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/allocation.inline.hpp"
63 #include "memory/metadataFactory.hpp"
64 #include "memory/metaspaceShared.hpp"
65 #include "memory/oopFactory.hpp"
66 #include "memory/resourceArea.hpp"
67 #include "oops/access.inline.hpp"
68 #include "oops/objArrayOop.inline.hpp"
69 #include "oops/oop.inline.hpp"
70 #include "runtime/atomic.hpp"
71 #include "runtime/handles.inline.hpp"
72 #include "runtime/javaCalls.hpp"
73 #include "runtime/jniHandles.hpp"
74 #include "runtime/mutex.hpp"
75 #include "runtime/orderAccess.hpp"
76 #include "runtime/safepoint.hpp"
77 #include "runtime/synchronizer.hpp"
78 #include "utilities/growableArray.hpp"
79 #include "utilities/macros.hpp"
80 #include "utilities/ostream.hpp"
81 #if INCLUDE_TRACE
82 #include "trace/tracing.hpp"
83 #endif
84
85 volatile size_t ClassLoaderDataGraph::_num_array_classes = 0;
86 volatile size_t ClassLoaderDataGraph::_num_instance_classes = 0;
87
88 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
89
90 void ClassLoaderData::init_null_class_loader_data() {
91 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
92 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
93
94 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
95 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
96 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
97
98 LogTarget(Debug, class, loader, data) lt;
99 if (lt.is_enabled()) {
100 ResourceMark rm;
101 LogStream ls(lt);
102 ls.print("create ");
103 _the_null_class_loader_data->print_value_on(&ls);
104 ls.cr();
105 }
106 }
107
108 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous) :
109 _class_loader(h_class_loader()),
110 _is_anonymous(is_anonymous),
111 // An anonymous class loader data doesn't have anything to keep
112 // it from being unloaded during parsing of the anonymous class.
113 // The null-class-loader should always be kept alive.
114 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
115 _metaspace(NULL), _unloading(false), _klasses(NULL),
116 _modules(NULL), _packages(NULL),
117 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false),
118 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
119 _next(NULL),
120 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
121 Monitor::_safepoint_check_never)) {
122
123 // A ClassLoaderData created solely for an anonymous class should never have a
124 // ModuleEntryTable or PackageEntryTable created for it. The defining package
125 // and module for an anonymous class will be found in its host class.
126 if (!is_anonymous) {
127 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
128 if (h_class_loader.is_null()) {
129 // Create unnamed module for boot loader
130 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
131 } else {
132 // Create unnamed module for all other loaders
133 _unnamed_module = ModuleEntry::create_unnamed_module(this);
134 }
135 _dictionary = create_dictionary();
136 } else {
137 _packages = NULL;
138 _unnamed_module = NULL;
139 _dictionary = NULL;
140 }
141
142 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
143
144 TRACE_INIT_ID(this);
145 }
146
147 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
148 Chunk* c = _head;
149 while (c != NULL) {
150 Chunk* next = c->_next;
151 delete c;
152 c = next;
153 }
154 }
155
156 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
157 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
158 Chunk* next = new Chunk(_head);
159 OrderAccess::release_store(&_head, next);
160 }
161 oop* handle = &_head->_data[_head->_size];
162 *handle = o;
163 OrderAccess::release_store(&_head->_size, _head->_size + 1);
164 return handle;
165 }
166
167 int ClassLoaderData::ChunkedHandleList::count() const {
168 int count = 0;
169 Chunk* chunk = _head;
170 while (chunk != NULL) {
171 count += chunk->_size;
172 chunk = chunk->_next;
173 }
174 return count;
175 }
176
177 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
178 for (juint i = 0; i < size; i++) {
179 if (c->_data[i] != NULL) {
180 f->do_oop(&c->_data[i]);
181 }
182 }
183 }
184
185 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
186 Chunk* head = OrderAccess::load_acquire(&_head);
187 if (head != NULL) {
188 // Must be careful when reading size of head
189 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
190 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
191 oops_do_chunk(f, c, c->_size);
192 }
193 }
194 }
195
196 class VerifyContainsOopClosure : public OopClosure {
197 oop _target;
198 bool _found;
199
200 public:
201 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
202
203 void do_oop(oop* p) {
204 if (p != NULL && *p == _target) {
205 _found = true;
206 }
207 }
208
209 void do_oop(narrowOop* p) {
210 // The ChunkedHandleList should not contain any narrowOop
211 ShouldNotReachHere();
212 }
213
214 bool found() const {
215 return _found;
216 }
217 };
218
219 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
220 VerifyContainsOopClosure cl(p);
221 oops_do(&cl);
222 return cl.found();
223 }
224
225 #ifndef PRODUCT
226 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
227 Chunk* chunk = _head;
228 while (chunk != NULL) {
229 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
230 return true;
231 }
232 chunk = chunk->_next;
233 }
234 return false;
235 }
236 #endif // PRODUCT
237
238 bool ClassLoaderData::claim() {
239 if (_claimed == 1) {
240 return false;
241 }
242
243 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
244 }
245
246 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
247 // while the class is being parsed, and if the class appears on the module fixup list.
