Invocations refactoring

Mono.Debugging.Soft/SoftDebuggerAdaptor.cs

@@ -32,8 +32,7 @@
 using System.Reflection.Emit;
 using System.Collections.Generic;
 using System.Runtime.CompilerServices;
-using System.Threading;
-
+using System.Threading.Tasks;
 using Mono.Debugger.Soft;
 using Mono.Debugging.Backend;
 using Mono.Debugging.Evaluation;
@@ -2145,100 +2144,112 @@ static string MirrorStringToString (EvaluationContext ctx, StringMirror mirror)
 		}
 	}
 
-	class MethodCall: AsyncOperation
+	internal class SoftOperationResult : OperationResult<Value>
 	{
-		readonly InvokeOptions options = InvokeOptions.DisableBreakpoints | InvokeOptions.SingleThreaded;
+		public SoftOperationResult (Value result, bool resultIsException, Value[] outArgs) : base (result, resultIsException)
+		{
+			OutArgs = outArgs;
+		}
 
-		readonly ManualResetEvent shutdownEvent = new ManualResetEvent (false);
+		public Value[] OutArgs { get; private set; }
+	}
+
+	internal class SoftMethodCall: AsyncOperationBase<Value>
+	{
+		readonly InvokeOptions options = InvokeOptions.DisableBreakpoints | InvokeOptions.SingleThreaded;
 		readonly SoftEvaluationContext ctx;
 		readonly MethodMirror function;
 		readonly Value[] args;
-		readonly object obj;
-		IAsyncResult handle;
-		Exception exception;
-		IInvokeResult result;
-
-		public MethodCall (SoftEvaluationContext ctx, MethodMirror function, object obj, Value[] args, bool enableOutArgs)
+		readonly IInvocableMethodOwnerMirror obj;
+		IInvokeAsyncResult invokeAsyncResult;
+
+		public SoftMethodCall (SoftEvaluationContext ctx, MethodMirror function, IInvocableMethodOwnerMirror obj, Value[] args, bool enableOutArgs)
 		{
 			this.ctx = ctx;
 			this.function = function;
 			this.obj = obj;
 			this.args = args;
 			if (enableOutArgs) {
-				this.options |= InvokeOptions.ReturnOutArgs;
+				options |= InvokeOptions.ReturnOutArgs;
 			}
 			if (function.VirtualMachine.Version.AtLeast (2, 40)) {
-				this.options |= InvokeOptions.Virtual;
+				options |= InvokeOptions.Virtual;
 			}
 		}
 
 		public override string Description {
-			get {
-				return function.DeclaringType.FullName + "." + function.Name;
-			}
-		}
-
-		public override void Invoke ()
-		{
-			try {
-				var invocableMirror = obj as IInvocableMethodOwnerMirror;
-				if (invocableMirror != null) {
-					var optionsToInvoke = options;
-					if (obj is StructMirror) {
-						optionsToInvoke |= InvokeOptions.ReturnOutThis;
-					}
-					handle = invocableMirror.BeginInvokeMethod (ctx.Thread, function, args, optionsToInvoke, null, null);
+			get
+			{
+				try {
+					return function.DeclaringType.FullName + "." + function.Name;
+				}
+				catch (Exception e) {
+					DebuggerLoggingService.LogError ("Exception during getting description of method", e);
+					return "[Unknown method]";
 				}
-				else
-					throw new ArgumentException ("Soft debugger method calls cannot be invoked on objects of type " + obj.GetType ().Name);
-			} catch (InvocationException ex) {
-				ctx.Session.StackVersion++;
-				exception = ex;
-			} catch (Exception ex) {
-				ctx.Session.StackVersion++;
-				DebuggerLoggingService.LogError ("Error in soft debugger method call thread on " + GetInfo (), ex);
-				exception = ex;
 			}
 		}
 
