From 53bb11a2368de3b05e83f64d169cd6549f0d888a Mon Sep 17 00:00:00 2001
From: Anton Firszov <antonfir@gmail.com>
Date: Thu, 24 Oct 2019 02:21:08 +0200
Subject: [PATCH] expose ParallelExecutionSettings and ParallelHelper, fix
 MaxDegreeOfParallelism

---
 .../DrawImageProcessor{TPixelBg,TPixelFg}.cs  |  2 +-
 .../Drawing/FillProcessor{TPixel}.cs          |  7 ++--
 .../ParallelExecutionSettings.cs              | 38 ++++++++++++++++--
 .../ParallelUtils/ParallelHelper.cs           | 28 ++++++-------
 src/ImageSharp/ImageFrame{TPixel}.cs          |  2 +-
 .../BinaryThresholdProcessor{TPixel}.cs       |  2 +-
 .../Convolution/BokehBlurProcessor{TPixel}.cs |  2 +-
 .../Convolution2DProcessor{TPixel}.cs         |  2 +-
 .../Convolution2PassProcessor{TPixel}.cs      |  3 +-
 .../ConvolutionProcessor{TPixel}.cs           |  3 +-
 .../EdgeDetectorCompassProcessor{TPixel}.cs   |  2 +-
 .../Effects/OilPaintingProcessor{TPixel}.cs   |  2 +-
 .../Filters/FilterProcessor{TPixel}.cs        |  2 +-
 ...lHistogramEqualizationProcessor{TPixel}.cs |  2 +-
 .../BackgroundColorProcessor{TPixel}.cs       |  2 +-
 .../Overlays/GlowProcessor{TPixel}.cs         |  2 +-
 .../Overlays/VignetteProcessor{TPixel}.cs     |  2 +-
 .../AffineTransformProcessor{TPixel}.cs       |  2 +-
 .../Transforms/CropProcessor{TPixel}.cs       |  8 ++--
 .../Transforms/FlipProcessor{TPixel}.cs       |  2 +-
 .../ProjectiveTransformProcessor{TPixel}.cs   |  2 +-
 .../Resize/ResizeProcessor{TPixel}.cs         |  2 +-
 .../Transforms/RotateProcessor{TPixel}.cs     |  2 +-
 tests/ImageSharp.Tests/ConfigurationTests.cs  | 26 +++++++++---
 .../Helpers/ParallelExecutionSettingsTests.cs | 40 +++++++++++++++++++
 .../Helpers/ParallelHelperTests.cs            |  2 +-
 .../TestUtilities/TestImageExtensions.cs      |  2 +-
 27 files changed, 138 insertions(+), 53 deletions(-)
 rename src/ImageSharp/{Common => Advanced}/ParallelUtils/ParallelExecutionSettings.cs (55%)
 rename src/ImageSharp/{Common => Advanced}/ParallelUtils/ParallelHelper.cs (84%)
 create mode 100644 tests/ImageSharp.Tests/Helpers/ParallelExecutionSettingsTests.cs

diff --git a/src/ImageSharp.Drawing/Processing/Processors/Drawing/DrawImageProcessor{TPixelBg,TPixelFg}.cs b/src/ImageSharp.Drawing/Processing/Processors/Drawing/DrawImageProcessor{TPixelBg,TPixelFg}.cs
index 76082136c..eab6b2f4a 100644
--- a/src/ImageSharp.Drawing/Processing/Processors/Drawing/DrawImageProcessor{TPixelBg,TPixelFg}.cs
+++ b/src/ImageSharp.Drawing/Processing/Processors/Drawing/DrawImageProcessor{TPixelBg,TPixelFg}.cs
@@ -4,7 +4,7 @@
 using System;
 
 using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.ParallelUtils;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
diff --git a/src/ImageSharp.Drawing/Processing/Processors/Drawing/FillProcessor{TPixel}.cs b/src/ImageSharp.Drawing/Processing/Processors/Drawing/FillProcessor{TPixel}.cs
index 012bda4e8..4e052818d 100644
--- a/src/ImageSharp.Drawing/Processing/Processors/Drawing/FillProcessor{TPixel}.cs
+++ b/src/ImageSharp.Drawing/Processing/Processors/Drawing/FillProcessor{TPixel}.cs
@@ -5,8 +5,8 @@ using System;
 using System.Buffers;
 
