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 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
84
85 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
86 _class_loader(h_class_loader()),
87 _is_anonymous(is_anonymous),
88 // An anonymous class loader data doesn't have anything to keep
89 // it from being unloaded during parsing of the anonymous class.
90 // The null-class-loader should always be kept alive.
91 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
92 _metaspace(NULL), _unloading(false), _klasses(NULL),
93 _modules(NULL), _packages(NULL),
94 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false),
95 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
96 _next(NULL), _dependencies(dependencies),
97 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
98 Monitor::_safepoint_check_never)) {
99
100 // A ClassLoaderData created solely for an anonymous class should never have a
101 // ModuleEntryTable or PackageEntryTable created for it. The defining package
102 // and module for an anonymous class will be found in its host class.
103 if (!is_anonymous) {
104 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
105 if (h_class_loader.is_null()) {
106 // Create unnamed module for boot loader
107 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
108 } else {
109 // Create unnamed module for all other loaders
110 _unnamed_module = ModuleEntry::create_unnamed_module(this);
111 }
112 } else {
113 _unnamed_module = NULL;
114 }
115
116 if (!is_anonymous) {
117 _dictionary = create_dictionary();
118 } else {
119 _dictionary = NULL;
120 }
121 TRACE_INIT_ID(this);
122 }
123
124 void ClassLoaderData::init_dependencies(TRAPS) {
125 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
126 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
127 _dependencies.init(CHECK);
128 }
129
130 void ClassLoaderData::Dependencies::init(TRAPS) {
131 // Create empty dependencies array to add to. CMS requires this to be
132 // an oop so that it can track additions via card marks. We think.
133 _list_head = oopFactory::new_objectArray(2, CHECK);
134 }
135
136 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
137 Chunk* c = _head;
138 while (c != NULL) {
139 Chunk* next = c->_next;
140 delete c;
141 c = next;
142 }
143 }
144
145 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
146 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
147 Chunk* next = new Chunk(_head);
148 OrderAccess::release_store(&_head, next);
149 }
150 oop* handle = &_head->_data[_head->_size];
151 *handle = o;
152 OrderAccess::release_store(&_head->_size, _head->_size + 1);
153 return handle;
154 }
155
156 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
157 for (juint i = 0; i < size; i++) {
158 if (c->_data[i] != NULL) {
159 f->do_oop(&c->_data[i]);
160 }
161 }
162 }
163
164 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
165 Chunk* head = OrderAccess::load_acquire(&_head);
166 if (head != NULL) {
167 // Must be careful when reading size of head
168 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
169 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
170 oops_do_chunk(f, c, c->_size);
171 }
172 }
173 }
174
175 #ifdef ASSERT
176 class VerifyContainsOopClosure : public OopClosure {
177 oop* _target;
178 bool _found;
179
180 public:
181 VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {}
182
183 void do_oop(oop* p) {
184 if (p == _target) {
185 _found = true;
186 }
187 }
188
189 void do_oop(narrowOop* p) {
190 // The ChunkedHandleList should not contain any narrowOop
191 ShouldNotReachHere();
192 }
193
194 bool found() const {
195 return _found;
196 }
197 };
198
199 bool ClassLoaderData::ChunkedHandleList::contains(oop* p) {
200 VerifyContainsOopClosure cl(p);
201 oops_do(&cl);
202 return cl.found();
203 }
204 #endif // ASSERT
205
206 bool ClassLoaderData::claim() {
207 if (_claimed == 1) {
208 return false;
209 }
210
211 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
212 }
213
214 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
215 // while the class is being parsed, and if the class appears on the module fixup list.
216 // Due to the uniqueness that no other class shares the anonymous class' name or
217 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
218 // it is being defined, therefore _keep_alive is not volatile or atomic.
219 void ClassLoaderData::inc_keep_alive() {
220 if (is_anonymous()) {
221 assert(_keep_alive >= 0, "Invalid keep alive increment count");
222 _keep_alive++;
223 }
224 }
225
226 void ClassLoaderData::dec_keep_alive() {
227 if (is_anonymous()) {
228 assert(_keep_alive > 0, "Invalid keep alive decrement count");
229 _keep_alive--;
230 }
231 }
232
233 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
234 if (must_claim && !claim()) {
235 return;
236 }
237
238 // Only clear modified_oops after the ClassLoaderData is claimed.
239 if (clear_mod_oops) {
240 clear_modified_oops();
241 }
242
243 f->do_oop(&_class_loader);
244 _dependencies.oops_do(f);
245 _handles.oops_do(f);
246 }
247
248 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
249 f->do_oop((oop*)&_list_head);
250 }
251
252 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
253 // Lock-free access requires load_acquire
254 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
255 klass_closure->do_klass(k);
256 assert(k != k->next_link(), "no loops!");
257 }
258 }
259
260 void ClassLoaderData::classes_do(void f(Klass * const)) {
261 // Lock-free access requires load_acquire
262 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
263 f(k);
264 assert(k != k->next_link(), "no loops!");
265 }
266 }
267
268 void ClassLoaderData::methods_do(void f(Method*)) {
269 // Lock-free access requires load_acquire
270 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
271 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
272 InstanceKlass::cast(k)->methods_do(f);
273 }
274 }
275 }
276
277 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
278 // Lock-free access requires load_acquire
279 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
280 // Do not filter ArrayKlass oops here...
