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
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, KlassClosure* klass_closure, 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 if (klass_closure != NULL) {
250 classes_do(klass_closure);
251 }
252 }
253
254 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
255 f->do_oop((oop*)&_list_head);
256 }
257
258 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
259 // Lock-free access requires load_ptr_acquire
260 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
261 klass_closure->do_klass(k);
262 assert(k != k->next_link(), "no loops!");
263 }
264 }
265
266 void ClassLoaderData::classes_do(void f(Klass * const)) {
267 // Lock-free access requires load_ptr_acquire
268 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
269 f(k);
270 assert(k != k->next_link(), "no loops!");
271 }
272 }
273
274 void ClassLoaderData::methods_do(void f(Method*)) {
275 // Lock-free access requires load_ptr_acquire
276 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
277 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
278 InstanceKlass::cast(k)->methods_do(f);
279 }
280 }
281 }
282
283 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
284 // Lock-free access requires load_ptr_acquire
285 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
286 // Do not filter ArrayKlass oops here...
287 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
288 klass_closure->do_klass(k);
289 }
290 }
291 }
292
293 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
294 // Lock-free access requires load_ptr_acquire
295 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
296 if (k->is_instance_klass()) {
297 f(InstanceKlass::cast(k));
298 }
299 assert(k != k->next_link(), "no loops!");
300 }
301 }
302
303 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
304 assert_locked_or_safepoint(Module_lock);
305 if (_unnamed_module != NULL) {
306 f(_unnamed_module);
307 }
308 if (_modules != NULL) {
309 for (int i = 0; i < _modules->table_size(); i++) {
310 for (ModuleEntry* entry = _modules->bucket(i);
311 entry != NULL;
312 entry = entry->next()) {
313 f(entry);
314 }
315 }
316 }
317 }
318
319 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
320 assert_locked_or_safepoint(Module_lock);
321 if (_packages != NULL) {
322 for (int i = 0; i < _packages->table_size(); i++) {
323 for (PackageEntry* entry = _packages->bucket(i);
324 entry != NULL;
325 entry = entry->next()) {
326 f(entry);
327 }
328 }
329 }
330 }
331
332 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
333 assert(k != NULL, "invariant");
334
335 ClassLoaderData * const from_cld = this;
336 ClassLoaderData * const to_cld = k->class_loader_data();
337
338 // Dependency to the null class loader data doesn't need to be recorded
339 // because the null class loader data never goes away.
340 if (to_cld->is_the_null_class_loader_data()) {
341 return;
342 }
343
344 oop to;
345 if (to_cld->is_anonymous()) {
346 // Anonymous class dependencies are through the mirror.
347 to = k->java_mirror();
348 } else {
349 to = to_cld->class_loader();
350
351 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
352 // we still have to add it. The class_loader won't keep from_cld alive.
353 if (!from_cld->is_anonymous()) {
354 // Check that this dependency isn't from the same or parent class_loader
355 oop from = from_cld->class_loader();
356
357 oop curr = from;
358 while (curr != NULL) {
359 if (curr == to) {
360 return; // this class loader is in the parent list, no need to add it.
361 }
362 curr = java_lang_ClassLoader::parent(curr);
363 }
364 }
365 }
366
367 // It's a dependency we won't find through GC, add it. This is relatively rare
368 // Must handle over GC point.
369 Handle dependency(THREAD, to);
370 from_cld->_dependencies.add(dependency, CHECK);
371 }
372
373
374 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
375 // Check first if this dependency is already in the list.
376 // Save a pointer to the last to add to under the lock.
377 objArrayOop ok = _list_head;
378 objArrayOop last = NULL;
379 while (ok != NULL) {
380 last = ok;
381 if (ok->obj_at(0) == dependency()) {
382 // Don't need to add it
383 return;
384 }
385 ok = (objArrayOop)ok->obj_at(1);
386 }
387
388 // Must handle over GC points
389 assert (last != NULL, "dependencies should be initialized");
390 objArrayHandle last_handle(THREAD, last);
391
392 // Create a new dependency node with fields for (class_loader or mirror, next)
393 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
394 deps->obj_at_put(0, dependency());
395
396 // Must handle over GC points
397 objArrayHandle new_dependency(THREAD, deps);
398
399 // Add the dependency under lock
400 locked_add(last_handle, new_dependency, THREAD);
401 }
402
403 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
404 objArrayHandle new_dependency,
405 Thread* THREAD) {
406
407 // Have to lock and put the new dependency on the end of the dependency
408 // array so the card mark for CMS sees that this dependency is new.
