Fix MemoryManager ctor, add unit and perf tests, and improve performance (#28880)

* Fix MemoryManager ctor, add unit and perf tests, and improve performance.

* Remove Dangerous Span Ctor

* Fix sort order in csproj and rename Perf.MemorySlice.cs to Perf.Memory.Slice

* Fix MemoryManager ctor and use internal span ctor to improve performance (#17452)

* Fix MemoryManager ctor, add unit and perf tests, and use internal span ctor.

* Address PR feedback (remove use of Unsafe.As and Dangerous Span Ctor)

Signed-off-by: dotnet-bot-corefx-mirror <dotnet-bot@microsoft.com>

6 files changed, 254 insertions, 1 deletions

diff --git a/src/System.Memory/tests/Memory/MemoryManager.cs b/src/System.Memory/tests/Memory/MemoryManager.cs
index 4f6f2461cf..5a6c675c72 100644
--- a/src/System.Memory/tests/Memory/MemoryManager.cs
+++ b/src/System.Memory/tests/Memory/MemoryManager.cs
@@ -28,6 +28,33 @@ namespace System.MemoryTests
         }
 
         [Fact]
+        public static void MemoryManagerCtorDefault()
+        {
+            MemoryManager<int> managerInt = default;
+            Assert.Throws<ArgumentNullException>(() => new Memory<int>(managerInt, 0, 0));
+
+            managerInt = null;
+            Assert.Throws<ArgumentNullException>(() => new Memory<int>(managerInt, 0, 0));
+
+            MemoryManager<object> managerObject = default;
+            Assert.Throws<ArgumentNullException>(() => new Memory<object>(managerObject, 0, 0));
+        }
+
+        [Fact]
+        public static void MemoryManagerCtorInvalid()
+        {
+            int[] a = { 91, 92, -93, 94 };
+            MemoryManager<int> manager = new CustomMemoryForTest<int>(a);
+            Assert.Throws<ArgumentOutOfRangeException>(() => new Memory<int>(manager, 0, -1));
+            Assert.Throws<ArgumentOutOfRangeException>(() => new Memory<int>(manager, -1, 0));
+            Assert.Throws<ArgumentOutOfRangeException>(() => new Memory<int>(manager, -1, -1));
+            Assert.Throws<ArgumentOutOfRangeException>(() => new Memory<int>(manager, -1, -1));
+            Assert.Throws<ArgumentOutOfRangeException>(() => new Memory<int>(manager, 0, a.Length + 1));
+            Assert.Throws<ArgumentOutOfRangeException>(() => new Memory<int>(manager, a.Length + 1, 0));
+            Assert.Throws<ArgumentOutOfRangeException>(() => new Memory<int>(manager, 1, a.Length));
+        }
+
+        [Fact]
         public static void ReadOnlyMemoryFromMemoryFromMemoryManagerInt()
         {
             int[] a = { 91, 92, -93, 94 };
diff --git a/src/System.Memory/tests/Memory/Span.cs b/src/System.Memory/tests/Memory/Span.cs
index 55ed001b3d..55956dd6ab 100644
--- a/src/System.Memory/tests/Memory/Span.cs
+++ b/src/System.Memory/tests/Memory/Span.cs
@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System.Buffers;
+using System.Runtime.InteropServices;
 using Xunit;
 
 namespace System.MemoryTests
@@ -42,6 +43,22 @@ namespace System.MemoryTests
         }
 
         [Fact]
+        public static void SpanFromCtorArrayChar()
+        {
+            char[] a = { '1', '2', '3', '4', '-' };
+            Memory<char> memory;
+
+            memory = new Memory<char>(a);
+            memory.Span.Validate('1', '2', '3', '4', '-');
+
+            memory = new Memory<char>(a, 0, a.Length);
+            memory.Span.Validate('1', '2', '3', '4', '-');
+
+            MemoryManager<char> manager = new CustomMemoryForTest<char>(a);
+            manager.Memory.Span.Validate('1', '2', '3', '4', '-');
+        }
+
+        [Fact]
         public static void SpanFromCtorArrayObject()
         {
             object o1 = new object();
@@ -60,6 +77,19 @@ namespace System.MemoryTests
         }
 
