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/valueKlass.hpp"
67 #include "oops/weakHandle.inline.hpp"
68 #include "runtime/atomic.hpp"
69 #include "runtime/handles.inline.hpp"
70 #include "runtime/mutex.hpp"
71 #include "runtime/orderAccess.hpp"
72 #include "runtime/safepoint.hpp"
73 #include "utilities/growableArray.hpp"
74 #include "utilities/macros.hpp"
75 #include "utilities/ostream.hpp"
76
77 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
78
79 void ClassLoaderData::init_null_class_loader_data() {
80 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
81 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
82
83 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
84 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
85 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
86
87 LogTarget(Trace, class, loader, data) lt;
88 if (lt.is_enabled()) {
89 ResourceMark rm;
90 LogStream ls(lt);
91 ls.print("create ");
92 _the_null_class_loader_data->print_value_on(&ls);
93 ls.cr();
94 }
95 }
96
97 // Obtain and set the class loader's name within the ClassLoaderData so
98 // it will be available for error messages, logging, JFR, etc. The name
99 // and klass are available after the class_loader oop is no longer alive,
100 // during unloading.
101 void ClassLoaderData::initialize_name(Handle class_loader) {
102 Thread* THREAD = Thread::current();
103 ResourceMark rm(THREAD);
104
105 // Obtain the class loader's name. If the class loader's name was not
106 // explicitly set during construction, the CLD's _name field will be null.
107 oop cl_name = java_lang_ClassLoader::name(class_loader());
108 if (cl_name != NULL) {
109 const char* cl_instance_name = java_lang_String::as_utf8_string(cl_name);
110
111 if (cl_instance_name != NULL && cl_instance_name[0] != '\0') {
112 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore.
113 _name = SymbolTable::new_symbol(cl_instance_name, CATCH);
114 }
115 }
116
117 // Obtain the class loader's name and identity hash. If the class loader's
118 // name was not explicitly set during construction, the class loader's name and id
119 // will be set to the qualified class name of the class loader along with its
120 // identity hash.
121 // If for some reason the ClassLoader's constructor has not been run, instead of
122 // leaving the _name_and_id field null, fall back to the external qualified class
123 // name. Thus CLD's _name_and_id field should never have a null value.
124 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader());
125 const char* cl_instance_name_and_id =
126 (cl_name_and_id == NULL) ? _class_loader_klass->external_name() :
127 java_lang_String::as_utf8_string(cl_name_and_id);
128 assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id");
129 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore.
130 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id, CATCH);
131 }
132
133 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_unsafe_anonymous) :
134 _metaspace(NULL),
135 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
136 Monitor::_safepoint_check_never)),
137 _unloading(false), _is_unsafe_anonymous(is_unsafe_anonymous),
138 _modified_oops(true), _accumulated_modified_oops(false),
139 // An unsafe anonymous class loader data doesn't have anything to keep
140 // it from being unloaded during parsing of the unsafe anonymous class.
141 // The null-class-loader should always be kept alive.
142 _keep_alive((is_unsafe_anonymous || h_class_loader.is_null()) ? 1 : 0),
143 _claim(0),
144 _handles(),
145 _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL),
146 _jmethod_ids(NULL),
147 _deallocate_list(NULL),
148 _next(NULL),
149 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL) {
150
151 if (!h_class_loader.is_null()) {
152 _class_loader = _handles.add(h_class_loader());
153 _class_loader_klass = h_class_loader->klass();
154 initialize_name(h_class_loader);
155 }
156
157 if (!is_unsafe_anonymous) {
158 // The holder is initialized later for unsafe anonymous classes, and before calling anything
159 // that call class_loader().
160 initialize_holder(h_class_loader);
161
162 // A ClassLoaderData created solely for an unsafe anonymous class should never have a
163 // ModuleEntryTable or PackageEntryTable created for it. The defining package
164 // and module for an unsafe anonymous class will be found in its host class.
