1 /*
2 * Copyright (c) 2003, 2020, 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/dictionary.hpp"
28 #include "classfile/protectionDomainCache.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "logging/log.hpp"
31 #include "logging/logStream.hpp"
32 #include "memory/iterator.hpp"
33 #include "memory/metaspaceClosure.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "memory/universe.hpp"
36 #include "oops/oop.inline.hpp"
37 #include "oops/oopHandle.inline.hpp"
38 #include "runtime/mutexLocker.hpp"
39 #include "runtime/safepointVerifiers.hpp"
40 #include "utilities/hashtable.inline.hpp"
41
42 // Optimization: if any dictionary needs resizing, we set this flag,
43 // so that we dont't have to walk all dictionaries to check if any actually
44 // needs resizing, which is costly to do at Safepoint.
45 bool Dictionary::_some_dictionary_needs_resizing = false;
46
47 Dictionary::Dictionary(ClassLoaderData* loader_data, int table_size, bool resizable)
48 : Hashtable<InstanceKlass*, mtClass>(table_size, (int)sizeof(DictionaryEntry)),
49 _resizable(resizable), _needs_resizing(false), _loader_data(loader_data) {
50 };
51
52
53 Dictionary::Dictionary(ClassLoaderData* loader_data,
54 int table_size, HashtableBucket<mtClass>* t,
55 int number_of_entries, bool resizable)
56 : Hashtable<InstanceKlass*, mtClass>(table_size, (int)sizeof(DictionaryEntry), t, number_of_entries),
57 _resizable(resizable), _needs_resizing(false), _loader_data(loader_data) {
58 };
59
60 Dictionary::~Dictionary() {
61 DictionaryEntry* probe = NULL;
62 for (int index = 0; index < table_size(); index++) {
63 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
64 probe = *p;
65 *p = probe->next();
66 free_entry(probe);
67 }
68 }
69 assert(number_of_entries() == 0, "should have removed all entries");
70 assert(new_entry_free_list() == NULL, "entry present on Dictionary's free list");
71 }
72
73 DictionaryEntry* Dictionary::new_entry(unsigned int hash, InstanceKlass* klass) {
74 DictionaryEntry* entry = (DictionaryEntry*)Hashtable<InstanceKlass*, mtClass>::allocate_new_entry(hash, klass);
75 entry->set_pd_set(NULL);
76 assert(klass->is_instance_klass(), "Must be");
77 return entry;
78 }
79
80
81 void Dictionary::free_entry(DictionaryEntry* entry) {
82 // avoid recursion when deleting linked list
83 // pd_set is accessed during a safepoint.
84 // This doesn't require a lock because nothing is reading this
85 // entry anymore. The ClassLoader is dead.
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 // Unlink from the Hashtable prior to freeing
92 unlink_entry(entry);
93 FREE_C_HEAP_ARRAY(char, entry);
94 }
95
96 const int _resize_load_trigger = 5; // load factor that will trigger the resize
97 const double _resize_factor = 2.0; // by how much we will resize using current number of entries
98 const int _resize_max_size = 40423; // the max dictionary size allowed
99 const int _primelist[] = {107, 1009, 2017, 4049, 5051, 10103, 20201, _resize_max_size};
100 const int _prime_array_size = sizeof(_primelist)/sizeof(int);
101
102 // Calculate next "good" dictionary size based on requested count
103 static int calculate_dictionary_size(int requested) {
104 int newsize = _primelist[0];
105 int index = 0;
106 for (newsize = _primelist[index]; index < (_prime_array_size - 1);
107 newsize = _primelist[++index]) {
108 if (requested <= newsize) {
109 break;
110 }
111 }
112 return newsize;
113 }
114
115 bool Dictionary::does_any_dictionary_needs_resizing() {
116 return Dictionary::_some_dictionary_needs_resizing;
117 }
118
119 void Dictionary::check_if_needs_resize() {
120 if (_resizable == true) {
121 if (number_of_entries() > (_resize_load_trigger*table_size())) {
122 _needs_resizing = true;
123 Dictionary::_some_dictionary_needs_resizing = true;
124 }
125 }
126 }
127
128 bool Dictionary::resize_if_needed() {
129 int desired_size = 0;
130 if (_needs_resizing == true) {
131 desired_size = calculate_dictionary_size((int)(_resize_factor*number_of_entries()));
132 if (desired_size >= _resize_max_size) {
133 desired_size = _resize_max_size;
134 // We have reached the limit, turn resizing off
135 _resizable = false;
136 }
137 if ((desired_size != 0) && (desired_size != table_size())) {
138 if (!resize(desired_size)) {
139 // Something went wrong, turn resizing off
140 _resizable = false;
141 }
142 }
143 }
144
145 _needs_resizing = false;
146 Dictionary::_some_dictionary_needs_resizing = false;
147
148 return (desired_size != 0);
149 }
150
151 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
152 // Lock the pd_set list. This lock cannot safepoint since the caller holds
153 // a Dictionary entry, which can be moved if the Dictionary is resized.
