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/objArrayOop.inline.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "runtime/atomic.hpp"
69 #include "runtime/javaCalls.hpp"
70 #include "runtime/jniHandles.hpp"
71 #include "runtime/mutex.hpp"
72 #include "runtime/orderAccess.hpp"
73 #include "runtime/safepoint.hpp"
74 #include "runtime/synchronizer.hpp"
75 #include "utilities/growableArray.hpp"
76 #include "utilities/macros.hpp"
77 #include "utilities/ostream.hpp"
78 #if INCLUDE_ALL_GCS
79 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
80 #endif // INCLUDE_ALL_GCS
81 #if INCLUDE_TRACE
82 #include "trace/tracing.hpp"
83 #endif
84
85 // helper function to avoid in-line casts
86 template <typename T> static T* load_ptr_acquire(T* volatile *p) {
87 return static_cast<T*>(OrderAccess::load_ptr_acquire(p));
88 }
89
90 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
91
92 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
93 _class_loader(h_class_loader()),
94 _is_anonymous(is_anonymous),
95 // An anonymous class loader data doesn't have anything to keep
96 // it from being unloaded during parsing of the anonymous class.
97 // The null-class-loader should always be kept alive.
98 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
99 _metaspace(NULL), _unloading(false), _klasses(NULL),
100 _modules(NULL), _packages(NULL),
101 _claimed(0), _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
102 _next(NULL), _dependencies(dependencies),
103 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
104 Monitor::_safepoint_check_never)) {
105
106 // A ClassLoaderData created solely for an anonymous class should never have a
107 // ModuleEntryTable or PackageEntryTable created for it. The defining package
108 // and module for an anonymous class will be found in its host class.
109 if (!is_anonymous) {
110 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
111 if (h_class_loader.is_null()) {
112 // Create unnamed module for boot loader
113 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
114 } else {
115 // Create unnamed module for all other loaders
116 _unnamed_module = ModuleEntry::create_unnamed_module(this);
117 }
118 } else {
119 _unnamed_module = NULL;
120 }
121
122 if (!is_anonymous) {
123 _dictionary = create_dictionary();
124 } else {
125 _dictionary = NULL;
126 }
127 TRACE_INIT_ID(this);
128 }
129
130 void ClassLoaderData::init_dependencies(TRAPS) {
131 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
132 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
133 _dependencies.init(CHECK);
134 }
135
136 void ClassLoaderData::Dependencies::init(TRAPS) {
137 // Create empty dependencies array to add to. CMS requires this to be
138 // an oop so that it can track additions via card marks. We think.
139 _list_head = oopFactory::new_objectArray(2, CHECK);
140 }
141
142 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
143 Chunk* c = _head;
144 while (c != NULL) {
145 Chunk* next = c->_next;
146 delete c;
147 c = next;
148 }
149 }
150
151 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
152 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
153 Chunk* next = new Chunk(_head);
154 OrderAccess::release_store_ptr(&_head, next);
155 }
156 oop* handle = &_head->_data[_head->_size];
157 *handle = o;
158 OrderAccess::release_store(&_head->_size, _head->_size + 1);
159 return handle;
160 }
161
162 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
163 for (juint i = 0; i < size; i++) {
164 if (c->_data[i] != NULL) {
165 f->do_oop(&c->_data[i]);
166 }
167 }
168 }
169
170 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
171 Chunk* head = (Chunk*) OrderAccess::load_ptr_acquire(&_head);
172 if (head != NULL) {
173 // Must be careful when reading size of head
174 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
175 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
176 oops_do_chunk(f, c, c->_size);
177 }
178 }
179 }
180
181 #ifdef ASSERT
182 class VerifyContainsOopClosure : public OopClosure {
183 oop* _target;
184 bool _found;
185
186 public:
187 VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {}
188
189 void do_oop(oop* p) {
190 if (p == _target) {
191 _found = true;
192 }
193 }
194
195 void do_oop(narrowOop* p) {
196 // The ChunkedHandleList should not contain any narrowOop
197 ShouldNotReachHere();
198 }
199
200 bool found() const {
201 return _found;
202 }
203 };
204
205 bool ClassLoaderData::ChunkedHandleList::contains(oop* p) {
206 VerifyContainsOopClosure cl(p);
207 oops_do(&cl);
208 return cl.found();
209 }
210 #endif // ASSERT
211
212 bool ClassLoaderData::claim() {
213 if (_claimed == 1) {
214 return false;
215 }
216
217 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
218 }
219
220 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
221 // while the class is being parsed, and if the class appears on the module fixup list.
222 // Due to the uniqueness that no other class shares the anonymous class' name or
223 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
224 // it is being defined, therefore _keep_alive is not volatile or atomic.
