1 /*
2 * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // A ClassLoaderData identifies the full set of class types that a class
26 // loader's name resolution strategy produces for a given configuration of the
27 // class loader.
28 // Class types in the ClassLoaderData may be defined by from class file binaries
29 // provided by the class loader, or from other class loader it interacts with
30 // according to its name resolution strategy.
31 //
32 // Class loaders that implement a deterministic name resolution strategy
33 // (including with respect to their delegation behavior), such as the boot, the
34 // platform, and the system loaders of the JDK's built-in class loader
35 // hierarchy, always produce the same linkset for a given configuration.
36 //
37 // ClassLoaderData carries information related to a linkset (e.g.,
38 // metaspace holding its klass definitions).
39 // The System Dictionary and related data structures (e.g., placeholder table,
40 // loader constraints table) as well as the runtime representation of classes
41 // only reference ClassLoaderData.
42 //
43 // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that
44 // that represent the loader's "linking domain" in the JVM.
45 //
46 // The bootstrap loader (represented by NULL) also has a ClassLoaderData,
47 // the singleton class the_null_class_loader_data().
48
49 #include "precompiled.hpp"
50 #include "classfile/classLoaderData.hpp"
51 #include "classfile/classLoaderData.inline.hpp"
52 #include "classfile/dictionary.hpp"
53 #include "classfile/javaClasses.hpp"
54 #include "classfile/metadataOnStackMark.hpp"
55 #include "classfile/moduleEntry.hpp"
56 #include "classfile/packageEntry.hpp"
57 #include "classfile/systemDictionary.hpp"
58 #include "code/codeCache.hpp"
59 #include "gc/shared/gcLocker.hpp"
60 #include "logging/log.hpp"
61 #include "logging/logStream.hpp"
62 #include "memory/metadataFactory.hpp"
63 #include "memory/metaspaceShared.hpp"
64 #include "memory/oopFactory.hpp"
65 #include "memory/resourceArea.hpp"
66 #include "oops/access.inline.hpp"
67 #include "oops/objArrayOop.inline.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "runtime/atomic.hpp"
70 #include "runtime/javaCalls.hpp"
71 #include "runtime/jniHandles.hpp"
72 #include "runtime/mutex.hpp"
73 #include "runtime/orderAccess.hpp"
74 #include "runtime/safepoint.hpp"
75 #include "runtime/synchronizer.hpp"
76 #include "utilities/growableArray.hpp"
77 #include "utilities/macros.hpp"
78 #include "utilities/ostream.hpp"
79 #if INCLUDE_TRACE
80 #include "trace/tracing.hpp"
81 #endif
82
83 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
84
85 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
86 _class_loader(h_class_loader()),
87 _is_anonymous(is_anonymous),
88 // An anonymous class loader data doesn't have anything to keep
89 // it from being unloaded during parsing of the anonymous class.
90 // The null-class-loader should always be kept alive.
91 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
92 _metaspace(NULL), _unloading(false), _klasses(NULL),
93 _modules(NULL), _packages(NULL),
94 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false),
95 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
96 _next(NULL), _dependencies(dependencies),
97 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
98 Monitor::_safepoint_check_never)) {
99
100 // A ClassLoaderData created solely for an anonymous class should never have a
101 // ModuleEntryTable or PackageEntryTable created for it. The defining package
102 // and module for an anonymous class will be found in its host class.
103 if (!is_anonymous) {
104 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
105 if (h_class_loader.is_null()) {
106 // Create unnamed module for boot loader
107 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
108 } else {
109 // Create unnamed module for all other loaders
110 _unnamed_module = ModuleEntry::create_unnamed_module(this);
111 }
112 } else {
113 _unnamed_module = NULL;
114 }
115
116 if (!is_anonymous) {
117 _dictionary = create_dictionary();
118 } else {
119 _dictionary = NULL;
120 }
121 TRACE_INIT_ID(this);
122 }
123
124 void ClassLoaderData::init_dependencies(TRAPS) {
125 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
126 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
127 _dependencies.init(CHECK);
128 }
129
130 void ClassLoaderData::Dependencies::init(TRAPS) {
131 // Create empty dependencies array to add to. CMS requires this to be
132 // an oop so that it can track additions via card marks. We think.
133 _list_head = oopFactory::new_objectArray(2, CHECK);
134 }
135
136 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
137 Chunk* c = _head;
138 while (c != NULL) {
139 Chunk* next = c->_next;
140 delete c;
141 c = next;
142 }
143 }
144
145 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
146 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
147 Chunk* next = new Chunk(_head);
148 OrderAccess::release_store(&_head, next);
149 }
150 oop* handle = &_head->_data[_head->_size];
151 *handle = o;
152 OrderAccess::release_store(&_head->_size, _head->_size + 1);
153 return handle;
154 }
155
156 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
157 for (juint i = 0; i < size; i++) {
158 if (c->_data[i] != NULL) {
159 f->do_oop(&c->_data[i]);
160 }
161 }
162 }
163
164 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
165 Chunk* head = OrderAccess::load_acquire(&_head);
166 if (head != NULL) {
167 // Must be careful when reading size of head
168 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
169 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
170 oops_do_chunk(f, c, c->_size);
171 }
172 }
173 }
174
175 #ifdef ASSERT
176 class VerifyContainsOopClosure : public OopClosure {
177 oop* _target;
178 bool _found;
179
180 public:
181 VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {}
182
183 void do_oop(oop* p) {
184 if (p == _target) {
185 _found = true;
186 }
187 }
188
189 void do_oop(narrowOop* p) {
190 // The ChunkedHandleList should not contain any narrowOop
191 ShouldNotReachHere();
192 }
193
194 bool found() const {
195 return _found;
196 }
197 };
198
199 bool ClassLoaderData::ChunkedHandleList::contains(oop* p) {
200 VerifyContainsOopClosure cl(p);
201 oops_do(&cl);
202 return cl.found();
203 }
204 #endif // ASSERT
205
206 bool ClassLoaderData::claim() {
207 if (_claimed == 1) {
208 return false;
209 }
210
211 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
212 }
213
214 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
215 // while the class is being parsed, and if the class appears on the module fixup list.
