use System.Memory and Span<> on all TFMs

src/csharp/Grpc.Core.Api/DeserializationContext.cs

@@ -48,13 +48,12 @@ namespace Grpc.Core
             throw new NotImplementedException();
         }
 
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
         /// <summary>
         /// Gets the entire payload as a ReadOnlySequence.
         /// The ReadOnlySequence is only valid for the duration of the deserializer routine and the caller must not access it after the deserializer returns.
         /// Using the read only sequence is the most efficient way to access the message payload. Where possible it allows directly
         /// accessing the received payload without needing to perform any buffer copying or buffer allocations.
-        /// NOTE: This method is only available in the netstandard2.0 build of the library.
+        /// NOTE: In order to access the payload via this method, your compiler needs to support C# 7.2 (to be able to use the <c>Span</c> type).
         /// NOTE: Deserializers are expected not to call this method (or other payload accessor methods) more than once per received message
         /// (as there is no practical reason for doing so) and <c>DeserializationContext</c> implementations are free to assume so.
         /// </summary>
@@ -63,6 +62,5 @@ namespace Grpc.Core
         {
             throw new NotImplementedException();
         }
-#endif        
     }
 }

src/csharp/Grpc.Core.Api/Grpc.Core.Api.csproj

@@ -20,18 +20,11 @@
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
   </PropertyGroup>
 
-  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
-    <DefineConstants>$(DefineConstants);GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY</DefineConstants>
-  </PropertyGroup>
-
   <Import Project="..\Grpc.Core\SourceLink.csproj.include" />
 
   <ItemGroup>
     <PackageReference Include="System.Interactive.Async" Version="3.2.0" />
-  </ItemGroup>
-
-  <ItemGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
-    <PackageReference Include="System.Memory" Version="4.5.2" />
+    <PackageReference Include="System.Memory" Version="4.5.3" />
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net45' ">

src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj

@@ -9,10 +9,6 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
-  <PropertyGroup Condition=" '$(TargetFramework)' == 'netcoreapp2.1' ">
-    <DefineConstants>$(DefineConstants);GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY</DefineConstants>
-  </PropertyGroup>
-
   <ItemGroup>
     <ProjectReference Include="../Grpc.Core/Grpc.Core.csproj" />
   </ItemGroup>

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

@@ -17,18 +17,14 @@
 #endregion
 
 using System;
+using System.Buffers;
 using System.Collections.Generic;
+using System.Runtime.InteropServices;
 using Grpc.Core;
 using Grpc.Core.Internal;
 using Grpc.Core.Utils;
 using NUnit.Framework;
 
-using System.Runtime.InteropServices;
-
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
-using System.Buffers;
-#endif
-
 namespace Grpc.Core.Internal.Tests
 {
     public class DefaultDeserializationContextTest
@@ -47,7 +43,6 @@ namespace Grpc.Core.Internal.Tests
             fakeBufferReaderManager.Dispose();
         }
 
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
         [TestCase]
         public void PayloadAsReadOnlySequence_ZeroSegmentPayload()
         {
@@ -118,7 +113,6 @@ namespace Grpc.Core.Internal.Tests
 
             Assert.IsFalse(segmentEnumerator.MoveNext());
         }
-#endif
 
         [TestCase]
         public void NullPayloadNotAllowed()
@@ -196,9 +190,7 @@ namespace Grpc.Core.Internal.Tests
 
             // Getting payload multiple times is illegal
             Assert.Throws(typeof(InvalidOperationException), () => context.PayloadAsNewBuffer());
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
             Assert.Throws(typeof(InvalidOperationException), () => context.PayloadAsReadOnlySequence());
-#endif
         }
 
         [TestCase]
@@ -215,9 +207,7 @@ namespace Grpc.Core.Internal.Tests
 
             Assert.AreEqual(0, context.PayloadLength);
             Assert.Throws(typeof(NullReferenceException), () => context.PayloadAsNewBuffer());
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
             Assert.Throws(typeof(NullReferenceException), () => context.PayloadAsReadOnlySequence());
-#endif
 
             // Previously reset context can be initialized again
             var origBuffer2 = GetTestBuffer(50);

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

@@ -103,7 +103,7 @@ namespace Grpc.Core.Internal.Tests
         private void AssertSliceDataEqual(byte[] expected, Slice actual)
         {
             var actualSliceData = new byte[actual.Length];
-            actual.CopyTo(new ArraySegment<byte>(actualSliceData));
+            actual.ToSpanUnsafe().CopyTo(actualSliceData);
             CollectionAssert.AreEqual(expected, actualSliceData);
         }
 

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

@@ -17,19 +17,15 @@
 #endregion
 
 using System;
+using System.Buffers;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.InteropServices;
 using Grpc.Core;
 using Grpc.Core.Internal;
 using Grpc.Core.Utils;
 using NUnit.Framework;
 
-using System.Runtime.InteropServices;
-
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
-using System.Buffers;
-#endif
-
 namespace Grpc.Core.Internal.Tests
 {
     // Converts IBufferReader into instances of ReadOnlySequence<byte>
@@ -50,7 +46,6 @@ namespace Grpc.Core.Internal.Tests
             fakeBufferReaderManager.Dispose();
         }
 
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
         [TestCase]
         public void NullPayload()
         {
@@ -131,13 +126,7 @@ namespace Grpc.Core.Internal.Tests
             }
             return result;
         }
-#else
-        [TestCase]
-        public void OnlySupportedOnNetCore()
-        {
-            // Test case needs to exist to make C# sanity test happy.
-        }
-#endif
+
         private byte[] GetTestBuffer(int length)
         {
             var testBuffer = new byte[length];