248 // Due to the uniqueness that no other class shares the anonymous class' name or
249 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
250 // it is being defined, therefore _keep_alive is not volatile or atomic.
251 void ClassLoaderData::inc_keep_alive() {
252 if (is_anonymous()) {
253 assert(_keep_alive >= 0, "Invalid keep alive increment count");
254 _keep_alive++;
255 }
256 }
257
258 void ClassLoaderData::dec_keep_alive() {
259 if (is_anonymous()) {
260 assert(_keep_alive > 0, "Invalid keep alive decrement count");
261 _keep_alive--;
262 }
263 }
264
265 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
266 if (must_claim && !claim()) {
267 return;
268 }
269
270 // Only clear modified_oops after the ClassLoaderData is claimed.
271 if (clear_mod_oops) {
272 clear_modified_oops();
273 }
274
275 f->do_oop(&_class_loader);
276 _handles.oops_do(f);
277 }
278
279 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
280 // Lock-free access requires load_acquire
281 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
282 klass_closure->do_klass(k);
283 assert(k != k->next_link(), "no loops!");
284 }
285 }
286
287 void ClassLoaderData::classes_do(void f(Klass * const)) {
288 // Lock-free access requires load_acquire
289 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
290 f(k);
291 assert(k != k->next_link(), "no loops!");
292 }
293 }
294
295 void ClassLoaderData::methods_do(void f(Method*)) {
296 // Lock-free access requires load_acquire
297 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
298 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
299 InstanceKlass::cast(k)->methods_do(f);
300 }
301 }
302 }
303
304 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
305 // Lock-free access requires load_acquire
306 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
307 // Do not filter ArrayKlass oops here...
308 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
309 klass_closure->do_klass(k);
310 }
311 }
312 }
313
314 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
315 // Lock-free access requires load_acquire
316 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
317 if (k->is_instance_klass()) {
318 f(InstanceKlass::cast(k));
319 }
320 assert(k != k->next_link(), "no loops!");
321 }
322 }
323
324 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
325 assert_locked_or_safepoint(Module_lock);
326 if (_unnamed_module != NULL) {
327 f(_unnamed_module);
328 }
329 if (_modules != NULL) {
330 for (int i = 0; i < _modules->table_size(); i++) {
331 for (ModuleEntry* entry = _modules->bucket(i);
332 entry != NULL;
333 entry = entry->next()) {
334 f(entry);
335 }
336 }
337 }
338 }
339
340 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
341 assert_locked_or_safepoint(Module_lock);
342 if (_packages != NULL) {
343 for (int i = 0; i < _packages->table_size(); i++) {
344 for (PackageEntry* entry = _packages->bucket(i);
345 entry != NULL;
346 entry = entry->next()) {
347 f(entry);
348 }
349 }
350 }
351 }
352
353 void ClassLoaderData::record_dependency(const Klass* k) {
354 assert(k != NULL, "invariant");
355
356 ClassLoaderData * const from_cld = this;
357 ClassLoaderData * const to_cld = k->class_loader_data();
358
359 // Do not need to record dependency if the dependency is to a class whose
360 // class loader data is never freed. (i.e. the dependency's class loader
361 // is one of the three builtin class loaders and the dependency is not
362 // anonymous.)
363 if (to_cld->is_permanent_class_loader_data()) {
364 return;
365 }
366
367 oop to;
368 if (to_cld->is_anonymous()) {
369 // Just return if an anonymous class is attempting to record a dependency
370 // to itself. (Note that every anonymous class has its own unique class
371 // loader data.)
372 if (to_cld == from_cld) {
373 return;
374 }
375 // Anonymous class dependencies are through the mirror.
376 to = k->java_mirror();
377 } else {
378 to = to_cld->class_loader();
379 oop from = from_cld->class_loader();
380
381 // Just return if this dependency is to a class with the same or a parent
382 // class_loader.
383 if (from == to || java_lang_ClassLoader::isAncestor(from, to)) {
384 return; // this class loader is in the parent list, no need to add it.
385 }
386 }
387
388 // It's a dependency we won't find through GC, add it.
389 if (!_handles.contains(to)) {
390 NOT_PRODUCT(Atomic::inc(&_dependency_count));
391 LogTarget(Trace, class, loader, data) lt;
392 if (lt.is_enabled()) {
393 ResourceMark rm;
394 LogStream ls(lt);
395 ls.print("adding dependency from ");
396 print_value_on(&ls);
397 ls.print(" to ");
398 to_cld->print_value_on(&ls);
399 ls.cr();
400 }
401 Handle dependency(Thread::current(), to);
402 add_handle(dependency);
403 // Added a potentially young gen oop to the ClassLoaderData
404 record_modified_oops();
405 }
406 }
407
408
409 void ClassLoaderDataGraph::clear_claimed_marks() {
410 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
411 cld->clear_claimed();
412 }
413 }
414
415 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
416 {
417 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
418 Klass* old_value = _klasses;
419 k->set_next_link(old_value);
420 // Link the new item into the list, making sure the linked class is stable
421 // since the list can be walked without a lock
422 OrderAccess::release_store(&_klasses, k);
423 if (k->is_array_klass()) {
424 ClassLoaderDataGraph::inc_array_classes(1);
425 } else {
426 ClassLoaderDataGraph::inc_instance_classes(1);
427 }
428 }
429
430 if (publicize) {
431 LogTarget(Trace, class, loader, data) lt;
432 if (lt.is_enabled()) {
433 ResourceMark rm;
434 LogStream ls(lt);
435 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
436 print_value_on(&ls);
437 ls.cr();
438 }
439 }
440 }
441
442 // Class iterator used by the compiler. It gets some number of classes at
443 // a safepoint to decay invocation counters on the methods.
