1 /* 2 * Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 // 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/safepoint.hpp" 71 #include "utilities/growableArray.hpp" 72 #include "utilities/macros.hpp" 73 #include "utilities/ostream.hpp" 74 75 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 76 77 void ClassLoaderData::init_null_class_loader_data() { 78 assert(_the_null_class_loader_data == NULL, "cannot initialize twice"); 79 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice"); 80 81 _the_null_class_loader_data = new ClassLoaderData(Handle(), false); 82 ClassLoaderDataGraph::_head = _the_null_class_loader_data; 83 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be"); 84 85 LogTarget(Trace, class, loader, data) lt; 86 if (lt.is_enabled()) { 87 ResourceMark rm; 88 LogStream ls(lt); 89 ls.print("create "); 90 _the_null_class_loader_data->print_value_on(&ls); 91 ls.cr(); 92 } 93 } 94 95 // Obtain and set the class loader's name within the ClassLoaderData so 96 // it will be available for error messages, logging, JFR, etc. The name 97 // and klass are available after the class_loader oop is no longer alive, 98 // during unloading. 99 void ClassLoaderData::initialize_name(Handle class_loader) { 100 Thread* THREAD = Thread::current(); 101 ResourceMark rm(THREAD); 102 103 // Obtain the class loader's name. If the class loader's name was not 104 // explicitly set during construction, the CLD's _name field will be null. 105 oop cl_name = java_lang_ClassLoader::name(class_loader()); 106 if (cl_name != NULL) { 107 const char* cl_instance_name = java_lang_String::as_utf8_string(cl_name); 108 109 if (cl_instance_name != NULL && cl_instance_name[0] != '\0') { 110 _name = SymbolTable::new_symbol(cl_instance_name); 111 } 112 } 113 114 // Obtain the class loader's name and identity hash. If the class loader's 115 // name was not explicitly set during construction, the class loader's name and id 116 // will be set to the qualified class name of the class loader along with its 117 // identity hash. 118 // If for some reason the ClassLoader's constructor has not been run, instead of 119 // leaving the _name_and_id field null, fall back to the external qualified class 120 // name. Thus CLD's _name_and_id field should never have a null value. 121 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader()); 122 const char* cl_instance_name_and_id = 123 (cl_name_and_id == NULL) ? _class_loader_klass->external_name() : 124 java_lang_String::as_utf8_string(cl_name_and_id); 125 assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id"); 126 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id); 127 } 128 129 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool has_class_mirror_holder) : 130 _metaspace(NULL), 131 _metaspace_lock(new Mutex(Mutex::leaf+1, "Metaspace allocation lock", true, 132 Mutex::_safepoint_check_never)), 133 _unloading(false), _has_class_mirror_holder(has_class_mirror_holder), 134 _modified_oops(true), _accumulated_modified_oops(false), 135 // An unsafe anonymous class loader data doesn't have anything to keep 136 // it from being unloaded during parsing of the unsafe anonymous class. 137 // The null-class-loader should always be kept alive. 138 _keep_alive((has_class_mirror_holder || h_class_loader.is_null()) ? 1 : 0), 139 _claim(0), 140 _handles(), 141 _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL), 142 _jmethod_ids(NULL), 143 _deallocate_list(NULL), 144 _next(NULL), 145 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL) { 146 147 if (!h_class_loader.is_null()) { 148 _class_loader = _handles.add(h_class_loader()); 149 _class_loader_klass = h_class_loader->klass(); 150 initialize_name(h_class_loader); 151 } 152 153 if (!has_class_mirror_holder) { 154 // The holder is initialized later for weak hidden and unsafe anonymous classes, 155 // and before calling anything that call class_loader(). 