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 "memory/metadataFactory.hpp"
62 #include "memory/metaspaceShared.hpp"
63 #include "memory/oopFactory.hpp"
64 #include "memory/resourceArea.hpp"
65 #include "oops/objArrayOop.inline.hpp"
66 #include "oops/oop.inline.hpp"
67 #include "runtime/atomic.hpp"
68 #include "runtime/javaCalls.hpp"
69 #include "runtime/jniHandles.hpp"
70 #include "runtime/mutex.hpp"
71 #include "runtime/orderAccess.hpp"
72 #include "runtime/safepoint.hpp"
73 #include "runtime/synchronizer.hpp"
74 #include "utilities/growableArray.hpp"
75 #include "utilities/macros.hpp"
76 #include "utilities/ostream.hpp"
77 #if INCLUDE_TRACE
78 #include "trace/tracing.hpp"
79 #endif
80
81 // helper function to avoid in-line casts
82 template <typename T> static T* load_ptr_acquire(T* volatile *p) {
83 return static_cast<T*>(OrderAccess::load_ptr_acquire(p));
84 }
85
86 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
87
88 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
89 _class_loader(h_class_loader()),
90 _is_anonymous(is_anonymous),
91 // An anonymous class loader data doesn't have anything to keep
92 // it from being unloaded during parsing of the anonymous class.
93 // The null-class-loader should always be kept alive.
94 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
95 _metaspace(NULL), _unloading(false), _klasses(NULL),
96 _modules(NULL), _packages(NULL),
97 _claimed(0), _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_ptr(&_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 = (Chunk*) OrderAccess::load_ptr_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
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, KlassClosure* klass_closure, bool must_claim) {
236 if (must_claim && !claim()) {
237 return;
238 }
239
240 f->do_oop(&_class_loader);
241 _dependencies.oops_do(f);
242
243 _handles.oops_do(f);
244
245 if (klass_closure != NULL) {
246 classes_do(klass_closure);
247 }
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_ptr_acquire
256 for (Klass* k = load_ptr_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_ptr_acquire
264 for (Klass* k = load_ptr_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_ptr_acquire
272 for (Klass* k = load_ptr_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_ptr_acquire
281 for (Klass* k = load_ptr_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_ptr_acquire
291 for (Klass* k = load_ptr_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
369
370 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
371 // Check first if this dependency is already in the list.
372 // Save a pointer to the last to add to under the lock.
373 objArrayOop ok = _list_head;
374 objArrayOop last = NULL;
375 while (ok != NULL) {
376 last = ok;
377 if (ok->obj_at(0) == dependency()) {
378 // Don't need to add it
379 return;
380 }
381 ok = (objArrayOop)ok->obj_at(1);
382 }
383
384 // Must handle over GC points
385 assert (last != NULL, "dependencies should be initialized");
386 objArrayHandle last_handle(THREAD, last);
387
388 // Create a new dependency node with fields for (class_loader or mirror, next)
389 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
390 deps->obj_at_put(0, dependency());
391
392 // Must handle over GC points
393 objArrayHandle new_dependency(THREAD, deps);
394
395 // Add the dependency under lock
396 locked_add(last_handle, new_dependency, THREAD);
397 }
398
399 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
400 objArrayHandle new_dependency,
401 Thread* THREAD) {
402
403 // Have to lock and put the new dependency on the end of the dependency
404 // array so the card mark for CMS sees that this dependency is new.
405 // Can probably do this lock free with some effort.
406 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
407
408 oop loader_or_mirror = new_dependency->obj_at(0);
409
410 // Since the dependencies are only added, add to the end.
411 objArrayOop end = last_handle();
412 objArrayOop last = NULL;
413 while (end != NULL) {
414 last = end;
415 // check again if another thread added it to the end.
416 if (end->obj_at(0) == loader_or_mirror) {
417 // Don't need to add it
418 return;
419 }
420 end = (objArrayOop)end->obj_at(1);
421 }
422 assert (last != NULL, "dependencies should be initialized");
423 // fill in the first element with the oop in new_dependency.
