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 "memory/iterator.hpp"
33 #include "memory/metaspaceClosure.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "oops/oop.inline.hpp"
36 #include "runtime/orderAccess.inline.hpp"
37 #include "utilities/hashtable.inline.hpp"
38
39 DictionaryEntry* Dictionary::_current_class_entry = NULL;
40 int Dictionary::_current_class_index = 0;
41
42 size_t Dictionary::entry_size() {
43 if (DumpSharedSpaces) {
44 return SystemDictionaryShared::dictionary_entry_size();
45 } else {
46 return sizeof(DictionaryEntry);
47 }
48 }
49
50 Dictionary::Dictionary(int table_size)
51 : TwoOopHashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size()) {
52 _current_class_index = 0;
53 _current_class_entry = NULL;
54 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
55 };
56
57
58 Dictionary::Dictionary(int table_size, HashtableBucket<mtClass>* t,
59 int number_of_entries)
60 : TwoOopHashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size(), t, number_of_entries) {
61 _current_class_index = 0;
62 _current_class_entry = NULL;
63 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
64 };
65
66 ProtectionDomainCacheEntry* Dictionary::cache_get(Handle protection_domain) {
67 return _pd_cache_table->get(protection_domain);
68 }
69
70 DictionaryEntry* Dictionary::new_entry(unsigned int hash, InstanceKlass* klass,
71 ClassLoaderData* loader_data) {
72 DictionaryEntry* entry = (DictionaryEntry*)Hashtable<InstanceKlass*, mtClass>::new_entry(hash, klass);
73 entry->set_loader_data(loader_data);
74 entry->set_pd_set(NULL);
75 assert(klass->is_instance_klass(), "Must be");
76 if (DumpSharedSpaces) {
77 SystemDictionaryShared::init_shared_dictionary_entry(klass, entry);
78 }
79 return entry;
80 }
81
82
83 void Dictionary::free_entry(DictionaryEntry* entry) {
84 // avoid recursion when deleting linked list
85 while (entry->pd_set() != NULL) {
86 ProtectionDomainEntry* to_delete = entry->pd_set();
87 entry->set_pd_set(to_delete->next());
88 delete to_delete;
89 }
90 Hashtable<InstanceKlass*, mtClass>::free_entry(entry);
91 }
92
93
94 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
95 #ifdef ASSERT
96 if (protection_domain == klass()->protection_domain()) {
97 // Ensure this doesn't show up in the pd_set (invariant)
98 bool in_pd_set = false;
99 for (ProtectionDomainEntry* current = _pd_set;
100 current != NULL;
101 current = current->next()) {
102 if (current->protection_domain() == protection_domain) {
103 in_pd_set = true;
104 break;
105 }
106 }
107 if (in_pd_set) {
108 assert(false, "A klass's protection domain should not show up "
109 "in its sys. dict. PD set");
110 }
111 }
112 #endif /* ASSERT */
113
114 if (protection_domain == klass()->protection_domain()) {
115 // Succeeds trivially
116 return true;
117 }
118
119 for (ProtectionDomainEntry* current = _pd_set;
120 current != NULL;
121 current = current->next()) {
122 if (current->protection_domain() == protection_domain) return true;
123 }
124 return false;
125 }
126
127
128 void DictionaryEntry::add_protection_domain(Dictionary* dict, Handle protection_domain) {
129 assert_locked_or_safepoint(SystemDictionary_lock);
130 if (!contains_protection_domain(protection_domain())) {
131 ProtectionDomainCacheEntry* entry = dict->cache_get(protection_domain);
132 ProtectionDomainEntry* new_head =
133 new ProtectionDomainEntry(entry, _pd_set);
134 // Warning: Preserve store ordering. The SystemDictionary is read
135 // without locks. The new ProtectionDomainEntry must be
136 // complete before other threads can be allowed to see it
137 // via a store to _pd_set.
138 OrderAccess::release_store_ptr(&_pd_set, new_head);
139 }
140 if (log_is_enabled(Trace, protectiondomain)) {
141 ResourceMark rm;
142 outputStream* log = Log(protectiondomain)::trace_stream();
143 print_count(log);
144 }
145 }
146
147
148 void Dictionary::do_unloading() {
149 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
150
151 // Remove unloadable entries and classes from system dictionary
152 DictionaryEntry* probe = NULL;
153 for (int index = 0; index < table_size(); index++) {
154 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
155 probe = *p;
156 Klass* e = probe->klass();
157 ClassLoaderData* loader_data = probe->loader_data();
158
159 InstanceKlass* ik = InstanceKlass::cast(e);
160
161 // Only unload classes that are not strongly reachable
162 if (!is_strongly_reachable(loader_data, e)) {
163 // Entry was not visited in phase1 (negated test from phase1)
164 assert(!loader_data->is_the_null_class_loader_data(), "unloading entry with null class loader");
165 ClassLoaderData* k_def_class_loader_data = ik->class_loader_data();
166
167 // Do we need to delete this system dictionary entry?
