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 _class_loader_klass = h_class_loader->klass();
162 }
163
164 if (!is_anonymous) {
165 // The holder is initialized later for anonymous classes, and before calling anything
166 // that call class_loader().
167 initialize_holder(h_class_loader);
168
169 // A ClassLoaderData created solely for an anonymous class should never have a
170 // ModuleEntryTable or PackageEntryTable created for it. The defining package
171 // and module for an anonymous class will be found in its host class.
172 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
173 if (h_class_loader.is_null()) {
174 // Create unnamed module for boot loader
175 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
176 } else {
177 // Create unnamed module for all other loaders
178 _unnamed_module = ModuleEntry::create_unnamed_module(this);
179 }
180 _dictionary = create_dictionary();
181 }
182
183 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
184
185 JFR_ONLY(INIT_ID(this);)
186 }
187
188 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
189 Chunk* c = _head;
190 while (c != NULL) {
191 Chunk* next = c->_next;
192 delete c;
193 c = next;
194 }
195 }
196
197 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
198 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
199 Chunk* next = new Chunk(_head);
200 OrderAccess::release_store(&_head, next);
201 }
202 oop* handle = &_head->_data[_head->_size];
203 *handle = o;
204 OrderAccess::release_store(&_head->_size, _head->_size + 1);
205 return handle;
206 }
207
208 int ClassLoaderData::ChunkedHandleList::count() const {
209 int count = 0;
210 Chunk* chunk = _head;
211 while (chunk != NULL) {
212 count += chunk->_size;
213 chunk = chunk->_next;
214 }
215 return count;
216 }
217
218 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
219 for (juint i = 0; i < size; i++) {
220 if (c->_data[i] != NULL) {
221 f->do_oop(&c->_data[i]);
222 }
223 }
224 }
225
226 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
227 Chunk* head = OrderAccess::load_acquire(&_head);
228 if (head != NULL) {
229 // Must be careful when reading size of head
230 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
231 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
232 oops_do_chunk(f, c, c->_size);
233 }
234 }
235 }
236
237 class VerifyContainsOopClosure : public OopClosure {
238 oop _target;
239 bool _found;
240
241 public:
242 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
243
244 void do_oop(oop* p) {
245 if (p != NULL && oopDesc::equals(RawAccess<>::oop_load(p), _target)) {
246 _found = true;
247 }
248 }
249
250 void do_oop(narrowOop* p) {
251 // The ChunkedHandleList should not contain any narrowOop
252 ShouldNotReachHere();
253 }
254
255 bool found() const {
256 return _found;
257 }
258 };
259
260 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
261 VerifyContainsOopClosure cl(p);
262 oops_do(&cl);
263 return cl.found();
264 }
265
266 #ifndef PRODUCT
267 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
268 Chunk* chunk = _head;
269 while (chunk != NULL) {
270 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
271 return true;
272 }
273 chunk = chunk->_next;
274 }
275 return false;
276 }
277 #endif // PRODUCT
278
279 bool ClassLoaderData::claim() {
280 if (_claimed == 1) {
281 return false;
282 }
283
284 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
285 }
286
287 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
288 // while the class is being parsed, and if the class appears on the module fixup list.
289 // Due to the uniqueness that no other class shares the anonymous class' name or
290 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
291 // it is being defined, therefore _keep_alive is not volatile or atomic.
292 void ClassLoaderData::inc_keep_alive() {
293 if (is_anonymous()) {
294 assert(_keep_alive >= 0, "Invalid keep alive increment count");
295 _keep_alive++;
296 }
297 }
298
299 void ClassLoaderData::dec_keep_alive() {
300 if (is_anonymous()) {
301 assert(_keep_alive > 0, "Invalid keep alive decrement count");
302 _keep_alive--;
303 }
304 }
305
306 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
307 if (must_claim && !claim()) {
308 return;
309 }
310
311 // Only clear modified_oops after the ClassLoaderData is claimed.
312 if (clear_mod_oops) {
313 clear_modified_oops();
314 }
315
316 _handles.oops_do(f);
317 }
318
319 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
320 // Lock-free access requires load_acquire
321 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
322 klass_closure->do_klass(k);
323 assert(k != k->next_link(), "no loops!");
324 }
325 }
326
327 void ClassLoaderData::classes_do(void f(Klass * const)) {
328 // Lock-free access requires load_acquire
329 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
330 f(k);
331 assert(k != k->next_link(), "no loops!");
332 }
333 }
334
335 void ClassLoaderData::methods_do(void f(Method*)) {
336 // Lock-free access requires load_acquire
337 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
338 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
339 InstanceKlass::cast(k)->methods_do(f);
340 }
341 }
342 }
343
344 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
345 // Lock-free access requires load_acquire
346 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
347 // Do not filter ArrayKlass oops here...