-		public override void Abort ()
-		{
-			if (handle is IInvokeAsyncResult) {
-				var info = GetInfo ();
-				DebuggerLoggingService.LogMessage ("Aborting invocation of " + info);
-				((IInvokeAsyncResult) handle).Abort ();
-				// Don't wait for the abort to finish. The engine will do it.
-			} else {
-				throw new NotSupportedException ();
-			}
-		}
-
-		public override void Shutdown ()
-		{
-			shutdownEvent.Set ();
-		}
-
-		void EndInvoke ()
+		protected override Task<OperationResult<Value>> InvokeAsyncImpl ()
 		{
 			try {
-				result = ((IInvocableMethodOwnerMirror) obj).EndInvokeMethodWithResult (handle);
-			} catch (InvocationException ex) {
-				if (!Aborting && ex.Exception != null) {
-					string ename = ctx.Adapter.GetValueTypeName (ctx, ex.Exception);
-					var vref = ctx.Adapter.GetMember (ctx, null, ex.Exception, "Message");
-
-					exception = vref != null ? new Exception (ename + ": " + (string) vref.ObjectValue) : new Exception (ename);
-					return;
+				var optionsToInvoke = options;
+				if (obj is StructMirror) {
+					optionsToInvoke |= InvokeOptions.ReturnOutThis;
 				}
-				exception = ex;
-			} catch (Exception ex) {
-				DebuggerLoggingService.LogError ("Error in soft debugger method call thread on " + GetInfo (), ex);
-				exception = ex;
-			} finally {
-				ctx.Session.StackVersion++;
+				var tcs = new TaskCompletionSource<OperationResult<Value>> ();
+				invokeAsyncResult = (IInvokeAsyncResult)obj.BeginInvokeMethod (ctx.Thread, function, args, optionsToInvoke, ar => {
+					try {
+						if (Token.IsCancellationRequested) {
+							tcs.SetCanceled ();
+							return;
+						}
+						var endInvokeResult = obj.EndInvokeMethodWithResult (ar);
+						tcs.SetResult (new SoftOperationResult (endInvokeResult.Result, false, endInvokeResult.OutArgs));
+					}
+					catch (InvocationException ex) {
+						if (ex.Exception != null) {
+							tcs.SetResult (new SoftOperationResult (ex.Exception, true, null));
+						}
+						else {
+							tcs.SetException (new EvaluatorException ("Target method has thrown an exception but the exception object is inaccessible"));
+						}
+					}
+					catch (CommandException e) {
+						if (e.ErrorCode == ErrorCode.INVOKE_ABORTED) {
+							tcs.TrySetCanceled ();
+						}
+						else {
+							tcs.SetException (new EvaluatorException (e.Message));
+						}
+					}
+					catch (Exception e) {
+						if (e is ObjectCollectedException ||
+							e is InvalidStackFrameException ||
+							e is VMNotSuspendedException ||
+							e is NotSupportedException ||
+							e is AbsentInformationException ||
+							e is ArgumentException) {
+							// user meaningfull evaluation exception -> wrap with EvaluatorException that will be properly shown in value viewer
+							tcs.SetException (new EvaluatorException (e.Message));
+						}
+						else {
+							DebuggerLoggingService.LogError (string.Format ("Unexpected exception has thrown when ending invocation of {0}", GetInfo ()), e);
+							tcs.SetException (e);
+						}
+					}
+					finally {
+						UpdateSessionState ();
+					}
+				}, null);
+				return tcs.Task;
+			} catch (Exception e) {
+				UpdateSessionState ();
+				DebuggerLoggingService.LogError (string.Format ("Unexpected exception has thrown when invoking {0}", GetInfo ()), e);
+				throw;
 			}
 		}
-		
+
 		string GetInfo ()
 		{
 			try {
@@ -2250,41 +2261,26 @@ string GetInfo ()
 				else if (obj is StructMirror)
 					type = ((StructMirror)obj).Type;
 				return string.Format ("method {0} on object {1}",
-				                      function == null? "[null]" : function.FullName,
-				                      type == null? "[null]" : type.FullName);
+					function.FullName,
+					type == null? "[null]" : type.FullName);
 			} catch (Exception ex) {
 				DebuggerLoggingService.LogError ("Error getting info for SDB MethodCall", ex);
-				return "";
+				return "[Unknown method]";
 			}
 		}
 
-		public override bool WaitForCompleted (int timeout)
+		void UpdateSessionState ()
 		{
-			if (handle == null)
-				return true;
-			int res = WaitHandle.WaitAny (new WaitHandle[] { handle.AsyncWaitHandle, shutdownEvent }, timeout); 
-			if (res == 0) {
-				EndInvoke ();
-				return true;
-			}
-			// Return true if shut down.
-			return res == 1;
-		}
-
-		public Value ReturnValue {
-			get {
-				if (exception != null)
-					throw new EvaluatorException (exception.Message);
-				return result.Result;
-			}
+			ctx.Session.StackVersion++;
 		}
 
-		public Value[] OutArgs {
-			get {
-				if (exception != null)
-					throw new EvaluatorException (exception.Message);
-				return result.OutArgs;
+		protected override void AbortImpl (int abortCallTimes)
+		{
+			if (invokeAsyncResult == null) {
+				DebuggerLoggingService.LogError ("invokeAsyncResult is null", new ArgumentNullException ("invokeAsyncResult"));
+				return;
 			}
+			invokeAsyncResult.Abort ();
 		}
 	}
 }

Mono.Debugging.Soft/SoftEvaluationContext.cs

@@ -190,16 +190,19 @@ Value RuntimeInvoke (MethodMirror method, object target, Value[] values, bool en
 					DC.DebuggerLoggingService.LogMessage ("Thread state before evaluation is {0}", threadState);
 					throw new EvaluatorException ("Evaluation is not allowed when the thread is in 'Wait' state");
 				}
-				var mc = new MethodCall (this, method, target, values, enableOutArgs);
+				var invocableMirror = target as IInvocableMethodOwnerMirror;
+				if (invocableMirror == null)
+					throw new ArgumentException ("Soft debugger method calls cannot be invoked on objects of type " + target.GetType ().Name);
+				var mc = new SoftMethodCall (this, method, invocableMirror, values, enableOutArgs);
 				//Since runtime is returning NOT_SUSPENDED error if two methods invokes are executed
 				//at same time we have to lock invoking to prevent this...
 				lock (method.VirtualMachine) {
-					Adapter.AsyncExecute (mc, Options.EvaluationTimeout);
-				}
-				if (enableOutArgs) {
-					outArgs = mc.OutArgs;
+					var result = (SoftOperationResult)Adapter.InvokeSync (mc, Options.EvaluationTimeout).ThrowIfException (this);
+					if (enableOutArgs) {
+						outArgs = result.OutArgs;
+					}
+					return result.Result;
 				}
-				return mc.ReturnValue;
 			}
 		}
 

Mono.Debugging.Win32/CorDebuggerSession.cs

@@ -111,6 +111,13 @@ public static int EvaluationTimestamp {
 			get { return evaluationTimestamp; }
 		}
 
+		internal CorProcess Process
+		{
+			get
+			{
+				return process;
+			}
+		}
 
 		public override void Dispose ( )
 		{
@@ -1417,49 +1424,16 @@ public CorValue RuntimeInvoke (CorEvaluationContext ctx, CorFunction function, C
 				arguments.CopyTo (args, 1);
 			}
 