225 void ClassLoaderData::inc_keep_alive() {
226 if (is_anonymous()) {
227 assert(_keep_alive >= 0, "Invalid keep alive increment count");
228 _keep_alive++;
229 }
230 }
231
232 void ClassLoaderData::dec_keep_alive() {
233 if (is_anonymous()) {
234 assert(_keep_alive > 0, "Invalid keep alive decrement count");
235 _keep_alive--;
236 }
237 }
238
239 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim) {
240 if (must_claim && !claim()) {
241 return;
242 }
243
244 f->do_oop(&_class_loader);
245 _dependencies.oops_do(f);
246
247 _handles.oops_do(f);
248 }
249
250 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
251 f->do_oop((oop*)&_list_head);
252 }
253
254 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
255 // Lock-free access requires load_ptr_acquire
256 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
257 klass_closure->do_klass(k);
258 assert(k != k->next_link(), "no loops!");
259 }
260 }
261
262 void ClassLoaderData::classes_do(void f(Klass * const)) {
263 // Lock-free access requires load_ptr_acquire
264 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
265 f(k);
266 assert(k != k->next_link(), "no loops!");
267 }
268 }
269
270 void ClassLoaderData::methods_do(void f(Method*)) {
271 // Lock-free access requires load_ptr_acquire
272 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
273 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
274 InstanceKlass::cast(k)->methods_do(f);
275 }
276 }
277 }
278
279 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
280 // Lock-free access requires load_ptr_acquire
281 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
282 // Do not filter ArrayKlass oops here...
283 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
284 klass_closure->do_klass(k);
285 }
286 }
287 }
288
289 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
290 // Lock-free access requires load_ptr_acquire
291 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
292 if (k->is_instance_klass()) {
293 f(InstanceKlass::cast(k));
294 }
295 assert(k != k->next_link(), "no loops!");
296 }
297 }
298
299 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
300 assert_locked_or_safepoint(Module_lock);
301 if (_unnamed_module != NULL) {
302 f(_unnamed_module);
303 }
304 if (_modules != NULL) {
305 for (int i = 0; i < _modules->table_size(); i++) {
306 for (ModuleEntry* entry = _modules->bucket(i);
307 entry != NULL;
308 entry = entry->next()) {
309 f(entry);
310 }
311 }
312 }
313 }
314
315 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
316 assert_locked_or_safepoint(Module_lock);
317 if (_packages != NULL) {
318 for (int i = 0; i < _packages->table_size(); i++) {
319 for (PackageEntry* entry = _packages->bucket(i);
320 entry != NULL;
321 entry = entry->next()) {
322 f(entry);
323 }
324 }
325 }
326 }
327
328 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
329 assert(k != NULL, "invariant");
330
331 ClassLoaderData * const from_cld = this;
332 ClassLoaderData * const to_cld = k->class_loader_data();
333
334 // Dependency to the null class loader data doesn't need to be recorded
335 // because the null class loader data never goes away.
336 if (to_cld->is_the_null_class_loader_data()) {
337 return;
338 }
339
340 oop to;
341 if (to_cld->is_anonymous()) {
342 // Anonymous class dependencies are through the mirror.
343 to = k->java_mirror();
344 } else {
345 to = to_cld->class_loader();
346
347 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
348 // we still have to add it. The class_loader won't keep from_cld alive.
349 if (!from_cld->is_anonymous()) {
350 // Check that this dependency isn't from the same or parent class_loader
351 oop from = from_cld->class_loader();
352
353 oop curr = from;
354 while (curr != NULL) {
355 if (curr == to) {
356 return; // this class loader is in the parent list, no need to add it.
357 }
358 curr = java_lang_ClassLoader::parent(curr);
359 }
360 }
361 }
362
363 // It's a dependency we won't find through GC, add it. This is relatively rare
364 // Must handle over GC point.
365 Handle dependency(THREAD, to);
366 from_cld->_dependencies.add(dependency, CHECK);
367 }
368
369
370 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
371 // Check first if this dependency is already in the list.
372 // Save a pointer to the last to add to under the lock.
373 objArrayOop ok = _list_head;
374 objArrayOop last = NULL;
375 while (ok != NULL) {
376 last = ok;
377 if (ok->obj_at(0) == dependency()) {
378 // Don't need to add it
379 return;
380 }
381 ok = (objArrayOop)ok->obj_at(1);
382 }
383
384 // Must handle over GC points
385 assert (last != NULL, "dependencies should be initialized");
386 objArrayHandle last_handle(THREAD, last);
387
388 // Create a new dependency node with fields for (class_loader or mirror, next)
389 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
390 deps->obj_at_put(0, dependency());
391
392 // Must handle over GC points
393 objArrayHandle new_dependency(THREAD, deps);
394
395 // Add the dependency under lock
396 locked_add(last_handle, new_dependency, THREAD);
397 }
398
399 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
400 objArrayHandle new_dependency,
401 Thread* THREAD) {
402
403 // Have to lock and put the new dependency on the end of the dependency
404 // array so the card mark for CMS sees that this dependency is new.
405 // Can probably do this lock free with some effort.
406 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
407
408 oop loader_or_mirror = new_dependency->obj_at(0);
409
410 // Since the dependencies are only added, add to the end.
411 objArrayOop end = last_handle();
412 objArrayOop last = NULL;
413 while (end != NULL) {
414 last = end;
415 // check again if another thread added it to the end.
