IAsyncProgress Interface

Represents a progress updates provider for asynchronous operations. It provides methods for updating the progress from concurrent threads.


Namespace: KGySoft.Threading
Assembly: KGySoft.CoreLibraries (in KGySoft.CoreLibraries.dll) Version: 8.0.0
public interface IAsyncProgress


The following example demonstrates how to implement this interface allowing concurrent updates.
#nullable enable

using System;
using System.Threading;
using System.Timers;

using KGySoft.Threading;

using Timer = System.Timers.Timer;

class Example
    public static void Main()
        var progressTracker = new ProgressTracker();
        using var progressReporter = new ConsoleProgressReporter(progressTracker);
        var config = new ParallelConfig { Progress = progressTracker };

        // imitating some long concurrent task
        progressReporter.Enabled = true; // starts updating the progress periodically
        ParallelHelper.For("Some parallel operation", 0, 1000, config,
            body: i => Thread.Sleep(1));
        progressReporter.UpdateProgress(); // to show the completed progress.
        progressReporter.Enabled = false; // stopping the timer

    // This IAsyncProgress implementation just provides an always up-to-date Current property.
    // You can add an event if you don't want to miss any tiny progress change.
    private class ProgressTracker : IAsyncProgress
        private readonly object syncRoot = new object();
        private string? currentOperation;
        private int maximumValue;
        private int currentValue;

        public AsyncProgress<string?> Current
                lock (syncRoot)
                    return new AsyncProgress<string?>(currentOperation, maximumValue, currentValue);

        public void Report<T>(AsyncProgress<T> progress)
            lock (syncRoot)
                // Converting any T to string (assuming it can be displayed as a text)
                currentOperation = progress.OperationType?.ToString();
                maximumValue = progress.MaximumValue;
                currentValue = progress.CurrentValue;

        public void New<T>(T operationType, int maximumValue = 0, int currentValue = 0)
            => Report(new AsyncProgress<T>(operationType, maximumValue, currentValue));

        public void Increment()
            lock (syncRoot)

        public void SetProgressValue(int value)
            lock (syncRoot)
                currentValue = value;

        public void Complete()
            lock (syncRoot)
                currentValue = maximumValue;

    // This class is the one that displays the actual progress. It can be easily adapted to any UI.
    private class ConsoleProgressReporter : IDisposable
        private readonly Timer timer; // using System.Timers.Timer here but you can use UI-specific versions
        private readonly ProgressTracker progressTracker;

        // To turn progress reporting on and off. In a UI you can set also some progress bar visibility here.
        public bool Enabled
            get => timer.Enabled;
            set => timer.Enabled = value;

        public ConsoleProgressReporter(ProgressTracker progress)
            progressTracker = progress;
            timer = new Timer { Interval = 100 }; // Displayed progress is updated only in every 100ms.
            timer.Elapsed += Timer_Elapsed;

        // Please note that progress is updated only when the timer ticks so can skip some rapid changes.
        private void Timer_Elapsed(object? sender, ElapsedEventArgs e) => UpdateProgress();

        public void UpdateProgress()
            // In a UI you can set progress bar value, maximum value and some text here.
            var current = progressTracker.Current; // a local copy to prevent an inconsistent report.
            Console.WriteLine($"{current.OperationType}: {current.CurrentValue}/{current.MaximumValue}");

        public void Dispose()
            timer.Elapsed -= Timer_Elapsed;

// The example above prints a similar output to this one:
// Some parallel operation: 56/1000
// Some parallel operation: 152/1000
// Some parallel operation: 200/1000
// Some parallel operation: 248/1000
// Some parallel operation: 304/1000
// Some parallel operation: 352/1000
// Some parallel operation: 408/1000
// Some parallel operation: 456/1000
// Some parallel operation: 504/1000
// Some parallel operation: 560/1000
// Some parallel operation: 608/1000
// Some parallel operation: 664/1000
// Some parallel operation: 712/1000
// Some parallel operation: 768/1000
// Some parallel operation: 816/1000
// Some parallel operation: 864/1000
// Some parallel operation: 920/1000
// Some parallel operation: 968/1000
// Some parallel operation: 1000/1000


Complete Indicates that a progress value of the last New or Report method should be set to the maximum value. It is not required to be called at the end of each sessions so it just indicates that whatever progress has reached the last step.
Increment Indicates a progress update of a single step. Expected to be called after the New or Report methods if they were called with nonzero maximum steps. The implementation should not be sensitive for concurrency racing conditions.
NewT Indicates that a new progress session is started that consists of maximumValue steps.
ReportT Reports a progress update to any arbitrary state. For parallel operations it is recommended to use the Increment method after starting a new progress because this method cannot guarantee that CurrentValue will be a strictly increasing value when called from Parallel members, for example.
SetProgressValue Indicates that the current progress is at a specific position.

See Also