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