1 /* 2 * Copyright (c) 2012, 2018, 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 // A ClassLoaderData identifies the full set of class types that a class 26 // loader's name resolution strategy produces for a given configuration of the 27 // class loader. 28 // Class types in the ClassLoaderData may be defined by from class file binaries 29 // provided by the class loader, or from other class loader it interacts with 30 // according to its name resolution strategy. 31 // 32 // Class loaders that implement a deterministic name resolution strategy 33 // (including with respect to their delegation behavior), such as the boot, the 34 // platform, and the system loaders of the JDK's built-in class loader 35 // hierarchy, always produce the same linkset for a given configuration. 36 // 37 // ClassLoaderData carries information related to a linkset (e.g., 38 // metaspace holding its klass definitions). 39 // The System Dictionary and related data structures (e.g., placeholder table, 40 // loader constraints table) as well as the runtime representation of classes 41 // only reference ClassLoaderData. 42 // 43 // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that 44 // that represent the loader's "linking domain" in the JVM. 45 // 46 // The bootstrap loader (represented by NULL) also has a ClassLoaderData, 47 // the singleton class the_null_class_loader_data(). 48 49 #include "precompiled.hpp" 50 #include "classfile/classLoaderData.inline.hpp" 51 #include "classfile/classLoaderDataGraph.inline.hpp" 52 #include "classfile/dictionary.hpp" 53 #include "classfile/javaClasses.hpp" 54 #include "classfile/moduleEntry.hpp" 55 #include "classfile/packageEntry.hpp" 56 #include "classfile/symbolTable.hpp" 57 #include "classfile/systemDictionary.hpp" 58 #include "logging/log.hpp" 59 #include "logging/logStream.hpp" 60 #include "memory/allocation.inline.hpp" 61 #include "memory/metadataFactory.hpp" 62 #include "memory/resourceArea.hpp" 63 #include "oops/access.inline.hpp" 64 #include "oops/oop.inline.hpp" 65 #include "oops/oopHandle.inline.hpp" 66 #include "oops/weakHandle.inline.hpp" 67 #include "runtime/atomic.hpp" 68 #include "runtime/handles.inline.hpp" 69 #include "runtime/mutex.hpp" 70 #include "runtime/orderAccess.hpp" 71 #include "runtime/safepoint.hpp" 72 #include "utilities/growableArray.hpp" 73 #include "utilities/macros.hpp" 74 #include "utilities/ostream.hpp" 75 76 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 77 78 void ClassLoaderData::init_null_class_loader_data() { 79 assert(_the_null_class_loader_data == NULL, "cannot initialize twice"); 80 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice"); 81 82 _the_null_class_loader_data = new ClassLoaderData(Handle(), false); 83 ClassLoaderDataGraph::_head = _the_null_class_loader_data; 84 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be"); 85 86 LogTarget(Trace, class, loader, data) lt; 87 if (lt.is_enabled()) { 88 ResourceMark rm; 89 LogStream ls(lt); 90 ls.print("create "); 91 _the_null_class_loader_data->print_value_on(&ls); 92 ls.cr(); 93 } 94 } 95 96 // Obtain and set the class loader's name within the ClassLoaderData so 97 // it will be available for error messages, logging, JFR, etc. The name 98 // and klass are available after the class_loader oop is no longer alive, 99 // during unloading. 100 void ClassLoaderData::initialize_name(Handle class_loader) { 101 Thread* THREAD = Thread::current(); 102 ResourceMark rm(THREAD); 103 104 // Obtain the class loader's name. If the class loader's name was not 105 // explicitly set during construction, the CLD's _name field will be null. 106 oop cl_name = java_lang_ClassLoader::name(class_loader()); 107 if (cl_name != NULL) { 108 const char* cl_instance_name = java_lang_String::as_utf8_string(cl_name); 109 110 if (cl_instance_name != NULL && cl_instance_name[0] != '\0') { 111 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore. 112 _name = SymbolTable::new_symbol(cl_instance_name, CATCH); 113 } 114 } 115 116 // Obtain the class loader's name and identity hash. If the class loader's 117 // name was not explicitly set during construction, the class loader's name and id 118 // will be set to the qualified class name of the class loader along with its 119 // identity hash. 120 // If for some reason the ClassLoader's constructor has not been run, instead of 121 // leaving the _name_and_id field null, fall back to the external qualified class 122 // name. Thus CLD's _name_and_id field should never have a null value. 