dictionary.cpp revision 1472:c18cbe5936b8
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 29DictionaryEntry* Dictionary::_current_class_entry = NULL; 30int Dictionary::_current_class_index = 0; 31 32 33Dictionary::Dictionary(int table_size) 34 : TwoOopHashtable(table_size, sizeof(DictionaryEntry)) { 35 _current_class_index = 0; 36 _current_class_entry = NULL; 37}; 38 39 40 41Dictionary::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 49DictionaryEntry* 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 59DictionaryEntry* 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 67void 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 78bool 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 112void 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 129bool 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 290void 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 311void 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 326void 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 343void 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 357void 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 369void 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 384void 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 399klassOop 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 419void 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. 441DictionaryEntry* 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 459klassOop 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 470klassOop 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 483klassOop 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 492void 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 510bool 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 519void 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 552SymbolPropertyTable::SymbolPropertyTable(int table_size) 553 : Hashtable(table_size, sizeof(SymbolPropertyEntry)) 554{ 555} 556SymbolPropertyTable::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 563SymbolPropertyEntry* 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 576SymbolPropertyEntry* 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 588void 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 599void 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 614void 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 644void 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} 668