I'm trying to use the BackgroundWorker class to start a new thread which loads a large number of objects into the cache when the website is started.
My code so far:
private void PreLoadCachedSearches()
{
var worker = new BackgroundWorker() { WorkerReportsProgress = false, WorkerSupportsCancellation = true };
worker.DoWork += new DoWorkEventHandler(DoWork);
worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(WorkerCompleted);
worker.RunWorkerAsync();
}
private static void DoWork(object sender, DoWorkEventArgs e)
{
// Do the cache loading...
var x = HttpContext.Current.Cache; // BUT the Cache is now null!!!!
}
private static void WorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// Logging?
}
I put the code in Global.asax.cs and call PreLoadCachedSearches during the Application_Start event: The new thread is started, but it fails whenever it tries to access the cache via HttpContext.Current.Cache which is null. I assume HttpContext doesn't exist/isn't available in the new thread I'm kicking off with the BackgroundWorker.
I've also tried moving the code to a separate page and start the thread manually rather than via the Application_Start event - same problem.
If I call my cache-loading code in the context of the web application (i.e. no threading) it works just fine.
How do I work around this? Pass in a reference to the cache of the main thread or access it somehow?
This question is a continuation of this previous question, Asynchronous task in ASP.NET.
You don't have an HttpContext because the thread isn't involved in servicing an Http Request.
Try HttpRuntime.Cache
You can do it by passing HttpContex.Current as parameter;
private void PreLoadCachedSearches()
{
var worker = new BackgroundWorker() { WorkerReportsProgress = false, WorkerSupportsCancellation = true };
worker.DoWork += new DoWorkEventHandler(DoWork);
worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(WorkerCompleted);
worker.RunWorkerAsync(HttpContext.Current);
}
private static void DoWork(object sender, DoWorkEventArgs e)
{
HttpContext.Current = (HttpContext)e.Argument;
var x = HttpContext.Current.Cache;
}
private static void WorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// Logging?
}
Related
What I'm trying to achieve is simple. I have a dynamic timer (one that can be changed by the user) which calls on background worker to go and fetch the user's external IP address. The combination of Timer and BackgroundWorker is causing some problems. Here's the code:
namespace IPdevices
{
/// <summary>
/// Interaction logic for Main.xaml
/// </summary>
public partial class Main : Window
{
private readonly BackgroundWorker worker;
private IPret iprep;
private Timer timer;
public Main(Client client)
{
InitializeComponent();
iprep = new IPret();
startClock();
worker = new BackgroundWorker();
worker.DoWork += worker_DoWork;
worker.RunWorkerCompleted += worker_RunWorkerCompleted;
worker.WorkerReportsProgress = true;
worker.ProgressChanged += worker_ProgressChanged;
}
private void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
ipAdd.Content = e.UserState;
}
private void startClock()
{
timer = new Timer();
timer.Interval = 2000;
timer.Elapsed += new ElapsedEventHandler(clockTimer_Tick);
timer.Start();
}
private void clockTimer_Tick(object sender, ElapsedEventArgs e)
{
timer.Stop();
worker.RunWorkerAsync();
}
private void worker_DoWork(object sender, DoWorkEventArgs e)
{
Console.WriteLine("Checking ip");
iprep.refresh();
worker.ReportProgress(0, iprep.getExternalIp());
Console.WriteLine("Found ip");
}
private void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
timer.Start();
}
}
}
Essentially, once the timer fires, I wish to fetch the ip address and output on a label in the application. However, I get an exception in the ProgressChanged method saying that it can't be changed because another thread owns it. Which thread is that? Is it the iprep that is owned by another thread? In fact, RunWorkerCompleted never gets fired. I'm having trouble understanding which threads own what and how objects are locked...Any insight would be appreciated.
This appears to fix it in my test of it
private void clockTimer_Tick(object sender, ElapsedEventArgs e)
{
timer.Stop();
Action a = () =>
{
worker.RunWorkerAsync();
};
Application.Current.Dispatcher.BeginInvoke(a);
}
Also, I'll note this is consistent behavior for Timer in WPF (I hadn't used it in WPF before); trying ipAdd.Content = "Tick"; in the clockTimer_Tick causes the same error. System.Timers.Timer's tick event does not happen on the UI thread.