165 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
166 if (h_class_loader.is_null()) {
167 // Create unnamed module for boot loader
168 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
169 } else {
170 // Create unnamed module for all other loaders
171 _unnamed_module = ModuleEntry::create_unnamed_module(this);
172 }
173 _dictionary = create_dictionary();
174 }
175
176 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
177
178 JFR_ONLY(INIT_ID(this);)
179 }
180
181 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
182 Chunk* c = _head;
183 while (c != NULL) {
184 Chunk* next = c->_next;
185 delete c;
186 c = next;
187 }
188 }
189
190 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
191 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
192 Chunk* next = new Chunk(_head);
193 OrderAccess::release_store(&_head, next);
194 }
195 oop* handle = &_head->_data[_head->_size];
196 NativeAccess<IS_DEST_UNINITIALIZED>::oop_store(handle, o);
197 OrderAccess::release_store(&_head->_size, _head->_size + 1);
198 return handle;
199 }
200
201 int ClassLoaderData::ChunkedHandleList::count() const {
202 int count = 0;
203 Chunk* chunk = _head;
204 while (chunk != NULL) {
205 count += chunk->_size;
206 chunk = chunk->_next;
207 }
208 return count;
209 }
210
211 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
212 for (juint i = 0; i < size; i++) {
213 if (c->_data[i] != NULL) {
214 f->do_oop(&c->_data[i]);
215 }
216 }
217 }
218
219 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
220 Chunk* head = OrderAccess::load_acquire(&_head);
221 if (head != NULL) {
222 // Must be careful when reading size of head
223 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
224 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
225 oops_do_chunk(f, c, c->_size);
226 }
227 }
228 }
229
230 class VerifyContainsOopClosure : public OopClosure {
231 oop _target;
232 bool _found;
233
234 public:
235 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
236
237 void do_oop(oop* p) {
238 if (p != NULL && oopDesc::equals(NativeAccess<AS_NO_KEEPALIVE>::oop_load(p), _target)) {
239 _found = true;
240 }
241 }
242
243 void do_oop(narrowOop* p) {
244 // The ChunkedHandleList should not contain any narrowOop
245 ShouldNotReachHere();
246 }
247
248 bool found() const {
249 return _found;
250 }
251 };
252
253 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
254 VerifyContainsOopClosure cl(p);
255 oops_do(&cl);
256 return cl.found();
257 }
258
259 #ifndef PRODUCT
260 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
261 Chunk* chunk = _head;
262 while (chunk != NULL) {
263 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
264 return true;
265 }
266 chunk = chunk->_next;
267 }
268 return false;
269 }
270 #endif // PRODUCT
271
272 bool ClassLoaderData::try_claim(int claim) {
273 for (;;) {
274 int old_claim = Atomic::load(&_claim);
275 if ((old_claim & claim) == claim) {
276 return false;
277 }
278 int new_claim = old_claim | claim;
279 if (Atomic::cmpxchg(new_claim, &_claim, old_claim) == old_claim) {
280 return true;
281 }
282 }
283 }
284
285 // Unsafe anonymous classes have their own ClassLoaderData that is marked to keep alive
286 // while the class is being parsed, and if the class appears on the module fixup list.
287 // Due to the uniqueness that no other class shares the unsafe anonymous class' name or
288 // ClassLoaderData, no other non-GC thread has knowledge of the unsafe anonymous class while
289 // it is being defined, therefore _keep_alive is not volatile or atomic.
290 void ClassLoaderData::inc_keep_alive() {
291 if (is_unsafe_anonymous()) {
292 assert(_keep_alive >= 0, "Invalid keep alive increment count");
293 _keep_alive++;
294 }
295 }
296
297 void ClassLoaderData::dec_keep_alive() {
298 if (is_unsafe_anonymous()) {
299 assert(_keep_alive > 0, "Invalid keep alive decrement count");
300 _keep_alive--;
301 }
302 }
303
304 void ClassLoaderData::oops_do(OopClosure* f, int claim_value, bool clear_mod_oops) {
305 if (claim_value != ClassLoaderData::_claim_none && !try_claim(claim_value)) {
306 return;
307 }
308
309 // Only clear modified_oops after the ClassLoaderData is claimed.