281 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
282 klass_closure->do_klass(k);
283 }
284 }
285 }
286
287 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
288 // Lock-free access requires load_acquire
289 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
290 if (k->is_instance_klass()) {
291 f(InstanceKlass::cast(k));
292 }
293 assert(k != k->next_link(), "no loops!");
294 }
295 }
296
297 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
298 assert_locked_or_safepoint(Module_lock);
299 if (_unnamed_module != NULL) {
300 f(_unnamed_module);
301 }
302 if (_modules != NULL) {
303 for (int i = 0; i < _modules->table_size(); i++) {
304 for (ModuleEntry* entry = _modules->bucket(i);
305 entry != NULL;
306 entry = entry->next()) {
307 f(entry);
308 }
309 }
310 }
311 }
312
313 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
314 assert_locked_or_safepoint(Module_lock);
315 if (_packages != NULL) {
316 for (int i = 0; i < _packages->table_size(); i++) {
317 for (PackageEntry* entry = _packages->bucket(i);
318 entry != NULL;
319 entry = entry->next()) {
320 f(entry);
321 }
322 }
323 }
324 }
325
326 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
327 assert(k != NULL, "invariant");
328
329 ClassLoaderData * const from_cld = this;
330 ClassLoaderData * const to_cld = k->class_loader_data();
331
332 // Do not need to record dependency if the dependency is to a class whose
333 // class loader data is never freed. (i.e. the dependency's class loader
334 // is one of the three builtin class loaders and the dependency is not
335 // anonymous.)
336 if (to_cld->is_permanent_class_loader_data()) {
337 return;
338 }
339
340 oop to;
341 if (to_cld->is_anonymous()) {
342 // Anonymous class dependencies are through the mirror.
343 to = k->java_mirror();
344 } else {
345 to = to_cld->class_loader();
346 oop from = from_cld->class_loader();
347
348 // Just return if this dependency is to a class with the same or a parent
349 // class_loader.
350 if (from == to || java_lang_ClassLoader::isAncestor(from, to)) {
351 return; // this class loader is in the parent list, no need to add it.
352 }
353 }
354
355 // It's a dependency we won't find through GC, add it. This is relatively rare.
356 // Must handle over GC point.
357 Handle dependency(THREAD, to);
358 from_cld->_dependencies.add(dependency, CHECK);
359
360 // Added a potentially young gen oop to the ClassLoaderData
361 record_modified_oops();
362 }
363
364
365 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
366 // Check first if this dependency is already in the list.
367 // Save a pointer to the last to add to under the lock.
368 objArrayOop ok = _list_head;
369 objArrayOop last = NULL;
370 while (ok != NULL) {
371 last = ok;
372 if (ok->obj_at(0) == dependency()) {
373 // Don't need to add it
374 return;
375 }
376 ok = (objArrayOop)ok->obj_at(1);
377 }
378
379 // Must handle over GC points
380 assert (last != NULL, "dependencies should be initialized");
381 objArrayHandle last_handle(THREAD, last);
382
383 // Create a new dependency node with fields for (class_loader or mirror, next)
384 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
385 deps->obj_at_put(0, dependency());
386
387 // Must handle over GC points
388 objArrayHandle new_dependency(THREAD, deps);
389
390 // Add the dependency under lock
391 locked_add(last_handle, new_dependency, THREAD);
392 }
393
394 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
395 objArrayHandle new_dependency,
396 Thread* THREAD) {
397
398 // Have to lock and put the new dependency on the end of the dependency
399 // array so the card mark for CMS sees that this dependency is new.
400 // Can probably do this lock free with some effort.
401 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
402
403 oop loader_or_mirror = new_dependency->obj_at(0);
404
405 // Since the dependencies are only added, add to the end.
406 objArrayOop end = last_handle();
407 objArrayOop last = NULL;
408 while (end != NULL) {
409 last = end;
410 // check again if another thread added it to the end.
411 if (end->obj_at(0) == loader_or_mirror) {
412 // Don't need to add it
413 return;
414 }
415 end = (objArrayOop)end->obj_at(1);
416 }
417 assert (last != NULL, "dependencies should be initialized");
418 // fill in the first element with the oop in new_dependency.
419 if (last->obj_at(0) == NULL) {
420 last->obj_at_put(0, new_dependency->obj_at(0));
421 } else {
422 last->obj_at_put(1, new_dependency());
423 }
424 }
425
426 void ClassLoaderDataGraph::clear_claimed_marks() {
427 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
428 cld->clear_claimed();
429 }
430 }
431
432 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
433 {
434 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
435 Klass* old_value = _klasses;
436 k->set_next_link(old_value);
437 // Link the new item into the list, making sure the linked class is stable
438 // since the list can be walked without a lock
439 OrderAccess::release_store(&_klasses, k);
440 }
441
442 if (publicize && k->class_loader_data() != NULL) {
443 ResourceMark rm;
444 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
445 PTR_FORMAT " loader: " PTR_FORMAT " %s",
446 p2i(k),
447 k->external_name(),
448 p2i(k->class_loader_data()),
449 p2i((void *)k->class_loader()),
450 loader_name());
451 }
452 }
453
454 // Class iterator used by the compiler. It gets some number of classes at
455 // a safepoint to decay invocation counters on the methods.
