1 /* 2 * Copyright (c) 2012, 2016, 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.hpp" 51 #include "classfile/classLoaderData.inline.hpp" 52 #include "classfile/javaClasses.hpp" 53 #include "classfile/metadataOnStackMark.hpp" 54 #include "classfile/moduleEntry.hpp" 55 #include "classfile/packageEntry.hpp" 56 #include "classfile/systemDictionary.hpp" 57 #include "code/codeCache.hpp" 58 #include "gc/shared/gcLocker.hpp" 59 #include "logging/log.hpp" 60 #include "memory/metadataFactory.hpp" 61 #include "memory/metaspaceShared.hpp" 62 #include "memory/oopFactory.hpp" 63 #include "memory/resourceArea.hpp" 64 #include "oops/objArrayOop.inline.hpp" 65 #include "oops/oop.inline.hpp" 66 #include "runtime/atomic.hpp" 67 #include "runtime/javaCalls.hpp" 68 #include "runtime/jniHandles.hpp" 69 #include "runtime/mutex.hpp" 70 #include "runtime/orderAccess.hpp" 71 #include "runtime/safepoint.hpp" 72 #include "runtime/synchronizer.hpp" 73 #include "utilities/growableArray.hpp" 74 #include "utilities/macros.hpp" 75 #include "utilities/ostream.hpp" 76 #if INCLUDE_TRACE 77 #include "trace/tracing.hpp" 78 #endif 79 80 // helper function to avoid in-line casts 81 template <typename T> static T* load_ptr_acquire(T* volatile *p) { 82 return static_cast<T*>(OrderAccess::load_ptr_acquire(p)); 83 } 84 85 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL; 86 87 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) : 88 _class_loader(h_class_loader()), 89 _is_anonymous(is_anonymous), 90 // An anonymous class loader data doesn't have anything to keep 91 // it from being unloaded during parsing of the anonymous class. 92 // The null-class-loader should always be kept alive. 93 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0), 94 _metaspace(NULL), _unloading(false), _klasses(NULL), 95 _modules(NULL), _packages(NULL), 96 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL), 97 _next(NULL), _dependencies(dependencies), 98 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true, 99 Monitor::_safepoint_check_never)) { 100 TRACE_INIT_ID(this); 101 } 102 103 void ClassLoaderData::init_dependencies(TRAPS) { 104 assert(!Universe::is_fully_initialized(), "should only be called when initializing"); 105 assert(is_the_null_class_loader_data(), "should only call this for the null class loader"); 106 _dependencies.init(CHECK); 107 } 108 109 void ClassLoaderData::Dependencies::init(TRAPS) { 110 // Create empty dependencies array to add to. CMS requires this to be 111 // an oop so that it can track additions via card marks. We think. 112 _list_head = oopFactory::new_objectArray(2, CHECK); 113 } 114 115 bool ClassLoaderData::claim() { 116 if (_claimed == 1) { 117 return false; 118 } 119 120 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0; 121 } 122 123 // Anonymous classes have their own ClassLoaderData that is marked to keep alive 124 // while the class is being parsed, and if the class appears on the module fixup list. 125 // Due to the uniqueness that no other class shares the anonymous class' name or 126 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while 127 // it is being defined, therefore _keep_alive is not volatile or atomic. 128 void ClassLoaderData::inc_keep_alive() { 129 if (is_anonymous()) { 130 assert(_keep_alive >= 0, "Invalid keep alive increment count"); 131 _keep_alive++; 132 } 133 } 134 135 void ClassLoaderData::dec_keep_alive() { 136 if (is_anonymous()) { 137 assert(_keep_alive > 0, "Invalid keep alive decrement count"); 138 _keep_alive--; 139 } 140 } 141 142 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 143 if (must_claim && !claim()) { 144 return; 145 } 146 147 f->do_oop(&_class_loader); 148 _dependencies.oops_do(f); 149 if (_handles != NULL) { 150 _handles->oops_do(f); 151 } 152 if (klass_closure != NULL) { 153 classes_do(klass_closure); 154 } 155 } 156 157 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) { 158 f->do_oop((oop*)&_list_head); 159 } 160 161 void ClassLoaderData::classes_do(KlassClosure* klass_closure) { 162 // Lock-free access requires load_ptr_acquire 163 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 164 klass_closure->do_klass(k); 165 assert(k != k->next_link(), "no loops!"); 166 } 167 } 168 169 void ClassLoaderData::classes_do(void f(Klass * const)) { 170 // Lock-free access requires load_ptr_acquire 171 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 172 f(k); 173 assert(k != k->next_link(), "no loops!"); 174 } 175 } 176 177 void ClassLoaderData::methods_do(void f(Method*)) { 178 // Lock-free access requires load_ptr_acquire 179 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 180 if (k->is_instance_klass()) { 181 InstanceKlass::cast(k)->methods_do(f); 182 } 183 } 184 } 185 186 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) { 