1 /*
2 * Copyright (c) 2012, 2017, 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/objArrayOop.inline.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "runtime/atomic.hpp"
69 #include "runtime/javaCalls.hpp"
70 #include "runtime/jniHandles.hpp"
71 #include "runtime/mutex.hpp"
72 #include "runtime/orderAccess.hpp"
73 #include "runtime/safepoint.hpp"
74 #include "runtime/synchronizer.hpp"
75 #include "utilities/growableArray.hpp"
76 #include "utilities/macros.hpp"
77 #include "utilities/ostream.hpp"
78 #if INCLUDE_ALL_GCS
79 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
80 #endif // INCLUDE_ALL_GCS
81 #if INCLUDE_TRACE
82 #include "trace/tracing.hpp"
83 #endif
84
85 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
86
87 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
88 _class_loader(h_class_loader()),
89 _is_anonymous(is_anonymous),
90 // An anonymous class loader data doesn't have anything to keep
91 // it from being unloaded during parsing of the anonymous class.
92 // The null-class-loader should always be kept alive.
93 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
94 _metaspace(NULL), _unloading(false), _klasses(NULL),
95 _modules(NULL), _packages(NULL),
96 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false),
97 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
98 _next(NULL), _dependencies(dependencies),
99 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
100 Monitor::_safepoint_check_never)) {
101
102 // A ClassLoaderData created solely for an anonymous class should never have a
103 // ModuleEntryTable or PackageEntryTable created for it. The defining package
104 // and module for an anonymous class will be found in its host class.
105 if (!is_anonymous) {
106 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
107 if (h_class_loader.is_null()) {
108 // Create unnamed module for boot loader
109 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
110 } else {
111 // Create unnamed module for all other loaders
112 _unnamed_module = ModuleEntry::create_unnamed_module(this);
113 }
114 } else {
115 _unnamed_module = NULL;
116 }
117
118 if (!is_anonymous) {
119 _dictionary = create_dictionary();
120 } else {
121 _dictionary = NULL;
122 }
123 TRACE_INIT_ID(this);
124 }
125
126 void ClassLoaderData::init_dependencies(TRAPS) {
127 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
128 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
129 _dependencies.init(CHECK);
130 }
131
132 void ClassLoaderData::Dependencies::init(TRAPS) {
133 // Create empty dependencies array to add to. CMS requires this to be
134 // an oop so that it can track additions via card marks. We think.
135 _list_head = oopFactory::new_objectArray(2, CHECK);
136 }
137
138 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
139 Chunk* c = _head;
140 while (c != NULL) {
141 Chunk* next = c->_next;
142 delete c;
143 c = next;
144 }
145 }
146
147 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
148 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
149 Chunk* next = new Chunk(_head);
150 OrderAccess::release_store(&_head, next);
151 }
152 oop* handle = &_head->_data[_head->_size];
153 *handle = o;
154 OrderAccess::release_store(&_head->_size, _head->_size + 1);
155 return handle;
156 }
157
158 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
159 for (juint i = 0; i < size; i++) {
160 if (c->_data[i] != NULL) {
161 f->do_oop(&c->_data[i]);
162 }
163 }
164 }
165
166 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
167 Chunk* head = OrderAccess::load_acquire(&_head);
168 if (head != NULL) {
169 // Must be careful when reading size of head
170 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
171 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
172 oops_do_chunk(f, c, c->_size);
173 }
174 }
175 }
176
177 #ifdef ASSERT
178 class VerifyContainsOopClosure : public OopClosure {
179 oop* _target;
180 bool _found;
181
182 public:
183 VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {}
184
185 void do_oop(oop* p) {
186 if (p == _target) {
187 _found = true;
188 }
189 }
190
191 void do_oop(narrowOop* p) {
192 // The ChunkedHandleList should not contain any narrowOop
193 ShouldNotReachHere();
194 }
195
196 bool found() const {
197 return _found;
198 }
199 };
200
201 bool ClassLoaderData::ChunkedHandleList::contains(oop* p) {
202 VerifyContainsOopClosure cl(p);
203 oops_do(&cl);
204 return cl.found();
205 }
206 #endif // ASSERT
207
208 bool ClassLoaderData::claim() {
209 if (_claimed == 1) {
210 return false;
211 }
212
213 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
214 }
215
216 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
217 // while the class is being parsed, and if the class appears on the module fixup list.
218 // Due to the uniqueness that no other class shares the anonymous class' name or
219 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
220 // it is being defined, therefore _keep_alive is not volatile or atomic.
221 void ClassLoaderData::inc_keep_alive() {
222 if (is_anonymous()) {
223 assert(_keep_alive >= 0, "Invalid keep alive increment count");
224 _keep_alive++;
225 }
226 }
227
228 void ClassLoaderData::dec_keep_alive() {
229 if (is_anonymous()) {
230 assert(_keep_alive > 0, "Invalid keep alive decrement count");
231 _keep_alive--;
232 }
233 }
234
235 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
236 if (must_claim && !claim()) {
237 return;
238 }
239
240 // Only clear modified_oops after the ClassLoaderData is claimed.
