1 /*
2 * Copyright (c) 2003, 2017, 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/classLoaderData.inline.hpp"
27 #include "classfile/sharedClassUtil.hpp"
28 #include "classfile/dictionary.hpp"
29 #include "classfile/protectionDomainCache.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/systemDictionaryShared.hpp"
32 #include "logging/log.hpp"
33 #include "logging/logStream.hpp"
34 #include "memory/iterator.hpp"
35 #include "memory/resourceArea.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "runtime/orderAccess.inline.hpp"
38 #include "utilities/hashtable.inline.hpp"
39
40 DictionaryEntry* Dictionary::_current_class_entry = NULL;
41 int Dictionary::_current_class_index = 0;
42
43 size_t Dictionary::entry_size() {
44 if (DumpSharedSpaces) {
45 return SystemDictionaryShared::dictionary_entry_size();
46 } else {
47 return sizeof(DictionaryEntry);
48 }
49 }
50
51 Dictionary::Dictionary(int table_size)
52 : TwoOopHashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size()) {
53 _current_class_index = 0;
54 _current_class_entry = NULL;
55 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
56 };
57
58
59 Dictionary::Dictionary(int table_size, HashtableBucket<mtClass>* t,
60 int number_of_entries)
61 : TwoOopHashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size(), t, number_of_entries) {
62 _current_class_index = 0;
63 _current_class_entry = NULL;
64 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
65 };
66
67 ProtectionDomainCacheEntry* Dictionary::cache_get(Handle protection_domain) {
68 return _pd_cache_table->get(protection_domain);
69 }
70
71 DictionaryEntry* Dictionary::new_entry(unsigned int hash, InstanceKlass* klass,
72 ClassLoaderData* loader_data) {
73 DictionaryEntry* entry = (DictionaryEntry*)Hashtable<InstanceKlass*, mtClass>::new_entry(hash, klass);
74 entry->set_loader_data(loader_data);
75 entry->set_pd_set(NULL);
76 assert(klass->is_instance_klass(), "Must be");
77 if (DumpSharedSpaces) {
78 SystemDictionaryShared::init_shared_dictionary_entry(klass, entry);
79 }
80 return entry;
81 }
82
83
84 void Dictionary::free_entry(DictionaryEntry* entry) {
85 // avoid recursion when deleting linked list
86 while (entry->pd_set() != NULL) {
87 ProtectionDomainEntry* to_delete = entry->pd_set();
88 entry->set_pd_set(to_delete->next());
89 delete to_delete;
90 }
91 Hashtable<InstanceKlass*, mtClass>::free_entry(entry);
92 }
93
94
95 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
96 #ifdef ASSERT
97 if (protection_domain == klass()->protection_domain()) {
98 // Ensure this doesn't show up in the pd_set (invariant)
99 bool in_pd_set = false;
100 for (ProtectionDomainEntry* current = _pd_set;
101 current != NULL;
102 current = current->next()) {
103 if (current->protection_domain() == protection_domain) {
104 in_pd_set = true;
105 break;
106 }
107 }
108 if (in_pd_set) {
109 assert(false, "A klass's protection domain should not show up "
110 "in its sys. dict. PD set");
111 }
112 }
113 #endif /* ASSERT */
114
115 if (protection_domain == klass()->protection_domain()) {
116 // Succeeds trivially
117 return true;
118 }
119
120 for (ProtectionDomainEntry* current = _pd_set;
121 current != NULL;
122 current = current->next()) {
123 if (current->protection_domain() == protection_domain) return true;
124 }
125 return false;
126 }
127
128
129 void DictionaryEntry::add_protection_domain(Dictionary* dict, Handle protection_domain) {
130 assert_locked_or_safepoint(SystemDictionary_lock);
131 if (!contains_protection_domain(protection_domain())) {
132 ProtectionDomainCacheEntry* entry = dict->cache_get(protection_domain);
133 ProtectionDomainEntry* new_head =
134 new ProtectionDomainEntry(entry, _pd_set);
135 // Warning: Preserve store ordering. The SystemDictionary is read
136 // without locks. The new ProtectionDomainEntry must be
137 // complete before other threads can be allowed to see it
138 // via a store to _pd_set.
