Merge pull request #624 from Nihlus/cocoa-machport-leak-fix

Fix leaking Cocoa Machports on macOS

src/OpenTK/OpenTK.csproj

@@ -137,6 +137,7 @@
     <Compile Include="Platform\Egl\EglUnixContext.cs" />
     <Compile Include="Platform\Egl\EglWinContext.cs" />
     <Compile Include="Platform\Egl\EglAnglePlatformFactory.cs" />
+    <Compile Include="Platform\MacOS\Cocoa\NSAutoreleasePool.cs" />
     <Compile Include="Platform\MappedGamePadDriver.cs" />
     <Compile Include="Platform\Windows\Bindings\HidProtocol.cs" />
     <Compile Include="Platform\Windows\WinInputBase.cs" />

src/OpenTK/Platform/MacOS/Cocoa/NSAutoreleasePool.cs

@@ -0,0 +1,34 @@
+using System;
+
+namespace OpenTK.Platform.MacOS
+{
+    /// <summary>
+    /// The <see cref="NSAutoreleasePool"/> class is a wrapper around the native objective-C NSAutoreleasePool.
+    /// In particular, this construct mimics the usage of an @autorelease block and can be used in much the same way,
+    /// only with a C# using block instead.
+    /// </summary>
+    public sealed class NSAutoreleasePool : IDisposable
+    {
+        private readonly IntPtr _autoreleasePool;
+
+        /// <summary>
+        /// Allocates and initializes a new <see cref="NSAutoreleasePool"/>.
+        /// </summary>
+        public NSAutoreleasePool()
+        {
+            var uninitializedPool = Cocoa.SendIntPtr(Class.NSAutoreleasePool, Selector.Alloc);
+            _autoreleasePool = Cocoa.SendIntPtr(uninitializedPool, Selector.Init);
+        }
+
+        /// <summary>
+        /// Disposes of the <see cref="NSAutoreleasePool"/> instance, draining it.
+        /// </summary>
+        public void Dispose()
+        {
+            if (_autoreleasePool != IntPtr.Zero)
+            {
+                Cocoa.SendVoid(_autoreleasePool, Selector.Get("drain"));
+            }
+        }
+    }
+}

src/OpenTK/Platform/MacOS/CocoaContext.cs

@@ -345,12 +345,16 @@ namespace OpenTK
                 return;
             }
 
+            using (var pool = new NSAutoreleasePool())
+            {
                 if (IsCurrent)
                 {
                     Cocoa.SendVoid(NSOpenGLContext, Selector.Get("clearCurrentContext"));
                 }
+
                 Cocoa.SendVoid(Handle.Handle, Selector.Get("clearDrawable"));
                 Cocoa.SendVoid(Handle.Handle, Selector.Get("release"));
+            }
 
             Handle = ContextHandle.Zero;
 

src/OpenTK/Platform/MacOS/CocoaNativeWindow.cs

@@ -137,6 +137,7 @@ namespace OpenTK.Platform.MacOS
         }
 
         private CocoaWindowInfo windowInfo;
+
         private IntPtr windowClass;
         private IntPtr trackingArea;
         private IntPtr current_icon_handle;