1 /*
2 * Copyright (c) 2012, 2019, 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 _name = SymbolTable::new_symbol(cl_instance_name);
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 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id);
129 }
130
131 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_unsafe_anonymous) :
132 _metaspace(NULL),
133 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
134 Monitor::_safepoint_check_never)),
135 _unloading(false), _is_unsafe_anonymous(is_unsafe_anonymous),
136 _modified_oops(true), _accumulated_modified_oops(false),
137 // An unsafe anonymous class loader data doesn't have anything to keep
138 // it from being unloaded during parsing of the unsafe anonymous class.
139 // The null-class-loader should always be kept alive.
140 _keep_alive((is_unsafe_anonymous || h_class_loader.is_null()) ? 1 : 0),
141 _claim(0),
142 _handles(),
143 _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL),
144 _jmethod_ids(NULL),
145 _deallocate_list(NULL),
146 _next(NULL),
147 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL) {
148
149 if (!h_class_loader.is_null()) {
150 _class_loader = _handles.add(h_class_loader());
151 _class_loader_klass = h_class_loader->klass();
152 initialize_name(h_class_loader);
153 }
154
155 if (!is_unsafe_anonymous) {
156 // The holder is initialized later for unsafe anonymous classes, and before calling anything
157 // that call class_loader().
158 initialize_holder(h_class_loader);
159
160 // A ClassLoaderData created solely for an unsafe anonymous class should never have a
161 // ModuleEntryTable or PackageEntryTable created for it. The defining package
162 // and module for an unsafe anonymous class will be found in its host class.
163 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
164 if (h_class_loader.is_null()) {
165 // Create unnamed module for boot loader
166 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
167 } else {
168 // Create unnamed module for all other loaders
169 _unnamed_module = ModuleEntry::create_unnamed_module(this);
170 }
171 _dictionary = create_dictionary();
172 }
173
174 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
175
176 JFR_ONLY(INIT_ID(this);)
177 }
178
179 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
180 Chunk* c = _head;
181 while (c != NULL) {
182 Chunk* next = c->_next;
183 delete c;
184 c = next;
185 }
186 }
187
188 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
189 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
190 Chunk* next = new Chunk(_head);
191 OrderAccess::release_store(&_head, next);
192 }
193 oop* handle = &_head->_data[_head->_size];
194 NativeAccess<IS_DEST_UNINITIALIZED>::oop_store(handle, o);
195 OrderAccess::release_store(&_head->_size, _head->_size + 1);
196 return handle;
197 }
198
199 int ClassLoaderData::ChunkedHandleList::count() const {
200 int count = 0;
201 Chunk* chunk = _head;
202 while (chunk != NULL) {
203 count += chunk->_size;
204 chunk = chunk->_next;
205 }
206 return count;
207 }
208
209 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
210 for (juint i = 0; i < size; i++) {
211 if (c->_data[i] != NULL) {
212 f->do_oop(&c->_data[i]);
213 }
214 }
215 }
216
217 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
218 Chunk* head = OrderAccess::load_acquire(&_head);
219 if (head != NULL) {
220 // Must be careful when reading size of head
221 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
222 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
223 oops_do_chunk(f, c, c->_size);
224 }
225 }
226 }
227
228 class VerifyContainsOopClosure : public OopClosure {
229 oop _target;
230 bool _found;
231
232 public:
233 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
234
235 void do_oop(oop* p) {
236 if (p != NULL && NativeAccess<AS_NO_KEEPALIVE>::oop_load(p) == _target) {
237 _found = true;
238 }
239 }
240
241 void do_oop(narrowOop* p) {
242 // The ChunkedHandleList should not contain any narrowOop
243 ShouldNotReachHere();
244 }
245
246 bool found() const {
247 return _found;
248 }
249 };
250
251 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
252 VerifyContainsOopClosure cl(p);
253 oops_do(&cl);
254 return cl.found();
255 }
256
257 #ifndef PRODUCT
258 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
259 Chunk* chunk = _head;
260 while (chunk != NULL) {
261 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
262 return true;
263 }
264 chunk = chunk->_next;
265 }
266 return false;
267 }
268 #endif // PRODUCT
269
270 void ClassLoaderData::clear_claim(int claim) {
271 for (;;) {
272 int old_claim = Atomic::load(&_claim);
273 if ((old_claim & claim) == 0) {
274 return;
275 }
276 int new_claim = old_claim & ~claim;
277 if (Atomic::cmpxchg(new_claim, &_claim, old_claim) == old_claim) {
278 return;
279 }
280 }
281 }
282
283 bool ClassLoaderData::try_claim(int claim) {
284 for (;;) {
285 int old_claim = Atomic::load(&_claim);
286 if ((old_claim & claim) == claim) {
287 return false;
288 }
289 int new_claim = old_claim | claim;
290 if (Atomic::cmpxchg(new_claim, &_claim, old_claim) == old_claim) {
291 return true;
292 }
293 }
294 }
295
296 // Unsafe anonymous classes have their own ClassLoaderData that is marked to keep alive
297 // while the class is being parsed, and if the class appears on the module fixup list.