409 // Can probably do this lock free with some effort.
410 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
411
412 oop loader_or_mirror = new_dependency->obj_at(0);
413
414 // Since the dependencies are only added, add to the end.
415 objArrayOop end = last_handle();
416 objArrayOop last = NULL;
417 while (end != NULL) {
418 last = end;
419 // check again if another thread added it to the end.
420 if (end->obj_at(0) == loader_or_mirror) {
421 // Don't need to add it
422 return;
423 }
424 end = (objArrayOop)end->obj_at(1);
425 }
426 assert (last != NULL, "dependencies should be initialized");
427 // fill in the first element with the oop in new_dependency.
428 if (last->obj_at(0) == NULL) {
429 last->obj_at_put(0, new_dependency->obj_at(0));
430 } else {
431 last->obj_at_put(1, new_dependency());
432 }
433 }
434
435 void ClassLoaderDataGraph::clear_claimed_marks() {
436 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
437 cld->clear_claimed();
438 }
439 }
440
441 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
442 {
443 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
444 Klass* old_value = _klasses;
445 k->set_next_link(old_value);
446 // Link the new item into the list, making sure the linked class is stable
447 // since the list can be walked without a lock
448 OrderAccess::release_store_ptr(&_klasses, k);
449 }
450
451 if (publicize && k->class_loader_data() != NULL) {
452 ResourceMark rm;
453 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
454 PTR_FORMAT " loader: " PTR_FORMAT " %s",
455 p2i(k),
456 k->external_name(),
457 p2i(k->class_loader_data()),
458 p2i((void *)k->class_loader()),
459 loader_name());
460 }
461 }
462
463 // Class iterator used by the compiler. It gets some number of classes at
464 // a safepoint to decay invocation counters on the methods.
465 class ClassLoaderDataGraphKlassIteratorStatic {
466 ClassLoaderData* _current_loader_data;
467 Klass* _current_class_entry;
468 public:
469
470 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
471
472 InstanceKlass* try_get_next_class() {
473 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
474 int max_classes = InstanceKlass::number_of_instance_classes();
475 assert(max_classes > 0, "should not be called with no instance classes");
476 for (int i = 0; i < max_classes; ) {
477
478 if (_current_class_entry != NULL) {
479 Klass* k = _current_class_entry;
480 _current_class_entry = _current_class_entry->next_link();
481
482 if (k->is_instance_klass()) {
483 InstanceKlass* ik = InstanceKlass::cast(k);
484 i++; // count all instance classes found
485 // Not yet loaded classes are counted in max_classes
486 // but only return loaded classes.
487 if (ik->is_loaded()) {
488 return ik;
489 }
490 }
491 } else {
492 // Go to next CLD
493 if (_current_loader_data != NULL) {
494 _current_loader_data = _current_loader_data->next();
495 }
496 // Start at the beginning
497 if (_current_loader_data == NULL) {
498 _current_loader_data = ClassLoaderDataGraph::_head;
499 }
500
501 _current_class_entry = _current_loader_data->klasses();
502 }
503 }
504 // Should never be reached unless all instance classes have failed or are not fully loaded.
505 // Caller handles NULL.
506 return NULL;
507 }
508
509 // If the current class for the static iterator is a class being unloaded or
510 // deallocated, adjust the current class.
511 void adjust_saved_class(ClassLoaderData* cld) {
512 if (_current_loader_data == cld) {
513 _current_loader_data = cld->next();
514 if (_current_loader_data != NULL) {
515 _current_class_entry = _current_loader_data->klasses();
516 } // else try_get_next_class will start at the head
517 }
518 }
519
520 void adjust_saved_class(Klass* klass) {
521 if (_current_class_entry == klass) {
522 _current_class_entry = klass->next_link();
523 }
524 }
525 };
526
527 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
528
529 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
530 return static_klass_iterator.try_get_next_class();
531 }
532
533
534 // Remove a klass from the _klasses list for scratch_class during redefinition
535 // or parsed class in the case of an error.
536 void ClassLoaderData::remove_class(Klass* scratch_class) {
537 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
538
539 // Adjust global class iterator.
