1 /*
2 * Copyright (c) 2012, 2018, 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/access.inline.hpp"
67 #include "oops/objArrayOop.inline.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.hpp"
70 #include "runtime/javaCalls.hpp"
71 #include "runtime/jniHandles.hpp"
72 #include "runtime/mutex.hpp"
73 #include "runtime/orderAccess.hpp"
74 #include "runtime/safepoint.hpp"
75 #include "runtime/synchronizer.hpp"
76 #include "utilities/growableArray.hpp"
77 #include "utilities/macros.hpp"
78 #include "utilities/ostream.hpp"
79 #if INCLUDE_TRACE
80 #include "trace/tracing.hpp"
81 #endif
82
83 volatile size_t ClassLoaderDataGraph::_num_array_classes = 0;
84 volatile size_t ClassLoaderDataGraph::_num_instance_classes = 0;
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), _modified_oops(true), _accumulated_modified_oops(false),
98 _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(&_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 = OrderAccess::load_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 // ASSERT
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, bool must_claim, bool clear_mod_oops) {
237 if (must_claim && !claim()) {
238 return;
239 }
240
241 // Only clear modified_oops after the ClassLoaderData is claimed.
242 if (clear_mod_oops) {
243 clear_modified_oops();
244 }
245
246 f->do_oop(&_class_loader);
247 _dependencies.oops_do(f);
248 _handles.oops_do(f);
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_acquire
257 for (Klass* k = OrderAccess::load_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_acquire
265 for (Klass* k = OrderAccess::load_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_acquire
273 for (Klass* k = OrderAccess::load_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_acquire
282 for (Klass* k = OrderAccess::load_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_acquire
292 for (Klass* k = OrderAccess::load_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 // Do not need to record dependency if the dependency is to a class whose
336 // class loader data is never freed. (i.e. the dependency's class loader
337 // is one of the three builtin class loaders and the dependency is not
338 // anonymous.)
339 if (to_cld->is_permanent_class_loader_data()) {
340 return;
341 }
342
343 oop to;
344 if (to_cld->is_anonymous()) {
345 // Just return if an anonymous class is attempting to record a dependency
346 // to itself. (Note that every anonymous class has its own unique class
347 // loader data.)
348 if (to_cld == from_cld) {
349 return;
350 }
351 // Anonymous class dependencies are through the mirror.
352 to = k->java_mirror();
353 } else {
354 to = to_cld->class_loader();
355 oop from = from_cld->class_loader();
356
357 // Just return if this dependency is to a class with the same or a parent
358 // class_loader.
359 if (from == to || java_lang_ClassLoader::isAncestor(from, to)) {
360 return; // this class loader is in the parent list, no need to add it.
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 // Added a potentially young gen oop to the ClassLoaderData
370 record_modified_oops();
371 }
372
373
374 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
375 // Check first if this dependency is already in the list.
376 // Save a pointer to the last to add to under the lock.
377 objArrayOop ok = _list_head;
378 objArrayOop last = NULL;
379 while (ok != NULL) {
380 last = ok;
381 if (ok->obj_at(0) == dependency()) {
382 // Don't need to add it
383 return;
384 }
385 ok = (objArrayOop)ok->obj_at(1);
386 }
387
388 // Must handle over GC points
389 assert (last != NULL, "dependencies should be initialized");
390 objArrayHandle last_handle(THREAD, last);
391
392 // Create a new dependency node with fields for (class_loader or mirror, next)
393 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
394 deps->obj_at_put(0, dependency());
395
396 // Must handle over GC points
397 objArrayHandle new_dependency(THREAD, deps);
398
399 // Add the dependency under lock
400 locked_add(last_handle, new_dependency, THREAD);
401 }
402
403 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
404 objArrayHandle new_dependency,
405 Thread* THREAD) {
406
407 // Have to lock and put the new dependency on the end of the dependency
408 // array so the card mark for CMS sees that this dependency is new.
409 // Can probably do this lock free with some effort.
410 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
411
412 oop loader_or_mirror = new_dependency->obj_at(0);
413
414 // Since the dependencies are only added, add to the end.
415 objArrayOop end = last_handle();
416 objArrayOop last = NULL;
417 while (end != NULL) {
418 last = end;
419 // check again if another thread added it to the end.
420 if (end->obj_at(0) == loader_or_mirror) {
421 // Don't need to add it
422 return;
423 }
424 end = (objArrayOop)end->obj_at(1);
425 }
426 assert (last != NULL, "dependencies should be initialized");
427 // fill in the first element with the oop in new_dependency.