187 // Lock to avoid classes being modified/added/removed during iteration 188 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 189 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 190 // Do not filter ArrayKlass oops here... 191 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) { 192 klass_closure->do_klass(k); 193 } 194 } 195 } 196 197 void ClassLoaderData::classes_do(void f(InstanceKlass*)) { 198 // Lock-free access requires load_ptr_acquire 199 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 200 if (k->is_instance_klass()) { 201 f(InstanceKlass::cast(k)); 202 } 203 assert(k != k->next_link(), "no loops!"); 204 } 205 } 206 207 void ClassLoaderData::modules_do(void f(ModuleEntry*)) { 208 assert_locked_or_safepoint(Module_lock); 209 if (_modules != NULL) { 210 for (int i = 0; i < _modules->table_size(); i++) { 211 for (ModuleEntry* entry = _modules->bucket(i); 212 entry != NULL; 213 entry = entry->next()) { 214 f(entry); 215 } 216 } 217 } 218 } 219 220 void ClassLoaderData::packages_do(void f(PackageEntry*)) { 221 // Lock-free access requires load_ptr_acquire 222 PackageEntryTable* packages = load_ptr_acquire(&_packages); 223 if (packages != NULL) { 224 for (int i = 0; i < packages->table_size(); i++) { 225 for (PackageEntry* entry = packages->bucket(i); 226 entry != NULL; 227 entry = entry->next()) { 228 f(entry); 229 } 230 } 231 } 232 } 233 234 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) { 235 assert(k != NULL, "invariant"); 236 237 ClassLoaderData * const from_cld = this; 238 ClassLoaderData * const to_cld = k->class_loader_data(); 239 240 // Dependency to the null class loader data doesn't need to be recorded 241 // because the null class loader data never goes away. 242 if (to_cld->is_the_null_class_loader_data()) { 243 return; 244 } 245 246 oop to; 247 if (to_cld->is_anonymous()) { 248 // Anonymous class dependencies are through the mirror. 249 to = k->java_mirror(); 250 } else { 251 to = to_cld->class_loader(); 252 253 // If from_cld is anonymous, even if it's class_loader is a parent of 'to' 254 // we still have to add it. The class_loader won't keep from_cld alive. 255 if (!from_cld->is_anonymous()) { 256 // Check that this dependency isn't from the same or parent class_loader 257 oop from = from_cld->class_loader(); 258 259 oop curr = from; 260 while (curr != NULL) { 261 if (curr == to) { 262 return; // this class loader is in the parent list, no need to add it. 263 } 264 curr = java_lang_ClassLoader::parent(curr); 265 } 266 } 267 } 268 269 // It's a dependency we won't find through GC, add it. This is relatively rare 270 // Must handle over GC point. 271 Handle dependency(THREAD, to); 272 from_cld->_dependencies.add(dependency, CHECK); 273 } 274 275 276 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) { 277 // Check first if this dependency is already in the list. 278 // Save a pointer to the last to add to under the lock. 279 objArrayOop ok = _list_head; 280 objArrayOop last = NULL; 281 while (ok != NULL) { 282 last = ok; 283 if (ok->obj_at(0) == dependency()) { 284 // Don't need to add it 285 return; 286 } 287 ok = (objArrayOop)ok->obj_at(1); 288 } 289 290 // Must handle over GC points 291 assert (last != NULL, "dependencies should be initialized"); 292 objArrayHandle last_handle(THREAD, last); 293 294 // Create a new dependency node with fields for (class_loader or mirror, next) 295 objArrayOop deps = oopFactory::new_objectArray(2, CHECK); 296 deps->obj_at_put(0, dependency()); 297 298 // Must handle over GC points 299 objArrayHandle new_dependency(THREAD, deps); 300 301 // Add the dependency under lock 302 locked_add(last_handle, new_dependency, THREAD); 303 } 304 305 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle, 306 objArrayHandle new_dependency, 307 Thread* THREAD) { 308 309 // Have to lock and put the new dependency on the end of the dependency 310 // array so the card mark for CMS sees that this dependency is new. 311 // Can probably do this lock free with some effort. 312 ObjectLocker ol(Handle(THREAD, _list_head), THREAD); 313 314 oop loader_or_mirror = new_dependency->obj_at(0); 315 316 // Since the dependencies are only added, add to the end. 317 objArrayOop end = last_handle(); 318 objArrayOop last = NULL; 319 while (end != NULL) { 320 last = end; 321 // check again if another thread added it to the end. 322 if (end->obj_at(0) == loader_or_mirror) { 323 // Don't need to add it 324 return; 325 } 326 end = (objArrayOop)end->obj_at(1); 327 } 328 assert (last != NULL, "dependencies should be initialized"); 329 // fill in the first element with the oop in new_dependency. 