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 public:
291 ClassLoaderDataGraphIterator() : _next(ClassLoaderDataGraph::_head) {
292 _thread = Thread::current();
293 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
294 }
295
296 ClassLoaderData* get_next() {
297 ClassLoaderData* cld = _next;
298 // Skip already unloaded CLD for concurrent unloading.
299 while (cld != NULL && !cld->is_alive()) {
300 cld = cld->next();
301 }
302 if (cld != NULL) {
303 // Keep cld that is being returned alive.
304 _holder = Handle(_thread, cld->holder_phantom());
305 _next = cld->next();
306 } else {
307 _next = NULL;
308 }
309 return cld;
310 }
311
312
313 };
314
315 // These functions assume that the caller has locked the ClassLoaderDataGraph_lock
316 // if they are not calling the function from a safepoint.
317 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
318 ClassLoaderDataGraphIterator iter;
319 while (ClassLoaderData* cld = iter.get_next()) {
320 cld->classes_do(klass_closure);
321 }
322 }
323
324 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
325 ClassLoaderDataGraphIterator iter;
326 while (ClassLoaderData* cld = iter.get_next()) {
327 cld->classes_do(f);
328 }
329 }
330
331 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
332 ClassLoaderDataGraphIterator iter;
333 while (ClassLoaderData* cld = iter.get_next()) {
334 cld->methods_do(f);
335 }
336 }
337
338 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
339 assert_locked_or_safepoint(Module_lock);
340 ClassLoaderDataGraphIterator iter;
341 while (ClassLoaderData* cld = iter.get_next()) {
342 cld->modules_do(f);
343 }
344 }
345
346 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
347 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
348 // Only walk the head until any clds not purged from prior unloading
349 // (CMS doesn't purge right away).
350 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
351 assert(cld->is_unloading(), "invariant");
352 cld->modules_do(f);
353 }
354 }
355
356 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
357 assert_locked_or_safepoint(Module_lock);
358 ClassLoaderDataGraphIterator iter;
359 while (ClassLoaderData* cld = iter.get_next()) {
360 cld->packages_do(f);
361 }
362 }
363
364 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
365 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
366 // Only walk the head until any clds not purged from prior unloading
367 // (CMS doesn't purge right away).
368 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
369 assert(cld->is_unloading(), "invariant");
370 cld->packages_do(f);
371 }
372 }
373
374 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
375 ClassLoaderDataGraphIterator iter;
376 while (ClassLoaderData* cld = iter.get_next()) {
377 cld->loaded_classes_do(klass_closure);
378 }
379 }
380
381 // This case can block but cannot do unloading (called from CDS)
382 void ClassLoaderDataGraph::unlocked_loaded_classes_do(KlassClosure* klass_closure) {
383 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
384 cld->loaded_classes_do(klass_closure);
385 }
386 }
387
388
389 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
390 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
391 // Only walk the head until any clds not purged from prior unloading
392 // (CMS doesn't purge right away).
393 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
394 assert(cld->is_unloading(), "invariant");
395 cld->classes_do(f);
396 }
397 }
398
399 #define FOR_ALL_DICTIONARY(X) ClassLoaderDataGraphIterator iter; \
400 while (ClassLoaderData* X = iter.get_next()) \
401 if (X->dictionary() != NULL)
402
403 // Walk classes in the loaded class dictionaries in various forms.
404 // Only walks the classes defined in this class loader.
405 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
406 FOR_ALL_DICTIONARY(cld) {
407 cld->dictionary()->classes_do(f);
408 }
409 }
410
411 // Only walks the classes defined in this class loader.