348 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
349 #ifdef ASSERT
350 oop m = k->java_mirror();
351 assert(m != NULL, "NULL mirror");
352 assert(m->is_a(SystemDictionary::Class_klass()), "invalid mirror");
353 #endif
354 klass_closure->do_klass(k);
355 }
356 }
357 }
358
359 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
360 // Lock-free access requires load_acquire
361 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
362 if (k->is_instance_klass()) {
363 f(InstanceKlass::cast(k));
364 }
365 assert(k != k->next_link(), "no loops!");
366 }
367 }
368
369 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
370 assert_locked_or_safepoint(Module_lock);
371 if (_unnamed_module != NULL) {
372 f(_unnamed_module);
373 }
374 if (_modules != NULL) {
375 for (int i = 0; i < _modules->table_size(); i++) {
376 for (ModuleEntry* entry = _modules->bucket(i);
377 entry != NULL;
378 entry = entry->next()) {
379 f(entry);
380 }
381 }
382 }
383 }
384
385 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
386 assert_locked_or_safepoint(Module_lock);
387 if (_packages != NULL) {
388 for (int i = 0; i < _packages->table_size(); i++) {
389 for (PackageEntry* entry = _packages->bucket(i);
390 entry != NULL;
391 entry = entry->next()) {
392 f(entry);
393 }
394 }
395 }
396 }
397
398 void ClassLoaderData::record_dependency(const Klass* k) {
399 assert(k != NULL, "invariant");
400
401 ClassLoaderData * const from_cld = this;
402 ClassLoaderData * const to_cld = k->class_loader_data();
403
404 // Do not need to record dependency if the dependency is to a class whose
405 // class loader data is never freed. (i.e. the dependency's class loader
406 // is one of the three builtin class loaders and the dependency is not
407 // anonymous.)
408 if (to_cld->is_permanent_class_loader_data()) {
409 return;
410 }
411
412 oop to;
413 if (to_cld->is_anonymous()) {
414 // Just return if an anonymous class is attempting to record a dependency
415 // to itself. (Note that every anonymous class has its own unique class
416 // loader data.)
417 if (to_cld == from_cld) {
418 return;
419 }
420 // Anonymous class dependencies are through the mirror.
421 to = k->java_mirror();
422 } else {
423 to = to_cld->class_loader();
424 oop from = from_cld->class_loader();
425
426 // Just return if this dependency is to a class with the same or a parent
427 // class_loader.
428 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) {
429 return; // this class loader is in the parent list, no need to add it.
430 }
431 }
432
433 // It's a dependency we won't find through GC, add it.
434 if (!_handles.contains(to)) {
435 NOT_PRODUCT(Atomic::inc(&_dependency_count));
436 LogTarget(Trace, class, loader, data) lt;
437 if (lt.is_enabled()) {
438 ResourceMark rm;
439 LogStream ls(lt);
440 ls.print("adding dependency from ");
441 print_value_on(&ls);
442 ls.print(" to ");
443 to_cld->print_value_on(&ls);
444 ls.cr();
445 }
446 Handle dependency(Thread::current(), to);
447 add_handle(dependency);
448 // Added a potentially young gen oop to the ClassLoaderData
449 record_modified_oops();
450 }
451 }
452
453
454 void ClassLoaderDataGraph::clear_claimed_marks() {
455 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
456 cld->clear_claimed();
457 }
458 }
459
460 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
461 {
462 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
463 Klass* old_value = _klasses;
464 k->set_next_link(old_value);
465 // Link the new item into the list, making sure the linked class is stable
466 // since the list can be walked without a lock
467 OrderAccess::release_store(&_klasses, k);
468 if (k->is_array_klass()) {
469 ClassLoaderDataGraph::inc_array_classes(1);
470 } else {
471 ClassLoaderDataGraph::inc_instance_classes(1);
472 }
473 }
474
475 if (publicize) {
476 LogTarget(Trace, class, loader, data) lt;
477 if (lt.is_enabled()) {
478 ResourceMark rm;
479 LogStream ls(lt);
480 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
481 print_value_on(&ls);
482 ls.cr();
483 }
484 }
485 }
486
487 // Class iterator used by the compiler. It gets some number of classes at
488 // a safepoint to decay invocation counters on the methods.
489 class ClassLoaderDataGraphKlassIteratorStatic {
490 ClassLoaderData* _current_loader_data;
491 Klass* _current_class_entry;
492 public:
493
494 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
495
496 InstanceKlass* try_get_next_class() {
497 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
498 size_t max_classes = ClassLoaderDataGraph::num_instance_classes();
499 assert(max_classes > 0, "should not be called with no instance classes");
500 for (size_t i = 0; i < max_classes; ) {
501
502 if (_current_class_entry != NULL) {
503 Klass* k = _current_class_entry;
504 _current_class_entry = _current_class_entry->next_link();
505
506 if (k->is_instance_klass()) {
507 InstanceKlass* ik = InstanceKlass::cast(k);
508 i++; // count all instance classes found
509 // Not yet loaded classes are counted in max_classes
510 // but only return loaded classes.
511 if (ik->is_loaded()) {
512 return ik;
513 }
514 }
515 } else {
516 // Go to next CLD
517 if (_current_loader_data != NULL) {
518 _current_loader_data = _current_loader_data->next();
519 }
520 // Start at the beginning
521 if (_current_loader_data == NULL) {
522 _current_loader_data = ClassLoaderDataGraph::_head;
523 }
524
525 _current_class_entry = _current_loader_data->klasses();
526 }
527 }
528 // Should never be reached unless all instance classes have failed or are not fully loaded.
