1 /*
2 * Copyright (c) 2016, 2019, Red Hat, Inc. 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_GC_SHENANDOAH_SHENANDOAHFREESET_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHFREESET_HPP
27
28 #include "gc/shenandoah/shenandoahHeapRegionSet.hpp"
29 #include "gc/shenandoah/shenandoahHeap.hpp"
30
31 class ShenandoahFreeSet : public CHeapObj<mtGC> {
32 private:
33 ShenandoahHeap* const _heap;
34 CHeapBitMap _mutator_free_bitmap;
35 CHeapBitMap _collector_free_bitmap;
36 size_t _max;
37
38 // Left-most and right-most region indexes. There are no free regions outside
39 // of [left-most; right-most] index intervals
40 size_t _mutator_leftmost, _mutator_rightmost;
41 size_t _collector_leftmost, _collector_rightmost;
42
43 size_t _capacity;
44 size_t _used;
45
46 void assert_bounds() const NOT_DEBUG_RETURN;
47
48 bool is_mutator_free(size_t idx) const;
49 bool is_collector_free(size_t idx) const;
50
51 HeapWord* try_allocate_in(ShenandoahHeapRegion* region, ShenandoahAllocRequest& req, bool& in_new_region);
52 HeapWord* allocate_with_affiliation(ShenandoahRegionAffiliation affiliation, ShenandoahAllocRequest& req, bool& in_new_region);
53 HeapWord* allocate_with_old_affiliation(ShenandoahAllocRequest& req, bool& in_new_region);
54
55 // While holding the heap lock, allocate memory for a single object which is to be entirely contained
56 // within a single HeapRegion as characterized by req. The req.size() value is known to be less than or
57 // equal to ShenandoahHeapRegion::humongous_threshold_words(). The caller of allocate_single is responsible
58 // for registering the resulting object and setting the remembered set card values as appropriate. The
59 // most common case is that we are allocating a PLAB in which case object registering and card dirtying
60 // is managed after the PLAB is divided into individual objects.
61 HeapWord* allocate_single(ShenandoahAllocRequest& req, bool& in_new_region);
62 HeapWord* allocate_contiguous(ShenandoahAllocRequest& req);
63
64 void flip_to_gc(ShenandoahHeapRegion* r);
65
66 void recompute_bounds();
67 void adjust_bounds();
68 bool touches_bounds(size_t num) const;
69
70 void increase_used(size_t amount);
71 void clear_internal();
72
73 void try_recycle_trashed(ShenandoahHeapRegion *r);
74
75 bool can_allocate_from(ShenandoahHeapRegion *r);
76 size_t alloc_capacity(ShenandoahHeapRegion *r);
77 bool has_no_alloc_capacity(ShenandoahHeapRegion *r);
78
79 public:
80 ShenandoahFreeSet(ShenandoahHeap* heap, size_t max_regions);
81
82 // Number of regions dedicated to GC allocations (for evacuation or promotion) that are currently free
83 size_t collector_count() const { return _collector_free_bitmap.count_one_bits(); }
84
85 // Number of regions dedicated to mutator allocations that are currently free
86 size_t mutator_count() const { return _mutator_free_bitmap.count_one_bits(); }
87
88 void clear();
89 void rebuild();
90
91 void recycle_trash();
92
93 void log_status();
94
95 size_t capacity() const { return _capacity; }
96 size_t used() const { return _used; }
97 size_t available() const {
98 assert(_used <= _capacity, "must use less than capacity");
99 return _capacity - _used;
100 }
101
102 HeapWord* allocate(ShenandoahAllocRequest& req, bool& in_new_region);
103 size_t unsafe_peek_free() const;
104
105 double internal_fragmentation();
106 double external_fragmentation();
107
108 void print_on(outputStream* out) const;
109
110 void reserve_regions(size_t to_reserve);
111 };
112
113 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHFREESET_HPP