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/symbolTable.hpp"
58 #include "classfile/systemDictionary.hpp"
59 #include "logging/log.hpp"
60 #include "logging/logStream.hpp"
61 #include "memory/allocation.inline.hpp"
62 #include "memory/metadataFactory.hpp"
63 #include "memory/metaspaceShared.hpp"
64 #include "memory/resourceArea.hpp"
65 #include "memory/universe.hpp"
66 #include "oops/access.inline.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "oops/oopHandle.inline.hpp"
69 #include "oops/weakHandle.inline.hpp"
70 #include "runtime/atomic.hpp"
71 #include "runtime/handles.inline.hpp"
72 #include "runtime/mutex.hpp"
73 #include "runtime/orderAccess.hpp"
74 #include "runtime/safepoint.hpp"
75 #include "runtime/safepointVerifiers.hpp"
76 #include "utilities/growableArray.hpp"
77 #include "utilities/macros.hpp"
78 #include "utilities/ostream.hpp"
79 #include "utilities/ticks.hpp"
80 #if INCLUDE_JFR
81 #include "jfr/jfr.hpp"
82 #include "jfr/jfrEvents.hpp"
83 #endif
84
85 volatile size_t ClassLoaderDataGraph::_num_array_classes = 0;
86 volatile size_t ClassLoaderDataGraph::_num_instance_classes = 0;
87
88 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
89
90 void ClassLoaderData::init_null_class_loader_data() {
91 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
92 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
93
94 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
95 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
96 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
97
98 LogTarget(Debug, class, loader, data) lt;
99 if (lt.is_enabled()) {
100 ResourceMark rm;
101 LogStream ls(lt);
102 ls.print("create ");
103 _the_null_class_loader_data->print_value_on(&ls);
104 ls.cr();
105 }
106 }
107
108 // JFR and logging support so that the name and klass are available after the
109 // class_loader oop is no longer alive, during unloading.
110 void ClassLoaderData::initialize_name_and_klass(Handle class_loader) {
111 _class_loader_klass = class_loader->klass();
112 oop class_loader_name = java_lang_ClassLoader::name(class_loader());
113 if (class_loader_name != NULL) {
114 Thread* THREAD = Thread::current();
115 ResourceMark rm(THREAD);
116 const char* class_loader_instance_name =
117 java_lang_String::as_utf8_string(class_loader_name);
118
119 if (class_loader_instance_name != NULL && class_loader_instance_name[0] != '\0') {
120 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore.
121 _class_loader_name = SymbolTable::new_symbol(class_loader_instance_name, CATCH);
122 }
123 }
124 }
125
126 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous) :
127 _is_anonymous(is_anonymous),
128 // An anonymous class loader data doesn't have anything to keep
129 // it from being unloaded during parsing of the anonymous class.
130 // The null-class-loader should always be kept alive.
131 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
132 _metaspace(NULL), _unloading(false), _klasses(NULL),
133 _modules(NULL), _packages(NULL), _unnamed_module(NULL), _dictionary(NULL),
134 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false),
135 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
136 _next(NULL),
137 _class_loader_klass(NULL), _class_loader_name(NULL),
138 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
139 Monitor::_safepoint_check_never)) {
140
141 if (!h_class_loader.is_null()) {
142 _class_loader = _handles.add(h_class_loader());
143 }
144
145 if (!is_anonymous) {
146 // The holder is initialized later for anonymous classes, and before calling anything
147 // that call class_loader().
148 initialize_holder(h_class_loader);
149
150 // A ClassLoaderData created solely for an anonymous class should never have a
151 // ModuleEntryTable or PackageEntryTable created for it. The defining package
152 // and module for an anonymous class will be found in its host class.
153 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
154 if (h_class_loader.is_null()) {
155 // Create unnamed module for boot loader
156 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
157 } else {
158 // Create unnamed module for all other loaders
159 _unnamed_module = ModuleEntry::create_unnamed_module(this);
160 }
161 _dictionary = create_dictionary();
162 }
163
164 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
165
166 JFR_ONLY(INIT_ID(this);)
167 }
168
169 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
170 Chunk* c = _head;
171 while (c != NULL) {
172 Chunk* next = c->_next;
173 delete c;
174 c = next;
175 }
176 }
177
178 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
179 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
180 Chunk* next = new Chunk(_head);
181 OrderAccess::release_store(&_head, next);
182 }
183 oop* handle = &_head->_data[_head->_size];
184 *handle = o;
185 OrderAccess::release_store(&_head->_size, _head->_size + 1);
186 return handle;
187 }
188
189 int ClassLoaderData::ChunkedHandleList::count() const {
190 int count = 0;
191 Chunk* chunk = _head;
192 while (chunk != NULL) {
193 count += chunk->_size;
194 chunk = chunk->_next;
195 }
196 return count;
197 }
198
199 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
200 for (juint i = 0; i < size; i++) {
201 if (c->_data[i] != NULL) {
202 f->do_oop(&c->_data[i]);
203 }
204 }
205 }
206
207 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
208 Chunk* head = OrderAccess::load_acquire(&_head);
209 if (head != NULL) {
210 // Must be careful when reading size of head
211 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
212 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
213 oops_do_chunk(f, c, c->_size);
214 }
215 }
216 }
217
218 class VerifyContainsOopClosure : public OopClosure {
219 oop _target;
220 bool _found;
221
222 public:
223 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
224
225 void do_oop(oop* p) {
226 if (p != NULL && oopDesc::equals(RawAccess<>::oop_load(p), _target)) {
227 _found = true;
228 }
229 }
230
231 void do_oop(narrowOop* p) {
232 // The ChunkedHandleList should not contain any narrowOop
233 ShouldNotReachHere();
234 }
235
236 bool found() const {
237 return _found;
238 }
239 };
240
241 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
242 VerifyContainsOopClosure cl(p);
243 oops_do(&cl);
244 return cl.found();
245 }
246
247 #ifndef PRODUCT
248 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
249 Chunk* chunk = _head;
250 while (chunk != NULL) {
251 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
252 return true;
253 }
254 chunk = chunk->_next;
255 }
256 return false;
257 }
258 #endif // PRODUCT
259
260 bool ClassLoaderData::claim() {
261 if (_claimed == 1) {
262 return false;
263 }
264
265 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
266 }
267
268 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
269 // while the class is being parsed, and if the class appears on the module fixup list.
