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
21 * questions.
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/refArrayOop.hpp"
33 #include "oops/oop.inline.hpp"
34
35 inline bool ZIterator::is_invisible_object(oop obj) {
36 // This is a good place to make sure that we can't concurrently iterate over
37 // objects while VMThread operations think they have exclusive access to the
38 // object graph.
39 //
40 // One example that have caused problems is the JFR Leak Profiler, which
41 // sets the mark word to a value that makes the object arrays look like
42 // invisible objects.
43 z_verify_safepoints_are_blocked();
44
45 return obj->mark_acquire().is_marked();
46 }
47
48 inline bool ZIterator::is_invisible_object_array(oop obj) {
49 return obj->klass()->is_refArray_klass() && is_invisible_object(obj);
50 }
51
52 // This iterator skips invisible object arrays
53 template <typename OopClosureT>
54 void ZIterator::oop_iterate_safe(oop obj, OopClosureT* cl) {
55 // Skip invisible object arrays - we only filter out *object* arrays,
56 // because that check is arguably faster than the is_invisible_object
57 // check, and primitive arrays are cheap to call oop_iterate on.
58 if (!is_invisible_object_array(obj)) {
59 obj->oop_iterate(cl);
60 }
61 }
62
63 template <typename OopClosureT>
64 void ZIterator::oop_iterate(oop obj, OopClosureT* cl) {
65 assert(!is_invisible_object_array(obj), "not safe");
66 obj->oop_iterate(cl);
67 }
68
69 template <typename OopClosureT>
70 void ZIterator::oop_iterate_range(objArrayOop obj, OopClosureT* cl, int start, int end) {
71 assert(!is_invisible_object_array(obj), "not safe");
72 assert(obj->is_refArray(), "Must be");
73 refArrayOop(obj)->oop_iterate_range(cl, start, end);
74 }
75
76 template <typename Function>
77 class ZBasicOopIterateClosure : public BasicOopIterateClosure {
78 private:
79 Function _function;
80
81 public:
82 ZBasicOopIterateClosure(Function function)
83 : _function(function) {}
84
85 virtual void do_oop(oop* p) {
86 _function((volatile zpointer*)p);
87 }
88
89 virtual void do_oop(narrowOop* p_) {
90 ShouldNotReachHere();
91 }
92 };
93
94 // This function skips invisible roots
95 template <typename Function>
96 void ZIterator::basic_oop_iterate_safe(oop obj, Function function) {
97 ZBasicOopIterateClosure<Function> cl(function);
98 oop_iterate_safe(obj, &cl);
99 }
100
101 template <typename Function>
102 void ZIterator::basic_oop_iterate(oop obj, Function function) {
103 ZBasicOopIterateClosure<Function> cl(function);
104 oop_iterate(obj, &cl);
105 }
106
107 template <typename Function>
108 ZObjectClosure<Function>::ZObjectClosure(Function function)
109 : _function(function) {}
110
111 template <typename Function>
112 void ZObjectClosure<Function>::do_object(oop obj) {
113 _function(obj);
114 }
115
116 #endif // SHARE_GC_Z_ZITERATOR_INLINE_HPP