1 /*
2 * Copyright (c) 2012, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // A ClassLoaderData identifies the full set of class types that a class
26 // loader's name resolution strategy produces for a given configuration of the
27 // class loader.
28 // Class types in the ClassLoaderData may be defined by from class file binaries
29 // provided by the class loader, or from other class loader it interacts with
30 // according to its name resolution strategy.
31 //
32 // Class loaders that implement a deterministic name resolution strategy
33 // (including with respect to their delegation behavior), such as the boot, the
34 // platform, and the system loaders of the JDK's built-in class loader
35 // hierarchy, always produce the same linkset for a given configuration.
36 //
37 // ClassLoaderData carries information related to a linkset (e.g.,
38 // metaspace holding its klass definitions).
39 // The System Dictionary and related data structures (e.g., placeholder table,
40 // loader constraints table) as well as the runtime representation of classes
41 // only reference ClassLoaderData.
42 //
43 // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that
44 // that represent the loader's "linking domain" in the JVM.
45 //
46 // The bootstrap loader (represented by NULL) also has a ClassLoaderData,
47 // the singleton class the_null_class_loader_data().
48
49 #include "precompiled.hpp"
50 #include "classfile/classLoaderData.hpp"
51 #include "classfile/classLoaderData.inline.hpp"
52 #include "classfile/dictionary.hpp"
53 #include "classfile/javaClasses.hpp"
54 #include "classfile/metadataOnStackMark.hpp"
55 #include "classfile/moduleEntry.hpp"
56 #include "classfile/packageEntry.hpp"
57 #include "classfile/systemDictionary.hpp"
58 #include "code/codeCache.hpp"
59 #include "gc/shared/gcLocker.hpp"
60 #include "logging/log.hpp"
61 #include "logging/logStream.hpp"
62 #include "memory/metadataFactory.hpp"
63 #include "memory/metaspaceShared.hpp"
64 #include "memory/oopFactory.hpp"
65 #include "memory/resourceArea.hpp"
66 #include "oops/objArrayOop.inline.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "runtime/atomic.hpp"
69 #include "runtime/javaCalls.hpp"
70 #include "runtime/jniHandles.hpp"
71 #include "runtime/mutex.hpp"
72 #include "runtime/orderAccess.hpp"
73 #include "runtime/safepoint.hpp"
74 #include "runtime/synchronizer.hpp"
75 #include "utilities/growableArray.hpp"
76 #include "utilities/macros.hpp"
77 #include "utilities/ostream.hpp"
78 #if INCLUDE_ALL_GCS
79 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
80 #endif // INCLUDE_ALL_GCS
81 #if INCLUDE_TRACE
82 #include "trace/tracing.hpp"
83 #endif
84
85 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
86
87 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
88 _class_loader(h_class_loader()),
89 _is_anonymous(is_anonymous),
90 // An anonymous class loader data doesn't have anything to keep
91 // it from being unloaded during parsing of the anonymous class.
92 // The null-class-loader should always be kept alive.
93 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
94 _metaspace(NULL), _unloading(false), _klasses(NULL),
95 _modules(NULL), _packages(NULL),
96 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false),
97 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
98 _next(NULL), _dependencies(dependencies),
99 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
100 Monitor::_safepoint_check_never)) {
101
102 // A ClassLoaderData created solely for an anonymous class should never have a
103 // ModuleEntryTable or PackageEntryTable created for it. The defining package
104 // and module for an anonymous class will be found in its host class.
105 if (!is_anonymous) {
106 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
107 if (h_class_loader.is_null()) {
108 // Create unnamed module for boot loader
109 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
110 } else {
111 // Create unnamed module for all other loaders
112 _unnamed_module = ModuleEntry::create_unnamed_module(this);
113 }
114 } else {
115 _unnamed_module = NULL;
116 }
117
118 if (!is_anonymous) {
119 _dictionary = create_dictionary();
120 } else {
121 _dictionary = NULL;
122 }
123 TRACE_INIT_ID(this);
124 }
125
126 void ClassLoaderData::init_dependencies(TRAPS) {
127 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
128 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
129 _dependencies.init(CHECK);
130 }
131
132 void ClassLoaderData::Dependencies::init(TRAPS) {
133 // Create empty dependencies array to add to. CMS requires this to be
134 // an oop so that it can track additions via card marks. We think.
135 _list_head = oopFactory::new_objectArray(2, CHECK);
136 }
137
138 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
139 Chunk* c = _head;
140 while (c != NULL) {
141 Chunk* next = c->_next;
142 delete c;
143 c = next;
144 }
145 }
146
147 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
148 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
149 Chunk* next = new Chunk(_head);
150 OrderAccess::release_store(&_head, next);
151 }
152 oop* handle = &_head->_data[_head->_size];
153 *handle = o;
154 OrderAccess::release_store(&_head->_size, _head->_size + 1);
155 return handle;
156 }
157
158 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
159 for (juint i = 0; i < size; i++) {
160 if (c->_data[i] != NULL) {
161 f->do_oop(&c->_data[i]);
162 }
163 }
164 }
165
166 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
167 Chunk* head = OrderAccess::load_acquire(&_head);
168 if (head != NULL) {
169 // Must be careful when reading size of head
170 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
171 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
172 oops_do_chunk(f, c, c->_size);
173 }
174 }
175 }
176
177 #ifdef ASSERT
178 class VerifyContainsOopClosure : public OopClosure {
179 oop* _target;
180 bool _found;
181
182 public:
183 VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {}
184
185 void do_oop(oop* p) {
186 if (p == _target) {
187 _found = true;
188 }
189 }
190
191 void do_oop(narrowOop* p) {
192 // The ChunkedHandleList should not contain any narrowOop
193 ShouldNotReachHere();
194 }
195
196 bool found() const {
197 return _found;
198 }
199 };
200
201 bool ClassLoaderData::ChunkedHandleList::contains(oop* p) {
202 VerifyContainsOopClosure cl(p);
203 oops_do(&cl);
204 return cl.found();
205 }
206 #endif // ASSERT
207
208 bool ClassLoaderData::claim() {
209 if (_claimed == 1) {
210 return false;
211 }
212
213 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
214 }
215
216 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
217 // while the class is being parsed, and if the class appears on the module fixup list.
