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), _dictionary(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 TRACE_INIT_ID(this);
118 }
119
120 void ClassLoaderData::init_dependencies(TRAPS) {
121 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
122 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
123 _dependencies.init(CHECK);
124 }
125
126 void ClassLoaderData::Dependencies::init(TRAPS) {
127 // Create empty dependencies array to add to. CMS requires this to be
128 // an oop so that it can track additions via card marks. We think.
129 _list_head = oopFactory::new_objectArray(2, CHECK);
130 }
131
132 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
133 Chunk* c = _head;
134 while (c != NULL) {
135 Chunk* next = c->_next;
136 delete c;
137 c = next;
138 }
139 }
140
141 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
142 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
143 Chunk* next = new Chunk(_head);
144 OrderAccess::release_store_ptr(&_head, next);
145 }
146 oop* handle = &_head->_data[_head->_size];
147 *handle = o;
148 OrderAccess::release_store(&_head->_size, _head->_size + 1);
149 return handle;
150 }
151
152 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
153 for (juint i = 0; i < size; i++) {
154 if (c->_data[i] != NULL) {
155 f->do_oop(&c->_data[i]);
156 }
157 }
158 }
159
160 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
161 Chunk* head = (Chunk*) OrderAccess::load_ptr_acquire(&_head);
162 if (head != NULL) {
163 // Must be careful when reading size of head
164 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
165 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
166 oops_do_chunk(f, c, c->_size);
167 }
168 }
169 }
170
171 #ifdef ASSERT
172 class VerifyContainsOopClosure : public OopClosure {
173 oop* _target;
174 bool _found;
175
176 public:
177 VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {}
178
179 void do_oop(oop* p) {
180 if (p == _target) {
181 _found = true;
182 }
183 }
184
185 void do_oop(narrowOop* p) {
186 // The ChunkedHandleList should not contain any narrowOop
187 ShouldNotReachHere();
188 }
189
190 bool found() const {
191 return _found;
192 }
193 };
194
195 bool ClassLoaderData::ChunkedHandleList::contains(oop* p) {
196 VerifyContainsOopClosure cl(p);
197 oops_do(&cl);
198 return cl.found();
199 }
200 #endif
201
202 bool ClassLoaderData::claim() {
203 if (_claimed == 1) {
204 return false;
205 }
206
207 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
208 }
209
210 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
211 // while the class is being parsed, and if the class appears on the module fixup list.
212 // Due to the uniqueness that no other class shares the anonymous class' name or
213 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
214 // it is being defined, therefore _keep_alive is not volatile or atomic.
215 void ClassLoaderData::inc_keep_alive() {
216 if (is_anonymous()) {
217 assert(_keep_alive >= 0, "Invalid keep alive increment count");
218 _keep_alive++;
219 }
220 }
221
222 void ClassLoaderData::dec_keep_alive() {
223 if (is_anonymous()) {
224 assert(_keep_alive > 0, "Invalid keep alive decrement count");
225 _keep_alive--;
226 }
227 }
228
229 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
230 if (must_claim && !claim()) {
231 return;
232 }
233
234 f->do_oop(&_class_loader);
235 _dependencies.oops_do(f);
236
237 _handles.oops_do(f);
238
239 if (klass_closure != NULL) {
240 classes_do(klass_closure);
241 }
242 }
243
244 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
245 f->do_oop((oop*)&_list_head);
246 }
247
248 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
249 // Lock-free access requires load_ptr_acquire
250 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
251 klass_closure->do_klass(k);
252 assert(k != k->next_link(), "no loops!");
253 }
254 }
255
256 void ClassLoaderData::classes_do(void f(Klass * const)) {
257 // Lock-free access requires load_ptr_acquire
258 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
259 f(k);
260 assert(k != k->next_link(), "no loops!");
261 }
262 }
263
264 void ClassLoaderData::methods_do(void f(Method*)) {
265 // Lock-free access requires load_ptr_acquire
266 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
267 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
268 InstanceKlass::cast(k)->methods_do(f);
269 }
270 }
271 }
272
273 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
274 // Lock-free access requires load_ptr_acquire
275 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
276 // Do not filter ArrayKlass oops here...
277 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
278 klass_closure->do_klass(k);
279 }
280 }
281 }
282
283 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
284 // Lock-free access requires load_ptr_acquire
285 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
286 if (k->is_instance_klass()) {
287 f(InstanceKlass::cast(k));
288 }
289 assert(k != k->next_link(), "no loops!");
290 }
291 }
292
293 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
294 assert_locked_or_safepoint(Module_lock);
295 if (_unnamed_module != NULL) {
296 f(_unnamed_module);
297 }
298 if (_modules != NULL) {
299 for (int i = 0; i < _modules->table_size(); i++) {
300 for (ModuleEntry* entry = _modules->bucket(i);
301 entry != NULL;
302 entry = entry->next()) {
303 f(entry);
304 }
305 }
306 }
307 }
308
309 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
310 assert_locked_or_safepoint(Module_lock);
311 if (_packages != NULL) {
312 for (int i = 0; i < _packages->table_size(); i++) {
313 for (PackageEntry* entry = _packages->bucket(i);
314 entry != NULL;
315 entry = entry->next()) {
316 f(entry);
317 }
318 }
319 }
320 }
321
322 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
323 assert(k != NULL, "invariant");
324
325 ClassLoaderData * const from_cld = this;
326 ClassLoaderData * const to_cld = k->class_loader_data();
327
328 // Dependency to the null class loader data doesn't need to be recorded
329 // because the null class loader data never goes away.
