1 /*
2 * Copyright (c) 2003, 2013, 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/dictionary.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "oops/oop.inline.hpp"
29 #include "prims/jvmtiRedefineClassesTrace.hpp"
30 #include "utilities/hashtable.inline.hpp"
31
32
33 DictionaryEntry* Dictionary::_current_class_entry = NULL;
34 int Dictionary::_current_class_index = 0;
35
36
37 Dictionary::Dictionary(int table_size)
38 : TwoOopHashtable<Klass*, mtClass>(table_size, sizeof(DictionaryEntry)) {
39 _current_class_index = 0;
40 _current_class_entry = NULL;
41 _pd_cache_table = new ProtectionDomainCacheTable(137);
42 };
43
44
45 Dictionary::Dictionary(int table_size, HashtableBucket<mtClass>* t,
46 int number_of_entries)
47 : TwoOopHashtable<Klass*, mtClass>(table_size, sizeof(DictionaryEntry), t, number_of_entries) {
48 _current_class_index = 0;
49 _current_class_entry = NULL;
50 _pd_cache_table = new ProtectionDomainCacheTable(137);
51 };
52
53 ProtectionDomainCacheEntry* Dictionary::cache_get(oop protection_domain) {
54 return _pd_cache_table->get(protection_domain);
55 }
56
57 DictionaryEntry* Dictionary::new_entry(unsigned int hash, Klass* klass,
58 ClassLoaderData* loader_data) {
59 DictionaryEntry* entry = (DictionaryEntry*)Hashtable<Klass*, mtClass>::new_entry(hash, klass);
60 entry->set_loader_data(loader_data);
61 entry->set_pd_set(NULL);
62 assert(klass->oop_is_instance(), "Must be");
63 return entry;
64 }
65
66
67 void Dictionary::free_entry(DictionaryEntry* entry) {
68 // avoid recursion when deleting linked list
69 while (entry->pd_set() != NULL) {
70 ProtectionDomainEntry* to_delete = entry->pd_set();
71 entry->set_pd_set(to_delete->next());
72 ProtectionDomainCacheEntry* cache = to_delete->release_pd_cache();
73 if (cache != NULL) {
74 _pd_cache_table->free(cache);
75 }
76 delete to_delete;
77 }
78 Hashtable<Klass*, mtClass>::free_entry(entry);
79 }
80
81
82 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
83 #ifdef ASSERT
84 if (protection_domain == InstanceKlass::cast(klass())->protection_domain()) {
85 // Ensure this doesn't show up in the pd_set (invariant)
86 bool in_pd_set = false;
87 for (ProtectionDomainEntry* current = _pd_set;
88 current != NULL;
89 current = current->next()) {
90 if (current->protection_domain() == protection_domain) {
91 in_pd_set = true;
92 break;
93 }
94 }
95 if (in_pd_set) {
96 assert(false, "A klass's protection domain should not show up "
97 "in its sys. dict. PD set");
98 }
99 }
100 #endif /* ASSERT */
101
102 if (protection_domain == InstanceKlass::cast(klass())->protection_domain()) {
103 // Succeeds trivially
104 return true;
105 }
106
107 for (ProtectionDomainEntry* current = _pd_set;
108 current != NULL;
109 current = current->next()) {
110 if (current->protection_domain() == protection_domain) return true;
111 }
112 return false;
113 }
114
115
116 void DictionaryEntry::add_protection_domain(Dictionary* dict, oop protection_domain) {
117 assert_locked_or_safepoint(SystemDictionary_lock);
118 if (!contains_protection_domain(protection_domain)) {
119 ProtectionDomainCacheEntry* entry = dict->cache_get(protection_domain);
120 ProtectionDomainEntry* new_head =
121 new ProtectionDomainEntry(entry, _pd_set);
122 // Warning: Preserve store ordering. The SystemDictionary is read
123 // without locks. The new ProtectionDomainEntry must be
124 // complete before other threads can be allowed to see it
125 // via a store to _pd_set.
126 OrderAccess::release_store_ptr(&_pd_set, new_head);
127 }
128 if (TraceProtectionDomainVerification && WizardMode) {
129 print();
130 }
131 }
132
133
134 bool Dictionary::do_unloading() {
135 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
136 bool class_was_unloaded = false;
137 int index = 0; // Defined here for portability! Do not move
138
139 // Remove unloadable entries and classes from system dictionary
140 // The placeholder array has been handled in always_strong_oops_do.