540 static_klass_iterator.adjust_saved_class(scratch_class);
541
542 Klass* prev = NULL;
543 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
544 if (k == scratch_class) {
545 if (prev == NULL) {
546 _klasses = k->next_link();
547 } else {
548 Klass* next = k->next_link();
549 prev->set_next_link(next);
550 }
551 return;
552 }
553 prev = k;
554 assert(k != k->next_link(), "no loops!");
555 }
556 ShouldNotReachHere(); // should have found this class!!
557 }
558
559 void ClassLoaderData::unload() {
560 _unloading = true;
561
562 // Tell serviceability tools these classes are unloading
563 classes_do(InstanceKlass::notify_unload_class);
564
565 LogTarget(Debug, class, loader, data) lt;
566 if (lt.is_enabled()) {
567 ResourceMark rm;
568 LogStream ls(lt);
569 ls.print(": unload loader data " INTPTR_FORMAT, p2i(this));
570 ls.print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
571 loader_name());
572 if (is_anonymous()) {
573 ls.print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
574 }
575 ls.cr();
576 }
577
578 // In some rare cases items added to this list will not be freed elsewhere.
579 // To keep it simple, just free everything in it here.
580 free_deallocate_list();
581
582 // Clean up global class iterator for compiler
583 static_klass_iterator.adjust_saved_class(this);
584 }
585
586 ModuleEntryTable* ClassLoaderData::modules() {
587 // Lazily create the module entry table at first request.
588 // Lock-free access requires load_ptr_acquire.
589 ModuleEntryTable* modules = load_ptr_acquire(&_modules);
590 if (modules == NULL) {
591 MutexLocker m1(Module_lock);
592 // Check if _modules got allocated while we were waiting for this lock.
593 if ((modules = _modules) == NULL) {
594 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
595
596 {
597 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
598 // Ensure _modules is stable, since it is examined without a lock
599 OrderAccess::release_store_ptr(&_modules, modules);
600 }
601 }
602 }
603 return modules;
604 }
605
606 const int _boot_loader_dictionary_size = 1009;
607 const int _default_loader_dictionary_size = 107;
608 const int _prime_array_size = 8; // array of primes for system dictionary size
609 const int _average_depth_goal = 3; // goal for lookup length
610 const int _primelist[_prime_array_size] = {107, 1009, 2017, 4049, 5051, 10103, 20201, 40423};
611
612 // Calculate a "good" dictionary size based
613 // on predicted or current loaded classes count.
614 static int calculate_dictionary_size(int classcount) {
615 int newsize = _primelist[0];
616 if (classcount > 0 && !DumpSharedSpaces) {
617 int index = 0;
618 int desiredsize = classcount/_average_depth_goal;
619 for (newsize = _primelist[index]; index < _prime_array_size -1;
620 newsize = _primelist[++index]) {
621 if (desiredsize <= newsize) {
622 break;
623 }
624 }
625 }
626 return newsize;
627 }
628
629 Dictionary* ClassLoaderData::create_dictionary() {
630 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
631 int size;
632 if (_the_null_class_loader_data == NULL) {
633 size = _boot_loader_dictionary_size;
634 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
635 size = 1; // there's only one class in relection class loader and no initiated classes
636 } else if (is_system_class_loader_data()) {
637 size = calculate_dictionary_size(PredictedLoadedClassCount);
638 } else {
639 size = _default_loader_dictionary_size;
640 }
641 return new Dictionary(this, size);
642 }
643
644 // Unloading support
645 oop ClassLoaderData::keep_alive_object() const {
646 assert_locked_or_safepoint(_metaspace_lock);
647 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
648 return is_anonymous() ? _klasses->java_mirror() : class_loader();
649 }
650
651 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
652 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
653 || is_alive_closure->do_object_b(keep_alive_object());
654
655 return alive;
656 }
657
658 ClassLoaderData::~ClassLoaderData() {
659 // Release C heap structures for all the classes.
660 classes_do(InstanceKlass::release_C_heap_structures);
661
662 // Release C heap allocated hashtable for all the packages.
663 if (_packages != NULL) {
664 // Destroy the table itself
665 delete _packages;
666 _packages = NULL;
667 }
668
669 // Release C heap allocated hashtable for all the modules.
