1 /* 2 * Copyright (c) 2012, 2022, 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 "classfile/systemDictionaryShared.hpp" 59 #include "classfile/vmClasses.hpp" 60 #include "logging/log.hpp" 61 #include "logging/logStream.hpp" 62 #include "memory/allocation.inline.hpp" 63 #include "memory/classLoaderMetaspace.hpp" 64 #include "memory/metadataFactory.hpp" 65 #include "memory/metaspace.hpp" 66 #include "memory/resourceArea.hpp" 67 #include "memory/universe.hpp" 68 #include "oops/access.inline.hpp" 69 #include "oops/klass.inline.hpp" 70 #include "oops/objArrayKlass.hpp" 71 #include "oops/oop.inline.hpp" 72 #include "oops/oopHandle.inline.hpp" 73 #include "oops/inlineKlass.inline.hpp" 74 #include "oops/weakHandle.inline.hpp" 75 #include "runtime/arguments.hpp" 76 #include "runtime/atomic.hpp" 77 #include "runtime/handles.inline.hpp" 78 #include "runtime/mutex.hpp" 79 #include "runtime/safepoint.hpp" 80 #include "utilities/growableArray.hpp" 81 #include "utilities/macros.hpp" 82 #include "utilities/ostream.hpp" 83 84 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 85 86 void ClassLoaderData::init_null_class_loader_data() { 87 assert(_the_null_class_loader_data == NULL, "cannot initialize twice"); 88 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice"); 89 90 _the_null_class_loader_data = new ClassLoaderData(Handle(), false); 91 ClassLoaderDataGraph::_head = _the_null_class_loader_data; 92 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be"); 93 94 LogTarget(Trace, class, loader, data) lt; 95 if (lt.is_enabled()) { 96 ResourceMark rm; 97 LogStream ls(lt); 98 ls.print("create "); 99 _the_null_class_loader_data->print_value_on(&ls); 100 ls.cr(); 101 } 102 } 103 104 // Obtain and set the class loader's name within the ClassLoaderData so 105 // it will be available for error messages, logging, JFR, etc. The name 106 // and klass are available after the class_loader oop is no longer alive, 107 // during unloading. 108 void ClassLoaderData::initialize_name(Handle class_loader) { 109 ResourceMark rm; 110 111 // Obtain the class loader's name. If the class loader's name was not 112 // explicitly set during construction, the CLD's _name field will be null. 113 oop cl_name = java_lang_ClassLoader::name(class_loader()); 114 if (cl_name != NULL) { 115 const char* cl_instance_name = java_lang_String::as_utf8_string(cl_name); 116 117 if (cl_instance_name != NULL && cl_instance_name[0] != '\0') { 118 _name = SymbolTable::new_symbol(cl_instance_name); 119 } 120 } 121 122 // Obtain the class loader's name and identity hash. If the class loader's 123 // name was not explicitly set during construction, the class loader's name and id 124 // will be set to the qualified class name of the class loader along with its 125 // identity hash. 126 // If for some reason the ClassLoader's constructor has not been run, instead of 127 // leaving the _name_and_id field null, fall back to the external qualified class 128 // name. Thus CLD's _name_and_id field should never have a null value. 129 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader()); 130 const char* cl_instance_name_and_id = 131 (cl_name_and_id == NULL) ? _class_loader_klass->external_name() : 132 java_lang_String::as_utf8_string(cl_name_and_id); 133 assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id"); 134 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id); 135 } 136 137 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool has_class_mirror_holder) : 138 _metaspace(NULL), 139 _metaspace_lock(new Mutex(Mutex::nosafepoint-2, "MetaspaceAllocation_lock")), 140 _unloading(false), _has_class_mirror_holder(has_class_mirror_holder), 141 _modified_oops(true), 142 // A non-strong hidden class loader data doesn't have anything to keep 143 // it from being unloaded during parsing of the non-strong hidden class. 144 // The null-class-loader should always be kept alive. 145 _keep_alive((has_class_mirror_holder || h_class_loader.is_null()) ? 1 : 0), 146 _claim(0), 147 _handles(), 148 _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL), 149 _jmethod_ids(NULL), 150 _deallocate_list(NULL), 151 _next(NULL), 152 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL) { 153 154 if (!h_class_loader.is_null()) { 155 _class_loader = _handles.add(h_class_loader()); 156 _class_loader_klass = h_class_loader->klass(); 157 initialize_name(h_class_loader); 158 } 159 160 if (!has_class_mirror_holder) { 161 // The holder is initialized later for non-strong hidden classes, 162 // and before calling anything that call class_loader(). 