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 klass_closure->do_klass(k);
349 }
350 }
351 }
352
353 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
354 // Lock-free access requires load_acquire
355 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
356 if (k->is_instance_klass()) {
357 f(InstanceKlass::cast(k));
358 }
359 assert(k != k->next_link(), "no loops!");
360 }
361 }
362
363 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
364 assert_locked_or_safepoint(Module_lock);
365 if (_unnamed_module != NULL) {
366 f(_unnamed_module);
367 }
368 if (_modules != NULL) {
369 for (int i = 0; i < _modules->table_size(); i++) {
370 for (ModuleEntry* entry = _modules->bucket(i);
371 entry != NULL;
372 entry = entry->next()) {
373 f(entry);
374 }
375 }
376 }
377 }
378
379 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
380 assert_locked_or_safepoint(Module_lock);
381 if (_packages != NULL) {
382 for (int i = 0; i < _packages->table_size(); i++) {
383 for (PackageEntry* entry = _packages->bucket(i);
384 entry != NULL;
385 entry = entry->next()) {
386 f(entry);
387 }
388 }
389 }
390 }
391
392 void ClassLoaderData::record_dependency(const Klass* k) {
393 assert(k != NULL, "invariant");
394
395 ClassLoaderData * const from_cld = this;
396 ClassLoaderData * const to_cld = k->class_loader_data();
397
398 // Do not need to record dependency if the dependency is to a class whose
399 // class loader data is never freed. (i.e. the dependency's class loader
400 // is one of the three builtin class loaders and the dependency is not
401 // unsafe anonymous.)
402 if (to_cld->is_permanent_class_loader_data()) {
403 return;
404 }
405
406 oop to;
407 if (to_cld->is_unsafe_anonymous()) {
408 // Just return if an unsafe anonymous class is attempting to record a dependency
409 // to itself. (Note that every unsafe anonymous class has its own unique class
410 // loader data.)
411 if (to_cld == from_cld) {
412 return;
413 }
414 // Unsafe anonymous class dependencies are through the mirror.
415 to = k->java_mirror();
416 } else {
417 to = to_cld->class_loader();
418 oop from = from_cld->class_loader();
419
420 // Just return if this dependency is to a class with the same or a parent
421 // class_loader.
422 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) {
423 return; // this class loader is in the parent list, no need to add it.
424 }
425 }
426
427 // It's a dependency we won't find through GC, add it.
428 if (!_handles.contains(to)) {
429 NOT_PRODUCT(Atomic::inc(&_dependency_count));
430 LogTarget(Trace, class, loader, data) lt;
431 if (lt.is_enabled()) {
432 ResourceMark rm;
433 LogStream ls(lt);
434 ls.print("adding dependency from ");
435 print_value_on(&ls);
436 ls.print(" to ");
437 to_cld->print_value_on(&ls);
438 ls.cr();
439 }
440 Handle dependency(Thread::current(), to);
441 add_handle(dependency);
442 // Added a potentially young gen oop to the ClassLoaderData
443 record_modified_oops();
444 }
445 }
446
447
448 void ClassLoaderDataGraph::clear_claimed_marks() {
449 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
450 cld->clear_claimed();
451 }
452 }
453
454 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
455 {
456 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
457 Klass* old_value = _klasses;
458 k->set_next_link(old_value);
459 // Link the new item into the list, making sure the linked class is stable
460 // since the list can be walked without a lock
461 OrderAccess::release_store(&_klasses, k);
462 if (k->is_array_klass()) {
463 ClassLoaderDataGraph::inc_array_classes(1);
464 } else {
465 ClassLoaderDataGraph::inc_instance_classes(1);
466 }
467 }
468
469 if (publicize) {
470 LogTarget(Trace, class, loader, data) lt;
471 if (lt.is_enabled()) {
472 ResourceMark rm;
473 LogStream ls(lt);
474 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
475 print_value_on(&ls);
476 ls.cr();
477 }
478 }
479 }
480
481 // Class iterator used by the compiler. It gets some number of classes at
482 // a safepoint to decay invocation counters on the methods.
483 class ClassLoaderDataGraphKlassIteratorStatic {
484 ClassLoaderData* _current_loader_data;
485 Klass* _current_class_entry;
486 public:
487
488 ClassLoaderDataGraphKlassIteratorStatic() : _current_loader_data(NULL), _current_class_entry(NULL) {}
489
490 InstanceKlass* try_get_next_class() {
491 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
492 size_t max_classes = ClassLoaderDataGraph::num_instance_classes();
493 assert(max_classes > 0, "should not be called with no instance classes");
494 for (size_t i = 0; i < max_classes; ) {
495
496 if (_current_class_entry != NULL) {
497 Klass* k = _current_class_entry;
498 _current_class_entry = _current_class_entry->next_link();
499
500 if (k->is_instance_klass()) {
501 InstanceKlass* ik = InstanceKlass::cast(k);
502 i++; // count all instance classes found
503 // Not yet loaded classes are counted in max_classes
504 // but only return loaded classes.