Replace all your code by the few lines shown below. The Tick handler is executed in the UI thread. Still it asynchronously runs a background operation and does not block the UI thread.
private void StartClock()
{
var timer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(2) };
timer.Tick += async (o, e) => await GetIP();
timer.Start();
}
private async Task GetIP()
{
Debug.WriteLine("Checking ip");
await Task.Run(() =>
{
// Get the IP asynchronously here
});
Debug.WriteLine("Found ip");
// Update the UI here
}
ipAdd is an UI element if I am not mistaken. If it is then the problem lies on cross threading.
What happened is that Background worker is going to be running on a different thread than the UI thread. If you want to modify UI element's property you need to do it on the UI thread. One option is to use Dispatcher.Invoke but since you are using WPF, there is a better way to do it.
Do a search about MVVM design patter and move the background code into View Model. Then you could do something like
string _XXContent
public string XXContent
{
get
{
return _XXContent;
}
set
{
_XXContent = value;
OnPropertyChanged("XXContent");
}
}
private void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
XXContent = e.UserState;
}
xaml :
<TextBox Content={Binding XXContent}/>
Edit:
If you are on c# 5 then you should look into async/IProgress as well an get rid of Background worker.
I have a Windows Forms application which makes calls to web services via proxies generated with SvcUtil from WSDL descriptors. These calls can last for minutes, and during this time I don't want the client app to 'freeze out'. What do I have to do to achieve this? I guess something Threading related, but I'm not sure how to manage return values and parameters in that case.
You could use a BackgroundWorker.
private void wrk_DoWork(object sender, DoWorkEventArgs e)
{
// Do your work here
}
private void wrk_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// Executed when worker completed its execution
}
private void StartIt()
{
BackgroundWorker wrk1 = new BackgroundWorker();
wrk1.DoWork += wrk_DoWork;
wrk1.RunWorkerCompleted += wrk_RunWorkerCompleted;
wrk1.RunWorkerAsync();
}
I'd go for a background worker.
Set the RunWorkerCompleted event and DoWork, run it and when you get your result in DoWork, set the event argument to your result (e.Result).
BackgroundWorker bw = new BackgroundWorker();
bw.DoWork += new DoWorkEventHandler(bw_DoWork);
bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
bw.RunWorkerAsync();
private void bw_DoWork(object sender, DoWorkEventArgs e)
{
// Do your processing
e.Result = result;
}
private void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
ResultLabel.Text = (string)e.Result;
}
The examples aren't tested, but your IDE should help you out. Also you will have to resolve the BackgroundWorker, or just add
using System.ComponentModel;
More information here: http://msdn.microsoft.com/en-us/library/cc221403(v=vs.95).aspx
Hope it helps!
You can use methods that start with Begin......
e.g, use BeginAbc() instead of Abc()
I would recommend looking into BackgroundWorkers..
BackgroundWorker proxyWorker = new BackgroundWorker();
proxyWorker.DoWork +=
(sender, args) =>
{
//make proxy call here
};
proxyWorker.RunWorkerAsync();
I have a WPF application that executes external programs to process media files, and so that the GUI doesn't freeze when the media files are being processed, I execute the process on a separate thread through backgroundworker.
private void BackgroundWorkerExecProcess(Process process)
{
BackgroundWorker worker = new BackgroundWorker();
worker.WorkerReportsProgress = false;
worker.DoWork += DoWork;
worker.RunWorkerCompleted += WorkerCompleted;
worker.RunWorkerAsync(process);
}
void DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
Process process = e.Argument as Process;
process.Start();
string stderr = process.StandardError.ReadToEnd();
//I want to display stderr on main thread
process.WaitForExit();
}
void WorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
//some code to update gui telling user that process has finished
}
so, if there is something printed to stderr, I can see it in the debugger, but if I try to do anything with the string stderr, such as if I have a textbox called "_tbLog" and did
_tbLog.Text+=stderr;
I get an error from the compiler about them being on separate threads. is there a way to pass the object from the worker thread to the main thread?