412 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
413 FOR_ALL_DICTIONARY(cld) {
414 cld->dictionary()->classes_do(f, CHECK);
415 }
416 }
417
418 void ClassLoaderDataGraph::verify_dictionary() {
419 FOR_ALL_DICTIONARY(cld) {
420 cld->dictionary()->verify();
421 }
422 }
423
424 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
425 FOR_ALL_DICTIONARY(cld) {
426 st->print("Dictionary for ");
427 cld->print_value_on(st);
428 st->cr();
429 cld->dictionary()->print_on(st);
430 st->cr();
431 }
432 }
433
434 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
435 FOR_ALL_DICTIONARY(cld) {
436 ResourceMark rm;
437 stringStream tempst;
438 tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id());
439 cld->dictionary()->print_table_statistics(st, tempst.as_string());
440 }
441 }
442
443 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
444 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
445 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
446
447 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
448
449 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
450 ClassLoaderData* curr = _head;
451 while (curr != _saved_head) {
452 if (!curr->claimed()) {
453 array->push(curr);
454 LogTarget(Debug, class, loader, data) lt;
455 if (lt.is_enabled()) {
456 LogStream ls(lt);
457 ls.print("found new CLD: ");
458 curr->print_value_on(&ls);
459 ls.cr();
460 }
461 }
462
463 curr = curr->_next;
464 }
465
466 return array;
467 }
468
469 #ifndef PRODUCT
470 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
471 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
472 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
473 if (loader_data == data) {
474 return true;
475 }
476 }
477
478 return false;
479 }
480 #endif // PRODUCT
481
482 bool ClassLoaderDataGraph::is_valid(ClassLoaderData* loader_data) {
483 DEBUG_ONLY( if (!VMError::is_error_reported()) { assert_locked_or_safepoint(ClassLoaderDataGraph_lock); } )
484 if (loader_data != NULL) {
485 if (loader_data == ClassLoaderData::the_null_class_loader_data()) {
486 return true;
487 }
488 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
489 if (loader_data == data) {
490 return true;
491 }
492 }
493 }
494 return false;
495 }
496
497 // Move class loader data from main list to the unloaded list for unloading
498 // and deallocation later.
499 bool ClassLoaderDataGraph::do_unloading(bool do_cleaning) {
500 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
501
502 // Indicate whether safepoint cleanup is needed.
503 _safepoint_cleanup_needed |= do_cleaning;
504
505 ClassLoaderData* data = _head;
506 ClassLoaderData* prev = NULL;
507 bool seen_dead_loader = false;
508 uint loaders_processed = 0;
509 uint loaders_removed = 0;
510
511 // Save previous _unloading pointer for CMS which may add to unloading list before
512 // purging and we don't want to rewalk the previously unloaded class loader data.
513 _saved_unloading = _unloading;
514
515 data = _head;
516 while (data != NULL) {
517 if (data->is_alive()) {
518 prev = data;
519 data = data->next();
520 loaders_processed++;
521 continue;
522 }
523 seen_dead_loader = true;
524 loaders_removed++;
525 ClassLoaderData* dead = data;
526 dead->unload();
527 data = data->next();
528 // Remove from loader list.
529 // This class loader data will no longer be found
530 // in the ClassLoaderDataGraph.
531 if (prev != NULL) {
532 prev->set_next(data);
533 } else {
534 assert(dead == _head, "sanity check");
535 _head = data;
536 }
537 dead->set_next(_unloading);
538 _unloading = dead;
539 }
540
541 log_debug(class, loader, data)("do_unloading: loaders processed %u, loaders removed %u", loaders_processed, loaders_removed);
542
543 return seen_dead_loader;
544 }
545
546 // There's at least one dead class loader. Purge refererences of healthy module
547 // reads lists and package export lists to modules belonging to dead loaders.
548 void ClassLoaderDataGraph::clean_module_and_package_info() {
549 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
550
551 ClassLoaderData* data = _head;
552 while (data != NULL) {
553 // Remove entries in the dictionary of live class loader that have
554 // initiated loading classes in a dead class loader.
555 if (data->dictionary() != NULL) {
556 data->dictionary()->do_unloading();
557 }
558 // Walk a ModuleEntry's reads, and a PackageEntry's exports
559 // lists to determine if there are modules on those lists that are now
560 // dead and should be removed. A module's life cycle is equivalent
561 // to its defining class loader's life cycle. Since a module is
562 // considered dead if its class loader is dead, these walks must
563 // occur after each class loader's aliveness is determined.
