1 /*
2 * Copyright (c) 2003, 2012, 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 "services/classLoadingService.hpp"
31 #include "utilities/hashtable.inline.hpp"
32
33
34 DictionaryEntry* Dictionary::_current_class_entry = NULL;
35 int Dictionary::_current_class_index = 0;
36
37
38 Dictionary::Dictionary(int table_size)
39 : TwoOopHashtable<Klass*, mtClass>(table_size, sizeof(DictionaryEntry)) {
40 _current_class_index = 0;
41 _current_class_entry = NULL;
42 };
43
44
45
46 Dictionary::Dictionary(int table_size, HashtableBucket<mtClass>* t,
47 int number_of_entries)
48 : TwoOopHashtable<Klass*, mtClass>(table_size, sizeof(DictionaryEntry), t, number_of_entries) {
49 _current_class_index = 0;
50 _current_class_entry = NULL;
51 };
52
53
54 DictionaryEntry* Dictionary::new_entry(unsigned int hash, Klass* klass,
55 ClassLoaderData* loader_data) {
56 DictionaryEntry* entry = (DictionaryEntry*)Hashtable<Klass*, mtClass>::new_entry(hash, klass);
57 entry->set_loader_data(loader_data);
58 entry->set_pd_set(NULL);
59 assert(klass->oop_is_instance(), "Must be");
60 return entry;
61 }
62
63
64 void Dictionary::free_entry(DictionaryEntry* entry) {
65 // avoid recursion when deleting linked list
66 while (entry->pd_set() != NULL) {
67 ProtectionDomainEntry* to_delete = entry->pd_set();
68 entry->set_pd_set(to_delete->next());
69 delete to_delete;
70 }
71 Hashtable<Klass*, mtClass>::free_entry(entry);
72 }
73
74
75 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
76 #ifdef ASSERT
77 if (protection_domain == InstanceKlass::cast(klass())->protection_domain()) {
78 // Ensure this doesn't show up in the pd_set (invariant)
79 bool in_pd_set = false;
80 for (ProtectionDomainEntry* current = _pd_set;
81 current != NULL;
82 current = current->next()) {
83 if (current->protection_domain() == protection_domain) {
84 in_pd_set = true;
85 break;
86 }
87 }
88 if (in_pd_set) {
89 assert(false, "A klass's protection domain should not show up "
90 "in its sys. dict. PD set");
91 }
92 }
93 #endif /* ASSERT */
94
95 if (protection_domain == InstanceKlass::cast(klass())->protection_domain()) {
96 // Succeeds trivially
97 return true;
98 }
99
100 for (ProtectionDomainEntry* current = _pd_set;
101 current != NULL;
102 current = current->next()) {
103 if (current->protection_domain() == protection_domain) return true;
104 }
105 return false;
106 }
107
108
109 void DictionaryEntry::add_protection_domain(oop protection_domain) {
110 assert_locked_or_safepoint(SystemDictionary_lock);
111 if (!contains_protection_domain(protection_domain)) {
112 ProtectionDomainEntry* new_head =
113 new ProtectionDomainEntry(protection_domain, _pd_set);
114 // Warning: Preserve store ordering. The SystemDictionary is read
115 // without locks. The new ProtectionDomainEntry must be
116 // complete before other threads can be allowed to see it
117 // via a store to _pd_set.
118 OrderAccess::release_store_ptr(&_pd_set, new_head);
119 }
120 if (TraceProtectionDomainVerification && WizardMode) {
121 print();
122 }
123 }
124
125
126 bool Dictionary::do_unloading() {
127 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
128 bool class_was_unloaded = false;
129 int index = 0; // Defined here for portability! Do not move
130
131 // Remove unloadable entries and classes from system dictionary
132 // The placeholder array has been handled in always_strong_oops_do.
133 DictionaryEntry* probe = NULL;
134 for (index = 0; index < table_size(); index++) {
135 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
136 probe = *p;
137 Klass* e = probe->klass();
138 ClassLoaderData* loader_data = probe->loader_data();
139
140 InstanceKlass* ik = InstanceKlass::cast(e);
141
142 // Non-unloadable classes were handled in always_strong_oops_do
143 if (!is_strongly_reachable(loader_data, e)) {
144 // Entry was not visited in phase1 (negated test from phase1)
145 assert(!loader_data->is_the_null_class_loader_data(), "unloading entry with null class loader");
146 ClassLoaderData* k_def_class_loader_data = ik->class_loader_data();
147
148 // Do we need to delete this system dictionary entry?
