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/symbolTable.hpp"
58 #include "classfile/systemDictionary.hpp"
59 #include "logging/log.hpp"
60 #include "logging/logStream.hpp"
61 #include "memory/allocation.inline.hpp"
62 #include "memory/metadataFactory.hpp"
63 #include "memory/metaspaceShared.hpp"
64 #include "memory/resourceArea.hpp"
65 #include "memory/universe.hpp"
66 #include "oops/access.inline.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "oops/oopHandle.inline.hpp"
69 #include "oops/weakHandle.inline.hpp"
70 #include "runtime/atomic.hpp"
71 #include "runtime/handles.inline.hpp"
72 #include "runtime/mutex.hpp"
73 #include "runtime/orderAccess.hpp"
74 #include "runtime/safepoint.hpp"
75 #include "runtime/safepointVerifiers.hpp"
76 #include "utilities/growableArray.hpp"
77 #include "utilities/macros.hpp"
78 #include "utilities/ostream.hpp"
79 #include "utilities/ticks.hpp"
80 #if INCLUDE_JFR
81 #include "jfr/jfr.hpp"
82 #include "jfr/jfrEvents.hpp"
83 #endif
84
85 volatile size_t ClassLoaderDataGraph::_num_array_classes = 0;
86 volatile size_t ClassLoaderDataGraph::_num_instance_classes = 0;
87
88 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
89
90 void ClassLoaderData::init_null_class_loader_data() {
91 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
92 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
93
94 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
95 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
96 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
97
98 LogTarget(Debug, class, loader, data) lt;
99 if (lt.is_enabled()) {
100 ResourceMark rm;
101 LogStream ls(lt);
102 ls.print("create ");
103 _the_null_class_loader_data->print_value_on(&ls);
104 ls.cr();
105 }
106 }
107
108 // Obtain and set the class loader's name within the ClassLoaderData so
109 // it will be available for error messages, logging, JFR, etc. The name
110 // and klass are available after the class_loader oop is no longer alive,
111 // during unloading.
112 void ClassLoaderData::initialize_name(Handle class_loader) {
113 Thread* THREAD = Thread::current();
114 ResourceMark rm(THREAD);
115
116 // Obtain the class loader's name. If the class loader's name was not
117 // explicitly set during construction, the CLD's _name field will be null.
118 oop cl_name = java_lang_ClassLoader::name(class_loader());
119 if (cl_name != NULL) {
120 const char* cl_instance_name = java_lang_String::as_utf8_string(cl_name);
121
122 if (cl_instance_name != NULL && cl_instance_name[0] != '\0') {
123 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore.
124 _name = SymbolTable::new_symbol(cl_instance_name, CATCH);
125 }
126 }
127
128 // Obtain the class loader's name and identity hash. If the class loader's
129 // name was not explicitly set during construction, the class loader's name and id
130 // will be set to the qualified class name of the class loader along with its
131 // identity hash.
132 // If for some reason the ClassLoader's constructor has not been run, instead of
133 // leaving the _name_and_id field null, fall back to the external qualified class
134 // name. Thus CLD's _name_and_id field should never have a null value.
135 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader());
136 const char* cl_instance_name_and_id =
137 (cl_name_and_id == NULL) ? _class_loader_klass->external_name() :
138 java_lang_String::as_utf8_string(cl_name_and_id);
139 assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id");
140 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore.
141 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id, CATCH);
142 }
143
144 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous) :
145 _is_anonymous(is_anonymous),
146 // An anonymous class loader data doesn't have anything to keep
147 // it from being unloaded during parsing of the anonymous class.
148 // The null-class-loader should always be kept alive.
149 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
150 _metaspace(NULL), _unloading(false), _klasses(NULL),
151 _modules(NULL), _packages(NULL), _unnamed_module(NULL), _dictionary(NULL),
152 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false),
153 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
154 _next(NULL),
155 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL),
156 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
157 Monitor::_safepoint_check_never)) {
158
159 if (!h_class_loader.is_null()) {
160 _class_loader = _handles.add(h_class_loader());
161 }
162
163 if (!h_class_loader.is_null()) {
164 _class_loader_klass = h_class_loader->klass();
165 }
166
167 if (!is_anonymous) {
168 // The holder is initialized later for anonymous classes, and before calling anything
169 // that call class_loader().
170 initialize_holder(h_class_loader);
171
172 // A ClassLoaderData created solely for an anonymous class should never have a
173 // ModuleEntryTable or PackageEntryTable created for it. The defining package
174 // and module for an anonymous class will be found in its host class.
