause problems in a server farm.
So, the most obvious route is to do this work in a web service. You can have the method return a chunk of HTML if you want. You could also add status methods to see how the thread is progressing.
Other options include: Handing the intense processing off to a database server (sounds like this might be a good use of OLAP) or, another cheap trick might be to set up the click to fire off a scheduled task that runs on the server. Can you provide some additional detail about the environment? Single server? Data storage platform, version of .net?
Ok, I didn't use either answer so here is what I did. I decided that it would be better if subsequent clicks would terminate instead of the currently executing one. Thanks for your answers guys.
//code behind
protected void butRefreshData_Click(object sender, EventArgs e)
{
Thread t = new Thread(new ThreadStart(DataRepopulater.DataRepopulater.RepopulateDatabase));
t.Start();
}
//DataRepopulater.cs
namespace DataRepopulater
{
public static class DataRepopulater
{
private static string myLock = "My Lock";
public static void RepopulateDatabase()
{
if(Monitor.TryEnter(myLock))
{
DoWork();
Monitor.Exit(myLock);
}
}
}
Are there any build in UI capabilities when using Windows Workflow..
Lets say I have a workflow that takes an hour to run where different activities are happening all the time. While it's running I want to see what activity is currently active, what activities have already ran etc..
Do I have to code this UI myself or does WF have built in features that graphically show the status etc of the workflow?
To find out which state a workflow is in, I subscribe to the WorkflowIdled event and do something like this:
private delegate void UpdateDelegate();
void workflowRuntime_WorkflowIdled(object sender, WorkflowEventArgs e)
{
StateMachineWorkflowInstance stateMachineInstance = new StateMachineWorkflowInstance(MyManager.WorkflowRuntime, MyInstance.Id);
UpdateDelegate LclUpdateDelgate = delegate()
{
// Update the workflow state on the form thread
if (stateMachineInstance.CurrentState != null)
LabelWorkflowState.Text = stateMachineInstance.CurrentStateName;
else
LabelWorkflowState.Text = "";
};
this.Invoke(LclUpdateDelgate);
}
There is no built in UI.
But you can create one, either by subscribing to events on the WorflowInstance (see other answer), or by using the Tracking Service.
The former is simple to set up for a quick solution but the latter will work with multiple host processes and long running (unloaded) workflow instances.
Check out the this code sample over at MSDN:
http://msdn.microsoft.com/en-us/library/ms741706.aspx