444 class ClassLoaderDataGraphKlassIteratorStatic {
445 ClassLoaderData* _current_loader_data;
446 Klass* _current_class_entry;
447 public:
448
449 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
450
451 InstanceKlass* try_get_next_class() {
452 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
453 size_t max_classes = ClassLoaderDataGraph::num_instance_classes();
454 assert(max_classes > 0, "should not be called with no instance classes");
455 for (size_t i = 0; i < max_classes; ) {
456
457 if (_current_class_entry != NULL) {
458 Klass* k = _current_class_entry;
459 _current_class_entry = _current_class_entry->next_link();
460
461 if (k->is_instance_klass()) {
462 InstanceKlass* ik = InstanceKlass::cast(k);
463 i++; // count all instance classes found
464 // Not yet loaded classes are counted in max_classes
465 // but only return loaded classes.
466 if (ik->is_loaded()) {
467 return ik;
468 }
469 }
470 } else {
471 // Go to next CLD
472 if (_current_loader_data != NULL) {
473 _current_loader_data = _current_loader_data->next();
474 }
475 // Start at the beginning
476 if (_current_loader_data == NULL) {
477 _current_loader_data = ClassLoaderDataGraph::_head;
478 }
479
480 _current_class_entry = _current_loader_data->klasses();
481 }
482 }
483 // Should never be reached unless all instance classes have failed or are not fully loaded.
484 // Caller handles NULL.
485 return NULL;
486 }
487
488 // If the current class for the static iterator is a class being unloaded or
489 // deallocated, adjust the current class.
490 void adjust_saved_class(ClassLoaderData* cld) {
491 if (_current_loader_data == cld) {
492 _current_loader_data = cld->next();
493 if (_current_loader_data != NULL) {
494 _current_class_entry = _current_loader_data->klasses();
495 } // else try_get_next_class will start at the head
496 }
497 }
498
499 void adjust_saved_class(Klass* klass) {
500 if (_current_class_entry == klass) {
501 _current_class_entry = klass->next_link();
502 }
503 }
504 };
505
506 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
507
508 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
509 return static_klass_iterator.try_get_next_class();
510 }
511
512
513 // Remove a klass from the _klasses list for scratch_class during redefinition
514 // or parsed class in the case of an error.
515 void ClassLoaderData::remove_class(Klass* scratch_class) {
516 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
517
518 // Adjust global class iterator.
519 static_klass_iterator.adjust_saved_class(scratch_class);
520
521 Klass* prev = NULL;
522 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
523 if (k == scratch_class) {
524 if (prev == NULL) {
525 _klasses = k->next_link();
526 } else {
527 Klass* next = k->next_link();
528 prev->set_next_link(next);
529 }
530
531 if (k->is_array_klass()) {
532 ClassLoaderDataGraph::dec_array_classes(1);
533 } else {
534 ClassLoaderDataGraph::dec_instance_classes(1);
535 }
536
537 return;
538 }
539 prev = k;
540 assert(k != k->next_link(), "no loops!");
541 }
542 ShouldNotReachHere(); // should have found this class!!
543 }
544
545 void ClassLoaderData::unload() {
546 _unloading = true;
547
548 // Tell serviceability tools these classes are unloading
549 classes_do(InstanceKlass::notify_unload_class);
550
551 LogTarget(Debug, class, loader, data) lt;
552 if (lt.is_enabled()) {
553 ResourceMark rm;
554 LogStream ls(lt);
555 ls.print("unload ");
556 print_value_on(&ls);
557 ls.cr();
558 }
559
560 // Some items on the _deallocate_list need to free their C heap structures
561 // if they are not already on the _klasses list.
562 unload_deallocate_list();
563
564 // Clean up global class iterator for compiler
565 static_klass_iterator.adjust_saved_class(this);
566 }
567
568 ModuleEntryTable* ClassLoaderData::modules() {
569 // Lazily create the module entry table at first request.
570 // Lock-free access requires load_acquire.
571 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
572 if (modules == NULL) {
573 MutexLocker m1(Module_lock);
574 // Check if _modules got allocated while we were waiting for this lock.