168 bool purge_entry = false;
169
170 // Do we need to delete this system dictionary entry?
171 if (loader_data->is_unloading()) {
172 // If the loader is not live this entry should always be
173 // removed (will never be looked up again).
174 purge_entry = true;
175 } else {
176 // The loader in this entry is alive. If the klass is dead,
177 // (determined by checking the defining class loader)
178 // the loader must be an initiating loader (rather than the
179 // defining loader). Remove this entry.
180 if (k_def_class_loader_data->is_unloading()) {
181 // If we get here, the class_loader_data must not be the defining
182 // loader, it must be an initiating one.
183 assert(k_def_class_loader_data != loader_data,
184 "cannot have live defining loader and unreachable klass");
185 // Loader is live, but class and its defining loader are dead.
186 // Remove the entry. The class is going away.
187 purge_entry = true;
188 }
189 }
190
191 if (purge_entry) {
192 *p = probe->next();
193 if (probe == _current_class_entry) {
194 _current_class_entry = NULL;
195 }
196 free_entry(probe);
197 continue;
198 }
199 }
200 p = probe->next_addr();
201 }
202 }
203 }
204
205 void Dictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
206 // Do strong roots marking if the closures are the same.
207 if (strong == weak || !ClassUnloading) {
208 // Only the protection domain oops contain references into the heap. Iterate
209 // over all of them.
210 _pd_cache_table->oops_do(strong);
211 } else {
212 if (weak != NULL) {
213 _pd_cache_table->oops_do(weak);
214 }
215 }
216 }
217
218
219 void Dictionary::remove_classes_in_error_state() {
220 assert(DumpSharedSpaces, "supported only when dumping");
221 DictionaryEntry* probe = NULL;
222 for (int index = 0; index < table_size(); index++) {
223 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
224 probe = *p;
225 InstanceKlass* ik = InstanceKlass::cast(probe->klass());
226 if (ik->is_in_error_state()) { // purge this entry
227 *p = probe->next();
228 if (probe == _current_class_entry) {
229 _current_class_entry = NULL;
230 }
231 free_entry(probe);
232 ResourceMark rm;
233 tty->print_cr("Preload Warning: Removed error class: %s", ik->external_name());
234 continue;
235 }
236
237 p = probe->next_addr();
238 }
239 }
240 }
241
242 // Just the classes from defining class loaders
243 void Dictionary::classes_do(void f(Klass*)) {
244 for (int index = 0; index < table_size(); index++) {
245 for (DictionaryEntry* probe = bucket(index);
246 probe != NULL;
247 probe = probe->next()) {
248 Klass* k = probe->klass();
249 if (probe->loader_data() == k->class_loader_data()) {
250 f(k);
251 }
252 }
253 }
254 }
255
256 // Added for initialize_itable_for_klass to handle exceptions
257 // Just the classes from defining class loaders
258 void Dictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
259 for (int index = 0; index < table_size(); index++) {
260 for (DictionaryEntry* probe = bucket(index);
261 probe != NULL;
262 probe = probe->next()) {
263 Klass* k = probe->klass();
264 if (probe->loader_data() == k->class_loader_data()) {
265 f(k, CHECK);
266 }
267 }
268 }
269 }
270
271 // All classes, and their class loaders
272 // Don't iterate over placeholders
273 void Dictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
274 for (int index = 0; index < table_size(); index++) {
275 for (DictionaryEntry* probe = bucket(index);
276 probe != NULL;
277 probe = probe->next()) {
278 Klass* k = probe->klass();
279 f(k, probe->loader_data());
280 }
281 }
282 }
283
284 // Used to scan and relocate the classes during CDS archive dump.
285 void Dictionary::classes_do(MetaspaceClosure* it) {
286 for (int index = 0; index < table_size(); index++) {
287 for (DictionaryEntry* probe = bucket(index);
288 probe != NULL;
289 probe = probe->next()) {
290 it->push(probe->klass_addr());
291 if (DumpSharedSpaces) {
292 ((SharedDictionaryEntry*)probe)->metaspace_pointers_do(it);
293 }
294 }
295 }
296 }
297
298
299 void Dictionary::oops_do(OopClosure* f) {
300 // Only the protection domain oops contain references into the heap. Iterate
301 // over all of them.