         [Fact]
+        public static void SpanFromStringAsMemory()
+        {
+            string a = "1234-";
+            ReadOnlyMemory<char> memory;
+
+            memory = a.AsMemory();
+            MemoryMarshal.AsMemory(memory).Span.Validate('1', '2', '3', '4', '-');
+
+            memory = a.AsMemory(0, a.Length);
+            MemoryMarshal.AsMemory(memory).Span.Validate('1', '2', '3', '4', '-');
+        }
+
+        [Fact]
         public static void SpanFromCtorArrayZeroLength()
         {
             int[] empty = Array.Empty<int>();
diff --git a/src/System.Memory/tests/Performance/Perf.MemorySlice.cs b/src/System.Memory/tests/Performance/Perf.Memory.Slice.cs
index 27cecdef49..27cecdef49 100644
--- a/src/System.Memory/tests/Performance/Perf.MemorySlice.cs
+++ b/src/System.Memory/tests/Performance/Perf.Memory.Slice.cs
diff --git a/src/System.Memory/tests/Performance/Perf.Memory.Span.cs b/src/System.Memory/tests/Performance/Perf.Memory.Span.cs
new file mode 100644
index 0000000000..f2db92e0f4
--- /dev/null
+++ b/src/System.Memory/tests/Performance/Perf.Memory.Span.cs
@@ -0,0 +1,166 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Buffers;
+using System.MemoryTests;
+using Microsoft.Xunit.Performance;
+using Xunit;
+
+namespace System.Memory.Tests
+{
+    public class Perf_Memory_Span
+    {
+        private const int InnerCount = 1_000_000;
+
+        [Benchmark(InnerIterationCount = InnerCount)]
+        public static void SpanFromDefaultIntegerMemory()
+        {
+            Memory<int> memory = default;
+
+            foreach (BenchmarkIteration iteration in Benchmark.Iterations)
+            {
+                using (iteration.StartMeasurement())
+                {
+                    for (int i = 0; i < Benchmark.InnerIterationCount; i++)
+                    {
+                        Span<int> span = memory.Span;
+                    }
+                }
+            }
+        }
+
+        [Benchmark(InnerIterationCount = InnerCount)]
+        public static void SpanFromIntegerArrayBackedMemory()
+        {
+            int[] a = { 91, 92, -93, 94 };
+            var memory = new Memory<int>(a);
+
+            foreach (BenchmarkIteration iteration in Benchmark.Iterations)
+            {
+                using (iteration.StartMeasurement())
+                {
+                    for (int i = 0; i < Benchmark.InnerIterationCount; i++)
+                    {
+                        Span<int> span = memory.Span;
+                    }
+                }
+            }
+        }
+
+        [Benchmark(InnerIterationCount = InnerCount)]
+        public static void SpanFromCharArrayBackedMemory()
+        {
+            char[] a = "9192-9394".ToCharArray();
+            var memory = new Memory<char>(a);
+
+            foreach (BenchmarkIteration iteration in Benchmark.Iterations)
+            {
+                using (iteration.StartMeasurement())
+                {
+                    for (int i = 0; i < Benchmark.InnerIterationCount; i++)
+                    {
+                        Span<char> span = memory.Span;
+                    }
+                }
+            }
+        }
+
+        [Benchmark(InnerIterationCount = InnerCount)]
+        public static void SpanFromObjectArrayBackedMemory()
+        {
+            object o1 = new object();
+            object o2 = new object();
+            object[] a = { o1, o2 };
+            var memory = new Memory<object>(a);
+
+            foreach (BenchmarkIteration iteration in Benchmark.Iterations)
+            {
+                using (iteration.StartMeasurement())
+                {
+                    for (int i = 0; i < Benchmark.InnerIterationCount; i++)
+                    {
+                        Span<object> span = memory.Span;
+                    }
+                }
+            }
+        }
+
+        [Benchmark(InnerIterationCount = InnerCount)]
+        public static void SpanFromStringBackedMemory()
+        {
+            string a = "9192-9394";
+            ReadOnlyMemory<char> memory = a.AsMemory();
+
+            foreach (BenchmarkIteration iteration in Benchmark.Iterations)
+            {
+                using (iteration.StartMeasurement())
+                {
+                    for (int i = 0; i < Benchmark.InnerIterationCount; i++)
+                    {
+                        ReadOnlySpan<char> span = memory.Span;
+                    }
+                }
+            }
+        }
+
+        [Benchmark(InnerIterationCount = InnerCount)]
+        public static void SpanFromIntegerMemoryManager()
+        {
+            int[] a = { 91, 92, -93, 94 };
+            var memory = new Memory<int>(a);
+            MemoryManager<int> manager = new CustomMemoryForTest<int>(a);
+
+            foreach (BenchmarkIteration iteration in Benchmark.Iterations)
+            {
+                using (iteration.StartMeasurement())
+                {
+                    for (int i = 0; i < Benchmark.InnerIterationCount; i++)
+                    {
+                        Span<int> span = manager.Memory.Span;
+                    }
+                }
+            }
+        }
+
+        [Benchmark(InnerIterationCount = InnerCount)]
+        public static void SpanFromCharMemoryManager()
+        {
+            char[] a = "9192-9394".ToCharArray();
+            var memory = new Memory<char>(a);
+            MemoryManager<char> manager = new CustomMemoryForTest<char>(a);
+
+            foreach (BenchmarkIteration iteration in Benchmark.Iterations)
+            {
+                using (iteration.StartMeasurement())
+                {
+                    for (int i = 0; i < Benchmark.InnerIterationCount; i++)
+                    {
+                        Span<char> span = manager.Memory.Span;
+                    }
+                }
+            }
+        }
+
+        [Benchmark(InnerIterationCount = InnerCount)]
+        public static void SpanFromObjectMemoryManager()
+        {
+            object o1 = new object();
+            object o2 = new object();
+            object[] a = { o1, o2 };
+            var memory = new Memory<object>(a);
+            MemoryManager<object> manager = new CustomMemoryForTest<object>(a);
+
+            foreach (BenchmarkIteration iteration in Benchmark.Iterations)
+            {
+                using (iteration.StartMeasurement())
+                {
+                    for (int i = 0; i < Benchmark.InnerIterationCount; i++)
+                    {
+                        Span<object> span = manager.Memory.Span;
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/src/System.Memory/tests/Performance/System.Memory.Performance.Tests.csproj b/src/System.Memory/tests/Performance/System.Memory.Performance.Tests.csproj
index edb6ffe73c..28249af672 100644
--- a/src/System.Memory/tests/Performance/System.Memory.Performance.Tests.csproj
+++ b/src/System.Memory/tests/Performance/System.Memory.Performance.Tests.csproj
@@ -10,6 +10,8 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp-Release|AnyCPU'" />
   <ItemGroup>
     <Compile Include="Perf.Base64EncodeDecode.cs" />
+    <Compile Include="Perf.Memory.Slice.cs" />
+    <Compile Include="Perf.Memory.Span.cs" />
     <Compile Include="Perf.ReadOnlySequence.Enumerator.cs" />
     <Compile Include="Perf.ReadOnlySequence.First.cs" />
     <Compile Include="Perf.ReadOnlySequence.GetPosition.cs" />
@@ -23,7 +25,6 @@
     <Compile Include="Perf.Span.IndexOfAny.cs" />
     <Compile Include="Perf.Span.SequenceCompareTo.cs" />
     <Compile Include="Perf.Span.StartsWith.cs" />
-    <Compile Include="Perf.MemorySlice.cs" />
     <Compile Include="Perf.Utf8Formatter.cs" />
     <Compile Include="Perf.Utf8Parser.cs" />
     <Compile Include="..\Base64\Base64TestHelper.cs" />
diff --git a/src/System.Memory/tests/ReadOnlyMemory/Span.cs b/src/System.Memory/tests/ReadOnlyMemory/Span.cs
index 50ac96ee79..728c65e2e1 100644
--- a/src/System.Memory/tests/ReadOnlyMemory/Span.cs
+++ b/src/System.Memory/tests/ReadOnlyMemory/Span.cs
@@ -42,6 +42,22 @@ namespace System.MemoryTests
         }
 
