refactor!: Major code cleanup for clearer state (#27)

* Quick pass

* no locks

* github actions

* publish via github actions

* pack

* Parent non-optional

* Generics are fun

* second pass

* Group workers, CTS, and Task in a class for simpler nullability

* pollysharp

* reverted cancellation changes

* reset state

* Update samples

* changes

* still working

* the fix

* private workers

* comments

* comments 2

* comments 3

* public worker count

GrasshopperAsyncComponent/GH_AsyncComponent.cs

@@ -1,51 +1,76 @@
-using System.Collections.Concurrent;
+using System.Collections.Concurrent;
 using System.Diagnostics;
 using Grasshopper.Kernel;
 using Timer = System.Timers.Timer;
 
 namespace GrasshopperAsyncComponent;
 
+internal sealed class Worker<T> : IDisposable
+    where T : GH_Component
+{
+    public required WorkerInstance<T> Instance { get; init; }
+
+    public required Task Task { get; init; }
+
+    public required CancellationTokenSource CancellationSource { get; init; }
+
+    public void Cancel() => CancellationSource.Cancel();
+
+    public void Dispose()
+    {
+        if (Task.IsCompleted)
+        {
+            Task.Dispose();
+        }
+        CancellationSource.Dispose();
+    }
+}
+
 /// <summary>
 /// Inherit your component from this class to make all the async goodness available.
 /// </summary>
-public abstract class GH_AsyncComponent : GH_Component, IDisposable
+public abstract class GH_AsyncComponent<T> : GH_Component, IDisposable
+    where T : GH_Component
 {
     //List<(string, GH_RuntimeMessageLevel)> Errors;
 
     private readonly Action<string, double> _reportProgress;
 
-    public ConcurrentDictionary<string, double> ProgressReports { get; protected set; }
+    public ConcurrentDictionary<string, double> ProgressReports { get; }
-
-    private readonly Action _done;
 
     private readonly Timer _displayProgressTimer;
 
-    private int _state;
+    /// <summary>
+    /// a counter, used to count up the number of workers that have completed,
+    /// until _setData is set true, when it starts to count down the workers as their data is set.
+    /// </summary>
+    private volatile int _state;
 
-    private int _setData;
+    /// <summary>
+    /// functionally, a boolean, 1 or 0;
+    /// it will be set to 1 once all workers are ready for SetData to be called on them, then set back to 0.
+    /// </summary>
+    private volatile int _setData;
 
-    public List<WorkerInstance> Workers { get; protected set; }
+    private readonly List<Worker<T>> _workers;
 
-    private readonly List<Task> _tasks;
+    public int WorkerCount => _workers.Count;
-
-    public List<CancellationTokenSource> CancellationSources { get; }
 
     /// <summary>
     /// Set this property inside the constructor of your derived component.
     /// </summary>
-    public WorkerInstance? BaseWorker { get; set; }
+    public WorkerInstance<T>? BaseWorker { get; set; }
 
     /// <summary>
     /// Optional: if you have opinions on how the default system task scheduler should treat your workers, set it here.
     /// </summary>
-    public TaskCreationOptions? TaskCreationOptions { get; set; }
+    public TaskCreationOptions TaskCreationOptions { get; set; } = TaskCreationOptions.None;
 
     protected GH_AsyncComponent(string name, string nickname, string description, string category, string subCategory)
         : base(name, nickname, description, category, subCategory)
     {
-        Workers = new List<WorkerInstance>();
+        _workers = new List<Worker<T>>();
-        CancellationSources = new List<CancellationTokenSource>();
+
-        _tasks = new List<Task>();
         ProgressReports = new ConcurrentDictionary<string, double>();
 
         _displayProgressTimer = new Timer(333) { AutoReset = false };
@@ -59,36 +84,36 @@ public abstract class GH_AsyncComponent : GH_Component, IDisposable
                 _displayProgressTimer.Start();
             }
         };
+    }
 
-        _done = () =>
+    private void Done()
+    {
+        Interlocked.Increment(ref _state);
+        if (_state == _workers.Count && _setData == 0)
         {
-            Interlocked.Increment(ref _state);
+            Interlocked.Exchange(ref _setData, 1);
-            if (_state == Workers.Count && _setData == 0)
-            {
-                Interlocked.Exchange(ref _setData, 1);
 
