1 /*
2 * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // A ClassLoaderData identifies the full set of class types that a class
26 // loader's name resolution strategy produces for a given configuration of the
27 // class loader.
28 // Class types in the ClassLoaderData may be defined by from class file binaries
29 // provided by the class loader, or from other class loader it interacts with
30 // according to its name resolution strategy.
31 //
32 // Class loaders that implement a deterministic name resolution strategy
33 // (including with respect to their delegation behavior), such as the boot, the
34 // platform, and the system loaders of the JDK's built-in class loader
35 // hierarchy, always produce the same linkset for a given configuration.
36 //
37 // ClassLoaderData carries information related to a linkset (e.g.,
38 // metaspace holding its klass definitions).
39 // The System Dictionary and related data structures (e.g., placeholder table,
40 // loader constraints table) as well as the runtime representation of classes
41 // only reference ClassLoaderData.
42 //
43 // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that
44 // that represent the loader's "linking domain" in the JVM.
45 //
46 // The bootstrap loader (represented by NULL) also has a ClassLoaderData,
47 // the singleton class the_null_class_loader_data().
48
49 #include "precompiled.hpp"
50 #include "classfile/classLoaderData.hpp"
51 #include "classfile/classLoaderData.inline.hpp"
52 #include "classfile/dictionary.hpp"
53 #include "classfile/javaClasses.hpp"
54 #include "classfile/metadataOnStackMark.hpp"
55 #include "classfile/moduleEntry.hpp"
56 #include "classfile/packageEntry.hpp"
57 #include "classfile/symbolTable.hpp"
58 #include "classfile/systemDictionary.hpp"
59 #include "logging/log.hpp"
60 #include "logging/logStream.hpp"
61 #include "memory/allocation.inline.hpp"
62 #include "memory/metadataFactory.hpp"
63 #include "memory/metaspaceShared.hpp"
64 #include "memory/resourceArea.hpp"
65 #include "memory/universe.hpp"
66 #include "oops/access.inline.hpp"
67 #include "oops/oop.inline.hpp"
68 #include "oops/oopHandle.inline.hpp"
69 #include "oops/weakHandle.inline.hpp"
70 #include "runtime/atomic.hpp"
71 #include "runtime/handles.inline.hpp"
72 #include "runtime/mutex.hpp"
73 #include "runtime/orderAccess.hpp"
74 #include "runtime/safepoint.hpp"
75 #include "runtime/safepointVerifiers.hpp"
76 #include "utilities/growableArray.hpp"
77 #include "utilities/macros.hpp"
78 #include "utilities/ostream.hpp"
79
80 volatile size_t ClassLoaderDataGraph::_num_array_classes = 0;
81 volatile size_t ClassLoaderDataGraph::_num_instance_classes = 0;
82
83 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
84
85 void ClassLoaderData::init_null_class_loader_data() {
86 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
87 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
88
89 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
90 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
91 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
92
93 LogTarget(Trace, class, loader, data) lt;
94 if (lt.is_enabled()) {
95 ResourceMark rm;
96 LogStream ls(lt);
97 ls.print("create ");
98 _the_null_class_loader_data->print_value_on(&ls);
99 ls.cr();
100 }
101 }
102
103 // Obtain and set the class loader's name within the ClassLoaderData so
104 // it will be available for error messages, logging, JFR, etc. The name
105 // and klass are available after the class_loader oop is no longer alive,
106 // during unloading.
107 void ClassLoaderData::initialize_name(Handle class_loader) {
108 Thread* THREAD = Thread::current();
109 ResourceMark rm(THREAD);
110
111 // Obtain the class loader's name. If the class loader's name was not
112 // explicitly set during construction, the CLD's _name field will be null.
113 oop cl_name = java_lang_ClassLoader::name(class_loader());
114 if (cl_name != NULL) {
115 const char* cl_instance_name = java_lang_String::as_utf8_string(cl_name);
116
117 if (cl_instance_name != NULL && cl_instance_name[0] != '\0') {
118 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore.
119 _name = SymbolTable::new_symbol(cl_instance_name, CATCH);
120 }
121 }
122
123 // Obtain the class loader's name and identity hash. If the class loader's
124 // name was not explicitly set during construction, the class loader's name and id
125 // will be set to the qualified class name of the class loader along with its
126 // identity hash.
127 // If for some reason the ClassLoader's constructor has not been run, instead of
128 // leaving the _name_and_id field null, fall back to the external qualified class
129 // name. Thus CLD's _name_and_id field should never have a null value.
130 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader());
131 const char* cl_instance_name_and_id =
132 (cl_name_and_id == NULL) ? _class_loader_klass->external_name() :
133 java_lang_String::as_utf8_string(cl_name_and_id);
134 assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id");
135 // Can't throw InternalError and SymbolTable doesn't throw OOM anymore.
136 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id, CATCH);
137 }
138
139 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_unsafe_anonymous) :
140 _metaspace(NULL),
141 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
142 Monitor::_safepoint_check_never)),
143 _unloading(false), _is_unsafe_anonymous(is_unsafe_anonymous),
144 _modified_oops(true), _accumulated_modified_oops(false),
145 // An unsafe anonymous class loader data doesn't have anything to keep
146 // it from being unloaded during parsing of the unsafe anonymous class.
147 // The null-class-loader should always be kept alive.
148 _keep_alive((is_unsafe_anonymous || h_class_loader.is_null()) ? 1 : 0),
149 _claimed(0),
150 _handles(),
151 _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL),
152 _jmethod_ids(NULL),
153 _deallocate_list(NULL),
154 _next(NULL),
155 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL) {
156
157 if (!h_class_loader.is_null()) {
158 _class_loader = _handles.add(h_class_loader());
159 _class_loader_klass = h_class_loader->klass();
160 initialize_name(h_class_loader);
161 }
162
163 if (!is_unsafe_anonymous) {
164 // The holder is initialized later for unsafe anonymous classes, and before calling anything
165 // that call class_loader().
166 initialize_holder(h_class_loader);
167
168 // A ClassLoaderData created solely for an unsafe anonymous class should never have a
169 // ModuleEntryTable or PackageEntryTable created for it. The defining package
170 // and module for an unsafe anonymous class will be found in its host class.
