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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
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 *
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#ifndef SHARE_GC_G1_G1SURVIVORREGIONS_HPP
#define SHARE_GC_G1_G1SURVIVORREGIONS_HPP

#include "runtime/globals.hpp"

template <typename T>
class GrowableArray;
class HeapRegion;

class G1SurvivorRegions {
private:
  GrowableArray<HeapRegion*>* _regions;
  volatile size_t             _used_bytes;
  // When a heap region is retired add_used_bytes() will be called to update its used bytes.
  // But when the heap region is retained, that heap region's used bytes must be subtracted
  // because it will be reused as a mutator region. Save that value in _retained_used_bytes.
  size_t                      _retained_used_bytes;
  uint                        _retained_regions;

public:
  G1SurvivorRegions();

  void add(HeapRegion* hr);

  // Remove the heap region from _regions.
  // Later the removed heap region will be used as a mutator region.
  void remove(HeapRegion* hr);

  void convert_to_eden();

  void clear();

  // Total of heap regions at _regions.
  // I.e. heap regions tagged as a survivor.
  uint length() const;

  // Returns 0 or 1 which is retained region count.
  uint retained_length() const;

  const GrowableArray<HeapRegion*>* regions() const {
    return _regions;
  }

  void add_used_bytes(size_t used_bytes);

  // Returns used bytes of retired survivor regions not including used bytes of
  // any retained region. When Heap_lock is not held, G1CollectedHeap::_summary_bytes_used
  // is referred to get used bytes of non-allocating heap regions. In such case,
  // the used bytes of any retained region should not be included as it has already been changed
  // to a mutator region.
  size_t used_bytes() const { return _used_bytes; }

  size_t retained_used_bytes() const { return _retained_used_bytes; }
};

#endif // SHARE_GC_G1_G1SURVIVORREGIONS_HPP