241 if (clear_mod_oops) {
242 clear_modified_oops();
243 }
244
245 f->do_oop(&_class_loader);
246 _dependencies.oops_do(f);
247 _handles.oops_do(f);
248 }
249
250 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
251 f->do_oop((oop*)&_list_head);
252 }
253
254 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
255 // Lock-free access requires load_acquire
256 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
257 klass_closure->do_klass(k);
258 assert(k != k->next_link(), "no loops!");
259 }
260 }
261
262 void ClassLoaderData::classes_do(void f(Klass * const)) {
263 // Lock-free access requires load_acquire
264 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
265 f(k);
266 assert(k != k->next_link(), "no loops!");
267 }
268 }
269
270 void ClassLoaderData::methods_do(void f(Method*)) {
271 // Lock-free access requires load_acquire
272 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
273 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
274 InstanceKlass::cast(k)->methods_do(f);
275 }
276 }
277 }
278
279 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
280 // Lock-free access requires load_acquire
281 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
282 // Do not filter ArrayKlass oops here...
283 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
284 klass_closure->do_klass(k);
285 }
286 }
287 }
288
289 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
290 // Lock-free access requires load_acquire
291 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
292 if (k->is_instance_klass()) {
293 f(InstanceKlass::cast(k));
294 }
295 assert(k != k->next_link(), "no loops!");
296 }
297 }
298
299 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
300 assert_locked_or_safepoint(Module_lock);
301 if (_unnamed_module != NULL) {
302 f(_unnamed_module);
303 }
304 if (_modules != NULL) {
305 for (int i = 0; i < _modules->table_size(); i++) {
306 for (ModuleEntry* entry = _modules->bucket(i);
307 entry != NULL;
308 entry = entry->next()) {
309 f(entry);
310 }
311 }
312 }
313 }
314
315 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
316 assert_locked_or_safepoint(Module_lock);
317 if (_packages != NULL) {
318 for (int i = 0; i < _packages->table_size(); i++) {
319 for (PackageEntry* entry = _packages->bucket(i);
320 entry != NULL;
321 entry = entry->next()) {
322 f(entry);
323 }
324 }
325 }
326 }
327
328 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
329 assert(k != NULL, "invariant");
330
331 ClassLoaderData * const from_cld = this;
332 ClassLoaderData * const to_cld = k->class_loader_data();
333
334 // Dependency to the null class loader data doesn't need to be recorded
335 // because the null class loader data never goes away.
336 if (to_cld->is_the_null_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
347 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
348 // we still have to add it. The class_loader won't keep from_cld alive.
349 if (!from_cld->is_anonymous()) {
350 // Check that this dependency isn't from the same or parent class_loader
351 oop from = from_cld->class_loader();
352
353 oop curr = from;
354 while (curr != NULL) {
355 if (curr == to) {
356 return; // this class loader is in the parent list, no need to add it.
357 }
358 curr = java_lang_ClassLoader::parent(curr);
359 }
360 }
361 }
362
363 // It's a dependency we won't find through GC, add it. This is relatively rare
364 // Must handle over GC point.
365 Handle dependency(THREAD, to);
366 from_cld->_dependencies.add(dependency, CHECK);
367
368 // Added a potentially young gen oop to the ClassLoaderData
369 record_modified_oops();
370 }
371
372
373 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
374 // Check first if this dependency is already in the list.
375 // Save a pointer to the last to add to under the lock.
376 objArrayOop ok = _list_head;
377 objArrayOop last = NULL;
378 while (ok != NULL) {
379 last = ok;
380 if (ok->obj_at(0) == dependency()) {
381 // Don't need to add it
382 return;
383 }
384 ok = (objArrayOop)ok->obj_at(1);
385 }
386
387 // Must handle over GC points
388 assert (last != NULL, "dependencies should be initialized");
389 objArrayHandle last_handle(THREAD, last);
390
391 // Create a new dependency node with fields for (class_loader or mirror, next)
392 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
393 deps->obj_at_put(0, dependency());
394
395 // Must handle over GC points
396 objArrayHandle new_dependency(THREAD, deps);
397
398 // Add the dependency under lock
399 locked_add(last_handle, new_dependency, THREAD);
400 }
401
402 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
403 objArrayHandle new_dependency,
404 Thread* THREAD) {
405
406 // Have to lock and put the new dependency on the end of the dependency
407 // array so the card mark for CMS sees that this dependency is new.
408 // Can probably do this lock free with some effort.
409 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
410
411 oop loader_or_mirror = new_dependency->obj_at(0);
412
413 // Since the dependencies are only added, add to the end.
414 objArrayOop end = last_handle();
415 objArrayOop last = NULL;
416 while (end != NULL) {
417 last = end;
418 // check again if another thread added it to the end.