123 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader()); 124 const char* cl_instance_name_and_id = 125 (cl_name_and_id == NULL) ? _class_loader_klass->external_name() : 126 java_lang_String::as_utf8_string(cl_name_and_id); 127 assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id"); 128 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore. 129 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id, CATCH); 130 } 131 132 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_unsafe_anonymous) : 133 _metaspace(NULL), 134 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true, 135 Monitor::_safepoint_check_never)), 136 _unloading(false), _is_unsafe_anonymous(is_unsafe_anonymous), 137 _modified_oops(true), _accumulated_modified_oops(false), 138 // An unsafe anonymous class loader data doesn't have anything to keep 139 // it from being unloaded during parsing of the unsafe anonymous class. 140 // The null-class-loader should always be kept alive. 141 _keep_alive((is_unsafe_anonymous || h_class_loader.is_null()) ? 1 : 0), 142 _claimed(0), 143 _handles(), 144 _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL), 145 _jmethod_ids(NULL), 146 _deallocate_list(NULL), 147 _next(NULL), 148 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL) { 149 150 if (!h_class_loader.is_null()) { 151 _class_loader = _handles.add(h_class_loader()); 152 _class_loader_klass = h_class_loader->klass(); 153 initialize_name(h_class_loader); 154 } 155 156 if (!is_unsafe_anonymous) { 157 // The holder is initialized later for unsafe anonymous classes, and before calling anything 158 // that call class_loader(). 159 initialize_holder(h_class_loader); 160 161 // A ClassLoaderData created solely for an unsafe anonymous class should never have a 162 // ModuleEntryTable or PackageEntryTable created for it. The defining package 163 // and module for an unsafe anonymous class will be found in its host class. 164 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); 165 if (h_class_loader.is_null()) { 166 // Create unnamed module for boot loader 167 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this); 168 } else { 169 // Create unnamed module for all other loaders 170 _unnamed_module = ModuleEntry::create_unnamed_module(this); 171 } 172 _dictionary = create_dictionary(); 173 } 174 175 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies 176 177 JFR_ONLY(INIT_ID(this);) 178 } 179 180 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() { 181 Chunk* c = _head; 182 while (c != NULL) { 183 Chunk* next = c->_next; 184 delete c; 185 c = next; 186 } 187 } 188 189 oop* ClassLoaderData::ChunkedHandleList::add(oop o) { 190 if (_head == NULL || _head->_size == Chunk::CAPACITY) { 191 Chunk* next = new Chunk(_head); 192 OrderAccess::release_store(&_head, next); 193 } 194 oop* handle = &_head->_data[_head->_size]; 195 *handle = o; 196 OrderAccess::release_store(&_head->_size, _head->_size + 1); 197 return handle; 198 } 199 200 int ClassLoaderData::ChunkedHandleList::count() const { 201 int count = 0; 202 Chunk* chunk = _head; 203 while (chunk != NULL) { 204 count += chunk->_size; 205 chunk = chunk->_next; 206 } 207 return count; 208 } 209 210 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) { 211 for (juint i = 0; i < size; i++) { 212 if (c->_data[i] != NULL) { 213 f->do_oop(&c->_data[i]); 214 } 215 } 216 } 217 218 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) { 219 Chunk* head = OrderAccess::load_acquire(&_head); 220 if (head != NULL) { 221 // Must be careful when reading size of head 222 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size)); 223 for (Chunk* c = head->_next; c != NULL; c = c->_next) { 224 oops_do_chunk(f, c, c->_size); 225 } 226 } 227 } 228 