416 if (end->obj_at(0) == loader_or_mirror) {
417 // Don't need to add it
418 return;
419 }
420 end = (objArrayOop)end->obj_at(1);
421 }
422 assert (last != NULL, "dependencies should be initialized");
423 // fill in the first element with the oop in new_dependency.
424 if (last->obj_at(0) == NULL) {
425 last->obj_at_put(0, new_dependency->obj_at(0));
426 } else {
427 last->obj_at_put(1, new_dependency());
428 }
429 }
430
431 void ClassLoaderDataGraph::clear_claimed_marks() {
432 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
433 cld->clear_claimed();
434 }
435 }
436
437 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
438 {
439 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
440 Klass* old_value = _klasses;
441 k->set_next_link(old_value);
442 // Link the new item into the list, making sure the linked class is stable
443 // since the list can be walked without a lock
444 OrderAccess::release_store_ptr(&_klasses, k);
445 }
446
447 if (publicize && k->class_loader_data() != NULL) {
448 ResourceMark rm;
449 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
450 PTR_FORMAT " loader: " PTR_FORMAT " %s",
451 p2i(k),
452 k->external_name(),
453 p2i(k->class_loader_data()),
454 p2i((void *)k->class_loader()),
455 loader_name());
456 }
457 }
458
459 // Class iterator used by the compiler. It gets some number of classes at
460 // a safepoint to decay invocation counters on the methods.
461 class ClassLoaderDataGraphKlassIteratorStatic {
462 ClassLoaderData* _current_loader_data;
463 Klass* _current_class_entry;
464 public:
465
466 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
467
468 InstanceKlass* try_get_next_class() {
469 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
470 int max_classes = InstanceKlass::number_of_instance_classes();
471 assert(max_classes > 0, "should not be called with no instance classes");
472 for (int i = 0; i < max_classes; ) {
473
474 if (_current_class_entry != NULL) {
475 Klass* k = _current_class_entry;
476 _current_class_entry = _current_class_entry->next_link();
477
478 if (k->is_instance_klass()) {
479 InstanceKlass* ik = InstanceKlass::cast(k);
480 i++; // count all instance classes found
481 // Not yet loaded classes are counted in max_classes
482 // but only return loaded classes.
483 if (ik->is_loaded()) {
484 return ik;
485 }
486 }
487 } else {
488 // Go to next CLD
489 if (_current_loader_data != NULL) {
490 _current_loader_data = _current_loader_data->next();
491 }
492 // Start at the beginning
493 if (_current_loader_data == NULL) {
494 _current_loader_data = ClassLoaderDataGraph::_head;
495 }
496
497 _current_class_entry = _current_loader_data->klasses();
498 }
499 }
500 // Should never be reached unless all instance classes have failed or are not fully loaded.
501 // Caller handles NULL.
502 return NULL;
503 }
504
505 // If the current class for the static iterator is a class being unloaded or
506 // deallocated, adjust the current class.
507 void adjust_saved_class(ClassLoaderData* cld) {
508 if (_current_loader_data == cld) {
509 _current_loader_data = cld->next();
510 if (_current_loader_data != NULL) {
511 _current_class_entry = _current_loader_data->klasses();
512 } // else try_get_next_class will start at the head
513 }
514 }
515
516 void adjust_saved_class(Klass* klass) {
517 if (_current_class_entry == klass) {
518 _current_class_entry = klass->next_link();
519 }
520 }
521 };
522
523 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
524
525 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
526 return static_klass_iterator.try_get_next_class();
527 }
528
529
530 // Remove a klass from the _klasses list for scratch_class during redefinition
531 // or parsed class in the case of an error.
532 void ClassLoaderData::remove_class(Klass* scratch_class) {
533 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
534
535 // Adjust global class iterator.
536 static_klass_iterator.adjust_saved_class(scratch_class);
537
538 Klass* prev = NULL;
539 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
540 if (k == scratch_class) {
541 if (prev == NULL) {
542 _klasses = k->next_link();
543 } else {
544 Klass* next = k->next_link();
545 prev->set_next_link(next);
546 }
547 return;
548 }
549 prev = k;
550 assert(k != k->next_link(), "no loops!");
551 }
552 ShouldNotReachHere(); // should have found this class!!
553 }
554
555 void ClassLoaderData::unload() {
556 _unloading = true;
557
558 // Tell serviceability tools these classes are unloading
559 classes_do(InstanceKlass::notify_unload_class);
560
561 LogTarget(Debug, class, loader, data) lt;
562 if (lt.is_enabled()) {
563 ResourceMark rm;
564 LogStream ls(lt);
565 ls.print(": unload loader data " INTPTR_FORMAT, p2i(this));
566 ls.print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
567 loader_name());
568 if (is_anonymous()) {
569 ls.print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
570 }
571 ls.cr();
572 }
573
574 // In some rare cases items added to this list will not be freed elsewhere.
575 // To keep it simple, just free everything in it here.
