Remove statics and threadstatic so that we can pass options around

Notepad.Extensions.Logging/IWindowFinder.cs

@@ -0,0 +1,7 @@
+namespace Notepad.Extensions.Logging
+{
+    interface IWindowFinder
+    {
+        WindowInfo FindNotepadWindow();
+    }
+}

Notepad.Extensions.Logging/NativeMethods.cs

@@ -22,10 +22,10 @@ namespace Notepad.Extensions.Logging
         [DllImport("User32.dll", CharSet = CharSet.Unicode, SetLastError = true)]
         public static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);
 
-        public delegate bool EnumWindowsDelegate(IntPtr hWnd, IntPtr lParam);
+        public delegate bool EnumWindowsDelegate(IntPtr hWnd, object lParam);
 
         [DllImport("user32.dll")]
-        public static extern bool EnumWindows(EnumWindowsDelegate lpEnumFunc, IntPtr lParam);
+        public static extern bool EnumWindows(EnumWindowsDelegate lpEnumFunc, object lParam);
 
         [DllImport("User32.dll")]
         public static extern int GetWindowText(IntPtr hWndParent, StringBuilder sb, int maxCount);

Notepad.Extensions.Logging/NotepadLogger.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Buffers;
-using System.ComponentModel;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Text;
@@ -12,13 +11,15 @@ namespace Notepad.Extensions.Logging
 {
     class NotepadLogger : ILogger
     {
-        public NotepadLogger(ObjectPool<StringBuilder> stringBuilderPool, string categoryName)
+        public NotepadLogger(ObjectPool<StringBuilder> stringBuilderPool, IWindowFinder windowFinder, string categoryName)
         {
-            this.stringBuilderPool = stringBuilderPool;
+            this.stringBuilderPool = stringBuilderPool ?? throw new ArgumentNullException(nameof(stringBuilderPool));
+            this.windowFinder = windowFinder ?? throw new ArgumentNullException(nameof(windowFinder));
             this.categoryName = categoryName;
         }
 
         readonly ObjectPool<StringBuilder> stringBuilderPool;
+        readonly IWindowFinder windowFinder;
         readonly string categoryName;
 
         public IDisposable BeginScope<TState>(TState state) => NullDisposable.Instance;
@@ -87,18 +88,18 @@ namespace Notepad.Extensions.Logging
             _ => throw new ArgumentOutOfRangeException(nameof(logLevel)),
         };
 
-        static void WriteToNotepad(string message)
+        void WriteToNotepad(string message)
         {
-            var (kind, hwnd) = WindowFinder.FindNotepadWindow();
+            var info = windowFinder.FindNotepadWindow();
-            switch (kind)
+            switch (info.Kind)
             {
                 case WindowKind.Notepad:
-                        SendMessage(hwnd, EM_REPLACESEL, (IntPtr)1, message);
+                        SendMessage(info.Handle, EM_REPLACESEL, (IntPtr)1, message);
                     break;
 
                 case WindowKind.NotepadPlusPlus:
                 {
-                    WriteToNotepadPlusPlus(hwnd, message);
+                    WriteToNotepadPlusPlus(info.Handle, message);
                     break;
                 }
             }

Notepad.Extensions.Logging/NotepadLoggerProvider.cs

@@ -10,13 +10,15 @@ namespace Notepad.Extensions.Logging
         {
             var poolProvider = new DefaultObjectPoolProvider();
             stringBuilderPool = poolProvider.CreateStringBuilderPool();
+            windowFinder = new WindowFinder();
         }
 
         public static ILoggerProvider Instance { get; } = new NotepadLoggerProvider();
 
         readonly ObjectPool<StringBuilder> stringBuilderPool;
+        readonly IWindowFinder windowFinder;
 
-        public ILogger CreateLogger(string categoryName) => new NotepadLogger(stringBuilderPool, categoryName);
+        public ILogger CreateLogger(string categoryName) => new NotepadLogger(stringBuilderPool, windowFinder, categoryName);
 
         public void Dispose()
         {

Notepad.Extensions.Logging/WindowEnumerationState.cs

@@ -0,0 +1,72 @@
+using System;
+using System.ComponentModel;
+using System.Text;
+using System.Text.RegularExpressions;
+
+namespace Notepad.Extensions.Logging
+{
+    class WindowEnumerationState
+    {
+        public WindowEnumerationState()
+        {
+            sb = new StringBuilder(capacity: 4096);
+        }
+
+        readonly StringBuilder sb;
+
+        public IntPtr Handle { get; private set; }
+        public WindowKind WindowKind { get; private set; }
+
+        public void Reset()
+        {
+            Handle = default;
+            WindowKind = default;
+            sb.Clear();
+        }
+
+        public bool ExamineWindow(IntPtr hWnd)
+        {
+            var result = NativeMethods.GetWindowText(hWnd, sb, sb.Capacity);
+            if (result < 0)
+            {
+                throw new Win32Exception(result);
+            }
+
+            Handle = hWnd;
+
+            if (sb.Length > 0 && sb[0] == '*')
+            {
+                // Notepad and Notepad++ both mark dirty documents by adding a leading asterisk to the window name.
+                sb.Remove(0, 1);
+            }
+
+            if (IsKnownNotepadWindow(sb.ToString()))
+            {
+                return false;
+            }
+            return true;
+        }
+
+        static Regex notepadPlusPlusRegex = new Regex(@"^new \d+ - Notepad\+\+$", RegexOptions.Compiled);
+
+        bool IsKnownNotepadWindow(string titleText)
+        {
+            switch (titleText)
+            {
+                case "Untitled - Notepad":
+                    WindowKind = WindowKind.Notepad;
+                    Handle = NativeMethods.FindWindowEx(Handle, IntPtr.Zero, "EDIT", null);
+                    return true;
+            }
+
+            if (notepadPlusPlusRegex.IsMatch(titleText))
+            {
+                WindowKind = WindowKind.NotepadPlusPlus;
+                Handle = NativeMethods.FindWindowEx(Handle, IntPtr.Zero, "Scintilla", null);
+                return true;
+            }
+
+            return false;
+        }
+    }
+}