218 // Due to the uniqueness that no other class shares the anonymous class' name or
219 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
220 // it is being defined, therefore _keep_alive is not volatile or atomic.
221 void ClassLoaderData::inc_keep_alive() {
222 if (is_anonymous()) {
223 assert(_keep_alive >= 0, "Invalid keep alive increment count");
224 _keep_alive++;
225 }
226 }
227
228 void ClassLoaderData::dec_keep_alive() {
229 if (is_anonymous()) {
230 assert(_keep_alive > 0, "Invalid keep alive decrement count");
231 _keep_alive--;
232 }
233 }
234
235 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
236 if (must_claim && !claim()) {
237 return;
238 }
239
240 // Only clear modified_oops after the ClassLoaderData is claimed.
241 if (clear_mod_oops) {
242 clear_modified_oops();
243 }
244
245 f->do_oop(&_class_loader);
246 _dependencies.oops_do(f);
247 _handles.oops_do(f);
248 }
249
250 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
251 f->do_oop((oop*)&_list_head);
252 }
253
254 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
255 // Lock-free access requires load_acquire
256 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
257 klass_closure->do_klass(k);
258 assert(k != k->next_link(), "no loops!");
259 }
260 }
261
262 void ClassLoaderData::classes_do(void f(Klass * const)) {
263 // Lock-free access requires load_acquire
264 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
265 f(k);
266 assert(k != k->next_link(), "no loops!");
267 }
268 }
269
270 void ClassLoaderData::methods_do(void f(Method*)) {
271 // Lock-free access requires load_acquire
272 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
273 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
274 InstanceKlass::cast(k)->methods_do(f);
275 }
276 }
277 }
278
279 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
280 // Lock-free access requires load_acquire
281 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
282 // Do not filter ArrayKlass oops here...
283 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
284 klass_closure->do_klass(k);
285 }
286 }
287 }
288
289 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
290 // Lock-free access requires load_acquire
291 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
292 if (k->is_instance_klass()) {
293 f(InstanceKlass::cast(k));
294 }
295 assert(k != k->next_link(), "no loops!");
296 }
297 }
298
299 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
300 assert_locked_or_safepoint(Module_lock);
301 if (_unnamed_module != NULL) {
302 f(_unnamed_module);
303 }
304 if (_modules != NULL) {
305 for (int i = 0; i < _modules->table_size(); i++) {
306 for (ModuleEntry* entry = _modules->bucket(i);
307 entry != NULL;
308 entry = entry->next()) {
309 f(entry);
310 }
311 }
312 }
313 }
314
315 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
316 assert_locked_or_safepoint(Module_lock);
317 if (_packages != NULL) {
318 for (int i = 0; i < _packages->table_size(); i++) {
319 for (PackageEntry* entry = _packages->bucket(i);
320 entry != NULL;
321 entry = entry->next()) {
322 f(entry);
323 }
324 }
325 }
326 }
327
328 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
329 assert(k != NULL, "invariant");
330
331 ClassLoaderData * const from_cld = this;
332 ClassLoaderData * const to_cld = k->class_loader_data();
333
334 // Dependency to the null class loader data doesn't need to be recorded
335 // because the null class loader data never goes away.
336 if (to_cld->is_the_null_class_loader_data()) {
337 return;
338 }
339
340 oop to;
341 if (to_cld->is_anonymous()) {
342 // Anonymous class dependencies are through the mirror.
343 to = k->java_mirror();
344 } else {
345 to = to_cld->class_loader();
346
347 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
348 // we still have to add it. The class_loader won't keep from_cld alive.
349 if (!from_cld->is_anonymous()) {
350 // Check that this dependency isn't from the same or parent class_loader
351 oop from = from_cld->class_loader();
352
353 oop curr = from;
354 while (curr != NULL) {
355 if (curr == to) {
356 return; // this class loader is in the parent list, no need to add it.
357 }
358 curr = java_lang_ClassLoader::parent(curr);
359 }
360 }
361 }
362
363 // It's a dependency we won't find through GC, add it. This is relatively rare
364 // Must handle over GC point.
365 Handle dependency(THREAD, to);
366 from_cld->_dependencies.add(dependency, CHECK);
367
368 // Added a potentially young gen oop to the ClassLoaderData
369 record_modified_oops();
370 }
371
372
373 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
374 // Check first if this dependency is already in the list.
375 // Save a pointer to the last to add to under the lock.
