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/javaCalls.hpp"
73 #include "runtime/mutex.hpp"
74 #include "runtime/orderAccess.hpp"
75 #include "runtime/safepoint.hpp"
76 #include "runtime/safepointVerifiers.hpp"
77 #include "utilities/growableArray.hpp"
78 #include "utilities/macros.hpp"
79 #include "utilities/ostream.hpp"
80 #include "utilities/ticks.hpp"
81 #if INCLUDE_JFR
82 #include "jfr/jfr.hpp"
83 #include "jfr/jfrEvents.hpp"
84 #endif
85
86 volatile size_t ClassLoaderDataGraph::_num_array_classes = 0;
87 volatile size_t ClassLoaderDataGraph::_num_instance_classes = 0;
88
89 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
90
91 void ClassLoaderData::init_null_class_loader_data() {
92 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
93 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
94
95 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
96 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
97 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
98
99 LogTarget(Debug, class, loader, data) lt;
100 if (lt.is_enabled()) {
101 ResourceMark rm;
102 LogStream ls(lt);
103 ls.print("create ");
104 _the_null_class_loader_data->print_value_on(&ls);
105 ls.cr();
106 }
107 }
108
109 // Obtain and set the class loader's name within the ClassLoaderData so
110 // it will be available for error messages, logging, JFR, etc. The name
111 // and klass are available after the class_loader oop is no longer alive,
112 // during unloading.
113 void ClassLoaderData::initialize_name(Handle class_loader) {
114 Thread* THREAD = Thread::current();
115 ResourceMark rm(THREAD);
116
117 // Obtain the class loader's name. If the class loader's name was not
118 // explicitly set during construction, the CLD's _name field will be null.
119 oop cl_name = java_lang_ClassLoader::name(class_loader());
120 if (cl_name != NULL) {
121 const char* cl_instance_name = java_lang_String::as_utf8_string(cl_name);
122
123 if (cl_instance_name != NULL && cl_instance_name[0] != '\0') {
124 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore.
125 _name = SymbolTable::new_symbol(cl_instance_name, CATCH);
126 }
127 }
128
129 // Obtain the class loader's name and identity hash. If the class loader's
130 // name was not explicitly set during construction, the class loader's name and id
131 // will be set to the qualified class name of the class loader along with its
132 // identity hash.
133 // If for some reason the ClassLoader's constructor has not been run, instead of
134 // leaving the _name_and_id field null, fall back to the external qualified class
135 // name. Thus CLD's _name_and_id field should never have a null value.
136 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader());
137 const char* cl_instance_name_and_id =
138 (cl_name_and_id == NULL) ? _class_loader_klass->external_name() :
139 java_lang_String::as_utf8_string(cl_name_and_id);
140 assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id");
141 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore.
142 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id, CATCH);
143 }
144
145 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous) :
146 _is_anonymous(is_anonymous),
147 // An anonymous class loader data doesn't have anything to keep
148 // it from being unloaded during parsing of the anonymous class.
149 // The null-class-loader should always be kept alive.
150 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
151 _metaspace(NULL), _unloading(false), _klasses(NULL),
152 _modules(NULL), _packages(NULL), _unnamed_module(NULL), _dictionary(NULL),
153 _claimed(0), _modified_oops(true), _accumulated_modified_oops(false),
154 _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
155 _next(NULL),
156 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL),
157 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
158 Monitor::_safepoint_check_never)) {
159
160 if (!h_class_loader.is_null()) {
161 _class_loader = _handles.add(h_class_loader());
162 _class_loader_klass = h_class_loader->klass();
163 }
164
165 if (!is_anonymous) {
166 // The holder is initialized later for anonymous classes, and before calling anything
167 // that call class_loader().
168 initialize_holder(h_class_loader);
169
170 // A ClassLoaderData created solely for an anonymous class should never have a
171 // ModuleEntryTable or PackageEntryTable created for it. The defining package
172 // and module for an anonymous class will be found in its host class.
173 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
174 if (h_class_loader.is_null()) {
175 // Create unnamed module for boot loader
176 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
177 } else {
178 // Create unnamed module for all other loaders
179 _unnamed_module = ModuleEntry::create_unnamed_module(this);
180 }
181 _dictionary = create_dictionary();
182 }
183
184 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
185
186 JFR_ONLY(INIT_ID(this);)
187 }
188
189 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
190 Chunk* c = _head;
191 while (c != NULL) {
192 Chunk* next = c->_next;
193 delete c;
194 c = next;
195 }
196 }
197
198 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
199 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
200 Chunk* next = new Chunk(_head);
201 OrderAccess::release_store(&_head, next);
202 }
203 oop* handle = &_head->_data[_head->_size];
204 *handle = o;
205 OrderAccess::release_store(&_head->_size, _head->_size + 1);
206 return handle;
207 }
208
209 int ClassLoaderData::ChunkedHandleList::count() const {
210 int count = 0;
211 Chunk* chunk = _head;
212 while (chunk != NULL) {
213 count += chunk->_size;
214 chunk = chunk->_next;
215 }
216 return count;
217 }
218
219 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
220 for (juint i = 0; i < size; i++) {
221 if (c->_data[i] != NULL) {
222 f->do_oop(&c->_data[i]);
223 }
224 }
225 }
226
227 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
228 Chunk* head = OrderAccess::load_acquire(&_head);
229 if (head != NULL) {
230 // Must be careful when reading size of head
231 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
232 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
233 oops_do_chunk(f, c, c->_size);
234 }
235 }
236 }
237
238 class VerifyContainsOopClosure : public OopClosure {
239 oop _target;
240 bool _found;
241
242 public:
243 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
244
245 void do_oop(oop* p) {
246 if (p != NULL && oopDesc::equals(RawAccess<>::oop_load(p), _target)) {
247 _found = true;
248 }
249 }
250
251 void do_oop(narrowOop* p) {
252 // The ChunkedHandleList should not contain any narrowOop
253 ShouldNotReachHere();
254 }
255
256 bool found() const {
257 return _found;
258 }
259 };
260
261 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
262 VerifyContainsOopClosure cl(p);
263 oops_do(&cl);
264 return cl.found();
265 }
266
267 #ifndef PRODUCT
268 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
269 Chunk* chunk = _head;
270 while (chunk != NULL) {
271 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
272 return true;
273 }
274 chunk = chunk->_next;
275 }
276 return false;
277 }
278 #endif // PRODUCT
279
280 bool ClassLoaderData::claim() {
281 if (_claimed == 1) {
282 return false;
283 }
284
285 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
286 }
287
288 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
289 // while the class is being parsed, and if the class appears on the module fixup list.
