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