Merge pull request #6416 from jtattermusch/csharp_api_polishing

Add C# wrapping tests and fix some issues with the API.

src/csharp/Grpc.Core.Tests/ClientServerTest.cs

@@ -166,6 +166,37 @@ namespace Grpc.Core.Tests
             Assert.IsNotNull("xyz", call.GetTrailers()[0].Key);
         }
 
+        [Test]
+        public async Task ServerStreamingCall_EndOfStreamIsIdempotent()
+        {
+            helper.ServerStreamingHandler = new ServerStreamingServerMethod<string, string>(async (request, responseStream, context) =>
+            {
+            });
+
+            var call = Calls.AsyncServerStreamingCall(helper.CreateServerStreamingCall(), "");
+
+            Assert.IsFalse(await call.ResponseStream.MoveNext());
+            Assert.IsFalse(await call.ResponseStream.MoveNext());
+        }
+
+        [Test]
+        public async Task ServerStreamingCall_ErrorCanBeAwaitedTwice()
+        {
+            helper.ServerStreamingHandler = new ServerStreamingServerMethod<string, string>(async (request, responseStream, context) =>
+            {
+                context.Status = new Status(StatusCode.InvalidArgument, "");
+            });
+
+            var call = Calls.AsyncServerStreamingCall(helper.CreateServerStreamingCall(), "");
+
+            var ex = Assert.ThrowsAsync<RpcException>(async () => await call.ResponseStream.MoveNext());
+            Assert.AreEqual(StatusCode.InvalidArgument, ex.Status.StatusCode);
+
+            // attempting MoveNext again should result in throwing the same exception.
+            var ex2 = Assert.ThrowsAsync<RpcException>(async () => await call.ResponseStream.MoveNext());
+            Assert.AreEqual(StatusCode.InvalidArgument, ex2.Status.StatusCode);
+        }
+
         [Test]
         public async Task DuplexStreamingCall()
         {
@@ -208,6 +239,38 @@ namespace Grpc.Core.Tests
             Assert.AreEqual(StatusCode.Cancelled, ex.Status.StatusCode);
         }
 
+        [Test]
+        public async Task ClientStreamingCall_ServerSideReadAfterCancelNotificationReturnsNull()
+        {
+            var handlerStartedBarrier = new TaskCompletionSource<object>();
+            var cancelNotificationReceivedBarrier = new TaskCompletionSource<object>();
+            var successTcs = new TaskCompletionSource<string>();
+
+            helper.ClientStreamingHandler = new ClientStreamingServerMethod<string, string>(async (requestStream, context) =>
+            {
+                handlerStartedBarrier.SetResult(null);
+
+                // wait for cancellation to be delivered.
+                context.CancellationToken.Register(() => cancelNotificationReceivedBarrier.SetResult(null));
+                await cancelNotificationReceivedBarrier.Task;
+
+                var moveNextResult = await requestStream.MoveNext();
+                successTcs.SetResult(!moveNextResult ? "SUCCESS" : "FAIL");
+                return "";
+            });
+
+            var cts = new CancellationTokenSource();
+            var call = Calls.AsyncClientStreamingCall(helper.CreateClientStreamingCall(new CallOptions(cancellationToken: cts.Token)));
+
+            await handlerStartedBarrier.Task;
+            cts.Cancel();
+
+            var ex = Assert.ThrowsAsync<RpcException>(async () => await call.ResponseAsync);
+            Assert.AreEqual(StatusCode.Cancelled, ex.Status.StatusCode);
+
+            Assert.AreEqual("SUCCESS", await successTcs.Task);
+        }
+
         [Test]
         public async Task AsyncUnaryCall_EchoMetadata()
         {

src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj

@@ -84,6 +84,8 @@
     <Compile Include="SanityTest.cs" />
     <Compile Include="HalfcloseTest.cs" />
     <Compile Include="NUnitMain.cs" />
+    <Compile Include="Internal\FakeNativeCall.cs" />
+    <Compile Include="Internal\AsyncCallServerTest.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <ItemGroup>