163 initialize_holder(h_class_loader); 164 165 // A ClassLoaderData created solely for a non-strong hidden class should never 166 // have a ModuleEntryTable or PackageEntryTable created for it. 167 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); 168 if (h_class_loader.is_null()) { 169 // Create unnamed module for boot loader 170 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this); 171 } else { 172 // Create unnamed module for all other loaders 173 _unnamed_module = ModuleEntry::create_unnamed_module(this); 174 } 175 _dictionary = create_dictionary(); 176 } 177 178 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies 179 180 JFR_ONLY(INIT_ID(this);) 181 } 182 183 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() { 184 Chunk* c = _head; 185 while (c != NULL) { 186 Chunk* next = c->_next; 187 delete c; 188 c = next; 189 } 190 } 191 192 OopHandle ClassLoaderData::ChunkedHandleList::add(oop o) { 193 if (_head == NULL || _head->_size == Chunk::CAPACITY) { 194 Chunk* next = new Chunk(_head); 195 Atomic::release_store(&_head, next); 196 } 197 oop* handle = &_head->_data[_head->_size]; 198 NativeAccess<IS_DEST_UNINITIALIZED>::oop_store(handle, o); 199 Atomic::release_store(&_head->_size, _head->_size + 1); 200 return OopHandle(handle); 201 } 202 203 int ClassLoaderData::ChunkedHandleList::count() const { 204 int count = 0; 205 Chunk* chunk = _head; 206 while (chunk != NULL) { 207 count += chunk->_size; 208 chunk = chunk->_next; 209 } 210 return count; 211 } 212 213 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) { 214 for (juint i = 0; i < size; i++) { 215 if (c->_data[i] != NULL) { 216 f->do_oop(&c->_data[i]); 217 } 218 } 219 } 220 221 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) { 222 Chunk* head = Atomic::load_acquire(&_head); 223 if (head != NULL) { 224 // Must be careful when reading size of head 225 oops_do_chunk(f, head, Atomic::load_acquire(&head->_size)); 226 for (Chunk* c = head->_next; c != NULL; c = c->_next) { 227 oops_do_chunk(f, c, c->_size); 228 } 229 } 230 } 231 232 class VerifyContainsOopClosure : public OopClosure { 233 oop _target; 234 bool _found; 235 236 public: 237 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {} 238 239 void do_oop(oop* p) { 240 if (p != NULL && NativeAccess<AS_NO_KEEPALIVE>::oop_load(p) == _target) { 241 _found = true; 242 } 243 } 244 245 void do_oop(narrowOop* p) { 246 // The ChunkedHandleList should not contain any narrowOop 247 ShouldNotReachHere(); 248 } 249 250 bool found() const { 251 return _found; 252 } 253 }; 254 255 bool ClassLoaderData::ChunkedHandleList::contains(oop p) { 256 VerifyContainsOopClosure cl(p); 257 oops_do(&cl); 258 return cl.found(); 259 } 260 261 #ifndef PRODUCT 262 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) { 263 Chunk* chunk = _head; 264 while (chunk != NULL) { 265 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) { 266 return true; 267 } 268 chunk = chunk->_next; 269 } 270 return false; 271 } 272 #endif // PRODUCT 273 274 void ClassLoaderData::clear_claim(int claim) { 275 for (;;) { 276 int old_claim = Atomic::load(&_claim); 277 if ((old_claim & claim) == 0) { 278 return; 279 } 280 int new_claim = old_claim & ~claim; 281 if (Atomic::cmpxchg(&_claim, old_claim, new_claim) == old_claim) { 282 return; 283 } 284 } 285 } 286 287 bool ClassLoaderData::try_claim(int claim) { 288 for (;;) { 289 int old_claim = Atomic::load(&_claim); 290 if ((old_claim & claim) == claim) { 291 return false; 292 } 293 int new_claim = old_claim | claim; 294 if (Atomic::cmpxchg(&_claim, old_claim, new_claim) == old_claim) { 295 return true; 296 } 297 } 298 } 299 300 // Non-strong hidden classes have their own ClassLoaderData that is marked to keep alive 301 // while the class is being parsed, and if the class appears on the module fixup list. 302 // Due to the uniqueness that no other class shares the hidden class' name or 303 // ClassLoaderData, no other non-GC thread has knowledge of the hidden class while 304 // it is being defined, therefore _keep_alive is not volatile or atomic. 