424 if (last->obj_at(0) == NULL) {
425 last->obj_at_put(0, new_dependency->obj_at(0));
426 } else {
427 last->obj_at_put(1, new_dependency());
428 }
429 }
430
431 void ClassLoaderDataGraph::clear_claimed_marks() {
432 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
433 cld->clear_claimed();
434 }
435 }
436
437 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
438 {
439 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
440 Klass* old_value = _klasses;
441 k->set_next_link(old_value);
442 // Link the new item into the list, making sure the linked class is stable
443 // since the list can be walked without a lock
444 OrderAccess::release_store_ptr(&_klasses, k);
445 }
446
447 if (publicize && k->class_loader_data() != NULL) {
448 ResourceMark rm;
449 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
450 PTR_FORMAT " loader: " PTR_FORMAT " %s",
451 p2i(k),
452 k->external_name(),
453 p2i(k->class_loader_data()),
454 p2i((void *)k->class_loader()),
455 loader_name());
456 }
457 }
458
459 // Class iterator used by the compiler. It gets some number of classes at
460 // a safepoint to decay invocation counters on the methods.
461 class ClassLoaderDataGraphKlassIteratorStatic {
462 ClassLoaderData* _current_loader_data;
463 Klass* _current_class_entry;
464 public:
465
466 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
467
468 InstanceKlass* try_get_next_class() {
469 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
470 while (true) {
471
472 if (_current_class_entry != NULL) {
473 Klass* k = _current_class_entry;
474 _current_class_entry = _current_class_entry->next_link();
475
476 if (k->is_instance_klass()) {
477 InstanceKlass* ik = InstanceKlass::cast(k);
478 // Only return loaded classes
479 if (ik->is_loaded()) {
480 return ik;
481 }
482 }
483 } else {
484 // Go to next CLD
485 if (_current_loader_data != NULL) {
486 _current_loader_data = _current_loader_data->next();
487 }
488 // Start at the beginning
489 if (_current_loader_data == NULL) {
490 _current_loader_data = ClassLoaderDataGraph::_head;
491 }
492
493 _current_class_entry = _current_loader_data->klasses();
494 }
495 }
496 // never reached: an InstanceKlass should be returned above
497 }
498
499 // If the current class for the static iterator is a class being unloaded or
500 // deallocated, adjust the current class.
501 void adjust_saved_class(ClassLoaderData* cld) {
502 if (_current_loader_data == cld) {
503 _current_loader_data = cld->next();
504 if (_current_loader_data != NULL) {
505 _current_class_entry = _current_loader_data->klasses();
506 } // else try_get_next_class will start at the head
507 }
508 }
509
510 void adjust_saved_class(Klass* klass) {
511 if (_current_class_entry == klass) {
512 _current_class_entry = klass->next_link();
513 }
514 }
515 };
516
517 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
518
519 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
520 return static_klass_iterator.try_get_next_class();
521 }
522
523
524 // Remove a klass from the _klasses list for scratch_class during redefinition
525 // or parsed class in the case of an error.
526 void ClassLoaderData::remove_class(Klass* scratch_class) {
527 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
528
529 // Adjust global class iterator.
530 static_klass_iterator.adjust_saved_class(scratch_class);
531
532 Klass* prev = NULL;
533 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
534 if (k == scratch_class) {
535 if (prev == NULL) {
536 _klasses = k->next_link();
537 } else {
538 Klass* next = k->next_link();
539 prev->set_next_link(next);
540 }
541 return;
542 }
543 prev = k;
544 assert(k != k->next_link(), "no loops!");
545 }
546 ShouldNotReachHere(); // should have found this class!!
547 }
548
549 void ClassLoaderData::unload() {
550 _unloading = true;
551
552 // Tell serviceability tools these classes are unloading
553 classes_do(InstanceKlass::notify_unload_class);
554
555 if (log_is_enabled(Debug, class, loader, data)) {
556 ResourceMark rm;
557 outputStream* log = Log(class, loader, data)::debug_stream();
558 log->print(": unload loader data " INTPTR_FORMAT, p2i(this));
559 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
560 loader_name());
561 if (is_anonymous()) {
562 log->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
563 }
564 log->cr();
565 }
566
567 // In some rare cases items added to this list will not be freed elsewhere.
568 // To keep it simple, just free everything in it here.
569 free_deallocate_list();
570
571 // Clean up global class iterator for compiler
572 static_klass_iterator.adjust_saved_class(this);
573 }
574
575 ModuleEntryTable* ClassLoaderData::modules() {
576 // Lazily create the module entry table at first request.