290 // Due to the uniqueness that no other class shares the anonymous class' name or
291 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
292 // it is being defined, therefore _keep_alive is not volatile or atomic.
293 void ClassLoaderData::inc_keep_alive() {
294 if (is_anonymous()) {
295 assert(_keep_alive >= 0, "Invalid keep alive increment count");
296 _keep_alive++;
297 }
298 }
299
300 void ClassLoaderData::dec_keep_alive() {
301 if (is_anonymous()) {
302 assert(_keep_alive > 0, "Invalid keep alive decrement count");
303 _keep_alive--;
304 }
305 }
306
307 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
308 if (must_claim && !claim()) {
309 return;
310 }
311
312 // Only clear modified_oops after the ClassLoaderData is claimed.
313 if (clear_mod_oops) {
314 clear_modified_oops();
315 }
316
317 _handles.oops_do(f);
318 }
319
320 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
321 // Lock-free access requires load_acquire
322 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
323 klass_closure->do_klass(k);
324 assert(k != k->next_link(), "no loops!");
325 }
326 }
327
328 void ClassLoaderData::classes_do(void f(Klass * const)) {
329 // Lock-free access requires load_acquire
330 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
331 f(k);
332 assert(k != k->next_link(), "no loops!");
333 }
334 }
335
336 void ClassLoaderData::methods_do(void f(Method*)) {
337 // Lock-free access requires load_acquire
338 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
339 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
340 InstanceKlass::cast(k)->methods_do(f);
341 }
342 }
343 }
344
345 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
346 // Lock-free access requires load_acquire
347 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
348 // Do not filter ArrayKlass oops here...
349 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
350 klass_closure->do_klass(k);
351 }
352 }
353 }
354
355 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
356 // Lock-free access requires load_acquire
357 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
358 if (k->is_instance_klass()) {
359 f(InstanceKlass::cast(k));
360 }
361 assert(k != k->next_link(), "no loops!");
362 }
363 }
364
365 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
366 assert_locked_or_safepoint(Module_lock);
367 if (_unnamed_module != NULL) {
368 f(_unnamed_module);
369 }
370 if (_modules != NULL) {
371 for (int i = 0; i < _modules->table_size(); i++) {
372 for (ModuleEntry* entry = _modules->bucket(i);
373 entry != NULL;
374 entry = entry->next()) {
375 f(entry);
376 }
377 }
378 }
379 }
380
381 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
382 assert_locked_or_safepoint(Module_lock);
383 if (_packages != NULL) {
384 for (int i = 0; i < _packages->table_size(); i++) {
385 for (PackageEntry* entry = _packages->bucket(i);
386 entry != NULL;
387 entry = entry->next()) {
388 f(entry);
389 }
390 }
391 }
392 }
393
394 void ClassLoaderData::record_dependency(const Klass* k) {
395 assert(k != NULL, "invariant");
396
397 ClassLoaderData * const from_cld = this;
398 ClassLoaderData * const to_cld = k->class_loader_data();
399
400 // Do not need to record dependency if the dependency is to a class whose
401 // class loader data is never freed. (i.e. the dependency's class loader
402 // is one of the three builtin class loaders and the dependency is not
403 // anonymous.)
404 if (to_cld->is_permanent_class_loader_data()) {
405 return;
406 }
407
408 oop to;
409 if (to_cld->is_anonymous()) {
410 // Just return if an anonymous class is attempting to record a dependency
411 // to itself. (Note that every anonymous class has its own unique class
412 // loader data.)
413 if (to_cld == from_cld) {
414 return;
415 }
416 // Anonymous class dependencies are through the mirror.
417 to = k->java_mirror();
418 } else {
419 to = to_cld->class_loader();
420 oop from = from_cld->class_loader();
421
422 // Just return if this dependency is to a class with the same or a parent
423 // class_loader.
424 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) {
425 return; // this class loader is in the parent list, no need to add it.
426 }
427 }
428
429 // It's a dependency we won't find through GC, add it.