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
@@ -53,9 +53,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Drawing
             // If there's no reason for blending, then avoid it.
             if (this.IsSolidBrushWithoutBlending(out SolidBrush solidBrush))
             {
-                ParallelExecutionSettings parallelSettings = configuration.GetParallelSettings().MultiplyMinimumPixelsPerTask(4);
+                ParallelExecutionSettings parallelSettings = ParallelExecutionSettings.FromConfiguration(configuration)
+                    .MultiplyMinimumPixelsPerTask(4);
 
-                TPixel colorPixel = solidBrush.Color.ToPixel<TPixel>();
+                var colorPixel = solidBrush.Color.ToPixel<TPixel>();
 
                 ParallelHelper.IterateRows(
                     workingRect,
diff --git a/src/ImageSharp/Common/ParallelUtils/ParallelExecutionSettings.cs b/src/ImageSharp/Advanced/ParallelUtils/ParallelExecutionSettings.cs
similarity index 55%
rename from src/ImageSharp/Common/ParallelUtils/ParallelExecutionSettings.cs
rename to src/ImageSharp/Advanced/ParallelUtils/ParallelExecutionSettings.cs
index 40163bc78..431656ef9 100644
--- a/src/ImageSharp/Common/ParallelUtils/ParallelExecutionSettings.cs
+++ b/src/ImageSharp/Advanced/ParallelUtils/ParallelExecutionSettings.cs
@@ -1,16 +1,17 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using System.Threading.Tasks;
 
 using SixLabors.Memory;
 
-namespace SixLabors.ImageSharp.ParallelUtils
+namespace SixLabors.ImageSharp.Advanced.ParallelUtils
 {
     /// <summary>
     /// Defines execution settings for methods in <see cref="ParallelHelper"/>.
     /// </summary>
-    internal readonly struct ParallelExecutionSettings
+    public readonly struct ParallelExecutionSettings
     {
         /// <summary>
         /// Default value for <see cref="MinimumPixelsProcessedPerTask"/>.
@@ -20,11 +21,24 @@ namespace SixLabors.ImageSharp.ParallelUtils
         /// <summary>
         /// Initializes a new instance of the <see cref="ParallelExecutionSettings"/> struct.
         /// </summary>
+        /// <param name="maxDegreeOfParallelism">The value used for initializing <see cref="ParallelOptions.MaxDegreeOfParallelism"/> when using TPL.</param>
+        /// <param name="minimumPixelsProcessedPerTask">The value for <see cref="MinimumPixelsProcessedPerTask"/>.</param>
+        /// <param name="memoryAllocator">The <see cref="MemoryAllocator"/>.</param>
         public ParallelExecutionSettings(
             int maxDegreeOfParallelism,
             int minimumPixelsProcessedPerTask,
             MemoryAllocator memoryAllocator)
         {
+            // Shall be compatible with ParallelOptions.MaxDegreeOfParallelism:
+            // https://docs.microsoft.com/en-us/dotnet/api/system.threading.tasks.paralleloptions.maxdegreeofparallelism
+            if (maxDegreeOfParallelism == 0 || maxDegreeOfParallelism < -1)
+            {
+                throw new ArgumentOutOfRangeException(nameof(maxDegreeOfParallelism));
+            }
+
+            Guard.MustBeGreaterThan(minimumPixelsProcessedPerTask, 0, nameof(minimumPixelsProcessedPerTask));
+            Guard.NotNull(memoryAllocator, nameof(memoryAllocator));
+
             this.MaxDegreeOfParallelism = maxDegreeOfParallelism;
             this.MinimumPixelsProcessedPerTask = minimumPixelsProcessedPerTask;
             this.MemoryAllocator = memoryAllocator;
@@ -33,13 +47,15 @@ namespace SixLabors.ImageSharp.ParallelUtils
         /// <summary>
         /// Initializes a new instance of the <see cref="ParallelExecutionSettings"/> struct.
         /// </summary>
+        /// <param name="maxDegreeOfParallelism">The value used for initializing <see cref="ParallelOptions.MaxDegreeOfParallelism"/> when using TPL.</param>
+        /// <param name="memoryAllocator">The <see cref="MemoryAllocator"/>.</param>
         public ParallelExecutionSettings(int maxDegreeOfParallelism, MemoryAllocator memoryAllocator)
             : this(maxDegreeOfParallelism, DefaultMinimumPixelsProcessedPerTask, memoryAllocator)
         {
         }
 