456 class ClassLoaderDataGraphKlassIteratorStatic {
457 ClassLoaderData* _current_loader_data;
458 Klass* _current_class_entry;
459 public:
460
461 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
462
463 InstanceKlass* try_get_next_class() {
464 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
465 int max_classes = InstanceKlass::number_of_instance_classes();
466 assert(max_classes > 0, "should not be called with no instance classes");
467 for (int i = 0; i < max_classes; ) {
468
469 if (_current_class_entry != NULL) {
470 Klass* k = _current_class_entry;
471 _current_class_entry = _current_class_entry->next_link();
472
473 if (k->is_instance_klass()) {
474 InstanceKlass* ik = InstanceKlass::cast(k);
475 i++; // count all instance classes found
476 // Not yet loaded classes are counted in max_classes
477 // but only return loaded classes.
478 if (ik->is_loaded()) {
479 return ik;
480 }
481 }
482 } else {
483 // Go to next CLD
484 if (_current_loader_data != NULL) {
485 _current_loader_data = _current_loader_data->next();
486 }
487 // Start at the beginning
488 if (_current_loader_data == NULL) {
489 _current_loader_data = ClassLoaderDataGraph::_head;
490 }
491
492 _current_class_entry = _current_loader_data->klasses();
493 }
494 }
495 // Should never be reached unless all instance classes have failed or are not fully loaded.
496 // Caller handles NULL.
497 return NULL;
498 }
499
500 // If the current class for the static iterator is a class being unloaded or
501 // deallocated, adjust the current class.
502 void adjust_saved_class(ClassLoaderData* cld) {
503 if (_current_loader_data == cld) {
504 _current_loader_data = cld->next();
505 if (_current_loader_data != NULL) {
506 _current_class_entry = _current_loader_data->klasses();
507 } // else try_get_next_class will start at the head
508 }
509 }
510
511 void adjust_saved_class(Klass* klass) {
512 if (_current_class_entry == klass) {
513 _current_class_entry = klass->next_link();
514 }
515 }
516 };
517
518 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
519
520 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
521 return static_klass_iterator.try_get_next_class();
522 }
523
524
525 // Remove a klass from the _klasses list for scratch_class during redefinition
526 // or parsed class in the case of an error.
527 void ClassLoaderData::remove_class(Klass* scratch_class) {
528 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
529
530 // Adjust global class iterator.
531 static_klass_iterator.adjust_saved_class(scratch_class);
532
533 Klass* prev = NULL;
534 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
535 if (k == scratch_class) {
536 if (prev == NULL) {
537 _klasses = k->next_link();
538 } else {
539 Klass* next = k->next_link();
540 prev->set_next_link(next);
541 }
542 return;
543 }
544 prev = k;
545 assert(k != k->next_link(), "no loops!");
546 }
547 ShouldNotReachHere(); // should have found this class!!
548 }
549
550 void ClassLoaderData::unload() {
551 _unloading = true;
552
553 // Tell serviceability tools these classes are unloading
554 classes_do(InstanceKlass::notify_unload_class);
555
556 LogTarget(Debug, class, loader, data) lt;
557 if (lt.is_enabled()) {
558 ResourceMark rm;
559 LogStream ls(lt);
560 ls.print(": unload loader data " INTPTR_FORMAT, p2i(this));
561 ls.print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
562 loader_name());
563 if (is_anonymous()) {
564 ls.print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
565 }
566 ls.cr();
567 }
568
569 // Some items on the _deallocate_list need to free their C heap structures
570 // if they are not already on the _klasses list.
571 unload_deallocate_list();
572
573 // Clean up global class iterator for compiler
574 static_klass_iterator.adjust_saved_class(this);
575 }
576
577 ModuleEntryTable* ClassLoaderData::modules() {
578 // Lazily create the module entry table at first request.
579 // Lock-free access requires load_acquire.
580 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
581 if (modules == NULL) {
582 MutexLocker m1(Module_lock);
583 // Check if _modules got allocated while we were waiting for this lock.
