1 /*
2 * Copyright (c) 2012, 2017, 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/gcLocker.hpp"
60 #include "logging/log.hpp"
61 #include "logging/logStream.hpp"
62 #include "memory/metadataFactory.hpp"
63 #include "memory/metaspaceShared.hpp"
64 #include "memory/oopFactory.hpp"
65 #include "memory/resourceArea.hpp"
66 #include "oops/access.inline.hpp"
67 #include "oops/objArrayOop.inline.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.hpp"
70 #include "runtime/javaCalls.hpp"
71 #include "runtime/jniHandles.hpp"
72 #include "runtime/mutex.hpp"
73 #include "runtime/orderAccess.hpp"
74 #include "runtime/safepoint.hpp"
75 #include "runtime/synchronizer.hpp"
76 #include "utilities/growableArray.hpp"
77 #include "utilities/macros.hpp"
78 #include "utilities/ostream.hpp"
79 #if INCLUDE_TRACE
80 #include "trace/tracing.hpp"
81 #endif
82
83 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
84
85 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
86 _class_loader(h_class_loader()),
87 _is_anonymous(is_anonymous),
88 // An anonymous class loader data doesn't have anything to keep
89 // it from being unloaded during parsing of the anonymous class.
90 // The null-class-loader should always be kept alive.
91 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
92 _metaspace(NULL), _unloading(false), _klasses(NULL),
93 _modules(NULL), _packages(NULL),
94 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false),
95 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
96 _next(NULL), _dependencies(dependencies),
97 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
98 Monitor::_safepoint_check_never)) {
99
100 // A ClassLoaderData created solely for an anonymous class should never have a
101 // ModuleEntryTable or PackageEntryTable created for it. The defining package
102 // and module for an anonymous class will be found in its host class.
103 if (!is_anonymous) {
104 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
105 if (h_class_loader.is_null()) {
106 // Create unnamed module for boot loader
107 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
108 } else {
109 // Create unnamed module for all other loaders
110 _unnamed_module = ModuleEntry::create_unnamed_module(this);
111 }
112 } else {
113 _unnamed_module = NULL;
114 }
115
116 if (!is_anonymous) {
117 _dictionary = create_dictionary();
118 } else {
119 _dictionary = NULL;
120 }
121 TRACE_INIT_ID(this);
122 }
123
124 void ClassLoaderData::init_dependencies(TRAPS) {
125 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
126 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
127 _dependencies.init(CHECK);
128 }
129
130 void ClassLoaderData::Dependencies::init(TRAPS) {
131 // Create empty dependencies array to add to. CMS requires this to be
132 // an oop so that it can track additions via card marks. We think.
133 _list_head = oopFactory::new_objectArray(2, CHECK);
134 }
135
136 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
137 Chunk* c = _head;
138 while (c != NULL) {
139 Chunk* next = c->_next;
140 delete c;
141 c = next;
142 }
143 }
144
145 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
146 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
147 Chunk* next = new Chunk(_head);
148 OrderAccess::release_store(&_head, next);
149 }
150 oop* handle = &_head->_data[_head->_size];
151 *handle = o;
152 OrderAccess::release_store(&_head->_size, _head->_size + 1);
153 return handle;
154 }
155
156 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
157 for (juint i = 0; i < size; i++) {
158 if (c->_data[i] != NULL) {
159 f->do_oop(&c->_data[i]);
160 }
161 }
162 }
163
164 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
165 Chunk* head = OrderAccess::load_acquire(&_head);
166 if (head != NULL) {
167 // Must be careful when reading size of head
168 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
169 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
170 oops_do_chunk(f, c, c->_size);
171 }
172 }
173 }
174
175 #ifdef ASSERT
176 class VerifyContainsOopClosure : public OopClosure {
177 oop* _target;
178 bool _found;
179
180 public:
181 VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {}
182
183 void do_oop(oop* p) {
184 if (p == _target) {
185 _found = true;
186 }
187 }
188
189 void do_oop(narrowOop* p) {
190 // The ChunkedHandleList should not contain any narrowOop
191 ShouldNotReachHere();
192 }
193
194 bool found() const {
195 return _found;
196 }
197 };
198
199 bool ClassLoaderData::ChunkedHandleList::contains(oop* p) {
200 VerifyContainsOopClosure cl(p);
201 oops_do(&cl);
202 return cl.found();
203 }
204 #endif // ASSERT
205
206 bool ClassLoaderData::claim() {
207 if (_claimed == 1) {
208 return false;
209 }
210
211 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
212 }
213
214 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
215 // while the class is being parsed, and if the class appears on the module fixup list.
216 // Due to the uniqueness that no other class shares the anonymous class' name or
217 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
218 // it is being defined, therefore _keep_alive is not volatile or atomic.
