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.inline.hpp"
51 #include "classfile/classLoaderDataGraph.inline.hpp"
52 #include "classfile/dictionary.hpp"
53 #include "classfile/javaClasses.hpp"
54 #include "classfile/moduleEntry.hpp"
55 #include "classfile/packageEntry.hpp"
56 #include "classfile/symbolTable.hpp"
57 #include "classfile/systemDictionary.hpp"
58 #include "logging/log.hpp"
59 #include "logging/logStream.hpp"
60 #include "memory/allocation.inline.hpp"
61 #include "memory/metadataFactory.hpp"
62 #include "memory/resourceArea.hpp"
63 #include "oops/access.inline.hpp"
64 #include "oops/oop.inline.hpp"
65 #include "oops/oopHandle.inline.hpp"
66 #include "oops/weakHandle.inline.hpp"
67 #include "runtime/atomic.hpp"
68 #include "runtime/handles.inline.hpp"
69 #include "runtime/mutex.hpp"
70 #include "runtime/orderAccess.hpp"
71 #include "runtime/safepoint.hpp"
72 #include "utilities/growableArray.hpp"
73 #include "utilities/macros.hpp"
74 #include "utilities/ostream.hpp"
75
76 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
77
78 void ClassLoaderData::init_null_class_loader_data() {
79 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
80 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
81
82 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
83 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
84 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
85
86 LogTarget(Trace, class, loader, data) lt;
87 if (lt.is_enabled()) {
88 ResourceMark rm;
89 LogStream ls(lt);
90 ls.print("create ");
91 _the_null_class_loader_data->print_value_on(&ls);
92 ls.cr();
93 }
94 }
95
96 // Obtain and set the class loader's name within the ClassLoaderData so
97 // it will be available for error messages, logging, JFR, etc. The name
98 // and klass are available after the class_loader oop is no longer alive,
99 // during unloading.
100 void ClassLoaderData::initialize_name(Handle class_loader) {
101 Thread* THREAD = Thread::current();
102 ResourceMark rm(THREAD);
103
104 // Obtain the class loader's name. If the class loader's name was not
105 // explicitly set during construction, the CLD's _name field will be null.
106 oop cl_name = java_lang_ClassLoader::name(class_loader());
107 if (cl_name != NULL) {
108 const char* cl_instance_name = java_lang_String::as_utf8_string(cl_name);
109
110 if (cl_instance_name != NULL && cl_instance_name[0] != '\0') {
111 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore.
112 _name = SymbolTable::new_symbol(cl_instance_name, CATCH);
113 }
114 }
115
116 // Obtain the class loader's name and identity hash. If the class loader's
117 // name was not explicitly set during construction, the class loader's name and id
118 // will be set to the qualified class name of the class loader along with its
119 // identity hash.
120 // If for some reason the ClassLoader's constructor has not been run, instead of
121 // leaving the _name_and_id field null, fall back to the external qualified class
122 // name. Thus CLD's _name_and_id field should never have a null value.
123 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader());
124 const char* cl_instance_name_and_id =
125 (cl_name_and_id == NULL) ? _class_loader_klass->external_name() :
126 java_lang_String::as_utf8_string(cl_name_and_id);
127 assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id");
128 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore.
129 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id, CATCH);
130 }
131
132 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_unsafe_anonymous) :
133 _metaspace(NULL),
134 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
135 Monitor::_safepoint_check_never)),
136 _unloading(false), _is_unsafe_anonymous(is_unsafe_anonymous),
137 _modified_oops(true), _accumulated_modified_oops(false),
138 // An unsafe anonymous class loader data doesn't have anything to keep
139 // it from being unloaded during parsing of the unsafe anonymous class.
140 // The null-class-loader should always be kept alive.
141 _keep_alive((is_unsafe_anonymous || h_class_loader.is_null()) ? 1 : 0),
142 _claimed(0),
143 _handles(),
144 _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL),
145 _jmethod_ids(NULL),
146 _deallocate_list(NULL),
147 _next(NULL),
148 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL) {
149
150 if (!h_class_loader.is_null()) {
151 _class_loader = _handles.add(h_class_loader());
152 _class_loader_klass = h_class_loader->klass();
153 initialize_name(h_class_loader);
154 }
155
156 if (!is_unsafe_anonymous) {
157 // The holder is initialized later for unsafe anonymous classes, and before calling anything
158 // that call class_loader().