216 // Due to the uniqueness that no other class shares the anonymous class' name or
217 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
218 // it is being defined, therefore _keep_alive is not volatile or atomic.
219 void ClassLoaderData::inc_keep_alive() {
220 if (is_anonymous()) {
221 assert(_keep_alive >= 0, "Invalid keep alive increment count");
222 _keep_alive++;
223 }
224 }
225
226 void ClassLoaderData::dec_keep_alive() {
227 if (is_anonymous()) {
228 assert(_keep_alive > 0, "Invalid keep alive decrement count");
229 _keep_alive--;
230 }
231 }
232
233 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
234 if (must_claim && !claim()) {
235 return;
236 }
237
238 // Only clear modified_oops after the ClassLoaderData is claimed.
239 if (clear_mod_oops) {
240 clear_modified_oops();
241 }
242
243 f->do_oop(&_class_loader);
244 _dependencies.oops_do(f);
245 _handles.oops_do(f);
246 }
247
248 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
249 f->do_oop((oop*)&_list_head);
250 }
251
252 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
253 // Lock-free access requires load_acquire
254 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
255 klass_closure->do_klass(k);
256 assert(k != k->next_link(), "no loops!");
257 }
258 }
259
260 void ClassLoaderData::classes_do(void f(Klass * const)) {
261 // Lock-free access requires load_acquire
262 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
263 f(k);
264 assert(k != k->next_link(), "no loops!");
265 }
266 }
267
268 void ClassLoaderData::methods_do(void f(Method*)) {
269 // Lock-free access requires load_acquire
270 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
271 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
272 InstanceKlass::cast(k)->methods_do(f);
273 }
274 }
275 }
276
277 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
278 // Lock-free access requires load_acquire
279 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
280 // Do not filter ArrayKlass oops here...
281 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
282 klass_closure->do_klass(k);
283 }
284 }
285 }
286
287 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
288 // Lock-free access requires load_acquire
289 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
290 if (k->is_instance_klass()) {
291 f(InstanceKlass::cast(k));
292 }
293 assert(k != k->next_link(), "no loops!");
294 }
295 }
296
297 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
298 assert_locked_or_safepoint(Module_lock);
299 if (_unnamed_module != NULL) {
300 f(_unnamed_module);
301 }
302 if (_modules != NULL) {
303 for (int i = 0; i < _modules->table_size(); i++) {
304 for (ModuleEntry* entry = _modules->bucket(i);
305 entry != NULL;
306 entry = entry->next()) {
307 f(entry);
308 }
309 }
310 }
311 }
312
313 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
314 assert_locked_or_safepoint(Module_lock);
315 if (_packages != NULL) {
316 for (int i = 0; i < _packages->table_size(); i++) {
317 for (PackageEntry* entry = _packages->bucket(i);
318 entry != NULL;
319 entry = entry->next()) {
320 f(entry);
321 }
322 }
323 }
324 }
325
326 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
327 assert(k != NULL, "invariant");
328
329 ClassLoaderData * const from_cld = this;
330 ClassLoaderData * const to_cld = k->class_loader_data();
331
332 // Dependency to the null class loader data doesn't need to be recorded
333 // because the null class loader data never goes away.
334 if (to_cld->is_the_null_class_loader_data()) {
335 return;
336 }
337
338 oop to;
339 if (to_cld->is_anonymous()) {
340 // Anonymous class dependencies are through the mirror.
341 to = k->java_mirror();
342 } else {
343 to = to_cld->class_loader();
344
345 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
346 // we still have to add it. The class_loader won't keep from_cld alive.
347 if (!from_cld->is_anonymous()) {
348 // Check that this dependency isn't from the same or parent class_loader
349 oop from = from_cld->class_loader();
350
351 oop curr = from;
352 while (curr != NULL) {
353 if (curr == to) {
354 return; // this class loader is in the parent list, no need to add it.
355 }
356 curr = java_lang_ClassLoader::parent(curr);
357 }
358 }
359 }
360
361 // It's a dependency we won't find through GC, add it. This is relatively rare
362 // Must handle over GC point.
363 Handle dependency(THREAD, to);
364 from_cld->_dependencies.add(dependency, CHECK);
365
366 // Added a potentially young gen oop to the ClassLoaderData
367 record_modified_oops();
368 }
369
370
371 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
372 // Check first if this dependency is already in the list.
373 // Save a pointer to the last to add to under the lock.
