1 /*
2 * Copyright (c) 2012, 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 // A ClassLoaderData identifies the full set of class types that a class
26 // loader's name resolution strategy produces for a given configuration of the
27 // class loader.
28 // Class types in the ClassLoaderData may be defined by from class file binaries
29 // provided by the class loader, or from other class loader it interacts with
30 // according to its name resolution strategy.
31 //
32 // Class loaders that implement a deterministic name resolution strategy
33 // (including with respect to their delegation behavior), such as the boot, the
34 // platform, and the system loaders of the JDK's built-in class loader
35 // hierarchy, always produce the same linkset for a given configuration.
36 //
37 // ClassLoaderData carries information related to a linkset (e.g.,
38 // metaspace holding its klass definitions).
39 // The System Dictionary and related data structures (e.g., placeholder table,
40 // loader constraints table) as well as the runtime representation of classes
41 // only reference ClassLoaderData.
42 //
43 // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that
44 // that represent the loader's "linking domain" in the JVM.
45 //
46 // The bootstrap loader (represented by NULL) also has a ClassLoaderData,
47 // the singleton class the_null_class_loader_data().
48
49 #include "precompiled.hpp"
50 #include "classfile/classLoaderData.hpp"
51 #include "classfile/classLoaderData.inline.hpp"
52 #include "classfile/dictionary.hpp"
53 #include "classfile/javaClasses.hpp"
54 #include "classfile/metadataOnStackMark.hpp"
55 #include "classfile/moduleEntry.hpp"
56 #include "classfile/packageEntry.hpp"
57 #include "classfile/systemDictionary.hpp"
58 #include "code/codeCache.hpp"
59 #include "gc/shared/oopStorage.hpp"
60 #include "logging/log.hpp"
61 #include "logging/logStream.hpp"
62 #include "memory/allocation.inline.hpp"
63 #include "memory/metadataFactory.hpp"
64 #include "memory/metaspaceShared.hpp"
65 #include "memory/oopFactory.hpp"
66 #include "memory/resourceArea.hpp"
67 #include "oops/access.inline.hpp"
68 #include "oops/objArrayOop.inline.hpp"
69 #include "oops/oop.inline.hpp"
70 #include "runtime/atomic.hpp"
71 #include "runtime/handles.inline.hpp"
72 #include "runtime/javaCalls.hpp"
73 #include "runtime/jniHandles.hpp"
74 #include "runtime/mutex.hpp"
75 #include "runtime/orderAccess.hpp"
76 #include "runtime/safepoint.hpp"
77 #include "runtime/safepointVerifiers.hpp"
78 #include "runtime/synchronizer.hpp"
79 #include "utilities/growableArray.hpp"
80 #include "utilities/macros.hpp"
81 #include "utilities/ostream.hpp"
82 #if INCLUDE_TRACE
83 #include "trace/tracing.hpp"
84 #endif
85
86 volatile size_t ClassLoaderDataGraph::_num_array_classes = 0;
87 volatile size_t ClassLoaderDataGraph::_num_instance_classes = 0;
88
89 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
90
91 void ClassLoaderData::init_null_class_loader_data() {
92 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
93 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
94
95 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
96 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
97 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
98
99 LogTarget(Debug, class, loader, data) lt;
100 if (lt.is_enabled()) {
101 ResourceMark rm;
102 LogStream ls(lt);
103 ls.print("create ");
104 _the_null_class_loader_data->print_value_on(&ls);
105 ls.cr();
106 }
107 }
108
109 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous) :
110 _class_loader(h_class_loader()),
111 _is_anonymous(is_anonymous),
112 // An anonymous class loader data doesn't have anything to keep
113 // it from being unloaded during parsing of the anonymous class.
114 // The null-class-loader should always be kept alive.
115 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
116 _metaspace(NULL), _unloading(false), _klasses(NULL),
117 _modules(NULL), _packages(NULL),
118 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false),
119 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
120 _next(NULL),
121 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
122 Monitor::_safepoint_check_never)) {
123
124 // A ClassLoaderData created solely for an anonymous class should never have a
125 // ModuleEntryTable or PackageEntryTable created for it. The defining package
126 // and module for an anonymous class will be found in its host class.