149 bool purge_entry = false;
150
151 // Do we need to delete this system dictionary entry?
152 if (loader_data->is_unloading()) {
153 // If the loader is not live this entry should always be
154 // removed (will never be looked up again). Note that this is
155 // not the same as unloading the referred class.
156 if (k_def_class_loader_data == loader_data) {
157 // This is the defining entry, so the referred class is about
158 // to be unloaded.
159 // Notify the debugger and clean up the class.
160 class_was_unloaded = true;
161 // notify the debugger
162 if (JvmtiExport::should_post_class_unload()) {
163 JvmtiExport::post_class_unload(ik);
164 }
165
166 // notify ClassLoadingService of class unload
167 ClassLoadingService::notify_class_unloaded(ik);
168
169 // Clean up C heap
170 ik->release_C_heap_structures();
171 ik->constants()->release_C_heap_structures();
172 }
173 // Also remove this system dictionary entry.
174 purge_entry = true;
175
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 return class_was_unloaded;
205 }
206
207
208 void Dictionary::always_strong_oops_do(OopClosure* blk) {
209 // Follow all system classes and temporary placeholders in dictionary
210 for (int index = 0; index < table_size(); index++) {
211 for (DictionaryEntry *probe = bucket(index);
212 probe != NULL;
213 probe = probe->next()) {
214 Klass* e = probe->klass();
215 ClassLoaderData* loader_data = probe->loader_data();
216 if (is_strongly_reachable(loader_data, e)) {
217 probe->protection_domain_set_oops_do(blk);
218 }
219 }
220 }
221 }
222
223
224 void Dictionary::always_strong_classes_do(KlassClosure* closure) {
225 // Follow all system classes and temporary placeholders in dictionary
226 for (int index = 0; index < table_size(); index++) {
227 for (DictionaryEntry* probe = bucket(index);
228 probe != NULL;
229 probe = probe->next()) {
230 Klass* e = probe->klass();
231 ClassLoaderData* loader_data = probe->loader_data();
232 if (is_strongly_reachable(loader_data, e)) {
233 closure->do_klass(e);
234 }
235 }
236 }
237 }
238
239
240 // Just the classes from defining class loaders
241 void Dictionary::classes_do(void f(Klass*)) {
242 for (int index = 0; index < table_size(); index++) {
243 for (DictionaryEntry* probe = bucket(index);
244 probe != NULL;
245 probe = probe->next()) {
246 Klass* k = probe->klass();
247 if (probe->loader_data() == InstanceKlass::cast(k)->class_loader_data()) {
248 f(k);
249 }
250 }
251 }
252 }
253
254 // Added for initialize_itable_for_klass to handle exceptions
255 // Just the classes from defining class loaders
256 void Dictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
257 for (int index = 0; index < table_size(); index++) {
258 for (DictionaryEntry* probe = bucket(index);
259 probe != NULL;
260 probe = probe->next()) {
261 Klass* k = probe->klass();
262 if (probe->loader_data() == InstanceKlass::cast(k)->class_loader_data()) {
263 f(k, CHECK);
264 }
265 }
266 }
267 }
268
269
270 // All classes, and their class loaders
271 // (added for helpers that use HandleMarks and ResourceMarks)
272 // Don't iterate over placeholders
273 void Dictionary::classes_do(void f(Klass*, ClassLoaderData*, TRAPS), TRAPS) {
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(), CHECK);
280 }
281 }
282 }
283
284
285 // All classes, and their class loaders
286 // Don't iterate over placeholders
287 void Dictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
288 for (int index = 0; index < table_size(); index++) {
289 for (DictionaryEntry* probe = bucket(index);
290 probe != NULL;
291 probe = probe->next()) {
292 Klass* k = probe->klass();
293 f(k, probe->loader_data());
294 }
295 }
296 }
297
298
299 void Dictionary::oops_do(OopClosure* f) {
300 for (int index = 0; index < table_size(); index++) {
301 for (DictionaryEntry* probe = bucket(index);
302 probe != NULL;
303 probe = probe->next()) {
304 probe->protection_domain_set_oops_do(f);
305 }
306 }
307 }
308
309
310 void Dictionary::methods_do(void f(Method*)) {
311 for (int index = 0; index < table_size(); index++) {
312 for (DictionaryEntry* probe = bucket(index);
313 probe != NULL;
314 probe = probe->next()) {
315 Klass* k = probe->klass();
316 if (probe->loader_data() == InstanceKlass::cast(k)->class_loader_data()) {
317 // only take klass is we have the entry with the defining class loader
318 InstanceKlass::cast(k)->methods_do(f);
319 }
320 }
321 }
322 }
323
324
325 Klass* Dictionary::try_get_next_class() {
326 while (true) {
327 if (_current_class_entry != NULL) {
328 Klass* k = _current_class_entry->klass();
329 _current_class_entry = _current_class_entry->next();
330 return k;
331 }
332 _current_class_index = (_current_class_index + 1) % table_size();
333 _current_class_entry = bucket(_current_class_index);
334 }
335 // never reached
336 }
337
338
339 // Add a loaded class to the system dictionary.
