switch C# to contextual serializer and deserializer internally

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

@@ -49,7 +49,7 @@ namespace Grpc.Core.Internal.Tests
 
             fakeCall = new FakeNativeCall();
             asyncCallServer = new AsyncCallServer<string, string>(
-                Marshallers.StringMarshaller.Serializer, Marshallers.StringMarshaller.Deserializer,
+                Marshallers.StringMarshaller.ContextualSerializer, Marshallers.StringMarshaller.ContextualDeserializer,
                 server);
             asyncCallServer.InitializeForTesting(fakeCall);
         }

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

@@ -69,11 +69,8 @@ namespace Grpc.Core.Tests
 
             Assert.AreSame(contextualSerializer, marshaller.ContextualSerializer);
             Assert.AreSame(contextualDeserializer, marshaller.ContextualDeserializer);
-
-            // test that emulated serializer and deserializer work
-            var origMsg = "abc";
-            var serialized = marshaller.Serializer(origMsg);
-            Assert.AreEqual(origMsg, marshaller.Deserializer(serialized));
+            Assert.Throws(typeof(NotImplementedException), () => marshaller.Serializer("abc"));
+            Assert.Throws(typeof(NotImplementedException), () => marshaller.Deserializer(new byte[] {1, 2, 3}));
         }
 
         class FakeSerializationContext : SerializationContext

src/csharp/Grpc.Core/DeserializationContext.cs

@@ -16,6 +16,8 @@
 
 #endregion
 
+using System;
+
 namespace Grpc.Core
 {
     /// <summary>
@@ -41,6 +43,9 @@ namespace Grpc.Core
         /// (as there is no practical reason for doing so) and <c>DeserializationContext</c> implementations are free to assume so.
         /// </summary>
         /// <returns>byte array containing the entire payload.</returns>
-        public abstract byte[] PayloadAsNewBuffer();
+        public virtual byte[] PayloadAsNewBuffer()
+        {
+            throw new NotImplementedException();
+        }
     }
 }

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

@@ -54,7 +54,7 @@ namespace Grpc.Core.Internal
         ClientSideStatus? finishedStatus;
 
         public AsyncCall(CallInvocationDetails<TRequest, TResponse> callDetails)
-            : base(callDetails.RequestMarshaller.Serializer, callDetails.ResponseMarshaller.Deserializer)
+            : base(callDetails.RequestMarshaller.ContextualSerializer, callDetails.ResponseMarshaller.ContextualDeserializer)
         {
             this.details = callDetails.WithOptions(callDetails.Options.Normalize());
             this.initialMetadataSent = true;  // we always send metadata at the very beginning of the call.

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

@@ -40,8 +40,8 @@ namespace Grpc.Core.Internal
         static readonly ILogger Logger = GrpcEnvironment.Logger.ForType<AsyncCallBase<TWrite, TRead>>();
         protected static readonly Status DeserializeResponseFailureStatus = new Status(StatusCode.Internal, "Failed to deserialize response message.");
 
-        readonly Func<TWrite, byte[]> serializer;
-        readonly Func<byte[], TRead> deserializer;
+        readonly Action<TWrite, SerializationContext> serializer;
+        readonly Func<DeserializationContext, TRead> deserializer;
 
         protected readonly object myLock = new object();
 
@@ -63,7 +63,7 @@ namespace Grpc.Core.Internal
         protected bool initialMetadataSent;
         protected long streamingWritesCounter;  // Number of streaming send operations started so far.
 
-        public AsyncCallBase(Func<TWrite, byte[]> serializer, Func<byte[], TRead> deserializer)
+        public AsyncCallBase(Action<TWrite, SerializationContext> serializer, Func<DeserializationContext, TRead> deserializer)
         {
             this.serializer = GrpcPreconditions.CheckNotNull(serializer);
             this.deserializer = GrpcPreconditions.CheckNotNull(deserializer);
@@ -215,14 +215,26 @@ namespace Grpc.Core.Internal
 
         protected byte[] UnsafeSerialize(TWrite msg)
         {
-            return serializer(msg);
+            DefaultSerializationContext context = null;
+            try
+            {
+                context = DefaultSerializationContext.GetInitializedThreadLocal();
+                serializer(msg, context);
+                return context.GetPayload();
+            }
+            finally
+            {
+                context?.Reset();
+            }
         }
 
         protected Exception TryDeserialize(byte[] payload, out TRead msg)
         {
+            DefaultDeserializationContext context = null;
             try
             {
-                msg = deserializer(payload);
+                context = DefaultDeserializationContext.GetInitializedThreadLocal(payload);
+                msg = deserializer(context);
                 return null;
             }
             catch (Exception e)
@@ -230,6 +242,11 @@ namespace Grpc.Core.Internal
                 msg = default(TRead);
                 return e;
             }
+            finally
+            {
+                context?.Reset();
+
+            }
         }
 