330 if (to_cld->is_the_null_class_loader_data()) {
331 return;
332 }
333
334 oop to;
335 if (to_cld->is_anonymous()) {
336 // Anonymous class dependencies are through the mirror.
337 to = k->java_mirror();
338 } else {
339 to = to_cld->class_loader();
340
341 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
342 // we still have to add it. The class_loader won't keep from_cld alive.
343 if (!from_cld->is_anonymous()) {
344 // Check that this dependency isn't from the same or parent class_loader
345 oop from = from_cld->class_loader();
346
347 oop curr = from;
348 while (curr != NULL) {
349 if (curr == to) {
350 return; // this class loader is in the parent list, no need to add it.
351 }
352 curr = java_lang_ClassLoader::parent(curr);
353 }
354 }
355 }
356
357 // It's a dependency we won't find through GC, add it. This is relatively rare
358 // Must handle over GC point.
359 Handle dependency(THREAD, to);
360 from_cld->_dependencies.add(dependency, CHECK);
361 }
362
363
364 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
365 // Check first if this dependency is already in the list.
366 // Save a pointer to the last to add to under the lock.
367 objArrayOop ok = _list_head;
368 objArrayOop last = NULL;
369 while (ok != NULL) {
370 last = ok;
371 if (ok->obj_at(0) == dependency()) {
372 // Don't need to add it
373 return;
374 }
375 ok = (objArrayOop)ok->obj_at(1);
376 }
377
378 // Must handle over GC points
379 assert (last != NULL, "dependencies should be initialized");
380 objArrayHandle last_handle(THREAD, last);
381
382 // Create a new dependency node with fields for (class_loader or mirror, next)
383 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
384 deps->obj_at_put(0, dependency());
385
386 // Must handle over GC points
387 objArrayHandle new_dependency(THREAD, deps);
388
389 // Add the dependency under lock
390 locked_add(last_handle, new_dependency, THREAD);
391 }
392
393 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
394 objArrayHandle new_dependency,
395 Thread* THREAD) {
396
397 // Have to lock and put the new dependency on the end of the dependency
398 // array so the card mark for CMS sees that this dependency is new.
399 // Can probably do this lock free with some effort.
400 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
401
402 oop loader_or_mirror = new_dependency->obj_at(0);
403
404 // Since the dependencies are only added, add to the end.
405 objArrayOop end = last_handle();
406 objArrayOop last = NULL;
407 while (end != NULL) {
408 last = end;
409 // check again if another thread added it to the end.
410 if (end->obj_at(0) == loader_or_mirror) {
411 // Don't need to add it
412 return;
413 }
414 end = (objArrayOop)end->obj_at(1);
415 }
416 assert (last != NULL, "dependencies should be initialized");
417 // fill in the first element with the oop in new_dependency.
418 if (last->obj_at(0) == NULL) {
419 last->obj_at_put(0, new_dependency->obj_at(0));
420 } else {
421 last->obj_at_put(1, new_dependency());
422 }
423 }
424
425 void ClassLoaderDataGraph::clear_claimed_marks() {
426 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
427 cld->clear_claimed();
428 }
429 }
430
431 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
432 {
433 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
434 Klass* old_value = _klasses;
435 k->set_next_link(old_value);
436 // Link the new item into the list, making sure the linked class is stable
437 // since the list can be walked without a lock
438 OrderAccess::release_store_ptr(&_klasses, k);
439 }
440
441 if (publicize && k->class_loader_data() != NULL) {
442 ResourceMark rm;
443 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
444 PTR_FORMAT " loader: " PTR_FORMAT " %s",
445 p2i(k),
446 k->external_name(),
447 p2i(k->class_loader_data()),
448 p2i((void *)k->class_loader()),
449 loader_name());
450 }
451 }
452
453 // Class iterator used by the compiler. It gets some number of classes at
454 // a safepoint to decay invocation counters on the methods.