src/csharp/Grpc.Core.Tests/Internal/AsyncCallServerTest.cs

@@ -0,0 +1,203 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Threading.Tasks;
+
+using Grpc.Core.Internal;
+using NUnit.Framework;
+
+namespace Grpc.Core.Internal.Tests
+{
+    /// <summary>
+    /// Uses fake native call to test interaction of <c>AsyncCallServer</c> wrapping code with C core in different situations.
+    /// </summary>
+    public class AsyncCallServerTest
+    {
+        Server server;
+        FakeNativeCall fakeCall;
+        AsyncCallServer<string, string> asyncCallServer;
+
+        [SetUp]
+        public void Init()
+        {
+            var environment = GrpcEnvironment.AddRef();
+
+            // Create a fake server just so we have an instance to refer to.
+            // The server won't actually be used at all.
+            server = new Server()
+            {
+                Ports = { { "localhost", 0, ServerCredentials.Insecure } }
+            };
+            server.Start();
+
+            fakeCall = new FakeNativeCall();
+            asyncCallServer = new AsyncCallServer<string, string>(
+                Marshallers.StringMarshaller.Serializer, Marshallers.StringMarshaller.Deserializer,
+                environment,
+                server);
+            asyncCallServer.InitializeForTesting(fakeCall);
+        }
+
+        [TearDown]
+        public void Cleanup()
+        {
+            server.ShutdownAsync().Wait();
+            GrpcEnvironment.Release();
+        }
+
+        [Test]
+        public void CancelNotificationAfterStartDisposes()
+        {
+            var finishedTask = asyncCallServer.ServerSideCallAsync();
+            var requestStream = new ServerRequestStream<string, string>(asyncCallServer);
+
+            // Finishing requestStream is needed for dispose to happen.
+            var moveNextTask = requestStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, null);
+            Assert.IsFalse(moveNextTask.Result);
+
+            fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
+            AssertFinished(asyncCallServer, fakeCall, finishedTask);
+        }
+
+        [Test]
+        public void ReadAfterCancelNotificationCanSucceed()
+        {
+            var finishedTask = asyncCallServer.ServerSideCallAsync();
+            var requestStream = new ServerRequestStream<string, string>(asyncCallServer);
+
+            fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
+
+            // Check that startin a read after cancel notification has been processed is legal.
+            var moveNextTask = requestStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, null);
+            Assert.IsFalse(moveNextTask.Result);
+
+            AssertFinished(asyncCallServer, fakeCall, finishedTask);
+        }
+
+        [Test]
+        public void ReadCompletionFailureClosesRequestStream()
+        {
+            var finishedTask = asyncCallServer.ServerSideCallAsync();
+            var requestStream = new ServerRequestStream<string, string>(asyncCallServer);
+
+            // if a read completion's success==false, the request stream will silently finish
+            // and we rely on C core cancelling the call.
+            var moveNextTask = requestStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(false, null);
+            Assert.IsFalse(moveNextTask.Result);
+
+            fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
+            AssertFinished(asyncCallServer, fakeCall, finishedTask);
+        }
+
+        [Test]
+        public void WriteAfterCancelNotificationFails()
+        {
+            var finishedTask = asyncCallServer.ServerSideCallAsync();
+            var requestStream = new ServerRequestStream<string, string>(asyncCallServer);
+            var responseStream = new ServerResponseStream<string, string>(asyncCallServer);
+
+            fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
+
+            // TODO(jtattermusch): should we throw a different exception type instead?
+            Assert.Throws(typeof(InvalidOperationException), () => responseStream.WriteAsync("request1"));
+
+            // Finishing requestStream is needed for dispose to happen.
+            var moveNextTask = requestStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, null);
+            Assert.IsFalse(moveNextTask.Result);
+
+            AssertFinished(asyncCallServer, fakeCall, finishedTask);
+        }
+
+        [Test]
+        public void WriteCompletionFailureThrows()
+        {
+            var finishedTask = asyncCallServer.ServerSideCallAsync();
+            var requestStream = new ServerRequestStream<string, string>(asyncCallServer);
+            var responseStream = new ServerResponseStream<string, string>(asyncCallServer);
+
+            var writeTask = responseStream.WriteAsync("request1");
+            fakeCall.SendCompletionHandler(false);
+            // TODO(jtattermusch): should we throw a different exception type instead?
+            Assert.ThrowsAsync(typeof(InvalidOperationException), async () => await writeTask);
+
+            // Finishing requestStream is needed for dispose to happen.
+            var moveNextTask = requestStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, null);
+            Assert.IsFalse(moveNextTask.Result);
+
+            fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
+
+            AssertFinished(asyncCallServer, fakeCall, finishedTask);
+        }
+
+        [Test]
+        public void WriteAndWriteStatusCanRunConcurrently()
+        {
+            var finishedTask = asyncCallServer.ServerSideCallAsync();
+            var requestStream = new ServerRequestStream<string, string>(asyncCallServer);
+            var responseStream = new ServerResponseStream<string, string>(asyncCallServer);
+
+            var writeTask = responseStream.WriteAsync("request1");
+            var writeStatusTask = asyncCallServer.SendStatusFromServerAsync(Status.DefaultSuccess, new Metadata());
+
+            fakeCall.SendCompletionHandler(true);
+            fakeCall.SendStatusFromServerHandler(true);
+
+            Assert.DoesNotThrowAsync(async () => await writeTask);
+            Assert.DoesNotThrowAsync(async () => await writeStatusTask);
+
+            // Finishing requestStream is needed for dispose to happen.
+            var moveNextTask = requestStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, null);
+            Assert.IsFalse(moveNextTask.Result);
+
+            fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
+
+            AssertFinished(asyncCallServer, fakeCall, finishedTask);
+        }
+
+        static void AssertFinished(AsyncCallServer<string, string> asyncCallServer, FakeNativeCall fakeCall, Task finishedTask)
+        {
+            Assert.IsTrue(fakeCall.IsDisposed);
+            Assert.IsTrue(finishedTask.IsCompleted);
+            Assert.DoesNotThrow(() => finishedTask.Wait());
+        }
+    }
+}

src/csharp/Grpc.Core.Tests/Internal/AsyncCallTest.cs

@@ -32,6 +32,7 @@
 #endregion
 
 using System;
+using System.Collections.Generic;
 using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 
@@ -40,6 +41,9 @@ using NUnit.Framework;
 
 namespace Grpc.Core.Internal.Tests
 {
+    /// <summary>
+    /// Uses fake native call to test interaction of <c>AsyncCall</c> wrapping code with C core in different situations.
+    /// </summary>
     public class AsyncCallTest
     {
         Channel channel;
@@ -75,8 +79,8 @@ namespace Grpc.Core.Internal.Tests
         public void AsyncUnary_StreamingOperationsNotAllowed()
         {
             asyncCall.UnaryCallAsync("request1");
-            Assert.Throws(typeof(InvalidOperationException),
-                () => asyncCall.StartReadMessage((x,y) => {}));
+            Assert.ThrowsAsync(typeof(InvalidOperationException),
+                async () => await asyncCall.ReadMessageAsync());
             Assert.Throws(typeof(InvalidOperationException),
                 () => asyncCall.StartSendMessage("abc", new WriteFlags(), (x,y) => {}));
         }
@@ -118,6 +122,14 @@ namespace Grpc.Core.Internal.Tests
             AssertUnaryResponseError(asyncCall, fakeCall, resultTask, StatusCode.Internal);
         }
 