219 void ClassLoaderData::inc_keep_alive() {
220 if (is_anonymous()) {
221 assert(_keep_alive >= 0, "Invalid keep alive increment count");
222 _keep_alive++;
223 }
224 }
225
226 void ClassLoaderData::dec_keep_alive() {
227 if (is_anonymous()) {
228 assert(_keep_alive > 0, "Invalid keep alive decrement count");
229 _keep_alive--;
230 }
231 }
232
233 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
234 if (must_claim && !claim()) {
235 return;
236 }
237
238 // Only clear modified_oops after the ClassLoaderData is claimed.
239 if (clear_mod_oops) {
240 clear_modified_oops();
241 }
242
243 f->do_oop(&_class_loader);
244 _dependencies.oops_do(f);
245 _handles.oops_do(f);
246 }
247
248 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
249 f->do_oop((oop*)&_list_head);
250 }
251
252 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
253 // Lock-free access requires load_acquire
254 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
255 klass_closure->do_klass(k);
256 assert(k != k->next_link(), "no loops!");
257 }
258 }
259
260 void ClassLoaderData::classes_do(void f(Klass * const)) {
261 // Lock-free access requires load_acquire
262 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
263 f(k);
264 assert(k != k->next_link(), "no loops!");
265 }
266 }
267
268 void ClassLoaderData::methods_do(void f(Method*)) {
269 // Lock-free access requires load_acquire
270 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
271 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
272 InstanceKlass::cast(k)->methods_do(f);
273 }
274 }
275 }
276
277 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
278 // Lock-free access requires load_acquire
279 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
280 // Do not filter ArrayKlass oops here...
281 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
282 klass_closure->do_klass(k);
283 }
284 }
285 }
286
287 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
288 // Lock-free access requires load_acquire
289 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
290 if (k->is_instance_klass()) {
291 f(InstanceKlass::cast(k));
292 }
293 assert(k != k->next_link(), "no loops!");
294 }
295 }
296
297 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
298 assert_locked_or_safepoint(Module_lock);
299 if (_unnamed_module != NULL) {
300 f(_unnamed_module);
301 }
302 if (_modules != NULL) {
303 for (int i = 0; i < _modules->table_size(); i++) {
304 for (ModuleEntry* entry = _modules->bucket(i);
305 entry != NULL;
306 entry = entry->next()) {
307 f(entry);
308 }
309 }
310 }
311 }
312
313 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
314 assert_locked_or_safepoint(Module_lock);
315 if (_packages != NULL) {
316 for (int i = 0; i < _packages->table_size(); i++) {
317 for (PackageEntry* entry = _packages->bucket(i);
318 entry != NULL;
319 entry = entry->next()) {
320 f(entry);
321 }
322 }
323 }
324 }
325
326 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
327 assert(k != NULL, "invariant");
328
329 ClassLoaderData * const from_cld = this;
330 ClassLoaderData * const to_cld = k->class_loader_data();
331
332 // Dependency to the null class loader data doesn't need to be recorded
333 // because the null class loader data never goes away.
334 if (to_cld->is_the_null_class_loader_data()) {
335 return;
336 }
337
338 oop to;
339 if (to_cld->is_anonymous()) {
340 // Anonymous class dependencies are through the mirror.
341 to = k->java_mirror();
342 } else {
343 to = to_cld->class_loader();
344
345 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
346 // we still have to add it. The class_loader won't keep from_cld alive.
347 if (!from_cld->is_anonymous()) {
348 // Check that this dependency isn't from the same or parent class_loader
349 oop from = from_cld->class_loader();
350
351 oop curr = from;
352 while (curr != NULL) {
353 if (curr == to) {
354 return; // this class loader is in the parent list, no need to add it.
355 }
356 curr = java_lang_ClassLoader::parent(curr);
357 }
358 }
359 }
360
361 // It's a dependency we won't find through GC, add it. This is relatively rare
362 // Must handle over GC point.
363 Handle dependency(THREAD, to);
364 from_cld->_dependencies.add(dependency, CHECK);
365
366 // Added a potentially young gen oop to the ClassLoaderData
367 record_modified_oops();
368 }
369
370
371 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
372 // Check first if this dependency is already in the list.
373 // Save a pointer to the last to add to under the lock.
374 objArrayOop ok = _list_head;
375 objArrayOop last = NULL;
376 while (ok != NULL) {
377 last = ok;
378 if (ok->obj_at(0) == dependency()) {
379 // Don't need to add it
380 return;
381 }
382 ok = (objArrayOop)ok->obj_at(1);
383 }
384
385 // Must handle over GC points
386 assert (last != NULL, "dependencies should be initialized");
387 objArrayHandle last_handle(THREAD, last);
388
389 // Create a new dependency node with fields for (class_loader or mirror, next)
390 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
391 deps->obj_at_put(0, dependency());
392
393 // Must handle over GC points
394 objArrayHandle new_dependency(THREAD, deps);
395
396 // Add the dependency under lock
397 locked_add(last_handle, new_dependency, THREAD);
398 }
399
400 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
401 objArrayHandle new_dependency,
402 Thread* THREAD) {
403
404 // Have to lock and put the new dependency on the end of the dependency
405 // array so the card mark for CMS sees that this dependency is new.