298 // Due to the uniqueness that no other class shares the unsafe anonymous class' name or
299 // ClassLoaderData, no other non-GC thread has knowledge of the unsafe anonymous class while
300 // it is being defined, therefore _keep_alive is not volatile or atomic.
301 void ClassLoaderData::inc_keep_alive() {
302 if (is_unsafe_anonymous()) {
303 assert(_keep_alive > 0, "Invalid keep alive increment count");
304 _keep_alive++;
305 }
306 }
307
308 void ClassLoaderData::dec_keep_alive() {
309 if (is_unsafe_anonymous()) {
310 assert(_keep_alive > 0, "Invalid keep alive decrement count");
311 _keep_alive--;
312 }
313 }
314
315 void ClassLoaderData::oops_do(OopClosure* f, int claim_value, bool clear_mod_oops) {
316 if (claim_value != ClassLoaderData::_claim_none && !try_claim(claim_value)) {
317 return;
318 }
319
320 // Only clear modified_oops after the ClassLoaderData is claimed.
321 if (clear_mod_oops) {
322 clear_modified_oops();
323 }
324
325 _handles.oops_do(f);
326 }
327
328 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
329 // Lock-free access requires load_acquire
330 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
331 klass_closure->do_klass(k);
332 assert(k != k->next_link(), "no loops!");
333 }
334 }
335
336 void ClassLoaderData::classes_do(void f(Klass * const)) {
337 // Lock-free access requires load_acquire
338 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
339 f(k);
340 assert(k != k->next_link(), "no loops!");
341 }
342 }
343
344 void ClassLoaderData::methods_do(void f(Method*)) {
345 // Lock-free access requires load_acquire
346 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
347 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
348 InstanceKlass::cast(k)->methods_do(f);
349 }
350 }
351 }
352
353 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
354 // Lock-free access requires load_acquire
355 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
356 // Do not filter ArrayKlass oops here...