-                // We need to reverse the workers list to set the outputs in the same order as the inputs.
+            // We need to reverse the workers list to set the outputs in the same order as the inputs.
-                Workers.Reverse();
+            _workers.Reverse();
 
-                Rhino.RhinoApp.InvokeOnUiThread(
+            Rhino.RhinoApp.InvokeOnUiThread(
-                    (Action)
+                (Action)
-                        delegate
+                    delegate
-                        {
+                    {
-                            ExpireSolution(true);
+                        ExpireSolution(true);
-                        }
+                    }
-                );
+            );
-            }
+        }
-        };
     }
 
     public virtual void DisplayProgress(object sender, System.Timers.ElapsedEventArgs e)
     {
-        if (Workers.Count == 0 || ProgressReports.Values.Count == 0)
+        if (_workers.Count == 0 || ProgressReports.Values.Count == 0)
         {
             return;
         }
 
-        if (Workers.Count == 1)
+        if (_workers.Count == 1)
         {
             Message = ProgressReports.Values.Last().ToString("0.00%");
         }
@@ -100,7 +125,7 @@ public abstract class GH_AsyncComponent : GH_Component, IDisposable
                 total += kvp.Value;
             }
 
-            Message = (total / Workers.Count).ToString("0.00%");
+            Message = (total / _workers.Count).ToString("0.00%");
         }
 
         Rhino.RhinoApp.InvokeOnUiThread(
@@ -121,29 +146,24 @@ public abstract class GH_AsyncComponent : GH_Component, IDisposable
 
         Debug.WriteLine("Killing");
 
-        foreach (var source in CancellationSources)
+        foreach (var currentWorker in _workers)
         {
-            source.Cancel();
+            currentWorker.Cancel();
         }
 
-        CancellationSources.Clear();
+        ResetState();
-        Workers.Clear();
-        ProgressReports.Clear();
-        _tasks.Clear();
-
-        Interlocked.Exchange(ref _state, 0);
     }
 
     protected override void AfterSolveInstance()
     {
-        System.Diagnostics.Debug.WriteLine("After solve instance was called " + _state + " ? " + Workers.Count);
+        Debug.WriteLine("After solve instance was called " + _state + " ? " + _workers.Count);
         // We need to start all the tasks as close as possible to each other.
-        if (_state == 0 && _tasks.Count > 0 && _setData == 0)
+        if (_state == 0 && _workers.Count > 0 && _setData == 0)
         {
-            System.Diagnostics.Debug.WriteLine("After solve INVOKATION");
+            Debug.WriteLine("After solve INVOCATION");
-            foreach (var task in _tasks)
+            foreach (var worker in _workers)
             {
-                task.Start();
+                worker.Task.Start();
             }
         }
     }
@@ -170,31 +190,30 @@ public abstract class GH_AsyncComponent : GH_Component, IDisposable
 
             // Add cancellation source to our bag
             var tokenSource = new CancellationTokenSource();
-            CancellationSources.Add(tokenSource);
 
             var currentWorker = BaseWorker.Duplicate($"Worker-{da.Iteration}", tokenSource.Token);
-            if (currentWorker == null)
-            {
-                AddRuntimeMessage(GH_RuntimeMessageLevel.Error, "Could not get a worker instance.");
-                return;
-            }
 
             // Let the worker collect data.
             currentWorker.GetData(da, Params);
 
-            var currentRun =
+            var currentRun = new Task<Task>(
-                TaskCreationOptions != null
+                async () =>
-                    ? new Task(
+                {
-                        () => currentWorker.DoWork(_reportProgress, _done),
+                    await currentWorker.DoWork(_reportProgress, Done).ConfigureAwait(true);
-                        tokenSource.Token,
+                },
-                        (TaskCreationOptions)TaskCreationOptions
+                tokenSource.Token,
-                    )
+                TaskCreationOptions
-                    : new Task(() => currentWorker.DoWork(_reportProgress, _done), tokenSource.Token);
+            );
 
             // Add the worker to our list
-            Workers.Add(currentWorker);
+            _workers.Add(
-
+                new()
-            _tasks.Add(currentRun);
+                {
+                    Instance = currentWorker,
+                    Task = currentRun,
+                    CancellationSource = tokenSource,
+                }
+            );
 
             return;
         }
@@ -204,10 +223,10 @@ public abstract class GH_AsyncComponent : GH_Component, IDisposable
             return;
         }
 
