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 "oops/oop.inline.hpp"
36 #include "runtime/mutexLocker.hpp"
37 #include "runtime/safepointVerifiers.hpp"
38 #include "utilities/hashtable.inline.hpp"
39
40 // Optimization: if any dictionary needs resizing, we set this flag,
41 // so that we dont't have to walk all dictionaries to check if any actually
42 // needs resizing, which is costly to do at Safepoint.
43 bool Dictionary::_some_dictionary_needs_resizing = false;
44
45 Dictionary::Dictionary(ClassLoaderData* loader_data, int table_size, bool resizable)
46 : Hashtable<InstanceKlass*, mtClass>(table_size, (int)sizeof(DictionaryEntry)),
47 _resizable(resizable), _needs_resizing(false), _loader_data(loader_data) {
48 };
49
50
51 Dictionary::Dictionary(ClassLoaderData* loader_data,
52 int table_size, HashtableBucket<mtClass>* t,
53 int number_of_entries, bool resizable)
54 : Hashtable<InstanceKlass*, mtClass>(table_size, (int)sizeof(DictionaryEntry), t, number_of_entries),
55 _resizable(resizable), _needs_resizing(false), _loader_data(loader_data) {
56 };
57
58 Dictionary::~Dictionary() {
59 DictionaryEntry* probe = NULL;
60 for (int index = 0; index < table_size(); index++) {
61 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {
62 probe = *p;
63 *p = probe->next();
64 free_entry(probe);
65 }
66 }
67 assert(number_of_entries() == 0, "should have removed all entries");
68 assert(new_entry_free_list() == NULL, "entry present on Dictionary's free list");
69 }
70
71 DictionaryEntry* Dictionary::new_entry(unsigned int hash, InstanceKlass* klass) {
72 DictionaryEntry* entry = (DictionaryEntry*)Hashtable<InstanceKlass*, mtClass>::allocate_new_entry(hash, klass);
73 entry->set_pd_set(NULL);
74 assert(klass->is_instance_klass(), "Must be");
75 return entry;
76 }
77
78
79 void Dictionary::free_entry(DictionaryEntry* entry) {
80 // avoid recursion when deleting linked list
81 // pd_set is accessed during a safepoint.
82 // This doesn't require a lock because nothing is reading this
83 // entry anymore. The ClassLoader is dead.
84 while (entry->pd_set() != NULL) {
85 ProtectionDomainEntry* to_delete = entry->pd_set();
86 entry->set_pd_set(to_delete->next());
87 delete to_delete;
88 }
89 // Unlink from the Hashtable prior to freeing
90 unlink_entry(entry);
91 FREE_C_HEAP_ARRAY(char, entry);
92 }
93
94 const int _resize_load_trigger = 5; // load factor that will trigger the resize
95 const double _resize_factor = 2.0; // by how much we will resize using current number of entries
96 const int _resize_max_size = 40423; // the max dictionary size allowed
97 const int _primelist[] = {107, 1009, 2017, 4049, 5051, 10103, 20201, _resize_max_size};
98 const int _prime_array_size = sizeof(_primelist)/sizeof(int);
99
100 // Calculate next "good" dictionary size based on requested count
101 static int calculate_dictionary_size(int requested) {
102 int newsize = _primelist[0];
103 int index = 0;
104 for (newsize = _primelist[index]; index < (_prime_array_size - 1);
105 newsize = _primelist[++index]) {
106 if (requested <= newsize) {
107 break;
108 }
109 }
110 return newsize;
111 }
112
113 bool Dictionary::does_any_dictionary_needs_resizing() {
114 return Dictionary::_some_dictionary_needs_resizing;
115 }
116
117 void Dictionary::check_if_needs_resize() {
118 if (_resizable == true) {
119 if (number_of_entries() > (_resize_load_trigger*table_size())) {
120 _needs_resizing = true;
121 Dictionary::_some_dictionary_needs_resizing = true;
122 }
123 }
124 }
125
126 bool Dictionary::resize_if_needed() {
127 int desired_size = 0;
128 if (_needs_resizing == true) {
129 desired_size = calculate_dictionary_size((int)(_resize_factor*number_of_entries()));
130 if (desired_size >= _resize_max_size) {
131 desired_size = _resize_max_size;
132 // We have reached the limit, turn resizing off
133 _resizable = false;
134 }
135 if ((desired_size != 0) && (desired_size != table_size())) {
136 if (!resize(desired_size)) {
137 // Something went wrong, turn resizing off
138 _resizable = false;
139 }
140 }
141 }
142
143 _needs_resizing = false;
144 Dictionary::_some_dictionary_needs_resizing = false;
145
146 return (desired_size != 0);
147 }
148
149 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
150 // Lock the pd_set list. This lock cannot safepoint since the caller holds
151 // a Dictionary entry, which can be moved if the Dictionary is resized.
