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 _claim(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::try_claim(int claim) {
272 for (;;) {
273 int old_claim = Atomic::load(&_claim);
274 if ((old_claim & claim) == claim) {
275 return false;
276 }
277 int new_claim = old_claim | claim;
278 if (Atomic::cmpxchg(new_claim, &_claim, old_claim) == old_claim) {
279 return true;
280 }
281 }
282 }
283
284 // Unsafe anonymous classes have their own ClassLoaderData that is marked to keep alive
285 // while the class is being parsed, and if the class appears on the module fixup list.
286 // Due to the uniqueness that no other class shares the unsafe anonymous class' name or
287 // ClassLoaderData, no other non-GC thread has knowledge of the unsafe anonymous class while
288 // it is being defined, therefore _keep_alive is not volatile or atomic.
289 void ClassLoaderData::inc_keep_alive() {
290 if (is_unsafe_anonymous()) {
291 assert(_keep_alive >= 0, "Invalid keep alive increment count");
292 _keep_alive++;
293 }
294 }
295
296 void ClassLoaderData::dec_keep_alive() {
297 if (is_unsafe_anonymous()) {
298 assert(_keep_alive > 0, "Invalid keep alive decrement count");
299 _keep_alive--;
300 }
301 }
302
303 void ClassLoaderData::oops_do(OopClosure* f, int claim_value, bool clear_mod_oops) {
304 if (claim_value != ClassLoaderData::_claim_none && !try_claim(claim_value)) {
305 return;
306 }
307
308 // Only clear modified_oops after the ClassLoaderData is claimed.
309 if (clear_mod_oops) {
310 clear_modified_oops();
311 }
312
313 _handles.oops_do(f);
314 }
315
316 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
317 // Lock-free access requires load_acquire
318 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
319 klass_closure->do_klass(k);
320 assert(k != k->next_link(), "no loops!");
321 }
322 }
323
324 void ClassLoaderData::classes_do(void f(Klass * const)) {
325 // Lock-free access requires load_acquire
326 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
327 f(k);
328 assert(k != k->next_link(), "no loops!");
329 }
330 }
331
332 void ClassLoaderData::methods_do(void f(Method*)) {
333 // Lock-free access requires load_acquire
334 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
335 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
336 InstanceKlass::cast(k)->methods_do(f);
337 }
338 }
339 }
340
341 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
342 // Lock-free access requires load_acquire
343 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
344 // Do not filter ArrayKlass oops here...
345 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
346 #ifdef ASSERT
347 oop m = k->java_mirror();
348 assert(m != NULL, "NULL mirror");
349 assert(m->is_a(SystemDictionary::Class_klass()), "invalid mirror");
350 #endif
351 klass_closure->do_klass(k);
352 }
353 }
354 }
355
356 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
357 // Lock-free access requires load_acquire
358 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
359 if (k->is_instance_klass()) {
360 f(InstanceKlass::cast(k));
361 }
362 assert(k != k->next_link(), "no loops!");
363 }
364 }
365
366 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
367 assert_locked_or_safepoint(Module_lock);
368 if (_unnamed_module != NULL) {
369 f(_unnamed_module);
370 }
371 if (_modules != NULL) {
372 for (int i = 0; i < _modules->table_size(); i++) {
373 for (ModuleEntry* entry = _modules->bucket(i);
374 entry != NULL;
375 entry = entry->next()) {
376 f(entry);
377 }
378 }
379 }
380 }
381
382 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
383 assert_locked_or_safepoint(Module_lock);
384 if (_packages != NULL) {
385 for (int i = 0; i < _packages->table_size(); i++) {
386 for (PackageEntry* entry = _packages->bucket(i);
387 entry != NULL;
388 entry = entry->next()) {
389 f(entry);
390 }
391 }
392 }
393 }
394
395 void ClassLoaderData::record_dependency(const Klass* k) {
396 assert(k != NULL, "invariant");
397
398 ClassLoaderData * const from_cld = this;
399 ClassLoaderData * const to_cld = k->class_loader_data();
400
401 // Do not need to record dependency if the dependency is to a class whose
402 // class loader data is never freed. (i.e. the dependency's class loader
403 // is one of the three builtin class loaders and the dependency is not
404 // unsafe anonymous.)
405 if (to_cld->is_permanent_class_loader_data()) {
406 return;
407 }
408
409 oop to;
410 if (to_cld->is_unsafe_anonymous()) {
411 // Just return if an unsafe anonymous class is attempting to record a dependency
412 // to itself. (Note that every unsafe anonymous class has its own unique class
413 // loader data.)