430 if (!_handles.contains(to)) {
431 NOT_PRODUCT(Atomic::inc(&_dependency_count));
432 LogTarget(Trace, class, loader, data) lt;
433 if (lt.is_enabled()) {
434 ResourceMark rm;
435 LogStream ls(lt);
436 ls.print("adding dependency from ");
437 print_value_on(&ls);
438 ls.print(" to ");
439 to_cld->print_value_on(&ls);
440 ls.cr();
441 }
442 Handle dependency(Thread::current(), to);
443 add_handle(dependency);
444 // Added a potentially young gen oop to the ClassLoaderData
445 record_modified_oops();
446 }
447 }
448
449 void ClassLoaderData::record_init_exception(OopHandle cls, Handle exc, TRAPS) {
450 JavaValue v(T_VOID);
451 JavaCalls::call_static(&v,
452 SystemDictionary::ClassLoader_klass(),
453 vmSymbols::recordInitException_name(),
454 vmSymbols::class_throwable_void_signature(),
455 Handle(THREAD, cls.resolve()),
456 exc,
457 THREAD);
458 // Cleanup and ignore any exceptions because recording initialisation exceptions is optional
459 if (THREAD->has_pending_exception()) {
460 CLEAR_PENDING_EXCEPTION;
461 }
462 }
463
464 void ClassLoaderData::throw_reinit_exception(OopHandle cls, TRAPS) {
465 JavaValue v(T_VOID);
466 JavaCalls::call_static(&v,
467 SystemDictionary::ClassLoader_klass(),
468 vmSymbols::throwReinitException_name(),
469 vmSymbols::class_void_signature(),
470 Handle(THREAD, cls.resolve()),
471 THREAD);
472 }
473
474 void ClassLoaderDataGraph::clear_claimed_marks() {
475 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
476 cld->clear_claimed();
477 }
478 }
479
480 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
481 {
482 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
483 Klass* old_value = _klasses;
484 k->set_next_link(old_value);
485 // Link the new item into the list, making sure the linked class is stable
486 // since the list can be walked without a lock
487 OrderAccess::release_store(&_klasses, k);
488 if (k->is_array_klass()) {
489 ClassLoaderDataGraph::inc_array_classes(1);
490 } else {
491 ClassLoaderDataGraph::inc_instance_classes(1);
492 }
493 }
494
495 if (publicize) {
496 LogTarget(Trace, class, loader, data) lt;
497 if (lt.is_enabled()) {
498 ResourceMark rm;
499 LogStream ls(lt);
500 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
501 print_value_on(&ls);
502 ls.cr();
503 }
504 }
505 }
506
507 // Class iterator used by the compiler. It gets some number of classes at
508 // a safepoint to decay invocation counters on the methods.
509 class ClassLoaderDataGraphKlassIteratorStatic {
510 ClassLoaderData* _current_loader_data;
511 Klass* _current_class_entry;
512 public:
513
514 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
515
516 InstanceKlass* try_get_next_class() {
517 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
518 size_t max_classes = ClassLoaderDataGraph::num_instance_classes();
519 assert(max_classes > 0, "should not be called with no instance classes");
520 for (size_t i = 0; i < max_classes; ) {
521
522 if (_current_class_entry != NULL) {
523 Klass* k = _current_class_entry;
524 _current_class_entry = _current_class_entry->next_link();
525
526 if (k->is_instance_klass()) {
527 InstanceKlass* ik = InstanceKlass::cast(k);
528 i++; // count all instance classes found
529 // Not yet loaded classes are counted in max_classes
530 // but only return loaded classes.
531 if (ik->is_loaded()) {
532 return ik;
533 }
534 }
535 } else {
536 // Go to next CLD
537 if (_current_loader_data != NULL) {
538 _current_loader_data = _current_loader_data->next();
539 }
540 // Start at the beginning
541 if (_current_loader_data == NULL) {
542 _current_loader_data = ClassLoaderDataGraph::_head;
543 }
544
545 _current_class_entry = _current_loader_data->klasses();
546 }
547 }
548 // Should never be reached unless all instance classes have failed or are not fully loaded.
549 // Caller handles NULL.
550 return NULL;
551 }
552
553 // If the current class for the static iterator is a class being unloaded or
554 // deallocated, adjust the current class.
555 void adjust_saved_class(ClassLoaderData* cld) {
556 if (_current_loader_data == cld) {
557 _current_loader_data = cld->next();
558 if (_current_loader_data != NULL) {
559 _current_class_entry = _current_loader_data->klasses();
560 } // else try_get_next_class will start at the head
561 }
562 }
563
564 void adjust_saved_class(Klass* klass) {
565 if (_current_class_entry == klass) {
566 _current_class_entry = klass->next_link();
567 }
568 }
569 };
570
571 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
572
573 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
574 return static_klass_iterator.try_get_next_class();
575 }
576
577
578 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
579 if (loader_or_mirror() != NULL) {
580 assert(_holder.is_null(), "never replace holders");
581 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror);
582 }
583 }
584
585 // Remove a klass from the _klasses list for scratch_class during redefinition
586 // or parsed class in the case of an error.
587 void ClassLoaderData::remove_class(Klass* scratch_class) {
588 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
589
590 // Adjust global class iterator.
591 static_klass_iterator.adjust_saved_class(scratch_class);
592
593 Klass* prev = NULL;
594 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
595 if (k == scratch_class) {
596 if (prev == NULL) {
597 _klasses = k->next_link();
598 } else {
599 Klass* next = k->next_link();
600 prev->set_next_link(next);
601 }
602
603 if (k->is_array_klass()) {
604 ClassLoaderDataGraph::dec_array_classes(1);
605 } else {
606 ClassLoaderDataGraph::dec_instance_classes(1);
607 }
608
609 return;
610 }
611 prev = k;
612 assert(k != k->next_link(), "no loops!");
613 }
614 ShouldNotReachHere(); // should have found this class!!
615 }
616
617 void ClassLoaderData::unload() {
618 _unloading = true;
619
620 LogTarget(Debug, class, loader, data) lt;
621 if (lt.is_enabled()) {
622 ResourceMark rm;
623 LogStream ls(lt);
624 ls.print("unload");
625 print_value_on(&ls);
626 ls.cr();
627 }
628
629 // Some items on the _deallocate_list need to free their C heap structures
630 // if they are not already on the _klasses list.
631 unload_deallocate_list();
632
633 // Tell serviceability tools these classes are unloading
634 // after erroneous classes are released.