175 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
176 if (h_class_loader.is_null()) {
177 // Create unnamed module for boot loader
178 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
179 } else {
180 // Create unnamed module for all other loaders
181 _unnamed_module = ModuleEntry::create_unnamed_module(this);
182 }
183 _dictionary = create_dictionary();
184 }
185
186 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
187
188 JFR_ONLY(INIT_ID(this);)
189 }
190
191 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
192 Chunk* c = _head;
193 while (c != NULL) {
194 Chunk* next = c->_next;
195 delete c;
196 c = next;
197 }
198 }
199
200 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
201 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
202 Chunk* next = new Chunk(_head);
203 OrderAccess::release_store(&_head, next);
204 }
205 oop* handle = &_head->_data[_head->_size];
206 *handle = o;
207 OrderAccess::release_store(&_head->_size, _head->_size + 1);
208 return handle;
209 }
210
211 int ClassLoaderData::ChunkedHandleList::count() const {
212 int count = 0;
213 Chunk* chunk = _head;
214 while (chunk != NULL) {
215 count += chunk->_size;
216 chunk = chunk->_next;
217 }
218 return count;
219 }
220
221 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
222 for (juint i = 0; i < size; i++) {
223 if (c->_data[i] != NULL) {
224 f->do_oop(&c->_data[i]);
225 }
226 }
227 }
228
229 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
230 Chunk* head = OrderAccess::load_acquire(&_head);
231 if (head != NULL) {
232 // Must be careful when reading size of head
233 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
234 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
235 oops_do_chunk(f, c, c->_size);
236 }
237 }
238 }
239
240 class VerifyContainsOopClosure : public OopClosure {
241 oop _target;
242 bool _found;
243
244 public:
245 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
246
247 void do_oop(oop* p) {
248 if (p != NULL && oopDesc::equals(RawAccess<>::oop_load(p), _target)) {
249 _found = true;
250 }
251 }
252
253 void do_oop(narrowOop* p) {
254 // The ChunkedHandleList should not contain any narrowOop
255 ShouldNotReachHere();
256 }
257
258 bool found() const {
259 return _found;
260 }
261 };
262
263 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
264 VerifyContainsOopClosure cl(p);
265 oops_do(&cl);
266 return cl.found();
267 }
268
269 #ifndef PRODUCT
270 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
271 Chunk* chunk = _head;
272 while (chunk != NULL) {
273 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
274 return true;
275 }
276 chunk = chunk->_next;
277 }
278 return false;
279 }
280 #endif // PRODUCT
281
282 bool ClassLoaderData::claim() {
283 if (_claimed == 1) {
284 return false;
285 }
286
287 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
288 }
289
290 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
291 // while the class is being parsed, and if the class appears on the module fixup list.
292 // Due to the uniqueness that no other class shares the anonymous class' name or
293 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
294 // it is being defined, therefore _keep_alive is not volatile or atomic.
295 void ClassLoaderData::inc_keep_alive() {
296 if (is_anonymous()) {
297 assert(_keep_alive >= 0, "Invalid keep alive increment count");
298 _keep_alive++;
299 }
300 }
301
302 void ClassLoaderData::dec_keep_alive() {
303 if (is_anonymous()) {
304 assert(_keep_alive > 0, "Invalid keep alive decrement count");
305 _keep_alive--;
306 }
307 }
308
309 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
310 if (must_claim && !claim()) {
311 return;
312 }
313
314 // Only clear modified_oops after the ClassLoaderData is claimed.
315 if (clear_mod_oops) {
316 clear_modified_oops();
317 }
318
319 _handles.oops_do(f);
320 }
321
322 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
323 // Lock-free access requires load_acquire
324 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
325 klass_closure->do_klass(k);
326 assert(k != k->next_link(), "no loops!");
327 }
328 }
329
330 void ClassLoaderData::classes_do(void f(Klass * const)) {
331 // Lock-free access requires load_acquire
332 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
333 f(k);
334 assert(k != k->next_link(), "no loops!");
335 }
336 }
337
338 void ClassLoaderData::methods_do(void f(Method*)) {
339 // Lock-free access requires load_acquire
340 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
341 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
342 InstanceKlass::cast(k)->methods_do(f);
343 }
344 }
345 }
346
347 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
348 // Lock-free access requires load_acquire
349 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
350 // Do not filter ArrayKlass oops here...
351 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
352 klass_closure->do_klass(k);
353 }
354 }
355 }
356
357 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
358 // Lock-free access requires load_acquire
359 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
360 if (k->is_instance_klass()) {
361 f(InstanceKlass::cast(k));
362 }
363 assert(k != k->next_link(), "no loops!");
364 }
365 }
366
367 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
368 assert_locked_or_safepoint(Module_lock);
369 if (_unnamed_module != NULL) {
370 f(_unnamed_module);
371 }
372 if (_modules != NULL) {
373 for (int i = 0; i < _modules->table_size(); i++) {
374 for (ModuleEntry* entry = _modules->bucket(i);
375 entry != NULL;
376 entry = entry->next()) {
377 f(entry);
378 }
379 }
380 }
381 }
382
383 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
384 assert_locked_or_safepoint(Module_lock);
385 if (_packages != NULL) {
386 for (int i = 0; i < _packages->table_size(); i++) {
387 for (PackageEntry* entry = _packages->bucket(i);
388 entry != NULL;
389 entry = entry->next()) {
390 f(entry);
391 }
392 }
393 }
394 }
395
396 void ClassLoaderData::record_dependency(const Klass* k) {
397 assert(k != NULL, "invariant");
398
399 ClassLoaderData * const from_cld = this;
400 ClassLoaderData * const to_cld = k->class_loader_data();
401
402 // Do not need to record dependency if the dependency is to a class whose
403 // class loader data is never freed. (i.e. the dependency's class loader
404 // is one of the three builtin class loaders and the dependency is not
405 // anonymous.)
406 if (to_cld->is_permanent_class_loader_data()) {
407 return;
408 }
409
410 oop to;
411 if (to_cld->is_anonymous()) {
412 // Just return if an anonymous class is attempting to record a dependency
413 // to itself. (Note that every anonymous class has its own unique class
414 // loader data.)
415 if (to_cld == from_cld) {
416 return;
417 }
418 // Anonymous class dependencies are through the mirror.
419 to = k->java_mirror();
420 } else {
421 to = to_cld->class_loader();
422 oop from = from_cld->class_loader();
423
424 // Just return if this dependency is to a class with the same or a parent
425 // class_loader.
426 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) {
427 return; // this class loader is in the parent list, no need to add it.
