1 /* 2 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoaderDataGraph.inline.hpp" 27 #include "classfile/dictionary.hpp" 28 #include "classfile/javaClasses.hpp" 29 #include "classfile/metadataOnStackMark.hpp" 30 #include "classfile/moduleEntry.hpp" 31 #include "classfile/packageEntry.hpp" 32 #include "logging/log.hpp" 33 #include "logging/logStream.hpp" 34 #include "memory/allocation.inline.hpp" 35 #include "memory/metaspace.hpp" 36 #include "memory/resourceArea.hpp" 37 #include "runtime/atomic.hpp" 38 #include "runtime/handles.inline.hpp" 39 #include "runtime/mutex.hpp" 40 #include "runtime/safepoint.hpp" 41 #include "runtime/safepointVerifiers.hpp" 42 #include "utilities/growableArray.hpp" 43 #include "utilities/macros.hpp" 44 #include "utilities/ostream.hpp" 45 46 volatile size_t ClassLoaderDataGraph::_num_array_classes = 0; 47 volatile size_t ClassLoaderDataGraph::_num_instance_classes = 0; 48 49 void ClassLoaderDataGraph::clear_claimed_marks() { 50 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 51 cld->clear_claim(); 52 } 53 } 54 55 // Class iterator used by the compiler. It gets some number of classes at 56 // a safepoint to decay invocation counters on the methods. 57 class ClassLoaderDataGraphKlassIteratorStatic { 58 ClassLoaderData* _current_loader_data; 59 Klass* _current_class_entry; 60 public: 61 62 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {} 63 64 InstanceKlass* try_get_next_class() { 65 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 66 size_t max_classes = ClassLoaderDataGraph::num_instance_classes(); 67 assert(max_classes > 0, "should not be called with no instance classes"); 68 for (size_t i = 0; i < max_classes; ) { 69 70 if (_current_class_entry != NULL) { 71 Klass* k = _current_class_entry; 72 _current_class_entry = _current_class_entry->next_link(); 73 74 if (k->is_instance_klass()) { 75 InstanceKlass* ik = InstanceKlass::cast(k); 76 i++; // count all instance classes found 77 // Not yet loaded classes are counted in max_classes 78 // but only return loaded classes. 79 if (ik->is_loaded()) { 80 return ik; 81 } 82 } 83 } else { 84 // Go to next CLD 85 if (_current_loader_data != NULL) { 86 _current_loader_data = _current_loader_data->next(); 87 } 88 // Start at the beginning 89 if (_current_loader_data == NULL) { 90 _current_loader_data = ClassLoaderDataGraph::_head; 91 } 92 93 _current_class_entry = _current_loader_data->klasses(); 94 } 95 } 96 // Should never be reached unless all instance classes have failed or are not fully loaded. 97 // Caller handles NULL. 98 return NULL; 99 } 100 101 // If the current class for the static iterator is a class being unloaded or 102 // deallocated, adjust the current class. 103 void adjust_saved_class(ClassLoaderData* cld) { 104 if (_current_loader_data == cld) { 105 _current_loader_data = cld->next(); 106 if (_current_loader_data != NULL) { 107 _current_class_entry = _current_loader_data->klasses(); 108 } // else try_get_next_class will start at the head 109 } 110 } 111 112 void adjust_saved_class(Klass* klass) { 113 if (_current_class_entry == klass) { 114 _current_class_entry = klass->next_link(); 115 } 116 } 117 }; 118 119 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator; 120 121 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() { 122 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint"); 123 return static_klass_iterator.try_get_next_class(); 124 } 125 126 void ClassLoaderDataGraph::adjust_saved_class(ClassLoaderData* cld) { 127 return static_klass_iterator.adjust_saved_class(cld); 128 } 129 130 void ClassLoaderDataGraph::adjust_saved_class(Klass* klass) { 131 return static_klass_iterator.adjust_saved_class(klass); 132 } 133 134 void ClassLoaderDataGraph::clean_deallocate_lists(bool walk_previous_versions) { 135 assert(SafepointSynchronize::is_at_safepoint(), "must only be called at safepoint"); 136 uint loaders_processed = 0; 137 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 138 // is_alive check will be necessary for concurrent class unloading. 139 if (cld->is_alive()) { 140 // clean metaspace 141 if (walk_previous_versions) { 142 cld->classes_do(InstanceKlass::purge_previous_versions); 143 } 144 cld->free_deallocate_list(); 145 loaders_processed++; 146 } 147 } 148 log_debug(class, loader, data)("clean_deallocate_lists: loaders processed %u %s", 149 loaders_processed, walk_previous_versions ? "walk_previous_versions" : ""); 150 } 151 152 void ClassLoaderDataGraph::walk_metadata_and_clean_metaspaces() { 153 assert(SafepointSynchronize::is_at_safepoint(), "must only be called at safepoint"); 154 155 _should_clean_deallocate_lists = false; // assume everything gets cleaned 156 157 // Mark metadata seen on the stack so we can delete unreferenced entries. 