576 free_deallocate_list();
577
578 // Clean up global class iterator for compiler
579 static_klass_iterator.adjust_saved_class(this);
580 }
581
582 ModuleEntryTable* ClassLoaderData::modules() {
583 // Lazily create the module entry table at first request.
584 // Lock-free access requires load_ptr_acquire.
585 ModuleEntryTable* modules = load_ptr_acquire(&_modules);
586 if (modules == NULL) {
587 MutexLocker m1(Module_lock);
588 // Check if _modules got allocated while we were waiting for this lock.
589 if ((modules = _modules) == NULL) {
590 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
591
592 {
593 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
594 // Ensure _modules is stable, since it is examined without a lock
595 OrderAccess::release_store_ptr(&_modules, modules);
596 }
597 }
598 }
599 return modules;
600 }
601
602 const int _boot_loader_dictionary_size = 1009;
603 const int _default_loader_dictionary_size = 107;
604 const int _prime_array_size = 8; // array of primes for system dictionary size
605 const int _average_depth_goal = 3; // goal for lookup length
606 const int _primelist[_prime_array_size] = {107, 1009, 2017, 4049, 5051, 10103, 20201, 40423};
607
608 // Calculate a "good" dictionary size based
609 // on predicted or current loaded classes count.
610 static int calculate_dictionary_size(int classcount) {
611 int newsize = _primelist[0];
612 if (classcount > 0 && !DumpSharedSpaces) {
613 int index = 0;
614 int desiredsize = classcount/_average_depth_goal;
615 for (newsize = _primelist[index]; index < _prime_array_size -1;
616 newsize = _primelist[++index]) {
617 if (desiredsize <= newsize) {
618 break;
619 }
620 }
621 }
622 return newsize;
623 }
624
625 Dictionary* ClassLoaderData::create_dictionary() {
626 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
627 int size;
628 if (_the_null_class_loader_data == NULL) {
629 size = _boot_loader_dictionary_size;
630 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
631 size = 1; // there's only one class in relection class loader and no initiated classes
632 } else if (is_system_class_loader_data()) {
633 size = calculate_dictionary_size(PredictedLoadedClassCount);
634 } else {
635 size = _default_loader_dictionary_size;
636 }
637 return new Dictionary(this, size);
638 }
639
640 // Unloading support
641 oop ClassLoaderData::keep_alive_object() const {
642 assert_locked_or_safepoint(_metaspace_lock);
643 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
644 return is_anonymous() ? _klasses->java_mirror() : class_loader();
645 }
646
647 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
648 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
649 || is_alive_closure->do_object_b(keep_alive_object());
650
651 return alive;
652 }
653
654 ClassLoaderData::~ClassLoaderData() {
655 // Release C heap structures for all the classes.
656 classes_do(InstanceKlass::release_C_heap_structures);
657
658 // Release C heap allocated hashtable for all the packages.
659 if (_packages != NULL) {
660 // Destroy the table itself
661 delete _packages;
662 _packages = NULL;
663 }
664
665 // Release C heap allocated hashtable for all the modules.
666 if (_modules != NULL) {
667 // Destroy the table itself
668 delete _modules;
669 _modules = NULL;
670 }
671
672 // Release C heap allocated hashtable for the dictionary
673 if (_dictionary != NULL) {
674 // Destroy the table itself
675 delete _dictionary;
676 _dictionary = NULL;
677 }
678
679 if (_unnamed_module != NULL) {
680 _unnamed_module->delete_unnamed_module();
681 _unnamed_module = NULL;
682 }
683
684 // release the metaspace
685 Metaspace *m = _metaspace;
686 if (m != NULL) {
687 _metaspace = NULL;
688 delete m;
689 }
690 // Clear all the JNI handles for methods
691 // These aren't deallocated and are going to look like a leak, but that's
692 // needed because we can't really get rid of jmethodIDs because we don't
693 // know when native code is going to stop using them. The spec says that
694 // they're "invalid" but existing programs likely rely on their being
695 // NULL after class unloading.
696 if (_jmethod_ids != NULL) {
697 Method::clear_jmethod_ids(this);
698 }
699 // Delete lock
700 delete _metaspace_lock;
701
702 // Delete free list
703 if (_deallocate_list != NULL) {
704 delete _deallocate_list;
705 }
706 }
707
708 // Returns true if this class loader data is for the system class loader.
709 bool ClassLoaderData::is_system_class_loader_data() const {
710 return SystemDictionary::is_system_class_loader(class_loader());
711 }
712
713 // Returns true if this class loader data is for the platform class loader.
714 bool ClassLoaderData::is_platform_class_loader_data() const {
715 return SystemDictionary::is_platform_class_loader(class_loader());
716 }
717
718 // Returns true if this class loader data is one of the 3 builtin
719 // (boot, application/system or platform) class loaders. Note, the
720 // builtin loaders are not freed by a GC.
721 bool ClassLoaderData::is_builtin_class_loader_data() const {
722 return (is_the_null_class_loader_data() ||
723 SystemDictionary::is_system_class_loader(class_loader()) ||
724 SystemDictionary::is_platform_class_loader(class_loader()));
725 }
726
727 Metaspace* ClassLoaderData::metaspace_non_null() {
728 // If the metaspace has not been allocated, create a new one. Might want
729 // to create smaller arena for Reflection class loaders also.