171 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
172 if (h_class_loader.is_null()) {
173 // Create unnamed module for boot loader
174 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
175 } else {
176 // Create unnamed module for all other loaders
177 _unnamed_module = ModuleEntry::create_unnamed_module(this);
178 }
179 _dictionary = create_dictionary();
180 }
181
182 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
183
184 JFR_ONLY(INIT_ID(this);)
185 }
186
187 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
188 Chunk* c = _head;
189 while (c != NULL) {
190 Chunk* next = c->_next;
191 delete c;
192 c = next;
193 }
194 }
195
196 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
197 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
198 Chunk* next = new Chunk(_head);
199 OrderAccess::release_store(&_head, next);
200 }
201 oop* handle = &_head->_data[_head->_size];
202 *handle = o;
203 OrderAccess::release_store(&_head->_size, _head->_size + 1);
204 return handle;
205 }
206
207 int ClassLoaderData::ChunkedHandleList::count() const {
208 int count = 0;
209 Chunk* chunk = _head;
210 while (chunk != NULL) {
211 count += chunk->_size;
212 chunk = chunk->_next;
213 }
214 return count;
215 }
216
217 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
218 for (juint i = 0; i < size; i++) {
219 if (c->_data[i] != NULL) {
220 f->do_oop(&c->_data[i]);
221 }
222 }
223 }
224
225 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
226 Chunk* head = OrderAccess::load_acquire(&_head);
227 if (head != NULL) {
228 // Must be careful when reading size of head
229 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
230 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
231 oops_do_chunk(f, c, c->_size);
232 }
233 }
234 }
235
236 class VerifyContainsOopClosure : public OopClosure {
237 oop _target;
238 bool _found;
239
240 public:
241 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
242
243 void do_oop(oop* p) {
244 if (p != NULL && oopDesc::equals(RawAccess<>::oop_load(p), _target)) {
245 _found = true;
246 }
247 }
248
249 void do_oop(narrowOop* p) {
250 // The ChunkedHandleList should not contain any narrowOop
251 ShouldNotReachHere();
252 }
253
254 bool found() const {
255 return _found;
256 }
257 };
258
259 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
260 VerifyContainsOopClosure cl(p);
261 oops_do(&cl);
262 return cl.found();
263 }
264
265 #ifndef PRODUCT
266 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
267 Chunk* chunk = _head;
268 while (chunk != NULL) {
269 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
270 return true;
271 }
272 chunk = chunk->_next;
273 }
274 return false;
275 }
276 #endif // PRODUCT
277
278 bool ClassLoaderData::claim() {
279 if (_claimed == 1) {
280 return false;
281 }
282
283 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
284 }
285
286 // Unsafe anonymous classes have their own ClassLoaderData that is marked to keep alive
287 // while the class is being parsed, and if the class appears on the module fixup list.
288 // Due to the uniqueness that no other class shares the unsafe anonymous class' name or
289 // ClassLoaderData, no other non-GC thread has knowledge of the unsafe anonymous class while
290 // it is being defined, therefore _keep_alive is not volatile or atomic.
291 void ClassLoaderData::inc_keep_alive() {
292 if (is_unsafe_anonymous()) {
293 assert(_keep_alive >= 0, "Invalid keep alive increment count");
294 _keep_alive++;
295 }
296 }
297
298 void ClassLoaderData::dec_keep_alive() {
299 if (is_unsafe_anonymous()) {
300 assert(_keep_alive > 0, "Invalid keep alive decrement count");
301 _keep_alive--;
302 }
303 }
304
305 void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
306 if (must_claim && !claim()) {
307 return;
308 }
309
310 // Only clear modified_oops after the ClassLoaderData is claimed.
311 if (clear_mod_oops) {
312 clear_modified_oops();
313 }
314
315 _handles.oops_do(f);
316 }
317
318 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
319 // Lock-free access requires load_acquire
320 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
321 klass_closure->do_klass(k);
322 assert(k != k->next_link(), "no loops!");
323 }
324 }
325
326 void ClassLoaderData::classes_do(void f(Klass * const)) {
327 // Lock-free access requires load_acquire
328 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
329 f(k);
330 assert(k != k->next_link(), "no loops!");
331 }
332 }
333
334 void ClassLoaderData::methods_do(void f(Method*)) {
335 // Lock-free access requires load_acquire
336 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
337 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
338 InstanceKlass::cast(k)->methods_do(f);
339 }
340 }
341 }
342
343 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
344 // Lock-free access requires load_acquire
345 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
346 // Do not filter ArrayKlass oops here...
347 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
348 #ifdef ASSERT
349 oop m = k->java_mirror();
350 assert(m != NULL, "NULL mirror");
351 assert(m->is_a(SystemDictionary::Class_klass()), "invalid mirror");
352 #endif
353 klass_closure->do_klass(k);
354 }
355 }
356 }
357
358 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
359 // Lock-free access requires load_acquire
360 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
361 if (k->is_instance_klass()) {
362 f(InstanceKlass::cast(k));
363 }
364 assert(k != k->next_link(), "no loops!");
365 }
366 }
367
368 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
369 assert_locked_or_safepoint(Module_lock);
370 if (_unnamed_module != NULL) {
371 f(_unnamed_module);
372 }
373 if (_modules != NULL) {
374 for (int i = 0; i < _modules->table_size(); i++) {
375 for (ModuleEntry* entry = _modules->bucket(i);
376 entry != NULL;
377 entry = entry->next()) {
378 f(entry);
379 }
380 }
381 }
382 }
383
384 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
385 assert_locked_or_safepoint(Module_lock);
386 if (_packages != NULL) {
387 for (int i = 0; i < _packages->table_size(); i++) {
388 for (PackageEntry* entry = _packages->bucket(i);
389 entry != NULL;
390 entry = entry->next()) {
391 f(entry);
392 }
393 }
394 }
395 }
396
397 void ClassLoaderData::record_dependency(const Klass* k) {
398 assert(k != NULL, "invariant");
399
400 ClassLoaderData * const from_cld = this;
401 ClassLoaderData * const to_cld = k->class_loader_data();
402
403 // Do not need to record dependency if the dependency is to a class whose
404 // class loader data is never freed. (i.e. the dependency's class loader
405 // is one of the three builtin class loaders and the dependency is not
406 // unsafe anonymous.)