340 // Readers of the SystemDictionary aren't always locked, so _buckets
341 // is volatile. The store of the next field in the constructor is
342 // also cast to volatile; we do this to ensure store order is maintained
343 // by the compilers.
344
345 void Dictionary::add_klass(Symbol* class_name, ClassLoaderData* loader_data,
346 KlassHandle obj) {
347 assert_locked_or_safepoint(SystemDictionary_lock);
348 assert(obj() != NULL, "adding NULL obj");
349 assert(obj()->name() == class_name, "sanity check on name");
350 assert(loader_data != NULL, "Must be non-NULL");
351
352 unsigned int hash = compute_hash(class_name, loader_data);
353 int index = hash_to_index(hash);
354 DictionaryEntry* entry = new_entry(hash, obj(), loader_data);
355 add_entry(index, entry);
356 }
357
358
359 // This routine does not lock the system dictionary.
360 //
361 // Since readers don't hold a lock, we must make sure that system
362 // dictionary entries are only removed at a safepoint (when only one
363 // thread is running), and are added to in a safe way (all links must
364 // be updated in an MT-safe manner).
365 //
366 // Callers should be aware that an entry could be added just after
367 // _buckets[index] is read here, so the caller will not see the new entry.
368 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
369 Symbol* class_name,
370 ClassLoaderData* loader_data) {
371 debug_only(_lookup_count++);
372 for (DictionaryEntry* entry = bucket(index);
373 entry != NULL;
374 entry = entry->next()) {
375 if (entry->hash() == hash && entry->equals(class_name, loader_data)) {
376 return entry;
377 }
378 debug_only(_lookup_length++);
379 }
380 return NULL;
381 }
382
383
384 Klass* Dictionary::find(int index, unsigned int hash, Symbol* name,
385 ClassLoaderData* loader_data, Handle protection_domain, TRAPS) {
386 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
387 if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
388 return entry->klass();
389 } else {
390 return NULL;
391 }
392 }
393
394
395 Klass* Dictionary::find_class(int index, unsigned int hash,
396 Symbol* name, ClassLoaderData* loader_data) {
397 assert_locked_or_safepoint(SystemDictionary_lock);
398 assert (index == index_for(name, loader_data), "incorrect index?");
399
400 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
401 return (entry != NULL) ? entry->klass() : (Klass*)NULL;
402 }
403
404
405 // Variant of find_class for shared classes. No locking required, as
406 // that table is static.
407
408 Klass* Dictionary::find_shared_class(int index, unsigned int hash,
409 Symbol* name) {
410 assert (index == index_for(name, NULL), "incorrect index?");
411
412 DictionaryEntry* entry = get_entry(index, hash, name, NULL);
413 return (entry != NULL) ? entry->klass() : (Klass*)NULL;
414 }
415
416
417 void Dictionary::add_protection_domain(int index, unsigned int hash,
418 instanceKlassHandle klass,
419 ClassLoaderData* loader_data, Handle protection_domain,
420 TRAPS) {
421 Symbol* klass_name = klass->name();
422 DictionaryEntry* entry = get_entry(index, hash, klass_name, loader_data);
423
424 assert(entry != NULL,"entry must be present, we just created it");
425 assert(protection_domain() != NULL,
426 "real protection domain should be present");
427
428 entry->add_protection_domain(protection_domain());
429
430 assert(entry->contains_protection_domain(protection_domain()),
431 "now protection domain should be present");
432 }
433
434
435 bool Dictionary::is_valid_protection_domain(int index, unsigned int hash,
436 Symbol* name,
437 ClassLoaderData* loader_data,
438 Handle protection_domain) {
439 DictionaryEntry* entry = get_entry(index, hash, name, loader_data);
440 return entry->is_valid_protection_domain(protection_domain);
441 }
442
443
444 void Dictionary::reorder_dictionary() {
445
446 // Copy all the dictionary entries into a single master list.
