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