428 }
429 }
430
431 // It's a dependency we won't find through GC, add it.
432 if (!_handles.contains(to)) {
433 NOT_PRODUCT(Atomic::inc(&_dependency_count));
434 LogTarget(Trace, class, loader, data) lt;
435 if (lt.is_enabled()) {
436 ResourceMark rm;
437 LogStream ls(lt);
438 ls.print("adding dependency from ");
439 print_value_on(&ls);
440 ls.print(" to ");
441 to_cld->print_value_on(&ls);
442 ls.cr();
443 }
444 Handle dependency(Thread::current(), to);
445 add_handle(dependency);
446 // Added a potentially young gen oop to the ClassLoaderData
447 record_modified_oops();
448 }
449 }
450
451
452 void ClassLoaderDataGraph::clear_claimed_marks() {
453 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
454 cld->clear_claimed();
455 }
456 }
457
458 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
459 {
460 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
461 Klass* old_value = _klasses;
462 k->set_next_link(old_value);
463 // Link the new item into the list, making sure the linked class is stable
464 // since the list can be walked without a lock
465 OrderAccess::release_store(&_klasses, k);
466 if (k->is_array_klass()) {
467 ClassLoaderDataGraph::inc_array_classes(1);
468 } else {
469 ClassLoaderDataGraph::inc_instance_classes(1);
470 }
471 }
472
473 if (publicize) {
474 LogTarget(Trace, class, loader, data) lt;
475 if (lt.is_enabled()) {
476 ResourceMark rm;
477 LogStream ls(lt);
478 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
479 print_value_on(&ls);
480 ls.cr();
481 }
482 }
483 }
484
485 // Class iterator used by the compiler. It gets some number of classes at
486 // a safepoint to decay invocation counters on the methods.
487 class ClassLoaderDataGraphKlassIteratorStatic {
488 ClassLoaderData* _current_loader_data;
489 Klass* _current_class_entry;
490 public:
491
492 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
493
494 InstanceKlass* try_get_next_class() {
495 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
496 size_t max_classes = ClassLoaderDataGraph::num_instance_classes();
497 assert(max_classes > 0, "should not be called with no instance classes");
498 for (size_t i = 0; i < max_classes; ) {
499
500 if (_current_class_entry != NULL) {
501 Klass* k = _current_class_entry;
502 _current_class_entry = _current_class_entry->next_link();
503
504 if (k->is_instance_klass()) {
505 InstanceKlass* ik = InstanceKlass::cast(k);
506 i++; // count all instance classes found
507 // Not yet loaded classes are counted in max_classes
508 // but only return loaded classes.
509 if (ik->is_loaded()) {
510 return ik;
511 }
512 }
513 } else {
514 // Go to next CLD
515 if (_current_loader_data != NULL) {
516 _current_loader_data = _current_loader_data->next();
517 }
518 // Start at the beginning
519 if (_current_loader_data == NULL) {
520 _current_loader_data = ClassLoaderDataGraph::_head;
521 }
522
523 _current_class_entry = _current_loader_data->klasses();
524 }
525 }
526 // Should never be reached unless all instance classes have failed or are not fully loaded.
527 // Caller handles NULL.
528 return NULL;
529 }
530
531 // If the current class for the static iterator is a class being unloaded or
532 // deallocated, adjust the current class.
533 void adjust_saved_class(ClassLoaderData* cld) {
534 if (_current_loader_data == cld) {
535 _current_loader_data = cld->next();
536 if (_current_loader_data != NULL) {
537 _current_class_entry = _current_loader_data->klasses();
538 } // else try_get_next_class will start at the head
539 }
540 }
541
542 void adjust_saved_class(Klass* klass) {
543 if (_current_class_entry == klass) {
544 _current_class_entry = klass->next_link();
545 }
546 }
547 };
548
549 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
550
551 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
552 return static_klass_iterator.try_get_next_class();
553 }
554
555
556 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
557 if (loader_or_mirror() != NULL) {
558 assert(_holder.is_null(), "never replace holders");
559 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror);
560 }
561 }
562
563 // Remove a klass from the _klasses list for scratch_class during redefinition
564 // or parsed class in the case of an error.
565 void ClassLoaderData::remove_class(Klass* scratch_class) {
566 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
567
568 // Adjust global class iterator.
569 static_klass_iterator.adjust_saved_class(scratch_class);
570
571 Klass* prev = NULL;
572 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
573 if (k == scratch_class) {
574 if (prev == NULL) {
575 _klasses = k->next_link();
576 } else {
577 Klass* next = k->next_link();
578 prev->set_next_link(next);
579 }
580
581 if (k->is_array_klass()) {
582 ClassLoaderDataGraph::dec_array_classes(1);
583 } else {
584 ClassLoaderDataGraph::dec_instance_classes(1);
585 }
586
587 return;
588 }
589 prev = k;
590 assert(k != k->next_link(), "no loops!");
591 }
592 ShouldNotReachHere(); // should have found this class!!
593 }
594
595 void ClassLoaderData::unload() {
596 _unloading = true;
597
598 LogTarget(Debug, class, loader, data) lt;
599 if (lt.is_enabled()) {
600 ResourceMark rm;
601 LogStream ls(lt);
602 ls.print("unload");
603 print_value_on(&ls);
604 ls.cr();
605 }
606
607 // Some items on the _deallocate_list need to free their C heap structures
608 // if they are not already on the _klasses list.
609 unload_deallocate_list();
610
611 // Tell serviceability tools these classes are unloading
612 // after erroneous classes are released.
