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