302 _pd_cache_table->oops_do(f);
303 }
304
305 void Dictionary::unlink(BoolObjectClosure* is_alive) {
306 // Only the protection domain cache table may contain references to the heap
307 // that need to be unlinked.
308 _pd_cache_table->unlink(is_alive);
309 }
310
311 InstanceKlass* Dictionary::try_get_next_class() {
312 while (true) {
313 if (_current_class_entry != NULL) {
314 InstanceKlass* k = _current_class_entry->klass();
315 _current_class_entry = _current_class_entry->next();
316 return k;
317 }
318 _current_class_index = (_current_class_index + 1) % table_size();
319 _current_class_entry = bucket(_current_class_index);
320 }
321 // never reached
322 }
323
324 // Add a loaded class to the system dictionary.
325 // Readers of the SystemDictionary aren't always locked, so _buckets
326 // is volatile. The store of the next field in the constructor is
327 // also cast to volatile; we do this to ensure store order is maintained
328 // by the compilers.
329
330 void Dictionary::add_klass(Symbol* class_name, ClassLoaderData* loader_data,
331 InstanceKlass* obj) {
332 assert_locked_or_safepoint(SystemDictionary_lock);
333 assert(obj != NULL, "adding NULL obj");
334 assert(obj->name() == class_name, "sanity check on name");
335 assert(loader_data != NULL, "Must be non-NULL");
336
337 unsigned int hash = compute_hash(class_name, loader_data);
338 int index = hash_to_index(hash);
339 DictionaryEntry* entry = new_entry(hash, obj, loader_data);
340 add_entry(index, entry);
341 }
342
343
344 // This routine does not lock the system dictionary.
345 //
346 // Since readers don't hold a lock, we must make sure that system
347 // dictionary entries are only removed at a safepoint (when only one
348 // thread is running), and are added to in a safe way (all links must
349 // be updated in an MT-safe manner).
350 //
351 // Callers should be aware that an entry could be added just after
352 // _buckets[index] is read here, so the caller will not see the new entry.
353 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
354 Symbol* class_name,
355 ClassLoaderData* loader_data) {
356 for (DictionaryEntry* entry = bucket(index);
357 entry != NULL;
358 entry = entry->next()) {
359 if (entry->hash() == hash && entry->equals(class_name, loader_data)) {
360 return entry;
361 }
362 }
363 return NULL;
364 }
365
366
367 InstanceKlass* Dictionary::find(int index, unsigned int hash, Symbol* name,
368 ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
369 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
370 if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
371 return entry->klass();
372 } else {
373 return NULL;
374 }
375 }
376
377
378 InstanceKlass* Dictionary::find_class(int index, unsigned int hash,
379 Symbol* name, ClassLoaderData* loader_data) {
380 assert_locked_or_safepoint(SystemDictionary_lock);
381 assert (index == index_for(name, loader_data), "incorrect index?");
382
383 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
384 return (entry != NULL) ? entry->klass() : NULL;
385 }
386
387
388 // Variant of find_class for shared classes. No locking required, as
389 // that table is static.
390
391 InstanceKlass* Dictionary::find_shared_class(int index, unsigned int hash,
392 Symbol* name) {
393 assert (index == index_for(name, NULL), "incorrect index?");
394
395 DictionaryEntry* entry = get_entry(index, hash, name, NULL);
396 return (entry != NULL) ? entry->klass() : NULL;
397 }
398
399
400 void Dictionary::add_protection_domain(int index, unsigned int hash,
401 InstanceKlass* klass,
402 ClassLoaderData* loader_data, Handle protection_domain,
403 TRAPS) {
404 Symbol* klass_name = klass->name();
405 DictionaryEntry* entry = get_entry(index, hash, klass_name, loader_data);
406
407 assert(entry != NULL,"entry must be present, we just created it");
408 assert(protection_domain() != NULL,
409 "real protection domain should be present");
410
411 entry->add_protection_domain(this, protection_domain);
412
413 assert(entry->contains_protection_domain(protection_domain()),
414 "now protection domain should be present");
415 }
416
417
418 bool Dictionary::is_valid_protection_domain(int index, unsigned int hash,
419 Symbol* name,
420 ClassLoaderData* loader_data,
421 Handle protection_domain) {
422 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
423 return entry->is_valid_protection_domain(protection_domain);
424 }
425
426
427 void Dictionary::reorder_dictionary_for_sharing() {
428
429 // Copy all the dictionary entries into a single master list.