730 // The reason for the delayed allocation is because some class loaders are
731 // simply for delegating with no metadata of their own.
732 // Lock-free access requires load_ptr_acquire.
733 Metaspace* metaspace = load_ptr_acquire(&_metaspace);
734 if (metaspace == NULL) {
735 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
736 // Check if _metaspace got allocated while we were waiting for this lock.
737 if ((metaspace = _metaspace) == NULL) {
738 if (this == the_null_class_loader_data()) {
739 assert (class_loader() == NULL, "Must be");
740 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
741 } else if (is_anonymous()) {
742 if (class_loader() != NULL) {
743 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
744 }
745 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
746 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
747 if (class_loader() != NULL) {
748 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
749 }
750 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
751 } else {
752 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
753 }
754 // Ensure _metaspace is stable, since it is examined without a lock
755 OrderAccess::release_store_ptr(&_metaspace, metaspace);
756 }
757 }
758 return metaspace;
759 }
760
761 OopHandle ClassLoaderData::add_handle(Handle h) {
762 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
763 return OopHandle(_handles.add(h()));
764 }
765
766 void ClassLoaderData::remove_handle(OopHandle h) {
767 oop* ptr = h.ptr_raw();
768 if (ptr != NULL) {
769 assert(_handles.contains(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
770 #if INCLUDE_ALL_GCS
771 // This barrier is used by G1 to remember the old oop values, so
772 // that we don't forget any objects that were live at the snapshot at
773 // the beginning.
774 if (UseG1GC) {
775 oop obj = *ptr;
776 if (obj != NULL) {
777 G1SATBCardTableModRefBS::enqueue(obj);
778 }
779 }
780 #endif
781 *ptr = NULL;
782 }
783 }
784
785 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
786 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
787 if (dest.resolve() != NULL) {
788 return;
789 } else {
790 dest = _handles.add(h());
791 }
792 }
793
794 // Add this metadata pointer to be freed when it's safe. This is only during
795 // class unloading because Handles might point to this metadata field.
796 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
797 // Metadata in shared region isn't deleted.
798 if (!m->is_shared()) {
799 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
800 if (_deallocate_list == NULL) {
801 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
802 }
803 _deallocate_list->append_if_missing(m);
804 }
805 }
806
807 // Deallocate free metadata on the free list. How useful the PermGen was!
808 void ClassLoaderData::free_deallocate_list() {
809 // Don't need lock, at safepoint
810 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
811 if (_deallocate_list == NULL) {
812 return;
813 }
814 // Go backwards because this removes entries that are freed.
815 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
816 Metadata* m = _deallocate_list->at(i);
817 if (!m->on_stack()) {
818 _deallocate_list->remove_at(i);
819 // There are only three types of metadata that we deallocate directly.
820 // Cast them so they can be used by the template function.
821 if (m->is_method()) {
822 MetadataFactory::free_metadata(this, (Method*)m);
823 } else if (m->is_constantPool()) {
824 MetadataFactory::free_metadata(this, (ConstantPool*)m);
825 } else if (m->is_klass()) {
826 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
827 } else {
828 ShouldNotReachHere();
829 }
830 } else {
831 // Metadata is alive.
832 // If scratch_class is on stack then it shouldn't be on this list!
833 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
834 "scratch classes on this list should be dead");
835 // Also should assert that other metadata on the list was found in handles.
836 }
837 }
838 }
839
840 // These anonymous class loaders are to contain classes used for JSR292
841 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
842 // Add a new class loader data to the graph.
843 Handle lh(THREAD, loader);
844 return ClassLoaderDataGraph::add(lh, true, THREAD);
845 }
846
847 const char* ClassLoaderData::loader_name() {
848 // Handles null class loader
849 return SystemDictionary::loader_name(class_loader());
850 }
851
852 #ifndef PRODUCT
853 // Define to dump klasses
854 #undef CLD_DUMP_KLASSES
855
856 void ClassLoaderData::dump(outputStream * const out) {
857 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
858 p2i(this), p2i((void *)class_loader()),
859 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
860 if (claimed()) out->print(" claimed ");
861 if (is_unloading()) out->print(" unloading ");
862 out->cr();
863 if (metaspace_or_null() != NULL) {
864 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
865 metaspace_or_null()->dump(out);
866 } else {
867 out->print_cr("metaspace: NULL");
868 }
869
870 #ifdef CLD_DUMP_KLASSES
871 if (Verbose) {
872 Klass* k = _klasses;
873 while (k != NULL) {
874 out->print_cr("klass " PTR_FORMAT ", %s", k, k->name()->as_C_string());
875 assert(k != k->next_link(), "no loops!");
876 k = k->next_link();
877 }
878 }
879 #endif // CLD_DUMP_KLASSES
880 #undef CLD_DUMP_KLASSES
881 if (_jmethod_ids != NULL) {
882 Method::print_jmethod_ids(this, out);
883 }
884 out->print_cr("}");
885 }
886 #endif // PRODUCT
887
888 void ClassLoaderData::verify() {
889 assert_locked_or_safepoint(_metaspace_lock);
890 oop cl = class_loader();
891
892 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
893 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
894
895 // Verify the integrity of the allocated space.