575 if ((modules = _modules) == NULL) {
576 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
577
578 {
579 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
580 // Ensure _modules is stable, since it is examined without a lock
581 OrderAccess::release_store(&_modules, modules);
582 }
583 }
584 }
585 return modules;
586 }
587
588 const int _boot_loader_dictionary_size = 1009;
589 const int _default_loader_dictionary_size = 107;
590
591 Dictionary* ClassLoaderData::create_dictionary() {
592 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
593 int size;
594 bool resizable = false;
595 if (_the_null_class_loader_data == NULL) {
596 size = _boot_loader_dictionary_size;
597 resizable = true;
598 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
599 size = 1; // there's only one class in relection class loader and no initiated classes
600 } else if (is_system_class_loader_data()) {
601 size = _boot_loader_dictionary_size;
602 resizable = true;
603 } else {
604 size = _default_loader_dictionary_size;
605 resizable = true;
606 }
607 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) {
608 resizable = false;
609 }
610 return new Dictionary(this, size, resizable);
611 }
612
613 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
614 oop ClassLoaderData::ensure_loader_alive() {
615 // A klass that was previously considered dead can be looked up in the
616 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
617 // or a reachable object making it alive again. The SATB part of G1 needs
618 // to get notified about this potential resurrection, otherwise the marking
619 // might not find the object.
620 if (!keep_alive()) {
621 oop* o = is_anonymous() ? _klasses->java_mirror_handle().ptr_raw() : &_class_loader;
622 return RootAccess<ON_PHANTOM_OOP_REF>::oop_load(o);
623 } else {
624 return NULL;
625 }
626 }
627
628 // Unloading support
629 oop ClassLoaderData::keep_alive_object() const {
630 assert_locked_or_safepoint(_metaspace_lock);
631 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
632 return is_anonymous() ? _klasses->java_mirror() : class_loader();
633 }
634
635 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
636 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
637 || is_alive_closure->do_object_b(keep_alive_object());
638
639 return alive;
640 }
641
642 class ReleaseKlassClosure: public KlassClosure {
643 private:
644 size_t _instance_class_released;
645 size_t _array_class_released;
646 public:
647 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
648
649 size_t instance_class_released() const { return _instance_class_released; }
650 size_t array_class_released() const { return _array_class_released; }
651
652 void do_klass(Klass* k) {
653 if (k->is_array_klass()) {
654 _array_class_released ++;
655 } else {
656 assert(k->is_instance_klass(), "Must be");
657 _instance_class_released ++;
658 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
659 }
660 }
661 };
662
663 ClassLoaderData::~ClassLoaderData() {
664 // Release C heap structures for all the classes.
665 ReleaseKlassClosure cl;
666 classes_do(&cl);
667
668 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
669 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
670
671 // Release C heap allocated hashtable for all the packages.
672 if (_packages != NULL) {
673 // Destroy the table itself
674 delete _packages;
675 _packages = NULL;
676 }
677
678 // Release C heap allocated hashtable for all the modules.
679 if (_modules != NULL) {
680 // Destroy the table itself
681 delete _modules;
682 _modules = NULL;
683 }
684
685 // Release C heap allocated hashtable for the dictionary
686 if (_dictionary != NULL) {
687 // Destroy the table itself
688 delete _dictionary;
689 _dictionary = NULL;
690 }
691
692 if (_unnamed_module != NULL) {
693 _unnamed_module->delete_unnamed_module();
694 _unnamed_module = NULL;
695 }
696
697 // release the metaspace
698 ClassLoaderMetaspace *m = _metaspace;
699 if (m != NULL) {
700 _metaspace = NULL;
701 delete m;
702 }
703 // Clear all the JNI handles for methods
704 // These aren't deallocated and are going to look like a leak, but that's
705 // needed because we can't really get rid of jmethodIDs because we don't
706 // know when native code is going to stop using them. The spec says that
707 // they're "invalid" but existing programs likely rely on their being
708 // NULL after class unloading.
709 if (_jmethod_ids != NULL) {
710 Method::clear_jmethod_ids(this);
711 }
712 // Delete lock
713 delete _metaspace_lock;
714
715 // Delete free list
716 if (_deallocate_list != NULL) {
717 delete _deallocate_list;
718 }
719 }
720
721 // Returns true if this class loader data is for the app class loader
722 // or a user defined system class loader. (Note that the class loader
723 // data may be anonymous.)
724 bool ClassLoaderData::is_system_class_loader_data() const {
725 return SystemDictionary::is_system_class_loader(class_loader());
726 }
727
728 // Returns true if this class loader data is for the platform class loader.
729 // (Note that the class loader data may be anonymous.)
730 bool ClassLoaderData::is_platform_class_loader_data() const {
731 return SystemDictionary::is_platform_class_loader(class_loader());
732 }
733
734 // Returns true if the class loader for this class loader data is one of
735 // the 3 builtin (boot application/system or platform) class loaders,
736 // including a user-defined system class loader. Note that if the class
737 // loader data is for an anonymous class then it may get freed by a GC
738 // even if its class loader is one of these loaders.
739 bool ClassLoaderData::is_builtin_class_loader_data() const {
740 return (is_boot_class_loader_data() ||
741 SystemDictionary::is_system_class_loader(class_loader()) ||
742 SystemDictionary::is_platform_class_loader(class_loader()));
743 }
744
745 // Returns true if this class loader data is a class loader data
746 // that is not ever freed by a GC. It must be one of the builtin
747 // class loaders and not anonymous.
748 bool ClassLoaderData::is_permanent_class_loader_data() const {
749 return is_builtin_class_loader_data() && !is_anonymous();
750 }
751
752 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
753 // If the metaspace has not been allocated, create a new one. Might want
754 // to create smaller arena for Reflection class loaders also.
