1 /*
2 * Copyright (c) 2012, 2019, 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.inline.hpp"
51#include "classfile/classLoaderDataGraph.inline.hpp"
52#include "classfile/dictionary.hpp"
53#include "classfile/javaClasses.hpp"
54#include "classfile/moduleEntry.hpp"
55#include "classfile/packageEntry.hpp"
56#include "classfile/symbolTable.hpp"
57#include "classfile/systemDictionary.hpp"
58#include "logging/log.hpp"
59#include "logging/logStream.hpp"
60#include "memory/allocation.inline.hpp"
61#include "memory/metadataFactory.hpp"
62#include "memory/resourceArea.hpp"
63#include "oops/access.inline.hpp"
64#include "oops/oop.inline.hpp"
65#include "oops/oopHandle.inline.hpp"
66#include "oops/weakHandle.inline.hpp"
67#include "runtime/atomic.hpp"
68#include "runtime/handles.inline.hpp"
69#include "runtime/mutex.hpp"
70#include "runtime/orderAccess.hpp"
71#include "runtime/safepoint.hpp"
72#include "utilities/growableArray.hpp"
73#include "utilities/macros.hpp"
74#include "utilities/ostream.hpp"
75
76ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
77
78void ClassLoaderData::init_null_class_loader_data() {
79 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
80 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
81
82 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
83 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
84 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
85
86 LogTarget(Trace, class, loader, data) lt;
87 if (lt.is_enabled()) {
88 ResourceMark rm;
89 LogStream ls(lt);
90 ls.print("create ");
91 _the_null_class_loader_data->print_value_on(&ls);
92 ls.cr();
93 }
94}
95
96// Obtain and set the class loader's name within the ClassLoaderData so
97// it will be available for error messages, logging, JFR, etc. The name
98// and klass are available after the class_loader oop is no longer alive,
99// during unloading.
100void ClassLoaderData::initialize_name(Handle class_loader) {
101 Thread* THREAD = Thread::current();
102 ResourceMark rm(THREAD);
103
104 // Obtain the class loader's name. If the class loader's name was not
105 // explicitly set during construction, the CLD's _name field will be null.
106 oop cl_name = java_lang_ClassLoader::name(class_loader());
107 if (cl_name != NULL) {
108 const char* cl_instance_name = java_lang_String::as_utf8_string(cl_name);
109
110 if (cl_instance_name != NULL && cl_instance_name[0] != '\0') {
111 _name = SymbolTable::new_symbol(cl_instance_name);
112 }
113 }
114
115 // Obtain the class loader's name and identity hash. If the class loader's
116 // name was not explicitly set during construction, the class loader's name and id
117 // will be set to the qualified class name of the class loader along with its
118 // identity hash.
119 // If for some reason the ClassLoader's constructor has not been run, instead of
120 // leaving the _name_and_id field null, fall back to the external qualified class
121 // name. Thus CLD's _name_and_id field should never have a null value.
122 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader());
123 const char* cl_instance_name_and_id =
124 (cl_name_and_id == NULL) ? _class_loader_klass->external_name() :
125 java_lang_String::as_utf8_string(cl_name_and_id);
126 assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id");
127 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id);
128}
129
130ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_unsafe_anonymous) :
131 _metaspace(NULL),
132 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
133 Monitor::_safepoint_check_never)),
134 _unloading(false), _is_unsafe_anonymous(is_unsafe_anonymous),
135 _modified_oops(true), _accumulated_modified_oops(false),
136 // An unsafe anonymous class loader data doesn't have anything to keep
137 // it from being unloaded during parsing of the unsafe anonymous class.
138 // The null-class-loader should always be kept alive.
139 _keep_alive((is_unsafe_anonymous || h_class_loader.is_null()) ? 1 : 0),
140 _claim(0),
141 _handles(),
142 _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL),
143 _jmethod_ids(NULL),
144 _deallocate_list(NULL),
145 _next(NULL),
146 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL) {
147
148 if (!h_class_loader.is_null()) {
149 _class_loader = _handles.add(h_class_loader());
150 _class_loader_klass = h_class_loader->klass();
151 initialize_name(h_class_loader);
152 }
153
154 if (!is_unsafe_anonymous) {
155 // The holder is initialized later for unsafe anonymous classes, and before calling anything
156 // that call class_loader().