407 if (to_cld->is_permanent_class_loader_data()) {
408 return;
409 }
410
411 oop to;
412 if (to_cld->is_unsafe_anonymous()) {
413 // Just return if an unsafe anonymous class is attempting to record a dependency
414 // to itself. (Note that every unsafe anonymous class has its own unique class
415 // loader data.)
416 if (to_cld == from_cld) {
417 return;
418 }
419 // Unsafe anonymous class dependencies are through the mirror.
420 to = k->java_mirror();
421 } else {
422 to = to_cld->class_loader();
423 oop from = from_cld->class_loader();
424
425 // Just return if this dependency is to a class with the same or a parent
426 // class_loader.
427 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) {
428 return; // this class loader is in the parent list, no need to add it.
429 }
430 }
431
432 // It's a dependency we won't find through GC, add it.
433 if (!_handles.contains(to)) {
434 NOT_PRODUCT(Atomic::inc(&_dependency_count));
435 LogTarget(Trace, class, loader, data) lt;
436 if (lt.is_enabled()) {
437 ResourceMark rm;
438 LogStream ls(lt);
439 ls.print("adding dependency from ");
440 print_value_on(&ls);
441 ls.print(" to ");
442 to_cld->print_value_on(&ls);
443 ls.cr();
444 }
445 Handle dependency(Thread::current(), to);
446 add_handle(dependency);
447 // Added a potentially young gen oop to the ClassLoaderData
448 record_modified_oops();
449 }
450 }
451
452
453 void ClassLoaderDataGraph::clear_claimed_marks() {
454 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
455 cld->clear_claimed();
456 }
457 }
458
459 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
460 {
461 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
462 Klass* old_value = _klasses;
463 k->set_next_link(old_value);
464 // Link the new item into the list, making sure the linked class is stable
465 // since the list can be walked without a lock
466 OrderAccess::release_store(&_klasses, k);
467 if (k->is_array_klass()) {
468 ClassLoaderDataGraph::inc_array_classes(1);
469 } else {
470 ClassLoaderDataGraph::inc_instance_classes(1);
471 }
472 }
473
474 if (publicize) {
475 LogTarget(Trace, class, loader, data) lt;
476 if (lt.is_enabled()) {
477 ResourceMark rm;
478 LogStream ls(lt);
479 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
480 print_value_on(&ls);
481 ls.cr();
482 }
483 }
484 }
485
486 // Class iterator used by the compiler. It gets some number of classes at
487 // a safepoint to decay invocation counters on the methods.
488 class ClassLoaderDataGraphKlassIteratorStatic {
489 ClassLoaderData* _current_loader_data;
490 Klass* _current_class_entry;
491 public:
492
493 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
494
495 InstanceKlass* try_get_next_class() {
496 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
497 size_t max_classes = ClassLoaderDataGraph::num_instance_classes();
498 assert(max_classes > 0, "should not be called with no instance classes");
499 for (size_t i = 0; i < max_classes; ) {
500
501 if (_current_class_entry != NULL) {
502 Klass* k = _current_class_entry;
503 _current_class_entry = _current_class_entry->next_link();
504
505 if (k->is_instance_klass()) {
506 InstanceKlass* ik = InstanceKlass::cast(k);
507 i++; // count all instance classes found
508 // Not yet loaded classes are counted in max_classes
509 // but only return loaded classes.
510 if (ik->is_loaded()) {
511 return ik;
512 }
513 }
514 } else {
515 // Go to next CLD
516 if (_current_loader_data != NULL) {
517 _current_loader_data = _current_loader_data->next();
518 }
519 // Start at the beginning
520 if (_current_loader_data == NULL) {
521 _current_loader_data = ClassLoaderDataGraph::_head;
522 }
523
524 _current_class_entry = _current_loader_data->klasses();
525 }
526 }
527 // Should never be reached unless all instance classes have failed or are not fully loaded.
528 // Caller handles NULL.
529 return NULL;
530 }
531
532 // If the current class for the static iterator is a class being unloaded or
533 // deallocated, adjust the current class.
534 void adjust_saved_class(ClassLoaderData* cld) {
535 if (_current_loader_data == cld) {
536 _current_loader_data = cld->next();
537 if (_current_loader_data != NULL) {
538 _current_class_entry = _current_loader_data->klasses();
539 } // else try_get_next_class will start at the head
540 }
541 }
542
543 void adjust_saved_class(Klass* klass) {
544 if (_current_class_entry == klass) {
545 _current_class_entry = klass->next_link();
546 }
547 }
548 };
549
550 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
551
552 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
553 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
554 return static_klass_iterator.try_get_next_class();
555 }
556
557
558 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
559 if (loader_or_mirror() != NULL) {
560 assert(_holder.is_null(), "never replace holders");
561 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror);
562 }
563 }
564
565 // Remove a klass from the _klasses list for scratch_class during redefinition
566 // or parsed class in the case of an error.
567 void ClassLoaderData::remove_class(Klass* scratch_class) {
568 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
569
570 // Adjust global class iterator.
571 static_klass_iterator.adjust_saved_class(scratch_class);
572
573 Klass* prev = NULL;
574 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
575 if (k == scratch_class) {
576 if (prev == NULL) {
577 _klasses = k->next_link();
578 } else {
579 Klass* next = k->next_link();
580 prev->set_next_link(next);
581 }
582
583 if (k->is_array_klass()) {
584 ClassLoaderDataGraph::dec_array_classes(1);
585 } else {
586 ClassLoaderDataGraph::dec_instance_classes(1);
587 }
588
589 return;
590 }
591 prev = k;
592 assert(k != k->next_link(), "no loops!");
593 }
594 ShouldNotReachHere(); // should have found this class!!
595 }
596
597 void ClassLoaderData::unload() {
598 _unloading = true;
599
600 LogTarget(Trace, class, loader, data) lt;
601 if (lt.is_enabled()) {
602 ResourceMark rm;
603 LogStream ls(lt);
604 ls.print("unload");
605 print_value_on(&ls);
606 ls.cr();
607 }
608
609 // Some items on the _deallocate_list need to free their C heap structures
610 // if they are not already on the _klasses list.
611 free_deallocate_list_C_heap_structures();
612
613 // Clean up class dependencies and tell serviceability tools
614 // these classes are unloading. Must be called
615 // after erroneous classes are released.