406 // Can probably do this lock free with some effort.
407 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
408
409 oop loader_or_mirror = new_dependency->obj_at(0);
410
411 // Since the dependencies are only added, add to the end.
412 objArrayOop end = last_handle();
413 objArrayOop last = NULL;
414 while (end != NULL) {
415 last = end;
416 // check again if another thread added it to the end.
417 if (end->obj_at(0) == loader_or_mirror) {
418 // Don't need to add it
419 return;
420 }
421 end = (objArrayOop)end->obj_at(1);
422 }
423 assert (last != NULL, "dependencies should be initialized");
424 // fill in the first element with the oop in new_dependency.
425 if (last->obj_at(0) == NULL) {
426 last->obj_at_put(0, new_dependency->obj_at(0));
427 } else {
428 last->obj_at_put(1, new_dependency());
429 }
430 }
431
432 void ClassLoaderDataGraph::clear_claimed_marks() {
433 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
434 cld->clear_claimed();
435 }
436 }
437
438 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
439 {
440 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
441 Klass* old_value = _klasses;
442 k->set_next_link(old_value);
443 // Link the new item into the list, making sure the linked class is stable
444 // since the list can be walked without a lock
445 OrderAccess::release_store(&_klasses, k);
446 }
447
448 if (publicize && k->class_loader_data() != NULL) {
449 ResourceMark rm;
450 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
451 PTR_FORMAT " loader: " PTR_FORMAT " %s",
452 p2i(k),
453 k->external_name(),
454 p2i(k->class_loader_data()),
455 p2i((void *)k->class_loader()),
456 loader_name());
457 }
458 }
459
460 // Class iterator used by the compiler. It gets some number of classes at
461 // a safepoint to decay invocation counters on the methods.
462 class ClassLoaderDataGraphKlassIteratorStatic {
463 ClassLoaderData* _current_loader_data;
464 Klass* _current_class_entry;
465 public:
466
467 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
468
469 InstanceKlass* try_get_next_class() {
470 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
471 int max_classes = InstanceKlass::number_of_instance_classes();
472 assert(max_classes > 0, "should not be called with no instance classes");
473 for (int i = 0; i < max_classes; ) {
474
475 if (_current_class_entry != NULL) {
476 Klass* k = _current_class_entry;
477 _current_class_entry = _current_class_entry->next_link();
478
479 if (k->is_instance_klass()) {
480 InstanceKlass* ik = InstanceKlass::cast(k);
481 i++; // count all instance classes found
482 // Not yet loaded classes are counted in max_classes
483 // but only return loaded classes.
484 if (ik->is_loaded()) {
485 return ik;
486 }
487 }
488 } else {
489 // Go to next CLD
490 if (_current_loader_data != NULL) {
491 _current_loader_data = _current_loader_data->next();
492 }
493 // Start at the beginning
494 if (_current_loader_data == NULL) {
495 _current_loader_data = ClassLoaderDataGraph::_head;
496 }
497
498 _current_class_entry = _current_loader_data->klasses();
499 }
500 }
501 // Should never be reached unless all instance classes have failed or are not fully loaded.
502 // Caller handles NULL.
503 return NULL;
504 }
505
506 // If the current class for the static iterator is a class being unloaded or
507 // deallocated, adjust the current class.
508 void adjust_saved_class(ClassLoaderData* cld) {
509 if (_current_loader_data == cld) {
510 _current_loader_data = cld->next();
511 if (_current_loader_data != NULL) {
512 _current_class_entry = _current_loader_data->klasses();
513 } // else try_get_next_class will start at the head
514 }
515 }
516
517 void adjust_saved_class(Klass* klass) {
518 if (_current_class_entry == klass) {
519 _current_class_entry = klass->next_link();
520 }
521 }
522 };
523
524 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
525
526 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
527 return static_klass_iterator.try_get_next_class();
528 }
529
530
531 // Remove a klass from the _klasses list for scratch_class during redefinition
532 // or parsed class in the case of an error.
533 void ClassLoaderData::remove_class(Klass* scratch_class) {
534 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
535
536 // Adjust global class iterator.
537 static_klass_iterator.adjust_saved_class(scratch_class);
538
539 Klass* prev = NULL;
540 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
541 if (k == scratch_class) {
542 if (prev == NULL) {
543 _klasses = k->next_link();
544 } else {
545 Klass* next = k->next_link();
546 prev->set_next_link(next);
547 }
548 return;
549 }
550 prev = k;
551 assert(k != k->next_link(), "no loops!");
552 }
553 ShouldNotReachHere(); // should have found this class!!
554 }
555
556 void ClassLoaderData::unload() {
557 _unloading = true;
558
559 // Tell serviceability tools these classes are unloading
560 classes_do(InstanceKlass::notify_unload_class);
561
562 LogTarget(Debug, class, loader, data) lt;
563 if (lt.is_enabled()) {
564 ResourceMark rm;
565 LogStream ls(lt);
566 ls.print(": unload loader data " INTPTR_FORMAT, p2i(this));
567 ls.print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
568 loader_name());
569 if (is_anonymous()) {
570 ls.print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
571 }
572 ls.cr();
573 }
574
575 // In some rare cases items added to this list will not be freed elsewhere.