154 MutexLocker ml(ProtectionDomainSet_lock, Mutex::_no_safepoint_check_flag);
155 #ifdef ASSERT
156 if (protection_domain == instance_klass()->protection_domain()) {
157 // Ensure this doesn't show up in the pd_set (invariant)
158 bool in_pd_set = false;
159 for (ProtectionDomainEntry* current = pd_set();
160 current != NULL;
161 current = current->next()) {
162 if (current->object_no_keepalive() == protection_domain) {
163 in_pd_set = true;
164 break;
165 }
166 }
167 if (in_pd_set) {
168 assert(false, "A klass's protection domain should not show up "
169 "in its sys. dict. PD set");
170 }
171 }
172 #endif /* ASSERT */
173
174 if (protection_domain == instance_klass()->protection_domain()) {
175 // Succeeds trivially
176 return true;
177 }
178
179 for (ProtectionDomainEntry* current = pd_set();
180 current != NULL;
181 current = current->next()) {
182 if (current->object_no_keepalive() == protection_domain) return true;
183 }
184 return false;
185 }
186
187
188 void DictionaryEntry::add_protection_domain(Dictionary* dict, Handle protection_domain) {
189 assert_locked_or_safepoint(SystemDictionary_lock);
190 if (!contains_protection_domain(protection_domain())) {
191 ProtectionDomainCacheEntry* entry = SystemDictionary::cache_get(protection_domain);
192 // The pd_set in the dictionary entry is protected by a low level lock.
193 // With concurrent PD table cleanup, these links could be broken.
194 MutexLocker ml(ProtectionDomainSet_lock, Mutex::_no_safepoint_check_flag);
195 ProtectionDomainEntry* new_head =
196 new ProtectionDomainEntry(entry, pd_set());
197 set_pd_set(new_head);
198 }
199 LogTarget(Trace, protectiondomain) lt;
200 if (lt.is_enabled()) {
201 LogStream ls(lt);
202 print_count(&ls);
203 }
204 }
205
206 // Just the classes from defining class loaders
207 void Dictionary::classes_do(void f(InstanceKlass*)) {
208 for (int index = 0; index < table_size(); index++) {
209 for (DictionaryEntry* probe = bucket(index);
210 probe != NULL;
211 probe = probe->next()) {
212 InstanceKlass* k = probe->instance_klass();
213 if (loader_data() == k->class_loader_data()) {
214 f(k);
215 }
216 }
217 }
218 }
219
220 // Added for initialize_itable_for_klass to handle exceptions
221 // Just the classes from defining class loaders
222 void Dictionary::classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
223 for (int index = 0; index < table_size(); index++) {
224 for (DictionaryEntry* probe = bucket(index);
225 probe != NULL;
226 probe = probe->next()) {
227 InstanceKlass* k = probe->instance_klass();
228 if (loader_data() == k->class_loader_data()) {
229 f(k, CHECK);
230 }
231 }
232 }
233 }
234
235 // All classes, and their class loaders, including initiating class loaders
236 void Dictionary::all_entries_do(KlassClosure* closure) {
237 for (int index = 0; index < table_size(); index++) {
238 for (DictionaryEntry* probe = bucket(index);
239 probe != NULL;
240 probe = probe->next()) {
241 InstanceKlass* k = probe->instance_klass();
242 closure->do_klass(k);
243 }
244 }
245 }
246
247 // Used to scan and relocate the classes during CDS archive dump.
248 void Dictionary::classes_do(MetaspaceClosure* it) {
249 Arguments::assert_is_dumping_archive();
250 for (int index = 0; index < table_size(); index++) {
251 for (DictionaryEntry* probe = bucket(index);
252 probe != NULL;
253 probe = probe->next()) {
254 it->push(probe->klass_addr());
255 }
256 }
257 }
258
259
260
261 // Add a loaded class to the dictionary.
262 // Readers of the SystemDictionary aren't always locked, so _buckets
263 // is volatile. The store of the next field in the constructor is
264 // also cast to volatile; we do this to ensure store order is maintained
265 // by the compilers.
266
267 void Dictionary::add_klass(unsigned int hash, Symbol* class_name,
268 InstanceKlass* obj) {
269 assert_locked_or_safepoint(SystemDictionary_lock);
270 assert(obj != NULL, "adding NULL obj");
271 assert(obj->name() == class_name, "sanity check on name");
272
273 DictionaryEntry* entry = new_entry(hash, obj);
274 int index = hash_to_index(hash);
275 add_entry(index, entry);
276 check_if_needs_resize();
277 }
278
279
280 // This routine does not lock the dictionary.