529 // Caller handles NULL.
530 return NULL;
531 }
532
533 // If the current class for the static iterator is a class being unloaded or
534 // deallocated, adjust the current class.
535 void adjust_saved_class(ClassLoaderData* cld) {
536 if (_current_loader_data == cld) {
537 _current_loader_data = cld->next();
538 if (_current_loader_data != NULL) {
539 _current_class_entry = _current_loader_data->klasses();
540 } // else try_get_next_class will start at the head
541 }
542 }
543
544 void adjust_saved_class(Klass* klass) {
545 if (_current_class_entry == klass) {
546 _current_class_entry = klass->next_link();
547 }
548 }
549 };
550
551 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
552
553 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
554 return static_klass_iterator.try_get_next_class();
555 }
556
557
558 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
559 if (loader_or_mirror() != NULL) {
560 assert(_holder.is_null(), "never replace holders");
561 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror);
562 }
563 }
564
565 // Remove a klass from the _klasses list for scratch_class during redefinition
566 // or parsed class in the case of an error.
567 void ClassLoaderData::remove_class(Klass* scratch_class) {
568 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
569
570 // Adjust global class iterator.
571 static_klass_iterator.adjust_saved_class(scratch_class);
572
573 Klass* prev = NULL;
574 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
575 if (k == scratch_class) {
576 if (prev == NULL) {
577 _klasses = k->next_link();
578 } else {
579 Klass* next = k->next_link();
580 prev->set_next_link(next);
581 }
582
583 if (k->is_array_klass()) {
584 ClassLoaderDataGraph::dec_array_classes(1);
585 } else {
586 ClassLoaderDataGraph::dec_instance_classes(1);
587 }
588
589 return;
590 }
591 prev = k;
592 assert(k != k->next_link(), "no loops!");
593 }
594 ShouldNotReachHere(); // should have found this class!!
595 }
596
597 void ClassLoaderData::unload() {
598 _unloading = true;
599
600 LogTarget(Debug, class, loader, data) lt;
601 if (lt.is_enabled()) {
602 ResourceMark rm;
603 LogStream ls(lt);
604 ls.print("unload");
605 print_value_on(&ls);
606 ls.cr();
607 }
608
609 // Some items on the _deallocate_list need to free their C heap structures
610 // if they are not already on the _klasses list.
611 unload_deallocate_list();
612
613 // Tell serviceability tools these classes are unloading
614 // after erroneous classes are released.
615 classes_do(InstanceKlass::notify_unload_class);
616
617 // Clean up global class iterator for compiler
618 static_klass_iterator.adjust_saved_class(this);
619 }
620
621 ModuleEntryTable* ClassLoaderData::modules() {
622 // Lazily create the module entry table at first request.
623 // Lock-free access requires load_acquire.
624 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
625 if (modules == NULL) {
626 MutexLocker m1(Module_lock);
627 // Check if _modules got allocated while we were waiting for this lock.
628 if ((modules = _modules) == NULL) {
629 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
630
631 {
632 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
633 // Ensure _modules is stable, since it is examined without a lock
634 OrderAccess::release_store(&_modules, modules);
635 }
636 }
637 }
638 return modules;
639 }
640
641 const int _boot_loader_dictionary_size = 1009;
642 const int _default_loader_dictionary_size = 107;
643
644 Dictionary* ClassLoaderData::create_dictionary() {
645 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
646 int size;
647 bool resizable = false;
648 if (_the_null_class_loader_data == NULL) {
649 size = _boot_loader_dictionary_size;
650 resizable = true;
651 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
652 size = 1; // there's only one class in relection class loader and no initiated classes
653 } else if (is_system_class_loader_data()) {
654 size = _boot_loader_dictionary_size;
655 resizable = true;
656 } else {
657 size = _default_loader_dictionary_size;
658 resizable = true;
659 }
660 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) {
661 resizable = false;
662 }
663 return new Dictionary(this, size, resizable);
664 }
665
666 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
667 oop ClassLoaderData::holder_phantom() const {
668 // A klass that was previously considered dead can be looked up in the
669 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
670 // or a reachable object making it alive again. The SATB part of G1 needs
671 // to get notified about this potential resurrection, otherwise the marking
672 // might not find the object.
673 if (!_holder.is_null()) { // NULL class_loader
674 return _holder.resolve();
675 } else {
676 return NULL;
677 }
678 }
679
680 // Unloading support
681 bool ClassLoaderData::is_alive() const {
682 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
683 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
684
685 return alive;
686 }
687
688 class ReleaseKlassClosure: public KlassClosure {
689 private:
690 size_t _instance_class_released;
691 size_t _array_class_released;
692 public:
693 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
694
695 size_t instance_class_released() const { return _instance_class_released; }
696 size_t array_class_released() const { return _array_class_released; }
697
698 void do_klass(Klass* k) {
699 if (k->is_array_klass()) {
700 _array_class_released ++;
701 } else {
702 assert(k->is_instance_klass(), "Must be");
703 _instance_class_released ++;
704 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
705 }
706 }
707 };
708
709 ClassLoaderData::~ClassLoaderData() {
710 // Release C heap structures for all the classes.