141 DictionaryEntry* probe = NULL;
142 for (index = 0; index < table_size(); index++) {
143 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
144 probe = *p;
145 Klass* e = probe->klass();
146 ClassLoaderData* loader_data = probe->loader_data();
147
148 InstanceKlass* ik = InstanceKlass::cast(e);
149
150 // Non-unloadable classes were handled in always_strong_oops_do
151 if (!is_strongly_reachable(loader_data, e)) {
152 // Entry was not visited in phase1 (negated test from phase1)
153 assert(!loader_data->is_the_null_class_loader_data(), "unloading entry with null class loader");
154 ClassLoaderData* k_def_class_loader_data = ik->class_loader_data();
155
156 // Do we need to delete this system dictionary entry?
157 bool purge_entry = false;
158
159 // Do we need to delete this system dictionary entry?
160 if (loader_data->is_unloading()) {
161 // If the loader is not live this entry should always be
162 // removed (will never be looked up again). Note that this is
163 // not the same as unloading the referred class.
164 if (k_def_class_loader_data == loader_data) {
165 // This is the defining entry, so the referred class is about
166 // to be unloaded.
167 class_was_unloaded = true;
168 }
169 // Also remove this system dictionary entry.
170 purge_entry = true;
171
172 } else {
173 // The loader in this entry is alive. If the klass is dead,
174 // (determined by checking the defining class loader)
175 // the loader must be an initiating loader (rather than the
176 // defining loader). Remove this entry.
177 if (k_def_class_loader_data->is_unloading()) {
178 // If we get here, the class_loader_data must not be the defining
179 // loader, it must be an initiating one.
180 assert(k_def_class_loader_data != loader_data,
181 "cannot have live defining loader and unreachable klass");
182 // Loader is live, but class and its defining loader are dead.
183 // Remove the entry. The class is going away.
184 purge_entry = true;
185 }
186 }
187
188 if (purge_entry) {
189 *p = probe->next();
190 if (probe == _current_class_entry) {
191 _current_class_entry = NULL;
192 }
193 free_entry(probe);
194 continue;
195 }
196 }
197 p = probe->next_addr();
198 }
199 }
200 return class_was_unloaded;
201 }
202
203
204 void Dictionary::always_strong_oops_do(OopClosure* blk) {
205 // This code is not multi-thread safe, but it should be called only
206 // by GC thread.
207 static int scan_generation = 0;
208 scan_generation++;
209 if (scan_generation == 0) {
210 // Wrapped around 32-bit. Never use 0 -- it's the initial value of
211 // ProtectionDomainCacheEntry::_scan_generation.
212 scan_generation = 1;
213 }
214
215 // Follow all system classes and temporary placeholders in dictionary
216 for (int index = 0; index < table_size(); index++) {
217 for (DictionaryEntry *probe = bucket(index);
218 probe != NULL;
219 probe = probe->next()) {
220 Klass* e = probe->klass();
221 ClassLoaderData* loader_data = probe->loader_data();
222 if (is_strongly_reachable(loader_data, e)) {
223 probe->set_strongly_reachable(scan_generation);
224 }
225 }
226 }
227
228 _pd_cache_table->always_strong_oops_do(blk, scan_generation);
229 }
230
231
232 void Dictionary::always_strong_classes_do(KlassClosure* closure) {
233 // Follow all system classes and temporary placeholders in dictionary
234 for (int index = 0; index < table_size(); index++) {
235 for (DictionaryEntry* probe = bucket(index);
236 probe != NULL;
237 probe = probe->next()) {
238 Klass* e = probe->klass();
239 ClassLoaderData* loader_data = probe->loader_data();
240 if (is_strongly_reachable(loader_data, e)) {
241 closure->do_klass(e);
242 }
243 }
244 }
245 }
246
247
248 // Just the classes from defining class loaders
249 void Dictionary::classes_do(void f(Klass*)) {
250 for (int index = 0; index < table_size(); index++) {
251 for (DictionaryEntry* probe = bucket(index);
252 probe != NULL;
253 probe = probe->next()) {
254 Klass* k = probe->klass();
255 if (probe->loader_data() == InstanceKlass::cast(k)->class_loader_data()) {
256 f(k);
257 }
258 }
259 }
260 }
261
262 // Added for initialize_itable_for_klass to handle exceptions
263 // Just the classes from defining class loaders
264 void Dictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
