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 "logging/log.hpp" 33 #include "logging/logStream.hpp" 34 #include "memory/iterator.hpp" 35 #include "memory/metaspaceClosure.hpp" 36 #include "memory/resourceArea.hpp" 37 #include "oops/oop.inline.hpp" 38 #include "runtime/orderAccess.inline.hpp" 39 #include "utilities/hashtable.inline.hpp" 40 41 DictionaryEntry* Dictionary::_current_class_entry = NULL; 42 int Dictionary::_current_class_index = 0; 43 44 size_t Dictionary::entry_size() { 45 if (DumpSharedSpaces) { 46 return SystemDictionaryShared::dictionary_entry_size(); 47 } else { 48 return sizeof(DictionaryEntry); 49 } 50 } 51 52 Dictionary::Dictionary(int table_size) 53 : TwoOopHashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size()) { 54 _current_class_index = 0; 55 _current_class_entry = NULL; 56 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize); 57 }; 58 59 60 Dictionary::Dictionary(int table_size, HashtableBucket<mtClass>* t, 61 int number_of_entries) 62 : TwoOopHashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size(), t, number_of_entries) { 63 _current_class_index = 0; 64 _current_class_entry = NULL; 65 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize); 66 }; 67 68 ProtectionDomainCacheEntry* Dictionary::cache_get(Handle protection_domain) { 69 return _pd_cache_table->get(protection_domain); 70 } 71 72 DictionaryEntry* Dictionary::new_entry(unsigned int hash, InstanceKlass* klass, 73 ClassLoaderData* loader_data) { 74 DictionaryEntry* entry = (DictionaryEntry*)Hashtable<InstanceKlass*, mtClass>::new_entry(hash, klass); 75 entry->set_loader_data(loader_data); 76 entry->set_pd_set(NULL); 77 assert(klass->is_instance_klass(), "Must be"); 78 if (DumpSharedSpaces) { 79 SystemDictionaryShared::init_shared_dictionary_entry(klass, entry); 80 } 81 return entry; 82 } 83 84 85 void Dictionary::free_entry(DictionaryEntry* entry) { 86 // avoid recursion when deleting linked list 87 while (entry->pd_set() != NULL) { 88 ProtectionDomainEntry* to_delete = entry->pd_set(); 89 entry->set_pd_set(to_delete->next()); 90 delete to_delete; 91 } 92 Hashtable<InstanceKlass*, mtClass>::free_entry(entry); 93 } 94 95 96 bool DictionaryEntry::contains_protection_domain(oop protection_domain) const { 97 #ifdef ASSERT 98 if (protection_domain == klass()->protection_domain()) { 99 // Ensure this doesn't show up in the pd_set (invariant) 100 bool in_pd_set = false; 101 for (ProtectionDomainEntry* current = _pd_set; 102 current != NULL; 103 current = current->next()) { 104 if (current->protection_domain() == protection_domain) { 105 in_pd_set = true; 106 break; 107 } 108 } 109 if (in_pd_set) { 110 assert(false, "A klass's protection domain should not show up " 111 "in its sys. dict. PD set"); 112 } 113 } 114 #endif /* ASSERT */ 115 116 if (protection_domain == klass()->protection_domain()) { 117 // Succeeds trivially 118 return true; 119 } 120 121 for (ProtectionDomainEntry* current = _pd_set; 122 current != NULL; 123 current = current->next()) { 124 if (current->protection_domain() == protection_domain) return true; 125 } 126 return false; 127 } 128 129 130 void DictionaryEntry::add_protection_domain(Dictionary* dict, Handle protection_domain) { 131 assert_locked_or_safepoint(SystemDictionary_lock); 132 if (!contains_protection_domain(protection_domain())) { 133 ProtectionDomainCacheEntry* entry = dict->cache_get(protection_domain); 134 ProtectionDomainEntry* new_head = 135 new ProtectionDomainEntry(entry, _pd_set); 136 // Warning: Preserve store ordering. The SystemDictionary is read 137 // without locks. The new ProtectionDomainEntry must be 138 // complete before other threads can be allowed to see it 139 // via a store to _pd_set. 140 OrderAccess::release_store_ptr(&_pd_set, new_head); 141 } 142 LogTarget(Trace, protectiondomain) lt; 143 if (lt.is_enabled()) { 144 LogStream ls(lt); 145 print_count(&ls); 146 } 147 } 148 149 150 void Dictionary::do_unloading() { 151 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 152 153 // Remove unloadable entries and classes from system dictionary 154 DictionaryEntry* probe = NULL; 155 for (int index = 0; index < table_size(); index++) { 156 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) { 157 probe = *p; 158 Klass* e = probe->klass(); 159 ClassLoaderData* loader_data = probe->loader_data(); 160 161 InstanceKlass* ik = InstanceKlass::cast(e); 162 163 // Only unload classes that are not strongly reachable 164 if (!is_strongly_reachable(loader_data, e)) { 165 // Entry was not visited in phase1 (negated test from phase1) 166 assert(!loader_data->is_the_null_class_loader_data(), "unloading entry with null class loader"); 167 ClassLoaderData* k_def_class_loader_data = ik->class_loader_data(); 168 169 // Do we need to delete this system dictionary entry? 