-        if (Workers.Count > 0)
+        if (_workers.Count > 0)
         {
             Interlocked.Decrement(ref _state);
-            Workers[_state].SetData(da);
+            _workers[_state].Instance.SetData(da);
         }
 
         if (_state != 0)
@@ -215,31 +234,34 @@ public abstract class GH_AsyncComponent : GH_Component, IDisposable
             return;
         }
 
-        CancellationSources.Clear();
+        foreach (var worker in _workers)
-        Workers.Clear();
+        {
-        ProgressReports.Clear();
+            worker?.Dispose();
-        _tasks.Clear();
+        }
 
-        Interlocked.Exchange(ref _setData, 0);
+        ResetState();
 
         Message = "Done";
         OnDisplayExpired(true);
     }
 
-    public void RequestCancellation()
+    private void ResetState()
     {
-        foreach (var source in CancellationSources)
+        _workers.Clear();
-        {
-            source.Cancel();
-        }
-
-        CancellationSources.Clear();
-        Workers.Clear();
         ProgressReports.Clear();
-        _tasks.Clear();
 
         Interlocked.Exchange(ref _state, 0);
         Interlocked.Exchange(ref _setData, 0);
+    }
+
+    public void RequestCancellation()
+    {
+        foreach (var worker in _workers)
+        {
+            worker.Cancel();
+        }
+
+        ResetState();
         Message = "Cancelled";
         OnDisplayExpired(true);
     }
@@ -260,6 +282,10 @@ public abstract class GH_AsyncComponent : GH_Component, IDisposable
 
             if (disposing)
             {
+                foreach (var worker in _workers)
+                {
+                    worker?.Dispose();
+                }
                 _displayProgressTimer?.Dispose();
             }
         }

GrasshopperAsyncComponent/GrasshopperAsyncComponent.csproj

@@ -21,6 +21,7 @@
 
   <ItemGroup Label="Package References">
     <PackageReference Include="Grasshopper" Version="7.4.21078.1001" IncludeAssets="compile;build" PrivateAssets="all" />
+    <PackageReference Include="PolySharp" Version="1.14.1" />
   </ItemGroup>
 
   <ItemGroup>

GrasshopperAsyncComponent/WorkerInstance.cs

@@ -1,16 +1,17 @@
-using Grasshopper.Kernel;
+using Grasshopper.Kernel;
 
 namespace GrasshopperAsyncComponent;
 
 /// <summary>
-/// A class that holds the actual compute logic and encapsulates the state it needs. Every <see cref="GH_AsyncComponent"/> needs to have one.
+/// A class that holds the actual compute logic and encapsulates the state it needs. Every <see cref="GH_AsyncComponent{T}"/> needs to have one.
 /// </summary>
-public abstract class WorkerInstance(GH_Component? parent, string id, CancellationToken cancellationToken)
+public abstract class WorkerInstance<T>(T parent, string id, CancellationToken cancellationToken)
+    where T : GH_Component
 {
     /// <summary>
     /// The parent component. Useful for passing state back to the host component.
     /// </summary>
-    public GH_Component? Parent { get; set; } = parent;
+    public T Parent { get; set; } = parent;
 
     public CancellationToken CancellationToken { get; } = cancellationToken;
 
@@ -22,24 +23,29 @@ public abstract class WorkerInstance(GH_Component? parent, string id, Cancellati
     /// <param name="id">A Unique id for the new duplicate</param>
     /// <param name="cancellationToken">A cancellationToken to be passed to the new duplicate</param>
     /// <returns></returns>
-    public abstract WorkerInstance? Duplicate(string id, CancellationToken cancellationToken);
+    public abstract WorkerInstance<T> Duplicate(string id, CancellationToken cancellationToken);
 
     /// <summary>
     /// This method is where the actual calculation/computation/heavy lifting should be done.
-    /// <b>Make sure you always check as frequently as you can if <see cref="WorkerInstance.CancellationToken"/> is cancelled. For an example, see the PrimeCalculatorWorker example.</b>
+    /// <b>Make sure you always check as frequently as you can if <see cref="WorkerInstance{T}.CancellationToken"/> is cancelled. For an example, see the PrimeCalculatorWorker example.</b>
     /// </summary>
+    /// <remarks>
+    /// If you don't need <see langword="async"/> function, then you can simply return <see cref="Task.CompletedTask"/>
+    /// Either way, you should be sure to handle exceptions in this function. Otherwise, they will be Unobserved!
+    /// You can call <paramref name="done"/> on <see cref="Exception"/>s, but avoid calling it when cancellation is has been observed.
+    /// </remarks>
     /// <param name="reportProgress">Call this to report progress up to the parent component.</param>
     /// <param name="done">Call this when everything is <b>done</b>. It will tell the parent component that you're ready to <see cref="SetData(IGH_DataAccess)"/>.</param>
-    public abstract void DoWork(Action<string, double> reportProgress, Action done);
+    public abstract Task DoWork(Action<string, double> reportProgress, Action done);
 