414 if (to_cld == from_cld) {
415 return;
416 }
417 // Unsafe anonymous class dependencies are through the mirror.
418 to = k->java_mirror();
419 } else {
420 to = to_cld->class_loader();
421 oop from = from_cld->class_loader();
422
423 // Just return if this dependency is to a class with the same or a parent
424 // class_loader.
425 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) {
426 return; // this class loader is in the parent list, no need to add it.
427 }
428 }
429
430 // It's a dependency we won't find through GC, add it.
431 if (!_handles.contains(to)) {
432 NOT_PRODUCT(Atomic::inc(&_dependency_count));
433 LogTarget(Trace, class, loader, data) lt;
434 if (lt.is_enabled()) {
435 ResourceMark rm;
436 LogStream ls(lt);
437 ls.print("adding dependency from ");
438 print_value_on(&ls);
439 ls.print(" to ");
440 to_cld->print_value_on(&ls);
441 ls.cr();
442 }
443 Handle dependency(Thread::current(), to);
444 add_handle(dependency);
445 // Added a potentially young gen oop to the ClassLoaderData
446 record_modified_oops();
447 }
448 }
449
450 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
451 {
452 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
453 Klass* old_value = _klasses;
454 k->set_next_link(old_value);
455 // Link the new item into the list, making sure the linked class is stable
456 // since the list can be walked without a lock
457 OrderAccess::release_store(&_klasses, k);
458 if (k->is_array_klass()) {
459 ClassLoaderDataGraph::inc_array_classes(1);
460 } else {
461 ClassLoaderDataGraph::inc_instance_classes(1);
462 }
463 }
464
465 if (publicize) {
466 LogTarget(Trace, class, loader, data) lt;
467 if (lt.is_enabled()) {
468 ResourceMark rm;
469 LogStream ls(lt);
470 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
471 print_value_on(&ls);
472 ls.cr();
473 }
474 }
475 }
476
477 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
478 if (loader_or_mirror() != NULL) {
479 assert(_holder.is_null(), "never replace holders");
480 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror);
481 }
482 }
483
484 // Remove a klass from the _klasses list for scratch_class during redefinition
485 // or parsed class in the case of an error.
486 void ClassLoaderData::remove_class(Klass* scratch_class) {
487 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
488
489 // Adjust global class iterator.
490 ClassLoaderDataGraph::adjust_saved_class(scratch_class);
491
492 Klass* prev = NULL;
493 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
494 if (k == scratch_class) {
495 if (prev == NULL) {
496 _klasses = k->next_link();
497 } else {
498 Klass* next = k->next_link();
499 prev->set_next_link(next);
500 }
501
502 if (k->is_array_klass()) {
503 ClassLoaderDataGraph::dec_array_classes(1);
504 } else {
505 ClassLoaderDataGraph::dec_instance_classes(1);
506 }
507
508 return;
509 }
510 prev = k;
511 assert(k != k->next_link(), "no loops!");
512 }
513 ShouldNotReachHere(); // should have found this class!!
514 }
515
516 void ClassLoaderData::unload() {
517 _unloading = true;
518
519 LogTarget(Trace, class, loader, data) lt;
520 if (lt.is_enabled()) {
521 ResourceMark rm;
522 LogStream ls(lt);
523 ls.print("unload");
524 print_value_on(&ls);
525 ls.cr();
526 }
527
528 // Some items on the _deallocate_list need to free their C heap structures
529 // if they are not already on the _klasses list.
530 free_deallocate_list_C_heap_structures();
531
532 // Clean up class dependencies and tell serviceability tools
533 // these classes are unloading. Must be called
534 // after erroneous classes are released.
535 classes_do(InstanceKlass::unload_class);
536
537 // Clean up global class iterator for compiler
538 ClassLoaderDataGraph::adjust_saved_class(this);
539 }
540
541 ModuleEntryTable* ClassLoaderData::modules() {
542 // Lazily create the module entry table at first request.
543 // Lock-free access requires load_acquire.
544 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
545 if (modules == NULL) {
546 MutexLocker m1(Module_lock);
547 // Check if _modules got allocated while we were waiting for this lock.