157 initialize_holder(h_class_loader);
158
159 // A ClassLoaderData created solely for an unsafe anonymous class should never have a
160 // ModuleEntryTable or PackageEntryTable created for it. The defining package
161 // and module for an unsafe anonymous class will be found in its host class.
162 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
163 if (h_class_loader.is_null()) {
164 // Create unnamed module for boot loader
165 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
166 } else {
167 // Create unnamed module for all other loaders
168 _unnamed_module = ModuleEntry::create_unnamed_module(this);
169 }
170 _dictionary = create_dictionary();
171 }
172
173 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
174
175 JFR_ONLY(INIT_ID(this);)
176}
177
178ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
179 Chunk* c = _head;
180 while (c != NULL) {
181 Chunk* next = c->_next;
182 delete c;
183 c = next;
184 }
185}
186
187oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
188 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
189 Chunk* next = new Chunk(_head);
190 OrderAccess::release_store(&_head, next);
191 }
192 oop* handle = &_head->_data[_head->_size];
193 NativeAccess<IS_DEST_UNINITIALIZED>::oop_store(handle, o);
194 OrderAccess::release_store(&_head->_size, _head->_size + 1);
195 return handle;
196}
197
198int ClassLoaderData::ChunkedHandleList::count() const {
199 int count = 0;
200 Chunk* chunk = _head;
201 while (chunk != NULL) {
202 count += chunk->_size;
203 chunk = chunk->_next;
204 }
205 return count;
206}
207
208inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
209 for (juint i = 0; i < size; i++) {
210 if (c->_data[i] != NULL) {
211 f->do_oop(&c->_data[i]);
212 }
213 }
214}
215
216void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
217 Chunk* head = OrderAccess::load_acquire(&_head);
218 if (head != NULL) {
219 // Must be careful when reading size of head
220 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
221 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
222 oops_do_chunk(f, c, c->_size);
223 }
224 }
225}
226
227class VerifyContainsOopClosure : public OopClosure {
228 oop _target;
229 bool _found;
230
231 public:
232 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
233
234 void do_oop(oop* p) {
235 if (p != NULL && oopDesc::equals(NativeAccess<AS_NO_KEEPALIVE>::oop_load(p), _target)) {
236 _found = true;
237 }
238 }
239
240 void do_oop(narrowOop* p) {
241 // The ChunkedHandleList should not contain any narrowOop
242 ShouldNotReachHere();
243 }
244
245 bool found() const {
246 return _found;
247 }
248};
249
250bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
251 VerifyContainsOopClosure cl(p);
252 oops_do(&cl);
253 return cl.found();
254}
255
256#ifndef PRODUCT
257bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
258 Chunk* chunk = _head;
259 while (chunk != NULL) {
260 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
261 return true;
262 }
263 chunk = chunk->_next;
264 }
265 return false;
266}
267#endif // PRODUCT
268
269void ClassLoaderData::clear_claim(int claim) {
270 for (;;) {
271 int old_claim = Atomic::load(&_claim);
272 if ((old_claim & claim) == 0) {
273 return;
274 }
275 int new_claim = old_claim & ~claim;
276 if (Atomic::cmpxchg(new_claim, &_claim, old_claim) == old_claim) {
277 return;
278 }
279 }
280}
281
282bool ClassLoaderData::try_claim(int claim) {
283 for (;;) {
284 int old_claim = Atomic::load(&_claim);
285 if ((old_claim & claim) == claim) {
286 return false;
287 }
288 int new_claim = old_claim | claim;
289 if (Atomic::cmpxchg(new_claim, &_claim, old_claim) == old_claim) {
290 return true;
291 }
292 }
293}
294
295// Unsafe anonymous classes have their own ClassLoaderData that is marked to keep alive
296// while the class is being parsed, and if the class appears on the module fixup list.
297// Due to the uniqueness that no other class shares the unsafe anonymous class' name or
298// ClassLoaderData, no other non-GC thread has knowledge of the unsafe anonymous class while
299// it is being defined, therefore _keep_alive is not volatile or atomic.
300void ClassLoaderData::inc_keep_alive() {
301 if (is_unsafe_anonymous()) {
302 assert(_keep_alive > 0, "Invalid keep alive increment count");
303 _keep_alive++;
304 }
305}
306
307void ClassLoaderData::dec_keep_alive() {
308 if (is_unsafe_anonymous()) {
309 assert(_keep_alive > 0, "Invalid keep alive decrement count");
310 _keep_alive--;
311 }
312}
313
314void ClassLoaderData::oops_do(OopClosure* f, int claim_value, bool clear_mod_oops) {
315 if (claim_value != ClassLoaderData::_claim_none && !try_claim(claim_value)) {
316 return;
317 }
318
319 // Only clear modified_oops after the ClassLoaderData is claimed.
