Add optimized Read(Span) API

src/ImageSharp/IO/ChunkedMemoryStream.cs

@@ -236,11 +236,18 @@ namespace SixLabors.ImageSharp.IO
             Guard.NotNull(buffer, nameof(buffer));
             Guard.MustBeGreaterThanOrEqualTo(offset, 0, nameof(offset));
             Guard.MustBeGreaterThanOrEqualTo(count, 0, nameof(count));
-            if (buffer.Length - offset < count)
-            {
-                throw new ArgumentException($"{offset} subtracted from the buffer length is less than {count}");
-            }
+            Guard.IsFalse(buffer.Length - offset < count, nameof(buffer), $"{offset} subtracted from the buffer length is less than {count}");
+
+            return this.ReadImpl(buffer.AsSpan().Slice(offset, count));
+        }
+
+#if SUPPORTS_SPAN_STREAM
+        /// <inheritdoc/>
+        public override int Read(Span<byte> buffer) => this.ReadImpl(buffer);
+#endif
 
+        private int ReadImpl(Span<byte> buffer)
+        {
             this.EnsureNotDisposed();
 
             if (this.readChunk is null)
@@ -254,7 +261,7 @@ namespace SixLabors.ImageSharp.IO
                 this.readOffset = 0;
             }
 
-            byte[] chunkBuffer = this.readChunk.Buffer.Array;
+            Span<byte> chunkBuffer = this.readChunk.Buffer.GetSpan();
             int chunkSize = this.readChunk.Length;
             if (this.readChunk.Next is null)
             {
@@ -262,7 +269,8 @@ namespace SixLabors.ImageSharp.IO
             }
 
             int bytesRead = 0;
-
+            int offset = 0;
+            int count = buffer.Length;
             while (count > 0)
             {
                 if (this.readOffset == chunkSize)
@@ -275,7 +283,7 @@ namespace SixLabors.ImageSharp.IO
 
                     this.readChunk = this.readChunk.Next;
                     this.readOffset = 0;
-                    chunkBuffer = this.readChunk.Buffer.Array;
+                    chunkBuffer = this.readChunk.Buffer.GetSpan();
                     chunkSize = this.readChunk.Length;
                     if (this.readChunk.Next is null)
                     {
@@ -284,7 +292,7 @@ namespace SixLabors.ImageSharp.IO
                 }
 
                 int readCount = Math.Min(count, chunkSize - this.readOffset);
-                Buffer.BlockCopy(chunkBuffer, this.readOffset, buffer, offset, readCount);
+                chunkBuffer.Slice(this.readOffset, count).CopyTo(buffer.Slice(offset));
                 offset += readCount;
                 count -= readCount;
                 this.readOffset += readCount;

src/ImageSharp/Memory/MemoryOwnerExtensions.cs

@@ -13,6 +13,7 @@ namespace SixLabors.ImageSharp.Memory
     /// </summary>
     internal static class MemoryOwnerExtensions
     {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static Span<T> GetSpan<T>(this IMemoryOwner<T> buffer)
             => buffer.Memory.Span;
 

tests/ImageSharp.Tests/IO/ChunkedMemoryStreamTests.cs

@@ -49,8 +49,8 @@ namespace SixLabors.ImageSharp.Tests.IO
             Assert.Throws<ArgumentNullException>(() => ms2.Read(null, 0, 0));
             Assert.Throws<ArgumentOutOfRangeException>(() => ms2.Read(new byte[] { 1 }, -1, 0));
             Assert.Throws<ArgumentOutOfRangeException>(() => ms2.Read(new byte[] { 1 }, 0, -1));
-            Assert.Throws<ArgumentException>(null, () => ms2.Read(new byte[] { 1 }, 2, 0));
-            Assert.Throws<ArgumentException>(null, () => ms2.Read(new byte[] { 1 }, 0, 2));
+            Assert.Throws<ArgumentException>(() => ms2.Read(new byte[] { 1 }, 2, 0));
+            Assert.Throws<ArgumentException>(() => ms2.Read(new byte[] { 1 }, 0, 2));
 
             ms2.Dispose();
 
@@ -58,10 +58,11 @@ namespace SixLabors.ImageSharp.Tests.IO
         }
 
         [Theory]
-        [InlineData(1024)]
-        [InlineData(1024 * 4)]
-        [InlineData(1024 * 6)]
-        [InlineData(1024 * 8)]
+        [InlineData(ChunkedMemoryStream.DefaultBufferLength)]
+        [InlineData((int)(ChunkedMemoryStream.DefaultBufferLength * 1.5))]
+        [InlineData(ChunkedMemoryStream.DefaultBufferLength * 4)]
+        [InlineData((int)(ChunkedMemoryStream.DefaultBufferLength * 5.5))]
+        [InlineData(ChunkedMemoryStream.DefaultBufferLength * 8)]
         public void MemoryStream_ReadByteTest(int length)
         {
             using MemoryStream ms = this.CreateTestStream(length);
@@ -78,10 +79,11 @@ namespace SixLabors.ImageSharp.Tests.IO
         }
 
         [Theory]
-        [InlineData(1024)]
-        [InlineData(1024 * 4)]
-        [InlineData(1024 * 6)]
-        [InlineData(1024 * 8)]
+        [InlineData(ChunkedMemoryStream.DefaultBufferLength)]
+        [InlineData((int)(ChunkedMemoryStream.DefaultBufferLength * 1.5))]
+        [InlineData(ChunkedMemoryStream.DefaultBufferLength * 4)]
+        [InlineData((int)(ChunkedMemoryStream.DefaultBufferLength * 5.5))]
+        [InlineData(ChunkedMemoryStream.DefaultBufferLength * 8)]
         public void MemoryStream_ReadByteBufferTest(int length)
         {
             using MemoryStream ms = this.CreateTestStream(length);
@@ -99,6 +101,29 @@ namespace SixLabors.ImageSharp.Tests.IO
             }
         }
 
+        [Theory]
+        [InlineData(ChunkedMemoryStream.DefaultBufferLength)]
+        [InlineData((int)(ChunkedMemoryStream.DefaultBufferLength * 1.5))]
+        [InlineData(ChunkedMemoryStream.DefaultBufferLength * 4)]
+        [InlineData((int)(ChunkedMemoryStream.DefaultBufferLength * 5.5))]
+        [InlineData(ChunkedMemoryStream.DefaultBufferLength * 8)]
+        public void MemoryStream_ReadByteBufferSpanTest(int length)
+        {
+            using MemoryStream ms = this.CreateTestStream(length);
+            using var cms = new ChunkedMemoryStream(this.allocator);
+
+            ms.CopyTo(cms);
+            cms.Position = 0;
+            var expected = ms.ToArray();
+            Span<byte> buffer = new byte[2];
+            for (int i = 0; i < expected.Length; i += 2)
+            {
+                cms.Read(buffer);
+                Assert.Equal(expected[i], buffer[0]);
+                Assert.Equal(expected[i + 1], buffer[1]);
+            }
+        }
+
         [Fact]
         public void MemoryStream_WriteToTests()
         {
@@ -107,7 +132,7 @@ namespace SixLabors.ImageSharp.Tests.IO
                 byte[] bytArrRet;
                 byte[] bytArr = new byte[] { byte.MinValue, byte.MaxValue, 1, 2, 3, 4, 5, 6, 128, 250 };
 
-                // [] Write to FileStream, check the filestream
+                // [] Write to memoryStream, check the memoryStream
                 ms2.Write(bytArr, 0, bytArr.Length);
 
                 using var readonlyStream = new ChunkedMemoryStream(this.allocator);