+        [Test]
+        public void ClientStreaming_StreamingReadNotAllowed()
+        {
+            asyncCall.ClientStreamingCallAsync();
+            Assert.ThrowsAsync(typeof(InvalidOperationException),
+                async () => await asyncCall.ReadMessageAsync());
+        }
+
         [Test]
         public void ClientStreaming_NoRequest_Success()
         {
@@ -142,6 +154,283 @@ namespace Grpc.Core.Internal.Tests
             AssertUnaryResponseError(asyncCall, fakeCall, resultTask, StatusCode.InvalidArgument);
         }
 
+        [Test]
+        public void ClientStreaming_MoreRequests_Success()
+        {
+            var resultTask = asyncCall.ClientStreamingCallAsync();
+            var requestStream = new ClientRequestStream<string, string>(asyncCall);
+
+            var writeTask = requestStream.WriteAsync("request1");
+            fakeCall.SendCompletionHandler(true);
+            writeTask.Wait();
+
+            var writeTask2 = requestStream.WriteAsync("request2");
+            fakeCall.SendCompletionHandler(true);
+            writeTask2.Wait();
+
+            var completeTask = requestStream.CompleteAsync();
+            fakeCall.SendCompletionHandler(true);
+            completeTask.Wait();
+
+            fakeCall.UnaryResponseClientHandler(true,
+                new ClientSideStatus(Status.DefaultSuccess, new Metadata()),
+                CreateResponsePayload(),
+                new Metadata());
+
+            AssertUnaryResponseSuccess(asyncCall, fakeCall, resultTask);
+        }
+
+        [Test]
+        public void ClientStreaming_WriteFailure()
+        {
+            var resultTask = asyncCall.ClientStreamingCallAsync();
+            var requestStream = new ClientRequestStream<string, string>(asyncCall);
+
+            var writeTask = requestStream.WriteAsync("request1");
+            fakeCall.SendCompletionHandler(false);
+            Assert.ThrowsAsync(typeof(InvalidOperationException), async () => await writeTask);
+
+            fakeCall.UnaryResponseClientHandler(true,
+                CreateClientSideStatus(StatusCode.Internal),
+                CreateResponsePayload(),
+                new Metadata());
+
+            AssertUnaryResponseError(asyncCall, fakeCall, resultTask, StatusCode.Internal);
+        }
+
+        [Test]
+        public void ClientStreaming_WriteAfterReceivingStatusFails()
+        {
+            var resultTask = asyncCall.ClientStreamingCallAsync();
+            var requestStream = new ClientRequestStream<string, string>(asyncCall);
+
+            fakeCall.UnaryResponseClientHandler(true,
+                new ClientSideStatus(Status.DefaultSuccess, new Metadata()),
+                CreateResponsePayload(),
+                new Metadata());
+
+            AssertUnaryResponseSuccess(asyncCall, fakeCall, resultTask);
+            Assert.Throws(typeof(InvalidOperationException), () => requestStream.WriteAsync("request1"));
+        }
+
+        [Test]
+        public void ClientStreaming_CompleteAfterReceivingStatusSucceeds()
+        {
+            var resultTask = asyncCall.ClientStreamingCallAsync();
+            var requestStream = new ClientRequestStream<string, string>(asyncCall);
+
+            fakeCall.UnaryResponseClientHandler(true,
+                new ClientSideStatus(Status.DefaultSuccess, new Metadata()),
+                CreateResponsePayload(),
+                new Metadata());
+
+            AssertUnaryResponseSuccess(asyncCall, fakeCall, resultTask);
+            Assert.DoesNotThrowAsync(async () => await requestStream.CompleteAsync());
+        }
+
+        [Test]
+        public void ClientStreaming_WriteAfterCancellationRequestFails()
+        {
+            var resultTask = asyncCall.ClientStreamingCallAsync();
+            var requestStream = new ClientRequestStream<string, string>(asyncCall);
+
+            asyncCall.Cancel();
+            Assert.IsTrue(fakeCall.IsCancelled);
+
+            Assert.Throws(typeof(OperationCanceledException), () => requestStream.WriteAsync("request1"));
+
+            fakeCall.UnaryResponseClientHandler(true,
+                CreateClientSideStatus(StatusCode.Cancelled),
+                CreateResponsePayload(),
+                new Metadata());
+
+            AssertUnaryResponseError(asyncCall, fakeCall, resultTask, StatusCode.Cancelled);
+        }
+
+        [Test]
+        public void ServerStreaming_StreamingSendNotAllowed()
+        {
+            asyncCall.StartServerStreamingCall("request1");
+            Assert.Throws(typeof(InvalidOperationException),
+                () => asyncCall.StartSendMessage("abc", new WriteFlags(), (x,y) => {}));
+        }
+
+        [Test]
+        public void ServerStreaming_NoResponse_Success1()
+        {
+            asyncCall.StartServerStreamingCall("request1");
+            var responseStream = new ClientResponseStream<string, string>(asyncCall);
+            var readTask = responseStream.MoveNext();
+
+            fakeCall.ReceivedResponseHeadersHandler(true, new Metadata());
+            Assert.AreEqual(0, asyncCall.ResponseHeadersAsync.Result.Count);
+
+            fakeCall.ReceivedMessageHandler(true, null);
+            fakeCall.ReceivedStatusOnClientHandler(true, new ClientSideStatus(Status.DefaultSuccess, new Metadata()));
+
+            AssertStreamingResponseSuccess(asyncCall, fakeCall, readTask);
+        }
+
+        [Test]
+        public void ServerStreaming_NoResponse_Success2()
+        {
+            asyncCall.StartServerStreamingCall("request1");
+            var responseStream = new ClientResponseStream<string, string>(asyncCall);
+            var readTask = responseStream.MoveNext();
+
+            // try alternative order of completions
+            fakeCall.ReceivedStatusOnClientHandler(true, new ClientSideStatus(Status.DefaultSuccess, new Metadata()));
+            fakeCall.ReceivedMessageHandler(true, null);
+
+            AssertStreamingResponseSuccess(asyncCall, fakeCall, readTask);
+        }
+
+        [Test]
+        public void ServerStreaming_NoResponse_ReadFailure()
+        {
+            asyncCall.StartServerStreamingCall("request1");
+            var responseStream = new ClientResponseStream<string, string>(asyncCall);
+            var readTask = responseStream.MoveNext();
+
+            fakeCall.ReceivedMessageHandler(false, null);  // after a failed read, we rely on C core to deliver appropriate status code.
+            fakeCall.ReceivedStatusOnClientHandler(true, CreateClientSideStatus(StatusCode.Internal));