374 objArrayOop ok = _list_head;
375 objArrayOop last = NULL;
376 while (ok != NULL) {
377 last = ok;
378 if (ok->obj_at(0) == dependency()) {
379 // Don't need to add it
380 return;
381 }
382 ok = (objArrayOop)ok->obj_at(1);
383 }
384
385 // Must handle over GC points
386 assert (last != NULL, "dependencies should be initialized");
387 objArrayHandle last_handle(THREAD, last);
388
389 // Create a new dependency node with fields for (class_loader or mirror, next)
390 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
391 deps->obj_at_put(0, dependency());
392
393 // Must handle over GC points
394 objArrayHandle new_dependency(THREAD, deps);
395
396 // Add the dependency under lock
397 locked_add(last_handle, new_dependency, THREAD);
398 }
399
400 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
401 objArrayHandle new_dependency,
402 Thread* THREAD) {
403
404 // Have to lock and put the new dependency on the end of the dependency
405 // array so the card mark for CMS sees that this dependency is new.
406 // Can probably do this lock free with some effort.
407 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
408
409 oop loader_or_mirror = new_dependency->obj_at(0);
410
411 // Since the dependencies are only added, add to the end.
412 objArrayOop end = last_handle();
413 objArrayOop last = NULL;
414 while (end != NULL) {
415 last = end;
416 // check again if another thread added it to the end.
417 if (end->obj_at(0) == loader_or_mirror) {
418 // Don't need to add it
419 return;
420 }
421 end = (objArrayOop)end->obj_at(1);
422 }
423 assert (last != NULL, "dependencies should be initialized");
424 // fill in the first element with the oop in new_dependency.
425 if (last->obj_at(0) == NULL) {
426 last->obj_at_put(0, new_dependency->obj_at(0));
427 } else {
428 last->obj_at_put(1, new_dependency());
429 }
430 }
431
432 void ClassLoaderDataGraph::clear_claimed_marks() {
433 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
434 cld->clear_claimed();
435 }
436 }
437
438 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
439 {
440 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
441 Klass* old_value = _klasses;
442 k->set_next_link(old_value);
443 // Link the new item into the list, making sure the linked class is stable
444 // since the list can be walked without a lock
445 OrderAccess::release_store(&_klasses, k);
446 }
447
448 if (publicize && k->class_loader_data() != NULL) {
449 ResourceMark rm;
450 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
451 PTR_FORMAT " loader: " PTR_FORMAT " %s",
452 p2i(k),
453 k->external_name(),
454 p2i(k->class_loader_data()),
455 p2i((void *)k->class_loader()),
456 loader_name());
457 }
458 }
459
460 // Class iterator used by the compiler. It gets some number of classes at
461 // a safepoint to decay invocation counters on the methods.
462 class ClassLoaderDataGraphKlassIteratorStatic {
463 ClassLoaderData* _current_loader_data;
464 Klass* _current_class_entry;
465 public:
466
467 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
468
469 InstanceKlass* try_get_next_class() {
470 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
471 int max_classes = InstanceKlass::number_of_instance_classes();
472 assert(max_classes > 0, "should not be called with no instance classes");
473 for (int i = 0; i < max_classes; ) {
474
475 if (_current_class_entry != NULL) {
476 Klass* k = _current_class_entry;
477 _current_class_entry = _current_class_entry->next_link();
478
479 if (k->is_instance_klass()) {
480 InstanceKlass* ik = InstanceKlass::cast(k);
481 i++; // count all instance classes found
482 // Not yet loaded classes are counted in max_classes
483 // but only return loaded classes.
484 if (ik->is_loaded()) {
485 return ik;
486 }
487 }
488 } else {
489 // Go to next CLD
490 if (_current_loader_data != NULL) {
491 _current_loader_data = _current_loader_data->next();
492 }
493 // Start at the beginning
494 if (_current_loader_data == NULL) {
495 _current_loader_data = ClassLoaderDataGraph::_head;
496 }
497
498 _current_class_entry = _current_loader_data->klasses();
499 }
500 }
501 // Should never be reached unless all instance classes have failed or are not fully loaded.
502 // Caller handles NULL.
503 return NULL;
504 }
505
506 // If the current class for the static iterator is a class being unloaded or
507 // deallocated, adjust the current class.
508 void adjust_saved_class(ClassLoaderData* cld) {
509 if (_current_loader_data == cld) {
510 _current_loader_data = cld->next();
511 if (_current_loader_data != NULL) {
512 _current_class_entry = _current_loader_data->klasses();
513 } // else try_get_next_class will start at the head
514 }
515 }
516
517 void adjust_saved_class(Klass* klass) {
518 if (_current_class_entry == klass) {
519 _current_class_entry = klass->next_link();
520 }
521 }
522 };
523
524 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
525
526 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
527 return static_klass_iterator.try_get_next_class();
528 }
529
530
531 // Remove a klass from the _klasses list for scratch_class during redefinition
532 // or parsed class in the case of an error.
533 void ClassLoaderData::remove_class(Klass* scratch_class) {
534 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
535
536 // Adjust global class iterator.