376 objArrayOop ok = _list_head;
377 objArrayOop last = NULL;
378 while (ok != NULL) {
379 last = ok;
380 if (ok->obj_at(0) == dependency()) {
381 // Don't need to add it
382 return;
383 }
384 ok = (objArrayOop)ok->obj_at(1);
385 }
386
387 // Must handle over GC points
388 assert (last != NULL, "dependencies should be initialized");
389 objArrayHandle last_handle(THREAD, last);
390
391 // Create a new dependency node with fields for (class_loader or mirror, next)
392 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
393 deps->obj_at_put(0, dependency());
394
395 // Must handle over GC points
396 objArrayHandle new_dependency(THREAD, deps);
397
398 // Add the dependency under lock
399 locked_add(last_handle, new_dependency, THREAD);
400 }
401
402 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
403 objArrayHandle new_dependency,
404 Thread* THREAD) {
405
406 // Have to lock and put the new dependency on the end of the dependency
407 // array so the card mark for CMS sees that this dependency is new.
408 // Can probably do this lock free with some effort.
409 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
410
411 oop loader_or_mirror = new_dependency->obj_at(0);
412
413 // Since the dependencies are only added, add to the end.
414 objArrayOop end = last_handle();
415 objArrayOop last = NULL;
416 while (end != NULL) {
417 last = end;
418 // check again if another thread added it to the end.
419 if (end->obj_at(0) == loader_or_mirror) {
420 // Don't need to add it
421 return;
422 }
423 end = (objArrayOop)end->obj_at(1);
424 }
425 assert (last != NULL, "dependencies should be initialized");
426 // fill in the first element with the oop in new_dependency.
427 if (last->obj_at(0) == NULL) {
428 last->obj_at_put(0, new_dependency->obj_at(0));
429 } else {
430 last->obj_at_put(1, new_dependency());
431 }
432 }
433
434 void ClassLoaderDataGraph::clear_claimed_marks() {
435 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
436 cld->clear_claimed();
437 }
438 }
439
440 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
441 {
442 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
443 Klass* old_value = _klasses;
444 k->set_next_link(old_value);
445 // Link the new item into the list, making sure the linked class is stable
446 // since the list can be walked without a lock
447 OrderAccess::release_store(&_klasses, k);
448 }
449
450 if (publicize && k->class_loader_data() != NULL) {
451 ResourceMark rm;
452 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
453 PTR_FORMAT " loader: " PTR_FORMAT " %s",
454 p2i(k),
455 k->external_name(),
456 p2i(k->class_loader_data()),
457 p2i((void *)k->class_loader()),
458 loader_name());
459 }
460 }
461
462 // Class iterator used by the compiler. It gets some number of classes at
463 // a safepoint to decay invocation counters on the methods.
464 class ClassLoaderDataGraphKlassIteratorStatic {
465 ClassLoaderData* _current_loader_data;
466 Klass* _current_class_entry;
467 public:
468
469 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
470
471 InstanceKlass* try_get_next_class() {
472 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
473 int max_classes = InstanceKlass::number_of_instance_classes();
474 assert(max_classes > 0, "should not be called with no instance classes");
475 for (int i = 0; i < max_classes; ) {
476
477 if (_current_class_entry != NULL) {
478 Klass* k = _current_class_entry;
479 _current_class_entry = _current_class_entry->next_link();
480
481 if (k->is_instance_klass()) {
482 InstanceKlass* ik = InstanceKlass::cast(k);
483 i++; // count all instance classes found
484 // Not yet loaded classes are counted in max_classes
485 // but only return loaded classes.
486 if (ik->is_loaded()) {
487 return ik;
488 }
489 }
490 } else {
491 // Go to next CLD
492 if (_current_loader_data != NULL) {
493 _current_loader_data = _current_loader_data->next();
494 }
495 // Start at the beginning
496 if (_current_loader_data == NULL) {
497 _current_loader_data = ClassLoaderDataGraph::_head;
498 }
499
500 _current_class_entry = _current_loader_data->klasses();
501 }
502 }
503 // Should never be reached unless all instance classes have failed or are not fully loaded.
504 // Caller handles NULL.
505 return NULL;
506 }
507
508 // If the current class for the static iterator is a class being unloaded or
509 // deallocated, adjust the current class.
510 void adjust_saved_class(ClassLoaderData* cld) {
511 if (_current_loader_data == cld) {
512 _current_loader_data = cld->next();
513 if (_current_loader_data != NULL) {
514 _current_class_entry = _current_loader_data->klasses();
515 } // else try_get_next_class will start at the head
516 }
517 }
518
519 void adjust_saved_class(Klass* klass) {
520 if (_current_class_entry == klass) {
521 _current_class_entry = klass->next_link();
522 }
523 }
524 };
525
526 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
527
528 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
529 return static_klass_iterator.try_get_next_class();
530 }
531
532
533 // Remove a klass from the _klasses list for scratch_class during redefinition
534 // or parsed class in the case of an error.
535 void ClassLoaderData::remove_class(Klass* scratch_class) {
536 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
537
538 // Adjust global class iterator.