139 OrderAccess::release_store_ptr(&_pd_set, new_head);
140 }
141 LogTarget(Trace, protectiondomain) lt;
142 if (lt.is_enabled()) {
143 LogStream ls(lt);
144 print_count(&ls);
145 }
146 }
147
148
149 void Dictionary::do_unloading() {
150 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
151
152 // Remove unloadable entries and classes from system dictionary
153 DictionaryEntry* probe = NULL;
154 for (int index = 0; index < table_size(); index++) {
155 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
156 probe = *p;
157 Klass* e = probe->klass();
158 ClassLoaderData* loader_data = probe->loader_data();
159
160 InstanceKlass* ik = InstanceKlass::cast(e);
161
162 // Only unload classes that are not strongly reachable
163 if (!is_strongly_reachable(loader_data, e)) {
164 // Entry was not visited in phase1 (negated test from phase1)
165 assert(!loader_data->is_the_null_class_loader_data(), "unloading entry with null class loader");
166 ClassLoaderData* k_def_class_loader_data = ik->class_loader_data();
167
168 // Do we need to delete this system dictionary entry?
169 bool purge_entry = false;
170
171 // Do we need to delete this system dictionary entry?
172 if (loader_data->is_unloading()) {
173 // If the loader is not live this entry should always be
174 // removed (will never be looked up again).
175 purge_entry = true;
176 } else {
177 // The loader in this entry is alive. If the klass is dead,
178 // (determined by checking the defining class loader)
179 // the loader must be an initiating loader (rather than the
180 // defining loader). Remove this entry.
181 if (k_def_class_loader_data->is_unloading()) {
182 // If we get here, the class_loader_data must not be the defining
183 // loader, it must be an initiating one.
184 assert(k_def_class_loader_data != loader_data,
185 "cannot have live defining loader and unreachable klass");
186 // Loader is live, but class and its defining loader are dead.
187 // Remove the entry. The class is going away.
188 purge_entry = true;
189 }
190 }
191
192 if (purge_entry) {
193 *p = probe->next();
194 if (probe == _current_class_entry) {
195 _current_class_entry = NULL;
196 }
197 free_entry(probe);
198 continue;
199 }
200 }
201 p = probe->next_addr();
202 }
203 }
204 }
205
206 void Dictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
207 // Do strong roots marking if the closures are the same.
208 if (strong == weak || !ClassUnloading) {
209 // Only the protection domain oops contain references into the heap. Iterate
210 // over all of them.
211 _pd_cache_table->oops_do(strong);
212 } else {
213 if (weak != NULL) {
214 _pd_cache_table->oops_do(weak);
215 }
216 }
217 }
218
219
220 void Dictionary::remove_classes_in_error_state() {
221 assert(DumpSharedSpaces, "supported only when dumping");
222 DictionaryEntry* probe = NULL;
223 for (int index = 0; index < table_size(); index++) {
224 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
225 probe = *p;
226 InstanceKlass* ik = InstanceKlass::cast(probe->klass());
227 if (ik->is_in_error_state()) { // purge this entry
228 *p = probe->next();
229 if (probe == _current_class_entry) {
230 _current_class_entry = NULL;
231 }
232 free_entry(probe);
233 ResourceMark rm;
234 tty->print_cr("Preload Warning: Removed error class: %s", ik->external_name());
235 continue;
236 }
237
238 p = probe->next_addr();
239 }
240 }
241 }
242
243 // Just the classes from defining class loaders
244 void Dictionary::classes_do(void f(Klass*)) {
245 for (int index = 0; index < table_size(); index++) {
246 for (DictionaryEntry* probe = bucket(index);
247 probe != NULL;
248 probe = probe->next()) {
249 Klass* k = probe->klass();
250 if (probe->loader_data() == k->class_loader_data()) {
251 f(k);
252 }
253 }
254 }
255 }
256
257 // Added for initialize_itable_for_klass to handle exceptions
258 // Just the classes from defining class loaders
259 void Dictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
260 for (int index = 0; index < table_size(); index++) {
261 for (DictionaryEntry* probe = bucket(index);
262 probe != NULL;
263 probe = probe->next()) {
264 Klass* k = probe->klass();
265 if (probe->loader_data() == k->class_loader_data()) {
266 f(k, CHECK);
267 }
268 }
269 }
270 }
271
272 // All classes, and their class loaders
273 // Don't iterate over placeholders
274 void Dictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
275 for (int index = 0; index < table_size(); index++) {
276 for (DictionaryEntry* probe = bucket(index);
277 probe != NULL;
278 probe = probe->next()) {
279 Klass* k = probe->klass();
280 f(k, probe->loader_data());
281 }
282 }
283 }
284
285 void Dictionary::oops_do(OopClosure* f) {
286 // Only the protection domain oops contain references into the heap. Iterate
287 // over all of them.