613 classes_do(InstanceKlass::notify_unload_class);
614
615 // Clean up global class iterator for compiler
616 static_klass_iterator.adjust_saved_class(this);
617 }
618
619 ModuleEntryTable* ClassLoaderData::modules() {
620 // Lazily create the module entry table at first request.
621 // Lock-free access requires load_acquire.
622 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
623 if (modules == NULL) {
624 MutexLocker m1(Module_lock);
625 // Check if _modules got allocated while we were waiting for this lock.
626 if ((modules = _modules) == NULL) {
627 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
628
629 {
630 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
631 // Ensure _modules is stable, since it is examined without a lock
632 OrderAccess::release_store(&_modules, modules);
633 }
634 }
635 }
636 return modules;
637 }
638
639 const int _boot_loader_dictionary_size = 1009;
640 const int _default_loader_dictionary_size = 107;
641
642 Dictionary* ClassLoaderData::create_dictionary() {
643 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
644 int size;
645 bool resizable = false;
646 if (_the_null_class_loader_data == NULL) {
647 size = _boot_loader_dictionary_size;
648 resizable = true;
649 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
650 size = 1; // there's only one class in relection class loader and no initiated classes
651 } else if (is_system_class_loader_data()) {
652 size = _boot_loader_dictionary_size;
653 resizable = true;
654 } else {
655 size = _default_loader_dictionary_size;
656 resizable = true;
657 }
658 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) {
659 resizable = false;
660 }
661 return new Dictionary(this, size, resizable);
662 }
663
664 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
665 oop ClassLoaderData::holder_phantom() const {
666 // A klass that was previously considered dead can be looked up in the
667 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
668 // or a reachable object making it alive again. The SATB part of G1 needs
669 // to get notified about this potential resurrection, otherwise the marking
670 // might not find the object.
671 if (!_holder.is_null()) { // NULL class_loader
672 return _holder.resolve();
673 } else {
674 return NULL;
675 }
676 }
677
678 // Unloading support
679 bool ClassLoaderData::is_alive() const {
680 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
681 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
682
683 return alive;
684 }
685
686 class ReleaseKlassClosure: public KlassClosure {
687 private:
688 size_t _instance_class_released;
689 size_t _array_class_released;
690 public:
691 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
692
693 size_t instance_class_released() const { return _instance_class_released; }
694 size_t array_class_released() const { return _array_class_released; }
695
696 void do_klass(Klass* k) {
697 if (k->is_array_klass()) {
698 _array_class_released ++;
699 } else {
700 assert(k->is_instance_klass(), "Must be");
701 _instance_class_released ++;
702 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
703 }
704 }
705 };
706
707 ClassLoaderData::~ClassLoaderData() {
708 // Release C heap structures for all the classes.
709 ReleaseKlassClosure cl;
710 classes_do(&cl);
711
712 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
713 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
714
715 // Release the WeakHandle
716 _holder.release();
717
718 // Release C heap allocated hashtable for all the packages.
719 if (_packages != NULL) {
720 // Destroy the table itself
721 delete _packages;
722 _packages = NULL;
723 }
724
725 // Release C heap allocated hashtable for all the modules.
726 if (_modules != NULL) {
727 // Destroy the table itself
728 delete _modules;
729 _modules = NULL;
730 }
731
732 // Release C heap allocated hashtable for the dictionary
733 if (_dictionary != NULL) {
734 // Destroy the table itself
735 delete _dictionary;
736 _dictionary = NULL;
737 }
738
739 if (_unnamed_module != NULL) {
740 _unnamed_module->delete_unnamed_module();
741 _unnamed_module = NULL;
742 }
743
744 // release the metaspace
745 ClassLoaderMetaspace *m = _metaspace;
746 if (m != NULL) {
747 _metaspace = NULL;
748 delete m;
749 }
750 // Clear all the JNI handles for methods
751 // These aren't deallocated and are going to look like a leak, but that's
752 // needed because we can't really get rid of jmethodIDs because we don't
753 // know when native code is going to stop using them. The spec says that
754 // they're "invalid" but existing programs likely rely on their being
755 // NULL after class unloading.
756 if (_jmethod_ids != NULL) {
757 Method::clear_jmethod_ids(this);
758 }
759 // Delete lock
760 delete _metaspace_lock;
761
762 // Delete free list
763 if (_deallocate_list != NULL) {
764 delete _deallocate_list;
765 }
766 }
767
768 // Returns true if this class loader data is for the app class loader
769 // or a user defined system class loader. (Note that the class loader
770 // data may be anonymous.)
771 bool ClassLoaderData::is_system_class_loader_data() const {
772 return SystemDictionary::is_system_class_loader(class_loader());
773 }
774
775 // Returns true if this class loader data is for the platform class loader.
776 // (Note that the class loader data may be anonymous.)
777 bool ClassLoaderData::is_platform_class_loader_data() const {
778 return SystemDictionary::is_platform_class_loader(class_loader());
779 }
780
781 // Returns true if the class loader for this class loader data is one of
782 // the 3 builtin (boot application/system or platform) class loaders,
783 // including a user-defined system class loader. Note that if the class
784 // loader data is for an anonymous class then it may get freed by a GC
785 // even if its class loader is one of these loaders.
786 bool ClassLoaderData::is_builtin_class_loader_data() const {
787 return (is_boot_class_loader_data() ||
788 SystemDictionary::is_system_class_loader(class_loader()) ||
789 SystemDictionary::is_platform_class_loader(class_loader()));
790 }
791
792 // Returns true if this class loader data is a class loader data
793 // that is not ever freed by a GC. It must be one of the builtin
794 // class loaders and not anonymous.