127 if (!is_anonymous) {
128 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
129 if (h_class_loader.is_null()) {
130 // Create unnamed module for boot loader
131 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
132 } else {
133 // Create unnamed module for all other loaders
134 _unnamed_module = ModuleEntry::create_unnamed_module(this);
135 }
136 _dictionary = create_dictionary();
137 } else {
138 _packages = NULL;
139 _unnamed_module = NULL;
140 _dictionary = NULL;
141 }
142
143 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
144
145 TRACE_INIT_ID(this);
146 }
147
148 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
149 Chunk* c = _head;
150 while (c != NULL) {
151 Chunk* next = c->_next;
152 delete c;
153 c = next;
154 }
155 }
156
157 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
158 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
159 Chunk* next = new Chunk(_head);
160 OrderAccess::release_store(&_head, next);
161 }
162 oop* handle = &_head->_data[_head->_size];
163 *handle = o;
164 OrderAccess::release_store(&_head->_size, _head->_size + 1);
165 return handle;
166 }
167
168 int ClassLoaderData::ChunkedHandleList::count() const {
169 int count = 0;
170 Chunk* chunk = _head;
171 while (chunk != NULL) {
172 count += chunk->_size;
173 chunk = chunk->_next;
174 }
175 return count;
176 }
177
178 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
179 for (juint i = 0; i < size; i++) {
180 if (c->_data[i] != NULL) {
181 f->do_oop(&c->_data[i]);
182 }
183 }
184 }
185
186 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
187 Chunk* head = OrderAccess::load_acquire(&_head);
188 if (head != NULL) {
189 // Must be careful when reading size of head
190 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
191 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
192 oops_do_chunk(f, c, c->_size);
193 }
194 }
195 }
196
197 class VerifyContainsOopClosure : public OopClosure {
198 oop _target;
199 bool _found;
200
201 public:
202 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
203
204 void do_oop(oop* p) {
205 if (p != NULL && *p == _target) {
206 _found = true;
207 }
208 }
209
210 void do_oop(narrowOop* p) {
211 // The ChunkedHandleList should not contain any narrowOop
212 ShouldNotReachHere();
213 }
214
215 bool found() const {
216 return _found;
217 }
218 };
219
220 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
221 VerifyContainsOopClosure cl(p);
222 oops_do(&cl);
223 return cl.found();
224 }
225
226 #ifndef PRODUCT
227 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
228 Chunk* chunk = _head;
229 while (chunk != NULL) {
230 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
231 return true;
232 }
233 chunk = chunk->_next;
234 }
235 return false;
236 }
237 #endif // PRODUCT
238
239 bool ClassLoaderData::claim() {
240 if (_claimed == 1) {
241 return false;
242 }
243
244 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
245 }
246
247 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
248 // while the class is being parsed, and if the class appears on the module fixup list.
249 // Due to the uniqueness that no other class shares the anonymous class' name or
250 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
251 // it is being defined, therefore _keep_alive is not volatile or atomic.
252 void ClassLoaderData::inc_keep_alive() {
253 if (is_anonymous()) {
254 assert(_keep_alive >= 0, "Invalid keep alive increment count");
255 _keep_alive++;
256 }
257 }
258
259 void ClassLoaderData::dec_keep_alive() {
260 if (is_anonymous()) {
261 assert(_keep_alive > 0, "Invalid keep alive decrement count");
262 _keep_alive--;
263 }
264 }
265
266 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
267 if (must_claim && !claim()) {
268 return;
269 }
270
271 // Only clear modified_oops after the ClassLoaderData is claimed.
272 if (clear_mod_oops) {
273 clear_modified_oops();
274 }
275
276 f->do_oop(&_class_loader);
277 _handles.oops_do(f);
278 }
279
280 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
281 // Lock-free access requires load_acquire
282 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
283 klass_closure->do_klass(k);
284 assert(k != k->next_link(), "no loops!");
285 }
286 }
287
288 void ClassLoaderData::classes_do(void f(Klass * const)) {
289 // Lock-free access requires load_acquire
290 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
291 f(k);
292 assert(k != k->next_link(), "no loops!");
293 }
294 }
295
296 void ClassLoaderData::methods_do(void f(Method*)) {
297 // Lock-free access requires load_acquire
298 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
299 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
300 InstanceKlass::cast(k)->methods_do(f);
301 }
302 }
303 }
304
305 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
306 // Lock-free access requires load_acquire
307 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
308 // Do not filter ArrayKlass oops here...
309 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
310 klass_closure->do_klass(k);
311 }
312 }
313 }
314
315 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
316 // Lock-free access requires load_acquire
317 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
318 if (k->is_instance_klass()) {
319 f(InstanceKlass::cast(k));
320 }
321 assert(k != k->next_link(), "no loops!");
322 }
323 }
324
325 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
326 assert_locked_or_safepoint(Module_lock);
327 if (_unnamed_module != NULL) {
328 f(_unnamed_module);
329 }
330 if (_modules != NULL) {
331 for (int i = 0; i < _modules->table_size(); i++) {
332 for (ModuleEntry* entry = _modules->bucket(i);
333 entry != NULL;
334 entry = entry->next()) {
335 f(entry);
336 }
337 }
338 }
339 }
340
341 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
342 assert_locked_or_safepoint(Module_lock);
343 if (_packages != NULL) {
344 for (int i = 0; i < _packages->table_size(); i++) {
345 for (PackageEntry* entry = _packages->bucket(i);
346 entry != NULL;
347 entry = entry->next()) {
348 f(entry);
349 }
350 }
351 }
352 }
353
354 void ClassLoaderData::record_dependency(const Klass* k) {
355 assert(k != NULL, "invariant");
356
357 ClassLoaderData * const from_cld = this;
358 ClassLoaderData * const to_cld = k->class_loader_data();
359
360 // Do not need to record dependency if the dependency is to a class whose
361 // class loader data is never freed. (i.e. the dependency's class loader
362 // is one of the three builtin class loaders and the dependency is not
363 // anonymous.)
364 if (to_cld->is_permanent_class_loader_data()) {
365 return;
366 }
367
368 oop to;
369 if (to_cld->is_anonymous()) {
370 // Just return if an anonymous class is attempting to record a dependency
371 // to itself. (Note that every anonymous class has its own unique class
372 // loader data.)
373 if (to_cld == from_cld) {
374 return;
375 }
376 // Anonymous class dependencies are through the mirror.
377 to = k->java_mirror();
378 } else {
379 to = to_cld->class_loader();
380 oop from = from_cld->class_loader();
381
382 // Just return if this dependency is to a class with the same or a parent
383 // class_loader.