428 if (last->obj_at(0) == NULL) {
429 last->obj_at_put(0, new_dependency->obj_at(0));
430 } else {
431 last->obj_at_put(1, new_dependency());
432 }
433 }
434
435 void ClassLoaderDataGraph::clear_claimed_marks() {
436 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
437 cld->clear_claimed();
438 }
439 }
440
441 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
442 {
443 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
444 Klass* old_value = _klasses;
445 k->set_next_link(old_value);
446 // Link the new item into the list, making sure the linked class is stable
447 // since the list can be walked without a lock
448 OrderAccess::release_store(&_klasses, k);
449 if (k->is_array_klass()) {
450 ClassLoaderDataGraph::inc_array_classes(1);
451 } else {
452 ClassLoaderDataGraph::inc_instance_classes(1);
453 }
454 }
455
456 if (publicize && k->class_loader_data() != NULL) {
457 ResourceMark rm;
458 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
459 PTR_FORMAT " loader: " PTR_FORMAT " %s",
460 p2i(k),
461 k->external_name(),
462 p2i(k->class_loader_data()),
463 p2i((void *)k->class_loader()),
464 loader_name());
465 }
466 }
467
468 // Class iterator used by the compiler. It gets some number of classes at
469 // a safepoint to decay invocation counters on the methods.
470 class ClassLoaderDataGraphKlassIteratorStatic {
471 ClassLoaderData* _current_loader_data;
472 Klass* _current_class_entry;
473 public:
474
475 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
476
477 InstanceKlass* try_get_next_class() {
478 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
479 size_t max_classes = ClassLoaderDataGraph::num_instance_classes();
480 assert(max_classes > 0, "should not be called with no instance classes");
481 for (size_t i = 0; i < max_classes; ) {
482
483 if (_current_class_entry != NULL) {
484 Klass* k = _current_class_entry;
485 _current_class_entry = _current_class_entry->next_link();
486
487 if (k->is_instance_klass()) {
488 InstanceKlass* ik = InstanceKlass::cast(k);
489 i++; // count all instance classes found
490 // Not yet loaded classes are counted in max_classes
491 // but only return loaded classes.
492 if (ik->is_loaded()) {
493 return ik;
494 }
495 }
496 } else {
497 // Go to next CLD
498 if (_current_loader_data != NULL) {
499 _current_loader_data = _current_loader_data->next();
500 }
501 // Start at the beginning
502 if (_current_loader_data == NULL) {
503 _current_loader_data = ClassLoaderDataGraph::_head;
504 }
505
506 _current_class_entry = _current_loader_data->klasses();
507 }
508 }
509 // Should never be reached unless all instance classes have failed or are not fully loaded.
510 // Caller handles NULL.
511 return NULL;
512 }
513
514 // If the current class for the static iterator is a class being unloaded or
515 // deallocated, adjust the current class.
516 void adjust_saved_class(ClassLoaderData* cld) {
517 if (_current_loader_data == cld) {
518 _current_loader_data = cld->next();
519 if (_current_loader_data != NULL) {
520 _current_class_entry = _current_loader_data->klasses();
521 } // else try_get_next_class will start at the head
522 }
523 }
524
525 void adjust_saved_class(Klass* klass) {
526 if (_current_class_entry == klass) {
527 _current_class_entry = klass->next_link();
528 }
529 }
530 };
531
532 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
533
534 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
535 return static_klass_iterator.try_get_next_class();
536 }
537
538
539 // Remove a klass from the _klasses list for scratch_class during redefinition
540 // or parsed class in the case of an error.
541 void ClassLoaderData::remove_class(Klass* scratch_class) {
542 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
543
544 // Adjust global class iterator.
545 static_klass_iterator.adjust_saved_class(scratch_class);
546
547 Klass* prev = NULL;
548 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
549 if (k == scratch_class) {
550 if (prev == NULL) {
551 _klasses = k->next_link();
552 } else {
553 Klass* next = k->next_link();
554 prev->set_next_link(next);
555 }
556
557 if (k->is_array_klass()) {
558 ClassLoaderDataGraph::dec_array_classes(1);
559 } else {
560 ClassLoaderDataGraph::dec_instance_classes(1);
561 }
562
563 return;
564 }
565 prev = k;
566 assert(k != k->next_link(), "no loops!");
567 }
568 ShouldNotReachHere(); // should have found this class!!
569 }
570
571 void ClassLoaderData::unload() {
572 _unloading = true;
573
574 // Tell serviceability tools these classes are unloading
575 classes_do(InstanceKlass::notify_unload_class);
576
577 LogTarget(Debug, class, loader, data) lt;
578 if (lt.is_enabled()) {
579 ResourceMark rm;
580 LogStream ls(lt);
581 ls.print(": unload loader data " INTPTR_FORMAT, p2i(this));
582 ls.print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
583 loader_name());
584 if (is_anonymous()) {
585 ls.print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
586 }
587 ls.cr();
588 }
589
590 // Some items on the _deallocate_list need to free their C heap structures
591 // if they are not already on the _klasses list.