455 class ClassLoaderDataGraphKlassIteratorStatic {
456 ClassLoaderData* _current_loader_data = NULL;
457 Klass* _current_class_entry = NULL;
458 public:
459
460 InstanceKlass* try_get_next_class() {
461 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
462 while (true) {
463
464 if (_current_class_entry != NULL) {
465 Klass* k = _current_class_entry;
466 _current_class_entry = _current_class_entry->next_link();
467
468 if (k->is_instance_klass()) {
469 InstanceKlass* ik = InstanceKlass::cast(k);
470 // Only return loaded classes
471 if (ik->is_loaded()) {
472 return ik;
473 }
474 }
475 } else {
476 // Go to next CLD
477 if (_current_loader_data != NULL) {
478 _current_loader_data = _current_loader_data->next();
479 }
480 // Start at the beginning
481 if (_current_loader_data == NULL) {
482 _current_loader_data = ClassLoaderDataGraph::_head;
483 }
484
485 _current_class_entry = _current_loader_data->klasses();
486 }
487 }
488 // never reached: an InstanceKlass should be returned above
489 }
490
491 // If the current class for the static iterator is a class being unloaded or
492 // deallocated, adjust the current class.
493 void adjust_saved_class(ClassLoaderData* cld) {
494 if (_current_loader_data == cld) {
495 _current_loader_data = cld->next();
496 if (_current_loader_data != NULL) {
497 _current_class_entry = _current_loader_data->klasses();
498 } // else try_get_next_class will start at the head
499 }
500 }
501
502 void adjust_saved_class(Klass* klass) {
503 if (_current_class_entry == klass) {
504 _current_class_entry = klass->next_link();
505 }
506 }
507 };
508
509 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
510
511 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
512 return static_klass_iterator.try_get_next_class();
513 }
514
515
516 // Remove a klass from the _klasses list for scratch_class during redefinition
517 // or parsed class in the case of an error.
518 void ClassLoaderData::remove_class(Klass* scratch_class) {
519 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
520
521 // Adjust global class iterator.
522 static_klass_iterator.adjust_saved_class(scratch_class);
523
524 Klass* prev = NULL;
525 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
526 if (k == scratch_class) {
527 if (prev == NULL) {
528 _klasses = k->next_link();
529 } else {
530 Klass* next = k->next_link();
531 prev->set_next_link(next);
532 }
533 return;
534 }
535 prev = k;
536 assert(k != k->next_link(), "no loops!");
537 }
538 ShouldNotReachHere(); // should have found this class!!
539 }
540
541 void ClassLoaderData::unload() {
542 _unloading = true;
543
544 // Tell serviceability tools these classes are unloading
545 classes_do(InstanceKlass::notify_unload_class);
546
547 if (log_is_enabled(Debug, class, loader, data)) {
548 ResourceMark rm;
549 outputStream* log = Log(class, loader, data)::debug_stream();
550 log->print(": unload loader data " INTPTR_FORMAT, p2i(this));
551 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
552 loader_name());
553 if (is_anonymous()) {
554 log->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
555 }
556 log->cr();
557 }
558
559 // In some rare cases items added to this list will not be freed elsewhere.
560 // To keep it simple, just free everything in it here.
561 free_deallocate_list();
562
563 // Clean up global class iterator for compiler
564 static_klass_iterator.adjust_saved_class(this);
565 }
566
567 ModuleEntryTable* ClassLoaderData::modules() {
568 // Lazily create the module entry table at first request.
569 // Lock-free access requires load_ptr_acquire.
570 ModuleEntryTable* modules = load_ptr_acquire(&_modules);
571 if (modules == NULL) {
572 MutexLocker m1(Module_lock);
573 // Check if _modules got allocated while we were waiting for this lock.
574 if ((modules = _modules) == NULL) {
575 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
576
577 {
578 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
579 // Ensure _modules is stable, since it is examined without a lock
580 OrderAccess::release_store_ptr(&_modules, modules);
581 }
582 }
583 }
584 return modules;
585 }
586
587 const int _boot_loader_dictionary_size = 1009;
588 const int _prime_array_size = 8; // array of primes for system dictionary size
589 const int _average_depth_goal = 3; // goal for lookup length
590 const int _primelist[_prime_array_size] = {107, 1009, 2017, 4049, 5051, 10103, 20201, 40423};
591
592 // Calculate a "good" dictionary size based
593 // on predicted or current loaded classes count *per class loader*
594 // This size will be used for all class loaders if specified,
595 // except boot loader and reflection class loaders
596 static int calculate_dictionary_size(int classcount) {
597 static int newsize = 0; // only calculate once
598 if (newsize != 0) {
599 return newsize;
600 }
601 newsize = _primelist[0];
602 if (classcount > 0 && !DumpSharedSpaces) {
603 int index = 0;
604 int desiredsize = classcount/_average_depth_goal;
605 for (newsize = _primelist[index]; index < _prime_array_size -1;
606 newsize = _primelist[++index]) {
607 if (desiredsize <= newsize) {
608 break;
609 }
610 }
611 }
612 return newsize;
613 }
614
615 Dictionary* ClassLoaderData::dictionary_or_null() {
616 return load_ptr_acquire(&_dictionary);
617 }
618
619 Dictionary* ClassLoaderData::dictionary() {
620 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
621 // Lazily create the dictionary, in the same way of lazily creating modules.