384 if (from == to || java_lang_ClassLoader::isAncestor(from, to)) {
385 return; // this class loader is in the parent list, no need to add it.
386 }
387 }
388
389 // It's a dependency we won't find through GC, add it.
390 if (!_handles.contains(to)) {
391 NOT_PRODUCT(Atomic::inc(&_dependency_count));
392 LogTarget(Trace, class, loader, data) lt;
393 if (lt.is_enabled()) {
394 ResourceMark rm;
395 LogStream ls(lt);
396 ls.print("adding dependency from ");
397 print_value_on(&ls);
398 ls.print(" to ");
399 to_cld->print_value_on(&ls);
400 ls.cr();
401 }
402 Handle dependency(Thread::current(), to);
403 add_handle(dependency);
404 // Added a potentially young gen oop to the ClassLoaderData
405 record_modified_oops();
406 }
407 }
408
409
410 void ClassLoaderDataGraph::clear_claimed_marks() {
411 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
412 cld->clear_claimed();
413 }
414 }
415
416 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
417 {
418 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
419 Klass* old_value = _klasses;
420 k->set_next_link(old_value);
421 // Link the new item into the list, making sure the linked class is stable
422 // since the list can be walked without a lock
423 OrderAccess::release_store(&_klasses, k);
424 if (k->is_array_klass()) {
425 ClassLoaderDataGraph::inc_array_classes(1);
426 } else {
427 ClassLoaderDataGraph::inc_instance_classes(1);
428 }
429 }
430
431 if (publicize) {
432 LogTarget(Trace, class, loader, data) lt;
433 if (lt.is_enabled()) {
434 ResourceMark rm;
435 LogStream ls(lt);
436 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
437 print_value_on(&ls);
438 ls.cr();
439 }
440 }
441 }
442
443 // Class iterator used by the compiler. It gets some number of classes at
444 // a safepoint to decay invocation counters on the methods.
445 class ClassLoaderDataGraphKlassIteratorStatic {
446 ClassLoaderData* _current_loader_data;
447 Klass* _current_class_entry;
448 public:
449
450 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
451
452 InstanceKlass* try_get_next_class() {
453 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
454 size_t max_classes = ClassLoaderDataGraph::num_instance_classes();
455 assert(max_classes > 0, "should not be called with no instance classes");
456 for (size_t i = 0; i < max_classes; ) {
457
458 if (_current_class_entry != NULL) {
459 Klass* k = _current_class_entry;
460 _current_class_entry = _current_class_entry->next_link();
461
462 if (k->is_instance_klass()) {
463 InstanceKlass* ik = InstanceKlass::cast(k);
464 i++; // count all instance classes found
465 // Not yet loaded classes are counted in max_classes
466 // but only return loaded classes.
467 if (ik->is_loaded()) {
468 return ik;
469 }
470 }
471 } else {
472 // Go to next CLD
473 if (_current_loader_data != NULL) {
474 _current_loader_data = _current_loader_data->next();
475 }
476 // Start at the beginning
477 if (_current_loader_data == NULL) {
478 _current_loader_data = ClassLoaderDataGraph::_head;
479 }
480
481 _current_class_entry = _current_loader_data->klasses();
482 }
483 }
484 // Should never be reached unless all instance classes have failed or are not fully loaded.
485 // Caller handles NULL.
486 return NULL;
487 }
488
489 // If the current class for the static iterator is a class being unloaded or
490 // deallocated, adjust the current class.
491 void adjust_saved_class(ClassLoaderData* cld) {
492 if (_current_loader_data == cld) {
493 _current_loader_data = cld->next();
494 if (_current_loader_data != NULL) {
495 _current_class_entry = _current_loader_data->klasses();
496 } // else try_get_next_class will start at the head
497 }
498 }
499
500 void adjust_saved_class(Klass* klass) {
501 if (_current_class_entry == klass) {
502 _current_class_entry = klass->next_link();
503 }
504 }
505 };
506
507 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
508
509 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
510 return static_klass_iterator.try_get_next_class();
511 }
512
513
514 void ClassLoaderData::update_holder(Handle holder) {
515 assert(holder() != NULL, "should be called with non-NULL loader");
516 assert(_holder.peek() == NULL, "never replace holders");
517 _holder = WeakHandle::create(holder);
518 }
519
520 // Remove a klass from the _klasses list for scratch_class during redefinition
521 // or parsed class in the case of an error.
522 void ClassLoaderData::remove_class(Klass* scratch_class) {
523 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
524
525 // Adjust global class iterator.
526 static_klass_iterator.adjust_saved_class(scratch_class);
527
528 Klass* prev = NULL;
529 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
530 if (k == scratch_class) {
531 if (prev == NULL) {
532 _klasses = k->next_link();
533 } else {
534 Klass* next = k->next_link();
535 prev->set_next_link(next);
536 }
537
538 if (k->is_array_klass()) {
539 ClassLoaderDataGraph::dec_array_classes(1);
540 } else {
541 ClassLoaderDataGraph::dec_instance_classes(1);
542 }
543
544 return;
545 }
546 prev = k;
547 assert(k != k->next_link(), "no loops!");
548 }
549 ShouldNotReachHere(); // should have found this class!!
550 }
551
552 void ClassLoaderData::unload() {
553 _unloading = true;
554
555 // Tell serviceability tools these classes are unloading
556 classes_do(InstanceKlass::notify_unload_class);
557
558 LogTarget(Debug, class, loader, data) lt;
559 if (lt.is_enabled()) {
560 ResourceMark rm;
561 LogStream ls(lt);
562 ls.print("unload ");
563 print_value_on(&ls);
564 ls.cr();
565 }
566
567 // Some items on the _deallocate_list need to free their C heap structures
568 // if they are not already on the _klasses list.