310 if (clear_mod_oops) {
311 clear_modified_oops();
312 }
313
314 _handles.oops_do(f);
315 }
316
317 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
318 // Lock-free access requires load_acquire
319 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
320 klass_closure->do_klass(k);
321 assert(k != k->next_link(), "no loops!");
322 }
323 }
324
325 void ClassLoaderData::classes_do(void f(Klass * const)) {
326 // Lock-free access requires load_acquire
327 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
328 f(k);
329 assert(k != k->next_link(), "no loops!");
330 }
331 }
332
333 void ClassLoaderData::methods_do(void f(Method*)) {
334 // Lock-free access requires load_acquire
335 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
336 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
337 InstanceKlass::cast(k)->methods_do(f);
338 }
339 }
340 }
341
342 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
343 // Lock-free access requires load_acquire
344 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
345 // Do not filter ArrayKlass oops here...
346 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
347 #ifdef ASSERT
348 oop m = k->java_mirror();
349 assert(m != NULL, "NULL mirror");
350 assert(m->is_a(SystemDictionary::Class_klass()), "invalid mirror");
351 #endif
352 klass_closure->do_klass(k);
353 }
354 }
355 }
356
357 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
358 // Lock-free access requires load_acquire
359 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
360 if (k->is_instance_klass()) {
361 f(InstanceKlass::cast(k));
362 }
363 assert(k != k->next_link(), "no loops!");
364 }
365 }
366
367 void ClassLoaderData::value_classes_do(void f(ValueKlass*)) {
368 // Lock-free access requires load_acquire
369 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
370 if (k->is_value()) {
371 f(ValueKlass::cast(k));
372 }
373 assert(k != k->next_link(), "no loops!");
374 }
375 }
376
377 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
378 assert_locked_or_safepoint(Module_lock);
379 if (_unnamed_module != NULL) {
380 f(_unnamed_module);
381 }
382 if (_modules != NULL) {
383 for (int i = 0; i < _modules->table_size(); i++) {
384 for (ModuleEntry* entry = _modules->bucket(i);
385 entry != NULL;
386 entry = entry->next()) {
387 f(entry);
388 }
389 }
390 }
391 }
392
393 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
394 assert_locked_or_safepoint(Module_lock);
395 if (_packages != NULL) {
396 for (int i = 0; i < _packages->table_size(); i++) {
397 for (PackageEntry* entry = _packages->bucket(i);
398 entry != NULL;
399 entry = entry->next()) {
400 f(entry);
401 }
402 }
403 }
404 }
405
406 void ClassLoaderData::record_dependency(const Klass* k) {
407 assert(k != NULL, "invariant");
408
409 ClassLoaderData * const from_cld = this;
410 ClassLoaderData * const to_cld = k->class_loader_data();
411
412 // Do not need to record dependency if the dependency is to a class whose
413 // class loader data is never freed. (i.e. the dependency's class loader
414 // is one of the three builtin class loaders and the dependency is not
415 // unsafe anonymous.)
416 if (to_cld->is_permanent_class_loader_data()) {
417 return;
418 }
419
420 oop to;
421 if (to_cld->is_unsafe_anonymous()) {
422 // Just return if an unsafe anonymous class is attempting to record a dependency
423 // to itself. (Note that every unsafe anonymous class has its own unique class
424 // loader data.)
425 if (to_cld == from_cld) {
426 return;
427 }
428 // Unsafe anonymous class dependencies are through the mirror.
429 to = k->java_mirror();
430 } else {
431 to = to_cld->class_loader();
432 oop from = from_cld->class_loader();
433
434 // Just return if this dependency is to a class with the same or a parent
435 // class_loader.
436 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) {
437 return; // this class loader is in the parent list, no need to add it.
438 }
439 }
440
441 // It's a dependency we won't find through GC, add it.
