1 /* 2 * Copyright (c) 2003, 2017, 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/sharedClassUtil.hpp" 28 #include "classfile/dictionary.hpp" 29 #include "classfile/protectionDomainCache.hpp" 30 #include "classfile/systemDictionary.hpp" 31 #include "classfile/systemDictionaryShared.hpp" 32 #include "memory/iterator.hpp" 33 #include "memory/resourceArea.hpp" 34 #include "oops/oop.inline.hpp" 35 #include "runtime/orderAccess.inline.hpp" 36 #include "utilities/hashtable.inline.hpp" 37 38 DictionaryEntry* Dictionary::_current_class_entry = NULL; 39 int Dictionary::_current_class_index = 0; 40 41 size_t Dictionary::entry_size() { 42 if (DumpSharedSpaces) { 43 return SystemDictionaryShared::dictionary_entry_size(); 44 } else { 45 return sizeof(DictionaryEntry); 46 } 47 } 48 49 Dictionary::Dictionary(int table_size) 50 : TwoOopHashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size()) { 51 _current_class_index = 0; 52 _current_class_entry = NULL; 53 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize); 54 }; 55 56 57 Dictionary::Dictionary(int table_size, HashtableBucket<mtClass>* t, 58 int number_of_entries) 59 : TwoOopHashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size(), t, number_of_entries) { 60 _current_class_index = 0; 61 _current_class_entry = NULL; 62 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize); 63 }; 64 65 ProtectionDomainCacheEntry* Dictionary::cache_get(Handle protection_domain) { 66 return _pd_cache_table->get(protection_domain); 67 } 68 69 DictionaryEntry* Dictionary::new_entry(unsigned int hash, InstanceKlass* klass, 70 ClassLoaderData* loader_data) { 71 DictionaryEntry* entry = (DictionaryEntry*)Hashtable<InstanceKlass*, mtClass>::new_entry(hash, klass); 72 entry->set_loader_data(loader_data); 73 entry->set_pd_set(NULL); 74 assert(klass->is_instance_klass(), "Must be"); 75 if (DumpSharedSpaces) { 76 SystemDictionaryShared::init_shared_dictionary_entry(klass, entry); 77 } 78 return entry; 79 } 80 81 82 void Dictionary::free_entry(DictionaryEntry* entry) { 83 // avoid recursion when deleting linked list 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 Hashtable<InstanceKlass*, mtClass>::free_entry(entry); 90 } 91 92 93 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const { 94 #ifdef ASSERT 95 if (protection_domain == klass()->protection_domain()) { 96 // Ensure this doesn't show up in the pd_set (invariant) 97 bool in_pd_set = false; 98 for (ProtectionDomainEntry* current = _pd_set; 99 current != NULL; 100 current = current->next()) { 101 if (current->protection_domain() == protection_domain) { 102 in_pd_set = true; 103 break; 104 } 105 } 106 if (in_pd_set) { 107 assert(false, "A klass's protection domain should not show up " 108 "in its sys. dict. PD set"); 109 } 110 } 111 #endif /* ASSERT */ 112 113 if (protection_domain == klass()->protection_domain()) { 114 // Succeeds trivially 115 return true; 116 } 117 118 for (ProtectionDomainEntry* current = _pd_set; 119 current != NULL; 120 current = current->next()) { 121 if (current->protection_domain() == protection_domain) return true; 122 } 123 return false; 124 } 125 126 127 void DictionaryEntry::add_protection_domain(Dictionary* dict, Handle protection_domain) { 128 assert_locked_or_safepoint(SystemDictionary_lock); 129 if (!contains_protection_domain(protection_domain())) { 130 ProtectionDomainCacheEntry* entry = dict->cache_get(protection_domain); 131 ProtectionDomainEntry* new_head = 132 new ProtectionDomainEntry(entry, _pd_set); 133 // Warning: Preserve store ordering. The SystemDictionary is read 134 // without locks. The new ProtectionDomainEntry must be 135 // complete before other threads can be allowed to see it 136 // via a store to _pd_set. 137 OrderAccess::release_store_ptr(&_pd_set, new_head); 138 } 139 if (log_is_enabled(Trace, protectiondomain)) { 140 ResourceMark rm; 141 outputStream* log = Log(protectiondomain)::trace_stream(); 142 print_count(log); 143 } 144 } 145 146 147 void Dictionary::do_unloading() { 148 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 149 150 // Remove unloadable entries and classes from system dictionary 151 DictionaryEntry* probe = NULL; 152 for (int index = 0; index < table_size(); index++) { 153 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) { 154 probe = *p; 155 Klass* e = probe->klass(); 156 ClassLoaderData* loader_data = probe->loader_data(); 157 158 InstanceKlass* ik = InstanceKlass::cast(e); 159 160 // Only unload classes that are not strongly reachable 161 if (!is_strongly_reachable(loader_data, e)) { 162 // Entry was not visited in phase1 (negated test from phase1) 163 assert(!loader_data->is_the_null_class_loader_data(), "unloading entry with null class loader"); 164 ClassLoaderData* k_def_class_loader_data = ik->class_loader_data(); 165 166 // Do we need to delete this system dictionary entry? 