In DoWork, set e.Result to your object. In the WorkerCompleted you can get that object back out... it will once again be e.Result of type object. Just cast it to the object it was. The WorkerCompleted should be on the correct thread.
Here is one of mine:
private void workerUpdateBuildHistory_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
{
UpdateStatusModel model = (UpdateStatusModel)e.Argument;
BuildService buildService = new BuildService(model.TFSUrl);
e.Result = buildService.UpdateBuildHistoryList(model);
}
private void workerUpdateBuildHistory_RunWorkerCompleted(object sender, System.ComponentModel.RunWorkerCompletedEventArgs e)
{
BuildHistoryListModel model = (BuildHistoryListModel)e.Result;
if (model != null)
{
listViewPastBuilds.Items.Clear();
foreach (var item in model.Builds)
{
listViewPastBuilds.Items.Add(item);
}
}
}
Use your WorkerCompleted event handler to make changes the UI, it runs on the right thread. All you have to do is pass the string to the event handler. Which is what DoWorkEventArgs.Result was designed to do. You'll retrieve it in the event handler from e.Result. Thus:
void DoWork(object sender, DoWorkEventArgs e)
{
//...
e.Result = stderr;
}
void WorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (e.Error != null) DisplayError(e.Error);
else _tbLog.Text += (string)e.Result;
}
First you need to place whatever result object (in this example, a list of strings) in the DoWorkEventArgs.Result property, then retrieve this object via the RunWorkerCompletedArgs.Result property
Then, hook up an event handler RunWorkedCompleted event of the Background worker and have it pass back whatever object you want in the RunWorkerCompletedEventArgs.Result property.
Example:
void DoWork(object sender, DoWorkEventArgs arg)
{
List<string> results = new List<string>();
results.Add("one");
results.Add("two");
results.Add("three");
arg.Results = results;
}
void WorkComplete(object sender, runWorkerCompelteEventArgs arg)
{
//Get our result back as a list of strings
List<string> results = (List<string>)arg.Result;
PrintResults(results);
}
Note: I have not tested this code, but I believe it should compile.
http://msdn.microsoft.com/en-us/library/system.componentmodel.runworkercompletedeventargs.result.aspx
http://msdn.microsoft.com/en-us/library/system.componentmodel.doworkeventargs.aspx
you can also use the dispatcher as #Zembi mentiones:
this.Dispatcher.Invoke( new Action( () => {
_tbLog.Text+=stderr;
} ) );
you can also use TPL to make sure things get run on the right thread
-edit-
Here is a good article on diffrent ways to do ui updates, including using TPL
In C# 4.0 and IronPython 2.6, is it possible to execute a python script in it's own thread?
I would like to spawn off the script after passing in some event handler objects so that it can update the GUI as it runs.
I would use a Task:
ScriptEngine engine = ...;
// initialize your script and events
Task.Factory.StartNew(() => engine.Execute(...));
The IronPython script will then run on a separate thread. Make sure your event handlers use the appropriate synchronization mechanism when updating the GUI.
You could use a background worker to run the script on a separate thread. Then use the ProgressChanged and RunWorkerCompleted event handlers to update the ui.
BackgroundWorker worker;
private void RunScriptBackground()
{
string path = "c:\\myscript.py";
if (File.Exists(path))
{
worker = new BackgroundWorker();
worker.DoWork += new DoWorkEventHandler(bw_DoWork);
worker.ProgressChanged += new ProgressChangedEventHandler(bw_ProgressChanged);
worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
worker.RunWorkerAsync();
}
}
private void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// handle completion here
}
private void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
// handle progress updates here
}
private void bw_DoWork(object sender, DoWorkEventArgs e)
{
// following assumes you have setup IPy engine and scope already
ScriptSource source = engine.CreateScriptSourceFromFile(path);
var result = source.Execute(scope);
}
I have spent the whole day trying to make my application use threads but with no luck. I have read much documentation about it and I still get lots of errors, so I hope you can help me.