281 //
282 // Since readers don't hold a lock, we must make sure that system
283 // dictionary entries are only removed at a safepoint (when only one
284 // thread is running), and are added to in a safe way (all links must
285 // be updated in an MT-safe manner).
286 //
287 // Callers should be aware that an entry could be added just after
288 // _buckets[index] is read here, so the caller will not see the new entry.
289 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
290 Symbol* class_name) {
291 for (DictionaryEntry* entry = bucket(index);
292 entry != NULL;
293 entry = entry->next()) {
294 if (entry->hash() == hash && entry->equals(class_name)) {
295 return entry;
296 }
297 }
298 return NULL;
299 }
300
301
302 InstanceKlass* Dictionary::find(unsigned int hash, Symbol* name,
303 Handle protection_domain) {
304 NoSafepointVerifier nsv;
305
306 int index = hash_to_index(hash);
307 DictionaryEntry* entry = get_entry(index, hash, name);
308 if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
309 return entry->instance_klass();
310 } else {
311 return NULL;
312 }
313 }
314
315 InstanceKlass* Dictionary::find_class(int index, unsigned int hash,
316 Symbol* name) {
317 assert_locked_or_safepoint(SystemDictionary_lock);
318 assert (index == index_for(name), "incorrect index?");
319
320 DictionaryEntry* entry = get_entry(index, hash, name);
321 return (entry != NULL) ? entry->instance_klass() : NULL;
322 }
323
324 InstanceKlass* Dictionary::replace_class(int index, unsigned hash,
325 Symbol* name, InstanceKlass* k) {
326 DictionaryEntry* entry = get_entry(index, hash, name);
327 assert(entry != NULL, "InstanceKlass k should exist in dictionary");
328
329 InstanceKlass** addr = entry->klass_addr();
330 InstanceKlass* old = *addr;
331 *addr = k;
332 return old;
333 }
334
335 void Dictionary::add_protection_domain(int index, unsigned int hash,
336 InstanceKlass* klass,
337 Handle protection_domain,
338 TRAPS) {
339 Symbol* klass_name = klass->name();
340 DictionaryEntry* entry = get_entry(index, hash, klass_name);
341
342 assert(entry != NULL,"entry must be present, we just created it");
343 assert(protection_domain() != NULL,
344 "real protection domain should be present");
345
346 entry->add_protection_domain(this, protection_domain);
347
348 #ifdef ASSERT
349 assert(loader_data() != ClassLoaderData::the_null_class_loader_data(), "doesn't make sense");
350 #endif
351
352 assert(entry->contains_protection_domain(protection_domain()),
353 "now protection domain should be present");
354 }
355
356
357 bool Dictionary::is_valid_protection_domain(unsigned int hash,
358 Symbol* name,
359 Handle protection_domain) {
360 int index = hash_to_index(hash);
361 DictionaryEntry* entry = get_entry(index, hash, name);
362 return entry->is_valid_protection_domain(protection_domain);
363 }
364
365 // During class loading we may have cached a protection domain that has
366 // since been unreferenced, so this entry should be cleared.
367 void Dictionary::clean_cached_protection_domains() {
368 assert_locked_or_safepoint(SystemDictionary_lock);
369 assert(!loader_data()->has_class_mirror_holder(), "cld should have a ClassLoader holder not a Class holder");
370
371 if (loader_data()->is_the_null_class_loader_data()) {
372 // Classes in the boot loader are not loaded with protection domains
373 return;
374 }
375
376 for (int index = 0; index < table_size(); index++) {
377 for (DictionaryEntry* probe = bucket(index);
378 probe != NULL;
379 probe = probe->next()) {
380 Klass* e = probe->instance_klass();
381
382 MutexLocker ml(ProtectionDomainSet_lock, Mutex::_no_safepoint_check_flag);
383 ProtectionDomainEntry* current = probe->pd_set();
384 ProtectionDomainEntry* prev = NULL;
385 while (current != NULL) {
386 if (current->object_no_keepalive() == NULL) {
387 LogTarget(Debug, protectiondomain) lt;
388 if (lt.is_enabled()) {
389 ResourceMark rm;
390 // Print out trace information
391 LogStream ls(lt);
392 ls.print_cr("PD in set is not alive:");
393 ls.print("class loader: "); loader_data()->class_loader()->print_value_on(&ls);
394 ls.print(" loading: "); probe->instance_klass()->print_value_on(&ls);
395 ls.cr();
396 }
397 if (probe->pd_set() == current) {
398 probe->set_pd_set(current->next());
399 } else {
400 assert(prev != NULL, "should be set by alive entry");
401 prev->set_next(current->next());
402 }
403 ProtectionDomainEntry* to_delete = current;
404 current = current->next();
405 delete to_delete;
406 } else {
407 prev = current;
408 current = current->next();
409 }
410 }
411 }
412 }
413 }
414
415 oop SymbolPropertyEntry::method_type() const {
416 return _method_type.resolve();
417 }
418
419 void SymbolPropertyEntry::set_method_type(oop p) {
420 _method_type = OopHandle(Universe::vm_global(), p);
421 }
422
423 void SymbolPropertyEntry::free_entry() {
424 // decrement Symbol refcount here because hashtable doesn't.