537 static_klass_iterator.adjust_saved_class(scratch_class);
538
539 Klass* prev = NULL;
540 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
541 if (k == scratch_class) {
542 if (prev == NULL) {
543 _klasses = k->next_link();
544 } else {
545 Klass* next = k->next_link();
546 prev->set_next_link(next);
547 }
548 return;
549 }
550 prev = k;
551 assert(k != k->next_link(), "no loops!");
552 }
553 ShouldNotReachHere(); // should have found this class!!
554 }
555
556 void ClassLoaderData::unload() {
557 _unloading = true;
558
559 // Tell serviceability tools these classes are unloading
560 classes_do(InstanceKlass::notify_unload_class);
561
562 LogTarget(Debug, class, loader, data) lt;
563 if (lt.is_enabled()) {
564 ResourceMark rm;
565 LogStream ls(lt);
566 ls.print(": unload loader data " INTPTR_FORMAT, p2i(this));
567 ls.print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
568 loader_name());
569 if (is_anonymous()) {
570 ls.print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
571 }
572 ls.cr();
573 }
574
575 // Some items on the _deallocate_list need to free their C heap structures
576 // if they are not already on the _klasses list.
577 unload_deallocate_list();
578
579 // Clean up global class iterator for compiler
580 static_klass_iterator.adjust_saved_class(this);
581 }
582
583 ModuleEntryTable* ClassLoaderData::modules() {
584 // Lazily create the module entry table at first request.
585 // Lock-free access requires load_acquire.
586 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
587 if (modules == NULL) {
588 MutexLocker m1(Module_lock);
589 // Check if _modules got allocated while we were waiting for this lock.
590 if ((modules = _modules) == NULL) {
591 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
592
593 {
594 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
595 // Ensure _modules is stable, since it is examined without a lock
596 OrderAccess::release_store(&_modules, modules);
597 }
598 }
599 }
600 return modules;
601 }
602
603 const int _boot_loader_dictionary_size = 1009;
604 const int _default_loader_dictionary_size = 107;
605
606 Dictionary* ClassLoaderData::create_dictionary() {
607 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
608 int size;
609 bool resizable = false;
610 if (_the_null_class_loader_data == NULL) {
611 size = _boot_loader_dictionary_size;
612 resizable = true;
613 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
614 size = 1; // there's only one class in relection class loader and no initiated classes
615 } else if (is_system_class_loader_data()) {
616 size = _boot_loader_dictionary_size;
617 resizable = true;
618 } else {
619 size = _default_loader_dictionary_size;
620 resizable = true;
621 }
622 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) {
623 resizable = false;
624 }
625 return new Dictionary(this, size, resizable);
626 }
627
628 // Unloading support
629 oop ClassLoaderData::keep_alive_object() const {
630 assert_locked_or_safepoint(_metaspace_lock);
631 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
632 return is_anonymous() ? _klasses->java_mirror() : class_loader();
633 }
634
635 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
636 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
637 || is_alive_closure->do_object_b(keep_alive_object());
638
639 return alive;
640 }
641
642 ClassLoaderData::~ClassLoaderData() {
643 // Release C heap structures for all the classes.
644 classes_do(InstanceKlass::release_C_heap_structures);
645
646 // Release C heap allocated hashtable for all the packages.
647 if (_packages != NULL) {
648 // Destroy the table itself
649 delete _packages;
650 _packages = NULL;
651 }
652
653 // Release C heap allocated hashtable for all the modules.
654 if (_modules != NULL) {
655 // Destroy the table itself
656 delete _modules;
657 _modules = NULL;
658 }
659
660 // Release C heap allocated hashtable for the dictionary
661 if (_dictionary != NULL) {
662 // Destroy the table itself
663 delete _dictionary;
664 _dictionary = NULL;
665 }
666
667 if (_unnamed_module != NULL) {
668 _unnamed_module->delete_unnamed_module();
669 _unnamed_module = NULL;
670 }
671
672 // release the metaspace
673 Metaspace *m = _metaspace;
674 if (m != NULL) {
675 _metaspace = NULL;
676 delete m;
677 }
678 // Clear all the JNI handles for methods
679 // These aren't deallocated and are going to look like a leak, but that's
680 // needed because we can't really get rid of jmethodIDs because we don't
681 // know when native code is going to stop using them. The spec says that
682 // they're "invalid" but existing programs likely rely on their being
683 // NULL after class unloading.
684 if (_jmethod_ids != NULL) {
685 Method::clear_jmethod_ids(this);
686 }
687 // Delete lock
688 delete _metaspace_lock;
689
690 // Delete free list
691 if (_deallocate_list != NULL) {
692 delete _deallocate_list;
693 }
694 }
695
696 // Returns true if this class loader data is for the system class loader.
697 bool ClassLoaderData::is_system_class_loader_data() const {
698 return SystemDictionary::is_system_class_loader(class_loader());
699 }
700
701 // Returns true if this class loader data is for the platform class loader.
702 bool ClassLoaderData::is_platform_class_loader_data() const {
703 return SystemDictionary::is_platform_class_loader(class_loader());
704 }
705
706 // Returns true if this class loader data is one of the 3 builtin
707 // (boot, application/system or platform) class loaders. Note, the
708 // builtin loaders are not freed by a GC.
709 bool ClassLoaderData::is_builtin_class_loader_data() const {
710 return (is_the_null_class_loader_data() ||
711 SystemDictionary::is_system_class_loader(class_loader()) ||
712 SystemDictionary::is_platform_class_loader(class_loader()));
713 }
714
715 Metaspace* ClassLoaderData::metaspace_non_null() {
716 // If the metaspace has not been allocated, create a new one. Might want
717 // to create smaller arena for Reflection class loaders also.
718 // The reason for the delayed allocation is because some class loaders are
719 // simply for delegating with no metadata of their own.