156 initialize_holder(h_class_loader); 157 158 // A ClassLoaderData created solely for an weak hidden or unsafe anonymous class should 159 // never have a ModuleEntryTable or PackageEntryTable created for it. The defining package 160 // and module for an unsafe anonymous class will be found in its host class. 161 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); 162 if (h_class_loader.is_null()) { 163 // Create unnamed module for boot loader 164 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this); 165 } else { 166 // Create unnamed module for all other loaders 167 _unnamed_module = ModuleEntry::create_unnamed_module(this); 168 } 169 _dictionary = create_dictionary(); 170 } 171 172 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies 173 174 JFR_ONLY(INIT_ID(this);) 175 } 176 177 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() { 178 Chunk* c = _head; 179 while (c != NULL) { 180 Chunk* next = c->_next; 181 delete c; 182 c = next; 183 } 184 } 185 186 oop* ClassLoaderData::ChunkedHandleList::add(oop o) { 187 if (_head == NULL || _head->_size == Chunk::CAPACITY) { 188 Chunk* next = new Chunk(_head); 189 Atomic::release_store(&_head, next); 190 } 191 oop* handle = &_head->_data[_head->_size]; 192 NativeAccess<IS_DEST_UNINITIALIZED>::oop_store(handle, o); 193 Atomic::release_store(&_head->_size, _head->_size + 1); 194 return handle; 195 } 196 197 int ClassLoaderData::ChunkedHandleList::count() const { 198 int count = 0; 199 Chunk* chunk = _head; 200 while (chunk != NULL) { 201 count += chunk->_size; 202 chunk = chunk->_next; 203 } 204 return count; 205 } 206 207 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) { 208 for (juint i = 0; i < size; i++) { 209 if (c->_data[i] != NULL) { 210 f->do_oop(&c->_data[i]); 211 } 212 } 213 } 214 215 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) { 216 Chunk* head = Atomic::load_acquire(&_head); 217 if (head != NULL) { 218 // Must be careful when reading size of head 219 oops_do_chunk(f, head, Atomic::load_acquire(&head->_size)); 220 for (Chunk* c = head->_next; c != NULL; c = c->_next) { 221 oops_do_chunk(f, c, c->_size); 222 } 223 } 224 } 225 226 class VerifyContainsOopClosure : public OopClosure { 227 oop _target; 228 bool _found; 229 230 public: 231 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {} 232 233 void do_oop(oop* p) { 234 if (p != NULL && NativeAccess<AS_NO_KEEPALIVE>::oop_load(p) == _target) { 235 _found = true; 236 } 237 } 238 239 void do_oop(narrowOop* p) { 240 // The ChunkedHandleList should not contain any narrowOop 241 ShouldNotReachHere(); 242 } 243 244 bool found() const { 245 return _found; 246 } 247 }; 248 249 bool ClassLoaderData::ChunkedHandleList::contains(oop p) { 250 VerifyContainsOopClosure cl(p); 251 oops_do(&cl); 252 return cl.found(); 253 } 254 255 #ifndef PRODUCT 256 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) { 257 Chunk* chunk = _head; 258 while (chunk != NULL) { 259 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) { 260 return true; 261 } 262 chunk = chunk->_next; 263 } 264 return false; 265 } 266 #endif // PRODUCT 267 268 void ClassLoaderData::clear_claim(int claim) { 269 for (;;) { 270 int old_claim = Atomic::load(&_claim); 271 if ((old_claim & claim) == 0) { 272 return; 273 } 274 int new_claim = old_claim & ~claim; 275 if (Atomic::cmpxchg(&_claim, old_claim, new_claim) == old_claim) { 276 return; 277 } 278 } 279 } 280 281 bool ClassLoaderData::try_claim(int claim) { 282 for (;;) { 283 int old_claim = Atomic::load(&_claim); 284 if ((old_claim & claim) == claim) { 285 return false; 286 } 287 int new_claim = old_claim | claim; 288 if (Atomic::cmpxchg(&_claim, old_claim, new_claim) == old_claim) { 289 return true; 290 } 291 } 292 } 293 294 // Weak hidden and unsafe anonymous classes have their own ClassLoaderData that is marked to keep alive 295 // while the class is being parsed, and if the class appears on the module fixup list. 296 // Due to the uniqueness that no other class shares the hidden or unsafe anonymous class' name or 297 // ClassLoaderData, no other non-GC thread has knowledge of the hidden or unsafe anonymous class while 298 // it is being defined, therefore _keep_alive is not volatile or atomic. 