I have one big time consuming method which calls the database and updates the GUI. This has to happen all the time(or about every 30 seconds).
public class UpdateController
{
private UserController _userController;
public UpdateController(LoginController loginController, UserController userController)
{
_userController = userController;
loginController.LoginEvent += Update;
}
public void Update()
{
BackgroundWorker backgroundWorker = new BackgroundWorker();
while(true)
{
backgroundWorker.DoWork += new DoWorkEventHandler(backgroundWorker_DoWork);
backgroundWorker.RunWorkerAsync();
}
}
public void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
_userController.UpdateUsersOnMap();
}
}
With this approach I get an exception because the backgroundworker is not and STA thread(but from what I can understand this is what I should use). I have tried with a STA thread and that gave other errors.
I think the problem is because I try to update the GUI while doing the database call(in the background thread). I should only be doing the database call and then somehow it should switch back to the main thread. After the main thread has executed it should go back to the background thread and so on. But I can't see how to do that.
The application should update the GUI right after the database call. Firering events don't seem to work. The backgroundthread just enters them.
EDIT:
Some really great answers :) This is the new code:
public class UpdateController{
private UserController _userController;
private BackgroundWorker _backgroundWorker;
public UpdateController(LoginController loginController, UserController userController)
{
_userController = userController;
loginController.LoginEvent += Update;
_backgroundWorker = new BackgroundWorker();
_backgroundWorker.DoWork += backgroundWorker_DoWork;
_backgroundWorker.RunWorkerCompleted += backgroundWorker_RunWorkerCompleted;
}
public void _backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
_userController.UpdateUsersOnMap();
}
public void Update()
{
_backgroundWorker.RunWorkerAsync();
}
void backgroundWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
//UI update
System.Threading.Thread.Sleep(10000);
Update();
}
public void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
// Big database task
}
}
But how can I make this run every 10 second? System.Threading.Thread.Sleep(10000) will just make my GUI freeze and while(true) loop in Update() as suggested gives an exception(Thread too busy).
You need to declare and configure the BackgroundWorker once - then Invoke the RunWorkerAsync method within your loop...
public class UpdateController
{
private UserController _userController;
private BackgroundWorker _backgroundWorker;
public UpdateController(LoginController loginController, UserController userController)
{
_userController = userController;
loginController.LoginEvent += Update;
_backgroundWorker = new BackgroundWorker();
_backgroundWorker.DoWork += new DoWorkEventHandler(backgroundWorker_DoWork);
_backgroundWorker.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker_ProgressChanged);
_backgroundWorker.WorkerReportsProgress= true;
}
public void Update()
{
_backgroundWorker.RunWorkerAsync();
}
public void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
while (true)
{
// Do the long-duration work here, and optionally
// send the update back to the UI thread...
int p = 0;// set your progress if appropriate
object param = "something"; // use this to pass any additional parameter back to the UI
_backgroundWorker.ReportProgress(p, param);
}
}
// This event handler updates the UI
private void backgroundWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
// Update the UI here
// _userController.UpdateUsersOnMap();
}
}
You have to use the Control.InvokeRequired property to determine if you are on a background thread. Then you need to invoke your logic that modified your UI via the Control.Invoke method to force your UI operations to occur on the main thread. You do this by creating a delegate and passing it to the Control.Invoke method. The catch here is you need some object derived from Control to call these methods.
Edit: As another user posted, if yo you can wait to the BackgroundWorker.Completed event to update your UI then you can subscribe to that event and call your UI code directly. BackgroundWorker_Completed is called on the main app thread. my code assumes you want to do updates during the operation. One alternative to my method is to subscribe to the BwackgroundWorker.ProgressChanged event, but I believe you'll need to still call Invoke to update your UI in that case.
for example
public class UpdateController
{
private UserController _userController;
BackgroundWorker backgroundWorker = new BackgroundWorker();
public UpdateController(LoginController loginController, UserController userController)
{
_userController = userController;
loginController.LoginEvent += Update;
}
public void Update()
{
// The while loop was unecessary here
backgroundWorker.DoWork += new DoWorkEventHandler(backgroundWorker_DoWork);
backgroundWorker.RunWorkerAsync();
}
public delegate void DoUIWorkHandler();
public void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
// You must check here if your are executing on a background thread.