         /// <summary>
-        /// Gets the MemoryAllocator
+        /// Gets the <see cref="MemoryAllocator"/>.
         /// </summary>
         public MemoryAllocator MemoryAllocator { get; }
 
@@ -60,12 +76,26 @@ namespace SixLabors.ImageSharp.ParallelUtils
         /// Creates a new instance of <see cref="ParallelExecutionSettings"/>
         /// having <see cref="MinimumPixelsProcessedPerTask"/> multiplied by <paramref name="multiplier"/>
         /// </summary>
+        /// <param name="multiplier">The value to multiply <see cref="MinimumPixelsProcessedPerTask"/> with.</param>
+        /// <returns>The modified <see cref="ParallelExecutionSettings"/>.</returns>
         public ParallelExecutionSettings MultiplyMinimumPixelsPerTask(int multiplier)
         {
+            Guard.MustBeGreaterThan(multiplier, 0, nameof(multiplier));
+
             return new ParallelExecutionSettings(
                 this.MaxDegreeOfParallelism,
                 this.MinimumPixelsProcessedPerTask * multiplier,
                 this.MemoryAllocator);
         }
+
+        /// <summary>
+        /// Get the default <see cref="SixLabors.ImageSharp.Advanced.ParallelUtils.ParallelExecutionSettings"/> for a <see cref="SixLabors.ImageSharp.Configuration"/>
+        /// </summary>
+        /// <param name="configuration">The <see cref="Configuration"/>.</param>
+        /// <returns>The <see cref="ParallelExecutionSettings"/>.</returns>
+        public static ParallelExecutionSettings FromConfiguration(Configuration configuration)
+        {
+            return new ParallelExecutionSettings(configuration.MaxDegreeOfParallelism, configuration.MemoryAllocator);
+        }
     }
-}
\ No newline at end of file
+}
diff --git a/src/ImageSharp/Common/ParallelUtils/ParallelHelper.cs b/src/ImageSharp/Advanced/ParallelUtils/ParallelHelper.cs
similarity index 84%
rename from src/ImageSharp/Common/ParallelUtils/ParallelHelper.cs
rename to src/ImageSharp/Advanced/ParallelUtils/ParallelHelper.cs
index 170489c7a..c56337bff 100644
--- a/src/ImageSharp/Common/ParallelUtils/ParallelHelper.cs
+++ b/src/ImageSharp/Advanced/ParallelUtils/ParallelHelper.cs
@@ -10,12 +10,13 @@ using SixLabors.ImageSharp.Memory;
 using SixLabors.Memory;
 using SixLabors.Primitives;
 
-namespace SixLabors.ImageSharp.ParallelUtils
+namespace SixLabors.ImageSharp.Advanced.ParallelUtils
 {
     /// <summary>
     /// Utility methods for batched processing of pixel row intervals.
-    /// Parallel execution is optimized for image processing.
-    /// Use this instead of direct <see cref="Parallel"/> calls!
+    /// Parallel execution is optimized for image processing based on values defined
+    /// <see cref="ParallelExecutionSettings"/> or <see cref="Configuration"/>.
+    /// Using this class is preferred over direct usage of <see cref="Parallel"/> utility methods.
     /// </summary>
     public static class ParallelHelper
     {
@@ -27,7 +28,7 @@ namespace SixLabors.ImageSharp.ParallelUtils
         /// <param name="body">The method body defining the iteration logic on a single <see cref="RowInterval"/>.</param>
         public static void IterateRows(Rectangle rectangle, Configuration configuration, Action<RowInterval> body)
         {
-            ParallelExecutionSettings parallelSettings = configuration.GetParallelSettings();
+            ParallelExecutionSettings parallelSettings = ParallelExecutionSettings.FromConfiguration(configuration);
 