670 if (_modules != NULL) {
671 // Destroy the table itself
672 delete _modules;
673 _modules = NULL;
674 }
675
676 // Release C heap allocated hashtable for the dictionary
677 if (_dictionary != NULL) {
678 // Destroy the table itself
679 delete _dictionary;
680 _dictionary = NULL;
681 }
682
683 if (_unnamed_module != NULL) {
684 _unnamed_module->delete_unnamed_module();
685 _unnamed_module = NULL;
686 }
687
688 // release the metaspace
689 Metaspace *m = _metaspace;
690 if (m != NULL) {
691 _metaspace = NULL;
692 delete m;
693 }
694 // Clear all the JNI handles for methods
695 // These aren't deallocated and are going to look like a leak, but that's
696 // needed because we can't really get rid of jmethodIDs because we don't
697 // know when native code is going to stop using them. The spec says that
698 // they're "invalid" but existing programs likely rely on their being
699 // NULL after class unloading.
700 if (_jmethod_ids != NULL) {
701 Method::clear_jmethod_ids(this);
702 }
703 // Delete lock
704 delete _metaspace_lock;
705
706 // Delete free list
707 if (_deallocate_list != NULL) {
708 delete _deallocate_list;
709 }
710 }
711
712 // Returns true if this class loader data is for the system class loader.
713 bool ClassLoaderData::is_system_class_loader_data() const {
714 return SystemDictionary::is_system_class_loader(class_loader());
715 }
716
717 // Returns true if this class loader data is for the platform class loader.
718 bool ClassLoaderData::is_platform_class_loader_data() const {
719 return SystemDictionary::is_platform_class_loader(class_loader());
720 }
721
722 // Returns true if this class loader data is one of the 3 builtin
723 // (boot, application/system or platform) class loaders. Note, the
724 // builtin loaders are not freed by a GC.
725 bool ClassLoaderData::is_builtin_class_loader_data() const {
726 return (is_the_null_class_loader_data() ||
727 SystemDictionary::is_system_class_loader(class_loader()) ||
728 SystemDictionary::is_platform_class_loader(class_loader()));
729 }
730
731 Metaspace* ClassLoaderData::metaspace_non_null() {
732 // If the metaspace has not been allocated, create a new one. Might want
733 // to create smaller arena for Reflection class loaders also.
734 // The reason for the delayed allocation is because some class loaders are
735 // simply for delegating with no metadata of their own.
736 // Lock-free access requires load_ptr_acquire.
737 Metaspace* metaspace = load_ptr_acquire(&_metaspace);
738 if (metaspace == NULL) {
739 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
740 // Check if _metaspace got allocated while we were waiting for this lock.
741 if ((metaspace = _metaspace) == NULL) {
742 if (this == the_null_class_loader_data()) {
743 assert (class_loader() == NULL, "Must be");
744 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
745 } else if (is_anonymous()) {
746 if (class_loader() != NULL) {
747 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
748 }
749 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
750 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
751 if (class_loader() != NULL) {
752 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
753 }
754 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
755 } else {
756 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
757 }
758 // Ensure _metaspace is stable, since it is examined without a lock
759 OrderAccess::release_store_ptr(&_metaspace, metaspace);
760 }
761 }
762 return metaspace;
763 }
764
765 OopHandle ClassLoaderData::add_handle(Handle h) {
766 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
767 return OopHandle(_handles.add(h()));
768 }
769
770 void ClassLoaderData::remove_handle(OopHandle h) {
771 oop* ptr = h.ptr_raw();
772 if (ptr != NULL) {
773 assert(_handles.contains(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
774 #if INCLUDE_ALL_GCS
775 // This barrier is used by G1 to remember the old oop values, so
776 // that we don't forget any objects that were live at the snapshot at
777 // the beginning.
778 if (UseG1GC) {
779 oop obj = *ptr;
780 if (obj != NULL) {
781 G1SATBCardTableModRefBS::enqueue(obj);
782 }
783 }
784 #endif
785 *ptr = NULL;
786 }
787 }
788
789 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
790 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
791 if (dest.resolve() != NULL) {
792 return;
793 } else {
794 dest = _handles.add(h());
795 }
796 }
797
798 // Add this metadata pointer to be freed when it's safe. This is only during
799 // class unloading because Handles might point to this metadata field.
800 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
801 // Metadata in shared region isn't deleted.
802 if (!m->is_shared()) {
803 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
804 if (_deallocate_list == NULL) {
805 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
806 }
807 _deallocate_list->append_if_missing(m);
808 }
809 }
810
811 // Deallocate free metadata on the free list. How useful the PermGen was!
812 void ClassLoaderData::free_deallocate_list() {
813 // Don't need lock, at safepoint
814 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
815 if (_deallocate_list == NULL) {
816 return;
817 }
818 // Go backwards because this removes entries that are freed.