635 classes_do(InstanceKlass::notify_unload_class);
636
637 // Clean up global class iterator for compiler
638 static_klass_iterator.adjust_saved_class(this);
639 }
640
641 ModuleEntryTable* ClassLoaderData::modules() {
642 // Lazily create the module entry table at first request.
643 // Lock-free access requires load_acquire.
644 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
645 if (modules == NULL) {
646 MutexLocker m1(Module_lock);
647 // Check if _modules got allocated while we were waiting for this lock.
648 if ((modules = _modules) == NULL) {
649 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
650
651 {
652 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
653 // Ensure _modules is stable, since it is examined without a lock
654 OrderAccess::release_store(&_modules, modules);
655 }
656 }
657 }
658 return modules;
659 }
660
661 const int _boot_loader_dictionary_size = 1009;
662 const int _default_loader_dictionary_size = 107;
663
664 Dictionary* ClassLoaderData::create_dictionary() {
665 assert(!is_anonymous(), "anonymous class loader data do not have a dictionary");
666 int size;
667 bool resizable = false;
668 if (_the_null_class_loader_data == NULL) {
669 size = _boot_loader_dictionary_size;
670 resizable = true;
671 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
672 size = 1; // there's only one class in relection class loader and no initiated classes
673 } else if (is_system_class_loader_data()) {
674 size = _boot_loader_dictionary_size;
675 resizable = true;
676 } else {
677 size = _default_loader_dictionary_size;
678 resizable = true;
679 }
680 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces || UseSharedSpaces) {
681 resizable = false;
682 }
683 return new Dictionary(this, size, resizable);
684 }
685
686 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
687 oop ClassLoaderData::holder_phantom() const {
688 // A klass that was previously considered dead can be looked up in the
689 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
690 // or a reachable object making it alive again. The SATB part of G1 needs
691 // to get notified about this potential resurrection, otherwise the marking
692 // might not find the object.
693 if (!_holder.is_null()) { // NULL class_loader
694 return _holder.resolve();
695 } else {
696 return NULL;
697 }
698 }
699
700 // Unloading support
701 bool ClassLoaderData::is_alive() const {
702 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
703 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
704
705 return alive;
706 }
707
708 class ReleaseKlassClosure: public KlassClosure {
709 private:
710 size_t _instance_class_released;
711 size_t _array_class_released;
712 public:
713 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
714
715 size_t instance_class_released() const { return _instance_class_released; }
716 size_t array_class_released() const { return _array_class_released; }
717
718 void do_klass(Klass* k) {
719 if (k->is_array_klass()) {
720 _array_class_released ++;
721 } else {
722 assert(k->is_instance_klass(), "Must be");
723 _instance_class_released ++;
724 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
725 }
726 }
727 };
728
729 ClassLoaderData::~ClassLoaderData() {
730 // Release C heap structures for all the classes.
731 ReleaseKlassClosure cl;
732 classes_do(&cl);
733
734 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
735 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
736
737 // Release the WeakHandle
738 _holder.release();
739
740 // Release C heap allocated hashtable for all the packages.
741 if (_packages != NULL) {
742 // Destroy the table itself
743 delete _packages;
744 _packages = NULL;
745 }
746
747 // Release C heap allocated hashtable for all the modules.
748 if (_modules != NULL) {
749 // Destroy the table itself
750 delete _modules;
751 _modules = NULL;
752 }
753
754 // Release C heap allocated hashtable for the dictionary
755 if (_dictionary != NULL) {
756 // Destroy the table itself
757 delete _dictionary;
758 _dictionary = NULL;
759 }
760
761 if (_unnamed_module != NULL) {
762 _unnamed_module->delete_unnamed_module();
763 _unnamed_module = NULL;
764 }
765
766 // release the metaspace
767 ClassLoaderMetaspace *m = _metaspace;
768 if (m != NULL) {
769 _metaspace = NULL;
770 delete m;
771 }
772 // Clear all the JNI handles for methods
773 // These aren't deallocated and are going to look like a leak, but that's
774 // needed because we can't really get rid of jmethodIDs because we don't
775 // know when native code is going to stop using them. The spec says that
776 // they're "invalid" but existing programs likely rely on their being
777 // NULL after class unloading.
778 if (_jmethod_ids != NULL) {
779 Method::clear_jmethod_ids(this);
780 }
781 // Delete lock
782 delete _metaspace_lock;
783
784 // Delete free list
785 if (_deallocate_list != NULL) {
786 delete _deallocate_list;
787 }
788 }
789
790 // Returns true if this class loader data is for the app class loader
791 // or a user defined system class loader. (Note that the class loader
792 // data may be anonymous.)
793 bool ClassLoaderData::is_system_class_loader_data() const {
794 return SystemDictionary::is_system_class_loader(class_loader());
795 }
796
797 // Returns true if this class loader data is for the platform class loader.
798 // (Note that the class loader data may be anonymous.)
799 bool ClassLoaderData::is_platform_class_loader_data() const {
800 return SystemDictionary::is_platform_class_loader(class_loader());
801 }
802
803 // Returns true if the class loader for this class loader data is one of
804 // the 3 builtin (boot application/system or platform) class loaders,
805 // including a user-defined system class loader. Note that if the class
806 // loader data is for an anonymous class then it may get freed by a GC
807 // even if its class loader is one of these loaders.
808 bool ClassLoaderData::is_builtin_class_loader_data() const {
809 return (is_boot_class_loader_data() ||
810 SystemDictionary::is_system_class_loader(class_loader()) ||
811 SystemDictionary::is_platform_class_loader(class_loader()));
812 }
813
814 // Returns true if this class loader data is a class loader data
815 // that is not ever freed by a GC. It must be one of the builtin
816 // class loaders and not anonymous.