430
431 DictionaryEntry* master_list = NULL;
432 for (int i = 0; i < table_size(); ++i) {
433 DictionaryEntry* p = bucket(i);
434 while (p != NULL) {
435 DictionaryEntry* tmp;
436 tmp = p->next();
437 p->set_next(master_list);
438 master_list = p;
439 p = tmp;
440 }
441 set_entry(i, NULL);
442 }
443
444 // Add the dictionary entries back to the list in the correct buckets.
445 while (master_list != NULL) {
446 DictionaryEntry* p = master_list;
447 master_list = master_list->next();
448 p->set_next(NULL);
449 Symbol* class_name = p->klass()->name();
450 // Since the null class loader data isn't copied to the CDS archive,
451 // compute the hash with NULL for loader data.
452 unsigned int hash = compute_hash(class_name, NULL);
453 int index = hash_to_index(hash);
454 p->set_hash(hash);
455 p->set_loader_data(NULL); // loader_data isn't copied to CDS
456 p->set_next(bucket(index));
457 set_entry(index, p);
458 }
459 }
460
461
462 SymbolPropertyTable::SymbolPropertyTable(int table_size)
463 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry))
464 {
465 }
466 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t,
467 int number_of_entries)
468 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)
469 {
470 }
471
472
473 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,
474 Symbol* sym,
475 intptr_t sym_mode) {
476 assert(index == index_for(sym, sym_mode), "incorrect index?");
477 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
478 if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) {
479 return p;
480 }
481 }
482 return NULL;
483 }
484
485
486 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,
487 Symbol* sym, intptr_t sym_mode) {
488 assert_locked_or_safepoint(SystemDictionary_lock);
489 assert(index == index_for(sym, sym_mode), "incorrect index?");
490 assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");
491
492 SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode);
493 Hashtable<Symbol*, mtSymbol>::add_entry(index, p);
494 return p;
495 }
496
497 void SymbolPropertyTable::oops_do(OopClosure* f) {
498 for (int index = 0; index < table_size(); index++) {
499 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
500 if (p->method_type() != NULL) {
501 f->do_oop(p->method_type_addr());
502 }
503 }
504 }
505 }
506
507 void SymbolPropertyTable::methods_do(void f(Method*)) {
508 for (int index = 0; index < table_size(); index++) {
509 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
510 Method* prop = p->method();
511 if (prop != NULL) {
512 f((Method*)prop);
513 }
514 }
515 }
516 }
517
518
519 // ----------------------------------------------------------------------------
520
521 void Dictionary::print(bool details) {
522 ResourceMark rm;
523
524 if (details) {
525 tty->print_cr("Java system dictionary (table_size=%d, classes=%d)",
526 table_size(), number_of_entries());
527 tty->print_cr("^ indicates that initiating loader is different from "
528 "defining loader");
529 }
530
531 for (int index = 0; index < table_size(); index++) {
532 for (DictionaryEntry* probe = bucket(index);
533 probe != NULL;
534 probe = probe->next()) {
535 Klass* e = probe->klass();
536 ClassLoaderData* loader_data = probe->loader_data();
537 bool is_defining_class =
538 (loader_data == e->class_loader_data());
539 if (details) {
540 tty->print("%4d: ", index);
541 }
542 tty->print("%s%s", ((!details) || is_defining_class) ? " " : "^",
543 e->external_name());
544
545 if (details) {
546 tty->print(", loader ");
547 if (loader_data != NULL) {
548 loader_data->print_value();
549 } else {
550 tty->print("NULL");
551 }
552 }
553 tty->cr();
554 }
555 }
556
557 if (details) {
558 tty->cr();
559 _pd_cache_table->print();
560 }
561 tty->cr();
562 }
563
564 void DictionaryEntry::verify() {
565 Klass* e = klass();
566 ClassLoaderData* cld = loader_data();
567 guarantee(e->is_instance_klass(),
568 "Verify of system dictionary failed");
569 // class loader must be present; a null class loader is the
570 // boostrap loader
571 guarantee(cld != NULL || DumpSharedSpaces ||
572 cld->class_loader() == NULL ||
573 cld->class_loader()->is_instance(),
574 "checking type of class_loader");
575 e->verify();
576 verify_protection_domain_set();
577 }
578
579 void Dictionary::verify() {
580 guarantee(number_of_entries() >= 0, "Verify of system dictionary failed");
581 verify_table<DictionaryEntry>("System Dictionary");
582 _pd_cache_table->verify();
583 }
584