419 if (end->obj_at(0) == loader_or_mirror) {
420 // Don't need to add it
421 return;
422 }
423 end = (objArrayOop)end->obj_at(1);
424 }
425 assert (last != NULL, "dependencies should be initialized");
426 // fill in the first element with the oop in new_dependency.
427 if (last->obj_at(0) == NULL) {
428 last->obj_at_put(0, new_dependency->obj_at(0));
429 } else {
430 last->obj_at_put(1, new_dependency());
431 }
432 }
433
434 void ClassLoaderDataGraph::clear_claimed_marks() {
435 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
436 cld->clear_claimed();
437 }
438 }
439
440 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
441 {
442 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
443 Klass* old_value = _klasses;
444 k->set_next_link(old_value);
445 // Link the new item into the list, making sure the linked class is stable
446 // since the list can be walked without a lock
447 OrderAccess::release_store(&_klasses, k);
448 }
449
450 if (publicize && k->class_loader_data() != NULL) {
451 ResourceMark rm;
452 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
453 PTR_FORMAT " loader: " PTR_FORMAT " %s",
454 p2i(k),
455 k->external_name(),
456 p2i(k->class_loader_data()),
457 p2i((void *)k->class_loader()),
458 loader_name());
459 }
460 }
461
462 // Class iterator used by the compiler. It gets some number of classes at
463 // a safepoint to decay invocation counters on the methods.
464 class ClassLoaderDataGraphKlassIteratorStatic {
465 ClassLoaderData* _current_loader_data;
466 Klass* _current_class_entry;
467 public:
468
469 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
470
471 InstanceKlass* try_get_next_class() {
472 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
473 int max_classes = InstanceKlass::number_of_instance_classes();
474 assert(max_classes > 0, "should not be called with no instance classes");
475 for (int i = 0; i < max_classes; ) {
476
477 if (_current_class_entry != NULL) {
478 Klass* k = _current_class_entry;
479 _current_class_entry = _current_class_entry->next_link();
480
481 if (k->is_instance_klass()) {
482 InstanceKlass* ik = InstanceKlass::cast(k);
483 i++; // count all instance classes found
484 // Not yet loaded classes are counted in max_classes
485 // but only return loaded classes.
486 if (ik->is_loaded()) {
487 return ik;
488 }
489 }
490 } else {
491 // Go to next CLD
492 if (_current_loader_data != NULL) {
493 _current_loader_data = _current_loader_data->next();
494 }
495 // Start at the beginning
496 if (_current_loader_data == NULL) {
497 _current_loader_data = ClassLoaderDataGraph::_head;
498 }
499
500 _current_class_entry = _current_loader_data->klasses();
501 }
502 }
503 // Should never be reached unless all instance classes have failed or are not fully loaded.
504 // Caller handles NULL.
505 return NULL;
506 }
507
508 // If the current class for the static iterator is a class being unloaded or
509 // deallocated, adjust the current class.
510 void adjust_saved_class(ClassLoaderData* cld) {
511 if (_current_loader_data == cld) {
512 _current_loader_data = cld->next();
513 if (_current_loader_data != NULL) {
514 _current_class_entry = _current_loader_data->klasses();
515 } // else try_get_next_class will start at the head
516 }
517 }
518
519 void adjust_saved_class(Klass* klass) {
520 if (_current_class_entry == klass) {
521 _current_class_entry = klass->next_link();
522 }
523 }
524 };
525
526 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
527
528 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
529 return static_klass_iterator.try_get_next_class();
530 }
531
532
533 // Remove a klass from the _klasses list for scratch_class during redefinition
534 // or parsed class in the case of an error.
535 void ClassLoaderData::remove_class(Klass* scratch_class) {
536 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
537
538 // Adjust global class iterator.
539 static_klass_iterator.adjust_saved_class(scratch_class);
540
541 Klass* prev = NULL;
542 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
543 if (k == scratch_class) {
544 if (prev == NULL) {
545 _klasses = k->next_link();
546 } else {
547 Klass* next = k->next_link();
548 prev->set_next_link(next);
549 }
550 return;
551 }
552 prev = k;
553 assert(k != k->next_link(), "no loops!");
554 }
555 ShouldNotReachHere(); // should have found this class!!
556 }
557
558 void ClassLoaderData::unload() {
559 _unloading = true;
560
561 // Tell serviceability tools these classes are unloading
562 classes_do(InstanceKlass::notify_unload_class);
563
564 LogTarget(Debug, class, loader, data) lt;
565 if (lt.is_enabled()) {
566 ResourceMark rm;
567 LogStream ls(lt);
568 ls.print(": unload loader data " INTPTR_FORMAT, p2i(this));
569 ls.print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
570 loader_name());
571 if (is_anonymous()) {
572 ls.print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
573 }
574 ls.cr();
575 }
576
577 // In some rare cases items added to this list will not be freed elsewhere.
578 // To keep it simple, just free everything in it here.