576 // To keep it simple, just free everything in it here.
577 free_deallocate_list();
578
579 // Clean up global class iterator for compiler
580 static_klass_iterator.adjust_saved_class(this);
581 }
582
583 ModuleEntryTable* ClassLoaderData::modules() {
584 // Lazily create the module entry table at first request.
585 // Lock-free access requires load_acquire.
586 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
587 if (modules == NULL) {
588 MutexLocker m1(Module_lock);
589 // Check if _modules got allocated while we were waiting for this lock.
590 if ((modules = _modules) == NULL) {
591 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
592
593 {
594 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
595 // Ensure _modules is stable, since it is examined without a lock
596 OrderAccess::release_store(&_modules, modules);
597 }
598 }
599 }
600 return modules;
601 }
602
603 const int _boot_loader_dictionary_size = 1009;
604 const int _default_loader_dictionary_size = 107;
605
606 Dictionary* ClassLoaderData::create_dictionary() {
607 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
608 int size;
609 bool resizable = false;
610 if (_the_null_class_loader_data == NULL) {
611 size = _boot_loader_dictionary_size;
612 resizable = true;
613 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
614 size = 1; // there's only one class in relection class loader and no initiated classes
615 } else if (is_system_class_loader_data()) {
616 size = _boot_loader_dictionary_size;
617 resizable = true;
618 } else {
619 size = _default_loader_dictionary_size;
620 resizable = true;
621 }
622 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) {
623 resizable = false;
624 }
625 return new Dictionary(this, size, resizable);
626 }
627
628 // Unloading support
629 oop ClassLoaderData::keep_alive_object() const {
630 assert_locked_or_safepoint(_metaspace_lock);
631 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
632 return is_anonymous() ? _klasses->java_mirror() : class_loader();
633 }
634
635 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
636 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
637 || is_alive_closure->do_object_b(keep_alive_object());
638
639 return alive;
640 }
641
642 ClassLoaderData::~ClassLoaderData() {
643 // Release C heap structures for all the classes.
644 classes_do(InstanceKlass::release_C_heap_structures);
645
646 // Release C heap allocated hashtable for all the packages.
647 if (_packages != NULL) {
648 // Destroy the table itself
649 delete _packages;
650 _packages = NULL;
651 }
652
653 // Release C heap allocated hashtable for all the modules.
654 if (_modules != NULL) {
655 // Destroy the table itself
656 delete _modules;
657 _modules = NULL;
658 }
659
660 // Release C heap allocated hashtable for the dictionary
661 if (_dictionary != NULL) {
662 // Destroy the table itself
663 delete _dictionary;
664 _dictionary = NULL;
665 }
666
667 if (_unnamed_module != NULL) {
668 _unnamed_module->delete_unnamed_module();
669 _unnamed_module = NULL;
670 }
671
672 // release the metaspace
673 Metaspace *m = _metaspace;
674 if (m != NULL) {
675 _metaspace = NULL;
676 delete m;
677 }
678 // Clear all the JNI handles for methods
679 // These aren't deallocated and are going to look like a leak, but that's
680 // needed because we can't really get rid of jmethodIDs because we don't
681 // know when native code is going to stop using them. The spec says that
682 // they're "invalid" but existing programs likely rely on their being
683 // NULL after class unloading.
684 if (_jmethod_ids != NULL) {
685 Method::clear_jmethod_ids(this);
686 }
687 // Delete lock
688 delete _metaspace_lock;
689
690 // Delete free list
691 if (_deallocate_list != NULL) {
692 delete _deallocate_list;
693 }
694 }
695
696 // Returns true if this class loader data is for the system class loader.
697 bool ClassLoaderData::is_system_class_loader_data() const {
698 return SystemDictionary::is_system_class_loader(class_loader());
699 }
700
701 // Returns true if this class loader data is for the platform class loader.
702 bool ClassLoaderData::is_platform_class_loader_data() const {
703 return SystemDictionary::is_platform_class_loader(class_loader());
704 }
705
706 // Returns true if this class loader data is one of the 3 builtin
707 // (boot, application/system or platform) class loaders. Note, the
708 // builtin loaders are not freed by a GC.
709 bool ClassLoaderData::is_builtin_class_loader_data() const {
710 return (is_the_null_class_loader_data() ||
711 SystemDictionary::is_system_class_loader(class_loader()) ||
712 SystemDictionary::is_platform_class_loader(class_loader()));
713 }
714
715 Metaspace* ClassLoaderData::metaspace_non_null() {
716 // If the metaspace has not been allocated, create a new one. Might want
717 // to create smaller arena for Reflection class loaders also.
718 // The reason for the delayed allocation is because some class loaders are
719 // simply for delegating with no metadata of their own.
720 // Lock-free access requires load_acquire.