299 void ClassLoaderData::inc_keep_alive() { 300 if (has_class_mirror_holder()) { 301 assert(_keep_alive > 0, "Invalid keep alive increment count"); 302 _keep_alive++; 303 } 304 } 305 306 void ClassLoaderData::dec_keep_alive() { 307 if (has_class_mirror_holder()) { 308 assert(_keep_alive > 0, "Invalid keep alive decrement count"); 309 _keep_alive--; 310 } 311 } 312 313 void ClassLoaderData::oops_do(OopClosure* f, int claim_value, bool clear_mod_oops) { 314 if (claim_value != ClassLoaderData::_claim_none && !try_claim(claim_value)) { 315 return; 316 } 317 318 // Only clear modified_oops after the ClassLoaderData is claimed. 319 if (clear_mod_oops) { 320 clear_modified_oops(); 321 } 322 323 _handles.oops_do(f); 324 } 325 326 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 327 // Lock-free access requires load_acquire 328 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 329 klass_closure->do_klass(k); 330 assert(k != k->next_link(), "no loops!"); 331 } 332 } 333 334 void ClassLoaderData::classes_do(void f(Klass * const)) { 335 // Lock-free access requires load_acquire 336 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 337 f(k); 338 assert(k != k->next_link(), "no loops!"); 339 } 340 } 341 342 void ClassLoaderData::methods_do(void f(Method*)) { 343 // Lock-free access requires load_acquire 344 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 345 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) { 346 InstanceKlass::cast(k)->methods_do(f); 347 } 348 } 349 } 350 351 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 352 // Lock-free access requires load_acquire 353 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 354 // Do not filter ArrayKlass oops here... 355 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { 356 #ifdef ASSERT 357 oop m = k->java_mirror(); 358 assert(m != NULL, "NULL mirror"); 359 assert(m->is_a(SystemDictionary::Class_klass()), "invalid mirror"); 360 #endif 361 klass_closure->do_klass(k); 362 } 363 } 364 } 365 366 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 367 // Lock-free access requires load_acquire 368 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 369 if (k->is_instance_klass()) { 370 f(InstanceKlass::cast(k)); 371 } 372 assert(k != k->next_link(), "no loops!"); 373 } 374 } 375 376 void ClassLoaderData::modules_do(void f(ModuleEntry*)) { 377 assert_locked_or_safepoint(Module_lock); 378 if (_unnamed_module != NULL) { 379 f(_unnamed_module); 380 } 381 if (_modules != NULL) { 382 for (int i = 0; i < _modules->table_size(); i++) { 383 for (ModuleEntry* entry = _modules->bucket(i); 384 entry != NULL; 385 entry = entry->next()) { 386 f(entry); 387 } 388 } 389 } 390 } 391 392 void ClassLoaderData::packages_do(void f(PackageEntry*)) { 393 assert_locked_or_safepoint(Module_lock); 394 if (_packages != NULL) { 395 for (int i = 0; i < _packages->table_size(); i++) { 396 for (PackageEntry* entry = _packages->bucket(i); 397 entry != NULL; 398 entry = entry->next()) { 399 f(entry); 400 } 401 } 402 } 403 } 404 405 void ClassLoaderData::record_dependency(const Klass* k) { 406 assert(k != NULL, "invariant"); 407 408 ClassLoaderData * const from_cld = this; 409 ClassLoaderData * const to_cld = k->class_loader_data(); 410 411 // Do not need to record dependency if the dependency is to a class whose 412 // class loader data is never freed. (i.e. the dependency's class loader 413 // is one of the three builtin class loaders and the dependency's class 414 // loader data has a ClassLoader holder, not a Class holder.) 415 if (to_cld->is_permanent_class_loader_data()) { 416 return; 417 } 418 419 oop to; 420 if (to_cld->has_class_mirror_holder()) { 421 // Just return if a weak hidden or unsafe anonymous class is attempting to record a dependency 422 // to itself. (Note that every weak hidden or unsafe anonymous class has its own unique class 423 // loader data.) 424 if (to_cld == from_cld) { 425 return; 426 } 427 // Hidden and unsafe anonymous class dependencies are through the mirror. 