158 // Walk all metadata, including the expensive code cache walk, only for class redefinition. 159 // The MetadataOnStackMark walk during redefinition saves previous versions if it finds old methods 160 // on the stack or in the code cache, so we only have to repeat the full walk if 161 // they were found at that time. 162 // TODO: have redefinition clean old methods out of the code cache. They still exist in some places. 163 bool walk_all_metadata = InstanceKlass::has_previous_versions_and_reset(); 164 165 MetadataOnStackMark md_on_stack(walk_all_metadata); 166 clean_deallocate_lists(walk_all_metadata); 167 } 168 169 // GC root of class loader data created. 170 ClassLoaderData* ClassLoaderDataGraph::_head = NULL; 171 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL; 172 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL; 173 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL; 174 175 bool ClassLoaderDataGraph::_should_purge = false; 176 bool ClassLoaderDataGraph::_should_clean_deallocate_lists = false; 177 bool ClassLoaderDataGraph::_safepoint_cleanup_needed = false; 178 bool ClassLoaderDataGraph::_metaspace_oom = false; 179 180 // Add a new class loader data node to the list. Assign the newly created 181 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field 182 ClassLoaderData* ClassLoaderDataGraph::add_to_graph(Handle loader, bool is_unsafe_anonymous) { 183 184 assert_lock_strong(ClassLoaderDataGraph_lock); 185 186 ClassLoaderData* cld; 187 188 // First check if another thread beat us to creating the CLD and installing 189 // it into the loader while we were waiting for the lock. 190 if (!is_unsafe_anonymous && loader.not_null()) { 191 cld = java_lang_ClassLoader::loader_data_acquire(loader()); 192 if (cld != NULL) { 193 return cld; 194 } 195 } 196 197 // We mustn't GC until we've installed the ClassLoaderData in the Graph since the CLD 198 // contains oops in _handles that must be walked. GC doesn't walk CLD from the 199 // loader oop in all collections, particularly young collections. 200 NoSafepointVerifier no_safepoints; 201 202 cld = new ClassLoaderData(loader, is_unsafe_anonymous); 203 204 // First install the new CLD to the Graph. 205 cld->set_next(_head); 206 _head = cld; 207 208 // Next associate with the class_loader. 209 if (!is_unsafe_anonymous) { 210 // Use OrderAccess, since readers need to get the loader_data only after 211 // it's added to the Graph 212 java_lang_ClassLoader::release_set_loader_data(loader(), cld); 213 } 214 215 // Lastly log, if requested 216 LogTarget(Trace, class, loader, data) lt; 217 if (lt.is_enabled()) { 218 ResourceMark rm; 219 LogStream ls(lt); 220 ls.print("create "); 221 cld->print_value_on(&ls); 222 ls.cr(); 223 } 224 return cld; 225 } 226 227 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_unsafe_anonymous) { 228 MutexLocker ml(ClassLoaderDataGraph_lock); 229 ClassLoaderData* loader_data = add_to_graph(loader, is_unsafe_anonymous); 230 return loader_data; 231 } 232 233 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) { 234 assert_locked_or_safepoint_weak(ClassLoaderDataGraph_lock); 235 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 236 cl->do_cld(cld); 237 } 238 } 239 240 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) { 241 assert_locked_or_safepoint_weak(ClassLoaderDataGraph_lock); 242 // Only walk the head until any clds not purged from prior unloading 243 // (CMS doesn't purge right away). 244 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 245 assert(cld->is_unloading(), "invariant"); 246 cl->do_cld(cld); 247 } 248 } 249 250 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) { 251 assert_locked_or_safepoint_weak(ClassLoaderDataGraph_lock); 252 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) { 253 CLDClosure* closure = cld->keep_alive() ? strong : weak; 254 if (closure != NULL) { 255 closure->do_cld(cld); 256 } 257 } 258 } 259 260 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) { 261 assert_locked_or_safepoint_weak(ClassLoaderDataGraph_lock); 262 if (ClassUnloading) { 263 roots_cld_do(cl, NULL); 264 } else { 265 cld_do(cl); 266 } 267 } 268 269 // Closure for locking and iterating through classes. 