1 /*
2 * Copyright (c) 2003, 2009, 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 "incls/_precompiled.incl"
26 # include "incls/_dictionary.cpp.incl"
27
28
29 DictionaryEntry* Dictionary::_current_class_entry = NULL;
30 int Dictionary::_current_class_index = 0;
31
32
33 Dictionary::Dictionary(int table_size)
34 : TwoOopHashtable(table_size, sizeof(DictionaryEntry)) {
35 _current_class_index = 0;
36 _current_class_entry = NULL;
37 };
38
39
40
41 Dictionary::Dictionary(int table_size, HashtableBucket* t,
42 int number_of_entries)
43 : TwoOopHashtable(table_size, sizeof(DictionaryEntry), t, number_of_entries) {
44 _current_class_index = 0;
45 _current_class_entry = NULL;
46 };
47
48
49 DictionaryEntry* Dictionary::new_entry(unsigned int hash, klassOop klass,
50 oop loader) {
51 DictionaryEntry* entry;
52 entry = (DictionaryEntry*)Hashtable::new_entry(hash, klass);
53 entry->set_loader(loader);
54 entry->set_pd_set(NULL);
55 return entry;
56 }
57
58
59 DictionaryEntry* Dictionary::new_entry() {
60 DictionaryEntry* entry = (DictionaryEntry*)Hashtable::new_entry(0L, NULL);
61 entry->set_loader(NULL);
62 entry->set_pd_set(NULL);
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 delete to_delete;
73 }
74 Hashtable::free_entry(entry);
75 }
76
77
78 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
79 #ifdef ASSERT
80 if (protection_domain == instanceKlass::cast(klass())->protection_domain()) {
81 // Ensure this doesn't show up in the pd_set (invariant)
82 bool in_pd_set = false;
83 for (ProtectionDomainEntry* current = _pd_set;
84 current != NULL;
85 current = current->next()) {
86 if (current->protection_domain() == protection_domain) {
87 in_pd_set = true;
88 break;
89 }
90 }
91 if (in_pd_set) {
92 assert(false, "A klass's protection domain should not show up "
93 "in its sys. dict. PD set");
94 }
95 }
96 #endif /* ASSERT */
97
98 if (protection_domain == instanceKlass::cast(klass())->protection_domain()) {
99 // Succeeds trivially
100 return true;
101 }
102
103 for (ProtectionDomainEntry* current = _pd_set;
104 current != NULL;
105 current = current->next()) {
106 if (current->protection_domain() == protection_domain) return true;
107 }
108 return false;
109 }
110
111
112 void DictionaryEntry::add_protection_domain(oop protection_domain) {
113 assert_locked_or_safepoint(SystemDictionary_lock);
114 if (!contains_protection_domain(protection_domain)) {
115 ProtectionDomainEntry* new_head =
116 new ProtectionDomainEntry(protection_domain, _pd_set);
117 // Warning: Preserve store ordering. The SystemDictionary is read
118 // without locks. The new ProtectionDomainEntry must be
119 // complete before other threads can be allowed to see it
120 // via a store to _pd_set.
121 OrderAccess::release_store_ptr(&_pd_set, new_head);
122 }
123 if (TraceProtectionDomainVerification && WizardMode) {
124 print();
125 }
126 }
127
128
129 bool Dictionary::do_unloading(BoolObjectClosure* is_alive) {
130 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
131 bool class_was_unloaded = false;
132 int index = 0; // Defined here for portability! Do not move
133
134 // Remove unloadable entries and classes from system dictionary
135 // The placeholder array has been handled in always_strong_oops_do.
136 DictionaryEntry* probe = NULL;
137 for (index = 0; index < table_size(); index++) {
138 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
139 probe = *p;
140 klassOop e = probe->klass();
141 oop class_loader = probe->loader();
142
143 instanceKlass* ik = instanceKlass::cast(e);
144 if (ik->previous_versions() != NULL) {
145 // This klass has previous versions so see what we can cleanup
146 // while it is safe to do so.
147
148 int gc_count = 0; // leave debugging breadcrumbs
149 int live_count = 0;
150
151 // RC_TRACE macro has an embedded ResourceMark
152 RC_TRACE(0x00000200, ("unload: %s: previous version length=%d",
153 ik->external_name(), ik->previous_versions()->length()));
154
155 for (int i = ik->previous_versions()->length() - 1; i >= 0; i--) {
156 // check the previous versions array for GC'ed weak refs
157 PreviousVersionNode * pv_node = ik->previous_versions()->at(i);
158 jobject cp_ref = pv_node->prev_constant_pool();
159 assert(cp_ref != NULL, "cp ref was unexpectedly cleared");
160 if (cp_ref == NULL) {
161 delete pv_node;
162 ik->previous_versions()->remove_at(i);
163 // Since we are traversing the array backwards, we don't have to
164 // do anything special with the index.