569 unload_deallocate_list();
570
571 // Clean up global class iterator for compiler
572 static_klass_iterator.adjust_saved_class(this);
573 }
574
575 ModuleEntryTable* ClassLoaderData::modules() {
576 // Lazily create the module entry table at first request.
577 // Lock-free access requires load_acquire.
578 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
579 if (modules == NULL) {
580 MutexLocker m1(Module_lock);
581 // Check if _modules got allocated while we were waiting for this lock.
582 if ((modules = _modules) == NULL) {
583 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
584
585 {
586 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
587 // Ensure _modules is stable, since it is examined without a lock
588 OrderAccess::release_store(&_modules, modules);
589 }
590 }
591 }
592 return modules;
593 }
594
595 const int _boot_loader_dictionary_size = 1009;
596 const int _default_loader_dictionary_size = 107;
597
598 Dictionary* ClassLoaderData::create_dictionary() {
599 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
600 int size;
601 bool resizable = false;
602 if (_the_null_class_loader_data == NULL) {
603 size = _boot_loader_dictionary_size;
604 resizable = true;
605 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
606 size = 1; // there's only one class in relection class loader and no initiated classes
607 } else if (is_system_class_loader_data()) {
608 size = _boot_loader_dictionary_size;
609 resizable = true;
610 } else {
611 size = _default_loader_dictionary_size;
612 resizable = true;
613 }
614 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) {
615 resizable = false;
616 }
617 return new Dictionary(this, size, resizable);
618 }
619
620 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
621 oop ClassLoaderData::holder_phantom() {
622 // A klass that was previously considered dead can be looked up in the
623 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
624 // or a reachable object making it alive again. The SATB part of G1 needs
625 // to get notified about this potential resurrection, otherwise the marking
626 // might not find the object.
627 return _holder.resolve();
628 }
629
630 // Unloading support
631 bool ClassLoaderData::is_alive() const {
632 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
633 || _holder.is_null()
634 || (_holder.peek() != NULL); // not cleaned by weak reference processing
635
636 return alive;
637 }
638
639 class ReleaseKlassClosure: public KlassClosure {
640 private:
641 size_t _instance_class_released;
642 size_t _array_class_released;
643 public:
644 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
645
646 size_t instance_class_released() const { return _instance_class_released; }
647 size_t array_class_released() const { return _array_class_released; }
648
649 void do_klass(Klass* k) {
650 if (k->is_array_klass()) {
651 _array_class_released ++;
652 } else {
653 assert(k->is_instance_klass(), "Must be");
654 _instance_class_released ++;
655 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
656 }
657 }
658 };
659
660 ClassLoaderData::~ClassLoaderData() {
661 // Release C heap structures for all the classes.
662 ReleaseKlassClosure cl;
663 classes_do(&cl);
664
665 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
666 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
667
668 // Release the WeakHandle, if already set
669 if (!_holder.is_null()) {
670 _holder.release();
671 }
672
673 // Release C heap allocated hashtable for all the packages.
674 if (_packages != NULL) {
675 // Destroy the table itself
676 delete _packages;
677 _packages = NULL;
678 }
679
680 // Release C heap allocated hashtable for all the modules.
681 if (_modules != NULL) {
682 // Destroy the table itself
683 delete _modules;
684 _modules = NULL;
685 }
686
687 // Release C heap allocated hashtable for the dictionary
688 if (_dictionary != NULL) {
689 // Destroy the table itself
690 delete _dictionary;
691 _dictionary = NULL;
692 }
693
694 if (_unnamed_module != NULL) {
695 _unnamed_module->delete_unnamed_module();
696 _unnamed_module = NULL;
697 }
698
699 // release the metaspace
700 ClassLoaderMetaspace *m = _metaspace;
701 if (m != NULL) {
702 _metaspace = NULL;
703 delete m;
704 }
705 // Clear all the JNI handles for methods
706 // These aren't deallocated and are going to look like a leak, but that's
707 // needed because we can't really get rid of jmethodIDs because we don't
708 // know when native code is going to stop using them. The spec says that
709 // they're "invalid" but existing programs likely rely on their being
710 // NULL after class unloading.
711 if (_jmethod_ids != NULL) {
712 Method::clear_jmethod_ids(this);
713 }
714 // Delete lock
715 delete _metaspace_lock;
716
717 // Delete free list
718 if (_deallocate_list != NULL) {
719 delete _deallocate_list;
720 }
721 }
722
723 // Returns true if this class loader data is for the app class loader
724 // or a user defined system class loader. (Note that the class loader
725 // data may be anonymous.)
726 bool ClassLoaderData::is_system_class_loader_data() const {
727 return SystemDictionary::is_system_class_loader(class_loader());
728 }
729
730 // Returns true if this class loader data is for the platform class loader.
731 // (Note that the class loader data may be anonymous.)
732 bool ClassLoaderData::is_platform_class_loader_data() const {
733 return SystemDictionary::is_platform_class_loader(class_loader());
734 }
735
736 // Returns true if the class loader for this class loader data is one of
737 // the 3 builtin (boot application/system or platform) class loaders,
738 // including a user-defined system class loader. Note that if the class
739 // loader data is for an anonymous class then it may get freed by a GC
740 // even if its class loader is one of these loaders.