539 static_klass_iterator.adjust_saved_class(scratch_class);
540
541 Klass* prev = NULL;
542 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
543 if (k == scratch_class) {
544 if (prev == NULL) {
545 _klasses = k->next_link();
546 } else {
547 Klass* next = k->next_link();
548 prev->set_next_link(next);
549 }
550 return;
551 }
552 prev = k;
553 assert(k != k->next_link(), "no loops!");
554 }
555 ShouldNotReachHere(); // should have found this class!!
556 }
557
558 void ClassLoaderData::unload() {
559 _unloading = true;
560
561 // Tell serviceability tools these classes are unloading
562 classes_do(InstanceKlass::notify_unload_class);
563
564 LogTarget(Debug, class, loader, data) lt;
565 if (lt.is_enabled()) {
566 ResourceMark rm;
567 LogStream ls(lt);
568 ls.print(": unload loader data " INTPTR_FORMAT, p2i(this));
569 ls.print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
570 loader_name());
571 if (is_anonymous()) {
572 ls.print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
573 }
574 ls.cr();
575 }
576
577 // Some items on the _deallocate_list need to free their C heap structures
578 // if they are not already on the _klasses list.
579 unload_deallocate_list();
580
581 // Clean up global class iterator for compiler
582 static_klass_iterator.adjust_saved_class(this);
583 }
584
585 ModuleEntryTable* ClassLoaderData::modules() {
586 // Lazily create the module entry table at first request.
587 // Lock-free access requires load_acquire.
588 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
589 if (modules == NULL) {
590 MutexLocker m1(Module_lock);
591 // Check if _modules got allocated while we were waiting for this lock.
592 if ((modules = _modules) == NULL) {
593 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
594
595 {
596 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
597 // Ensure _modules is stable, since it is examined without a lock
598 OrderAccess::release_store(&_modules, modules);
599 }
600 }
601 }
602 return modules;
603 }
604
605 const int _boot_loader_dictionary_size = 1009;
606 const int _default_loader_dictionary_size = 107;
607
608 Dictionary* ClassLoaderData::create_dictionary() {
609 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
610 int size;
611 bool resizable = false;
612 if (_the_null_class_loader_data == NULL) {
613 size = _boot_loader_dictionary_size;
614 resizable = true;
615 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
616 size = 1; // there's only one class in relection class loader and no initiated classes
617 } else if (is_system_class_loader_data()) {
618 size = _boot_loader_dictionary_size;
619 resizable = true;
620 } else {
621 size = _default_loader_dictionary_size;
622 resizable = true;
623 }
624 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) {
625 resizable = false;
626 }
627 return new Dictionary(this, size, resizable);
628 }
629
630 // Unloading support
631 oop ClassLoaderData::keep_alive_object() const {
632 assert_locked_or_safepoint(_metaspace_lock);
633 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
634 return is_anonymous() ? _klasses->java_mirror() : class_loader();
635 }
636
637 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
638 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
639 || is_alive_closure->do_object_b(keep_alive_object());
640
641 return alive;
642 }
643
644 ClassLoaderData::~ClassLoaderData() {
645 // Release C heap structures for all the classes.
646 classes_do(InstanceKlass::release_C_heap_structures);
647
648 // Release C heap allocated hashtable for all the packages.
649 if (_packages != NULL) {
650 // Destroy the table itself
651 delete _packages;
652 _packages = NULL;
653 }
654
655 // Release C heap allocated hashtable for all the modules.
656 if (_modules != NULL) {
657 // Destroy the table itself
658 delete _modules;
659 _modules = NULL;
660 }
661
662 // Release C heap allocated hashtable for the dictionary
663 if (_dictionary != NULL) {
664 // Destroy the table itself
665 delete _dictionary;
666 _dictionary = NULL;
667 }
668
669 if (_unnamed_module != NULL) {
670 _unnamed_module->delete_unnamed_module();
671 _unnamed_module = NULL;
672 }
673
674 // release the metaspace
675 Metaspace *m = _metaspace;
676 if (m != NULL) {
677 _metaspace = NULL;
678 delete m;
679 }
680 // Clear all the JNI handles for methods
681 // These aren't deallocated and are going to look like a leak, but that's
682 // needed because we can't really get rid of jmethodIDs because we don't
683 // know when native code is going to stop using them. The spec says that
684 // they're "invalid" but existing programs likely rely on their being
685 // NULL after class unloading.
686 if (_jmethod_ids != NULL) {
687 Method::clear_jmethod_ids(this);
688 }
689 // Delete lock
690 delete _metaspace_lock;
691
692 // Delete free list
693 if (_deallocate_list != NULL) {
694 delete _deallocate_list;
695 }
696 }
697
698 // Returns true if this class loader data is for the system class loader.
699 bool ClassLoaderData::is_system_class_loader_data() const {
700 return SystemDictionary::is_system_class_loader(class_loader());
701 }
702
703 // Returns true if this class loader data is for the platform class loader.
704 bool ClassLoaderData::is_platform_class_loader_data() const {
705 return SystemDictionary::is_platform_class_loader(class_loader());
706 }
707
708 // Returns true if this class loader data is one of the 3 builtin
709 // (boot, application/system or platform) class loaders. Note, the
710 // builtin loaders are not freed by a GC.
711 bool ClassLoaderData::is_builtin_class_loader_data() const {
712 return (is_the_null_class_loader_data() ||
713 SystemDictionary::is_system_class_loader(class_loader()) ||
714 SystemDictionary::is_platform_class_loader(class_loader()));
715 }
716
717 Metaspace* ClassLoaderData::metaspace_non_null() {
718 // If the metaspace has not been allocated, create a new one. Might want
719 // to create smaller arena for Reflection class loaders also.