265 for (int index = 0; index < table_size(); index++) {
266 for (DictionaryEntry* probe = bucket(index);
267 probe != NULL;
268 probe = probe->next()) {
269 Klass* k = probe->klass();
270 if (probe->loader_data() == InstanceKlass::cast(k)->class_loader_data()) {
271 f(k, CHECK);
272 }
273 }
274 }
275 }
276
277 // All classes, and their class loaders
278 // Don't iterate over placeholders
279 void Dictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
280 for (int index = 0; index < table_size(); index++) {
281 for (DictionaryEntry* probe = bucket(index);
282 probe != NULL;
283 probe = probe->next()) {
284 Klass* k = probe->klass();
285 f(k, probe->loader_data());
286 }
287 }
288 }
289
290 void Dictionary::oops_do(OopClosure* f) {
291 _pd_cache_table->oops_do(f);
292 }
293
294 void Dictionary::methods_do(void f(Method*)) {
295 for (int index = 0; index < table_size(); index++) {
296 for (DictionaryEntry* probe = bucket(index);
297 probe != NULL;
298 probe = probe->next()) {
299 Klass* k = probe->klass();
300 if (probe->loader_data() == InstanceKlass::cast(k)->class_loader_data()) {
301 // only take klass is we have the entry with the defining class loader
302 InstanceKlass::cast(k)->methods_do(f);
303 }
304 }
305 }
306 }
307
308 Klass* Dictionary::try_get_next_class() {
309 while (true) {
310 if (_current_class_entry != NULL) {
311 Klass* k = _current_class_entry->klass();
312 _current_class_entry = _current_class_entry->next();
313 return k;
314 }
315 _current_class_index = (_current_class_index + 1) % table_size();
316 _current_class_entry = bucket(_current_class_index);
317 }
318 // never reached
319 }
320
321 // Add a loaded class to the system dictionary.
322 // Readers of the SystemDictionary aren't always locked, so _buckets
323 // is volatile. The store of the next field in the constructor is
324 // also cast to volatile; we do this to ensure store order is maintained
325 // by the compilers.
326
327 void Dictionary::add_klass(Symbol* class_name, ClassLoaderData* loader_data,
328 KlassHandle obj) {
329 assert_locked_or_safepoint(SystemDictionary_lock);
330 assert(obj() != NULL, "adding NULL obj");
331 assert(obj()->name() == class_name, "sanity check on name");
332 assert(loader_data != NULL, "Must be non-NULL");
333
334 unsigned int hash = compute_hash(class_name, loader_data);
335 int index = hash_to_index(hash);
336 DictionaryEntry* entry = new_entry(hash, obj(), loader_data);
337 add_entry(index, entry);
338 }
339
340
341 // This routine does not lock the system dictionary.
342 //
343 // Since readers don't hold a lock, we must make sure that system
344 // dictionary entries are only removed at a safepoint (when only one
345 // thread is running), and are added to in a safe way (all links must
346 // be updated in an MT-safe manner).
347 //
348 // Callers should be aware that an entry could be added just after
349 // _buckets[index] is read here, so the caller will not see the new entry.
350 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
351 Symbol* class_name,
352 ClassLoaderData* loader_data) {
353 debug_only(_lookup_count++);
354 for (DictionaryEntry* entry = bucket(index);
355 entry != NULL;
356 entry = entry->next()) {
357 if (entry->hash() == hash && entry->equals(class_name, loader_data)) {
358 return entry;
359 }
360 debug_only(_lookup_length++);
361 }
362 return NULL;
363 }
364
365
366 Klass* Dictionary::find(int index, unsigned int hash, Symbol* name,
367 ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
368 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
369 if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
370 return entry->klass();
371 } else {
372 return NULL;
373 }
374 }
375
376
377 Klass* Dictionary::find_class(int index, unsigned int hash,
378 Symbol* name, ClassLoaderData* loader_data) {
379 assert_locked_or_safepoint(SystemDictionary_lock);
380 assert (index == index_for(name, loader_data), "incorrect index?");
381
382 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
383 return (entry != NULL) ? entry->klass() : (Klass*)NULL;
384 }
385
386
387 // Variant of find_class for shared classes. No locking required, as
388 // that table is static.