584 if ((modules = _modules) == NULL) {
585 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
586
587 {
588 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
589 // Ensure _modules is stable, since it is examined without a lock
590 OrderAccess::release_store(&_modules, modules);
591 }
592 }
593 }
594 return modules;
595 }
596
597 const int _boot_loader_dictionary_size = 1009;
598 const int _default_loader_dictionary_size = 107;
599
600 Dictionary* ClassLoaderData::create_dictionary() {
601 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
602 int size;
603 bool resizable = false;
604 if (_the_null_class_loader_data == NULL) {
605 size = _boot_loader_dictionary_size;
606 resizable = true;
607 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
608 size = 1; // there's only one class in relection class loader and no initiated classes
609 } else if (is_system_class_loader_data()) {
610 size = _boot_loader_dictionary_size;
611 resizable = true;
612 } else {
613 size = _default_loader_dictionary_size;
614 resizable = true;
615 }
616 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) {
617 resizable = false;
618 }
619 return new Dictionary(this, size, resizable);
620 }
621
622 // Unloading support
623 oop ClassLoaderData::keep_alive_object() const {
624 assert_locked_or_safepoint(_metaspace_lock);
625 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
626 return is_anonymous() ? _klasses->java_mirror() : class_loader();
627 }
628
629 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
630 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
631 || is_alive_closure->do_object_b(keep_alive_object());
632
633 return alive;
634 }
635
636 ClassLoaderData::~ClassLoaderData() {
637 // Release C heap structures for all the classes.
638 classes_do(InstanceKlass::release_C_heap_structures);
639
640 // Release C heap allocated hashtable for all the packages.
641 if (_packages != NULL) {
642 // Destroy the table itself
643 delete _packages;
644 _packages = NULL;
645 }
646
647 // Release C heap allocated hashtable for all the modules.
648 if (_modules != NULL) {
649 // Destroy the table itself
650 delete _modules;
651 _modules = NULL;
652 }
653
654 // Release C heap allocated hashtable for the dictionary
655 if (_dictionary != NULL) {
656 // Destroy the table itself
657 delete _dictionary;
658 _dictionary = NULL;
659 }
660
661 if (_unnamed_module != NULL) {
662 _unnamed_module->delete_unnamed_module();
663 _unnamed_module = NULL;
664 }
665
666 // release the metaspace
667 Metaspace *m = _metaspace;
668 if (m != NULL) {
669 _metaspace = NULL;
670 delete m;
671 }
672 // Clear all the JNI handles for methods
673 // These aren't deallocated and are going to look like a leak, but that's
674 // needed because we can't really get rid of jmethodIDs because we don't
675 // know when native code is going to stop using them. The spec says that
676 // they're "invalid" but existing programs likely rely on their being
677 // NULL after class unloading.
678 if (_jmethod_ids != NULL) {
679 Method::clear_jmethod_ids(this);
680 }
681 // Delete lock
682 delete _metaspace_lock;
683
684 // Delete free list
685 if (_deallocate_list != NULL) {
686 delete _deallocate_list;
687 }
688 }
689
690 // Returns true if this class loader data is for the system class loader.
691 bool ClassLoaderData::is_system_class_loader_data() const {
692 return SystemDictionary::is_system_class_loader(class_loader());
693 }
694
695 // Returns true if this class loader data is for the platform class loader.
696 bool ClassLoaderData::is_platform_class_loader_data() const {
697 return SystemDictionary::is_platform_class_loader(class_loader());
698 }
699
700 // Returns true if this class loader data is one of the 3 builtin
701 // (boot, application/system or platform) class loaders. Note that
702 // if the class loader data is for an anonymous class then it may get
703 // freed by a GC even if its class loader is one of the 3 builtin
704 // loaders.
705 bool ClassLoaderData::is_builtin_class_loader_data() const {
706 return (is_the_null_class_loader_data() ||
707 SystemDictionary::is_system_class_loader(class_loader()) ||
708 SystemDictionary::is_platform_class_loader(class_loader()));
709 }
710
711 // Returns true if this class loader data is a class loader data
712 // that is not ever freed by a GC. It must be one of the builtin
713 // class loaders and not anonymous.
714 bool ClassLoaderData::is_permanent_class_loader_data() const {
715 return is_builtin_class_loader_data() && !is_anonymous();
716 }
717
718 Metaspace* ClassLoaderData::metaspace_non_null() {
719 // If the metaspace has not been allocated, create a new one. Might want
720 // to create smaller arena for Reflection class loaders also.
721 // The reason for the delayed allocation is because some class loaders are
722 // simply for delegating with no metadata of their own.
723 // Lock-free access requires load_acquire.
724 Metaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
725 if (metaspace == NULL) {
726 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
727 // Check if _metaspace got allocated while we were waiting for this lock.
728 if ((metaspace = _metaspace) == NULL) {
729 if (this == the_null_class_loader_data()) {
730 assert (class_loader() == NULL, "Must be");
731 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
732 } else if (is_anonymous()) {
733 if (class_loader() != NULL) {
734 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
735 }
736 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
737 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
738 if (class_loader() != NULL) {
739 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
740 }
741 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
742 } else {
743 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
744 }
745 // Ensure _metaspace is stable, since it is examined without a lock
746 OrderAccess::release_store(&_metaspace, metaspace);
747 }
748 }
749 return metaspace;
750 }
751
752 OopHandle ClassLoaderData::add_handle(Handle h) {
753 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
754 record_modified_oops();
755 return OopHandle(_handles.add(h()));
756 }
757
758 void ClassLoaderData::remove_handle(OopHandle h) {
759 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
760 oop* ptr = h.ptr_raw();
761 if (ptr != NULL) {
762 assert(_handles.contains(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
763 // This root is not walked in safepoints, and hence requires an appropriate
764 // decorator that e.g. maintains the SATB invariant in SATB collectors.