270 LockedClassesDo::LockedClassesDo(classes_do_func_t f) : _function(f) { 271 ClassLoaderDataGraph_lock->lock(); 272 } 273 274 LockedClassesDo::LockedClassesDo() : _function(NULL) { 275 // callers provide their own do_klass 276 ClassLoaderDataGraph_lock->lock(); 277 } 278 279 LockedClassesDo::~LockedClassesDo() { ClassLoaderDataGraph_lock->unlock(); } 280 281 282 // Iterating over the CLDG needs to be locked because 283 // unloading can remove entries concurrently soon. 284 class ClassLoaderDataGraphIterator : public StackObj { 285 ClassLoaderData* _next; 286 HandleMark _hm; // clean up handles when this is done. 287 Handle _holder; 288 Thread* _thread; 289 290 void hold_next() { 291 if (_next != NULL) { 292 _holder = Handle(_thread, _next->holder_phantom()); 293 } 294 } 295 public: 296 ClassLoaderDataGraphIterator() : _next(ClassLoaderDataGraph::_head) { 297 _thread = Thread::current(); 298 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 299 hold_next(); 300 } 301 302 bool repeat() const { 303 return _next != NULL; 304 } 305 306 ClassLoaderData* get_next() { 307 ClassLoaderData* next = _next; 308 if (_next != NULL) { 309 _next = _next->next(); 310 hold_next(); 311 } 312 return next; 313 } 314 }; 315 316 // These functions assume that the caller has locked the ClassLoaderDataGraph_lock 317 // if they are not calling the function from a safepoint. 318 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) { 319 ClassLoaderDataGraphIterator iter; 320 while (iter.repeat()) { 321 ClassLoaderData* cld = iter.get_next(); 322 cld->classes_do(klass_closure); 323 } 324 } 325 326 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) { 327 ClassLoaderDataGraphIterator iter; 328 while (iter.repeat()) { 329 ClassLoaderData* cld = iter.get_next(); 330 cld->classes_do(f); 331 } 332 } 333 334 void ClassLoaderDataGraph::methods_do(void f(Method*)) { 335 ClassLoaderDataGraphIterator iter; 336 while (iter.repeat()) { 337 ClassLoaderData* cld = iter.get_next(); 338 cld->methods_do(f); 339 } 340 } 341 342 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) { 343 assert_locked_or_safepoint(Module_lock); 344 ClassLoaderDataGraphIterator iter; 345 while (iter.repeat()) { 346 ClassLoaderData* cld = iter.get_next(); 347 cld->modules_do(f); 348 } 349 } 350 351 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) { 352 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 353 // Only walk the head until any clds not purged from prior unloading 354 // (CMS doesn't purge right away). 355 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 356 assert(cld->is_unloading(), "invariant"); 357 cld->modules_do(f); 358 } 359 } 360 361 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) { 362 assert_locked_or_safepoint(Module_lock); 363 ClassLoaderDataGraphIterator iter; 364 while (iter.repeat()) { 365 ClassLoaderData* cld = iter.get_next(); 366 cld->packages_do(f); 367 } 368 } 369 370 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) { 371 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 372 // Only walk the head until any clds not purged from prior unloading 373 // (CMS doesn't purge right away). 374 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 375 assert(cld->is_unloading(), "invariant"); 376 cld->packages_do(f); 377 } 378 } 379 380 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) { 381 ClassLoaderDataGraphIterator iter; 382 while (iter.repeat()) { 383 ClassLoaderData* cld = iter.get_next(); 384 cld->loaded_classes_do(klass_closure); 385 } 386 } 387 388 // This case can block but cannot do unloading (called from CDS) 389 void ClassLoaderDataGraph::unlocked_loaded_classes_do(KlassClosure* klass_closure) { 390 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) { 391 cld->loaded_classes_do(klass_closure); 392 } 393 } 394 395 396 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) { 397 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 398 // Only walk the head until any clds not purged from prior unloading 399 // (CMS doesn't purge right away). 400 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) { 401 assert(cld->is_unloading(), "invariant"); 402 cld->classes_do(f); 403 } 404 } 405 406 #define FOR_ALL_DICTIONARY(X) ClassLoaderDataGraphIterator iter; \ 407 ClassLoaderData* X; \ 408 while ((X = iter.get_next()) != NULL) \ 409 if (X->dictionary() != NULL) 410 411 // Walk classes in the loaded class dictionaries in various forms. 