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