795 bool ClassLoaderData::is_permanent_class_loader_data() const {
796 return is_builtin_class_loader_data() && !is_anonymous();
797 }
798
799 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
800 // If the metaspace has not been allocated, create a new one. Might want
801 // to create smaller arena for Reflection class loaders also.
802 // The reason for the delayed allocation is because some class loaders are
803 // simply for delegating with no metadata of their own.
804 // Lock-free access requires load_acquire.
805 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
806 if (metaspace == NULL) {
807 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
808 // Check if _metaspace got allocated while we were waiting for this lock.
809 if ((metaspace = _metaspace) == NULL) {
810 if (this == the_null_class_loader_data()) {
811 assert (class_loader() == NULL, "Must be");
812 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
813 } else if (is_anonymous()) {
814 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
815 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
816 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
817 } else {
818 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
819 }
820 // Ensure _metaspace is stable, since it is examined without a lock
821 OrderAccess::release_store(&_metaspace, metaspace);
822 }
823 }
824 return metaspace;
825 }
826
827 OopHandle ClassLoaderData::add_handle(Handle h) {
828 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
829 record_modified_oops();
830 return OopHandle(_handles.add(h()));
831 }
832
833 void ClassLoaderData::remove_handle(OopHandle h) {
834 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
835 oop* ptr = h.ptr_raw();
836 if (ptr != NULL) {
837 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
838 // This root is not walked in safepoints, and hence requires an appropriate
839 // decorator that e.g. maintains the SATB invariant in SATB collectors.
840 NativeAccess<IN_CONCURRENT_ROOT>::oop_store(ptr, oop(NULL));
841 }
842 }
843
844 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
845 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
846 if (dest.resolve() != NULL) {
847 return;
848 } else {
849 dest = _handles.add(h());
850 }
851 }
852
853 // Add this metadata pointer to be freed when it's safe. This is only during
854 // class unloading because Handles might point to this metadata field.
855 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
856 // Metadata in shared region isn't deleted.
857 if (!m->is_shared()) {
858 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
859 if (_deallocate_list == NULL) {
860 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
861 }
862 _deallocate_list->append_if_missing(m);
863 }
864 }
865
866 // Deallocate free metadata on the free list. How useful the PermGen was!
867 void ClassLoaderData::free_deallocate_list() {
868 // Don't need lock, at safepoint
869 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
870 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
871 if (_deallocate_list == NULL) {
872 return;
873 }
874 // Go backwards because this removes entries that are freed.
875 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
876 Metadata* m = _deallocate_list->at(i);
877 if (!m->on_stack()) {
878 _deallocate_list->remove_at(i);
879 // There are only three types of metadata that we deallocate directly.
880 // Cast them so they can be used by the template function.
881 if (m->is_method()) {
882 MetadataFactory::free_metadata(this, (Method*)m);
883 } else if (m->is_constantPool()) {
884 MetadataFactory::free_metadata(this, (ConstantPool*)m);
885 } else if (m->is_klass()) {
886 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
887 } else {
888 ShouldNotReachHere();
889 }
890 } else {
891 // Metadata is alive.
892 // If scratch_class is on stack then it shouldn't be on this list!
893 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
894 "scratch classes on this list should be dead");
895 // Also should assert that other metadata on the list was found in handles.
896 }
897 }
898 }
899
900 // This is distinct from free_deallocate_list. For class loader data that are
901 // unloading, this frees the C heap memory for items on the list, and unlinks
902 // scratch or error classes so that unloading events aren't triggered for these
903 // classes. The metadata is removed with the unloading metaspace.
904 // There isn't C heap memory allocated for methods, so nothing is done for them.
905 void ClassLoaderData::unload_deallocate_list() {
906 // Don't need lock, at safepoint
907 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
908 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
909 if (_deallocate_list == NULL) {
910 return;
911 }
912 // Go backwards because this removes entries that are freed.
913 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
914 Metadata* m = _deallocate_list->at(i);
915 assert (!m->on_stack(), "wouldn't be unloading if this were so");
916 _deallocate_list->remove_at(i);
917 if (m->is_constantPool()) {
918 ((ConstantPool*)m)->release_C_heap_structures();
919 } else if (m->is_klass()) {
920 InstanceKlass* ik = (InstanceKlass*)m;
921 // also releases ik->constants() C heap memory
922 InstanceKlass::release_C_heap_structures(ik);
923 // Remove the class so unloading events aren't triggered for
924 // this class (scratch or error class) in do_unloading().
925 remove_class(ik);
926 }
927 }
928 }
929
930 // These anonymous class loaders are to contain classes used for JSR292
931 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(Handle loader) {
932 // Add a new class loader data to the graph.
933 return ClassLoaderDataGraph::add(loader, true);
934 }
935
936 // Caller needs ResourceMark
937 // If the class loader's _name has not been explicitly set, the class loader's
938 // qualified class name is returned.
939 const char* ClassLoaderData::loader_name() const {
940 if (_class_loader_klass == NULL) {
941 return BOOTSTRAP_LOADER_NAME;
942 } else if (_name != NULL) {
943 return _name->as_C_string();
944 } else {
945 return _class_loader_klass->external_name();
946 }
947 }
948
949 // Caller needs ResourceMark
950 // Format of the _name_and_id is as follows:
951 // If the defining loader has a name explicitly set then '<loader-name>' @<id>
952 // If the defining loader has no name then <qualified-class-name> @<id>
953 // If built-in loader, then omit '@<id>' as there is only one instance.