505 if (ik->is_loaded()) {
506 return ik;
507 }
508 }
509 } else {
510 // Go to next CLD
511 if (_current_loader_data != NULL) {
512 _current_loader_data = _current_loader_data->next();
513 }
514 // Start at the beginning
515 if (_current_loader_data == NULL) {
516 _current_loader_data = ClassLoaderDataGraph::_head;
517 }
518
519 _current_class_entry = _current_loader_data->klasses();
520 }
521 }
522 // Should never be reached unless all instance classes have failed or are not fully loaded.
523 // Caller handles NULL.
524 return NULL;
525 }
526
527 // If the current class for the static iterator is a class being unloaded or
528 // deallocated, adjust the current class.
529 void adjust_saved_class(ClassLoaderData* cld) {
530 if (_current_loader_data == cld) {
531 _current_loader_data = cld->next();
532 if (_current_loader_data != NULL) {
533 _current_class_entry = _current_loader_data->klasses();
534 } // else try_get_next_class will start at the head
535 }
536 }
537
538 void adjust_saved_class(Klass* klass) {
539 if (_current_class_entry == klass) {
540 _current_class_entry = klass->next_link();
541 }
542 }
543 };
544
545 static ClassLoaderDataGraphKlassIteratorStatic static_klass_iterator;
546
547 InstanceKlass* ClassLoaderDataGraph::try_get_next_class() {
548 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
549 return static_klass_iterator.try_get_next_class();
550 }
551
552
553 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
554 if (loader_or_mirror() != NULL) {
555 assert(_holder.is_null(), "never replace holders");
556 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror);
557 }
558 }
559
560 // Remove a klass from the _klasses list for scratch_class during redefinition
561 // or parsed class in the case of an error.
562 void ClassLoaderData::remove_class(Klass* scratch_class) {
563 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
564
565 // Adjust global class iterator.
566 static_klass_iterator.adjust_saved_class(scratch_class);
567
568 Klass* prev = NULL;
569 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
570 if (k == scratch_class) {
571 if (prev == NULL) {
572 _klasses = k->next_link();
573 } else {
574 Klass* next = k->next_link();
575 prev->set_next_link(next);
576 }
577
578 if (k->is_array_klass()) {
579 ClassLoaderDataGraph::dec_array_classes(1);
580 } else {
581 ClassLoaderDataGraph::dec_instance_classes(1);
582 }
583
584 return;
585 }
586 prev = k;
587 assert(k != k->next_link(), "no loops!");
588 }
589 ShouldNotReachHere(); // should have found this class!!
590 }
591
592 void ClassLoaderData::unload() {
593 _unloading = true;
594
595 LogTarget(Trace, class, loader, data) lt;
596 if (lt.is_enabled()) {
597 ResourceMark rm;
598 LogStream ls(lt);
599 ls.print("unload");
600 print_value_on(&ls);
601 ls.cr();
602 }
603
604 // Some items on the _deallocate_list need to free their C heap structures
605 // if they are not already on the _klasses list.
606 free_deallocate_list_C_heap_structures();
607
608 // Clean up class dependencies and tell serviceability tools
609 // these classes are unloading. Must be called
610 // after erroneous classes are released.
611 classes_do(InstanceKlass::unload_class);
612
613 // Clean up global class iterator for compiler
614 static_klass_iterator.adjust_saved_class(this);
615 }
616
617 ModuleEntryTable* ClassLoaderData::modules() {
618 // Lazily create the module entry table at first request.
619 // Lock-free access requires load_acquire.
620 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
621 if (modules == NULL) {
622 MutexLocker m1(Module_lock);
623 // Check if _modules got allocated while we were waiting for this lock.
624 if ((modules = _modules) == NULL) {
625 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
626
627 {
628 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
629 // Ensure _modules is stable, since it is examined without a lock
630 OrderAccess::release_store(&_modules, modules);
631 }
632 }
633 }
634 return modules;
635 }
636
637 const int _boot_loader_dictionary_size = 1009;
638 const int _default_loader_dictionary_size = 107;
639
640 Dictionary* ClassLoaderData::create_dictionary() {
641 assert(!is_unsafe_anonymous(), "unsafe anonymous class loader data do not have a dictionary");
642 int size;
643 bool resizable = false;
644 if (_the_null_class_loader_data == NULL) {
645 size = _boot_loader_dictionary_size;
646 resizable = true;
647 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
648 size = 1; // there's only one class in relection class loader and no initiated classes
649 } else if (is_system_class_loader_data()) {
650 size = _boot_loader_dictionary_size;
651 resizable = true;
652 } else {
653 size = _default_loader_dictionary_size;
654 resizable = true;
655 }
656 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) {
657 resizable = false;
658 }
659 return new Dictionary(this, size, resizable);
660 }
661
662 // Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
663 oop ClassLoaderData::holder_phantom() const {
664 // A klass that was previously considered dead can be looked up in the
665 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
666 // or a reachable object making it alive again. The SATB part of G1 needs
667 // to get notified about this potential resurrection, otherwise the marking
668 // might not find the object.