305 void ClassLoaderData::inc_keep_alive() { 306 if (has_class_mirror_holder()) { 307 assert(_keep_alive > 0, "Invalid keep alive increment count"); 308 _keep_alive++; 309 } 310 } 311 312 void ClassLoaderData::dec_keep_alive() { 313 if (has_class_mirror_holder()) { 314 assert(_keep_alive > 0, "Invalid keep alive decrement count"); 315 _keep_alive--; 316 } 317 } 318 319 void ClassLoaderData::oops_do(OopClosure* f, int claim_value, bool clear_mod_oops) { 320 if (claim_value != ClassLoaderData::_claim_none && !try_claim(claim_value)) { 321 return; 322 } 323 324 // Only clear modified_oops after the ClassLoaderData is claimed. 325 if (clear_mod_oops) { 326 clear_modified_oops(); 327 } 328 329 _handles.oops_do(f); 330 } 331 332 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 333 // Lock-free access requires load_acquire 334 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 335 klass_closure->do_klass(k); 336 assert(k != k->next_link(), "no loops!"); 337 } 338 } 339 340 void ClassLoaderData::classes_do(void f(Klass * const)) { 341 // Lock-free access requires load_acquire 342 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 343 f(k); 344 assert(k != k->next_link(), "no loops!"); 345 } 346 } 347 348 void ClassLoaderData::methods_do(void f(Method*)) { 349 // Lock-free access requires load_acquire 350 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 351 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) { 352 InstanceKlass::cast(k)->methods_do(f); 353 } 354 } 355 } 356 357 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 358 // To call this, one must have the MultiArray_lock held, but the _klasses list still has lock free reads. 359 assert_locked_or_safepoint(MultiArray_lock); 360 361 // Lock-free access requires load_acquire 362 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 363 // Filter out InstanceKlasses (or their ObjArrayKlasses) that have not entered the 364 // loaded state. 365 if (k->is_instance_klass()) { 366 if (!InstanceKlass::cast(k)->is_loaded()) { 367 continue; 368 } 369 } else if (k->is_shared() && k->is_objArray_klass()) { 370 Klass* bottom = ObjArrayKlass::cast(k)->bottom_klass(); 371 if (bottom->is_instance_klass() && !InstanceKlass::cast(bottom)->is_loaded()) { 372 // This could happen if <bottom> is a shared class that has been restored 373 // but is not yet marked as loaded. All archived array classes of the 374 // bottom class are already restored and placed in the _klasses list. 375 continue; 376 } 377 } 378 379 #ifdef ASSERT 380 oop m = k->java_mirror(); 381 assert(m != NULL, "NULL mirror"); 382 assert(m->is_a(vmClasses::Class_klass()), "invalid mirror"); 383 #endif 384 klass_closure->do_klass(k); 385 } 386 } 387 388 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 389 // Lock-free access requires load_acquire 390 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 391 if (k->is_instance_klass()) { 392 f(InstanceKlass::cast(k)); 393 } 394 assert(k != k->next_link(), "no loops!"); 395 } 396 } 397 398 void ClassLoaderData::inline_classes_do(void f(InlineKlass*)) { 399 // Lock-free access requires load_acquire 400 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 401 if (k->is_inline_klass()) { 402 f(InlineKlass::cast(k)); 403 } 404 assert(k != k->next_link(), "no loops!"); 405 } 406 } 407 408 void ClassLoaderData::modules_do(void f(ModuleEntry*)) { 409 assert_locked_or_safepoint(Module_lock); 410 if (_unnamed_module != NULL) { 411 f(_unnamed_module); 412 } 413 if (_modules != NULL) { 414 for (int i = 0; i < _modules->table_size(); i++) { 415 for (ModuleEntry* entry = _modules->bucket(i); 416 entry != NULL; 417 entry = entry->next()) { 418 f(entry); 419 } 420 } 421 } 422 } 423 424 void ClassLoaderData::packages_do(void f(PackageEntry*)) { 425 assert_locked_or_safepoint(Module_lock); 426 if (_packages != NULL) { 427 for (int i = 0; i < _packages->table_size(); i++) { 428 for (PackageEntry* entry = _packages->bucket(i); 429 entry != NULL; 430 entry = entry->next()) { 431 f(entry); 432 } 433 } 434 } 435 } 436 437 void ClassLoaderData::record_dependency(const Klass* k) { 438 assert(k != NULL, "invariant"); 439 440 ClassLoaderData * const from_cld = this; 441 ClassLoaderData * const to_cld = k->class_loader_data(); 442 443 // Do not need to record dependency if the dependency is to a class whose 444 // class loader data is never freed. (i.e. the dependency's class loader 445 // is one of the three builtin class loaders and the dependency's class 446 // loader data has a ClassLoader holder, not a Class holder.) 