src/hotspot/share/gc/shenandoah/shenandoahCollectionSet.hpp

@@ -1,7 +1,8 @@
  /*
   * Copyright (c) 2016, 2020, Red Hat, Inc. All rights reserved.
+  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.

@@ -31,24 +32,50 @@
  #include "gc/shenandoah/shenandoahHeapRegion.hpp"
  #include "gc/shenandoah/shenandoahPadding.hpp"
  
  class ShenandoahCollectionSet : public CHeapObj<mtGC> {
    friend class ShenandoahHeap;
+   friend class ShenandoahCollectionSetPreselector;
+ 
+   void establish_preselected(bool *preselected) {
+    assert(_preselected_regions == nullptr, "Over-writing");
+    _preselected_regions = preselected;
+   }
+   void abandon_preselected() { _preselected_regions = nullptr; }
+ 
  private:
    size_t const          _map_size;
    size_t const          _region_size_bytes_shift;
    ReservedSpace         _map_space;
    char* const           _cset_map;
    // Bias cset map's base address for fast test if an oop is in cset
    char* const           _biased_cset_map;
  
    ShenandoahHeap* const _heap;
  
+   bool                  _has_old_regions;
    size_t                _garbage;
    size_t                _used;
+   size_t                _live;
    size_t                _region_count;
  
+   size_t                _young_bytes_to_evacuate;
+   size_t                _young_bytes_to_promote;
+   size_t                _old_bytes_to_evacuate;
+ 
+   // How many bytes of old garbage are present in a mixed collection set?
+   size_t                _old_garbage;
+ 
+   // Points to array identifying which tenure-age regions have been preselected
+   // for inclusion in collection set. This field is only valid during brief
+   // spans of time while collection set is being constructed.
+   bool*                 _preselected_regions;
+ 
+   // When a region having memory available to be allocated is added to the collection set, the region's available memory
+   // should be subtracted from what's available.
+   size_t                _young_available_bytes_collected;
+ 
    shenandoah_padding(0);
    volatile size_t       _current_index;
    shenandoah_padding(1);
  
  public:

@@ -75,12 +102,35 @@
    inline bool is_in(oop obj)                 const;
    inline bool is_in_loc(void* loc)           const;
  
    void print_on(outputStream* out) const;
  
-   size_t used()      const { return _used; }
-   size_t garbage()   const { return _garbage;   }
+   // It is not known how many of these bytes will be promoted.
+   inline size_t get_young_bytes_reserved_for_evacuation();
+   inline size_t get_old_bytes_reserved_for_evacuation();
+ 
+   inline size_t get_young_bytes_to_be_promoted();
+ 
+   size_t get_young_available_bytes_collected() { return _young_available_bytes_collected; }
+ 
+   inline size_t get_old_garbage();
+ 
+   bool is_preselected(size_t region_idx) {
+     assert(_preselected_regions != nullptr, "Missing etsablish after abandon");
+     return _preselected_regions[region_idx];
+   }
+ 
+   bool* preselected_regions() {
+     assert(_preselected_regions != nullptr, "Null ptr");
+     return _preselected_regions;
+   }
+ 
+   bool has_old_regions() const { return _has_old_regions; }
+   size_t used()          const { return _used; }
+   size_t live()          const { return _live; }
+   size_t garbage()       const { return _garbage; }
+ 
    void clear();
  
  private:
    char* map_address() const {
      return _cset_map;