--- old/src/hotspot/share/gc/z/zRelocationSetSelector.hpp	2020-01-21 12:41:09.830684859 +0100
+++ new/src/hotspot/share/gc/z/zRelocationSetSelector.hpp	2020-01-21 12:41:09.307674247 +0100
@@ -30,17 +30,55 @@
 class ZPage;
 class ZRelocationSet;
 
+class ZRelocationSetSelectorGroupStats {
+  friend class ZRelocationSetSelectorGroup;
+
+private:
+  size_t _npages;
+  size_t _total;
+  size_t _live;
+  size_t _garbage;
+  size_t _empty;
+  size_t _compacting_from;
+  size_t _compacting_to;
+
+public:
+  ZRelocationSetSelectorGroupStats();
+
+  size_t npages() const;
+  size_t total() const;
+  size_t live() const;
+  size_t garbage() const;
+  size_t empty() const;
+  size_t compacting_from() const;
+  size_t compacting_to() const;
+};
+
+class ZRelocationSetSelectorStats {
+  friend class ZRelocationSetSelector;
+
+private:
+  ZRelocationSetSelectorGroupStats _small;
+  ZRelocationSetSelectorGroupStats _medium;
+  ZRelocationSetSelectorGroupStats _large;
+
+public:
+  const ZRelocationSetSelectorGroupStats& small() const;
+  const ZRelocationSetSelectorGroupStats& medium() const;
+  const ZRelocationSetSelectorGroupStats& large() const;
+};
+
 class ZRelocationSetSelectorGroup {
 private:
-  const char* const _name;
-  const size_t      _page_size;
-  const size_t      _object_size_limit;
-  const size_t      _fragmentation_limit;
-
-  ZArray<ZPage*>    _registered_pages;
-  ZPage**           _sorted_pages;
-  size_t            _nselected;
-  size_t            _relocating;
+  const char* const                _name;
+  const size_t                     _page_size;
+  const size_t                     _object_size_limit;
+  const size_t                     _fragmentation_limit;
+
+  ZArray<ZPage*>                   _registered_pages;
+  ZPage**                          _sorted_pages;
+  size_t                           _nselected;
+  ZRelocationSetSelectorGroupStats _stats;
 
   void semi_sort();
 
@@ -50,20 +88,21 @@
                               size_t object_size_limit);
   ~ZRelocationSetSelectorGroup();
 
-  void register_live_page(ZPage* page, size_t garbage);
+  void register_live_page(ZPage* page);
+  void register_garbage_page(ZPage* page);
   void select();
 
   ZPage* const* selected() const;
   size_t nselected() const;
-  size_t relocating() const;
+
+  const ZRelocationSetSelectorGroupStats& stats() const;
 };
 
 class ZRelocationSetSelector : public StackObj {
 private:
   ZRelocationSetSelectorGroup _small;
   ZRelocationSetSelectorGroup _medium;
-  size_t                      _live;
-  size_t                      _garbage;
+  ZRelocationSetSelectorGroup _large;
 
 public:
   ZRelocationSetSelector();
@@ -72,9 +111,7 @@
   void register_garbage_page(ZPage* page);
   void select(ZRelocationSet* relocation_set);
 
-  size_t live() const;
-  size_t garbage() const;
-  size_t relocating() const;
+  ZRelocationSetSelectorStats stats() const;
 };
 
 #endif // SHARE_GC_Z_ZRELOCATIONSETSELECTOR_HPP