-			CorMethodCall mc = new CorMethodCall ();
-			CorValue exception = null;
-			CorEval eval = ctx.Eval;
-
-			DebugEventHandler<CorEvalEventArgs> completeHandler = delegate (object o, CorEvalEventArgs eargs) {
-				OnEndEvaluating ();
-				mc.DoneEvent.Set ();
-				eargs.Continue = false;
-			};
-
-			DebugEventHandler<CorEvalEventArgs> exceptionHandler = delegate(object o, CorEvalEventArgs eargs) {
-				OnEndEvaluating ();
-				exception = eargs.Eval.Result;
-				mc.DoneEvent.Set ();
-				eargs.Continue = false;
-			};
-
-			process.OnEvalComplete += completeHandler;
-			process.OnEvalException += exceptionHandler;
-
-			mc.OnInvoke = delegate {
-				if (function.GetMethodInfo (this).Name == ".ctor")
-					eval.NewParameterizedObject (function, typeArgs, args);
-				else
-					eval.CallParameterizedFunction (function, typeArgs, args);
-				process.SetAllThreadsDebugState (CorDebugThreadState.THREAD_SUSPEND, ctx.Thread);
-				ClearEvalStatus ();
-				OnStartEvaluating ();
-				process.Continue (false);
-			};
-			mc.OnAbort = delegate {
-				eval.Abort ();
-			};
-			mc.OnGetDescription = delegate {
-				MethodInfo met = function.GetMethodInfo (ctx.Session);
-				if (met != null)
-					return met.DeclaringType.FullName + "." + met.Name;
-				else
-					return "<Unknown>";
-			};
-
+			var methodCall = new CorMethodCall (ctx, function, typeArgs, args);
 			try {
-				ObjectAdapter.AsyncExecute (mc, ctx.Options.EvaluationTimeout);
+				var result = ObjectAdapter.InvokeSync (methodCall, ctx.Options.EvaluationTimeout);
+				if (result.ResultIsException) {
+					var vref = new CorValRef (result.Result);
+					throw new EvaluatorExceptionThrownException (vref, ObjectAdapter.GetValueTypeName (ctx, vref));
+				}
+
+				WaitUntilStopped ();
+				return result.Result;
 			}
 			catch (COMException ex) {
 				// eval exception is a 'good' exception that should be shown in value box
@@ -1469,35 +1443,16 @@ public CorValue RuntimeInvoke (CorEvaluationContext ctx, CorFunction function, C
 					throw evalException;
 				throw;
 			}
-			finally {
-				process.OnEvalComplete -= completeHandler;
-				process.OnEvalException -= exceptionHandler;
-			}
-
-			WaitUntilStopped ();
-			if (exception != null) {
-/*				ValueReference<CorValue, CorType> msg = ctx.Adapter.GetMember (ctx, val, "Message");
-				if (msg != null) {
-					string s = msg.ObjectValue as string;
-					mc.ExceptionMessage = s;
-				}
-				else
-					mc.ExceptionMessage = "Evaluation failed.";*/
-				CorValRef vref = new CorValRef (exception);
-				throw new EvaluatorException ("Evaluation failed: " + ObjectAdapter.GetValueTypeName (ctx, vref));
-			}
-
-			return eval.Result;
 		}
 
-		void OnStartEvaluating ( )
+		internal void OnStartEvaluating ( )
 		{
 			lock (debugLock) {
 				evaluating = true;
 			}
 		}
 
-		void OnEndEvaluating ( )
+		internal void OnEndEvaluating ( )
 		{
 			lock (debugLock) {
 				evaluating = false;
@@ -1603,7 +1558,7 @@ public void WaitUntilStopped ()
 			}
 		}
 
-		void ClearEvalStatus ( )
+		internal void ClearEvalStatus ( )
 		{
 			foreach (CorProcess p in dbg.Processes) {
 				if (p.Id == processId) {

Mono.Debugging.Win32/CorMethodCall.cs

@@ -1,47 +1,143 @@
-using System.Threading;
+using System;
+using System.Runtime.InteropServices;
+using System.Threading.Tasks;
+using Microsoft.Samples.Debugging.CorDebug;
+using Microsoft.Samples.Debugging.CorDebug.NativeApi;
+using Mono.Debugging.Client;
 using Mono.Debugging.Evaluation;
 
 namespace Mono.Debugging.Win32
 {
-	class CorMethodCall: AsyncOperation
+	class CorMethodCall: AsyncOperationBase<CorValue>
 	{
-		public delegate void CallCallback ( );
-		public delegate string DescriptionCallback ( );
+		readonly CorEvaluationContext context;
+		readonly CorFunction function;
+		readonly CorType[] typeArgs;
+		readonly CorValue[] args;
 
-		public CallCallback OnInvoke;
-		public CallCallback OnAbort;
-		public DescriptionCallback OnGetDescription;
+		readonly CorEval eval;
 
-		public ManualResetEvent DoneEvent = new ManualResetEvent (false);
-
-		public override string Description
+		public CorMethodCall (CorEvaluationContext context, CorFunction function, CorType[] typeArgs, CorValue[] args)
 		{
-			get { return OnGetDescription (); }
+			this.context = context;
+			this.function = function;
+			this.typeArgs = typeArgs;
+			this.args = args;
+			eval = context.Eval;
 		}
 
-		public override void Invoke ( )
+		void ProcessOnEvalComplete (object sender, CorEvalEventArgs evalArgs)
 		{
-			OnInvoke ();
+			DoProcessEvalFinished (evalArgs, false);
 		}
 
-		public override void Abort ( )
+		void ProcessOnEvalException (object sender, CorEvalEventArgs evalArgs)
 		{
-			OnAbort ();
+			DoProcessEvalFinished (evalArgs, true);
 		}
 
-		public override void Shutdown ( )
+		void DoProcessEvalFinished (CorEvalEventArgs evalArgs, bool isException)
 		{
-			try {
-				Abort ();
+			if (evalArgs.Eval != eval)
+				return;
+			context.Session.OnEndEvaluating ();
+			evalArgs.Continue = false;
+			if (Token.IsCancellationRequested) {
+				DebuggerLoggingService.LogMessage ("EvalFinished() but evaluation was cancelled");
+				tcs.TrySetCanceled ();
 			}
-			catch {
+			else {
+				DebuggerLoggingService.LogMessage ("EvalFinished(). Setting the result");
+				tcs.TrySetResult(new OperationResult<CorValue> (evalArgs.Eval.Result, isException));
 			}
-			DoneEvent.Set ();
 		}
 