765 RootAccess<IN_CONCURRENT_ROOT>::oop_store(ptr, oop(NULL));
766 }
767 }
768
769 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
770 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
771 if (dest.resolve() != NULL) {
772 return;
773 } else {
774 dest = _handles.add(h());
775 }
776 }
777
778 // Add this metadata pointer to be freed when it's safe. This is only during
779 // class unloading because Handles might point to this metadata field.
780 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
781 // Metadata in shared region isn't deleted.
782 if (!m->is_shared()) {
783 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
784 if (_deallocate_list == NULL) {
785 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
786 }
787 _deallocate_list->append_if_missing(m);
788 }
789 }
790
791 // Deallocate free metadata on the free list. How useful the PermGen was!
792 void ClassLoaderData::free_deallocate_list() {
793 // Don't need lock, at safepoint
794 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
795 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
796 if (_deallocate_list == NULL) {
797 return;
798 }
799 // Go backwards because this removes entries that are freed.
800 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
801 Metadata* m = _deallocate_list->at(i);
802 if (!m->on_stack()) {
803 _deallocate_list->remove_at(i);
804 // There are only three types of metadata that we deallocate directly.
805 // Cast them so they can be used by the template function.
806 if (m->is_method()) {
807 MetadataFactory::free_metadata(this, (Method*)m);
808 } else if (m->is_constantPool()) {
809 MetadataFactory::free_metadata(this, (ConstantPool*)m);
810 } else if (m->is_klass()) {
811 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
812 } else {
813 ShouldNotReachHere();
814 }
815 } else {
816 // Metadata is alive.
817 // If scratch_class is on stack then it shouldn't be on this list!
818 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
819 "scratch classes on this list should be dead");
820 // Also should assert that other metadata on the list was found in handles.
821 }
822 }
823 }
824
825 // This is distinct from free_deallocate_list. For class loader data that are
826 // unloading, this frees the C heap memory for items on the list, and unlinks
827 // scratch or error classes so that unloading events aren't triggered for these
828 // classes. The metadata is removed with the unloading metaspace.
829 // There isn't C heap memory allocated for methods, so nothing is done for them.
830 void ClassLoaderData::unload_deallocate_list() {
831 // Don't need lock, at safepoint
832 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
833 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
834 if (_deallocate_list == NULL) {
835 return;
836 }
837 // Go backwards because this removes entries that are freed.
838 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
839 Metadata* m = _deallocate_list->at(i);
840 assert (!m->on_stack(), "wouldn't be unloading if this were so");
841 _deallocate_list->remove_at(i);
842 if (m->is_constantPool()) {
843 ((ConstantPool*)m)->release_C_heap_structures();
844 } else if (m->is_klass()) {
845 InstanceKlass* ik = (InstanceKlass*)m;
846 // also releases ik->constants() C heap memory
847 InstanceKlass::release_C_heap_structures(ik);
848 // Remove the class so unloading events aren't triggered for
849 // this class (scratch or error class) in do_unloading().
850 remove_class(ik);
851 }
852 }
853 }
854
855 // These anonymous class loaders are to contain classes used for JSR292
856 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
857 // Add a new class loader data to the graph.
858 Handle lh(THREAD, loader);
859 return ClassLoaderDataGraph::add(lh, true, THREAD);
860 }
861
862 const char* ClassLoaderData::loader_name() {
863 // Handles null class loader
864 return SystemDictionary::loader_name(class_loader());
865 }
866
867 #ifndef PRODUCT
868 // Define to dump klasses
869 #undef CLD_DUMP_KLASSES
870
871 void ClassLoaderData::dump(outputStream * const out) {
872 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
873 p2i(this), p2i((void *)class_loader()),
874 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
875 if (claimed()) out->print(" claimed ");
876 if (is_unloading()) out->print(" unloading ");
877 out->cr();
878 if (metaspace_or_null() != NULL) {
879 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
880 metaspace_or_null()->dump(out);
881 } else {
882 out->print_cr("metaspace: NULL");
883 }
884
885 #ifdef CLD_DUMP_KLASSES
886 if (Verbose) {
887 Klass* k = _klasses;
888 while (k != NULL) {
889 out->print_cr("klass " PTR_FORMAT ", %s", p2i(k), k->name()->as_C_string());
890 assert(k != k->next_link(), "no loops!");
891 k = k->next_link();
892 }
893 }
894 #endif // CLD_DUMP_KLASSES
895 #undef CLD_DUMP_KLASSES
896 if (_jmethod_ids != NULL) {
897 Method::print_jmethod_ids(this, out);
898 }
899 out->print_cr("}");
900 }
901 #endif // PRODUCT
902
903 void ClassLoaderData::verify() {
904 assert_locked_or_safepoint(_metaspace_lock);
905 oop cl = class_loader();
906
907 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
908 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
909
910 // Verify the integrity of the allocated space.