616 classes_do(InstanceKlass::unload_class);
617
618 // Clean up global class iterator for compiler
619 static_klass_iterator.adjust_saved_class(this);
620 }
621
622 ModuleEntryTable* ClassLoaderData::modules() {
623 // Lazily create the module entry table at first request.
624 // Lock-free access requires load_acquire.
625 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
626 if (modules == NULL) {
627 MutexLocker m1(Module_lock);
628 // Check if _modules got allocated while we were waiting for this lock.
629 if ((modules = _modules) == NULL) {
630 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
631
632 {
633 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
634 // Ensure _modules is stable, since it is examined without a lock
635 OrderAccess::release_store(&_modules, modules);
636 }
637 }
638 }
639 return modules;
640 }
641
642 const int _boot_loader_dictionary_size = 1009;
643 const int _default_loader_dictionary_size = 107;
644
645 Dictionary* ClassLoaderData::create_dictionary() {
646 assert(!is_unsafe_anonymous(), "unsafe anonymous class loader data do not have a dictionary");
647 int size;
648 bool resizable = false;
649 if (_the_null_class_loader_data == NULL) {
650 size = _boot_loader_dictionary_size;
651 resizable = true;
652 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
653 size = 1; // there's only one class in relection class loader and no initiated classes
654 } else if (is_system_class_loader_data()) {
655 size = _boot_loader_dictionary_size;
656 resizable = true;
657 } else {
658 size = _default_loader_dictionary_size;
659 resizable = true;
660 }
661 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) {
662 resizable = false;
663 }
664 return new Dictionary(this, size, resizable);
665 }
666
667 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
668 oop ClassLoaderData::holder_phantom() const {
669 // A klass that was previously considered dead can be looked up in the
670 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
671 // or a reachable object making it alive again. The SATB part of G1 needs
672 // to get notified about this potential resurrection, otherwise the marking
673 // might not find the object.
674 if (!_holder.is_null()) { // NULL class_loader
675 return _holder.resolve();
676 } else {
677 return NULL;
678 }
679 }
680
681 // Let the GC read the holder without keeping it alive.
682 oop ClassLoaderData::holder_no_keepalive() const {
683 if (!_holder.is_null()) { // NULL class_loader
684 return _holder.peek();
685 } else {
686 return NULL;
687 }
688 }
689
690 // Unloading support
691 bool ClassLoaderData::is_alive() const {
692 bool alive = keep_alive() // null class loader and incomplete unsafe anonymous klasses.
693 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
694
695 return alive;
696 }
697
698 class ReleaseKlassClosure: public KlassClosure {
699 private:
700 size_t _instance_class_released;
701 size_t _array_class_released;
702 public:
703 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
704
705 size_t instance_class_released() const { return _instance_class_released; }
706 size_t array_class_released() const { return _array_class_released; }
707
708 void do_klass(Klass* k) {
709 if (k->is_array_klass()) {
710 _array_class_released ++;
711 } else {
712 assert(k->is_instance_klass(), "Must be");
713 _instance_class_released ++;
714 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
715 }
716 }
717 };
718
719 ClassLoaderData::~ClassLoaderData() {
720 // Release C heap structures for all the classes.
721 ReleaseKlassClosure cl;
722 classes_do(&cl);
723
724 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
725 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
726
727 // Release the WeakHandle
728 _holder.release();
729
730 // Release C heap allocated hashtable for all the packages.
731 if (_packages != NULL) {
732 // Destroy the table itself
733 delete _packages;
734 _packages = NULL;
735 }
736
737 // Release C heap allocated hashtable for all the modules.
738 if (_modules != NULL) {
739 // Destroy the table itself
740 delete _modules;
741 _modules = NULL;
742 }
743
744 // Release C heap allocated hashtable for the dictionary
745 if (_dictionary != NULL) {
746 // Destroy the table itself
747 delete _dictionary;
748 _dictionary = NULL;
749 }
750
751 if (_unnamed_module != NULL) {
752 _unnamed_module->delete_unnamed_module();
753 _unnamed_module = NULL;
754 }
755
756 // release the metaspace
757 ClassLoaderMetaspace *m = _metaspace;
758 if (m != NULL) {
759 _metaspace = NULL;
760 delete m;
761 }
762 // Clear all the JNI handles for methods
763 // These aren't deallocated and are going to look like a leak, but that's
764 // needed because we can't really get rid of jmethodIDs because we don't
765 // know when native code is going to stop using them. The spec says that
766 // they're "invalid" but existing programs likely rely on their being
767 // NULL after class unloading.
768 if (_jmethod_ids != NULL) {
769 Method::clear_jmethod_ids(this);
770 }
771 // Delete lock
772 delete _metaspace_lock;
773
774 // Delete free list
775 if (_deallocate_list != NULL) {
776 delete _deallocate_list;
777 }
778
779 // Decrement refcounts of Symbols if created.
780 if (_name != NULL) {
781 _name->decrement_refcount();
782 }
783 if (_name_and_id != NULL) {
784 _name_and_id->decrement_refcount();
785 }
786 }
787
788 // Returns true if this class loader data is for the app class loader
789 // or a user defined system class loader. (Note that the class loader
790 // data may be unsafe anonymous.)
791 bool ClassLoaderData::is_system_class_loader_data() const {
792 return SystemDictionary::is_system_class_loader(class_loader());
793 }
794
795 // Returns true if this class loader data is for the platform class loader.
796 // (Note that the class loader data may be unsafe anonymous.)
797 bool ClassLoaderData::is_platform_class_loader_data() const {
798 return SystemDictionary::is_platform_class_loader(class_loader());
799 }
800
801 // Returns true if the class loader for this class loader data is one of
802 // the 3 builtin (boot application/system or platform) class loaders,
803 // including a user-defined system class loader. Note that if the class
804 // loader data is for an unsafe anonymous class then it may get freed by a GC
805 // even if its class loader is one of these loaders.
806 bool ClassLoaderData::is_builtin_class_loader_data() const {
807 return (is_boot_class_loader_data() ||
808 SystemDictionary::is_system_class_loader(class_loader()) ||
809 SystemDictionary::is_platform_class_loader(class_loader()));
810 }
811
812 // Returns true if this class loader data is a class loader data
813 // that is not ever freed by a GC. It must be the CLD for one of the builtin
814 // class loaders and not the CLD for an unsafe anonymous class.