577 // Lock-free access requires load_ptr_acquire.
578 ModuleEntryTable* modules = load_ptr_acquire(&_modules);
579 if (modules == NULL) {
580 MutexLocker m1(Module_lock);
581 // Check if _modules got allocated while we were waiting for this lock.
582 if ((modules = _modules) == NULL) {
583 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
584
585 {
586 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
587 // Ensure _modules is stable, since it is examined without a lock
588 OrderAccess::release_store_ptr(&_modules, modules);
589 }
590 }
591 }
592 return modules;
593 }
594
595 const int _boot_loader_dictionary_size = 1009;
596 const int _prime_array_size = 8; // array of primes for system dictionary size
597 const int _average_depth_goal = 3; // goal for lookup length
598 const int _primelist[_prime_array_size] = {107, 1009, 2017, 4049, 5051, 10103, 20201, 40423};
599
600 // Calculate a "good" dictionary size based
601 // on predicted or current loaded classes count *per class loader*
602 // This size will be used for all class loaders if specified,
603 // except boot loader and reflection class loaders
604 static int calculate_dictionary_size(int classcount) {
605 static int newsize = 0; // only calculate once
606 if (newsize != 0) {
607 return newsize;
608 }
609 newsize = _primelist[0];
610 if (classcount > 0 && !DumpSharedSpaces) {
611 int index = 0;
612 int desiredsize = classcount/_average_depth_goal;
613 for (newsize = _primelist[index]; index < _prime_array_size -1;
614 newsize = _primelist[++index]) {
615 if (desiredsize <= newsize) {
616 break;
617 }
618 }
619 }
620 return newsize;
621 }
622
623 Dictionary* ClassLoaderData::create_dictionary() {
624 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
625 int size;
626 if (_the_null_class_loader_data == NULL) {
627 size = _boot_loader_dictionary_size;
628 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
629 size = 1; // there's only one class in relection class loader and no initiated classes
630 } else {
631 size = calculate_dictionary_size(PredictedLoadedClassCount);
632 }
633 return new Dictionary(this, size);
634 }
635
636 // Unloading support
637 oop ClassLoaderData::keep_alive_object() const {
638 assert_locked_or_safepoint(_metaspace_lock);
639 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
640 return is_anonymous() ? _klasses->java_mirror() : class_loader();
641 }
642
643 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
644 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
645 || is_alive_closure->do_object_b(keep_alive_object());
646
647 return alive;
648 }
649
650 ClassLoaderData::~ClassLoaderData() {
651 // Release C heap structures for all the classes.
652 classes_do(InstanceKlass::release_C_heap_structures);
653
654 // Release C heap allocated hashtable for all the packages.
655 if (_packages != NULL) {
656 // Destroy the table itself
657 delete _packages;
658 _packages = NULL;
659 }
660
661 // Release C heap allocated hashtable for all the modules.
662 if (_modules != NULL) {
663 // Destroy the table itself
664 delete _modules;
665 _modules = NULL;
666 }
667
668 // Release C heap allocated hashtable for the dictionary
669 if (_dictionary != NULL) {
670 // Destroy the table itself
671 delete _dictionary;
672 _dictionary = NULL;
673 }
674
675 if (_unnamed_module != NULL) {
676 _unnamed_module->delete_unnamed_module();
677 _unnamed_module = NULL;
678 }
679
680 // release the metaspace
681 Metaspace *m = _metaspace;
682 if (m != NULL) {
683 _metaspace = NULL;
684 delete m;
685 }
686 // Clear all the JNI handles for methods
687 // These aren't deallocated and are going to look like a leak, but that's
688 // needed because we can't really get rid of jmethodIDs because we don't
689 // know when native code is going to stop using them. The spec says that
690 // they're "invalid" but existing programs likely rely on their being
691 // NULL after class unloading.
692 if (_jmethod_ids != NULL) {
693 Method::clear_jmethod_ids(this);
694 }
695 // Delete lock
696 delete _metaspace_lock;
697
698 // Delete free list
699 if (_deallocate_list != NULL) {
700 delete _deallocate_list;
701 }
702 }
703
704 // Returns true if this class loader data is for the system class loader.