389
390 Klass* Dictionary::find_shared_class(int index, unsigned int hash,
391 Symbol* name) {
392 assert (index == index_for(name, NULL), "incorrect index?");
393
394 DictionaryEntry* entry = get_entry(index, hash, name, NULL);
395 return (entry != NULL) ? entry->klass() : (Klass*)NULL;
396 }
397
398
399 void Dictionary::add_protection_domain(int index, unsigned int hash,
400 instanceKlassHandle klass,
401 ClassLoaderData* loader_data, Handle protection_domain,
402 TRAPS) {
403 Symbol* klass_name = klass->name();
404 DictionaryEntry* entry = get_entry(index, hash, klass_name, loader_data);
405
406 assert(entry != NULL,"entry must be present, we just created it");
407 assert(protection_domain() != NULL,
408 "real protection domain should be present");
409
410 entry->add_protection_domain(this, protection_domain());
411
412 assert(entry->contains_protection_domain(protection_domain()),
413 "now protection domain should be present");
414 }
415
416
417 bool Dictionary::is_valid_protection_domain(int index, unsigned int hash,
418 Symbol* name,
419 ClassLoaderData* loader_data,
420 Handle protection_domain) {
421 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
422 return entry->is_valid_protection_domain(protection_domain);
423 }
424
425
426 void Dictionary::reorder_dictionary() {
427
428 // Copy all the dictionary entries into a single master list.
429
430 DictionaryEntry* master_list = NULL;
431 for (int i = 0; i < table_size(); ++i) {
432 DictionaryEntry* p = bucket(i);
433 while (p != NULL) {
434 DictionaryEntry* tmp;
435 tmp = p->next();
436 p->set_next(master_list);
437 master_list = p;
438 p = tmp;
439 }
440 set_entry(i, NULL);
441 }
442
443 // Add the dictionary entries back to the list in the correct buckets.
444 while (master_list != NULL) {
445 DictionaryEntry* p = master_list;
446 master_list = master_list->next();
447 p->set_next(NULL);
448 Symbol* class_name = InstanceKlass::cast((Klass*)(p->klass()))->name();
449 // Since the null class loader data isn't copied to the CDS archive,
450 // compute the hash with NULL for loader data.
451 unsigned int hash = compute_hash(class_name, NULL);
452 int index = hash_to_index(hash);
453 p->set_hash(hash);
454 p->set_loader_data(NULL); // loader_data isn't copied to CDS
455 p->set_next(bucket(index));
456 set_entry(index, p);
457 }
458 }
459
460 ProtectionDomainCacheTable::ProtectionDomainCacheTable(int table_size)
461 : Hashtable<oop, mtClass>(table_size, sizeof(ProtectionDomainCacheEntry))
462 {
463 }
464
465 void ProtectionDomainCacheTable::oops_do(OopClosure* f) {
466 for (int index = 0; index < table_size(); index++) {
467 for (ProtectionDomainCacheEntry* probe = bucket(index);
468 probe != NULL;
469 probe = probe->next()) {
470 probe->oops_do(f);
471 }
472 }
473 }
474
475
476 void ProtectionDomainCacheTable::always_strong_oops_do(OopClosure* f, int gen) {
477 for (int index = 0; index < table_size(); index++) {
478 for (ProtectionDomainCacheEntry* probe = bucket(index);
479 probe != NULL;
480 probe = probe->next()) {
481 if (probe->is_strongly_reachable(gen)) {
482 probe->oops_do(f);
483 }
484 }
485 }
486 }
487
488 ProtectionDomainCacheEntry* ProtectionDomainCacheTable::get(oop protection_domain) {
489 unsigned int hash = compute_hash(protection_domain);
490 int index = hash_to_index(hash);
491
492 ProtectionDomainCacheEntry* entry = find_entry(index, protection_domain);
493 if (entry == NULL) {
494 entry = add_entry(index, hash, protection_domain);
495 }
496 return entry;
497 }
498
499 ProtectionDomainCacheEntry* ProtectionDomainCacheTable::find_entry(int index, oop protection_domain) {
500 for (ProtectionDomainCacheEntry* e = bucket(index); e != NULL; e = e->next()) {
501 if (e->protection_domain() == protection_domain) {
502 return e;
503 }
504 }
505
506 return NULL;
507 }
508
509 ProtectionDomainCacheEntry* ProtectionDomainCacheTable::add_entry(int index, unsigned int hash, oop protection_domain) {
510 assert_locked_or_safepoint(SystemDictionary_lock);
511 assert(index == index_for(protection_domain), "incorrect index?");
512 assert(find_entry(index, protection_domain) == NULL, "no double entry");
513
514 ProtectionDomainCacheEntry* p = new_entry(hash, protection_domain);
515 Hashtable<oop, mtClass>::add_entry(index, p);
