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