pooling JpegDecoderCore.DecodedBlocks + made Sandbox46 executable

src/ImageSharp.Formats.Jpeg/Components/Block8x8F.cs

@@ -6,6 +6,7 @@
 namespace ImageSharp.Formats.Jpg
 {
     using System;
+    using System.Buffers;
     using System.Numerics;
     using System.Runtime.CompilerServices;
     using System.Runtime.InteropServices;

src/ImageSharp.Formats.Jpeg/JpegDecoderCore.cs

@@ -5,6 +5,7 @@
 namespace ImageSharp.Formats
 {
     using System;
+    using System.Buffers;
     using System.IO;
     using System.Runtime.CompilerServices;
     using System.Threading.Tasks;
@@ -21,6 +22,11 @@ namespace ImageSharp.Formats
         /// </summary>
         public const int MaxComponents = 4;
 
+        /// <summary>
+        /// The maximum number of quantization tables
+        /// </summary>
+        public const int MaxTq = 3;
+
         // Complex value type field + mutable + available to other classes = the field MUST NOT be private :P
 #pragma warning disable SA1401 // FieldsMustBePrivate
         /// <summary>
@@ -35,9 +41,10 @@ namespace ImageSharp.Formats
 #pragma warning restore SA401
 
         /// <summary>
-        /// The maximum number of quantization tables
+        /// The <see cref="ArrayPool{T}"/> used to pool data in <see cref="DecodedBlocks"/>.
+        /// Should always clean arrays when returning!
         /// </summary>
-        private const int MaxTq = 3;
+        private static readonly ArrayPool<Block8x8F> BlockPool = ArrayPool<Block8x8F>.Create();
 
         /// <summary>
         /// The App14 marker color-space
@@ -406,6 +413,15 @@ namespace ImageSharp.Formats
                 this.HuffmanTrees[i].Dispose();
             }
 
+            for (int i = 0; i < this.DecodedBlocks.Length; i++)
+            {
+                Block8x8F[] blockArray = this.DecodedBlocks[i];
+                if (blockArray != null)
+                {
+                    BlockPool.Return(blockArray, true);
+                }
+            }
+
             this.ycbcrImage?.Dispose();
             this.Bytes.Dispose();
             this.grayImage.ReturnPooled();
@@ -1407,7 +1423,7 @@ namespace ImageSharp.Formats
             {
                 int size = this.TotalMCUCount * this.ComponentArray[i].HorizontalFactor
                            * this.ComponentArray[i].VerticalFactor;
-                this.DecodedBlocks[i] = new Block8x8F[size];
+                this.DecodedBlocks[i] = BlockPool.Rent(size);
             }
         }
 

tests/ImageSharp.Sandbox46/ImageSharp.Sandbox46.csproj

@@ -6,7 +6,7 @@
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
     <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
     <ProjectGuid>{96188137-5FA6-4924-AB6E-4EFF79C6E0BB}</ProjectGuid>
-    <OutputType>Library</OutputType>
+    <OutputType>Exe</OutputType>
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>ImageSharp</RootNamespace>
     <AssemblyName>ImageSharp.Sandbox46</AssemblyName>
@@ -34,6 +34,9 @@
     <WarningLevel>4</WarningLevel>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
+  <PropertyGroup>
+    <StartupObject>ImageSharp.Sandbox46.Program</StartupObject>
+  </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
     <Reference Include="System.Core" />
@@ -199,6 +202,7 @@
     <Compile Include="..\ImageSharp.Tests\TestUtilities\TestUtilityExtensions.cs">
       <Link>Tests\TestUtilities\TestUtilityExtensions.cs</Link>
     </Compile>
+    <Compile Include="Program.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>
@@ -208,6 +212,9 @@
   <ItemGroup>
     <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
   </ItemGroup>
+  <ItemGroup>
+    <Folder Include="Benchmarks\" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
     <PropertyGroup>

tests/ImageSharp.Sandbox46/Program.cs

@@ -0,0 +1,24 @@
+// <copyright file="Program.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Sandbox46
+{
+    using System;
+
+    public class Program
+    {
+        /// <summary>
+        /// The main entry point. Useful for executing benchmarks and performance unit tests manually,
+        /// when the IDE test runners lack some of the functionality. Eg.: it's not possible to run JetBrains memory profiler for unit tests.
+        /// </summary>
+        /// <param name="args">
+        /// The arguments to pass to the program.
+        /// </param>
+        public static void Main(string[] args)
+        {
+            Console.WriteLine("Hello.");
+        }
+    }
+}