Quellcode-Bibliothek

^© Kompilation durch diese Firma

[Weder Korrektheit noch Funktionsfähigkeit der Software werden zugesichert.]

Datei: g1CardTable.hpp Sprache: C

/*
* Copyright (c) 2001, 2019, 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
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/

#ifndef SHARE_GC_G1_G1CARDTABLE_HPP
#define SHARE_GC_G1_G1CARDTABLE_HPP

#include "gc/g1/g1RegionToSpaceMapper.hpp"
#include "gc/shared/cardTable.hpp"
#include "oops/oopsHierarchy.hpp"
#include "utilities/macros.hpp"

class G1CardTable;
class G1RegionToSpaceMapper;

class G1CardTableChangedListener : public G1MappingChangedListener {
private:
  G1CardTable* _card_table;
public:
  G1CardTableChangedListener() : _card_table(NULL) { }

  void set_card_table(G1CardTable* card_table) { _card_table = card_table; }

  void on_commit(uint start_idx, size_t num_regions, bool zero_filled) override;
};

class G1CardTable : public CardTable {
  friend class VMStructs;
  friend class G1CardTableChangedListener;

  G1CardTableChangedListener _listener;

public:
  enum G1CardValues {
    g1_young_gen = CT_MR_BS_last_reserved << 1,

    // During evacuation we use the card table to consolidate the cards we need to
    // scan for roots onto the card table from the various sources. Further it is
    // used to record already completely scanned cards to avoid re-scanning them
    // when incrementally evacuating the old gen regions of a collection set.
    // This means that already scanned cards should be preserved.
    //
    // The merge at the start of each evacuation round simply sets cards to dirty
    // that are clean; scanned cards are set to 0x1.
    //
    // This means that the LSB determines what to do with the card during evacuation
    // given the following possible values:
    //
    // 11111111 - clean, do not scan
    // 00000001 - already scanned, do not scan
    // 00000000 - dirty, needs to be scanned.
    //
    g1_card_already_scanned = 0x1
  };

  static const size_t WordAllClean = SIZE_MAX;
  static const size_t WordAllDirty = 0;

  STATIC_ASSERT(BitsPerByte == 8);
  static const size_t WordAlreadyScanned = (SIZE_MAX / 255) * g1_card_already_scanned;

  G1CardTable(MemRegion whole_heap): CardTable(whole_heap), _listener() {
    _listener.set_card_table(this);
  }

  static CardValue g1_young_card_val() { return g1_young_gen; }
  static CardValue g1_scanned_card_val() { return g1_card_already_scanned; }

  void verify_g1_young_region(MemRegion mr) PRODUCT_RETURN;
  void g1_mark_as_young(const MemRegion& mr);

  size_t index_for_cardvalue(CardValue const* p) const {
    return pointer_delta(p, _byte_map, sizeof(CardValue));
  }

  // Mark the given card as Dirty if it is Clean. Returns whether the card was
  // Clean before this operation. This result may be inaccurate as it does not
  // perform the dirtying atomically.
  inline bool mark_clean_as_dirty(CardValue* card);

  // Change Clean cards in a (large) area on the card table as Dirty, preserving
  // already scanned cards. Assumes that most cards in that area are Clean.
  inline void mark_range_dirty(size_t start_card_index, size_t num_cards);

  // Change the given range of dirty cards to "which". All of these cards must be Dirty.
  inline void change_dirty_cards_to(size_t start_card_index, size_t num_cards, CardValue which);

  inline uint region_idx_for(CardValue* p);

  static size_t compute_size(size_t mem_region_size_in_words) {
    size_t number_of_slots = (mem_region_size_in_words / _card_size_in_words);
    return ReservedSpace::allocation_align_size_up(number_of_slots);
  }

  // Returns how many bytes of the heap a single byte of the Card Table corresponds to.
  static size_t heap_map_factor() { return _card_size; }

  void initialize() override {}
  void initialize(G1RegionToSpaceMapper* mapper);

  void resize_covered_region(MemRegion new_region) override { ShouldNotReachHere(); }

  bool is_in_young(const void* p) const override;
};

#endif // SHARE_GC_G1_G1CARDTABLE_HPP

¤ Dauer der Verarbeitung: 0.14 Sekunden (vorverarbeitet) ¤

Download des Quellennavigators
Download des sprechenden Kalenders
in der Quellcodebibliothek suchen

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.