669 if (!_holder.is_null()) { // NULL class_loader
670 return _holder.resolve();
671 } else {
672 return NULL;
673 }
674 }
675
676 // Let the GC read the holder without keeping it alive.
677 oop ClassLoaderData::holder_no_keepalive() const {
678 if (!_holder.is_null()) { // NULL class_loader
679 return _holder.peek();
680 } else {
681 return NULL;
682 }
683 }
684
685 // Unloading support
686 bool ClassLoaderData::is_alive() const {
687 bool alive = keep_alive() // null class loader and incomplete unsafe anonymous klasses.
688 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
689
690 return alive;
691 }
692
693 class ReleaseKlassClosure: public KlassClosure {
694 private:
695 size_t _instance_class_released;
696 size_t _array_class_released;
697 public:
698 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
699
700 size_t instance_class_released() const { return _instance_class_released; }
701 size_t array_class_released() const { return _array_class_released; }
702
703 void do_klass(Klass* k) {
704 if (k->is_array_klass()) {
705 _array_class_released ++;
706 } else {
707 assert(k->is_instance_klass(), "Must be");
708 _instance_class_released ++;
709 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
710 }
711 }
712 };
713
714 ClassLoaderData::~ClassLoaderData() {
715 // Release C heap structures for all the classes.
716 ReleaseKlassClosure cl;
717 classes_do(&cl);
718
719 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
720 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
721
722 // Release the WeakHandle
723 _holder.release();
724
725 // Release C heap allocated hashtable for all the packages.
726 if (_packages != NULL) {
727 // Destroy the table itself
728 delete _packages;
729 _packages = NULL;
730 }
731
732 // Release C heap allocated hashtable for all the modules.
733 if (_modules != NULL) {
734 // Destroy the table itself
735 delete _modules;
736 _modules = NULL;
737 }
738
739 // Release C heap allocated hashtable for the dictionary
740 if (_dictionary != NULL) {
741 // Destroy the table itself
742 delete _dictionary;
743 _dictionary = NULL;
744 }
745
746 if (_unnamed_module != NULL) {
747 _unnamed_module->delete_unnamed_module();
748 _unnamed_module = NULL;
749 }
750
751 // release the metaspace
752 ClassLoaderMetaspace *m = _metaspace;
753 if (m != NULL) {
754 _metaspace = NULL;
755 delete m;
756 }
757 // Clear all the JNI handles for methods
758 // These aren't deallocated and are going to look like a leak, but that's
759 // needed because we can't really get rid of jmethodIDs because we don't
760 // know when native code is going to stop using them. The spec says that
761 // they're "invalid" but existing programs likely rely on their being
762 // NULL after class unloading.
763 if (_jmethod_ids != NULL) {
764 Method::clear_jmethod_ids(this);
765 }
766 // Delete lock
767 delete _metaspace_lock;
768
769 // Delete free list
770 if (_deallocate_list != NULL) {
771 delete _deallocate_list;
772 }
773
774 // Decrement refcounts of Symbols if created.
775 if (_name != NULL) {
776 _name->decrement_refcount();
777 }
778 if (_name_and_id != NULL) {
779 _name_and_id->decrement_refcount();
780 }
781 }
782
783 // Returns true if this class loader data is for the app class loader
784 // or a user defined system class loader. (Note that the class loader
785 // data may be unsafe anonymous.)
786 bool ClassLoaderData::is_system_class_loader_data() const {
787 return SystemDictionary::is_system_class_loader(class_loader());
788 }
789
790 // Returns true if this class loader data is for the platform class loader.
791 // (Note that the class loader data may be unsafe anonymous.)
792 bool ClassLoaderData::is_platform_class_loader_data() const {
793 return SystemDictionary::is_platform_class_loader(class_loader());
794 }
795
796 // Returns true if the class loader for this class loader data is one of
797 // the 3 builtin (boot application/system or platform) class loaders,
798 // including a user-defined system class loader. Note that if the class
799 // loader data is for an unsafe anonymous class then it may get freed by a GC
800 // even if its class loader is one of these loaders.
801 bool ClassLoaderData::is_builtin_class_loader_data() const {
802 return (is_boot_class_loader_data() ||
803 SystemDictionary::is_system_class_loader(class_loader()) ||
804 SystemDictionary::is_platform_class_loader(class_loader()));
805 }
806
807 // Returns true if this class loader data is a class loader data
808 // that is not ever freed by a GC. It must be the CLD for one of the builtin
809 // class loaders and not the CLD for an unsafe anonymous class.
810 bool ClassLoaderData::is_permanent_class_loader_data() const {
811 return is_builtin_class_loader_data() && !is_unsafe_anonymous();
812 }
813
814 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
815 // If the metaspace has not been allocated, create a new one. Might want
816 // to create smaller arena for Reflection class loaders also.
817 // The reason for the delayed allocation is because some class loaders are
818 // simply for delegating with no metadata of their own.
819 // Lock-free access requires load_acquire.
820 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
821 if (metaspace == NULL) {
822 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
823 // Check if _metaspace got allocated while we were waiting for this lock.