579 free_deallocate_list();
580
581 // Clean up global class iterator for compiler
582 static_klass_iterator.adjust_saved_class(this);
583 }
584
585 ModuleEntryTable* ClassLoaderData::modules() {
586 // Lazily create the module entry table at first request.
587 // Lock-free access requires load_acquire.
588 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
589 if (modules == NULL) {
590 MutexLocker m1(Module_lock);
591 // Check if _modules got allocated while we were waiting for this lock.
592 if ((modules = _modules) == NULL) {
593 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
594
595 {
596 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
597 // Ensure _modules is stable, since it is examined without a lock
598 OrderAccess::release_store(&_modules, modules);
599 }
600 }
601 }
602 return modules;
603 }
604
605 const int _boot_loader_dictionary_size = 1009;
606 const int _default_loader_dictionary_size = 107;
607 const int _prime_array_size = 8; // array of primes for system dictionary size
608 const int _average_depth_goal = 3; // goal for lookup length
609 const int _primelist[_prime_array_size] = {107, 1009, 2017, 4049, 5051, 10103, 20201, 40423};
610
611 // Calculate a "good" dictionary size based
612 // on predicted or current loaded classes count.
613 static int calculate_dictionary_size(int classcount) {
614 int newsize = _primelist[0];
615 if (classcount > 0 && !DumpSharedSpaces) {
616 int index = 0;
617 int desiredsize = classcount/_average_depth_goal;
618 for (newsize = _primelist[index]; index < _prime_array_size -1;
619 newsize = _primelist[++index]) {
620 if (desiredsize <= newsize) {
621 break;
622 }
623 }
624 }
625 return newsize;
626 }
627
628 Dictionary* ClassLoaderData::create_dictionary() {
629 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
630 int size;
631 if (_the_null_class_loader_data == NULL) {
632 size = _boot_loader_dictionary_size;
633 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
634 size = 1; // there's only one class in relection class loader and no initiated classes
635 } else if (is_system_class_loader_data()) {
636 size = calculate_dictionary_size(PredictedLoadedClassCount);
637 } else {
638 size = _default_loader_dictionary_size;
639 }
640 return new Dictionary(this, size);
641 }
642
643 // Unloading support
644 oop ClassLoaderData::keep_alive_object() const {
645 assert_locked_or_safepoint(_metaspace_lock);
646 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
647 return is_anonymous() ? _klasses->java_mirror() : class_loader();
648 }
649
650 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
651 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
652 || is_alive_closure->do_object_b(keep_alive_object());
653
654 return alive;
655 }
656
657 ClassLoaderData::~ClassLoaderData() {
658 // Release C heap structures for all the classes.
659 classes_do(InstanceKlass::release_C_heap_structures);
660
661 // Release C heap allocated hashtable for all the packages.
662 if (_packages != NULL) {
663 // Destroy the table itself
664 delete _packages;
665 _packages = NULL;
666 }
667
668 // Release C heap allocated hashtable for all the modules.
669 if (_modules != NULL) {
670 // Destroy the table itself
671 delete _modules;
672 _modules = NULL;
673 }
674
675 // Release C heap allocated hashtable for the dictionary
676 if (_dictionary != NULL) {
677 // Destroy the table itself
678 delete _dictionary;
679 _dictionary = NULL;
680 }
681
682 if (_unnamed_module != NULL) {
683 _unnamed_module->delete_unnamed_module();
684 _unnamed_module = NULL;
685 }
686
687 // release the metaspace
688 Metaspace *m = _metaspace;
689 if (m != NULL) {
690 _metaspace = NULL;
691 delete m;
692 }
693 // Clear all the JNI handles for methods
694 // These aren't deallocated and are going to look like a leak, but that's
695 // needed because we can't really get rid of jmethodIDs because we don't
696 // know when native code is going to stop using them. The spec says that
697 // they're "invalid" but existing programs likely rely on their being
698 // NULL after class unloading.
699 if (_jmethod_ids != NULL) {
700 Method::clear_jmethod_ids(this);
701 }
702 // Delete lock
703 delete _metaspace_lock;
704
705 // Delete free list
706 if (_deallocate_list != NULL) {
707 delete _deallocate_list;
708 }
709 }
710
711 // Returns true if this class loader data is for the system class loader.
712 bool ClassLoaderData::is_system_class_loader_data() const {
713 return SystemDictionary::is_system_class_loader(class_loader());
714 }
715
716 // Returns true if this class loader data is for the platform class loader.
717 bool ClassLoaderData::is_platform_class_loader_data() const {
718 return SystemDictionary::is_platform_class_loader(class_loader());
719 }
720
721 // Returns true if this class loader data is one of the 3 builtin
722 // (boot, application/system or platform) class loaders. Note, the
723 // builtin loaders are not freed by a GC.
724 bool ClassLoaderData::is_builtin_class_loader_data() const {
725 return (is_the_null_class_loader_data() ||
726 SystemDictionary::is_system_class_loader(class_loader()) ||
727 SystemDictionary::is_platform_class_loader(class_loader()));
728 }
729
730 Metaspace* ClassLoaderData::metaspace_non_null() {
731 // If the metaspace has not been allocated, create a new one. Might want
732 // to create smaller arena for Reflection class loaders also.
