1 /*
2 * Copyright (c) 2021, 2024, 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
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22 */
23
24 #ifndef SHARE_GC_Z_ZITERATOR_INLINE_HPP
25 #define SHARE_GC_Z_ZITERATOR_INLINE_HPP
26
27 #include "gc/z/zIterator.hpp"
28
29 #include "gc/z/zVerify.hpp"
30 #include "memory/iterator.inline.hpp"
31 #include "oops/objArrayOop.hpp"
32 #include "oops/oop.inline.hpp"
33
34 inline bool ZIterator::is_invisible_object(oop obj) {
35 // This is a good place to make sure that we can't concurrently iterate over
36 // objects while VMThread operations think they have exclusive access to the
37 // object graph.
38 //
39 // One example that have caused problems is the JFR Leak Profiler, which
40 // sets the mark word to a value that makes the object arrays look like
41 // invisible objects.
42 z_verify_safepoints_are_blocked();
43
44 return obj->mark_acquire().is_marked();
45 }
46
47 inline bool ZIterator::is_invisible_object_array(oop obj) {
48 return obj->klass()->is_objArray_klass() && is_invisible_object(obj);
49 }
50
51 // This iterator skips invisible object arrays
52 template <typename OopClosureT>
53 void ZIterator::oop_iterate_safe(oop obj, OopClosureT* cl) {
54 // Skip invisible object arrays - we only filter out *object* arrays,
55 // because that check is arguably faster than the is_invisible_object
56 // check, and primitive arrays are cheap to call oop_iterate on.
57 if (!is_invisible_object_array(obj)) {
58 obj->oop_iterate(cl);
59 }
60 }
61
62 template <typename OopClosureT>
63 void ZIterator::oop_iterate(oop obj, OopClosureT* cl) {
64 assert(!is_invisible_object_array(obj), "not safe");
65 obj->oop_iterate(cl);
66 }
67
68 template <typename OopClosureT>
69 void ZIterator::oop_iterate_range(objArrayOop obj, OopClosureT* cl, int start, int end) {
70 assert(!is_invisible_object_array(obj), "not safe");
71 obj->oop_iterate_range(cl, start, end);
72 }
73
74 template <typename Function>
75 class ZBasicOopIterateClosure : public BasicOopIterateClosure {
76 private:
77 Function _function;
78
79 public:
80 ZBasicOopIterateClosure(Function function)
81 : _function(function) {}
82
83 virtual void do_oop(oop* p) {
84 _function((volatile zpointer*)p);
85 }
86
87 virtual void do_oop(narrowOop* p_) {
88 ShouldNotReachHere();
89 }
90 };
91
92 // This function skips invisible roots
93 template <typename Function>
94 void ZIterator::basic_oop_iterate_safe(oop obj, Function function) {
95 ZBasicOopIterateClosure<Function> cl(function);
96 oop_iterate_safe(obj, &cl);
97 }
98
99 template <typename Function>
100 void ZIterator::basic_oop_iterate(oop obj, Function function) {
101 ZBasicOopIterateClosure<Function> cl(function);
102 oop_iterate(obj, &cl);
103 }
104
105 template <typename Function>
106 ZObjectClosure<Function>::ZObjectClosure(Function function)
107 : _function(function) {}
108
109 template <typename Function>
110 void ZObjectClosure<Function>::do_object(oop obj) {
111 _function(obj);
112 }
113
114 #endif // SHARE_GC_Z_ZITERATOR_INLINE_HPP