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