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