442 if (!_handles.contains(to)) {
443 NOT_PRODUCT(Atomic::inc(&_dependency_count));
444 LogTarget(Trace, class, loader, data) lt;
445 if (lt.is_enabled()) {
446 ResourceMark rm;
447 LogStream ls(lt);
448 ls.print("adding dependency from ");
449 print_value_on(&ls);
450 ls.print(" to ");
451 to_cld->print_value_on(&ls);
452 ls.cr();
453 }
454 Handle dependency(Thread::current(), to);
455 add_handle(dependency);
456 // Added a potentially young gen oop to the ClassLoaderData
457 record_modified_oops();
458 }
459 }
460
461 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
462 {
463 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
464 Klass* old_value = _klasses;
465 k->set_next_link(old_value);
466 // Link the new item into the list, making sure the linked class is stable
467 // since the list can be walked without a lock
468 OrderAccess::release_store(&_klasses, k);
469 if (k->is_array_klass()) {
470 ClassLoaderDataGraph::inc_array_classes(1);
471 } else {
472 ClassLoaderDataGraph::inc_instance_classes(1);
473 }
474 }
475
476 if (publicize) {
477 LogTarget(Trace, class, loader, data) lt;
478 if (lt.is_enabled()) {
479 ResourceMark rm;
480 LogStream ls(lt);
481 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
482 print_value_on(&ls);
483 ls.cr();
484 }
485 }
486 }
487
488 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
489 if (loader_or_mirror() != NULL) {
490 assert(_holder.is_null(), "never replace holders");
491 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror);
492 }
493 }
494
495 // Remove a klass from the _klasses list for scratch_class during redefinition
496 // or parsed class in the case of an error.
497 void ClassLoaderData::remove_class(Klass* scratch_class) {
498 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
499
500 // Adjust global class iterator.
501 ClassLoaderDataGraph::adjust_saved_class(scratch_class);
502
503 Klass* prev = NULL;
504 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
505 if (k == scratch_class) {
506 if (prev == NULL) {
507 _klasses = k->next_link();
508 } else {
509 Klass* next = k->next_link();
510 prev->set_next_link(next);
511 }
512
513 if (k->is_array_klass()) {
514 ClassLoaderDataGraph::dec_array_classes(1);
515 } else {
516 ClassLoaderDataGraph::dec_instance_classes(1);
517 }
518
519 return;
520 }
521 prev = k;
522 assert(k != k->next_link(), "no loops!");
523 }
524 ShouldNotReachHere(); // should have found this class!!
525 }
526
527 void ClassLoaderData::unload() {
528 _unloading = true;
529
530 LogTarget(Trace, class, loader, data) lt;
531 if (lt.is_enabled()) {
532 ResourceMark rm;
533 LogStream ls(lt);
534 ls.print("unload");
535 print_value_on(&ls);
536 ls.cr();
537 }
538
539 // Some items on the _deallocate_list need to free their C heap structures
540 // if they are not already on the _klasses list.
541 free_deallocate_list_C_heap_structures();
542
543 value_classes_do(ValueKlass::cleanup);
544
545 // Clean up class dependencies and tell serviceability tools
546 // these classes are unloading. Must be called
547 // after erroneous classes are released.
548 classes_do(InstanceKlass::unload_class);
549
550 // Clean up global class iterator for compiler
551 ClassLoaderDataGraph::adjust_saved_class(this);
552 }
553
554 ModuleEntryTable* ClassLoaderData::modules() {
555 // Lazily create the module entry table at first request.
556 // Lock-free access requires load_acquire.
557 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
558 if (modules == NULL) {
559 MutexLocker m1(Module_lock);
560 // Check if _modules got allocated while we were waiting for this lock.
561 if ((modules = _modules) == NULL) {
562 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
563
564 {
565 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
566 // Ensure _modules is stable, since it is examined without a lock
567 OrderAccess::release_store(&_modules, modules);
568 }
569 }
570 }
571 return modules;
572 }
573
574 const int _boot_loader_dictionary_size = 1009;
575 const int _default_loader_dictionary_size = 107;
576
577 Dictionary* ClassLoaderData::create_dictionary() {
578 assert(!is_unsafe_anonymous(), "unsafe anonymous class loader data do not have a dictionary");
579 int size;
580 bool resizable = false;
581 if (_the_null_class_loader_data == NULL) {
582 size = _boot_loader_dictionary_size;
583 resizable = true;
584 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
585 size = 1; // there's only one class in relection class loader and no initiated classes
586 } else if (is_system_class_loader_data()) {
587 size = _boot_loader_dictionary_size;
588 resizable = true;
589 } else {
590 size = _default_loader_dictionary_size;
591 resizable = true;
592 }
593 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) {
594 resizable = false;
595 }
596 return new Dictionary(this, size, resizable);
597 }
598
599 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
600 oop ClassLoaderData::holder_phantom() const {
601 // A klass that was previously considered dead can be looked up in the
602 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
603 // or a reachable object making it alive again. The SATB part of G1 needs
604 // to get notified about this potential resurrection, otherwise the marking
605 // might not find the object.