167 bool purge_entry = false; 168 169 // Do we need to delete this system dictionary entry? 170 if (loader_data->is_unloading()) { 171 // If the loader is not live this entry should always be 172 // removed (will never be looked up again). 173 purge_entry = true; 174 } else { 175 // The loader in this entry is alive. If the klass is dead, 176 // (determined by checking the defining class loader) 177 // the loader must be an initiating loader (rather than the 178 // defining loader). Remove this entry. 179 if (k_def_class_loader_data->is_unloading()) { 180 // If we get here, the class_loader_data must not be the defining 181 // loader, it must be an initiating one. 182 assert(k_def_class_loader_data != loader_data, 183 "cannot have live defining loader and unreachable klass"); 184 // Loader is live, but class and its defining loader are dead. 185 // Remove the entry. The class is going away. 186 purge_entry = true; 187 } 188 } 189 190 if (purge_entry) { 191 *p = probe->next(); 192 if (probe == _current_class_entry) { 193 _current_class_entry = NULL; 194 } 195 free_entry(probe); 196 continue; 197 } 198 } 199 p = probe->next_addr(); 200 } 201 } 202 } 203 204 void Dictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) { 205 // Do strong roots marking if the closures are the same. 206 if (strong == weak || !ClassUnloading) { 207 // Only the protection domain oops contain references into the heap. Iterate 208 // over all of them. 209 _pd_cache_table->oops_do(strong); 210 } else { 211 if (weak != NULL) { 212 _pd_cache_table->oops_do(weak); 213 } 214 } 215 } 216 217 218 void Dictionary::remove_classes_in_error_state() { 219 assert(DumpSharedSpaces, "supported only when dumping"); 220 DictionaryEntry* probe = NULL; 221 for (int index = 0; index < table_size(); index++) { 222 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) { 223 probe = *p; 224 InstanceKlass* ik = InstanceKlass::cast(probe->klass()); 225 if (ik->is_in_error_state()) { // purge this entry 226 *p = probe->next(); 227 if (probe == _current_class_entry) { 228 _current_class_entry = NULL; 229 } 230 free_entry(probe); 231 ResourceMark rm; 232 tty->print_cr("Preload Warning: Removed error class: %s", ik->external_name()); 233 continue; 234 } 235 236 p = probe->next_addr(); 237 } 238 } 239 } 240 241 // Just the classes from defining class loaders 242 void Dictionary::classes_do(void f(Klass*)) { 243 for (int index = 0; index < table_size(); index++) { 244 for (DictionaryEntry* probe = bucket(index); 245 probe != NULL; 246 probe = probe->next()) { 247 Klass* k = probe->klass(); 248 if (probe->loader_data() == k->class_loader_data()) { 249 f(k); 250 } 251 } 252 } 253 } 254 255 // Added for initialize_itable_for_klass to handle exceptions 256 // Just the classes from defining class loaders 257 void Dictionary::classes_do(void f(Klass*, TRAPS), TRAPS) { 258 for (int index = 0; index < table_size(); index++) { 259 for (DictionaryEntry* probe = bucket(index); 260 probe != NULL; 261 probe = probe->next()) { 262 Klass* k = probe->klass(); 263 if (probe->loader_data() == k->class_loader_data()) { 264 f(k, CHECK); 265 } 266 } 267 } 268 } 269 270 // All classes, and their class loaders 271 // Don't iterate over placeholders 272 void Dictionary::classes_do(void f(Klass*, ClassLoaderData*)) { 273 for (int index = 0; index < table_size(); index++) { 274 for (DictionaryEntry* probe = bucket(index); 275 probe != NULL; 276 probe = probe->next()) { 277 Klass* k = probe->klass(); 278 f(k, probe->loader_data()); 279 } 280 } 281 } 282 283 void Dictionary::oops_do(OopClosure* f) { 284 // Only the protection domain oops contain references into the heap. Iterate 285 // over all of them. 286 _pd_cache_table->oops_do(f); 287 } 288 289 void Dictionary::unlink(BoolObjectClosure* is_alive) { 290 // Only the protection domain cache table may contain references to the heap 291 // that need to be unlinked. 