330 if (last->obj_at(0) == NULL) { 331 last->obj_at_put(0, new_dependency->obj_at(0)); 332 } else { 333 last->obj_at_put(1, new_dependency()); 334 } 335 } 336 337 void ClassLoaderDataGraph::clear_claimed_marks() { 338 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 339 cld->clear_claimed(); 340 } 341 } 342 343 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) { 344 { 345 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 346 Klass* old_value = _klasses; 347 k->set_next_link(old_value); 348 // Link the new item into the list, making sure the linked class is stable 349 // since the list can be walked without a lock 350 OrderAccess::release_store_ptr(&_klasses, k); 351 } 352 353 if (publicize && k->class_loader_data() != NULL) { 354 ResourceMark rm; 355 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: " 356 PTR_FORMAT " loader: " PTR_FORMAT " %s", 357 p2i(k), 358 k->external_name(), 359 p2i(k->class_loader_data()), 360 p2i((void *)k->class_loader()), 361 loader_name()); 362 } 363 } 364 365 // Remove a klass from the _klasses list for scratch_class during redefinition 366 // or parsed class in the case of an error. 367 void ClassLoaderData::remove_class(Klass* scratch_class) { 368 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 369 Klass* prev = NULL; 370 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 371 if (k == scratch_class) { 372 if (prev == NULL) { 373 _klasses = k->next_link(); 374 } else { 375 Klass* next = k->next_link(); 376 prev->set_next_link(next); 377 } 378 return; 379 } 380 prev = k; 381 assert(k != k->next_link(), "no loops!"); 382 } 383 ShouldNotReachHere(); // should have found this class!! 384 } 385 386 void ClassLoaderData::unload() { 387 _unloading = true; 388 389 // Tell serviceability tools these classes are unloading 390 classes_do(InstanceKlass::notify_unload_class); 391 392 if (log_is_enabled(Debug, class, loader, data)) { 393 ResourceMark rm; 394 outputStream* log = Log(class, loader, data)::debug_stream(); 395 log->print(": unload loader data " INTPTR_FORMAT, p2i(this)); 396 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()), 397 loader_name()); 398 if (is_anonymous()) { 399 log->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses)); 400 } 401 log->cr(); 402 } 403 404 // In some rare cases items added to this list will not be freed elsewhere. 405 // To keep it simple, just free everything in it here. 406 free_deallocate_list(); 407 } 408 409 PackageEntryTable* ClassLoaderData::packages() { 410 // Lazily create the package entry table at first request. 411 // Lock-free access requires load_ptr_acquire. 412 PackageEntryTable* packages = load_ptr_acquire(&_packages); 413 if (packages == NULL) { 414 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 415 // Check if _packages got allocated while we were waiting for this lock. 416 if ((packages = _packages) == NULL) { 417 packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size); 418 // Ensure _packages is stable, since it is examined without a lock 419 OrderAccess::release_store_ptr(&_packages, packages); 420 } 421 } 422 return packages; 423 } 424 425 ModuleEntryTable* ClassLoaderData::modules() { 426 // Lazily create the module entry table at first request. 427 // Lock-free access requires load_ptr_acquire. 428 ModuleEntryTable* modules = load_ptr_acquire(&_modules); 429 if (modules == NULL) { 430 MutexLocker m1(Module_lock); 431 // Check if _modules got allocated while we were waiting for this lock. 432 if ((modules = _modules) == NULL) { 433 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size); 434 // Each loader has one unnamed module entry. Create it before 435 // any classes, loaded by this loader, are defined in case 436 // they end up being defined in loader's unnamed module. 437 modules->create_unnamed_module(this); 438 439 { 440 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag); 441 // Ensure _modules is stable, since it is examined without a lock 442 OrderAccess::release_store_ptr(&_modules, modules); 443 } 444 } 445 } 446 return modules; 447 } 448 449 oop ClassLoaderData::keep_alive_object() const { 450 assert_locked_or_safepoint(_metaspace_lock); 451 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive"); 452 return is_anonymous() ? _klasses->java_mirror() : class_loader(); 453 } 454 455 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const { 456 bool alive = keep_alive() // null class loader and incomplete anonymous klasses. 457 || is_alive_closure->do_object_b(keep_alive_object()); 458 459 return alive; 460 } 461 462 463 ClassLoaderData::~ClassLoaderData() { 464 // Release C heap structures for all the classes. 465 classes_do(InstanceKlass::release_C_heap_structures); 466 467 // Release C heap allocated hashtable for all the packages. 468 if (_packages != NULL) { 469 // Destroy the table itself 470 delete _packages; 471 _packages = NULL; 472 } 473 474 // Release C heap allocated hashtable for all the modules. 