412 // Only walks the classes defined in this class loader. 413 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) { 414 FOR_ALL_DICTIONARY(cld) { 415 cld->dictionary()->classes_do(f); 416 } 417 } 418 419 // Only walks the classes defined in this class loader. 420 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) { 421 FOR_ALL_DICTIONARY(cld) { 422 cld->dictionary()->classes_do(f, CHECK); 423 } 424 } 425 426 void ClassLoaderDataGraph::verify_dictionary() { 427 FOR_ALL_DICTIONARY(cld) { 428 cld->dictionary()->verify(); 429 } 430 } 431 432 void ClassLoaderDataGraph::print_dictionary(outputStream* st) { 433 FOR_ALL_DICTIONARY(cld) { 434 st->print("Dictionary for "); 435 cld->print_value_on(st); 436 st->cr(); 437 cld->dictionary()->print_on(st); 438 st->cr(); 439 } 440 } 441 442 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) { 443 FOR_ALL_DICTIONARY(cld) { 444 ResourceMark rm; 445 stringStream tempst; 446 tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id()); 447 cld->dictionary()->print_table_statistics(st, tempst.as_string()); 448 } 449 } 450 451 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() { 452 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 453 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?"); 454 455 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>(); 456 457 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true); 458 ClassLoaderData* curr = _head; 459 while (curr != _saved_head) { 460 if (!curr->claimed()) { 461 array->push(curr); 462 LogTarget(Debug, class, loader, data) lt; 463 if (lt.is_enabled()) { 464 LogStream ls(lt); 465 ls.print("found new CLD: "); 466 curr->print_value_on(&ls); 467 ls.cr(); 468 } 469 } 470 471 curr = curr->_next; 472 } 473 474 return array; 475 } 476 477 #ifndef PRODUCT 478 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) { 479 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 480 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 481 if (loader_data == data) { 482 return true; 483 } 484 } 485 486 return false; 487 } 488 #endif // PRODUCT 489 490 bool ClassLoaderDataGraph::is_valid(ClassLoaderData* loader_data) { 491 DEBUG_ONLY( if (!VMError::is_error_reported()) { assert_locked_or_safepoint(ClassLoaderDataGraph_lock); } ) 492 if (loader_data != NULL) { 493 if (loader_data == ClassLoaderData::the_null_class_loader_data()) { 494 return true; 495 } 496 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) { 497 if (loader_data == data) { 498 return true; 499 } 500 } 501 } 502 return false; 503 } 504 505 // Move class loader data from main list to the unloaded list for unloading 506 // and deallocation later. 507 bool ClassLoaderDataGraph::do_unloading(bool do_cleaning) { 508 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 509 510 // Indicate whether safepoint cleanup is needed. 511 _safepoint_cleanup_needed |= do_cleaning; 512 513 ClassLoaderData* data = _head; 514 ClassLoaderData* prev = NULL; 515 bool seen_dead_loader = false; 516 uint loaders_processed = 0; 517 uint loaders_removed = 0; 518 519 // Save previous _unloading pointer for CMS which may add to unloading list before 520 // purging and we don't want to rewalk the previously unloaded class loader data. 521 _saved_unloading = _unloading; 522 523 data = _head; 524 while (data != NULL) { 525 if (data->is_alive()) { 526 prev = data; 527 data = data->next(); 528 loaders_processed++; 529 continue; 530 } 531 seen_dead_loader = true; 532 loaders_removed++; 533 ClassLoaderData* dead = data; 534 dead->unload(); 535 data = data->next(); 536 // Remove from loader list. 537 // This class loader data will no longer be found 538 // in the ClassLoaderDataGraph. 539 if (prev != NULL) { 540 prev->set_next(data); 541 } else { 542 assert(dead == _head, "sanity check"); 543 _head = data; 544 } 545 dead->set_next(_unloading); 546 _unloading = dead; 547 } 548 549 log_debug(class, loader, data)("do_unloading: loaders processed %u, loaders removed %u", loaders_processed, loaders_removed); 550 551 return seen_dead_loader; 552 } 553 554 // There's at least one dead class loader. Purge refererences of healthy module 555 // reads lists and package export lists to modules belonging to dead loaders. 556 void ClassLoaderDataGraph::clean_module_and_package_info() { 557 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 558 559 ClassLoaderData* data = _head; 560 while (data != NULL) { 561 // Remove entries in the dictionary of live class loader that have 562 // initiated loading classes in a dead class loader. 