IVSoftware.Portable.WatchdogTimer 1.1.0

Watchdog timer

A timer designed to complete after the time span set by the Interval property has elapsed since the most recent call to the StartOrRestart method. This results in a single completion regardless of the number of restarts. Invoking the Cancel method negates any enqueued action or event in the queue.

Methods

/// <summary>
/// Restart the watchdog timer.
/// </summary>
/// <remarks>
/// Core method that can take a parameterized action as well as a custom EventArgs object.
/// </remarks>
public void StartOrRestart(Action action, EventArgs e)
{
    Running = true;
    _wdtCount++;
    var capturedCount = _wdtCount;
    _isCancelled= false;
    Task
        .Delay(Interval)
        .GetAwaiter()
        .OnCompleted(() =>
        {
            // If the 'captured' localCount has not changed after awaiting the Interval, 
            // it indicates that no new 'bones' have been thrown during that interval.        
            if (capturedCount.Equals(_wdtCount) && !_isCancelled)
            {
                action?.Invoke();
                Running = false;
                RanToCompletion?.Invoke(this, e ?? EventArgs.Empty);
            }
        });
}

/// <summary>
/// Restart the watchdog timer.
/// </summary>
/// <remarks>
/// Subscribe to the RanToCompletion event to receive notification of completion.  
/// On completion, fire an event with an empty EventArgs object.
/// </remarks>
public void StartOrRestart() => StartOrRestart(null, EventArgs.Empty);

/// <summary>
/// Restart the watchdog timer.
/// </summary>
/// <remarks>
/// Subscribe to the RanToCompletion event to receive notification of completion.  
/// On completion, fire an event using a custom parameterized EventArgs object.
/// </remarks>
public void StartOrRestart(EventArgs e) => StartOrRestart(null, e);

/// <summary>
/// Restart the watchdog timer.
/// </summary>
/// <remarks>
/// Subscribe to the RanToCompletion event to receive notification of completion.  
/// On completion, invoke a parameterized action.
/// </remarks>
public void StartOrRestart(Action action) => StartOrRestart(action, EventArgs.Empty);
    

public void Cancel() => _isCancelled = true;    

Properties

public TimeSpan Interval { get; set; } = TimeSpan.FromSeconds(1);

public bool Running { get; private set; }

Event

public event EventHandler RanToCompletion;

Usage

Source and demo code is available on the GitHub.

using IVSoftware.Portable;
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Threading.Tasks;

namespace testbench
{
    internal class Program
    {
        static void Main(string[] args)
        {
            runAsync();

            Console.ReadKey();
        }

        private static async void runAsync()
        {
            BringConsoleToFront();

            // Three second watchdog timer
            WatchdogTimer _wdt = new WatchdogTimer { Interval = TimeSpan.FromSeconds(3) };
            // System.Diagnostics.Stopwatch for testing purposes.
            Stopwatch _stopWatch = new Stopwatch();

            #region T E S T    A C T I O N
            Console.WriteLine("T E S T    A C T I O N");
            _stopWatch.Start();
            Console.WriteLine($"{_stopWatch.Elapsed} START");

            _wdt.StartOrRestart(()=> MarkEmailAsRead(id: 1));
            await Task.Delay(TimeSpan.FromSeconds(1));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(() => MarkEmailAsRead(id: 2));
            await Task.Delay(TimeSpan.FromSeconds(1));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(() => MarkEmailAsRead(id: 3)); 
            // Should run to completion
            await Task.Delay(TimeSpan.FromSeconds(4));
            Console.WriteLine(_stopWatch.Elapsed + Environment.NewLine);

            _wdt.StartOrRestart(() => MarkEmailAsRead(id: 10));
            await Task.Delay(TimeSpan.FromSeconds(2));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(() => MarkEmailAsRead(id: 20));
            await Task.Delay(TimeSpan.FromSeconds(1));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(() => MarkEmailAsRead(id: 30));
            // Should run to completion
            await Task.Delay(TimeSpan.FromSeconds(4));
            Console.WriteLine(_stopWatch.Elapsed + Environment.NewLine);
            #endregion T E S T    A C T I O N