320 if (clear_mod_oops) {
321 clear_modified_oops();
322 }
323
324 _handles.oops_do(f);
325}
326
327void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
328 // Lock-free access requires load_acquire
329 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
330 klass_closure->do_klass(k);
331 assert(k != k->next_link(), "no loops!");
332 }
333}
334
335void ClassLoaderData::classes_do(void f(Klass * const)) {
336 // Lock-free access requires load_acquire
337 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
338 f(k);
339 assert(k != k->next_link(), "no loops!");
340 }
341}
342
343void ClassLoaderData::methods_do(void f(Method*)) {
344 // Lock-free access requires load_acquire
345 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
346 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
347 InstanceKlass::cast(k)->methods_do(f);
348 }
349 }
350}
351
352void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
353 // Lock-free access requires load_acquire
354 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
355 // Do not filter ArrayKlass oops here...
356 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
357#ifdef ASSERT
358 oop m = k->java_mirror();
359 assert(m != NULL, "NULL mirror");
360 assert(m->is_a(SystemDictionary::Class_klass()), "invalid mirror");
361#endif
362 klass_closure->do_klass(k);
363 }
364 }
365}
366
367void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
368 // Lock-free access requires load_acquire
369 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
370 if (k->is_instance_klass()) {
371 f(InstanceKlass::cast(k));
372 }
373 assert(k != k->next_link(), "no loops!");
374 }
375}
376
377void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
378 assert_locked_or_safepoint(Module_lock);
379 if (_unnamed_module != NULL) {
380 f(_unnamed_module);
381 }
382 if (_modules != NULL) {
383 for (int i = 0; i < _modules->table_size(); i++) {
384 for (ModuleEntry* entry = _modules->bucket(i);
385 entry != NULL;
386 entry = entry->next()) {
387 f(entry);
388 }
389 }
390 }
391}
392
393void ClassLoaderData::packages_do(void f(PackageEntry*)) {
394 assert_locked_or_safepoint(Module_lock);
395 if (_packages != NULL) {
396 for (int i = 0; i < _packages->table_size(); i++) {
397 for (PackageEntry* entry = _packages->bucket(i);
398 entry != NULL;
399 entry = entry->next()) {
400 f(entry);
401 }
402 }
403 }
404}
405
406void ClassLoaderData::record_dependency(const Klass* k) {
407 assert(k != NULL, "invariant");
408
409 ClassLoaderData * const from_cld = this;
410 ClassLoaderData * const to_cld = k->class_loader_data();
411
412 // Do not need to record dependency if the dependency is to a class whose
413 // class loader data is never freed. (i.e. the dependency's class loader
414 // is one of the three builtin class loaders and the dependency is not
415 // unsafe anonymous.)
416 if (to_cld->is_permanent_class_loader_data()) {
417 return;
418 }
419
420 oop to;
421 if (to_cld->is_unsafe_anonymous()) {
422 // Just return if an unsafe anonymous class is attempting to record a dependency
423 // to itself. (Note that every unsafe anonymous class has its own unique class
424 // loader data.)
425 if (to_cld == from_cld) {
426 return;
427 }
428 // Unsafe anonymous class dependencies are through the mirror.
429 to = k->java_mirror();
430 } else {
431 to = to_cld->class_loader();
432 oop from = from_cld->class_loader();
433
434 // Just return if this dependency is to a class with the same or a parent
435 // class_loader.
436 if (oopDesc::equals(from, to) || java_lang_ClassLoader::isAncestor(from, to)) {
437 return; // this class loader is in the parent list, no need to add it.
438 }
439 }
440
441 // It's a dependency we won't find through GC, add it.