606 if (!_holder.is_null()) { // NULL class_loader
607 return _holder.resolve();
608 } else {
609 return NULL;
610 }
611 }
612
613 // Let the GC read the holder without keeping it alive.
614 oop ClassLoaderData::holder_no_keepalive() const {
615 if (!_holder.is_null()) { // NULL class_loader
616 return _holder.peek();
617 } else {
618 return NULL;
619 }
620 }
621
622 // Unloading support
623 bool ClassLoaderData::is_alive() const {
624 bool alive = keep_alive() // null class loader and incomplete unsafe anonymous klasses.
625 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
626
627 return alive;
628 }
629
630 class ReleaseKlassClosure: public KlassClosure {
631 private:
632 size_t _instance_class_released;
633 size_t _array_class_released;
634 public:
635 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
636
637 size_t instance_class_released() const { return _instance_class_released; }
638 size_t array_class_released() const { return _array_class_released; }
639
640 void do_klass(Klass* k) {
641 if (k->is_array_klass()) {
642 _array_class_released ++;
643 } else {
644 assert(k->is_instance_klass(), "Must be");
645 _instance_class_released ++;
646 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
647 }
648 }
649 };
650
651 ClassLoaderData::~ClassLoaderData() {
652 // Release C heap structures for all the classes.
653 ReleaseKlassClosure cl;
654 classes_do(&cl);
655
656 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
657 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
658
659 // Release the WeakHandle
660 _holder.release();
661
662 // Release C heap allocated hashtable for all the packages.
663 if (_packages != NULL) {
664 // Destroy the table itself
665 delete _packages;
666 _packages = NULL;
667 }
668
669 // Release C heap allocated hashtable for all the modules.
670 if (_modules != NULL) {
671 // Destroy the table itself
672 delete _modules;
673 _modules = NULL;
674 }
675
676 // Release C heap allocated hashtable for the dictionary
677 if (_dictionary != NULL) {
678 // Destroy the table itself
679 delete _dictionary;
680 _dictionary = NULL;
681 }
682
683 if (_unnamed_module != NULL) {
684 _unnamed_module->delete_unnamed_module();
685 _unnamed_module = NULL;
686 }
687
688 // release the metaspace
689 ClassLoaderMetaspace *m = _metaspace;
690 if (m != NULL) {
691 _metaspace = NULL;
692 delete m;
693 }
694 // Clear all the JNI handles for methods
695 // These aren't deallocated and are going to look like a leak, but that's
696 // needed because we can't really get rid of jmethodIDs because we don't
697 // know when native code is going to stop using them. The spec says that
698 // they're "invalid" but existing programs likely rely on their being
699 // NULL after class unloading.
700 if (_jmethod_ids != NULL) {
701 Method::clear_jmethod_ids(this);
702 }
703 // Delete lock
704 delete _metaspace_lock;
705
706 // Delete free list
707 if (_deallocate_list != NULL) {
708 delete _deallocate_list;
709 }
710
711 // Decrement refcounts of Symbols if created.
712 if (_name != NULL) {
713 _name->decrement_refcount();
714 }
715 if (_name_and_id != NULL) {
716 _name_and_id->decrement_refcount();
717 }
718 }
719
720 // Returns true if this class loader data is for the app class loader
721 // or a user defined system class loader. (Note that the class loader
722 // data may be unsafe anonymous.)
723 bool ClassLoaderData::is_system_class_loader_data() const {
724 return SystemDictionary::is_system_class_loader(class_loader());
725 }
726
727 // Returns true if this class loader data is for the platform class loader.
728 // (Note that the class loader data may be unsafe anonymous.)
729 bool ClassLoaderData::is_platform_class_loader_data() const {
730 return SystemDictionary::is_platform_class_loader(class_loader());
731 }
732
733 // Returns true if the class loader for this class loader data is one of
734 // the 3 builtin (boot application/system or platform) class loaders,
735 // including a user-defined system class loader. Note that if the class
736 // loader data is for an unsafe anonymous class then it may get freed by a GC
737 // even if its class loader is one of these loaders.
