1 /*
2 * Copyright (c) 2013, 2016, 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 "classfile/metadataOnStackMark.hpp"
27 #include "code/codeCache.hpp"
28 #include "compiler/compileBroker.hpp"
29 #include "oops/metadata.hpp"
30 #include "prims/jvmtiImpl.hpp"
31 #include "runtime/synchronizer.hpp"
32 #include "runtime/thread.hpp"
33 #include "services/threadService.hpp"
34 #include "utilities/chunkedList.hpp"
35 #if INCLUDE_JVMCI
36 #include "jvmci/jvmciRuntime.hpp"
37 #endif
38
39 MetadataOnStackBuffer* MetadataOnStackMark::_used_buffers = NULL;
40 MetadataOnStackBuffer* MetadataOnStackMark::_free_buffers = NULL;
41
42 MetadataOnStackBuffer* MetadataOnStackMark::_current_buffer = NULL;
43 NOT_PRODUCT(bool MetadataOnStackMark::_is_active = false;)
44
45 // Walk metadata on the stack and mark it so that redefinition doesn't delete
46 // it. Class unloading only deletes in-error class files, methods created by
47 // the relocator and dummy constant pools. None of these appear anywhere except
48 // in metadata Handles.
49 MetadataOnStackMark::MetadataOnStackMark(bool redefinition_walk) {
50 assert(_used_buffers == NULL, "sanity check");
51 assert(!_is_active, "MetadataOnStackMarks do not nest");
52 NOT_PRODUCT(_is_active = true;)
53
54 if (!UseZGC) {
55 assert(SafepointSynchronize::is_at_safepoint(), "sanity check");
56 Threads::metadata_handles_do(Metadata::mark_on_stack);
57 }
58
59 if (redefinition_walk) {
60 Threads::metadata_do(Metadata::mark_on_stack);
61 CodeCache::metadata_do(Metadata::mark_on_stack);
62 CompileBroker::mark_on_stack();
63 JvmtiCurrentBreakpoints::metadata_do(Metadata::mark_on_stack);
64 ThreadService::metadata_do(Metadata::mark_on_stack);
65 #if INCLUDE_JVMCI
66 JVMCIRuntime::metadata_do(Metadata::mark_on_stack);
67 #endif
68 }
69 }
70
71 MetadataOnStackMark::~MetadataOnStackMark() {
72 assert(SafepointSynchronize::is_at_safepoint() || UseZGC, "sanity check");
73 // Unmark everything that was marked. Can't do the same walk because
74 // redefine classes messes up the code cache so the set of methods
75 // might not be the same.
76 retire_current_buffer();
77
78 MetadataOnStackBuffer* buffer = _used_buffers;
79 while (buffer != NULL) {
80 // Clear on stack state for all metadata.
81 size_t size = buffer->size();
82 for (size_t i = 0; i < size; i++) {
83 Metadata* md = buffer->at(i);
84 md->set_on_stack(false);
85 }
86
87 MetadataOnStackBuffer* next = buffer->next_used();
88
89 // Move the buffer to the free list.
90 buffer->clear();
91 buffer->set_next_used(NULL);
92 buffer->set_next_free(_free_buffers);
93 _free_buffers = buffer;
94
95 // Step to next used buffer.
96 buffer = next;
97 }
98
99 _used_buffers = NULL;
100
101 NOT_PRODUCT(_is_active = false;)
102 }
103
104 void MetadataOnStackMark::retire_buffer(MetadataOnStackBuffer* buffer) {
105 if (buffer == NULL) {
106 return;
107 }
108 buffer->set_next_used(_used_buffers);
109 _used_buffers = buffer;
110 }
111
112 // Current buffer is full or we're ready to walk them, add it to the used list.
113 void MetadataOnStackMark::retire_current_buffer() {
114 retire_buffer(_current_buffer);
115 _current_buffer = NULL;
116 }
117
118 // Get buffer off free list.
119 MetadataOnStackBuffer* MetadataOnStackMark::allocate_buffer() {
120 MetadataOnStackBuffer* allocated = _free_buffers;
121
122 if (allocated != NULL) {
123 _free_buffers = allocated->next_free();
124 }
125
126 if (allocated == NULL) {
127 allocated = new MetadataOnStackBuffer();
128 }
129
130 assert(!allocated->is_full(), "Should not be full: " PTR_FORMAT, p2i(allocated));
131
132 return allocated;
133 }
134
135 // Record which objects are marked so we can unmark the same objects.
136 void MetadataOnStackMark::record(Metadata* m) {
137 assert(_is_active, "metadata on stack marking is active");
138
139 MetadataOnStackBuffer* buffer = _current_buffer;
140
141 if (buffer != NULL && buffer->is_full()) {
142 retire_buffer(buffer);
143 buffer = NULL;
144 }
145
146 if (buffer == NULL) {
147 buffer = allocate_buffer();
148 _current_buffer = buffer;
149 }
150
151 buffer->push(m);
152 }