-		public override bool WaitForCompleted (int timeout)
+		void SubscribeOnEvals ()
+		{
+			context.Session.Process.OnEvalComplete += ProcessOnEvalComplete;
+			context.Session.Process.OnEvalException += ProcessOnEvalException;
+		}
+
+		void UnSubcribeOnEvals ()
 		{
-			return DoneEvent.WaitOne (timeout, false);
+			context.Session.Process.OnEvalComplete -= ProcessOnEvalComplete;
+			context.Session.Process.OnEvalException -= ProcessOnEvalException;
+		}
+
+		public override string Description
+		{
+			get
+			{
+				var met = function.GetMethodInfo (context.Session);
+				if (met == null)
+					return "[Unknown method]";
+				if (met.DeclaringType == null)
+					return met.Name;
+				return met.DeclaringType.FullName + "." + met.Name;
+			}
+		}
+
+		readonly TaskCompletionSource<OperationResult<CorValue>> tcs = new TaskCompletionSource<OperationResult<CorValue>> ();
+
+		protected override Task<OperationResult<CorValue>> InvokeAsyncImpl ()
+		{
+			SubscribeOnEvals ();
+
+			if (function.GetMethodInfo (context.Session).Name == ".ctor")
+				eval.NewParameterizedObject (function, typeArgs, args);
+			else
+				eval.CallParameterizedFunction (function, typeArgs, args);
+			context.Session.Process.SetAllThreadsDebugState (CorDebugThreadState.THREAD_SUSPEND, context.Thread);
+			context.Session.ClearEvalStatus ();
+			context.Session.OnStartEvaluating ();
+			context.Session.Process.Continue (false);
+			Task = tcs.Task;
+			// Don't pass token here, because it causes immediately task cancellation which must be performed by debugger event or real timeout
+			return Task.ContinueWith (task => {
+				UnSubcribeOnEvals ();
+				return task.Result;
+			});
+		}
+
+
+		protected override void AbortImpl (int abortCallTimes)
+		{
+			try {
+				if (abortCallTimes < 10) {
+					DebuggerLoggingService.LogMessage ("Calling Abort() for {0} time", abortCallTimes);
+					eval.Abort ();
+				}
+				else {
+					if (abortCallTimes == 20) {
+						// if Abort() and RudeAbort() didn't bring any result let's try to resume all the threads to free possible deadlocks in target process
+						// maybe this can help to abort hanging evaluations
+						DebuggerLoggingService.LogMessage ("RudeAbort() didn't stop eval after {0} times", abortCallTimes - 1);
+						DebuggerLoggingService.LogMessage ("Calling Stop()");
+						context.Session.Process.Stop (0);
+						DebuggerLoggingService.LogMessage ("Calling SetAllThreadsDebugState(THREAD_RUN)");
+						context.Session.Process.SetAllThreadsDebugState (CorDebugThreadState.THREAD_RUN, null);
+						DebuggerLoggingService.LogMessage ("Calling Continue()");
+						context.Session.Process.Continue (false);
+					}
+					DebuggerLoggingService.LogMessage ("Calling RudeAbort() for {0} time", abortCallTimes);
+					eval.RudeAbort();
+				}
+
+			} catch (COMException e) {
+				var hResult = e.ToHResult<HResult> ();
+				switch (hResult) {
+					case HResult.CORDBG_E_PROCESS_TERMINATED:
+						DebuggerLoggingService.LogMessage ("Process was terminated. Set cancelled for eval");
+						tcs.TrySetCanceled ();
+						return;
+					case HResult.CORDBG_E_OBJECT_NEUTERED:
+						DebuggerLoggingService.LogMessage ("Eval object was neutered. Set cancelled for eval");
+						tcs.TrySetCanceled ();
+						return;
+				}
+				tcs.SetException (e);
+				throw;
+			}
 		}
 	}
 }

Mono.Debugging/Mono.Debugging.Client/ObjectValue.cs

@@ -32,6 +32,7 @@
 using System.Linq;
 
 using Mono.Debugging.Backend;
+using Mono.Debugging.Evaluation;
 
 namespace Mono.Debugging.Client
 {
@@ -151,8 +152,18 @@ public static ObjectValue CreateError (IObjectValueSource source, ObjectPath pat
 			val.value = value;
 			return val;
 		}
-
-		public static ObjectValue CreateImplicitNotSupported (IObjectValueSource source, ObjectPath path, string typeName, ObjectValueFlags flags)
+
+		public static ObjectValue CreateEvaluationException (EvaluationContext ctx, IObjectValueSource source, ObjectPath path, EvaluatorExceptionThrownException exception,
+			ObjectValueFlags flags = ObjectValueFlags.None)
+		{
+			var error = CreateError (source, path, exception.ExceptionTypeName, "Exception was thrown", flags);
+			var exceptionReference = LiteralValueReference.CreateTargetObjectLiteral (ctx, "Exception", exception.Exception);
+			var exceptionValue = exceptionReference.CreateObjectValue (ctx.Options);
+			error.children = new List<ObjectValue> {exceptionValue};
+			return error;
+		}
+
+	  public static ObjectValue CreateImplicitNotSupported (IObjectValueSource source, ObjectPath path, string typeName, ObjectValueFlags flags)
 		{
 			var val = Create (source, path, typeName);
 			val.flags = flags | ObjectValueFlags.ImplicitNotSupported;
@@ -530,8 +541,7 @@ public ObjectValue[] GetAllChildren (EvaluationOptions options)
 						ConnectCallbacks (parentFrame, cs);
 						children.AddRange (cs);
 					} catch (Exception ex) {
-						if (parentFrame != null)
-							parentFrame.DebuggerSession.OnDebuggerOutput (true, ex.ToString ());
+						DebuggerLoggingService.LogError ("Exception in GetAllChildren()", ex);
 						children.Add (CreateFatalError ("", ex.Message, ObjectValueFlags.ReadOnly));
 					}
 				}