Notepad.Extensions.Logging/WindowEnumerationStatePoolingPolicy.cs

@@ -0,0 +1,17 @@
+using Microsoft.Extensions.ObjectPool;
+
+namespace Notepad.Extensions.Logging
+{
+    class WindowEnumerationStatePoolingPolicy : IPooledObjectPolicy<WindowEnumerationState>
+    {
+        public static IPooledObjectPolicy<WindowEnumerationState> Instance { get; } = new WindowEnumerationStatePoolingPolicy();
+
+        public WindowEnumerationState Create() => new WindowEnumerationState();
+
+        public bool Return(WindowEnumerationState obj)
+        {
+            obj.Reset();
+            return true;
+        }
+    }
+}

Notepad.Extensions.Logging/WindowFinder.cs

@@ -1,89 +1,37 @@
 using System;
-using System.ComponentModel;
+using Microsoft.Extensions.ObjectPool;
-using System.Text;
-using System.Text.RegularExpressions;
 
 namespace Notepad.Extensions.Logging
 {
-    static class WindowFinder
+    class WindowFinder : IWindowFinder
     {
-        public static (WindowKind kind, IntPtr hwnd) FindNotepadWindow()
+        public WindowFinder()
         {
-            sb ??= new StringBuilder(4096);
+            statePool = new DefaultObjectPool<WindowEnumerationState>(WindowEnumerationStatePoolingPolicy.Instance);
+        }
 
+        readonly ObjectPool<WindowEnumerationState> statePool;
+
+        public WindowInfo FindNotepadWindow()
+        {
+            var stateObject = statePool.Get();
             try
             {
-                FindMainWindow();
+                NativeMethods.EnumWindows(enumWindowsDelegate, stateObject);
-                return (windowKind, handle);
+                return new WindowInfo(stateObject.WindowKind, stateObject.Handle);
             }
             finally
             {
-                handle = IntPtr.Zero;
+                statePool.Return(stateObject);
-                sb.Clear();
-                windowKind = WindowKind.Invalid;
             }
         }
 
-        static IntPtr FindMainWindow()
-        {
-            NativeMethods.EnumWindows(enumWindowsDelegate, IntPtr.Zero);
-            return handle;
-        }
-
         static NativeMethods.EnumWindowsDelegate enumWindowsDelegate = new NativeMethods.EnumWindowsDelegate(EnumWindowsCallback);
 
-        static bool EnumWindowsCallback(IntPtr hWnd, IntPtr lParam)
+        static bool EnumWindowsCallback(IntPtr hWnd, object lParam)
         {
-            var result = NativeMethods.GetWindowText(hWnd, sb, sb.Capacity);
+            var state = (WindowEnumerationState)lParam;
-            if (result < 0)
+            return state.ExamineWindow(hWnd);
-            {
-                throw new Win32Exception(result);
-            }
-
-            WindowFinder.handle = hWnd;
-
-            if (sb.Length > 0 && sb[0] == '*')
-            {
-                // Notepad and Notepad++ both mark dirty documents by adding a leading asterisk to the window name.
-                sb.Remove(0, 1);
-            }
-
-            if (IsKnownNotepadWindow(sb.ToString()))
-            {
-                return false;
-            }
-            return true;
-        }
-
-        [ThreadStatic]
-        static IntPtr handle;
-
-        [ThreadStatic]
-        static WindowKind windowKind;
-
-        [ThreadStatic]
-        static StringBuilder sb;
-
-        static Regex notepadPlusPlusRegex = new Regex(@"^new \d+ - Notepad\+\+$", RegexOptions.Compiled);
-
-        static bool IsKnownNotepadWindow(string titleText)
-        {
-            switch (titleText)
-            {
-                case "Untitled - Notepad":
-                    windowKind = WindowKind.Notepad;
-                    handle = NativeMethods.FindWindowEx(handle, IntPtr.Zero, "EDIT", null);
-                    return true;
-            }
-
-            if (notepadPlusPlusRegex.IsMatch(titleText))
-            {
-                windowKind = WindowKind.NotepadPlusPlus;
-                handle = NativeMethods.FindWindowEx(handle, IntPtr.Zero, "Scintilla", null);
-                return true;
-            }
-
-            return false;
         }
     }
 }

Notepad.Extensions.Logging/WindowInfo.cs

@@ -0,0 +1,16 @@
+using System;
+
+namespace Notepad.Extensions.Logging
+{
+    struct WindowInfo
+    {
+        public WindowInfo(WindowKind kind, IntPtr handle)
+        {
+            Kind = kind;
+            Handle = handle;
+        }
+
+        public WindowKind Kind { get; }
+        public IntPtr Handle { get; }
+    }
+}

Notepad.Extensions.Logging/WindowKind.cs

@@ -1,6 +1,6 @@
 namespace Notepad.Extensions.Logging
 {
-    public enum WindowKind
+    enum WindowKind
     {
         Invalid,
         Notepad,