Added ThreadUtility.EnterBackgroundProcessingMode.

Code derived from http://code.logos.com/blog/2008/10/using_background_processing_mode_from_c.html.

src/Logos.Utility/EnvironmentUtility.cs

@@ -0,0 +1,21 @@
+
+using System;
+
+namespace Logos.Utility
+{
+	/// <summary>
+	/// Provides utility methods for inspecting and using the current environment.
+	/// </summary>
+	public static class EnvironmentUtility
+	{
+		/// <summary>
+		/// Returns <c>true</c> if the current OS is Windows Vista (or Server 2008) or later.
+		/// </summary>
+		/// <returns><c>true</c> if the current OS is at least Windows Vista (or Server 2008).</returns>
+		public static bool IsWindowsVistaOrLater()
+		{
+			OperatingSystem os = Environment.OSVersion;
+			return os.Platform == PlatformID.Win32NT && os.Version >= new Version(6, 0);
+		}
+	}
+}

src/Logos.Utility/Logos.Utility.csproj

@@ -51,13 +51,17 @@
     <Compile Include="DictionaryUtility.cs" />
     <Compile Include="DisposableService.cs" />
     <Compile Include="DisposableUtility.cs" />
+    <Compile Include="EnvironmentUtility.cs" />
     <Compile Include="HashCodeUtility.cs" />
     <Compile Include="IO\WrappingStream.cs" />
+    <Compile Include="NativeMethods.cs" />
     <Compile Include="ObjectImpl.cs" />
     <Compile Include="ObjectUtility.cs" />
     <Compile Include="Ownership.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Scope.cs" />
+    <Compile Include="Threading\ThreadUtility.cs" />
+    <Compile Include="Win32.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 

src/Logos.Utility/NativeMethods.cs

@@ -0,0 +1,22 @@
+
+using System;
+using System.Runtime.InteropServices;
+using System.Security;
+
+namespace Logos.Utility
+{
+	[SuppressUnmanagedCodeSecurity]
+	internal static class SafeNativeMethods
+	{
+		[DllImport("Kernel32.dll", ExactSpelling = true)]
+		public static extern IntPtr GetCurrentThread();
+	}
+
+	[SuppressUnmanagedCodeSecurity]
+	internal static class UnsafeNativeMethods
+	{
+		[DllImport("Kernel32.dll", ExactSpelling = true)]
+		[return: MarshalAs(UnmanagedType.Bool)]
+		public static extern bool SetThreadPriority(IntPtr hThread, int nPriority);
+	}
+}

src/Logos.Utility/Threading/ThreadUtility.cs

@@ -0,0 +1,40 @@
+
+using System;
+using System.Security.Permissions;
+using System.Threading;
+
+namespace Logos.Utility.Threading
+{
+	/// <summary>
+	/// Utility methods for working with threads.
+	/// </summary>
+	public static class ThreadUtility
+	{
+		/// <summary>
+		/// Puts the current thread into background processing mode.
+		/// </summary>
+		/// <returns>A Scope that must be disposed to leave background processing mode.</returns>
+		/// <remarks>See <a href="http://code.logos.com/blog/2008/10/using_background_processing_mode_from_c.html">Using
+		/// "Background Processing Mode" from C#</a>.</remarks>
+		[SecurityPermission(SecurityAction.Demand, Flags = SecurityPermissionFlag.ControlThread)]
+		public static Scope EnterBackgroundProcessingMode()
+		{
+			Thread.BeginThreadAffinity();
+			IntPtr hThread = SafeNativeMethods.GetCurrentThread();
+			if (EnvironmentUtility.IsWindowsVistaOrLater() && UnsafeNativeMethods.SetThreadPriority(hThread,
+				Win32.THREAD_MODE_BACKGROUND_BEGIN))
+			{
+				// OS supports background processing; return Scope that exits this mode
+				return Scope.Create(() =>
+				{
+					UnsafeNativeMethods.SetThreadPriority(hThread, Win32.THREAD_MODE_BACKGROUND_END);
+					Thread.EndThreadAffinity();
+				});
+			}
+
+			// OS doesn't support background processing mode (or setting it failed)
+			Thread.EndThreadAffinity();
+			return Scope.Empty;
+		}
+	}
+}

src/Logos.Utility/Win32.cs

@@ -0,0 +1,9 @@
+
+namespace Logos.Utility
+{
+	internal static class Win32
+	{
+		public const int THREAD_MODE_BACKGROUND_BEGIN = 0x00010000;
+		public const int THREAD_MODE_BACKGROUND_END = 0x00020000;
+	}
+}