720 // The reason for the delayed allocation is because some class loaders are
721 // simply for delegating with no metadata of their own.
722 // Lock-free access requires load_acquire.
723 Metaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
724 if (metaspace == NULL) {
725 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
726 // Check if _metaspace got allocated while we were waiting for this lock.
727 if ((metaspace = _metaspace) == NULL) {
728 if (this == the_null_class_loader_data()) {
729 assert (class_loader() == NULL, "Must be");
730 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
731 } else if (is_anonymous()) {
732 if (class_loader() != NULL) {
733 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
734 }
735 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
736 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
737 if (class_loader() != NULL) {
738 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
739 }
740 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
741 } else {
742 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
743 }
744 // Ensure _metaspace is stable, since it is examined without a lock
745 OrderAccess::release_store(&_metaspace, metaspace);
746 }
747 }
748 return metaspace;
749 }
750
751 OopHandle ClassLoaderData::add_handle(Handle h) {
752 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
753 record_modified_oops();
754 return OopHandle(_handles.add(h()));
755 }
756
757 void ClassLoaderData::remove_handle(OopHandle h) {
758 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
759 oop* ptr = h.ptr_raw();
760 if (ptr != NULL) {
761 assert(_handles.contains(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
762 #if INCLUDE_ALL_GCS
763 // This barrier is used by G1 to remember the old oop values, so
764 // that we don't forget any objects that were live at the snapshot at
765 // the beginning.
766 if (UseG1GC) {
767 oop obj = *ptr;
768 if (obj != NULL) {
769 G1SATBCardTableModRefBS::enqueue(obj);
770 }
771 }
772 #endif
773 *ptr = NULL;
774 }
775 }
776
777 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
778 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
779 if (dest.resolve() != NULL) {
780 return;
781 } else {
782 dest = _handles.add(h());
783 }
784 }
785
786 // Add this metadata pointer to be freed when it's safe. This is only during
787 // class unloading because Handles might point to this metadata field.
788 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
789 // Metadata in shared region isn't deleted.
790 if (!m->is_shared()) {
791 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
792 if (_deallocate_list == NULL) {
793 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
794 }
795 _deallocate_list->append_if_missing(m);
796 }
797 }
798
799 // Deallocate free metadata on the free list. How useful the PermGen was!
800 void ClassLoaderData::free_deallocate_list() {
801 // Don't need lock, at safepoint
802 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
803 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
804 if (_deallocate_list == NULL) {
805 return;
806 }
807 // Go backwards because this removes entries that are freed.
808 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
809 Metadata* m = _deallocate_list->at(i);
810 if (!m->on_stack()) {
811 _deallocate_list->remove_at(i);
812 // There are only three types of metadata that we deallocate directly.
813 // Cast them so they can be used by the template function.
814 if (m->is_method()) {
815 MetadataFactory::free_metadata(this, (Method*)m);
816 } else if (m->is_constantPool()) {
817 MetadataFactory::free_metadata(this, (ConstantPool*)m);
818 } else if (m->is_klass()) {
819 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
820 } else {
821 ShouldNotReachHere();
822 }
823 } else {
824 // Metadata is alive.
825 // If scratch_class is on stack then it shouldn't be on this list!
826 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
827 "scratch classes on this list should be dead");
828 // Also should assert that other metadata on the list was found in handles.
829 }
830 }
831 }
832
833 // This is distinct from free_deallocate_list. For class loader data that are
834 // unloading, this frees the C heap memory for constant pools on the list. If there
835 // were C heap memory allocated for methods, it would free that too. The C heap memory
836 // for InstanceKlasses on this list is freed in the ClassLoaderData destructor.
837 void ClassLoaderData::unload_deallocate_list() {
838 // Don't need lock, at safepoint
839 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
840 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
841 if (_deallocate_list == NULL) {
842 return;
843 }
844 // Go backwards because this removes entries that are freed.
845 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
846 Metadata* m = _deallocate_list->at(i);
847 assert (!m->on_stack(), "wouldn't be unloading if this were so");
848 _deallocate_list->remove_at(i);
849 // Only constant pool entries have C heap memory to free.
850 if (m->is_constantPool()) {
851 ((ConstantPool*)m)->release_C_heap_structures();
852 }
853 }
854 }
855
856 // These anonymous class loaders are to contain classes used for JSR292
857 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
858 // Add a new class loader data to the graph.
859 Handle lh(THREAD, loader);
860 return ClassLoaderDataGraph::add(lh, true, THREAD);
861 }
862
863 const char* ClassLoaderData::loader_name() {
864 // Handles null class loader
865 return SystemDictionary::loader_name(class_loader());
866 }
867
868 #ifndef PRODUCT
869 // Define to dump klasses
870 #undef CLD_DUMP_KLASSES
871
872 void ClassLoaderData::dump(outputStream * const out) {
873 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
874 p2i(this), p2i((void *)class_loader()),
875 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
876 if (claimed()) out->print(" claimed ");
877 if (is_unloading()) out->print(" unloading ");
878 out->cr();
879 if (metaspace_or_null() != NULL) {
880 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
881 metaspace_or_null()->dump(out);
882 } else {
883 out->print_cr("metaspace: NULL");
884 }
885
886 #ifdef CLD_DUMP_KLASSES
887 if (Verbose) {
888 Klass* k = _klasses;
889 while (k != NULL) {
890 out->print_cr("klass " PTR_FORMAT ", %s", p2i(k), k->name()->as_C_string());
891 assert(k != k->next_link(), "no loops!");
892 k = k->next_link();
893 }
894 }
895 #endif // CLD_DUMP_KLASSES
896 #undef CLD_DUMP_KLASSES
897 if (_jmethod_ids != NULL) {
898 Method::print_jmethod_ids(this, out);
899 }
900 out->print_cr("}");
901 }
902 #endif // PRODUCT
903
904 void ClassLoaderData::verify() {
905 assert_locked_or_safepoint(_metaspace_lock);
906 oop cl = class_loader();
907
908 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
909 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
910
911 // Verify the integrity of the allocated space.