475 if (_modules != NULL) { 476 // Destroy the table itself 477 delete _modules; 478 _modules = NULL; 479 } 480 481 // release the metaspace 482 Metaspace *m = _metaspace; 483 if (m != NULL) { 484 _metaspace = NULL; 485 delete m; 486 } 487 // release the handles 488 if (_handles != NULL) { 489 JNIHandleBlock::release_block(_handles); 490 _handles = NULL; 491 } 492 493 // Clear all the JNI handles for methods 494 // These aren't deallocated and are going to look like a leak, but that's 495 // needed because we can't really get rid of jmethodIDs because we don't 496 // know when native code is going to stop using them. The spec says that 497 // they're "invalid" but existing programs likely rely on their being 498 // NULL after class unloading. 499 if (_jmethod_ids != NULL) { 500 Method::clear_jmethod_ids(this); 501 } 502 // Delete lock 503 delete _metaspace_lock; 504 505 // Delete free list 506 if (_deallocate_list != NULL) { 507 delete _deallocate_list; 508 } 509 } 510 511 // Returns true if this class loader data is for the system class loader. 512 bool ClassLoaderData::is_system_class_loader_data() const { 513 return SystemDictionary::is_system_class_loader(class_loader()); 514 } 515 516 // Returns true if this class loader data is for the platform class loader. 517 bool ClassLoaderData::is_platform_class_loader_data() const { 518 return SystemDictionary::is_platform_class_loader(class_loader()); 519 } 520 521 // Returns true if this class loader data is one of the 3 builtin 522 // (boot, application/system or platform) class loaders. Note, the 523 // builtin loaders are not freed by a GC. 524 bool ClassLoaderData::is_builtin_class_loader_data() const { 525 Handle classLoaderHandle = class_loader(); 526 return (is_the_null_class_loader_data() || 527 SystemDictionary::is_system_class_loader(classLoaderHandle) || 528 SystemDictionary::is_platform_class_loader(classLoaderHandle)); 529 } 530 531 Metaspace* ClassLoaderData::metaspace_non_null() { 532 assert(!DumpSharedSpaces, "wrong metaspace!"); 533 // If the metaspace has not been allocated, create a new one. Might want 534 // to create smaller arena for Reflection class loaders also. 535 // The reason for the delayed allocation is because some class loaders are 536 // simply for delegating with no metadata of their own. 537 // Lock-free access requires load_ptr_acquire. 538 Metaspace* metaspace = load_ptr_acquire(&_metaspace); 539 if (metaspace == NULL) { 540 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag); 541 // Check if _metaspace got allocated while we were waiting for this lock. 542 if ((metaspace = _metaspace) == NULL) { 543 if (this == the_null_class_loader_data()) { 544 assert (class_loader() == NULL, "Must be"); 545 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType); 546 } else if (is_anonymous()) { 547 if (class_loader() != NULL) { 548 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name()); 549 } 550 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType); 551 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) { 552 if (class_loader() != NULL) { 553 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name()); 554 } 555 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType); 556 } else { 557 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType); 558 } 559 // Ensure _metaspace is stable, since it is examined without a lock 560 OrderAccess::release_store_ptr(&_metaspace, metaspace); 561 } 562 } 563 return metaspace; 564 } 565 566 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; } 567 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; } 568 569 jobject ClassLoaderData::add_handle(Handle h) { 570 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 571 if (handles() == NULL) { 572 set_handles(JNIHandleBlock::allocate_block()); 573 } 574 return handles()->allocate_handle(h()); 575 } 576 577 void ClassLoaderData::remove_handle(jobject h) { 578 _handles->release_handle(h); 579 } 580 581 // Add this metadata pointer to be freed when it's safe. This is only during 582 // class unloading because Handles might point to this metadata field. 583 void ClassLoaderData::add_to_deallocate_list(Metadata* m) { 584 // Metadata in shared region isn't deleted. 585 if (!m->is_shared()) { 586 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 587 if (_deallocate_list == NULL) { 588 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true); 589 } 590 _deallocate_list->append_if_missing(m); 591 } 592 } 593 594 // Deallocate free metadata on the free list. How useful the PermGen was! 595 void ClassLoaderData::free_deallocate_list() { 596 // Don't need lock, at safepoint 597 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 598 if (_deallocate_list == NULL) { 599 return; 600 } 601 // Go backwards because this removes entries that are freed. 