1 /*
   2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_VM_GC_G1_G1CARDLIVEDATA_HPP
  26 #define SHARE_VM_GC_G1_G1CARDLIVEDATA_HPP
  27 
  28 #include "gc/g1/g1CollectedHeap.hpp"
  29 #include "utilities/bitMap.hpp"
  30 #include "utilities/globalDefinitions.hpp"
  31 
  32 class G1CollectedHeap;
  33 class G1CMBitMap;
  34 class WorkGang;
  35 
  36 // Information about object liveness on the Java heap on a "card" basis.
  37 // Can be used for various purposes, like as remembered set for completely
  38 // coarsened remembered sets, scrubbing remembered sets or estimating liveness.
  39 // This information is created as part of the concurrent marking cycle.
  40 class G1CardLiveData VALUE_OBJ_CLASS_SPEC {
  41   friend class G1CardLiveDataHelper;
  42   friend class G1VerifyCardLiveDataTask;
  43 private:
  44   typedef BitMap::bm_word_t bm_word_t;
  45   // Store some additional information about the covered area to be able to test.
  46   size_t _max_capacity;
  47   size_t _cards_per_region;
  48 
  49   // The per-card liveness bitmap.
  50   bm_word_t* _live_cards;
  51   size_t _live_cards_size_in_bits;
  52   // The per-region liveness bitmap.
  53   bm_word_t* _live_regions;
  54   size_t _live_regions_size_in_bits;
  55   // The bits in this bitmap contain for every card whether it contains
  56   // at least part of at least one live object.
  57   BitMap live_cards_bm() const { return BitMap(_live_cards, _live_cards_size_in_bits); }
  58   // The bits in this bitmap indicate that a given region contains some live objects.
  59   BitMap live_regions_bm() const { return BitMap(_live_regions, _live_regions_size_in_bits); }
  60 
  61   // Allocate a "large" bitmap from virtual memory with the given size in bits.
  62   bm_word_t* allocate_large_bitmap(size_t size_in_bits);
  63   void free_large_bitmap(bm_word_t* map, size_t size_in_bits);
  64 
  65   inline BitMap live_card_bitmap(uint region);
  66 
  67   inline bool is_card_live_at(BitMap::idx_t idx) const;
  68 
  69   size_t live_region_bitmap_size_in_bits() const;
  70   size_t live_card_bitmap_size_in_bits() const;
  71 public:
  72   inline bool is_region_live(uint region) const;
  73 
  74   inline void remove_nonlive_cards(uint region, BitMap* bm);
  75   inline void remove_nonlive_regions(BitMap* bm);
  76 
  77   G1CardLiveData();
  78   ~G1CardLiveData();
  79 
  80   void initialize(size_t max_capacity, uint num_max_regions);
  81   void pretouch();
  82 
  83   // Create the initial liveness data based on the marking result from the bottom
  84   // to the ntams of every region in the heap and the marks in the given bitmap.
  85   void create(WorkGang* workers, G1CMBitMap* mark_bitmap);
  86   // Finalize the liveness data.
  87   void finalize(WorkGang* workers, G1CMBitMap* mark_bitmap);
  88 
  89   // Verify that the liveness count data created concurrently matches one created
  90   // during this safepoint.
  91   void verify(WorkGang* workers, G1CMBitMap* actual_bitmap);
  92   // Clear all data structures, prepare for next processing.
  93   void clear(WorkGang* workers);
  94 
  95   void verify_is_clear() PRODUCT_RETURN;
  96 };
  97 
  98 #endif /* SHARE_VM_GC_G1_G1CARDLIVEDATA_HPP */
  99