165 continue; // robustness
166 }
167
168 constantPoolOop pvcp = (constantPoolOop)JNIHandles::resolve(cp_ref);
169 if (pvcp == NULL) {
170 // this entry has been GC'ed so remove it
171 delete pv_node;
172 ik->previous_versions()->remove_at(i);
173 // Since we are traversing the array backwards, we don't have to
174 // do anything special with the index.
175 gc_count++;
176 continue;
177 } else {
178 RC_TRACE(0x00000200, ("unload: previous version @%d is alive", i));
179 if (is_alive->do_object_b(pvcp)) {
180 live_count++;
181 } else {
182 guarantee(false, "sanity check");
183 }
184 }
185
186 GrowableArray<jweak>* method_refs = pv_node->prev_EMCP_methods();
187 if (method_refs != NULL) {
188 RC_TRACE(0x00000200, ("unload: previous methods length=%d",
189 method_refs->length()));
190 for (int j = method_refs->length() - 1; j >= 0; j--) {
191 jweak method_ref = method_refs->at(j);
192 assert(method_ref != NULL, "weak method ref was unexpectedly cleared");
193 if (method_ref == NULL) {
194 method_refs->remove_at(j);
195 // Since we are traversing the array backwards, we don't have to
196 // do anything special with the index.
197 continue; // robustness
198 }
199
200 methodOop method = (methodOop)JNIHandles::resolve(method_ref);
201 if (method == NULL) {
202 // this method entry has been GC'ed so remove it
203 JNIHandles::destroy_weak_global(method_ref);
204 method_refs->remove_at(j);
205 } else {
206 // RC_TRACE macro has an embedded ResourceMark
207 RC_TRACE(0x00000200,
208 ("unload: %s(%s): prev method @%d in version @%d is alive",
209 method->name()->as_C_string(),
210 method->signature()->as_C_string(), j, i));
211 }
212 }
213 }
214 }
215 assert(ik->previous_versions()->length() == live_count, "sanity check");
216 RC_TRACE(0x00000200,
217 ("unload: previous version stats: live=%d, GC'ed=%d", live_count,
218 gc_count));
219 }
220
221 // Non-unloadable classes were handled in always_strong_oops_do
222 if (!is_strongly_reachable(class_loader, e)) {
223 // Entry was not visited in phase1 (negated test from phase1)
224 assert(class_loader != NULL, "unloading entry with null class loader");
225 oop k_def_class_loader = ik->class_loader();
226
227 // Do we need to delete this system dictionary entry?
228 bool purge_entry = false;
229
230 // Do we need to delete this system dictionary entry?
231 if (!is_alive->do_object_b(class_loader)) {
232 // If the loader is not live this entry should always be
233 // removed (will never be looked up again). Note that this is
234 // not the same as unloading the referred class.
235 if (k_def_class_loader == class_loader) {
236 // This is the defining entry, so the referred class is about
237 // to be unloaded.
238 // Notify the debugger and clean up the class.
239 guarantee(!is_alive->do_object_b(e),
240 "klass should not be live if defining loader is not");
241 class_was_unloaded = true;
242 // notify the debugger
243 if (JvmtiExport::should_post_class_unload()) {
244 JvmtiExport::post_class_unload(ik->as_klassOop());
245 }
246
247 // notify ClassLoadingService of class unload
248 ClassLoadingService::notify_class_unloaded(ik);
249
250 // Clean up C heap
251 ik->release_C_heap_structures();
252 }
253 // Also remove this system dictionary entry.
254 purge_entry = true;
255
256 } else {
257 // The loader in this entry is alive. If the klass is dead,
258 // the loader must be an initiating loader (rather than the
259 // defining loader). Remove this entry.
260 if (!is_alive->do_object_b(e)) {
261 guarantee(!is_alive->do_object_b(k_def_class_loader),
262 "defining loader should not be live if klass is not");
263 // If we get here, the class_loader must not be the defining
264 // loader, it must be an initiating one.
