use dotnet thread pool for keen parallel cringe

CringeLauncher/Utils/ThreadPoolScheduler.cs

@@ -0,0 +1,60 @@
+using System.Diagnostics;
+using System.Reflection;
+using HarmonyLib;
+using Havok;
+using ParallelTasks;
+using CringeTask = ParallelTasks.Task;
+
+namespace CringeLauncher.Utils;
+
+public class ThreadPoolScheduler : IWorkScheduler
+{
+    public void Schedule(CringeTask item)
+    {
+        ThreadPool.UnsafeQueueUserWorkItem(new ThreadPoolWorkItemTask(item), false);
+    }
+
+    public bool WaitForTasksToFinish(TimeSpan waitTimeout) => true;
+
+    public void ScheduleOnEachWorker(Action action)
+    {
+    }
+
+    public int ReadAndClearExecutionTime() => 0;
+
+    public void SuspendThreads(TimeSpan waitTimeout)
+    {
+    }
+
+    public void ResumeThreads()
+    {
+    }
+
+    public int ThreadCount { get; } = ThreadPool.ThreadCount;
+}
+
+[HarmonyPatch]
+internal class ThreadPoolWorkItemTask(CringeTask task) : IThreadPoolWorkItem
+{
+    public void Execute()
+    {
+        if (HkBaseSystem.IsInitialized && !HkBaseSystem.IsThreadInitialized) 
+            HkBaseSystem.InitThread(Thread.CurrentThread.Name);
+            
+        task.Execute();
+    }
+
+    private static MethodBase TargetMethod()
+    {
+        var type = Type.GetType("System.Threading.PortableThreadPool+WorkerThread, System.Private.CoreLib", true);
+        return AccessTools.DeclaredMethod(type, "WorkerThreadStart");
+    }
+
+    private static void Postfix()
+    {
+        if (!HkBaseSystem.IsInitialized || !HkBaseSystem.IsThreadInitialized) return;
+        
+        HkBaseSystem.QuitThread();
+        Debug.WriteLine($"Hk Shutdown for {Thread.CurrentThread.Name}");
+    }
+}