[Java.Interop] JNI handles are now in a "control block"

src/Java.Interop/Java.Interop/IJavaPeerable.cs

@@ -37,6 +37,8 @@ public interface IJavaPeerable : IDisposable
 		void    Disposed ();
 		/// <include file="../Documentation/Java.Interop/IJavaPeerable.xml" path="/docs/member[@name='M:Finalized']/*" />
 		void    Finalized ();
+
+		IntPtr  JniObjectReferenceControlBlock  => IntPtr.Zero;
 	}
 }
 

src/Java.Interop/Java.Interop/JavaException.cs

@@ -5,7 +5,7 @@
 namespace Java.Interop
 {
 	[JniTypeSignature (JniTypeName, GenerateJavaPeer=false)]
-	unsafe public class JavaException : Exception, IJavaPeerable
+	unsafe public partial class JavaException : Exception, IJavaPeerable
 	{
 		internal    const   string          JniTypeName = "java/lang/Throwable";
 		readonly    static  JniPeerMembers  _members    = new JniPeerMembers (JniTypeName, typeof (JavaException));
@@ -18,13 +18,7 @@ unsafe public class JavaException : Exception, IJavaPeerable
 		JniObjectReference  reference;
 #endif  // FEATURE_JNIOBJECTREFERENCE_SAFEHANDLES
 #if FEATURE_JNIOBJECTREFERENCE_INTPTRS
-		IntPtr                  handle;
-		JniObjectReferenceType  handle_type;
-	#pragma warning disable 0169
-		// Used by JavaInteropGCBridge
-		IntPtr                  weak_handle;
-		int                     refs_added;
-	#pragma warning restore 0169
+		unsafe  JniObjectReferenceControlBlock* jniObjectReferenceControlBlock;
 #endif  // FEATURE_JNIOBJECTREFERENCE_INTPTRS
 
 		protected   static  readonly    JniObjectReference*     InvalidJniObjectReference = null;
@@ -106,7 +100,11 @@ public          JniObjectReference          PeerReference {
 				return reference;
 #endif  // FEATURE_JNIOBJECTREFERENCE_SAFEHANDLES
 #if FEATURE_JNIOBJECTREFERENCE_INTPTRS
-				return new JniObjectReference (handle, handle_type);
+				var c = jniObjectReferenceControlBlock;
+				if (c == null) {
+					return default;
+				}
+				return new JniObjectReference (c->handle, (JniObjectReferenceType) c->handle_type);
 #endif  // FEATURE_JNIOBJECTREFERENCE_INTPTRS
 			}
 		}
@@ -137,8 +135,13 @@ protected void SetPeerReference (ref JniObjectReference reference, JniObjectRefe
 			this.reference      = reference;
 #endif  // FEATURE_JNIOBJECTREFERENCE_SAFEHANDLES
 #if FEATURE_JNIOBJECTREFERENCE_INTPTRS
-			this.handle         = reference.Handle;
-			this.handle_type    = reference.Type;
+			var c   = jniObjectReferenceControlBlock;
+			if (c == null) {
+				c   = jniObjectReferenceControlBlock    =
+					Java.Interop.JniObjectReferenceControlBlock.Alloc ();
+			}
+			c->handle       = reference.Handle;
+			c->handle_type  = (int) reference.Type;
 #endif  // FEATURE_JNIOBJECTREFERENCE_INTPTRS
 
 			JniObjectReference.Dispose (ref reference, options);
@@ -260,11 +263,13 @@ protected void SetJavaStackTrace (JniObjectReference peerReferenceOverride = def
 
 		void IJavaPeerable.Disposed ()
 		{
+			JniManagedPeerState |= Disposed;
 			Dispose (disposing: true);
 		}
 
 		void IJavaPeerable.Finalized ()
 		{
+			JniManagedPeerState |= Disposed;
 			Dispose (disposing: false);
 		}
 
@@ -281,7 +286,15 @@ void IJavaPeerable.SetJniManagedPeerState (JniManagedPeerStates value)
 		void IJavaPeerable.SetPeerReference (JniObjectReference reference)
 		{
 			SetPeerReference (ref reference, JniObjectReferenceOptions.Copy);
+#if FEATURE_JNIOBJECTREFERENCE_INTPTRS
+			if (!reference.IsValid && JniManagedPeerState.HasFlag (Disposed)) {
+				Java.Interop.JniObjectReferenceControlBlock.Free (ref jniObjectReferenceControlBlock);
+			}
+#endif  // FEATURE_JNIOBJECTREFERENCE_INTPTRS
 		}
+
+		IntPtr IJavaPeerable.JniObjectReferenceControlBlock =>
+			(IntPtr) jniObjectReferenceControlBlock;
 	}
 }
 

src/Java.Interop/Java.Interop/JavaObject.cs

@@ -8,7 +8,7 @@ namespace Java.Interop
 {
 	[JniTypeSignature ("java/lang/Object", GenerateJavaPeer=false)]
 	[Serializable]
-	unsafe public class JavaObject : IJavaPeerable
+	unsafe public partial class JavaObject : IJavaPeerable
 	{
 		internal const DynamicallyAccessedMemberTypes Constructors = DynamicallyAccessedMemberTypes.PublicConstructors | DynamicallyAccessedMemberTypes.NonPublicConstructors;
 