229 class VerifyContainsOopClosure : public OopClosure { 230 oop _target; 231 bool _found; 232 233 public: 234 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {} 235 236 void do_oop(oop* p) { 237 if (p != NULL && oopDesc::equals(RawAccess<>::oop_load(p), _target)) { 238 _found = true; 239 } 240 } 241 242 void do_oop(narrowOop* p) { 243 // The ChunkedHandleList should not contain any narrowOop 244 ShouldNotReachHere(); 245 } 246 247 bool found() const { 248 return _found; 249 } 250 }; 251 252 bool ClassLoaderData::ChunkedHandleList::contains(oop p) { 253 VerifyContainsOopClosure cl(p); 254 oops_do(&cl); 255 return cl.found(); 256 } 257 258 #ifndef PRODUCT 259 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) { 260 Chunk* chunk = _head; 261 while (chunk != NULL) { 262 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) { 263 return true; 264 } 265 chunk = chunk->_next; 266 } 267 return false; 268 } 269 #endif // PRODUCT 270 271 bool ClassLoaderData::claim() { 272 if (_claimed == 1) { 273 return false; 274 } 275 276 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; 277 } 278 279 // Unsafe anonymous classes have their own ClassLoaderData that is marked to keep alive 280 // while the class is being parsed, and if the class appears on the module fixup list. 281 // Due to the uniqueness that no other class shares the unsafe anonymous class' name or 282 // ClassLoaderData, no other non-GC thread has knowledge of the unsafe anonymous class while 283 // it is being defined, therefore _keep_alive is not volatile or atomic. 284 void ClassLoaderData::inc_keep_alive() { 285 if (is_unsafe_anonymous()) { 286 assert(_keep_alive >= 0, "Invalid keep alive increment count"); 287 _keep_alive++; 288 } 289 } 290 291 void ClassLoaderData::dec_keep_alive() { 292 if (is_unsafe_anonymous()) { 293 assert(_keep_alive > 0, "Invalid keep alive decrement count"); 294 _keep_alive--; 295 } 296 } 297 298 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) { 299 if (must_claim && !claim()) { 300 return; 301 } 302 303 // Only clear modified_oops after the ClassLoaderData is claimed. 304 if (clear_mod_oops) { 305 clear_modified_oops(); 306 } 307 308 _handles.oops_do(f); 309 } 310 311 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 312 // Lock-free access requires load_acquire 313 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 314 klass_closure->do_klass(k); 315 assert(k != k->next_link(), "no loops!"); 316 } 317 } 318 319 void ClassLoaderData::classes_do(void f(Klass * const)) { 320 // Lock-free access requires load_acquire 321 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 322 f(k); 323 assert(k != k->next_link(), "no loops!"); 324 } 325 } 326 327 void ClassLoaderData::methods_do(void f(Method*)) { 328 // Lock-free access requires load_acquire 329 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 330 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) { 331 InstanceKlass::cast(k)->methods_do(f); 332 } 333 } 334 } 335 336 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 337 // Lock-free access requires load_acquire 338 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 339 // Do not filter ArrayKlass oops here... 340 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { 341 #ifdef ASSERT 342 oop m = k->java_mirror(); 343 assert(m != NULL, "NULL mirror"); 344 assert(m->is_a(SystemDictionary::Class_klass()), "invalid mirror"); 345 #endif 346 klass_closure->do_klass(k); 347 } 348 } 349 } 350 351 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 352 // Lock-free access requires load_acquire 353 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 354 if (k->is_instance_klass()) { 355 f(InstanceKlass::cast(k)); 356 } 357 assert(k != k->next_link(), "no loops!"); 358 } 359 } 360 361 void ClassLoaderData::modules_do(void f(ModuleEntry*)) { 362 assert_locked_or_safepoint(Module_lock); 363 if (_unnamed_module != NULL) { 364 f(_unnamed_module); 365 } 366 if (_modules != NULL) { 367 for (int i = 0; i < _modules->table_size(); i++) { 368 for (ModuleEntry* entry = _modules->bucket(i); 369 entry != NULL; 370 entry = entry->next()) { 371 