159 initialize_holder(h_class_loader);
160
161 // A ClassLoaderData created solely for an unsafe anonymous class should never have a
162 // ModuleEntryTable or PackageEntryTable created for it. The defining package
163 // and module for an unsafe anonymous class will be found in its host class.
164 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
165 if (h_class_loader.is_null()) {
166 // Create unnamed module for boot loader
167 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
168 } else {
169 // Create unnamed module for all other loaders
170 _unnamed_module = ModuleEntry::create_unnamed_module(this);
171 }
172 _dictionary = create_dictionary();
173 }
174
175 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
176
177 JFR_ONLY(INIT_ID(this);)
178 }
179
180 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
181 Chunk* c = _head;
182 while (c != NULL) {
183 Chunk* next = c->_next;
184 delete c;
185 c = next;
186 }
187 }
188
189 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
190 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
191 Chunk* next = new Chunk(_head);
192 OrderAccess::release_store(&_head, next);
193 }
194 oop* handle = &_head->_data[_head->_size];
195 *handle = o;
196 OrderAccess::release_store(&_head->_size, _head->_size + 1);
197 return handle;
198 }
199
200 int ClassLoaderData::ChunkedHandleList::count() const {
201 int count = 0;
202 Chunk* chunk = _head;
203 while (chunk != NULL) {
204 count += chunk->_size;
205 chunk = chunk->_next;
206 }
207 return count;
208 }
209
210 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
211 for (juint i = 0; i < size; i++) {
212 if (c->_data[i] != NULL) {
213 f->do_oop(&c->_data[i]);
214 }
215 }
216 }
217
218 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
219 Chunk* head = OrderAccess::load_acquire(&_head);
220 if (head != NULL) {
221 // Must be careful when reading size of head
222 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
223 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
224 oops_do_chunk(f, c, c->_size);
225 }
226 }
227 }
228
229 class VerifyContainsOopClosure : public OopClosure {
230 oop _target;
231 bool _found;
232
233 public:
234 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
235
236 void do_oop(oop* p) {
237 if (p != NULL && oopDesc::equals(RawAccess<>::oop_load(p), _target)) {
238 _found = true;
239 }
240 }
241
242 void do_oop(narrowOop* p) {
243 // The ChunkedHandleList should not contain any narrowOop
244 ShouldNotReachHere();
245 }
246
247 bool found() const {
248 return _found;
249 }
250 };
251
252 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
253 VerifyContainsOopClosure cl(p);
254 oops_do(&cl);
255 return cl.found();
256 }
257
258 #ifndef PRODUCT
259 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
260 Chunk* chunk = _head;
261 while (chunk != NULL) {
262 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
263 return true;
264 }
265 chunk = chunk->_next;
266 }
267 return false;
268 }
269 #endif // PRODUCT
270
271 bool ClassLoaderData::claim() {
272 if (_claimed == 1) {
273 return false;
274 }
275
276 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
277 }
278
279 // Unsafe anonymous classes have their own ClassLoaderData that is marked to keep alive
280 // while the class is being parsed, and if the class appears on the module fixup list.
281 // Due to the uniqueness that no other class shares the unsafe anonymous class' name or
282 // ClassLoaderData, no other non-GC thread has knowledge of the unsafe anonymous class while
283 // it is being defined, therefore _keep_alive is not volatile or atomic.
284 void ClassLoaderData::inc_keep_alive() {
285 if (is_unsafe_anonymous()) {
286 assert(_keep_alive >= 0, "Invalid keep alive increment count");
287 _keep_alive++;
288 }
289 }
290
291 void ClassLoaderData::dec_keep_alive() {
292 if (is_unsafe_anonymous()) {
293 assert(_keep_alive > 0, "Invalid keep alive decrement count");
294 _keep_alive--;
295 }
296 }
297
298 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
299 if (must_claim && !claim()) {
300 return;
301 }
302
303 // Only clear modified_oops after the ClassLoaderData is claimed.
