Remove ThreadPool native implementation (#71719)

* Remove UsePortableThreadPool() and UsePortableThreadPoolForIO()

* Delete win32threadpool.cpp and win32threadpool.h

* Delete hillclimbing stuff in function GetThreadpoolData in request.cpp

* Delete TPIndex

Co-authored-by: Stephen Toub <[email protected]>
Co-authored-by: Jan Kotas <[email protected]>

Author: 3 people

src/coreclr/System.Private.CoreLib/src/System/Threading/Overlapped.cs

@@ -25,41 +25,6 @@
 
 namespace System.Threading
 {
-    #region class _IOCompletionCallback
-
-    internal sealed unsafe partial class _IOCompletionCallback
-    {
-        // call back helper
-        internal static void PerformIOCompletionCallback(uint errorCode, uint numBytes, NativeOverlapped* pNativeOverlapped)
-        {
-            do
-            {
-                OverlappedData overlapped = OverlappedData.GetOverlappedFromNative(pNativeOverlapped);
-
-                if (overlapped._callback is IOCompletionCallback iocb)
-                {
-                    // We got here because of UnsafePack (or) Pack with EC flow suppressed
-                    iocb(errorCode, numBytes, pNativeOverlapped);
-                }
-                else
-                {
-                    // We got here because of Pack
-                    var helper = (_IOCompletionCallback?)overlapped._callback;
-                    Debug.Assert(helper != null, "Should only be receiving a completion callback if a delegate was provided.");
-                    helper._errorCode = errorCode;
-                    helper._numBytes = numBytes;
-                    helper._pNativeOverlapped = pNativeOverlapped;
-                    ExecutionContext.RunInternal(helper._executionContext, IOCompletionCallback_Context_Delegate, helper);
-                }
-
-                // Quickly check the VM again, to see if a packet has arrived.
-                OverlappedData.CheckVMForIOPacket(out pNativeOverlapped, out errorCode, out numBytes);
-            } while (pNativeOverlapped != null);
-        }
-    }
-
-    #endregion class _IOCompletionCallback
-
     #region class OverlappedData
 
     internal sealed unsafe class OverlappedData
@@ -120,9 +85,6 @@ internal sealed unsafe class OverlappedData
 
         [MethodImpl(MethodImplOptions.InternalCall)]
         internal static extern OverlappedData GetOverlappedFromNative(NativeOverlapped* nativeOverlappedPtr);
-
-        [MethodImpl(MethodImplOptions.InternalCall)]
-        internal static extern void CheckVMForIOPacket(out NativeOverlapped* pNativeOverlapped, out uint errorCode, out uint numBytes);
     }
 
     #endregion class OverlappedData

src/coreclr/System.Private.CoreLib/src/System/Threading/Thread.CoreCLR.cs

@@ -356,13 +356,6 @@ internal void ResetThreadPoolThread()
             Debug.Assert(this == CurrentThread);
             Debug.Assert(IsThreadPoolThread);
 
-            if (!ThreadPool.UsePortableThreadPool)
-            {
-                // Currently implemented in unmanaged method Thread::InternalReset and
-                // called internally from the ThreadPool in NotifyWorkItemComplete.
-                return;
-            }
-
             if (_mayNeedResetForThreadPool)
             {
                 ResetThreadPoolThreadSlow();

src/coreclr/System.Private.CoreLib/src/System/Threading/ThreadPool.CoreCLR.Windows.cs

@@ -18,32 +18,19 @@ public static unsafe bool UnsafeQueueNativeOverlapped(NativeOverlapped* overlapp
                 ThrowHelper.ThrowArgumentNullException(ExceptionArgument.overlapped);
             }
 
-            if (UsePortableThreadPoolForIO)
-            {
-                // OS doesn't signal handle, so do it here
-                overlapped->InternalLow = IntPtr.Zero;
-
-                PortableThreadPool.ThreadPoolInstance.QueueNativeOverlapped(overlapped);
-                return true;
-            }
+            // OS doesn't signal handle, so do it here
+            overlapped->InternalLow = IntPtr.Zero;
 
-            return PostQueuedCompletionStatus(overlapped);
+            PortableThreadPool.ThreadPoolInstance.QueueNativeOverlapped(overlapped);
+            return true;
         }
 
-        [MethodImpl(MethodImplOptions.InternalCall)]
-        private static extern unsafe bool PostQueuedCompletionStatus(NativeOverlapped* overlapped);
-
         [Obsolete("ThreadPool.BindHandle(IntPtr) has been deprecated. Use ThreadPool.BindHandle(SafeHandle) instead.")]
         [SupportedOSPlatform("windows")]
         public static bool BindHandle(IntPtr osHandle)
         {
-            if (UsePortableThreadPoolForIO)
-            {
-                PortableThreadPool.ThreadPoolInstance.RegisterForIOCompletionNotifications(osHandle);
-                return true;
-            }
-
-            return BindIOCompletionCallbackNative(osHandle);
+            PortableThreadPool.ThreadPoolInstance.RegisterForIOCompletionNotifications(osHandle);
+            return true;
         }
 
         [SupportedOSPlatform("windows")]
@@ -56,22 +43,14 @@ public static bool BindHandle(SafeHandle osHandle)
             {
                 osHandle.DangerousAddRef(ref mustReleaseSafeHandle);
 
-                if (UsePortableThreadPoolForIO)
-                {
-                    PortableThreadPool.ThreadPoolInstance.RegisterForIOCompletionNotifications(osHandle.DangerousGetHandle());
-                    return true;
-                }
-
-                return BindIOCompletionCallbackNative(osHandle.DangerousGetHandle());
+                PortableThreadPool.ThreadPoolInstance.RegisterForIOCompletionNotifications(osHandle.DangerousGetHandle());
+                return true;
             }
             finally
             {
                 if (mustReleaseSafeHandle)
                     osHandle.DangerousRelease();
             }
         }
-
-        [MethodImpl(MethodImplOptions.InternalCall)]
-        private static extern bool BindIOCompletionCallbackNative(IntPtr fileHandle);
     }
 }