Add benchmark

Makefile.am

@@ -89,6 +89,7 @@ csharp_EXTRA_DIST=                                                           \
   csharp/src/Google.Protobuf.Benchmarks/BenchmarkDatasetConfig.cs            \
   csharp/src/Google.Protobuf.Benchmarks/BenchmarkMessage1Proto3.cs           \
   csharp/src/Google.Protobuf.Benchmarks/Benchmarks.cs                        \
+  csharp/src/Google.Protobuf.Benchmarks/ByteStringBenchmark.cs               \
   csharp/src/Google.Protobuf.Benchmarks/Google.Protobuf.Benchmarks.csproj    \
   csharp/src/Google.Protobuf.Benchmarks/GoogleMessageBenchmark.cs            \
   csharp/src/Google.Protobuf.Benchmarks/ParseMessagesBenchmark.cs            \

csharp/src/Google.Protobuf.Benchmarks/ByteStringBenchmark.cs

@@ -0,0 +1,73 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2019 Google Inc.  All rights reserved.
+// https://github.com/protocolbuffers/protobuf
+//
+// 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 BenchmarkDotNet.Attributes;
+
+namespace Google.Protobuf.Benchmarks
+{
+    /// <summary>
+    /// Benchmarks using ByteString.
+    /// </summary>
+    [MemoryDiagnoser]
+    public class ByteStringBenchmark
+    {
+        private const int Zero = 0;
+        private const int Kilobyte = 1024;
+        private const int _128Kilobytes = 1024 * 128;
+        private const int Megabyte = 1024 * 1024;
+        private const int _10Megabytes = 1024 * 1024 * 10;
+
+
+        byte[] byteBuffer;
+
+        [GlobalSetup]
+        public void GlobalSetup()
+        {
+            byteBuffer = new byte[BytesToParse];
+        }
+
+        [Params(Zero, Kilobyte, _128Kilobytes, Megabyte, _10Megabytes)]
+        public int BytesToParse { get; set; }
+
+        [Benchmark]
+        public ByteString CopyFrom()
+        {
+            return ByteString.CopyFrom(byteBuffer);
+        }
+
+        [Benchmark]
+        public ByteString UnsafeWrap()
+        {
+            return UnsafeByteOperations.UnsafeWrap(byteBuffer);
+        }
+    }
+}