447 if (to_cld->is_permanent_class_loader_data()) { 448 return; 449 } 450 451 oop to; 452 if (to_cld->has_class_mirror_holder()) { 453 // Just return if a non-strong hidden class class is attempting to record a dependency 454 // to itself. (Note that every non-strong hidden class has its own unique class 455 // loader data.) 456 if (to_cld == from_cld) { 457 return; 458 } 459 // Hidden class dependencies are through the mirror. 460 to = k->java_mirror(); 461 } else { 462 to = to_cld->class_loader(); 463 oop from = from_cld->class_loader(); 464 465 // Just return if this dependency is to a class with the same or a parent 466 // class_loader. 467 if (from == to || java_lang_ClassLoader::isAncestor(from, to)) { 468 return; // this class loader is in the parent list, no need to add it. 469 } 470 } 471 472 // It's a dependency we won't find through GC, add it. 473 if (!_handles.contains(to)) { 474 NOT_PRODUCT(Atomic::inc(&_dependency_count)); 475 LogTarget(Trace, class, loader, data) lt; 476 if (lt.is_enabled()) { 477 ResourceMark rm; 478 LogStream ls(lt); 479 ls.print("adding dependency from "); 480 print_value_on(&ls); 481 ls.print(" to "); 482 to_cld->print_value_on(&ls); 483 ls.cr(); 484 } 485 Handle dependency(Thread::current(), to); 486 add_handle(dependency); 487 // Added a potentially young gen oop to the ClassLoaderData 488 record_modified_oops(); 489 } 490 } 491 492 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 493 { 494 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 495 Klass* old_value = _klasses; 496 k->set_next_link(old_value); 497 // Link the new item into the list, making sure the linked class is stable 498 // since the list can be walked without a lock 499 Atomic::release_store(&_klasses, k); 500 if (k->is_array_klass()) { 501 ClassLoaderDataGraph::inc_array_classes(1); 502 } else { 503 ClassLoaderDataGraph::inc_instance_classes(1); 504 } 505 } 506 507 if (publicize) { 508 LogTarget(Trace, class, loader, data) lt; 509 if (lt.is_enabled()) { 510 ResourceMark rm; 511 LogStream ls(lt); 512 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name()); 513 print_value_on(&ls); 514 ls.cr(); 515 } 516 } 517 } 518 519 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) { 520 if (loader_or_mirror() != NULL) { 521 assert(_holder.is_null(), "never replace holders"); 522 _holder = WeakHandle(Universe::vm_weak(), loader_or_mirror); 523 } 524 } 525 526 // Remove a klass from the _klasses list for scratch_class during redefinition 527 // or parsed class in the case of an error. 528 void ClassLoaderData::remove_class(Klass* scratch_class) { 529 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 530 531 // Adjust global class iterator. 532 ClassLoaderDataGraph::adjust_saved_class(scratch_class); 533 534 Klass* prev = NULL; 535 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 536 if (k == scratch_class) { 537 if (prev == NULL) { 538 _klasses = k->next_link(); 539 } else { 540 Klass* next = k->next_link(); 541 prev->set_next_link(next); 542 } 543 544 if (k->is_array_klass()) { 545 ClassLoaderDataGraph::dec_array_classes(1); 546 } else { 547 ClassLoaderDataGraph::dec_instance_classes(1); 548 } 549 550 return; 551 } 552 prev = k; 553 assert(k != k->next_link(), "no loops!"); 554 } 555 ShouldNotReachHere(); // should have found this class!! 556 } 557 558 void ClassLoaderData::unload() { 559 _unloading = true; 560 561 LogTarget(Trace, class, loader, data) lt; 562 if (lt.is_enabled()) { 563 ResourceMark rm; 564 LogStream ls(lt); 565 ls.print("unload"); 566 print_value_on(&ls); 567 ls.cr(); 568 } 569 570 // Some items on the _deallocate_list need to free their C heap structures 571 // if they are not already on the _klasses list. 572 free_deallocate_list_C_heap_structures(); 573 574 inline_classes_do(InlineKlass::cleanup); 575 576 // Clean up class dependencies and tell serviceability tools 577 // these classes are unloading. Must be called 578 // after erroneous classes are released. 579 classes_do(InstanceKlass::unload_class); 580 581 // Method::clear_jmethod_ids only sets the jmethod_ids to NULL without 582 // releasing the memory for related JNIMethodBlocks and JNIMethodBlockNodes. 