357 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
358 #ifdef ASSERT
359 oop m = k->java_mirror();
360 assert(m != NULL, "NULL mirror");
361 assert(m->is_a(SystemDictionary::Class_klass()), "invalid mirror");
362 #endif
363 klass_closure->do_klass(k);
364 }
365 }
366 }
367
368 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
369 // Lock-free access requires load_acquire
370 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
371 if (k->is_instance_klass()) {
372 f(InstanceKlass::cast(k));
373 }
374 assert(k != k->next_link(), "no loops!");
375 }
376 }
377
378 void ClassLoaderData::value_classes_do(void f(ValueKlass*)) {
379 // Lock-free access requires load_acquire
380 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
381 if (k->is_value()) {
382 f(ValueKlass::cast(k));
383 }
384 assert(k != k->next_link(), "no loops!");
385 }
386 }
387
388 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
389 assert_locked_or_safepoint(Module_lock);
390 if (_unnamed_module != NULL) {
391 f(_unnamed_module);
392 }
393 if (_modules != NULL) {
394 for (int i = 0; i < _modules->table_size(); i++) {
395 for (ModuleEntry* entry = _modules->bucket(i);
396 entry != NULL;
397 entry = entry->next()) {
398 f(entry);
399 }
400 }
401 }
402 }
403
404 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
405 assert_locked_or_safepoint(Module_lock);
406 if (_packages != NULL) {
407 for (int i = 0; i < _packages->table_size(); i++) {
408 for (PackageEntry* entry = _packages->bucket(i);
409 entry != NULL;
410 entry = entry->next()) {
411 f(entry);
412 }
413 }
414 }
415 }
416
417 void ClassLoaderData::record_dependency(const Klass* k) {
418 assert(k != NULL, "invariant");
419
420 ClassLoaderData * const from_cld = this;
421 ClassLoaderData * const to_cld = k->class_loader_data();
422
423 // Do not need to record dependency if the dependency is to a class whose
424 // class loader data is never freed. (i.e. the dependency's class loader
425 // is one of the three builtin class loaders and the dependency is not
426 // unsafe anonymous.)
427 if (to_cld->is_permanent_class_loader_data()) {
428 return;
429 }
430
431 oop to;
432 if (to_cld->is_unsafe_anonymous()) {
433 // Just return if an unsafe anonymous class is attempting to record a dependency
434 // to itself. (Note that every unsafe anonymous class has its own unique class
435 // loader data.)
436 if (to_cld == from_cld) {
437 return;
438 }
439 // Unsafe anonymous class dependencies are through the mirror.
440 to = k->java_mirror();
441 } else {
442 to = to_cld->class_loader();
443 oop from = from_cld->class_loader();
444
445 // Just return if this dependency is to a class with the same or a parent
446 // class_loader.
447 if (from == to || java_lang_ClassLoader::isAncestor(from, to)) {
448 return; // this class loader is in the parent list, no need to add it.
449 }
450 }
451
452 // It's a dependency we won't find through GC, add it.
453 if (!_handles.contains(to)) {
454 NOT_PRODUCT(Atomic::inc(&_dependency_count));
455 LogTarget(Trace, class, loader, data) lt;
456 if (lt.is_enabled()) {
457 ResourceMark rm;
458 LogStream ls(lt);
459 ls.print("adding dependency from ");
460 print_value_on(&ls);
461 ls.print(" to ");
462 to_cld->print_value_on(&ls);
463 ls.cr();
464 }
465 Handle dependency(Thread::current(), to);
466 add_handle(dependency);
467 // Added a potentially young gen oop to the ClassLoaderData
468 record_modified_oops();
469 }
470 }
471
472 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
473 {
474 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
475 Klass* old_value = _klasses;
476 k->set_next_link(old_value);
477 // Link the new item into the list, making sure the linked class is stable
478 // since the list can be walked without a lock
479 OrderAccess::release_store(&_klasses, k);
480 if (k->is_array_klass()) {
481 ClassLoaderDataGraph::inc_array_classes(1);
482 } else {
483 ClassLoaderDataGraph::inc_instance_classes(1);
484 }
485 }
486
487 if (publicize) {
488 LogTarget(Trace, class, loader, data) lt;
489 if (lt.is_enabled()) {
490 ResourceMark rm;
491 LogStream ls(lt);
492 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
493 print_value_on(&ls);
494 ls.cr();
495 }
496 }
497 }
498
499 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
500 if (loader_or_mirror() != NULL) {
501 assert(_holder.is_null(), "never replace holders");
502 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror);
503 }
504 }
505
506 // Remove a klass from the _klasses list for scratch_class during redefinition
507 // or parsed class in the case of an error.
508 void ClassLoaderData::remove_class(Klass* scratch_class) {
509 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
510
511 // Adjust global class iterator.