817 bool ClassLoaderData::is_permanent_class_loader_data() const {
818 return is_builtin_class_loader_data() && !is_anonymous();
819 }
820
821 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
822 // If the metaspace has not been allocated, create a new one. Might want
823 // to create smaller arena for Reflection class loaders also.
824 // The reason for the delayed allocation is because some class loaders are
825 // simply for delegating with no metadata of their own.
826 // Lock-free access requires load_acquire.
827 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
828 if (metaspace == NULL) {
829 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
830 // Check if _metaspace got allocated while we were waiting for this lock.
831 if ((metaspace = _metaspace) == NULL) {
832 if (this == the_null_class_loader_data()) {
833 assert (class_loader() == NULL, "Must be");
834 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
835 } else if (is_anonymous()) {
836 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
837 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
838 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
839 } else {
840 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
841 }
842 // Ensure _metaspace is stable, since it is examined without a lock
843 OrderAccess::release_store(&_metaspace, metaspace);
844 }
845 }
846 return metaspace;
847 }
848
849 OopHandle ClassLoaderData::add_handle(Handle h) {
850 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
851 record_modified_oops();
852 return OopHandle(_handles.add(h()));
853 }
854
855 void ClassLoaderData::remove_handle(OopHandle h) {
856 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
857 oop* ptr = h.ptr_raw();
858 if (ptr != NULL) {
859 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
860 NativeAccess<>::oop_store(ptr, oop(NULL));
861 }
862 }
863
864 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
865 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
866 if (dest.resolve() != NULL) {
867 return;
868 } else {
869 dest = _handles.add(h());
870 }
871 }
872
873 // Add this metadata pointer to be freed when it's safe. This is only during
874 // class unloading because Handles might point to this metadata field.
875 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
876 // Metadata in shared region isn't deleted.
877 if (!m->is_shared()) {
878 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
879 if (_deallocate_list == NULL) {
880 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
881 }
882 _deallocate_list->append_if_missing(m);
883 }
884 }
885
886 // Deallocate free metadata on the free list. How useful the PermGen was!
887 void ClassLoaderData::free_deallocate_list() {
888 // Don't need lock, at safepoint
889 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
890 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
891 if (_deallocate_list == NULL) {
892 return;
893 }
894 // Go backwards because this removes entries that are freed.
895 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
896 Metadata* m = _deallocate_list->at(i);
897 if (!m->on_stack()) {
898 _deallocate_list->remove_at(i);
899 // There are only three types of metadata that we deallocate directly.
900 // Cast them so they can be used by the template function.
901 if (m->is_method()) {
902 MetadataFactory::free_metadata(this, (Method*)m);
903 } else if (m->is_constantPool()) {
904 MetadataFactory::free_metadata(this, (ConstantPool*)m);
905 } else if (m->is_klass()) {
906 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
907 } else {
908 ShouldNotReachHere();
909 }
910 } else {
911 // Metadata is alive.
912 // If scratch_class is on stack then it shouldn't be on this list!
913 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
914 "scratch classes on this list should be dead");
915 // Also should assert that other metadata on the list was found in handles.
916 }
917 }
918 }
919
920 // This is distinct from free_deallocate_list. For class loader data that are
921 // unloading, this frees the C heap memory for items on the list, and unlinks
922 // scratch or error classes so that unloading events aren't triggered for these
923 // classes. The metadata is removed with the unloading metaspace.
924 // There isn't C heap memory allocated for methods, so nothing is done for them.
925 void ClassLoaderData::unload_deallocate_list() {
926 // Don't need lock, at safepoint
927 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
928 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
929 if (_deallocate_list == NULL) {
930 return;
931 }
932 // Go backwards because this removes entries that are freed.
933 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
934 Metadata* m = _deallocate_list->at(i);
935 assert (!m->on_stack(), "wouldn't be unloading if this were so");
936 _deallocate_list->remove_at(i);
937 if (m->is_constantPool()) {
938 ((ConstantPool*)m)->release_C_heap_structures();
939 } else if (m->is_klass()) {
940 InstanceKlass* ik = (InstanceKlass*)m;
941 // also releases ik->constants() C heap memory
942 InstanceKlass::release_C_heap_structures(ik);
943 // Remove the class so unloading events aren't triggered for
944 // this class (scratch or error class) in do_unloading().
945 remove_class(ik);
946 }
947 }
948 }
949
950 // These anonymous class loaders are to contain classes used for JSR292
951 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(Handle loader) {
952 // Add a new class loader data to the graph.
953 return ClassLoaderDataGraph::add(loader, true);
954 }
955
956 // Caller needs ResourceMark
957 // If the class loader's _name has not been explicitly set, the class loader's
958 // qualified class name is returned.
959 const char* ClassLoaderData::loader_name() const {
960 if (_class_loader_klass == NULL) {
961 return BOOTSTRAP_LOADER_NAME;
962 } else if (_name != NULL) {
963 return _name->as_C_string();
964 } else {
965 return _class_loader_klass->external_name();
966 }
967 }
968
969 // Caller needs ResourceMark
970 // Format of the _name_and_id is as follows:
971 // If the defining loader has a name explicitly set then '<loader-name>' @<id>
972 // If the defining loader has no name then <qualified-class-name> @<id>
973 // If built-in loader, then omit '@<id>' as there is only one instance.
974 const char* ClassLoaderData::loader_name_and_id() const {
975 if (_class_loader_klass == NULL) {
976 return "'" BOOTSTRAP_LOADER_NAME "'";
977 } else if (_name_and_id != NULL) {
978 return _name_and_id->as_C_string();
979 } else {
980 // May be called in a race before _name_and_id is initialized.