         /// <summary>

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

@@ -37,7 +37,7 @@ namespace Grpc.Core.Internal
         readonly CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
         readonly Server server;
 
-        public AsyncCallServer(Func<TResponse, byte[]> serializer, Func<byte[], TRequest> deserializer, Server server) : base(serializer, deserializer)
+        public AsyncCallServer(Action<TResponse, SerializationContext> serializer, Func<DeserializationContext, TRequest> deserializer, Server server) : base(serializer, deserializer)
         {
             this.server = GrpcPreconditions.CheckNotNull(server);
         }

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

@@ -0,0 +1,66 @@
+#region Copyright notice and license
+
+// Copyright 2018 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#endregion
+
+using Grpc.Core.Utils;
+using System;
+using System.Threading;
+
+namespace Grpc.Core.Internal
+{
+    internal class DefaultDeserializationContext : DeserializationContext
+    {
+        static readonly ThreadLocal<DefaultDeserializationContext> threadLocalInstance =
+            new ThreadLocal<DefaultDeserializationContext>(() => new DefaultDeserializationContext(), false);
+
+        byte[] payload;
+        bool alreadyCalledPayloadAsNewBuffer;
+
+        public DefaultDeserializationContext()
+        {
+            Reset();
+        }
+
+        public override int PayloadLength => payload.Length;
+
+        public override byte[] PayloadAsNewBuffer()
+        {
+            GrpcPreconditions.CheckState(!alreadyCalledPayloadAsNewBuffer);
+            alreadyCalledPayloadAsNewBuffer = true;
+            return payload;
+        }
+
+        public void Initialize(byte[] payload)
+        {
+            this.payload = GrpcPreconditions.CheckNotNull(payload);
+            this.alreadyCalledPayloadAsNewBuffer = false;
+        }
+
+        public void Reset()
+        {
+            this.payload = null;
+            this.alreadyCalledPayloadAsNewBuffer = true;  // mark payload as read
+        }
+
+        public static DefaultDeserializationContext GetInitializedThreadLocal(byte[] payload)
+        {
+            var instance = threadLocalInstance.Value;
+            instance.Initialize(payload);
+            return instance;
+        }
+    }
+}

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

@@ -0,0 +1,62 @@
+#region Copyright notice and license
+
+// Copyright 2018 The gRPC Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#endregion
+
+using Grpc.Core.Utils;
+using System.Threading;
+
+namespace Grpc.Core.Internal
+{
+    internal class DefaultSerializationContext : SerializationContext
+    {
+        static readonly ThreadLocal<DefaultSerializationContext> threadLocalInstance =
+            new ThreadLocal<DefaultSerializationContext>(() => new DefaultSerializationContext(), false);
+
+        bool isComplete;
+        byte[] payload;
+
+        public DefaultSerializationContext()
+        {
+            Reset();
+        }
+
+        public override void Complete(byte[] payload)
+        {
+            GrpcPreconditions.CheckState(!isComplete);
+            this.isComplete = true;
+            this.payload = payload;
+        }
+
+        internal byte[] GetPayload()
+        {
+            return this.payload;
+        }
+
+        public void Reset()
+        {
+            this.isComplete = false;
+            this.payload = null;
+        }
+
+        public static DefaultSerializationContext GetInitializedThreadLocal()
+        {
+            var instance = threadLocalInstance.Value;
+            instance.Reset();
+            return instance;
+        }
+    }
+}

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

@@ -52,8 +52,8 @@ namespace Grpc.Core.Internal
         public async Task HandleCall(ServerRpcNew newRpc, CompletionQueueSafeHandle cq)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
-                method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer,
+                method.ResponseMarshaller.ContextualSerializer,
+                method.RequestMarshaller.ContextualDeserializer,
                 newRpc.Server);
 
             asyncCall.Initialize(newRpc.Call, cq);
@@ -116,8 +116,8 @@ namespace Grpc.Core.Internal
         public async Task HandleCall(ServerRpcNew newRpc, CompletionQueueSafeHandle cq)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
-                method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer,
+                method.ResponseMarshaller.ContextualSerializer,
+                method.RequestMarshaller.ContextualDeserializer,
                 newRpc.Server);
 
             asyncCall.Initialize(newRpc.Call, cq);
@@ -179,8 +179,8 @@ namespace Grpc.Core.Internal
         public async Task HandleCall(ServerRpcNew newRpc, CompletionQueueSafeHandle cq)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
-                method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer,
+                method.ResponseMarshaller.ContextualSerializer,
+                method.RequestMarshaller.ContextualDeserializer,
                 newRpc.Server);
 