912 if (metaspace_or_null() != NULL) {
913 metaspace_or_null()->verify();
914 }
915
916 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
917 guarantee(k->class_loader_data() == this, "Must be the same");
918 k->verify();
919 assert(k != k->next_link(), "no loops!");
920 }
921 }
922
923 bool ClassLoaderData::contains_klass(Klass* klass) {
924 // Lock-free access requires load_acquire
925 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
926 if (k == klass) return true;
927 }
928 return false;
929 }
930
931
932 // GC root of class loader data created.
933 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
934 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
935 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
936 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
937
938 bool ClassLoaderDataGraph::_should_purge = false;
939 bool ClassLoaderDataGraph::_metaspace_oom = false;
940
941 // Add a new class loader data node to the list. Assign the newly created
942 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
943 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
944 // We need to allocate all the oops for the ClassLoaderData before allocating the
945 // actual ClassLoaderData object.
946 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
947
948 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
949 // ClassLoaderData in the graph since the CLD
950 // contains unhandled oops
951
952 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
953
954
955 if (!is_anonymous) {
956 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
957 // First, Atomically set it
958 ClassLoaderData* old = Atomic::cmpxchg(cld, cld_addr, (ClassLoaderData*)NULL);
959 if (old != NULL) {
960 delete cld;
961 // Returns the data.
962 return old;
963 }
964 }
965
966 // We won the race, and therefore the task of adding the data to the list of
967 // class loader data
968 ClassLoaderData** list_head = &_head;
969 ClassLoaderData* next = _head;
970
971 do {
972 cld->set_next(next);
973 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next);
974 if (exchanged == next) {
975 LogTarget(Debug, class, loader, data) lt;
976 if (lt.is_enabled()) {
977 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
978 LogStream ls(lt);
979 print_creation(&ls, loader, cld, CHECK_NULL);
980 }
981 return cld;
982 }
983 next = exchanged;
984 } while (true);
985 }
986
987 void ClassLoaderDataGraph::print_creation(outputStream* out, Handle loader, ClassLoaderData* cld, TRAPS) {
988 Handle string;
989 if (loader.not_null()) {
990 // Include the result of loader.toString() in the output. This allows
991 // the user of the log to identify the class loader instance.
992 JavaValue result(T_OBJECT);
993 Klass* spec_klass = SystemDictionary::ClassLoader_klass();
994 JavaCalls::call_virtual(&result,
995 loader,
996 spec_klass,
997 vmSymbols::toString_name(),
998 vmSymbols::void_string_signature(),
999 CHECK);
1000 assert(result.get_type() == T_OBJECT, "just checking");
1001 string = Handle(THREAD, (oop)result.get_jobject());
1002 }
1003
1004 ResourceMark rm;
1005 out->print("create class loader data " INTPTR_FORMAT, p2i(cld));
1006 out->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
1007 cld->loader_name());
1008
1009 if (string.not_null()) {
1010 out->print(": ");
1011 java_lang_String::print(string(), out);
1012 }
1013 out->cr();
1014 }
1015
1016
1017 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1018 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1019 cld->oops_do(f, must_claim);
1020 }
1021 }
1022
1023 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1024 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1025 if (cld->keep_alive()) {
1026 cld->oops_do(f, must_claim);
1027 }
1028 }
1029 }
1030
1031 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1032 if (ClassUnloading) {
1033 keep_alive_oops_do(f, must_claim);
1034 } else {
1035 oops_do(f, must_claim);
1036 }
1037 }
1038
1039 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1040 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1041 cl->do_cld(cld);
1042 }
1043 }
1044
1045 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1046 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1047 // Only walk the head until any clds not purged from prior unloading
1048 // (CMS doesn't purge right away).
1049 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1050 assert(cld->is_unloading(), "invariant");
1051 cl->do_cld(cld);
1052 }
1053 }
1054
1055 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1056 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1057 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1058 if (closure != NULL) {
1059 closure->do_cld(cld);
1060 }
1061 }
1062 }
1063
1064 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1065 roots_cld_do(cl, NULL);
1066 }
1067
1068 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1069 if (ClassUnloading) {
1070 keep_alive_cld_do(cl);
1071 } else {
1072 cld_do(cl);
1073 }
1074 }
1075
1076 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1077 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1078 cld->classes_do(klass_closure);
1079 }
1080 }
1081
1082 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1083 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1084 cld->classes_do(f);
1085 }
1086 }
1087
1088 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1089 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1090 cld->methods_do(f);
1091 }
1092 }
1093
1094 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1095 assert_locked_or_safepoint(Module_lock);
1096 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1097 cld->modules_do(f);
1098 }
1099 }
1100
1101 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
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->modules_do(f);
1108 }
1109 }
1110
1111 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1112 assert_locked_or_safepoint(Module_lock);
1113 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1114 cld->packages_do(f);
1115 }
1116 }
1117
1118 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1119 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1120 // Only walk the head until any clds not purged from prior unloading
1121 // (CMS doesn't purge right away).