602 for (int i = _deallocate_list->length() - 1; i >= 0; i--) { 603 Metadata* m = _deallocate_list->at(i); 604 if (!m->on_stack()) { 605 _deallocate_list->remove_at(i); 606 // There are only three types of metadata that we deallocate directly. 607 // Cast them so they can be used by the template function. 608 if (m->is_method()) { 609 MetadataFactory::free_metadata(this, (Method*)m); 610 } else if (m->is_constantPool()) { 611 MetadataFactory::free_metadata(this, (ConstantPool*)m); 612 } else if (m->is_klass()) { 613 MetadataFactory::free_metadata(this, (InstanceKlass*)m); 614 } else { 615 ShouldNotReachHere(); 616 } 617 } else { 618 // Metadata is alive. 619 // If scratch_class is on stack then it shouldn't be on this list! 620 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(), 621 "scratch classes on this list should be dead"); 622 // Also should assert that other metadata on the list was found in handles. 623 } 624 } 625 } 626 627 // These anonymous class loaders are to contain classes used for JSR292 628 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) { 629 // Add a new class loader data to the graph. 630 return ClassLoaderDataGraph::add(loader, true, THREAD); 631 } 632 633 const char* ClassLoaderData::loader_name() { 634 // Handles null class loader 635 return SystemDictionary::loader_name(class_loader()); 636 } 637 638 #ifndef PRODUCT 639 // Define to dump klasses 640 #undef CLD_DUMP_KLASSES 641 642 void ClassLoaderData::dump(outputStream * const out) { 643 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {", 644 p2i(this), p2i((void *)class_loader()), 645 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name()); 646 if (claimed()) out->print(" claimed "); 647 if (is_unloading()) out->print(" unloading "); 648 out->print(" handles " INTPTR_FORMAT, p2i(handles())); 649 out->cr(); 650 if (metaspace_or_null() != NULL) { 651 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null())); 652 metaspace_or_null()->dump(out); 653 } else { 654 out->print_cr("metaspace: NULL"); 655 } 656 657 #ifdef CLD_DUMP_KLASSES 658 if (Verbose) { 659 Klass* k = _klasses; 660 while (k != NULL) { 661 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(), 662 k->has_modified_oops(), k->has_accumulated_modified_oops()); 663 assert(k != k->next_link(), "no loops!"); 664 k = k->next_link(); 665 } 666 } 667 #endif // CLD_DUMP_KLASSES 668 #undef CLD_DUMP_KLASSES 669 if (_jmethod_ids != NULL) { 670 Method::print_jmethod_ids(this, out); 671 } 672 out->print_cr("}"); 673 } 674 #endif // PRODUCT 675 676 void ClassLoaderData::verify() { 677 assert_locked_or_safepoint(_metaspace_lock); 678 oop cl = class_loader(); 679 680 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same"); 681 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be"); 682 683 // Verify the integrity of the allocated space. 684 if (metaspace_or_null() != NULL) { 685 metaspace_or_null()->verify(); 686 } 687 688 for (Klass* k = _klasses; k != NULL; k = k->next_link()) { 689 guarantee(k->class_loader_data() == this, "Must be the same"); 690 k->verify(); 691 assert(k != k->next_link(), "no loops!"); 692 } 693 } 694 695 bool ClassLoaderData::contains_klass(Klass* klass) { 696 // Lock-free access requires load_ptr_acquire 697 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) { 698 if (k == klass) return true; 699 } 700 return false; 701 } 702 703 704 // GC root of class loader data created. 705 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 706 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 707 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 708 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 709 710 bool ClassLoaderDataGraph::_should_purge = false; 711 bool ClassLoaderDataGraph::_metaspace_oom = false; 712 713 // Add a new class loader data node to the list. Assign the newly created 714 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 715 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) { 716 // We need to allocate all the oops for the ClassLoaderData before allocating the 717 // actual ClassLoaderData object. 