Mono.Debugging/Mono.Debugging.Evaluation/AsyncEvaluationTracker.cs

@@ -41,7 +41,7 @@ namespace Mono.Debugging.Evaluation
 	/// will then be made asynchronous and the Run method will immediately return an ObjectValue
 	/// with the Evaluating state.
 	/// </summary>
-	public class AsyncEvaluationTracker: RemoteFrameObject, IObjectValueUpdater, IDisposable
+	public class AsyncEvaluationTracker: IObjectValueUpdater, IDisposable
 	{
 		Dictionary<string, UpdateCallback> asyncCallbacks = new Dictionary<string, UpdateCallback> ();
 		Dictionary<string, ObjectValue> asyncResults = new Dictionary<string, ObjectValue> ();

Mono.Debugging/Mono.Debugging.Evaluation/AsyncOperationBase.cs

@@ -0,0 +1,94 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Mono.Debugging.Client;
+
+namespace Mono.Debugging.Evaluation
+{
+	public class OperationResult<TValue>
+	{
+		public TValue Result { get; private set; }
+		public bool ResultIsException { get; private set; }
+
+		public OperationResult (TValue result, bool resultIsException)
+		{
+			Result = result;
+			ResultIsException = resultIsException;
+		}
+	}
+
+	public static class OperationResultEx
+	{
+		public static OperationResult<TValue> ThrowIfException<TValue> (this OperationResult<TValue> result, EvaluationContext ctx)
+		{
+			if (!result.ResultIsException)
+				return result;
+			var exceptionTypeName = ctx.Adapter.GetValueTypeName (ctx, result.Result);
+			throw new EvaluatorExceptionThrownException (result.Result, exceptionTypeName);
+		}
+	}
+
+	public interface IAsyncOperationBase
+	{
+		Task RawTask { get; }
+		string Description { get; }
+		void Abort ();
+	}
+
+	public abstract class AsyncOperationBase<TValue> : IAsyncOperationBase
+	{
+		public Task<OperationResult<TValue>> Task { get; protected set; }
+
+		public Task RawTask
+		{
+			get
+			{
+				return Task;
+			}
+		}
+
+		public abstract string Description { get; }
+
+		int abortCalls = 0;
+
+		readonly CancellationTokenSource tokenSource = new CancellationTokenSource ();
+
+		/// <summary>
+		/// When evaluation is aborted and debugger callback is invoked the implementation has to check
+		/// for Token.IsCancellationRequested and call Task.SetCancelled() instead of setting the result
+		/// </summary>
+		protected CancellationToken Token { get { return tokenSource.Token; } }
+
+		public void Abort ()
+		{
+			try {
+				tokenSource.Cancel();
+				AbortImpl (Interlocked.Increment (ref abortCalls) - 1);
+			}
+			catch (OperationCanceledException) {
+				// if CancelImpl throw OCE we shouldn't mute it
+				throw;
+			}
+			catch (Exception e) {
+				DebuggerLoggingService.LogMessage ("Exception in CancelImpl(): {0}", e.Message);
+			}
+		}
+
+		public Task<OperationResult<TValue>> InvokeAsync ()
+		{
+			if (Task != null) throw new Exception("Task must be null");
+			Task = InvokeAsyncImpl ();
+			return Task;
+		}
+
+		protected abstract Task<OperationResult<TValue>> InvokeAsyncImpl ();
+
+		/// <summary>
+		/// The implementation has to tell the debugger to abort the evaluation. This method must bot block.
+		/// </summary>
+		/// <param name="abortCallTimes">indicates how many times this method has been already called for this evaluation.
+		/// E.g. the implementation can perform some 'rude abort' after several previous ordinary 'aborts' were failed. For the first call this parameter == 0</param>
+		protected abstract void AbortImpl (int abortCallTimes);
+
+	}
+}

Mono.Debugging/Mono.Debugging.Evaluation/AsyncOperationManager.cs

@@ -27,215 +27,163 @@
 
 using System;
 using System.Collections.Generic;
-using ST = System.Threading;
+using System.Linq;
+using System.Threading.Tasks;
 using Mono.Debugging.Client;
 
 namespace Mono.Debugging.Evaluation
 {
-	public class AsyncOperationManager: IDisposable
+	public class AsyncOperationManager : IDisposable
 	{
-		List<AsyncOperation> operationsToCancel = new List<AsyncOperation> ();
-		internal bool Disposing;
+		readonly HashSet<IAsyncOperationBase> currentOperations = new HashSet<IAsyncOperationBase> ();
+		bool disposed = false;
+		const int ShortCancelTimeout = 100;
 
-		public void Invoke (AsyncOperation methodCall, int timeout)
+		static bool IsOperationCancelledException (Exception e, int depth = 4)
 		{
-			methodCall.Aborted = false;
-			methodCall.Manager = this;
+			if (e is OperationCanceledException)
+				return true;
+			var aggregateException = e as AggregateException;
 
-			lock (operationsToCancel) {
-				operationsToCancel.Add (methodCall);
-				methodCall.Invoke ();
+			if (depth > 0 && aggregateException != null) {
+				foreach (var innerException in aggregateException.InnerExceptions) {
+					if (IsOperationCancelledException (innerException, depth - 1))
+						return true;
+				}
+			}
+			return false;
+		}
+
+		public OperationResult<TValue> Invoke<TValue> (AsyncOperationBase<TValue> mc, int timeout)
+		{
+			if (timeout <= 0)
+				throw new ArgumentOutOfRangeException("timeout", timeout, "timeout must be greater than 0");
+
+			Task<OperationResult<TValue>> task;
+			var description = mc.Description;
+			lock (currentOperations) {
+				if (disposed)
+					throw new ObjectDisposedException ("Already disposed");
+				DebuggerLoggingService.LogMessage (string.Format("Starting invoke for {0}", description));
+				task = mc.InvokeAsync ();
+				currentOperations.Add (mc);
 			}
 