270 // Due to the uniqueness that no other class shares the anonymous class' name or
271 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
272 // it is being defined, therefore _keep_alive is not volatile or atomic.
273 void ClassLoaderData::inc_keep_alive() {
274 if (is_anonymous()) {
275 assert(_keep_alive >= 0, "Invalid keep alive increment count");
276 _keep_alive++;
277 }
278 }
279
280 void ClassLoaderData::dec_keep_alive() {
281 if (is_anonymous()) {
282 assert(_keep_alive > 0, "Invalid keep alive decrement count");
283 _keep_alive--;
284 }
285 }
286
287 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
288 if (must_claim && !claim()) {
289 return;
290 }
291
292 // Only clear modified_oops after the ClassLoaderData is claimed.
293 if (clear_mod_oops) {
294 clear_modified_oops();
295 }
296
297 _handles.oops_do(f);
298 }
299
300 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
301 // Lock-free access requires load_acquire
302 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
303 klass_closure->do_klass(k);
304 assert(k != k->next_link(), "no loops!");
305 }
306 }
307
308 void ClassLoaderData::classes_do(void f(Klass * const)) {
309 // Lock-free access requires load_acquire
310 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
311 f(k);
312 assert(k != k->next_link(), "no loops!");
313 }
314 }
315
316 void ClassLoaderData::methods_do(void f(Method*)) {
317 // Lock-free access requires load_acquire
318 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
319 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
320 InstanceKlass::cast(k)->methods_do(f);
321 }
322 }
323 }
324
325 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
326 // Lock-free access requires load_acquire
327 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
328 // Do not filter ArrayKlass oops here...
329 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
330 klass_closure->do_klass(k);
331 }
332 }
333 }
334
335 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
336 // Lock-free access requires load_acquire
337 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
338 if (k->is_instance_klass()) {
339 f(InstanceKlass::cast(k));
340 }
341 assert(k != k->next_link(), "no loops!");
342 }
343 }
344
345 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
346 assert_locked_or_safepoint(Module_lock);
347 if (_unnamed_module != NULL) {
348 f(_unnamed_module);
349 }
350 if (_modules != NULL) {
351 for (int i = 0; i < _modules->table_size(); i++) {
352 for (ModuleEntry* entry = _modules->bucket(i);
353 entry != NULL;
354 entry = entry->next()) {
355 f(entry);
356 }
357 }
358 }
359 }
360
361 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
362 assert_locked_or_safepoint(Module_lock);
363 if (_packages != NULL) {
364 for (int i = 0; i < _packages->table_size(); i++) {
365 for (PackageEntry* entry = _packages->bucket(i);
366 entry != NULL;
367 entry = entry->next()) {
368 f(entry);
369 }
370 }
371 }
372 }
373
374 void ClassLoaderData::record_dependency(const Klass* k) {
375 assert(k != NULL, "invariant");
376
377 ClassLoaderData * const from_cld = this;
378 ClassLoaderData * const to_cld = k->class_loader_data();
379
380 // Do not need to record dependency if the dependency is to a class whose
381 // class loader data is never freed. (i.e. the dependency's class loader
382 // is one of the three builtin class loaders and the dependency is not
383 // anonymous.)
384 if (to_cld->is_permanent_class_loader_data()) {
385 return;
386 }
387
388 oop to;
389 if (to_cld->is_anonymous()) {
390 // Just return if an anonymous class is attempting to record a dependency
391 // to itself. (Note that every anonymous class has its own unique class
392 // loader data.)
393 if (to_cld == from_cld) {
394 return;
395 }
396 // Anonymous class dependencies are through the mirror.
397 to = k->java_mirror();
398 } else {
399 to = to_cld->class_loader();
400 oop from = from_cld->class_loader();
401
402 // Just return if this dependency is to a class with the same or a parent
403 // class_loader.
404 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) {
405 return; // this class loader is in the parent list, no need to add it.
406 }
407 }
408
409 // It's a dependency we won't find through GC, add it.