f(entry); 372 } 373 } 374 } 375 } 376 377 void ClassLoaderData::packages_do(void f(PackageEntry*)) { 378 assert_locked_or_safepoint(Module_lock); 379 if (_packages != NULL) { 380 for (int i = 0; i < _packages->table_size(); i++) { 381 for (PackageEntry* entry = _packages->bucket(i); 382 entry != NULL; 383 entry = entry->next()) { 384 f(entry); 385 } 386 } 387 } 388 } 389 390 void ClassLoaderData::record_dependency(const Klass* k) { 391 assert(k != NULL, "invariant"); 392 393 ClassLoaderData * const from_cld = this; 394 ClassLoaderData * const to_cld = k->class_loader_data(); 395 396 // Do not need to record dependency if the dependency is to a class whose 397 // class loader data is never freed. (i.e. the dependency's class loader 398 // is one of the three builtin class loaders and the dependency is not 399 // unsafe anonymous.) 400 if (to_cld->is_permanent_class_loader_data()) { 401 return; 402 } 403 404 oop to; 405 if (to_cld->is_unsafe_anonymous()) { 406 // Just return if an unsafe anonymous class is attempting to record a dependency 407 // to itself. (Note that every unsafe anonymous class has its own unique class 408 // loader data.) 409 if (to_cld == from_cld) { 410 return; 411 } 412 // Unsafe anonymous class dependencies are through the mirror. 413 to = k->java_mirror(); 414 } else { 415 to = to_cld->class_loader(); 416 oop from = from_cld->class_loader(); 417 418 // Just return if this dependency is to a class with the same or a parent 419 // class_loader. 420 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) { 421 return; // this class loader is in the parent list, no need to add it. 422 } 423 } 424 425 // It's a dependency we won't find through GC, add it. 426 if (!_handles.contains(to)) { 427 NOT_PRODUCT(Atomic::inc(&_dependency_count)); 428 LogTarget(Trace, class, loader, data) lt; 429 if (lt.is_enabled()) { 430 ResourceMark rm; 431 LogStream ls(lt); 432 ls.print("adding dependency from "); 433 print_value_on(&ls); 434 ls.print(" to "); 435 to_cld->print_value_on(&ls); 436 ls.cr(); 437 } 438 Handle dependency(Thread::current(), to); 439 add_handle(dependency); 440 // Added a potentially young gen oop to the ClassLoaderData 441 record_modified_oops(); 442 } 443 } 444 445 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 446 { 447 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 448 Klass* old_value = _klasses; 449 k->set_next_link(old_value); 450 // Link the new item into the list, making sure the linked class is stable 451 // since the list can be walked without a lock 452 OrderAccess::release_store(&_klasses, k); 453 if (k->is_array_klass()) { 454 ClassLoaderDataGraph::inc_array_classes(1); 455 } else { 456 ClassLoaderDataGraph::inc_instance_classes(1); 457 } 458 } 459 460 if (publicize) { 461 LogTarget(Trace, class, loader, data) lt; 462 if (lt.is_enabled()) { 463 ResourceMark rm; 464 LogStream ls(lt); 465 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name()); 466 print_value_on(&ls); 467 ls.cr(); 468 } 469 } 470 } 471 472 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) { 473 if (loader_or_mirror() != NULL) { 474 assert(_holder.is_null(), "never replace holders"); 475 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror); 476 } 477 } 478 479 // Remove a klass from the _klasses list for scratch_class during redefinition 480 // or parsed class in the case of an error. 481 void ClassLoaderData::remove_class(Klass* scratch_class) { 482 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 483 484 // Adjust global class iterator. 485 ClassLoaderDataGraph::adjust_saved_class(scratch_class); 486 487 Klass* prev = NULL; 488 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 489 if (k == scratch_class) { 490 if (prev == NULL) { 491 _klasses = k->next_link(); 492 } else { 493 Klass* next = k->next_link(); 494 prev->set_next_link(next); 495 } 496 497 if (k->is_array_klass()) { 498 ClassLoaderDataGraph::dec_array_classes(1); 499 } else { 500 ClassLoaderDataGraph::dec_instance_classes(1); 501 } 502 503 return; 504 } 505 prev = k; 506 assert(k != k->next_link(), "no loops!"); 507 } 508 ShouldNotReachHere(); // should have found this class!! 