592 unload_deallocate_list();
593
594 // Clean up global class iterator for compiler
595 static_klass_iterator.adjust_saved_class(this);
596 }
597
598 ModuleEntryTable* ClassLoaderData::modules() {
599 // Lazily create the module entry table at first request.
600 // Lock-free access requires load_acquire.
601 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
602 if (modules == NULL) {
603 MutexLocker m1(Module_lock);
604 // Check if _modules got allocated while we were waiting for this lock.
605 if ((modules = _modules) == NULL) {
606 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
607
608 {
609 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
610 // Ensure _modules is stable, since it is examined without a lock
611 OrderAccess::release_store(&_modules, modules);
612 }
613 }
614 }
615 return modules;
616 }
617
618 const int _boot_loader_dictionary_size = 1009;
619 const int _default_loader_dictionary_size = 107;
620
621 Dictionary* ClassLoaderData::create_dictionary() {
622 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
623 int size;
624 bool resizable = false;
625 if (_the_null_class_loader_data == NULL) {
626 size = _boot_loader_dictionary_size;
627 resizable = true;
628 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
629 size = 1; // there's only one class in relection class loader and no initiated classes
630 } else if (is_system_class_loader_data()) {
631 size = _boot_loader_dictionary_size;
632 resizable = true;
633 } else {
634 size = _default_loader_dictionary_size;
635 resizable = true;
636 }
637 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) {
638 resizable = false;
639 }
640 return new Dictionary(this, size, resizable);
641 }
642
643 // Unloading support
644 oop ClassLoaderData::keep_alive_object() const {
645 assert_locked_or_safepoint(_metaspace_lock);
646 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
647 return is_anonymous() ? _klasses->java_mirror() : class_loader();
648 }
649
650 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
651 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
652 || is_alive_closure->do_object_b(keep_alive_object());
653
654 return alive;
655 }
656
657 class ReleaseKlassClosure: public KlassClosure {
658 private:
659 size_t _instance_class_released;
660 size_t _array_class_released;
661 public:
662 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
663
664 size_t instance_class_released() const { return _instance_class_released; }
665 size_t array_class_released() const { return _array_class_released; }
666
667 void do_klass(Klass* k) {
668 if (k->is_array_klass()) {
669 _array_class_released ++;
670 } else {
671 assert(k->is_instance_klass(), "Must be");
672 _instance_class_released ++;
673 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
674 }
675 }
676 };
677
678 ClassLoaderData::~ClassLoaderData() {
679 // Release C heap structures for all the classes.
680 ReleaseKlassClosure cl;
681 classes_do(&cl);
682
683 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
684 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
685
686 // Release C heap allocated hashtable for all the packages.
687 if (_packages != NULL) {
688 // Destroy the table itself
689 delete _packages;
690 _packages = NULL;
691 }
692
693 // Release C heap allocated hashtable for all the modules.
694 if (_modules != NULL) {
695 // Destroy the table itself
696 delete _modules;
697 _modules = NULL;
698 }
699
700 // Release C heap allocated hashtable for the dictionary
701 if (_dictionary != NULL) {
702 // Destroy the table itself
703 delete _dictionary;
704 _dictionary = NULL;
705 }
706
707 if (_unnamed_module != NULL) {
708 _unnamed_module->delete_unnamed_module();
709 _unnamed_module = NULL;
710 }
711
712 // release the metaspace
713 Metaspace *m = _metaspace;
714 if (m != NULL) {
715 _metaspace = NULL;
716 delete m;
717 }
718 // Clear all the JNI handles for methods
719 // These aren't deallocated and are going to look like a leak, but that's
720 // needed because we can't really get rid of jmethodIDs because we don't
721 // know when native code is going to stop using them. The spec says that
722 // they're "invalid" but existing programs likely rely on their being
723 // NULL after class unloading.
724 if (_jmethod_ids != NULL) {
725 Method::clear_jmethod_ids(this);
726 }
727 // Delete lock
728 delete _metaspace_lock;
729
730 // Delete free list
731 if (_deallocate_list != NULL) {
732 delete _deallocate_list;
733 }
734 }
735
736 // Returns true if this class loader data is for the app class loader
737 // or a user defined system class loader. (Note that the class loader
738 // data may be anonymous.)