622 // Lock-free access requires load_ptr_acquire.
623 Dictionary* dictionary = load_ptr_acquire(&_dictionary);
624 if (dictionary == NULL) {
625 MutexLocker m1(SystemDictionary_lock);
626 // Check if _dictionary got allocated while we were waiting for this lock.
627 if ((dictionary = _dictionary) == NULL) {
628 int size;
629 if (this == the_null_class_loader_data()) {
630 size = _boot_loader_dictionary_size;
631 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
632 size = 1; // there's only one class in relection class loader and no initiated classes
633 } else {
634 size = calculate_dictionary_size(PredictedLoadedClassCount);
635 }
636 dictionary = new Dictionary(this, size);
637 // Ensure _dictionary is stable, since it is examined without a lock.
638 // Don't need metaspace_lock since SystemDictionary_lock is held.
639 OrderAccess::release_store_ptr(&_dictionary, dictionary);
640 }
641 }
642 return dictionary;
643 }
644
645 // Unloading support
646 oop ClassLoaderData::keep_alive_object() const {
647 assert_locked_or_safepoint(_metaspace_lock);
648 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
649 return is_anonymous() ? _klasses->java_mirror() : class_loader();
650 }
651
652 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
653 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
654 || is_alive_closure->do_object_b(keep_alive_object());
655
656 return alive;
657 }
658
659 ClassLoaderData::~ClassLoaderData() {
660 // Release C heap structures for all the classes.
661 classes_do(InstanceKlass::release_C_heap_structures);
662
663 // Release C heap allocated hashtable for all the packages.
664 if (_packages != NULL) {
665 // Destroy the table itself
666 delete _packages;
667 _packages = NULL;
668 }
669
670 // Release C heap allocated hashtable for all the modules.
671 if (_modules != NULL) {
672 // Destroy the table itself
673 delete _modules;
674 _modules = NULL;
675 }
676
677 // Release C heap allocated hashtable for the dictionary
678 if (_dictionary != NULL) {
679 // Destroy the table itself
680 delete _dictionary;
681 _dictionary = NULL;
682 }
683
684 if (_unnamed_module != NULL) {
685 _unnamed_module->delete_unnamed_module();
686 _unnamed_module = NULL;
687 }
688
689 // release the metaspace
690 Metaspace *m = _metaspace;
691 if (m != NULL) {
692 _metaspace = NULL;
693 delete m;
694 }
695 // Clear all the JNI handles for methods
696 // These aren't deallocated and are going to look like a leak, but that's
697 // needed because we can't really get rid of jmethodIDs because we don't
698 // know when native code is going to stop using them. The spec says that
699 // they're "invalid" but existing programs likely rely on their being
700 // NULL after class unloading.
701 if (_jmethod_ids != NULL) {
702 Method::clear_jmethod_ids(this);
703 }
704 // Delete lock
705 delete _metaspace_lock;
706
707 // Delete free list
708 if (_deallocate_list != NULL) {
709 delete _deallocate_list;
710 }
711 }
712
713 // Returns true if this class loader data is for the system class loader.
714 bool ClassLoaderData::is_system_class_loader_data() const {
715 return SystemDictionary::is_system_class_loader(class_loader());
716 }
717
718 // Returns true if this class loader data is for the platform class loader.
719 bool ClassLoaderData::is_platform_class_loader_data() const {
720 return SystemDictionary::is_platform_class_loader(class_loader());
721 }
722
723 // Returns true if this class loader data is one of the 3 builtin
724 // (boot, application/system or platform) class loaders. Note, the
725 // builtin loaders are not freed by a GC.
726 bool ClassLoaderData::is_builtin_class_loader_data() const {
727 return (is_the_null_class_loader_data() ||
728 SystemDictionary::is_system_class_loader(class_loader()) ||
729 SystemDictionary::is_platform_class_loader(class_loader()));
730 }
731
732 Metaspace* ClassLoaderData::metaspace_non_null() {
733 assert(!DumpSharedSpaces, "wrong metaspace!");
734 // If the metaspace has not been allocated, create a new one. Might want
735 // to create smaller arena for Reflection class loaders also.
736 // The reason for the delayed allocation is because some class loaders are
737 // simply for delegating with no metadata of their own.
738 // Lock-free access requires load_ptr_acquire.
739 Metaspace* metaspace = load_ptr_acquire(&_metaspace);
740 if (metaspace == NULL) {
741 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
742 // Check if _metaspace got allocated while we were waiting for this lock.