509 } 510 511 void ClassLoaderData::unload() { 512 _unloading = true; 513 514 LogTarget(Trace, class, loader, data) lt; 515 if (lt.is_enabled()) { 516 ResourceMark rm; 517 LogStream ls(lt); 518 ls.print("unload"); 519 print_value_on(&ls); 520 ls.cr(); 521 } 522 523 // Some items on the _deallocate_list need to free their C heap structures 524 // if they are not already on the _klasses list. 525 free_deallocate_list_C_heap_structures(); 526 527 // Clean up class dependencies and tell serviceability tools 528 // these classes are unloading. Must be called 529 // after erroneous classes are released. 530 classes_do(InstanceKlass::unload_class); 531 532 // Clean up global class iterator for compiler 533 ClassLoaderDataGraph::adjust_saved_class(this); 534 } 535 536 ModuleEntryTable* ClassLoaderData::modules() { 537 // Lazily create the module entry table at first request. 538 // Lock-free access requires load_acquire. 539 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules); 540 if (modules == NULL) { 541 MutexLocker m1(Module_lock); 542 // Check if _modules got allocated while we were waiting for this lock. 543 if ((modules = _modules) == NULL) { 544 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); 545 546 { 547 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 548 // Ensure _modules is stable, since it is examined without a lock 549 OrderAccess::release_store(&_modules, modules); 550 } 551 } 552 } 553 return modules; 554 } 555 556 const int _boot_loader_dictionary_size = 1009; 557 const int _default_loader_dictionary_size = 107; 558 559 Dictionary* ClassLoaderData::create_dictionary() { 560 assert(!is_unsafe_anonymous(), "unsafe anonymous class loader data do not have a dictionary"); 561 int size; 562 bool resizable = false; 563 if (_the_null_class_loader_data == NULL) { 564 size = _boot_loader_dictionary_size; 565 resizable = true; 566 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 567 size = 1; // there's only one class in relection class loader and no initiated classes 568 } else if (is_system_class_loader_data()) { 569 size = _boot_loader_dictionary_size; 570 resizable = true; 571 } else { 572 size = _default_loader_dictionary_size; 573 resizable = true; 574 } 575 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) { 576 resizable = false; 577 } 578 return new Dictionary(this, size, resizable); 579 } 580 581 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph 582 oop ClassLoaderData::holder_phantom() const { 583 // A klass that was previously considered dead can be looked up in the 584 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root 585 // or a reachable object making it alive again. The SATB part of G1 needs 586 // to get notified about this potential resurrection, otherwise the marking 587 // might not find the object. 588 if (!_holder.is_null()) { // NULL class_loader 589 return _holder.resolve(); 590 } else { 591 return NULL; 592 } 593 } 594 595 // Let the GC read the holder without keeping it alive. 596 oop ClassLoaderData::holder_no_keepalive() const { 597 if (!_holder.is_null()) { // NULL class_loader 598 return _holder.peek(); 599 } else { 600 return NULL; 601 } 602 } 603 604 // Unloading support 605 bool ClassLoaderData::is_alive() const { 606 bool alive = keep_alive() // null class loader and incomplete unsafe anonymous klasses. 607 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing. 608 609 return alive; 610 } 611 612 class ReleaseKlassClosure: public KlassClosure { 613 private: 614 size_t _instance_class_released; 615 size_t _array_class_released; 616 public: 617 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { } 618 619 size_t instance_class_released() const { return _instance_class_released; } 620 size_t array_class_released() const { return _array_class_released; } 621 622 void do_klass(Klass* k) { 623 if (k->is_array_klass()) { 624 _array_class_released ++; 625 } else { 626 assert(k->is_instance_klass(), "Must be"); 627 _instance_class_released ++; 628 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k)); 629 } 630 } 631 }; 632 633 ClassLoaderData::~ClassLoaderData() { 634 // Release C heap structures for all the classes. 