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