516 return p;
517 }
518
519 void ProtectionDomainCacheTable::free(ProtectionDomainCacheEntry* to_delete) {
520 unsigned int hash = compute_hash(to_delete->protection_domain());
521 int index = hash_to_index(hash);
522
523 ProtectionDomainCacheEntry** p = bucket_addr(index);
524 ProtectionDomainCacheEntry* entry = bucket(index);
525 while (true) {
526 assert(entry != NULL, "sanity");
527
528 if (entry == to_delete) {
529 *p = entry->next();
530 Hashtable<oop, mtClass>::free_entry(entry);
531 break;
532 } else {
533 p = entry->next_addr();
534 entry = *p;
535 }
536 }
537 }
538
539 SymbolPropertyTable::SymbolPropertyTable(int table_size)
540 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry))
541 {
542 }
543 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t,
544 int number_of_entries)
545 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)
546 {
547 }
548
549
550 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,
551 Symbol* sym,
552 intptr_t sym_mode) {
553 assert(index == index_for(sym, sym_mode), "incorrect index?");
554 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
555 if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) {
556 return p;
557 }
558 }
559 return NULL;
560 }
561
562
563 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,
564 Symbol* sym, intptr_t sym_mode) {
565 assert_locked_or_safepoint(SystemDictionary_lock);
566 assert(index == index_for(sym, sym_mode), "incorrect index?");
567 assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");
568
569 SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode);
570 Hashtable<Symbol*, mtSymbol>::add_entry(index, p);
571 return p;
572 }
573
574 void SymbolPropertyTable::oops_do(OopClosure* f) {
575 for (int index = 0; index < table_size(); index++) {
576 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
577 if (p->method_type() != NULL) {
578 f->do_oop(p->method_type_addr());
579 }
580 }
581 }
582 }
583
584 void SymbolPropertyTable::methods_do(void f(Method*)) {
585 for (int index = 0; index < table_size(); index++) {
586 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
587 Method* prop = p->method();
588 if (prop != NULL) {
589 f((Method*)prop);
590 }
591 }
592 }
593 }
594
595
596 // ----------------------------------------------------------------------------
597 #ifndef PRODUCT
598
599 void Dictionary::print() {
600 ResourceMark rm;
601 HandleMark hm;
602
603 tty->print_cr("Java system dictionary (table_size=%d, classes=%d)",
604 table_size(), number_of_entries());
605 tty->print_cr("^ indicates that initiating loader is different from "
606 "defining loader");
607
608 for (int index = 0; index < table_size(); index++) {
609 for (DictionaryEntry* probe = bucket(index);
610 probe != NULL;
611 probe = probe->next()) {
612 if (Verbose) tty->print("%4d: ", index);
613 Klass* e = probe->klass();
614 ClassLoaderData* loader_data = probe->loader_data();
615 bool is_defining_class =
616 (loader_data == InstanceKlass::cast(e)->class_loader_data());
617 tty->print("%s%s", is_defining_class ? " " : "^",
618 e->external_name());
619
620 tty->print(", loader ");
621 loader_data->print_value();
622 tty->cr();
623 }
624 }
625 }
626
627 #endif
628
629
630 void Dictionary::verify() {
631 guarantee(number_of_entries() >= 0, "Verify of system dictionary failed");
632
633 int element_count = 0;
634 for (int index = 0; index < table_size(); index++) {
635 for (DictionaryEntry* probe = bucket(index);
636 probe != NULL;
637 probe = probe->next()) {
638 Klass* e = probe->klass();
639 ClassLoaderData* loader_data = probe->loader_data();
640 guarantee(e->oop_is_instance(),
641 "Verify of system dictionary failed");
642 // class loader must be present; a null class loader is the
643 // boostrap loader
644 guarantee(loader_data != NULL || DumpSharedSpaces ||
645 loader_data->class_loader() == NULL ||
646 loader_data->class_loader()->is_instance(),
647 "checking type of class_loader");
648 e->verify(/*check_dictionary*/false);
649 probe->verify_protection_domain_set();
650 element_count++;
651 }
652 }
653 guarantee(number_of_entries() == element_count,
654 "Verify of system dictionary failed");
655 debug_only(verify_lookup_length((double)number_of_entries() / table_size()));
656 }
657