635 ReleaseKlassClosure cl; 636 classes_do(&cl); 637 638 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released()); 639 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released()); 640 641 // Release the WeakHandle 642 _holder.release(); 643 644 // Release C heap allocated hashtable for all the packages. 645 if (_packages != NULL) { 646 // Destroy the table itself 647 delete _packages; 648 _packages = NULL; 649 } 650 651 // Release C heap allocated hashtable for all the modules. 652 if (_modules != NULL) { 653 // Destroy the table itself 654 delete _modules; 655 _modules = NULL; 656 } 657 658 // Release C heap allocated hashtable for the dictionary 659 if (_dictionary != NULL) { 660 // Destroy the table itself 661 delete _dictionary; 662 _dictionary = NULL; 663 } 664 665 if (_unnamed_module != NULL) { 666 _unnamed_module->delete_unnamed_module(); 667 _unnamed_module = NULL; 668 } 669 670 // release the metaspace 671 ClassLoaderMetaspace *m = _metaspace; 672 if (m != NULL) { 673 _metaspace = NULL; 674 delete m; 675 } 676 // Clear all the JNI handles for methods 677 // These aren't deallocated and are going to look like a leak, but that's 678 // needed because we can't really get rid of jmethodIDs because we don't 679 // know when native code is going to stop using them. The spec says that 680 // they're "invalid" but existing programs likely rely on their being 681 // NULL after class unloading. 682 if (_jmethod_ids != NULL) { 683 Method::clear_jmethod_ids(this); 684 } 685 // Delete lock 686 delete _metaspace_lock; 687 688 // Delete free list 689 if (_deallocate_list != NULL) { 690 delete _deallocate_list; 691 } 692 693 // Decrement refcounts of Symbols if created. 694 if (_name != NULL) { 695 _name->decrement_refcount(); 696 } 697 if (_name_and_id != NULL) { 698 _name_and_id->decrement_refcount(); 699 } 700 } 701 702 // Returns true if this class loader data is for the app class loader 703 // or a user defined system class loader. (Note that the class loader 704 // data may be unsafe anonymous.) 705 bool ClassLoaderData::is_system_class_loader_data() const { 706 return SystemDictionary::is_system_class_loader(class_loader()); 707 } 708 709 // Returns true if this class loader data is for the platform class loader. 710 // (Note that the class loader data may be unsafe anonymous.) 711 bool ClassLoaderData::is_platform_class_loader_data() const { 712 return SystemDictionary::is_platform_class_loader(class_loader()); 713 } 714 715 // Returns true if the class loader for this class loader data is one of 716 // the 3 builtin (boot application/system or platform) class loaders, 717 // including a user-defined system class loader. Note that if the class 718 // loader data is for an unsafe anonymous class then it may get freed by a GC 719 // even if its class loader is one of these loaders. 720 bool ClassLoaderData::is_builtin_class_loader_data() const { 721 return (is_boot_class_loader_data() || 722 SystemDictionary::is_system_class_loader(class_loader()) || 723 SystemDictionary::is_platform_class_loader(class_loader())); 724 } 725 726 // Returns true if this class loader data is a class loader data 727 // that is not ever freed by a GC. It must be the CLD for one of the builtin 728 // class loaders and not the CLD for an unsafe anonymous class. 729 bool ClassLoaderData::is_permanent_class_loader_data() const { 730 return is_builtin_class_loader_data() && !is_unsafe_anonymous(); 731 } 732 733 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() { 734 // If the metaspace has not been allocated, create a new one. Might want 735 // to create smaller arena for Reflection class loaders also. 736 // The reason for the delayed allocation is because some class loaders are 737 // simply for delegating with no metadata of their own. 738 // Lock-free access requires load_acquire. 