1 /*
2 * Copyright (c) 2012, 2022, 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 "classfile/systemDictionaryShared.hpp"
59 #include "classfile/vmClasses.hpp"
60 #include "logging/log.hpp"
61 #include "logging/logStream.hpp"
62 #include "memory/allocation.inline.hpp"
63 #include "memory/classLoaderMetaspace.hpp"
64 #include "memory/metadataFactory.hpp"
65 #include "memory/metaspace.hpp"
66 #include "memory/resourceArea.hpp"
67 #include "memory/universe.hpp"
68 #include "oops/access.inline.hpp"
69 #include "oops/klass.inline.hpp"
70 #include "oops/objArrayKlass.hpp"
71 #include "oops/oop.inline.hpp"
72 #include "oops/oopHandle.inline.hpp"
73 #include "oops/inlineKlass.inline.hpp"
74 #include "oops/weakHandle.inline.hpp"
75 #include "runtime/arguments.hpp"
76 #include "runtime/atomic.hpp"
77 #include "runtime/handles.inline.hpp"
78 #include "runtime/mutex.hpp"
79 #include "runtime/safepoint.hpp"
80 #include "utilities/growableArray.hpp"
81 #include "utilities/macros.hpp"
82 #include "utilities/ostream.hpp"
83
84 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
85
86 void ClassLoaderData::init_null_class_loader_data() {
87 assert(_the_null_class_loader_data == NULL, "cannot initialize twice");
88 assert(ClassLoaderDataGraph::_head == NULL, "cannot initialize twice");
89
90 _the_null_class_loader_data = new ClassLoaderData(Handle(), false);
91 ClassLoaderDataGraph::_head = _the_null_class_loader_data;
92 assert(_the_null_class_loader_data->is_the_null_class_loader_data(), "Must be");
93
94 LogTarget(Trace, class, loader, data) lt;
95 if (lt.is_enabled()) {
96 ResourceMark rm;
97 LogStream ls(lt);
98 ls.print("create ");
99 _the_null_class_loader_data->print_value_on(&ls);
100 ls.cr();
101 }
102 }
103
104 // Obtain and set the class loader's name within the ClassLoaderData so
105 // it will be available for error messages, logging, JFR, etc. The name
106 // and klass are available after the class_loader oop is no longer alive,
107 // during unloading.
108 void ClassLoaderData::initialize_name(Handle class_loader) {
109 ResourceMark rm;
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 _name = SymbolTable::new_symbol(cl_instance_name);
119 }
120 }
121
122 // Obtain the class loader's name and identity hash. If the class loader's
123 // name was not explicitly set during construction, the class loader's name and id
124 // will be set to the qualified class name of the class loader along with its
125 // identity hash.
126 // If for some reason the ClassLoader's constructor has not been run, instead of
127 // leaving the _name_and_id field null, fall back to the external qualified class
128 // name. Thus CLD's _name_and_id field should never have a null value.
129 oop cl_name_and_id = java_lang_ClassLoader::nameAndId(class_loader());
130 const char* cl_instance_name_and_id =
131 (cl_name_and_id == NULL) ? _class_loader_klass->external_name() :
132 java_lang_String::as_utf8_string(cl_name_and_id);
133 assert(cl_instance_name_and_id != NULL && cl_instance_name_and_id[0] != '\0', "class loader has no name and id");
134 _name_and_id = SymbolTable::new_symbol(cl_instance_name_and_id);
135 }
136
137 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool has_class_mirror_holder) :
138 _metaspace(NULL),
139 _metaspace_lock(new Mutex(Mutex::nosafepoint-2, "MetaspaceAllocation_lock")),
140 _unloading(false), _has_class_mirror_holder(has_class_mirror_holder),
141 _modified_oops(true),
142 // A non-strong hidden class loader data doesn't have anything to keep
143 // it from being unloaded during parsing of the non-strong hidden class.
144 // The null-class-loader should always be kept alive.
145 _keep_alive((has_class_mirror_holder || h_class_loader.is_null()) ? 1 : 0),
146 _claim(0),
147 _handles(),
148 _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL),
149 _jmethod_ids(NULL),
150 _deallocate_list(NULL),
151 _next(NULL),
152 _class_loader_klass(NULL), _name(NULL), _name_and_id(NULL) {
153
154 if (!h_class_loader.is_null()) {
155 _class_loader = _handles.add(h_class_loader());
156 _class_loader_klass = h_class_loader->klass();
157 initialize_name(h_class_loader);
158 }
159
160 if (!has_class_mirror_holder) {
161 // The holder is initialized later for non-strong hidden classes,
162 // and before calling anything that call class_loader().
163 initialize_holder(h_class_loader);
164
165 // A ClassLoaderData created solely for a non-strong hidden class should never
166 // have a ModuleEntryTable or PackageEntryTable created for it.