512 ClassLoaderDataGraph::adjust_saved_class(scratch_class);
513
514 Klass* prev = NULL;
515 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
516 if (k == scratch_class) {
517 if (prev == NULL) {
518 _klasses = k->next_link();
519 } else {
520 Klass* next = k->next_link();
521 prev->set_next_link(next);
522 }
523
524 if (k->is_array_klass()) {
525 ClassLoaderDataGraph::dec_array_classes(1);
526 } else {
527 ClassLoaderDataGraph::dec_instance_classes(1);
528 }
529
530 return;
531 }
532 prev = k;
533 assert(k != k->next_link(), "no loops!");
534 }
535 ShouldNotReachHere(); // should have found this class!!
536 }
537
538 void ClassLoaderData::unload() {
539 _unloading = true;
540
541 LogTarget(Trace, class, loader, data) lt;
542 if (lt.is_enabled()) {
543 ResourceMark rm;
544 LogStream ls(lt);
545 ls.print("unload");
546 print_value_on(&ls);
547 ls.cr();
548 }
549
550 // Some items on the _deallocate_list need to free their C heap structures
551 // if they are not already on the _klasses list.
552 free_deallocate_list_C_heap_structures();
553
554 value_classes_do(ValueKlass::cleanup);
555
556 // Clean up class dependencies and tell serviceability tools
557 // these classes are unloading. Must be called
558 // after erroneous classes are released.
559 classes_do(InstanceKlass::unload_class);
560
561 // Clean up global class iterator for compiler
562 ClassLoaderDataGraph::adjust_saved_class(this);
563 }
564
565 ModuleEntryTable* ClassLoaderData::modules() {
566 // Lazily create the module entry table at first request.
567 // Lock-free access requires load_acquire.
568 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
569 if (modules == NULL) {
570 MutexLocker m1(Module_lock);
571 // Check if _modules got allocated while we were waiting for this lock.
572 if ((modules = _modules) == NULL) {
573 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
574
575 {
576 MutexLocker m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
577 // Ensure _modules is stable, since it is examined without a lock
578 OrderAccess::release_store(&_modules, modules);
579 }
580 }
581 }
582 return modules;
583 }
584
585 const int _boot_loader_dictionary_size = 1009;
586 const int _default_loader_dictionary_size = 107;
587
588 Dictionary* ClassLoaderData::create_dictionary() {
589 assert(!is_unsafe_anonymous(), "unsafe anonymous class loader data do not have a dictionary");
590 int size;
591 bool resizable = false;
592 if (_the_null_class_loader_data == NULL) {
593 size = _boot_loader_dictionary_size;
594 resizable = true;
595 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
596 size = 1; // there's only one class in relection class loader and no initiated classes
597 } else if (is_system_class_loader_data()) {
598 size = _boot_loader_dictionary_size;
599 resizable = true;
600 } else {
601 size = _default_loader_dictionary_size;
602 resizable = true;
603 }
604 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) {
605 resizable = false;
606 }
607 return new Dictionary(this, size, resizable);
608 }
609
610 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
611 oop ClassLoaderData::holder_phantom() const {
612 // A klass that was previously considered dead can be looked up in the
613 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
614 // or a reachable object making it alive again. The SATB part of G1 needs
615 // to get notified about this potential resurrection, otherwise the marking
616 // might not find the object.
617 if (!_holder.is_null()) { // NULL class_loader
618 return _holder.resolve();
619 } else {
620 return NULL;
621 }
622 }
623
624 // Let the GC read the holder without keeping it alive.
625 oop ClassLoaderData::holder_no_keepalive() const {
626 if (!_holder.is_null()) { // NULL class_loader
627 return _holder.peek();
628 } else {
629 return NULL;
630 }
631 }
632
633 // Unloading support
634 bool ClassLoaderData::is_alive() const {
635 bool alive = keep_alive() // null class loader and incomplete unsafe anonymous klasses.
