add unary call overhead benchmark

src/csharp/Grpc.Microbenchmarks/UnaryCallOverheadBenchmark.cs

@@ -0,0 +1,93 @@
+#region Copyright notice and license
+
+// Copyright 2019 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 System.Threading.Tasks;
+using BenchmarkDotNet.Attributes;
+using Grpc.Core;
+using Grpc.Core.Internal;
+using System;
+
+namespace Grpc.Microbenchmarks
+{
+    // this test creates a real server and client, measuring the inherent inbuilt
+    // platform overheads; the marshallers **DO NOT ALLOCATE**, so any allocations
+    // are from the framework, not the messages themselves
+
+    // important: allocs are not reliable on .NET Core until .NET Core 3, since
+    // this test involves multiple threads
+
+    [ClrJob, CoreJob] // test .NET Core and .NET Framework
+    [MemoryDiagnoser] // allocations
+    public class UnaryCallOverheadBenchmark
+    {
+        private static readonly Task<string> CompletedString = Task.FromResult("");
+        private static readonly byte[] EmptyBlob = new byte[0];
+        private static readonly Marshaller<string> EmptyMarshaller = new Marshaller<string>(_ => EmptyBlob, _ => "");
+        private static readonly Method<string, string> PingMethod = new Method<string, string>(MethodType.Unary, nameof(PingBenchmark), "Ping", EmptyMarshaller, EmptyMarshaller);
+
+        [Benchmark]
+        public string Ping()
+        {
+            return client.Ping("", new CallOptions());
+        }
+
+        Channel channel;
+        PingClient client;
+
+        [GlobalSetup]
+        public void Setup()
+        {
+            // create client
+            channel = new Channel("localhost", 10042, ChannelCredentials.Insecure);
+            client = new PingClient(new DefaultCallInvoker(channel));
+
+            var native = NativeMethods.Get();
+
+            // replace the implementation of a native method with a fake
+            NativeMethods.Delegates.grpcsharp_call_start_unary_delegate fakeCallStartUnary = (CallSafeHandle call, BatchContextSafeHandle ctx, byte[] sendBuffer, UIntPtr sendBufferLen, WriteFlags writeFlags, MetadataArraySafeHandle metadataArray, CallFlags metadataFlags) => {
+                return native.grpcsharp_test_call_start_unary_echo(call, ctx, sendBuffer, sendBufferLen, writeFlags, metadataArray, metadataFlags);
+            };
+            native.GetType().GetField(nameof(native.grpcsharp_call_start_unary)).SetValue(native, fakeCallStartUnary);
+
+            NativeMethods.Delegates.grpcsharp_completion_queue_pluck_delegate fakeCqPluck = (CompletionQueueSafeHandle cq, IntPtr tag) => {
+                return new CompletionQueueEvent {
+                    type = CompletionQueueEvent.CompletionType.OpComplete,
+                    success = 1,
+                    tag = tag
+                };
+            };
+            native.GetType().GetField(nameof(native.grpcsharp_completion_queue_pluck)).SetValue(native, fakeCqPluck);
+        }
+
+        [GlobalCleanup]
+        public async Task Cleanup()
+        {
+            await channel.ShutdownAsync();
+        }
+
+        class PingClient : LiteClientBase
+        {
+            public PingClient(CallInvoker callInvoker) : base(callInvoker) { }
+
+            public string Ping(string request, CallOptions options)
+            {
+                return CallInvoker.BlockingUnaryCall(PingMethod, null, options, request);
+            }
+        }
+    }
+}