741 bool ClassLoaderData::is_builtin_class_loader_data() const {
742 return (is_boot_class_loader_data() ||
743 SystemDictionary::is_system_class_loader(class_loader()) ||
744 SystemDictionary::is_platform_class_loader(class_loader()));
745 }
746
747 // Returns true if this class loader data is a class loader data
748 // that is not ever freed by a GC. It must be one of the builtin
749 // class loaders and not anonymous.
750 bool ClassLoaderData::is_permanent_class_loader_data() const {
751 return is_builtin_class_loader_data() && !is_anonymous();
752 }
753
754 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
755 // If the metaspace has not been allocated, create a new one. Might want
756 // to create smaller arena for Reflection class loaders also.
757 // The reason for the delayed allocation is because some class loaders are
758 // simply for delegating with no metadata of their own.
759 // Lock-free access requires load_acquire.
760 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
761 if (metaspace == NULL) {
762 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
763 // Check if _metaspace got allocated while we were waiting for this lock.
764 if ((metaspace = _metaspace) == NULL) {
765 if (this == the_null_class_loader_data()) {
766 assert (class_loader() == NULL, "Must be");
767 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
768 } else if (is_anonymous()) {
769 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
770 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
771 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
772 } else {
773 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
774 }
775 // Ensure _metaspace is stable, since it is examined without a lock
776 OrderAccess::release_store(&_metaspace, metaspace);
777 }
778 }
779 return metaspace;
780 }
781
782 OopHandle ClassLoaderData::add_handle(Handle h) {
783 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
784 record_modified_oops();
785 return OopHandle(_handles.add(h()));
786 }
787
788 void ClassLoaderData::remove_handle(OopHandle h) {
789 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
790 oop* ptr = h.ptr_raw();
791 if (ptr != NULL) {
792 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
793 // This root is not walked in safepoints, and hence requires an appropriate
794 // decorator that e.g. maintains the SATB invariant in SATB collectors.
795 RootAccess<IN_CONCURRENT_ROOT>::oop_store(ptr, oop(NULL));
796 }
797 }
798
799 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
800 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
801 if (dest.resolve() != NULL) {
802 return;
803 } else {
804 dest = _handles.add(h());
805 }
806 }
807
808 // Add this metadata pointer to be freed when it's safe. This is only during
809 // class unloading because Handles might point to this metadata field.
810 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
811 // Metadata in shared region isn't deleted.
812 if (!m->is_shared()) {
813 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
814 if (_deallocate_list == NULL) {
815 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
816 }
817 _deallocate_list->append_if_missing(m);
818 }
819 }
820
821 // Deallocate free metadata on the free list. How useful the PermGen was!
822 void ClassLoaderData::free_deallocate_list() {
823 // Don't need lock, at safepoint
824 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
825 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
826 if (_deallocate_list == NULL) {
827 return;
828 }
829 // Go backwards because this removes entries that are freed.
830 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
831 Metadata* m = _deallocate_list->at(i);
832 if (!m->on_stack()) {
833 _deallocate_list->remove_at(i);
834 // There are only three types of metadata that we deallocate directly.
835 // Cast them so they can be used by the template function.
836 if (m->is_method()) {
837 MetadataFactory::free_metadata(this, (Method*)m);
838 } else if (m->is_constantPool()) {
839 MetadataFactory::free_metadata(this, (ConstantPool*)m);
840 } else if (m->is_klass()) {
841 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
842 } else {
843 ShouldNotReachHere();
844 }
845 } else {
846 // Metadata is alive.
847 // If scratch_class is on stack then it shouldn't be on this list!
848 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
849 "scratch classes on this list should be dead");
850 // Also should assert that other metadata on the list was found in handles.
851 }
852 }
853 }
854
855 // This is distinct from free_deallocate_list. For class loader data that are
856 // unloading, this frees the C heap memory for items on the list, and unlinks
857 // scratch or error classes so that unloading events aren't triggered for these
858 // classes. The metadata is removed with the unloading metaspace.
859 // There isn't C heap memory allocated for methods, so nothing is done for them.
860 void ClassLoaderData::unload_deallocate_list() {
861 // Don't need lock, at safepoint
862 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
863 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
864 if (_deallocate_list == NULL) {
865 return;
866 }
867 // Go backwards because this removes entries that are freed.
868 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
869 Metadata* m = _deallocate_list->at(i);
870 assert (!m->on_stack(), "wouldn't be unloading if this were so");
871 _deallocate_list->remove_at(i);
872 if (m->is_constantPool()) {
873 ((ConstantPool*)m)->release_C_heap_structures();
874 } else if (m->is_klass()) {
875 InstanceKlass* ik = (InstanceKlass*)m;
876 // also releases ik->constants() C heap memory
877 InstanceKlass::release_C_heap_structures(ik);
878 // Remove the class so unloading events aren't triggered for
879 // this class (scratch or error class) in do_unloading().
880 remove_class(ik);
881 }
882 }
883 }
884
885 // These anonymous class loaders are to contain classes used for JSR292
886 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(Handle loader) {
887 // Add a new class loader data to the graph.