428 to = k->java_mirror(); 429 } else { 430 to = to_cld->class_loader(); 431 oop from = from_cld->class_loader(); 432 433 // Just return if this dependency is to a class with the same or a parent 434 // class_loader. 435 if (from == to || java_lang_ClassLoader::isAncestor(from, to)) { 436 return; // this class loader is in the parent list, no need to add it. 437 } 438 } 439 440 // It's a dependency we won't find through GC, add it. 441 if (!_handles.contains(to)) { 442 NOT_PRODUCT(Atomic::inc(&_dependency_count)); 443 LogTarget(Trace, class, loader, data) lt; 444 if (lt.is_enabled()) { 445 ResourceMark rm; 446 LogStream ls(lt); 447 ls.print("adding dependency from "); 448 print_value_on(&ls); 449 ls.print(" to "); 450 to_cld->print_value_on(&ls); 451 ls.cr(); 452 } 453 Handle dependency(Thread::current(), to); 454 add_handle(dependency); 455 // Added a potentially young gen oop to the ClassLoaderData 456 record_modified_oops(); 457 } 458 } 459 460 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 461 { 462 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 463 Klass* old_value = _klasses; 464 k->set_next_link(old_value); 465 // Link the new item into the list, making sure the linked class is stable 466 // since the list can be walked without a lock 467 Atomic::release_store(&_klasses, k); 468 if (k->is_array_klass()) { 469 ClassLoaderDataGraph::inc_array_classes(1); 470 } else { 471 ClassLoaderDataGraph::inc_instance_classes(1); 472 } 473 } 474 475 if (publicize) { 476 LogTarget(Trace, class, loader, data) lt; 477 if (lt.is_enabled()) { 478 ResourceMark rm; 479 LogStream ls(lt); 480 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name()); 481 print_value_on(&ls); 482 ls.cr(); 483 } 484 } 485 } 486 487 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) { 488 if (loader_or_mirror() != NULL) { 489 assert(_holder.is_null(), "never replace holders"); 490 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror); 491 } 492 } 493 494 // Remove a klass from the _klasses list for scratch_class during redefinition 495 // or parsed class in the case of an error. 496 void ClassLoaderData::remove_class(Klass* scratch_class) { 497 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 498 499 // Adjust global class iterator. 500 ClassLoaderDataGraph::adjust_saved_class(scratch_class); 501 502 Klass* prev = NULL; 503 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 504 if (k == scratch_class) { 505 if (prev == NULL) { 506 _klasses = k->next_link(); 507 } else { 508 Klass* next = k->next_link(); 509 prev->set_next_link(next); 510 } 511 512 if (k->is_array_klass()) { 513 ClassLoaderDataGraph::dec_array_classes(1); 514 } else { 515 ClassLoaderDataGraph::dec_instance_classes(1); 516 } 517 518 return; 519 } 520 prev = k; 521 assert(k != k->next_link(), "no loops!"); 522 } 523 ShouldNotReachHere(); // should have found this class!! 524 } 525 526 void ClassLoaderData::unload() { 527 _unloading = true; 528 529 LogTarget(Trace, class, loader, data) lt; 530 if (lt.is_enabled()) { 531 ResourceMark rm; 532 LogStream ls(lt); 533 ls.print("unload"); 534 print_value_on(&ls); 535 ls.cr(); 536 } 537 538 // Some items on the _deallocate_list need to free their C heap structures 539 // if they are not already on the _klasses list. 540 free_deallocate_list_C_heap_structures(); 541 542 // Clean up class dependencies and tell serviceability tools 543 // these classes are unloading. Must be called 544 // after erroneous classes are released. 545 classes_do(InstanceKlass::unload_class); 546 547 // Clean up global class iterator for compiler 548 ClassLoaderDataGraph::adjust_saved_class(this); 549 } 550 551 ModuleEntryTable* ClassLoaderData::modules() { 552 // Lazily create the module entry table at first request. 