718 ClassLoaderData::Dependencies dependencies(CHECK_NULL); 719 720 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the 721 // ClassLoaderData in the graph since the CLD 722 // contains unhandled oops 723 724 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies); 725 726 727 if (!is_anonymous) { 728 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader()); 729 // First, Atomically set it 730 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL); 731 if (old != NULL) { 732 delete cld; 733 // Returns the data. 734 return old; 735 } 736 } 737 738 // We won the race, and therefore the task of adding the data to the list of 739 // class loader data 740 ClassLoaderData** list_head = &_head; 741 ClassLoaderData* next = _head; 742 743 do { 744 cld->set_next(next); 745 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next); 746 if (exchanged == next) { 747 if (log_is_enabled(Debug, class, loader, data)) { 748 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual 749 log_creation(loader, cld, CHECK_NULL); 750 } 751 return cld; 752 } 753 next = exchanged; 754 } while (true); 755 } 756 757 void ClassLoaderDataGraph::log_creation(Handle loader, ClassLoaderData* cld, TRAPS) { 758 Handle string; 759 if (loader.not_null()) { 760 // Include the result of loader.toString() in the output. This allows 761 // the user of the log to identify the class loader instance. 762 JavaValue result(T_OBJECT); 763 KlassHandle spec_klass(THREAD, SystemDictionary::ClassLoader_klass()); 764 JavaCalls::call_virtual(&result, 765 loader, 766 spec_klass, 767 vmSymbols::toString_name(), 768 vmSymbols::void_string_signature(), 769 CHECK); 770 assert(result.get_type() == T_OBJECT, "just checking"); 771 string = (oop)result.get_jobject(); 772 } 773 774 ResourceMark rm; 775 outputStream* log = Log(class, loader, data)::debug_stream(); 776 log->print("create class loader data " INTPTR_FORMAT, p2i(cld)); 777 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()), 778 cld->loader_name()); 779 780 if (string.not_null()) { 781 log->print(": "); 782 java_lang_String::print(string(), log); 783 } 784 log->cr(); 785 } 786 787 788 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 789 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 790 cld->oops_do(f, klass_closure, must_claim); 791 } 792 } 793 794 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 795 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 796 if (cld->keep_alive()) { 797 cld->oops_do(f, klass_closure, must_claim); 798 } 799 } 800 } 801 802 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) { 803 if (ClassUnloading) { 804 keep_alive_oops_do(f, klass_closure, must_claim); 805 } else { 806 oops_do(f, klass_closure, must_claim); 807 } 808 } 809 810 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 811 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) { 812 cl->do_cld(cld); 813 } 814 } 815 816 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) { 817 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 818 // Only walk the head until any clds not purged from prior unloading 819 // (CMS doesn't purge right away). 820 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 821 assert(cld->is_unloading(), "invariant"); 822 cl->do_cld(cld); 823 } 824 } 825 826 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 827 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 828 CLDClosure* closure = cld->keep_alive() ? strong : weak; 829 if (closure != NULL) { 830 closure->do_cld(cld); 831 } 832 } 833 } 834 835 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) { 836 roots_cld_do(cl, NULL); 837 } 838 839 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 840 if (ClassUnloading) { 841 keep_alive_cld_do(cl); 842 } else { 843 cld_do(cl); 844 } 845 } 846 847 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 848 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 849 cld->classes_do(klass_closure); 850 } 851 } 852 853 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 854 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 855 cld->classes_do(f); 856 } 857 } 858 859 void ClassLoaderDataGraph::methods_do(void f(Method*)) { 860 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 861 cld->methods_do(f); 862 } 863 } 864 865 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) { 866 assert_locked_or_safepoint(Module_lock); 867 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 868 cld->modules_do(f); 869 } 870 } 871 872 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) { 873 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 874 // Only walk the head until any clds not purged from prior unloading 875 // (CMS doesn't purge right away). 876 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 877 assert(cld->is_unloading(), "invariant"); 878 cld->modules_do(f); 879 } 880 } 881 882 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) { 883 assert_locked_or_safepoint(Module_lock); 884 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 885 cld->packages_do(f); 886 } 887 } 888 889 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) { 890 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 891 // Only walk the head until any clds not purged from prior unloading 892 // (CMS doesn't purge right away). 