152 MutexLocker ml(ProtectionDomainSet_lock, Mutex::_no_safepoint_check_flag);
153 #ifdef ASSERT
154 if (protection_domain == instance_klass()->protection_domain()) {
155 // Ensure this doesn't show up in the pd_set (invariant)
156 bool in_pd_set = false;
157 for (ProtectionDomainEntry* current = pd_set();
158 current != NULL;
159 current = current->next()) {
160 if (current->object_no_keepalive() == protection_domain) {
161 in_pd_set = true;
162 break;
163 }
164 }
165 if (in_pd_set) {
166 assert(false, "A klass's protection domain should not show up "
167 "in its sys. dict. PD set");
168 }
169 }
170 #endif /* ASSERT */
171
172 if (protection_domain == instance_klass()->protection_domain()) {
173 // Succeeds trivially
174 return true;
175 }
176
177 for (ProtectionDomainEntry* current = pd_set();
178 current != NULL;
179 current = current->next()) {
180 if (current->object_no_keepalive() == protection_domain) return true;
181 }
182 return false;
183 }
184
185
186 void DictionaryEntry::add_protection_domain(Dictionary* dict, Handle protection_domain) {
187 assert_locked_or_safepoint(SystemDictionary_lock);
188 if (!contains_protection_domain(protection_domain())) {
189 ProtectionDomainCacheEntry* entry = SystemDictionary::cache_get(protection_domain);
190 // The pd_set in the dictionary entry is protected by a low level lock.
191 // With concurrent PD table cleanup, these links could be broken.
192 MutexLocker ml(ProtectionDomainSet_lock, Mutex::_no_safepoint_check_flag);
193 ProtectionDomainEntry* new_head =
194 new ProtectionDomainEntry(entry, pd_set());
195 set_pd_set(new_head);
196 }
197 LogTarget(Trace, protectiondomain) lt;
198 if (lt.is_enabled()) {
199 LogStream ls(lt);
200 print_count(&ls);
201 }
202 }
203
204 // Just the classes from defining class loaders
205 void Dictionary::classes_do(void f(InstanceKlass*)) {
206 for (int index = 0; index < table_size(); index++) {
207 for (DictionaryEntry* probe = bucket(index);
208 probe != NULL;
209 probe = probe->next()) {
210 InstanceKlass* k = probe->instance_klass();
211 if (loader_data() == k->class_loader_data()) {
212 f(k);
213 }
214 }
215 }
216 }
217
218 // Added for initialize_itable_for_klass to handle exceptions
219 // Just the classes from defining class loaders
220 void Dictionary::classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
221 for (int index = 0; index < table_size(); index++) {
222 for (DictionaryEntry* probe = bucket(index);
223 probe != NULL;
224 probe = probe->next()) {
225 InstanceKlass* k = probe->instance_klass();
226 if (loader_data() == k->class_loader_data()) {
227 f(k, CHECK);
228 }
229 }
230 }
231 }
232
233 // All classes, and their class loaders, including initiating class loaders
234 void Dictionary::all_entries_do(KlassClosure* closure) {
235 for (int index = 0; index < table_size(); index++) {
236 for (DictionaryEntry* probe = bucket(index);
237 probe != NULL;
238 probe = probe->next()) {
239 InstanceKlass* k = probe->instance_klass();
240 closure->do_klass(k);
241 }
242 }
243 }
244
245 // Used to scan and relocate the classes during CDS archive dump.
246 void Dictionary::classes_do(MetaspaceClosure* it) {
247 Arguments::assert_is_dumping_archive();
248 for (int index = 0; index < table_size(); index++) {
249 for (DictionaryEntry* probe = bucket(index);
250 probe != NULL;
251 probe = probe->next()) {
252 it->push(probe->klass_addr());
253 }
254 }
255 }
256
257
258
259 // Add a loaded class to the dictionary.
260 // Readers of the SystemDictionary aren't always locked, so _buckets
261 // is volatile. The store of the next field in the constructor is
262 // also cast to volatile; we do this to ensure store order is maintained
263 // by the compilers.