705 bool ClassLoaderData::is_system_class_loader_data() const {
706 return SystemDictionary::is_system_class_loader(class_loader());
707 }
708
709 // Returns true if this class loader data is for the platform class loader.
710 bool ClassLoaderData::is_platform_class_loader_data() const {
711 return SystemDictionary::is_platform_class_loader(class_loader());
712 }
713
714 // Returns true if this class loader data is one of the 3 builtin
715 // (boot, application/system or platform) class loaders. Note, the
716 // builtin loaders are not freed by a GC.
717 bool ClassLoaderData::is_builtin_class_loader_data() const {
718 return (is_the_null_class_loader_data() ||
719 SystemDictionary::is_system_class_loader(class_loader()) ||
720 SystemDictionary::is_platform_class_loader(class_loader()));
721 }
722
723 Metaspace* ClassLoaderData::metaspace_non_null() {
724 assert(!DumpSharedSpaces, "wrong metaspace!");
725 // If the metaspace has not been allocated, create a new one. Might want
726 // to create smaller arena for Reflection class loaders also.
727 // The reason for the delayed allocation is because some class loaders are
728 // simply for delegating with no metadata of their own.
729 // Lock-free access requires load_ptr_acquire.
730 Metaspace* metaspace = load_ptr_acquire(&_metaspace);
731 if (metaspace == NULL) {
732 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
733 // Check if _metaspace got allocated while we were waiting for this lock.
734 if ((metaspace = _metaspace) == NULL) {
735 if (this == the_null_class_loader_data()) {
736 assert (class_loader() == NULL, "Must be");
737 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
738 } else if (is_anonymous()) {
739 if (class_loader() != NULL) {
740 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
741 }
742 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
743 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
744 if (class_loader() != NULL) {
745 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
746 }
747 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
748 } else {
749 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
750 }
751 // Ensure _metaspace is stable, since it is examined without a lock
752 OrderAccess::release_store_ptr(&_metaspace, metaspace);
753 }
754 }
755 return metaspace;
756 }
757
758 jobject ClassLoaderData::add_handle(Handle h) {
759 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
760 return (jobject) _handles.add(h());
761 }
762
763 void ClassLoaderData::remove_handle_unsafe(jobject h) {
764 assert(_handles.contains((oop*) h), "Got unexpected handle " PTR_FORMAT, p2i((oop*) h));
765 *((oop*) h) = NULL;
766 }
767
768 // Add this metadata pointer to be freed when it's safe. This is only during
769 // class unloading because Handles might point to this metadata field.
770 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
771 // Metadata in shared region isn't deleted.
772 if (!m->is_shared()) {
773 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
774 if (_deallocate_list == NULL) {
775 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
776 }
777 _deallocate_list->append_if_missing(m);
778 }
779 }
780
781 // Deallocate free metadata on the free list. How useful the PermGen was!
782 void ClassLoaderData::free_deallocate_list() {
783 // Don't need lock, at safepoint
784 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
785 if (_deallocate_list == NULL) {
786 return;
787 }
788 // Go backwards because this removes entries that are freed.
789 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
790 Metadata* m = _deallocate_list->at(i);
791 if (!m->on_stack()) {
792 _deallocate_list->remove_at(i);
793 // There are only three types of metadata that we deallocate directly.
794 // Cast them so they can be used by the template function.
795 if (m->is_method()) {
796 MetadataFactory::free_metadata(this, (Method*)m);
797 } else if (m->is_constantPool()) {
798 MetadataFactory::free_metadata(this, (ConstantPool*)m);
799 } else if (m->is_klass()) {
800 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
801 } else {
802 ShouldNotReachHere();
803 }
804 } else {
805 // Metadata is alive.
806 // If scratch_class is on stack then it shouldn't be on this list!
807 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
808 "scratch classes on this list should be dead");
809 // Also should assert that other metadata on the list was found in handles.
810 }
811 }
812 }
813
814 // These anonymous class loaders are to contain classes used for JSR292
815 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
816 // Add a new class loader data to the graph.