583 // This is done intentionally because native code (e.g. JVMTI agent) holding 584 // jmethod_ids may access them after the associated classes and class loader 585 // are unloaded. The Java Native Interface Specification says "method ID 586 // does not prevent the VM from unloading the class from which the ID has 587 // been derived. After the class is unloaded, the method or field ID becomes 588 // invalid". In real world usages, the native code may rely on jmethod_ids 589 // being NULL after class unloading. Hence, it is unsafe to free the memory 590 // from the VM side without knowing when native code is going to stop using 591 // them. 592 if (_jmethod_ids != NULL) { 593 Method::clear_jmethod_ids(this); 594 } 595 596 // Clean up global class iterator for compiler 597 ClassLoaderDataGraph::adjust_saved_class(this); 598 } 599 600 ModuleEntryTable* ClassLoaderData::modules() { 601 // Lazily create the module entry table at first request. 602 // Lock-free access requires load_acquire. 603 ModuleEntryTable* modules = Atomic::load_acquire(&_modules); 604 if (modules == NULL) { 605 MutexLocker m1(Module_lock); 606 // Check if _modules got allocated while we were waiting for this lock. 607 if ((modules = _modules) == NULL) { 608 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); 609 610 { 611 MutexLocker m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 612 // Ensure _modules is stable, since it is examined without a lock 613 Atomic::release_store(&_modules, modules); 614 } 615 } 616 } 617 return modules; 618 } 619 620 const int _boot_loader_dictionary_size = 1009; 621 const int _default_loader_dictionary_size = 107; 622 623 Dictionary* ClassLoaderData::create_dictionary() { 624 assert(!has_class_mirror_holder(), "class mirror holder cld does not have a dictionary"); 625 int size; 626 bool resizable = false; 627 if (_the_null_class_loader_data == NULL) { 628 size = _boot_loader_dictionary_size; 629 resizable = true; 630 } else if (class_loader()->is_a(vmClasses::reflect_DelegatingClassLoader_klass())) { 631 size = 1; // there's only one class in relection class loader and no initiated classes 632 } else if (is_system_class_loader_data()) { 633 size = _boot_loader_dictionary_size; 634 resizable = true; 635 } else { 636 size = _default_loader_dictionary_size; 637 resizable = true; 638 } 639 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) { 640 resizable = false; 641 } 642 return new Dictionary(this, size, resizable); 643 } 644 645 // Tell the GC to keep this klass alive. Needed while iterating ClassLoaderDataGraph, 646 // and any runtime code that uses klasses. 647 oop ClassLoaderData::holder() const { 648 // A klass that was previously considered dead can be looked up in the 649 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root 650 // or a reachable object making it alive again. The SATB part of G1 needs 651 // to get notified about this potential resurrection, otherwise the marking 652 // might not find the object. 653 if (!_holder.is_null()) { // NULL class_loader 654 return _holder.resolve(); 655 } else { 656 return NULL; 657 } 658 } 659 660 // Let the GC read the holder without keeping it alive. 661 oop ClassLoaderData::holder_no_keepalive() const { 662 if (!_holder.is_null()) { // NULL class_loader 663 return _holder.peek(); 664 } else { 665 return NULL; 666 } 667 } 668 669 // Unloading support 670 bool ClassLoaderData::is_alive() const { 671 bool alive = keep_alive() // null class loader and incomplete non-strong hidden class. 672 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing. 673 674 return alive; 675 } 676 677 class ReleaseKlassClosure: public KlassClosure { 678 private: 679 size_t _instance_class_released; 680 size_t _array_class_released; 681 public: 682 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { } 683 684 size_t instance_class_released() const { return _instance_class_released; } 685 size_t array_class_released() const { return _array_class_released; } 686 687 void do_klass(Klass* k) { 688 if (k->is_array_klass()) { 689 _array_class_released ++; 690 } else { 691 assert(k->is_instance_klass(), "Must be"); 692 _instance_class_released ++; 693 } 694 k->release_C_heap_structures(); 695 } 696 }; 697 698 ClassLoaderData::~ClassLoaderData() { 699 // Release C heap structures for all the classes. 700 ReleaseKlassClosure cl; 701 classes_do(&cl); 702 703 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released()); 704 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released()); 705 706 // Release the WeakHandle 707 _holder.release(Universe::vm_weak()); 708 709 // Release C heap allocated hashtable for all the packages. 710 if (_packages != NULL) { 711 // Destroy the table itself 712 delete _packages; 713 _packages = NULL; 714 } 715 716 // Release C heap allocated hashtable for all the modules. 