264
265 void Dictionary::add_klass(unsigned int hash, Symbol* class_name,
266 InstanceKlass* obj) {
267 assert_locked_or_safepoint(SystemDictionary_lock);
268 assert(obj != NULL, "adding NULL obj");
269 assert(obj->name() == class_name, "sanity check on name");
270
271 DictionaryEntry* entry = new_entry(hash, obj);
272 int index = hash_to_index(hash);
273 add_entry(index, entry);
274 check_if_needs_resize();
275 }
276
277
278 // This routine does not lock the dictionary.
279 //
280 // Since readers don't hold a lock, we must make sure that system
281 // dictionary entries are only removed at a safepoint (when only one
282 // thread is running), and are added to in a safe way (all links must
283 // be updated in an MT-safe manner).
284 //
285 // Callers should be aware that an entry could be added just after
286 // _buckets[index] is read here, so the caller will not see the new entry.
287 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,
288 Symbol* class_name) {
289 for (DictionaryEntry* entry = bucket(index);
290 entry != NULL;
291 entry = entry->next()) {
292 if (entry->hash() == hash && entry->equals(class_name)) {
293 return entry;
294 }
295 }
296 return NULL;
297 }
298
299
300 InstanceKlass* Dictionary::find(unsigned int hash, Symbol* name,
301 Handle protection_domain) {
302 NoSafepointVerifier nsv;
303
304 int index = hash_to_index(hash);
305 DictionaryEntry* entry = get_entry(index, hash, name);
306 if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
307 return entry->instance_klass();
308 } else {
309 return NULL;
310 }
311 }
312
313 InstanceKlass* Dictionary::find_class(int index, unsigned int hash,
314 Symbol* name) {
315 assert_locked_or_safepoint(SystemDictionary_lock);
316 assert (index == index_for(name), "incorrect index?");
317
318 DictionaryEntry* entry = get_entry(index, hash, name);
319 return (entry != NULL) ? entry->instance_klass() : NULL;
320 }
321
322
323 void Dictionary::add_protection_domain(int index, unsigned int hash,
324 InstanceKlass* klass,
325 Handle protection_domain,
326 TRAPS) {
327 Symbol* klass_name = klass->name();
328 DictionaryEntry* entry = get_entry(index, hash, klass_name);
329
330 assert(entry != NULL,"entry must be present, we just created it");
331 assert(protection_domain() != NULL,
332 "real protection domain should be present");
333
334 entry->add_protection_domain(this, protection_domain);
335
336 #ifdef ASSERT
337 assert(loader_data() != ClassLoaderData::the_null_class_loader_data(), "doesn't make sense");
338 #endif
339
340 assert(entry->contains_protection_domain(protection_domain()),
341 "now protection domain should be present");
342 }
343
344
345 bool Dictionary::is_valid_protection_domain(unsigned int hash,
346 Symbol* name,
347 Handle protection_domain) {
348 int index = hash_to_index(hash);
349 DictionaryEntry* entry = get_entry(index, hash, name);
350 return entry->is_valid_protection_domain(protection_domain);
351 }
352
353 // During class loading we may have cached a protection domain that has
354 // since been unreferenced, so this entry should be cleared.
355 void Dictionary::clean_cached_protection_domains() {
356 assert_locked_or_safepoint(SystemDictionary_lock);
357 assert(!loader_data()->has_class_mirror_holder(), "cld should have a ClassLoader holder not a Class holder");
358
359 if (loader_data()->is_the_null_class_loader_data()) {
360 // Classes in the boot loader are not loaded with protection domains
361 return;
362 }
363
364 for (int index = 0; index < table_size(); index++) {
365 for (DictionaryEntry* probe = bucket(index);
366 probe != NULL;
367 probe = probe->next()) {
368 Klass* e = probe->instance_klass();
369
370 MutexLocker ml(ProtectionDomainSet_lock, Mutex::_no_safepoint_check_flag);
371 ProtectionDomainEntry* current = probe->pd_set();
372 ProtectionDomainEntry* prev = NULL;
373 while (current != NULL) {
374 if (current->object_no_keepalive() == NULL) {
375 LogTarget(Debug, protectiondomain) lt;
376 if (lt.is_enabled()) {
377 ResourceMark rm;
378 // Print out trace information
379 LogStream ls(lt);
380 ls.print_cr("PD in set is not alive:");
381 ls.print("class loader: "); loader_data()->class_loader()->print_value_on(&ls);
382 ls.print(" loading: "); probe->instance_klass()->print_value_on(&ls);
383 ls.cr();
384 }
385 if (probe->pd_set() == current) {
386 probe->set_pd_set(current->next());
387 } else {
388 assert(prev != NULL, "should be set by alive entry");
389 prev->set_next(current->next());
390 }
391 ProtectionDomainEntry* to_delete = current;
392 current = current->next();