721 Metaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
722 if (metaspace == NULL) {
723 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
724 // Check if _metaspace got allocated while we were waiting for this lock.
725 if ((metaspace = _metaspace) == NULL) {
726 if (this == the_null_class_loader_data()) {
727 assert (class_loader() == NULL, "Must be");
728 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
729 } else if (is_anonymous()) {
730 if (class_loader() != NULL) {
731 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
732 }
733 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
734 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
735 if (class_loader() != NULL) {
736 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
737 }
738 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
739 } else {
740 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
741 }
742 // Ensure _metaspace is stable, since it is examined without a lock
743 OrderAccess::release_store(&_metaspace, metaspace);
744 }
745 }
746 return metaspace;
747 }
748
749 OopHandle ClassLoaderData::add_handle(Handle h) {
750 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
751 record_modified_oops();
752 return OopHandle(_handles.add(h()));
753 }
754
755 void ClassLoaderData::remove_handle(OopHandle h) {
756 oop* ptr = h.ptr_raw();
757 if (ptr != NULL) {
758 assert(_handles.contains(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
759 // This root is not walked in safepoints, and hence requires an appropriate
760 // decorator that e.g. maintains the SATB invariant in SATB collectors.
761 RootAccess<IN_CONCURRENT_ROOT>::oop_store(ptr, oop(NULL));
762 }
763 }
764
765 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
766 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
767 if (dest.resolve() != NULL) {
768 return;
769 } else {
770 dest = _handles.add(h());
771 }
772 }
773
774 // Add this metadata pointer to be freed when it's safe. This is only during
775 // class unloading because Handles might point to this metadata field.
776 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
777 // Metadata in shared region isn't deleted.
778 if (!m->is_shared()) {
779 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
780 if (_deallocate_list == NULL) {
781 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
782 }
783 _deallocate_list->append_if_missing(m);
784 }
785 }
786
787 // Deallocate free metadata on the free list. How useful the PermGen was!
788 void ClassLoaderData::free_deallocate_list() {
789 // Don't need lock, at safepoint
790 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
791 if (_deallocate_list == NULL) {
792 return;
793 }
794 // Go backwards because this removes entries that are freed.
795 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
796 Metadata* m = _deallocate_list->at(i);
797 if (!m->on_stack()) {
798 _deallocate_list->remove_at(i);
799 // There are only three types of metadata that we deallocate directly.
800 // Cast them so they can be used by the template function.
801 if (m->is_method()) {
802 MetadataFactory::free_metadata(this, (Method*)m);
803 } else if (m->is_constantPool()) {
804 MetadataFactory::free_metadata(this, (ConstantPool*)m);
805 } else if (m->is_klass()) {
806 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
807 } else {
808 ShouldNotReachHere();
809 }
810 } else {
811 // Metadata is alive.
812 // If scratch_class is on stack then it shouldn't be on this list!
813 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
814 "scratch classes on this list should be dead");
815 // Also should assert that other metadata on the list was found in handles.
816 }
817 }
818 }
819
820 // These anonymous class loaders are to contain classes used for JSR292
821 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
822 // Add a new class loader data to the graph.
823 Handle lh(THREAD, loader);
824 return ClassLoaderDataGraph::add(lh, true, THREAD);
825 }
826
827 const char* ClassLoaderData::loader_name() {
828 // Handles null class loader
829 return SystemDictionary::loader_name(class_loader());
830 }
831
832 #ifndef PRODUCT
833 // Define to dump klasses
834 #undef CLD_DUMP_KLASSES
835
836 void ClassLoaderData::dump(outputStream * const out) {
837 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
838 p2i(this), p2i((void *)class_loader()),
839 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
840 if (claimed()) out->print(" claimed ");
841 if (is_unloading()) out->print(" unloading ");
842 out->cr();
843 if (metaspace_or_null() != NULL) {
844 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
845 metaspace_or_null()->dump(out);
846 } else {
847 out->print_cr("metaspace: NULL");
848 }
849
850 #ifdef CLD_DUMP_KLASSES
851 if (Verbose) {
852 Klass* k = _klasses;
853 while (k != NULL) {
854 out->print_cr("klass " PTR_FORMAT ", %s", p2i(k), k->name()->as_C_string());
855 assert(k != k->next_link(), "no loops!");
856 k = k->next_link();
857 }
858 }
859 #endif // CLD_DUMP_KLASSES
860 #undef CLD_DUMP_KLASSES
861 if (_jmethod_ids != NULL) {
862 Method::print_jmethod_ids(this, out);
863 }
864 out->print_cr("}");
865 }
866 #endif // PRODUCT
867
868 void ClassLoaderData::verify() {
869 assert_locked_or_safepoint(_metaspace_lock);
870 oop cl = class_loader();
871
872 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
873 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
874
875 // Verify the integrity of the allocated space.