911 if (metaspace_or_null() != NULL) {
912 metaspace_or_null()->verify();
913 }
914
915 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
916 guarantee(k->class_loader_data() == this, "Must be the same");
917 k->verify();
918 assert(k != k->next_link(), "no loops!");
919 }
920 }
921
922 bool ClassLoaderData::contains_klass(Klass* klass) {
923 // Lock-free access requires load_acquire
924 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
925 if (k == klass) return true;
926 }
927 return false;
928 }
929
930
931 // GC root of class loader data created.
932 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
933 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
934 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
935 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
936
937 bool ClassLoaderDataGraph::_should_purge = false;
938 bool ClassLoaderDataGraph::_metaspace_oom = false;
939
940 // Add a new class loader data node to the list. Assign the newly created
941 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
942 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
943 // We need to allocate all the oops for the ClassLoaderData before allocating the
944 // actual ClassLoaderData object.
945 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
946
947 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
948 // ClassLoaderData in the graph since the CLD
949 // contains unhandled oops
950
951 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
952
953
954 if (!is_anonymous) {
955 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
956 // First, Atomically set it
957 ClassLoaderData* old = Atomic::cmpxchg(cld, cld_addr, (ClassLoaderData*)NULL);
958 if (old != NULL) {
959 delete cld;
960 // Returns the data.
961 return old;
962 }
963 }
964
965 // We won the race, and therefore the task of adding the data to the list of
966 // class loader data
967 ClassLoaderData** list_head = &_head;
968 ClassLoaderData* next = _head;
969
970 do {
971 cld->set_next(next);
972 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next);
973 if (exchanged == next) {
974 LogTarget(Debug, class, loader, data) lt;
975 if (lt.is_enabled()) {
976 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
977 LogStream ls(lt);
978 print_creation(&ls, loader, cld, CHECK_NULL);
979 }
980 return cld;
981 }
982 next = exchanged;
983 } while (true);
984 }
985
986 void ClassLoaderDataGraph::print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS) {
987 Handle string;
988 if (loader.not_null()) {
989 // Include the result of loader.toString() in the output. This allows
990 // the user of the log to identify the class loader instance.
991 JavaValue result(T_OBJECT);
992 Klass* spec_klass = SystemDictionary::ClassLoader_klass();
993 JavaCalls::call_virtual(&result,
994 loader,
995 spec_klass,
996 vmSymbols::toString_name(),
997 vmSymbols::void_string_signature(),
998 CHECK);
999 assert(result.get_type() == T_OBJECT, "just checking");
1000 string = Handle(THREAD, (oop)result.get_jobject());
1001 }
1002
1003 ResourceMark rm;
1004 out->print("create class loader data " INTPTR_FORMAT, p2i(cld));
1005 out->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
1006 cld->loader_name());
1007
1008 if (string.not_null()) {
1009 out->print(": ");
1010 java_lang_String::print(string(), out);
1011 }
1012 out->cr();
1013 }
1014
1015
1016 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1017 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1018 cld->oops_do(f, must_claim);
1019 }
1020 }
1021
1022 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1023 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1024 if (cld->keep_alive()) {
1025 cld->oops_do(f, must_claim);
1026 }
1027 }
1028 }
1029
1030 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1031 if (ClassUnloading) {
1032 keep_alive_oops_do(f, must_claim);
1033 } else {
1034 oops_do(f, must_claim);
1035 }
1036 }
1037
1038 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1039 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1040 cl->do_cld(cld);
1041 }
1042 }
1043
1044 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1045 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1046 // Only walk the head until any clds not purged from prior unloading
1047 // (CMS doesn't purge right away).
1048 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1049 assert(cld->is_unloading(), "invariant");
1050 cl->do_cld(cld);
1051 }
1052 }
1053
1054 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1055 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1056 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1057 if (closure != NULL) {
1058 closure->do_cld(cld);
1059 }
1060 }
1061 }
1062
1063 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1064 roots_cld_do(cl, NULL);
1065 }
1066
1067 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1068 if (ClassUnloading) {
1069 keep_alive_cld_do(cl);
1070 } else {
1071 cld_do(cl);
1072 }
1073 }
1074
1075 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1076 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1077 cld->classes_do(klass_closure);
1078 }
1079 }
1080
1081 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1082 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1083 cld->classes_do(f);
1084 }
1085 }
1086
1087 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1088 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1089 cld->methods_do(f);
1090 }
1091 }
1092
1093 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1094 assert_locked_or_safepoint(Module_lock);
1095 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1096 cld->modules_do(f);
1097 }
1098 }
1099
1100 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1101 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1102 // Only walk the head until any clds not purged from prior unloading
1103 // (CMS doesn't purge right away).
1104 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1105 assert(cld->is_unloading(), "invariant");
1106 cld->modules_do(f);
1107 }
1108 }
1109
1110 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1111 assert_locked_or_safepoint(Module_lock);
1112 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1113 cld->packages_do(f);
1114 }
1115 }
1116
1117 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1118 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1119 // Only walk the head until any clds not purged from prior unloading
1120 // (CMS doesn't purge right away).
