This is the fourteenth part of the Async Wandering series. For your convenience you can find other parts in the table of contents in Part 1 – Why creating Form from WinForms in unit tests breaks async?
We already implemented Loom in C# with Fibers. This time, a piece of code which uses P/Invoke (instead of C++/CLI) and works in .NET 5 (on Windows).
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using System; using System.Collections.Concurrent; using System.Collections.Generic; using System.Runtime.InteropServices; using System.Threading; namespace AsyncWithFibers { class Program { static void Main(string[] args) { HKTMonadFiberAsync.Run(); } public static void WhereAmI(string what) { Console.WriteLine($"Thread {Thread.CurrentThread.ManagedThreadId} Time {DateTime.Now}: {what}"); } } public class FiberHelper { [DllImport("kernel32.dll")] static extern IntPtr ConvertThreadToFiber(IntPtr lpParameter); [DllImport("kernel32.dll")] static extern IntPtr CreateFiber(uint dwStackSize, IntPtr lpStartAddress, IntPtr lpParameter); [DllImport("kernel32.dll")] static extern IntPtr SwitchToFiber(IntPtr lpStartAddress); [DllImport("kernel32.dll")] static extern IntPtr DeleteFiber(IntPtr lpStartAddress); Dictionary<int, IntPtr> actions; public IntPtr fiberCaller; public FiberHelper() { actions = new Dictionary<int, IntPtr>(); } public void Convert() { actions.Add(0, ConvertThreadToFiber(IntPtr.Zero)); } public void Create(int action) { actions.Add(action, CreateFiber(1024 * 1024, fiberCaller, (IntPtr)action)); } public void Switch(int action) { Thread.Sleep(100); IntPtr param = actions[action]; SwitchToFiber(param); } public void Delete(int action) { DeleteFiber(actions[action]); } } public class HKTMonadFiberAsync { public static ConcurrentDictionary<int, byte> readyToGo = new ConcurrentDictionary<int, byte>(); public static ConcurrentDictionary<int, Action> allJobs = new ConcurrentDictionary<int, Action>(); public static FiberHelper helper = new FiberHelper(); public static int current; public static bool done; public static int StartFiber(int actionId) { allJobs[actionId](); if (actionId != 0) { HKTMonadFiberAsync.done = true; HKTMonadFiberAsync.helper.Switch(0); } return 0; } delegate int StartFiberDelegate(int actionId); public static void Run() { helper.fiberCaller = Marshal.GetFunctionPointerForDelegate((StartFiberDelegate)StartFiber); helper.Convert(); allJobs.TryAdd(1, RunInternal); readyToGo.TryAdd(1, 0); helper.Create(1); allJobs.TryAdd(2, SideJob); readyToGo.TryAdd(2, 0); helper.Create(2); while (true) { done = false; var keys = readyToGo.Keys.GetEnumerator(); while (keys.MoveNext()) { current = keys.Current; helper.Switch(current); if (done) { helper.Delete(current); Action action; allJobs.TryRemove(current, out action); byte b; readyToGo.TryRemove(current, out b); } } if (allJobs.IsEmpty) { break; } Thread.Sleep(1); } } private static void RunInternal() { Program.WhereAmI("\tBefore nesting"); RunInternalNested<AsyncBuilder>(); //RunInternalNested<IdBuilder>(); Program.WhereAmI("\tAfter nesting"); } private static void RunInternalNested<T>() where T : Builder, new() { Program.WhereAmI("\t\tBefore creating delay"); Delay<T>(2000); Program.WhereAmI("\t\tAfter sleeping"); var data = Data<T, string>("Some string"); Program.WhereAmI($"\t\tAfter creating data {data}"); } private static void Delay<T>(int timeout) where T : Builder, new() { var context = new T().Build<object>(); var timer = new Timer(_ => context.Complete(new object()), null, timeout, Timeout.Infinite); GC.KeepAlive(timer); context.Map((object)null, _ => timeout); } private static U Data<T, U>(U d) where T : Builder, new() { var context = new T().Build<U>(); return context.Map(d, _ => d); } private static void SideJob() { Program.WhereAmI("\tSide job"); } } public abstract class Builder { public abstract Monad<T> Build<T>(); } public class IdBuilder : Builder { public override Monad<T> Build<T>() { return new Id<T>(); } } public class AsyncBuilder : Builder { public override Monad<T> Build<T>() { return new Async<T>(); } } public interface Monad<T> { U Map<U>(T value, Func<T, U> lambda); void Complete(T t); } public class Id<T> : Monad<T> { private T t; public U Map<U>(T value, Func<T, U> lambda) { this.t = value; lock (this) { while (t == null) { Monitor.Wait(this); } } return lambda(this.t); } public void Complete(T t) { lock (this) { this.t = t; Monitor.PulseAll(this); } } } public class Async<T> : Monad<T> { private T t; private int current; public U Map<U>(T value, Func<T, U> lambda) { this.t = value; if (t == null) { this.current = HKTMonadFiberAsync.current; byte b; HKTMonadFiberAsync.readyToGo.TryRemove(this.current, out b); HKTMonadFiberAsync.helper.Switch(0); } return lambda(this.t); } public void Complete(T t) { this.t = t; HKTMonadFiberAsync.readyToGo.TryAdd(this.current, 0); } } } |
Crucial differences are in lines 22-65. We use P/Invoke and pass things as IntPtrs so they work in x86 and in x64. Also, notice the Marshal.GetFunctionPointerForDelegate in line 91 which allows us to call the managed code from the WinAPI.