170 bool purge_entry = false; 171 172 // Do we need to delete this system dictionary entry? 173 if (loader_data->is_unloading()) { 174 // If the loader is not live this entry should always be 175 // removed (will never be looked up again). 176 purge_entry = true; 177 } else { 178 // The loader in this entry is alive. If the klass is dead, 179 // (determined by checking the defining class loader) 180 // the loader must be an initiating loader (rather than the 181 // defining loader). Remove this entry. 182 if (k_def_class_loader_data->is_unloading()) { 183 // If we get here, the class_loader_data must not be the defining 184 // loader, it must be an initiating one. 185 assert(k_def_class_loader_data != loader_data, 186 "cannot have live defining loader and unreachable klass"); 187 // Loader is live, but class and its defining loader are dead. 188 // Remove the entry. The class is going away. 189 purge_entry = true; 190 } 191 } 192 193 if (purge_entry) { 194 *p = probe->next(); 195 if (probe == _current_class_entry) { 196 _current_class_entry = NULL; 197 } 198 free_entry(probe); 199 continue; 200 } 201 } 202 p = probe->next_addr(); 203 } 204 } 205 } 206 207 void Dictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) { 208 // Do strong roots marking if the closures are the same. 209 if (strong == weak || !ClassUnloading) { 210 // Only the protection domain oops contain references into the heap. Iterate 211 // over all of them. 212 _pd_cache_table->oops_do(strong); 213 } else { 214 if (weak != NULL) { 215 _pd_cache_table->oops_do(weak); 216 } 217 } 218 } 219 220 221 void Dictionary::remove_classes_in_error_state() { 222 assert(DumpSharedSpaces, "supported only when dumping"); 223 DictionaryEntry* probe = NULL; 224 for (int index = 0; index < table_size(); index++) { 225 for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) { 226 probe = *p; 227 InstanceKlass* ik = InstanceKlass::cast(probe->klass()); 228 if (ik->is_in_error_state()) { // purge this entry 229 *p = probe->next(); 230 if (probe == _current_class_entry) { 231 _current_class_entry = NULL; 232 } 233 free_entry(probe); 234 ResourceMark rm; 235 tty->print_cr("Preload Warning: Removed error class: %s", ik->external_name()); 236 continue; 237 } 238 239 p = probe->next_addr(); 240 } 241 } 242 } 243 244 // Just the classes from defining class loaders 245 void Dictionary::classes_do(void f(Klass*)) { 246 for (int index = 0; index < table_size(); index++) { 247 for (DictionaryEntry* probe = bucket(index); 248 probe != NULL; 249 probe = probe->next()) { 250 Klass* k = probe->klass(); 251 if (probe->loader_data() == k->class_loader_data()) { 252 f(k); 253 } 254 } 255 } 256 } 257 258 // Added for initialize_itable_for_klass to handle exceptions 259 // Just the classes from defining class loaders 260 void Dictionary::classes_do(void f(Klass*, TRAPS), TRAPS) { 261 for (int index = 0; index < table_size(); index++) { 262 for (DictionaryEntry* probe = bucket(index); 263 probe != NULL; 264 probe = probe->next()) { 265 Klass* k = probe->klass(); 266 if (probe->loader_data() == k->class_loader_data()) { 267 f(k, CHECK); 268 } 269 } 270 } 271 } 272 273 // All classes, and their class loaders 274 // Don't iterate over placeholders 275 void Dictionary::classes_do(void f(Klass*, ClassLoaderData*)) { 276 for (int index = 0; index < table_size(); index++) { 277 for (DictionaryEntry* probe = bucket(index); 278 probe != NULL; 279 probe = probe->next()) { 280 Klass* k = probe->klass(); 281 f(k, probe->loader_data()); 282 } 283 } 284 } 285 286 // Used to scan and relocate the classes during CDS archive dump. 287 void Dictionary::classes_do(MetaspaceClosure* it) { 288 for (int index = 0; index < table_size(); index++) { 289 for (DictionaryEntry* probe = bucket(index); 290 probe != NULL; 291 probe = probe->next()) { 292 it->push(probe->klass_addr()); 293 if (DumpSharedSpaces) { 294 ((SharedDictionaryEntry*)probe)->metaspace_pointers_do(it); 295 } 296 } 297 } 298 } 299 300 301 void Dictionary::oops_do(OopClosure* f) { 302 // Only the protection domain oops contain references into the heap. Iterate 303 // over all of them. 304 _pd_cache_table->oops_do(f); 305 } 306 307 void Dictionary::unlink(BoolObjectClosure* is_alive) { 308 // Only the protection domain cache table may contain references to the heap 309 // that need to be unlinked. 