954 const char* ClassLoaderData::loader_name_and_id() const {
955 if (_class_loader_klass == NULL) {
956 return "'" BOOTSTRAP_LOADER_NAME "'";
957 } else if (_name_and_id != NULL) {
958 return _name_and_id->as_C_string();
959 } else {
960 return _class_loader_klass->external_name();
961 }
962 }
963
964 void ClassLoaderData::print_value_on(outputStream* out) const {
965 if (!is_unloading() && class_loader() != NULL) {
966 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
967 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance
968 } else {
969 // loader data: 0xsomeaddr of 'bootstrap'
970 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
971 }
972 if (is_anonymous()) {
973 out->print(" anonymous");
974 }
975 }
976
977 #ifndef PRODUCT
978 void ClassLoaderData::print_on(outputStream* out) const {
979 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
980 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id());
981 if (is_anonymous()) out->print(" anonymous");
982 if (claimed()) out->print(" claimed");
983 if (is_unloading()) out->print(" unloading");
984 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
985
986 if (_jmethod_ids != NULL) {
987 Method::print_jmethod_ids(this, out);
988 }
989 out->print(" handles count %d", _handles.count());
990 out->print(" dependencies %d", _dependency_count);
991 out->print_cr("}");
992 }
993 #endif // PRODUCT
994
995 void ClassLoaderData::verify() {
996 assert_locked_or_safepoint(_metaspace_lock);
997 oop cl = class_loader();
998
999 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
1000 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
1001
1002 // Verify the integrity of the allocated space.
1003 if (metaspace_or_null() != NULL) {
1004 metaspace_or_null()->verify();
1005 }
1006
1007 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
1008 guarantee(k->class_loader_data() == this, "Must be the same");
1009 k->verify();
1010 assert(k != k->next_link(), "no loops!");
1011 }
1012 }
1013
1014 bool ClassLoaderData::contains_klass(Klass* klass) {
1015 // Lock-free access requires load_acquire
1016 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
1017 if (k == klass) return true;
1018 }
1019 return false;
1020 }
1021
1022
1023 // GC root of class loader data created.
1024 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
1025 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
1026 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
1027 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
1028
1029 bool ClassLoaderDataGraph::_should_purge = false;
1030 bool ClassLoaderDataGraph::_metaspace_oom = false;
1031
1032 // Add a new class loader data node to the list. Assign the newly created
1033 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
1034 ClassLoaderData* ClassLoaderDataGraph::add_to_graph(Handle loader, bool is_anonymous) {
1035 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
1036 // ClassLoaderData in the graph since the CLD
1037 // contains oops in _handles that must be walked.
1038
1039 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous);
1040
1041 if (!is_anonymous) {
1042 // First, Atomically set it
1043 ClassLoaderData* old = java_lang_ClassLoader::cmpxchg_loader_data(cld, loader(), NULL);
1044 if (old != NULL) {
1045 delete cld;
1046 // Returns the data.
1047 return old;
1048 }
1049 }
1050
1051 // We won the race, and therefore the task of adding the data to the list of
1052 // class loader data
1053 ClassLoaderData** list_head = &_head;
1054 ClassLoaderData* next = _head;
1055
1056 do {
1057 cld->set_next(next);
1058 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next);
1059 if (exchanged == next) {
1060 LogTarget(Debug, class, loader, data) lt;
1061 if (lt.is_enabled()) {
1062 ResourceMark rm;
1063 LogStream ls(lt);
1064 ls.print("create ");
1065 cld->print_value_on(&ls);
1066 ls.cr();
1067 }
1068 return cld;
1069 }
1070 next = exchanged;
1071 } while (true);
1072 }
1073
1074 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous) {
1075 ClassLoaderData* loader_data = add_to_graph(loader, is_anonymous);
1076 // Initialize name and class after the loader data is added to the CLDG
1077 // because adding the Symbol for the name might safepoint.
1078 if (loader.not_null()) {
1079 loader_data->initialize_name(loader);
1080 }
1081 return loader_data;
1082 }
1083
1084 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1085 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1086 cld->oops_do(f, must_claim);
1087 }
1088 }
1089
1090 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1091 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1092 if (cld->keep_alive()) {
1093 cld->oops_do(f, must_claim);
1094 }
1095 }
1096 }
1097
1098 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1099 if (ClassUnloading) {
1100 keep_alive_oops_do(f, must_claim);
1101 } else {
1102 oops_do(f, must_claim);
1103 }
1104 }
1105
1106 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1107 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1108 cl->do_cld(cld);
1109 }
1110 }
1111
1112 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1113 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1114 // Only walk the head until any clds not purged from prior unloading
1115 // (CMS doesn't purge right away).
1116 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1117 assert(cld->is_unloading(), "invariant");
1118 cl->do_cld(cld);
1119 }
1120 }
1121
1122 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1123 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1124 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1125 if (closure != NULL) {
1126 closure->do_cld(cld);
1127 }
1128 }
1129 }
1130
1131 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1132 roots_cld_do(cl, NULL);
1133 }
1134
1135 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1136 if (ClassUnloading) {
1137 keep_alive_cld_do(cl);
1138 } else {
1139 cld_do(cl);
1140 }
1141 }
1142
1143 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1144 Thread* thread = Thread::current();
1145 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1146 Handle holder(thread, cld->holder_phantom());
1147 cld->classes_do(klass_closure);
1148 }
1149 }
1150
1151 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1152 Thread* thread = Thread::current();
1153 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1154 Handle holder(thread, cld->holder_phantom());
1155 cld->classes_do(f);
1156 }
1157 }
1158
1159 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1160 Thread* thread = Thread::current();
1161 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1162 Handle holder(thread, cld->holder_phantom());
1163 cld->methods_do(f);
1164 }
1165 }
1166
1167 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1168 assert_locked_or_safepoint(Module_lock);
1169 Thread* thread = Thread::current();
1170 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1171 Handle holder(thread, cld->holder_phantom());
1172 cld->modules_do(f);
1173 }
1174 }
1175
1176 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1177 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1178 // Only walk the head until any clds not purged from prior unloading
1179 // (CMS doesn't purge right away).