563 if (data->dictionary() != NULL) { 564 data->dictionary()->do_unloading(); 565 } 566 // Walk a ModuleEntry's reads, and a PackageEntry's exports 567 // lists to determine if there are modules on those lists that are now 568 // dead and should be removed. A module's life cycle is equivalent 569 // to its defining class loader's life cycle. Since a module is 570 // considered dead if its class loader is dead, these walks must 571 // occur after each class loader's aliveness is determined. 572 if (data->packages() != NULL) { 573 data->packages()->purge_all_package_exports(); 574 } 575 if (data->modules_defined()) { 576 data->modules()->purge_all_module_reads(); 577 } 578 data = data->next(); 579 } 580 } 581 582 void ClassLoaderDataGraph::purge() { 583 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); 584 ClassLoaderData* list = _unloading; 585 _unloading = NULL; 586 ClassLoaderData* next = list; 587 bool classes_unloaded = false; 588 while (next != NULL) { 589 ClassLoaderData* purge_me = next; 590 next = purge_me->next(); 591 delete purge_me; 592 classes_unloaded = true; 593 } 594 if (classes_unloaded) { 595 Metaspace::purge(); 596 set_metaspace_oom(false); 597 } 598 } 599 600 int ClassLoaderDataGraph::resize_if_needed() { 601 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 602 int resized = 0; 603 if (Dictionary::does_any_dictionary_needs_resizing()) { 604 FOR_ALL_DICTIONARY(cld) { 605 if (cld->dictionary()->resize_if_needed()) { 606 resized++; 607 } 608 } 609 } 610 return resized; 611 } 612 613 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic() 614 : _next_klass(NULL) { 615 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 616 ClassLoaderData* cld = ClassLoaderDataGraph::_head; 617 Klass* klass = NULL; 618 619 // Find the first klass in the CLDG. 620 while (cld != NULL) { 621 assert_locked_or_safepoint(cld->metaspace_lock()); 622 klass = cld->_klasses; 623 if (klass != NULL) { 624 _next_klass = klass; 625 return; 626 } 627 cld = cld->next(); 628 } 629 } 630 631 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) { 632 Klass* next = klass->next_link(); 633 if (next != NULL) { 634 return next; 635 } 636 637 // No more klasses in the current CLD. Time to find a new CLD. 638 ClassLoaderData* cld = klass->class_loader_data(); 639 assert_locked_or_safepoint(cld->metaspace_lock()); 640 while (next == NULL) { 641 cld = cld->next(); 642 if (cld == NULL) { 643 break; 644 } 645 next = cld->_klasses; 646 } 647 648 return next; 649 } 650 651 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() { 652 Klass* head = _next_klass; 653 654 while (head != NULL) { 655 Klass* next = next_klass_in_cldg(head); 656 657 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head); 658 659 if (old_head == head) { 660 return head; // Won the CAS. 661 } 662 663 head = old_head; 664 } 665 666 // Nothing more for the iterator to hand out. 667 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head)); 668 return NULL; 669 } 670 671 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() { 672 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!"); 673 _data = ClassLoaderDataGraph::_head; 674 } 675 676 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {} 677 678 ClassLoaderMetaspace* ClassLoaderDataGraphMetaspaceIterator::get_next() { 679 assert(_data != NULL, "Should not be NULL in call to the iterator"); 680 ClassLoaderMetaspace* result = _data->metaspace_or_null(); 681 _data = _data->next(); 682 // This result might be NULL for class loaders without metaspace 683 // yet. It would be nice to return only non-null results but 684 // there is no guarantee that there will be a non-null result 685 // down the list so the caller is going to have to check. 686 return result; 687 } 688 689 #ifndef PRODUCT 690 // callable from debugger 691 extern "C" int print_loader_data_graph() { 692 ResourceMark rm; 693 ClassLoaderDataGraph::print_on(tty); 694 return 0; 695 } 696 697 void ClassLoaderDataGraph::verify() { 698 ClassLoaderDataGraphIterator iter; 699 while (iter.repeat()) { 700 ClassLoaderData* cld = iter.get_next(); 701 cld->verify(); 702 } 703 } 704 705 void ClassLoaderDataGraph::print_on(outputStream * const out) { 706 ClassLoaderDataGraphIterator iter; 707 while (iter.repeat()) { 708 ClassLoaderData* cld = iter.get_next(); 709 cld->print_on(out); 710 } 711 } 712 #endif // PRODUCT