720 // Lock-free access requires load_acquire.
721 Metaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
722 if (metaspace == NULL) {
723 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
724 // Check if _metaspace got allocated while we were waiting for this lock.
725 if ((metaspace = _metaspace) == NULL) {
726 if (this == the_null_class_loader_data()) {
727 assert (class_loader() == NULL, "Must be");
728 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
729 } else if (is_anonymous()) {
730 if (class_loader() != NULL) {
731 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
732 }
733 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
734 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
735 if (class_loader() != NULL) {
736 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
737 }
738 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
739 } else {
740 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
741 }
742 // Ensure _metaspace is stable, since it is examined without a lock
743 OrderAccess::release_store(&_metaspace, metaspace);
744 }
745 }
746 return metaspace;
747 }
748
749 OopHandle ClassLoaderData::add_handle(Handle h) {
750 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
751 record_modified_oops();
752 return OopHandle(_handles.add(h()));
753 }
754
755 void ClassLoaderData::remove_handle(OopHandle h) {
756 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
757 oop* ptr = h.ptr_raw();
758 if (ptr != NULL) {
759 assert(_handles.contains(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
760 // This root is not walked in safepoints, and hence requires an appropriate
761 // decorator that e.g. maintains the SATB invariant in SATB collectors.
762 RootAccess<IN_CONCURRENT_ROOT>::oop_store(ptr, oop(NULL));
763 }
764 }
765
766 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
767 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
768 if (dest.resolve() != NULL) {
769 return;
770 } else {
771 dest = _handles.add(h());
772 }
773 }
774
775 // Add this metadata pointer to be freed when it's safe. This is only during
776 // class unloading because Handles might point to this metadata field.
777 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
778 // Metadata in shared region isn't deleted.
779 if (!m->is_shared()) {
780 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
781 if (_deallocate_list == NULL) {
782 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
783 }
784 _deallocate_list->append_if_missing(m);
785 }
786 }
787
788 // Deallocate free metadata on the free list. How useful the PermGen was!
789 void ClassLoaderData::free_deallocate_list() {
790 // Don't need lock, at safepoint
791 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
792 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
793 if (_deallocate_list == NULL) {
794 return;
795 }
796 // Go backwards because this removes entries that are freed.
797 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
798 Metadata* m = _deallocate_list->at(i);
799 if (!m->on_stack()) {
800 _deallocate_list->remove_at(i);
801 // There are only three types of metadata that we deallocate directly.
802 // Cast them so they can be used by the template function.
803 if (m->is_method()) {
804 MetadataFactory::free_metadata(this, (Method*)m);
805 } else if (m->is_constantPool()) {
806 MetadataFactory::free_metadata(this, (ConstantPool*)m);
807 } else if (m->is_klass()) {
808 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
809 } else {
810 ShouldNotReachHere();
811 }
812 } else {
813 // Metadata is alive.
814 // If scratch_class is on stack then it shouldn't be on this list!
815 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
816 "scratch classes on this list should be dead");
817 // Also should assert that other metadata on the list was found in handles.
818 }
819 }
820 }
821
822 // This is distinct from free_deallocate_list. For class loader data that are
823 // unloading, this frees the C heap memory for items on the list, and unlinks
824 // scratch or error classes so that unloading events aren't triggered for these
825 // classes. The metadata is removed with the unloading metaspace.
826 // There isn't C heap memory allocated for methods, so nothing is done for them.
827 void ClassLoaderData::unload_deallocate_list() {
828 // Don't need lock, at safepoint
829 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
830 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
831 if (_deallocate_list == NULL) {
832 return;
833 }
834 // Go backwards because this removes entries that are freed.
835 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
836 Metadata* m = _deallocate_list->at(i);
837 assert (!m->on_stack(), "wouldn't be unloading if this were so");
838 _deallocate_list->remove_at(i);
839 if (m->is_constantPool()) {
840 ((ConstantPool*)m)->release_C_heap_structures();
841 } else if (m->is_klass()) {
842 InstanceKlass* ik = (InstanceKlass*)m;
843 // also releases ik->constants() C heap memory
844 InstanceKlass::release_C_heap_structures(ik);
845 // Remove the class so unloading events aren't triggered for
846 // this class (scratch or error class) in do_unloading().
847 remove_class(ik);
848 }
849 }
850 }
851
852 // These anonymous class loaders are to contain classes used for JSR292
853 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
854 // Add a new class loader data to the graph.
855 Handle lh(THREAD, loader);
856 return ClassLoaderDataGraph::add(lh, true, THREAD);
857 }
858
859 const char* ClassLoaderData::loader_name() {
860 // Handles null class loader
861 return SystemDictionary::loader_name(class_loader());
862 }
863
864 #ifndef PRODUCT
865 // Define to dump klasses
866 #undef CLD_DUMP_KLASSES
867
868 void ClassLoaderData::dump(outputStream * const out) {
869 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
870 p2i(this), p2i((void *)class_loader()),
871 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
872 if (claimed()) out->print(" claimed ");
873 if (is_unloading()) out->print(" unloading ");
874 out->cr();
875 if (metaspace_or_null() != NULL) {
876 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
877 metaspace_or_null()->dump(out);
878 } else {
879 out->print_cr("metaspace: NULL");
880 }
881
882 #ifdef CLD_DUMP_KLASSES
883 if (Verbose) {
884 Klass* k = _klasses;
885 while (k != NULL) {
886 out->print_cr("klass " PTR_FORMAT ", %s", p2i(k), k->name()->as_C_string());
887 assert(k != k->next_link(), "no loops!");
888 k = k->next_link();
889 }
890 }
891 #endif // CLD_DUMP_KLASSES
892 #undef CLD_DUMP_KLASSES
893 if (_jmethod_ids != NULL) {
894 Method::print_jmethod_ids(this, out);
895 }
896 out->print_cr("}");
897 }
898 #endif // PRODUCT
899
900 void ClassLoaderData::verify() {
901 assert_locked_or_safepoint(_metaspace_lock);
902 oop cl = class_loader();
903
904 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
905 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
906
907 // Verify the integrity of the allocated space.
