+int mono_gc_get_generation (MonoObject *object);
+int mono_gc_collection_count (int generation);
+int64_t mono_gc_get_used_size (void);
+int64_t mono_gc_get_heap_size (void);
+int mono_gc_invoke_finalizers (void);
+/* heap walking is only valid in the pre-stop-world event callback */
+int mono_gc_walk_heap (int flags, MonoGCReferences callback, void *data);