1180 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1181 assert(cld->is_unloading(), "invariant");
1182 cld->modules_do(f);
1183 }
1184 }
1185
1186 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1187 assert_locked_or_safepoint(Module_lock);
1188 Thread* thread = Thread::current();
1189 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1190 Handle holder(thread, cld->holder_phantom());
1191 cld->packages_do(f);
1192 }
1193 }
1194
1195 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1196 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1197 // Only walk the head until any clds not purged from prior unloading
1198 // (CMS doesn't purge right away).
1199 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1200 assert(cld->is_unloading(), "invariant");
1201 cld->packages_do(f);
1202 }
1203 }
1204
1205 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1206 Thread* thread = Thread::current();
1207 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1208 Handle holder(thread, cld->holder_phantom());
1209 cld->loaded_classes_do(klass_closure);
1210 }
1211 }
1212
1213 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1214 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1215 // Only walk the head until any clds not purged from prior unloading
1216 // (CMS doesn't purge right away).
1217 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1218 assert(cld->is_unloading(), "invariant");
1219 cld->classes_do(f);
1220 }
1221 }
1222
1223 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1224 if (X->dictionary() != NULL)
1225
1226 // Walk classes in the loaded class dictionaries in various forms.
1227 // Only walks the classes defined in this class loader.
1228 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1229 Thread* thread = Thread::current();
1230 FOR_ALL_DICTIONARY(cld) {
1231 Handle holder(thread, cld->holder_phantom());
1232 cld->dictionary()->classes_do(f);
1233 }
1234 }
1235
1236 // Only walks the classes defined in this class loader.
1237 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1238 Thread* thread = Thread::current();
1239 FOR_ALL_DICTIONARY(cld) {
1240 Handle holder(thread, cld->holder_phantom());
1241 cld->dictionary()->classes_do(f, CHECK);
1242 }
1243 }
1244
1245 // Walks all entries in the dictionary including entries initiated by this class loader.
1246 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1247 Thread* thread = Thread::current();
1248 FOR_ALL_DICTIONARY(cld) {
1249 Handle holder(thread, cld->holder_phantom());
1250 cld->dictionary()->all_entries_do(f);
1251 }
1252 }
1253
1254 void ClassLoaderDataGraph::verify_dictionary() {
1255 FOR_ALL_DICTIONARY(cld) {
1256 cld->dictionary()->verify();
1257 }
1258 }
1259
1260 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1261 FOR_ALL_DICTIONARY(cld) {
1262 st->print("Dictionary for ");
1263 cld->print_value_on(st);
1264 st->cr();
1265 cld->dictionary()->print_on(st);
1266 st->cr();
1267 }
1268 }
1269
1270 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1271 FOR_ALL_DICTIONARY(cld) {
1272 ResourceMark rm;
1273 stringStream tempst;
1274 tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id());
1275 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1276 }
1277 }
1278
1279 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1280 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1281
1282 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1283
1284 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1285 ClassLoaderData* curr = _head;
1286 while (curr != _saved_head) {
1287 if (!curr->claimed()) {
1288 array->push(curr);
1289 LogTarget(Debug, class, loader, data) lt;
1290 if (lt.is_enabled()) {
1291 LogStream ls(lt);
1292 ls.print("found new CLD: ");
1293 curr->print_value_on(&ls);
1294 ls.cr();
1295 }
1296 }
1297
1298 curr = curr->_next;
1299 }
1300
1301 return array;
1302 }
1303
1304 #ifndef PRODUCT
1305 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1306 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1307 if (loader_data == data) {
1308 return true;
1309 }
1310 }
1311
1312 return false;
1313 }
1314 #endif // PRODUCT
1315
1316 #if INCLUDE_JFR
1317 static Ticks class_unload_time;
1318 static void post_class_unload_event(Klass* const k) {
1319 assert(k != NULL, "invariant");
1320 EventClassUnload event(UNTIMED);
1321 event.set_endtime(class_unload_time);
1322 event.set_unloadedClass(k);
1323 event.set_definingClassLoader(k->class_loader_data());
1324 event.commit();
1325 }
1326
1327 static void post_class_unload_events() {
1328 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1329 if (Jfr::is_enabled()) {
1330 if (EventClassUnload::is_enabled()) {
1331 class_unload_time = Ticks::now();
1332 ClassLoaderDataGraph::classes_unloading_do(&post_class_unload_event);
1333 }
1334 Jfr::on_unloading_classes();
1335 }
1336 }
1337 #endif // INCLUDE_JFR
1338
1339 // Move class loader data from main list to the unloaded list for unloading
1340 // and deallocation later.
1341 bool ClassLoaderDataGraph::do_unloading(bool clean_previous_versions) {
1342
1343 ClassLoaderData* data = _head;
1344 ClassLoaderData* prev = NULL;
1345 bool seen_dead_loader = false;
1346 uint loaders_processed = 0;
1347 uint loaders_removed = 0;
1348
1349 // Mark metadata seen on the stack only so we can delete unneeded entries.
1350 // Only walk all metadata, including the expensive code cache walk, for Full GC
1351 // and only if class redefinition and if there's previous versions of
1352 // Klasses to delete.