447
448 DictionaryEntry* master_list = NULL;
449 for (int i = 0; i < table_size(); ++i) {
450 DictionaryEntry* p = bucket(i);
451 while (p != NULL) {
452 DictionaryEntry* tmp;
453 tmp = p->next();
454 p->set_next(master_list);
455 master_list = p;
456 p = tmp;
457 }
458 set_entry(i, NULL);
459 }
460
461 // Add the dictionary entries back to the list in the correct buckets.
462 while (master_list != NULL) {
463 DictionaryEntry* p = master_list;
464 master_list = master_list->next();
465 p->set_next(NULL);
466 Symbol* class_name = InstanceKlass::cast((Klass*)(p->klass()))->name();
467 // Since the null class loader data isn't copied to the CDS archive,
468 // compute the hash with NULL for loader data.
469 unsigned int hash = compute_hash(class_name, NULL);
470 int index = hash_to_index(hash);
471 p->set_hash(hash);
472 p->set_loader_data(NULL); // loader_data isn't copied to CDS
473 p->set_next(bucket(index));
474 set_entry(index, p);
475 }
476 }
477
478 SymbolPropertyTable::SymbolPropertyTable(int table_size)
479 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry))
480 {
481 }
482 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t,
483 int number_of_entries)
484 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)
485 {
486 }
487
488
489 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,
490 Symbol* sym,
491 intptr_t sym_mode) {
492 assert(index == index_for(sym, sym_mode), "incorrect index?");
493 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
494 if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) {
495 return p;
496 }
497 }
498 return NULL;
499 }
500
501
502 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,
503 Symbol* sym, intptr_t sym_mode) {
504 assert_locked_or_safepoint(SystemDictionary_lock);
505 assert(index == index_for(sym, sym_mode), "incorrect index?");
506 assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");
507
508 SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode);
509 Hashtable<Symbol*, mtSymbol>::add_entry(index, p);
510 return p;
511 }
512
513 void SymbolPropertyTable::oops_do(OopClosure* f) {
514 for (int index = 0; index < table_size(); index++) {
515 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
516 if (p->method_type() != NULL) {
517 f->do_oop(p->method_type_addr());
518 }
519 }
520 }
521 }
522
523 void SymbolPropertyTable::methods_do(void f(Method*)) {
524 for (int index = 0; index < table_size(); index++) {
525 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
526 Method* prop = p->method();
527 if (prop != NULL) {
528 f((Method*)prop);
529 }
530 }
531 }
532 }
533
534
535 // ----------------------------------------------------------------------------
536 #ifndef PRODUCT
537
538 void Dictionary::print() {
539 ResourceMark rm;
540 HandleMark hm;
541
542 tty->print_cr("Java system dictionary (table_size=%d, classes=%d)",
543 table_size(), number_of_entries());
544 tty->print_cr("^ indicates that initiating loader is different from "
545 "defining loader");
546
547 for (int index = 0; index < table_size(); index++) {
548 for (DictionaryEntry* probe = bucket(index);
549 probe != NULL;
550 probe = probe->next()) {
551 if (Verbose) tty->print("%4d: ", index);
552 Klass* e = probe->klass();
553 ClassLoaderData* loader_data = probe->loader_data();
554 bool is_defining_class =
555 (loader_data == InstanceKlass::cast(e)->class_loader_data());
556 tty->print("%s%s", is_defining_class ? " " : "^",
557 e->external_name());
558
559 tty->print(", loader ");
560 loader_data->print_value();
561 tty->cr();
562 }
563 }
564 }
565
566 #endif
567
568
569 void Dictionary::verify() {
570 guarantee(number_of_entries() >= 0, "Verify of system dictionary failed");
571
572 int element_count = 0;
573 for (int index = 0; index < table_size(); index++) {
574 for (DictionaryEntry* probe = bucket(index);
575 probe != NULL;
576 probe = probe->next()) {
577 Klass* e = probe->klass();
578 ClassLoaderData* loader_data = probe->loader_data();
579 guarantee(e->oop_is_instance(),
580 "Verify of system dictionary failed");
581 // class loader must be present; a null class loader is the
582 // boostrap loader
583 guarantee(loader_data != NULL || DumpSharedSpaces ||
584 loader_data->class_loader() == NULL ||
585 loader_data->class_loader()->is_instance(),
586 "checking type of class_loader");
587 e->verify();
588 probe->verify_protection_domain_set();
589 element_count++;
590 }
591 }
592 guarantee(number_of_entries() == element_count,
593 "Verify of system dictionary failed");
594 debug_only(verify_lookup_length((double)number_of_entries() / table_size()));
595 }
596