+
+            AssertStreamingResponseError(asyncCall, fakeCall, readTask, StatusCode.Internal);
+        }
+
+        [Test]
+        public void ServerStreaming_MoreResponses_Success()
+        {
+            asyncCall.StartServerStreamingCall("request1");
+            var responseStream = new ClientResponseStream<string, string>(asyncCall);
+
+            var readTask1 = responseStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, CreateResponsePayload());
+            Assert.IsTrue(readTask1.Result);
+            Assert.AreEqual("response1", responseStream.Current);
+
+            var readTask2 = responseStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, CreateResponsePayload());
+            Assert.IsTrue(readTask2.Result);
+            Assert.AreEqual("response1", responseStream.Current);
+
+            var readTask3 = responseStream.MoveNext();
+            fakeCall.ReceivedStatusOnClientHandler(true, new ClientSideStatus(Status.DefaultSuccess, new Metadata()));
+            fakeCall.ReceivedMessageHandler(true, null);
+
+            AssertStreamingResponseSuccess(asyncCall, fakeCall, readTask3);
+        }
+
+        [Test]
+        public void DuplexStreaming_NoRequestNoResponse_Success()
+        {
+            asyncCall.StartDuplexStreamingCall();
+            var requestStream = new ClientRequestStream<string, string>(asyncCall);
+            var responseStream = new ClientResponseStream<string, string>(asyncCall);
+
+            var writeTask1 = requestStream.CompleteAsync();
+            fakeCall.SendCompletionHandler(true);
+            Assert.DoesNotThrowAsync(async () => await writeTask1);
+
+            var readTask = responseStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, null);
+            fakeCall.ReceivedStatusOnClientHandler(true, new ClientSideStatus(Status.DefaultSuccess, new Metadata()));
+
+            AssertStreamingResponseSuccess(asyncCall, fakeCall, readTask);
+        }
+
+        [Test]
+        public void DuplexStreaming_WriteAfterReceivingStatusFails()
+        {
+            asyncCall.StartDuplexStreamingCall();
+            var requestStream = new ClientRequestStream<string, string>(asyncCall);
+            var responseStream = new ClientResponseStream<string, string>(asyncCall);
+
+            var readTask = responseStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, null);
+            fakeCall.ReceivedStatusOnClientHandler(true, new ClientSideStatus(Status.DefaultSuccess, new Metadata()));
+
+            AssertStreamingResponseSuccess(asyncCall, fakeCall, readTask);
+
+            Assert.ThrowsAsync(typeof(InvalidOperationException), async () => await requestStream.WriteAsync("request1"));
+        }
+
+        [Test]
+        public void DuplexStreaming_CompleteAfterReceivingStatusFails()
+        {
+            asyncCall.StartDuplexStreamingCall();
+            var requestStream = new ClientRequestStream<string, string>(asyncCall);
+            var responseStream = new ClientResponseStream<string, string>(asyncCall);
+
+            var readTask = responseStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, null);
+            fakeCall.ReceivedStatusOnClientHandler(true, new ClientSideStatus(Status.DefaultSuccess, new Metadata()));
+
+            AssertStreamingResponseSuccess(asyncCall, fakeCall, readTask);
+
+            Assert.DoesNotThrowAsync(async () => await requestStream.CompleteAsync());
+        }
+
+        [Test]
+        public void DuplexStreaming_WriteAfterCancellationRequestFails()
+        {
+            asyncCall.StartDuplexStreamingCall();
+            var requestStream = new ClientRequestStream<string, string>(asyncCall);
+            var responseStream = new ClientResponseStream<string, string>(asyncCall);
+
+            asyncCall.Cancel();
+            Assert.IsTrue(fakeCall.IsCancelled);
+            Assert.Throws(typeof(OperationCanceledException), () => requestStream.WriteAsync("request1"));
+
+            var readTask = responseStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, null);
+            fakeCall.ReceivedStatusOnClientHandler(true, CreateClientSideStatus(StatusCode.Cancelled));
+
+            AssertStreamingResponseError(asyncCall, fakeCall, readTask, StatusCode.Cancelled);
+        }
+
+        [Test]
+        public void DuplexStreaming_ReadAfterCancellationRequestCanSucceed()
+        {
+            asyncCall.StartDuplexStreamingCall();
+            var responseStream = new ClientResponseStream<string, string>(asyncCall);
+
+            asyncCall.Cancel();
+            Assert.IsTrue(fakeCall.IsCancelled);
+
+            var readTask1 = responseStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, CreateResponsePayload());
+            Assert.IsTrue(readTask1.Result);
+            Assert.AreEqual("response1", responseStream.Current);
+
+            var readTask2 = responseStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, null);
+            fakeCall.ReceivedStatusOnClientHandler(true, CreateClientSideStatus(StatusCode.Cancelled));
+
+            AssertStreamingResponseError(asyncCall, fakeCall, readTask2, StatusCode.Cancelled);
+        }
+
+        [Test]
+        public void DuplexStreaming_ReadStartedBeforeCancellationRequestCanSucceed()
+        {
+            asyncCall.StartDuplexStreamingCall();
+            var responseStream = new ClientResponseStream<string, string>(asyncCall);
+
+            var readTask1 = responseStream.MoveNext();  // initiate the read before cancel request
+            asyncCall.Cancel();
+            Assert.IsTrue(fakeCall.IsCancelled);
+
+            fakeCall.ReceivedMessageHandler(true, CreateResponsePayload());
+            Assert.IsTrue(readTask1.Result);
+            Assert.AreEqual("response1", responseStream.Current);
+
+            var readTask2 = responseStream.MoveNext();
+            fakeCall.ReceivedMessageHandler(true, null);
+            fakeCall.ReceivedStatusOnClientHandler(true, CreateClientSideStatus(StatusCode.Cancelled));
+
+            AssertStreamingResponseError(asyncCall, fakeCall, readTask2, StatusCode.Cancelled);
+        }
+
         ClientSideStatus CreateClientSideStatus(StatusCode statusCode)
         {
             return new ClientSideStatus(new Status(statusCode, ""), new Metadata());
@@ -163,6 +452,16 @@ namespace Grpc.Core.Internal.Tests
             Assert.AreEqual("response1", resultTask.Result);
         }
 