755 // The reason for the delayed allocation is because some class loaders are
756 // simply for delegating with no metadata of their own.
757 // Lock-free access requires load_acquire.
758 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
759 if (metaspace == NULL) {
760 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
761 // Check if _metaspace got allocated while we were waiting for this lock.
762 if ((metaspace = _metaspace) == NULL) {
763 if (this == the_null_class_loader_data()) {
764 assert (class_loader() == NULL, "Must be");
765 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
766 } else if (is_anonymous()) {
767 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
768 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
769 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
770 } else {
771 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
772 }
773 // Ensure _metaspace is stable, since it is examined without a lock
774 OrderAccess::release_store(&_metaspace, metaspace);
775 }
776 }
777 return metaspace;
778 }
779
780 OopHandle ClassLoaderData::add_handle(Handle h) {
781 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
782 record_modified_oops();
783 return OopHandle(_handles.add(h()));
784 }
785
786 void ClassLoaderData::remove_handle(OopHandle h) {
787 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
788 oop* ptr = h.ptr_raw();
789 if (ptr != NULL) {
790 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
791 // This root is not walked in safepoints, and hence requires an appropriate
792 // decorator that e.g. maintains the SATB invariant in SATB collectors.
793 RootAccess<IN_CONCURRENT_ROOT>::oop_store(ptr, oop(NULL));
794 }
795 }
796
797 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
798 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
799 if (dest.resolve() != NULL) {
800 return;
801 } else {
802 dest = _handles.add(h());
803 }
804 }
805
806 // Add this metadata pointer to be freed when it's safe. This is only during
807 // class unloading because Handles might point to this metadata field.
808 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
809 // Metadata in shared region isn't deleted.
810 if (!m->is_shared()) {
811 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
812 if (_deallocate_list == NULL) {
813 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
814 }
815 _deallocate_list->append_if_missing(m);
816 }
817 }
818
819 // Deallocate free metadata on the free list. How useful the PermGen was!
820 void ClassLoaderData::free_deallocate_list() {
821 // Don't need lock, at safepoint
822 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
823 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
824 if (_deallocate_list == NULL) {
825 return;
826 }
827 // Go backwards because this removes entries that are freed.
828 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
829 Metadata* m = _deallocate_list->at(i);
830 if (!m->on_stack()) {
831 _deallocate_list->remove_at(i);
832 // There are only three types of metadata that we deallocate directly.
833 // Cast them so they can be used by the template function.
834 if (m->is_method()) {
835 MetadataFactory::free_metadata(this, (Method*)m);
836 } else if (m->is_constantPool()) {
837 MetadataFactory::free_metadata(this, (ConstantPool*)m);
838 } else if (m->is_klass()) {
839 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
840 } else {
841 ShouldNotReachHere();
842 }
843 } else {
844 // Metadata is alive.
845 // If scratch_class is on stack then it shouldn't be on this list!
846 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
847 "scratch classes on this list should be dead");
848 // Also should assert that other metadata on the list was found in handles.
849 }
850 }
851 }
852
853 // This is distinct from free_deallocate_list. For class loader data that are
854 // unloading, this frees the C heap memory for items on the list, and unlinks
855 // scratch or error classes so that unloading events aren't triggered for these
856 // classes. The metadata is removed with the unloading metaspace.
857 // There isn't C heap memory allocated for methods, so nothing is done for them.
858 void ClassLoaderData::unload_deallocate_list() {
859 // Don't need lock, at safepoint
860 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
861 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
862 if (_deallocate_list == NULL) {
863 return;
864 }
865 // Go backwards because this removes entries that are freed.
866 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
867 Metadata* m = _deallocate_list->at(i);
868 assert (!m->on_stack(), "wouldn't be unloading if this were so");
869 _deallocate_list->remove_at(i);
870 if (m->is_constantPool()) {
871 ((ConstantPool*)m)->release_C_heap_structures();
872 } else if (m->is_klass()) {
873 InstanceKlass* ik = (InstanceKlass*)m;
874 // also releases ik->constants() C heap memory
875 InstanceKlass::release_C_heap_structures(ik);
876 // Remove the class so unloading events aren't triggered for
877 // this class (scratch or error class) in do_unloading().
878 remove_class(ik);
879 }
880 }
881 }
882
883 // These anonymous class loaders are to contain classes used for JSR292
884 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(Handle loader) {
885 // Add a new class loader data to the graph.
886 return ClassLoaderDataGraph::add(loader, true);
887 }
888
889 const char* ClassLoaderData::loader_name() const {
890 // Handles null class loader
891 return SystemDictionary::loader_name(class_loader());
892 }
893
894
895 void ClassLoaderData::print_value_on(outputStream* out) const {
896 if (class_loader() != NULL) {
897 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
898 class_loader()->print_value_on(out); // includes loader_name() and address of class loader instance
899 } else {
900 // loader data: 0xsomeaddr of <bootloader>
901 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name());
902 }
903 if (is_anonymous()) {
904 out->print(" anonymous");
905 }
906 }
907
908 #ifndef PRODUCT
909 void ClassLoaderData::print_on(outputStream* out) const {
910 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
911 p2i(this), p2i((void *)class_loader()), loader_name());
912 if (is_anonymous()) out->print(" anonymous");
913 if (claimed()) out->print(" claimed");
914 if (is_unloading()) out->print(" unloading");
915 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
916
917 if (_jmethod_ids != NULL) {
918 Method::print_jmethod_ids(this, out);
919 }
920 out->print(" handles count %d", _handles.count());
921 out->print(" dependencies %d", _dependency_count);
922 out->print_cr("}");
923 }
924 #endif // PRODUCT
925
926 void ClassLoaderData::verify() {
927 assert_locked_or_safepoint(_metaspace_lock);
928 oop cl = class_loader();
929
930 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
931 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
932
933 // Verify the integrity of the allocated space.