304 if (clear_mod_oops) {
305 clear_modified_oops();
306 }
307
308 _handles.oops_do(f);
309 }
310
311 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
312 // Lock-free access requires load_acquire
313 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
314 klass_closure->do_klass(k);
315 assert(k != k->next_link(), "no loops!");
316 }
317 }
318
319 void ClassLoaderData::classes_do(void f(Klass * const)) {
320 // Lock-free access requires load_acquire
321 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
322 f(k);
323 assert(k != k->next_link(), "no loops!");
324 }
325 }
326
327 void ClassLoaderData::methods_do(void f(Method*)) {
328 // Lock-free access requires load_acquire
329 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
330 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
331 InstanceKlass::cast(k)->methods_do(f);
332 }
333 }
334 }
335
336 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
337 // Lock-free access requires load_acquire
338 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
339 // Do not filter ArrayKlass oops here...
340 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
341 #ifdef ASSERT
342 oop m = k->java_mirror();
343 assert(m != NULL, "NULL mirror");
344 assert(m->is_a(SystemDictionary::Class_klass()), "invalid mirror");
345 #endif
346 klass_closure->do_klass(k);
347 }
348 }
349 }
350
351 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
352 // Lock-free access requires load_acquire
353 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
354 if (k->is_instance_klass()) {
355 f(InstanceKlass::cast(k));
356 }
357 assert(k != k->next_link(), "no loops!");
358 }
359 }
360
361 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
362 assert_locked_or_safepoint(Module_lock);
363 if (_unnamed_module != NULL) {
364 f(_unnamed_module);
365 }
366 if (_modules != NULL) {
367 for (int i = 0; i < _modules->table_size(); i++) {
368 for (ModuleEntry* entry = _modules->bucket(i);
369 entry != NULL;
370 entry = entry->next()) {
371 f(entry);
372 }
373 }
374 }
375 }
376
377 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
378 assert_locked_or_safepoint(Module_lock);
379 if (_packages != NULL) {
380 for (int i = 0; i < _packages->table_size(); i++) {
381 for (PackageEntry* entry = _packages->bucket(i);
382 entry != NULL;
383 entry = entry->next()) {
384 f(entry);
385 }
386 }
387 }
388 }
389
390 void ClassLoaderData::record_dependency(const Klass* k) {
391 assert(k != NULL, "invariant");
392
393 ClassLoaderData * const from_cld = this;
394 ClassLoaderData * const to_cld = k->class_loader_data();
395
396 // Do not need to record dependency if the dependency is to a class whose
397 // class loader data is never freed. (i.e. the dependency's class loader
398 // is one of the three builtin class loaders and the dependency is not
399 // unsafe anonymous.)
400 if (to_cld->is_permanent_class_loader_data()) {
401 return;
402 }
403
404 oop to;
405 if (to_cld->is_unsafe_anonymous()) {
406 // Just return if an unsafe anonymous class is attempting to record a dependency
407 // to itself. (Note that every unsafe anonymous class has its own unique class
408 // loader data.)
409 if (to_cld == from_cld) {
410 return;
411 }
412 // Unsafe anonymous class dependencies are through the mirror.
413 to = k->java_mirror();
414 } else {
415 to = to_cld->class_loader();
416 oop from = from_cld->class_loader();
417
418 // Just return if this dependency is to a class with the same or a parent
419 // class_loader.
420 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) {
421 return; // this class loader is in the parent list, no need to add it.
422 }
423 }
424
425 // It's a dependency we won't find through GC, add it.