743 if ((metaspace = _metaspace) == NULL) {
744 if (this == the_null_class_loader_data()) {
745 assert (class_loader() == NULL, "Must be");
746 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
747 } else if (is_anonymous()) {
748 if (class_loader() != NULL) {
749 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
750 }
751 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
752 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
753 if (class_loader() != NULL) {
754 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
755 }
756 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
757 } else {
758 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
759 }
760 // Ensure _metaspace is stable, since it is examined without a lock
761 OrderAccess::release_store_ptr(&_metaspace, metaspace);
762 }
763 }
764 return metaspace;
765 }
766
767 jobject ClassLoaderData::add_handle(Handle h) {
768 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
769 return (jobject) _handles.add(h());
770 }
771
772 void ClassLoaderData::remove_handle_unsafe(jobject h) {
773 assert(_handles.contains((oop*) h), "Got unexpected handle " PTR_FORMAT, p2i((oop*) h));
774 *((oop*) h) = NULL;
775 }
776
777 // Add this metadata pointer to be freed when it's safe. This is only during
778 // class unloading because Handles might point to this metadata field.
779 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
780 // Metadata in shared region isn't deleted.
781 if (!m->is_shared()) {
782 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
783 if (_deallocate_list == NULL) {
784 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
785 }
786 _deallocate_list->append_if_missing(m);
787 }
788 }
789
790 // Deallocate free metadata on the free list. How useful the PermGen was!
791 void ClassLoaderData::free_deallocate_list() {
792 // Don't need lock, at safepoint
793 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
794 if (_deallocate_list == NULL) {
795 return;
796 }
797 // Go backwards because this removes entries that are freed.
798 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
799 Metadata* m = _deallocate_list->at(i);
800 if (!m->on_stack()) {
801 _deallocate_list->remove_at(i);
802 // There are only three types of metadata that we deallocate directly.
803 // Cast them so they can be used by the template function.
804 if (m->is_method()) {
805 MetadataFactory::free_metadata(this, (Method*)m);
806 } else if (m->is_constantPool()) {
807 MetadataFactory::free_metadata(this, (ConstantPool*)m);
808 } else if (m->is_klass()) {
809 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
810 } else {
811 ShouldNotReachHere();
812 }
813 } else {
814 // Metadata is alive.
815 // If scratch_class is on stack then it shouldn't be on this list!
816 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
817 "scratch classes on this list should be dead");
818 // Also should assert that other metadata on the list was found in handles.
819 }
820 }
821 }
822
823 // These anonymous class loaders are to contain classes used for JSR292
824 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
825 // Add a new class loader data to the graph.
826 Handle lh(THREAD, loader);
827 return ClassLoaderDataGraph::add(lh, true, THREAD);
828 }
829
830 const char* ClassLoaderData::loader_name() {
831 // Handles null class loader
832 return SystemDictionary::loader_name(class_loader());
833 }
834
835 #ifndef PRODUCT
836 // Define to dump klasses
837 #undef CLD_DUMP_KLASSES
838
839 void ClassLoaderData::dump(outputStream * const out) {
840 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
841 p2i(this), p2i((void *)class_loader()),
842 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
843 if (claimed()) out->print(" claimed ");
844 if (is_unloading()) out->print(" unloading ");
845 out->cr();
846 if (metaspace_or_null() != NULL) {
847 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
848 metaspace_or_null()->dump(out);
849 } else {
850 out->print_cr("metaspace: NULL");
851 }
852
853 #ifdef CLD_DUMP_KLASSES
854 if (Verbose) {
855 Klass* k = _klasses;
856 while (k != NULL) {
857 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
858 k->has_modified_oops(), k->has_accumulated_modified_oops());
859 assert(k != k->next_link(), "no loops!");
860 k = k->next_link();
861 }
862 }
863 #endif // CLD_DUMP_KLASSES
864 #undef CLD_DUMP_KLASSES
865 if (_jmethod_ids != NULL) {
866 Method::print_jmethod_ids(this, out);
867 }
868 out->print_cr("}");
869 }
870 #endif // PRODUCT
871
872 void ClassLoaderData::verify() {
873 assert_locked_or_safepoint(_metaspace_lock);
874 oop cl = class_loader();
875
876 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
877 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
878
879 // Verify the integrity of the allocated space.
880 if (metaspace_or_null() != NULL) {
881 metaspace_or_null()->verify();
882 }
883
884 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
885 guarantee(k->class_loader_data() == this, "Must be the same");
886 k->verify();
887 assert(k != k->next_link(), "no loops!");
888 }
889 }
890
891 bool ClassLoaderData::contains_klass(Klass* klass) {
892 // Lock-free access requires load_ptr_acquire
893 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
894 if (k == klass) return true;
895 }
896 return false;
897 }
898
899
900 // GC root of class loader data created.
901 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
902 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
903 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
904 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
905
906 bool ClassLoaderDataGraph::_should_purge = false;
907 bool ClassLoaderDataGraph::_metaspace_oom = false;
908
909 // Add a new class loader data node to the list. Assign the newly created
910 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
911 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
912 // We need to allocate all the oops for the ClassLoaderData before allocating the
913 // actual ClassLoaderData object.