442 if (!_handles.contains(to)) {
443 NOT_PRODUCT(Atomic::inc(&_dependency_count));
444 LogTarget(Trace, class, loader, data) lt;
445 if (lt.is_enabled()) {
446 ResourceMark rm;
447 LogStream ls(lt);
448 ls.print("adding dependency from ");
449 print_value_on(&ls);
450 ls.print(" to ");
451 to_cld->print_value_on(&ls);
452 ls.cr();
453 }
454 Handle dependency(Thread::current(), to);
455 add_handle(dependency);
456 // Added a potentially young gen oop to the ClassLoaderData
457 record_modified_oops();
458 }
459}
460
461void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
462 {
463 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
464 Klass* old_value = _klasses;
465 k->set_next_link(old_value);
466 // Link the new item into the list, making sure the linked class is stable
467 // since the list can be walked without a lock
468 OrderAccess::release_store(&_klasses, k);
469 if (k->is_array_klass()) {
470 ClassLoaderDataGraph::inc_array_classes(1);
471 } else {
472 ClassLoaderDataGraph::inc_instance_classes(1);
473 }
474 }
475
476 if (publicize) {
477 LogTarget(Trace, class, loader, data) lt;
478 if (lt.is_enabled()) {
479 ResourceMark rm;
480 LogStream ls(lt);
481 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
482 print_value_on(&ls);
483 ls.cr();
484 }
485 }
486}
487
488void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
489 if (loader_or_mirror() != NULL) {
490 assert(_holder.is_null(), "never replace holders");
491 _holder = WeakHandle<vm_class_loader_data>::create(loader_or_mirror);
492 }
493}
494
495// Remove a klass from the _klasses list for scratch_class during redefinition
496// or parsed class in the case of an error.
497void ClassLoaderData::remove_class(Klass* scratch_class) {
498 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
499
500 // Adjust global class iterator.
501 ClassLoaderDataGraph::adjust_saved_class(scratch_class);
502
503 Klass* prev = NULL;
504 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
505 if (k == scratch_class) {
506 if (prev == NULL) {
507 _klasses = k->next_link();
508 } else {
509 Klass* next = k->next_link();
510 prev->set_next_link(next);
511 }
512
513 if (k->is_array_klass()) {
514 ClassLoaderDataGraph::dec_array_classes(1);
515 } else {
516 ClassLoaderDataGraph::dec_instance_classes(1);
517 }
518
519 return;
520 }
521 prev = k;
522 assert(k != k->next_link(), "no loops!");
523 }
524 ShouldNotReachHere(); // should have found this class!!
525}
526
527void ClassLoaderData::unload() {
528 _unloading = true;
529
530 LogTarget(Trace, class, loader, data) lt;
531 if (lt.is_enabled()) {
532 ResourceMark rm;
533 LogStream ls(lt);
534 ls.print("unload");
535 print_value_on(&ls);
536 ls.cr();
537 }
538
539 // Some items on the _deallocate_list need to free their C heap structures
540 // if they are not already on the _klasses list.
541 free_deallocate_list_C_heap_structures();
542
543 // Clean up class dependencies and tell serviceability tools
544 // these classes are unloading. Must be called
545 // after erroneous classes are released.
546 classes_do(InstanceKlass::unload_class);
547
548 // Clean up global class iterator for compiler
549 ClassLoaderDataGraph::adjust_saved_class(this);
550}
551
552ModuleEntryTable* ClassLoaderData::modules() {
553 // Lazily create the module entry table at first request.
554 // Lock-free access requires load_acquire.
555 ModuleEntryTable* modules = OrderAccess::load_acquire(&_modules);
556 if (modules == NULL) {
557 MutexLocker m1(Module_lock);
558 // Check if _modules got allocated while we were waiting for this lock.
559 if ((modules = _modules) == NULL) {
560 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
561
562 {
563 MutexLocker m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
564 // Ensure _modules is stable, since it is examined without a lock
565 OrderAccess::release_store(&_modules, modules);
566 }
567 }
568 }
569 return modules;
570}
571
572const int _boot_loader_dictionary_size = 1009;
573const int _default_loader_dictionary_size = 107;
574
575Dictionary* ClassLoaderData::create_dictionary() {
576 assert(!is_unsafe_anonymous(), "unsafe anonymous class loader data do not have a dictionary");
577 int size;
578 bool resizable = false;
579 if (_the_null_class_loader_data == NULL) {
580 size = _boot_loader_dictionary_size;
581 resizable = true;
582 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
583 size = 1; // there's only one class in relection class loader and no initiated classes
584 } else if (is_system_class_loader_data()) {
585 size = _boot_loader_dictionary_size;
586 resizable = true;
587 } else {
588 size = _default_loader_dictionary_size;
589 resizable = true;
590 }
591 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) {
592 resizable = false;
593 }
594 return new Dictionary(this, size, resizable);
595}
596
597// Tell the GC to keep this klass alive while iterating ClassLoaderDataGraph
598oop ClassLoaderData::holder_phantom() const {
599 // A klass that was previously considered dead can be looked up in the
600 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
601 // or a reachable object making it alive again. The SATB part of G1 needs
602 // to get notified about this potential resurrection, otherwise the marking
603 // might not find the object.