896 if (metaspace_or_null() != NULL) {
897 metaspace_or_null()->verify();
898 }
899
900 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
901 guarantee(k->class_loader_data() == this, "Must be the same");
902 k->verify();
903 assert(k != k->next_link(), "no loops!");
904 }
905 }
906
907 bool ClassLoaderData::contains_klass(Klass* klass) {
908 // Lock-free access requires load_ptr_acquire
909 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
910 if (k == klass) return true;
911 }
912 return false;
913 }
914
915
916 // GC root of class loader data created.
917 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
918 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
919 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
920 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
921
922 bool ClassLoaderDataGraph::_should_purge = false;
923 bool ClassLoaderDataGraph::_metaspace_oom = false;
924
925 // Add a new class loader data node to the list. Assign the newly created
926 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
927 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
928 // We need to allocate all the oops for the ClassLoaderData before allocating the
929 // actual ClassLoaderData object.
930 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
931
932 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
933 // ClassLoaderData in the graph since the CLD
934 // contains unhandled oops
935
936 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
937
938
939 if (!is_anonymous) {
940 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
941 // First, Atomically set it
942 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
943 if (old != NULL) {
944 delete cld;
945 // Returns the data.
946 return old;
947 }
948 }
949
950 // We won the race, and therefore the task of adding the data to the list of
951 // class loader data
952 ClassLoaderData** list_head = &_head;
953 ClassLoaderData* next = _head;
954
955 do {
956 cld->set_next(next);
957 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
958 if (exchanged == next) {
959 LogTarget(Debug, class, loader, data) lt;
960 if (lt.is_enabled()) {
961 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
962 LogStream ls(lt);
963 print_creation(&ls, loader, cld, CHECK_NULL);
964 }
965 return cld;
966 }
967 next = exchanged;
968 } while (true);
969 }
970
971 void ClassLoaderDataGraph::print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS) {
972 Handle string;
973 if (loader.not_null()) {
974 // Include the result of loader.toString() in the output. This allows
975 // the user of the log to identify the class loader instance.
976 JavaValue result(T_OBJECT);
977 Klass* spec_klass = SystemDictionary::ClassLoader_klass();
978 JavaCalls::call_virtual(&result,
979 loader,
980 spec_klass,
981 vmSymbols::toString_name(),
982 vmSymbols::void_string_signature(),
983 CHECK);
984 assert(result.get_type() == T_OBJECT, "just checking");
985 string = Handle(THREAD, (oop)result.get_jobject());
986 }
987
988 ResourceMark rm;
989 out->print("create class loader data " INTPTR_FORMAT, p2i(cld));
990 out->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
991 cld->loader_name());
992
993 if (string.not_null()) {
994 out->print(": ");
995 java_lang_String::print(string(), out);
996 }
997 out->cr();
998 }
999
1000
1001 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1002 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1003 cld->oops_do(f, must_claim);
1004 }
1005 }
1006
1007 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1008 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1009 if (cld->keep_alive()) {
1010 cld->oops_do(f, must_claim);
1011 }
1012 }
1013 }
1014
1015 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1016 if (ClassUnloading) {
1017 keep_alive_oops_do(f, must_claim);
1018 } else {
1019 oops_do(f, must_claim);
1020 }
1021 }
1022
1023 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1024 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1025 cl->do_cld(cld);
1026 }
1027 }
1028
1029 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1030 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1031 // Only walk the head until any clds not purged from prior unloading
1032 // (CMS doesn't purge right away).
1033 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1034 assert(cld->is_unloading(), "invariant");
1035 cl->do_cld(cld);
1036 }
1037 }
1038
1039 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1040 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1041 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1042 if (closure != NULL) {
1043 closure->do_cld(cld);
1044 }
1045 }
1046 }
1047
1048 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1049 roots_cld_do(cl, NULL);
1050 }
1051
1052 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1053 if (ClassUnloading) {
1054 keep_alive_cld_do(cl);
1055 } else {
1056 cld_do(cl);
1057 }
1058 }
1059
1060 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1061 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1062 cld->classes_do(klass_closure);
1063 }
1064 }
1065
1066 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1067 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1068 cld->classes_do(f);
1069 }
1070 }
1071
1072 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1073 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1074 cld->methods_do(f);
1075 }
1076 }
1077
1078 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1079 assert_locked_or_safepoint(Module_lock);
1080 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1081 cld->modules_do(f);
1082 }
1083 }
1084
1085 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1086 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1087 // Only walk the head until any clds not purged from prior unloading
1088 // (CMS doesn't purge right away).