738 bool ClassLoaderData::is_builtin_class_loader_data() const {
739 return (is_boot_class_loader_data() ||
740 SystemDictionary::is_system_class_loader(class_loader()) ||
741 SystemDictionary::is_platform_class_loader(class_loader()));
742 }
743
744 // Returns true if this class loader data is a class loader data
745 // that is not ever freed by a GC. It must be the CLD for one of the builtin
746 // class loaders and not the CLD for an unsafe anonymous class.
747 bool ClassLoaderData::is_permanent_class_loader_data() const {
748 return is_builtin_class_loader_data() && !is_unsafe_anonymous();
749 }
750
751 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
752 // If the metaspace has not been allocated, create a new one. Might want
753 // to create smaller arena for Reflection class loaders also.
754 // The reason for the delayed allocation is because some class loaders are
755 // simply for delegating with no metadata of their own.
756 // Lock-free access requires load_acquire.
757 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
758 if (metaspace == NULL) {
759 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
760 // Check if _metaspace got allocated while we were waiting for this lock.
761 if ((metaspace = _metaspace) == NULL) {
762 if (this == the_null_class_loader_data()) {
763 assert (class_loader() == NULL, "Must be");
764 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
765 } else if (is_unsafe_anonymous()) {
766 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::UnsafeAnonymousMetaspaceType);
767 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
768 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
769 } else {
770 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
771 }
772 // Ensure _metaspace is stable, since it is examined without a lock
773 OrderAccess::release_store(&_metaspace, metaspace);
774 }
775 }
776 return metaspace;
777 }
778
779 OopHandle ClassLoaderData::add_handle(Handle h) {
780 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
781 record_modified_oops();
782 return OopHandle(_handles.add(h()));
783 }
784
785 void ClassLoaderData::remove_handle(OopHandle h) {
786 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
787 oop* ptr = h.ptr_raw();
788 if (ptr != NULL) {
789 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
790 NativeAccess<>::oop_store(ptr, oop(NULL));
791 }
792 }
793
794 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
795 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
796 if (dest.resolve() != NULL) {
797 return;
798 } else {
799 dest = _handles.add(h());
800 }
801 }
802
803 // Add this metadata pointer to be freed when it's safe. This is only during
804 // a safepoint which checks if handles point to this metadata field.
805 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
806 // Metadata in shared region isn't deleted.
807 if (!m->is_shared()) {
808 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
809 if (_deallocate_list == NULL) {
810 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
811 }
812 _deallocate_list->append_if_missing(m);
813 log_debug(class, loader, data)("deallocate added for %s", m->print_value_string());
814 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
815 }
816 }
817
818 // Deallocate free metadata on the free list. How useful the PermGen was!
819 void ClassLoaderData::free_deallocate_list() {
820 // This must be called at a safepoint because it depends on metadata walking at
821 // safepoint cleanup time.
822 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
823 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
824 if (_deallocate_list == NULL) {
825 return;
826 }
827 // Go backwards because this removes entries that are freed.
828 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
829 Metadata* m = _deallocate_list->at(i);
830 if (!m->on_stack()) {
831 _deallocate_list->remove_at(i);
832 // There are only three types of metadata that we deallocate directly.
833 // Cast them so they can be used by the template function.
834 if (m->is_method()) {
835 MetadataFactory::free_metadata(this, (Method*)m);
836 } else if (m->is_constantPool()) {
837 MetadataFactory::free_metadata(this, (ConstantPool*)m);
838 } else if (m->is_klass()) {
839 if (!((Klass*)m)->is_value()) {
840 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
841 } else {
842 MetadataFactory::free_metadata(this, (ValueKlass*)m);
843 }
844 } else {
845 ShouldNotReachHere();
846 }
847 } else {
848 // Metadata is alive.
849 // If scratch_class is on stack then it shouldn't be on this list!
850 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
851 "scratch classes on this list should be dead");
852 // Also should assert that other metadata on the list was found in handles.
853 // Some cleaning remains.
854 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
855 }
856 }
857 }
858
859 // This is distinct from free_deallocate_list. For class loader data that are
860 // unloading, this frees the C heap memory for items on the list, and unlinks
861 // scratch or error classes so that unloading events aren't triggered for these
862 // classes. The metadata is removed with the unloading metaspace.
