Implement MonoVM BC Bridge :: Java Marshaling API "thunk"

Commit 9e9daf4 suggested that we could
probably "thunk" the MonoVM API to implement the proposed
Java Bridge API..

Implement the thunk!

Next up: implementing `markCrossReferences` in C#!

Author: jonpryor

src/Java.Runtime.Environment/Java.Interop/JavaBridgedValueManager.cs

@@ -23,6 +23,7 @@ public struct ComponentCrossReference {
 	}
 
 	public unsafe struct StronglyConnectedComponent {
+		public int IsAlive;
 		public nint Count;
 		public System.IntPtr* Context;
 	}

src/Java.Runtime.Environment/Java.Interop/MonoRuntimeValueManager.cs

@@ -415,6 +415,18 @@ partial class JreNativeMethods {
 
 		[DllImport (JavaInteropLib, CallingConvention=CallingConvention.Cdecl)]
 		internal static extern void java_interop_gc_bridge_wait_for_bridge_processing (IntPtr bridge);
+
+		[DllImport (JavaInteropLib, CallingConvention=CallingConvention.Cdecl)]
+		internal static extern unsafe int java_interop_gc_bridge_set_mark_cross_references (
+				IntPtr bridge,
+				delegate* unmanaged[Cdecl]<System.Runtime.InteropServices.Java.MarkCrossReferences*, void> markCrossReferences
+		);
+
+		[DllImport (JavaInteropLib, CallingConvention=CallingConvention.Cdecl)]
+		internal static extern unsafe int java_interop_gc_bridge_release_mark_cross_references_resources (
+				IntPtr bridge,
+				System.Runtime.InteropServices.Java.MarkCrossReferences* crossReferences
+		);
 	}
 
 	sealed class OverrideStackTrace : Exception {

src/java-interop/java-interop-gc-bridge-mono.cc

@@ -76,6 +76,8 @@ struct JavaInteropGCBridge {
 	char                               *gref_path,     *lref_path;
 	int                                 gref_log_level, lref_log_level;
 	int                                 gref_cleanup,   lref_cleanup;
+
+	JavaInteropMarkCrossReferencesCallback  mark_cross_references;
 };
 
 static jobject
@@ -1283,6 +1285,46 @@ gc_cross_references (int num_sccs, MonoGCBridgeSCC **sccs, int num_xrefs, MonoGC
 	free (thread_name);
 }
 
+static void
+managed_gc_cross_references (int num_sccs, MonoGCBridgeSCC **sccs, int num_xrefs, MonoGCBridgeXRef *xrefs)
+{
+	if (mono_bridge->mark_cross_references == NULL) {
+		assert (!"mono_bridge->mark_cross_references is NULL; WE SHOULD NOT BE EXECUTING");
+		return;
+	}
+	int i;
+
+	Srij_MarkCrossReferences cross_references = {};
+
+	cross_references.ComponentsLen  = (void*) (intptr_t) num_sccs;
+	cross_references.Components     = (Srij_StronglyConnectedComponent*) calloc (num_sccs, sizeof (Srij_StronglyConnectedComponent));
+	for (i = 0; i < num_sccs; ++i) {
+		Srij_StronglyConnectedComponent *scc    = &cross_references.Components [i];
+
+		scc->Count      = (void*) (intptr_t) sccs [i]->num_objs;
+		scc->Context    = (void**) calloc (sccs [i]->num_objs, sizeof (void*));
+		for (int j = 0; j < sccs [i]->num_objs; ++j) {
+			MonoObject *obj	    = sccs [i]->objs [j];
+			scc->Context [j]    = get_gc_control_block_for_object (mono_bridge, obj);
+		}
+	}
+
+	cross_references.CrossReferencesLen = (void*) (intptr_t) num_xrefs;
+	cross_references.CrossReferences    = (Srij_ComponentCrossReference*) calloc (num_xrefs, sizeof (Srij_ComponentCrossReference));
+	for (i = 0; i < num_xrefs; ++i) {
+		Srij_ComponentCrossReference *xref = &cross_references.CrossReferences [i];
+		xref->SourceGroupIndex      = (void*) (intptr_t) xrefs [i].src_scc_index;
+		xref->DestinationGroupIndex = (void*) (intptr_t) xrefs [i].dst_scc_index;
+	}
+
+	mono_bridge->mark_cross_references (&cross_references);
+
+	for (i = 0; i < num_sccs; ++i) {
+		Srij_StronglyConnectedComponent *scc    = &cross_references.Components [i];
+		sccs [i]->is_alive = scc->IsAlive;
+	}
+}
+
 int
 java_interop_gc_bridge_register_hooks (JavaInteropGCBridge *bridge, int weak_ref_kind)
 {
@@ -1316,7 +1358,9 @@ java_interop_gc_bridge_register_hooks (JavaInteropGCBridge *bridge, int weak_ref
 	bridge_cbs.bridge_version       = SGEN_BRIDGE_VERSION;
 	bridge_cbs.bridge_class_kind    = gc_bridge_class_kind;
 	bridge_cbs.is_bridge_object     = gc_is_bridge_object;
-	bridge_cbs.cross_references     = gc_cross_references;
+	bridge_cbs.cross_references     = bridge->mark_cross_references
+		? managed_gc_cross_references
+		: gc_cross_references;
 