893 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 894 assert(cld->is_unloading(), "invariant"); 895 cld->packages_do(f); 896 } 897 } 898 899 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 900 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 901 cld->loaded_classes_do(klass_closure); 902 } 903 } 904 905 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 906 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 907 // Only walk the head until any clds not purged from prior unloading 908 // (CMS doesn't purge right away). 909 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 910 assert(cld->is_unloading(), "invariant"); 911 cld->classes_do(f); 912 } 913 } 914 915 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 916 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 917 918 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 919 920 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 921 ClassLoaderData* curr = _head; 922 while (curr != _saved_head) { 923 if (!curr->claimed()) { 924 array->push(curr); 925 926 if (log_is_enabled(Debug, class, loader, data)) { 927 outputStream* log = Log(class, loader, data)::debug_stream(); 928 log->print("found new CLD: "); 929 curr->print_value_on(log); 930 log->cr(); 931 } 932 } 933 934 curr = curr->_next; 935 } 936 937 return array; 938 } 939 940 bool ClassLoaderDataGraph::unload_list_contains(const void* x) { 941 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint"); 942 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) { 943 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) { 944 return true; 945 } 946 } 947 return false; 948 } 949 950 #ifndef PRODUCT 951 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 952 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 953 if (loader_data == data) { 954 return true; 955 } 956 } 957 958 return false; 959 } 960 #endif // PRODUCT 961 962 963 // Move class loader data from main list to the unloaded list for unloading 964 // and deallocation later. 965 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, 966 bool clean_previous_versions) { 967 968 ClassLoaderData* data = _head; 969 ClassLoaderData* prev = NULL; 970 bool seen_dead_loader = false; 971 972 // Mark metadata seen on the stack only so we can delete unneeded entries. 973 // Only walk all metadata, including the expensive code cache walk, for Full GC 974 // and only if class redefinition and if there's previous versions of 975 // Klasses to delete. 976 bool walk_all_metadata = clean_previous_versions && 977 JvmtiExport::has_redefined_a_class() && 978 InstanceKlass::has_previous_versions_and_reset(); 979 MetadataOnStackMark md_on_stack(walk_all_metadata); 980 981 // Save previous _unloading pointer for CMS which may add to unloading list before 982 // purging and we don't want to rewalk the previously unloaded class loader data. 983 _saved_unloading = _unloading; 984 985 data = _head; 986 while (data != NULL) { 987 if (data->is_alive(is_alive_closure)) { 988 // clean metaspace 989 if (walk_all_metadata) { 990 data->classes_do(InstanceKlass::purge_previous_versions); 991 } 992 data->free_deallocate_list(); 993 prev = data; 994 data = data->next(); 995 continue; 996 } 997 seen_dead_loader = true; 998 ClassLoaderData* dead = data; 999 dead->unload(); 1000 data = data->next(); 1001 // Remove from loader list. 1002 // This class loader data will no longer be found 1003 // in the ClassLoaderDataGraph. 1004 if (prev != NULL) { 1005 prev->set_next(data); 1006 } else { 1007 assert(dead == _head, "sanity check"); 1008 _head = data; 1009 } 1010 dead->set_next(_unloading); 1011 _unloading = dead; 1012 } 1013 1014 if (seen_dead_loader) { 1015 // Walk a ModuleEntry's reads and a PackageEntry's exports lists 1016 // to determine if there are modules on those lists that are now 1017 // dead and should be removed. A module's life cycle is equivalent 1018 // to its defining class loader's life cycle. Since a module is 1019 // considered dead if its class loader is dead, these walks must 1020 // occur after each class loader's aliveness is determined. 1021 data = _head; 1022 while (data != NULL) { 1023 if (data->packages_defined()) { 1024 data->packages()->purge_all_package_exports(); 1025 } 1026 if (data->modules_defined()) { 1027 data->modules()->purge_all_module_reads(); 1028 } 1029 data = data->next(); 1030 } 1031 1032 post_class_unload_events(); 1033 } 1034 1035 return seen_dead_loader; 1036 } 1037 1038 void ClassLoaderDataGraph::purge() { 1039 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1040 ClassLoaderData* list = _unloading; 1041 _unloading = NULL; 1042 ClassLoaderData* next = list; 1043 bool classes_unloaded = false; 1044 while (next != NULL) { 1045 ClassLoaderData* purge_me = next; 1046 next = purge_me->next(); 1047 delete purge_me; 1048 classes_unloaded = true; 1049 } 1050 if (classes_unloaded) { 1051 