410 if (!_handles.contains(to)) {
411 NOT_PRODUCT(Atomic::inc(&_dependency_count));
412 LogTarget(Trace, class, loader, data) lt;
413 if (lt.is_enabled()) {
414 ResourceMark rm;
415 LogStream ls(lt);
416 ls.print("adding dependency from ");
417 print_value_on(&ls);
418 ls.print(" to ");
419 to_cld->print_value_on(&ls);
420 ls.cr();
421 }
422 Handle dependency(Thread::current(), to);
423 add_handle(dependency);
424 // Added a potentially young gen oop to the ClassLoaderData
425 record_modified_oops();
426 }
427 }
428
429
430 void ClassLoaderDataGraph::clear_claimed_marks() {
431 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
432 cld->clear_claimed();
433 }
434 }
435
436 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
437 {
438 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
439 Klass* old_value = _klasses;
440 k->set_next_link(old_value);
441 // Link the new item into the list, making sure the linked class is stable
442 // since the list can be walked without a lock
443 OrderAccess::release_store(&_klasses, k);
444 if (k->is_array_klass()) {
445 ClassLoaderDataGraph::inc_array_classes(1);
446 } else {
447 ClassLoaderDataGraph::inc_instance_classes(1);
448 }
449 }
450
451 if (publicize) {
452 LogTarget(Trace, class, loader, data) lt;
453 if (lt.is_enabled()) {
454 ResourceMark rm;
455 LogStream ls(lt);
456 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
457 print_value_on(&ls);
458 ls.cr();
459 }
460 }
461 }
462
463 // Class iterator used by the compiler. It gets some number of classes at
464 // a safepoint to decay invocation counters on the methods.
465 class ClassLoaderDataGraphKlassIteratorStatic {
466 ClassLoaderData* _current_loader_data;
467 Klass* _current_class_entry;
468 public:
469
470 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
471
472 InstanceKlass* try_get_next_class() {
473 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
474 size_t max_classes = ClassLoaderDataGraph::num_instance_classes();
475 assert(max_classes > 0, "should not be called with no instance classes");
476 for (size_t i = 0; i < max_classes; ) {
477
478 if (_current_class_entry != NULL) {
479 Klass* k = _current_class_entry;
480 _current_class_entry = _current_class_entry->next_link();
481
482 if (k->is_instance_klass()) {
483 InstanceKlass* ik = InstanceKlass::cast(k);
484 i++; // count all instance classes found
485 // Not yet loaded classes are counted in max_classes
486 // but only return loaded classes.
487 if (ik->is_loaded()) {
488 return ik;
489 }
490 }
491 } else {
492 // Go to next CLD
493 if (_current_loader_data != NULL) {
494 _current_loader_data = _current_loader_data->next();
495 }
496 // Start at the beginning
497 if (_current_loader_data == NULL) {
498 _current_loader_data = ClassLoaderDataGraph::_head;
499 }
500
501 _current_class_entry = _current_loader_data->klasses();
502 }
503 }
504 // Should never be reached unless all instance classes have failed or are not fully loaded.
505 // Caller handles NULL.
506 return NULL;
507 }
508
509 // If the current class for the static iterator is a class being unloaded or
510 // deallocated, adjust the current class.
511 void adjust_saved_class(ClassLoaderData* cld) {
512 if (_current_loader_data == cld) {
513 _current_loader_data = cld->next();
514 if (_current_loader_data != NULL) {
515 _current_class_entry = _current_loader_data->klasses();
516 } // else try_get_next_class will start at the head
517 }
518 }
519
520 void adjust_saved_class(Klass* klass) {
521 if (_current_class_entry == klass) {
522 _current_class_entry = klass->next_link();
523 }
524 }
525 };
526
527 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
528
529 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
530 return static_klass_iterator.try_get_next_class();
531 }
532
533
534 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
535 if (loader_or_mirror() != NULL) {
536 assert(_holder.is_null(), "never replace holders");
537 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror);
538 }
539 }
540
541 // Remove a klass from the _klasses list for scratch_class during redefinition
542 // or parsed class in the case of an error.
543 void ClassLoaderData::remove_class(Klass* scratch_class) {
544 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
545
546 // Adjust global class iterator.
547 static_klass_iterator.adjust_saved_class(scratch_class);
548
549 Klass* prev = NULL;
550 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
551 if (k == scratch_class) {
552 if (prev == NULL) {
553 _klasses = k->next_link();
554 } else {
555 Klass* next = k->next_link();
556 prev->set_next_link(next);
557 }
558
559 if (k->is_array_klass()) {
560 ClassLoaderDataGraph::dec_array_classes(1);
561 } else {
562 ClassLoaderDataGraph::dec_instance_classes(1);
563 }
564
565 return;
566 }
567 prev = k;
568 assert(k != k->next_link(), "no loops!");
569 }
570 ShouldNotReachHere(); // should have found this class!!
571 }
572
573 void ClassLoaderData::unload() {
574 _unloading = true;
575
576 LogTarget(Debug, class, loader, data) lt;
577 if (lt.is_enabled()) {
578 ResourceMark rm;
579 LogStream ls(lt);
580 ls.print("unload");
581 print_value_on(&ls);
582 ls.cr();
583 }
584
585 // Some items on the _deallocate_list need to free their C heap structures
586 // if they are not already on the _klasses list.
587 unload_deallocate_list();
588
589 // Tell serviceability tools these classes are unloading
590 // after erroneous classes are released.
591 classes_do(InstanceKlass::notify_unload_class);
592
593 // Clean up global class iterator for compiler
594 static_klass_iterator.adjust_saved_class(this);
595 }
596
597 ModuleEntryTable* ClassLoaderData::modules() {
598 // Lazily create the module entry table at first request.
599 // Lock-free access requires load_acquire.
600 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
601 if (modules == NULL) {
602 MutexLocker m1(Module_lock);
603 // Check if _modules got allocated while we were waiting for this lock.