981 return _class_loader_klass->external_name();
982 }
983 }
984
985 void ClassLoaderData::print_value_on(outputStream* out) const {
986 if (!is_unloading() && class_loader() != NULL) {
987 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
988 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance
989 } else {
990 // loader data: 0xsomeaddr of 'bootstrap'
991 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
992 }
993 if (is_anonymous()) {
994 out->print(" anonymous");
995 }
996 }
997
998 #ifndef PRODUCT
999 void ClassLoaderData::print_on(outputStream* out) const {
1000 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
1001 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id());
1002 if (is_anonymous()) out->print(" anonymous");
1003 if (claimed()) out->print(" claimed");
1004 if (is_unloading()) out->print(" unloading");
1005 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
1006
1007 if (_jmethod_ids != NULL) {
1008 Method::print_jmethod_ids(this, out);
1009 }
1010 out->print(" handles count %d", _handles.count());
1011 out->print(" dependencies %d", _dependency_count);
1012 out->print_cr("}");
1013 }
1014 #endif // PRODUCT
1015
1016 void ClassLoaderData::verify() {
1017 assert_locked_or_safepoint(_metaspace_lock);
1018 oop cl = class_loader();
1019
1020 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
1021 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
1022
1023 // Verify the integrity of the allocated space.
1024 if (metaspace_or_null() != NULL) {
1025 metaspace_or_null()->verify();
1026 }
1027
1028 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
1029 guarantee(k->class_loader_data() == this, "Must be the same");
1030 k->verify();
1031 assert(k != k->next_link(), "no loops!");
1032 }
1033 }
1034
1035 bool ClassLoaderData::contains_klass(Klass* klass) {
1036 // Lock-free access requires load_acquire
1037 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
1038 if (k == klass) return true;
1039 }
1040 return false;
1041 }
1042
1043
1044 // GC root of class loader data created.
1045 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
1046 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
1047 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
1048 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
1049
1050 bool ClassLoaderDataGraph::_should_purge = false;
1051 bool ClassLoaderDataGraph::_metaspace_oom = false;
1052
1053 // Add a new class loader data node to the list. Assign the newly created
1054 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
1055 ClassLoaderData* ClassLoaderDataGraph::add_to_graph(Handle loader, bool is_anonymous) {
1056 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
1057 // ClassLoaderData in the graph since the CLD
1058 // contains oops in _handles that must be walked.
1059
1060 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous);
1061
1062 if (!is_anonymous) {
1063 // First, Atomically set it
1064 ClassLoaderData* old = java_lang_ClassLoader::cmpxchg_loader_data(cld, loader(), NULL);
1065 if (old != NULL) {
1066 delete cld;
1067 // Returns the data.
1068 return old;
1069 }
1070 }
1071
1072 // We won the race, and therefore the task of adding the data to the list of
1073 // class loader data
1074 ClassLoaderData** list_head = &_head;
1075 ClassLoaderData* next = _head;
1076
1077 do {
1078 cld->set_next(next);
1079 ClassLoaderData* exchanged = Atomic::cmpxchg(cld, list_head, next);
1080 if (exchanged == next) {
1081 LogTarget(Debug, class, loader, data) lt;
1082 if (lt.is_enabled()) {
1083 ResourceMark rm;
1084 LogStream ls(lt);
1085 ls.print("create ");
1086 cld->print_value_on(&ls);
1087 ls.cr();
1088 }
1089 return cld;
1090 }
1091 next = exchanged;
1092 } while (true);
1093 }
1094
1095 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous) {
1096 ClassLoaderData* loader_data = add_to_graph(loader, is_anonymous);
1097 // Initialize _name and _name_and_id after the loader data is added to the
1098 // CLDG because adding the Symbol for _name and _name_and_id might safepoint.
1099 if (loader.not_null()) {
1100 loader_data->initialize_name(loader);
1101 }
1102 return loader_data;
1103 }
1104
1105 void ClassLoaderDataGraph::oops_do(OopClosure* f, bool must_claim) {
1106 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1107 cld->oops_do(f, must_claim);
1108 }
1109 }
1110
1111 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, bool must_claim) {
1112 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1113 if (cld->keep_alive()) {
1114 cld->oops_do(f, must_claim);
1115 }
1116 }
1117 }
1118
1119 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, bool must_claim) {
1120 if (ClassUnloading) {
1121 keep_alive_oops_do(f, must_claim);
1122 } else {
1123 oops_do(f, must_claim);
1124 }
1125 }
1126
1127 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1128 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
1129 cl->do_cld(cld);
1130 }
1131 }
1132
1133 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1134 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1135 // Only walk the head until any clds not purged from prior unloading
1136 // (CMS doesn't purge right away).
1137 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1138 assert(cld->is_unloading(), "invariant");
1139 cl->do_cld(cld);
1140 }
1141 }
1142
1143 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1144 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1145 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1146 if (closure != NULL) {
1147 closure->do_cld(cld);
1148 }
1149 }
1150 }
1151
1152 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
1153 roots_cld_do(cl, NULL);
1154 }
1155
1156 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1157 if (ClassUnloading) {
1158 keep_alive_cld_do(cl);
1159 } else {
1160 cld_do(cl);
1161 }
1162 }
1163
1164 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1165 Thread* thread = Thread::current();
1166 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1167 Handle holder(thread, cld->holder_phantom());
1168 cld->classes_do(klass_closure);
1169 }
1170 }
1171
1172 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1173 Thread* thread = Thread::current();
1174 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1175 Handle holder(thread, cld->holder_phantom());
1176 cld->classes_do(f);
1177 }
1178 }
1179
1180 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1181 Thread* thread = Thread::current();
1182 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1183 Handle holder(thread, cld->holder_phantom());
1184 cld->methods_do(f);
1185 }
1186 }
1187
1188 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1189 assert_locked_or_safepoint(Module_lock);
1190 Thread* thread = Thread::current();
1191 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1192 Handle holder(thread, cld->holder_phantom());
1193 cld->modules_do(f);
1194 }
1195 }
1196
1197 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1198 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1199 // Only walk the head until any clds not purged from prior unloading
1200 // (CMS doesn't purge right away).
