c# - Using a Background Worker - Update a ProgressBar on the progress of a Recursive Method

Question

Below is a method that I want to ship off into a background worker but I am struggling how to do it based on how created my method. As you can it doesn't return anything which is ok but it expects a directoryInfo object everytime it is recalled.

    private void getSizeForTargetDirectory(DirectoryInfo dtar)
    { 
        // generate a collection of objects. files comes first and then directories.

        foreach (Object item in collection )
        {
            if (item == file)
            {
               track the size of the files as you encounter.
            }
            else if (item == directory)
            {
                // found a new directory, recall the method. !!!
            }
        }
    }

This is my first time using a background worker so I'm a little stuck, I tried implementing something thanks to the help found here but got stuck when I realised my method was recursive.

How do I display progress during a busy loop?

I implemented a doWork event handler method but noticed that i needed to somehow recall the method if I had more files and folders to process on lower sub levels.

I have a simple button click event handler that calls my 'getSizeForTargetDirectory()' method when the current selected node is a directory.

 private void retrieveInfoButton_Click(object sender, EventArgs e)
    {
        // check to see if the path is valid
        // reset the labels and textfields.
        string fullPath = treeDrives.SelectedNode.FullPath;
        string sNodesName = treeDrives.SelectedNode.Text;

        if (directory) // Enter here if its a directory.
        {
            string parentPath = treeDrives.SelectedNode.Parent.FullPath;
            DirectoryInfo[] dirArray = populateFoldersArray(parentPath);

            for (int i = 0; i < dirArray.Length; i++)
            {
                if (dirArray[i].Name == sNodesName)
                {
                    getSizeForTargetDirectory(dirArray[i]);

                    // do work !

Hopefully that explains what I am trying to do and how I am doing it. Question is how can i use the report progress feature of the background worker class when the bulk of the work I am trying to ship is coming from a recursive method.

Through early testing I noticed that my getSize method was incredibly efficient after a few tweaks and reported size information for the current supplied folder very quickley but then again I use quite a powerful dev machine so this may not be true for all users.

Thanks For Reading, Hope someone can help !!!

Answer 1

I think it is much simpler to use the built-in methods on either Directory or DirectoryInfo to obtain all directories, or files, using the recursive search option:

public partial class Form1 : Form
{
    private Action<float> updateProgMethod;

    public Form1()
    {
        InitializeComponent();
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        updateProgMethod = UpdateProgress;
    }

    private void GetDirectorySizeAsync(string path)
    {
        backgroundWorker.RunWorkerAsync(path);
    }

    private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
    {
        DirectoryInfo di = new DirectoryInfo((string)e.Argument);
        di.GetTotalSize(ProgressCallback);
    }

    // Takes callbacks from the GetTotalSize() method
    private void ProgressCallback(float p)
    {
        // Invokes update progress bar on GUI thread:
        this.BeginInvoke(updateProgMethod, new object[] { p });
    }

    // Actually updates the progress bar:
    private void UpdateProgress(float p)
    {
        progressBar.Value = (int)(p * (progressBar.Maximum - progressBar.Minimum)) + progressBar.Minimum;
    }
}

public static class IOExtensions
{
    public static long GetTotalSize(this DirectoryInfo directory, Action<float> progressCallback)
    {
        FileInfo[] files = directory.GetFiles("*.*", SearchOption.AllDirectories);
        long sum = 0;
        int countDown = 0;
        for (int i = 0; i < files.Length; i++)
        {
            sum += files[i].Length;
            countDown--;
            if (progressCallback != null && countDown <= 0)
            {
                countDown = 100;
                progressCallback((float)i / files.Length);
            }
        }
        return sum;
    }
}

It's hard to guess progress without knowing the number of files or folders first!

EDIT: I've improved the code a little.