604 if ((modules = _modules) == NULL) {
605 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
606
607 {
608 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
609 // Ensure _modules is stable, since it is examined without a lock
610 OrderAccess::release_store(&_modules, modules);
611 }
612 }
613 }
614 return modules;
615 }
616
617 const int _boot_loader_dictionary_size = 1009;
618 const int _default_loader_dictionary_size = 107;
619
620 Dictionary* ClassLoaderData::create_dictionary() {
621 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
622 int size;
623 bool resizable = false;
624 if (_the_null_class_loader_data == NULL) {
625 size = _boot_loader_dictionary_size;
626 resizable = true;
627 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
628 size = 1; // there's only one class in relection class loader and no initiated classes
629 } else if (is_system_class_loader_data()) {
630 size = _boot_loader_dictionary_size;
631 resizable = true;
632 } else {
633 size = _default_loader_dictionary_size;
634 resizable = true;
635 }
636 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) {
637 resizable = false;
638 }
639 return new Dictionary(this, size, resizable);
640 }
641
642 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
643 oop ClassLoaderData::holder_phantom() const {
644 // A klass that was previously considered dead can be looked up in the
645 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
646 // or a reachable object making it alive again. The SATB part of G1 needs
647 // to get notified about this potential resurrection, otherwise the marking
648 // might not find the object.
649 if (!_holder.is_null()) { // NULL class_loader
650 return _holder.resolve();
651 } else {
652 return NULL;
653 }
654 }
655
656 // Unloading support
657 bool ClassLoaderData::is_alive() const {
658 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
659 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
660
661 return alive;
662 }
663
664 class ReleaseKlassClosure: public KlassClosure {
665 private:
666 size_t _instance_class_released;
667 size_t _array_class_released;
668 public:
669 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
670
671 size_t instance_class_released() const { return _instance_class_released; }
672 size_t array_class_released() const { return _array_class_released; }
673
674 void do_klass(Klass* k) {
675 if (k->is_array_klass()) {
676 _array_class_released ++;
677 } else {
678 assert(k->is_instance_klass(), "Must be");
679 _instance_class_released ++;
680 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
681 }
682 }
683 };
684
685 ClassLoaderData::~ClassLoaderData() {
686 // Release C heap structures for all the classes.
687 ReleaseKlassClosure cl;
688 classes_do(&cl);
689
690 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
691 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
692
693 // Release the WeakHandle
694 _holder.release();
695
696 // Release C heap allocated hashtable for all the packages.
697 if (_packages != NULL) {
698 // Destroy the table itself
699 delete _packages;
700 _packages = NULL;
701 }
702
703 // Release C heap allocated hashtable for all the modules.
704 if (_modules != NULL) {
705 // Destroy the table itself
706 delete _modules;
707 _modules = NULL;
708 }
709
710 // Release C heap allocated hashtable for the dictionary
711 if (_dictionary != NULL) {
712 // Destroy the table itself
713 delete _dictionary;
714 _dictionary = NULL;
715 }
716
717 if (_unnamed_module != NULL) {
718 _unnamed_module->delete_unnamed_module();
719 _unnamed_module = NULL;
720 }
721
722 // release the metaspace
723 ClassLoaderMetaspace *m = _metaspace;
724 if (m != NULL) {
725 _metaspace = NULL;
726 delete m;
727 }
728 // Clear all the JNI handles for methods
729 // These aren't deallocated and are going to look like a leak, but that's
730 // needed because we can't really get rid of jmethodIDs because we don't
731 // know when native code is going to stop using them. The spec says that
732 // they're "invalid" but existing programs likely rely on their being
733 // NULL after class unloading.
734 if (_jmethod_ids != NULL) {
735 Method::clear_jmethod_ids(this);
736 }
737 // Delete lock
738 delete _metaspace_lock;
739
740 // Delete free list
741 if (_deallocate_list != NULL) {
742 delete _deallocate_list;
743 }
744 }
745
746 // Returns true if this class loader data is for the app class loader
747 // or a user defined system class loader. (Note that the class loader
748 // data may be anonymous.)
749 bool ClassLoaderData::is_system_class_loader_data() const {
750 return SystemDictionary::is_system_class_loader(class_loader());
751 }
752
753 // Returns true if this class loader data is for the platform class loader.
754 // (Note that the class loader data may be anonymous.)
755 bool ClassLoaderData::is_platform_class_loader_data() const {
756 return SystemDictionary::is_platform_class_loader(class_loader());
757 }
758
759 // Returns true if the class loader for this class loader data is one of
760 // the 3 builtin (boot application/system or platform) class loaders,
761 // including a user-defined system class loader. Note that if the class
762 // loader data is for an anonymous class then it may get freed by a GC
763 // even if its class loader is one of these loaders.
764 bool ClassLoaderData::is_builtin_class_loader_data() const {
765 return (is_boot_class_loader_data() ||
766 SystemDictionary::is_system_class_loader(class_loader()) ||
767 SystemDictionary::is_platform_class_loader(class_loader()));
768 }
769
770 // Returns true if this class loader data is a class loader data
771 // that is not ever freed by a GC. It must be one of the builtin
772 // class loaders and not anonymous.
773 bool ClassLoaderData::is_permanent_class_loader_data() const {
774 return is_builtin_class_loader_data() && !is_anonymous();
775 }
776
777 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
778 // If the metaspace has not been allocated, create a new one. Might want
779 // to create smaller arena for Reflection class loaders also.