824 if ((metaspace = _metaspace) == NULL) {
825 if (this == the_null_class_loader_data()) {
826 assert (class_loader() == NULL, "Must be");
827 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
828 } else if (is_unsafe_anonymous()) {
829 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::UnsafeAnonymousMetaspaceType);
830 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
831 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
832 } else {
833 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
834 }
835 // Ensure _metaspace is stable, since it is examined without a lock
836 OrderAccess::release_store(&_metaspace, metaspace);
837 }
838 }
839 return metaspace;
840 }
841
842 OopHandle ClassLoaderData::add_handle(Handle h) {
843 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
844 record_modified_oops();
845 return OopHandle(_handles.add(h()));
846 }
847
848 void ClassLoaderData::remove_handle(OopHandle h) {
849 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
850 oop* ptr = h.ptr_raw();
851 if (ptr != NULL) {
852 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
853 NativeAccess<>::oop_store(ptr, oop(NULL));
854 }
855 }
856
857 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
858 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
859 if (dest.resolve() != NULL) {
860 return;
861 } else {
862 dest = _handles.add(h());
863 }
864 }
865
866 // Add this metadata pointer to be freed when it's safe. This is only during
867 // a safepoint which checks if handles point to this metadata field.
868 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
869 // Metadata in shared region isn't deleted.
870 if (!m->is_shared()) {
871 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
872 if (_deallocate_list == NULL) {
873 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
874 }
875 _deallocate_list->append_if_missing(m);
876 log_debug(class, loader, data)("deallocate added for %s", m->print_value_string());
877 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
878 }
879 }
880
881 // Deallocate free metadata on the free list. How useful the PermGen was!
882 void ClassLoaderData::free_deallocate_list() {
883 // Don't need lock, at safepoint
884 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
885 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
886 if (_deallocate_list == NULL) {
887 return;
888 }
889 // Go backwards because this removes entries that are freed.
890 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
891 Metadata* m = _deallocate_list->at(i);
892 if (!m->on_stack()) {
893 _deallocate_list->remove_at(i);
894 // There are only three types of metadata that we deallocate directly.
895 // Cast them so they can be used by the template function.
896 if (m->is_method()) {
897 MetadataFactory::free_metadata(this, (Method*)m);
898 } else if (m->is_constantPool()) {
899 MetadataFactory::free_metadata(this, (ConstantPool*)m);
900 } else if (m->is_klass()) {
901 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
902 } else {
903 ShouldNotReachHere();
904 }
905 } else {
906 // Metadata is alive.
907 // If scratch_class is on stack then it shouldn't be on this list!
908 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
909 "scratch classes on this list should be dead");
910 // Also should assert that other metadata on the list was found in handles.
911 // Some cleaning remains.
912 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
913 }
914 }
915 }
916
917 void ClassLoaderDataGraph::clean_deallocate_lists(bool walk_previous_versions) {
918 assert(SafepointSynchronize::is_at_safepoint(), "must only be called at safepoint");
919 uint loaders_processed = 0;
920 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
921 // is_alive check will be necessary for concurrent class unloading.
922 if (cld->is_alive()) {
923 // clean metaspace
924 if (walk_previous_versions) {
925 cld->classes_do(InstanceKlass::purge_previous_versions);
926 }
927 cld->free_deallocate_list();
928 loaders_processed++;
929 }
930 }
931 log_debug(class, loader, data)("clean_deallocate_lists: loaders processed %u %s",
932 loaders_processed, walk_previous_versions ? "walk_previous_versions" : "");
933 }
934
935 void ClassLoaderDataGraph::walk_metadata_and_clean_metaspaces() {
936 assert(SafepointSynchronize::is_at_safepoint(), "must only be called at safepoint");
937
938 _should_clean_deallocate_lists = false; // assume everything gets cleaned
939
940 // Mark metadata seen on the stack so we can delete unreferenced entries.
941 // Walk all metadata, including the expensive code cache walk, only for class redefinition.
942 // The MetadataOnStackMark walk during redefinition saves previous versions if it finds old methods
943 // on the stack or in the code cache, so we only have to repeat the full walk if
944 // they were found at that time.
945 // TODO: have redefinition clean old methods out of the code cache. They still exist in some places.
946 bool walk_all_metadata = InstanceKlass::has_previous_versions_and_reset();
947
948 MetadataOnStackMark md_on_stack(walk_all_metadata);
949 clean_deallocate_lists(walk_all_metadata);
950 }
951
952 // This is distinct from free_deallocate_list. For class loader data that are
953 // unloading, this frees the C heap memory for items on the list, and unlinks
954 // scratch or error classes so that unloading events aren't triggered for these
955 // classes. The metadata is removed with the unloading metaspace.
956 // There isn't C heap memory allocated for methods, so nothing is done for them.
957 void ClassLoaderData::free_deallocate_list_C_heap_structures() {
958 // Don't need lock, at safepoint
959 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
960 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
961 if (_deallocate_list == NULL) {
962 return;
963 }
964 // Go backwards because this removes entries that are freed.
