CODEWITHSUNDEEP
c#multithreadingbackgroundworkerfilesystemwatcher
Pablo Costa
Pablo Costa

Reputation: 125

Backgroundworker with FileSystemWatcher

I'm trying to implement a BackgroundWorker for monitoring a FileSystemWatcher service.

My code is divided as: A Classes.cs wich contains all methods , variables and FileSystemWatcher implementation. And the main Form1 , wich contains form data and calls for the buttons\etc. When i run my program all that happens is the cursor to change (this was already expected) - the action happens in the background (things get done) but no report is shown on my progress bar. I got the example from a website and adapted it to my code - is there anything wrong i'm doing ? I believe there's something involved with the fact the only thing i call is the filesystemwatcher - but i expected that it would report the progress based on the action running "on background".

Any help is appreciated. Thanks

My form1 code (the BackgroundWorker part) and the FileSystemWatcher follows:

namespace PPF_Converter_v10
{
    public partial class Form1 : Form
    {
        private FileManipulation prg;
        //private FileManipulation FileOp;

        public Form1()
        {
            InitializeComponent();
            //FileOp = new FileManipulation();
            prg = new FileManipulation();
            //Load config before the program begins - loading sample config or newly generated config
            prg.LoadConfig();
            FillTextBox();
            bgWorker.DoWork += new DoWorkEventHandler(bgWorker_DoWork);
        }

BackgroundWorker CODE:

private void bgWorker_DoWork(object sender, DoWorkEventArgs e)
{                
        if (!textBox1.Text.Contains("\\"))
        {
            MessageBox.Show("Please define the input folder before starting");

        }
        else if (!textBox2.Text.Contains("\\"))
        {
            MessageBox.Show("Please define the XML Output folder before starting");

        }
        else if (!textBox3.Text.Contains("\\"))
        {
            MessageBox.Show("Please define the Converted PPF Output Folder before starting");

        }
        else if (!textBox4.Text.Contains("\\"))
        {
            MessageBox.Show("Please define the Invalid PPF Output Folder before starting");

        }
        else
        {
            // calls the watcher
            // prg.FileWatcher.SynchronizingObject = progressBar1.
            prg.ProgramProcessing(textBox1.Text);
        }            
    // do some long-winded process here
    // this is executed in a separate thread
    int maxOps = 1000000;
    for (int i = 0; i < maxOps; i++)
    {
        //rtbText.AppendText(i.ToString() + "\r\n");
        // report progress as a percentage complete
        bgWorker.WorkerReportsProgress = true;

        bgWorker.ReportProgress(100 * i / maxOps);
    }
}
private void bgWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    // update the progress bar
    pbProgress.Value = e.ProgressPercentage;
}
private void bgWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    // return to "normal" mode of operation
    this.Cursor = Cursors.Default;
    btnGo.Enabled = true;
}

private void btnGo_Click_1(object sender, EventArgs e)
{
    // give the appearance of something happening
    this.Cursor = Cursors.WaitCursor;
    btnGo.Enabled = false;
    // call RunWorkerAsync to start the background thread
    bgWorker.RunWorkerAsync();
}

Exception thrown when the RichtextBox is enabled: Additional information: Cross-thread operation not valid: Control 'rtbText' accessed from a thread other than the thread it was created on.

Upvotes: 0

Views: 958

Answers (1)

Pedro G. Dias
Pedro G. Dias

Reputation: 3222

You're invoking a MessageBox from the background thread on the foreground thread. That is like doing UI in two separate threads which is a no-no.

What you can do is either use events or an event aggregator from your background thread. I would probably go for the latter. This way, your background thread, when something is wrong, can (and should) abort immediately and notify through a message that it was unable to process the file.

Think of a background task as something that has no UI whatsoever. It is there in the background and can only communicate to the UI thread using events or messages.

Upvotes: 0

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