            #region T E S T    C A N C E L
            Console.WriteLine("T E S T    C A N C E L");

            _stopWatch.Restart();
            Console.WriteLine($"{_stopWatch.Elapsed} START");

            _wdt.StartOrRestart(() => MarkEmailAsRead(id: 1), new CustomEventArgs(id: 1));
            await Task.Delay(TimeSpan.FromSeconds(1));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(() => MarkEmailAsRead(id: 2), new CustomEventArgs(id: 2));
            await Task.Delay(TimeSpan.FromSeconds(1));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(() => MarkEmailAsRead(id: 3), new CustomEventArgs(id: 3));
            // Cancel event and allow enough time to otherwise complete.
            await Task.Delay(TimeSpan.FromSeconds(2));
            _wdt.Cancel();
            await Task.Delay(TimeSpan.FromSeconds(2));
            Console.WriteLine(_stopWatch.Elapsed + Environment.NewLine);

            _wdt.StartOrRestart(() => MarkEmailAsRead(id: 10), new CustomEventArgs(id: 10));
            await Task.Delay(TimeSpan.FromSeconds(2));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(() => MarkEmailAsRead(id: 20), new CustomEventArgs(id: 20));
            await Task.Delay(TimeSpan.FromSeconds(1));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(() => MarkEmailAsRead(id: 30), new CustomEventArgs(id: 30));
            // Cancel event and allow enough time to otherwise complete.
            await Task.Delay(TimeSpan.FromSeconds(2));
            _wdt.Cancel();
            await Task.Delay(TimeSpan.FromSeconds(2));
            Console.WriteLine(_stopWatch.Elapsed + Environment.NewLine);
            #endregion T E S T    C A N C E L

            #region T E S T    E V E N T
            _wdt.RanToCompletion += onWdtRanToCompletion;

            Console.WriteLine("T E S T    E V E N T");
            _stopWatch.Restart();
            Console.WriteLine($"{_stopWatch.Elapsed} START");

            _wdt.StartOrRestart(new CustomEventArgs(id: 1));
            await Task.Delay(TimeSpan.FromSeconds(1));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(new CustomEventArgs(id: 2));
            await Task.Delay(TimeSpan.FromSeconds(1));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(new CustomEventArgs(id: 3));
            // Should run to completion
            await Task.Delay(TimeSpan.FromSeconds(4));
            Console.WriteLine(_stopWatch.Elapsed + Environment.NewLine);


            Console.WriteLine(_stopWatch.Elapsed);
            _wdt.StartOrRestart(new CustomEventArgs(id: 10));
            await Task.Delay(TimeSpan.FromSeconds(2));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(new CustomEventArgs(id: 20));
            await Task.Delay(TimeSpan.FromSeconds(1));
            Console.WriteLine(_stopWatch.Elapsed);

            _wdt.StartOrRestart(new CustomEventArgs(id: 30));
            // Should run to completion
            await Task.Delay(TimeSpan.FromSeconds(4));
            Console.WriteLine(_stopWatch.Elapsed + Environment.NewLine);
            Console.WriteLine($"DONE {_stopWatch.Elapsed}");
            #endregion T E S T    E V E N T


            #region L o c a l F x
            void MarkEmailAsRead(int id)
            {
                Console.WriteLine($"Expired: {_stopWatch.Elapsed}");
                Console.WriteLine($"The email with the ID '{id}' has been marked read");
            }

            void onWdtRanToCompletion(object sender, EventArgs e)
            {
                if (e is CustomEventArgs ePlus)
                {
                    Console.WriteLine($"Expired: {_stopWatch.Elapsed}");
                    Console.WriteLine($"The email with the ID '{ePlus.Id}' has been marked read");
                }
            }

            void BringConsoleToFront()
            {
                SetForegroundWindow(GetConsoleWindow());
            }
            #endregion L o c a l F x
        }
        
        [DllImport("kernel32.dll", ExactSpelling = true)]
        public static extern IntPtr GetConsoleWindow();

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool SetForegroundWindow(IntPtr hWnd);
    }
    class CustomEventArgs : EventArgs
    {
        public CustomEventArgs(int id)
        {
            Id = id;
        }

        public int Id { get; }
    }
}