     /// <summary>
-    /// Write your data setting logic here. <b>Do not call this function directly from this class. It will be invoked by the parent <see cref="GH_AsyncComponent"/> after you've called `Done` in the <see cref="DoWork"/> function.</b>
+    /// Write your data setting logic here. <b>Do not call this function directly from this class. It will be invoked by the parent <see cref="GH_AsyncComponent{T}"/> after you've called `Done` in the <see cref="DoWork"/> function.</b>
     /// </summary>
     /// <param name="da"></param>
     public abstract void SetData(IGH_DataAccess da);
 
     /// <summary>
-    /// Write your data collection logic here. <b>Do not call this method directly. It will be invoked by the parent <see cref="GH_AsyncComponent"/>.</b>
+    /// Write your data collection logic here. <b>Do not call this method directly. It will be invoked by the parent <see cref="GH_AsyncComponent{T}"/>.</b>
     /// </summary>
     /// <param name="da"></param>
     /// <param name="parameters"></param>

GrasshopperAsyncComponentDemo/SampleImplementations/Sample_PrimeCalculatorAsyncComponent.cs

@@ -1,10 +1,10 @@
-using System.Windows.Forms;
+using System.Windows.Forms;
 using Grasshopper.Kernel;
 using GrasshopperAsyncComponent;
 
 namespace GrasshopperAsyncComponentDemo.SampleImplementations;
 
-public class Sample_PrimeCalculatorAsyncComponent : GH_AsyncComponent
+public class Sample_PrimeCalculatorAsyncComponent : GH_AsyncComponent<Sample_PrimeCalculatorAsyncComponent>
 {
     public override Guid ComponentGuid => new Guid("22C612B0-2C57-47CE-B9FE-E10621F18933");
 
@@ -46,25 +46,38 @@ public class Sample_PrimeCalculatorAsyncComponent : GH_AsyncComponent
         );
     }
 
-    private sealed class PrimeCalculatorWorker : WorkerInstance
+    private sealed class PrimeCalculatorWorker : WorkerInstance<Sample_PrimeCalculatorAsyncComponent>
     {
         private int TheNthPrime { get; set; } = 100;
         private long ThePrime { get; set; } = -1;
 
         public PrimeCalculatorWorker(
-            GH_Component? parent,
+            Sample_PrimeCalculatorAsyncComponent parent,
             string id = "baseworker",
             CancellationToken cancellationToken = default
         )
             : base(parent, id, cancellationToken) { }
 
-        public override void DoWork(Action<string, double> reportProgress, Action done)
+        public override Task DoWork(Action<string, double> reportProgress, Action done)
+        {
+            try
+            {
+                CalculatePrimes(reportProgress);
+                done();
+            }
+            catch (OperationCanceledException) when (CancellationToken.IsCancellationRequested)
+            {
+                //No need to call `done()` - GrasshopperAsyncComponent assumes immediate cancel,
+                //thus it has already performed clean-up actions that would normally be done on `done()`
+            }
+
+            return Task.CompletedTask;
+        }
+
+        public void CalculatePrimes(Action<string, double> reportProgress)
         {
             // 👉 Checking for cancellation!
-            if (CancellationToken.IsCancellationRequested)
+            CancellationToken.ThrowIfCancellationRequested();
-            {
-                return;
-            }
 
             int count = 0;
             long a = 2;
@@ -73,20 +86,14 @@ public class Sample_PrimeCalculatorAsyncComponent : GH_AsyncComponent
             while (count < TheNthPrime)
             {
                 // 👉 Checking for cancellation!
-                if (CancellationToken.IsCancellationRequested)
+                CancellationToken.ThrowIfCancellationRequested();
-                {
-                    return;
-                }
 
                 long b = 2;
                 int prime = 1; // to check if found a prime
                 while (b * b <= a)
                 {
                     // 👉 Checking for cancellation!
-                    if (CancellationToken.IsCancellationRequested)
+                    CancellationToken.ThrowIfCancellationRequested();
-                    {
-                        return;
-                    }
 
                     if (a % b == 0)
                     {
@@ -106,11 +113,12 @@ public class Sample_PrimeCalculatorAsyncComponent : GH_AsyncComponent
             }
 