711 ReleaseKlassClosure cl;
712 classes_do(&cl);
713
714 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
715 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
716
717 // Release the WeakHandle
718 _holder.release();
719
720 // Release C heap allocated hashtable for all the packages.
721 if (_packages != NULL) {
722 // Destroy the table itself
723 delete _packages;
724 _packages = NULL;
725 }
726
727 // Release C heap allocated hashtable for all the modules.
728 if (_modules != NULL) {
729 // Destroy the table itself
730 delete _modules;
731 _modules = NULL;
732 }
733
734 // Release C heap allocated hashtable for the dictionary
735 if (_dictionary != NULL) {
736 // Destroy the table itself
737 delete _dictionary;
738 _dictionary = NULL;
739 }
740
741 if (_unnamed_module != NULL) {
742 _unnamed_module->delete_unnamed_module();
743 _unnamed_module = NULL;
744 }
745
746 // release the metaspace
747 ClassLoaderMetaspace *m = _metaspace;
748 if (m != NULL) {
749 _metaspace = NULL;
750 delete m;
751 }
752 // Clear all the JNI handles for methods
753 // These aren't deallocated and are going to look like a leak, but that's
754 // needed because we can't really get rid of jmethodIDs because we don't
755 // know when native code is going to stop using them. The spec says that
756 // they're "invalid" but existing programs likely rely on their being
757 // NULL after class unloading.
758 if (_jmethod_ids != NULL) {
759 Method::clear_jmethod_ids(this);
760 }
761 // Delete lock
762 delete _metaspace_lock;
763
764 // Delete free list
765 if (_deallocate_list != NULL) {
766 delete _deallocate_list;
767 }
768
769 // Decrement refcounts of Symbols if created.
770 if (_name != NULL) {
771 _name->decrement_refcount();
772 }
773 if (_name_and_id != NULL) {
774 _name_and_id->decrement_refcount();
775 }
776 }
777
778 // Returns true if this class loader data is for the app class loader
779 // or a user defined system class loader. (Note that the class loader
780 // data may be anonymous.)
781 bool ClassLoaderData::is_system_class_loader_data() const {
782 return SystemDictionary::is_system_class_loader(class_loader());
783 }
784
785 // Returns true if this class loader data is for the platform class loader.
786 // (Note that the class loader data may be anonymous.)
787 bool ClassLoaderData::is_platform_class_loader_data() const {
788 return SystemDictionary::is_platform_class_loader(class_loader());
789 }
790
791 // Returns true if the class loader for this class loader data is one of
792 // the 3 builtin (boot application/system or platform) class loaders,
793 // including a user-defined system class loader. Note that if the class
794 // loader data is for an anonymous class then it may get freed by a GC
795 // even if its class loader is one of these loaders.
796 bool ClassLoaderData::is_builtin_class_loader_data() const {
797 return (is_boot_class_loader_data() ||
798 SystemDictionary::is_system_class_loader(class_loader()) ||
799 SystemDictionary::is_platform_class_loader(class_loader()));
800 }
801
802 // Returns true if this class loader data is a class loader data
803 // that is not ever freed by a GC. It must be one of the builtin
804 // class loaders and not anonymous.
805 bool ClassLoaderData::is_permanent_class_loader_data() const {
806 return is_builtin_class_loader_data() && !is_anonymous();
807 }
808
809 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
810 // If the metaspace has not been allocated, create a new one. Might want
811 // to create smaller arena for Reflection class loaders also.
812 // The reason for the delayed allocation is because some class loaders are
813 // simply for delegating with no metadata of their own.
814 // Lock-free access requires load_acquire.
815 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
816 if (metaspace == NULL) {
817 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
818 // Check if _metaspace got allocated while we were waiting for this lock.
819 if ((metaspace = _metaspace) == NULL) {
820 if (this == the_null_class_loader_data()) {
821 assert (class_loader() == NULL, "Must be");
822 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
823 } else if (is_anonymous()) {
824 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
825 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
826 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
827 } else {
828 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
829 }
830 // Ensure _metaspace is stable, since it is examined without a lock
831 OrderAccess::release_store(&_metaspace, metaspace);
832 }
833 }
834 return metaspace;
835 }
836
837 OopHandle ClassLoaderData::add_handle(Handle h) {
838 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
839 record_modified_oops();
840 return OopHandle(_handles.add(h()));
841 }
842
843 void ClassLoaderData::remove_handle(OopHandle h) {
844 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
845 oop* ptr = h.ptr_raw();
846 if (ptr != NULL) {
847 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
848 NativeAccess<>::oop_store(ptr, oop(NULL));
849 }
850 }
851
852 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
853 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
854 if (dest.resolve() != NULL) {
855 return;
856 } else {
857 dest = _handles.add(h());
858 }
859 }
860
861 // Add this metadata pointer to be freed when it's safe. This is only during
862 // class unloading because Handles might point to this metadata field.
863 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
864 // Metadata in shared region isn't deleted.
865 if (!m->is_shared()) {
866 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
867 if (_deallocate_list == NULL) {
868 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
869 }
870 _deallocate_list->append_if_missing(m);
871 }
872 }
873
874 // Deallocate free metadata on the free list. How useful the PermGen was!