815 bool ClassLoaderData::is_permanent_class_loader_data() const {
816 return is_builtin_class_loader_data() && !is_unsafe_anonymous();
817 }
818
819 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
820 // If the metaspace has not been allocated, create a new one. Might want
821 // to create smaller arena for Reflection class loaders also.
822 // The reason for the delayed allocation is because some class loaders are
823 // simply for delegating with no metadata of their own.
824 // Lock-free access requires load_acquire.
825 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
826 if (metaspace == NULL) {
827 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
828 // Check if _metaspace got allocated while we were waiting for this lock.
829 if ((metaspace = _metaspace) == NULL) {
830 if (this == the_null_class_loader_data()) {
831 assert (class_loader() == NULL, "Must be");
832 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
833 } else if (is_unsafe_anonymous()) {
834 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::UnsafeAnonymousMetaspaceType);
835 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
836 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
837 } else {
838 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
839 }
840 // Ensure _metaspace is stable, since it is examined without a lock
841 OrderAccess::release_store(&_metaspace, metaspace);
842 }
843 }
844 return metaspace;
845 }
846
847 OopHandle ClassLoaderData::add_handle(Handle h) {
848 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
849 record_modified_oops();
850 return OopHandle(_handles.add(h()));
851 }
852
853 void ClassLoaderData::remove_handle(OopHandle h) {
854 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
855 oop* ptr = h.ptr_raw();
856 if (ptr != NULL) {
857 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
858 NativeAccess<>::oop_store(ptr, oop(NULL));
859 }
860 }
861
862 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
863 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
864 if (dest.resolve() != NULL) {
865 return;
866 } else {
867 dest = _handles.add(h());
868 }
869 }
870
871 // Add this metadata pointer to be freed when it's safe. This is only during
872 // a safepoint which checks if handles point to this metadata field.
873 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
874 // Metadata in shared region isn't deleted.
875 if (!m->is_shared()) {
876 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
877 if (_deallocate_list == NULL) {
878 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
879 }
880 _deallocate_list->append_if_missing(m);
881 log_debug(class, loader, data)("deallocate added for %s", m->print_value_string());
882 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
883 }
884 }
885
886 // Deallocate free metadata on the free list. How useful the PermGen was!
887 void ClassLoaderData::free_deallocate_list() {
888 // Don't need lock, at safepoint
889 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
890 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
891 if (_deallocate_list == NULL) {
892 return;
893 }
894 // Go backwards because this removes entries that are freed.
895 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
896 Metadata* m = _deallocate_list->at(i);
897 if (!m->on_stack()) {
898 _deallocate_list->remove_at(i);
899 // There are only three types of metadata that we deallocate directly.
900 // Cast them so they can be used by the template function.
901 if (m->is_method()) {
902 MetadataFactory::free_metadata(this, (Method*)m);
903 } else if (m->is_constantPool()) {
904 MetadataFactory::free_metadata(this, (ConstantPool*)m);
905 } else if (m->is_klass()) {
906 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
907 } else {
908 ShouldNotReachHere();
909 }
910 } else {
911 // Metadata is alive.
912 // If scratch_class is on stack then it shouldn't be on this list!
913 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
914 "scratch classes on this list should be dead");
915 // Also should assert that other metadata on the list was found in handles.
916 // Some cleaning remains.
917 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
918 }
919 }
920 }
921
922 void ClassLoaderDataGraph::clean_deallocate_lists(bool walk_previous_versions) {
923 assert(SafepointSynchronize::is_at_safepoint(), "must only be called at safepoint");
924 uint loaders_processed = 0;
925 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
926 // is_alive check will be necessary for concurrent class unloading.
927 if (cld->is_alive()) {
928 // clean metaspace
929 if (walk_previous_versions) {
930 cld->classes_do(InstanceKlass::purge_previous_versions);
931 }
932 cld->free_deallocate_list();
933 loaders_processed++;
934 }
935 }
936 log_debug(class, loader, data)("clean_deallocate_lists: loaders processed %u %s",
937 loaders_processed, walk_previous_versions ? "walk_previous_versions" : "");
938 }
939
940 void ClassLoaderDataGraph::walk_metadata_and_clean_metaspaces() {
941 assert(SafepointSynchronize::is_at_safepoint(), "must only be called at safepoint");
942
943 _should_clean_deallocate_lists = false; // assume everything gets cleaned
944
945 // Mark metadata seen on the stack so we can delete unreferenced entries.
946 // Walk all metadata, including the expensive code cache walk, only for class redefinition.
947 // The MetadataOnStackMark walk during redefinition saves previous versions if it finds old methods
948 // on the stack or in the code cache, so we only have to repeat the full walk if
949 // they were found at that time.
950 // TODO: have redefinition clean old methods out of the code cache. They still exist in some places.
951 bool walk_all_metadata = InstanceKlass::has_previous_versions_and_reset();
952
953 MetadataOnStackMark md_on_stack(walk_all_metadata);
954 clean_deallocate_lists(walk_all_metadata);
955 }
956
957 // This is distinct from free_deallocate_list. For class loader data that are
958 // unloading, this frees the C heap memory for items on the list, and unlinks
959 // scratch or error classes so that unloading events aren't triggered for these
960 // classes. The metadata is removed with the unloading metaspace.
961 // There isn't C heap memory allocated for methods, so nothing is done for them.
962 void ClassLoaderData::free_deallocate_list_C_heap_structures() {
963 // Don't need lock, at safepoint
964 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
965 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
966 if (_deallocate_list == NULL) {
967 return;
968 }
969 // Go backwards because this removes entries that are freed.
970 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
971 Metadata* m = _deallocate_list->at(i);
972 _deallocate_list->remove_at(i);
973 if (m->is_constantPool()) {
974 ((ConstantPool*)m)->release_C_heap_structures();
975 } else if (m->is_klass()) {
976 InstanceKlass* ik = (InstanceKlass*)m;
977 // also releases ik->constants() C heap memory
978 InstanceKlass::release_C_heap_structures(ik);
979 // Remove the class so unloading events aren't triggered for
980 // this class (scratch or error class) in do_unloading().
981 remove_class(ik);
982 }
983 }
984 }
985
986 // These CLDs are to contain unsafe anonymous classes used for JSR292
987 ClassLoaderData* ClassLoaderData::unsafe_anonymous_class_loader_data(Handle loader) {
988 // Add a new class loader data to the graph.
