1 /*
2 * Copyright (c) 2018, 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
35 G1SATBMarkQueueSet::G1SATBMarkQueueSet() : _g1h(NULL) {}
36
37 void 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 Mutex* lock) {
43 SATBMarkQueueSet::initialize(cbl_mon,
44 allocator,
45 process_completed_buffers_threshold,
46 buffer_enqueue_threshold_percentage,
47 lock);
48 _g1h = g1h;
49 }
50
51 void G1SATBMarkQueueSet::handle_zero_index_for_thread(JavaThread* t) {
52 G1ThreadLocalData::satb_mark_queue(t).handle_zero_index();
53 }
54
55 SATBMarkQueue& G1SATBMarkQueueSet::satb_queue_for_thread(JavaThread* const t) const{
56 return G1ThreadLocalData::satb_mark_queue(t);
57 }
58
59 // Return true if a SATB buffer entry refers to an object that
60 // requires marking.
61 //
62 // The entry must point into the G1 heap. In particular, it must not
63 // be a NULL pointer. NULL pointers are pre-filtered and never
64 // inserted into a SATB buffer.
65 //
66 // An entry that is below the NTAMS pointer for the containing heap
67 // region requires marking. Such an entry must point to a valid object.
68 //
69 // An entry that is at least the NTAMS pointer for the containing heap
70 // region might be any of the following, none of which should be marked.
71 //
72 // * A reference to an object allocated since marking started.
73 // According to SATB, such objects are implicitly kept live and do
74 // not need to be dealt with via SATB buffer processing.
75 //
76 // * A reference to a young generation object. Young objects are
77 // handled separately and are not marked by concurrent marking.
78 //
79 // * A stale reference to a young generation object. If a young
80 // generation object reference is recorded and not filtered out
81 // before being moved by a young collection, the reference becomes
82 // stale.
83 //
84 // * A stale reference to an eagerly reclaimed humongous object. If a
85 // humongous object is recorded and then reclaimed, the reference
86 // becomes stale.
87 //
88 // The stale reference cases are implicitly handled by the NTAMS
89 // comparison. Because of the possibility of stale references, buffer
90 // processing must be somewhat circumspect and not assume entries
91 // in an unfiltered buffer refer to valid objects.
92
93 static inline bool requires_marking(const void* entry, G1CollectedHeap* g1h) {
94 // Includes rejection of NULL pointers.
95 assert(g1h->is_in_reserved(entry),
96 "Non-heap pointer in SATB buffer: " PTR_FORMAT, p2i(entry));
97
98 HeapRegion* region = g1h->heap_region_containing(entry);
99 assert(region != NULL, "No region for " PTR_FORMAT, p2i(entry));
100 if (entry >= region->next_top_at_mark_start()) {
101 return false;
102 }
103
104 assert(oopDesc::is_oop(oop(entry), true /* ignore mark word */),
105 "Invalid oop in SATB buffer: " PTR_FORMAT, p2i(entry));
106
107 return true;
108 }
109
110 static inline bool discard_entry(const void* entry, G1CollectedHeap* g1h) {
111 return !requires_marking(entry, g1h) || g1h->is_marked_next((oop)entry);
112 }
113
114 // Workaround for not yet having std::bind.
115 class G1SATBMarkQueueFilterFn {
116 G1CollectedHeap* _g1h;
117
118 public:
119 G1SATBMarkQueueFilterFn(G1CollectedHeap* g1h) : _g1h(g1h) {}
120
121 // Return true if entry should be filtered out (removed), false if
122 // it should be retained.
123 bool operator()(const void* entry) const {
124 return discard_entry(entry, _g1h);
125 }
126 };
127
128 void G1SATBMarkQueueSet::filter(SATBMarkQueue* queue) {
129 assert(_g1h != NULL, "SATB queue set not initialized");
130 apply_filter(G1SATBMarkQueueFilterFn(_g1h), queue);
131 }