finishing serverside request stream should not be required for disposal

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

@@ -80,16 +80,24 @@ namespace Grpc.Core.Internal.Tests
 
         [Test]
         public void CancelNotificationAfterStartDisposes()
+        {
+            var finishedTask = asyncCallServer.ServerSideCallAsync();
+            fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
+            AssertFinished(asyncCallServer, fakeCall, finishedTask);
+        }
+
+        [Test]
+        public void CancelNotificationAfterStartDisposesAfterPendingReadFinishes()
         {
             var finishedTask = asyncCallServer.ServerSideCallAsync();
             var requestStream = new ServerRequestStream<string, string>(asyncCallServer);
 
-            // Finishing requestStream is needed for dispose to happen.
             var moveNextTask = requestStream.MoveNext();
+
+            fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
             fakeCall.ReceivedMessageHandler(true, null);
             Assert.IsFalse(moveNextTask.Result);
 
-            fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
             AssertFinished(asyncCallServer, fakeCall, finishedTask);
         }
 
@@ -101,9 +109,8 @@ namespace Grpc.Core.Internal.Tests
 
             fakeCall.ReceivedCloseOnServerHandler(true, cancelled: true);
 
-            // Check that startin a read after cancel notification has been processed is legal.
+            // Check that starting 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);
@@ -136,12 +143,6 @@ namespace Grpc.Core.Internal.Tests
 
             // 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);
         }
 
@@ -149,7 +150,6 @@ namespace Grpc.Core.Internal.Tests
         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");
@@ -157,13 +157,7 @@ namespace Grpc.Core.Internal.Tests
             // 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);
         }
 
@@ -171,7 +165,6 @@ namespace Grpc.Core.Internal.Tests
         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");
@@ -183,11 +176,6 @@ namespace Grpc.Core.Internal.Tests
             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);

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

@@ -155,7 +155,7 @@ namespace Grpc.Core.Internal
         {
             lock (myLock)
             {
-                CheckReadingAllowed();
+                GrpcPreconditions.CheckState(started);
                 if (readingDone)
                 {
                     // the last read that returns null or throws an exception is idempotent
@@ -224,11 +224,6 @@ namespace Grpc.Core.Internal
             GrpcPreconditions.CheckState(sendCompletionDelegate == null, "Only one write can be pending at a time");
         }
 
-        protected virtual void CheckReadingAllowed()
-        {
-            GrpcPreconditions.CheckState(started);
-        }
-
         protected void CheckNotCancelled()
         {
             if (cancelRequested)

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

@@ -183,12 +183,6 @@ namespace Grpc.Core.Internal
             get { return false; }
         }
 
-        protected override void CheckReadingAllowed()
-        {
-            base.CheckReadingAllowed();
-            GrpcPreconditions.CheckArgument(!cancelRequested);
-        }
-
         protected override void OnAfterReleaseResources()
         {
             server.RemoveCallReference(this);
@@ -204,6 +198,14 @@ namespace Grpc.Core.Internal
             lock (myLock)
             {
                 finished = true;
+                if (streamingReadTcs == null)
+                {
+                    // if there's no pending read, readingDone=true will dispose now.
+                    // if there is a pending read, we will dispose once that read finishes.
+                    readingDone = true;
+                    streamingReadTcs = new TaskCompletionSource<TRequest>();
+                    streamingReadTcs.SetResult(default(TRequest));
+                }
                 ReleaseResourcesIfPossible();
             }