989 return ClassLoaderDataGraph::add(loader, true);
990 }
991
992 // Caller needs ResourceMark
993 // If the class loader's _name has not been explicitly set, the class loader's
994 // qualified class name is returned.
995 const char* ClassLoaderData::loader_name() const {
996 if (_class_loader_klass == NULL) {
997 return BOOTSTRAP_LOADER_NAME;
998 } else if (_name != NULL) {
999 return _name->as_C_string();
1000 } else {
1001 return _class_loader_klass->external_name();
1002 }
1003 }
1004
1005 // Caller needs ResourceMark
1006 // Format of the _name_and_id is as follows:
1007 // If the defining loader has a name explicitly set then '<loader-name>' @<id>
1008 // If the defining loader has no name then <qualified-class-name> @<id>
1009 // If built-in loader, then omit '@<id>' as there is only one instance.
1010 const char* ClassLoaderData::loader_name_and_id() const {
1011 if (_class_loader_klass == NULL) {
1012 return "'" BOOTSTRAP_LOADER_NAME "'";
1013 } else if (_name_and_id != NULL) {
1014 return _name_and_id->as_C_string();
1015 } else {
1016 // May be called in a race before _name_and_id is initialized.
1017 return _class_loader_klass->external_name();
1018 }
1019 }
1020
1021 void ClassLoaderData::print_value_on(outputStream* out) const {
1022 if (!is_unloading() && class_loader() != NULL) {
1023 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
1024 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance
1025 } else {
1026 // loader data: 0xsomeaddr of 'bootstrap'
1027 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
1028 }
1029 if (is_unsafe_anonymous()) {
1030 out->print(" unsafe anonymous");
1031 }
1032 }
1033
1034 #ifndef PRODUCT
1035 void ClassLoaderData::print_on(outputStream* out) const {
1036 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
1037 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id());
1038 if (is_unsafe_anonymous()) out->print(" unsafe anonymous");
1039 if (claimed()) out->print(" claimed");
1040 if (is_unloading()) out->print(" unloading");
1041 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
1042
1043 if (_jmethod_ids != NULL) {
1044 Method::print_jmethod_ids(this, out);
1045 }
1046 out->print(" handles count %d", _handles.count());
1047 out->print(" dependencies %d", _dependency_count);
1048 out->print_cr("}");
1049 }
1050 #endif // PRODUCT
1051
1052 void ClassLoaderData::verify() {
1053 assert_locked_or_safepoint(_metaspace_lock);
1054 oop cl = class_loader();
1055
1056 guarantee(this == class_loader_data(cl) || is_unsafe_anonymous(), "Must be the same");
1057 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_unsafe_anonymous(), "must be");
1058
1059 // Verify the integrity of the allocated space.
1060 if (metaspace_or_null() != NULL) {
1061 metaspace_or_null()->verify();
1062 }
1063
1064 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
1065 guarantee(k->class_loader_data() == this, "Must be the same");
1066 k->verify();
1067 assert(k != k->next_link(), "no loops!");
1068 }
1069 }
1070
1071 bool ClassLoaderData::contains_klass(Klass* klass) {
1072 // Lock-free access requires load_acquire
1073 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
1074 if (k == klass) return true;
1075 }
1076 return false;
1077 }
1078
1079
1080 // GC root of class loader data created.
1081 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
1082 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
1083 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
1084 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
1085
1086 bool ClassLoaderDataGraph::_should_purge = false;
1087 bool ClassLoaderDataGraph::_should_clean_deallocate_lists = false;
1088 bool ClassLoaderDataGraph::_safepoint_cleanup_needed = false;
1089 bool ClassLoaderDataGraph::_metaspace_oom = false;
1090
1091 // Add a new class loader data node to the list. Assign the newly created
1092 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
1093 ClassLoaderData* ClassLoaderDataGraph::add_to_graph(Handle loader, bool is_unsafe_anonymous) {
1094
1095 assert_lock_strong(ClassLoaderDataGraph_lock);
1096
1097 ClassLoaderData* cld;
1098
1099 // First check if another thread beat us to creating the CLD and installing
1100 // it into the loader while we were waiting for the lock.
1101 if (!is_unsafe_anonymous && loader.not_null()) {
1102 cld = java_lang_ClassLoader::loader_data_acquire(loader());
1103 if (cld != NULL) {
1104 return cld;
1105 }
1106 }
1107
1108 // We mustn't GC until we've installed the ClassLoaderData in the Graph since the CLD
1109 // contains oops in _handles that must be walked. GC doesn't walk CLD from the
1110 // loader oop in all collections, particularly young collections.
1111 NoSafepointVerifier no_safepoints;
1112
1113 cld = new ClassLoaderData(loader, is_unsafe_anonymous);
1114
1115 // First install the new CLD to the Graph.
1116 cld->set_next(_head);
1117 _head = cld;
1118
1119 // Next associate with the class_loader.
1120 if (!is_unsafe_anonymous) {
1121 // Use OrderAccess, since readers need to get the loader_data only after
1122 // it's added to the Graph
1123 java_lang_ClassLoader::release_set_loader_data(loader(), cld);
1124 }
1125
1126 // Lastly log, if requested
1127 LogTarget(Trace, class, loader, data) lt;
1128 if (lt.is_enabled()) {
1129 ResourceMark rm;
1130 LogStream ls(lt);
1131 ls.print("create ");
1132 cld->print_value_on(&ls);
1133 ls.cr();
1134 }
1135 return cld;
1136 }
1137
1138 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_unsafe_anonymous) {
1139 MutexLocker ml(ClassLoaderDataGraph_lock);
1140 ClassLoaderData* loader_data = add_to_graph(loader, is_unsafe_anonymous);
1141 return loader_data;
1142 }
1143
1144 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1145 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1146 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1147 cl->do_cld(cld);
1148 }
1149 }
1150
1151 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1152 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1153 // Only walk the head until any clds not purged from prior unloading
1154 // (CMS doesn't purge right away).
1155 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1156 assert(cld->is_unloading(), "invariant");
1157 cl->do_cld(cld);
1158 }
1159 }
1160
1161 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1162 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1163 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1164 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1165 if (closure != NULL) {
1166 closure->do_cld(cld);
1167 }
1168 }
1169 }
1170
1171 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1172 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1173 if (ClassUnloading) {
1174 roots_cld_do(cl, NULL);
1175 } else {
1176 cld_do(cl);
1177 }
1178 }
1179
1180 // Closure for locking and iterating through classes.