-			if (timeout > 0) {
-				if (!methodCall.WaitForCompleted (timeout)) {
-					bool wasAborted = methodCall.Aborted;
-					methodCall.InternalAbort ();
-					lock (operationsToCancel) {
-						operationsToCancel.Remove (methodCall);
-						ST.Monitor.PulseAll (operationsToCancel);
+			bool cancelledAfterTimeout = false;
+			try {
+				if (task.Wait (timeout)) {
+					DebuggerLoggingService.LogMessage (string.Format ("Invoke {0} succeeded in {1} ms", description, timeout));
+					return task.Result;
+				}
+				DebuggerLoggingService.LogMessage (string.Format ("Invoke {0} timed out after {1} ms. Cancelling.", description, timeout));
+				mc.Abort ();
+				try {
+					WaitAfterCancel (mc);
+				}
+				catch (Exception e) {
+					if (IsOperationCancelledException (e)) {
+						DebuggerLoggingService.LogMessage (string.Format ("Invoke {0} was cancelled after timeout", description));
+						cancelledAfterTimeout = true;
 					}
-					if (wasAborted)
-						throw new EvaluatorAbortedException ();
-					else
-						throw new TimeOutException ();
+					throw;
 				}
+				DebuggerLoggingService.LogMessage (string.Format ("{0} cancelling timed out", description));
+				throw new TimeOutException ();
 			}
-			else {
-				methodCall.WaitForCompleted (System.Threading.Timeout.Infinite);
-			}
-
-			lock (operationsToCancel) {
-				operationsToCancel.Remove (methodCall);
-				ST.Monitor.PulseAll (operationsToCancel);
-				if (methodCall.Aborted) {
+			catch (Exception e) {
+				if (IsOperationCancelledException (e)) {
+					if (cancelledAfterTimeout)
+						throw new TimeOutException ();
+					DebuggerLoggingService.LogMessage (string.Format ("Invoke {0} was cancelled outside before timeout", description));
 					throw new EvaluatorAbortedException ();
 				}
+				throw;
+			}
+			finally {
+				lock (currentOperations) {
+					currentOperations.Remove (mc);
+				}
 			}
+		}
+
 
-			if (!string.IsNullOrEmpty (methodCall.ExceptionMessage)) {
-				throw new Exception (methodCall.ExceptionMessage);
+		public event EventHandler<BusyStateEventArgs> BusyStateChanged = delegate {  };
+
+		void ChangeBusyState (bool busy, string description)
+		{
+			try {
+				BusyStateChanged (this, new BusyStateEventArgs {IsBusy = busy, Description = description});
+			}
+			catch (Exception e) {
+				DebuggerLoggingService.LogError ("Exception during ChangeBusyState", e);
 			}
 		}
-		
-		public void Dispose ()
+
+		void WaitAfterCancel (IAsyncOperationBase op)
 		{
-			Disposing = true;
-			lock (operationsToCancel) {
-				foreach (AsyncOperation op in operationsToCancel) {
-					op.InternalShutdown ();
+			var desc = op.Description;
+			DebuggerLoggingService.LogMessage (string.Format ("Waiting for cancel of invoke {0}", desc));
+			if (!op.RawTask.Wait (ShortCancelTimeout)) {
+				try {
+					ChangeBusyState (true, desc);
+					while (true) {
+						op.Abort ();
+						if (op.RawTask.Wait (ShortCancelTimeout))
+							break;
+					}
+				}
+				finally {
+					ChangeBusyState (false, desc);
 				}
-				operationsToCancel.Clear ();
 			}
 		}
 
 		public void AbortAll ()
 		{
-			lock (operationsToCancel) {
-				foreach (AsyncOperation op in operationsToCancel)
-					op.InternalAbort ();
+			DebuggerLoggingService.LogMessage ("Aborting all the current invocations");
+			List<IAsyncOperationBase> copy;
+			lock (currentOperations) {
+				if (disposed) throw new ObjectDisposedException ("Already disposed");
+				copy = currentOperations.ToList ();
+				currentOperations.Clear ();
 			}
+
+			CancelOperations (copy, true);
 		}
-
-		public void EnterBusyState (AsyncOperation oper)
-		{
-			BusyStateEventArgs args = new BusyStateEventArgs ();
-			args.IsBusy = true;
-			args.Description = oper.Description;
-			if (BusyStateChanged != null)
-				BusyStateChanged (this, args);
-		}
-
-		public void LeaveBusyState (AsyncOperation oper)
-		{
-			BusyStateEventArgs args = new BusyStateEventArgs ();
-			args.IsBusy = false;
-			args.Description = oper.Description;
-			if (BusyStateChanged != null)
-				BusyStateChanged (this, args);
-		}
-
-		public event EventHandler<BusyStateEventArgs> BusyStateChanged;
-	}
 
