Merge pull request #13462 from jtattermusch/tuple_is_not_a_struct

ServerCallHandlers: save allocation by using a struct instead of a tuple

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

@@ -127,10 +127,10 @@ namespace Grpc.Core.Internal
         /// 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 Task SendStatusFromServerAsync(Status status, Metadata trailers, Tuple<TResponse, WriteFlags> optionalWrite)
+        public Task SendStatusFromServerAsync(Status status, Metadata trailers, ResponseWithFlags? optionalWrite)
         {
-            byte[] payload = optionalWrite != null ? UnsafeSerialize(optionalWrite.Item1) : null;
-            var writeFlags = optionalWrite != null ? optionalWrite.Item2 : default(WriteFlags);
+            byte[] payload = optionalWrite.HasValue ? UnsafeSerialize(optionalWrite.Value.Response) : null;
+            var writeFlags = optionalWrite.HasValue ? optionalWrite.Value.WriteFlags : default(WriteFlags);
 
             lock (myLock)
             {
@@ -146,7 +146,7 @@ namespace Grpc.Core.Internal
                 halfcloseRequested = true;
                 initialMetadataSent = true;
                 sendStatusFromServerTcs = new TaskCompletionSource<object>();
-                if (optionalWrite != null)
+                if (optionalWrite.HasValue)
                 {
                     streamingWritesCounter++;
                 }
@@ -241,5 +241,17 @@ namespace Grpc.Core.Internal
         {
             HandleSendStatusFromServerFinished(success);
         }
+
+        public struct ResponseWithFlags
+        {
+            public ResponseWithFlags(TResponse response, WriteFlags writeFlags)
+            {
+                this.Response = response;
+                this.WriteFlags = writeFlags;
+            }
+
+            public TResponse Response { get; }
+            public WriteFlags WriteFlags { get; }
+        }
     }
 }

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

@@ -60,7 +60,7 @@ namespace Grpc.Core.Internal
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
 
             Status status;
-            Tuple<TResponse,WriteFlags> responseTuple = null;
+            AsyncCallServer<TRequest,TResponse>.ResponseWithFlags? responseWithFlags = null;
             var context = HandlerUtils.NewContext(newRpc, responseStream, asyncCall.CancellationToken);
             try
             {
@@ -68,7 +68,7 @@ namespace Grpc.Core.Internal
                 var request = requestStream.Current;
                 var response = await handler(request, context).ConfigureAwait(false);
                 status = context.Status;
-                responseTuple = Tuple.Create(response, HandlerUtils.GetWriteFlags(context.WriteOptions));
+                responseWithFlags = new AsyncCallServer<TRequest, TResponse>.ResponseWithFlags(response, HandlerUtils.GetWriteFlags(context.WriteOptions));
             } 
             catch (Exception e)
             {
@@ -80,7 +80,7 @@ namespace Grpc.Core.Internal
             }
             try
             {
-                await asyncCall.SendStatusFromServerAsync(status, context.ResponseTrailers, responseTuple).ConfigureAwait(false);
+                await asyncCall.SendStatusFromServerAsync(status, context.ResponseTrailers, responseWithFlags).ConfigureAwait(false);
             }
             catch (Exception)
             {
@@ -177,13 +177,13 @@ namespace Grpc.Core.Internal
             var responseStream = new ServerResponseStream<TRequest, TResponse>(asyncCall);
 
             Status status;
-            Tuple<TResponse,WriteFlags> responseTuple = null;
+            AsyncCallServer<TRequest, TResponse>.ResponseWithFlags? responseWithFlags = null;
             var context = HandlerUtils.NewContext(newRpc, responseStream, asyncCall.CancellationToken);
             try
             {
                 var response = await handler(requestStream, context).ConfigureAwait(false);
                 status = context.Status;
-                responseTuple = Tuple.Create(response, HandlerUtils.GetWriteFlags(context.WriteOptions));
+                responseWithFlags = new AsyncCallServer<TRequest, TResponse>.ResponseWithFlags(response, HandlerUtils.GetWriteFlags(context.WriteOptions));
             }
             catch (Exception e)
             {
@@ -196,7 +196,7 @@ namespace Grpc.Core.Internal
 
             try
             {
-                await asyncCall.SendStatusFromServerAsync(status, context.ResponseTrailers, responseTuple).ConfigureAwait(false);
+                await asyncCall.SendStatusFromServerAsync(status, context.ResponseTrailers, responseWithFlags).ConfigureAwait(false);
             }
             catch (Exception)
             {