1/*
2 * Copyright (c) 2019, 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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25#ifndef SHARE_GC_G1_G1COLLECTIONSETCANDIDATES_HPP
26#define SHARE_GC_G1_G1COLLECTIONSETCANDIDATES_HPP
27
28#include "gc/g1/g1CollectionSetCandidates.hpp"
29#include "gc/shared/workgroup.hpp"
30#include "memory/allocation.hpp"
31#include "runtime/globals.hpp"
32
33class HeapRegion;
34class HeapRegionClosure;
35
36// Set of collection set candidates, i.e. all old gen regions we consider worth
37// collecting in the remainder of the current mixed phase. Regions are sorted by decreasing
38// gc efficiency.
39// Maintains a cursor into the list that specifies the next collection set candidate
40// to put into the current collection set.
41class G1CollectionSetCandidates : public CHeapObj<mtGC> {
42 HeapRegion** _regions;
43 uint _num_regions; // Total number of regions in the collection set candidate set.
44
45 // The sum of bytes that can be reclaimed in the remaining set of collection
46 // set candidates.
47 size_t _remaining_reclaimable_bytes;
48 // The index of the next candidate old region to be considered for
49 // addition to the current collection set.
50 uint _front_idx;
51
52public:
53 G1CollectionSetCandidates(HeapRegion** regions, uint num_regions, size_t remaining_reclaimable_bytes) :
54 _regions(regions),
55 _num_regions(num_regions),
56 _remaining_reclaimable_bytes(remaining_reclaimable_bytes),
57 _front_idx(0) { }
58
59 ~G1CollectionSetCandidates() {
60 FREE_C_HEAP_ARRAY(HeapRegion*, _regions);
61 }
62
63 // Returns the total number of collection set candidate old regions added.
64 uint num_regions() { return _num_regions; }
65
66 uint cur_idx() const { return _front_idx; }
67
68 HeapRegion* at(uint idx) const {
69 HeapRegion* res = NULL;
70 if (idx < _num_regions) {
71 res = _regions[idx];
72 assert(res != NULL, "Unexpected NULL HeapRegion at index %u", idx);
73 }
74 return res;
75 }
76
77 void remove(uint num_regions);
78
79 // Iterate over all remaining collection set candidate regions.
80 void iterate(HeapRegionClosure* cl);
81
82 // Return the number of candidate regions remaining.
83 uint num_remaining() { return _num_regions - _front_idx; }
84
85 bool is_empty() { return num_remaining() == 0; }
86
87 // Return the amount of reclaimable bytes that may be collected by the remaining
88 // candidate regions.
89 size_t remaining_reclaimable_bytes() { return _remaining_reclaimable_bytes; }
90
91 void verify() const PRODUCT_RETURN;
92};
93
94#endif /* SHARE_GC_G1_G1COLLECTIONSETCANDIDATES_HPP */
95
96