717 if (_modules != NULL) { 718 // Destroy the table itself 719 delete _modules; 720 _modules = NULL; 721 } 722 723 // Release C heap allocated hashtable for the dictionary 724 if (_dictionary != NULL) { 725 // Destroy the table itself 726 delete _dictionary; 727 _dictionary = NULL; 728 } 729 730 if (_unnamed_module != NULL) { 731 _unnamed_module->delete_unnamed_module(); 732 _unnamed_module = NULL; 733 } 734 735 // release the metaspace 736 ClassLoaderMetaspace *m = _metaspace; 737 if (m != NULL) { 738 _metaspace = NULL; 739 delete m; 740 } 741 742 // Delete lock 743 delete _metaspace_lock; 744 745 // Delete free list 746 if (_deallocate_list != NULL) { 747 delete _deallocate_list; 748 } 749 750 // Decrement refcounts of Symbols if created. 751 if (_name != NULL) { 752 _name->decrement_refcount(); 753 } 754 if (_name_and_id != NULL) { 755 _name_and_id->decrement_refcount(); 756 } 757 } 758 759 // Returns true if this class loader data is for the app class loader 760 // or a user defined system class loader. (Note that the class loader 761 // data may have a Class holder.) 762 bool ClassLoaderData::is_system_class_loader_data() const { 763 return SystemDictionary::is_system_class_loader(class_loader()); 764 } 765 766 // Returns true if this class loader data is for the platform class loader. 767 // (Note that the class loader data may have a Class holder.) 768 bool ClassLoaderData::is_platform_class_loader_data() const { 769 return SystemDictionary::is_platform_class_loader(class_loader()); 770 } 771 772 // Returns true if the class loader for this class loader data is one of 773 // the 3 builtin (boot application/system or platform) class loaders, 774 // including a user-defined system class loader. Note that if the class 775 // loader data is for a non-strong hidden class then it may 776 // get freed by a GC even if its class loader is one of these loaders. 777 bool ClassLoaderData::is_builtin_class_loader_data() const { 778 return (is_boot_class_loader_data() || 779 SystemDictionary::is_system_class_loader(class_loader()) || 780 SystemDictionary::is_platform_class_loader(class_loader())); 781 } 782 783 // Returns true if this class loader data is a class loader data 784 // that is not ever freed by a GC. It must be the CLD for one of the builtin 785 // class loaders and not the CLD for a non-strong hidden class. 786 bool ClassLoaderData::is_permanent_class_loader_data() const { 787 return is_builtin_class_loader_data() && !has_class_mirror_holder(); 788 } 789 790 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() { 791 // If the metaspace has not been allocated, create a new one. Might want 792 // to create smaller arena for Reflection class loaders also. 793 // The reason for the delayed allocation is because some class loaders are 794 // simply for delegating with no metadata of their own. 795 // Lock-free access requires load_acquire. 796 ClassLoaderMetaspace* metaspace = Atomic::load_acquire(&_metaspace); 797 if (metaspace == NULL) { 798 MutexLocker ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); 799 // Check if _metaspace got allocated while we were waiting for this lock. 800 if ((metaspace = _metaspace) == NULL) { 801 if (this == the_null_class_loader_data()) { 802 assert (class_loader() == NULL, "Must be"); 803 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType); 804 } else if (has_class_mirror_holder()) { 805 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ClassMirrorHolderMetaspaceType); 806 } else if (class_loader()->is_a(vmClasses::reflect_DelegatingClassLoader_klass())) { 807 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); 808 } else { 809 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); 810 } 811 // Ensure _metaspace is stable, since it is examined without a lock 812 Atomic::release_store(&_metaspace, metaspace); 813 } 814 } 815 return metaspace; 816 } 817 818 OopHandle ClassLoaderData::add_handle(Handle h) { 819 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 820 record_modified_oops(); 821 return _handles.add(h()); 822 } 823 824 void ClassLoaderData::remove_handle(OopHandle h) { 825 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading"); 826 oop* ptr = h.ptr_raw(); 827 if (ptr != NULL) { 828 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr)); 829 NativeAccess<>::oop_store(ptr, oop(NULL)); 830 } 831 } 832 833 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) { 834 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 835 if (dest.resolve() != NULL) { 836 return; 837 } else { 838 record_modified_oops(); 839 dest = _handles.add(h()); 840 } 841 } 842 843 // Add this metadata pointer to be freed when it's safe. This is only during 844 // a safepoint which checks if handles point to this metadata field. 