780 // The reason for the delayed allocation is because some class loaders are
781 // simply for delegating with no metadata of their own.
782 // Lock-free access requires load_acquire.
783 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
784 if (metaspace == NULL) {
785 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
786 // Check if _metaspace got allocated while we were waiting for this lock.
787 if ((metaspace = _metaspace) == NULL) {
788 if (this == the_null_class_loader_data()) {
789 assert (class_loader() == NULL, "Must be");
790 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
791 } else if (is_anonymous()) {
792 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
793 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
794 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
795 } else {
796 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
797 }
798 // Ensure _metaspace is stable, since it is examined without a lock
799 OrderAccess::release_store(&_metaspace, metaspace);
800 }
801 }
802 return metaspace;
803 }
804
805 OopHandle ClassLoaderData::add_handle(Handle h) {
806 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
807 record_modified_oops();
808 return OopHandle(_handles.add(h()));
809 }
810
811 void ClassLoaderData::remove_handle(OopHandle h) {
812 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
813 oop* ptr = h.ptr_raw();
814 if (ptr != NULL) {
815 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
816 // This root is not walked in safepoints, and hence requires an appropriate
817 // decorator that e.g. maintains the SATB invariant in SATB collectors.
818 NativeAccess<IN_CONCURRENT_ROOT>::oop_store(ptr, oop(NULL));
819 }
820 }
821
822 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
823 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
824 if (dest.resolve() != NULL) {
825 return;
826 } else {
827 dest = _handles.add(h());
828 }
829 }
830
831 // Add this metadata pointer to be freed when it's safe. This is only during
832 // class unloading because Handles might point to this metadata field.
833 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
834 // Metadata in shared region isn't deleted.
835 if (!m->is_shared()) {
836 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
837 if (_deallocate_list == NULL) {
838 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
839 }
840 _deallocate_list->append_if_missing(m);
841 }
842 }
843
844 // Deallocate free metadata on the free list. How useful the PermGen was!
845 void ClassLoaderData::free_deallocate_list() {
846 // Don't need lock, at safepoint
847 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
848 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
849 if (_deallocate_list == NULL) {
850 return;
851 }
852 // Go backwards because this removes entries that are freed.
853 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
854 Metadata* m = _deallocate_list->at(i);
855 if (!m->on_stack()) {
856 _deallocate_list->remove_at(i);
857 // There are only three types of metadata that we deallocate directly.
858 // Cast them so they can be used by the template function.
859 if (m->is_method()) {
860 MetadataFactory::free_metadata(this, (Method*)m);
861 } else if (m->is_constantPool()) {
862 MetadataFactory::free_metadata(this, (ConstantPool*)m);
863 } else if (m->is_klass()) {
864 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
865 } else {
866 ShouldNotReachHere();
867 }
868 } else {
869 // Metadata is alive.
870 // If scratch_class is on stack then it shouldn't be on this list!
871 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
872 "scratch classes on this list should be dead");
873 // Also should assert that other metadata on the list was found in handles.
874 }
875 }
876 }
877
878 // This is distinct from free_deallocate_list. For class loader data that are
879 // unloading, this frees the C heap memory for items on the list, and unlinks
880 // scratch or error classes so that unloading events aren't triggered for these
881 // classes. The metadata is removed with the unloading metaspace.
882 // There isn't C heap memory allocated for methods, so nothing is done for them.
883 void ClassLoaderData::unload_deallocate_list() {
884 // Don't need lock, at safepoint
885 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
886 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
887 if (_deallocate_list == NULL) {
888 return;
889 }
890 // Go backwards because this removes entries that are freed.
891 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
892 Metadata* m = _deallocate_list->at(i);
893 assert (!m->on_stack(), "wouldn't be unloading if this were so");
894 _deallocate_list->remove_at(i);
895 if (m->is_constantPool()) {
896 ((ConstantPool*)m)->release_C_heap_structures();
897 } else if (m->is_klass()) {
898 InstanceKlass* ik = (InstanceKlass*)m;
899 // also releases ik->constants() C heap memory
900 InstanceKlass::release_C_heap_structures(ik);
901 // Remove the class so unloading events aren't triggered for
902 // this class (scratch or error class) in do_unloading().
903 remove_class(ik);
904 }
905 }
906 }
907
908 // These anonymous class loaders are to contain classes used for JSR292
909 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(Handle loader) {
910 // Add a new class loader data to the graph.
911 return ClassLoaderDataGraph::add(loader, true);
912 }
913
914 const char* ClassLoaderData::loader_name() const {
915 if (is_unloading()) {
916 if (_class_loader_klass == NULL) {
917 return "<bootloader>";
918 } else if (_class_loader_name != NULL) {
919 return _class_loader_name->as_C_string();
920 } else {
921 return _class_loader_klass->name()->as_C_string();
922 }
923 } else {
924 // Handles null class loader
925 return SystemDictionary::loader_name(class_loader());
926 }
927 }
928
929
930 void ClassLoaderData::print_value_on(outputStream* out) const {
931 if (!is_unloading() && class_loader() != NULL) {
932 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
933 class_loader()->print_value_on(out); // includes loader_name() and address of class loader instance
934 } else {
935 // loader data: 0xsomeaddr of <bootloader>
936 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name());
937 }
938 if (is_anonymous()) {
939 out->print(" anonymous");
940 }
941 }
942
943 #ifndef PRODUCT
944 void ClassLoaderData::print_on(outputStream* out) const {
945 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
946 p2i(this), p2i(_class_loader.ptr_raw()), loader_name());
947 if (is_anonymous()) out->print(" anonymous");
948 if (claimed()) out->print(" claimed");
949 if (is_unloading()) out->print(" unloading");
950 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
951
952 if (_jmethod_ids != NULL) {
953 Method::print_jmethod_ids(this, out);
954 }
955 out->print(" handles count %d", _handles.count());
956 out->print(" dependencies %d", _dependency_count);
957 out->print_cr("}");
958 }
959 #endif // PRODUCT
960
961 void ClassLoaderData::verify() {
962 assert_locked_or_safepoint(_metaspace_lock);
963 oop cl = class_loader();
964
965 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
966 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
967
968 // Verify the integrity of the allocated space.