914 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
915
916 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
917 // ClassLoaderData in the graph since the CLD
918 // contains unhandled oops
919
920 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
921
922
923 if (!is_anonymous) {
924 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
925 // First, Atomically set it
926 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
927 if (old != NULL) {
928 delete cld;
929 // Returns the data.
930 return old;
931 }
932 }
933
934 // We won the race, and therefore the task of adding the data to the list of
935 // class loader data
936 ClassLoaderData** list_head = &_head;
937 ClassLoaderData* next = _head;
938
939 do {
940 cld->set_next(next);
941 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
942 if (exchanged == next) {
943 if (log_is_enabled(Debug, class, loader, data)) {
944 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
945 log_creation(loader, cld, CHECK_NULL);
946 }
947 return cld;
948 }
949 next = exchanged;
950 } while (true);
951 }
952
953 void ClassLoaderDataGraph::log_creation(Handle loader, ClassLoaderData* cld, TRAPS) {
954 Handle string;
955 if (loader.not_null()) {
956 // Include the result of loader.toString() in the output. This allows
957 // the user of the log to identify the class loader instance.
958 JavaValue result(T_OBJECT);
959 Klass* spec_klass = SystemDictionary::ClassLoader_klass();
960 JavaCalls::call_virtual(&result,
961 loader,
962 spec_klass,
963 vmSymbols::toString_name(),
964 vmSymbols::void_string_signature(),
965 CHECK);
966 assert(result.get_type() == T_OBJECT, "just checking");
967 string = Handle(THREAD, (oop)result.get_jobject());
968 }
969
970 ResourceMark rm;
971 outputStream* log = Log(class, loader, data)::debug_stream();
972 log->print("create class loader data " INTPTR_FORMAT, p2i(cld));
973 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
974 cld->loader_name());
975
976 if (string.not_null()) {
977 log->print(": ");
978 java_lang_String::print(string(), log);
979 }
980 log->cr();
981 }
982
983
984 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
985 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
986 cld->oops_do(f, klass_closure, must_claim);
987 }
988 }
989
990 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
991 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
992 if (cld->keep_alive()) {
993 cld->oops_do(f, klass_closure, must_claim);
994 }
995 }
996 }
997
998 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
999 if (ClassUnloading) {
1000 keep_alive_oops_do(f, klass_closure, must_claim);
1001 } else {
1002 oops_do(f, klass_closure, must_claim);
1003 }
1004 }
1005
1006 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1007 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1008 cl->do_cld(cld);
1009 }
1010 }
1011
1012 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1013 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1014 // Only walk the head until any clds not purged from prior unloading
1015 // (CMS doesn't purge right away).
1016 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1017 assert(cld->is_unloading(), "invariant");
1018 cl->do_cld(cld);
1019 }
1020 }
1021
1022 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1023 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1024 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1025 if (closure != NULL) {
1026 closure->do_cld(cld);
1027 }
1028 }
1029 }
1030
1031 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1032 roots_cld_do(cl, NULL);
1033 }
1034
1035 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1036 if (ClassUnloading) {
1037 keep_alive_cld_do(cl);
1038 } else {
1039 cld_do(cl);
1040 }
1041 }
1042
1043 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1044 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1045 cld->classes_do(klass_closure);
1046 }
1047 }
1048
1049 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1050 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1051 cld->classes_do(f);
1052 }
1053 }
1054
1055 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1056 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1057 cld->methods_do(f);
1058 }
1059 }
1060
1061 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1062 assert_locked_or_safepoint(Module_lock);
1063 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1064 cld->modules_do(f);
1065 }
1066 }
1067
1068 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1069 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1070 // Only walk the head until any clds not purged from prior unloading
1071 // (CMS doesn't purge right away).
1072 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1073 assert(cld->is_unloading(), "invariant");
1074 cld->modules_do(f);
1075 }
1076 }
1077
1078 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1079 assert_locked_or_safepoint(Module_lock);
1080 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1081 cld->packages_do(f);
1082 }
1083 }
1084
1085 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1086 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1087 // Only walk the head until any clds not purged from prior unloading
1088 // (CMS doesn't purge right away).
1089 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1090 assert(cld->is_unloading(), "invariant");
1091 cld->packages_do(f);
1092 }
1093 }
1094
1095 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1096 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1097 cld->loaded_classes_do(klass_closure);
1098 }
1099 }
1100
1101 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1102 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1103 // Only walk the head until any clds not purged from prior unloading
1104 // (CMS doesn't purge right away).
1105 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1106 assert(cld->is_unloading(), "invariant");
1107 cld->classes_do(f);
1108 }
1109 }
1110
1111 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1112 if (X->dictionary_or_null() != NULL)
1113
1114 // Walk classes in the loaded class dictionaries in various forms.