-	public abstract class AsyncOperation
-	{
-		internal bool Aborted;
-		internal AsyncOperationManager Manager;
-
-		public bool Aborting { get; internal set; }
-
-		internal void InternalAbort ()
+		void CancelOperations (List<IAsyncOperationBase> operations, bool wait)
 		{
-			ST.Monitor.Enter (this);
-			if (Aborted) {
-				ST.Monitor.Exit (this);
-				return;
-			}
-
-			if (Aborting) {
-				// Somebody else is aborting this. Just wait for it to finish.
-				ST.Monitor.Exit (this);
-				WaitForCompleted (ST.Timeout.Infinite);
-				return;
-			}
-
-			Aborting = true;
-
-			int abortState = 0;
-			int abortRetryWait = 100;
-			bool abortRequested = false;
-
-			do {
-				if (abortState > 0)
-					ST.Monitor.Enter (this);
-
+			foreach (var operation in operations) {
+				var taskDescription = operation.Description;
 				try {
-					if (!Aborted && !abortRequested) {
-						// The Abort() call doesn't block. WaitForCompleted is used below to wait for the abort to succeed
-						Abort ();
-						abortRequested = true;
-					}
-					// Short wait for the Abort to finish. If this wait is not enough, it will wait again in the next loop
-					if (WaitForCompleted (100)) {
-						ST.Monitor.Exit (this);
-						break;
+					operation.Abort ();
+					if (wait) {
+						WaitAfterCancel (operation);
 					}
-				} catch {
-					// If abort fails, try again after a short wait
 				}
-				abortState++;
-				if (abortState == 6) {
-					// Several abort calls have failed. Inform the user that the debugger is busy
-					abortRetryWait = 500;
-					try {
-						Manager.EnterBusyState (this);
-					} catch (Exception ex) {
-						Console.WriteLine (ex);
+				catch (Exception e) {
+					if (IsOperationCancelledException (e)) {
+						DebuggerLoggingService.LogMessage (string.Format ("Invocation of {0} cancelled in CancelOperations()", taskDescription));
+					}
+					else {
+						DebuggerLoggingService.LogError (string.Format ("Invocation of {0} thrown an exception in CancelOperations()", taskDescription), e);
 					}
-				}
-				ST.Monitor.Exit (this);
-			} while (!Aborted && !WaitForCompleted (abortRetryWait) && !Manager.Disposing);
-
-			if (Manager.Disposing) {
-				InternalShutdown ();
-			}
-			else {
-				lock (this) {
-					Aborted = true;
-					if (abortState >= 6)
-						Manager.LeaveBusyState (this);
 				}
 			}
 		}
-
-		internal void InternalShutdown ()
+
+
+		public void Dispose ()
 		{
-			lock (this) {
-				if (Aborted)
-					return;
-				try {
-					Aborted = true;
-					Shutdown ();
-				} catch {
-					// Ignore
-				}
+			List<IAsyncOperationBase> copy;
+			lock (currentOperations) {
+				if (disposed) throw new ObjectDisposedException ("Already disposed");
+				disposed = true;
+				copy = currentOperations.ToList ();
+				currentOperations.Clear ();
 			}
+			// don't wait on dispose
+			CancelOperations (copy, wait: false);
 		}
-
-		/// <summary>
-		/// Message of the exception, if the execution failed. 
-		/// </summary>
-		public string ExceptionMessage { get; set; }
-
-		/// <summary>
-		/// Returns a short description of the operation, to be shown in the Debugger Busy Dialog
-		/// when it blocks the execution of the debugger. 
-		/// </summary>
-		public abstract string Description { get; }
-
-		/// <summary>
-		/// Called to invoke the operation. The execution must be asynchronous (it must return immediatelly).
-		/// </summary>
-		public abstract void Invoke ( );
-
-		/// <summary>
-		/// Called to abort the execution of the operation. It has to throw an exception
-		/// if the operation can't be aborted. This operation must not block. The engine
-		/// will wait for the operation to be aborted by calling WaitForCompleted.
-		/// </summary>
-		public abstract void Abort ();
-
-		/// <summary>
-		/// Waits until the operation has been completed or aborted.
-		/// </summary>
-		public abstract bool WaitForCompleted (int timeout);
-
-		/// <summary>
-		/// Called when the debugging session has been disposed.
-		/// I must cause any call to WaitForCompleted to exit, even if the operation
-		/// has not been completed or can't be aborted.
-		/// </summary>
-		public abstract void Shutdown ();
 	}
-}
+}

Mono.Debugging/Mono.Debugging.Evaluation/ExpressionEvaluator.cs

@@ -199,14 +199,28 @@ public virtual ValueReference GetCurrentException (EvaluationContext ctx)
 	[Serializable]
 	public class EvaluatorException: Exception
 	{
+
 		protected EvaluatorException (SerializationInfo info, StreamingContext context)
 			: base (info, context)
 		{
 		}
 
-		public EvaluatorException (string msg, params object[] args): base (string.Format (msg, args))
+		public EvaluatorException (string msg, params object[] args): base (string.Format(msg, args))
+		{
+		}
+	}
+
+	[Serializable]
+	public class EvaluatorExceptionThrownException : EvaluatorException
+	{
+		public EvaluatorExceptionThrownException (object exception, string exceptionTypeName) : base ("Exception is thrown")
 		{
+			Exception = exception;
+			ExceptionTypeName = exceptionTypeName;
 		}
+
+		public object Exception { get; private set; }
+		public string ExceptionTypeName { get; private set; }
 	}
 
 	[Serializable]

Mono.Debugging/Mono.Debugging.Evaluation/IAsyncOperation.cs

@@ -0,0 +1,22 @@
+namespace Mono.Debugging.Evaluation
+{
+	public interface IAsyncOperation
+	{
+		/// <summary>
+		/// Called to invoke the operation. The execution must be asynchronous (it must return immediatelly).
+		/// </summary>
+		void BeginInvoke ();
+
+		/// <summary>
+		/// Called to abort the execution of the operation. It has to throw an exception
+		/// if the operation can't be aborted. This operation must not block. The engine
+		/// will wait for the operation to be aborted by calling WaitForCompleted.
+		/// </summary>
+		void Abort ();
+
+		/// <summary>
+		/// Waits until the operation has been completed or aborted.
+		/// </summary>
+		bool WaitForCompleted (int timeout);
+	}
+}