739 bool ClassLoaderData::is_system_class_loader_data() const {
740 return SystemDictionary::is_system_class_loader(class_loader());
741 }
742
743 // Returns true if this class loader data is for the platform class loader.
744 // (Note that the class loader data may be anonymous.)
745 bool ClassLoaderData::is_platform_class_loader_data() const {
746 return SystemDictionary::is_platform_class_loader(class_loader());
747 }
748
749 // Returns true if the class loader for this class loader data is one of
750 // the 3 builtin (boot application/system or platform) class loaders,
751 // including a user-defined system class loader. Note that if the class
752 // loader data is for an anonymous class then it may get freed by a GC
753 // even if its class loader is one of these loaders.
754 bool ClassLoaderData::is_builtin_class_loader_data() const {
755 return (is_boot_class_loader_data() ||
756 SystemDictionary::is_system_class_loader(class_loader()) ||
757 SystemDictionary::is_platform_class_loader(class_loader()));
758 }
759
760 // Returns true if this class loader data is a class loader data
761 // that is not ever freed by a GC. It must be one of the builtin
762 // class loaders and not anonymous.
763 bool ClassLoaderData::is_permanent_class_loader_data() const {
764 return is_builtin_class_loader_data() && !is_anonymous();
765 }
766
767 Metaspace* ClassLoaderData::metaspace_non_null() {
768 // If the metaspace has not been allocated, create a new one. Might want
769 // to create smaller arena for Reflection class loaders also.
770 // The reason for the delayed allocation is because some class loaders are
771 // simply for delegating with no metadata of their own.
772 // Lock-free access requires load_acquire.
773 Metaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
774 if (metaspace == NULL) {
775 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
776 // Check if _metaspace got allocated while we were waiting for this lock.
777 if ((metaspace = _metaspace) == NULL) {
778 if (this == the_null_class_loader_data()) {
779 assert (class_loader() == NULL, "Must be");
780 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
781 } else if (is_anonymous()) {
782 if (class_loader() != NULL) {
783 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
784 }
785 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
786 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
787 if (class_loader() != NULL) {
788 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
789 }
790 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
791 } else {
792 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
793 }
794 // Ensure _metaspace is stable, since it is examined without a lock
795 OrderAccess::release_store(&_metaspace, metaspace);
796 }
797 }
798 return metaspace;
799 }
800
801 OopHandle ClassLoaderData::add_handle(Handle h) {
802 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
803 record_modified_oops();
804 return OopHandle(_handles.add(h()));
805 }
806
807 void ClassLoaderData::remove_handle(OopHandle h) {
808 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
809 oop* ptr = h.ptr_raw();
810 if (ptr != NULL) {
811 assert(_handles.contains(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
812 // This root is not walked in safepoints, and hence requires an appropriate
813 // decorator that e.g. maintains the SATB invariant in SATB collectors.
814 RootAccess<IN_CONCURRENT_ROOT>::oop_store(ptr, oop(NULL));
815 }
816 }
817
818 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
819 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
820 if (dest.resolve() != NULL) {
821 return;
822 } else {
823 dest = _handles.add(h());
824 }
825 }
826
827 // Add this metadata pointer to be freed when it's safe. This is only during
828 // class unloading because Handles might point to this metadata field.
829 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
830 // Metadata in shared region isn't deleted.
831 if (!m->is_shared()) {
832 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
833 if (_deallocate_list == NULL) {
834 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
835 }
836 _deallocate_list->append_if_missing(m);
837 }
838 }
839
840 // Deallocate free metadata on the free list. How useful the PermGen was!
841 void ClassLoaderData::free_deallocate_list() {
842 // Don't need lock, at safepoint
843 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
844 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
845 if (_deallocate_list == NULL) {
846 return;
847 }
848 // Go backwards because this removes entries that are freed.
849 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
850 Metadata* m = _deallocate_list->at(i);
851 if (!m->on_stack()) {
852 _deallocate_list->remove_at(i);
853 // There are only three types of metadata that we deallocate directly.
854 // Cast them so they can be used by the template function.
855 if (m->is_method()) {
856 MetadataFactory::free_metadata(this, (Method*)m);
857 } else if (m->is_constantPool()) {
858 MetadataFactory::free_metadata(this, (ConstantPool*)m);
859 } else if (m->is_klass()) {
860 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
861 } else {
862 ShouldNotReachHere();
863 }
864 } else {
865 // Metadata is alive.
866 // If scratch_class is on stack then it shouldn't be on this list!
867 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
868 "scratch classes on this list should be dead");
869 // Also should assert that other metadata on the list was found in handles.