876 if (metaspace_or_null() != NULL) {
877 metaspace_or_null()->verify();
878 }
879
880 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
881 guarantee(k->class_loader_data() == this, "Must be the same");
882 k->verify();
883 assert(k != k->next_link(), "no loops!");
884 }
885 }
886
887 bool ClassLoaderData::contains_klass(Klass* klass) {
888 // Lock-free access requires load_acquire
889 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
890 if (k == klass) return true;
891 }
892 return false;
893 }
894
895
896 // GC root of class loader data created.
897 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
898 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
899 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
900 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
901
902 bool ClassLoaderDataGraph::_should_purge = false;
903 bool ClassLoaderDataGraph::_metaspace_oom = false;
904
905 // Add a new class loader data node to the list. Assign the newly created
906 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
907 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
908 // We need to allocate all the oops for the ClassLoaderData before allocating the
909 // actual ClassLoaderData object.
910 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
911
912 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
913 // ClassLoaderData in the graph since the CLD
914 // contains unhandled oops
915
916 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
917
918
919 if (!is_anonymous) {
920 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
921 // First, Atomically set it
922 ClassLoaderData* old = Atomic::cmpxchg(cld, cld_addr, (ClassLoaderData*)NULL);
923 if (old != NULL) {
924 delete cld;
925 // Returns the data.
926 return old;
927 }
928 }
929
930 // We won the race, and therefore the task of adding the data to the list of
931 // class loader data
932 ClassLoaderData** list_head = &_head;
933 ClassLoaderData* next = _head;
934
935 do {
936 cld->set_next(next);
937 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next);
938 if (exchanged == next) {
939 LogTarget(Debug, class, loader, data) lt;
940 if (lt.is_enabled()) {
941 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
942 LogStream ls(lt);
943 print_creation(&ls, loader, cld, CHECK_NULL);
944 }
945 return cld;
946 }
947 next = exchanged;
948 } while (true);
949 }
950
951 void ClassLoaderDataGraph::print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS) {
952 Handle string;
953 if (loader.not_null()) {
954 // Include the result of loader.toString() in the output. This allows
955 // the user of the log to identify the class loader instance.
956 JavaValue result(T_OBJECT);
957 Klass* spec_klass = SystemDictionary::ClassLoader_klass();
958 JavaCalls::call_virtual(&result,
959 loader,
960 spec_klass,
961 vmSymbols::toString_name(),
962 vmSymbols::void_string_signature(),
963 CHECK);
964 assert(result.get_type() == T_OBJECT, "just checking");
965 string = Handle(THREAD, (oop)result.get_jobject());
966 }
967
968 ResourceMark rm;
969 out->print("create class loader data " INTPTR_FORMAT, p2i(cld));
970 out->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
971 cld->loader_name());
972
973 if (string.not_null()) {
974 out->print(": ");
975 java_lang_String::print(string(), out);
976 }
977 out->cr();
978 }
979
980
981 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
982 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
983 cld->oops_do(f, must_claim);
984 }
985 }
986
987 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
988 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
989 if (cld->keep_alive()) {
990 cld->oops_do(f, must_claim);
991 }
992 }
993 }
994
995 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
996 if (ClassUnloading) {
997 keep_alive_oops_do(f, must_claim);
998 } else {
999 oops_do(f, must_claim);
1000 }
1001 }
1002
1003 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1004 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1005 cl->do_cld(cld);
1006 }
1007 }
1008
1009 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1010 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1011 // Only walk the head until any clds not purged from prior unloading
1012 // (CMS doesn't purge right away).
1013 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1014 assert(cld->is_unloading(), "invariant");
1015 cl->do_cld(cld);
1016 }
1017 }
1018
1019 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1020 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1021 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1022 if (closure != NULL) {
1023 closure->do_cld(cld);
1024 }
1025 }
1026 }
1027
1028 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1029 roots_cld_do(cl, NULL);
1030 }
1031
1032 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1033 if (ClassUnloading) {
1034 keep_alive_cld_do(cl);
1035 } else {
1036 cld_do(cl);
1037 }
1038 }
1039
1040 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1041 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1042 cld->classes_do(klass_closure);
1043 }
1044 }
1045
1046 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1047 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1048 cld->classes_do(f);
1049 }
1050 }
1051
1052 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1053 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1054 cld->methods_do(f);
1055 }
1056 }
1057
1058 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1059 assert_locked_or_safepoint(Module_lock);
1060 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1061 cld->modules_do(f);
1062 }
1063 }
1064
1065 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1066 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1067 // Only walk the head until any clds not purged from prior unloading
1068 // (CMS doesn't purge right away).
1069 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1070 assert(cld->is_unloading(), "invariant");
1071 cld->modules_do(f);
1072 }
1073 }
1074
1075 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1076 assert_locked_or_safepoint(Module_lock);
1077 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1078 cld->packages_do(f);
1079 }
1080 }
1081
1082 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1083 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1084 // Only walk the head until any clds not purged from prior unloading
1085 // (CMS doesn't purge right away).
1086 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1087 assert(cld->is_unloading(), "invariant");
1088 cld->packages_do(f);
1089 }
1090 }
1091
1092 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1093 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1094 cld->loaded_classes_do(klass_closure);
1095 }
1096 }
1097
1098 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1099 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1100 // Only walk the head until any clds not purged from prior unloading
1101 // (CMS doesn't purge right away).