553 // Lock-free access requires load_acquire. 554 ModuleEntryTable* modules = Atomic::load_acquire(&_modules); 555 if (modules == NULL) { 556 MutexLocker m1(Module_lock); 557 // Check if _modules got allocated while we were waiting for this lock. 558 if ((modules = _modules) == NULL) { 559 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); 560 561 { 562 MutexLocker m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 563 // Ensure _modules is stable, since it is examined without a lock 564 Atomic::release_store(&_modules, modules); 565 } 566 } 567 } 568 return modules; 569 } 570 571 const int _boot_loader_dictionary_size = 1009; 572 const int _default_loader_dictionary_size = 107; 573 574 Dictionary* ClassLoaderData::create_dictionary() { 575 assert(!has_class_mirror_holder(), "class mirror holder cld does not have a dictionary"); 576 int size; 577 bool resizable = false; 578 if (_the_null_class_loader_data == NULL) { 579 size = _boot_loader_dictionary_size; 580 resizable = true; 581 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 582 size = 1; // there's only one class in relection class loader and no initiated classes 583 } else if (is_system_class_loader_data()) { 584 size = _boot_loader_dictionary_size; 585 resizable = true; 586 } else { 587 size = _default_loader_dictionary_size; 588 resizable = true; 589 } 590 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) { 591 resizable = false; 592 } 593 return new Dictionary(this, size, resizable); 594 } 595 596 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph 597 oop ClassLoaderData::holder_phantom() const { 598 // A klass that was previously considered dead can be looked up in the 599 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root 600 // or a reachable object making it alive again. The SATB part of G1 needs 601 // to get notified about this potential resurrection, otherwise the marking 602 // might not find the object. 603 if (!_holder.is_null()) { // NULL class_loader 604 return _holder.resolve(); 605 } else { 606 return NULL; 607 } 608 } 609 610 // Let the GC read the holder without keeping it alive. 611 oop ClassLoaderData::holder_no_keepalive() const { 612 if (!_holder.is_null()) { // NULL class_loader 613 return _holder.peek(); 614 } else { 615 return NULL; 616 } 617 } 618 619 // Unloading support 620 bool ClassLoaderData::is_alive() const { 621 bool alive = keep_alive() // null class loader and incomplete weak hidden or unsafe anonymous klasses. 622 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing. 623 624 return alive; 625 } 626 627 class ReleaseKlassClosure: public KlassClosure { 628 private: 629 size_t _instance_class_released; 630 size_t _array_class_released; 631 public: 632 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { } 633 634 size_t instance_class_released() const { return _instance_class_released; } 635 size_t array_class_released() const { return _array_class_released; } 636 637 void do_klass(Klass* k) { 638 if (k->is_array_klass()) { 639 _array_class_released ++; 640 } else { 641 assert(k->is_instance_klass(), "Must be"); 642 _instance_class_released ++; 643 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k)); 644 } 645 } 646 }; 647 648 ClassLoaderData::~ClassLoaderData() { 649 // Release C heap structures for all the classes. 650 ReleaseKlassClosure cl; 651 classes_do(&cl); 652 653 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released()); 654 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released()); 655 656 // Release the WeakHandle 657 _holder.release(); 658 659 // Release C heap allocated hashtable for all the packages. 660 if (_packages != NULL) { 661 // Destroy the table itself 662 delete _packages; 663 _packages = NULL; 664 } 665 666 // Release C heap allocated hashtable for all the modules. 