564 if (data->packages() != NULL) {
565 data->packages()->purge_all_package_exports();
566 }
567 if (data->modules_defined()) {
568 data->modules()->purge_all_module_reads();
569 }
570 data = data->next();
571 }
572 }
573
574 void ClassLoaderDataGraph::purge() {
575 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
576 ClassLoaderData* list = _unloading;
577 _unloading = NULL;
578 ClassLoaderData* next = list;
579 bool classes_unloaded = false;
580 while (next != NULL) {
581 ClassLoaderData* purge_me = next;
582 next = purge_me->next();
583 delete purge_me;
584 classes_unloaded = true;
585 }
586 if (classes_unloaded) {
587 Metaspace::purge();
588 set_metaspace_oom(false);
589 }
590 }
591
592 int ClassLoaderDataGraph::resize_if_needed() {
593 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
594 int resized = 0;
595 if (Dictionary::does_any_dictionary_needs_resizing()) {
596 FOR_ALL_DICTIONARY(cld) {
597 if (cld->dictionary()->resize_if_needed()) {
598 resized++;
599 }
600 }
601 }
602 return resized;
603 }
604
605 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
606 : _next_klass(NULL) {
607 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
608 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
609 Klass* klass = NULL;
610
611 // Find the first klass in the CLDG.
612 while (cld != NULL) {
613 assert_locked_or_safepoint(cld->metaspace_lock());
614 klass = cld->_klasses;
615 if (klass != NULL) {
616 _next_klass = klass;
617 return;
618 }
619 cld = cld->next();
620 }
621 }
622
623 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
624 Klass* next = klass->next_link();
625 if (next != NULL) {
626 return next;
627 }
628
629 // No more klasses in the current CLD. Time to find a new CLD.
630 ClassLoaderData* cld = klass->class_loader_data();
631 assert_locked_or_safepoint(cld->metaspace_lock());
632 while (next == NULL) {
633 cld = cld->next();
634 if (cld == NULL) {
635 break;
636 }
637 next = cld->_klasses;
638 }
639
640 return next;
641 }
642
643 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
644 Klass* head = _next_klass;
645
646 while (head != NULL) {
647 Klass* next = next_klass_in_cldg(head);
648
649 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
650
651 if (old_head == head) {
652 return head; // Won the CAS.
653 }
654
655 head = old_head;
656 }
657
658 // Nothing more for the iterator to hand out.
659 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
660 return NULL;
661 }
662
663 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
664 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
665 _data = ClassLoaderDataGraph::_head;
666 }
667
668 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
669
670 ClassLoaderMetaspace* ClassLoaderDataGraphMetaspaceIterator::get_next() {
671 assert(_data != NULL, "Should not be NULL in call to the iterator");
672 ClassLoaderMetaspace* result = _data->metaspace_or_null();
673 _data = _data->next();
674 // This result might be NULL for class loaders without metaspace
675 // yet. It would be nice to return only non-null results but
676 // there is no guarantee that there will be a non-null result
677 // down the list so the caller is going to have to check.
678 return result;
679 }
680
681 #ifndef PRODUCT
682 // callable from debugger
683 extern "C" int print_loader_data_graph() {
684 ResourceMark rm;
685 ClassLoaderDataGraph::print_on(tty);
686 return 0;
687 }
688
689 void ClassLoaderDataGraph::verify() {
690 ClassLoaderDataGraphIterator iter;
691 while (ClassLoaderData* cld = iter.get_next()) {
692 cld->verify();
693 }
694 }
695
696 void ClassLoaderDataGraph::print_on(outputStream * const out) {
697 ClassLoaderDataGraphIterator iter;
698 while (ClassLoaderData* cld = iter.get_next()) {
699 cld->print_on(out);
700 }
701 }
702 #endif // PRODUCT