908 if (metaspace_or_null() != NULL) {
909 metaspace_or_null()->verify();
910 }
911
912 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
913 guarantee(k->class_loader_data() == this, "Must be the same");
914 k->verify();
915 assert(k != k->next_link(), "no loops!");
916 }
917 }
918
919 bool ClassLoaderData::contains_klass(Klass* klass) {
920 // Lock-free access requires load_acquire
921 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
922 if (k == klass) return true;
923 }
924 return false;
925 }
926
927
928 // GC root of class loader data created.
929 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
930 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
931 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
932 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
933
934 bool ClassLoaderDataGraph::_should_purge = false;
935 bool ClassLoaderDataGraph::_metaspace_oom = false;
936
937 // Add a new class loader data node to the list. Assign the newly created
938 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
939 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
940 // We need to allocate all the oops for the ClassLoaderData before allocating the
941 // actual ClassLoaderData object.
942 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
943
944 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
945 // ClassLoaderData in the graph since the CLD
946 // contains unhandled oops
947
948 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
949
950
951 if (!is_anonymous) {
952 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
953 // First, Atomically set it
954 ClassLoaderData* old = Atomic::cmpxchg(cld, cld_addr, (ClassLoaderData*)NULL);
955 if (old != NULL) {
956 delete cld;
957 // Returns the data.
958 return old;
959 }
960 }
961
962 // We won the race, and therefore the task of adding the data to the list of
963 // class loader data
964 ClassLoaderData** list_head = &_head;
965 ClassLoaderData* next = _head;
966
967 do {
968 cld->set_next(next);
969 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next);
970 if (exchanged == next) {
971 LogTarget(Debug, class, loader, data) lt;
972 if (lt.is_enabled()) {
973 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
974 LogStream ls(lt);
975 print_creation(&ls, loader, cld, CHECK_NULL);
976 }
977 return cld;
978 }
979 next = exchanged;
980 } while (true);
981 }
982
983 void ClassLoaderDataGraph::print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS) {
984 Handle string;
985 if (loader.not_null()) {
986 // Include the result of loader.toString() in the output. This allows
987 // the user of the log to identify the class loader instance.
988 JavaValue result(T_OBJECT);
989 Klass* spec_klass = SystemDictionary::ClassLoader_klass();
990 JavaCalls::call_virtual(&result,
991 loader,
992 spec_klass,
993 vmSymbols::toString_name(),
994 vmSymbols::void_string_signature(),
995 CHECK);
996 assert(result.get_type() == T_OBJECT, "just checking");
997 string = Handle(THREAD, (oop)result.get_jobject());
998 }
999
1000 ResourceMark rm;
1001 out->print("create class loader data " INTPTR_FORMAT, p2i(cld));
1002 out->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
1003 cld->loader_name());
1004
1005 if (string.not_null()) {
1006 out->print(": ");
1007 java_lang_String::print(string(), out);
1008 }
1009 out->cr();
1010 }
1011
1012
1013 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1014 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1015 cld->oops_do(f, must_claim);
1016 }
1017 }
1018
1019 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1020 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1021 if (cld->keep_alive()) {
1022 cld->oops_do(f, must_claim);
1023 }
1024 }
1025 }
1026
1027 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1028 if (ClassUnloading) {
1029 keep_alive_oops_do(f, must_claim);
1030 } else {
1031 oops_do(f, must_claim);
1032 }
1033 }
1034
1035 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1036 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1037 cl->do_cld(cld);
1038 }
1039 }
1040
1041 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1042 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1043 // Only walk the head until any clds not purged from prior unloading
1044 // (CMS doesn't purge right away).
1045 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1046 assert(cld->is_unloading(), "invariant");
1047 cl->do_cld(cld);
1048 }
1049 }
1050
1051 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1052 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1053 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1054 if (closure != NULL) {
1055 closure->do_cld(cld);
1056 }
1057 }
1058 }
1059
1060 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1061 roots_cld_do(cl, NULL);
1062 }
1063
1064 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1065 if (ClassUnloading) {
1066 keep_alive_cld_do(cl);
1067 } else {
1068 cld_do(cl);
1069 }
1070 }
1071
1072 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1073 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1074 cld->classes_do(klass_closure);
1075 }
1076 }
1077
1078 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1079 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1080 cld->classes_do(f);
1081 }
1082 }
1083
1084 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1085 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1086 cld->methods_do(f);
1087 }
1088 }
1089
1090 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1091 assert_locked_or_safepoint(Module_lock);
1092 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1093 cld->modules_do(f);
1094 }
1095 }
1096
1097 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1098 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1099 // Only walk the head until any clds not purged from prior unloading
1100 // (CMS doesn't purge right away).