888 return ClassLoaderDataGraph::add(loader, true);
889 }
890
891 const char* ClassLoaderData::loader_name() const {
892 // Handles null class loader
893 return SystemDictionary::loader_name(class_loader());
894 }
895
896
897 void ClassLoaderData::print_value_on(outputStream* out) const {
898 if (class_loader() != NULL) {
899 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
900 class_loader()->print_value_on(out); // includes loader_name() and address of class loader instance
901 } else {
902 // loader data: 0xsomeaddr of <bootloader>
903 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name());
904 }
905 if (is_anonymous()) {
906 out->print(" anonymous");
907 }
908 }
909
910 #ifndef PRODUCT
911 void ClassLoaderData::print_on(outputStream* out) const {
912 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
913 p2i(this), p2i((void *)class_loader()), loader_name());
914 if (is_anonymous()) out->print(" anonymous");
915 if (claimed()) out->print(" claimed");
916 if (is_unloading()) out->print(" unloading");
917 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
918
919 if (_jmethod_ids != NULL) {
920 Method::print_jmethod_ids(this, out);
921 }
922 out->print(" handles count %d", _handles.count());
923 out->print(" dependencies %d", _dependency_count);
924 out->print_cr("}");
925 }
926 #endif // PRODUCT
927
928 void ClassLoaderData::verify() {
929 assert_locked_or_safepoint(_metaspace_lock);
930 oop cl = class_loader();
931
932 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
933 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
934
935 // Verify the integrity of the allocated space.
936 if (metaspace_or_null() != NULL) {
937 metaspace_or_null()->verify();
938 }
939
940 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
941 guarantee(k->class_loader_data() == this, "Must be the same");
942 k->verify();
943 assert(k != k->next_link(), "no loops!");
944 }
945 }
946
947 bool ClassLoaderData::contains_klass(Klass* klass) {
948 // Lock-free access requires load_acquire
949 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
950 if (k == klass) return true;
951 }
952 return false;
953 }
954
955
956 // GC root of class loader data created.
957 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
958 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
959 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
960 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
961
962 bool ClassLoaderDataGraph::_should_purge = false;
963 bool ClassLoaderDataGraph::_metaspace_oom = false;
964
965 // Add a new class loader data node to the list. Assign the newly created
966 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
967 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous) {
968 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
969 // ClassLoaderData in the graph since the CLD
970 // contains unhandled oops
971
972 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous);
973
974 if (!is_anonymous) {
975 // First, Atomically set it
976 ClassLoaderData* old = java_lang_ClassLoader::cmpxchg_loader_data(cld, loader(), NULL);
977 if (old != NULL) {
978 delete cld;
979 // Returns the data.
980 return old;
981 }
982
983 // Update the holder if we've won the race
984 // The holder of this class is the class_loader generically.
985 cld->update_holder(loader);
986 }
987
988
989 // We won the race, and therefore the task of adding the data to the list of
990 // class loader data
991 ClassLoaderData** list_head = &_head;
992 ClassLoaderData* next = _head;
993
994 do {
995 cld->set_next(next);
996 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next);
997 if (exchanged == next) {
998 LogTarget(Debug, class, loader, data) lt;
999 if (lt.is_enabled()) {
1000 ResourceMark rm;
1001 LogStream ls(lt);
1002 ls.print("create ");
1003 cld->print_value_on(&ls);
1004 ls.cr();
1005 }
1006 return cld;
1007 }
1008 next = exchanged;
1009 } while (true);
1010 }
1011
1012 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1013 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1014 cld->oops_do(f, must_claim);
1015 }
1016 }
1017
1018 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1019 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1020 if (cld->keep_alive()) {
1021 cld->oops_do(f, must_claim);
1022 }
1023 }
1024 }
1025
1026 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1027 if (ClassUnloading) {
1028 keep_alive_oops_do(f, must_claim);
1029 } else {
1030 oops_do(f, must_claim);
1031 }
1032 }
1033
1034 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1035 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1036 cl->do_cld(cld);
1037 }
1038 }
1039
1040 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1041 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1042 // Only walk the head until any clds not purged from prior unloading
1043 // (CMS doesn't purge right away).
1044 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1045 assert(cld->is_unloading(), "invariant");
1046 cl->do_cld(cld);
1047 }
1048 }
1049
1050 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1051 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1052 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1053 if (closure != NULL) {
1054 closure->do_cld(cld);
1055 }
1056 }
1057 }
1058
1059 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1060 roots_cld_do(cl, NULL);
1061 }
1062
1063 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1064 if (ClassUnloading) {
1065 keep_alive_cld_do(cl);
1066 } else {
1067 cld_do(cl);
1068 }
1069 }
1070
1071 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1072 Thread* thread = Thread::current();
1073 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1074 Handle holder(thread, cld->holder_phantom());
1075 cld->classes_do(klass_closure);
1076 }
1077 }
1078
1079 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1080 Thread* thread = Thread::current();
1081 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1082 Handle holder(thread, cld->holder_phantom());
1083 cld->classes_do(f);
1084 }
1085 }
1086
1087 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1088 Thread* thread = Thread::current();
1089 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1090 Handle holder(thread, cld->holder_phantom());
1091 cld->methods_do(f);
1092 }
1093 }
1094
1095 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1096 assert_locked_or_safepoint(Module_lock);
1097 Thread* thread = Thread::current();
1098 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1099 Handle holder(thread, cld->holder_phantom());
1100 cld->modules_do(f);
1101 }
1102 }
1103
1104 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1105 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1106 // Only walk the head until any clds not purged from prior unloading
1107 // (CMS doesn't purge right away).