875 void ClassLoaderData::free_deallocate_list() {
876 // Don't need lock, at safepoint
877 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
878 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
879 if (_deallocate_list == NULL) {
880 return;
881 }
882 // Go backwards because this removes entries that are freed.
883 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
884 Metadata* m = _deallocate_list->at(i);
885 if (!m->on_stack()) {
886 _deallocate_list->remove_at(i);
887 // There are only three types of metadata that we deallocate directly.
888 // Cast them so they can be used by the template function.
889 if (m->is_method()) {
890 MetadataFactory::free_metadata(this, (Method*)m);
891 } else if (m->is_constantPool()) {
892 MetadataFactory::free_metadata(this, (ConstantPool*)m);
893 } else if (m->is_klass()) {
894 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
895 } else {
896 ShouldNotReachHere();
897 }
898 } else {
899 // Metadata is alive.
900 // If scratch_class is on stack then it shouldn't be on this list!
901 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
902 "scratch classes on this list should be dead");
903 // Also should assert that other metadata on the list was found in handles.
904 }
905 }
906 }
907
908 // This is distinct from free_deallocate_list. For class loader data that are
909 // unloading, this frees the C heap memory for items on the list, and unlinks
910 // scratch or error classes so that unloading events aren't triggered for these
911 // classes. The metadata is removed with the unloading metaspace.
912 // There isn't C heap memory allocated for methods, so nothing is done for them.
913 void ClassLoaderData::unload_deallocate_list() {
914 // Don't need lock, at safepoint
915 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
916 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
917 if (_deallocate_list == NULL) {
918 return;
919 }
920 // Go backwards because this removes entries that are freed.
921 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
922 Metadata* m = _deallocate_list->at(i);
923 assert (!m->on_stack(), "wouldn't be unloading if this were so");
924 _deallocate_list->remove_at(i);
925 if (m->is_constantPool()) {
926 ((ConstantPool*)m)->release_C_heap_structures();
927 } else if (m->is_klass()) {
928 InstanceKlass* ik = (InstanceKlass*)m;
929 // also releases ik->constants() C heap memory
930 InstanceKlass::release_C_heap_structures(ik);
931 // Remove the class so unloading events aren't triggered for
932 // this class (scratch or error class) in do_unloading().
933 remove_class(ik);
934 }
935 }
936 }
937
938 // These anonymous class loaders are to contain classes used for JSR292
939 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(Handle loader) {
940 // Add a new class loader data to the graph.
941 return ClassLoaderDataGraph::add(loader, true);
942 }
943
944 // Caller needs ResourceMark
945 // If the class loader's _name has not been explicitly set, the class loader's
946 // qualified class name is returned.
947 const char* ClassLoaderData::loader_name() const {
948 if (_class_loader_klass == NULL) {
949 return BOOTSTRAP_LOADER_NAME;
950 } else if (_name != NULL) {
951 return _name->as_C_string();
952 } else {
953 return _class_loader_klass->external_name();
954 }
955 }
956
957 // Caller needs ResourceMark
958 // Format of the _name_and_id is as follows:
959 // If the defining loader has a name explicitly set then '<loader-name>' @<id>
960 // If the defining loader has no name then <qualified-class-name> @<id>
961 // If built-in loader, then omit '@<id>' as there is only one instance.
962 const char* ClassLoaderData::loader_name_and_id() const {
963 if (_class_loader_klass == NULL) {
964 return "'" BOOTSTRAP_LOADER_NAME "'";
965 } else if (_name_and_id != NULL) {
966 return _name_and_id->as_C_string();
967 } else {
968 // May be called in a race before _name_and_id is initialized.
969 return _class_loader_klass->external_name();
970 }
971 }
972
973 void ClassLoaderData::print_value_on(outputStream* out) const {
974 if (!is_unloading() && class_loader() != NULL) {
975 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
976 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance
977 } else {
978 // loader data: 0xsomeaddr of 'bootstrap'
979 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
980 }
981 if (is_anonymous()) {
982 out->print(" anonymous");
983 }
984 }
985
986 #ifndef PRODUCT
987 void ClassLoaderData::print_on(outputStream* out) const {
988 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
989 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id());
990 if (is_anonymous()) out->print(" anonymous");
991 if (claimed()) out->print(" claimed");
992 if (is_unloading()) out->print(" unloading");
993 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
994
995 if (_jmethod_ids != NULL) {
996 Method::print_jmethod_ids(this, out);
997 }
998 out->print(" handles count %d", _handles.count());
999 out->print(" dependencies %d", _dependency_count);
1000 out->print_cr("}");
1001 }
1002 #endif // PRODUCT
1003
1004 void ClassLoaderData::verify() {
1005 assert_locked_or_safepoint(_metaspace_lock);
1006 oop cl = class_loader();
1007
1008 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
1009 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
1010
1011 // Verify the integrity of the allocated space.
1012 if (metaspace_or_null() != NULL) {
1013 metaspace_or_null()->verify();
1014 }
1015
1016 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
1017 guarantee(k->class_loader_data() == this, "Must be the same");
1018 k->verify();
1019 assert(k != k->next_link(), "no loops!");
1020 }
1021 }
1022
1023 bool ClassLoaderData::contains_klass(Klass* klass) {
1024 // Lock-free access requires load_acquire
1025 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
1026 if (k == klass) return true;
1027 }
1028 return false;
1029 }
1030
1031
1032 // GC root of class loader data created.