1353 bool walk_all_metadata = clean_previous_versions &&
1354 JvmtiExport::has_redefined_a_class() &&
1355 InstanceKlass::has_previous_versions_and_reset();
1356 MetadataOnStackMark md_on_stack(walk_all_metadata);
1357
1358 // Save previous _unloading pointer for CMS which may add to unloading list before
1359 // purging and we don't want to rewalk the previously unloaded class loader data.
1360 _saved_unloading = _unloading;
1361
1362 data = _head;
1363 while (data != NULL) {
1364 if (data->is_alive()) {
1365 // clean metaspace
1366 if (walk_all_metadata) {
1367 data->classes_do(InstanceKlass::purge_previous_versions);
1368 }
1369 data->free_deallocate_list();
1370 prev = data;
1371 data = data->next();
1372 loaders_processed++;
1373 continue;
1374 }
1375 seen_dead_loader = true;
1376 loaders_removed++;
1377 ClassLoaderData* dead = data;
1378 dead->unload();
1379 data = data->next();
1380 // Remove from loader list.
1381 // This class loader data will no longer be found
1382 // in the ClassLoaderDataGraph.
1383 if (prev != NULL) {
1384 prev->set_next(data);
1385 } else {
1386 assert(dead == _head, "sanity check");
1387 _head = data;
1388 }
1389 dead->set_next(_unloading);
1390 _unloading = dead;
1391 }
1392
1393 if (seen_dead_loader) {
1394 data = _head;
1395 while (data != NULL) {
1396 // Remove entries in the dictionary of live class loader that have
1397 // initiated loading classes in a dead class loader.
1398 if (data->dictionary() != NULL) {
1399 data->dictionary()->do_unloading();
1400 }
1401 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1402 // lists to determine if there are modules on those lists that are now
1403 // dead and should be removed. A module's life cycle is equivalent
1404 // to its defining class loader's life cycle. Since a module is
1405 // considered dead if its class loader is dead, these walks must
1406 // occur after each class loader's aliveness is determined.
1407 if (data->packages() != NULL) {
1408 data->packages()->purge_all_package_exports();
1409 }
1410 if (data->modules_defined()) {
1411 data->modules()->purge_all_module_reads();
1412 }
1413 data = data->next();
1414 }
1415 JFR_ONLY(post_class_unload_events();)
1416 }
1417
1418 log_debug(class, loader, data)("do_unloading: loaders processed %u, loaders removed %u", loaders_processed, loaders_removed);
1419
1420 return seen_dead_loader;
1421 }
1422
1423 void ClassLoaderDataGraph::purge() {
1424 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1425 ClassLoaderData* list = _unloading;
1426 _unloading = NULL;
1427 ClassLoaderData* next = list;
1428 bool classes_unloaded = false;
1429 while (next != NULL) {
1430 ClassLoaderData* purge_me = next;
1431 next = purge_me->next();
1432 delete purge_me;
1433 classes_unloaded = true;
1434 }
1435 if (classes_unloaded) {
1436 Metaspace::purge();
1437 set_metaspace_oom(false);
1438 }
1439 }
1440
1441 int ClassLoaderDataGraph::resize_if_needed() {
1442 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1443 int resized = 0;
1444 if (Dictionary::does_any_dictionary_needs_resizing()) {
1445 FOR_ALL_DICTIONARY(cld) {
1446 if (cld->dictionary()->resize_if_needed()) {
1447 resized++;
1448 }
1449 }
1450 }
1451 return resized;
1452 }
1453
1454 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1455 : _next_klass(NULL) {
1456 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1457 Klass* klass = NULL;
1458
1459 // Find the first klass in the CLDG.
1460 while (cld != NULL) {
1461 assert_locked_or_safepoint(cld->metaspace_lock());
1462 klass = cld->_klasses;
1463 if (klass != NULL) {
1464 _next_klass = klass;
1465 return;
1466 }
1467 cld = cld->next();
1468 }
1469 }
1470
1471 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1472 Klass* next = klass->next_link();
1473 if (next != NULL) {
1474 return next;
1475 }
1476
1477 // No more klasses in the current CLD. Time to find a new CLD.
1478 ClassLoaderData* cld = klass->class_loader_data();
1479 assert_locked_or_safepoint(cld->metaspace_lock());
1480 while (next == NULL) {
1481 cld = cld->next();
1482 if (cld == NULL) {
1483 break;
1484 }
1485 next = cld->_klasses;
1486 }
1487
1488 return next;
1489 }
1490
1491 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1492 Klass* head = _next_klass;
1493
1494 while (head != NULL) {
1495 Klass* next = next_klass_in_cldg(head);
1496
1497 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1498
1499 if (old_head == head) {
1500 return head; // Won the CAS.
1501 }
1502
1503 head = old_head;
1504 }
1505
1506 // Nothing more for the iterator to hand out.
1507 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1508 return NULL;
1509 }
1510
1511 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1512 _data = ClassLoaderDataGraph::_head;
1513 }
1514
1515 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1516
1517 #ifndef PRODUCT
1518 // callable from debugger
1519 extern "C" int print_loader_data_graph() {
1520 ResourceMark rm;
1521 ClassLoaderDataGraph::print_on(tty);
1522 return 0;
1523 }
1524
1525 void ClassLoaderDataGraph::verify() {
1526 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1527 data->verify();
1528 }
1529 }
1530
1531 void ClassLoaderDataGraph::print_on(outputStream * const out) {
1532 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1533 data->print_on(out);
1534 }
1535 }
1536 #endif // PRODUCT