1089 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1090 assert(cld->is_unloading(), "invariant");
1091 cld->modules_do(f);
1092 }
1093 }
1094
1095 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1096 assert_locked_or_safepoint(Module_lock);
1097 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1098 cld->packages_do(f);
1099 }
1100 }
1101
1102 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1103 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1104 // Only walk the head until any clds not purged from prior unloading
1105 // (CMS doesn't purge right away).
1106 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1107 assert(cld->is_unloading(), "invariant");
1108 cld->packages_do(f);
1109 }
1110 }
1111
1112 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1113 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1114 cld->loaded_classes_do(klass_closure);
1115 }
1116 }
1117
1118 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1119 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1120 // Only walk the head until any clds not purged from prior unloading
1121 // (CMS doesn't purge right away).
1122 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1123 assert(cld->is_unloading(), "invariant");
1124 cld->classes_do(f);
1125 }
1126 }
1127
1128 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1129 if (X->dictionary() != NULL)
1130
1131 // Walk classes in the loaded class dictionaries in various forms.
1132 // Only walks the classes defined in this class loader.
1133 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1134 FOR_ALL_DICTIONARY(cld) {
1135 cld->dictionary()->classes_do(f);
1136 }
1137 }
1138
1139 // Only walks the classes defined in this class loader.
1140 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1141 FOR_ALL_DICTIONARY(cld) {
1142 cld->dictionary()->classes_do(f, CHECK);
1143 }
1144 }
1145
1146 // Walks all entries in the dictionary including entries initiated by this class loader.
1147 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1148 FOR_ALL_DICTIONARY(cld) {
1149 cld->dictionary()->all_entries_do(f);
1150 }
1151 }
1152
1153 void ClassLoaderDataGraph::verify_dictionary() {
1154 FOR_ALL_DICTIONARY(cld) {
1155 cld->dictionary()->verify();
1156 }
1157 }
1158
1159 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1160 FOR_ALL_DICTIONARY(cld) {
1161 st->print("Dictionary for ");
1162 cld->print_value_on(st);
1163 st->cr();
1164 cld->dictionary()->print_on(st);
1165 st->cr();
1166 }
1167 }
1168
1169 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1170 FOR_ALL_DICTIONARY(cld) {
1171 ResourceMark rm;
1172 stringStream tempst;
1173 tempst.print("System Dictionary for %s", cld->loader_name());
1174 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1175 }
1176 }
1177
1178 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1179 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1180
1181 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1182
1183 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1184 ClassLoaderData* curr = _head;
1185 while (curr != _saved_head) {
1186 if (!curr->claimed()) {
1187 array->push(curr);
1188 LogTarget(Debug, class, loader, data) lt;
1189 if (lt.is_enabled()) {
1190 LogStream ls(lt);
1191 ls.print("found new CLD: ");
1192 curr->print_value_on(&ls);
1193 ls.cr();
1194 }
1195 }
1196
1197 curr = curr->_next;
1198 }
1199
1200 return array;
1201 }
1202
1203 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
1204 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
1205 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
1206 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
1207 return true;
1208 }
1209 }
1210 return false;
1211 }
1212
1213 #ifndef PRODUCT
1214 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1215 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1216 if (loader_data == data) {
1217 return true;
1218 }
1219 }
1220
1221 return false;
1222 }
1223 #endif // PRODUCT
1224
1225
1226 // Move class loader data from main list to the unloaded list for unloading
1227 // and deallocation later.
1228 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1229 bool clean_previous_versions) {
1230
1231 ClassLoaderData* data = _head;
1232 ClassLoaderData* prev = NULL;
1233 bool seen_dead_loader = false;
1234
1235 // Mark metadata seen on the stack only so we can delete unneeded entries.
1236 // Only walk all metadata, including the expensive code cache walk, for Full GC
1237 // and only if class redefinition and if there's previous versions of
1238 // Klasses to delete.
1239 bool walk_all_metadata = clean_previous_versions &&
1240 JvmtiExport::has_redefined_a_class() &&
1241 InstanceKlass::has_previous_versions_and_reset();
1242 MetadataOnStackMark md_on_stack(walk_all_metadata);
1243
1244 // Save previous _unloading pointer for CMS which may add to unloading list before
1245 // purging and we don't want to rewalk the previously unloaded class loader data.
1246 _saved_unloading = _unloading;
1247
1248 data = _head;
1249 while (data != NULL) {
1250 if (data->is_alive(is_alive_closure)) {
1251 // clean metaspace
1252 if (walk_all_metadata) {
1253 data->classes_do(InstanceKlass::purge_previous_versions);
1254 }
1255 data->free_deallocate_list();
1256 prev = data;
1257 data = data->next();
1258 continue;
1259 }
1260 seen_dead_loader = true;
1261 ClassLoaderData* dead = data;
1262 dead->unload();
1263 data = data->next();
1264 // Remove from loader list.
1265 // This class loader data will no longer be found
1266 // in the ClassLoaderDataGraph.
1267 if (prev != NULL) {
1268 prev->set_next(data);
1269 } else {
1270 assert(dead == _head, "sanity check");
1271 _head = data;
1272 }
1273 dead->set_next(_unloading);
1274 _unloading = dead;
1275 }
1276
1277 if (seen_dead_loader) {
1278 data = _head;
1279 while (data != NULL) {
1280 // Remove entries in the dictionary of live class loader that have
1281 // initiated loading classes in a dead class loader.