870 }
871 }
872 }
873
874 // This is distinct from free_deallocate_list. For class loader data that are
875 // unloading, this frees the C heap memory for items on the list, and unlinks
876 // scratch or error classes so that unloading events aren't triggered for these
877 // classes. The metadata is removed with the unloading metaspace.
878 // There isn't C heap memory allocated for methods, so nothing is done for them.
879 void ClassLoaderData::unload_deallocate_list() {
880 // Don't need lock, at safepoint
881 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
882 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
883 if (_deallocate_list == NULL) {
884 return;
885 }
886 // Go backwards because this removes entries that are freed.
887 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
888 Metadata* m = _deallocate_list->at(i);
889 assert (!m->on_stack(), "wouldn't be unloading if this were so");
890 _deallocate_list->remove_at(i);
891 if (m->is_constantPool()) {
892 ((ConstantPool*)m)->release_C_heap_structures();
893 } else if (m->is_klass()) {
894 InstanceKlass* ik = (InstanceKlass*)m;
895 // also releases ik->constants() C heap memory
896 InstanceKlass::release_C_heap_structures(ik);
897 // Remove the class so unloading events aren't triggered for
898 // this class (scratch or error class) in do_unloading().
899 remove_class(ik);
900 }
901 }
902 }
903
904 // These anonymous class loaders are to contain classes used for JSR292
905 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
906 // Add a new class loader data to the graph.
907 Handle lh(THREAD, loader);
908 return ClassLoaderDataGraph::add(lh, true, THREAD);
909 }
910
911 const char* ClassLoaderData::loader_name() {
912 // Handles null class loader
913 return SystemDictionary::loader_name(class_loader());
914 }
915
916 #ifndef PRODUCT
917 // Define to dump klasses
918 #undef CLD_DUMP_KLASSES
919
920 void ClassLoaderData::dump(outputStream * const out) {
921 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
922 p2i(this), p2i((void *)class_loader()),
923 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
924 if (claimed()) out->print(" claimed ");
925 if (is_unloading()) out->print(" unloading ");
926 out->cr();
927 if (metaspace_or_null() != NULL) {
928 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
929 metaspace_or_null()->dump(out);
930 } else {
931 out->print_cr("metaspace: NULL");
932 }
933
934 #ifdef CLD_DUMP_KLASSES
935 if (Verbose) {
936 Klass* k = _klasses;
937 while (k != NULL) {
938 out->print_cr("klass " PTR_FORMAT ", %s", p2i(k), k->name()->as_C_string());
939 assert(k != k->next_link(), "no loops!");
940 k = k->next_link();
941 }
942 }
943 #endif // CLD_DUMP_KLASSES
944 #undef CLD_DUMP_KLASSES
945 if (_jmethod_ids != NULL) {
946 Method::print_jmethod_ids(this, out);
947 }
948 out->print_cr("}");
949 }
950 #endif // PRODUCT
951
952 void ClassLoaderData::verify() {
953 assert_locked_or_safepoint(_metaspace_lock);
954 oop cl = class_loader();
955
956 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
957 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
958
959 // Verify the integrity of the allocated space.
960 if (metaspace_or_null() != NULL) {
961 metaspace_or_null()->verify();
962 }
963
964 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
965 guarantee(k->class_loader_data() == this, "Must be the same");
966 k->verify();
967 assert(k != k->next_link(), "no loops!");
968 }
969 }
970
971 bool ClassLoaderData::contains_klass(Klass* klass) {
972 // Lock-free access requires load_acquire
973 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
974 if (k == klass) return true;
975 }
976 return false;
977 }
978
979
980 // GC root of class loader data created.
981 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
982 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
983 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
984 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
985
986 bool ClassLoaderDataGraph::_should_purge = false;
987 bool ClassLoaderDataGraph::_metaspace_oom = false;
988
989 // Add a new class loader data node to the list. Assign the newly created
990 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
991 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
992 // We need to allocate all the oops for the ClassLoaderData before allocating the
993 // actual ClassLoaderData object.
994 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
995
996 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
997 // ClassLoaderData in the graph since the CLD
998 // contains unhandled oops
999
1000 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
1001
1002
1003 if (!is_anonymous) {
1004 // First, Atomically set it
1005 ClassLoaderData* old = java_lang_ClassLoader::cmpxchg_loader_data(cld, loader(), NULL);
1006 if (old != NULL) {
1007 delete cld;
1008 // Returns the data.