969 if (metaspace_or_null() != NULL) {
970 metaspace_or_null()->verify();
971 }
972
973 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
974 guarantee(k->class_loader_data() == this, "Must be the same");
975 k->verify();
976 assert(k != k->next_link(), "no loops!");
977 }
978 }
979
980 bool ClassLoaderData::contains_klass(Klass* klass) {
981 // Lock-free access requires load_acquire
982 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
983 if (k == klass) return true;
984 }
985 return false;
986 }
987
988
989 // GC root of class loader data created.
990 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
991 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
992 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
993 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
994
995 bool ClassLoaderDataGraph::_should_purge = false;
996 bool ClassLoaderDataGraph::_metaspace_oom = false;
997
998 // Add a new class loader data node to the list. Assign the newly created
999 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
1000 ClassLoaderData* ClassLoaderDataGraph::add_to_graph(Handle loader, bool is_anonymous) {
1001 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
1002 // ClassLoaderData in the graph since the CLD
1003 // contains oops in _handles that must be walked.
1004
1005 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous);
1006
1007 if (!is_anonymous) {
1008 // First, Atomically set it
1009 ClassLoaderData* old = java_lang_ClassLoader::cmpxchg_loader_data(cld, loader(), NULL);
1010 if (old != NULL) {
1011 delete cld;
1012 // Returns the data.
1013 return old;
1014 }
1015 }
1016
1017 // We won the race, and therefore the task of adding the data to the list of
1018 // class loader data
1019 ClassLoaderData** list_head = &_head;
1020 ClassLoaderData* next = _head;
1021
1022 do {
1023 cld->set_next(next);
1024 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next);
1025 if (exchanged == next) {
1026 LogTarget(Debug, class, loader, data) lt;
1027 if (lt.is_enabled()) {
1028 ResourceMark rm;
1029 LogStream ls(lt);
1030 ls.print("create ");
1031 cld->print_value_on(&ls);
1032 ls.cr();
1033 }
1034 return cld;
1035 }
1036 next = exchanged;
1037 } while (true);
1038 }
1039
1040 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous) {
1041 ClassLoaderData* loader_data = add_to_graph(loader, is_anonymous);
1042 // Initialize name and class after the loader data is added to the CLDG
1043 // because adding the Symbol for the name might safepoint.
1044 if (loader.not_null()) {
1045 loader_data->initialize_name_and_klass(loader);
1046 }
1047 return loader_data;
1048 }
1049
1050 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1051 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1052 cld->oops_do(f, must_claim);
1053 }
1054 }
1055
1056 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1057 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1058 if (cld->keep_alive()) {
1059 cld->oops_do(f, must_claim);
1060 }
1061 }
1062 }
1063
1064 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1065 if (ClassUnloading) {
1066 keep_alive_oops_do(f, must_claim);
1067 } else {
1068 oops_do(f, must_claim);
1069 }
1070 }
1071
1072 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1073 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1074 cl->do_cld(cld);
1075 }
1076 }
1077
1078 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1079 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1080 // Only walk the head until any clds not purged from prior unloading
1081 // (CMS doesn't purge right away).
1082 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1083 assert(cld->is_unloading(), "invariant");
1084 cl->do_cld(cld);
1085 }
1086 }
1087
1088 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1089 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1090 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1091 if (closure != NULL) {
1092 closure->do_cld(cld);
1093 }
1094 }
1095 }
1096
1097 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1098 roots_cld_do(cl, NULL);
1099 }
1100
1101 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1102 if (ClassUnloading) {
1103 keep_alive_cld_do(cl);
1104 } else {
1105 cld_do(cl);
1106 }
1107 }
1108
1109 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1110 Thread* thread = Thread::current();
1111 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1112 Handle holder(thread, cld->holder_phantom());
1113 cld->classes_do(klass_closure);
1114 }
1115 }
1116
1117 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1118 Thread* thread = Thread::current();
1119 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1120 Handle holder(thread, cld->holder_phantom());
1121 cld->classes_do(f);
1122 }
1123 }
1124
1125 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1126 Thread* thread = Thread::current();
1127 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1128 Handle holder(thread, cld->holder_phantom());
1129 cld->methods_do(f);
1130 }
1131 }
1132
1133 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1134 assert_locked_or_safepoint(Module_lock);
1135 Thread* thread = Thread::current();
1136 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1137 Handle holder(thread, cld->holder_phantom());
1138 cld->modules_do(f);
1139 }
1140 }
1141
1142 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1143 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1144 // Only walk the head until any clds not purged from prior unloading
1145 // (CMS doesn't purge right away).