         [Fact]
+        public static void SpanFromCtorArrayChar()
+        {
+            char[] a = { '1', '2', '3', '4', '-' };
+            ReadOnlyMemory<char> memory;
+
+            memory = new ReadOnlyMemory<char>(a);
+            memory.Span.Validate('1', '2', '3', '4', '-');
+
+            memory = new ReadOnlyMemory<char>(a, 0, a.Length);
+            memory.Span.Validate('1', '2', '3', '4', '-');
+
+            MemoryManager<char> manager = new CustomMemoryForTest<char>(a);
+            ((ReadOnlyMemory<char>)manager.Memory).Span.Validate('1', '2', '3', '4', '-');
+        }
+
+        [Fact]
         public static void SpanFromCtorArrayObject()
         {
             object o1 = new object();
@@ -60,6 +76,19 @@ namespace System.MemoryTests
         }
 
         [Fact]
+        public static void SpanFromStringAsMemory()
+        {
+            string a = "1234-";
+            ReadOnlyMemory<char> memory;
+
+            memory = a.AsMemory();
+            memory.Span.Validate('1', '2', '3', '4', '-');
+
+            memory = a.AsMemory(0, a.Length);
+            memory.Span.Validate('1', '2', '3', '4', '-');
+        }
+
+        [Fact]
         public static void SpanFromCtorArrayZeroLength()
         {
             int[] empty = Array.Empty<int>();