739 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace); 740 if (metaspace == NULL) { 741 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); 742 // Check if _metaspace got allocated while we were waiting for this lock. 743 if ((metaspace = _metaspace) == NULL) { 744 if (this == the_null_class_loader_data()) { 745 assert (class_loader() == NULL, "Must be"); 746 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType); 747 } else if (is_unsafe_anonymous()) { 748 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::UnsafeAnonymousMetaspaceType); 749 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 750 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); 751 } else { 752 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); 753 } 754 // Ensure _metaspace is stable, since it is examined without a lock 755 OrderAccess::release_store(&_metaspace, metaspace); 756 } 757 } 758 return metaspace; 759 } 760 761 OopHandle ClassLoaderData::add_handle(Handle h) { 762 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 763 record_modified_oops(); 764 return OopHandle(_handles.add(h())); 765 } 766 767 void ClassLoaderData::remove_handle(OopHandle h) { 768 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading"); 769 oop* ptr = h.ptr_raw(); 770 if (ptr != NULL) { 771 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr)); 772 NativeAccess<>::oop_store(ptr, oop(NULL)); 773 } 774 } 775 776 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) { 777 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 778 if (dest.resolve() != NULL) { 779 return; 780 } else { 781 dest = _handles.add(h()); 782 } 783 } 784 785 // Add this metadata pointer to be freed when it's safe. This is only during 786 // a safepoint which checks if handles point to this metadata field. 787 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 788 // Metadata in shared region isn't deleted. 789 if (!m->is_shared()) { 790 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 791 if (_deallocate_list == NULL) { 792 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 793 } 794 _deallocate_list->append_if_missing(m); 795 log_debug(class, loader, data)("deallocate added for %s", m->print_value_string()); 796 ClassLoaderDataGraph::set_should_clean_deallocate_lists(); 797 } 798 } 799 800 // Deallocate free metadata on the free list. How useful the PermGen was! 801 void ClassLoaderData::free_deallocate_list() { 802 // Don't need lock, at safepoint 803 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 804 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading"); 805 if (_deallocate_list == NULL) { 806 return; 807 } 808 // Go backwards because this removes entries that are freed. 809 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 810 Metadata* m = _deallocate_list->at(i); 811 if (!m->on_stack()) { 812 _deallocate_list->remove_at(i); 813 // There are only three types of metadata that we deallocate directly. 814 // Cast them so they can be used by the template function. 815 if (m->is_method()) { 816 MetadataFactory::free_metadata(this, (Method*)m); 817 } else if (m->is_constantPool()) { 818 MetadataFactory::free_metadata(this, (ConstantPool*)m); 819 } else if (m->is_klass()) { 820 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 821 } else { 822 ShouldNotReachHere(); 823 } 824 } else { 825 // Metadata is alive. 826 // If scratch_class is on stack then it shouldn't be on this list! 827 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 828 "scratch classes on this list should be dead"); 829 // Also should assert that other metadata on the list was found in handles. 830 // Some cleaning remains. 831 ClassLoaderDataGraph::set_should_clean_deallocate_lists(); 832 } 833 } 834 } 835 836 // This is distinct from free_deallocate_list. For class loader data that are 837 // unloading, this frees the C heap memory for items on the list, and unlinks 838 // scratch or error classes so that unloading events aren't triggered for these 839 // classes. The metadata is removed with the unloading metaspace. 840 // There isn't C heap memory allocated for methods, so nothing is done for them. 841 void ClassLoaderData::free_deallocate_list_C_heap_structures() { 842 // Don't need lock, at safepoint 843 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 844 assert(is_unloading(), "only called for ClassLoaderData that are unloading"); 845 if (_deallocate_list == NULL) { 846 return; 847 } 848 // Go backwards because this removes entries that are freed. 