1181 LockedClassesDo::LockedClassesDo(classes_do_func_t f) : _function(f) {
1182 ClassLoaderDataGraph_lock->lock();
1183 }
1184
1185 LockedClassesDo::LockedClassesDo() : _function(NULL) {
1186 // callers provide their own do_klass
1187 ClassLoaderDataGraph_lock->lock();
1188 }
1189
1190 LockedClassesDo::~LockedClassesDo() { ClassLoaderDataGraph_lock->unlock(); }
1191
1192
1193 // Iterating over the CLDG needs to be locked because
1194 // unloading can remove entries concurrently soon.
1195 class ClassLoaderDataGraphIterator : public StackObj {
1196 ClassLoaderData* _next;
1197 HandleMark _hm; // clean up handles when this is done.
1198 Handle _holder;
1199 Thread* _thread;
1200
1201 void hold_next() {
1202 if (_next != NULL) {
1203 _holder = Handle(_thread, _next->holder_phantom());
1204 }
1205 }
1206 public:
1207 ClassLoaderDataGraphIterator() : _next(ClassLoaderDataGraph::_head) {
1208 _thread = Thread::current();
1209 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1210 hold_next();
1211 }
1212
1213 bool repeat() const {
1214 return _next != NULL;
1215 }
1216
1217 ClassLoaderData* get_next() {
1218 ClassLoaderData* next = _next;
1219 if (_next != NULL) {
1220 _next = _next->next();
1221 hold_next();
1222 }
1223 return next;
1224 }
1225 };
1226
1227 // These functions assume that the caller has locked the ClassLoaderDataGraph_lock
1228 // if they are not calling the function from a safepoint.
1229 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1230 ClassLoaderDataGraphIterator iter;
1231 while (iter.repeat()) {
1232 ClassLoaderData* cld = iter.get_next();
1233 cld->classes_do(klass_closure);
1234 }
1235 }
1236
1237 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1238 ClassLoaderDataGraphIterator iter;
1239 while (iter.repeat()) {
1240 ClassLoaderData* cld = iter.get_next();
1241 cld->classes_do(f);
1242 }
1243 }
1244
1245 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1246 ClassLoaderDataGraphIterator iter;
1247 while (iter.repeat()) {
1248 ClassLoaderData* cld = iter.get_next();
1249 cld->methods_do(f);
1250 }
1251 }
1252
1253 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1254 assert_locked_or_safepoint(Module_lock);
1255 ClassLoaderDataGraphIterator iter;
1256 while (iter.repeat()) {
1257 ClassLoaderData* cld = iter.get_next();
1258 cld->modules_do(f);
1259 }
1260 }
1261
1262 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1263 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1264 // Only walk the head until any clds not purged from prior unloading
1265 // (CMS doesn't purge right away).
1266 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1267 assert(cld->is_unloading(), "invariant");
1268 cld->modules_do(f);
1269 }
1270 }
1271
1272 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1273 assert_locked_or_safepoint(Module_lock);
1274 ClassLoaderDataGraphIterator iter;
1275 while (iter.repeat()) {
1276 ClassLoaderData* cld = iter.get_next();
1277 cld->packages_do(f);
1278 }
1279 }
1280
1281 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1282 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1283 // Only walk the head until any clds not purged from prior unloading
1284 // (CMS doesn't purge right away).
1285 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1286 assert(cld->is_unloading(), "invariant");
1287 cld->packages_do(f);
1288 }
1289 }
1290
1291 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1292 ClassLoaderDataGraphIterator iter;
1293 while (iter.repeat()) {
1294 ClassLoaderData* cld = iter.get_next();
1295 cld->loaded_classes_do(klass_closure);
1296 }
1297 }
1298
1299 // This case can block but cannot do unloading (called from CDS)
1300 void ClassLoaderDataGraph::unlocked_loaded_classes_do(KlassClosure* klass_closure) {
1301 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1302 cld->loaded_classes_do(klass_closure);
1303 }
1304 }
1305
1306
1307 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1308 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1309 // Only walk the head until any clds not purged from prior unloading
1310 // (CMS doesn't purge right away).
1311 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1312 assert(cld->is_unloading(), "invariant");
1313 cld->classes_do(f);
1314 }
1315 }
1316
1317 #define FOR_ALL_DICTIONARY(X) ClassLoaderDataGraphIterator iter; \
1318 ClassLoaderData* X; \
1319 while ((X = iter.get_next()) != NULL) \
1320 if (X->dictionary() != NULL)
1321
1322 // Walk classes in the loaded class dictionaries in various forms.
1323 // Only walks the classes defined in this class loader.
1324 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1325 FOR_ALL_DICTIONARY(cld) {
1326 cld->dictionary()->classes_do(f);
1327 }
1328 }
1329
1330 // Only walks the classes defined in this class loader.
1331 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1332 FOR_ALL_DICTIONARY(cld) {
1333 cld->dictionary()->classes_do(f, CHECK);
1334 }
1335 }
1336
1337 void ClassLoaderDataGraph::verify_dictionary() {
1338 FOR_ALL_DICTIONARY(cld) {
1339 cld->dictionary()->verify();
1340 }
1341 }
1342
1343 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1344 FOR_ALL_DICTIONARY(cld) {
1345 st->print("Dictionary for ");
1346 cld->print_value_on(st);
1347 st->cr();
1348 cld->dictionary()->print_on(st);
1349 st->cr();
1350 }
1351 }
1352
1353 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1354 FOR_ALL_DICTIONARY(cld) {
1355 ResourceMark rm;
1356 stringStream tempst;
1357 tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id());
1358 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1359 }
1360 }
1361
1362 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1363 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1364 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1365
1366 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1367
1368 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1369 ClassLoaderData* curr = _head;
1370 while (curr != _saved_head) {
1371 if (!curr->claimed()) {
1372 array->push(curr);
1373 LogTarget(Debug, class, loader, data) lt;
1374 if (lt.is_enabled()) {
1375 LogStream ls(lt);
1376 ls.print("found new CLD: ");
1377 curr->print_value_on(&ls);
1378 ls.cr();
1379 }
1380 }
1381
1382 curr = curr->_next;
1383 }
1384
1385 return array;
1386 }
1387
1388 #ifndef PRODUCT
1389 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1390 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1391 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1392 if (loader_data == data) {
1393 return true;
1394 }
1395 }
1396
1397 return false;
1398 }
1399 #endif // PRODUCT
1400
1401 // Move class loader data from main list to the unloaded list for unloading
1402 // and deallocation later.