 	mono_gc_register_bridge_callbacks (&bridge_cbs);
 
@@ -1332,3 +1376,28 @@ java_interop_gc_bridge_wait_for_bridge_processing (JavaInteropGCBridge *bridge)
 	mono_gc_wait_for_bridge_processing ();
 	return 0;
 }
+
+int
+java_interop_gc_bridge_set_mark_cross_references (JavaInteropGCBridge *bridge, JavaInteropMarkCrossReferencesCallback markCrossReferences)
+{
+	if (bridge == NULL)
+		return -1;
+
+	bridge->mark_cross_references   = markCrossReferences;
+
+	return 0;
+}
+
+int
+java_interop_gc_bridge_release_mark_cross_references_resources (JavaInteropGCBridge *bridge, Srij_MarkCrossReferences *crossReferences)
+{
+	if (bridge == NULL)
+		return -1;
+
+	if (crossReferences == NULL)
+		return -1;
+
+	// leak it…
+
+	return 0;
+}

src/java-interop/java-interop-gc-bridge.h

@@ -19,6 +19,26 @@ struct JavaInterop_System_RuntimeTypeHandle {
 	void   *value;
 };
 
+typedef struct Srij_ComponentCrossReference {
+	void *SourceGroupIndex;
+	void *DestinationGroupIndex;
+} Srij_ComponentCrossReference;
+
+typedef struct Srij_StronglyConnectedComponent {
+	int IsAlive;
+	void *Count;
+	void **Context;
+} Srij_StronglyConnectedComponent;
+
+typedef struct Srij_MarkCrossReferences {
+	void *ComponentsLen;
+	Srij_StronglyConnectedComponent *Components;
+	void* CrossReferencesLen;
+	Srij_ComponentCrossReference *CrossReferences;
+} Srij_MarkCrossReferences;
+
+typedef void (*JavaInteropMarkCrossReferencesCallback) (Srij_MarkCrossReferences *crossReferences);
+
 JAVA_INTEROP_API    JavaInteropGCBridge    *java_interop_gc_bridge_get_current                  (void);
 JAVA_INTEROP_API    int                     java_interop_gc_bridge_set_current_once             (JavaInteropGCBridge *bridge);
 
@@ -32,6 +52,10 @@ JAVA_INTEROP_API    int                     java_interop_gc_bridge_add_current_a
 JAVA_INTEROP_API    int                     java_interop_gc_bridge_remove_current_app_domain    (JavaInteropGCBridge *bridge);
 
 JAVA_INTEROP_API    int                     java_interop_gc_bridge_set_bridge_processing_field  (JavaInteropGCBridge *bridge,   struct JavaInterop_System_RuntimeTypeHandle type_handle,    char *field_name);
+
+JAVA_INTEROP_API    int                     java_interop_gc_bridge_set_mark_cross_references    (JavaInteropGCBridge *bridge,   JavaInteropMarkCrossReferencesCallback markCrossReferences);
+JAVA_INTEROP_API    int                     java_interop_gc_bridge_release_mark_cross_references_resources (JavaInteropGCBridge *bridge, Srij_MarkCrossReferences *crossReferences);
+
 JAVA_INTEROP_API    int                     java_interop_gc_bridge_register_bridgeable_type     (JavaInteropGCBridge *bridge,   struct JavaInterop_System_RuntimeTypeHandle type_handle);
 JAVA_INTEROP_API    int                     java_interop_gc_bridge_enable                       (JavaInteropGCBridge *bridge,   int enable);