+        static void AssertStreamingResponseSuccess(AsyncCall<string, string> asyncCall, FakeNativeCall fakeCall, Task<bool> moveNextTask)
+        {
+            Assert.IsTrue(moveNextTask.IsCompleted);
+            Assert.IsTrue(fakeCall.IsDisposed);
+
+            Assert.IsFalse(moveNextTask.Result);
+            Assert.AreEqual(Status.DefaultSuccess, asyncCall.GetStatus());
+            Assert.AreEqual(0, asyncCall.GetTrailers().Count);
+        }
+
         static void AssertUnaryResponseError(AsyncCall<string, string> asyncCall, FakeNativeCall fakeCall, Task<string> resultTask, StatusCode expectedStatusCode)
         {
             Assert.IsTrue(resultTask.IsCompleted);
@@ -175,135 +474,15 @@ namespace Grpc.Core.Internal.Tests
             Assert.AreEqual(0, asyncCall.GetTrailers().Count);
         }
 
-        internal class FakeNativeCall : INativeCall
-        {
-            public UnaryResponseClientHandler UnaryResponseClientHandler
-            {
-                get;
-                set;
-            }
-
-            public ReceivedStatusOnClientHandler ReceivedStatusOnClientHandler
-            {
-                get;
-                set;
-            }
-
-            public ReceivedMessageHandler ReceivedMessageHandler
-            {
-                get;
-                set;
-            }
-
-            public ReceivedResponseHeadersHandler ReceivedResponseHeadersHandler
-            {
-                get;
-                set;
-            }
-
-            public SendCompletionHandler SendCompletionHandler
-            {
-                get;
-                set;
-            }
-
-            public ReceivedCloseOnServerHandler ReceivedCloseOnServerHandler
-            {
-                get;
-                set;
-            }
-
-            public bool IsCancelled
-            {
-                get;
-                set;
-            }
-
-            public bool IsDisposed
-            {
-                get;
-                set;
-            }
-
-            public void Cancel()
-            {
-                IsCancelled = true;
-            }
-
-            public void CancelWithStatus(Status status)
-            {
-                IsCancelled = true;
-            }
-
-            public string GetPeer()
-            {
-                return "PEER";
-            }
-
-            public void StartUnary(UnaryResponseClientHandler callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
-            {
-                UnaryResponseClientHandler = callback;
-            }
-
-            public void StartUnary(BatchContextSafeHandle ctx, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
-            {
-                throw new NotImplementedException();
-            }
-
-            public void StartClientStreaming(UnaryResponseClientHandler callback, MetadataArraySafeHandle metadataArray)
-            {
-                UnaryResponseClientHandler = callback;
-            }
-
-            public void StartServerStreaming(ReceivedStatusOnClientHandler callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
-            {
-                ReceivedStatusOnClientHandler = callback;
-            }
-
-            public void StartDuplexStreaming(ReceivedStatusOnClientHandler callback, MetadataArraySafeHandle metadataArray)
-            {
-                ReceivedStatusOnClientHandler = callback;
-            }
-
-            public void StartReceiveMessage(ReceivedMessageHandler callback)
-            {
-                ReceivedMessageHandler = callback;
-            }
-
-            public void StartReceiveInitialMetadata(ReceivedResponseHeadersHandler callback)
-            {
-                ReceivedResponseHeadersHandler = callback;
-            }
-
-            public void StartSendInitialMetadata(SendCompletionHandler callback, MetadataArraySafeHandle metadataArray)
-            {
-                SendCompletionHandler = callback;
-            }
-
-            public void StartSendMessage(SendCompletionHandler callback, byte[] payload, WriteFlags writeFlags, bool sendEmptyInitialMetadata)
-            {
-                SendCompletionHandler = callback;
-            }
-
-            public void StartSendCloseFromClient(SendCompletionHandler callback)
-            {
-                SendCompletionHandler = callback;
-            }
-
-            public void StartSendStatusFromServer(SendCompletionHandler callback, Status status, MetadataArraySafeHandle metadataArray, bool sendEmptyInitialMetadata)
-            {
-                SendCompletionHandler = callback;
-            }
-
-            public void StartServerSide(ReceivedCloseOnServerHandler callback)
-            {
-                ReceivedCloseOnServerHandler = callback;
-            }
-
-            public void Dispose()
-            {
-                IsDisposed = true;
-            }
+        static void AssertStreamingResponseError(AsyncCall<string, string> asyncCall, FakeNativeCall fakeCall, Task<bool> moveNextTask, StatusCode expectedStatusCode)
+        {
+            Assert.IsTrue(moveNextTask.IsCompleted);
+            Assert.IsTrue(fakeCall.IsDisposed);
+
+            var ex = Assert.ThrowsAsync<RpcException>(async () => await moveNextTask);
+            Assert.AreEqual(expectedStatusCode, ex.Status.StatusCode);
+            Assert.AreEqual(expectedStatusCode, asyncCall.GetStatus().StatusCode);
+            Assert.AreEqual(0, asyncCall.GetTrailers().Count);
         }
     }
 }

