g1FromCardCache.hpp revision 9865:a8f8a794a896 
1/*
2 * Copyright (c) 2013, 2015, 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.
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23 */
24
25#ifndef SHARE_VM_GC_G1_G1FROMCARDCACHE_HPP
26#define SHARE_VM_GC_G1_G1FROMCARDCACHE_HPP
27
28#include "memory/allocation.hpp"
29#include "utilities/ostream.hpp"
30
31// The FromCardCache remembers the most recently processed card on the heap on
32// a per-region and per-thread basis.
33class FromCardCache : public AllStatic {
34 private:
35  // Array of card indices. Indexed by thread X and heap region to minimize
36  // thread contention.
37  static int** _cache;
38  static uint _max_regions;
39  static size_t _static_mem_size;
40
41 public:
42  enum {
43    InvalidCard = -1 // Card value of an invalid card, i.e. a card index not otherwise used.
44  };
45
46  static void clear(uint region_idx);
47
48  // Returns true if the given card is in the cache at the given location, or
49  // replaces the card at that location and returns false.
50  static bool contains_or_replace(uint worker_id, uint region_idx, int card) {
51    int card_in_cache = at(worker_id, region_idx);
52    if (card_in_cache == card) {
53      return true;
54    } else {
55      set(worker_id, region_idx, card);
56      return false;
57    }
58  }
59
60  static int at(uint worker_id, uint region_idx) {
61    return _cache[worker_id][region_idx];
62  }
63
64  static void set(uint worker_id, uint region_idx, int val) {
65    _cache[worker_id][region_idx] = val;
66  }
67
68  static void initialize(uint n_par_rs, uint max_num_regions);
69
70  static void invalidate(uint start_idx, size_t num_regions);
71
72  static void print(outputStream* out = tty) PRODUCT_RETURN;
73
74  static size_t static_mem_size() {
75    return _static_mem_size;
76  }
77};
78
79#endif // SHARE_VM_GC_G1_G1FROMCARDCACHE_HPP
80