393 delete to_delete;
394 } else {
395 prev = current;
396 current = current->next();
397 }
398 }
399 }
400 }
401 }
402
403
404 SymbolPropertyTable::SymbolPropertyTable(int table_size)
405 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry))
406 {
407 }
408 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t,
409 int number_of_entries)
410 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)
411 {
412 }
413
414
415 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,
416 Symbol* sym,
417 intptr_t sym_mode) {
418 assert(index == index_for(sym, sym_mode), "incorrect index?");
419 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
420 if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) {
421 return p;
422 }
423 }
424 return NULL;
425 }
426
427
428 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,
429 Symbol* sym, intptr_t sym_mode) {
430 assert_locked_or_safepoint(SystemDictionary_lock);
431 assert(index == index_for(sym, sym_mode), "incorrect index?");
432 assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");
433
434 SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode);
435 Hashtable<Symbol*, mtSymbol>::add_entry(index, p);
436 return p;
437 }
438
439 void SymbolPropertyTable::oops_do(OopClosure* f) {
440 for (int index = 0; index < table_size(); index++) {
441 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
442 if (p->method_type() != NULL) {
443 f->do_oop(p->method_type_addr());
444 }
445 }
446 }
447 }
448
449 void SymbolPropertyTable::methods_do(void f(Method*)) {
450 for (int index = 0; index < table_size(); index++) {
451 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {
452 Method* prop = p->method();
453 if (prop != NULL) {
454 f((Method*)prop);
455 }
456 }
457 }
458 }
459
460 void DictionaryEntry::verify_protection_domain_set() {
461 MutexLocker ml(ProtectionDomainSet_lock, Mutex::_no_safepoint_check_flag);
462 for (ProtectionDomainEntry* current = pd_set(); // accessed at a safepoint
463 current != NULL;
464 current = current->_next) {
465 guarantee(oopDesc::is_oop_or_null(current->_pd_cache->object_no_keepalive()), "Invalid oop");
466 }
467 }
468
469 void DictionaryEntry::print_count(outputStream *st) {
470 MutexLocker ml(ProtectionDomainSet_lock, Mutex::_no_safepoint_check_flag);
471 int count = 0;
472 for (ProtectionDomainEntry* current = pd_set(); // accessed inside SD lock
473 current != NULL;
474 current = current->_next) {
475 count++;
476 }
477 st->print_cr("pd set count = #%d", count);
478 }
479
480 // ----------------------------------------------------------------------------
481
482 void Dictionary::print_on(outputStream* st) const {
483 ResourceMark rm;
484
485 assert(loader_data() != NULL, "loader data should not be null");
486 assert(!loader_data()->has_class_mirror_holder(), "cld should have a ClassLoader holder not a Class holder");
487 st->print_cr("Java dictionary (table_size=%d, classes=%d, resizable=%s)",
488 table_size(), number_of_entries(), BOOL_TO_STR(_resizable));
489 st->print_cr("^ indicates that initiating loader is different from defining loader");
490
491 for (int index = 0; index < table_size(); index++) {
492 for (DictionaryEntry* probe = bucket(index);
493 probe != NULL;
494 probe = probe->next()) {
495 Klass* e = probe->instance_klass();
496 bool is_defining_class =
497 (loader_data() == e->class_loader_data());
498 st->print("%4d: %s%s", index, is_defining_class ? " " : "^", e->external_name());
499 ClassLoaderData* cld = e->class_loader_data();
500 if (!loader_data()->is_the_null_class_loader_data()) {
501 // Class loader output for the dictionary for the null class loader data is
502 // redundant and obvious.
503 st->print(", ");
504 cld->print_value_on(st);
505 }
506 st->cr();
507 }
508 }
509 tty->cr();
510 }
511
512 void DictionaryEntry::verify() {
513 Klass* e = instance_klass();
514 guarantee(e->is_instance_klass(),
515 "Verify of dictionary failed");
516 e->verify();
517 verify_protection_domain_set();
518 }
519
520 void Dictionary::verify() {
521 guarantee(number_of_entries() >= 0, "Verify of dictionary failed");
522
523 ClassLoaderData* cld = loader_data();
524 // class loader must be present; a null class loader is the
525 // boostrap loader
526 guarantee(cld != NULL ||
527 cld->class_loader() == NULL ||
528 cld->class_loader()->is_instance(),
529 "checking type of class_loader");
530
531 ResourceMark rm;
532 stringStream tempst;
533 tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id());
534 verify_table<DictionaryEntry>(tempst.as_string());
535 }