819 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
820 Metadata* m = _deallocate_list->at(i);
821 if (!m->on_stack()) {
822 _deallocate_list->remove_at(i);
823 // There are only three types of metadata that we deallocate directly.
824 // Cast them so they can be used by the template function.
825 if (m->is_method()) {
826 MetadataFactory::free_metadata(this, (Method*)m);
827 } else if (m->is_constantPool()) {
828 MetadataFactory::free_metadata(this, (ConstantPool*)m);
829 } else if (m->is_klass()) {
830 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
831 } else {
832 ShouldNotReachHere();
833 }
834 } else {
835 // Metadata is alive.
836 // If scratch_class is on stack then it shouldn't be on this list!
837 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
838 "scratch classes on this list should be dead");
839 // Also should assert that other metadata on the list was found in handles.
840 }
841 }
842 }
843
844 // These anonymous class loaders are to contain classes used for JSR292
845 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
846 // Add a new class loader data to the graph.
847 Handle lh(THREAD, loader);
848 return ClassLoaderDataGraph::add(lh, true, THREAD);
849 }
850
851 const char* ClassLoaderData::loader_name() {
852 // Handles null class loader
853 return SystemDictionary::loader_name(class_loader());
854 }
855
856 #ifndef PRODUCT
857 // Define to dump klasses
858 #undef CLD_DUMP_KLASSES
859
860 void ClassLoaderData::dump(outputStream * const out) {
861 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
862 p2i(this), p2i((void *)class_loader()),
863 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
864 if (claimed()) out->print(" claimed ");
865 if (is_unloading()) out->print(" unloading ");
866 out->cr();
867 if (metaspace_or_null() != NULL) {
868 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
869 metaspace_or_null()->dump(out);
870 } else {
871 out->print_cr("metaspace: NULL");
872 }
873
874 #ifdef CLD_DUMP_KLASSES
875 if (Verbose) {
876 Klass* k = _klasses;
877 while (k != NULL) {
878 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
879 k->has_modified_oops(), k->has_accumulated_modified_oops());
880 assert(k != k->next_link(), "no loops!");
881 k = k->next_link();
882 }
883 }
884 #endif // CLD_DUMP_KLASSES
885 #undef CLD_DUMP_KLASSES
886 if (_jmethod_ids != NULL) {
887 Method::print_jmethod_ids(this, out);
888 }
889 out->print_cr("}");
890 }
891 #endif // PRODUCT
892
893 void ClassLoaderData::verify() {
894 assert_locked_or_safepoint(_metaspace_lock);
895 oop cl = class_loader();
896
897 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
898 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
899
900 // Verify the integrity of the allocated space.
901 if (metaspace_or_null() != NULL) {
902 metaspace_or_null()->verify();
903 }
904
905 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
906 guarantee(k->class_loader_data() == this, "Must be the same");
907 k->verify();
908 assert(k != k->next_link(), "no loops!");
909 }
910 }
911
912 bool ClassLoaderData::contains_klass(Klass* klass) {
913 // Lock-free access requires load_ptr_acquire
914 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
915 if (k == klass) return true;
916 }
917 return false;
918 }
919
920
921 // GC root of class loader data created.
922 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
923 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
924 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
925 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
926
927 bool ClassLoaderDataGraph::_should_purge = false;
928 bool ClassLoaderDataGraph::_metaspace_oom = false;
929
930 // Add a new class loader data node to the list. Assign the newly created
931 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
932 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
933 // We need to allocate all the oops for the ClassLoaderData before allocating the
934 // actual ClassLoaderData object.
935 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
936
937 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
938 // ClassLoaderData in the graph since the CLD
939 // contains unhandled oops
940
941 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
942
943
944 if (!is_anonymous) {
945 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
946 // First, Atomically set it
947 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
948 if (old != NULL) {
949 delete cld;
950 // Returns the data.
951 return old;
952 }
953 }
954
955 // We won the race, and therefore the task of adding the data to the list of
956 // class loader data
957 ClassLoaderData** list_head = &_head;
958 ClassLoaderData* next = _head;
959
960 do {
961 cld->set_next(next);
962 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
963 if (exchanged == next) {
964 LogTarget(Debug, class, loader, data) lt;
965 if (lt.is_enabled()) {
966 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
967 LogStream ls(lt);
968 print_creation(&ls, loader, cld, CHECK_NULL);
969 }
970 return cld;
971 }
972 next = exchanged;
973 } while (true);
974 }
975
976 void ClassLoaderDataGraph::print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS) {
977 Handle string;
978 if (loader.not_null()) {
979 // Include the result of loader.toString() in the output. This allows
980 // the user of the log to identify the class loader instance.