1122 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1123 assert(cld->is_unloading(), "invariant");
1124 cld->packages_do(f);
1125 }
1126 }
1127
1128 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1129 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1130 cld->loaded_classes_do(klass_closure);
1131 }
1132 }
1133
1134 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1135 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1136 // Only walk the head until any clds not purged from prior unloading
1137 // (CMS doesn't purge right away).
1138 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1139 assert(cld->is_unloading(), "invariant");
1140 cld->classes_do(f);
1141 }
1142 }
1143
1144 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1145 if (X->dictionary() != NULL)
1146
1147 // Walk classes in the loaded class dictionaries in various forms.
1148 // Only walks the classes defined in this class loader.
1149 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1150 FOR_ALL_DICTIONARY(cld) {
1151 cld->dictionary()->classes_do(f);
1152 }
1153 }
1154
1155 // Only walks the classes defined in this class loader.
1156 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1157 FOR_ALL_DICTIONARY(cld) {
1158 cld->dictionary()->classes_do(f, CHECK);
1159 }
1160 }
1161
1162 // Walks all entries in the dictionary including entries initiated by this class loader.
1163 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1164 FOR_ALL_DICTIONARY(cld) {
1165 cld->dictionary()->all_entries_do(f);
1166 }
1167 }
1168
1169 void ClassLoaderDataGraph::verify_dictionary() {
1170 FOR_ALL_DICTIONARY(cld) {
1171 cld->dictionary()->verify();
1172 }
1173 }
1174
1175 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1176 FOR_ALL_DICTIONARY(cld) {
1177 st->print("Dictionary for ");
1178 cld->print_value_on(st);
1179 st->cr();
1180 cld->dictionary()->print_on(st);
1181 st->cr();
1182 }
1183 }
1184
1185 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1186 FOR_ALL_DICTIONARY(cld) {
1187 ResourceMark rm;
1188 stringStream tempst;
1189 tempst.print("System Dictionary for %s", cld->loader_name());
1190 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1191 }
1192 }
1193
1194 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1195 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1196
1197 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1198
1199 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1200 ClassLoaderData* curr = _head;
1201 while (curr != _saved_head) {
1202 if (!curr->claimed()) {
1203 array->push(curr);
1204 LogTarget(Debug, class, loader, data) lt;
1205 if (lt.is_enabled()) {
1206 LogStream ls(lt);
1207 ls.print("found new CLD: ");
1208 curr->print_value_on(&ls);
1209 ls.cr();
1210 }
1211 }
1212
1213 curr = curr->_next;
1214 }
1215
1216 return array;
1217 }
1218
1219 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
1220 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
1221 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
1222 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
1223 return true;
1224 }
1225 }
1226 return false;
1227 }
1228
1229 #ifndef PRODUCT
1230 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1231 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1232 if (loader_data == data) {
1233 return true;
1234 }
1235 }
1236
1237 return false;
1238 }
1239 #endif // PRODUCT
1240
1241
1242 // Move class loader data from main list to the unloaded list for unloading
1243 // and deallocation later.
1244 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
1245 bool clean_previous_versions) {
1246
1247 ClassLoaderData* data = _head;
1248 ClassLoaderData* prev = NULL;
1249 bool seen_dead_loader = false;
1250
1251 // Mark metadata seen on the stack only so we can delete unneeded entries.
1252 // Only walk all metadata, including the expensive code cache walk, for Full GC
1253 // and only if class redefinition and if there's previous versions of
1254 // Klasses to delete.
1255 bool walk_all_metadata = clean_previous_versions &&
1256 JvmtiExport::has_redefined_a_class() &&
1257 InstanceKlass::has_previous_versions_and_reset();
1258 MetadataOnStackMark md_on_stack(walk_all_metadata);
1259
1260 // Save previous _unloading pointer for CMS which may add to unloading list before
1261 // purging and we don't want to rewalk the previously unloaded class loader data.
1262 _saved_unloading = _unloading;
1263
1264 data = _head;
1265 while (data != NULL) {
1266 if (data->is_alive(is_alive_closure)) {
1267 // clean metaspace
1268 if (walk_all_metadata) {
1269 data->classes_do(InstanceKlass::purge_previous_versions);
1270 }
1271 data->free_deallocate_list();
1272 prev = data;
1273 data = data->next();
1274 continue;
1275 }
1276 seen_dead_loader = true;
1277 ClassLoaderData* dead = data;
1278 dead->unload();
1279 data = data->next();
1280 // Remove from loader list.
1281 // This class loader data will no longer be found
1282 // in the ClassLoaderDataGraph.
1283 if (prev != NULL) {
1284 prev->set_next(data);
1285 } else {
1286 assert(dead == _head, "sanity check");
1287 _head = data;
1288 }
1289 dead->set_next(_unloading);
1290 _unloading = dead;
1291 }
1292
1293 if (seen_dead_loader) {
1294 data = _head;
1295 while (data != NULL) {
1296 // Remove entries in the dictionary of live class loader that have
1297 // initiated loading classes in a dead class loader.
