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