426 if (!_handles.contains(to)) {
427 NOT_PRODUCT(Atomic::inc(&_dependency_count));
428 LogTarget(Trace, class, loader, data) lt;
429 if (lt.is_enabled()) {
430 ResourceMark rm;
431 LogStream ls(lt);
432 ls.print("adding dependency from ");
433 print_value_on(&ls);
434 ls.print(" to ");
435 to_cld->print_value_on(&ls);
436 ls.cr();
437 }
438 Handle dependency(Thread::current(), to);
439 add_handle(dependency);
440 // Added a potentially young gen oop to the ClassLoaderData
441 record_modified_oops();
442 }
443 }
444
445 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
446 {
447 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
448 Klass* old_value = _klasses;
449 k->set_next_link(old_value);
450 // Link the new item into the list, making sure the linked class is stable
451 // since the list can be walked without a lock
452 OrderAccess::release_store(&_klasses, k);
453 if (k->is_array_klass()) {
454 ClassLoaderDataGraph::inc_array_classes(1);
455 } else {
456 ClassLoaderDataGraph::inc_instance_classes(1);
457 }
458 }
459
460 if (publicize) {
461 LogTarget(Trace, class, loader, data) lt;
462 if (lt.is_enabled()) {
463 ResourceMark rm;
464 LogStream ls(lt);
465 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
466 print_value_on(&ls);
467 ls.cr();
468 }
469 }
470 }
471
472 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
473 if (loader_or_mirror() != NULL) {
474 assert(_holder.is_null(), "never replace holders");
475 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror);
476 }
477 }
478
479 // Remove a klass from the _klasses list for scratch_class during redefinition
480 // or parsed class in the case of an error.
481 void ClassLoaderData::remove_class(Klass* scratch_class) {
482 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
483
484 // Adjust global class iterator.
485 ClassLoaderDataGraph::adjust_saved_class(scratch_class);
486
487 Klass* prev = NULL;
488 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
489 if (k == scratch_class) {
490 if (prev == NULL) {
491 _klasses = k->next_link();
492 } else {
493 Klass* next = k->next_link();
494 prev->set_next_link(next);
495 }
496
497 if (k->is_array_klass()) {
498 ClassLoaderDataGraph::dec_array_classes(1);
499 } else {
500 ClassLoaderDataGraph::dec_instance_classes(1);
501 }
502
503 return;
504 }
505 prev = k;
506 assert(k != k->next_link(), "no loops!");
507 }
508 ShouldNotReachHere(); // should have found this class!!
509 }
510
511 void ClassLoaderData::unload() {
512 _unloading = true;
513
514 LogTarget(Trace, class, loader, data) lt;
515 if (lt.is_enabled()) {
516 ResourceMark rm;
517 LogStream ls(lt);
518 ls.print("unload");
519 print_value_on(&ls);
520 ls.cr();
521 }
522
523 // Some items on the _deallocate_list need to free their C heap structures
524 // if they are not already on the _klasses list.
525 free_deallocate_list_C_heap_structures();
526
527 // Clean up class dependencies and tell serviceability tools
528 // these classes are unloading. Must be called
529 // after erroneous classes are released.
530 classes_do(InstanceKlass::unload_class);
531
532 // Clean up global class iterator for compiler
533 ClassLoaderDataGraph::adjust_saved_class(this);
534 }
535
536 ModuleEntryTable* ClassLoaderData::modules() {
537 // Lazily create the module entry table at first request.
538 // Lock-free access requires load_acquire.
539 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
540 if (modules == NULL) {
541 MutexLocker m1(Module_lock);
542 // Check if _modules got allocated while we were waiting for this lock.
543 if ((modules = _modules) == NULL) {
544 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
545
546 {
547 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
548 // Ensure _modules is stable, since it is examined without a lock
549 OrderAccess::release_store(&_modules, modules);
550 }
551 }
552 }
553 return modules;
554 }
555
556 const int _boot_loader_dictionary_size = 1009;
557 const int _default_loader_dictionary_size = 107;
558
559 Dictionary* ClassLoaderData::create_dictionary() {
560 assert(!is_unsafe_anonymous(), "unsafe anonymous class loader data do not have a dictionary");
561 int size;
562 bool resizable = false;
563 if (_the_null_class_loader_data == NULL) {
564 size = _boot_loader_dictionary_size;
565 resizable = true;
566 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
567 size = 1; // there's only one class in relection class loader and no initiated classes
568 } else if (is_system_class_loader_data()) {
569 size = _boot_loader_dictionary_size;
570 resizable = true;
571 } else {
572 size = _default_loader_dictionary_size;
573 resizable = true;
574 }
575 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) {
576 resizable = false;
577 }
578 return new Dictionary(this, size, resizable);
579 }
580
581 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
582 oop ClassLoaderData::holder_phantom() const {
583 // A klass that was previously considered dead can be looked up in the
584 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
585 // or a reachable object making it alive again. The SATB part of G1 needs
586 // to get notified about this potential resurrection, otherwise the marking
587 // might not find the object.