981 JavaValue result(T_OBJECT);
982 Klass* spec_klass = SystemDictionary::ClassLoader_klass();
983 JavaCalls::call_virtual(&result,
984 loader,
985 spec_klass,
986 vmSymbols::toString_name(),
987 vmSymbols::void_string_signature(),
988 CHECK);
989 assert(result.get_type() == T_OBJECT, "just checking");
990 string = Handle(THREAD, (oop)result.get_jobject());
991 }
992
993 ResourceMark rm;
994 out->print("create class loader data " INTPTR_FORMAT, p2i(cld));
995 out->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
996 cld->loader_name());
997
998 if (string.not_null()) {
999 out->print(": ");
1000 java_lang_String::print(string(), out);
1001 }
1002 out->cr();
1003 }
1004
1005
1006 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
1007 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1008 cld->oops_do(f, klass_closure, must_claim);
1009 }
1010 }
1011
1012 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
1013 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1014 if (cld->keep_alive()) {
1015 cld->oops_do(f, klass_closure, must_claim);
1016 }
1017 }
1018 }
1019
1020 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
1021 if (ClassUnloading) {
1022 keep_alive_oops_do(f, klass_closure, must_claim);
1023 } else {
1024 oops_do(f, klass_closure, must_claim);
1025 }
1026 }
1027
1028 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1029 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1030 cl->do_cld(cld);
1031 }
1032 }
1033
1034 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1035 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1036 // Only walk the head until any clds not purged from prior unloading
1037 // (CMS doesn't purge right away).
1038 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1039 assert(cld->is_unloading(), "invariant");
1040 cl->do_cld(cld);
1041 }
1042 }
1043
1044 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1045 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1046 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1047 if (closure != NULL) {
1048 closure->do_cld(cld);
1049 }
1050 }
1051 }
1052
1053 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1054 roots_cld_do(cl, NULL);
1055 }
1056
1057 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1058 if (ClassUnloading) {
1059 keep_alive_cld_do(cl);
1060 } else {
1061 cld_do(cl);
1062 }
1063 }
1064
1065 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1066 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1067 cld->classes_do(klass_closure);
1068 }
1069 }
1070
1071 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1072 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1073 cld->classes_do(f);
1074 }
1075 }
1076
1077 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1078 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1079 cld->methods_do(f);
1080 }
1081 }
1082
1083 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1084 assert_locked_or_safepoint(Module_lock);
1085 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1086 cld->modules_do(f);
1087 }
1088 }
1089
1090 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1091 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1092 // Only walk the head until any clds not purged from prior unloading
1093 // (CMS doesn't purge right away).
1094 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1095 assert(cld->is_unloading(), "invariant");
1096 cld->modules_do(f);
1097 }
1098 }
1099
1100 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1101 assert_locked_or_safepoint(Module_lock);
1102 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1103 cld->packages_do(f);
1104 }
1105 }
1106
1107 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1108 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1109 // Only walk the head until any clds not purged from prior unloading
1110 // (CMS doesn't purge right away).
1111 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1112 assert(cld->is_unloading(), "invariant");
1113 cld->packages_do(f);
1114 }
1115 }
1116
1117 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1118 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1119 cld->loaded_classes_do(klass_closure);
1120 }
1121 }
1122
1123 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1124 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1125 // Only walk the head until any clds not purged from prior unloading
1126 // (CMS doesn't purge right away).
1127 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1128 assert(cld->is_unloading(), "invariant");
1129 cld->classes_do(f);
1130 }
1131 }
1132
1133 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1134 if (X->dictionary() != NULL)
1135
1136 // Walk classes in the loaded class dictionaries in various forms.
1137 // Only walks the classes defined in this class loader.
1138 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1139 FOR_ALL_DICTIONARY(cld) {
1140 cld->dictionary()->classes_do(f);
1141 }
1142 }
1143
1144 // Only walks the classes defined in this class loader.
1145 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1146 FOR_ALL_DICTIONARY(cld) {
1147 cld->dictionary()->classes_do(f, CHECK);
1148 }
1149 }
1150
1151 // Walks all entries in the dictionary including entries initiated by this class loader.