548 if ((modules = _modules) == NULL) {
549 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
550
551 {
552 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
553 // Ensure _modules is stable, since it is examined without a lock
554 OrderAccess::release_store(&_modules, modules);
555 }
556 }
557 }
558 return modules;
559 }
560
561 const int _boot_loader_dictionary_size = 1009;
562 const int _default_loader_dictionary_size = 107;
563
564 Dictionary* ClassLoaderData::create_dictionary() {
565 assert(!is_unsafe_anonymous(), "unsafe anonymous class loader data do not have a dictionary");
566 int size;
567 bool resizable = false;
568 if (_the_null_class_loader_data == NULL) {
569 size = _boot_loader_dictionary_size;
570 resizable = true;
571 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
572 size = 1; // there's only one class in relection class loader and no initiated classes
573 } else if (is_system_class_loader_data()) {
574 size = _boot_loader_dictionary_size;
575 resizable = true;
576 } else {
577 size = _default_loader_dictionary_size;
578 resizable = true;
579 }
580 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) {
581 resizable = false;
582 }
583 return new Dictionary(this, size, resizable);
584 }
585
586 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
587 oop ClassLoaderData::holder_phantom() const {
588 // A klass that was previously considered dead can be looked up in the
589 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
590 // or a reachable object making it alive again. The SATB part of G1 needs
591 // to get notified about this potential resurrection, otherwise the marking
592 // might not find the object.
593 if (!_holder.is_null()) { // NULL class_loader
594 return _holder.resolve();
595 } else {
596 return NULL;
597 }
598 }
599
600 // Let the GC read the holder without keeping it alive.
601 oop ClassLoaderData::holder_no_keepalive() const {
602 if (!_holder.is_null()) { // NULL class_loader
603 return _holder.peek();
604 } else {
605 return NULL;
606 }
607 }
608
609 // Unloading support
610 bool ClassLoaderData::is_alive() const {
611 bool alive = keep_alive() // null class loader and incomplete unsafe anonymous klasses.
612 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
613
614 return alive;
615 }
616
617 class ReleaseKlassClosure: public KlassClosure {
618 private:
619 size_t _instance_class_released;
620 size_t _array_class_released;
621 public:
622 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
623
624 size_t instance_class_released() const { return _instance_class_released; }
625 size_t array_class_released() const { return _array_class_released; }
626
627 void do_klass(Klass* k) {
628 if (k->is_array_klass()) {
629 _array_class_released ++;
630 } else {
631 assert(k->is_instance_klass(), "Must be");
632 _instance_class_released ++;
633 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
634 }
635 }
636 };
637
638 ClassLoaderData::~ClassLoaderData() {
639 // Release C heap structures for all the classes.
640 ReleaseKlassClosure cl;
641 classes_do(&cl);
642
643 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
644 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
645
646 // Release the WeakHandle
647 _holder.release();
648
649 // Release C heap allocated hashtable for all the packages.
650 if (_packages != NULL) {
651 // Destroy the table itself
652 delete _packages;
653 _packages = NULL;
654 }
655
656 // Release C heap allocated hashtable for all the modules.
657 if (_modules != NULL) {
658 // Destroy the table itself
659 delete _modules;
660 _modules = NULL;
661 }
662
663 // Release C heap allocated hashtable for the dictionary
664 if (_dictionary != NULL) {
665 // Destroy the table itself
666 delete _dictionary;
667 _dictionary = NULL;
668 }
669
670 if (_unnamed_module != NULL) {
671 _unnamed_module->delete_unnamed_module();
672 _unnamed_module = NULL;
673 }
674
675 // release the metaspace
676 ClassLoaderMetaspace *m = _metaspace;
677 if (m != NULL) {
678 _metaspace = NULL;
679 delete m;
680 }
681 // Clear all the JNI handles for methods
682 // These aren't deallocated and are going to look like a leak, but that's
683 // needed because we can't really get rid of jmethodIDs because we don't
684 // know when native code is going to stop using them. The spec says that
685 // they're "invalid" but existing programs likely rely on their being
686 // NULL after class unloading.
687 if (_jmethod_ids != NULL) {
688 Method::clear_jmethod_ids(this);
689 }
690 // Delete lock
691 delete _metaspace_lock;
692
693 // Delete free list
694 if (_deallocate_list != NULL) {
695 delete _deallocate_list;
696 }
697
698 // Decrement refcounts of Symbols if created.
699 if (_name != NULL) {
700 _name->decrement_refcount();
701 }
702 if (_name_and_id != NULL) {
703 _name_and_id->decrement_refcount();
704 }
705 }
706
707 // Returns true if this class loader data is for the app class loader
708 // or a user defined system class loader. (Note that the class loader
709 // data may be unsafe anonymous.)