1121 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1122 assert(cld->is_unloading(), "invariant");
1123 cld->packages_do(f);
1124 }
1125 }
1126
1127 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1128 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1129 cld->loaded_classes_do(klass_closure);
1130 }
1131 }
1132
1133 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1134 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1135 // Only walk the head until any clds not purged from prior unloading
1136 // (CMS doesn't purge right away).
1137 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1138 assert(cld->is_unloading(), "invariant");
1139 cld->classes_do(f);
1140 }
1141 }
1142
1143 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1144 if (X->dictionary() != NULL)
1145
1146 // Walk classes in the loaded class dictionaries in various forms.
1147 // Only walks the classes defined in this class loader.
1148 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1149 FOR_ALL_DICTIONARY(cld) {
1150 cld->dictionary()->classes_do(f);
1151 }
1152 }
1153
1154 // Only walks the classes defined in this class loader.
1155 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1156 FOR_ALL_DICTIONARY(cld) {
1157 cld->dictionary()->classes_do(f, CHECK);
1158 }
1159 }
1160
1161 // Walks all entries in the dictionary including entries initiated by this class loader.
1162 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1163 FOR_ALL_DICTIONARY(cld) {
1164 cld->dictionary()->all_entries_do(f);
1165 }
1166 }
1167
1168 void ClassLoaderDataGraph::verify_dictionary() {
1169 FOR_ALL_DICTIONARY(cld) {
1170 cld->dictionary()->verify();
1171 }
1172 }
1173
1174 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1175 FOR_ALL_DICTIONARY(cld) {
1176 st->print("Dictionary for ");
1177 cld->print_value_on(st);
1178 st->cr();
1179 cld->dictionary()->print_on(st);
1180 st->cr();
1181 }
1182 }
1183
1184 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1185 FOR_ALL_DICTIONARY(cld) {
1186 ResourceMark rm;
1187 stringStream tempst;
1188 tempst.print("System Dictionary for %s", cld->loader_name());
1189 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1190 }
1191 }
1192
1193 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1194 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1195
1196 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1197
1198 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1199 ClassLoaderData* curr = _head;
1200 while (curr != _saved_head) {
1201 if (!curr->claimed()) {
1202 array->push(curr);
1203 LogTarget(Debug, class, loader, data) lt;
1204 if (lt.is_enabled()) {
1205 LogStream ls(lt);
1206 ls.print("found new CLD: ");
1207 curr->print_value_on(&ls);
1208 ls.cr();
1209 }
1210 }
1211
1212 curr = curr->_next;
1213 }
1214
1215 return array;
1216 }
1217
1218 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
1219 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
1220 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
1221 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
1222 return true;
1223 }
1224 }
1225 return false;
1226 }
1227
1228 #ifndef PRODUCT
1229 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1230 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1231 if (loader_data == data) {
1232 return true;
1233 }
1234 }
1235
1236 return false;
1237 }
1238 #endif // PRODUCT
1239
1240
1241 // Move class loader data from main list to the unloaded list for unloading
1242 // and deallocation later.
1243 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1244 bool clean_previous_versions) {
1245
1246 ClassLoaderData* data = _head;
1247 ClassLoaderData* prev = NULL;
1248 bool seen_dead_loader = false;
1249
1250 // Mark metadata seen on the stack only so we can delete unneeded entries.
1251 // Only walk all metadata, including the expensive code cache walk, for Full GC
1252 // and only if class redefinition and if there's previous versions of
1253 // Klasses to delete.
1254 bool walk_all_metadata = clean_previous_versions &&
1255 JvmtiExport::has_redefined_a_class() &&
1256 InstanceKlass::has_previous_versions_and_reset();
1257 MetadataOnStackMark md_on_stack(walk_all_metadata);
1258
1259 // Save previous _unloading pointer for CMS which may add to unloading list before
1260 // purging and we don't want to rewalk the previously unloaded class loader data.
1261 _saved_unloading = _unloading;
1262
1263 data = _head;
1264 while (data != NULL) {
1265 if (data->is_alive(is_alive_closure)) {
1266 // clean metaspace
1267 if (walk_all_metadata) {
1268 data->classes_do(InstanceKlass::purge_previous_versions);
1269 }
1270 data->free_deallocate_list();
1271 prev = data;
1272 data = data->next();
1273 continue;
1274 }
1275 seen_dead_loader = true;
1276 ClassLoaderData* dead = data;
1277 dead->unload();
1278 data = data->next();
1279 // Remove from loader list.
1280 // This class loader data will no longer be found
1281 // in the ClassLoaderDataGraph.
1282 if (prev != NULL) {
1283 prev->set_next(data);
1284 } else {
1285 assert(dead == _head, "sanity check");
1286 _head = data;
1287 }
1288 dead->set_next(_unloading);
1289 _unloading = dead;
1290 }
1291
1292 if (seen_dead_loader) {
1293 data = _head;
1294 while (data != NULL) {
1295 // Remove entries in the dictionary of live class loader that have
1296 // initiated loading classes in a dead class loader.