934 if (metaspace_or_null() != NULL) {
935 metaspace_or_null()->verify();
936 }
937
938 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
939 guarantee(k->class_loader_data() == this, "Must be the same");
940 k->verify();
941 assert(k != k->next_link(), "no loops!");
942 }
943 }
944
945 bool ClassLoaderData::contains_klass(Klass* klass) {
946 // Lock-free access requires load_acquire
947 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
948 if (k == klass) return true;
949 }
950 return false;
951 }
952
953
954 // GC root of class loader data created.
955 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
956 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
957 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
958 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
959
960 bool ClassLoaderDataGraph::_should_purge = false;
961 bool ClassLoaderDataGraph::_metaspace_oom = false;
962
963 // Add a new class loader data node to the list. Assign the newly created
964 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
965 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous) {
966 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
967 // ClassLoaderData in the graph since the CLD
968 // contains unhandled oops
969
970 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous);
971
972
973 if (!is_anonymous) {
974 // First, Atomically set it
975 ClassLoaderData* old = java_lang_ClassLoader::cmpxchg_loader_data(cld, loader(), NULL);
976 if (old != NULL) {
977 delete cld;
978 // Returns the data.
979 return old;
980 }
981 }
982
983 // We won the race, and therefore the task of adding the data to the list of
984 // class loader data
985 ClassLoaderData** list_head = &_head;
986 ClassLoaderData* next = _head;
987
988 do {
989 cld->set_next(next);
990 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next);
991 if (exchanged == next) {
992 LogTarget(Debug, class, loader, data) lt;
993 if (lt.is_enabled()) {
994 ResourceMark rm;
995 LogStream ls(lt);
996 ls.print("create ");
997 cld->print_value_on(&ls);
998 ls.cr();
999 }
1000 return cld;
1001 }
1002 next = exchanged;
1003 } while (true);
1004 }
1005
1006 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1007 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1008 cld->oops_do(f, must_claim);
1009 }
1010 }
1011
1012 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1013 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1014 if (cld->keep_alive()) {
1015 cld->oops_do(f, must_claim);
1016 }
1017 }
1018 }
1019
1020 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1021 if (ClassUnloading) {
1022 keep_alive_oops_do(f, must_claim);
1023 } else {
1024 oops_do(f, must_claim);
1025 }
1026 }
1027
1028 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1029 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1030 cl->do_cld(cld);
1031 }
1032 }
1033
1034 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1035 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1036 // Only walk the head until any clds not purged from prior unloading
1037 // (CMS doesn't purge right away).
1038 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1039 assert(cld->is_unloading(), "invariant");
1040 cl->do_cld(cld);
1041 }
1042 }
1043
1044 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1045 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1046 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1047 if (closure != NULL) {
1048 closure->do_cld(cld);
1049 }
1050 }
1051 }
1052
1053 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1054 roots_cld_do(cl, NULL);
1055 }
1056
1057 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1058 if (ClassUnloading) {
1059 keep_alive_cld_do(cl);
1060 } else {
1061 cld_do(cl);
1062 }
1063 }
1064
1065 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1066 Thread* thread = Thread::current();
1067 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1068 Handle holder(thread, cld->ensure_loader_alive());
1069 cld->classes_do(klass_closure);
1070 }
1071 }
1072
1073 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1074 Thread* thread = Thread::current();
1075 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1076 Handle holder(thread, cld->ensure_loader_alive());
1077 cld->classes_do(f);
1078 }
1079 }
1080
1081 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1082 Thread* thread = Thread::current();
1083 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1084 Handle holder(thread, cld->ensure_loader_alive());
1085 cld->methods_do(f);
1086 }
1087 }
1088
1089 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1090 assert_locked_or_safepoint(Module_lock);
1091 Thread* thread = Thread::current();
1092 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1093 Handle holder(thread, cld->ensure_loader_alive());
1094 cld->modules_do(f);
1095 }
1096 }
1097
1098 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1099 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1100 // Only walk the head until any clds not purged from prior unloading
1101 // (CMS doesn't purge right away).
1102 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1103 assert(cld->is_unloading(), "invariant");
1104 cld->modules_do(f);
1105 }
1106 }
1107
1108 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1109 assert_locked_or_safepoint(Module_lock);
1110 Thread* thread = Thread::current();
1111 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1112 Handle holder(thread, cld->ensure_loader_alive());
1113 cld->packages_do(f);
1114 }
1115 }
1116
1117 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1118 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1119 // Only walk the head until any clds not purged from prior unloading
1120 // (CMS doesn't purge right away).