588 if (!_holder.is_null()) { // NULL class_loader
589 return _holder.resolve();
590 } else {
591 return NULL;
592 }
593 }
594
595 // Let the GC read the holder without keeping it alive.
596 oop ClassLoaderData::holder_no_keepalive() const {
597 if (!_holder.is_null()) { // NULL class_loader
598 return _holder.peek();
599 } else {
600 return NULL;
601 }
602 }
603
604 // Unloading support
605 bool ClassLoaderData::is_alive() const {
606 bool alive = keep_alive() // null class loader and incomplete unsafe anonymous klasses.
607 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
608
609 return alive;
610 }
611
612 class ReleaseKlassClosure: public KlassClosure {
613 private:
614 size_t _instance_class_released;
615 size_t _array_class_released;
616 public:
617 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
618
619 size_t instance_class_released() const { return _instance_class_released; }
620 size_t array_class_released() const { return _array_class_released; }
621
622 void do_klass(Klass* k) {
623 if (k->is_array_klass()) {
624 _array_class_released ++;
625 } else {
626 assert(k->is_instance_klass(), "Must be");
627 _instance_class_released ++;
628 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
629 }
630 }
631 };
632
633 ClassLoaderData::~ClassLoaderData() {
634 // Release C heap structures for all the classes.
635 ReleaseKlassClosure cl;
636 classes_do(&cl);
637
638 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
639 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
640
641 // Release the WeakHandle
642 _holder.release();
643
644 // Release C heap allocated hashtable for all the packages.
645 if (_packages != NULL) {
646 // Destroy the table itself
647 delete _packages;
648 _packages = NULL;
649 }
650
651 // Release C heap allocated hashtable for all the modules.
652 if (_modules != NULL) {
653 // Destroy the table itself
654 delete _modules;
655 _modules = NULL;
656 }
657
658 // Release C heap allocated hashtable for the dictionary
659 if (_dictionary != NULL) {
660 // Destroy the table itself
661 delete _dictionary;
662 _dictionary = NULL;
663 }
664
665 if (_unnamed_module != NULL) {
666 _unnamed_module->delete_unnamed_module();
667 _unnamed_module = NULL;
668 }
669
670 // release the metaspace
671 ClassLoaderMetaspace *m = _metaspace;
672 if (m != NULL) {
673 _metaspace = NULL;
674 delete m;
675 }
676 // Clear all the JNI handles for methods
677 // These aren't deallocated and are going to look like a leak, but that's
678 // needed because we can't really get rid of jmethodIDs because we don't
679 // know when native code is going to stop using them. The spec says that
680 // they're "invalid" but existing programs likely rely on their being
681 // NULL after class unloading.
682 if (_jmethod_ids != NULL) {
683 Method::clear_jmethod_ids(this);
684 }
685 // Delete lock
686 delete _metaspace_lock;
687
688 // Delete free list
689 if (_deallocate_list != NULL) {
690 delete _deallocate_list;
691 }
692
693 // Decrement refcounts of Symbols if created.
694 if (_name != NULL) {
695 _name->decrement_refcount();
696 }
697 if (_name_and_id != NULL) {
698 _name_and_id->decrement_refcount();
699 }
700 }
701
702 // Returns true if this class loader data is for the app class loader
703 // or a user defined system class loader. (Note that the class loader
704 // data may be unsafe anonymous.)
705 bool ClassLoaderData::is_system_class_loader_data() const {
706 return SystemDictionary::is_system_class_loader(class_loader());
707 }
708
709 // Returns true if this class loader data is for the platform class loader.
710 // (Note that the class loader data may be unsafe anonymous.)
711 bool ClassLoaderData::is_platform_class_loader_data() const {
712 return SystemDictionary::is_platform_class_loader(class_loader());
713 }
714
715 // Returns true if the class loader for this class loader data is one of
716 // the 3 builtin (boot application/system or platform) class loaders,
717 // including a user-defined system class loader. Note that if the class
718 // loader data is for an unsafe anonymous class then it may get freed by a GC
719 // even if its class loader is one of these loaders.