710 bool ClassLoaderData::is_system_class_loader_data() const {
711 return SystemDictionary::is_system_class_loader(class_loader());
712 }
713
714 // Returns true if this class loader data is for the platform class loader.
715 // (Note that the class loader data may be unsafe anonymous.)
716 bool ClassLoaderData::is_platform_class_loader_data() const {
717 return SystemDictionary::is_platform_class_loader(class_loader());
718 }
719
720 // Returns true if the class loader for this class loader data is one of
721 // the 3 builtin (boot application/system or platform) class loaders,
722 // including a user-defined system class loader. Note that if the class
723 // loader data is for an unsafe anonymous class then it may get freed by a GC
724 // even if its class loader is one of these loaders.
725 bool ClassLoaderData::is_builtin_class_loader_data() const {
726 return (is_boot_class_loader_data() ||
727 SystemDictionary::is_system_class_loader(class_loader()) ||
728 SystemDictionary::is_platform_class_loader(class_loader()));
729 }
730
731 // Returns true if this class loader data is a class loader data
732 // that is not ever freed by a GC. It must be the CLD for one of the builtin
733 // class loaders and not the CLD for an unsafe anonymous class.
734 bool ClassLoaderData::is_permanent_class_loader_data() const {
735 return is_builtin_class_loader_data() && !is_unsafe_anonymous();
736 }
737
738 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
739 // If the metaspace has not been allocated, create a new one. Might want
740 // to create smaller arena for Reflection class loaders also.
741 // The reason for the delayed allocation is because some class loaders are
742 // simply for delegating with no metadata of their own.
743 // Lock-free access requires load_acquire.
744 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
745 if (metaspace == NULL) {
746 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
747 // Check if _metaspace got allocated while we were waiting for this lock.
748 if ((metaspace = _metaspace) == NULL) {
749 if (this == the_null_class_loader_data()) {
750 assert (class_loader() == NULL, "Must be");
751 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
752 } else if (is_unsafe_anonymous()) {
753 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::UnsafeAnonymousMetaspaceType);
754 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
755 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
756 } else {
757 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
758 }
759 // Ensure _metaspace is stable, since it is examined without a lock
760 OrderAccess::release_store(&_metaspace, metaspace);
761 }
762 }
763 return metaspace;
764 }
765
766 OopHandle ClassLoaderData::add_handle(Handle h) {
767 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
768 record_modified_oops();
769 return OopHandle(_handles.add(h()));
770 }
771
772 void ClassLoaderData::remove_handle(OopHandle h) {
773 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
774 oop* ptr = h.ptr_raw();
775 if (ptr != NULL) {
776 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
777 NativeAccess<>::oop_store(ptr, oop(NULL));
778 }
779 }
780
781 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
782 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
783 if (dest.resolve() != NULL) {
784 return;
785 } else {
786 dest = _handles.add(h());
787 }
788 }
789
790 // Add this metadata pointer to be freed when it's safe. This is only during
791 // a safepoint which checks if handles point to this metadata field.
792 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
793 // Metadata in shared region isn't deleted.
794 if (!m->is_shared()) {
795 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
796 if (_deallocate_list == NULL) {
797 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
798 }
799 _deallocate_list->append_if_missing(m);
800 log_debug(class, loader, data)("deallocate added for %s", m->print_value_string());
801 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
802 }
803 }
804
805 // Deallocate free metadata on the free list. How useful the PermGen was!
806 void ClassLoaderData::free_deallocate_list() {
807 // This must be called at a safepoint because it depends on metadata walking at
808 // safepoint cleanup time.
809 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
810 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
811 if (_deallocate_list == NULL) {
812 return;
813 }
814 // Go backwards because this removes entries that are freed.
815 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
816 Metadata* m = _deallocate_list->at(i);
817 if (!m->on_stack()) {
818 _deallocate_list->remove_at(i);
819 // There are only three types of metadata that we deallocate directly.
820 // Cast them so they can be used by the template function.
821 if (m->is_method()) {
822 MetadataFactory::free_metadata(this, (Method*)m);
823 } else if (m->is_constantPool()) {
824 MetadataFactory::free_metadata(this, (ConstantPool*)m);
825 } else if (m->is_klass()) {
826 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
827 } else {
828 ShouldNotReachHere();
829 }
830 } else {
831 // Metadata is alive.
832 // If scratch_class is on stack then it shouldn't be on this list!
833 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
834 "scratch classes on this list should be dead");
835 // Also should assert that other metadata on the list was found in handles.