667 if (_modules != NULL) { 668 // Destroy the table itself 669 delete _modules; 670 _modules = NULL; 671 } 672 673 // Release C heap allocated hashtable for the dictionary 674 if (_dictionary != NULL) { 675 // Destroy the table itself 676 delete _dictionary; 677 _dictionary = NULL; 678 } 679 680 if (_unnamed_module != NULL) { 681 _unnamed_module->delete_unnamed_module(); 682 _unnamed_module = NULL; 683 } 684 685 // release the metaspace 686 ClassLoaderMetaspace *m = _metaspace; 687 if (m != NULL) { 688 _metaspace = NULL; 689 delete m; 690 } 691 // Clear all the JNI handles for methods 692 // These aren't deallocated and are going to look like a leak, but that's 693 // needed because we can't really get rid of jmethodIDs because we don't 694 // know when native code is going to stop using them. The spec says that 695 // they're "invalid" but existing programs likely rely on their being 696 // NULL after class unloading. 697 if (_jmethod_ids != NULL) { 698 Method::clear_jmethod_ids(this); 699 } 700 // Delete lock 701 delete _metaspace_lock; 702 703 // Delete free list 704 if (_deallocate_list != NULL) { 705 delete _deallocate_list; 706 } 707 708 // Decrement refcounts of Symbols if created. 709 if (_name != NULL) { 710 _name->decrement_refcount(); 711 } 712 if (_name_and_id != NULL) { 713 _name_and_id->decrement_refcount(); 714 } 715 } 716 717 // Returns true if this class loader data is for the app class loader 718 // or a user defined system class loader. (Note that the class loader 719 // data may have a Class holder.) 720 bool ClassLoaderData::is_system_class_loader_data() const { 721 return SystemDictionary::is_system_class_loader(class_loader()); 722 } 723 724 // Returns true if this class loader data is for the platform class loader. 725 // (Note that the class loader data may have a Class holder.) 726 bool ClassLoaderData::is_platform_class_loader_data() const { 727 return SystemDictionary::is_platform_class_loader(class_loader()); 728 } 729 730 // Returns true if the class loader for this class loader data is one of 731 // the 3 builtin (boot application/system or platform) class loaders, 732 // including a user-defined system class loader. Note that if the class 733 // loader data is for a weak hidden or unsafe anonymous class then it may 734 // get freed by a GC even if its class loader is one of these loaders. 735 bool ClassLoaderData::is_builtin_class_loader_data() const { 736 return (is_boot_class_loader_data() || 737 SystemDictionary::is_system_class_loader(class_loader()) || 738 SystemDictionary::is_platform_class_loader(class_loader())); 739 } 740 741 // Returns true if this class loader data is a class loader data 742 // that is not ever freed by a GC. It must be the CLD for one of the builtin 743 // class loaders and not the CLD for a weak hidden or unsafe anonymous class. 744 bool ClassLoaderData::is_permanent_class_loader_data() const { 745 return is_builtin_class_loader_data() && !has_class_mirror_holder(); 746 } 747 748 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() { 749 // If the metaspace has not been allocated, create a new one. Might want 750 // to create smaller arena for Reflection class loaders also. 751 // The reason for the delayed allocation is because some class loaders are 752 // simply for delegating with no metadata of their own. 753 // Lock-free access requires load_acquire. 754 ClassLoaderMetaspace* metaspace = Atomic::load_acquire(&_metaspace); 755 if (metaspace == NULL) { 756 MutexLocker ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); 757 // Check if _metaspace got allocated while we were waiting for this lock. 758 if ((metaspace = _metaspace) == NULL) { 759 if (this == the_null_class_loader_data()) { 760 assert (class_loader() == NULL, "Must be"); 761 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType); 762 } else if (has_class_mirror_holder()) { 763 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ClassMirrorHolderMetaspaceType); 764 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 765 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); 766 } else { 767 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); 