// UI operations are only allowed on the main application thread
if (someControlOnMyForm.InvokeRequired)
{
// This is how you force your logic to be called on the main
// application thread
someControlOnMyForm.Invoke(new
DoUIWorkHandler(_userController.UpdateUsersOnMap);
}
else
{
_userController.UpdateUsersOnMap()
}
}
}
You should remove the while(true), you are adding infinite event handlers and invoking them infinite times.
You can use the RunWorkerCompleted event on the backgroundWorker class to define what should be done when the background task has completed. So you should do the database call in the DoWork handler, and then update the interface in the RunWorkerCompleted handler, something like this:
BackgroundWorker bgw = new BackgroundWorker();
bgw.DoWork += (o, e) => { longRunningTask(); }
bgw.RunWorkerCompleted += (o, e) => {
if(e.Error == null && !e.Cancelled)
{
_userController.UpdateUsersOnMap();
}
}
bgw.RunWorkerAsync();
In addition to previous comments, take a look at www.albahari.com/threading - best doc on threading you will ever find. It will teach you how to use the BackgroundWorker properly.
You should update the GUI when the BackgroundWorker fires Completed event (which is invoked on UI thread to make it easy for you, so that you don't have to do Control.Invoke yourself).
Here's a source code pattern you can use based on some WinForms example code, but you can apply it for WPF as well very easily. In this example, I am redirecting output to a Console which I then use to let the background worker write some messages to a textbox while it is processing.
It consists of:
A helper class TextBoxStreamWriter used to redirect console output to a textbox
A background worker writing to the redirected console
A progress bar which needs to be reset after completion of background worker
Some text boxes (txtPath and txtResult), and a "Start" button
In other words, there is some background task which needs to interact with the UI. Now I am going to show how that is done.
From the context of the background task, you need to use Invoke to access any UI element. I believe the simplest way to do that is to use lambda expression syntax, like
progressBar1.Invoke((Action) (() =>
{ // inside this context, you can safely access the control
progressBar1.Style = ProgressBarStyle.Continuous;
}));
To update the ProgressBar, a local method like
private void UpdateProgress(int value)
{
progressBar1.Invoke((Action)(() => { progressBar1.Value = value; }));
}
helps. It is passing the value parameter to the progress bar as a closure.
This is the helper class TextBoxStreamWriter, which is used to redirect console output:
public class TextBoxStreamWriter : TextWriter
{
TextBox _output = null;
public TextBoxStreamWriter(TextBox output)
{
_output = output;
}
public override void WriteLine(string value)
{
// When character data is written, append it to the text box.
// using Invoke so it works in a different thread as well
_output.Invoke((Action)(() => _output.AppendText(value+"\r\n")));
}
}
You need to use it in the form load event as follows (where txtResult is a textbox, to which the output will be redirected):
private void Form1_Load(object sender, EventArgs e)
{
// Instantiate the writer and redirect the console out
var _writer = new TextBoxStreamWriter(txtResult);
Console.SetOut(_writer);
}
There is also a button on the form which starts the background worker, it passes a path to it:
private void btnStart_Click(object sender, EventArgs e)
{
backgroundWorker1.RunWorkerAsync(txtPath.Text);
}
This is the workload of the background worker, note how it uses the console to output messages to the textbox (because of the redirection that was set up earlier):
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
var selectedPath = e.Argument as string;
Console.Out.WriteLine("Processing Path:"+selectedPath);
// ...
}
The variable selectedPath consists of the path that was passed to the backgroundWorker1 earlier via the parameter txtPath.Text, it is being accessed via e.Argument.