1033 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
1034 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
1035 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
1036 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
1037
1038 bool ClassLoaderDataGraph::_should_purge = false;
1039 bool ClassLoaderDataGraph::_metaspace_oom = false;
1040
1041 // Add a new class loader data node to the list. Assign the newly created
1042 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
1043 ClassLoaderData* ClassLoaderDataGraph::add_to_graph(Handle loader, bool is_anonymous) {
1044 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
1045 // ClassLoaderData in the graph since the CLD
1046 // contains oops in _handles that must be walked.
1047
1048 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous);
1049
1050 if (!is_anonymous) {
1051 // First, Atomically set it
1052 ClassLoaderData* old = java_lang_ClassLoader::cmpxchg_loader_data(cld, loader(), NULL);
1053 if (old != NULL) {
1054 delete cld;
1055 // Returns the data.
1056 return old;
1057 }
1058 }
1059
1060 // We won the race, and therefore the task of adding the data to the list of
1061 // class loader data
1062 ClassLoaderData** list_head = &_head;
1063 ClassLoaderData* next = _head;
1064
1065 do {
1066 cld->set_next(next);
1067 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next);
1068 if (exchanged == next) {
1069 LogTarget(Debug, class, loader, data) lt;
1070 if (lt.is_enabled()) {
1071 ResourceMark rm;
1072 LogStream ls(lt);
1073 ls.print("create ");
1074 cld->print_value_on(&ls);
1075 ls.cr();
1076 }
1077 return cld;
1078 }
1079 next = exchanged;
1080 } while (true);
1081 }
1082
1083 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous) {
1084 ClassLoaderData* loader_data = add_to_graph(loader, is_anonymous);
1085 // Initialize _name and _name_and_id after the loader data is added to the
1086 // CLDG because adding the Symbol for _name and _name_and_id might safepoint.
1087 if (loader.not_null()) {
1088 loader_data->initialize_name(loader);
1089 }
1090 return loader_data;
1091 }
1092
1093 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1094 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1095 cld->oops_do(f, must_claim);
1096 }
1097 }
1098
1099 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1100 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1101 if (cld->keep_alive()) {
1102 cld->oops_do(f, must_claim);
1103 }
1104 }
1105 }
1106
1107 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1108 if (ClassUnloading) {
1109 keep_alive_oops_do(f, must_claim);
1110 } else {
1111 oops_do(f, must_claim);
1112 }
1113 }
1114
1115 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1116 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1117 cl->do_cld(cld);
1118 }
1119 }
1120
1121 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1122 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1123 // Only walk the head until any clds not purged from prior unloading
1124 // (CMS doesn't purge right away).
1125 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1126 assert(cld->is_unloading(), "invariant");
1127 cl->do_cld(cld);
1128 }
1129 }
1130
1131 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1132 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1133 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1134 if (closure != NULL) {
1135 closure->do_cld(cld);
1136 }
1137 }
1138 }
1139
1140 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1141 roots_cld_do(cl, NULL);
1142 }
1143
1144 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1145 if (ClassUnloading) {
1146 keep_alive_cld_do(cl);
1147 } else {
1148 cld_do(cl);
1149 }
1150 }
1151
1152 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1153 Thread* thread = Thread::current();
1154 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1155 Handle holder(thread, cld->holder_phantom());
1156 cld->classes_do(klass_closure);
1157 }
1158 }
1159
1160 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1161 Thread* thread = Thread::current();
1162 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1163 Handle holder(thread, cld->holder_phantom());
1164 cld->classes_do(f);
1165 }
1166 }
1167
1168 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1169 Thread* thread = Thread::current();
1170 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1171 Handle holder(thread, cld->holder_phantom());
1172 cld->methods_do(f);
1173 }
1174 }
1175
1176 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1177 assert_locked_or_safepoint(Module_lock);
1178 Thread* thread = Thread::current();
1179 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1180 Handle holder(thread, cld->holder_phantom());
1181 cld->modules_do(f);
1182 }
1183 }
1184
1185 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1186 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1187 // Only walk the head until any clds not purged from prior unloading
1188 // (CMS doesn't purge right away).
1189 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1190 assert(cld->is_unloading(), "invariant");
1191 cld->modules_do(f);
1192 }
1193 }
1194
1195 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1196 assert_locked_or_safepoint(Module_lock);
1197 Thread* thread = Thread::current();
1198 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1199 Handle holder(thread, cld->holder_phantom());
1200 cld->packages_do(f);
1201 }
1202 }
1203
1204 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1205 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1206 // Only walk the head until any clds not purged from prior unloading
1207 // (CMS doesn't purge right away).
1208 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1209 assert(cld->is_unloading(), "invariant");
1210 cld->packages_do(f);
1211 }
1212 }
1213
1214 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1215 Thread* thread = Thread::current();
1216 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1217 Handle holder(thread, cld->holder_phantom());
1218 cld->loaded_classes_do(klass_closure);
1219 }
1220 }
1221
1222 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1223 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1224 // Only walk the head until any clds not purged from prior unloading
1225 // (CMS doesn't purge right away).