             IterateRows(rectangle, parallelSettings, body);
         }
@@ -35,14 +36,19 @@ namespace SixLabors.ImageSharp.ParallelUtils
         /// <summary>
         /// Iterate through the rows of a rectangle in optimized batches defined by <see cref="RowInterval"/>-s.
         /// </summary>
-        internal static void IterateRows(
+        /// <param name="rectangle">The <see cref="Rectangle"/>.</param>
+        /// <param name="parallelSettings">The <see cref="ParallelExecutionSettings"/>.</param>
+        /// <param name="body">The method body defining the iteration logic on a single <see cref="RowInterval"/>.</param>
+        public static void IterateRows(
             Rectangle rectangle,
             in ParallelExecutionSettings parallelSettings,
             Action<RowInterval> body)
         {
             ValidateRectangle(rectangle);
 
-            int maxSteps = DivideCeil(rectangle.Width * rectangle.Height, parallelSettings.MinimumPixelsProcessedPerTask);
+            int maxSteps = DivideCeil(
+                rectangle.Width * rectangle.Height,
+                parallelSettings.MinimumPixelsProcessedPerTask);
 
             int numOfSteps = Math.Min(parallelSettings.MaxDegreeOfParallelism, maxSteps);
 
@@ -72,14 +78,6 @@ namespace SixLabors.ImageSharp.ParallelUtils
                     });
         }
 
-        /// <summary>
-        /// Get the default <see cref="ParallelExecutionSettings"/> for a <see cref="Configuration"/>
-        /// </summary>
-        internal static ParallelExecutionSettings GetParallelSettings(this Configuration configuration)
-        {
-            return new ParallelExecutionSettings(configuration.MaxDegreeOfParallelism, configuration.MemoryAllocator);
-        }
-
         /// <summary>
         /// Iterate through the rows of a rectangle in optimized batches defined by <see cref="RowInterval"/>-s
         /// instantiating a temporary buffer for each <paramref name="body"/> invocation.
@@ -142,7 +140,7 @@ namespace SixLabors.ImageSharp.ParallelUtils
             Action<RowInterval, Memory<T>> body)
             where T : unmanaged
         {
-            IterateRowsWithTempBuffer(rectangle, configuration.GetParallelSettings(), body);
+            IterateRowsWithTempBuffer(rectangle, ParallelExecutionSettings.FromConfiguration(configuration), body);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
diff --git a/src/ImageSharp/ImageFrame{TPixel}.cs b/src/ImageSharp/ImageFrame{TPixel}.cs
index 4f0e7c1ce..64f37a340 100644
--- a/src/ImageSharp/ImageFrame{TPixel}.cs
+++ b/src/ImageSharp/ImageFrame{TPixel}.cs
@@ -6,9 +6,9 @@ using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.Metadata;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
 using SixLabors.Primitives;
diff --git a/src/ImageSharp/Processing/Processors/Binarization/BinaryThresholdProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Binarization/BinaryThresholdProcessor{TPixel}.cs
index 7234955ed..7208fc3cd 100644
--- a/src/ImageSharp/Processing/Processors/Binarization/BinaryThresholdProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Binarization/BinaryThresholdProcessor{TPixel}.cs
@@ -4,7 +4,7 @@
 using System;
 
 using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.ParallelUtils;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
diff --git a/src/ImageSharp/Processing/Processors/Convolution/BokehBlurProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Convolution/BokehBlurProcessor{TPixel}.cs
index 9339c8fe4..f8fb3f796 100644
--- a/src/ImageSharp/Processing/Processors/Convolution/BokehBlurProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Convolution/BokehBlurProcessor{TPixel}.cs
@@ -8,8 +8,8 @@ using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
 using SixLabors.ImageSharp.Processing.Processors.Convolution.Parameters;
diff --git a/src/ImageSharp/Processing/Processors/Convolution/Convolution2DProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Convolution/Convolution2DProcessor{TPixel}.cs
index b38d87cd4..4419f064e 100644
--- a/src/ImageSharp/Processing/Processors/Convolution/Convolution2DProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Convolution/Convolution2DProcessor{TPixel}.cs
@@ -5,8 +5,8 @@ using System;
 using System.Numerics;
 using System.Runtime.InteropServices;
 