768 } 769 // Ensure _metaspace is stable, since it is examined without a lock 770 Atomic::release_store(&_metaspace, metaspace); 771 } 772 } 773 return metaspace; 774 } 775 776 OopHandle ClassLoaderData::add_handle(Handle h) { 777 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 778 record_modified_oops(); 779 return OopHandle(_handles.add(h())); 780 } 781 782 void ClassLoaderData::remove_handle(OopHandle h) { 783 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading"); 784 oop* ptr = h.ptr_raw(); 785 if (ptr != NULL) { 786 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr)); 787 NativeAccess<>::oop_store(ptr, oop(NULL)); 788 } 789 } 790 791 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) { 792 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 793 if (dest.resolve() != NULL) { 794 return; 795 } else { 796 dest = _handles.add(h()); 797 } 798 } 799 800 // Add this metadata pointer to be freed when it's safe. This is only during 801 // a safepoint which checks if handles point to this metadata field. 802 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 803 // Metadata in shared region isn't deleted. 804 if (!m->is_shared()) { 805 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 806 if (_deallocate_list == NULL) { 807 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 808 } 809 _deallocate_list->append_if_missing(m); 810 log_debug(class, loader, data)("deallocate added for %s", m->print_value_string()); 811 ClassLoaderDataGraph::set_should_clean_deallocate_lists(); 812 } 813 } 814 815 // Deallocate free metadata on the free list. How useful the PermGen was! 816 void ClassLoaderData::free_deallocate_list() { 817 // This must be called at a safepoint because it depends on metadata walking at 818 // safepoint cleanup time. 819 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 820 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading"); 821 if (_deallocate_list == NULL) { 822 return; 823 } 824 // Go backwards because this removes entries that are freed. 825 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 826 Metadata* m = _deallocate_list->at(i); 827 if (!m->on_stack()) { 828 _deallocate_list->remove_at(i); 829 // There are only three types of metadata that we deallocate directly. 830 // Cast them so they can be used by the template function. 831 if (m->is_method()) { 832 MetadataFactory::free_metadata(this, (Method*)m); 833 } else if (m->is_constantPool()) { 834 MetadataFactory::free_metadata(this, (ConstantPool*)m); 835 } else if (m->is_klass()) { 836 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 837 } else { 838 ShouldNotReachHere(); 839 } 840 } else { 841 // Metadata is alive. 842 // If scratch_class is on stack then it shouldn't be on this list! 843 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 844 "scratch classes on this list should be dead"); 845 // Also should assert that other metadata on the list was found in handles. 846 // Some cleaning remains. 847 ClassLoaderDataGraph::set_should_clean_deallocate_lists(); 848 } 849 } 850 } 851 852 // This is distinct from free_deallocate_list. For class loader data that are 853 // unloading, this frees the C heap memory for items on the list, and unlinks 854 // scratch or error classes so that unloading events aren't triggered for these 855 // classes. The metadata is removed with the unloading metaspace. 856 // There isn't C heap memory allocated for methods, so nothing is done for them. 857 void ClassLoaderData::free_deallocate_list_C_heap_structures() { 858 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 859 assert(is_unloading(), "only called for ClassLoaderData that are unloading"); 860 if (_deallocate_list == NULL) { 861 return; 862 } 863 // Go backwards because this removes entries that are freed. 