@@ -25,13 +25,7 @@ unsafe public class JavaObject : IJavaPeerable
 		[NonSerialized] JniObjectReference  reference;
 #endif  // FEATURE_JNIOBJECTREFERENCE_SAFEHANDLES
 #if FEATURE_JNIOBJECTREFERENCE_INTPTRS
-		[NonSerialized] IntPtr                  handle;
-		[NonSerialized] JniObjectReferenceType  handle_type;
-	#pragma warning disable 0169
-		// Used by JavaInteropGCBridge
-		[NonSerialized] IntPtr                  weak_handle;
-		[NonSerialized] int                     refs_added;
-	#pragma warning restore 0169
+		unsafe  JniObjectReferenceControlBlock* jniObjectReferenceControlBlock;
 #endif  // FEATURE_JNIOBJECTREFERENCE_INTPTRS
 
 		protected   static  readonly    JniObjectReference*     InvalidJniObjectReference  = null;
@@ -41,13 +35,17 @@ unsafe public class JavaObject : IJavaPeerable
 			JniEnvironment.Runtime.ValueManager.FinalizePeer (this);
 		}
 
-		public          JniObjectReference          PeerReference {
+		public  unsafe  JniObjectReference          PeerReference {
 			get {
 #if FEATURE_JNIOBJECTREFERENCE_SAFEHANDLES
 				return reference;
 #endif  // FEATURE_JNIOBJECTREFERENCE_SAFEHANDLES
 #if FEATURE_JNIOBJECTREFERENCE_INTPTRS
-				return new JniObjectReference (handle, handle_type);
+				var c = jniObjectReferenceControlBlock;
+				if (c == null) {
+					return default;
+				}
+				return new JniObjectReference (c->handle, (JniObjectReferenceType) c->handle_type);
 #endif  // FEATURE_JNIOBJECTREFERENCE_INTPTRS
 			}
 		}
@@ -91,8 +89,13 @@ protected void SetPeerReference (ref JniObjectReference reference, JniObjectRefe
 			this.reference      = reference;
 #endif  // FEATURE_JNIOBJECTREFERENCE_SAFEHANDLES
 #if FEATURE_JNIOBJECTREFERENCE_INTPTRS
-			this.handle         = reference.Handle;
-			this.handle_type    = reference.Type;
+			var c   = jniObjectReferenceControlBlock;
+			if (c == null) {
+				c   = jniObjectReferenceControlBlock    =
+					Java.Interop.JniObjectReferenceControlBlock.Alloc ();
+			}
+			c->handle       = reference.Handle;
+			c->handle_type  = (int) reference.Type;
 #endif  // FEATURE_JNIOBJECTREFERENCE_INTPTRS
 
 			JniObjectReference.Dispose (ref reference, options);
@@ -147,11 +150,13 @@ public override unsafe int GetHashCode ()
 
 		void IJavaPeerable.Disposed ()
 		{
+			managedPeerState    |= Disposed;
 			Dispose (disposing: true);
 		}
 
 		void IJavaPeerable.Finalized ()
 		{
+			managedPeerState    |= Disposed;
 			Dispose (disposing: false);
 		}
 
@@ -168,7 +173,16 @@ void IJavaPeerable.SetJniManagedPeerState (JniManagedPeerStates value)
 		void IJavaPeerable.SetPeerReference (JniObjectReference reference)
 		{
 			SetPeerReference (ref reference, JniObjectReferenceOptions.Copy);
+
+#if FEATURE_JNIOBJECTREFERENCE_INTPTRS
+			if (!reference.IsValid && managedPeerState.HasFlag (Disposed)) {
+				Java.Interop.JniObjectReferenceControlBlock.Free (ref jniObjectReferenceControlBlock);
+			}
+#endif  // FEATURE_JNIOBJECTREFERENCE_INTPTRS
 		}
+
+		IntPtr IJavaPeerable.JniObjectReferenceControlBlock =>
+			(IntPtr) jniObjectReferenceControlBlock;
 	}
 }
 

src/Java.Interop/Java.Interop/JniManagedPeerStates.cs

@@ -11,4 +11,12 @@ public enum JniManagedPeerStates {
 		/// <include file="../Documentation/Java.Interop/JniManagedPeerStates.xml" path="/docs/member[@name='F:Replaceable']/*" />
 		Replaceable         = (1 << 1),
 	}
+
+	partial class JavaObject {
+		const       JniManagedPeerStates        Disposed            = (JniManagedPeerStates) (1 << 2);
+	}
+
+	partial class JavaException {
+		const       JniManagedPeerStates        Disposed            = (JniManagedPeerStates) (1 << 2);
+	}
 }

src/Java.Interop/Java.Interop/JniObjectReferenceControlBlock.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace Java.Interop;
+
+internal struct JniObjectReferenceControlBlock {
+	public	IntPtr  handle;
+	public  int     handle_type;
+	public  IntPtr  weak_handle;
+	public  int     refs_added;
+
+	public  static  readonly    int Size    = Marshal.SizeOf<JniObjectReferenceControlBlock>();
+
+	public static unsafe JniObjectReferenceControlBlock* Alloc ()
+	{
+		return (JniObjectReferenceControlBlock*) NativeMemory.AllocZeroed (1, (uint) Size);
+	}
+
+	public static unsafe void Free (ref JniObjectReferenceControlBlock* value)
+	{
+		if (value == null) {
+			return;
+		}
+		NativeMemory.Free (value);
+		value   = null;
+	}
+}

src/Java.Interop/PublicAPI.Unshipped.txt

@@ -11,3 +11,4 @@ Java.Interop.JniRuntime.JniTypeManager.GetInvokerType(System.Type! type) -> Syst
 Java.Interop.JniRuntime.JniValueManager.GetPeer(Java.Interop.JniObjectReference reference, System.Type? targetType = null) -> Java.Interop.IJavaPeerable?
 Java.Interop.JniTypeSignatureAttribute.InvokerType.get -> System.Type?
 Java.Interop.JniTypeSignatureAttribute.InvokerType.set -> void
+Java.Interop.IJavaPeerable.JniObjectReferenceControlBlock.get -> nint