1226 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1227 assert(cld->is_unloading(), "invariant");
1228 cld->classes_do(f);
1229 }
1230 }
1231
1232 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1233 if (X->dictionary() != NULL)
1234
1235 // Walk classes in the loaded class dictionaries in various forms.
1236 // Only walks the classes defined in this class loader.
1237 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1238 Thread* thread = Thread::current();
1239 FOR_ALL_DICTIONARY(cld) {
1240 Handle holder(thread, cld->holder_phantom());
1241 cld->dictionary()->classes_do(f);
1242 }
1243 }
1244
1245 // Only walks the classes defined in this class loader.
1246 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1247 Thread* thread = Thread::current();
1248 FOR_ALL_DICTIONARY(cld) {
1249 Handle holder(thread, cld->holder_phantom());
1250 cld->dictionary()->classes_do(f, CHECK);
1251 }
1252 }
1253
1254 // Walks all entries in the dictionary including entries initiated by this class loader.
1255 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1256 Thread* thread = Thread::current();
1257 FOR_ALL_DICTIONARY(cld) {
1258 Handle holder(thread, cld->holder_phantom());
1259 cld->dictionary()->all_entries_do(f);
1260 }
1261 }
1262
1263 void ClassLoaderDataGraph::verify_dictionary() {
1264 FOR_ALL_DICTIONARY(cld) {
1265 cld->dictionary()->verify();
1266 }
1267 }
1268
1269 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1270 FOR_ALL_DICTIONARY(cld) {
1271 st->print("Dictionary for ");
1272 cld->print_value_on(st);
1273 st->cr();
1274 cld->dictionary()->print_on(st);
1275 st->cr();
1276 }
1277 }
1278
1279 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1280 FOR_ALL_DICTIONARY(cld) {
1281 ResourceMark rm;
1282 stringStream tempst;
1283 tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id());
1284 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1285 }
1286 }
1287
1288 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1289 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1290
1291 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1292
1293 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1294 ClassLoaderData* curr = _head;
1295 while (curr != _saved_head) {
1296 if (!curr->claimed()) {
1297 array->push(curr);
1298 LogTarget(Debug, class, loader, data) lt;
1299 if (lt.is_enabled()) {
1300 LogStream ls(lt);
1301 ls.print("found new CLD: ");
1302 curr->print_value_on(&ls);
1303 ls.cr();
1304 }
1305 }
1306
1307 curr = curr->_next;
1308 }
1309
1310 return array;
1311 }
1312
1313 #ifndef PRODUCT
1314 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1315 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1316 if (loader_data == data) {
1317 return true;
1318 }
1319 }
1320
1321 return false;
1322 }
1323 #endif // PRODUCT
1324
1325 bool ClassLoaderDataGraph::is_valid(ClassLoaderData* loader_data) {
1326 if (loader_data != NULL) {
1327 if (loader_data == ClassLoaderData::the_null_class_loader_data()) {
1328 return true;
1329 }
1330 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1331 if (loader_data == data) {
1332 return true;
1333 }
1334 }
1335 }
1336 return false;
1337 }
1338
1339 #if INCLUDE_JFR
1340 static Ticks class_unload_time;
1341 static void post_class_unload_event(Klass* const k) {
1342 assert(k != NULL, "invariant");
1343 EventClassUnload event(UNTIMED);
1344 event.set_endtime(class_unload_time);
1345 event.set_unloadedClass(k);
1346 event.set_definingClassLoader(k->class_loader_data());
1347 event.commit();
1348 }
1349
1350 static void post_class_unload_events() {
1351 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1352 if (Jfr::is_enabled()) {
1353 if (EventClassUnload::is_enabled()) {
1354 class_unload_time = Ticks::now();
1355 ClassLoaderDataGraph::classes_unloading_do(&post_class_unload_event);
1356 }
1357 Jfr::on_unloading_classes();
1358 }
1359 }
1360 #endif // INCLUDE_JFR
1361
1362 // Move class loader data from main list to the unloaded list for unloading
1363 // and deallocation later.
1364 bool ClassLoaderDataGraph::do_unloading(bool clean_previous_versions) {
1365
1366 ClassLoaderData* data = _head;
1367 ClassLoaderData* prev = NULL;
1368 bool seen_dead_loader = false;
1369 uint loaders_processed = 0;
1370 uint loaders_removed = 0;
1371
1372 // Mark metadata seen on the stack only so we can delete unneeded entries.
1373 // Only walk all metadata, including the expensive code cache walk, for Full GC
1374 // and only if class redefinition and if there's previous versions of
1375 // Klasses to delete.
1376 bool walk_all_metadata = clean_previous_versions &&
1377 JvmtiExport::has_redefined_a_class() &&
1378 InstanceKlass::has_previous_versions_and_reset();
1379 MetadataOnStackMark md_on_stack(walk_all_metadata);
1380
1381 // Save previous _unloading pointer for CMS which may add to unloading list before
1382 // purging and we don't want to rewalk the previously unloaded class loader data.