864 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 865 Metadata* m = _deallocate_list->at(i); 866 _deallocate_list->remove_at(i); 867 if (m->is_constantPool()) { 868 ((ConstantPool*)m)->release_C_heap_structures(); 869 } else if (m->is_klass()) { 870 InstanceKlass* ik = (InstanceKlass*)m; 871 // also releases ik->constants() C heap memory 872 InstanceKlass::release_C_heap_structures(ik); 873 // Remove the class so unloading events aren't triggered for 874 // this class (scratch or error class) in do_unloading(). 875 remove_class(ik); 876 } 877 } 878 } 879 880 // These CLDs are to contain weak hidden or unsafe anonymous classes used for JSR292 881 ClassLoaderData* ClassLoaderData::has_class_mirror_holder_cld(Handle loader) { 882 // Add a new class loader data to the graph. 883 return ClassLoaderDataGraph::add(loader, true); 884 } 885 886 // Caller needs ResourceMark 887 // If the class loader's _name has not been explicitly set, the class loader's 888 // qualified class name is returned. 889 const char* ClassLoaderData::loader_name() const { 890 if (_class_loader_klass == NULL) { 891 return BOOTSTRAP_LOADER_NAME; 892 } else if (_name != NULL) { 893 return _name->as_C_string(); 894 } else { 895 return _class_loader_klass->external_name(); 896 } 897 } 898 899 // Caller needs ResourceMark 900 // Format of the _name_and_id is as follows: 901 // If the defining loader has a name explicitly set then '<loader-name>' @<id> 902 // If the defining loader has no name then <qualified-class-name> @<id> 903 // If built-in loader, then omit '@<id>' as there is only one instance. 904 const char* ClassLoaderData::loader_name_and_id() const { 905 if (_class_loader_klass == NULL) { 906 return "'" BOOTSTRAP_LOADER_NAME "'"; 907 } else if (_name_and_id != NULL) { 908 return _name_and_id->as_C_string(); 909 } else { 910 // May be called in a race before _name_and_id is initialized. 911 return _class_loader_klass->external_name(); 912 } 913 } 914 915 void ClassLoaderData::print_value_on(outputStream* out) const { 916 if (!is_unloading() && class_loader() != NULL) { 917 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this)); 918 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance 919 } else { 920 // loader data: 0xsomeaddr of 'bootstrap' 921 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id()); 922 } 923 if (_has_class_mirror_holder) { 924 out->print(" has a class holder"); 925 } 926 } 927 928 void ClassLoaderData::print_value() const { print_value_on(tty); } 929 930 #ifndef PRODUCT 931 void ClassLoaderData::print_on(outputStream* out) const { 932 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {", 933 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id()); 934 if (has_class_mirror_holder()) out->print(" has a class holder"); 935 if (claimed()) out->print(" claimed"); 936 if (is_unloading()) out->print(" unloading"); 937 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 938 939 if (_jmethod_ids != NULL) { 940 Method::print_jmethod_ids(this, out); 941 } 942 out->print(" handles count %d", _handles.count()); 943 out->print(" dependencies %d", _dependency_count); 944 out->print_cr("}"); 945 } 946 #endif // PRODUCT 947 948 void ClassLoaderData::print() const { print_on(tty); } 949 950 void ClassLoaderData::verify() { 951 assert_locked_or_safepoint(_metaspace_lock); 952 oop cl = class_loader(); 953 954 guarantee(this == class_loader_data(cl) || has_class_mirror_holder(), "Must be the same"); 955 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || has_class_mirror_holder(), "must be"); 956 957 // Verify the integrity of the allocated space. 958 if (metaspace_or_null() != NULL) { 959 metaspace_or_null()->verify(); 960 } 961 962 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 963 guarantee(k->class_loader_data() == this, "Must be the same"); 964 k->verify(); 965 assert(k != k->next_link(), "no loops!"); 966 } 967 } 968 969 bool ClassLoaderData::contains_klass(Klass* klass) { 970 // Lock-free access requires load_acquire 971 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 972 if (k == klass) return true; 973 } 974 return false; 975 }