636 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
637
638 return alive;
639 }
640
641 class ReleaseKlassClosure: public KlassClosure {
642 private:
643 size_t _instance_class_released;
644 size_t _array_class_released;
645 public:
646 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
647
648 size_t instance_class_released() const { return _instance_class_released; }
649 size_t array_class_released() const { return _array_class_released; }
650
651 void do_klass(Klass* k) {
652 if (k->is_array_klass()) {
653 _array_class_released ++;
654 } else {
655 assert(k->is_instance_klass(), "Must be");
656 _instance_class_released ++;
657 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
658 }
659 }
660 };
661
662 ClassLoaderData::~ClassLoaderData() {
663 // Release C heap structures for all the classes.
664 ReleaseKlassClosure cl;
665 classes_do(&cl);
666
667 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
668 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
669
670 // Release the WeakHandle
671 _holder.release();
672
673 // Release C heap allocated hashtable for all the packages.
674 if (_packages != NULL) {
675 // Destroy the table itself
676 delete _packages;
677 _packages = NULL;
678 }
679
680 // Release C heap allocated hashtable for all the modules.
681 if (_modules != NULL) {
682 // Destroy the table itself
683 delete _modules;
684 _modules = NULL;
685 }
686
687 // Release C heap allocated hashtable for the dictionary
688 if (_dictionary != NULL) {
689 // Destroy the table itself
690 delete _dictionary;
691 _dictionary = NULL;
692 }
693
694 if (_unnamed_module != NULL) {
695 _unnamed_module->delete_unnamed_module();
696 _unnamed_module = NULL;
697 }
698
699 // release the metaspace
700 ClassLoaderMetaspace *m = _metaspace;
701 if (m != NULL) {
702 _metaspace = NULL;
703 delete m;
704 }
705 // Clear all the JNI handles for methods
706 // These aren't deallocated and are going to look like a leak, but that's
707 // needed because we can't really get rid of jmethodIDs because we don't
708 // know when native code is going to stop using them. The spec says that
709 // they're "invalid" but existing programs likely rely on their being
710 // NULL after class unloading.
711 if (_jmethod_ids != NULL) {
712 Method::clear_jmethod_ids(this);
713 }
714 // Delete lock
715 delete _metaspace_lock;
716
717 // Delete free list
718 if (_deallocate_list != NULL) {
719 delete _deallocate_list;
720 }
721
722 // Decrement refcounts of Symbols if created.
723 if (_name != NULL) {
724 _name->decrement_refcount();
725 }
726 if (_name_and_id != NULL) {
727 _name_and_id->decrement_refcount();
728 }
729 }
730
731 // Returns true if this class loader data is for the app class loader
732 // or a user defined system class loader. (Note that the class loader
733 // data may be unsafe anonymous.)
734 bool ClassLoaderData::is_system_class_loader_data() const {
735 return SystemDictionary::is_system_class_loader(class_loader());
736 }
737
738 // Returns true if this class loader data is for the platform class loader.
739 // (Note that the class loader data may be unsafe anonymous.)
740 bool ClassLoaderData::is_platform_class_loader_data() const {
741 return SystemDictionary::is_platform_class_loader(class_loader());
742 }
743
744 // Returns true if the class loader for this class loader data is one of
745 // the 3 builtin (boot application/system or platform) class loaders,
746 // including a user-defined system class loader. Note that if the class
747 // loader data is for an unsafe anonymous class then it may get freed by a GC
748 // even if its class loader is one of these loaders.
749 bool ClassLoaderData::is_builtin_class_loader_data() const {
750 return (is_boot_class_loader_data() ||
751 SystemDictionary::is_system_class_loader(class_loader()) ||
752 SystemDictionary::is_platform_class_loader(class_loader()));
753 }
754
755 // Returns true if this class loader data is a class loader data
756 // that is not ever freed by a GC. It must be the CLD for one of the builtin
757 // class loaders and not the CLD for an unsafe anonymous class.
758 bool ClassLoaderData::is_permanent_class_loader_data() const {
759 return is_builtin_class_loader_data() && !is_unsafe_anonymous();
760 }
761
762 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
763 // If the metaspace has not been allocated, create a new one. Might want
764 // to create smaller arena for Reflection class loaders also.
