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