733 // The reason for the delayed allocation is because some class loaders are
734 // simply for delegating with no metadata of their own.
735 // Lock-free access requires load_acquire.
736 Metaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
737 if (metaspace == NULL) {
738 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
739 // Check if _metaspace got allocated while we were waiting for this lock.
740 if ((metaspace = _metaspace) == NULL) {
741 if (this == the_null_class_loader_data()) {
742 assert (class_loader() == NULL, "Must be");
743 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
744 } else if (is_anonymous()) {
745 if (class_loader() != NULL) {
746 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
747 }
748 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
749 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
750 if (class_loader() != NULL) {
751 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
752 }
753 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
754 } else {
755 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
756 }
757 // Ensure _metaspace is stable, since it is examined without a lock
758 OrderAccess::release_store(&_metaspace, metaspace);
759 }
760 }
761 return metaspace;
762 }
763
764 OopHandle ClassLoaderData::add_handle(Handle h) {
765 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
766 record_modified_oops();
767 return OopHandle(_handles.add(h()));
768 }
769
770 void ClassLoaderData::remove_handle(OopHandle h) {
771 oop* ptr = h.ptr_raw();
772 if (ptr != NULL) {
773 assert(_handles.contains(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
774 #if INCLUDE_ALL_GCS
775 // This barrier is used by G1 to remember the old oop values, so
776 // that we don't forget any objects that were live at the snapshot at
777 // the beginning.
778 if (UseG1GC) {
779 oop obj = *ptr;
780 if (obj != NULL) {
781 G1SATBCardTableModRefBS::enqueue(obj);
782 }
783 }
784 #endif
785 *ptr = NULL;
786 }
787 }
788
789 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
790 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
791 if (dest.resolve() != NULL) {
792 return;
793 } else {
794 dest = _handles.add(h());
795 }
796 }
797
798 // Add this metadata pointer to be freed when it's safe. This is only during
799 // class unloading because Handles might point to this metadata field.
800 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
801 // Metadata in shared region isn't deleted.
802 if (!m->is_shared()) {
803 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
804 if (_deallocate_list == NULL) {
805 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
806 }
807 _deallocate_list->append_if_missing(m);
808 }
809 }
810
811 // Deallocate free metadata on the free list. How useful the PermGen was!
812 void ClassLoaderData::free_deallocate_list() {
813 // Don't need lock, at safepoint
814 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
815 if (_deallocate_list == NULL) {
816 return;
817 }
818 // Go backwards because this removes entries that are freed.
819 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
820 Metadata* m = _deallocate_list->at(i);
821 if (!m->on_stack()) {
822 _deallocate_list->remove_at(i);
823 // There are only three types of metadata that we deallocate directly.
824 // Cast them so they can be used by the template function.
825 if (m->is_method()) {
826 MetadataFactory::free_metadata(this, (Method*)m);
827 } else if (m->is_constantPool()) {
828 MetadataFactory::free_metadata(this, (ConstantPool*)m);
829 } else if (m->is_klass()) {
830 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
831 } else {
832 ShouldNotReachHere();
833 }
834 } else {
835 // Metadata is alive.
836 // If scratch_class is on stack then it shouldn't be on this list!
837 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
838 "scratch classes on this list should be dead");
839 // Also should assert that other metadata on the list was found in handles.
840 }
841 }
842 }
843
844 // These anonymous class loaders are to contain classes used for JSR292
845 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
846 // Add a new class loader data to the graph.
847 Handle lh(THREAD, loader);
848 return ClassLoaderDataGraph::add(lh, true, THREAD);
849 }
850
851 const char* ClassLoaderData::loader_name() {
852 // Handles null class loader
853 return SystemDictionary::loader_name(class_loader());
854 }
855
856 #ifndef PRODUCT
857 // Define to dump klasses
858 #undef CLD_DUMP_KLASSES
859
860 void ClassLoaderData::dump(outputStream * const out) {
861 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
862 p2i(this), p2i((void *)class_loader()),
863 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
864 if (claimed()) out->print(" claimed ");
865 if (is_unloading()) out->print(" unloading ");
866 out->cr();
867 if (metaspace_or_null() != NULL) {
868 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
869 metaspace_or_null()->dump(out);
870 } else {
871 out->print_cr("metaspace: NULL");
872 }
873
874 #ifdef CLD_DUMP_KLASSES
875 if (Verbose) {
876 Klass* k = _klasses;
877 while (k != NULL) {
878 out->print_cr("klass " PTR_FORMAT ", %s", p2i(k), k->name()->as_C_string());
879 assert(k != k->next_link(), "no loops!");
880 k = k->next_link();
881 }
882 }
883 #endif // CLD_DUMP_KLASSES
884 #undef CLD_DUMP_KLASSES
885 if (_jmethod_ids != NULL) {
886 Method::print_jmethod_ids(this, out);
887 }
888 out->print_cr("}");
889 }
890 #endif // PRODUCT
891
892 void ClassLoaderData::verify() {
893 assert_locked_or_safepoint(_metaspace_lock);
894 oop cl = class_loader();
895
896 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
897 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
898
899 // Verify the integrity of the allocated space.