817 Handle lh(THREAD, loader);
818 return ClassLoaderDataGraph::add(lh, true, THREAD);
819 }
820
821 const char* ClassLoaderData::loader_name() {
822 // Handles null class loader
823 return SystemDictionary::loader_name(class_loader());
824 }
825
826 #ifndef PRODUCT
827 // Define to dump klasses
828 #undef CLD_DUMP_KLASSES
829
830 void ClassLoaderData::dump(outputStream * const out) {
831 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
832 p2i(this), p2i((void *)class_loader()),
833 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
834 if (claimed()) out->print(" claimed ");
835 if (is_unloading()) out->print(" unloading ");
836 out->cr();
837 if (metaspace_or_null() != NULL) {
838 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
839 metaspace_or_null()->dump(out);
840 } else {
841 out->print_cr("metaspace: NULL");
842 }
843
844 #ifdef CLD_DUMP_KLASSES
845 if (Verbose) {
846 Klass* k = _klasses;
847 while (k != NULL) {
848 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
849 k->has_modified_oops(), k->has_accumulated_modified_oops());
850 assert(k != k->next_link(), "no loops!");
851 k = k->next_link();
852 }
853 }
854 #endif // CLD_DUMP_KLASSES
855 #undef CLD_DUMP_KLASSES
856 if (_jmethod_ids != NULL) {
857 Method::print_jmethod_ids(this, out);
858 }
859 out->print_cr("}");
860 }
861 #endif // PRODUCT
862
863 void ClassLoaderData::verify() {
864 assert_locked_or_safepoint(_metaspace_lock);
865 oop cl = class_loader();
866
867 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
868 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
869
870 // Verify the integrity of the allocated space.
871 if (metaspace_or_null() != NULL) {
872 metaspace_or_null()->verify();
873 }
874
875 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
876 guarantee(k->class_loader_data() == this, "Must be the same");
877 k->verify();
878 assert(k != k->next_link(), "no loops!");
879 }
880 }
881
882 bool ClassLoaderData::contains_klass(Klass* klass) {
883 // Lock-free access requires load_ptr_acquire
884 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
885 if (k == klass) return true;
886 }
887 return false;
888 }
889
890
891 // GC root of class loader data created.
892 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
893 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
894 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
895 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
896
897 bool ClassLoaderDataGraph::_should_purge = false;
898 bool ClassLoaderDataGraph::_metaspace_oom = false;
899
900 // Add a new class loader data node to the list. Assign the newly created
901 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
902 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
903 // We need to allocate all the oops for the ClassLoaderData before allocating the
904 // actual ClassLoaderData object.
905 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
906
907 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
908 // ClassLoaderData in the graph since the CLD
909 // contains unhandled oops
910
911 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
912
913
914 if (!is_anonymous) {
915 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
916 // First, Atomically set it
917 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
918 if (old != NULL) {
919 delete cld;
920 // Returns the data.
921 return old;
922 }
923 }
924
925 // We won the race, and therefore the task of adding the data to the list of
926 // class loader data
927 ClassLoaderData** list_head = &_head;
928 ClassLoaderData* next = _head;
929
930 do {
931 cld->set_next(next);
932 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
933 if (exchanged == next) {
934 if (log_is_enabled(Debug, class, loader, data)) {
935 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
936 log_creation(loader, cld, CHECK_NULL);
937 }
938 return cld;
939 }
940 next = exchanged;
941 } while (true);
942 }
943
944 void ClassLoaderDataGraph::log_creation(Handle loader, ClassLoaderData* cld, TRAPS) {
945 Handle string;
946 if (loader.not_null()) {
947 // Include the result of loader.toString() in the output. This allows
948 // the user of the log to identify the class loader instance.
949 JavaValue result(T_OBJECT);
950 Klass* spec_klass = SystemDictionary::ClassLoader_klass();
951 JavaCalls::call_virtual(&result,
952 loader,
953 spec_klass,
954 vmSymbols::toString_name(),
955 vmSymbols::void_string_signature(),
956 CHECK);
957 assert(result.get_type() == T_OBJECT, "just checking");
958 string = Handle(THREAD, (oop)result.get_jobject());
959 }
960
961 ResourceMark rm;
962 outputStream* log = Log(class, loader, data)::debug_stream();
963 log->print("create class loader data " INTPTR_FORMAT, p2i(cld));
964 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
965 cld->loader_name());
966
967 if (string.not_null()) {
968 log->print(": ");
969 java_lang_String::print(string(), log);
970 }
971 log->cr();
972 }
973
974
975 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
976 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
977 cld->oops_do(f, klass_closure, must_claim);
978 }
979 }
980
981 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
982 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
983 if (cld->keep_alive()) {
984 cld->oops_do(f, klass_closure, must_claim);
985 }
986 }
987 }
988
989 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
990 if (ClassUnloading) {
991 keep_alive_oops_do(f, klass_closure, must_claim);
992 } else {
993 oops_do(f, klass_closure, must_claim);
994 }
995 }
996
997 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
998 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
999 cl->do_cld(cld);
1000 }
1001 }
1002
1003 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1004 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1005 // Only walk the head until any clds not purged from prior unloading
1006 // (CMS doesn't purge right away).
