Pool buffer

src/ImageSharp/Formats/Jpeg/PdfJsPort/Components/DoubleBufferedStreamReader.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.IO;
+using SixLabors.ImageSharp.Memory;
 
 // TODO: This could be useful elsewhere.
 namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
@@ -11,7 +12,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
     /// A stream reader that add a secondary level buffer in addition to native stream buffered reading
     /// to reduce the overhead of small incremental reads.
     /// </summary>
-    internal class DoubleBufferedStreamReader
+    internal class DoubleBufferedStreamReader : IDisposable
     {
         /// <summary>
         /// The length, in bytes, of the chunk
@@ -20,6 +21,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
 
         private readonly Stream stream;
 
+        private readonly IManagedByteBuffer buffer;
+
         private readonly byte[] chunk;
 
         private int bytesRead;
@@ -29,14 +32,15 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
         /// <summary>
         /// Initializes a new instance of the <see cref="DoubleBufferedStreamReader"/> class.
         /// </summary>
+        /// <param name="memoryManager">The <see cref="MemoryManager"/> to use for buffer allocations.</param>
         /// <param name="stream">The input stream.</param>
-        public DoubleBufferedStreamReader(Stream stream)
+        public DoubleBufferedStreamReader(MemoryManager memoryManager, Stream stream)
         {
             this.stream = stream;
             this.Length = stream.Length;
 
-            // TODO: Consider pooling this.
-            this.chunk = new byte[ChunkLength];
+            this.buffer = memoryManager.AllocateCleanManagedByteBuffer(ChunkLength);
+            this.chunk = this.buffer.Array;
         }
 
         /// <summary>
@@ -147,5 +151,11 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components
 
             return Math.Max(n, 0);
         }
+
+        /// <inheritdoc/>
+        public void Dispose()
+        {
+            this.buffer?.Dispose();
+        }
     }
 }

src/ImageSharp/Formats/Jpeg/PdfJsPort/PdfJsJpegDecoderCore.cs

@@ -208,7 +208,7 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         public void ParseStream(Stream stream, bool metadataOnly = false)
         {
             this.MetaData = new ImageMetaData();
-            this.InputStream = new DoubleBufferedStreamReader(stream);
+            this.InputStream = new DoubleBufferedStreamReader(this.configuration.MemoryManager, stream);
 
             // Check for the Start Of Image marker.
             this.InputStream.Read(this.markerBuffer, 0, 2);
@@ -339,9 +339,11 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort
         /// <inheritdoc/>
         public void Dispose()
         {
+            this.InputStream?.Dispose();
             this.Frame?.Dispose();
 
             // Set large fields to null.
+            this.InputStream = null;
             this.Frame = null;
             this.dcHuffmanTables = null;
             this.acHuffmanTables = null;

tests/ImageSharp.Benchmarks/Codecs/Jpeg/DoubleBufferedStreams.cs

@@ -0,0 +1,73 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.IO;
+using BenchmarkDotNet.Attributes;
+using SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components;
+
+namespace SixLabors.ImageSharp.Benchmarks.Codecs.Jpeg
+{
+    [Config(typeof(Config.ShortClr))]
+    public class DoubleBufferedStreams
+    {
+        private byte[] buffer = CreateTestBytes();
+
+        private MemoryStream stream1;
+        private MemoryStream stream2;
+        DoubleBufferedStreamReader reader;
+
+        [GlobalSetup]
+        public void CreateStreams()
+        {
+            this.stream1 = new MemoryStream(this.buffer);
+            this.stream2 = new MemoryStream(this.buffer);
+            this.reader = new DoubleBufferedStreamReader(Configuration.Default.MemoryManager, this.stream2);
+        }
+
+        [GlobalCleanup]
+        public void DestroyStreams()
+        {
+            this.stream1?.Dispose();
+            this.stream2?.Dispose();
+            this.reader?.Dispose();
+        }
+
+        [Benchmark(Baseline = true)]
+        public int StandardStream()
+        {
+            int r = 0;
+            Stream stream = this.stream1;
+
+            for (int i = 0; i < stream.Length; i++)
+            {
+                r += stream.ReadByte();
+            }
+
+            return r;
+        }
+
+        [Benchmark]
+        public int DoubleBufferedStream()
+        {
+            int r = 0;
+            DoubleBufferedStreamReader reader = this.reader;
+
+            for (int i = 0; i < reader.Length; i++)
+            {
+                r += reader.ReadByte();
+            }
+
+            return r;
+        }
+
+        private static byte[] CreateTestBytes()
+        {
+            byte[] buffer = new byte[DoubleBufferedStreamReader.ChunkLength * 3];
+            var random = new Random();
+            random.NextBytes(buffer);
+
+            return buffer;
+        }
+    }
+}

tests/ImageSharp.Benchmarks/General/DoubleBufferedStreams.cs

@@ -1,53 +0,0 @@
-using System;
-using System.IO;
-using BenchmarkDotNet.Attributes;
-using SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort.Components;
-
-namespace SixLabors.ImageSharp.Benchmarks.General
-{
-    [Config(typeof(Config.ShortClr))]
-    public class DoubleBufferedStreams
-    {
-        private byte[] buffer = CreateTestBytes();
-
-        [Benchmark]
-        public int StandardStream()
-        {
-            int r = 0;
-            using (var stream = new MemoryStream(this.buffer))
-            {
-                for (int i = 0; i < stream.Length; i++)
-                {
-                    r += stream.ReadByte();
-                }
-            }
-
-            return r;
-        }
-
-        [Benchmark]
-        public int ChunkedStream()
-        {
-            int r = 0;
-            using (var stream = new MemoryStream(this.buffer))
-            {
-                var reader = new DoubleBufferedStreamReader(stream);
-                for (int i = 0; i < reader.Length; i++)
-                {
-                    r += reader.ReadByte();
-                }
-            }
-
-            return r;
-        }
-
-        private static byte[] CreateTestBytes()
-        {
-            byte[] buffer = new byte[DoubleBufferedStreamReader.ChunkLength * 3];
-            var random = new Random();
-            random.NextBytes(buffer);
-
-            return buffer;
-        }
-    }
-}