Metaspace::purge(); 1052 set_metaspace_oom(false); 1053 } 1054 } 1055 1056 void ClassLoaderDataGraph::post_class_unload_events() { 1057 #if INCLUDE_TRACE 1058 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 1059 if (Tracing::enabled()) { 1060 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) { 1061 assert(_unloading != NULL, "need class loader data unload list!"); 1062 _class_unload_time = Ticks::now(); 1063 classes_unloading_do(&class_unload_event); 1064 } 1065 Tracing::on_unloading_classes(); 1066 } 1067 #endif 1068 } 1069 1070 // CDS support 1071 1072 // Global metaspaces for writing information to the shared archive. When 1073 // application CDS is supported, we may need one per metaspace, so this 1074 // sort of looks like it. 1075 Metaspace* ClassLoaderData::_ro_metaspace = NULL; 1076 Metaspace* ClassLoaderData::_rw_metaspace = NULL; 1077 static bool _shared_metaspaces_initialized = false; 1078 1079 // Initialize shared metaspaces (change to call from somewhere not lazily) 1080 void ClassLoaderData::initialize_shared_metaspaces() { 1081 assert(DumpSharedSpaces, "only use this for dumping shared spaces"); 1082 assert(this == ClassLoaderData::the_null_class_loader_data(), 1083 "only supported for null loader data for now"); 1084 assert (!_shared_metaspaces_initialized, "only initialize once"); 1085 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag); 1086 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType); 1087 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType); 1088 _shared_metaspaces_initialized = true; 1089 } 1090 1091 Metaspace* ClassLoaderData::ro_metaspace() { 1092 assert(_ro_metaspace != NULL, "should already be initialized"); 1093 return _ro_metaspace; 1094 } 1095 1096 Metaspace* ClassLoaderData::rw_metaspace() { 1097 assert(_rw_metaspace != NULL, "should already be initialized"); 1098 return _rw_metaspace; 1099 } 1100 1101 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 1102 : _next_klass(NULL) { 1103 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 1104 Klass* klass = NULL; 1105 1106 // Find the first klass in the CLDG. 1107 while (cld != NULL) { 1108 assert_locked_or_safepoint(cld->metaspace_lock()); 1109 klass = cld->_klasses; 1110 if (klass != NULL) { 1111 _next_klass = klass; 1112 return; 1113 } 1114 cld = cld->next(); 1115 } 1116 } 1117 1118 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 1119 Klass* next = klass->next_link(); 1120 if (next != NULL) { 1121 return next; 1122 } 1123 1124 // No more klasses in the current CLD. Time to find a new CLD. 1125 ClassLoaderData* cld = klass->class_loader_data(); 1126 assert_locked_or_safepoint(cld->metaspace_lock()); 1127 while (next == NULL) { 1128 cld = cld->next(); 1129 if (cld == NULL) { 1130 break; 1131 } 1132 next = cld->_klasses; 1133 } 1134 1135 return next; 1136 } 1137 1138 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 1139 Klass* head = _next_klass; 1140 1141 while (head != NULL) { 1142 Klass* next = next_klass_in_cldg(head); 1143 1144 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head); 1145 1146 if (old_head == head) { 1147 return head; // Won the CAS. 1148 } 1149 1150 head = old_head; 1151 } 1152 1153 // Nothing more for the iterator to hand out. 1154 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); 1155 return NULL; 1156 } 1157 1158 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 1159 _data = ClassLoaderDataGraph::_head; 1160 } 1161 1162 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 1163 1164 #ifndef PRODUCT 1165 // callable from debugger 1166 extern "C" int print_loader_data_graph() { 1167 ClassLoaderDataGraph::dump_on(tty); 1168 return 0; 1169 } 1170 1171 void ClassLoaderDataGraph::verify() { 1172 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1173 data->verify(); 1174 } 1175 } 1176 1177 void ClassLoaderDataGraph::dump_on(outputStream * const out) { 1178 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 1179 data->dump(out); 1180 } 1181 MetaspaceAux::dump(out); 1182 } 1183 #endif // PRODUCT 1184 1185 void ClassLoaderData::print_value_on(outputStream* out) const { 1186 if (class_loader() == NULL) { 1187 out->print("NULL class_loader"); 1188 } else { 1189 out->print("class loader " INTPTR_FORMAT " ", p2i(this)); 1190 class_loader()->print_value_on(out); 1191 } 1192 } 1193 1194 #if INCLUDE_TRACE 1195 1196 Ticks ClassLoaderDataGraph::_class_unload_time; 1197 1198 void ClassLoaderDataGraph::class_unload_event(Klass* const k) { 1199 assert(k != NULL, "invariant"); 1200 1201 // post class unload event 1202 EventClassUnload event(UNTIMED); 1203 event.set_endtime(_class_unload_time); 1204 event.set_unloadedClass(k); 1205 event.set_definingClassLoader(k->class_loader_data()); 1206 event.commit(); 1207 } 1208 1209 #endif // INCLUDE_TRACE