1009 return old;
1010 }
1011 }
1012
1013 // We won the race, and therefore the task of adding the data to the list of
1014 // class loader data
1015 ClassLoaderData** list_head = &_head;
1016 ClassLoaderData* next = _head;
1017
1018 do {
1019 cld->set_next(next);
1020 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next);
1021 if (exchanged == next) {
1022 LogTarget(Debug, class, loader, data) lt;
1023 if (lt.is_enabled()) {
1024 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
1025 LogStream ls(lt);
1026 print_creation(&ls, loader, cld, CHECK_NULL);
1027 }
1028 return cld;
1029 }
1030 next = exchanged;
1031 } while (true);
1032 }
1033
1034 void ClassLoaderDataGraph::print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS) {
1035 Handle string;
1036 if (loader.not_null()) {
1037 // Include the result of loader.toString() in the output. This allows
1038 // the user of the log to identify the class loader instance.
1039 JavaValue result(T_OBJECT);
1040 Klass* spec_klass = SystemDictionary::ClassLoader_klass();
1041 JavaCalls::call_virtual(&result,
1042 loader,
1043 spec_klass,
1044 vmSymbols::toString_name(),
1045 vmSymbols::void_string_signature(),
1046 CHECK);
1047 assert(result.get_type() == T_OBJECT, "just checking");
1048 string = Handle(THREAD, (oop)result.get_jobject());
1049 }
1050
1051 ResourceMark rm;
1052 out->print("create class loader data " INTPTR_FORMAT, p2i(cld));
1053 out->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
1054 cld->loader_name());
1055
1056 if (string.not_null()) {
1057 out->print(": ");
1058 java_lang_String::print(string(), out);
1059 }
1060 out->cr();
1061 }
1062
1063
1064 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1065 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1066 cld->oops_do(f, must_claim);
1067 }
1068 }
1069
1070 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1071 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1072 if (cld->keep_alive()) {
1073 cld->oops_do(f, must_claim);
1074 }
1075 }
1076 }
1077
1078 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1079 if (ClassUnloading) {
1080 keep_alive_oops_do(f, must_claim);
1081 } else {
1082 oops_do(f, must_claim);
1083 }
1084 }
1085
1086 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1087 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1088 cl->do_cld(cld);
1089 }
1090 }
1091
1092 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1093 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1094 // Only walk the head until any clds not purged from prior unloading
1095 // (CMS doesn't purge right away).
1096 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1097 assert(cld->is_unloading(), "invariant");
1098 cl->do_cld(cld);
1099 }
1100 }
1101
1102 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1103 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1104 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1105 if (closure != NULL) {
1106 closure->do_cld(cld);
1107 }
1108 }
1109 }
1110
1111 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1112 roots_cld_do(cl, NULL);
1113 }
1114
1115 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1116 if (ClassUnloading) {
1117 keep_alive_cld_do(cl);
1118 } else {
1119 cld_do(cl);
1120 }
1121 }
1122
1123 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1124 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1125 cld->classes_do(klass_closure);
1126 }
1127 }
1128
1129 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1130 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1131 cld->classes_do(f);
1132 }
1133 }
1134
1135 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1136 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1137 cld->methods_do(f);
1138 }
1139 }
1140
1141 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1142 assert_locked_or_safepoint(Module_lock);
1143 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1144 cld->modules_do(f);
1145 }
1146 }
1147
1148 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1149 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1150 // Only walk the head until any clds not purged from prior unloading
1151 // (CMS doesn't purge right away).
1152 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1153 assert(cld->is_unloading(), "invariant");
1154 cld->modules_do(f);
1155 }
1156 }
1157
1158 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1159 assert_locked_or_safepoint(Module_lock);
1160 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1161 cld->packages_do(f);
1162 }
1163 }
1164
1165 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1166 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1167 // Only walk the head until any clds not purged from prior unloading
1168 // (CMS doesn't purge right away).
1169 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1170 assert(cld->is_unloading(), "invariant");
1171 cld->packages_do(f);
1172 }
1173 }
1174
1175 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1176 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1177 cld->loaded_classes_do(klass_closure);
1178 }
1179 }
1180
1181 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1182 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1183 // Only walk the head until any clds not purged from prior unloading
1184 // (CMS doesn't purge right away).
1185 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1186 assert(cld->is_unloading(), "invariant");
1187 cld->classes_do(f);
1188 }
1189 }
1190
1191 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1192 if (X->dictionary() != NULL)
1193
1194 // Walk classes in the loaded class dictionaries in various forms.
1195 // Only walks the classes defined in this class loader.
1196 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1197 FOR_ALL_DICTIONARY(cld) {
1198 cld->dictionary()->classes_do(f);
1199 }
1200 }
1201
1202 // Only walks the classes defined in this class loader.
1203 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1204 FOR_ALL_DICTIONARY(cld) {
1205 cld->dictionary()->classes_do(f, CHECK);
1206 }
1207 }
1208
1209 // Walks all entries in the dictionary including entries initiated by this class loader.