1101 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1102 assert(cld->is_unloading(), "invariant");
1103 cld->modules_do(f);
1104 }
1105 }
1106
1107 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1108 assert_locked_or_safepoint(Module_lock);
1109 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1110 cld->packages_do(f);
1111 }
1112 }
1113
1114 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1115 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1116 // Only walk the head until any clds not purged from prior unloading
1117 // (CMS doesn't purge right away).
1118 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1119 assert(cld->is_unloading(), "invariant");
1120 cld->packages_do(f);
1121 }
1122 }
1123
1124 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1125 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1126 cld->loaded_classes_do(klass_closure);
1127 }
1128 }
1129
1130 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1131 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1132 // Only walk the head until any clds not purged from prior unloading
1133 // (CMS doesn't purge right away).
1134 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1135 assert(cld->is_unloading(), "invariant");
1136 cld->classes_do(f);
1137 }
1138 }
1139
1140 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1141 if (X->dictionary() != NULL)
1142
1143 // Walk classes in the loaded class dictionaries in various forms.
1144 // Only walks the classes defined in this class loader.
1145 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1146 FOR_ALL_DICTIONARY(cld) {
1147 cld->dictionary()->classes_do(f);
1148 }
1149 }
1150
1151 // Only walks the classes defined in this class loader.
1152 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1153 FOR_ALL_DICTIONARY(cld) {
1154 cld->dictionary()->classes_do(f, CHECK);
1155 }
1156 }
1157
1158 // Walks all entries in the dictionary including entries initiated by this class loader.
1159 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1160 FOR_ALL_DICTIONARY(cld) {
1161 cld->dictionary()->all_entries_do(f);
1162 }
1163 }
1164
1165 void ClassLoaderDataGraph::verify_dictionary() {
1166 FOR_ALL_DICTIONARY(cld) {
1167 cld->dictionary()->verify();
1168 }
1169 }
1170
1171 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1172 FOR_ALL_DICTIONARY(cld) {
1173 st->print("Dictionary for ");
1174 cld->print_value_on(st);
1175 st->cr();
1176 cld->dictionary()->print_on(st);
1177 st->cr();
1178 }
1179 }
1180
1181 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1182 FOR_ALL_DICTIONARY(cld) {
1183 ResourceMark rm;
1184 stringStream tempst;
1185 tempst.print("System Dictionary for %s", cld->loader_name());
1186 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1187 }
1188 }
1189
1190 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1191 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1192
1193 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1194
1195 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1196 ClassLoaderData* curr = _head;
1197 while (curr != _saved_head) {
1198 if (!curr->claimed()) {
1199 array->push(curr);
1200 LogTarget(Debug, class, loader, data) lt;
1201 if (lt.is_enabled()) {
1202 LogStream ls(lt);
1203 ls.print("found new CLD: ");
1204 curr->print_value_on(&ls);
1205 ls.cr();
1206 }
1207 }
1208
1209 curr = curr->_next;
1210 }
1211
1212 return array;
1213 }
1214
1215 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
1216 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
1217 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
1218 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
1219 return true;
1220 }
1221 }
1222 return false;
1223 }
1224
1225 #ifndef PRODUCT
1226 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1227 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1228 if (loader_data == data) {
1229 return true;
1230 }
1231 }
1232
1233 return false;
1234 }
1235 #endif // PRODUCT
1236
1237
1238 // Move class loader data from main list to the unloaded list for unloading
1239 // and deallocation later.
1240 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1241 bool clean_previous_versions) {
1242
1243 ClassLoaderData* data = _head;
1244 ClassLoaderData* prev = NULL;
1245 bool seen_dead_loader = false;
1246
1247 // Mark metadata seen on the stack only so we can delete unneeded entries.
1248 // Only walk all metadata, including the expensive code cache walk, for Full GC
1249 // and only if class redefinition and if there's previous versions of
1250 // Klasses to delete.
1251 bool walk_all_metadata = clean_previous_versions &&
1252 JvmtiExport::has_redefined_a_class() &&
1253 InstanceKlass::has_previous_versions_and_reset();
1254 MetadataOnStackMark md_on_stack(walk_all_metadata);
1255
1256 // Save previous _unloading pointer for CMS which may add to unloading list before
1257 // purging and we don't want to rewalk the previously unloaded class loader data.
1258 _saved_unloading = _unloading;
1259
1260 data = _head;
1261 while (data != NULL) {
1262 if (data->is_alive(is_alive_closure)) {
1263 // clean metaspace
1264 if (walk_all_metadata) {
1265 data->classes_do(InstanceKlass::purge_previous_versions);
1266 }
1267 data->free_deallocate_list();
1268 prev = data;
1269 data = data->next();
1270 continue;
1271 }
1272 seen_dead_loader = true;
1273 ClassLoaderData* dead = data;
1274 dead->unload();
1275 data = data->next();
1276 // Remove from loader list.
1277 // This class loader data will no longer be found
1278 // in the ClassLoaderDataGraph.
1279 if (prev != NULL) {
1280 prev->set_next(data);
1281 } else {
1282 assert(dead == _head, "sanity check");
1283 _head = data;
1284 }
1285 dead->set_next(_unloading);
1286 _unloading = dead;
1287 }
1288
1289 if (seen_dead_loader) {
1290 data = _head;
1291 while (data != NULL) {
1292 // Remove entries in the dictionary of live class loader that have
1293 // initiated loading classes in a dead class loader.