425 literal()->decrement_refcount();
426 // Free OopHandle
427 _method_type.release(Universe::vm_global());
428 }
429
430 SymbolPropertyTable::SymbolPropertyTable(int table_size)
431 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry))
432 {
433 }
434 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t,
435 int number_of_entries)
436 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)
437 {
438 }
439
440
441 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,
442 Symbol* sym,
443 intptr_t sym_mode) {
444 assert(index == index_for(sym, sym_mode), "incorrect index?");
445 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
446 if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) {
447 return p;
448 }
449 }
450 return NULL;
451 }
452
453
454 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,
455 Symbol* sym, intptr_t sym_mode) {
456 assert_locked_or_safepoint(SystemDictionary_lock);
457 assert(index == index_for(sym, sym_mode), "incorrect index?");
458 assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");
459
460 SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode);
461 Hashtable<Symbol*, mtSymbol>::add_entry(index, p);
462 return p;
463 }
464
465 void SymbolPropertyTable::methods_do(void f(Method*)) {
466 for (int index = 0; index < table_size(); index++) {
467 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
468 Method* prop = p->method();
469 if (prop != NULL) {
470 f((Method*)prop);
471 }
472 }
473 }
474 }
475
476 void SymbolPropertyTable::free_entry(SymbolPropertyEntry* entry) {
477 entry->free_entry();
478 Hashtable<Symbol*, mtSymbol>::free_entry(entry);
479 }
480
481 void DictionaryEntry::verify_protection_domain_set() {
482 MutexLocker ml(ProtectionDomainSet_lock, Mutex::_no_safepoint_check_flag);
483 for (ProtectionDomainEntry* current = pd_set(); // accessed at a safepoint
484 current != NULL;
485 current = current->_next) {
486 guarantee(oopDesc::is_oop_or_null(current->_pd_cache->object_no_keepalive()), "Invalid oop");
487 }
488 }
489
490 void DictionaryEntry::print_count(outputStream *st) {
491 MutexLocker ml(ProtectionDomainSet_lock, Mutex::_no_safepoint_check_flag);
492 int count = 0;
493 for (ProtectionDomainEntry* current = pd_set(); // accessed inside SD lock
494 current != NULL;
495 current = current->_next) {
496 count++;
497 }
498 st->print_cr("pd set count = #%d", count);
499 }
500
501 // ----------------------------------------------------------------------------
502
503 void Dictionary::print_on(outputStream* st) const {
504 ResourceMark rm;
505
506 assert(loader_data() != NULL, "loader data should not be null");
507 assert(!loader_data()->has_class_mirror_holder(), "cld should have a ClassLoader holder not a Class holder");
508 st->print_cr("Java dictionary (table_size=%d, classes=%d, resizable=%s)",
509 table_size(), number_of_entries(), BOOL_TO_STR(_resizable));
510 st->print_cr("^ indicates that initiating loader is different from defining loader");
511
512 for (int index = 0; index < table_size(); index++) {
513 for (DictionaryEntry* probe = bucket(index);
514 probe != NULL;
515 probe = probe->next()) {
516 Klass* e = probe->instance_klass();
517 bool is_defining_class =
518 (loader_data() == e->class_loader_data());
519 st->print("%4d: %s%s", index, is_defining_class ? " " : "^", e->external_name());
520 ClassLoaderData* cld = e->class_loader_data();
521 if (!loader_data()->is_the_null_class_loader_data()) {
522 // Class loader output for the dictionary for the null class loader data is
523 // redundant and obvious.
524 st->print(", ");
525 cld->print_value_on(st);
526 }
527 st->cr();
528 }
529 }
530 tty->cr();
531 }
532
533 void DictionaryEntry::verify() {
534 Klass* e = instance_klass();
535 guarantee(e->is_instance_klass(),
536 "Verify of dictionary failed");
537 e->verify();
538 verify_protection_domain_set();
539 }
540
541 void Dictionary::verify() {
542 guarantee(number_of_entries() >= 0, "Verify of dictionary failed");
543
544 ClassLoaderData* cld = loader_data();
545 // class loader must be present; a null class loader is the
546 // boostrap loader
547 guarantee(cld != NULL ||
548 cld->class_loader() == NULL ||
549 cld->class_loader()->is_instance(),
550 "checking type of class_loader");
551
552 ResourceMark rm;
553 stringStream tempst;
554 tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id());
555 verify_table<DictionaryEntry>(tempst.as_string());
556 }