src/csharp/Grpc.Core.Tests/Internal/FakeNativeCall.cs

@@ -0,0 +1,183 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Runtime.InteropServices;
+using System.Threading.Tasks;
+
+using Grpc.Core.Internal;
+using NUnit.Framework;
+
+namespace Grpc.Core.Internal.Tests
+{
+    /// <summary>
+    /// For testing purposes.
+    /// </summary>
+    internal class FakeNativeCall : INativeCall
+    {
+        public UnaryResponseClientHandler UnaryResponseClientHandler
+        {
+            get;
+            set;
+        }
+
+        public ReceivedStatusOnClientHandler ReceivedStatusOnClientHandler
+        {
+            get;
+            set;
+        }
+
+        public ReceivedMessageHandler ReceivedMessageHandler
+        {
+            get;
+            set;
+        }
+
+        public ReceivedResponseHeadersHandler ReceivedResponseHeadersHandler
+        {
+            get;
+            set;
+        }
+
+        public SendCompletionHandler SendCompletionHandler
+        {
+            get;
+            set;
+        }
+
+        public SendCompletionHandler SendStatusFromServerHandler
+        {
+            get;
+            set;
+        }
+
+        public ReceivedCloseOnServerHandler ReceivedCloseOnServerHandler
+        {
+            get;
+            set;
+        }
+
+        public bool IsCancelled
+        {
+            get;
+            set;
+        }
+
+        public bool IsDisposed
+        {
+            get;
+            set;
+        }
+
+        public void Cancel()
+        {
+            IsCancelled = true;
+        }
+
+        public void CancelWithStatus(Status status)
+        {
+            IsCancelled = true;
+        }
+
+        public string GetPeer()
+        {
+            return "PEER";
+        }
+
+        public void StartUnary(UnaryResponseClientHandler callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
+        {
+            UnaryResponseClientHandler = callback;
+        }
+
+        public void StartUnary(BatchContextSafeHandle ctx, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
+        {
+            throw new NotImplementedException();
+        }
+
+        public void StartClientStreaming(UnaryResponseClientHandler callback, MetadataArraySafeHandle metadataArray)
+        {
+            UnaryResponseClientHandler = callback;
+        }
+
+        public void StartServerStreaming(ReceivedStatusOnClientHandler callback, byte[] payload, MetadataArraySafeHandle metadataArray, WriteFlags writeFlags)
+        {
+            ReceivedStatusOnClientHandler = callback;
+        }
+
+        public void StartDuplexStreaming(ReceivedStatusOnClientHandler callback, MetadataArraySafeHandle metadataArray)
+        {
+            ReceivedStatusOnClientHandler = callback;
+        }
+
+        public void StartReceiveMessage(ReceivedMessageHandler callback)
+        {
+            ReceivedMessageHandler = callback;
+        }
+
+        public void StartReceiveInitialMetadata(ReceivedResponseHeadersHandler callback)
+        {
+            ReceivedResponseHeadersHandler = callback;
+        }
+
+        public void StartSendInitialMetadata(SendCompletionHandler callback, MetadataArraySafeHandle metadataArray)
+        {
+            SendCompletionHandler = callback;
+        }
+
+        public void StartSendMessage(SendCompletionHandler callback, byte[] payload, WriteFlags writeFlags, bool sendEmptyInitialMetadata)
+        {
+            SendCompletionHandler = callback;
+        }
+
+        public void StartSendCloseFromClient(SendCompletionHandler callback)
+        {
+            SendCompletionHandler = callback;
+        }
+
+        public void StartSendStatusFromServer(SendCompletionHandler callback, Status status, MetadataArraySafeHandle metadataArray, bool sendEmptyInitialMetadata)
+        {
+            SendStatusFromServerHandler = callback;
+        }
+
+        public void StartServerSide(ReceivedCloseOnServerHandler callback)
+        {
+            ReceivedCloseOnServerHandler = callback;
+        }
+
+        public void Dispose()
+        {
+            IsDisposed = true;
+        }
+    }
+}

src/csharp/Grpc.Core/Internal/AsyncCall.cs

@@ -241,11 +241,10 @@ namespace Grpc.Core.Internal
 
         /// <summary>
         /// Receives a streaming response. Only one pending read action is allowed at any given time.
-        /// completionDelegate is called when the operation finishes.
         /// </summary>
-        public void StartReadMessage(AsyncCompletionDelegate<TResponse> completionDelegate)
+        public Task<TResponse> ReadMessageAsync()
         {
-            StartReadMessageInternal(completionDelegate);
+            return ReadMessageInternalAsync();
         }
 
         /// <summary>

src/csharp/Grpc.Core/Internal/AsyncCallBase.cs

@@ -68,7 +68,8 @@ namespace Grpc.Core.Internal
         protected bool cancelRequested;
 
         protected AsyncCompletionDelegate<object> sendCompletionDelegate;  // Completion of a pending send or sendclose if not null.
-        protected AsyncCompletionDelegate<TRead> readCompletionDelegate;  // Completion of a pending send or sendclose if not null.
+        protected TaskCompletionSource<TRead> streamingReadTcs;  // Completion of a pending streaming read if not null.
+        protected TaskCompletionSource<object> sendStatusFromServerTcs;
 