1294 if (data->dictionary() != NULL) {
1295 data->dictionary()->do_unloading(is_alive_closure);
1296 }
1297 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1298 // lists to determine if there are modules on those lists that are now
1299 // dead and should be removed. A module's life cycle is equivalent
1300 // to its defining class loader's life cycle. Since a module is
1301 // considered dead if its class loader is dead, these walks must
1302 // occur after each class loader's aliveness is determined.
1303 if (data->packages() != NULL) {
1304 data->packages()->purge_all_package_exports();
1305 }
1306 if (data->modules_defined()) {
1307 data->modules()->purge_all_module_reads();
1308 }
1309 data = data->next();
1310 }
1311
1312 post_class_unload_events();
1313 }
1314
1315 return seen_dead_loader;
1316 }
1317
1318 void ClassLoaderDataGraph::purge() {
1319 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1320 ClassLoaderData* list = _unloading;
1321 _unloading = NULL;
1322 ClassLoaderData* next = list;
1323 bool classes_unloaded = false;
1324 while (next != NULL) {
1325 ClassLoaderData* purge_me = next;
1326 next = purge_me->next();
1327 delete purge_me;
1328 classes_unloaded = true;
1329 }
1330 if (classes_unloaded) {
1331 Metaspace::purge();
1332 set_metaspace_oom(false);
1333 }
1334 }
1335
1336 int ClassLoaderDataGraph::resize_if_needed() {
1337 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1338 int resized = 0;
1339 if (Dictionary::does_any_dictionary_needs_resizing()) {
1340 FOR_ALL_DICTIONARY(cld) {
1341 if (cld->dictionary()->resize_if_needed()) {
1342 resized++;
1343 }
1344 }
1345 }
1346 return resized;
1347 }
1348
1349 void ClassLoaderDataGraph::post_class_unload_events() {
1350 #if INCLUDE_TRACE
1351 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1352 if (Tracing::enabled()) {
1353 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1354 assert(_unloading != NULL, "need class loader data unload list!");
1355 _class_unload_time = Ticks::now();
1356 classes_unloading_do(&class_unload_event);
1357 }
1358 Tracing::on_unloading_classes();
1359 }
1360 #endif
1361 }
1362
1363 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1364 : _next_klass(NULL) {
1365 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1366 Klass* klass = NULL;
1367
1368 // Find the first klass in the CLDG.
1369 while (cld != NULL) {
1370 assert_locked_or_safepoint(cld->metaspace_lock());
1371 klass = cld->_klasses;
1372 if (klass != NULL) {
1373 _next_klass = klass;
1374 return;
1375 }
1376 cld = cld->next();
1377 }
1378 }
1379
1380 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1381 Klass* next = klass->next_link();
1382 if (next != NULL) {
1383 return next;
1384 }
1385
1386 // No more klasses in the current CLD. Time to find a new CLD.
1387 ClassLoaderData* cld = klass->class_loader_data();
1388 assert_locked_or_safepoint(cld->metaspace_lock());
1389 while (next == NULL) {
1390 cld = cld->next();
1391 if (cld == NULL) {
1392 break;
1393 }
1394 next = cld->_klasses;
1395 }
1396
1397 return next;
1398 }
1399
1400 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1401 Klass* head = _next_klass;
1402
1403 while (head != NULL) {
1404 Klass* next = next_klass_in_cldg(head);
1405
1406 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1407
1408 if (old_head == head) {
1409 return head; // Won the CAS.
1410 }
1411
1412 head = old_head;
1413 }
1414
1415 // Nothing more for the iterator to hand out.
1416 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1417 return NULL;
1418 }
1419
1420 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1421 _data = ClassLoaderDataGraph::_head;
1422 }
1423
1424 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1425
1426 #ifndef PRODUCT
1427 // callable from debugger
1428 extern "C" int print_loader_data_graph() {
1429 ClassLoaderDataGraph::dump_on(tty);
1430 return 0;
1431 }
1432
1433 void ClassLoaderDataGraph::verify() {
1434 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1435 data->verify();
1436 }
1437 }
1438
1439 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1440 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1441 data->dump(out);
1442 }
1443 MetaspaceAux::dump(out);
1444 }
1445 #endif // PRODUCT
1446
1447 void ClassLoaderData::print_value_on(outputStream* out) const {
1448 if (class_loader() == NULL) {
1449 out->print("NULL class loader");
1450 } else {
1451 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1452 class_loader()->print_value_on(out);
1453 }
1454 }
1455
1456 void ClassLoaderData::print_on(outputStream* out) const {
1457 if (class_loader() == NULL) {
1458 out->print("NULL class loader");
1459 } else {
1460 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1461 class_loader()->print_on(out);
1462 }
1463 }
1464
1465 #if INCLUDE_TRACE
1466
1467 Ticks ClassLoaderDataGraph::_class_unload_time;
1468
1469 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1470 assert(k != NULL, "invariant");
1471
1472 // post class unload event
1473 EventClassUnload event(UNTIMED);
1474 event.set_endtime(_class_unload_time);
1475 event.set_unloadedClass(k);
1476 event.set_definingClassLoader(k->class_loader_data());
1477 event.commit();
1478 }
1479
1480 #endif // INCLUDE_TRACE