265 assert(k_def_class_loader != class_loader,
266 "cannot have live defining loader and unreachable klass");
267
268 // Loader is live, but class and its defining loader are dead.
269 // Remove the entry. The class is going away.
270 purge_entry = true;
271 }
272 }
273
274 if (purge_entry) {
275 *p = probe->next();
276 if (probe == _current_class_entry) {
277 _current_class_entry = NULL;
278 }
279 free_entry(probe);
280 continue;
281 }
282 }
283 p = probe->next_addr();
284 }
285 }
286 return class_was_unloaded;
287 }
288
289
290 void Dictionary::always_strong_classes_do(OopClosure* blk) {
291 // Follow all system classes and temporary placeholders in dictionary
292 for (int index = 0; index < table_size(); index++) {
293 for (DictionaryEntry *probe = bucket(index);
294 probe != NULL;
295 probe = probe->next()) {
296 oop e = probe->klass();
297 oop class_loader = probe->loader();
298 if (is_strongly_reachable(class_loader, e)) {
299 blk->do_oop((oop*)probe->klass_addr());
300 if (class_loader != NULL) {
301 blk->do_oop(probe->loader_addr());
302 }
303 probe->protection_domain_set_oops_do(blk);
304 }
305 }
306 }
307 }
308
309
310 // Just the classes from defining class loaders
311 void Dictionary::classes_do(void f(klassOop)) {
312 for (int index = 0; index < table_size(); index++) {
313 for (DictionaryEntry* probe = bucket(index);
314 probe != NULL;
315 probe = probe->next()) {
316 klassOop k = probe->klass();
317 if (probe->loader() == instanceKlass::cast(k)->class_loader()) {
318 f(k);
319 }
320 }
321 }
322 }
323
324 // Added for initialize_itable_for_klass to handle exceptions
325 // Just the classes from defining class loaders
326 void Dictionary::classes_do(void f(klassOop, TRAPS), TRAPS) {
327 for (int index = 0; index < table_size(); index++) {
328 for (DictionaryEntry* probe = bucket(index);
329 probe != NULL;
330 probe = probe->next()) {
331 klassOop k = probe->klass();
332 if (probe->loader() == instanceKlass::cast(k)->class_loader()) {
333 f(k, CHECK);
334 }
335 }
336 }
337 }
338
339
340 // All classes, and their class loaders
341 // (added for helpers that use HandleMarks and ResourceMarks)
342 // Don't iterate over placeholders
343 void Dictionary::classes_do(void f(klassOop, oop, TRAPS), TRAPS) {
344 for (int index = 0; index < table_size(); index++) {
345 for (DictionaryEntry* probe = bucket(index);
346 probe != NULL;
347 probe = probe->next()) {
348 klassOop k = probe->klass();
349 f(k, probe->loader(), CHECK);
350 }
351 }
352 }
353
354
355 // All classes, and their class loaders
356 // Don't iterate over placeholders
357 void Dictionary::classes_do(void f(klassOop, oop)) {
358 for (int index = 0; index < table_size(); index++) {
359 for (DictionaryEntry* probe = bucket(index);
360 probe != NULL;
361 probe = probe->next()) {
362 klassOop k = probe->klass();
363 f(k, probe->loader());
364 }
365 }
366 }
367
368
369 void Dictionary::oops_do(OopClosure* f) {
370 for (int index = 0; index < table_size(); index++) {
371 for (DictionaryEntry* probe = bucket(index);
372 probe != NULL;
373 probe = probe->next()) {
374 f->do_oop((oop*)probe->klass_addr());
375 if (probe->loader() != NULL) {
376 f->do_oop(probe->loader_addr());
377 }
378 probe->protection_domain_set_oops_do(f);
379 }
380 }
381 }
382
383
384 void Dictionary::methods_do(void f(methodOop)) {
385 for (int index = 0; index < table_size(); index++) {
386 for (DictionaryEntry* probe = bucket(index);
387 probe != NULL;
388 probe = probe->next()) {
389 klassOop k = probe->klass();
390 if (probe->loader() == instanceKlass::cast(k)->class_loader()) {
391 // only take klass is we have the entry with the defining class loader
392 instanceKlass::cast(k)->methods_do(f);
393 }
394 }
395 }
396 }
397
398
399 klassOop Dictionary::try_get_next_class() {
400 while (true) {
401 if (_current_class_entry != NULL) {
402 klassOop k = _current_class_entry->klass();
403 _current_class_entry = _current_class_entry->next();
404 return k;
405 }
406 _current_class_index = (_current_class_index + 1) % table_size();
407 _current_class_entry = bucket(_current_class_index);
408 }
409 // never reached
410 }
411
412
413 // Add a loaded class to the system dictionary.