965 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
966 Metadata* m = _deallocate_list->at(i);
967 _deallocate_list->remove_at(i);
968 if (m->is_constantPool()) {
969 ((ConstantPool*)m)->release_C_heap_structures();
970 } else if (m->is_klass()) {
971 InstanceKlass* ik = (InstanceKlass*)m;
972 // also releases ik->constants() C heap memory
973 InstanceKlass::release_C_heap_structures(ik);
974 // Remove the class so unloading events aren't triggered for
975 // this class (scratch or error class) in do_unloading().
976 remove_class(ik);
977 }
978 }
979 }
980
981 // These CLDs are to contain unsafe anonymous classes used for JSR292
982 ClassLoaderData* ClassLoaderData::unsafe_anonymous_class_loader_data(Handle loader) {
983 // Add a new class loader data to the graph.
984 return ClassLoaderDataGraph::add(loader, true);
985 }
986
987 // Caller needs ResourceMark
988 // If the class loader's _name has not been explicitly set, the class loader's
989 // qualified class name is returned.
990 const char* ClassLoaderData::loader_name() const {
991 if (_class_loader_klass == NULL) {
992 return BOOTSTRAP_LOADER_NAME;
993 } else if (_name != NULL) {
994 return _name->as_C_string();
995 } else {
996 return _class_loader_klass->external_name();
997 }
998 }
999
1000 // Caller needs ResourceMark
1001 // Format of the _name_and_id is as follows:
1002 // If the defining loader has a name explicitly set then '<loader-name>' @<id>
1003 // If the defining loader has no name then <qualified-class-name> @<id>
1004 // If built-in loader, then omit '@<id>' as there is only one instance.
1005 const char* ClassLoaderData::loader_name_and_id() const {
1006 if (_class_loader_klass == NULL) {
1007 return "'" BOOTSTRAP_LOADER_NAME "'";
1008 } else if (_name_and_id != NULL) {
1009 return _name_and_id->as_C_string();
1010 } else {
1011 // May be called in a race before _name_and_id is initialized.
1012 return _class_loader_klass->external_name();
1013 }
1014 }
1015
1016 void ClassLoaderData::print_value_on(outputStream* out) const {
1017 if (!is_unloading() && class_loader() != NULL) {
1018 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
1019 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance
1020 } else {
1021 // loader data: 0xsomeaddr of 'bootstrap'
1022 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
1023 }
1024 if (is_unsafe_anonymous()) {
1025 out->print(" unsafe anonymous");
1026 }
1027 }
1028
1029 #ifndef PRODUCT
1030 void ClassLoaderData::print_on(outputStream* out) const {
1031 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
1032 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id());
1033 if (is_unsafe_anonymous()) out->print(" unsafe anonymous");
1034 if (claimed()) out->print(" claimed");
1035 if (is_unloading()) out->print(" unloading");
1036 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
1037
1038 if (_jmethod_ids != NULL) {
1039 Method::print_jmethod_ids(this, out);
1040 }
1041 out->print(" handles count %d", _handles.count());
1042 out->print(" dependencies %d", _dependency_count);
1043 out->print_cr("}");
1044 }
1045 #endif // PRODUCT
1046
1047 void ClassLoaderData::verify() {
1048 assert_locked_or_safepoint(_metaspace_lock);
1049 oop cl = class_loader();
1050
1051 guarantee(this == class_loader_data(cl) || is_unsafe_anonymous(), "Must be the same");
1052 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_unsafe_anonymous(), "must be");
1053
1054 // Verify the integrity of the allocated space.
1055 if (metaspace_or_null() != NULL) {
1056 metaspace_or_null()->verify();
1057 }
1058
1059 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
1060 guarantee(k->class_loader_data() == this, "Must be the same");
1061 k->verify();
1062 assert(k != k->next_link(), "no loops!");
1063 }
1064 }
1065
1066 bool ClassLoaderData::contains_klass(Klass* klass) {
1067 // Lock-free access requires load_acquire
1068 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
1069 if (k == klass) return true;
1070 }
1071 return false;
1072 }
1073
1074
1075 // GC root of class loader data created.
1076 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
1077 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
1078 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
1079 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
1080
1081 bool ClassLoaderDataGraph::_should_purge = false;
1082 bool ClassLoaderDataGraph::_should_clean_deallocate_lists = false;
1083 bool ClassLoaderDataGraph::_safepoint_cleanup_needed = false;
1084 bool ClassLoaderDataGraph::_metaspace_oom = false;
1085
1086 // Add a new class loader data node to the list. Assign the newly created
1087 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
1088 ClassLoaderData* ClassLoaderDataGraph::add_to_graph(Handle loader, bool is_unsafe_anonymous) {
1089
1090 assert_lock_strong(ClassLoaderDataGraph_lock);
1091
1092 ClassLoaderData* cld;
1093
1094 // First check if another thread beat us to creating the CLD and installing
1095 // it into the loader while we were waiting for the lock.
1096 if (!is_unsafe_anonymous && loader.not_null()) {
1097 cld = java_lang_ClassLoader::loader_data_acquire(loader());
1098 if (cld != NULL) {
1099 return cld;
1100 }
1101 }
1102
1103 // We mustn't GC until we've installed the ClassLoaderData in the Graph since the CLD
1104 // contains oops in _handles that must be walked. GC doesn't walk CLD from the
1105 // loader oop in all collections, particularly young collections.