1298 if (data->dictionary() != NULL) {
1299 data->dictionary()->do_unloading();
1300 }
1301 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1302 // lists to determine if there are modules on those lists that are now
1303 // dead and should be removed. A module's life cycle is equivalent
1304 // to its defining class loader's life cycle. Since a module is
1305 // considered dead if its class loader is dead, these walks must
1306 // occur after each class loader's aliveness is determined.
1307 if (data->packages() != NULL) {
1308 data->packages()->purge_all_package_exports();
1309 }
1310 if (data->modules_defined()) {
1311 data->modules()->purge_all_module_reads();
1312 }
1313 data = data->next();
1314 }
1315
1316 post_class_unload_events();
1317 }
1318
1319 return seen_dead_loader;
1320 }
1321
1322 void ClassLoaderDataGraph::purge() {
1323 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1324 ClassLoaderData* list = _unloading;
1325 _unloading = NULL;
1326 ClassLoaderData* next = list;
1327 bool classes_unloaded = false;
1328 while (next != NULL) {
1329 ClassLoaderData* purge_me = next;
1330 next = purge_me->next();
1331 delete purge_me;
1332 classes_unloaded = true;
1333 }
1334 if (classes_unloaded) {
1335 Metaspace::purge();
1336 set_metaspace_oom(false);
1337 }
1338 }
1339
1340 int ClassLoaderDataGraph::resize_if_needed() {
1341 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1342 int resized = 0;
1343 if (Dictionary::does_any_dictionary_needs_resizing()) {
1344 FOR_ALL_DICTIONARY(cld) {
1345 if (cld->dictionary()->resize_if_needed()) {
1346 resized++;
1347 }
1348 }
1349 }
1350 return resized;
1351 }
1352
1353 void ClassLoaderDataGraph::post_class_unload_events() {
1354 #if INCLUDE_TRACE
1355 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1356 if (Tracing::enabled()) {
1357 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1358 assert(_unloading != NULL, "need class loader data unload list!");
1359 _class_unload_time = Ticks::now();
1360 classes_unloading_do(&class_unload_event);
1361 }
1362 Tracing::on_unloading_classes();
1363 }
1364 #endif
1365 }
1366
1367 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1368 : _next_klass(NULL) {
1369 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1370 Klass* klass = NULL;
1371
1372 // Find the first klass in the CLDG.
1373 while (cld != NULL) {
1374 assert_locked_or_safepoint(cld->metaspace_lock());
1375 klass = cld->_klasses;
1376 if (klass != NULL) {
1377 _next_klass = klass;
1378 return;
1379 }
1380 cld = cld->next();
1381 }
1382 }
1383
1384 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1385 Klass* next = klass->next_link();
1386 if (next != NULL) {
1387 return next;
1388 }
1389
1390 // No more klasses in the current CLD. Time to find a new CLD.
1391 ClassLoaderData* cld = klass->class_loader_data();
1392 assert_locked_or_safepoint(cld->metaspace_lock());
1393 while (next == NULL) {
1394 cld = cld->next();
1395 if (cld == NULL) {
1396 break;
1397 }
1398 next = cld->_klasses;
1399 }
1400
1401 return next;
1402 }
1403
1404 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1405 Klass* head = _next_klass;
1406
1407 while (head != NULL) {
1408 Klass* next = next_klass_in_cldg(head);
1409
1410 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1411
1412 if (old_head == head) {
1413 return head; // Won the CAS.
1414 }
1415
1416 head = old_head;
1417 }
1418
1419 // Nothing more for the iterator to hand out.
1420 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1421 return NULL;
1422 }
1423
1424 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1425 _data = ClassLoaderDataGraph::_head;
1426 }
1427
1428 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1429
1430 #ifndef PRODUCT
1431 // callable from debugger
1432 extern "C" int print_loader_data_graph() {
1433 ClassLoaderDataGraph::dump_on(tty);
1434 return 0;
1435 }
1436
1437 void ClassLoaderDataGraph::verify() {
1438 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1439 data->verify();
1440 }
1441 }
1442
1443 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1444 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1445 data->dump(out);
1446 }
1447 MetaspaceAux::dump(out);
1448 }
1449 #endif // PRODUCT
1450
1451 void ClassLoaderData::print_value_on(outputStream* out) const {
1452 if (class_loader() == NULL) {
1453 out->print("NULL class loader");
1454 } else {
1455 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1456 class_loader()->print_value_on(out);
1457 }
1458 }
1459
1460 void ClassLoaderData::print_on(outputStream* out) const {
1461 if (class_loader() == NULL) {
1462 out->print("NULL class loader");
1463 } else {
1464 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1465 class_loader()->print_on(out);
1466 }
1467 }
1468
1469 #if INCLUDE_TRACE
1470
1471 Ticks ClassLoaderDataGraph::_class_unload_time;
1472
1473 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1474 assert(k != NULL, "invariant");
1475
1476 // post class unload event
1477 EventClassUnload event(UNTIMED);
1478 event.set_endtime(_class_unload_time);
1479 event.set_unloadedClass(k);
1480 event.set_definingClassLoader(k->class_loader_data());
1481 event.commit();
1482 }
1483
1484 #endif // INCLUDE_TRACE