         protected bool readingDone;  // True if last read (i.e. read with null payload) was already received.
         protected bool halfcloseRequested;  // True if send close have been initiated.
@@ -150,15 +151,25 @@ namespace Grpc.Core.Internal
         /// Initiates reading a message. Only one read operation can be active at a time.
         /// completionDelegate is invoked upon completion.
         /// </summary>
-        protected void StartReadMessageInternal(AsyncCompletionDelegate<TRead> completionDelegate)
+        protected Task<TRead> ReadMessageInternalAsync()
         {
             lock (myLock)
             {
-                GrpcPreconditions.CheckNotNull(completionDelegate, "Completion delegate cannot be null");
                 CheckReadingAllowed();
+                if (readingDone)
+                {
+                    // the last read that returns null or throws an exception is idempotent
+                    // and maintain its state.
+                    GrpcPreconditions.CheckState(streamingReadTcs != null, "Call does not support streaming reads.");
+                    return streamingReadTcs.Task;
+                }
+
+                GrpcPreconditions.CheckState(streamingReadTcs == null, "Only one read can be pending at a time");
+                GrpcPreconditions.CheckState(!disposed);
 
                 call.StartReceiveMessage(HandleReadFinished);
-                readCompletionDelegate = completionDelegate;
+                streamingReadTcs = new TaskCompletionSource<TRead>();
+                return streamingReadTcs.Task;
             }
         }
 
@@ -216,10 +227,6 @@ namespace Grpc.Core.Internal
         protected virtual void CheckReadingAllowed()
         {
             GrpcPreconditions.CheckState(started);
-            GrpcPreconditions.CheckState(!disposed);
-
-            GrpcPreconditions.CheckState(!readingDone, "Stream has already been closed.");
-            GrpcPreconditions.CheckState(readCompletionDelegate == null, "Only one read can be pending at a time");
         }
 
         protected void CheckNotCancelled()
@@ -322,22 +329,18 @@ namespace Grpc.Core.Internal
         /// </summary>
         protected void HandleSendStatusFromServerFinished(bool success)
         {
-            AsyncCompletionDelegate<object> origCompletionDelegate = null;
             lock (myLock)
             {
-                origCompletionDelegate = sendCompletionDelegate;
-                sendCompletionDelegate = null;
-
                 ReleaseResourcesIfPossible();
             }
 
             if (!success)
             {
-                FireCompletion(origCompletionDelegate, null, new InvalidOperationException("Error sending status from server."));
+                sendStatusFromServerTcs.SetException(new InvalidOperationException("Error sending status from server."));
             }
             else
             {
-                FireCompletion(origCompletionDelegate, null, null);
+                sendStatusFromServerTcs.SetResult(null);
             }
         }
 
@@ -346,15 +349,17 @@ namespace Grpc.Core.Internal
         /// </summary>
         protected void HandleReadFinished(bool success, byte[] receivedMessage)
         {
+            // if success == false, received message will be null. It that case we will
+            // treat this completion as the last read an rely on C core to handle the failed
+            // read (e.g. deliver approriate statusCode on the clientside).
+
             TRead msg = default(TRead);
             var deserializeException = (success && receivedMessage != null) ? TryDeserialize(receivedMessage, out msg) : null;
 
-            AsyncCompletionDelegate<TRead> origCompletionDelegate = null;
+            TaskCompletionSource<TRead> origTcs = null;
             lock (myLock)
             {
-                origCompletionDelegate = readCompletionDelegate;
-                readCompletionDelegate = null;
-
+                origTcs = streamingReadTcs;
                 if (receivedMessage == null)
                 {
                     // This was the last read.
@@ -364,20 +369,25 @@ namespace Grpc.Core.Internal
                 if (deserializeException != null && IsClient)
                 {
                     readingDone = true;
+
+                    // TODO(jtattermusch): it might be too late to set the status
                     CancelWithStatus(DeserializeResponseFailureStatus);
                 }
 
+                if (!readingDone)
+                {
+                    streamingReadTcs = null;
+                }
+
                 ReleaseResourcesIfPossible();
             }
 
-            // TODO: handle the case when success==false
-
             if (deserializeException != null && !IsClient)
             {
-                FireCompletion(origCompletionDelegate, default(TRead), new IOException("Failed to deserialize request message.", deserializeException));
+                origTcs.SetException(new IOException("Failed to deserialize request message.", deserializeException));
                 return;
             }
-            FireCompletion(origCompletionDelegate, msg, null);
+            origTcs.SetResult(msg);
         }
     }
 }

src/csharp/Grpc.Core/Internal/AsyncCallServer.cs

@@ -64,6 +64,15 @@ namespace Grpc.Core.Internal
             InitializeInternal(call);
         }
 
+        /// <summary>
+        /// Only for testing purposes.
+        /// </summary>
+        public void InitializeForTesting(INativeCall call)
+        {
+            server.AddCallReference(this);
+            InitializeInternal(call);
+        }
+
         /// <summary>
         /// Starts a server side call.
         /// </summary>
@@ -91,11 +100,10 @@ namespace Grpc.Core.Internal
 
         /// <summary>
         /// Receives a streaming request. Only one pending read action is allowed at any given time.
-        /// completionDelegate is called when the operation finishes.
         /// </summary>
-        public void StartReadMessage(AsyncCompletionDelegate<TRequest> completionDelegate)
+        public Task<TRequest> ReadMessageAsync()
         {
-            StartReadMessageInternal(completionDelegate);
+            return ReadMessageInternalAsync();
         }
 