1007 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1008 assert(cld->is_unloading(), "invariant");
1009 cl->do_cld(cld);
1010 }
1011 }
1012
1013 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1014 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1015 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1016 if (closure != NULL) {
1017 closure->do_cld(cld);
1018 }
1019 }
1020 }
1021
1022 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1023 roots_cld_do(cl, NULL);
1024 }
1025
1026 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1027 if (ClassUnloading) {
1028 keep_alive_cld_do(cl);
1029 } else {
1030 cld_do(cl);
1031 }
1032 }
1033
1034 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1035 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1036 cld->classes_do(klass_closure);
1037 }
1038 }
1039
1040 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1041 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1042 cld->classes_do(f);
1043 }
1044 }
1045
1046 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1047 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1048 cld->methods_do(f);
1049 }
1050 }
1051
1052 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1053 assert_locked_or_safepoint(Module_lock);
1054 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1055 cld->modules_do(f);
1056 }
1057 }
1058
1059 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1060 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1061 // Only walk the head until any clds not purged from prior unloading
1062 // (CMS doesn't purge right away).
1063 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1064 assert(cld->is_unloading(), "invariant");
1065 cld->modules_do(f);
1066 }
1067 }
1068
1069 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1070 assert_locked_or_safepoint(Module_lock);
1071 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1072 cld->packages_do(f);
1073 }
1074 }
1075
1076 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1077 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1078 // Only walk the head until any clds not purged from prior unloading
1079 // (CMS doesn't purge right away).
1080 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1081 assert(cld->is_unloading(), "invariant");
1082 cld->packages_do(f);
1083 }
1084 }
1085
1086 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1087 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1088 cld->loaded_classes_do(klass_closure);
1089 }
1090 }
1091
1092 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1093 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1094 // Only walk the head until any clds not purged from prior unloading
1095 // (CMS doesn't purge right away).
1096 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1097 assert(cld->is_unloading(), "invariant");
1098 cld->classes_do(f);
1099 }
1100 }
1101
1102 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1103 if (X->dictionary() != NULL)
1104
1105 // Walk classes in the loaded class dictionaries in various forms.
1106 // Only walks the classes defined in this class loader.
1107 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1108 FOR_ALL_DICTIONARY(cld) {
1109 cld->dictionary()->classes_do(f);
1110 }
1111 }
1112
1113 // Only walks the classes defined in this class loader.
1114 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1115 FOR_ALL_DICTIONARY(cld) {
1116 cld->dictionary()->classes_do(f, CHECK);
1117 }
1118 }
1119
1120 // Walks all entries in the dictionary including entries initiated by this class loader.
1121 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1122 FOR_ALL_DICTIONARY(cld) {
1123 cld->dictionary()->all_entries_do(f);
1124 }
1125 }
1126
1127 void ClassLoaderDataGraph::verify_dictionary() {
1128 FOR_ALL_DICTIONARY(cld) {
1129 cld->dictionary()->verify();
1130 }
1131 }
1132
1133 void ClassLoaderDataGraph::print_dictionary(bool details) {
1134 FOR_ALL_DICTIONARY(cld) {
1135 tty->print("Dictionary for class loader ");
1136 cld->print_value();
1137 tty->cr();
1138 cld->dictionary()->print(details);
1139 }
1140 }
1141
1142 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1143 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1144
1145 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1146
1147 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1148 ClassLoaderData* curr = _head;
1149 while (curr != _saved_head) {
1150 if (!curr->claimed()) {
1151 array->push(curr);
1152
1153 if (log_is_enabled(Debug, class, loader, data)) {
1154 outputStream* log = Log(class, loader, data)::debug_stream();
1155 log->print("found new CLD: ");
1156 curr->print_value_on(log);
1157 log->cr();
1158 }
1159 }
1160
1161 curr = curr->_next;
1162 }
1163
1164 return array;
1165 }
1166
1167 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
1168 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
1169 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
1170 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
1171 return true;
1172 }
1173 }
1174 return false;
1175 }
1176
1177 #ifndef PRODUCT
1178 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1179 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1180 if (loader_data == data) {
1181 return true;
1182 }
1183 }
1184
1185 return false;
1186 }
1187 #endif // PRODUCT
1188
1189
1190 // Move class loader data from main list to the unloaded list for unloading
1191 // and deallocation later.
