1/*
2 * Copyright (c) 2018, 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.
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#include "precompiled.hpp"
26#include "gc/g1/g1CollectedHeap.inline.hpp"
27#include "gc/g1/g1SATBMarkQueueSet.hpp"
28#include "gc/g1/g1ThreadLocalData.hpp"
29#include "gc/g1/heapRegion.hpp"
30#include "gc/shared/satbMarkQueue.hpp"
31#include "oops/oop.hpp"
32#include "utilities/debug.hpp"
33#include "utilities/globalDefinitions.hpp"
34
35G1SATBMarkQueueSet::G1SATBMarkQueueSet() : _g1h(NULL) {}
36
37void G1SATBMarkQueueSet::initialize(G1CollectedHeap* g1h,
38 Monitor* cbl_mon,
39 BufferNode::Allocator* allocator,
40 size_t process_completed_buffers_threshold,
41 uint buffer_enqueue_threshold_percentage) {
42 SATBMarkQueueSet::initialize(cbl_mon,
43 allocator,
44 process_completed_buffers_threshold,
45 buffer_enqueue_threshold_percentage);
46 _g1h = g1h;
47}
48
49void G1SATBMarkQueueSet::handle_zero_index_for_thread(Thread* t) {
50 G1ThreadLocalData::satb_mark_queue(t).handle_zero_index();
51}
52
53SATBMarkQueue& G1SATBMarkQueueSet::satb_queue_for_thread(Thread* const t) const{
54 return G1ThreadLocalData::satb_mark_queue(t);
55}
56
57// Return true if a SATB buffer entry refers to an object that
58// requires marking.
59//
60// The entry must point into the G1 heap. In particular, it must not
61// be a NULL pointer. NULL pointers are pre-filtered and never
62// inserted into a SATB buffer.
63//
64// An entry that is below the NTAMS pointer for the containing heap
65// region requires marking. Such an entry must point to a valid object.
66//
67// An entry that is at least the NTAMS pointer for the containing heap
68// region might be any of the following, none of which should be marked.
69//
70// * A reference to an object allocated since marking started.
71// According to SATB, such objects are implicitly kept live and do
72// not need to be dealt with via SATB buffer processing.
73//
74// * A reference to a young generation object. Young objects are
75// handled separately and are not marked by concurrent marking.
76//
77// * A stale reference to a young generation object. If a young
78// generation object reference is recorded and not filtered out
79// before being moved by a young collection, the reference becomes
80// stale.
81//
82// * A stale reference to an eagerly reclaimed humongous object. If a
83// humongous object is recorded and then reclaimed, the reference
84// becomes stale.
85//
86// The stale reference cases are implicitly handled by the NTAMS
87// comparison. Because of the possibility of stale references, buffer
88// processing must be somewhat circumspect and not assume entries
89// in an unfiltered buffer refer to valid objects.
90
91static inline bool requires_marking(const void* entry, G1CollectedHeap* g1h) {
92 // Includes rejection of NULL pointers.
93 assert(g1h->is_in_reserved(entry),
94 "Non-heap pointer in SATB buffer: " PTR_FORMAT, p2i(entry));
95
96 HeapRegion* region = g1h->heap_region_containing(entry);
97 assert(region != NULL, "No region for " PTR_FORMAT, p2i(entry));
98 if (entry >= region->next_top_at_mark_start()) {
99 return false;
100 }
101
102 assert(oopDesc::is_oop(oop(entry), true /* ignore mark word */),
103 "Invalid oop in SATB buffer: " PTR_FORMAT, p2i(entry));
104
105 return true;
106}
107
108static inline bool discard_entry(const void* entry, G1CollectedHeap* g1h) {
109 return !requires_marking(entry, g1h) || g1h->is_marked_next((oop)entry);
110}
111
112// Workaround for not yet having std::bind.
113class G1SATBMarkQueueFilterFn {
114 G1CollectedHeap* _g1h;
115
116public:
117 G1SATBMarkQueueFilterFn(G1CollectedHeap* g1h) : _g1h(g1h) {}
118
119 // Return true if entry should be filtered out (removed), false if
120 // it should be retained.
121 bool operator()(const void* entry) const {
122 return discard_entry(entry, _g1h);
123 }
124};
125
126void G1SATBMarkQueueSet::filter(SATBMarkQueue* queue) {
127 assert(_g1h != NULL, "SATB queue set not initialized");
128 apply_filter(G1SATBMarkQueueFilterFn(_g1h), queue);
129}
130