288 _pd_cache_table->oops_do(f);
289 }
290
291 void Dictionary::unlink(BoolObjectClosure* is_alive) {
292 // Only the protection domain cache table may contain references to the heap
293 // that need to be unlinked.
294 _pd_cache_table->unlink(is_alive);
295 }
296
297 InstanceKlass* Dictionary::try_get_next_class() {
298 while (true) {
299 if (_current_class_entry != NULL) {
300 InstanceKlass* k = _current_class_entry->klass();
301 _current_class_entry = _current_class_entry->next();
302 return k;
303 }
304 _current_class_index = (_current_class_index + 1) % table_size();
305 _current_class_entry = bucket(_current_class_index);
306 }
307 // never reached
308 }
309
310 // Add a loaded class to the system dictionary.
311 // Readers of the SystemDictionary aren't always locked, so _buckets
312 // is volatile. The store of the next field in the constructor is
313 // also cast to volatile; we do this to ensure store order is maintained
314 // by the compilers.
315
316 void Dictionary::add_klass(Symbol* class_name, ClassLoaderData* loader_data,
317 InstanceKlass* obj) {
318 assert_locked_or_safepoint(SystemDictionary_lock);
319 assert(obj != NULL, "adding NULL obj");
320 assert(obj->name() == class_name, "sanity check on name");
321 assert(loader_data != NULL, "Must be non-NULL");
322
323 unsigned int hash = compute_hash(class_name, loader_data);
324 int index = hash_to_index(hash);
325 DictionaryEntry* entry = new_entry(hash, obj, loader_data);
326 add_entry(index, entry);
327 }
328
329
330 // This routine does not lock the system dictionary.
331 //
332 // Since readers don't hold a lock, we must make sure that system
333 // dictionary entries are only removed at a safepoint (when only one
334 // thread is running), and are added to in a safe way (all links must
335 // be updated in an MT-safe manner).
336 //
337 // Callers should be aware that an entry could be added just after
338 // _buckets[index] is read here, so the caller will not see the new entry.
339 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
340 Symbol* class_name,
341 ClassLoaderData* loader_data) {
342 for (DictionaryEntry* entry = bucket(index);
343 entry != NULL;
344 entry = entry->next()) {
345 if (entry->hash() == hash && entry->equals(class_name, loader_data)) {
346 return entry;
347 }
348 }
349 return NULL;
350 }
351
352
353 InstanceKlass* Dictionary::find(int index, unsigned int hash, Symbol* name,
354 ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
355 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
356 if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
357 return entry->klass();
358 } else {
359 return NULL;
360 }
361 }
362
363
364 InstanceKlass* Dictionary::find_class(int index, unsigned int hash,
365 Symbol* name, ClassLoaderData* loader_data) {
366 assert_locked_or_safepoint(SystemDictionary_lock);
367 assert (index == index_for(name, loader_data), "incorrect index?");
368
369 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
370 return (entry != NULL) ? entry->klass() : NULL;
371 }
372
373
374 // Variant of find_class for shared classes. No locking required, as
375 // that table is static.
376
377 InstanceKlass* Dictionary::find_shared_class(int index, unsigned int hash,
378 Symbol* name) {
379 assert (index == index_for(name, NULL), "incorrect index?");
380
381 DictionaryEntry* entry = get_entry(index, hash, name, NULL);
382 return (entry != NULL) ? entry->klass() : NULL;
383 }
384
385
386 void Dictionary::add_protection_domain(int index, unsigned int hash,
387 InstanceKlass* klass,
388 ClassLoaderData* loader_data, Handle protection_domain,
389 TRAPS) {
390 Symbol* klass_name = klass->name();
391 DictionaryEntry* entry = get_entry(index, hash, klass_name, loader_data);
392
393 assert(entry != NULL,"entry must be present, we just created it");
394 assert(protection_domain() != NULL,
395 "real protection domain should be present");
396
397 entry->add_protection_domain(this, protection_domain);
398
399 assert(entry->contains_protection_domain(protection_domain()),
400 "now protection domain should be present");
401 }
402
403
404 bool Dictionary::is_valid_protection_domain(int index, unsigned int hash,
405 Symbol* name,
406 ClassLoaderData* loader_data,
407 Handle protection_domain) {
408 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
409 return entry->is_valid_protection_domain(protection_domain);
410 }
411
412
413 void Dictionary::reorder_dictionary() {
414
415 // Copy all the dictionary entries into a single master list.