1192 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1193 bool clean_previous_versions) {
1194
1195 ClassLoaderData* data = _head;
1196 ClassLoaderData* prev = NULL;
1197 bool seen_dead_loader = false;
1198
1199 // Mark metadata seen on the stack only so we can delete unneeded entries.
1200 // Only walk all metadata, including the expensive code cache walk, for Full GC
1201 // and only if class redefinition and if there's previous versions of
1202 // Klasses to delete.
1203 bool walk_all_metadata = clean_previous_versions &&
1204 JvmtiExport::has_redefined_a_class() &&
1205 InstanceKlass::has_previous_versions_and_reset();
1206 MetadataOnStackMark md_on_stack(walk_all_metadata);
1207
1208 // Save previous _unloading pointer for CMS which may add to unloading list before
1209 // purging and we don't want to rewalk the previously unloaded class loader data.
1210 _saved_unloading = _unloading;
1211
1212 data = _head;
1213 while (data != NULL) {
1214 if (data->is_alive(is_alive_closure)) {
1215 // clean metaspace
1216 if (walk_all_metadata) {
1217 data->classes_do(InstanceKlass::purge_previous_versions);
1218 }
1219 data->free_deallocate_list();
1220 prev = data;
1221 data = data->next();
1222 continue;
1223 }
1224 seen_dead_loader = true;
1225 ClassLoaderData* dead = data;
1226 dead->unload();
1227 data = data->next();
1228 // Remove from loader list.
1229 // This class loader data will no longer be found
1230 // in the ClassLoaderDataGraph.
1231 if (prev != NULL) {
1232 prev->set_next(data);
1233 } else {
1234 assert(dead == _head, "sanity check");
1235 _head = data;
1236 }
1237 dead->set_next(_unloading);
1238 _unloading = dead;
1239 }
1240
1241 if (seen_dead_loader) {
1242 data = _head;
1243 while (data != NULL) {
1244 // Remove entries in the dictionary of live class loader that have
1245 // initiated loading classes in a dead class loader.
1246 if (data->dictionary() != NULL) {
1247 data->dictionary()->do_unloading();
1248 }
1249 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1250 // lists to determine if there are modules on those lists that are now
1251 // dead and should be removed. A module's life cycle is equivalent
1252 // to its defining class loader's life cycle. Since a module is
1253 // considered dead if its class loader is dead, these walks must
1254 // occur after each class loader's aliveness is determined.
1255 if (data->packages() != NULL) {
1256 data->packages()->purge_all_package_exports();
1257 }
1258 if (data->modules_defined()) {
1259 data->modules()->purge_all_module_reads();
1260 }
1261 data = data->next();
1262 }
1263
1264 post_class_unload_events();
1265 }
1266
1267 return seen_dead_loader;
1268 }
1269
1270 void ClassLoaderDataGraph::purge() {
1271 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1272 ClassLoaderData* list = _unloading;
1273 _unloading = NULL;
1274 ClassLoaderData* next = list;
1275 bool classes_unloaded = false;
1276 while (next != NULL) {
1277 ClassLoaderData* purge_me = next;
1278 next = purge_me->next();
1279 delete purge_me;
1280 classes_unloaded = true;
1281 }
1282 if (classes_unloaded) {
1283 Metaspace::purge();
1284 set_metaspace_oom(false);
1285 }
1286 }
1287
1288 void ClassLoaderDataGraph::post_class_unload_events() {
1289 #if INCLUDE_TRACE
1290 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1291 if (Tracing::enabled()) {
1292 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1293 assert(_unloading != NULL, "need class loader data unload list!");
1294 _class_unload_time = Ticks::now();
1295 classes_unloading_do(&class_unload_event);
1296 }
1297 Tracing::on_unloading_classes();
1298 }
1299 #endif
1300 }
1301
1302 // CDS support
1303
1304 // Global metaspaces for writing information to the shared archive. When
1305 // application CDS is supported, we may need one per metaspace, so this
1306 // sort of looks like it.