720 bool ClassLoaderData::is_builtin_class_loader_data() const {
721 return (is_boot_class_loader_data() ||
722 SystemDictionary::is_system_class_loader(class_loader()) ||
723 SystemDictionary::is_platform_class_loader(class_loader()));
724 }
725
726 // Returns true if this class loader data is a class loader data
727 // that is not ever freed by a GC. It must be the CLD for one of the builtin
728 // class loaders and not the CLD for an unsafe anonymous class.
729 bool ClassLoaderData::is_permanent_class_loader_data() const {
730 return is_builtin_class_loader_data() && !is_unsafe_anonymous();
731 }
732
733 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
734 // If the metaspace has not been allocated, create a new one. Might want
735 // to create smaller arena for Reflection class loaders also.
736 // The reason for the delayed allocation is because some class loaders are
737 // simply for delegating with no metadata of their own.
738 // Lock-free access requires load_acquire.
739 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
740 if (metaspace == NULL) {
741 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
742 // Check if _metaspace got allocated while we were waiting for this lock.
743 if ((metaspace = _metaspace) == NULL) {
744 if (this == the_null_class_loader_data()) {
745 assert (class_loader() == NULL, "Must be");
746 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
747 } else if (is_unsafe_anonymous()) {
748 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::UnsafeAnonymousMetaspaceType);
749 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
750 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
751 } else {
752 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
753 }
754 // Ensure _metaspace is stable, since it is examined without a lock
755 OrderAccess::release_store(&_metaspace, metaspace);
756 }
757 }
758 return metaspace;
759 }
760
761 OopHandle ClassLoaderData::add_handle(Handle h) {
762 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
763 record_modified_oops();
764 return OopHandle(_handles.add(h()));
765 }
766
767 void ClassLoaderData::remove_handle(OopHandle h) {
768 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
769 oop* ptr = h.ptr_raw();
770 if (ptr != NULL) {
771 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
772 NativeAccess<>::oop_store(ptr, oop(NULL));
773 }
774 }
775
776 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
777 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
778 if (dest.resolve() != NULL) {
779 return;
780 } else {
781 dest = _handles.add(h());
782 }
783 }
784
785 // Add this metadata pointer to be freed when it's safe. This is only during
786 // a safepoint which checks if handles point to this metadata field.
787 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
788 // Metadata in shared region isn't deleted.
789 if (!m->is_shared()) {
790 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
791 if (_deallocate_list == NULL) {
792 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
793 }
794 _deallocate_list->append_if_missing(m);
795 log_debug(class, loader, data)("deallocate added for %s", m->print_value_string());
796 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
797 }
798 }
799
800 // Deallocate free metadata on the free list. How useful the PermGen was!
801 void ClassLoaderData::free_deallocate_list() {
802 // Don't need lock, at safepoint
803 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
804 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
805 if (_deallocate_list == NULL) {
806 return;
807 }
808 // Go backwards because this removes entries that are freed.
809 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
810 Metadata* m = _deallocate_list->at(i);
811 if (!m->on_stack()) {
812 _deallocate_list->remove_at(i);
813 // There are only three types of metadata that we deallocate directly.
814 // Cast them so they can be used by the template function.
815 if (m->is_method()) {
816 MetadataFactory::free_metadata(this, (Method*)m);
817 } else if (m->is_constantPool()) {
818 MetadataFactory::free_metadata(this, (ConstantPool*)m);
819 } else if (m->is_klass()) {
820 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
821 } else {
822 ShouldNotReachHere();
823 }
824 } else {
825 // Metadata is alive.
826 // If scratch_class is on stack then it shouldn't be on this list!
827 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
828 "scratch classes on this list should be dead");
829 // Also should assert that other metadata on the list was found in handles.
830 // Some cleaning remains.
831 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
832 }
833 }
834 }
835
836 // This is distinct from free_deallocate_list. For class loader data that are
837 // unloading, this frees the C heap memory for items on the list, and unlinks
838 // scratch or error classes so that unloading events aren't triggered for these
839 // classes. The metadata is removed with the unloading metaspace.