1121 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1122 assert(cld->is_unloading(), "invariant");
1123 cld->packages_do(f);
1124 }
1125 }
1126
1127 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1128 Thread* thread = Thread::current();
1129 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1130 Handle holder(thread, cld->ensure_loader_alive());
1131 cld->loaded_classes_do(klass_closure);
1132 }
1133 }
1134
1135 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1136 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1137 // Only walk the head until any clds not purged from prior unloading
1138 // (CMS doesn't purge right away).
1139 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1140 assert(cld->is_unloading(), "invariant");
1141 cld->classes_do(f);
1142 }
1143 }
1144
1145 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1146 if (X->dictionary() != NULL)
1147
1148 // Walk classes in the loaded class dictionaries in various forms.
1149 // Only walks the classes defined in this class loader.
1150 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1151 Thread* thread = Thread::current();
1152 FOR_ALL_DICTIONARY(cld) {
1153 Handle holder(thread, cld->ensure_loader_alive());
1154 cld->dictionary()->classes_do(f);
1155 }
1156 }
1157
1158 // Only walks the classes defined in this class loader.
1159 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1160 Thread* thread = Thread::current();
1161 FOR_ALL_DICTIONARY(cld) {
1162 Handle holder(thread, cld->ensure_loader_alive());
1163 cld->dictionary()->classes_do(f, CHECK);
1164 }
1165 }
1166
1167 // Walks all entries in the dictionary including entries initiated by this class loader.
1168 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1169 Thread* thread = Thread::current();
1170 FOR_ALL_DICTIONARY(cld) {
1171 Handle holder(thread, cld->ensure_loader_alive());
1172 cld->dictionary()->all_entries_do(f);
1173 }
1174 }
1175
1176 void ClassLoaderDataGraph::verify_dictionary() {
1177 FOR_ALL_DICTIONARY(cld) {
1178 cld->dictionary()->verify();
1179 }
1180 }
1181
1182 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1183 FOR_ALL_DICTIONARY(cld) {
1184 st->print("Dictionary for ");
1185 cld->print_value_on(st);
1186 st->cr();
1187 cld->dictionary()->print_on(st);
1188 st->cr();
1189 }
1190 }
1191
1192 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1193 FOR_ALL_DICTIONARY(cld) {
1194 ResourceMark rm;
1195 stringStream tempst;
1196 tempst.print("System Dictionary for %s", cld->loader_name());
1197 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1198 }
1199 }
1200
1201 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1202 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1203
1204 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1205
1206 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1207 ClassLoaderData* curr = _head;
1208 while (curr != _saved_head) {
1209 if (!curr->claimed()) {
1210 array->push(curr);
1211 LogTarget(Debug, class, loader, data) lt;
1212 if (lt.is_enabled()) {
1213 LogStream ls(lt);
1214 ls.print("found new CLD: ");
1215 curr->print_value_on(&ls);
1216 ls.cr();
1217 }
1218 }
1219
1220 curr = curr->_next;
1221 }
1222
1223 return array;
1224 }
1225
1226 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
1227 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
1228 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
1229 // Needs fixing, see JDK-8199007.
1230 if (cld->metaspace_or_null() != NULL && Metaspace::contains(x)) {
1231 return true;
1232 }
1233 }
1234 return false;
1235 }
1236
1237 #ifndef PRODUCT
1238 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1239 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1240 if (loader_data == data) {
1241 return true;
1242 }
1243 }
1244
1245 return false;
1246 }
1247 #endif // PRODUCT
1248
1249
1250 // Move class loader data from main list to the unloaded list for unloading
1251 // and deallocation later.
1252 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1253 bool clean_previous_versions) {
1254
1255 ClassLoaderData* data = _head;
1256 ClassLoaderData* prev = NULL;
1257 bool seen_dead_loader = false;
1258
1259 // Mark metadata seen on the stack only so we can delete unneeded entries.
1260 // Only walk all metadata, including the expensive code cache walk, for Full GC
1261 // and only if class redefinition and if there's previous versions of
1262 // Klasses to delete.
1263 bool walk_all_metadata = clean_previous_versions &&
1264 JvmtiExport::has_redefined_a_class() &&
1265 InstanceKlass::has_previous_versions_and_reset();
1266 MetadataOnStackMark md_on_stack(walk_all_metadata);
1267
1268 // Save previous _unloading pointer for CMS which may add to unloading list before
1269 // purging and we don't want to rewalk the previously unloaded class loader data.
1270 _saved_unloading = _unloading;
1271
1272 data = _head;
1273 while (data != NULL) {
1274 if (data->is_alive(is_alive_closure)) {
1275 // clean metaspace
1276 if (walk_all_metadata) {
1277 data->classes_do(InstanceKlass::purge_previous_versions);
1278 }
1279 data->free_deallocate_list();
1280 prev = data;
1281 data = data->next();
1282 continue;
1283 }
1284 seen_dead_loader = true;
1285 ClassLoaderData* dead = data;
1286 dead->unload();
1287 data = data->next();
1288 // Remove from loader list.
1289 // This class loader data will no longer be found
1290 // in the ClassLoaderDataGraph.