1210 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1211 FOR_ALL_DICTIONARY(cld) {
1212 cld->dictionary()->all_entries_do(f);
1213 }
1214 }
1215
1216 void ClassLoaderDataGraph::verify_dictionary() {
1217 FOR_ALL_DICTIONARY(cld) {
1218 cld->dictionary()->verify();
1219 }
1220 }
1221
1222 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1223 FOR_ALL_DICTIONARY(cld) {
1224 st->print("Dictionary for ");
1225 cld->print_value_on(st);
1226 st->cr();
1227 cld->dictionary()->print_on(st);
1228 st->cr();
1229 }
1230 }
1231
1232 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1233 FOR_ALL_DICTIONARY(cld) {
1234 ResourceMark rm;
1235 stringStream tempst;
1236 tempst.print("System Dictionary for %s", cld->loader_name());
1237 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1238 }
1239 }
1240
1241 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1242 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1243
1244 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1245
1246 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1247 ClassLoaderData* curr = _head;
1248 while (curr != _saved_head) {
1249 if (!curr->claimed()) {
1250 array->push(curr);
1251 LogTarget(Debug, class, loader, data) lt;
1252 if (lt.is_enabled()) {
1253 LogStream ls(lt);
1254 ls.print("found new CLD: ");
1255 curr->print_value_on(&ls);
1256 ls.cr();
1257 }
1258 }
1259
1260 curr = curr->_next;
1261 }
1262
1263 return array;
1264 }
1265
1266 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
1267 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
1268 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
1269 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
1270 return true;
1271 }
1272 }
1273 return false;
1274 }
1275
1276 #ifndef PRODUCT
1277 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1278 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1279 if (loader_data == data) {
1280 return true;
1281 }
1282 }
1283
1284 return false;
1285 }
1286 #endif // PRODUCT
1287
1288
1289 // Move class loader data from main list to the unloaded list for unloading
1290 // and deallocation later.
1291 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1292 bool clean_previous_versions) {
1293
1294 ClassLoaderData* data = _head;
1295 ClassLoaderData* prev = NULL;
1296 bool seen_dead_loader = false;
1297
1298 // Mark metadata seen on the stack only so we can delete unneeded entries.
1299 // Only walk all metadata, including the expensive code cache walk, for Full GC
1300 // and only if class redefinition and if there's previous versions of
1301 // Klasses to delete.
1302 bool walk_all_metadata = clean_previous_versions &&
1303 JvmtiExport::has_redefined_a_class() &&
1304 InstanceKlass::has_previous_versions_and_reset();
1305 MetadataOnStackMark md_on_stack(walk_all_metadata);
1306
1307 // Save previous _unloading pointer for CMS which may add to unloading list before
1308 // purging and we don't want to rewalk the previously unloaded class loader data.
1309 _saved_unloading = _unloading;
1310
1311 data = _head;
1312 while (data != NULL) {
1313 if (data->is_alive(is_alive_closure)) {
1314 // clean metaspace
1315 if (walk_all_metadata) {
1316 data->classes_do(InstanceKlass::purge_previous_versions);
1317 }
1318 data->free_deallocate_list();
1319 prev = data;
1320 data = data->next();
1321 continue;
1322 }
1323 seen_dead_loader = true;
1324 ClassLoaderData* dead = data;
1325 dead->unload();
1326 data = data->next();
1327 // Remove from loader list.
1328 // This class loader data will no longer be found
1329 // in the ClassLoaderDataGraph.
1330 if (prev != NULL) {
1331 prev->set_next(data);
1332 } else {
1333 assert(dead == _head, "sanity check");
1334 _head = data;
1335 }
1336 dead->set_next(_unloading);
1337 _unloading = dead;
1338 }
1339
1340 if (seen_dead_loader) {
1341 data = _head;
1342 while (data != NULL) {
1343 // Remove entries in the dictionary of live class loader that have
1344 // initiated loading classes in a dead class loader.
1345 if (data->dictionary() != NULL) {
1346 data->dictionary()->do_unloading(is_alive_closure);
1347 }
1348 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1349 // lists to determine if there are modules on those lists that are now
1350 // dead and should be removed. A module's life cycle is equivalent
1351 // to its defining class loader's life cycle. Since a module is
1352 // considered dead if its class loader is dead, these walks must
1353 // occur after each class loader's aliveness is determined.