1403 bool ClassLoaderDataGraph::do_unloading(bool do_cleaning) {
1404 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1405
1406 // Indicate whether safepoint cleanup is needed.
1407 _safepoint_cleanup_needed |= do_cleaning;
1408
1409 ClassLoaderData* data = _head;
1410 ClassLoaderData* prev = NULL;
1411 bool seen_dead_loader = false;
1412 uint loaders_processed = 0;
1413 uint loaders_removed = 0;
1414
1415 // Save previous _unloading pointer for CMS which may add to unloading list before
1416 // purging and we don't want to rewalk the previously unloaded class loader data.
1417 _saved_unloading = _unloading;
1418
1419 data = _head;
1420 while (data != NULL) {
1421 if (data->is_alive()) {
1422 prev = data;
1423 data = data->next();
1424 loaders_processed++;
1425 continue;
1426 }
1427 seen_dead_loader = true;
1428 loaders_removed++;
1429 ClassLoaderData* dead = data;
1430 dead->unload();
1431 data = data->next();
1432 // Remove from loader list.
1433 // This class loader data will no longer be found
1434 // in the ClassLoaderDataGraph.
1435 if (prev != NULL) {
1436 prev->set_next(data);
1437 } else {
1438 assert(dead == _head, "sanity check");
1439 _head = data;
1440 }
1441 dead->set_next(_unloading);
1442 _unloading = dead;
1443 }
1444
1445 log_debug(class, loader, data)("do_unloading: loaders processed %u, loaders removed %u", loaders_processed, loaders_removed);
1446
1447 return seen_dead_loader;
1448 }
1449
1450 // There's at least one dead class loader. Purge refererences of healthy module
1451 // reads lists and package export lists to modules belonging to dead loaders.
1452 void ClassLoaderDataGraph::clean_module_and_package_info() {
1453 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1454
1455 ClassLoaderData* data = _head;
1456 while (data != NULL) {
1457 // Remove entries in the dictionary of live class loader that have
1458 // initiated loading classes in a dead class loader.
1459 if (data->dictionary() != NULL) {
1460 data->dictionary()->do_unloading();
1461 }
1462 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1463 // lists to determine if there are modules on those lists that are now
1464 // dead and should be removed. A module's life cycle is equivalent
1465 // to its defining class loader's life cycle. Since a module is
1466 // considered dead if its class loader is dead, these walks must
1467 // occur after each class loader's aliveness is determined.
1468 if (data->packages() != NULL) {
1469 data->packages()->purge_all_package_exports();
1470 }
1471 if (data->modules_defined()) {
1472 data->modules()->purge_all_module_reads();
1473 }
1474 data = data->next();
1475 }
1476 }
1477
1478 void ClassLoaderDataGraph::purge() {
1479 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1480 ClassLoaderData* list = _unloading;
1481 _unloading = NULL;
1482 ClassLoaderData* next = list;
1483 bool classes_unloaded = false;
1484 while (next != NULL) {
1485 ClassLoaderData* purge_me = next;
1486 next = purge_me->next();
1487 delete purge_me;
1488 classes_unloaded = true;
1489 }
1490 if (classes_unloaded) {
1491 Metaspace::purge();
1492 set_metaspace_oom(false);
1493 }
1494 }
1495
1496 int ClassLoaderDataGraph::resize_if_needed() {
1497 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1498 int resized = 0;
1499 if (Dictionary::does_any_dictionary_needs_resizing()) {
1500 FOR_ALL_DICTIONARY(cld) {
1501 if (cld->dictionary()->resize_if_needed()) {
1502 resized++;
1503 }
1504 }
1505 }
1506 return resized;
1507 }
1508
1509 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1510 : _next_klass(NULL) {
1511 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1512 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1513 Klass* klass = NULL;
1514
1515 // Find the first klass in the CLDG.
1516 while (cld != NULL) {
1517 assert_locked_or_safepoint(cld->metaspace_lock());
1518 klass = cld->_klasses;
1519 if (klass != NULL) {
1520 _next_klass = klass;
1521 return;
1522 }
1523 cld = cld->next();
1524 }
1525 }
1526
1527 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1528 Klass* next = klass->next_link();
1529 if (next != NULL) {
1530 return next;
1531 }
1532
1533 // No more klasses in the current CLD. Time to find a new CLD.
1534 ClassLoaderData* cld = klass->class_loader_data();
1535 assert_locked_or_safepoint(cld->metaspace_lock());
1536 while (next == NULL) {
1537 cld = cld->next();
1538 if (cld == NULL) {
1539 break;
1540 }
1541 next = cld->_klasses;
1542 }
1543
1544 return next;
1545 }
1546
1547 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1548 Klass* head = _next_klass;
1549
1550 while (head != NULL) {
1551 Klass* next = next_klass_in_cldg(head);
1552
1553 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1554
1555 if (old_head == head) {
1556 return head; // Won the CAS.
1557 }
1558
1559 head = old_head;
1560 }
1561
1562 // Nothing more for the iterator to hand out.
1563 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1564 return NULL;
1565 }
1566
1567 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1568 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1569 _data = ClassLoaderDataGraph::_head;
1570 }
1571
1572 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1573
1574 #ifndef PRODUCT
1575 // callable from debugger
1576 extern "C" int print_loader_data_graph() {
1577 ResourceMark rm;
1578 ClassLoaderDataGraph::print_on(tty);
1579 return 0;
1580 }
1581
1582 void ClassLoaderDataGraph::verify() {
1583 ClassLoaderDataGraphIterator iter;
1584 while (iter.repeat()) {
1585 ClassLoaderData* cld = iter.get_next();
1586 cld->verify();
1587 }
1588 }
1589
1590 void ClassLoaderDataGraph::print_on(outputStream * const out) {
1591 ClassLoaderDataGraphIterator iter;
1592 while (iter.repeat()) {
1593 ClassLoaderData* cld = iter.get_next();
1594 cld->print_on(out);
1595 }
1596 }
1597 #endif // PRODUCT