863 // There isn't C heap memory allocated for methods, so nothing is done for them.
864 void ClassLoaderData::free_deallocate_list_C_heap_structures() {
865 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
866 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
867 if (_deallocate_list == NULL) {
868 return;
869 }
870 // Go backwards because this removes entries that are freed.
871 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
872 Metadata* m = _deallocate_list->at(i);
873 _deallocate_list->remove_at(i);
874 if (m->is_constantPool()) {
875 ((ConstantPool*)m)->release_C_heap_structures();
876 } else if (m->is_klass()) {
877 InstanceKlass* ik = (InstanceKlass*)m;
878 // also releases ik->constants() C heap memory
879 InstanceKlass::release_C_heap_structures(ik);
880 // Remove the class so unloading events aren't triggered for
881 // this class (scratch or error class) in do_unloading().
882 remove_class(ik);
883 }
884 }
885 }
886
887 // These CLDs are to contain unsafe anonymous classes used for JSR292
888 ClassLoaderData* ClassLoaderData::unsafe_anonymous_class_loader_data(Handle loader) {
889 // Add a new class loader data to the graph.
890 return ClassLoaderDataGraph::add(loader, true);
891 }
892
893 // Caller needs ResourceMark
894 // If the class loader's _name has not been explicitly set, the class loader's
895 // qualified class name is returned.
896 const char* ClassLoaderData::loader_name() const {
897 if (_class_loader_klass == NULL) {
898 return BOOTSTRAP_LOADER_NAME;
899 } else if (_name != NULL) {
900 return _name->as_C_string();
901 } else {
902 return _class_loader_klass->external_name();
903 }
904 }
905
906 // Caller needs ResourceMark
907 // Format of the _name_and_id is as follows:
908 // If the defining loader has a name explicitly set then '<loader-name>' @<id>
909 // If the defining loader has no name then <qualified-class-name> @<id>
910 // If built-in loader, then omit '@<id>' as there is only one instance.
911 const char* ClassLoaderData::loader_name_and_id() const {
912 if (_class_loader_klass == NULL) {
913 return "'" BOOTSTRAP_LOADER_NAME "'";
914 } else if (_name_and_id != NULL) {
915 return _name_and_id->as_C_string();
916 } else {
917 // May be called in a race before _name_and_id is initialized.
918 return _class_loader_klass->external_name();
919 }
920 }
921
922 void ClassLoaderData::print_value_on(outputStream* out) const {
923 if (!is_unloading() && class_loader() != NULL) {
924 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
925 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance
926 } else {
927 // loader data: 0xsomeaddr of 'bootstrap'
928 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
929 }
930 if (is_unsafe_anonymous()) {
931 out->print(" unsafe anonymous");
932 }
933 }
934
935 #ifndef PRODUCT
936 void ClassLoaderData::print_on(outputStream* out) const {
937 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
938 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id());
939 if (is_unsafe_anonymous()) out->print(" unsafe anonymous");
940 if (claimed()) out->print(" claimed");
941 if (is_unloading()) out->print(" unloading");
942 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
943
944 if (_jmethod_ids != NULL) {
945 Method::print_jmethod_ids(this, out);
946 }
947 out->print(" handles count %d", _handles.count());
948 out->print(" dependencies %d", _dependency_count);
949 out->print_cr("}");
950 }
951 #endif // PRODUCT
952
953 void ClassLoaderData::verify() {
954 assert_locked_or_safepoint(_metaspace_lock);
955 oop cl = class_loader();
956
957 guarantee(this == class_loader_data(cl) || is_unsafe_anonymous(), "Must be the same");
958 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_unsafe_anonymous(), "must be");
959
960 // Verify the integrity of the allocated space.
961 if (metaspace_or_null() != NULL) {
962 metaspace_or_null()->verify();
963 }
964
965 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
966 guarantee(k->class_loader_data() == this, "Must be the same");
967 k->verify();
968 assert(k != k->next_link(), "no loops!");
969 }
970 }
971
972 bool ClassLoaderData::contains_klass(Klass* klass) {
973 // Lock-free access requires load_acquire
974 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
975 if (k == klass) return true;
976 }
977 return false;
978 }