900 if (metaspace_or_null() != NULL) {
901 metaspace_or_null()->verify();
902 }
903
904 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
905 guarantee(k->class_loader_data() == this, "Must be the same");
906 k->verify();
907 assert(k != k->next_link(), "no loops!");
908 }
909 }
910
911 bool ClassLoaderData::contains_klass(Klass* klass) {
912 // Lock-free access requires load_acquire
913 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
914 if (k == klass) return true;
915 }
916 return false;
917 }
918
919
920 // GC root of class loader data created.
921 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
922 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
923 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
924 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
925
926 bool ClassLoaderDataGraph::_should_purge = false;
927 bool ClassLoaderDataGraph::_metaspace_oom = false;
928
929 // Add a new class loader data node to the list. Assign the newly created
930 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
931 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
932 // We need to allocate all the oops for the ClassLoaderData before allocating the
933 // actual ClassLoaderData object.
934 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
935
936 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
937 // ClassLoaderData in the graph since the CLD
938 // contains unhandled oops
939
940 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
941
942
943 if (!is_anonymous) {
944 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
945 // First, Atomically set it
946 ClassLoaderData* old = Atomic::cmpxchg(cld, cld_addr, (ClassLoaderData*)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 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
966 LogStream ls(lt);
967 print_creation(&ls, loader, cld, CHECK_NULL);
968 }
969 return cld;
970 }
971 next = exchanged;
972 } while (true);
973 }
974
975 void ClassLoaderDataGraph::print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS) {
976 Handle string;
977 if (loader.not_null()) {
978 // Include the result of loader.toString() in the output. This allows
979 // the user of the log to identify the class loader instance.
980 JavaValue result(T_OBJECT);
981 Klass* spec_klass = SystemDictionary::ClassLoader_klass();
982 JavaCalls::call_virtual(&result,
983 loader,
984 spec_klass,
985 vmSymbols::toString_name(),
986 vmSymbols::void_string_signature(),
987 CHECK);
988 assert(result.get_type() == T_OBJECT, "just checking");
989 string = Handle(THREAD, (oop)result.get_jobject());
990 }
991
992 ResourceMark rm;
993 out->print("create class loader data " INTPTR_FORMAT, p2i(cld));
994 out->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
995 cld->loader_name());
996
997 if (string.not_null()) {
998 out->print(": ");
999 java_lang_String::print(string(), out);
1000 }
1001 out->cr();
1002 }
1003
1004
1005 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1006 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1007 cld->oops_do(f, must_claim);
1008 }
1009 }
1010
1011 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1012 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1013 if (cld->keep_alive()) {
1014 cld->oops_do(f, must_claim);
1015 }
1016 }
1017 }
1018
1019 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1020 if (ClassUnloading) {
1021 keep_alive_oops_do(f, must_claim);
1022 } else {
1023 oops_do(f, must_claim);
1024 }
1025 }
1026
1027 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1028 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1029 cl->do_cld(cld);
1030 }
1031 }
1032
1033 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1034 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1035 // Only walk the head until any clds not purged from prior unloading
1036 // (CMS doesn't purge right away).
1037 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1038 assert(cld->is_unloading(), "invariant");
1039 cl->do_cld(cld);
1040 }
1041 }
1042
1043 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1044 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1045 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1046 if (closure != NULL) {
1047 closure->do_cld(cld);
1048 }
1049 }
1050 }
1051
1052 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1053 roots_cld_do(cl, NULL);
1054 }
1055
1056 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1057 if (ClassUnloading) {
1058 keep_alive_cld_do(cl);
1059 } else {
1060 cld_do(cl);
1061 }
1062 }
1063
1064 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1065 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1066 cld->classes_do(klass_closure);
1067 }
1068 }
1069
1070 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1071 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1072 cld->classes_do(f);
1073 }
1074 }
1075
1076 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1077 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1078 cld->methods_do(f);
1079 }
1080 }
1081
1082 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1083 assert_locked_or_safepoint(Module_lock);
1084 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1085 cld->modules_do(f);
1086 }
1087 }
1088
1089 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1090 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1091 // Only walk the head until any clds not purged from prior unloading
1092 // (CMS doesn't purge right away).
1093 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1094 assert(cld->is_unloading(), "invariant");
1095 cld->modules_do(f);
1096 }
1097 }
1098
1099 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1100 assert_locked_or_safepoint(Module_lock);
1101 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1102 cld->packages_do(f);
1103 }
1104 }
1105
1106 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1107 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1108 // Only walk the head until any clds not purged from prior unloading
1109 // (CMS doesn't purge right away).