1307 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
1308 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
1309 static bool _shared_metaspaces_initialized = false;
1310
1311 // Initialize shared metaspaces (change to call from somewhere not lazily)
1312 void ClassLoaderData::initialize_shared_metaspaces() {
1313 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
1314 assert(this == ClassLoaderData::the_null_class_loader_data(),
1315 "only supported for null loader data for now");
1316 assert (!_shared_metaspaces_initialized, "only initialize once");
1317 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
1318 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
1319 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
1320 _shared_metaspaces_initialized = true;
1321 }
1322
1323 Metaspace* ClassLoaderData::ro_metaspace() {
1324 assert(_ro_metaspace != NULL, "should already be initialized");
1325 return _ro_metaspace;
1326 }
1327
1328 Metaspace* ClassLoaderData::rw_metaspace() {
1329 assert(_rw_metaspace != NULL, "should already be initialized");
1330 return _rw_metaspace;
1331 }
1332
1333 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1334 : _next_klass(NULL) {
1335 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1336 Klass* klass = NULL;
1337
1338 // Find the first klass in the CLDG.
1339 while (cld != NULL) {
1340 assert_locked_or_safepoint(cld->metaspace_lock());
1341 klass = cld->_klasses;
1342 if (klass != NULL) {
1343 _next_klass = klass;
1344 return;
1345 }
1346 cld = cld->next();
1347 }
1348 }
1349
1350 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1351 Klass* next = klass->next_link();
1352 if (next != NULL) {
1353 return next;
1354 }
1355
1356 // No more klasses in the current CLD. Time to find a new CLD.
1357 ClassLoaderData* cld = klass->class_loader_data();
1358 assert_locked_or_safepoint(cld->metaspace_lock());
1359 while (next == NULL) {
1360 cld = cld->next();
1361 if (cld == NULL) {
1362 break;
1363 }
1364 next = cld->_klasses;
1365 }
1366
1367 return next;
1368 }
1369
1370 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1371 Klass* head = _next_klass;
1372
1373 while (head != NULL) {
1374 Klass* next = next_klass_in_cldg(head);
1375
1376 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
1377
1378 if (old_head == head) {
1379 return head; // Won the CAS.
1380 }
1381
1382 head = old_head;
1383 }
1384
1385 // Nothing more for the iterator to hand out.
1386 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1387 return NULL;
1388 }
1389
1390 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1391 _data = ClassLoaderDataGraph::_head;
1392 }
1393
1394 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1395
1396 #ifndef PRODUCT
1397 // callable from debugger
1398 extern "C" int print_loader_data_graph() {
1399 ClassLoaderDataGraph::dump_on(tty);
1400 return 0;
1401 }
1402
1403 void ClassLoaderDataGraph::verify() {
1404 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1405 data->verify();
1406 }
1407 }
1408
1409 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1410 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1411 data->dump(out);
1412 }
1413 MetaspaceAux::dump(out);
1414 }
1415 #endif // PRODUCT
1416
1417 void ClassLoaderData::print_value_on(outputStream* out) const {
1418 if (class_loader() == NULL) {
1419 out->print("NULL class_loader");
1420 } else {
1421 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1422 class_loader()->print_value_on(out);
1423 }
1424 }
1425
1426 void ClassLoaderData::print_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_on(out);
1432 }
1433 }
1434
1435 #if INCLUDE_TRACE
1436
1437 Ticks ClassLoaderDataGraph::_class_unload_time;
1438
1439 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1440 assert(k != NULL, "invariant");
1441
1442 // post class unload event
1443 EventClassUnload event(UNTIMED);
1444 event.set_endtime(_class_unload_time);
1445 event.set_unloadedClass(k);
1446 event.set_definingClassLoader(k->class_loader_data());
1447 event.commit();
1448 }
1449
1450 #endif // INCLUDE_TRACE