1146 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1147 assert(cld->is_unloading(), "invariant");
1148 cld->modules_do(f);
1149 }
1150 }
1151
1152 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1153 assert_locked_or_safepoint(Module_lock);
1154 Thread* thread = Thread::current();
1155 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1156 Handle holder(thread, cld->holder_phantom());
1157 cld->packages_do(f);
1158 }
1159 }
1160
1161 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1162 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1163 // Only walk the head until any clds not purged from prior unloading
1164 // (CMS doesn't purge right away).
1165 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1166 assert(cld->is_unloading(), "invariant");
1167 cld->packages_do(f);
1168 }
1169 }
1170
1171 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1172 Thread* thread = Thread::current();
1173 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1174 Handle holder(thread, cld->holder_phantom());
1175 cld->loaded_classes_do(klass_closure);
1176 }
1177 }
1178
1179 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1180 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1181 // Only walk the head until any clds not purged from prior unloading
1182 // (CMS doesn't purge right away).
1183 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1184 assert(cld->is_unloading(), "invariant");
1185 cld->classes_do(f);
1186 }
1187 }
1188
1189 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1190 if (X->dictionary() != NULL)
1191
1192 // Walk classes in the loaded class dictionaries in various forms.
1193 // Only walks the classes defined in this class loader.
1194 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1195 Thread* thread = Thread::current();
1196 FOR_ALL_DICTIONARY(cld) {
1197 Handle holder(thread, cld->holder_phantom());
1198 cld->dictionary()->classes_do(f);
1199 }
1200 }
1201
1202 // Only walks the classes defined in this class loader.
1203 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1204 Thread* thread = Thread::current();
1205 FOR_ALL_DICTIONARY(cld) {
1206 Handle holder(thread, cld->holder_phantom());
1207 cld->dictionary()->classes_do(f, CHECK);
1208 }
1209 }
1210
1211 // Walks all entries in the dictionary including entries initiated by this class loader.
1212 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1213 Thread* thread = Thread::current();
1214 FOR_ALL_DICTIONARY(cld) {
1215 Handle holder(thread, cld->holder_phantom());
1216 cld->dictionary()->all_entries_do(f);
1217 }
1218 }
1219
1220 void ClassLoaderDataGraph::verify_dictionary() {
1221 FOR_ALL_DICTIONARY(cld) {
1222 cld->dictionary()->verify();
1223 }
1224 }
1225
1226 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1227 FOR_ALL_DICTIONARY(cld) {
1228 st->print("Dictionary for ");
1229 cld->print_value_on(st);
1230 st->cr();
1231 cld->dictionary()->print_on(st);
1232 st->cr();
1233 }
1234 }
1235
1236 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1237 FOR_ALL_DICTIONARY(cld) {
1238 ResourceMark rm;
1239 stringStream tempst;
1240 tempst.print("System Dictionary for %s", cld->loader_name());
1241 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1242 }
1243 }
1244
1245 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1246 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1247
1248 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1249
1250 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1251 ClassLoaderData* curr = _head;
1252 while (curr != _saved_head) {
1253 if (!curr->claimed()) {
1254 array->push(curr);
1255 LogTarget(Debug, class, loader, data) lt;
1256 if (lt.is_enabled()) {
1257 LogStream ls(lt);
1258 ls.print("found new CLD: ");
1259 curr->print_value_on(&ls);
1260 ls.cr();
1261 }
1262 }
1263
1264 curr = curr->_next;
1265 }
1266
1267 return array;
1268 }
1269
1270 #ifndef PRODUCT
1271 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1272 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1273 if (loader_data == data) {
1274 return true;
1275 }
1276 }
1277
1278 return false;
1279 }
1280 #endif // PRODUCT
1281
1282 #if INCLUDE_JFR
1283 static Ticks class_unload_time;
1284 static void post_class_unload_event(Klass* const k) {
1285 assert(k != NULL, "invariant");
1286 EventClassUnload event(UNTIMED);
1287 event.set_endtime(class_unload_time);
1288 event.set_unloadedClass(k);
1289 event.set_definingClassLoader(k->class_loader_data());
1290 event.commit();
1291 }
1292
1293 static void post_class_unload_events() {
1294 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1295 if (Jfr::is_enabled()) {
1296 if (EventClassUnload::is_enabled()) {
1297 class_unload_time = Ticks::now();
1298 ClassLoaderDataGraph::classes_unloading_do(&post_class_unload_event);
1299 }
1300 Jfr::on_unloading_classes();
1301 }
1302 }
1303 #endif // INCLUDE_JFR
1304
1305 // Move class loader data from main list to the unloaded list for unloading
1306 // and deallocation later.
1307 bool ClassLoaderDataGraph::do_unloading(bool clean_previous_versions) {
1308
1309 ClassLoaderData* data = _head;
1310 ClassLoaderData* prev = NULL;
1311 bool seen_dead_loader = false;
1312 uint loaders_processed = 0;
1313 uint loaders_removed = 0;
1314
1315 // Mark metadata seen on the stack only so we can delete unneeded entries.
1316 // Only walk all metadata, including the expensive code cache walk, for Full GC
1317 // and only if class redefinition and if there's previous versions of
1318 // Klasses to delete.