836 // Some cleaning remains.
837 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
838 }
839 }
840 }
841
842 // This is distinct from free_deallocate_list. For class loader data that are
843 // unloading, this frees the C heap memory for items on the list, and unlinks
844 // scratch or error classes so that unloading events aren't triggered for these
845 // classes. The metadata is removed with the unloading metaspace.
846 // There isn't C heap memory allocated for methods, so nothing is done for them.
847 void ClassLoaderData::free_deallocate_list_C_heap_structures() {
848 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
849 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
850 if (_deallocate_list == NULL) {
851 return;
852 }
853 // Go backwards because this removes entries that are freed.
854 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
855 Metadata* m = _deallocate_list->at(i);
856 _deallocate_list->remove_at(i);
857 if (m->is_constantPool()) {
858 ((ConstantPool*)m)->release_C_heap_structures();
859 } else if (m->is_klass()) {
860 InstanceKlass* ik = (InstanceKlass*)m;
861 // also releases ik->constants() C heap memory
862 InstanceKlass::release_C_heap_structures(ik);
863 // Remove the class so unloading events aren't triggered for
864 // this class (scratch or error class) in do_unloading().
865 remove_class(ik);
866 }
867 }
868 }
869
870 // These CLDs are to contain unsafe anonymous classes used for JSR292
871 ClassLoaderData* ClassLoaderData::unsafe_anonymous_class_loader_data(Handle loader) {
872 // Add a new class loader data to the graph.
873 return ClassLoaderDataGraph::add(loader, true);
874 }
875
876 // Caller needs ResourceMark
877 // If the class loader's _name has not been explicitly set, the class loader's
878 // qualified class name is returned.
879 const char* ClassLoaderData::loader_name() const {
880 if (_class_loader_klass == NULL) {
881 return BOOTSTRAP_LOADER_NAME;
882 } else if (_name != NULL) {
883 return _name->as_C_string();
884 } else {
885 return _class_loader_klass->external_name();
886 }
887 }
888
889 // Caller needs ResourceMark
890 // Format of the _name_and_id is as follows:
891 // If the defining loader has a name explicitly set then '<loader-name>' @<id>
892 // If the defining loader has no name then <qualified-class-name> @<id>
893 // If built-in loader, then omit '@<id>' as there is only one instance.
894 const char* ClassLoaderData::loader_name_and_id() const {
895 if (_class_loader_klass == NULL) {
896 return "'" BOOTSTRAP_LOADER_NAME "'";
897 } else if (_name_and_id != NULL) {
898 return _name_and_id->as_C_string();
899 } else {
900 // May be called in a race before _name_and_id is initialized.
901 return _class_loader_klass->external_name();
902 }
903 }
904
905 void ClassLoaderData::print_value_on(outputStream* out) const {
906 if (!is_unloading() && class_loader() != NULL) {
907 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
908 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance
909 } else {
910 // loader data: 0xsomeaddr of 'bootstrap'
911 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
912 }
913 if (is_unsafe_anonymous()) {
914 out->print(" unsafe anonymous");
915 }
916 }
917
918 #ifndef PRODUCT
919 void ClassLoaderData::print_on(outputStream* out) const {
920 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
921 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id());
922 if (is_unsafe_anonymous()) out->print(" unsafe anonymous");
923 if (claimed()) out->print(" claimed");
924 if (is_unloading()) out->print(" unloading");
925 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
926
927 if (_jmethod_ids != NULL) {
928 Method::print_jmethod_ids(this, out);
929 }
930 out->print(" handles count %d", _handles.count());
931 out->print(" dependencies %d", _dependency_count);
932 out->print_cr("}");
933 }
934 #endif // PRODUCT
935
936 void ClassLoaderData::verify() {
937 assert_locked_or_safepoint(_metaspace_lock);
938 oop cl = class_loader();
939
940 guarantee(this == class_loader_data(cl) || is_unsafe_anonymous(), "Must be the same");
941 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_unsafe_anonymous(), "must be");
942
943 // Verify the integrity of the allocated space.
944 if (metaspace_or_null() != NULL) {
945 metaspace_or_null()->verify();
946 }
947
948 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
949 guarantee(k->class_loader_data() == this, "Must be the same");
950 k->verify();
951 assert(k != k->next_link(), "no loops!");
952 }
953 }
954
955 bool ClassLoaderData::contains_klass(Klass* klass) {
956 // Lock-free access requires load_acquire
957 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
958 if (k == klass) return true;
959 }
960 return false;
961 }