1102 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1103 assert(cld->is_unloading(), "invariant");
1104 cld->classes_do(f);
1105 }
1106 }
1107
1108 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1109 if (X->dictionary() != NULL)
1110
1111 // Walk classes in the loaded class dictionaries in various forms.
1112 // Only walks the classes defined in this class loader.
1113 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1114 FOR_ALL_DICTIONARY(cld) {
1115 cld->dictionary()->classes_do(f);
1116 }
1117 }
1118
1119 // Only walks the classes defined in this class loader.
1120 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1121 FOR_ALL_DICTIONARY(cld) {
1122 cld->dictionary()->classes_do(f, CHECK);
1123 }
1124 }
1125
1126 // Walks all entries in the dictionary including entries initiated by this class loader.
1127 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1128 FOR_ALL_DICTIONARY(cld) {
1129 cld->dictionary()->all_entries_do(f);
1130 }
1131 }
1132
1133 void ClassLoaderDataGraph::verify_dictionary() {
1134 FOR_ALL_DICTIONARY(cld) {
1135 cld->dictionary()->verify();
1136 }
1137 }
1138
1139 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1140 FOR_ALL_DICTIONARY(cld) {
1141 st->print("Dictionary for ");
1142 cld->print_value_on(st);
1143 st->cr();
1144 cld->dictionary()->print_on(st);
1145 st->cr();
1146 }
1147 }
1148
1149 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1150 FOR_ALL_DICTIONARY(cld) {
1151 ResourceMark rm;
1152 stringStream tempst;
1153 tempst.print("System Dictionary for %s", cld->loader_name());
1154 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1155 }
1156 }
1157
1158 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1159 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1160
1161 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1162
1163 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1164 ClassLoaderData* curr = _head;
1165 while (curr != _saved_head) {
1166 if (!curr->claimed()) {
1167 array->push(curr);
1168 LogTarget(Debug, class, loader, data) lt;
1169 if (lt.is_enabled()) {
1170 LogStream ls(lt);
1171 ls.print("found new CLD: ");
1172 curr->print_value_on(&ls);
1173 ls.cr();
1174 }
1175 }
1176
1177 curr = curr->_next;
1178 }
1179
1180 return array;
1181 }
1182
1183 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
1184 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
1185 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
1186 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
1187 return true;
1188 }
1189 }
1190 return false;
1191 }
1192
1193 #ifndef PRODUCT
1194 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1195 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1196 if (loader_data == data) {
1197 return true;
1198 }
1199 }
1200
1201 return false;
1202 }
1203 #endif // PRODUCT
1204
1205
1206 // Move class loader data from main list to the unloaded list for unloading
1207 // and deallocation later.
1208 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1209 bool clean_previous_versions) {
1210
1211 ClassLoaderData* data = _head;
1212 ClassLoaderData* prev = NULL;
1213 bool seen_dead_loader = false;
1214
1215 // Mark metadata seen on the stack only so we can delete unneeded entries.
1216 // Only walk all metadata, including the expensive code cache walk, for Full GC
1217 // and only if class redefinition and if there's previous versions of
1218 // Klasses to delete.
1219 bool walk_all_metadata = clean_previous_versions &&
1220 JvmtiExport::has_redefined_a_class() &&
1221 InstanceKlass::has_previous_versions_and_reset();
1222 MetadataOnStackMark md_on_stack(walk_all_metadata);
1223
1224 // Save previous _unloading pointer for CMS which may add to unloading list before
1225 // purging and we don't want to rewalk the previously unloaded class loader data.
1226 _saved_unloading = _unloading;
1227
1228 data = _head;
1229 while (data != NULL) {
1230 if (data->is_alive(is_alive_closure)) {
1231 // clean metaspace
1232 if (walk_all_metadata) {
1233 data->classes_do(InstanceKlass::purge_previous_versions);
1234 }
1235 data->free_deallocate_list();
1236 prev = data;
1237 data = data->next();
1238 continue;
1239 }
1240 seen_dead_loader = true;
1241 ClassLoaderData* dead = data;
1242 dead->unload();
1243 data = data->next();
1244 // Remove from loader list.
1245 // This class loader data will no longer be found
1246 // in the ClassLoaderDataGraph.
1247 if (prev != NULL) {
1248 prev->set_next(data);
1249 } else {
1250 assert(dead == _head, "sanity check");
1251 _head = data;
1252 }
1253 dead->set_next(_unloading);
1254 _unloading = dead;
1255 }
1256
1257 if (seen_dead_loader) {
1258 data = _head;
1259 while (data != NULL) {
1260 // Remove entries in the dictionary of live class loader that have
1261 // initiated loading classes in a dead class loader.
1262 if (data->dictionary() != NULL) {
1263 data->dictionary()->do_unloading();
1264 }
1265 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1266 // lists to determine if there are modules on those lists that are now
1267 // dead and should be removed. A module's life cycle is equivalent
1268 // to its defining class loader's life cycle. Since a module is
1269 // considered dead if its class loader is dead, these walks must
1270 // occur after each class loader's aliveness is determined.