845 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 846 // Metadata in shared region isn't deleted. 847 if (!m->is_shared()) { 848 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 849 if (_deallocate_list == NULL) { 850 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, mtClass); 851 } 852 _deallocate_list->append_if_missing(m); 853 log_debug(class, loader, data)("deallocate added for %s", m->print_value_string()); 854 ClassLoaderDataGraph::set_should_clean_deallocate_lists(); 855 } 856 } 857 858 // Deallocate free metadata on the free list. How useful the PermGen was! 859 void ClassLoaderData::free_deallocate_list() { 860 // This must be called at a safepoint because it depends on metadata walking at 861 // safepoint cleanup time. 862 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 863 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading"); 864 if (_deallocate_list == NULL) { 865 return; 866 } 867 // Go backwards because this removes entries that are freed. 868 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 869 Metadata* m = _deallocate_list->at(i); 870 if (!m->on_stack()) { 871 _deallocate_list->remove_at(i); 872 // There are only three types of metadata that we deallocate directly. 873 // Cast them so they can be used by the template function. 874 if (m->is_method()) { 875 MetadataFactory::free_metadata(this, (Method*)m); 876 } else if (m->is_constantPool()) { 877 MetadataFactory::free_metadata(this, (ConstantPool*)m); 878 } else if (m->is_klass()) { 879 if (!((Klass*)m)->is_inline_klass()) { 880 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 881 } else { 882 MetadataFactory::free_metadata(this, (InlineKlass*)m); 883 } 884 } else { 885 ShouldNotReachHere(); 886 } 887 } else { 888 // Metadata is alive. 889 // If scratch_class is on stack then it shouldn't be on this list! 890 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 891 "scratch classes on this list should be dead"); 892 // Also should assert that other metadata on the list was found in handles. 893 // Some cleaning remains. 894 ClassLoaderDataGraph::set_should_clean_deallocate_lists(); 895 } 896 } 897 } 898 899 // This is distinct from free_deallocate_list. For class loader data that are 900 // unloading, this frees the C heap memory for items on the list, and unlinks 901 // scratch or error classes so that unloading events aren't triggered for these 902 // classes. The metadata is removed with the unloading metaspace. 903 // There isn't C heap memory allocated for methods, so nothing is done for them. 904 void ClassLoaderData::free_deallocate_list_C_heap_structures() { 905 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 906 assert(is_unloading(), "only called for ClassLoaderData that are unloading"); 907 if (_deallocate_list == NULL) { 908 return; 909 } 910 // Go backwards because this removes entries that are freed. 911 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 912 Metadata* m = _deallocate_list->at(i); 913 _deallocate_list->remove_at(i); 914 if (m->is_constantPool()) { 915 ((ConstantPool*)m)->release_C_heap_structures(); 916 } else if (m->is_klass()) { 917 InstanceKlass* ik = (InstanceKlass*)m; 918 // also releases ik->constants() C heap memory 919 ik->release_C_heap_structures(); 920 // Remove the class so unloading events aren't triggered for 921 // this class (scratch or error class) in do_unloading(). 922 remove_class(ik); 923 // But still have to remove it from the dumptime_table. 924 SystemDictionaryShared::handle_class_unloading(ik); 925 } 926 } 927 } 928 929 // Caller needs ResourceMark 930 // If the class loader's _name has not been explicitly set, the class loader's 931 // qualified class name is returned. 932 const char* ClassLoaderData::loader_name() const { 933 if (_class_loader_klass == NULL) { 934 return BOOTSTRAP_LOADER_NAME; 935 } else if (_name != NULL) { 936 return _name->as_C_string(); 937 } else { 938 return _class_loader_klass->external_name(); 939 } 940 } 941 942 // Caller needs ResourceMark 943 // Format of the _name_and_id is as follows: 944 // If the defining loader has a name explicitly set then '<loader-name>' @<id> 945 // If the defining loader has no name then <qualified-class-name> @<id> 946 // If built-in loader, then omit '@<id>' as there is only one instance. 