292 _pd_cache_table->unlink(is_alive); 293 } 294 295 InstanceKlass* Dictionary::try_get_next_class() { 296 while (true) { 297 if (_current_class_entry != NULL) { 298 InstanceKlass* k = _current_class_entry->klass(); 299 _current_class_entry = _current_class_entry->next(); 300 return k; 301 } 302 _current_class_index = (_current_class_index + 1) % table_size(); 303 _current_class_entry = bucket(_current_class_index); 304 } 305 // never reached 306 } 307 308 // Add a loaded class to the system dictionary. 309 // Readers of the SystemDictionary aren't always locked, so _buckets 310 // is volatile. The store of the next field in the constructor is 311 // also cast to volatile; we do this to ensure store order is maintained 312 // by the compilers. 313 314 void Dictionary::add_klass(Symbol* class_name, ClassLoaderData* loader_data, 315 InstanceKlass* obj) { 316 assert_locked_or_safepoint(SystemDictionary_lock); 317 assert(obj != NULL, "adding NULL obj"); 318 assert(obj->name() == class_name, "sanity check on name"); 319 assert(loader_data != NULL, "Must be non-NULL"); 320 321 unsigned int hash = compute_hash(class_name, loader_data); 322 int index = hash_to_index(hash); 323 DictionaryEntry* entry = new_entry(hash, obj, loader_data); 324 add_entry(index, entry); 325 } 326 327 328 // This routine does not lock the system dictionary. 329 // 330 // Since readers don't hold a lock, we must make sure that system 331 // dictionary entries are only removed at a safepoint (when only one 332 // thread is running), and are added to in a safe way (all links must 333 // be updated in an MT-safe manner). 334 // 335 // Callers should be aware that an entry could be added just after 336 // _buckets[index] is read here, so the caller will not see the new entry. 337 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash, 338 Symbol* class_name, 339 ClassLoaderData* loader_data) { 340 for (DictionaryEntry* entry = bucket(index); 341 entry != NULL; 342 entry = entry->next()) { 343 if (entry->hash() == hash && entry->equals(class_name, loader_data)) { 344 return entry; 345 } 346 } 347 return NULL; 348 } 349 350 351 InstanceKlass* Dictionary::find(int index, unsigned int hash, Symbol* name, 352 ClassLoaderData* loader_data, Handle protection_domain, TRAPS) { 353 DictionaryEntry* entry = get_entry(index, hash, name, loader_data); 354 if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) { 355 return entry->klass(); 356 } else { 357 return NULL; 358 } 359 } 360 361 362 InstanceKlass* Dictionary::find_class(int index, unsigned int hash, 363 Symbol* name, ClassLoaderData* loader_data) { 364 assert_locked_or_safepoint(SystemDictionary_lock); 365 assert (index == index_for(name, loader_data), "incorrect index?"); 366 367 DictionaryEntry* entry = get_entry(index, hash, name, loader_data); 368 return (entry != NULL) ? entry->klass() : NULL; 369 } 370 371 372 // Variant of find_class for shared classes. No locking required, as 373 // that table is static. 374 375 InstanceKlass* Dictionary::find_shared_class(int index, unsigned int hash, 376 Symbol* name) { 377 assert (index == index_for(name, NULL), "incorrect index?"); 378 379 DictionaryEntry* entry = get_entry(index, hash, name, NULL); 380 return (entry != NULL) ? entry->klass() : NULL; 381 } 382 383 384 void Dictionary::add_protection_domain(int index, unsigned int hash, 385 InstanceKlass* klass, 386 ClassLoaderData* loader_data, Handle protection_domain, 387 TRAPS) { 388 Symbol* klass_name = klass->name(); 389 DictionaryEntry* entry = get_entry(index, hash, klass_name, loader_data); 390 391 assert(entry != NULL,"entry must be present, we just created it"); 392 assert(protection_domain() != NULL, 393 "real protection domain should be present"); 394 395 entry->add_protection_domain(this, protection_domain); 396 397 assert(entry->contains_protection_domain(protection_domain()), 398 "now protection domain should be present"); 399 } 400 401 402 bool Dictionary::is_valid_protection_domain(int index, unsigned int hash, 403 Symbol* name, 404 ClassLoaderData* loader_data, 405 Handle protection_domain) { 406 DictionaryEntry* entry = get_entry(index, hash, name, loader_data); 407 return entry->is_valid_protection_domain(protection_domain); 408 } 409 410 411 void Dictionary::reorder_dictionary() { 412 413 // Copy all the dictionary entries into a single master list. 414 415 DictionaryEntry* master_list = NULL; 416 for (int i = 0; i < table_size(); ++i) { 417 DictionaryEntry* p = bucket(i); 418 while (p != NULL) { 419 DictionaryEntry* tmp; 420 tmp = p->next(); 421 p->set_next(master_list); 422 master_list = p; 423 p = tmp; 424 } 425 set_entry(i, NULL); 426 } 427 428 // Add the dictionary entries back to the list in the correct buckets. 