1201 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1202 assert(cld->is_unloading(), "invariant");
1203 cld->modules_do(f);
1204 }
1205 }
1206
1207 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1208 assert_locked_or_safepoint(Module_lock);
1209 Thread* thread = Thread::current();
1210 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1211 Handle holder(thread, cld->holder_phantom());
1212 cld->packages_do(f);
1213 }
1214 }
1215
1216 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1217 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1218 // Only walk the head until any clds not purged from prior unloading
1219 // (CMS doesn't purge right away).
1220 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1221 assert(cld->is_unloading(), "invariant");
1222 cld->packages_do(f);
1223 }
1224 }
1225
1226 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1227 Thread* thread = Thread::current();
1228 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1229 Handle holder(thread, cld->holder_phantom());
1230 cld->loaded_classes_do(klass_closure);
1231 }
1232 }
1233
1234 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1235 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1236 // Only walk the head until any clds not purged from prior unloading
1237 // (CMS doesn't purge right away).
1238 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1239 assert(cld->is_unloading(), "invariant");
1240 cld->classes_do(f);
1241 }
1242 }
1243
1244 #define FOR_ALL_DICTIONARY(X) for (ClassLoaderData* X = _head; X != NULL; X = X->next()) \
1245 if (X->dictionary() != NULL)
1246
1247 // Walk classes in the loaded class dictionaries in various forms.
1248 // Only walks the classes defined in this class loader.
1249 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1250 Thread* thread = Thread::current();
1251 FOR_ALL_DICTIONARY(cld) {
1252 Handle holder(thread, cld->holder_phantom());
1253 cld->dictionary()->classes_do(f);
1254 }
1255 }
1256
1257 // Only walks the classes defined in this class loader.
1258 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1259 Thread* thread = Thread::current();
1260 FOR_ALL_DICTIONARY(cld) {
1261 Handle holder(thread, cld->holder_phantom());
1262 cld->dictionary()->classes_do(f, CHECK);
1263 }
1264 }
1265
1266 // Walks all entries in the dictionary including entries initiated by this class loader.
1267 void ClassLoaderDataGraph::dictionary_all_entries_do(void f(InstanceKlass*, ClassLoaderData*)) {
1268 Thread* thread = Thread::current();
1269 FOR_ALL_DICTIONARY(cld) {
1270 Handle holder(thread, cld->holder_phantom());
1271 cld->dictionary()->all_entries_do(f);
1272 }
1273 }
1274
1275 void ClassLoaderDataGraph::verify_dictionary() {
1276 FOR_ALL_DICTIONARY(cld) {
1277 cld->dictionary()->verify();
1278 }
1279 }
1280
1281 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1282 FOR_ALL_DICTIONARY(cld) {
1283 st->print("Dictionary for ");
1284 cld->print_value_on(st);
1285 st->cr();
1286 cld->dictionary()->print_on(st);
1287 st->cr();
1288 }
1289 }
1290
1291 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1292 FOR_ALL_DICTIONARY(cld) {
1293 ResourceMark rm;
1294 stringStream tempst;
1295 tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id());
1296 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1297 }
1298 }
1299
1300 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1301 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1302
1303 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1304
1305 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1306 ClassLoaderData* curr = _head;
1307 while (curr != _saved_head) {
1308 if (!curr->claimed()) {
1309 array->push(curr);
1310 LogTarget(Debug, class, loader, data) lt;
1311 if (lt.is_enabled()) {
1312 LogStream ls(lt);
1313 ls.print("found new CLD: ");
1314 curr->print_value_on(&ls);
1315 ls.cr();
1316 }
1317 }
1318
1319 curr = curr->_next;
1320 }
1321
1322 return array;
1323 }
1324
1325 #ifndef PRODUCT
1326 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1327 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1328 if (loader_data == data) {
1329 return true;
1330 }
1331 }
1332
1333 return false;
1334 }
1335 #endif // PRODUCT
1336
1337 #if INCLUDE_JFR
1338 static Ticks class_unload_time;
1339 static void post_class_unload_event(Klass* const k) {
1340 assert(k != NULL, "invariant");
1341 EventClassUnload event(UNTIMED);
1342 event.set_endtime(class_unload_time);
1343 event.set_unloadedClass(k);
1344 event.set_definingClassLoader(k->class_loader_data());
1345 event.commit();
1346 }
1347
1348 static void post_class_unload_events() {
1349 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1350 if (Jfr::is_enabled()) {
1351 if (EventClassUnload::is_enabled()) {
1352 class_unload_time = Ticks::now();
1353 ClassLoaderDataGraph::classes_unloading_do(&post_class_unload_event);
1354 }
1355 Jfr::on_unloading_classes();
1356 }
1357 }
1358 #endif // INCLUDE_JFR
1359
1360 // Move class loader data from main list to the unloaded list for unloading
1361 // and deallocation later.
1362 bool ClassLoaderDataGraph::do_unloading(bool clean_previous_versions) {
1363
1364 ClassLoaderData* data = _head;
1365 ClassLoaderData* prev = NULL;
1366 bool seen_dead_loader = false;
1367 uint loaders_processed = 0;
1368 uint loaders_removed = 0;
1369
1370 // Mark metadata seen on the stack only so we can delete unneeded entries.