947 const char* ClassLoaderData::loader_name_and_id() const { 948 if (_class_loader_klass == NULL) { 949 return "'" BOOTSTRAP_LOADER_NAME "'"; 950 } else if (_name_and_id != NULL) { 951 return _name_and_id->as_C_string(); 952 } else { 953 // May be called in a race before _name_and_id is initialized. 954 return _class_loader_klass->external_name(); 955 } 956 } 957 958 void ClassLoaderData::print_value_on(outputStream* out) const { 959 if (!is_unloading() && class_loader() != NULL) { 960 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this)); 961 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance 962 } else { 963 // loader data: 0xsomeaddr of 'bootstrap' 964 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id()); 965 } 966 if (_has_class_mirror_holder) { 967 out->print(" has a class holder"); 968 } 969 } 970 971 void ClassLoaderData::print_value() const { print_value_on(tty); } 972 973 #ifndef PRODUCT 974 class PrintKlassClosure: public KlassClosure { 975 outputStream* _out; 976 public: 977 PrintKlassClosure(outputStream* out): _out(out) { } 978 979 void do_klass(Klass* k) { 980 ResourceMark rm; 981 _out->print("%s,", k->external_name()); 982 } 983 }; 984 985 void ClassLoaderData::print_on(outputStream* out) const { 986 ResourceMark rm; 987 out->print_cr("ClassLoaderData(" INTPTR_FORMAT ")", p2i(this)); 988 out->print_cr(" - name %s", loader_name_and_id()); 989 if (!_holder.is_null()) { 990 out->print (" - holder "); 991 _holder.print_on(out); 992 out->print_cr(""); 993 } 994 out->print_cr(" - class loader " INTPTR_FORMAT, p2i(_class_loader.ptr_raw())); 995 out->print_cr(" - metaspace " INTPTR_FORMAT, p2i(_metaspace)); 996 out->print_cr(" - unloading %s", _unloading ? "true" : "false"); 997 out->print_cr(" - class mirror holder %s", _has_class_mirror_holder ? "true" : "false"); 998 out->print_cr(" - modified oops %s", _modified_oops ? "true" : "false"); 999 out->print_cr(" - keep alive %d", _keep_alive); 1000 out->print (" - claim "); 1001 switch(_claim) { 1002 case _claim_none: out->print_cr("none"); break; 1003 case _claim_finalizable: out->print_cr("finalizable"); break; 1004 case _claim_strong: out->print_cr("strong"); break; 1005 case _claim_other: out->print_cr("other"); break; 1006 case _claim_other | _claim_finalizable: out->print_cr("other and finalizable"); break; 1007 case _claim_other | _claim_strong: out->print_cr("other and strong"); break; 1008 default: ShouldNotReachHere(); 1009 } 1010 out->print_cr(" - handles %d", _handles.count()); 1011 out->print_cr(" - dependency count %d", _dependency_count); 1012 out->print (" - klasses {"); 1013 PrintKlassClosure closure(out); 1014 ((ClassLoaderData*)this)->classes_do(&closure); 1015 out->print_cr(" }"); 1016 out->print_cr(" - packages " INTPTR_FORMAT, p2i(_packages)); 1017 out->print_cr(" - module " INTPTR_FORMAT, p2i(_modules)); 1018 out->print_cr(" - unnamed module " INTPTR_FORMAT, p2i(_unnamed_module)); 1019 out->print_cr(" - dictionary " INTPTR_FORMAT, p2i(_dictionary)); 1020 if (_jmethod_ids != NULL) { 1021 out->print (" - jmethod count "); 1022 Method::print_jmethod_ids_count(this, out); 1023 out->print_cr(""); 1024 } 1025 out->print_cr(" - deallocate list " INTPTR_FORMAT, p2i(_deallocate_list)); 1026 out->print_cr(" - next CLD " INTPTR_FORMAT, p2i(_next)); 1027 } 1028 #endif // PRODUCT 1029 1030 void ClassLoaderData::print() const { print_on(tty); } 1031 1032 void ClassLoaderData::verify() { 1033 assert_locked_or_safepoint(_metaspace_lock); 1034 oop cl = class_loader(); 1035 1036 guarantee(this == class_loader_data(cl) || has_class_mirror_holder(), "Must be the same"); 1037 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || has_class_mirror_holder(), "must be"); 1038 1039 // Verify the integrity of the allocated space. 1040 #ifdef ASSERT 1041 if (metaspace_or_null() != NULL) { 1042 metaspace_or_null()->verify(); 1043 } 1044 #endif 1045 1046 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 1047 guarantee(k->class_loader_data() == this, "Must be the same"); 1048 k->verify(); 1049 assert(k != k->next_link(), "no loops!"); 1050 } 1051 } 1052 1053 bool ClassLoaderData::contains_klass(Klass* klass) { 1054 // Lock-free access requires load_acquire 1055 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) { 1056 if (k == klass) return true; 1057 } 1058 return false; 1059 }