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

@@ -33,7 +33,7 @@ namespace Grpc.Core.Internal.Tests
         [TestCase(10)]
         [TestCase(100)]
         [TestCase(1000)]
-        public void SliceFromNativePtr_CopyToArraySegment(int bufferLength)
+        public void SliceFromNativePtr_Copy(int bufferLength)
         {
             var origBuffer = GetTestBuffer(bufferLength);
             var gcHandle = GCHandle.Alloc(origBuffer, GCHandleType.Pinned);
@@ -43,7 +43,7 @@ namespace Grpc.Core.Internal.Tests
                 Assert.AreEqual(bufferLength, slice.Length);
 
                 var newBuffer = new byte[bufferLength];
-                slice.CopyTo(new ArraySegment<byte>(newBuffer));
+                slice.ToSpanUnsafe().CopyTo(newBuffer);
                 CollectionAssert.AreEqual(origBuffer, newBuffer);
             }
             finally
@@ -52,23 +52,6 @@ namespace Grpc.Core.Internal.Tests
             }
         }
 
-        [TestCase]
-        public void SliceFromNativePtr_CopyToArraySegmentTooSmall()
-        {
-            var origBuffer = GetTestBuffer(100);
-            var gcHandle = GCHandle.Alloc(origBuffer, GCHandleType.Pinned);
-            try
-            {
-                var slice = new Slice(gcHandle.AddrOfPinnedObject(), origBuffer.Length);
-                var tooSmall = new byte[origBuffer.Length - 1];
-                Assert.Catch(typeof(ArgumentException), () => slice.CopyTo(new ArraySegment<byte>(tooSmall)));
-            }
-            finally
-            {
-                gcHandle.Free();
-            }
-        }
-
         // create a buffer of given size and fill it with some data
         private byte[] GetTestBuffer(int length)
         {

src/csharp/Grpc.Core/Grpc.Core.csproj

@@ -23,9 +23,8 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
-  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
+  <PropertyGroup>
     <LangVersion>7.2</LangVersion>
-    <DefineConstants>$(DefineConstants);GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY</DefineConstants>
   </PropertyGroup>
 
   <ItemGroup>
@@ -100,8 +99,7 @@
 
   <ItemGroup>
     <PackageReference Include="System.Interactive.Async" Version="3.2.0" />
-    <!-- System.Buffers *may* come in transitively, but: we can *always* use ArrayPool -->
-    <PackageReference Include="System.Buffers" Version="4.5.0" />
+    <PackageReference Include="System.Memory" Version="4.5.3" />
   </ItemGroup>
 
   <ItemGroup Condition=" '$(TargetFramework)' == 'net45' ">

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

@@ -16,13 +16,10 @@
 
 #endregion
 
-using Grpc.Core.Utils;
 using System;
-using System.Threading;
-
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
 using System.Buffers;
-#endif
+using System.Threading;
+using Grpc.Core.Utils;
 
 namespace Grpc.Core.Internal
 {
@@ -33,9 +30,7 @@ namespace Grpc.Core.Internal
 
         IBufferReader bufferReader;
         int payloadLength;
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
         ReusableSliceBuffer cachedSliceBuffer = new ReusableSliceBuffer();
-#endif
 
         public DefaultDeserializationContext()
         {
@@ -51,14 +46,12 @@ namespace Grpc.Core.Internal
             return buffer;
         }
 
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
         public override ReadOnlySequence<byte> PayloadAsReadOnlySequence()
         {
             var sequence = cachedSliceBuffer.PopulateFrom(bufferReader);
             GrpcPreconditions.CheckState(sequence.Length == payloadLength);
             return sequence;
         }
-#endif
 
         public void Initialize(IBufferReader bufferReader)
         {
@@ -70,9 +63,7 @@ namespace Grpc.Core.Internal
         {
             this.bufferReader = null;
             this.payloadLength = 0;
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
             this.cachedSliceBuffer.Invalidate();
-#endif
         }
 
         public static DefaultDeserializationContext GetInitializedThreadLocal(IBufferReader bufferReader)
@@ -84,18 +75,7 @@ namespace Grpc.Core.Internal
 
         private void FillContinguousBuffer(IBufferReader reader, byte[] destination)
         {
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
             PayloadAsReadOnlySequence().CopyTo(new Span<byte>(destination));
-#else
-            int offset = 0;
-            while (reader.TryGetNextSlice(out Slice slice))
-            {
-                slice.CopyTo(new ArraySegment<byte>(destination, offset, (int)slice.Length));
-                offset += (int)slice.Length;
-            }
-            // check that we filled the entire destination
-            GrpcPreconditions.CheckState(offset == payloadLength);
-#endif
         }
     }
 }

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

@@ -16,8 +16,6 @@
 
 #endregion
 
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
-
 using Grpc.Core.Utils;
 using System;
 using System.Threading;
@@ -145,4 +143,3 @@ namespace Grpc.Core.Internal
         }
     }
 }
-#endif

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

@@ -40,14 +40,6 @@ namespace Grpc.Core.Internal
 
         public int Length => length;
 
-        // copies data of the slice to given span.
-        // there needs to be enough space in the destination buffer
-        public void CopyTo(ArraySegment<byte> destination)
-        {
-            Marshal.Copy(dataPtr, destination.Array, destination.Offset, length);
-        }
-
-#if GRPC_CSHARP_SUPPORT_SYSTEM_MEMORY
         public Span<byte> ToSpanUnsafe()
         {
             unsafe
@@ -55,7 +47,6 @@ namespace Grpc.Core.Internal
                 return new Span<byte>((byte*) dataPtr, length);
             }
         }
-#endif
 
         /// <summary>
         /// Returns a <see cref="System.String"/> that represents the current <see cref="Grpc.Core.Internal.Slice"/>.