765 // The reason for the delayed allocation is because some class loaders are
766 // simply for delegating with no metadata of their own.
767 // Lock-free access requires load_acquire.
768 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
769 if (metaspace == NULL) {
770 MutexLocker ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
771 // Check if _metaspace got allocated while we were waiting for this lock.
772 if ((metaspace = _metaspace) == NULL) {
773 if (this == the_null_class_loader_data()) {
774 assert (class_loader() == NULL, "Must be");
775 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
776 } else if (is_unsafe_anonymous()) {
777 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::UnsafeAnonymousMetaspaceType);
778 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
779 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
780 } else {
781 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
782 }
783 // Ensure _metaspace is stable, since it is examined without a lock
784 OrderAccess::release_store(&_metaspace, metaspace);
785 }
786 }
787 return metaspace;
788 }
789
790 OopHandle ClassLoaderData::add_handle(Handle h) {
791 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
792 record_modified_oops();
793 return OopHandle(_handles.add(h()));
794 }
795
796 void ClassLoaderData::remove_handle(OopHandle h) {
797 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
798 oop* ptr = h.ptr_raw();
799 if (ptr != NULL) {
800 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
801 NativeAccess<>::oop_store(ptr, oop(NULL));
802 }
803 }
804
805 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
806 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
807 if (dest.resolve() != NULL) {
808 return;
809 } else {
810 dest = _handles.add(h());
811 }
812 }
813
814 // Add this metadata pointer to be freed when it's safe. This is only during
815 // a safepoint which checks if handles point to this metadata field.
816 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
817 // Metadata in shared region isn't deleted.
818 if (!m->is_shared()) {
819 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
820 if (_deallocate_list == NULL) {
821 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
822 }
823 _deallocate_list->append_if_missing(m);
824 log_debug(class, loader, data)("deallocate added for %s", m->print_value_string());
825 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
826 }
827 }
828
829 // Deallocate free metadata on the free list. How useful the PermGen was!
830 void ClassLoaderData::free_deallocate_list() {
831 // This must be called at a safepoint because it depends on metadata walking at
832 // safepoint cleanup time.
833 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
834 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
835 if (_deallocate_list == NULL) {
836 return;
837 }
838 // Go backwards because this removes entries that are freed.
839 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
840 Metadata* m = _deallocate_list->at(i);
841 if (!m->on_stack()) {
842 _deallocate_list->remove_at(i);
843 // There are only three types of metadata that we deallocate directly.
844 // Cast them so they can be used by the template function.
845 if (m->is_method()) {
846 MetadataFactory::free_metadata(this, (Method*)m);
847 } else if (m->is_constantPool()) {
848 MetadataFactory::free_metadata(this, (ConstantPool*)m);
849 } else if (m->is_klass()) {
850 if (!((Klass*)m)->is_value()) {
851 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
852 } else {
853 MetadataFactory::free_metadata(this, (ValueKlass*)m);
854 }
855 } else {
856 ShouldNotReachHere();
857 }
858 } else {
859 // Metadata is alive.
860 // If scratch_class is on stack then it shouldn't be on this list!
861 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
862 "scratch classes on this list should be dead");
863 // Also should assert that other metadata on the list was found in handles.
864 // Some cleaning remains.
865 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
866 }
867 }
868 }
869
870 // This is distinct from free_deallocate_list. For class loader data that are
871 // unloading, this frees the C heap memory for items on the list, and unlinks
872 // scratch or error classes so that unloading events aren't triggered for these
873 // classes. The metadata is removed with the unloading metaspace.
874 // There isn't C heap memory allocated for methods, so nothing is done for them.
875 void ClassLoaderData::free_deallocate_list_C_heap_structures() {
876 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
877 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
878 if (_deallocate_list == NULL) {
879 return;
880 }
881 // Go backwards because this removes entries that are freed.