1271 if (data->packages() != NULL) {
1272 data->packages()->purge_all_package_exports();
1273 }
1274 if (data->modules_defined()) {
1275 data->modules()->purge_all_module_reads();
1276 }
1277 data = data->next();
1278 }
1279
1280 post_class_unload_events();
1281 }
1282
1283 return seen_dead_loader;
1284 }
1285
1286 void ClassLoaderDataGraph::purge() {
1287 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1288 ClassLoaderData* list = _unloading;
1289 _unloading = NULL;
1290 ClassLoaderData* next = list;
1291 bool classes_unloaded = false;
1292 while (next != NULL) {
1293 ClassLoaderData* purge_me = next;
1294 next = purge_me->next();
1295 delete purge_me;
1296 classes_unloaded = true;
1297 }
1298 if (classes_unloaded) {
1299 Metaspace::purge();
1300 set_metaspace_oom(false);
1301 }
1302 }
1303
1304 int ClassLoaderDataGraph::resize_if_needed() {
1305 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1306 int resized = 0;
1307 if (Dictionary::does_any_dictionary_needs_resizing()) {
1308 FOR_ALL_DICTIONARY(cld) {
1309 if (cld->dictionary()->resize_if_needed()) {
1310 resized++;
1311 }
1312 }
1313 }
1314 return resized;
1315 }
1316
1317 void ClassLoaderDataGraph::post_class_unload_events() {
1318 #if INCLUDE_TRACE
1319 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1320 if (Tracing::enabled()) {
1321 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1322 assert(_unloading != NULL, "need class loader data unload list!");
1323 _class_unload_time = Ticks::now();
1324 classes_unloading_do(&class_unload_event);
1325 }
1326 Tracing::on_unloading_classes();
1327 }
1328 #endif
1329 }
1330
1331 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1332 : _next_klass(NULL) {
1333 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1334 Klass* klass = NULL;
1335
1336 // Find the first klass in the CLDG.
1337 while (cld != NULL) {
1338 assert_locked_or_safepoint(cld->metaspace_lock());
1339 klass = cld->_klasses;
1340 if (klass != NULL) {
1341 _next_klass = klass;
1342 return;
1343 }
1344 cld = cld->next();
1345 }
1346 }
1347
1348 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1349 Klass* next = klass->next_link();
1350 if (next != NULL) {
1351 return next;
1352 }
1353
1354 // No more klasses in the current CLD. Time to find a new CLD.
1355 ClassLoaderData* cld = klass->class_loader_data();
1356 assert_locked_or_safepoint(cld->metaspace_lock());
1357 while (next == NULL) {
1358 cld = cld->next();
1359 if (cld == NULL) {
1360 break;
1361 }
1362 next = cld->_klasses;
1363 }
1364
1365 return next;
1366 }
1367
1368 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1369 Klass* head = _next_klass;
1370
1371 while (head != NULL) {
1372 Klass* next = next_klass_in_cldg(head);
1373
1374 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1375
1376 if (old_head == head) {
1377 return head; // Won the CAS.
1378 }
1379
1380 head = old_head;
1381 }
1382
1383 // Nothing more for the iterator to hand out.
1384 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1385 return NULL;
1386 }
1387
1388 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1389 _data = ClassLoaderDataGraph::_head;
1390 }
1391
1392 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1393
1394 #ifndef PRODUCT
1395 // callable from debugger
1396 extern "C" int print_loader_data_graph() {
1397 ClassLoaderDataGraph::dump_on(tty);
1398 return 0;
1399 }
1400
1401 void ClassLoaderDataGraph::verify() {
1402 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1403 data->verify();
1404 }
1405 }
1406
1407 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1408 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1409 data->dump(out);
1410 }
1411 MetaspaceAux::dump(out);
1412 }
1413 #endif // PRODUCT
1414
1415 void ClassLoaderData::print_value_on(outputStream* out) const {
1416 if (class_loader() == NULL) {
1417 out->print("NULL class loader");
1418 } else {
1419 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1420 class_loader()->print_value_on(out);
1421 }
1422 }
1423
1424 void ClassLoaderData::print_on(outputStream* out) const {
1425 if (class_loader() == NULL) {
1426 out->print("NULL class loader");
1427 } else {
1428 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1429 class_loader()->print_on(out);
1430 }
1431 }
1432
1433 #if INCLUDE_TRACE
1434
1435 Ticks ClassLoaderDataGraph::_class_unload_time;
1436
1437 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1438 assert(k != NULL, "invariant");
1439
1440 // post class unload event
1441 EventClassUnload event(UNTIMED);
1442 event.set_endtime(_class_unload_time);
1443 event.set_unloadedClass(k);
1444 event.set_definingClassLoader(k->class_loader_data());
1445 event.commit();
1446 }
1447
1448 #endif // INCLUDE_TRACE