1354 if (data->packages() != NULL) {
1355 data->packages()->purge_all_package_exports();
1356 }
1357 if (data->modules_defined()) {
1358 data->modules()->purge_all_module_reads();
1359 }
1360 data = data->next();
1361 }
1362
1363 post_class_unload_events();
1364 }
1365
1366 return seen_dead_loader;
1367 }
1368
1369 void ClassLoaderDataGraph::purge() {
1370 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1371 ClassLoaderData* list = _unloading;
1372 _unloading = NULL;
1373 ClassLoaderData* next = list;
1374 bool classes_unloaded = false;
1375 while (next != NULL) {
1376 ClassLoaderData* purge_me = next;
1377 next = purge_me->next();
1378 delete purge_me;
1379 classes_unloaded = true;
1380 }
1381 if (classes_unloaded) {
1382 Metaspace::purge();
1383 set_metaspace_oom(false);
1384 }
1385 }
1386
1387 int ClassLoaderDataGraph::resize_if_needed() {
1388 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1389 int resized = 0;
1390 if (Dictionary::does_any_dictionary_needs_resizing()) {
1391 FOR_ALL_DICTIONARY(cld) {
1392 if (cld->dictionary()->resize_if_needed()) {
1393 resized++;
1394 }
1395 }
1396 }
1397 return resized;
1398 }
1399
1400 void ClassLoaderDataGraph::post_class_unload_events() {
1401 #if INCLUDE_TRACE
1402 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1403 if (Tracing::enabled()) {
1404 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1405 assert(_unloading != NULL, "need class loader data unload list!");
1406 _class_unload_time = Ticks::now();
1407 classes_unloading_do(&class_unload_event);
1408 }
1409 Tracing::on_unloading_classes();
1410 }
1411 #endif
1412 }
1413
1414 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1415 : _next_klass(NULL) {
1416 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1417 Klass* klass = NULL;
1418
1419 // Find the first klass in the CLDG.
1420 while (cld != NULL) {
1421 assert_locked_or_safepoint(cld->metaspace_lock());
1422 klass = cld->_klasses;
1423 if (klass != NULL) {
1424 _next_klass = klass;
1425 return;
1426 }
1427 cld = cld->next();
1428 }
1429 }
1430
1431 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1432 Klass* next = klass->next_link();
1433 if (next != NULL) {
1434 return next;
1435 }
1436
1437 // No more klasses in the current CLD. Time to find a new CLD.
1438 ClassLoaderData* cld = klass->class_loader_data();
1439 assert_locked_or_safepoint(cld->metaspace_lock());
1440 while (next == NULL) {
1441 cld = cld->next();
1442 if (cld == NULL) {
1443 break;
1444 }
1445 next = cld->_klasses;
1446 }
1447
1448 return next;
1449 }
1450
1451 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1452 Klass* head = _next_klass;
1453
1454 while (head != NULL) {
1455 Klass* next = next_klass_in_cldg(head);
1456
1457 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1458
1459 if (old_head == head) {
1460 return head; // Won the CAS.
1461 }
1462
1463 head = old_head;
1464 }
1465
1466 // Nothing more for the iterator to hand out.
1467 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1468 return NULL;
1469 }
1470
1471 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1472 _data = ClassLoaderDataGraph::_head;
1473 }
1474
1475 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1476
1477 #ifndef PRODUCT
1478 // callable from debugger
1479 extern "C" int print_loader_data_graph() {
1480 ClassLoaderDataGraph::dump_on(tty);
1481 return 0;
1482 }
1483
1484 void ClassLoaderDataGraph::verify() {
1485 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1486 data->verify();
1487 }
1488 }
1489
1490 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1491 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1492 data->dump(out);
1493 }
1494 MetaspaceAux::dump(out);
1495 }
1496 #endif // PRODUCT
1497
1498 void ClassLoaderData::print_value_on(outputStream* out) const {
1499 if (class_loader() == NULL) {
1500 out->print("NULL class loader");
1501 } else {
1502 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1503 class_loader()->print_value_on(out);
1504 }
1505 }
1506
1507 void ClassLoaderData::print_on(outputStream* out) const {
1508 if (class_loader() == NULL) {
1509 out->print("NULL class loader");
1510 } else {
1511 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1512 class_loader()->print_on(out);
1513 }
1514 }
1515
1516 #if INCLUDE_TRACE
1517
1518 Ticks ClassLoaderDataGraph::_class_unload_time;
1519
1520 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1521 assert(k != NULL, "invariant");
1522
1523 // post class unload event
1524 EventClassUnload event(UNTIMED);
1525 event.set_endtime(_class_unload_time);
1526 event.set_unloadedClass(k);
1527 event.set_definingClassLoader(k->class_loader_data());
1528 event.commit();
1529 }
1530
1531 #endif // INCLUDE_TRACE