310 _pd_cache_table->unlink(is_alive); 311 } 312 313 InstanceKlass* Dictionary::try_get_next_class() { 314 while (true) { 315 if (_current_class_entry != NULL) { 316 InstanceKlass* k = _current_class_entry->klass(); 317 _current_class_entry = _current_class_entry->next(); 318 return k; 319 } 320 _current_class_index = (_current_class_index + 1) % table_size(); 321 _current_class_entry = bucket(_current_class_index); 322 } 323 // never reached 324 } 325 326 // Add a loaded class to the system dictionary. 327 // Readers of the SystemDictionary aren't always locked, so _buckets 328 // is volatile. The store of the next field in the constructor is 329 // also cast to volatile; we do this to ensure store order is maintained 330 // by the compilers. 331 332 void Dictionary::add_klass(Symbol* class_name, ClassLoaderData* loader_data, 333 InstanceKlass* obj) { 334 assert_locked_or_safepoint(SystemDictionary_lock); 335 assert(obj != NULL, "adding NULL obj"); 336 assert(obj->name() == class_name, "sanity check on name"); 337 assert(loader_data != NULL, "Must be non-NULL"); 338 339 unsigned int hash = compute_hash(class_name, loader_data); 340 int index = hash_to_index(hash); 341 DictionaryEntry* entry = new_entry(hash, obj, loader_data); 342 add_entry(index, entry); 343 } 344 345 346 // This routine does not lock the system dictionary. 347 // 348 // Since readers don't hold a lock, we must make sure that system 349 // dictionary entries are only removed at a safepoint (when only one 350 // thread is running), and are added to in a safe way (all links must 351 // be updated in an MT-safe manner). 352 // 353 // Callers should be aware that an entry could be added just after 354 // _buckets[index] is read here, so the caller will not see the new entry. 355 DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash, 356 Symbol* class_name, 357 ClassLoaderData* loader_data) { 358 for (DictionaryEntry* entry = bucket(index); 359 entry != NULL; 360 entry = entry->next()) { 361 if (entry->hash() == hash && entry->equals(class_name, loader_data)) { 362 return entry; 363 } 364 } 365 return NULL; 366 } 367 368 369 InstanceKlass* Dictionary::find(int index, unsigned int hash, Symbol* name, 370 ClassLoaderData* loader_data, Handle protection_domain, TRAPS) { 371 DictionaryEntry* entry = get_entry(index, hash, name, loader_data); 372 if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) { 373 return entry->klass(); 374 } else { 375 return NULL; 376 } 377 } 378 379 380 InstanceKlass* Dictionary::find_class(int index, unsigned int hash, 381 Symbol* name, ClassLoaderData* loader_data) { 382 assert_locked_or_safepoint(SystemDictionary_lock); 383 assert (index == index_for(name, loader_data), "incorrect index?"); 384 385 DictionaryEntry* entry = get_entry(index, hash, name, loader_data); 386 return (entry != NULL) ? entry->klass() : NULL; 387 } 388 389 390 // Variant of find_class for shared classes. No locking required, as 391 // that table is static. 392 393 InstanceKlass* Dictionary::find_shared_class(int index, unsigned int hash, 394 Symbol* name) { 395 assert (index == index_for(name, NULL), "incorrect index?"); 396 397 DictionaryEntry* entry = get_entry(index, hash, name, NULL); 398 return (entry != NULL) ? entry->klass() : NULL; 399 } 400 401 402 void Dictionary::add_protection_domain(int index, unsigned int hash, 403 InstanceKlass* klass, 404 ClassLoaderData* loader_data, Handle protection_domain, 405 TRAPS) { 406 Symbol* klass_name = klass->name(); 407 DictionaryEntry* entry = get_entry(index, hash, klass_name, loader_data); 408 409 assert(entry != NULL,"entry must be present, we just created it"); 410 assert(protection_domain() != NULL, 411 "real protection domain should be present"); 412 413 entry->add_protection_domain(this, protection_domain); 414 415 assert(entry->contains_protection_domain(protection_domain()), 416 "now protection domain should be present"); 417 } 418 419 420 bool Dictionary::is_valid_protection_domain(int index, unsigned int hash, 421 Symbol* name, 422 ClassLoaderData* loader_data, 423 Handle protection_domain) { 424 DictionaryEntry* entry = get_entry(index, hash, name, loader_data); 425 return entry->is_valid_protection_domain(protection_domain); 426 } 427 428 429 void Dictionary::reorder_dictionary_for_sharing() { 430 431 // Copy all the dictionary entries into a single master list. 432 433 DictionaryEntry* master_list = NULL; 434 for (int i = 0; i < table_size(); ++i) { 435 DictionaryEntry* p = bucket(i); 436 while (p != NULL) { 437 DictionaryEntry* tmp; 438 tmp = p->next(); 439 p->set_next(master_list); 440 master_list = p; 441 p = tmp; 442 } 443 set_entry(i, NULL); 444 } 445 446 // Add the dictionary entries back to the list in the correct buckets. 