1152 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1153 FOR_ALL_DICTIONARY(cld) {
1154 cld->dictionary()->all_entries_do(f);
1155 }
1156 }
1157
1158 void ClassLoaderDataGraph::verify_dictionary() {
1159 FOR_ALL_DICTIONARY(cld) {
1160 cld->dictionary()->verify();
1161 }
1162 }
1163
1164 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1165 FOR_ALL_DICTIONARY(cld) {
1166 st->print("Dictionary for ");
1167 cld->print_value_on(st);
1168 st->cr();
1169 cld->dictionary()->print_on(st);
1170 st->cr();
1171 }
1172 }
1173
1174 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1175 FOR_ALL_DICTIONARY(cld) {
1176 ResourceMark rm;
1177 stringStream tempst;
1178 tempst.print("System Dictionary for %s", cld->loader_name());
1179 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1180 }
1181 }
1182
1183 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1184 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1185
1186 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1187
1188 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1189 ClassLoaderData* curr = _head;
1190 while (curr != _saved_head) {
1191 if (!curr->claimed()) {
1192 array->push(curr);
1193 LogTarget(Debug, class, loader, data) lt;
1194 if (lt.is_enabled()) {
1195 LogStream ls(lt);
1196 ls.print("found new CLD: ");
1197 curr->print_value_on(&ls);
1198 ls.cr();
1199 }
1200 }
1201
1202 curr = curr->_next;
1203 }
1204
1205 return array;
1206 }
1207
1208 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
1209 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
1210 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
1211 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
1212 return true;
1213 }
1214 }
1215 return false;
1216 }
1217
1218 #ifndef PRODUCT
1219 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1220 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1221 if (loader_data == data) {
1222 return true;
1223 }
1224 }
1225
1226 return false;
1227 }
1228 #endif // PRODUCT
1229
1230
1231 // Move class loader data from main list to the unloaded list for unloading
1232 // and deallocation later.
1233 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1234 bool clean_previous_versions) {
1235
1236 ClassLoaderData* data = _head;
1237 ClassLoaderData* prev = NULL;
1238 bool seen_dead_loader = false;
1239
1240 // Mark metadata seen on the stack only so we can delete unneeded entries.
1241 // Only walk all metadata, including the expensive code cache walk, for Full GC
1242 // and only if class redefinition and if there's previous versions of
1243 // Klasses to delete.
1244 bool walk_all_metadata = clean_previous_versions &&
1245 JvmtiExport::has_redefined_a_class() &&
1246 InstanceKlass::has_previous_versions_and_reset();
1247 MetadataOnStackMark md_on_stack(walk_all_metadata);
1248
1249 // Save previous _unloading pointer for CMS which may add to unloading list before
1250 // purging and we don't want to rewalk the previously unloaded class loader data.
1251 _saved_unloading = _unloading;
1252
1253 data = _head;
1254 while (data != NULL) {
1255 if (data->is_alive(is_alive_closure)) {
1256 // clean metaspace
1257 if (walk_all_metadata) {
1258 data->classes_do(InstanceKlass::purge_previous_versions);
1259 }
1260 data->free_deallocate_list();
1261 prev = data;
1262 data = data->next();
1263 continue;
1264 }
1265 seen_dead_loader = true;
1266 ClassLoaderData* dead = data;
1267 dead->unload();
1268 data = data->next();
1269 // Remove from loader list.
1270 // This class loader data will no longer be found
1271 // in the ClassLoaderDataGraph.
1272 if (prev != NULL) {
1273 prev->set_next(data);
1274 } else {
1275 assert(dead == _head, "sanity check");
1276 _head = data;
1277 }
1278 dead->set_next(_unloading);
1279 _unloading = dead;
1280 }
1281
1282 if (seen_dead_loader) {
1283 data = _head;
1284 while (data != NULL) {
1285 // Remove entries in the dictionary of live class loader that have
1286 // initiated loading classes in a dead class loader.
1287 if (data->dictionary() != NULL) {
1288 data->dictionary()->do_unloading();
1289 }
1290 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1291 // lists to determine if there are modules on those lists that are now
1292 // dead and should be removed. A module's life cycle is equivalent
1293 // to its defining class loader's life cycle. Since a module is
1294 // considered dead if its class loader is dead, these walks must
1295 // occur after each class loader's aliveness is determined.
