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 /*

  * Copyright (c) 2013, Oracle and/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.

  *

  * 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.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 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;

   }

   void check_card_num(size_t card_num, const char* msg) {

     assert(card_num >= 0 && card_num < _committed_max_card_num, msg);

   }

   size_t ptr_2_card_num(const jbyte* card_ptr) {

     assert(card_ptr >= _ct_bot,

            err_msg("Inavalied card pointer: "

                    "card_ptr: " PTR_FORMAT ", "

                    "_ct_bot: " PTR_FORMAT,

                    card_ptr, _ct_bot));

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

     check_card_num(card_num,

                    err_msg("card pointer out of range: " PTR_FORMAT, card_ptr));

     return card_num;

   }

   jbyte* card_num_2_ptr(size_t card_num) {

     check_card_num(card_num,

                    err_msg("card num out of range: "SIZE_FORMAT, 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