1 /*
2 * Copyright (c) 2017, 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 "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/dictionary.hpp"
28 #include "classfile/protectionDomainCache.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "logging/log.hpp"
31 #include "logging/logStream.hpp"
32 #include "memory/iterator.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "oops/weakHandle.inline.hpp"
36 #include "utilities/hashtable.inline.hpp"
37
38 unsigned int ProtectionDomainCacheTable::compute_hash(Handle protection_domain) {
39 // Identity hash can safepoint, so keep protection domain in a Handle.
40 return (unsigned int)(protection_domain->identity_hash());
41 }
42
43 int ProtectionDomainCacheTable::index_for(Handle protection_domain) {
44 return hash_to_index(compute_hash(protection_domain));
45 }
46
47 ProtectionDomainCacheTable::ProtectionDomainCacheTable(int table_size)
48 : Hashtable<WeakHandle<vm_class_loader_data>, mtClass>(table_size, sizeof(ProtectionDomainCacheEntry))
49 { _dead_entries = false;
50 _total_oops_removed = 0;
51 }
52
53 void ProtectionDomainCacheTable::trigger_cleanup() {
54 MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
55 _dead_entries = true;
56 Service_lock->notify_all();
57 }
58
59 class CleanProtectionDomainEntries : public CLDClosure {
60 void do_cld(ClassLoaderData* data) {
61 Dictionary* dictionary = data->dictionary();
62 if (dictionary != NULL) {
63 dictionary->clean_cached_protection_domains();
64 }
65 }
66 };
67
68 void ProtectionDomainCacheTable::unlink() {
69 {
70 // First clean cached pd lists in loaded CLDs
71 // It's unlikely, but some loaded classes in a dictionary might
72 // point to a protection_domain that has been unloaded.
73 // The dictionary pd_set points at entries in the ProtectionDomainCacheTable.
74 MutexLocker ml(ClassLoaderDataGraph_lock);
75 MutexLocker mldict(SystemDictionary_lock); // need both.
76 CleanProtectionDomainEntries clean;
77 ClassLoaderDataGraph::loaded_cld_do(&clean);
78 }
79
80 MutexLocker ml(SystemDictionary_lock);
81 int oops_removed = 0;
82 for (int i = 0; i < table_size(); ++i) {
83 ProtectionDomainCacheEntry** p = bucket_addr(i);
84 ProtectionDomainCacheEntry* entry = bucket(i);
85 while (entry != NULL) {
86 oop pd = entry->object_no_keepalive();
87 if (pd != NULL) {
88 p = entry->next_addr();
89 } else {
90 oops_removed++;
91 LogTarget(Debug, protectiondomain, table) lt;
92 if (lt.is_enabled()) {
93 LogStream ls(lt);
94 ls.print_cr("protection domain unlinked at %d", i);
95 }
96 entry->literal().release();
97 *p = entry->next();
98 free_entry(entry);
99 }
100 entry = *p;
101 }
102 }
103 _total_oops_removed += oops_removed;
104 _dead_entries = false;
105 }
106
107 void ProtectionDomainCacheTable::print_on(outputStream* st) const {
108 assert_locked_or_safepoint(SystemDictionary_lock);
109 st->print_cr("Protection domain cache table (table_size=%d, classes=%d)",
110 table_size(), number_of_entries());
111 for (int index = 0; index < table_size(); index++) {
112 for (ProtectionDomainCacheEntry* probe = bucket(index);
113 probe != NULL;
114 probe = probe->next()) {
115 st->print_cr("%4d: protection_domain: " PTR_FORMAT, index, p2i(probe->object_no_keepalive()));
116 }
117 }
118 }
119
120 void ProtectionDomainCacheTable::verify() {
121 verify_table<ProtectionDomainCacheEntry>("Protection Domain Table");
122 }
123
124 oop ProtectionDomainCacheEntry::object() {
125 return literal().resolve();
126 }
127
128 oop ProtectionDomainEntry::object() {
129 return _pd_cache->object();
130 }
131
132 // The object_no_keepalive() call peeks at the phantomly reachable oop without
133 // keeping it alive. This is okay to do in the VM thread state if it is not
134 // leaked out to become strongly reachable.
135 oop ProtectionDomainCacheEntry::object_no_keepalive() {
136 return literal().peek();
137 }
138
139 oop ProtectionDomainEntry::object_no_keepalive() {
140 return _pd_cache->object_no_keepalive();
141 }
142
143 void ProtectionDomainCacheEntry::verify() {
144 guarantee(object_no_keepalive() == NULL || oopDesc::is_oop(object_no_keepalive()), "must be an oop");
145 }
146
147 ProtectionDomainCacheEntry* ProtectionDomainCacheTable::get(Handle protection_domain) {
148 unsigned int hash = compute_hash(protection_domain);
149 int index = hash_to_index(hash);
150
151 ProtectionDomainCacheEntry* entry = find_entry(index, protection_domain);
152 if (entry == NULL) {
153 entry = add_entry(index, hash, protection_domain);
154 }
155 // keep entry alive
156 (void)entry->object();
157 return entry;
158 }
159
160 ProtectionDomainCacheEntry* ProtectionDomainCacheTable::find_entry(int index, Handle protection_domain) {
161 assert_locked_or_safepoint(SystemDictionary_lock);
162 for (ProtectionDomainCacheEntry* e = bucket(index); e != NULL; e = e->next()) {
163 if (e->object_no_keepalive() == protection_domain()) {
164 return e;
165 }
166 }
167
168 return NULL;
169 }
170
171 ProtectionDomainCacheEntry* ProtectionDomainCacheTable::add_entry(int index, unsigned int hash, Handle protection_domain) {
172 assert_locked_or_safepoint(SystemDictionary_lock);
173 assert(index == index_for(protection_domain), "incorrect index?");
174 assert(find_entry(index, protection_domain) == NULL, "no double entry");
175
176 LogTarget(Debug, protectiondomain, table) lt;
177 if (lt.is_enabled()) {
178 LogStream ls(lt);
179 ls.print("protection domain added ");
180 protection_domain->print_value_on(&ls);
181 ls.cr();
182 }
183 WeakHandle<vm_class_loader_data> w = WeakHandle<vm_class_loader_data>::create(protection_domain);
184 ProtectionDomainCacheEntry* p = new_entry(hash, w);
185 Hashtable<WeakHandle<vm_class_loader_data>, mtClass>::add_entry(index, p);
186 return p;
187 }