1296 if (data->packages() != NULL) {
1297 data->packages()->purge_all_package_exports();
1298 }
1299 if (data->modules_defined()) {
1300 data->modules()->purge_all_module_reads();
1301 }
1302 data = data->next();
1303 }
1304
1305 post_class_unload_events();
1306 }
1307
1308 return seen_dead_loader;
1309 }
1310
1311 void ClassLoaderDataGraph::purge() {
1312 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1313 ClassLoaderData* list = _unloading;
1314 _unloading = NULL;
1315 ClassLoaderData* next = list;
1316 bool classes_unloaded = false;
1317 while (next != NULL) {
1318 ClassLoaderData* purge_me = next;
1319 next = purge_me->next();
1320 delete purge_me;
1321 classes_unloaded = true;
1322 }
1323 if (classes_unloaded) {
1324 Metaspace::purge();
1325 set_metaspace_oom(false);
1326 }
1327 }
1328
1329 void ClassLoaderDataGraph::post_class_unload_events() {
1330 #if INCLUDE_TRACE
1331 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1332 if (Tracing::enabled()) {
1333 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1334 assert(_unloading != NULL, "need class loader data unload list!");
1335 _class_unload_time = Ticks::now();
1336 classes_unloading_do(&class_unload_event);
1337 }
1338 Tracing::on_unloading_classes();
1339 }
1340 #endif
1341 }
1342
1343 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1344 : _next_klass(NULL) {
1345 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1346 Klass* klass = NULL;
1347
1348 // Find the first klass in the CLDG.
1349 while (cld != NULL) {
1350 assert_locked_or_safepoint(cld->metaspace_lock());
1351 klass = cld->_klasses;
1352 if (klass != NULL) {
1353 _next_klass = klass;
1354 return;
1355 }
1356 cld = cld->next();
1357 }
1358 }
1359
1360 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1361 Klass* next = klass->next_link();
1362 if (next != NULL) {
1363 return next;
1364 }
1365
1366 // No more klasses in the current CLD. Time to find a new CLD.
1367 ClassLoaderData* cld = klass->class_loader_data();
1368 assert_locked_or_safepoint(cld->metaspace_lock());
1369 while (next == NULL) {
1370 cld = cld->next();
1371 if (cld == NULL) {
1372 break;
1373 }
1374 next = cld->_klasses;
1375 }
1376
1377 return next;
1378 }
1379
1380 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1381 Klass* head = _next_klass;
1382
1383 while (head != NULL) {
1384 Klass* next = next_klass_in_cldg(head);
1385
1386 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
1387
1388 if (old_head == head) {
1389 return head; // Won the CAS.
1390 }
1391
1392 head = old_head;
1393 }
1394
1395 // Nothing more for the iterator to hand out.
1396 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1397 return NULL;
1398 }
1399
1400 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1401 _data = ClassLoaderDataGraph::_head;
1402 }
1403
1404 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1405
1406 #ifndef PRODUCT
1407 // callable from debugger
1408 extern "C" int print_loader_data_graph() {
1409 ClassLoaderDataGraph::dump_on(tty);
1410 return 0;
1411 }
1412
1413 void ClassLoaderDataGraph::verify() {
1414 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1415 data->verify();
1416 }
1417 }
1418
1419 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1420 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1421 data->dump(out);
1422 }
1423 MetaspaceAux::dump(out);
1424 }
1425 #endif // PRODUCT
1426
1427 void ClassLoaderData::print_value_on(outputStream* out) const {
1428 if (class_loader() == NULL) {
1429 out->print("NULL class loader");
1430 } else {
1431 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1432 class_loader()->print_value_on(out);
1433 }
1434 }
1435
1436 void ClassLoaderData::print_on(outputStream* out) const {
1437 if (class_loader() == NULL) {
1438 out->print("NULL class loader");
1439 } else {
1440 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1441 class_loader()->print_on(out);
1442 }
1443 }
1444
1445 #if INCLUDE_TRACE
1446
1447 Ticks ClassLoaderDataGraph::_class_unload_time;
1448
1449 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1450 assert(k != NULL, "invariant");
1451
1452 // post class unload event
1453 EventClassUnload event(UNTIMED);
1454 event.set_endtime(_class_unload_time);
1455 event.set_unloadedClass(k);
1456 event.set_definingClassLoader(k->class_loader_data());
1457 event.commit();
1458 }
1459
1460 #endif // INCLUDE_TRACE