414 // Readers of the SystemDictionary aren't always locked, so _buckets
415 // is volatile. The store of the next field in the constructor is
416 // also cast to volatile; we do this to ensure store order is maintained
417 // by the compilers.
418
419 void Dictionary::add_klass(symbolHandle class_name, Handle class_loader,
420 KlassHandle obj) {
421 assert_locked_or_safepoint(SystemDictionary_lock);
422 assert(obj() != NULL, "adding NULL obj");
423 assert(Klass::cast(obj())->name() == class_name(), "sanity check on name");
424
425 unsigned int hash = compute_hash(class_name, class_loader);
426 int index = hash_to_index(hash);
427 DictionaryEntry* entry = new_entry(hash, obj(), class_loader());
428 add_entry(index, entry);
429 }
430
431
432 // This routine does not lock the system dictionary.
433 //
434 // Since readers don't hold a lock, we must make sure that system
435 // dictionary entries are only removed at a safepoint (when only one
436 // thread is running), and are added to in a safe way (all links must
437 // be updated in an MT-safe manner).
438 //
439 // Callers should be aware that an entry could be added just after
440 // _buckets[index] is read here, so the caller will not see the new entry.
441 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
442 symbolHandle class_name,
443 Handle class_loader) {
444 symbolOop name_ = class_name();
445 oop loader_ = class_loader();
446 debug_only(_lookup_count++);
447 for (DictionaryEntry* entry = bucket(index);
448 entry != NULL;
449 entry = entry->next()) {
450 if (entry->hash() == hash && entry->equals(name_, loader_)) {
451 return entry;
452 }
453 debug_only(_lookup_length++);
454 }
455 return NULL;
456 }
457
458
459 klassOop Dictionary::find(int index, unsigned int hash, symbolHandle name,
460 Handle loader, Handle protection_domain, TRAPS) {
461 DictionaryEntry* entry = get_entry(index, hash, name, loader);
462 if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
463 return entry->klass();
464 } else {
465 return NULL;
466 }
467 }
468
469
470 klassOop Dictionary::find_class(int index, unsigned int hash,
471 symbolHandle name, Handle loader) {
472 assert_locked_or_safepoint(SystemDictionary_lock);
473 assert (index == index_for(name, loader), "incorrect index?");
474
475 DictionaryEntry* entry = get_entry(index, hash, name, loader);
476 return (entry != NULL) ? entry->klass() : (klassOop)NULL;
477 }
478
479
480 // Variant of find_class for shared classes. No locking required, as
481 // that table is static.
482
483 klassOop Dictionary::find_shared_class(int index, unsigned int hash,
484 symbolHandle name) {
485 assert (index == index_for(name, Handle()), "incorrect index?");
486
487 DictionaryEntry* entry = get_entry(index, hash, name, Handle());
488 return (entry != NULL) ? entry->klass() : (klassOop)NULL;
489 }
490
491
492 void Dictionary::add_protection_domain(int index, unsigned int hash,
493 instanceKlassHandle klass,
494 Handle loader, Handle protection_domain,
495 TRAPS) {
496 symbolHandle klass_name(THREAD, klass->name());
497 DictionaryEntry* entry = get_entry(index, hash, klass_name, loader);
498
499 assert(entry != NULL,"entry must be present, we just created it");
500 assert(protection_domain() != NULL,
501 "real protection domain should be present");
502
503 entry->add_protection_domain(protection_domain());
504
505 assert(entry->contains_protection_domain(protection_domain()),
506 "now protection domain should be present");
507 }
508
509
510 bool Dictionary::is_valid_protection_domain(int index, unsigned int hash,
511 symbolHandle name,
512 Handle loader,
513 Handle protection_domain) {
514 DictionaryEntry* entry = get_entry(index, hash, name, loader);
515 return entry->is_valid_protection_domain(protection_domain);
516 }
517
518
519 void Dictionary::reorder_dictionary() {
520
521 // Copy all the dictionary entries into a single master list.
522
523 DictionaryEntry* master_list = NULL;
524 for (int i = 0; i < table_size(); ++i) {
525 DictionaryEntry* p = bucket(i);
526 while (p != NULL) {
527 DictionaryEntry* tmp;
528 tmp = p->next();
529 p->set_next(master_list);
530 master_list = p;
531 p = tmp;
532 }
533 set_entry(i, NULL);
534 }
535
536 // Add the dictionary entries back to the list in the correct buckets.