         /// <summary>
@@ -128,24 +136,25 @@ namespace Grpc.Core.Internal
         }
 
         /// <summary>
-        /// Sends call result status, also indicating server is done with streaming responses.
-        /// Only one pending send action is allowed at any given time.
-        /// completionDelegate is called when the operation finishes.
+        /// Sends call result status, indicating we are done with writes.
+        /// Sending a status different from StatusCode.OK will also implicitly cancel the call.
         /// </summary>
-        public void StartSendStatusFromServer(Status status, Metadata trailers, AsyncCompletionDelegate<object> completionDelegate)
+        public Task SendStatusFromServerAsync(Status status, Metadata trailers)
         {
             lock (myLock)
             {
-                GrpcPreconditions.CheckNotNull(completionDelegate, "Completion delegate cannot be null");
-                CheckSendingAllowed(allowFinished: false);
+                GrpcPreconditions.CheckState(started);
+                GrpcPreconditions.CheckState(!disposed);
+                GrpcPreconditions.CheckState(!halfcloseRequested, "Can only send status from server once.");
 
                 using (var metadataArray = MetadataArraySafeHandle.Create(trailers))
                 {
                     call.StartSendStatusFromServer(HandleSendStatusFromServerFinished, status, metadataArray, !initialMetadataSent);
                 }
                 halfcloseRequested = true;
-                readingDone = true;
-                sendCompletionDelegate = completionDelegate;
+                initialMetadataSent = true;
+                sendStatusFromServerTcs = new TaskCompletionSource<object>();
+                return sendStatusFromServerTcs.Task;
             }
         }
 
@@ -190,12 +199,13 @@ namespace Grpc.Core.Internal
         /// </summary>
         private void HandleFinishedServerside(bool success, bool cancelled)
         {
+            // NOTE: because this event is a result of batch containing GRPC_OP_RECV_CLOSE_ON_SERVER,
+            // success will be always set to true.
             lock (myLock)
             {
                 finished = true;
                 ReleaseResourcesIfPossible();
             }
-            // TODO(jtattermusch): handle error
 
             if (cancelled)
             {

src/csharp/Grpc.Core/Internal/ClientResponseStream.cs

@@ -68,9 +68,7 @@ namespace Grpc.Core.Internal
             {
                 throw new InvalidOperationException("Cancellation of individual reads is not supported.");
             }
-            var taskSource = new AsyncCompletionTaskSource<TResponse>();
-            call.StartReadMessage(taskSource.CompletionDelegate);
-            var result = await taskSource.Task.ConfigureAwait(false);
+            var result = await call.ReadMessageAsync().ConfigureAwait(false);
             this.current = result;
 
             if (result == null)

src/csharp/Grpc.Core/Internal/ServerCallHandler.cs

@@ -93,7 +93,7 @@ namespace Grpc.Core.Internal
             }
             try
             {
-                await responseStream.WriteStatusAsync(status, context.ResponseTrailers).ConfigureAwait(false);
+                await asyncCall.SendStatusFromServerAsync(status, context.ResponseTrailers).ConfigureAwait(false);
             }
             catch (OperationCanceledException)
             {
@@ -149,7 +149,7 @@ namespace Grpc.Core.Internal
 
             try
             {
-                await responseStream.WriteStatusAsync(status, context.ResponseTrailers).ConfigureAwait(false);
+                await asyncCall.SendStatusFromServerAsync(status, context.ResponseTrailers).ConfigureAwait(false);
             }
             catch (OperationCanceledException)
             {
@@ -209,7 +209,7 @@ namespace Grpc.Core.Internal
 
             try
             {
-                await responseStream.WriteStatusAsync(status, context.ResponseTrailers).ConfigureAwait(false);
+                await asyncCall.SendStatusFromServerAsync(status, context.ResponseTrailers).ConfigureAwait(false);
             }
             catch (OperationCanceledException)
             {
@@ -260,7 +260,7 @@ namespace Grpc.Core.Internal
             }
             try
             {
-                await responseStream.WriteStatusAsync(status, context.ResponseTrailers).ConfigureAwait(false);
+                await asyncCall.SendStatusFromServerAsync(status, context.ResponseTrailers).ConfigureAwait(false);
             }
             catch (OperationCanceledException)
             {
@@ -282,9 +282,7 @@ namespace Grpc.Core.Internal
             
             asyncCall.Initialize(newRpc.Call);
             var finishedTask = asyncCall.ServerSideCallAsync();
-            var responseStream = new ServerResponseStream<byte[], byte[]>(asyncCall);
-
-            await responseStream.WriteStatusAsync(new Status(StatusCode.Unimplemented, ""), Metadata.Empty).ConfigureAwait(false);
+            await asyncCall.SendStatusFromServerAsync(new Status(StatusCode.Unimplemented, ""), Metadata.Empty).ConfigureAwait(false);
             await finishedTask.ConfigureAwait(false);
         }
     }

src/csharp/Grpc.Core/Internal/ServerRequestStream.cs

@@ -68,9 +68,7 @@ namespace Grpc.Core.Internal
             {
                 throw new InvalidOperationException("Cancellation of individual reads is not supported.");
             }
-            var taskSource = new AsyncCompletionTaskSource<TRequest>();
-            call.StartReadMessage(taskSource.CompletionDelegate);
-            var result = await taskSource.Task.ConfigureAwait(false);
+            var result = await call.ReadMessageAsync().ConfigureAwait(false);
             this.current = result;
             return result != null;
         }

src/csharp/Grpc.Core/Internal/ServerResponseStream.cs

@@ -57,13 +57,6 @@ namespace Grpc.Core.Internal
             return taskSource.Task;
         }
 
-        public Task WriteStatusAsync(Status status, Metadata trailers)
-        {
-            var taskSource = new AsyncCompletionTaskSource<object>();
-            call.StartSendStatusFromServer(status, trailers, taskSource.CompletionDelegate);
-            return taskSource.Task;
-        }
-
         public Task WriteResponseHeadersAsync(Metadata responseHeaders)
         {
             var taskSource = new AsyncCompletionTaskSource<object>();

src/csharp/tests.json

@@ -1,5 +1,6 @@
 {
   "Grpc.Core.Tests": [
+    "Grpc.Core.Internal.Tests.AsyncCallServerTest",
     "Grpc.Core.Internal.Tests.AsyncCallTest",
     "Grpc.Core.Internal.Tests.ChannelArgsSafeHandleTest",
     "Grpc.Core.Internal.Tests.CompletionQueueEventTest",