1383 _saved_unloading = _unloading;
1384
1385 data = _head;
1386 while (data != NULL) {
1387 if (data->is_alive()) {
1388 // clean metaspace
1389 if (walk_all_metadata) {
1390 data->classes_do(InstanceKlass::purge_previous_versions);
1391 }
1392 data->free_deallocate_list();
1393 prev = data;
1394 data = data->next();
1395 loaders_processed++;
1396 continue;
1397 }
1398 seen_dead_loader = true;
1399 loaders_removed++;
1400 ClassLoaderData* dead = data;
1401 dead->unload();
1402 data = data->next();
1403 // Remove from loader list.
1404 // This class loader data will no longer be found
1405 // in the ClassLoaderDataGraph.
1406 if (prev != NULL) {
1407 prev->set_next(data);
1408 } else {
1409 assert(dead == _head, "sanity check");
1410 _head = data;
1411 }
1412 dead->set_next(_unloading);
1413 _unloading = dead;
1414 }
1415
1416 if (seen_dead_loader) {
1417 data = _head;
1418 while (data != NULL) {
1419 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1420 // lists to determine if there are modules on those lists that are now
1421 // dead and should be removed. A module's life cycle is equivalent
1422 // to its defining class loader's life cycle. Since a module is
1423 // considered dead if its class loader is dead, these walks must
1424 // occur after each class loader's aliveness is determined.
1425 if (data->packages() != NULL) {
1426 data->packages()->purge_all_package_exports();
1427 }
1428 if (data->modules_defined()) {
1429 data->modules()->purge_all_module_reads();
1430 }
1431 // Clean cached pd lists
1432 // It's unlikely, but some loaded classes in a dictionary might
1433 // point to a protection_domain that has been unloaded.
1434 // The dictionary pd_set points at entries in the ProtectionDomainCacheTable.
1435 if (data->dictionary() != NULL) {
1436 data->dictionary()->clean_cached_protection_domains();
1437 }
1438 data = data->next();
1439 }
1440 JFR_ONLY(post_class_unload_events();)
1441 }
1442
1443 log_debug(class, loader, data)("do_unloading: loaders processed %u, loaders removed %u", loaders_processed, loaders_removed);
1444
1445 return seen_dead_loader;
1446 }
1447
1448 void ClassLoaderDataGraph::purge() {
1449 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1450 ClassLoaderData* list = _unloading;
1451 _unloading = NULL;
1452 ClassLoaderData* next = list;
1453 bool classes_unloaded = false;
1454 while (next != NULL) {
1455 ClassLoaderData* purge_me = next;
1456 next = purge_me->next();
1457 delete purge_me;
1458 classes_unloaded = true;
1459 }
1460 if (classes_unloaded) {
1461 Metaspace::purge();
1462 set_metaspace_oom(false);
1463 }
1464 }
1465
1466 int ClassLoaderDataGraph::resize_if_needed() {
1467 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1468 int resized = 0;
1469 if (Dictionary::does_any_dictionary_needs_resizing()) {
1470 FOR_ALL_DICTIONARY(cld) {
1471 if (cld->dictionary()->resize_if_needed()) {
1472 resized++;
1473 }
1474 }
1475 }
1476 return resized;
1477 }
1478
1479 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1480 : _next_klass(NULL) {
1481 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1482 Klass* klass = NULL;
1483
1484 // Find the first klass in the CLDG.
1485 while (cld != NULL) {
1486 assert_locked_or_safepoint(cld->metaspace_lock());
1487 klass = cld->_klasses;
1488 if (klass != NULL) {
1489 _next_klass = klass;
1490 return;
1491 }
1492 cld = cld->next();
1493 }
1494 }
1495
1496 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1497 Klass* next = klass->next_link();
1498 if (next != NULL) {
1499 return next;
1500 }
1501
1502 // No more klasses in the current CLD. Time to find a new CLD.
1503 ClassLoaderData* cld = klass->class_loader_data();
1504 assert_locked_or_safepoint(cld->metaspace_lock());
1505 while (next == NULL) {
1506 cld = cld->next();
1507 if (cld == NULL) {
1508 break;
1509 }
1510 next = cld->_klasses;
1511 }
1512
1513 return next;
1514 }
1515
1516 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1517 Klass* head = _next_klass;
1518
1519 while (head != NULL) {
1520 Klass* next = next_klass_in_cldg(head);
1521
1522 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1523
1524 if (old_head == head) {
1525 return head; // Won the CAS.
1526 }
1527
1528 head = old_head;
1529 }
1530
1531 // Nothing more for the iterator to hand out.
1532 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1533 return NULL;
1534 }
1535
1536 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1537 _data = ClassLoaderDataGraph::_head;
1538 }
1539
1540 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1541
1542 #ifndef PRODUCT
1543 // callable from debugger
1544 extern "C" int print_loader_data_graph() {
1545 ResourceMark rm;
1546 ClassLoaderDataGraph::print_on(tty);
1547 return 0;
1548 }
1549
1550 void ClassLoaderDataGraph::verify() {
1551 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1552 data->verify();
1553 }
1554 }
1555
1556 void ClassLoaderDataGraph::print_on(outputStream * const out) {
1557 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1558 data->print_on(out);
1559 }
1560 }
1561 #endif // PRODUCT