537 Thread *thread = Thread::current();
538
539 while (master_list != NULL) {
540 DictionaryEntry* p = master_list;
541 master_list = master_list->next();
542 p->set_next(NULL);
543 symbolHandle class_name (thread, instanceKlass::cast((klassOop)(p->klass()))->name());
544 unsigned int hash = compute_hash(class_name, Handle(thread, p->loader()));
545 int index = hash_to_index(hash);
546 p->set_hash(hash);
547 p->set_next(bucket(index));
548 set_entry(index, p);
549 }
550 }
551
552 SymbolPropertyTable::SymbolPropertyTable(int table_size)
553 : Hashtable(table_size, sizeof(SymbolPropertyEntry))
554 {
555 }
556 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket* t,
557 int number_of_entries)
558 : Hashtable(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)
559 {
560 }
561
562
563 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,
564 symbolHandle sym,
565 intptr_t sym_mode) {
566 assert(index == index_for(sym, sym_mode), "incorrect index?");
567 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
568 if (p->hash() == hash && p->symbol() == sym() && p->symbol_mode() == sym_mode) {
569 return p;
570 }
571 }
572 return NULL;
573 }
574
575
576 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,
577 symbolHandle sym, intptr_t sym_mode) {
578 assert_locked_or_safepoint(SystemDictionary_lock);
579 assert(index == index_for(sym, sym_mode), "incorrect index?");
580 assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");
581
582 SymbolPropertyEntry* p = new_entry(hash, sym(), sym_mode);
583 Hashtable::add_entry(index, p);
584 return p;
585 }
586
587
588 void SymbolPropertyTable::oops_do(OopClosure* f) {
589 for (int index = 0; index < table_size(); index++) {
590 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
591 f->do_oop((oop*) p->symbol_addr());
592 if (p->property_oop() != NULL) {
593 f->do_oop(p->property_oop_addr());
594 }
595 }
596 }
597 }
598
599 void SymbolPropertyTable::methods_do(void f(methodOop)) {
600 for (int index = 0; index < table_size(); index++) {
601 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
602 oop prop = p->property_oop();
603 if (prop != NULL && prop->is_method()) {
604 f((methodOop)prop);
605 }
606 }
607 }
608 }
609
610
611 // ----------------------------------------------------------------------------
612 #ifndef PRODUCT
613
614 void Dictionary::print() {
615 ResourceMark rm;
616 HandleMark hm;
617
618 tty->print_cr("Java system dictionary (classes=%d)", number_of_entries());
619 tty->print_cr("^ indicates that initiating loader is different from "
620 "defining loader");
621
622 for (int index = 0; index < table_size(); index++) {
623 for (DictionaryEntry* probe = bucket(index);
624 probe != NULL;
625 probe = probe->next()) {
626 if (Verbose) tty->print("%4d: ", index);
627 klassOop e = probe->klass();
628 oop class_loader = probe->loader();
629 bool is_defining_class =
630 (class_loader == instanceKlass::cast(e)->class_loader());
631 tty->print("%s%s", is_defining_class ? " " : "^",
632 Klass::cast(e)->external_name());
633 if (class_loader != NULL) {
634 tty->print(", loader ");
635 class_loader->print_value();
636 }
637 tty->cr();
638 }
639 }
640 }
641
642 #endif
643
644 void Dictionary::verify() {
645 guarantee(number_of_entries() >= 0, "Verify of system dictionary failed");
646 int element_count = 0;
647 for (int index = 0; index < table_size(); index++) {
648 for (DictionaryEntry* probe = bucket(index);
649 probe != NULL;
650 probe = probe->next()) {
651 klassOop e = probe->klass();
652 oop class_loader = probe->loader();
653 guarantee(Klass::cast(e)->oop_is_instance(),
654 "Verify of system dictionary failed");
655 // class loader must be present; a null class loader is the
656 // boostrap loader
657 guarantee(class_loader == NULL || class_loader->is_instance(),
658 "checking type of class_loader");
659 e->verify();
660 probe->verify_protection_domain_set();
661 element_count++;
662 }
663 }
664 guarantee(number_of_entries() == element_count,
665 "Verify of system dictionary failed");
666 debug_only(verify_lookup_length((double)number_of_entries() / table_size()));
667 }