1106 NoSafepointVerifier no_safepoints;
1107
1108 cld = new ClassLoaderData(loader, is_unsafe_anonymous);
1109
1110 // First install the new CLD to the Graph.
1111 cld->set_next(_head);
1112 _head = cld;
1113
1114 // Next associate with the class_loader.
1115 if (!is_unsafe_anonymous) {
1116 // Use OrderAccess, since readers need to get the loader_data only after
1117 // it's added to the Graph
1118 java_lang_ClassLoader::release_set_loader_data(loader(), cld);
1119 }
1120
1121 // Lastly log, if requested
1122 LogTarget(Trace, class, loader, data) lt;
1123 if (lt.is_enabled()) {
1124 ResourceMark rm;
1125 LogStream ls(lt);
1126 ls.print("create ");
1127 cld->print_value_on(&ls);
1128 ls.cr();
1129 }
1130 return cld;
1131 }
1132
1133 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_unsafe_anonymous) {
1134 MutexLocker ml(ClassLoaderDataGraph_lock);
1135 ClassLoaderData* loader_data = add_to_graph(loader, is_unsafe_anonymous);
1136 return loader_data;
1137 }
1138
1139 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
1140 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1141 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1142 cl->do_cld(cld);
1143 }
1144 }
1145
1146 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
1147 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1148 // Only walk the head until any clds not purged from prior unloading
1149 // (CMS doesn't purge right away).
1150 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1151 assert(cld->is_unloading(), "invariant");
1152 cl->do_cld(cld);
1153 }
1154 }
1155
1156 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
1157 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1158 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
1159 CLDClosure* closure = cld->keep_alive() ? strong : weak;
1160 if (closure != NULL) {
1161 closure->do_cld(cld);
1162 }
1163 }
1164 }
1165
1166 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
1167 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1168 if (ClassUnloading) {
1169 roots_cld_do(cl, NULL);
1170 } else {
1171 cld_do(cl);
1172 }
1173 }
1174
1175 // Closure for locking and iterating through classes.
1176 LockedClassesDo::LockedClassesDo(classes_do_func_t f) : _function(f) {
1177 ClassLoaderDataGraph_lock->lock();
1178 }
1179
1180 LockedClassesDo::LockedClassesDo() : _function(NULL) {
1181 // callers provide their own do_klass
1182 ClassLoaderDataGraph_lock->lock();
1183 }
1184
1185 LockedClassesDo::~LockedClassesDo() { ClassLoaderDataGraph_lock->unlock(); }
1186
1187
1188 // Iterating over the CLDG needs to be locked because
1189 // unloading can remove entries concurrently soon.
1190 class ClassLoaderDataGraphIterator : public StackObj {
1191 ClassLoaderData* _next;
1192 HandleMark _hm; // clean up handles when this is done.
1193 Handle _holder;
1194 Thread* _thread;
1195
1196 void hold_next() {
1197 if (_next != NULL) {
1198 _holder = Handle(_thread, _next->holder_phantom());
1199 }
1200 }
1201 public:
1202 ClassLoaderDataGraphIterator() : _next(ClassLoaderDataGraph::_head) {
1203 _thread = Thread::current();
1204 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1205 hold_next();
1206 }
1207
1208 bool repeat() const {
1209 return _next != NULL;
1210 }
1211
1212 ClassLoaderData* get_next() {
1213 ClassLoaderData* next = _next;
1214 if (_next != NULL) {
1215 _next = _next->next();
1216 hold_next();
1217 }
1218 return next;
1219 }
1220 };
1221
1222 // These functions assume that the caller has locked the ClassLoaderDataGraph_lock
1223 // if they are not calling the function from a safepoint.
1224 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
1225 ClassLoaderDataGraphIterator iter;
1226 while (iter.repeat()) {
1227 ClassLoaderData* cld = iter.get_next();
1228 cld->classes_do(klass_closure);
1229 }
1230 }
1231
1232 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
1233 ClassLoaderDataGraphIterator iter;
1234 while (iter.repeat()) {
1235 ClassLoaderData* cld = iter.get_next();
1236 cld->classes_do(f);
1237 }
1238 }
1239
1240 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
1241 ClassLoaderDataGraphIterator iter;
1242 while (iter.repeat()) {
1243 ClassLoaderData* cld = iter.get_next();
1244 cld->methods_do(f);
1245 }
1246 }
1247
1248 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
1249 assert_locked_or_safepoint(Module_lock);
1250 ClassLoaderDataGraphIterator iter;
1251 while (iter.repeat()) {
1252 ClassLoaderData* cld = iter.get_next();
1253 cld->modules_do(f);
1254 }
1255 }
1256
1257 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
1258 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1259 // Only walk the head until any clds not purged from prior unloading
1260 // (CMS doesn't purge right away).