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
 using SixLabors.Primitives;
diff --git a/src/ImageSharp/Processing/Processors/Convolution/Convolution2PassProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Convolution/Convolution2PassProcessor{TPixel}.cs
index a523f7c22..9fad8b5b7 100644
--- a/src/ImageSharp/Processing/Processors/Convolution/Convolution2PassProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Convolution/Convolution2PassProcessor{TPixel}.cs
@@ -4,8 +4,9 @@
 using System;
 using System.Numerics;
 using System.Runtime.InteropServices;
+
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
 using SixLabors.Primitives;
diff --git a/src/ImageSharp/Processing/Processors/Convolution/ConvolutionProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Convolution/ConvolutionProcessor{TPixel}.cs
index 5bdec738d..f657e131d 100644
--- a/src/ImageSharp/Processing/Processors/Convolution/ConvolutionProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Convolution/ConvolutionProcessor{TPixel}.cs
@@ -4,8 +4,9 @@
 using System;
 using System.Numerics;
 using System.Runtime.InteropServices;
+
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
 using SixLabors.Primitives;
diff --git a/src/ImageSharp/Processing/Processors/Convolution/EdgeDetectorCompassProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Convolution/EdgeDetectorCompassProcessor{TPixel}.cs
index dc9974c61..4fa87bc98 100644
--- a/src/ImageSharp/Processing/Processors/Convolution/EdgeDetectorCompassProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Convolution/EdgeDetectorCompassProcessor{TPixel}.cs
@@ -6,8 +6,8 @@ using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
 using SixLabors.ImageSharp.Processing.Processors.Filters;
diff --git a/src/ImageSharp/Processing/Processors/Effects/OilPaintingProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Effects/OilPaintingProcessor{TPixel}.cs
index ea7ba7409..4cac6b0f6 100644
--- a/src/ImageSharp/Processing/Processors/Effects/OilPaintingProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Effects/OilPaintingProcessor{TPixel}.cs
@@ -5,8 +5,8 @@ using System;
 using System.Numerics;
 
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
diff --git a/src/ImageSharp/Processing/Processors/Filters/FilterProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Filters/FilterProcessor{TPixel}.cs
index 5fa233d18..731cd2a05 100644
--- a/src/ImageSharp/Processing/Processors/Filters/FilterProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Filters/FilterProcessor{TPixel}.cs
@@ -4,7 +4,7 @@
 using System;
 using System.Numerics;
 using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.ParallelUtils;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Primitives;
 using SixLabors.Primitives;
diff --git a/src/ImageSharp/Processing/Processors/Normalization/GlobalHistogramEqualizationProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Normalization/GlobalHistogramEqualizationProcessor{TPixel}.cs
index 8aaa5403d..f8cd5620a 100644
--- a/src/ImageSharp/Processing/Processors/Normalization/GlobalHistogramEqualizationProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Normalization/GlobalHistogramEqualizationProcessor{TPixel}.cs
@@ -8,8 +8,8 @@ using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
 using SixLabors.Primitives;
diff --git a/src/ImageSharp/Processing/Processors/Overlays/BackgroundColorProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Overlays/BackgroundColorProcessor{TPixel}.cs
index 2459b4706..7e3d2fdc5 100644
--- a/src/ImageSharp/Processing/Processors/Overlays/BackgroundColorProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Overlays/BackgroundColorProcessor{TPixel}.cs
@@ -5,8 +5,8 @@ using System;
 using System.Buffers;
 
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
diff --git a/src/ImageSharp/Processing/Processors/Overlays/GlowProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Overlays/GlowProcessor{TPixel}.cs
index 756e8647b..4082d9a65 100644
--- a/src/ImageSharp/Processing/Processors/Overlays/GlowProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Overlays/GlowProcessor{TPixel}.cs
@@ -6,8 +6,8 @@ using System.Buffers;
 using System.Numerics;
 