1110 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1111 assert(cld->is_unloading(), "invariant");
1112 cld->packages_do(f);
1113 }
1114 }
1115
1116 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1117 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1118 cld->loaded_classes_do(klass_closure);
1119 }
1120 }
1121
1122 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1123 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1124 // Only walk the head until any clds not purged from prior unloading
1125 // (CMS doesn't purge right away).
1126 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1127 assert(cld->is_unloading(), "invariant");
1128 cld->classes_do(f);
1129 }
1130 }
1131
1132 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1133 if (X->dictionary() != NULL)
1134
1135 // Walk classes in the loaded class dictionaries in various forms.
1136 // Only walks the classes defined in this class loader.
1137 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1138 FOR_ALL_DICTIONARY(cld) {
1139 cld->dictionary()->classes_do(f);
1140 }
1141 }
1142
1143 // Only walks the classes defined in this class loader.
1144 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1145 FOR_ALL_DICTIONARY(cld) {
1146 cld->dictionary()->classes_do(f, CHECK);
1147 }
1148 }
1149
1150 // Walks all entries in the dictionary including entries initiated by this class loader.
1151 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1152 FOR_ALL_DICTIONARY(cld) {
1153 cld->dictionary()->all_entries_do(f);
1154 }
1155 }
1156
1157 void ClassLoaderDataGraph::verify_dictionary() {
1158 FOR_ALL_DICTIONARY(cld) {
1159 cld->dictionary()->verify();
1160 }
1161 }
1162
1163 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1164 FOR_ALL_DICTIONARY(cld) {
1165 st->print("Dictionary for ");
1166 cld->print_value_on(st);
1167 st->cr();
1168 cld->dictionary()->print_on(st);
1169 st->cr();
1170 }
1171 }
1172
1173 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1174 FOR_ALL_DICTIONARY(cld) {
1175 ResourceMark rm;
1176 stringStream tempst;
1177 tempst.print("System Dictionary for %s", cld->loader_name());
1178 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1179 }
1180 }
1181
1182 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1183 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1184
1185 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1186
1187 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1188 ClassLoaderData* curr = _head;
1189 while (curr != _saved_head) {
1190 if (!curr->claimed()) {
1191 array->push(curr);
1192 LogTarget(Debug, class, loader, data) lt;
1193 if (lt.is_enabled()) {
1194 LogStream ls(lt);
1195 ls.print("found new CLD: ");
1196 curr->print_value_on(&ls);
1197 ls.cr();
1198 }
1199 }
1200
1201 curr = curr->_next;
1202 }
1203
1204 return array;
1205 }
1206
1207 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
1208 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
1209 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
1210 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
1211 return true;
1212 }
1213 }
1214 return false;
1215 }
1216
1217 #ifndef PRODUCT
1218 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1219 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1220 if (loader_data == data) {
1221 return true;
1222 }
1223 }
1224
1225 return false;
1226 }
1227 #endif // PRODUCT
1228
1229
1230 // Move class loader data from main list to the unloaded list for unloading
1231 // and deallocation later.
1232 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1233 bool clean_previous_versions) {
1234
1235 ClassLoaderData* data = _head;
1236 ClassLoaderData* prev = NULL;
1237 bool seen_dead_loader = false;
1238
1239 // Mark metadata seen on the stack only so we can delete unneeded entries.
1240 // Only walk all metadata, including the expensive code cache walk, for Full GC
1241 // and only if class redefinition and if there's previous versions of
1242 // Klasses to delete.
1243 bool walk_all_metadata = clean_previous_versions &&
1244 JvmtiExport::has_redefined_a_class() &&
1245 InstanceKlass::has_previous_versions_and_reset();
1246 MetadataOnStackMark md_on_stack(walk_all_metadata);
1247
1248 // Save previous _unloading pointer for CMS which may add to unloading list before
1249 // purging and we don't want to rewalk the previously unloaded class loader data.
1250 _saved_unloading = _unloading;
1251
1252 data = _head;
1253 while (data != NULL) {
1254 if (data->is_alive(is_alive_closure)) {
1255 // clean metaspace
1256 if (walk_all_metadata) {
1257 data->classes_do(InstanceKlass::purge_previous_versions);
1258 }
1259 data->free_deallocate_list();
1260 prev = data;
1261 data = data->next();
1262 continue;
1263 }
1264 seen_dead_loader = true;
1265 ClassLoaderData* dead = data;
1266 dead->unload();
1267 data = data->next();
1268 // Remove from loader list.
1269 // This class loader data will no longer be found
1270 // in the ClassLoaderDataGraph.
1271 if (prev != NULL) {
1272 prev->set_next(data);
1273 } else {
1274 assert(dead == _head, "sanity check");
1275 _head = data;
1276 }
1277 dead->set_next(_unloading);
1278 _unloading = dead;
1279 }
1280
1281 if (seen_dead_loader) {
1282 data = _head;
1283 while (data != NULL) {
1284 // Remove entries in the dictionary of live class loader that have
1285 // initiated loading classes in a dead class loader.