1261 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1262 assert(cld->is_unloading(), "invariant");
1263 cld->modules_do(f);
1264 }
1265 }
1266
1267 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
1268 assert_locked_or_safepoint(Module_lock);
1269 ClassLoaderDataGraphIterator iter;
1270 while (iter.repeat()) {
1271 ClassLoaderData* cld = iter.get_next();
1272 cld->packages_do(f);
1273 }
1274 }
1275
1276 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
1277 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1278 // Only walk the head until any clds not purged from prior unloading
1279 // (CMS doesn't purge right away).
1280 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1281 assert(cld->is_unloading(), "invariant");
1282 cld->packages_do(f);
1283 }
1284 }
1285
1286 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
1287 ClassLoaderDataGraphIterator iter;
1288 while (iter.repeat()) {
1289 ClassLoaderData* cld = iter.get_next();
1290 cld->loaded_classes_do(klass_closure);
1291 }
1292 }
1293
1294 // This case can block but cannot do unloading (called from CDS)
1295 void ClassLoaderDataGraph::unlocked_loaded_classes_do(KlassClosure* klass_closure) {
1296 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
1297 cld->loaded_classes_do(klass_closure);
1298 }
1299 }
1300
1301
1302 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
1303 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1304 // Only walk the head until any clds not purged from prior unloading
1305 // (CMS doesn't purge right away).
1306 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
1307 assert(cld->is_unloading(), "invariant");
1308 cld->classes_do(f);
1309 }
1310 }
1311
1312 #define FOR_ALL_DICTIONARY(X) ClassLoaderDataGraphIterator iter; \
1313 ClassLoaderData* X; \
1314 while ((X = iter.get_next()) != NULL) \
1315 if (X->dictionary() != NULL)
1316
1317 // Walk classes in the loaded class dictionaries in various forms.
1318 // Only walks the classes defined in this class loader.
1319 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*)) {
1320 FOR_ALL_DICTIONARY(cld) {
1321 cld->dictionary()->classes_do(f);
1322 }
1323 }
1324
1325 // Only walks the classes defined in this class loader.
1326 void ClassLoaderDataGraph::dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {
1327 FOR_ALL_DICTIONARY(cld) {
1328 cld->dictionary()->classes_do(f, CHECK);
1329 }
1330 }
1331
1332 void ClassLoaderDataGraph::verify_dictionary() {
1333 FOR_ALL_DICTIONARY(cld) {
1334 cld->dictionary()->verify();
1335 }
1336 }
1337
1338 void ClassLoaderDataGraph::print_dictionary(outputStream* st) {
1339 FOR_ALL_DICTIONARY(cld) {
1340 st->print("Dictionary for ");
1341 cld->print_value_on(st);
1342 st->cr();
1343 cld->dictionary()->print_on(st);
1344 st->cr();
1345 }
1346 }
1347
1348 void ClassLoaderDataGraph::print_dictionary_statistics(outputStream* st) {
1349 FOR_ALL_DICTIONARY(cld) {
1350 ResourceMark rm;
1351 stringStream tempst;
1352 tempst.print("System Dictionary for %s class loader", cld->loader_name_and_id());
1353 cld->dictionary()->print_table_statistics(st, tempst.as_string());
1354 }
1355 }
1356
1357 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
1358 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1359 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
1360
1361 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
1362
1363 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
1364 ClassLoaderData* curr = _head;
1365 while (curr != _saved_head) {
1366 if (!curr->claimed()) {
1367 array->push(curr);
1368 LogTarget(Debug, class, loader, data) lt;
1369 if (lt.is_enabled()) {
1370 LogStream ls(lt);
1371 ls.print("found new CLD: ");
1372 curr->print_value_on(&ls);
1373 ls.cr();
1374 }
1375 }
1376
1377 curr = curr->_next;
1378 }
1379
1380 return array;
1381 }
1382
1383 #ifndef PRODUCT
1384 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
1385 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1386 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1387 if (loader_data == data) {
1388 return true;
1389 }
1390 }
1391
1392 return false;
1393 }
1394 #endif // PRODUCT
1395
1396 // Move class loader data from main list to the unloaded list for unloading
1397 // and deallocation later.
1398 bool ClassLoaderDataGraph::do_unloading(bool do_cleaning) {
1399 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1400
1401 // Indicate whether safepoint cleanup is needed.
1402 _safepoint_cleanup_needed |= do_cleaning;
1403
1404 ClassLoaderData* data = _head;
1405 ClassLoaderData* prev = NULL;
1406 bool seen_dead_loader = false;
1407 uint loaders_processed = 0;
1408 uint loaders_removed = 0;
1409
1410 // Save previous _unloading pointer for CMS which may add to unloading list before
1411 // purging and we don't want to rewalk the previously unloaded class loader data.
1412 _saved_unloading = _unloading;
1413
1414 data = _head;
1415 while (data != NULL) {
1416 if (data->is_alive()) {
1417 prev = data;
1418 data = data->next();
1419 loaders_processed++;
1420 continue;
1421 }
1422 seen_dead_loader = true;
1423 loaders_removed++;
1424 ClassLoaderData* dead = data;
1425 dead->unload();
1426 data = data->next();
1427 // Remove from loader list.