1319 bool walk_all_metadata = clean_previous_versions &&
1320 JvmtiExport::has_redefined_a_class() &&
1321 InstanceKlass::has_previous_versions_and_reset();
1322 MetadataOnStackMark md_on_stack(walk_all_metadata);
1323
1324 // Save previous _unloading pointer for CMS which may add to unloading list before
1325 // purging and we don't want to rewalk the previously unloaded class loader data.
1326 _saved_unloading = _unloading;
1327
1328 data = _head;
1329 while (data != NULL) {
1330 if (data->is_alive()) {
1331 // clean metaspace
1332 if (walk_all_metadata) {
1333 data->classes_do(InstanceKlass::purge_previous_versions);
1334 }
1335 data->free_deallocate_list();
1336 prev = data;
1337 data = data->next();
1338 loaders_processed++;
1339 continue;
1340 }
1341 seen_dead_loader = true;
1342 loaders_removed++;
1343 ClassLoaderData* dead = data;
1344 dead->unload();
1345 data = data->next();
1346 // Remove from loader list.
1347 // This class loader data will no longer be found
1348 // in the ClassLoaderDataGraph.
1349 if (prev != NULL) {
1350 prev->set_next(data);
1351 } else {
1352 assert(dead == _head, "sanity check");
1353 _head = data;
1354 }
1355 dead->set_next(_unloading);
1356 _unloading = dead;
1357 }
1358
1359 if (seen_dead_loader) {
1360 data = _head;
1361 while (data != NULL) {
1362 // Remove entries in the dictionary of live class loader that have
1363 // initiated loading classes in a dead class loader.
1364 if (data->dictionary() != NULL) {
1365 data->dictionary()->do_unloading();
1366 }
1367 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1368 // lists to determine if there are modules on those lists that are now
1369 // dead and should be removed. A module's life cycle is equivalent
1370 // to its defining class loader's life cycle. Since a module is
1371 // considered dead if its class loader is dead, these walks must
1372 // occur after each class loader's aliveness is determined.
1373 if (data->packages() != NULL) {
1374 data->packages()->purge_all_package_exports();
1375 }
1376 if (data->modules_defined()) {
1377 data->modules()->purge_all_module_reads();
1378 }
1379 data = data->next();
1380 }
1381 JFR_ONLY(post_class_unload_events();)
1382 }
1383
1384 log_debug(class, loader, data)("do_unloading: loaders processed %u, loaders removed %u", loaders_processed, loaders_removed);
1385
1386 return seen_dead_loader;
1387 }
1388
1389 void ClassLoaderDataGraph::purge() {
1390 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1391 ClassLoaderData* list = _unloading;
1392 _unloading = NULL;
1393 ClassLoaderData* next = list;
1394 bool classes_unloaded = false;
1395 while (next != NULL) {
1396 ClassLoaderData* purge_me = next;
1397 next = purge_me->next();
1398 delete purge_me;
1399 classes_unloaded = true;
1400 }
1401 if (classes_unloaded) {
1402 Metaspace::purge();
1403 set_metaspace_oom(false);
1404 }
1405 }
1406
1407 int ClassLoaderDataGraph::resize_if_needed() {
1408 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1409 int resized = 0;
1410 if (Dictionary::does_any_dictionary_needs_resizing()) {
1411 FOR_ALL_DICTIONARY(cld) {
1412 if (cld->dictionary()->resize_if_needed()) {
1413 resized++;
1414 }
1415 }
1416 }
1417 return resized;
1418 }
1419
1420 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1421 : _next_klass(NULL) {
1422 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1423 Klass* klass = NULL;
1424
1425 // Find the first klass in the CLDG.
1426 while (cld != NULL) {
1427 assert_locked_or_safepoint(cld->metaspace_lock());
1428 klass = cld->_klasses;
1429 if (klass != NULL) {
1430 _next_klass = klass;
1431 return;
1432 }
1433 cld = cld->next();
1434 }
1435 }
1436
1437 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1438 Klass* next = klass->next_link();
1439 if (next != NULL) {
1440 return next;
1441 }
1442
1443 // No more klasses in the current CLD. Time to find a new CLD.
1444 ClassLoaderData* cld = klass->class_loader_data();
1445 assert_locked_or_safepoint(cld->metaspace_lock());
1446 while (next == NULL) {
1447 cld = cld->next();
1448 if (cld == NULL) {
1449 break;
1450 }
1451 next = cld->_klasses;
1452 }
1453
1454 return next;
1455 }
1456
1457 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1458 Klass* head = _next_klass;
1459
1460 while (head != NULL) {
1461 Klass* next = next_klass_in_cldg(head);
1462
1463 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1464
1465 if (old_head == head) {
1466 return head; // Won the CAS.
1467 }
1468
1469 head = old_head;
1470 }
1471
1472 // Nothing more for the iterator to hand out.
1473 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1474 return NULL;
1475 }
1476
1477 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1478 _data = ClassLoaderDataGraph::_head;
1479 }
1480
1481 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1482
1483 #ifndef PRODUCT
1484 // callable from debugger
1485 extern "C" int print_loader_data_graph() {
1486 ResourceMark rm;
1487 ClassLoaderDataGraph::print_on(tty);
1488 return 0;
1489 }
1490
1491 void ClassLoaderDataGraph::verify() {
1492 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1493 data->verify();
1494 }
1495 }
1496
1497 void ClassLoaderDataGraph::print_on(outputStream * const out) {
1498 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1499 data->print_on(out);
1500 }
1501 }
1502 #endif // PRODUCT