604 if (!_holder.is_null()) { // NULL class_loader
605 return _holder.resolve();
606 } else {
607 return NULL;
608 }
609}
610
611// Let the GC read the holder without keeping it alive.
612oop ClassLoaderData::holder_no_keepalive() const {
613 if (!_holder.is_null()) { // NULL class_loader
614 return _holder.peek();
615 } else {
616 return NULL;
617 }
618}
619
620// Unloading support
621bool ClassLoaderData::is_alive() const {
622 bool alive = keep_alive() // null class loader and incomplete unsafe anonymous klasses.
623 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
624
625 return alive;
626}
627
628class ReleaseKlassClosure: public KlassClosure {
629private:
630 size_t _instance_class_released;
631 size_t _array_class_released;
632public:
633 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
634
635 size_t instance_class_released() const { return _instance_class_released; }
636 size_t array_class_released() const { return _array_class_released; }
637
638 void do_klass(Klass* k) {
639 if (k->is_array_klass()) {
640 _array_class_released ++;
641 } else {
642 assert(k->is_instance_klass(), "Must be");
643 _instance_class_released ++;
644 InstanceKlass::release_C_heap_structures(InstanceKlass::cast(k));
645 }
646 }
647};
648
649ClassLoaderData::~ClassLoaderData() {
650 // Release C heap structures for all the classes.
651 ReleaseKlassClosure cl;
652 classes_do(&cl);
653
654 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
655 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
656
657 // Release the WeakHandle
658 _holder.release();
659
660 // Release C heap allocated hashtable for all the packages.
661 if (_packages != NULL) {
662 // Destroy the table itself
663 delete _packages;
664 _packages = NULL;
665 }
666
667 // Release C heap allocated hashtable for all the modules.
668 if (_modules != NULL) {
669 // Destroy the table itself
670 delete _modules;
671 _modules = NULL;
672 }
673
674 // Release C heap allocated hashtable for the dictionary
675 if (_dictionary != NULL) {
676 // Destroy the table itself
677 delete _dictionary;
678 _dictionary = NULL;
679 }
680
681 if (_unnamed_module != NULL) {
682 _unnamed_module->delete_unnamed_module();
683 _unnamed_module = NULL;
684 }
685
686 // release the metaspace
687 ClassLoaderMetaspace *m = _metaspace;
688 if (m != NULL) {
689 _metaspace = NULL;
690 delete m;
691 }
692 // Clear all the JNI handles for methods
693 // These aren't deallocated and are going to look like a leak, but that's
694 // needed because we can't really get rid of jmethodIDs because we don't
695 // know when native code is going to stop using them. The spec says that
696 // they're "invalid" but existing programs likely rely on their being
697 // NULL after class unloading.
698 if (_jmethod_ids != NULL) {
699 Method::clear_jmethod_ids(this);
700 }
701 // Delete lock
702 delete _metaspace_lock;
703
704 // Delete free list
705 if (_deallocate_list != NULL) {
706 delete _deallocate_list;
707 }
708
709 // Decrement refcounts of Symbols if created.
710 if (_name != NULL) {
711 _name->decrement_refcount();
712 }
713 if (_name_and_id != NULL) {
714 _name_and_id->decrement_refcount();
715 }
716}
717
718// Returns true if this class loader data is for the app class loader
719// or a user defined system class loader. (Note that the class loader
720// data may be unsafe anonymous.)
721bool ClassLoaderData::is_system_class_loader_data() const {
722 return SystemDictionary::is_system_class_loader(class_loader());
723}
724
725// Returns true if this class loader data is for the platform class loader.
726// (Note that the class loader data may be unsafe anonymous.)
727bool ClassLoaderData::is_platform_class_loader_data() const {
728 return SystemDictionary::is_platform_class_loader(class_loader());
729}
730
731// Returns true if the class loader for this class loader data is one of
732// the 3 builtin (boot application/system or platform) class loaders,
733// including a user-defined system class loader. Note that if the class
734// loader data is for an unsafe anonymous class then it may get freed by a GC
735// even if its class loader is one of these loaders.