1371 // Only walk all metadata, including the expensive code cache walk, for Full GC
1372 // and only if class redefinition and if there's previous versions of
1373 // Klasses to delete.
1374 bool walk_all_metadata = clean_previous_versions &&
1375 JvmtiExport::has_redefined_a_class() &&
1376 InstanceKlass::has_previous_versions_and_reset();
1377 MetadataOnStackMark md_on_stack(walk_all_metadata);
1378
1379 // Save previous _unloading pointer for CMS which may add to unloading list before
1380 // purging and we don't want to rewalk the previously unloaded class loader data.
1381 _saved_unloading = _unloading;
1382
1383 data = _head;
1384 while (data != NULL) {
1385 if (data->is_alive()) {
1386 // clean metaspace
1387 if (walk_all_metadata) {
1388 data->classes_do(InstanceKlass::purge_previous_versions);
1389 }
1390 data->free_deallocate_list();
1391 prev = data;
1392 data = data->next();
1393 loaders_processed++;
1394 continue;
1395 }
1396 seen_dead_loader = true;
1397 loaders_removed++;
1398 ClassLoaderData* dead = data;
1399 dead->unload();
1400 data = data->next();
1401 // Remove from loader list.
1402 // This class loader data will no longer be found
1403 // in the ClassLoaderDataGraph.
1404 if (prev != NULL) {
1405 prev->set_next(data);
1406 } else {
1407 assert(dead == _head, "sanity check");
1408 _head = data;
1409 }
1410 dead->set_next(_unloading);
1411 _unloading = dead;
1412 }
1413
1414 if (seen_dead_loader) {
1415 data = _head;
1416 while (data != NULL) {
1417 // Remove entries in the dictionary of live class loader that have
1418 // initiated loading classes in a dead class loader.
1419 if (data->dictionary() != NULL) {
1420 data->dictionary()->do_unloading();
1421 }
1422 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1423 // lists to determine if there are modules on those lists that are now
1424 // dead and should be removed. A module's life cycle is equivalent
1425 // to its defining class loader's life cycle. Since a module is
1426 // considered dead if its class loader is dead, these walks must
1427 // occur after each class loader's aliveness is determined.
1428 if (data->packages() != NULL) {
1429 data->packages()->purge_all_package_exports();
1430 }
1431 if (data->modules_defined()) {
1432 data->modules()->purge_all_module_reads();
1433 }
1434 data = data->next();
1435 }
1436 JFR_ONLY(post_class_unload_events();)
1437 }
1438
1439 log_debug(class, loader, data)("do_unloading: loaders processed %u, loaders removed %u", loaders_processed, loaders_removed);
1440
1441 return seen_dead_loader;
1442 }
1443
1444 void ClassLoaderDataGraph::purge() {
1445 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1446 ClassLoaderData* list = _unloading;
1447 _unloading = NULL;
1448 ClassLoaderData* next = list;
1449 bool classes_unloaded = false;
1450 while (next != NULL) {
1451 ClassLoaderData* purge_me = next;
1452 next = purge_me->next();
1453 delete purge_me;
1454 classes_unloaded = true;
1455 }
1456 if (classes_unloaded) {
1457 Metaspace::purge();
1458 set_metaspace_oom(false);
1459 }
1460 }
1461
1462 int ClassLoaderDataGraph::resize_if_needed() {
1463 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1464 int resized = 0;
1465 if (Dictionary::does_any_dictionary_needs_resizing()) {
1466 FOR_ALL_DICTIONARY(cld) {
1467 if (cld->dictionary()->resize_if_needed()) {
1468 resized++;
1469 }
1470 }
1471 }
1472 return resized;
1473 }
1474
1475 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1476 : _next_klass(NULL) {
1477 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1478 Klass* klass = NULL;
1479
1480 // Find the first klass in the CLDG.
1481 while (cld != NULL) {
1482 assert_locked_or_safepoint(cld->metaspace_lock());
1483 klass = cld->_klasses;
1484 if (klass != NULL) {
1485 _next_klass = klass;
1486 return;
1487 }
1488 cld = cld->next();
1489 }
1490 }
1491
1492 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1493 Klass* next = klass->next_link();
1494 if (next != NULL) {
1495 return next;
1496 }
1497
1498 // No more klasses in the current CLD. Time to find a new CLD.
1499 ClassLoaderData* cld = klass->class_loader_data();
1500 assert_locked_or_safepoint(cld->metaspace_lock());
1501 while (next == NULL) {
1502 cld = cld->next();
1503 if (cld == NULL) {
1504 break;
1505 }
1506 next = cld->_klasses;
1507 }
1508
1509 return next;
1510 }
1511
1512 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1513 Klass* head = _next_klass;
1514
1515 while (head != NULL) {
1516 Klass* next = next_klass_in_cldg(head);
1517
1518 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1519
1520 if (old_head == head) {
1521 return head; // Won the CAS.
1522 }
1523
1524 head = old_head;
1525 }
1526
1527 // Nothing more for the iterator to hand out.
1528 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1529 return NULL;
1530 }
1531
1532 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1533 _data = ClassLoaderDataGraph::_head;
1534 }
1535
1536 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1537
1538 #ifndef PRODUCT
1539 // callable from debugger
1540 extern "C" int print_loader_data_graph() {
1541 ResourceMark rm;
1542 ClassLoaderDataGraph::print_on(tty);
1543 return 0;
1544 }
1545
1546 void ClassLoaderDataGraph::verify() {
1547 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1548 data->verify();
1549 }
1550 }
1551
1552 void ClassLoaderDataGraph::print_on(outputStream * const out) {
1553 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1554 data->print_on(out);
1555 }
1556 }
1557 #endif // PRODUCT