Mono.Debugging/Mono.Debugging.Evaluation/ObjectValueAdaptor.cs

@@ -91,6 +91,8 @@ public ObjectValue CreateObjectValue (EvaluationContext ctx, IObjectValueSource
 				return CreateObjectValueImpl (ctx, source, path, obj, flags);
 			} catch (EvaluatorAbortedException ex) {
 				return ObjectValue.CreateFatalError (path.LastName, ex.Message, flags);
+			} catch (EvaluatorExceptionThrownException ex) {
+				return ObjectValue.CreateEvaluationException (ctx, source, path, ex);
 			} catch (EvaluatorException ex) {
 				return ObjectValue.CreateFatalError (path.LastName, ex.Message, flags);
 			} catch (Exception ex) {
@@ -588,7 +590,7 @@ public virtual ObjectValue[] GetObjectValueChildren (EvaluationContext ctx, IObj
 						values.Add (oval);
 					}
 				} catch (Exception ex) {
-					ctx.WriteDebuggerError (ex);
+					DebuggerLoggingService.LogError ("Exception in GetObjectValueChildren()", ex);
 					values.Add (ObjectValue.CreateError (null, new ObjectPath (val.Name), GetDisplayTypeName (GetTypeName (ctx, val.Type)), ex.Message, val.Flags));
 				}
 			}
@@ -1111,6 +1113,8 @@ public virtual object TargetObjectToObject (EvaluationContext ctx, object obj)
 						return new EvaluationResult ("{" + CallToString (ctx, obj) + "}");
 					} catch (TimeOutException) {
 						// ToString() timed out, fall back to default behavior.
+					} catch (EvaluatorExceptionThrownException e) {
+						// ToString() call thrown exception, fall back to default behavior.
 					}
 				}
 
@@ -1324,9 +1328,9 @@ public string EvaluateDisplayString (EvaluationContext ctx, object obj, string e
 			return display.ToString ();
 		}
 
-		public void AsyncExecute (AsyncOperation operation, int timeout)
+		public OperationResult<TValue> InvokeSync<TValue> (AsyncOperationBase<TValue> operation, int timeout)
 		{
-			asyncOperationManager.Invoke (operation, timeout);
+			return asyncOperationManager.Invoke (operation, timeout);
 		}
 
 		public ObjectValue CreateObjectValueAsync (string name, ObjectValueFlags flags, ObjectEvaluatorDelegate evaluator)
@@ -1355,10 +1359,12 @@ public ObjectValue GetExpressionValue (EvaluationContext ctx, string exp)
 				return ObjectValue.CreateImplicitNotSupported (ctx.ExpressionValueSource, new ObjectPath (exp), "", ObjectValueFlags.None);
 			} catch (NotSupportedExpressionException ex) {
 				return ObjectValue.CreateNotSupported (ctx.ExpressionValueSource, new ObjectPath (exp), "", ex.Message, ObjectValueFlags.None);
+			} catch (EvaluatorExceptionThrownException ex) {
+				return ObjectValue.CreateEvaluationException (ctx, ctx.ExpressionValueSource, new ObjectPath (exp), ex);
 			} catch (EvaluatorException ex) {
 				return ObjectValue.CreateError (ctx.ExpressionValueSource, new ObjectPath (exp), "", ex.Message, ObjectValueFlags.None);
 			} catch (Exception ex) {
-				ctx.WriteDebuggerError (ex);
+				DebuggerLoggingService.LogError ("Exception in GetExpressionValue()", ex);
 				return ObjectValue.CreateUnknown (exp);
 			}
 		}

Mono.Debugging/Mono.Debugging.Evaluation/ValueReference.cs

@@ -106,10 +106,13 @@ public ObjectValue CreateObjectValue (EvaluationOptions options)
 				return DC.ObjectValue.CreateImplicitNotSupported (this, new ObjectPath (Name), Context.Adapter.GetDisplayTypeName (GetContext (options), Type), Flags);
 			} catch (NotSupportedExpressionException ex) {
 				return DC.ObjectValue.CreateNotSupported (this, new ObjectPath (Name), Context.Adapter.GetDisplayTypeName (GetContext (options), Type), ex.Message, Flags);
+			} catch (EvaluatorExceptionThrownException ex) {
+				return DC.ObjectValue.CreateEvaluationException (Context, Context.ExpressionValueSource, new ObjectPath (Name), ex);
 			} catch (EvaluatorException ex) {
 				return DC.ObjectValue.CreateError (this, new ObjectPath (Name), "", ex.Message, Flags);
-			} catch (Exception ex) {
-				Context.WriteDebuggerError (ex);
+			}
+			catch (Exception ex) {
+				DebuggerLoggingService.LogError ("Exception in CreateObjectValue()", ex);
 				return DC.ObjectValue.CreateUnknown (Name);
 			}
 		}

Mono.Debugging/Mono.Debugging.csproj

@@ -82,10 +82,12 @@
     <Compile Include="Mono.Debugging.Evaluation\ArrayElementGroup.cs" />
     <Compile Include="Mono.Debugging.Evaluation\ArrayValueReference.cs" />
     <Compile Include="Mono.Debugging.Evaluation\AsyncEvaluationTracker.cs" />
+    <Compile Include="Mono.Debugging.Evaluation\AsyncOperationBase.cs" />
     <Compile Include="Mono.Debugging.Evaluation\AsyncOperationManager.cs" />
     <Compile Include="Mono.Debugging.Evaluation\EvaluationContext.cs" />
     <Compile Include="Mono.Debugging.Evaluation\ExpressionEvaluator.cs" />
     <Compile Include="Mono.Debugging.Evaluation\FilteredMembersSource.cs" />
+    <Compile Include="Mono.Debugging.Evaluation\IAsyncOperation.cs" />
     <Compile Include="Mono.Debugging.Evaluation\ICollectionAdaptor.cs" />
     <Compile Include="Mono.Debugging.Evaluation\LiteralValueReference.cs" />
     <Compile Include="Mono.Debugging.Evaluation\NamespaceValueReference.cs" />