If you need to reset some controls afterwards, do it in the following way (as already mentioned above):
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
progressBar1.Invoke((Action) (() =>
{
progressBar1.MarqueeAnimationSpeed = 0;
progressBar1.Style = ProgressBarStyle.Continuous;
}));
}
In this example, after completion, a progress bar is being reset.
Important: Whenever you access a GUI control, use Invoke as I did in the examples above.
Using Lambda's makes it easy, as you could see in the code.
And here's the complete example, which runs in LinqPad 6 (just copy and paste it into an empty C# Program query) - I decided to use LinqPad this time so you can learn something new, because you all know how to create a new Windows Forms project in Visual Studio (and if you still want to do so, just copy the events below and drag and drop the controls to the form):
// see: https://stackoverflow.com/a/27566468/1016343
using System.ComponentModel;
using System.Windows.Forms;
BackgroundWorker backgroundWorker1 = new System.ComponentModel.BackgroundWorker();
ProgressBar progressBar1 = new ProgressBar() { Text = "Progress", Width = 250, Height=20, Top=10, Left=0 };
TextBox txtPath = new TextBox() { Text =#"C:\temp\", Width = 100, Height=20, Top=30, Left=0 };
TextBox txtResult = new TextBox() { Text = "", Width = 200, Height=250, Top=70, Left=0, Multiline=true, Enabled=false };
Button btnStart = new Button() { Text = "Start", Width = 100, Height=30, Top=320, Left=0 };
void Main()
{
// see: https://www.linqpad.net/CustomVisualizers.aspx
// Instantiate the writer and redirect the console out
var _writer = new TextBoxStreamWriter(txtResult);
Console.SetOut(_writer);
// wire up events
btnStart.Click += (object sender, EventArgs e) => btnStart_Click(sender, e);
backgroundWorker1.DoWork += (object sender, DoWorkEventArgs e) => backgroundWorker1_DoWork(sender, e);
backgroundWorker1.RunWorkerCompleted += (object sender, RunWorkerCompletedEventArgs e)
=> backgroundWorker1_RunWorkerCompleted(sender, e);
using var frm = new Form() {Text="Form", Width = 300, Height=400, Top=0, Left=0};
frm.Controls.Add(progressBar1);
frm.Controls.Add(txtPath);
frm.Controls.Add(txtResult);
frm.Controls.Add(btnStart);
// display controls
frm.ShowDialog();
}
private void btnStart_Click(object sender, EventArgs e)
{
backgroundWorker1.RunWorkerAsync(txtPath.Text);
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
InitProgress();
var selectedPath = e.Argument as string;
Console.Out.WriteLine("Processing Path: " + selectedPath);
UpdateProgress(0); Thread.Sleep(300); UpdateProgress(30); Thread.Sleep(300);
UpdateProgress(50); Thread.Sleep(300);
Console.Out.WriteLine("Done.");
// ...
}
private void UpdateProgress(int value)
{
progressBar1.Invoke((Action)(() =>
{
progressBar1.Value = value;
}));
}
private void InitProgress()
{
progressBar1.Invoke((Action)(() =>
{
progressBar1.MarqueeAnimationSpeed = 0;
progressBar1.Style = ProgressBarStyle.Continuous;
}));
}
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
UpdateProgress(100); // always show 100% when done
}
// You can define other methods, fields, classes and namespaces here
public class TextBoxStreamWriter : TextWriter
{
TextBox _output = null;
public TextBoxStreamWriter(TextBox output)
{
_output = output;
}
public override Encoding Encoding => throw new NotImplementedException();
public override void WriteLine(string value)
{
// When character data is written, append it to the text box.
// using Invoke so it works in a different thread as well
_output.Invoke((Action)(() => _output.AppendText(value + "\r\n")));
}
}
The if-statement in #Lee's answer should look like:
bgw.RunWorkerCompleted += (o, e) => {
if(e.Error == null && !e.Cancelled)
{
_userController.UpdateUsersOnMap();
}
}
...if you want to invoke UpdateUsersOnMap(); when there are no errors and BgWorker hasn't been cancelled.