840 // There isn't C heap memory allocated for methods, so nothing is done for them.
841 void ClassLoaderData::free_deallocate_list_C_heap_structures() {
842 // Don't need lock, at safepoint
843 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
844 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
845 if (_deallocate_list == NULL) {
846 return;
847 }
848 // Go backwards because this removes entries that are freed.
849 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
850 Metadata* m = _deallocate_list->at(i);
851 _deallocate_list->remove_at(i);
852 if (m->is_constantPool()) {
853 ((ConstantPool*)m)->release_C_heap_structures();
854 } else if (m->is_klass()) {
855 InstanceKlass* ik = (InstanceKlass*)m;
856 // also releases ik->constants() C heap memory
857 InstanceKlass::release_C_heap_structures(ik);
858 // Remove the class so unloading events aren't triggered for
859 // this class (scratch or error class) in do_unloading().
860 remove_class(ik);
861 }
862 }
863 }
864
865 // These CLDs are to contain unsafe anonymous classes used for JSR292
866 ClassLoaderData* ClassLoaderData::unsafe_anonymous_class_loader_data(Handle loader) {
867 // Add a new class loader data to the graph.
868 return ClassLoaderDataGraph::add(loader, true);
869 }
870
871 // Caller needs ResourceMark
872 // If the class loader's _name has not been explicitly set, the class loader's
873 // qualified class name is returned.
874 const char* ClassLoaderData::loader_name() const {
875 if (_class_loader_klass == NULL) {
876 return BOOTSTRAP_LOADER_NAME;
877 } else if (_name != NULL) {
878 return _name->as_C_string();
879 } else {
880 return _class_loader_klass->external_name();
881 }
882 }
883
884 // Caller needs ResourceMark
885 // Format of the _name_and_id is as follows:
886 // If the defining loader has a name explicitly set then '<loader-name>' @<id>
887 // If the defining loader has no name then <qualified-class-name> @<id>
888 // If built-in loader, then omit '@<id>' as there is only one instance.
889 const char* ClassLoaderData::loader_name_and_id() const {
890 if (_class_loader_klass == NULL) {
891 return "'" BOOTSTRAP_LOADER_NAME "'";
892 } else if (_name_and_id != NULL) {
893 return _name_and_id->as_C_string();
894 } else {
895 // May be called in a race before _name_and_id is initialized.
896 return _class_loader_klass->external_name();
897 }
898 }
899
900 void ClassLoaderData::print_value_on(outputStream* out) const {
901 if (!is_unloading() && class_loader() != NULL) {
902 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
903 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance
904 } else {
905 // loader data: 0xsomeaddr of 'bootstrap'
906 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
907 }
908 if (is_unsafe_anonymous()) {
909 out->print(" unsafe anonymous");
910 }
911 }
912
913 #ifndef PRODUCT
914 void ClassLoaderData::print_on(outputStream* out) const {
915 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
916 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id());
917 if (is_unsafe_anonymous()) out->print(" unsafe anonymous");
918 if (claimed()) out->print(" claimed");
919 if (is_unloading()) out->print(" unloading");
920 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
921
922 if (_jmethod_ids != NULL) {
923 Method::print_jmethod_ids(this, out);
924 }
925 out->print(" handles count %d", _handles.count());
926 out->print(" dependencies %d", _dependency_count);
927 out->print_cr("}");
928 }
929 #endif // PRODUCT
930
931 void ClassLoaderData::verify() {
932 assert_locked_or_safepoint(_metaspace_lock);
933 oop cl = class_loader();
934
935 guarantee(this == class_loader_data(cl) || is_unsafe_anonymous(), "Must be the same");
936 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_unsafe_anonymous(), "must be");
937
938 // Verify the integrity of the allocated space.
939 if (metaspace_or_null() != NULL) {
940 metaspace_or_null()->verify();
941 }
942
943 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
944 guarantee(k->class_loader_data() == this, "Must be the same");
945 k->verify();
946 assert(k != k->next_link(), "no loops!");
947 }
948 }
949
950 bool ClassLoaderData::contains_klass(Klass* klass) {
951 // Lock-free access requires load_acquire
952 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
953 if (k == klass) return true;
954 }
955 return false;
956 }