429 while (master_list != NULL) { 430 DictionaryEntry* p = master_list; 431 master_list = master_list->next(); 432 p->set_next(NULL); 433 Symbol* class_name = p->klass()->name(); 434 // Since the null class loader data isn't copied to the CDS archive, 435 // compute the hash with NULL for loader data. 436 unsigned int hash = compute_hash(class_name, NULL); 437 int index = hash_to_index(hash); 438 p->set_hash(hash); 439 p->set_loader_data(NULL); // loader_data isn't copied to CDS 440 p->set_next(bucket(index)); 441 set_entry(index, p); 442 } 443 } 444 445 446 SymbolPropertyTable::SymbolPropertyTable(int table_size) 447 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry)) 448 { 449 } 450 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t, 451 int number_of_entries) 452 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries) 453 { 454 } 455 456 457 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash, 458 Symbol* sym, 459 intptr_t sym_mode) { 460 assert(index == index_for(sym, sym_mode), "incorrect index?"); 461 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) { 462 if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) { 463 return p; 464 } 465 } 466 return NULL; 467 } 468 469 470 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash, 471 Symbol* sym, intptr_t sym_mode) { 472 assert_locked_or_safepoint(SystemDictionary_lock); 473 assert(index == index_for(sym, sym_mode), "incorrect index?"); 474 assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry"); 475 476 SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode); 477 Hashtable<Symbol*, mtSymbol>::add_entry(index, p); 478 return p; 479 } 480 481 void SymbolPropertyTable::oops_do(OopClosure* f) { 482 for (int index = 0; index < table_size(); index++) { 483 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) { 484 if (p->method_type() != NULL) { 485 f->do_oop(p->method_type_addr()); 486 } 487 } 488 } 489 } 490 491 void SymbolPropertyTable::methods_do(void f(Method*)) { 492 for (int index = 0; index < table_size(); index++) { 493 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) { 494 Method* prop = p->method(); 495 if (prop != NULL) { 496 f((Method*)prop); 497 } 498 } 499 } 500 } 501 502 503 // ---------------------------------------------------------------------------- 504 505 void Dictionary::print(bool details) { 506 ResourceMark rm; 507 508 if (details) { 509 tty->print_cr("Java system dictionary (table_size=%d, classes=%d)", 510 table_size(), number_of_entries()); 511 tty->print_cr("^ indicates that initiating loader is different from " 512 "defining loader"); 513 } 514 515 for (int index = 0; index < table_size(); index++) { 516 for (DictionaryEntry* probe = bucket(index); 517 probe != NULL; 518 probe = probe->next()) { 519 Klass* e = probe->klass(); 520 ClassLoaderData* loader_data = probe->loader_data(); 521 bool is_defining_class = 522 (loader_data == e->class_loader_data()); 523 if (details) { 524 tty->print("%4d: ", index); 525 } 526 tty->print("%s%s", ((!details) || is_defining_class) ? " " : "^", 527 e->external_name()); 528 529 if (details) { 530 tty->print(", loader "); 531 if (loader_data != NULL) { 532 loader_data->print_value(); 533 } else { 534 tty->print("NULL"); 535 } 536 } 537 tty->cr(); 538 } 539 } 540 541 if (details) { 542 tty->cr(); 543 _pd_cache_table->print(); 544 } 545 tty->cr(); 546 } 547 548 void DictionaryEntry::verify() { 549 Klass* e = klass(); 550 ClassLoaderData* cld = loader_data(); 551 guarantee(e->is_instance_klass(), 552 "Verify of system dictionary failed"); 553 // class loader must be present; a null class loader is the 554 // boostrap loader 555 guarantee(cld != NULL || DumpSharedSpaces || 556 cld->class_loader() == NULL || 557 cld->class_loader()->is_instance(), 558 "checking type of class_loader"); 559 e->verify(); 560 verify_protection_domain_set(); 561 } 562 563 void Dictionary::verify() { 564 guarantee(number_of_entries() >= 0, "Verify of system dictionary failed"); 565 verify_table<DictionaryEntry>("System Dictionary"); 566 _pd_cache_table->verify(); 567 } 568