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(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
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