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