1282 if (data->dictionary() != NULL) {
1283 data->dictionary()->do_unloading();
1284 }
1285 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1286 // lists to determine if there are modules on those lists that are now
1287 // dead and should be removed. A module's life cycle is equivalent
1288 // to its defining class loader's life cycle. Since a module is
1289 // considered dead if its class loader is dead, these walks must
1290 // occur after each class loader's aliveness is determined.
1291 if (data->packages() != NULL) {
1292 data->packages()->purge_all_package_exports();
1293 }
1294 if (data->modules_defined()) {
1295 data->modules()->purge_all_module_reads();
1296 }
1297 data = data->next();
1298 }
1299
1300 post_class_unload_events();
1301 }
1302
1303 return seen_dead_loader;
1304 }
1305
1306 void ClassLoaderDataGraph::purge() {
1307 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1308 ClassLoaderData* list = _unloading;
1309 _unloading = NULL;
1310 ClassLoaderData* next = list;
1311 bool classes_unloaded = false;
1312 while (next != NULL) {
1313 ClassLoaderData* purge_me = next;
1314 next = purge_me->next();
1315 delete purge_me;
1316 classes_unloaded = true;
1317 }
1318 if (classes_unloaded) {
1319 Metaspace::purge();
1320 set_metaspace_oom(false);
1321 }
1322 }
1323
1324 void ClassLoaderDataGraph::post_class_unload_events() {
1325 #if INCLUDE_TRACE
1326 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1327 if (Tracing::enabled()) {
1328 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1329 assert(_unloading != NULL, "need class loader data unload list!");
1330 _class_unload_time = Ticks::now();
1331 classes_unloading_do(&class_unload_event);
1332 }
1333 Tracing::on_unloading_classes();
1334 }
1335 #endif
1336 }
1337
1338 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1339 : _next_klass(NULL) {
1340 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1341 Klass* klass = NULL;
1342
1343 // Find the first klass in the CLDG.
1344 while (cld != NULL) {
1345 assert_locked_or_safepoint(cld->metaspace_lock());
1346 klass = cld->_klasses;
1347 if (klass != NULL) {
1348 _next_klass = klass;
1349 return;
1350 }
1351 cld = cld->next();
1352 }
1353 }
1354
1355 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1356 Klass* next = klass->next_link();
1357 if (next != NULL) {
1358 return next;
1359 }
1360
1361 // No more klasses in the current CLD. Time to find a new CLD.
1362 ClassLoaderData* cld = klass->class_loader_data();
1363 assert_locked_or_safepoint(cld->metaspace_lock());
1364 while (next == NULL) {
1365 cld = cld->next();
1366 if (cld == NULL) {
1367 break;
1368 }
1369 next = cld->_klasses;
1370 }
1371
1372 return next;
1373 }
1374
1375 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1376 Klass* head = _next_klass;
1377
1378 while (head != NULL) {
1379 Klass* next = next_klass_in_cldg(head);
1380
1381 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
1382
1383 if (old_head == head) {
1384 return head; // Won the CAS.
1385 }
1386
1387 head = old_head;
1388 }
1389
1390 // Nothing more for the iterator to hand out.
1391 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1392 return NULL;
1393 }
1394
1395 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1396 _data = ClassLoaderDataGraph::_head;
1397 }
1398
1399 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1400
1401 #ifndef PRODUCT
1402 // callable from debugger
1403 extern "C" int print_loader_data_graph() {
1404 ClassLoaderDataGraph::dump_on(tty);
1405 return 0;
1406 }
1407
1408 void ClassLoaderDataGraph::verify() {
1409 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1410 data->verify();
1411 }
1412 }
1413
1414 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1415 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1416 data->dump(out);
1417 }
1418 MetaspaceAux::dump(out);
1419 }
1420 #endif // PRODUCT
1421
1422 void ClassLoaderData::print_value_on(outputStream* out) const {
1423 if (class_loader() == NULL) {
1424 out->print("NULL class loader");
1425 } else {
1426 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1427 class_loader()->print_value_on(out);
1428 }
1429 }
1430
1431 void ClassLoaderData::print_on(outputStream* out) const {
1432 if (class_loader() == NULL) {
1433 out->print("NULL class loader");
1434 } else {
1435 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1436 class_loader()->print_on(out);
1437 }
1438 }
1439
1440 #if INCLUDE_TRACE
1441
1442 Ticks ClassLoaderDataGraph::_class_unload_time;
1443
1444 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1445 assert(k != NULL, "invariant");
1446
1447 // post class unload event
1448 EventClassUnload event(UNTIMED);
1449 event.set_endtime(_class_unload_time);
1450 event.set_unloadedClass(k);
1451 event.set_definingClassLoader(k->class_loader_data());
1452 event.commit();
1453 }
1454
1455 #endif // INCLUDE_TRACE