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
diff --git a/src/ImageSharp/Processing/Processors/Overlays/VignetteProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Overlays/VignetteProcessor{TPixel}.cs
index 8569410d2..c27a634f3 100644
--- a/src/ImageSharp/Processing/Processors/Overlays/VignetteProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Overlays/VignetteProcessor{TPixel}.cs
@@ -6,8 +6,8 @@ using System.Buffers;
 using System.Numerics;
 
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
diff --git a/src/ImageSharp/Processing/Processors/Transforms/AffineTransformProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Transforms/AffineTransformProcessor{TPixel}.cs
index 97b8b009b..e693de8f6 100644
--- a/src/ImageSharp/Processing/Processors/Transforms/AffineTransformProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Transforms/AffineTransformProcessor{TPixel}.cs
@@ -4,7 +4,7 @@
 using System;
 using System.Numerics;
 using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.ParallelUtils;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
diff --git a/src/ImageSharp/Processing/Processors/Transforms/CropProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Transforms/CropProcessor{TPixel}.cs
index 1bbdd0a16..2cc4a3867 100644
--- a/src/ImageSharp/Processing/Processors/Transforms/CropProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Transforms/CropProcessor{TPixel}.cs
@@ -3,7 +3,7 @@
 
 using System;
 using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.ParallelUtils;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
@@ -47,10 +47,8 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             Rectangle bounds = this.cropRectangle;
 
             // Copying is cheap, we should process more pixels per task:
-            ParallelExecutionSettings parallelSettings
-                = this.Configuration
-                      .GetParallelSettings()
-                      .MultiplyMinimumPixelsPerTask(4);
+            ParallelExecutionSettings parallelSettings = ParallelExecutionSettings.FromConfiguration(this.Configuration)
+                .MultiplyMinimumPixelsPerTask(4);
 
             ParallelHelper.IterateRows(
                 bounds,
diff --git a/src/ImageSharp/Processing/Processors/Transforms/FlipProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Transforms/FlipProcessor{TPixel}.cs
index 9374af476..9ee8d0922 100644
--- a/src/ImageSharp/Processing/Processors/Transforms/FlipProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Transforms/FlipProcessor{TPixel}.cs
@@ -5,7 +5,7 @@ using System;
 using System.Buffers;
 
 using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.ParallelUtils;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
diff --git a/src/ImageSharp/Processing/Processors/Transforms/ProjectiveTransformProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Transforms/ProjectiveTransformProcessor{TPixel}.cs
index 68bfd817e..c6212a7d3 100644
--- a/src/ImageSharp/Processing/Processors/Transforms/ProjectiveTransformProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Transforms/ProjectiveTransformProcessor{TPixel}.cs
@@ -5,7 +5,7 @@ using System;
 using System.Numerics;
 
 using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.ParallelUtils;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
diff --git a/src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeProcessor{TPixel}.cs
index 78e471ad6..3b508032a 100644
--- a/src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeProcessor{TPixel}.cs
@@ -4,8 +4,8 @@
 using System;
 
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
 using SixLabors.Primitives;
diff --git a/src/ImageSharp/Processing/Processors/Transforms/RotateProcessor{TPixel}.cs b/src/ImageSharp/Processing/Processors/Transforms/RotateProcessor{TPixel}.cs
index 1ed4c362c..92776b7db 100644
--- a/src/ImageSharp/Processing/Processors/Transforms/RotateProcessor{TPixel}.cs
+++ b/src/ImageSharp/Processing/Processors/Transforms/RotateProcessor{TPixel}.cs
@@ -4,8 +4,8 @@
 using System;
 
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Metadata.Profiles.Exif;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Primitives;
 
diff --git a/tests/ImageSharp.Tests/ConfigurationTests.cs b/tests/ImageSharp.Tests/ConfigurationTests.cs
index 6f68d0428..a0e552aeb 100644
--- a/tests/ImageSharp.Tests/ConfigurationTests.cs
+++ b/tests/ImageSharp.Tests/ConfigurationTests.cs
@@ -61,12 +61,28 @@ namespace SixLabors.ImageSharp.Tests
         }
 