1291 if (prev != NULL) {
1292 prev->set_next(data);
1293 } else {
1294 assert(dead == _head, "sanity check");
1295 _head = data;
1296 }
1297 dead->set_next(_unloading);
1298 _unloading = dead;
1299 }
1300
1301 if (seen_dead_loader) {
1302 data = _head;
1303 while (data != NULL) {
1304 // Remove entries in the dictionary of live class loader that have
1305 // initiated loading classes in a dead class loader.
1306 if (data->dictionary() != NULL) {
1307 data->dictionary()->do_unloading(is_alive_closure);
1308 }
1309 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1310 // lists to determine if there are modules on those lists that are now
1311 // dead and should be removed. A module's life cycle is equivalent
1312 // to its defining class loader's life cycle. Since a module is
1313 // considered dead if its class loader is dead, these walks must
1314 // occur after each class loader's aliveness is determined.
1315 if (data->packages() != NULL) {
1316 data->packages()->purge_all_package_exports();
1317 }
1318 if (data->modules_defined()) {
1319 data->modules()->purge_all_module_reads();
1320 }
1321 data = data->next();
1322 }
1323
1324 post_class_unload_events();
1325 }
1326
1327 return seen_dead_loader;
1328 }
1329
1330 void ClassLoaderDataGraph::purge() {
1331 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1332 ClassLoaderData* list = _unloading;
1333 _unloading = NULL;
1334 ClassLoaderData* next = list;
1335 bool classes_unloaded = false;
1336 while (next != NULL) {
1337 ClassLoaderData* purge_me = next;
1338 next = purge_me->next();
1339 delete purge_me;
1340 classes_unloaded = true;
1341 }
1342 if (classes_unloaded) {
1343 Metaspace::purge();
1344 set_metaspace_oom(false);
1345 }
1346 }
1347
1348 int ClassLoaderDataGraph::resize_if_needed() {
1349 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1350 int resized = 0;
1351 if (Dictionary::does_any_dictionary_needs_resizing()) {
1352 FOR_ALL_DICTIONARY(cld) {
1353 if (cld->dictionary()->resize_if_needed()) {
1354 resized++;
1355 }
1356 }
1357 }
1358 return resized;
1359 }
1360
1361 void ClassLoaderDataGraph::post_class_unload_events() {
1362 #if INCLUDE_TRACE
1363 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1364 if (Tracing::enabled()) {
1365 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1366 assert(_unloading != NULL, "need class loader data unload list!");
1367 _class_unload_time = Ticks::now();
1368 classes_unloading_do(&class_unload_event);
1369 }
1370 Tracing::on_unloading_classes();
1371 }
1372 #endif
1373 }
1374
1375 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1376 : _next_klass(NULL) {
1377 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1378 Klass* klass = NULL;
1379
1380 // Find the first klass in the CLDG.
1381 while (cld != NULL) {
1382 assert_locked_or_safepoint(cld->metaspace_lock());
1383 klass = cld->_klasses;
1384 if (klass != NULL) {
1385 _next_klass = klass;
1386 return;
1387 }
1388 cld = cld->next();
1389 }
1390 }
1391
1392 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1393 Klass* next = klass->next_link();
1394 if (next != NULL) {
1395 return next;
1396 }
1397
1398 // No more klasses in the current CLD. Time to find a new CLD.
1399 ClassLoaderData* cld = klass->class_loader_data();
1400 assert_locked_or_safepoint(cld->metaspace_lock());
1401 while (next == NULL) {
1402 cld = cld->next();
1403 if (cld == NULL) {
1404 break;
1405 }
1406 next = cld->_klasses;
1407 }
1408
1409 return next;
1410 }
1411
1412 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1413 Klass* head = _next_klass;
1414
1415 while (head != NULL) {
1416 Klass* next = next_klass_in_cldg(head);
1417
1418 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1419
1420 if (old_head == head) {
1421 return head; // Won the CAS.
1422 }
1423
1424 head = old_head;
1425 }
1426
1427 // Nothing more for the iterator to hand out.
1428 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1429 return NULL;
1430 }
1431
1432 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1433 _data = ClassLoaderDataGraph::_head;
1434 }
1435
1436 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1437
1438 #ifndef PRODUCT
1439 // callable from debugger
1440 extern "C" int print_loader_data_graph() {
1441 ResourceMark rm;
1442 ClassLoaderDataGraph::print_on(tty);
1443 return 0;
1444 }
1445
1446 void ClassLoaderDataGraph::verify() {
1447 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1448 data->verify();
1449 }
1450 }
1451
1452 void ClassLoaderDataGraph::print_on(outputStream * const out) {
1453 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1454 data->print_on(out);
1455 }
1456 }
1457 #endif // PRODUCT
1458
1459 #if INCLUDE_TRACE
1460
1461 Ticks ClassLoaderDataGraph::_class_unload_time;
1462
1463 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1464 assert(k != NULL, "invariant");
1465
1466 // post class unload event
1467 EventClassUnload event(UNTIMED);
1468 event.set_endtime(_class_unload_time);
1469 event.set_unloadedClass(k);
1470 event.set_definingClassLoader(k->class_loader_data());
1471 event.commit();
1472 }
1473
1474 #endif // INCLUDE_TRACE