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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP

#define SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP

#include "memory/allocation.hpp"

#include "runtime/virtualspace.hpp"

#include "utilities/globalDefinitions.hpp"

class CardTableModRefBS;

class G1CollectedHeap;

class HeapRegion;

// Table to track the number of times a card has been refined. Once

// a card has been refined a certain number of times, it is

// considered 'hot' and its refinement is delayed by inserting the

// card into the hot card cache. The card will then be refined when

// it is evicted from the hot card cache, or when the hot card cache

// is 'drained' during the next evacuation pause.

class G1CardCounts: public CHeapObj<mtGC> {

  G1CollectedHeap* _g1h;

  // The table of counts

  jubyte* _card_counts;

  // Max capacity of the reserved space for the counts table

  size_t _reserved_max_card_num;

  // Max capacity of the committed space for the counts table

  size_t _committed_max_card_num;

  // Size of committed space for the counts table

  size_t _committed_size;

  // CardTable bottom.

  const jbyte* _ct_bot;

  // Barrier set

  CardTableModRefBS* _ct_bs;

  // The virtual memory backing the counts table

  VirtualSpace _card_counts_storage;

  // Returns true if the card counts table has been reserved.

  bool has_reserved_count_table() { return _card_counts != NULL; }

  // Returns true if the card counts table has been reserved and committed.

  bool has_count_table() {

    return has_reserved_count_table() && _committed_max_card_num > 0;

  }

  size_t ptr_2_card_num(const jbyte* card_ptr) {

    assert(card_ptr >= _ct_bot,

                   "card_ptr: " PTR_FORMAT ", "

                   "_ct_bot: " PTR_FORMAT,

                   card_ptr, _ct_bot));

    size_t card_num = pointer_delta(card_ptr, _ct_bot, sizeof(jbyte));

    return card_num;

  }

  jbyte* card_num_2_ptr(size_t card_num) {

    return (jbyte*) (_ct_bot + card_num);

  }

  // Helper routine.

  // Returns the number of cards that can be counted by the given committed

  // table size, with a maximum of the number of cards spanned by the max

  // capacity of the heap.

  size_t committed_to_card_num(size_t committed_size) {

    return MIN2(_reserved_max_card_num, committed_size / sizeof(jbyte));

  }

  // Clear the counts table for the given (exclusive) index range.

  void clear_range(size_t from_card_num, size_t to_card_num);

 public:

  G1CardCounts(G1CollectedHeap* g1h);

  ~G1CardCounts();

  void initialize();

  // Resize the committed space for the card counts table in

  // response to a resize of the committed space for the heap.

  void resize(size_t heap_capacity);

  // Increments the refinement count for the given card.

  // Returns the pre-increment count value.

  uint add_card_count(jbyte* card_ptr);

  // Returns true if the given count is high enough to be considered

  // 'hot'; false otherwise.

  bool is_hot(uint count);

  // Clears the card counts for the cards spanned by the region

  void clear_region(HeapRegion* hr);

  // Clear the entire card counts table during GC.

  // Updates the policy stats with the duration.

  void clear_all();

};

#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1CARDCOUNTS_HPP