         [Theory]
-        [InlineData(0)]
-        [InlineData(-42)]
-        public void Set_MaxDegreeOfParallelism_ToNonPositiveValue_Throws(int value)
+        [InlineData(-3, true)]
+        [InlineData(-2, true)]
+        [InlineData(-1, false)]
+        [InlineData(0, true)]
+        [InlineData(1, false)]
+        [InlineData(5, false)]
+        public void MaxDegreeOfParallelism_CompatibleWith_ParallelOptions(int maxDegreeOfParallelism, bool throws)
         {
             var cfg = new Configuration();
-            Assert.Throws<ArgumentOutOfRangeException>(() => cfg.MaxDegreeOfParallelism = value);
+            if (throws)
+            {
+                Assert.Throws<ArgumentOutOfRangeException>(
+                    () =>
+                    {
+                        cfg.MaxDegreeOfParallelism = maxDegreeOfParallelism;
+                    });
+            }
+            else
+            {
+                cfg.MaxDegreeOfParallelism = maxDegreeOfParallelism;
+                Assert.Equal(maxDegreeOfParallelism, cfg.MaxDegreeOfParallelism);
+            }
         }
 
 
@@ -117,4 +133,4 @@ namespace SixLabors.ImageSharp.Tests
             Assert.True(config.WorkingBufferSizeHintInBytes  > 1024);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/tests/ImageSharp.Tests/Helpers/ParallelExecutionSettingsTests.cs b/tests/ImageSharp.Tests/Helpers/ParallelExecutionSettingsTests.cs
new file mode 100644
index 000000000..3cfce6b8e
--- /dev/null
+++ b/tests/ImageSharp.Tests/Helpers/ParallelExecutionSettingsTests.cs
@@ -0,0 +1,40 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Helpers
+{
+    public class ParallelExecutionSettingsTests
+    {
+        [Theory]
+        [InlineData(-3, true)]
+        [InlineData(-2, true)]
+        [InlineData(-1, false)]
+        [InlineData(0, true)]
+        [InlineData(1, false)]
+        [InlineData(5, false)]
+        public void Constructor_MaxDegreeOfParallelism_CompatibleWith_ParallelOptions(int maxDegreeOfParallelism, bool throws)
+        {
+            if (throws)
+            {
+                Assert.Throws<ArgumentOutOfRangeException>(
+                    () =>
+                    {
+                        _ = new ParallelExecutionSettings(
+                            maxDegreeOfParallelism,
+                            Configuration.Default.MemoryAllocator);
+                    });
+            }
+            else
+            {
+                var parallelSettings = new ParallelExecutionSettings(
+                    maxDegreeOfParallelism,
+                    Configuration.Default.MemoryAllocator);
+                Assert.Equal(maxDegreeOfParallelism, parallelSettings.MaxDegreeOfParallelism);
+            }
+        }
+    }
+}
diff --git a/tests/ImageSharp.Tests/Helpers/ParallelHelperTests.cs b/tests/ImageSharp.Tests/Helpers/ParallelHelperTests.cs
index 403ff1e40..4b5c87c7f 100644
--- a/tests/ImageSharp.Tests/Helpers/ParallelHelperTests.cs
+++ b/tests/ImageSharp.Tests/Helpers/ParallelHelperTests.cs
@@ -7,8 +7,8 @@ using System.Linq;
 using System.Numerics;
 using System.Threading;
 
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.Memory;
 using SixLabors.Primitives;
diff --git a/tests/ImageSharp.Tests/TestUtilities/TestImageExtensions.cs b/tests/ImageSharp.Tests/TestUtilities/TestImageExtensions.cs
index 95f7f81fd..9da39fbe4 100644
--- a/tests/ImageSharp.Tests/TestUtilities/TestImageExtensions.cs
+++ b/tests/ImageSharp.Tests/TestUtilities/TestImageExtensions.cs
@@ -7,9 +7,9 @@ using System.IO;
 using System.Numerics;
 
 using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Advanced.ParallelUtils;
 using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Memory;
-using SixLabors.ImageSharp.ParallelUtils;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 using SixLabors.ImageSharp.Processing.Processors;