416
417 DictionaryEntry* master_list = NULL;
418 for (int i = 0; i < table_size(); ++i) {
419 DictionaryEntry* p = bucket(i);
420 while (p != NULL) {
421 DictionaryEntry* tmp;
422 tmp = p->next();
423 p->set_next(master_list);
424 master_list = p;
425 p = tmp;
426 }
427 set_entry(i, NULL);
428 }
429
430 // Add the dictionary entries back to the list in the correct buckets.
431 while (master_list != NULL) {
432 DictionaryEntry* p = master_list;
433 master_list = master_list->next();
434 p->set_next(NULL);
435 Symbol* class_name = p->klass()->name();
436 // Since the null class loader data isn't copied to the CDS archive,
437 // compute the hash with NULL for loader data.
438 unsigned int hash = compute_hash(class_name, NULL);
439 int index = hash_to_index(hash);
440 p->set_hash(hash);
441 p->set_loader_data(NULL); // loader_data isn't copied to CDS
442 p->set_next(bucket(index));
443 set_entry(index, p);
444 }
445 }
446
447
448 SymbolPropertyTable::SymbolPropertyTable(int table_size)
449 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry))
450 {
451 }
452 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t,
453 int number_of_entries)
454 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)
455 {
456 }
457
458
459 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,
460 Symbol* sym,
461 intptr_t sym_mode) {
462 assert(index == index_for(sym, sym_mode), "incorrect index?");
463 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
464 if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) {
465 return p;
466 }
467 }
468 return NULL;
469 }
470
471
472 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,
473 Symbol* sym, intptr_t sym_mode) {
474 assert_locked_or_safepoint(SystemDictionary_lock);
475 assert(index == index_for(sym, sym_mode), "incorrect index?");
476 assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");
477
478 SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode);
479 Hashtable<Symbol*, mtSymbol>::add_entry(index, p);
480 return p;
481 }
482
483 void SymbolPropertyTable::oops_do(OopClosure* f) {
484 for (int index = 0; index < table_size(); index++) {
485 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
486 if (p->method_type() != NULL) {
487 f->do_oop(p->method_type_addr());
488 }
489 }
490 }
491 }
492
493 void SymbolPropertyTable::methods_do(void f(Method*)) {
494 for (int index = 0; index < table_size(); index++) {
495 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
496 Method* prop = p->method();
497 if (prop != NULL) {
498 f((Method*)prop);
499 }
500 }
501 }
502 }
503
504
505 // ----------------------------------------------------------------------------
506
507 void Dictionary::print(bool details) {
508 ResourceMark rm;
509
510 if (details) {
511 tty->print_cr("Java system dictionary (table_size=%d, classes=%d)",
512 table_size(), number_of_entries());
513 tty->print_cr("^ indicates that initiating loader is different from "
514 "defining loader");
515 }
516
517 for (int index = 0; index < table_size(); index++) {
518 for (DictionaryEntry* probe = bucket(index);
519 probe != NULL;
520 probe = probe->next()) {
521 Klass* e = probe->klass();
522 ClassLoaderData* loader_data = probe->loader_data();
523 bool is_defining_class =
524 (loader_data == e->class_loader_data());
525 if (details) {
526 tty->print("%4d: ", index);
527 }
528 tty->print("%s%s", ((!details) || is_defining_class) ? " " : "^",
529 e->external_name());
530
531 if (details) {
532 tty->print(", loader ");
533 if (loader_data != NULL) {
534 loader_data->print_value();
535 } else {
536 tty->print("NULL");
537 }
538 }
539 tty->cr();
540 }
541 }
542
543 if (details) {
544 tty->cr();
545 _pd_cache_table->print();
546 }
547 tty->cr();
548 }
549
550 void DictionaryEntry::verify() {
551 Klass* e = klass();
552 ClassLoaderData* cld = loader_data();
553 guarantee(e->is_instance_klass(),
554 "Verify of system dictionary failed");
555 // class loader must be present; a null class loader is the
556 // boostrap loader
557 guarantee(cld != NULL || DumpSharedSpaces ||
558 cld->class_loader() == NULL ||
559 cld->class_loader()->is_instance(),
560 "checking type of class_loader");
561 e->verify();
562 verify_protection_domain_set();
563 }
564
565 void Dictionary::verify() {
566 guarantee(number_of_entries() >= 0, "Verify of system dictionary failed");
567 verify_table<DictionaryEntry>("System Dictionary");
568 _pd_cache_table->verify();
569 }
570