1108 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1109 assert(cld->is_unloading(), "invariant");
1110 cld->modules_do(f);
1111 }
1112 }
1113
1114 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1115 assert_locked_or_safepoint(Module_lock);
1116 Thread* thread = Thread::current();
1117 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1118 Handle holder(thread, cld->holder_phantom());
1119 cld->packages_do(f);
1120 }
1121 }
1122
1123 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1124 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1125 // Only walk the head until any clds not purged from prior unloading
1126 // (CMS doesn't purge right away).
1127 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1128 assert(cld->is_unloading(), "invariant");
1129 cld->packages_do(f);
1130 }
1131 }
1132
1133 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1134 Thread* thread = Thread::current();
1135 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1136 Handle holder(thread, cld->holder_phantom());
1137 cld->loaded_classes_do(klass_closure);
1138 }
1139 }
1140
1141 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1142 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1143 // Only walk the head until any clds not purged from prior unloading
1144 // (CMS doesn't purge right away).
1145 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1146 assert(cld->is_unloading(), "invariant");
1147 cld->classes_do(f);
1148 }
1149 }
1150
1151 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1152 if (X->dictionary() != NULL)
1153
1154 // Walk classes in the loaded class dictionaries in various forms.
1155 // Only walks the classes defined in this class loader.
1156 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1157 Thread* thread = Thread::current();
1158 FOR_ALL_DICTIONARY(cld) {
1159 Handle holder(thread, cld->holder_phantom());
1160 cld->dictionary()->classes_do(f);
1161 }
1162 }
1163
1164 // Only walks the classes defined in this class loader.
1165 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1166 Thread* thread = Thread::current();
1167 FOR_ALL_DICTIONARY(cld) {
1168 Handle holder(thread, cld->holder_phantom());
1169 cld->dictionary()->classes_do(f, CHECK);
1170 }
1171 }
1172
1173 // Walks all entries in the dictionary including entries initiated by this class loader.
1174 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1175 Thread* thread = Thread::current();
1176 FOR_ALL_DICTIONARY(cld) {
1177 Handle holder(thread, cld->holder_phantom());
1178 cld->dictionary()->all_entries_do(f);
1179 }
1180 }
1181
1182 void ClassLoaderDataGraph::verify_dictionary() {
1183 FOR_ALL_DICTIONARY(cld) {
1184 cld->dictionary()->verify();
1185 }
1186 }
1187
1188 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1189 FOR_ALL_DICTIONARY(cld) {
1190 st->print("Dictionary for ");
1191 cld->print_value_on(st);
1192 st->cr();
1193 cld->dictionary()->print_on(st);
1194 st->cr();
1195 }
1196 }
1197
1198 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1199 FOR_ALL_DICTIONARY(cld) {
1200 ResourceMark rm;
1201 stringStream tempst;
1202 tempst.print("System Dictionary for %s", cld->loader_name());
1203 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1204 }
1205 }
1206
1207 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1208 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1209
1210 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1211
1212 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1213 ClassLoaderData* curr = _head;
1214 while (curr != _saved_head) {
1215 if (!curr->claimed()) {
1216 array->push(curr);
1217 LogTarget(Debug, class, loader, data) lt;
1218 if (lt.is_enabled()) {
1219 LogStream ls(lt);
1220 ls.print("found new CLD: ");
1221 curr->print_value_on(&ls);
1222 ls.cr();
1223 }
1224 }
1225
1226 curr = curr->_next;
1227 }
1228
1229 return array;
1230 }
1231
1232 #ifndef PRODUCT
1233 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1234 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1235 if (loader_data == data) {
1236 return true;
1237 }
1238 }
1239
1240 return false;
1241 }
1242 #endif // PRODUCT
1243
1244
1245 // Move class loader data from main list to the unloaded list for unloading
1246 // and deallocation later.
1247 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1248 bool clean_previous_versions) {
1249
1250 ClassLoaderData* data = _head;
1251 ClassLoaderData* prev = NULL;
1252 bool seen_dead_loader = false;
1253 int loaders_processed = 0;
1254 int loaders_removed = 0;
1255
1256 // Mark metadata seen on the stack only so we can delete unneeded entries.
1257 // Only walk all metadata, including the expensive code cache walk, for Full GC
1258 // and only if class redefinition and if there's previous versions of
1259 // Klasses to delete.
1260 bool walk_all_metadata = clean_previous_versions &&
1261 JvmtiExport::has_redefined_a_class() &&
1262 InstanceKlass::has_previous_versions_and_reset();
1263 MetadataOnStackMark md_on_stack(walk_all_metadata);
1264
1265 // Save previous _unloading pointer for CMS which may add to unloading list before
1266 // purging and we don't want to rewalk the previously unloaded class loader data.
1267 _saved_unloading = _unloading;
1268
1269 data = _head;
1270 while (data != NULL) {
1271 if (data->is_alive()) {
1272 // clean metaspace
1273 if (walk_all_metadata) {
1274 data->classes_do(InstanceKlass::purge_previous_versions);
1275 }
1276 data->free_deallocate_list();
1277 prev = data;
1278 data = data->next();
1279 loaders_processed++;
1280 continue;
1281 }
1282 seen_dead_loader = true;
1283 loaders_removed++;
1284 ClassLoaderData* dead = data;
1285 dead->unload();
1286 data = data->next();
1287 // Remove from loader list.
1288 // This class loader data will no longer be found
1289 // in the ClassLoaderDataGraph.