736bool ClassLoaderData::is_builtin_class_loader_data() const {
737 return (is_boot_class_loader_data() ||
738 SystemDictionary::is_system_class_loader(class_loader()) ||
739 SystemDictionary::is_platform_class_loader(class_loader()));
740}
741
742// Returns true if this class loader data is a class loader data
743// that is not ever freed by a GC. It must be the CLD for one of the builtin
744// class loaders and not the CLD for an unsafe anonymous class.
745bool ClassLoaderData::is_permanent_class_loader_data() const {
746 return is_builtin_class_loader_data() && !is_unsafe_anonymous();
747}
748
749ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
750 // If the metaspace has not been allocated, create a new one. Might want
751 // to create smaller arena for Reflection class loaders also.
752 // The reason for the delayed allocation is because some class loaders are
753 // simply for delegating with no metadata of their own.
754 // Lock-free access requires load_acquire.
755 ClassLoaderMetaspace* metaspace = OrderAccess::load_acquire(&_metaspace);
756 if (metaspace == NULL) {
757 MutexLocker ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
758 // Check if _metaspace got allocated while we were waiting for this lock.
759 if ((metaspace = _metaspace) == NULL) {
760 if (this == the_null_class_loader_data()) {
761 assert (class_loader() == NULL, "Must be");
762 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
763 } else if (is_unsafe_anonymous()) {
764 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::UnsafeAnonymousMetaspaceType);
765 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
766 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
767 } else {
768 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
769 }
770 // Ensure _metaspace is stable, since it is examined without a lock
771 OrderAccess::release_store(&_metaspace, metaspace);
772 }
773 }
774 return metaspace;
775}
776
777OopHandle ClassLoaderData::add_handle(Handle h) {
778 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
779 record_modified_oops();
780 return OopHandle(_handles.add(h()));
781}
782
783void ClassLoaderData::remove_handle(OopHandle h) {
784 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
785 oop* ptr = h.ptr_raw();
786 if (ptr != NULL) {
787 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
788 NativeAccess<>::oop_store(ptr, oop(NULL));
789 }
790}
791
792void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
793 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
794 if (dest.resolve() != NULL) {
795 return;
796 } else {
797 dest = _handles.add(h());
798 }
799}
800
801// Add this metadata pointer to be freed when it's safe. This is only during
802// a safepoint which checks if handles point to this metadata field.
803void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
804 // Metadata in shared region isn't deleted.
805 if (!m->is_shared()) {
806 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
807 if (_deallocate_list == NULL) {
808 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
809 }
810 _deallocate_list->append_if_missing(m);
811 log_debug(class, loader, data)("deallocate added for %s", m->print_value_string());
812 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
813 }
814}
815
816// Deallocate free metadata on the free list. How useful the PermGen was!
817void ClassLoaderData::free_deallocate_list() {
818 // This must be called at a safepoint because it depends on metadata walking at
819 // safepoint cleanup time.
820 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
821 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
822 if (_deallocate_list == NULL) {
823 return;
824 }
825 // Go backwards because this removes entries that are freed.
826 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
827 Metadata* m = _deallocate_list->at(i);
828 if (!m->on_stack()) {
829 _deallocate_list->remove_at(i);
830 // There are only three types of metadata that we deallocate directly.
831 // Cast them so they can be used by the template function.
832 if (m->is_method()) {
833 MetadataFactory::free_metadata(this, (Method*)m);
834 } else if (m->is_constantPool()) {
835 MetadataFactory::free_metadata(this, (ConstantPool*)m);
836 } else if (m->is_klass()) {
837 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
838 } else {
839 ShouldNotReachHere();
840 }
841 } else {
842 // Metadata is alive.
843 // If scratch_class is on stack then it shouldn't be on this list!
844 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
845 "scratch classes on this list should be dead");
846 // Also should assert that other metadata on the list was found in handles.
847 // Some cleaning remains.
848 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
849 }
850 }
851}
852
853// This is distinct from free_deallocate_list. For class loader data that are
854// unloading, this frees the C heap memory for items on the list, and unlinks
855// scratch or error classes so that unloading events aren't triggered for these
856// classes. The metadata is removed with the unloading metaspace.