             ThePrime = --a;
-            done();
         }
 
-        public override WorkerInstance Duplicate(string id, CancellationToken cancellationToken) =>
+        public override WorkerInstance<Sample_PrimeCalculatorAsyncComponent> Duplicate(
-            new PrimeCalculatorWorker(Parent, id, cancellationToken);
+            string id,
+            CancellationToken cancellationToken
+        ) => new PrimeCalculatorWorker(Parent, id, cancellationToken);
 
         public override void GetData(IGH_DataAccess da, GH_ComponentParamServer parameters)
         {
@@ -131,12 +139,6 @@ public class Sample_PrimeCalculatorAsyncComponent : GH_AsyncComponent
 
         public override void SetData(IGH_DataAccess da)
         {
-            // 👉 Checking for cancellation!
-            if (CancellationToken.IsCancellationRequested)
-            {
-                return;
-            }
-
             da.SetData(0, ThePrime);
         }
     }

GrasshopperAsyncComponentDemo/SampleImplementations/Sample_UslessCyclesComponent.cs

@@ -1,10 +1,10 @@
-using System.Windows.Forms;
+using System.Windows.Forms;
 using Grasshopper.Kernel;
 using GrasshopperAsyncComponent;
 
 namespace GrasshopperAsyncComponentDemo.SampleImplementations;
 
-public class Sample_UselessCyclesAsyncComponent : GH_AsyncComponent
+public class Sample_UselessCyclesAsyncComponent : GH_AsyncComponent<Sample_UselessCyclesAsyncComponent>
 {
     public override Guid ComponentGuid => new Guid("DF2B93E2-052D-4BE4-BC62-90DC1F169BF6");
 
@@ -19,20 +19,33 @@ public class Sample_UselessCyclesAsyncComponent : GH_AsyncComponent
     }
 
     private sealed class UselessCyclesWorker(
-        GH_Component? parent,
+        Sample_UselessCyclesAsyncComponent parent,
         string id = "baseworker",
         CancellationToken cancellationToken = default
-    ) : WorkerInstance(parent, id, cancellationToken)
+    ) : WorkerInstance<Sample_UselessCyclesAsyncComponent>(parent, id, cancellationToken)
     {
         private int MaxIterations { get; set; } = 100;
 
-        public override void DoWork(Action<string, double> reportProgress, Action done)
+        public override Task DoWork(Action<string, double> reportProgress, Action done)
+        {
+            try
+            {
+                RunUselessCycles(reportProgress);
+                done();
+            }
+            catch (OperationCanceledException) when (CancellationToken.IsCancellationRequested)
+            {
+                //No need to call `done()` - GrasshopperAsyncComponent assumes immediate cancel,
+                //thus it has already performed clean-up actions that would normally be done on `done()`
+            }
+
+            return Task.CompletedTask;
+        }
+
+        public void RunUselessCycles(Action<string, double> reportProgress)
         {
             // Checking for cancellation
-            if (CancellationToken.IsCancellationRequested)
+            CancellationToken.ThrowIfCancellationRequested();
-            {
-                return;
-            }
 
             for (int i = 0; i <= MaxIterations; i++)
             {
@@ -45,17 +58,14 @@ public class Sample_UselessCyclesAsyncComponent : GH_AsyncComponent
                 reportProgress(Id, (i + 1) / (double)MaxIterations);
 
                 // Checking for cancellation
-                if (CancellationToken.IsCancellationRequested)
+                CancellationToken.ThrowIfCancellationRequested();
-                {
-                    return;
-                }
             }
-
-            done();
         }
 
-        public override WorkerInstance Duplicate(string id, CancellationToken cancellationToken) =>
+        public override WorkerInstance<Sample_UselessCyclesAsyncComponent> Duplicate(
-            new UselessCyclesWorker(Parent, id, cancellationToken);
+            string id,
+            CancellationToken cancellationToken
+        ) => new UselessCyclesWorker(Parent, id, cancellationToken);
 
         public override void GetData(IGH_DataAccess da, GH_ComponentParamServer parameters)
         {