849 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 850 Metadata* m = _deallocate_list->at(i); 851 _deallocate_list->remove_at(i); 852 if (m->is_constantPool()) { 853 ((ConstantPool*)m)->release_C_heap_structures(); 854 } else if (m->is_klass()) { 855 InstanceKlass* ik = (InstanceKlass*)m; 856 // also releases ik->constants() C heap memory 857 InstanceKlass::release_C_heap_structures(ik); 858 // Remove the class so unloading events aren't triggered for 859 // this class (scratch or error class) in do_unloading(). 860 remove_class(ik); 861 } 862 } 863 } 864 865 // These CLDs are to contain unsafe anonymous classes used for JSR292 866 ClassLoaderData* ClassLoaderData::unsafe_anonymous_class_loader_data(Handle loader) { 867 // Add a new class loader data to the graph. 868 return ClassLoaderDataGraph::add(loader, true); 869 } 870 871 // Caller needs ResourceMark 872 // If the class loader's _name has not been explicitly set, the class loader's 873 // qualified class name is returned. 874 const char* ClassLoaderData::loader_name() const { 875 if (_class_loader_klass == NULL) { 876 return BOOTSTRAP_LOADER_NAME; 877 } else if (_name != NULL) { 878 return _name->as_C_string(); 879 } else { 880 return _class_loader_klass->external_name(); 881 } 882 } 883 884 // Caller needs ResourceMark 885 // Format of the _name_and_id is as follows: 886 // If the defining loader has a name explicitly set then '<loader-name>' @<id> 887 // If the defining loader has no name then <qualified-class-name> @<id> 888 // If built-in loader, then omit '@<id>' as there is only one instance. 889 const char* ClassLoaderData::loader_name_and_id() const { 890 if (_class_loader_klass == NULL) { 891 return "'" BOOTSTRAP_LOADER_NAME "'"; 892 } else if (_name_and_id != NULL) { 893 return _name_and_id->as_C_string(); 894 } else { 895 // May be called in a race before _name_and_id is initialized. 896 return _class_loader_klass->external_name(); 897 } 898 } 899 900 void ClassLoaderData::print_value_on(outputStream* out) const { 901 if (!is_unloading() && class_loader() != NULL) { 902 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this)); 903 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance 904 } else { 905 // loader data: 0xsomeaddr of 'bootstrap' 906 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id()); 907 } 908 if (is_unsafe_anonymous()) { 909 out->print(" unsafe anonymous"); 910 } 911 } 912 913 #ifndef PRODUCT 914 void ClassLoaderData::print_on(outputStream* out) const { 915 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {", 916 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id()); 917 if (is_unsafe_anonymous()) out->print(" unsafe anonymous"); 918 if (claimed()) out->print(" claimed"); 919 if (is_unloading()) out->print(" unloading"); 920 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 921 922 if (_jmethod_ids != NULL) { 923 Method::print_jmethod_ids(this, out); 924 } 925 out->print(" handles count %d", _handles.count()); 926 out->print(" dependencies %d", _dependency_count); 927 out->print_cr("}"); 928 } 929 #endif // PRODUCT 930 931 void ClassLoaderData::verify() { 932 assert_locked_or_safepoint(_metaspace_lock); 933 oop cl = class_loader(); 934 935 guarantee(this == class_loader_data(cl) || is_unsafe_anonymous(), "Must be the same"); 936 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_unsafe_anonymous(), "must be"); 937 938 // Verify the integrity of the allocated space. 939 if (metaspace_or_null() != NULL) { 940 metaspace_or_null()->verify(); 941 } 942 943 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 944 guarantee(k->class_loader_data() == this, "Must be the same"); 945 k->verify(); 946 assert(k != k->next_link(), "no loops!"); 947 } 948 } 949 950 bool ClassLoaderData::contains_klass(Klass* klass) { 951 // Lock-free access requires load_acquire 952 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 953 if (k == klass) return true; 954 } 955 return false; 956 }