Added the CollectGarbage method

Author: Taritsyn

src/MsieJavaScriptEngine/ActiveScript/ActiveScriptJsEngineBase.cs

@@ -36,16 +36,26 @@ internal abstract class ActiveScriptJsEngineBase : IInnerJsEngine, IActiveScript
 		/// </summary>
 		private IntPtr _pActiveScript;
 
+		/// <summary>
+		/// Pointer to an instance of garbage collector
+		/// </summary>
+		private IntPtr _pActiveScriptGarbageCollector;
+
 		/// <summary>
 		/// Instance of native JavaScript engine
 		/// </summary>
 		private IActiveScript _activeScript;
 
 		/// <summary>
-		/// Instance of ActiveScriptParseWrapper
+		/// Instance of <see cref="IActiveScriptParseWrapper"/>
 		/// </summary>
 		private IActiveScriptParseWrapper _activeScriptParse;
 
+		/// <summary>
+		/// Instance of <see cref="IActiveScriptGarbageCollector"/>
+		/// </summary>
+		private IActiveScriptGarbageCollector _activeScriptGarbageCollector;
+
 		/// <summary>
 		/// Instance of script dispatch
 		/// </summary>
@@ -134,6 +144,9 @@ protected ActiveScriptJsEngineBase(string clsid, JsEngineMode engineMode, string
 			_activeScriptParse = new ActiveScriptParseWrapper(_pActiveScript, _activeScript);
 			_activeScriptParse.InitNew();
 
+			_pActiveScriptGarbageCollector = ComHelpers.QueryInterfaceNoThrow<IActiveScriptGarbageCollector>(_pActiveScript);
+			_activeScriptGarbageCollector = _activeScript as IActiveScriptGarbageCollector;
+
 			_activeScript.SetScriptSite(this);
 			_activeScript.SetScriptState(ScriptState.Started);
 
@@ -481,6 +494,18 @@ private void EmbedHostItem(string itemName, object value)
 			});
 		}
 
+		/// <summary>
+		/// Starts a garbage collection
+		/// </summary>
+		/// <param name="type">The type of garbage collection</param>
+		private void InnerCollectGarbage(ScriptGCType type)
+		{
+			if (_activeScriptGarbageCollector != null)
+			{
+				_activeScriptGarbageCollector.CollectGarbage(type);
+			}
+		}
+
 		/// <summary>
 		/// Loads a resources
 		/// </summary>
@@ -541,6 +566,9 @@ private void Dispose(bool disposing)
 						_dispatch = null;
 					}
 
+					_activeScriptGarbageCollector = null;
+					ComHelpers.ReleaseAndEmpty(ref _pActiveScriptGarbageCollector);
+
 					if (_activeScriptParse != null)
 					{
 						_activeScriptParse.Dispose();
@@ -550,6 +578,7 @@ private void Dispose(bool disposing)
 					if (_activeScript != null)
 					{
 						_activeScript.Close();
+						Marshal.FinalReleaseComObject(_activeScript);
 						_activeScript = null;
 					}
 
@@ -796,6 +825,11 @@ public void EmbedHostType(string itemName, Type type)
 			EmbedHostItem(itemName, typeValue);
 		}
 
+		public void CollectGarbage()
+		{
+			InvokeScript(() => InnerCollectGarbage(ScriptGCType.Exhaustive));
+		}
+
 		#endregion
 
 		#region IDisposable implementation

src/MsieJavaScriptEngine/ActiveScript/IActiveScriptGarbageCollector.cs

@@ -0,0 +1,22 @@
+#if !NETSTANDARD1_3
+using System.Runtime.InteropServices;
+
+namespace MsieJavaScriptEngine.ActiveScript
+{
+	/// <summary>
+	/// Provides a method to start garbage collection.
+	/// This interface should be implemented by Active Script engines that want to clean up their resources.
+	/// </summary>
+	[ComImport]
+	[Guid("6aa2c4a0-2b53-11d4-a2a0-00104bd35090")]
+	[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
+	internal interface IActiveScriptGarbageCollector
+	{
+		/// <summary>
+		/// Starts a garbage collection
+		/// </summary>
+		/// <param name="type">The type of garbage collection</param>
+		void CollectGarbage([In] ScriptGCType type);
+	}
+}
+#endif

src/MsieJavaScriptEngine/ActiveScript/ScriptGCType.cs

@@ -0,0 +1,20 @@
+#if !NETSTANDARD1_3
+namespace MsieJavaScriptEngine.ActiveScript
+{
+	/// <summary>
+	/// The type of garbage collection
+	/// </summary>
+	internal enum ScriptGCType
+	{
+		/// <summary>
+		/// Do normal garbage collection
+		/// </summary>
+		Normal = 0,
+
+		/// <summary>
+		/// Do exhaustive garbage collection
+		/// </summary>
+		Exhaustive = 1
+	}
+}
+#endif

src/MsieJavaScriptEngine/Helpers/ComHelpers.cs

@@ -62,6 +62,15 @@ public static IntPtr QueryInterface<T>(IntPtr pUnknown)
 			return pInterface;
 		}
 