447 while (master_list != NULL) { 448 DictionaryEntry* p = master_list; 449 master_list = master_list->next(); 450 p->set_next(NULL); 451 Symbol* class_name = p->klass()->name(); 452 // Since the null class loader data isn't copied to the CDS archive, 453 // compute the hash with NULL for loader data. 454 unsigned int hash = compute_hash(class_name, NULL); 455 int index = hash_to_index(hash); 456 p->set_hash(hash); 457 p->set_loader_data(NULL); // loader_data isn't copied to CDS 458 p->set_next(bucket(index)); 459 set_entry(index, p); 460 } 461 } 462 463 464 SymbolPropertyTable::SymbolPropertyTable(int table_size) 465 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry)) 466 { 467 } 468 SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t, 469 int number_of_entries) 470 : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries) 471 { 472 } 473 474 475 SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash, 476 Symbol* sym, 477 intptr_t sym_mode) { 478 assert(index == index_for(sym, sym_mode), "incorrect index?"); 479 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) { 480 if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) { 481 return p; 482 } 483 } 484 return NULL; 485 } 486 487 488 SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash, 489 Symbol* sym, intptr_t sym_mode) { 490 assert_locked_or_safepoint(SystemDictionary_lock); 491 assert(index == index_for(sym, sym_mode), "incorrect index?"); 492 assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry"); 493 494 SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode); 495 Hashtable<Symbol*, mtSymbol>::add_entry(index, p); 496 return p; 497 } 498 499 void SymbolPropertyTable::oops_do(OopClosure* f) { 500 for (int index = 0; index < table_size(); index++) { 501 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) { 502 if (p->method_type() != NULL) { 503 f->do_oop(p->method_type_addr()); 504 } 505 } 506 } 507 } 508 509 void SymbolPropertyTable::methods_do(void f(Method*)) { 510 for (int index = 0; index < table_size(); index++) { 511 for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) { 512 Method* prop = p->method(); 513 if (prop != NULL) { 514 f((Method*)prop); 515 } 516 } 517 } 518 } 519 520 521 // ---------------------------------------------------------------------------- 522 523 void Dictionary::print(bool details) { 524 ResourceMark rm; 525 526 if (details) { 527 tty->print_cr("Java system dictionary (table_size=%d, classes=%d)", 528 table_size(), number_of_entries()); 529 tty->print_cr("^ indicates that initiating loader is different from " 530 "defining loader"); 531 } 532 533 for (int index = 0; index < table_size(); index++) { 534 for (DictionaryEntry* probe = bucket(index); 535 probe != NULL; 536 probe = probe->next()) { 537 Klass* e = probe->klass(); 538 ClassLoaderData* loader_data = probe->loader_data(); 539 bool is_defining_class = 540 (loader_data == e->class_loader_data()); 541 if (details) { 542 tty->print("%4d: ", index); 543 } 544 tty->print("%s%s", ((!details) || is_defining_class) ? " " : "^", 545 e->external_name()); 546 547 if (details) { 548 tty->print(", loader "); 549 if (loader_data != NULL) { 550 loader_data->print_value(); 551 } else { 552 tty->print("NULL"); 553 } 554 } 555 tty->cr(); 556 } 557 } 558 559 if (details) { 560 tty->cr(); 561 _pd_cache_table->print(); 562 } 563 tty->cr(); 564 } 565 566 void DictionaryEntry::verify() { 567 Klass* e = klass(); 568 ClassLoaderData* cld = loader_data(); 569 guarantee(e->is_instance_klass(), 570 "Verify of system dictionary failed"); 571 // class loader must be present; a null class loader is the 572 // boostrap loader 573 guarantee(cld != NULL || DumpSharedSpaces || 574 cld->class_loader() == NULL || 575 cld->class_loader()->is_instance(), 576 "checking type of class_loader"); 577 e->verify(); 578 verify_protection_domain_set(); 579 } 580 581 void Dictionary::verify() { 582 guarantee(number_of_entries() >= 0, "Verify of system dictionary failed"); 583 verify_table<DictionaryEntry>("System Dictionary"); 584 _pd_cache_table->verify(); 585 } 586