882 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
883 Metadata* m = _deallocate_list->at(i);
884 _deallocate_list->remove_at(i);
885 if (m->is_constantPool()) {
886 ((ConstantPool*)m)->release_C_heap_structures();
887 } else if (m->is_klass()) {
888 InstanceKlass* ik = (InstanceKlass*)m;
889 // also releases ik->constants() C heap memory
890 InstanceKlass::release_C_heap_structures(ik);
891 // Remove the class so unloading events aren't triggered for
892 // this class (scratch or error class) in do_unloading().
893 remove_class(ik);
894 }
895 }
896 }
897
898 // These CLDs are to contain unsafe anonymous classes used for JSR292
899 ClassLoaderData* ClassLoaderData::unsafe_anonymous_class_loader_data(Handle loader) {
900 // Add a new class loader data to the graph.
901 return ClassLoaderDataGraph::add(loader, true);
902 }
903
904 // Caller needs ResourceMark
905 // If the class loader's _name has not been explicitly set, the class loader's
906 // qualified class name is returned.
907 const char* ClassLoaderData::loader_name() const {
908 if (_class_loader_klass == NULL) {
909 return BOOTSTRAP_LOADER_NAME;
910 } else if (_name != NULL) {
911 return _name->as_C_string();
912 } else {
913 return _class_loader_klass->external_name();
914 }
915 }
916
917 // Caller needs ResourceMark
918 // Format of the _name_and_id is as follows:
919 // If the defining loader has a name explicitly set then '<loader-name>' @<id>
920 // If the defining loader has no name then <qualified-class-name> @<id>
921 // If built-in loader, then omit '@<id>' as there is only one instance.
922 const char* ClassLoaderData::loader_name_and_id() const {
923 if (_class_loader_klass == NULL) {
924 return "'" BOOTSTRAP_LOADER_NAME "'";
925 } else if (_name_and_id != NULL) {
926 return _name_and_id->as_C_string();
927 } else {
928 // May be called in a race before _name_and_id is initialized.
929 return _class_loader_klass->external_name();
930 }
931 }
932
933 void ClassLoaderData::print_value_on(outputStream* out) const {
934 if (!is_unloading() && class_loader() != NULL) {
935 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
936 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance
937 } else {
938 // loader data: 0xsomeaddr of 'bootstrap'
939 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
940 }
941 if (is_unsafe_anonymous()) {
942 out->print(" unsafe anonymous");
943 }
944 }
945
946 void ClassLoaderData::print_value() const { print_value_on(tty); }
947
948 #ifndef PRODUCT
949 void ClassLoaderData::print_on(outputStream* out) const {
950 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
951 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id());
952 if (is_unsafe_anonymous()) out->print(" unsafe anonymous");
953 if (claimed()) out->print(" claimed");
954 if (is_unloading()) out->print(" unloading");
955 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
956
957 if (_jmethod_ids != NULL) {
958 Method::print_jmethod_ids(this, out);
959 }
960 out->print(" handles count %d", _handles.count());
961 out->print(" dependencies %d", _dependency_count);
962 out->print_cr("}");
963 }
964 #endif // PRODUCT
965
966 void ClassLoaderData::print() const { print_on(tty); }
967
968 void ClassLoaderData::verify() {
969 assert_locked_or_safepoint(_metaspace_lock);
970 oop cl = class_loader();
971
972 guarantee(this == class_loader_data(cl) || is_unsafe_anonymous(), "Must be the same");
973 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_unsafe_anonymous(), "must be");
974
975 // Verify the integrity of the allocated space.
976 if (metaspace_or_null() != NULL) {
977 metaspace_or_null()->verify();
978 }
979
980 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
981 guarantee(k->class_loader_data() == this, "Must be the same");
982 k->verify();
983 assert(k != k->next_link(), "no loops!");
984 }
985 }
986
987 bool ClassLoaderData::contains_klass(Klass* klass) {
988 // Lock-free access requires load_acquire
989 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
990 if (k == klass) return true;
991 }
992 return false;
993 }