1297 if (data->dictionary() != NULL) {
1298 data->dictionary()->do_unloading(is_alive_closure);
1299 }
1300 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1301 // lists to determine if there are modules on those lists that are now
1302 // dead and should be removed. A module's life cycle is equivalent
1303 // to its defining class loader's life cycle. Since a module is
1304 // considered dead if its class loader is dead, these walks must
1305 // occur after each class loader's aliveness is determined.
1306 if (data->packages() != NULL) {
1307 data->packages()->purge_all_package_exports();
1308 }
1309 if (data->modules_defined()) {
1310 data->modules()->purge_all_module_reads();
1311 }
1312 data = data->next();
1313 }
1314
1315 post_class_unload_events();
1316 }
1317
1318 return seen_dead_loader;
1319 }
1320
1321 void ClassLoaderDataGraph::purge() {
1322 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1323 ClassLoaderData* list = _unloading;
1324 _unloading = NULL;
1325 ClassLoaderData* next = list;
1326 bool classes_unloaded = false;
1327 while (next != NULL) {
1328 ClassLoaderData* purge_me = next;
1329 next = purge_me->next();
1330 delete purge_me;
1331 classes_unloaded = true;
1332 }
1333 if (classes_unloaded) {
1334 Metaspace::purge();
1335 set_metaspace_oom(false);
1336 }
1337 }
1338
1339 int ClassLoaderDataGraph::resize_if_needed() {
1340 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1341 int resized = 0;
1342 if (Dictionary::does_any_dictionary_needs_resizing()) {
1343 FOR_ALL_DICTIONARY(cld) {
1344 if (cld->dictionary()->resize_if_needed()) {
1345 resized++;
1346 }
1347 }
1348 }
1349 return resized;
1350 }
1351
1352 void ClassLoaderDataGraph::post_class_unload_events() {
1353 #if INCLUDE_TRACE
1354 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1355 if (Tracing::enabled()) {
1356 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1357 assert(_unloading != NULL, "need class loader data unload list!");
1358 _class_unload_time = Ticks::now();
1359 classes_unloading_do(&class_unload_event);
1360 }
1361 Tracing::on_unloading_classes();
1362 }
1363 #endif
1364 }
1365
1366 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1367 : _next_klass(NULL) {
1368 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1369 Klass* klass = NULL;
1370
1371 // Find the first klass in the CLDG.
1372 while (cld != NULL) {
1373 assert_locked_or_safepoint(cld->metaspace_lock());
1374 klass = cld->_klasses;
1375 if (klass != NULL) {
1376 _next_klass = klass;
1377 return;
1378 }
1379 cld = cld->next();
1380 }
1381 }
1382
1383 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1384 Klass* next = klass->next_link();
1385 if (next != NULL) {
1386 return next;
1387 }
1388
1389 // No more klasses in the current CLD. Time to find a new CLD.
1390 ClassLoaderData* cld = klass->class_loader_data();
1391 assert_locked_or_safepoint(cld->metaspace_lock());
1392 while (next == NULL) {
1393 cld = cld->next();
1394 if (cld == NULL) {
1395 break;
1396 }
1397 next = cld->_klasses;
1398 }
1399
1400 return next;
1401 }
1402
1403 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1404 Klass* head = _next_klass;
1405
1406 while (head != NULL) {
1407 Klass* next = next_klass_in_cldg(head);
1408
1409 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1410
1411 if (old_head == head) {
1412 return head; // Won the CAS.
1413 }
1414
1415 head = old_head;
1416 }
1417
1418 // Nothing more for the iterator to hand out.
1419 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1420 return NULL;
1421 }
1422
1423 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1424 _data = ClassLoaderDataGraph::_head;
1425 }
1426
1427 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1428
1429 #ifndef PRODUCT
1430 // callable from debugger
1431 extern "C" int print_loader_data_graph() {
1432 ClassLoaderDataGraph::dump_on(tty);
1433 return 0;
1434 }
1435
1436 void ClassLoaderDataGraph::verify() {
1437 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1438 data->verify();
1439 }
1440 }
1441
1442 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1443 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1444 data->dump(out);
1445 }
1446 MetaspaceAux::dump(out);
1447 }
1448 #endif // PRODUCT
1449
1450 void ClassLoaderData::print_value_on(outputStream* out) const {
1451 if (class_loader() == NULL) {
1452 out->print("NULL class loader");
1453 } else {
1454 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1455 class_loader()->print_value_on(out);
1456 }
1457 }
1458
1459 void ClassLoaderData::print_on(outputStream* out) const {
1460 if (class_loader() == NULL) {
1461 out->print("NULL class loader");
1462 } else {
1463 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1464 class_loader()->print_on(out);
1465 }
1466 }
1467
1468 #if INCLUDE_TRACE
1469
1470 Ticks ClassLoaderDataGraph::_class_unload_time;
1471
1472 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1473 assert(k != NULL, "invariant");
1474
1475 // post class unload event
1476 EventClassUnload event(UNTIMED);
1477 event.set_endtime(_class_unload_time);
1478 event.set_unloadedClass(k);
1479 event.set_definingClassLoader(k->class_loader_data());
1480 event.commit();
1481 }
1482
1483 #endif // INCLUDE_TRACE