1115 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1116 FOR_ALL_DICTIONARY(cld) {
1117 cld->dictionary()->classes_do(f);
1118 }
1119 }
1120
1121 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1122 FOR_ALL_DICTIONARY(cld) {
1123 cld->dictionary()->classes_do(f, CHECK);
1124 }
1125 }
1126
1127 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1128 FOR_ALL_DICTIONARY(cld) {
1129 cld->dictionary()->all_entries_do(f);
1130 }
1131 }
1132
1133 void ClassLoaderDataGraph::verify_dictionary() {
1134 FOR_ALL_DICTIONARY(cld) {
1135 cld->dictionary()->verify();
1136 }
1137 }
1138
1139 void ClassLoaderDataGraph::print_dictionary(bool details) {
1140 FOR_ALL_DICTIONARY(cld) {
1141 tty->print("Dictionary for class loader ");
1142 cld->print_value();
1143 tty->cr();
1144 cld->dictionary()->print(details);
1145 }
1146 }
1147
1148 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1149 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1150
1151 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1152
1153 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1154 ClassLoaderData* curr = _head;
1155 while (curr != _saved_head) {
1156 if (!curr->claimed()) {
1157 array->push(curr);
1158
1159 if (log_is_enabled(Debug, class, loader, data)) {
1160 outputStream* log = Log(class, loader, data)::debug_stream();
1161 log->print("found new CLD: ");
1162 curr->print_value_on(log);
1163 log->cr();
1164 }
1165 }
1166
1167 curr = curr->_next;
1168 }
1169
1170 return array;
1171 }
1172
1173 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
1174 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
1175 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
1176 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
1177 return true;
1178 }
1179 }
1180 return false;
1181 }
1182
1183 #ifndef PRODUCT
1184 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1185 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1186 if (loader_data == data) {
1187 return true;
1188 }
1189 }
1190
1191 return false;
1192 }
1193 #endif // PRODUCT
1194
1195
1196 // Move class loader data from main list to the unloaded list for unloading
1197 // and deallocation later.
1198 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1199 bool clean_previous_versions) {
1200
1201 ClassLoaderData* data = _head;
1202 ClassLoaderData* prev = NULL;
1203 bool seen_dead_loader = false;
1204
1205 // Mark metadata seen on the stack only so we can delete unneeded entries.
1206 // Only walk all metadata, including the expensive code cache walk, for Full GC
1207 // and only if class redefinition and if there's previous versions of
1208 // Klasses to delete.
1209 bool walk_all_metadata = clean_previous_versions &&
1210 JvmtiExport::has_redefined_a_class() &&
1211 InstanceKlass::has_previous_versions_and_reset();
1212 MetadataOnStackMark md_on_stack(walk_all_metadata);
1213
1214 // Save previous _unloading pointer for CMS which may add to unloading list before
1215 // purging and we don't want to rewalk the previously unloaded class loader data.
1216 _saved_unloading = _unloading;
1217
1218 data = _head;
1219 while (data != NULL) {
1220 if (data->is_alive(is_alive_closure)) {
1221 // clean metaspace
1222 if (walk_all_metadata) {
1223 data->classes_do(InstanceKlass::purge_previous_versions);
1224 }
1225 data->free_deallocate_list();
1226 prev = data;
1227 data = data->next();
1228 continue;
1229 }
1230 seen_dead_loader = true;
1231 ClassLoaderData* dead = data;
1232 dead->unload();
1233 data = data->next();
1234 // Remove from loader list.
1235 // This class loader data will no longer be found
1236 // in the ClassLoaderDataGraph.
1237 if (prev != NULL) {
1238 prev->set_next(data);
1239 } else {
1240 assert(dead == _head, "sanity check");
1241 _head = data;
1242 }
1243 dead->set_next(_unloading);
1244 _unloading = dead;
1245 }
1246
1247 if (seen_dead_loader) {
1248 // Walk a Dictionary, ModuleEntry's reads, and a PackageEntry's exports
1249 // lists to determine if there are modules on those lists that are now
1250 // dead and should be removed. A module's life cycle is equivalent
1251 // to its defining class loader's life cycle. Since a module is
1252 // considered dead if its class loader is dead, these walks must
1253 // occur after each class loader's aliveness is determined.