1290 if (prev != NULL) {
1291 prev->set_next(data);
1292 } else {
1293 assert(dead == _head, "sanity check");
1294 _head = data;
1295 }
1296 dead->set_next(_unloading);
1297 _unloading = dead;
1298 }
1299
1300 if (seen_dead_loader) {
1301 data = _head;
1302 while (data != NULL) {
1303 // Remove entries in the dictionary of live class loader that have
1304 // initiated loading classes in a dead class loader.
1305 if (data->dictionary() != NULL) {
1306 data->dictionary()->do_unloading(is_alive_closure);
1307 }
1308 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1309 // lists to determine if there are modules on those lists that are now
1310 // dead and should be removed. A module's life cycle is equivalent
1311 // to its defining class loader's life cycle. Since a module is
1312 // considered dead if its class loader is dead, these walks must
1313 // occur after each class loader's aliveness is determined.
1314 if (data->packages() != NULL) {
1315 data->packages()->purge_all_package_exports();
1316 }
1317 if (data->modules_defined()) {
1318 data->modules()->purge_all_module_reads();
1319 }
1320 data = data->next();
1321 }
1322
1323 post_class_unload_events();
1324 }
1325
1326 log_debug(class, loader, data)("do_unloading: loaders processed %d, loaders removed %d", loaders_processed, loaders_removed);
1327
1328 return seen_dead_loader;
1329 }
1330
1331 void ClassLoaderDataGraph::purge() {
1332 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1333 ClassLoaderData* list = _unloading;
1334 _unloading = NULL;
1335 ClassLoaderData* next = list;
1336 bool classes_unloaded = false;
1337 while (next != NULL) {
1338 ClassLoaderData* purge_me = next;
1339 next = purge_me->next();
1340 delete purge_me;
1341 classes_unloaded = true;
1342 }
1343 if (classes_unloaded) {
1344 Metaspace::purge();
1345 set_metaspace_oom(false);
1346 }
1347 }
1348
1349 int ClassLoaderDataGraph::resize_if_needed() {
1350 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1351 int resized = 0;
1352 if (Dictionary::does_any_dictionary_needs_resizing()) {
1353 FOR_ALL_DICTIONARY(cld) {
1354 if (cld->dictionary()->resize_if_needed()) {
1355 resized++;
1356 }
1357 }
1358 }
1359 return resized;
1360 }
1361
1362 void ClassLoaderDataGraph::post_class_unload_events() {
1363 #if INCLUDE_TRACE
1364 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1365 if (Tracing::enabled()) {
1366 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1367 assert(_unloading != NULL, "need class loader data unload list!");
1368 _class_unload_time = Ticks::now();
1369 classes_unloading_do(&class_unload_event);
1370 }
1371 Tracing::on_unloading_classes();
1372 }
1373 #endif
1374 }
1375
1376 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1377 : _next_klass(NULL) {
1378 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1379 Klass* klass = NULL;
1380
1381 // Find the first klass in the CLDG.
1382 while (cld != NULL) {
1383 assert_locked_or_safepoint(cld->metaspace_lock());
1384 klass = cld->_klasses;
1385 if (klass != NULL) {
1386 _next_klass = klass;
1387 return;
1388 }
1389 cld = cld->next();
1390 }
1391 }
1392
1393 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1394 Klass* next = klass->next_link();
1395 if (next != NULL) {
1396 return next;
1397 }
1398
1399 // No more klasses in the current CLD. Time to find a new CLD.
1400 ClassLoaderData* cld = klass->class_loader_data();
1401 assert_locked_or_safepoint(cld->metaspace_lock());
1402 while (next == NULL) {
1403 cld = cld->next();
1404 if (cld == NULL) {
1405 break;
1406 }
1407 next = cld->_klasses;
1408 }
1409
1410 return next;
1411 }
1412
1413 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1414 Klass* head = _next_klass;
1415
1416 while (head != NULL) {
1417 Klass* next = next_klass_in_cldg(head);
1418
1419 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1420
1421 if (old_head == head) {
1422 return head; // Won the CAS.
1423 }
1424
1425 head = old_head;
1426 }
1427
1428 // Nothing more for the iterator to hand out.
1429 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1430 return NULL;
1431 }
1432
1433 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1434 _data = ClassLoaderDataGraph::_head;
1435 }
1436
1437 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1438
1439 #ifndef PRODUCT
1440 // callable from debugger
1441 extern "C" int print_loader_data_graph() {
1442 ResourceMark rm;
1443 ClassLoaderDataGraph::print_on(tty);
1444 return 0;
1445 }
1446
1447 void ClassLoaderDataGraph::verify() {
1448 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1449 data->verify();
1450 }
1451 }
1452
1453 void ClassLoaderDataGraph::print_on(outputStream * const out) {
1454 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1455 data->print_on(out);
1456 }
1457 }
1458 #endif // PRODUCT
1459
1460 #if INCLUDE_TRACE
1461
1462 Ticks ClassLoaderDataGraph::_class_unload_time;
1463
1464 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1465 assert(k != NULL, "invariant");
1466
1467 // post class unload event
1468 EventClassUnload event(UNTIMED);
1469 event.set_endtime(_class_unload_time);
1470 event.set_unloadedClass(k);
1471 event.set_definingClassLoader(k->class_loader_data());
1472 event.commit();
1473 }
1474
1475 #endif // INCLUDE_TRACE