1286 if (data->dictionary() != NULL) {
1287 data->dictionary()->do_unloading();
1288 }
1289 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1290 // lists to determine if there are modules on those lists that are now
1291 // dead and should be removed. A module's life cycle is equivalent
1292 // to its defining class loader's life cycle. Since a module is
1293 // considered dead if its class loader is dead, these walks must
1294 // occur after each class loader's aliveness is determined.
1295 if (data->packages() != NULL) {
1296 data->packages()->purge_all_package_exports();
1297 }
1298 if (data->modules_defined()) {
1299 data->modules()->purge_all_module_reads();
1300 }
1301 data = data->next();
1302 }
1303
1304 post_class_unload_events();
1305 }
1306
1307 return seen_dead_loader;
1308 }
1309
1310 void ClassLoaderDataGraph::purge() {
1311 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1312 ClassLoaderData* list = _unloading;
1313 _unloading = NULL;
1314 ClassLoaderData* next = list;
1315 bool classes_unloaded = false;
1316 while (next != NULL) {
1317 ClassLoaderData* purge_me = next;
1318 next = purge_me->next();
1319 delete purge_me;
1320 classes_unloaded = true;
1321 }
1322 if (classes_unloaded) {
1323 Metaspace::purge();
1324 set_metaspace_oom(false);
1325 }
1326 }
1327
1328 void ClassLoaderDataGraph::post_class_unload_events() {
1329 #if INCLUDE_TRACE
1330 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1331 if (Tracing::enabled()) {
1332 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1333 assert(_unloading != NULL, "need class loader data unload list!");
1334 _class_unload_time = Ticks::now();
1335 classes_unloading_do(&class_unload_event);
1336 }
1337 Tracing::on_unloading_classes();
1338 }
1339 #endif
1340 }
1341
1342 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1343 : _next_klass(NULL) {
1344 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1345 Klass* klass = NULL;
1346
1347 // Find the first klass in the CLDG.
1348 while (cld != NULL) {
1349 assert_locked_or_safepoint(cld->metaspace_lock());
1350 klass = cld->_klasses;
1351 if (klass != NULL) {
1352 _next_klass = klass;
1353 return;
1354 }
1355 cld = cld->next();
1356 }
1357 }
1358
1359 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1360 Klass* next = klass->next_link();
1361 if (next != NULL) {
1362 return next;
1363 }
1364
1365 // No more klasses in the current CLD. Time to find a new CLD.
1366 ClassLoaderData* cld = klass->class_loader_data();
1367 assert_locked_or_safepoint(cld->metaspace_lock());
1368 while (next == NULL) {
1369 cld = cld->next();
1370 if (cld == NULL) {
1371 break;
1372 }
1373 next = cld->_klasses;
1374 }
1375
1376 return next;
1377 }
1378
1379 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1380 Klass* head = _next_klass;
1381
1382 while (head != NULL) {
1383 Klass* next = next_klass_in_cldg(head);
1384
1385 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1386
1387 if (old_head == head) {
1388 return head; // Won the CAS.
1389 }
1390
1391 head = old_head;
1392 }
1393
1394 // Nothing more for the iterator to hand out.
1395 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1396 return NULL;
1397 }
1398
1399 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1400 _data = ClassLoaderDataGraph::_head;
1401 }
1402
1403 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1404
1405 #ifndef PRODUCT
1406 // callable from debugger
1407 extern "C" int print_loader_data_graph() {
1408 ClassLoaderDataGraph::dump_on(tty);
1409 return 0;
1410 }
1411
1412 void ClassLoaderDataGraph::verify() {
1413 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1414 data->verify();
1415 }
1416 }
1417
1418 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1419 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1420 data->dump(out);
1421 }
1422 MetaspaceAux::dump(out);
1423 }
1424 #endif // PRODUCT
1425
1426 void ClassLoaderData::print_value_on(outputStream* out) const {
1427 if (class_loader() == NULL) {
1428 out->print("NULL class loader");
1429 } else {
1430 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1431 class_loader()->print_value_on(out);
1432 }
1433 }
1434
1435 void ClassLoaderData::print_on(outputStream* out) const {
1436 if (class_loader() == NULL) {
1437 out->print("NULL class loader");
1438 } else {
1439 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1440 class_loader()->print_on(out);
1441 }
1442 }
1443
1444 #if INCLUDE_TRACE
1445
1446 Ticks ClassLoaderDataGraph::_class_unload_time;
1447
1448 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1449 assert(k != NULL, "invariant");
1450
1451 // post class unload event
1452 EventClassUnload event(UNTIMED);
1453 event.set_endtime(_class_unload_time);
1454 event.set_unloadedClass(k);
1455 event.set_definingClassLoader(k->class_loader_data());
1456 event.commit();
1457 }
1458
1459 #endif // INCLUDE_TRACE