Progress of a Task in C#

By default Task doesn’t report it’s progress as a BackgroundWorker does. But that doesn’t mean we can’t get a progress of a Task. There is a new interface which was introduced with .NET framework 4.5 which is IProgress<T>. This interface exposes a Report(T) method, which the async task calls to report progress.

Let’s go by an example. I have the following async method.

async Task MyMethodAsync(int sleepTime, IProgress<MyTaskProgressReport> progress)

{

    int totalAmount = 10000; 

    for (int i = 0; i <= totalAmount;)

    {

        await Task.Delay(sleepTime);

        progress.Report(new MyTaskProgressReport { CurrentProgressAmount = i, TotalProgressAmount = totalAmount, CurrentProgressMessage = string.Format("On {0} Message", i) });

        i = i + sleepTime;

    }

}

It takes a progress parameter which is a IProgress of type “MyTaskProgressReport” and here is my “MyTaskProgressReport” class.

public class MyTaskProgressReport

{

   //current progress

   public int CurrentProgressAmount { get; set; }

   //total progress

   public int TotalProgressAmount { get; set; }

   //some message to pass to the UI of current progress

   public string CurrentProgressMessage { get; set; }

}

To simulate a time taking task, inside my async method, I have a For loop and inside it I have a Task Delay. In every iteration, progress is reported to the caller. Now let’ see how UI captures this.

On the UI thread, we have to define an event handler Action<T>, which will be called when IProgress<T>.Report is invoked.

private void ReportProgress(MyTaskProgressReport progress)

{

    label1.Text = progress.CurrentProgressMessage;

    textBox1.Text = string.Format("{0} out of {1}", progress.CurrentProgressAmount, progress.TotalProgressAmount);

}

Now I am going to call my async method. I have created a Progress<T> instance and invoked the async method, which is triggered by a button click.

private async void button1_Click(object sender, EventArgs e)

{

    var progressIndicator = new Progress<MyTaskProgressReport>(ReportProgress);

    await MyMethodAsync(1000, progressIndicator);

}

Here is the output,

Result

I have uploaded a full sample to my SkyDrive. Do check it out.


Happy Coding.

Regards
Jaliya