             asyncCall.Initialize(newRpc.Call, cq);
@@ -242,8 +242,8 @@ namespace Grpc.Core.Internal
         public async Task HandleCall(ServerRpcNew newRpc, CompletionQueueSafeHandle cq)
         {
             var asyncCall = new AsyncCallServer<TRequest, TResponse>(
-                method.ResponseMarshaller.Serializer,
-                method.RequestMarshaller.Deserializer,
+                method.ResponseMarshaller.ContextualSerializer,
+                method.RequestMarshaller.ContextualDeserializer,
                 newRpc.Server);
 
             asyncCall.Initialize(newRpc.Call, cq);

src/csharp/Grpc.Core/Marshaller.cs

@@ -41,6 +41,8 @@ namespace Grpc.Core
         {
             this.serializer = GrpcPreconditions.CheckNotNull(serializer, nameof(serializer));
             this.deserializer = GrpcPreconditions.CheckNotNull(deserializer, nameof(deserializer));
+            // contextual serialization/deserialization is emulated to make the marshaller
+            // usable with the grpc library (required for backward compatibility).
             this.contextualSerializer = EmulateContextualSerializer;
             this.contextualDeserializer = EmulateContextualDeserializer;
         }
@@ -57,10 +59,10 @@ namespace Grpc.Core
         {
             this.contextualSerializer = GrpcPreconditions.CheckNotNull(serializer, nameof(serializer));
             this.contextualDeserializer = GrpcPreconditions.CheckNotNull(deserializer, nameof(deserializer));
-            // TODO(jtattermusch): once gRPC C# library switches to using contextual (de)serializer,
-            // emulating the simple (de)serializer will become unnecessary.
-            this.serializer = EmulateSimpleSerializer;
-            this.deserializer = EmulateSimpleDeserializer;
+            // gRPC only uses contextual serializer/deserializer internally, so emulating the legacy
+            // (de)serializer is not necessary.
+            this.serializer = (msg) => { throw new NotImplementedException(); };
+            this.deserializer = (payload) => { throw new NotImplementedException(); };
         }
 
         /// <summary>
@@ -85,25 +87,6 @@ namespace Grpc.Core
         /// </summary>
         public Func<DeserializationContext, T> ContextualDeserializer => this.contextualDeserializer;
 
-        // for backward compatibility, emulate the simple serializer using the contextual one
-        private byte[] EmulateSimpleSerializer(T msg)
-        {
-            // TODO(jtattermusch): avoid the allocation by passing a thread-local instance
-            // This code will become unnecessary once gRPC C# library switches to using contextual (de)serializer.
-            var context = new EmulatedSerializationContext();
-            this.contextualSerializer(msg, context);
-            return context.GetPayload();
-        }
-
-        // for backward compatibility, emulate the simple deserializer using the contextual one
-        private T EmulateSimpleDeserializer(byte[] payload)
-        {
-            // TODO(jtattermusch): avoid the allocation by passing a thread-local instance
-            // This code will become unnecessary once gRPC C# library switches to using contextual (de)serializer.
-            var context = new EmulatedDeserializationContext(payload);
-            return this.contextualDeserializer(context);
-        }
-
         // for backward compatibility, emulate the contextual serializer using the simple one
         private void EmulateContextualSerializer(T message, SerializationContext context)
         {
@@ -116,44 +99,6 @@ namespace Grpc.Core
         {
             return this.deserializer(context.PayloadAsNewBuffer());
         }
-
-        internal class EmulatedSerializationContext : SerializationContext
-        {
-            bool isComplete;
-            byte[] payload;
-
-            public override void Complete(byte[] payload)
-            {
-                GrpcPreconditions.CheckState(!isComplete);
-                this.isComplete = true;
-                this.payload = payload;
-            }
-
-            internal byte[] GetPayload()
-            {
-                return this.payload;
-            }
-        }
-
-        internal class EmulatedDeserializationContext : DeserializationContext
-        {
-            readonly byte[] payload;
-            bool alreadyCalledPayloadAsNewBuffer;
-
-            public EmulatedDeserializationContext(byte[] payload)
-            {
-                this.payload = GrpcPreconditions.CheckNotNull(payload);
-            }
-
-            public override int PayloadLength => payload.Length;
-
-            public override byte[] PayloadAsNewBuffer()
-            {
-                GrpcPreconditions.CheckState(!alreadyCalledPayloadAsNewBuffer);
-                alreadyCalledPayloadAsNewBuffer = true;
-                return payload;
-            }
-        }
     }
 
     /// <summary>

src/csharp/Grpc.Core/SerializationContext.cs

@@ -16,6 +16,8 @@
 
 #endregion
 
+using System;
+
 namespace Grpc.Core
 {
     /// <summary>
@@ -29,6 +31,9 @@ namespace Grpc.Core
         /// payload which must not be accessed afterwards.
         /// </summary>
         /// <param name="payload">the serialized form of current message</param>
-        public abstract void Complete(byte[] payload);
+        public virtual void Complete(byte[] payload)
+        {
+            throw new NotImplementedException();
+        }
     }
 }