857// There isn't C heap memory allocated for methods, so nothing is done for them.
858void ClassLoaderData::free_deallocate_list_C_heap_structures() {
859 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
860 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
861 if (_deallocate_list == NULL) {
862 return;
863 }
864 // Go backwards because this removes entries that are freed.
865 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
866 Metadata* m = _deallocate_list->at(i);
867 _deallocate_list->remove_at(i);
868 if (m->is_constantPool()) {
869 ((ConstantPool*)m)->release_C_heap_structures();
870 } else if (m->is_klass()) {
871 InstanceKlass* ik = (InstanceKlass*)m;
872 // also releases ik->constants() C heap memory
873 InstanceKlass::release_C_heap_structures(ik);
874 // Remove the class so unloading events aren't triggered for
875 // this class (scratch or error class) in do_unloading().
876 remove_class(ik);
877 }
878 }
879}
880
881// These CLDs are to contain unsafe anonymous classes used for JSR292
882ClassLoaderData* ClassLoaderData::unsafe_anonymous_class_loader_data(Handle loader) {
883 // Add a new class loader data to the graph.
884 return ClassLoaderDataGraph::add(loader, true);
885}
886
887// Caller needs ResourceMark
888// If the class loader's _name has not been explicitly set, the class loader's
889// qualified class name is returned.
890const char* ClassLoaderData::loader_name() const {
891 if (_class_loader_klass == NULL) {
892 return BOOTSTRAP_LOADER_NAME;
893 } else if (_name != NULL) {
894 return _name->as_C_string();
895 } else {
896 return _class_loader_klass->external_name();
897 }
898}
899
900// Caller needs ResourceMark
901// Format of the _name_and_id is as follows:
902// If the defining loader has a name explicitly set then '<loader-name>' @<id>
903// If the defining loader has no name then <qualified-class-name> @<id>
904// If built-in loader, then omit '@<id>' as there is only one instance.
905const char* ClassLoaderData::loader_name_and_id() const {
906 if (_class_loader_klass == NULL) {
907 return "'" BOOTSTRAP_LOADER_NAME "'";
908 } else if (_name_and_id != NULL) {
909 return _name_and_id->as_C_string();
910 } else {
911 // May be called in a race before _name_and_id is initialized.
912 return _class_loader_klass->external_name();
913 }
914}
915
916void ClassLoaderData::print_value_on(outputStream* out) const {
917 if (!is_unloading() && class_loader() != NULL) {
918 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
919 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance
920 } else {
921 // loader data: 0xsomeaddr of 'bootstrap'
922 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
923 }
924 if (is_unsafe_anonymous()) {
925 out->print(" unsafe anonymous");
926 }
927}
928
929void ClassLoaderData::print_value() const { print_value_on(tty); }
930
931#ifndef PRODUCT
932void ClassLoaderData::print_on(outputStream* out) const {
933 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: %s {",
934 p2i(this), p2i(_class_loader.ptr_raw()), loader_name_and_id());
935 if (is_unsafe_anonymous()) out->print(" unsafe anonymous");
936 if (claimed()) out->print(" claimed");
937 if (is_unloading()) out->print(" unloading");
938 out->print(" metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
939
940 if (_jmethod_ids != NULL) {
941 Method::print_jmethod_ids(this, out);
942 }
943 out->print(" handles count %d", _handles.count());
944 out->print(" dependencies %d", _dependency_count);
945 out->print_cr("}");
946}
947#endif // PRODUCT
948
949void ClassLoaderData::print() const { print_on(tty); }
950
951void ClassLoaderData::verify() {
952 assert_locked_or_safepoint(_metaspace_lock);
953 oop cl = class_loader();
954
955 guarantee(this == class_loader_data(cl) || is_unsafe_anonymous(), "Must be the same");
956 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_unsafe_anonymous(), "must be");
957
958 // Verify the integrity of the allocated space.
959 if (metaspace_or_null() != NULL) {
960 metaspace_or_null()->verify();
961 }
962
963 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
964 guarantee(k->class_loader_data() == this, "Must be the same");
965 k->verify();
966 assert(k != k->next_link(), "no loops!");
967 }
968}
969
970bool ClassLoaderData::contains_klass(Klass* klass) {
971 // Lock-free access requires load_acquire
972 for (Klass* k = OrderAccess::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
973 if (k == klass) return true;
974 }
975 return false;
976}
977