+		public static IntPtr QueryInterfaceNoThrow<T>(IntPtr pUnknown)
+		{
+			IntPtr pInterface;
+			Guid iid = typeof(T).GetTypeInfo().GUID;
+			int result = Marshal.QueryInterface(pUnknown, ref iid, out pInterface);
+
+			return result == HResult.S_OK ? pInterface : IntPtr.Zero;
+		}
+
 		public static void ReleaseAndEmpty(ref IntPtr pUnk)
 		{
 			if (pUnk != IntPtr.Zero)
@@ -126,6 +135,9 @@ public static class HResult
 			// ReSharper disable InconsistentNaming
 			public const int SEVERITY_SUCCESS = 0;
 			public const int SEVERITY_ERROR = 1;
+
+			public const int S_OK = 0;
+			public const int S_FALSE = 1;
 			// ReSharper restore InconsistentNaming
 
 			public static void Check(uint result)

src/MsieJavaScriptEngine/IInnerJsEngine.cs

@@ -79,5 +79,10 @@ internal interface IInnerJsEngine : IDisposable
 		/// methods are bound to the type's static members.
 		/// </remarks>
 		void EmbedHostType(string itemName, Type type);
+
+		/// <summary>
+		/// Performs a full garbage collection
+		/// </summary>
+		void CollectGarbage();
 	}
 }

src/MsieJavaScriptEngine/JsRt/ChakraJsRtJsEngineBase.cs

@@ -129,6 +129,8 @@ private void ExternalObjectFinalizeCallback(IntPtr data)
 
 		public abstract void EmbedHostType(string itemName, Type type);
 
+		public abstract void CollectGarbage();
+
 		#endregion
 
 		#region IDisposable implementation

src/MsieJavaScriptEngine/JsRt/Edge/ChakraEdgeJsRtJsEngine.cs

@@ -1037,6 +1037,14 @@ public override void EmbedHostType(string itemName, Type type)
 			});
 		}
 
+		public override void CollectGarbage()
+		{
+			lock (_executionSynchronizer)
+			{
+				_jsRuntime.CollectGarbage();
+			}
+		}
+
 		#endregion
 
 		#region IDisposable implementation

src/MsieJavaScriptEngine/JsRt/Ie/ChakraIeJsRtJsEngine.cs

@@ -1076,6 +1076,14 @@ public override void EmbedHostType(string itemName, Type type)
 			});
 		}
 
+		public override void CollectGarbage()
+		{
+			lock (_executionSynchronizer)
+			{
+				_jsRuntime.CollectGarbage();
+			}
+		}
+
 		#endregion
 
 		#region IDisposable implementation

src/MsieJavaScriptEngine/MsieJavaScriptEngine.Net40.csproj

@@ -49,6 +49,8 @@
     <Compile Include="ActiveScript\ActiveScriptParseWrapper.cs" />
     <Compile Include="ActiveScript\ChakraActiveScriptJsEngine.cs" />
     <Compile Include="ActiveScript\ClassicActiveScriptJsEngine.cs" />
+    <Compile Include="ActiveScript\IActiveScriptGarbageCollector.cs" />
+    <Compile Include="ActiveScript\ScriptGCType.cs" />
     <Compile Include="ActiveScript\ScriptHResult.cs" />
     <Compile Include="ActiveScript\IActiveScript.cs" />
     <Compile Include="ActiveScript\IActiveScriptError.cs" />

src/MsieJavaScriptEngine/MsieJsEngine.cs

@@ -733,6 +733,16 @@ public void EmbedHostType(string itemName, Type type)
 			_jsEngine.EmbedHostType(itemName, type);
 		}
 
+		/// <summary>
+		/// Performs a full garbage collection
+		/// </summary>
+		public void CollectGarbage()
+		{
+			VerifyNotDisposed();
+
+			_jsEngine.CollectGarbage();
+		}
+
 		#region IDisposable implementation
 
 		/// <summary>