1254 data = _head;
1255 while (data != NULL) {
1256 if (data->dictionary_or_null() != NULL) {
1257 data->dictionary()->do_unloading();
1258 }
1259 if (data->packages() != NULL) {
1260 data->packages()->purge_all_package_exports();
1261 }
1262 if (data->modules_defined()) {
1263 data->modules()->purge_all_module_reads();
1264 }
1265 data = data->next();
1266 }
1267
1268 post_class_unload_events();
1269 }
1270
1271 return seen_dead_loader;
1272 }
1273
1274 void ClassLoaderDataGraph::purge() {
1275 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1276 ClassLoaderData* list = _unloading;
1277 _unloading = NULL;
1278 ClassLoaderData* next = list;
1279 bool classes_unloaded = false;
1280 while (next != NULL) {
1281 ClassLoaderData* purge_me = next;
1282 next = purge_me->next();
1283 delete purge_me;
1284 classes_unloaded = true;
1285 }
1286 if (classes_unloaded) {
1287 Metaspace::purge();
1288 set_metaspace_oom(false);
1289 }
1290 }
1291
1292 void ClassLoaderDataGraph::post_class_unload_events() {
1293 #if INCLUDE_TRACE
1294 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1295 if (Tracing::enabled()) {
1296 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1297 assert(_unloading != NULL, "need class loader data unload list!");
1298 _class_unload_time = Ticks::now();
1299 classes_unloading_do(&class_unload_event);
1300 }
1301 Tracing::on_unloading_classes();
1302 }
1303 #endif
1304 }
1305
1306 // CDS support
1307
1308 // Global metaspaces for writing information to the shared archive. When
1309 // application CDS is supported, we may need one per metaspace, so this
1310 // sort of looks like it.
1311 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
1312 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
1313 static bool _shared_metaspaces_initialized = false;
1314
1315 // Initialize shared metaspaces (change to call from somewhere not lazily)
1316 void ClassLoaderData::initialize_shared_metaspaces() {
1317 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
1318 assert(this == ClassLoaderData::the_null_class_loader_data(),
1319 "only supported for null loader data for now");
1320 assert (!_shared_metaspaces_initialized, "only initialize once");
1321 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
1322 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
1323 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
1324 _shared_metaspaces_initialized = true;
1325 }
1326
1327 Metaspace* ClassLoaderData::ro_metaspace() {
1328 assert(_ro_metaspace != NULL, "should already be initialized");
1329 return _ro_metaspace;
1330 }
1331
1332 Metaspace* ClassLoaderData::rw_metaspace() {
1333 assert(_rw_metaspace != NULL, "should already be initialized");
1334 return _rw_metaspace;
1335 }
1336
1337 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1338 : _next_klass(NULL) {
1339 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1340 Klass* klass = NULL;
1341
1342 // Find the first klass in the CLDG.
1343 while (cld != NULL) {
1344 assert_locked_or_safepoint(cld->metaspace_lock());
1345 klass = cld->_klasses;
1346 if (klass != NULL) {
1347 _next_klass = klass;
1348 return;
1349 }
1350 cld = cld->next();
1351 }
1352 }
1353
1354 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1355 Klass* next = klass->next_link();
1356 if (next != NULL) {
1357 return next;
1358 }
1359
1360 // No more klasses in the current CLD. Time to find a new CLD.
1361 ClassLoaderData* cld = klass->class_loader_data();
1362 assert_locked_or_safepoint(cld->metaspace_lock());
1363 while (next == NULL) {
1364 cld = cld->next();
1365 if (cld == NULL) {
1366 break;
1367 }
1368 next = cld->_klasses;
1369 }
1370
1371 return next;
1372 }
1373
1374 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1375 Klass* head = _next_klass;
1376
1377 while (head != NULL) {
1378 Klass* next = next_klass_in_cldg(head);
1379
1380 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
1381
1382 if (old_head == head) {
1383 return head; // Won the CAS.
1384 }
1385
1386 head = old_head;
1387 }
1388
1389 // Nothing more for the iterator to hand out.
1390 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1391 return NULL;
1392 }
1393
1394 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1395 _data = ClassLoaderDataGraph::_head;
1396 }
1397
1398 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1399
1400 #ifndef PRODUCT
1401 // callable from debugger
1402 extern "C" int print_loader_data_graph() {
1403 ClassLoaderDataGraph::dump_on(tty);
1404 return 0;
1405 }
1406
1407 void ClassLoaderDataGraph::verify() {
1408 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1409 data->verify();
1410 }
1411 }
1412
1413 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1414 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1415 data->dump(out);
1416 }
1417 MetaspaceAux::dump(out);
1418 }
1419 #endif // PRODUCT
1420
1421 void ClassLoaderData::print_value_on(outputStream* out) const {
1422 if (class_loader() == NULL) {
1423 out->print("NULL class_loader");
1424 } else {
1425 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1426 class_loader()->print_value_on(out);
1427 }
1428 }
1429
1430 void ClassLoaderData::print_on(outputStream* out) const {
1431 if (class_loader() == NULL) {
1432 out->print("NULL class_loader");
1433 } else {
1434 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1435 class_loader()->print_on(out);
1436 }
1437 }
1438
1439 #if INCLUDE_TRACE
1440
1441 Ticks ClassLoaderDataGraph::_class_unload_time;
1442
1443 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1444 assert(k != NULL, "invariant");
1445
1446 // post class unload event
1447 EventClassUnload event(UNTIMED);
1448 event.set_endtime(_class_unload_time);
1449 event.set_unloadedClass(k);
1450 event.set_definingClassLoader(k->class_loader_data());
1451 event.commit();
1452 }
1453
1454 #endif // INCLUDE_TRACE