1428 // This class loader data will no longer be found
1429 // in the ClassLoaderDataGraph.
1430 if (prev != NULL) {
1431 prev->set_next(data);
1432 } else {
1433 assert(dead == _head, "sanity check");
1434 _head = data;
1435 }
1436 dead->set_next(_unloading);
1437 _unloading = dead;
1438 }
1439
1440 log_debug(class, loader, data)("do_unloading: loaders processed %u, loaders removed %u", loaders_processed, loaders_removed);
1441
1442 return seen_dead_loader;
1443 }
1444
1445 // There's at least one dead class loader. Purge refererences of healthy module
1446 // reads lists and package export lists to modules belonging to dead loaders.
1447 void ClassLoaderDataGraph::clean_module_and_package_info() {
1448 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
1449
1450 ClassLoaderData* data = _head;
1451 while (data != NULL) {
1452 // Remove entries in the dictionary of live class loader that have
1453 // initiated loading classes in a dead class loader.
1454 if (data->dictionary() != NULL) {
1455 data->dictionary()->do_unloading();
1456 }
1457 // Walk a ModuleEntry's reads, and a PackageEntry's exports
1458 // lists to determine if there are modules on those lists that are now
1459 // dead and should be removed. A module's life cycle is equivalent
1460 // to its defining class loader's life cycle. Since a module is
1461 // considered dead if its class loader is dead, these walks must
1462 // occur after each class loader's aliveness is determined.
1463 if (data->packages() != NULL) {
1464 data->packages()->purge_all_package_exports();
1465 }
1466 if (data->modules_defined()) {
1467 data->modules()->purge_all_module_reads();
1468 }
1469 data = data->next();
1470 }
1471 }
1472
1473 void ClassLoaderDataGraph::purge() {
1474 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1475 ClassLoaderData* list = _unloading;
1476 _unloading = NULL;
1477 ClassLoaderData* next = list;
1478 bool classes_unloaded = false;
1479 while (next != NULL) {
1480 ClassLoaderData* purge_me = next;
1481 next = purge_me->next();
1482 delete purge_me;
1483 classes_unloaded = true;
1484 }
1485 if (classes_unloaded) {
1486 Metaspace::purge();
1487 set_metaspace_oom(false);
1488 }
1489 }
1490
1491 int ClassLoaderDataGraph::resize_if_needed() {
1492 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1493 int resized = 0;
1494 if (Dictionary::does_any_dictionary_needs_resizing()) {
1495 FOR_ALL_DICTIONARY(cld) {
1496 if (cld->dictionary()->resize_if_needed()) {
1497 resized++;
1498 }
1499 }
1500 }
1501 return resized;
1502 }
1503
1504 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1505 : _next_klass(NULL) {
1506 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1507 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1508 Klass* klass = NULL;
1509
1510 // Find the first klass in the CLDG.
1511 while (cld != NULL) {
1512 assert_locked_or_safepoint(cld->metaspace_lock());
1513 klass = cld->_klasses;
1514 if (klass != NULL) {
1515 _next_klass = klass;
1516 return;
1517 }
1518 cld = cld->next();
1519 }
1520 }
1521
1522 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1523 Klass* next = klass->next_link();
1524 if (next != NULL) {
1525 return next;
1526 }
1527
1528 // No more klasses in the current CLD. Time to find a new CLD.
1529 ClassLoaderData* cld = klass->class_loader_data();
1530 assert_locked_or_safepoint(cld->metaspace_lock());
1531 while (next == NULL) {
1532 cld = cld->next();
1533 if (cld == NULL) {
1534 break;
1535 }
1536 next = cld->_klasses;
1537 }
1538
1539 return next;
1540 }
1541
1542 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1543 Klass* head = _next_klass;
1544
1545 while (head != NULL) {
1546 Klass* next = next_klass_in_cldg(head);
1547
1548 Klass* old_head = Atomic::cmpxchg(next, &_next_klass, head);
1549
1550 if (old_head == head) {
1551 return head; // Won the CAS.
1552 }
1553
1554 head = old_head;
1555 }
1556
1557 // Nothing more for the iterator to hand out.
1558 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1559 return NULL;
1560 }
1561
1562 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1563 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1564 _data = ClassLoaderDataGraph::_head;
1565 }
1566
1567 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1568
1569 #ifndef PRODUCT
1570 // callable from debugger
1571 extern "C" int print_loader_data_graph() {
1572 ResourceMark rm;
1573 ClassLoaderDataGraph::print_on(tty);
1574 return 0;
1575 }
1576
1577 void ClassLoaderDataGraph::verify() {
1578 ClassLoaderDataGraphIterator iter;
1579 while (iter.repeat()) {
1580 ClassLoaderData* cld = iter.get_next();
1581 cld->verify();
1582 }
1583 }
1584
1585 void ClassLoaderDataGraph::print_on(outputStream * const out) {
1586 ClassLoaderDataGraphIterator iter;
1587 while (iter.repeat()) {
1588 ClassLoaderData* cld = iter.get_next();
1589 cld->print_on(out);
1590 }
1591 }
1592 #endif // PRODUCT