167 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
168 if (h_class_loader.is_null()) {
169 // Create unnamed module for boot loader
170 _unnamed_module = ModuleEntry::create_boot_unnamed_module(this);
171 } else {
172 // Create unnamed module for all other loaders
173 _unnamed_module = ModuleEntry::create_unnamed_module(this);
174 }
175 _dictionary = create_dictionary();
176 }
177
178 NOT_PRODUCT(_dependency_count = 0); // number of class loader dependencies
179
180 JFR_ONLY(INIT_ID(this);)
181 }
182
183 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
184 Chunk* c = _head;
185 while (c != NULL) {
186 Chunk* next = c->_next;
187 delete c;
188 c = next;
189 }
190 }
191
192 OopHandle ClassLoaderData::ChunkedHandleList::add(oop o) {
193 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
194 Chunk* next = new Chunk(_head);
195 Atomic::release_store(&_head, next);
196 }
197 oop* handle = &_head->_data[_head->_size];
198 NativeAccess<IS_DEST_UNINITIALIZED>::oop_store(handle, o);
199 Atomic::release_store(&_head->_size, _head->_size + 1);
200 return OopHandle(handle);
201 }
202
203 int ClassLoaderData::ChunkedHandleList::count() const {
204 int count = 0;
205 Chunk* chunk = _head;
206 while (chunk != NULL) {
207 count += chunk->_size;
208 chunk = chunk->_next;
209 }
210 return count;
211 }
212
213 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
214 for (juint i = 0; i < size; i++) {
215 if (c->_data[i] != NULL) {
216 f->do_oop(&c->_data[i]);
217 }
218 }
219 }
220
221 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
222 Chunk* head = Atomic::load_acquire(&_head);
223 if (head != NULL) {
224 // Must be careful when reading size of head
225 oops_do_chunk(f, head, Atomic::load_acquire(&head->_size));
226 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
227 oops_do_chunk(f, c, c->_size);
228 }
229 }
230 }
231
232 class VerifyContainsOopClosure : public OopClosure {
233 oop _target;
234 bool _found;
235
236 public:
237 VerifyContainsOopClosure(oop target) : _target(target), _found(false) {}
238
239 void do_oop(oop* p) {
240 if (p != NULL && NativeAccess<AS_NO_KEEPALIVE>::oop_load(p) == _target) {
241 _found = true;
242 }
243 }
244
245 void do_oop(narrowOop* p) {
246 // The ChunkedHandleList should not contain any narrowOop
247 ShouldNotReachHere();
248 }
249
250 bool found() const {
251 return _found;
252 }
253 };
254
255 bool ClassLoaderData::ChunkedHandleList::contains(oop p) {
256 VerifyContainsOopClosure cl(p);
257 oops_do(&cl);
258 return cl.found();
259 }
260
261 #ifndef PRODUCT
262 bool ClassLoaderData::ChunkedHandleList::owner_of(oop* oop_handle) {
263 Chunk* chunk = _head;
264 while (chunk != NULL) {
265 if (&(chunk->_data[0]) <= oop_handle && oop_handle < &(chunk->_data[chunk->_size])) {
266 return true;
267 }
268 chunk = chunk->_next;
269 }
270 return false;
271 }
272 #endif // PRODUCT
273
274 void ClassLoaderData::clear_claim(int claim) {
275 for (;;) {
276 int old_claim = Atomic::load(&_claim);
277 if ((old_claim & claim) == 0) {
278 return;
279 }
280 int new_claim = old_claim & ~claim;
281 if (Atomic::cmpxchg(&_claim, old_claim, new_claim) == old_claim) {
282 return;
283 }
284 }
285 }
286
287 bool ClassLoaderData::try_claim(int claim) {
288 for (;;) {
289 int old_claim = Atomic::load(&_claim);
290 if ((old_claim & claim) == claim) {
291 return false;
292 }
293 int new_claim = old_claim | claim;
294 if (Atomic::cmpxchg(&_claim, old_claim, new_claim) == old_claim) {
295 return true;
296 }
297 }
298 }
299
300 // Non-strong hidden classes have their own ClassLoaderData that is marked to keep alive
301 // while the class is being parsed, and if the class appears on the module fixup list.
302 // Due to the uniqueness that no other class shares the hidden class' name or
303 // ClassLoaderData, no other non-GC thread has knowledge of the hidden class while
304 // it is being defined, therefore _keep_alive is not volatile or atomic.
305 void ClassLoaderData::inc_keep_alive() {
306 if (has_class_mirror_holder()) {
307 assert(_keep_alive > 0, "Invalid keep alive increment count");
308 _keep_alive++;
309 }
310 }
311
312 void ClassLoaderData::dec_keep_alive() {
313 if (has_class_mirror_holder()) {
314 assert(_keep_alive > 0, "Invalid keep alive decrement count");
315 _keep_alive--;
316 }
317 }
318
319 void ClassLoaderData::oops_do(OopClosure* f, int claim_value, bool clear_mod_oops) {
320 if (claim_value != ClassLoaderData::_claim_none && !try_claim(claim_value)) {
321 return;
322 }
323
324 // Only clear modified_oops after the ClassLoaderData is claimed.
325 if (clear_mod_oops) {
326 clear_modified_oops();
327 }
328
329 _handles.oops_do(f);
330 }
331
332 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
333 // Lock-free access requires load_acquire
334 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
335 klass_closure->do_klass(k);
336 assert(k != k->next_link(), "no loops!");
337 }
338 }
339
340 void ClassLoaderData::classes_do(void f(Klass * const)) {
341 // Lock-free access requires load_acquire
342 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
343 f(k);
344 assert(k != k->next_link(), "no loops!");
345 }
346 }
347
348 void ClassLoaderData::methods_do(void f(Method*)) {
349 // Lock-free access requires load_acquire
350 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
351 if (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded()) {
352 InstanceKlass::cast(k)->methods_do(f);
353 }
354 }
355 }
356
357 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
358 // To call this, one must have the MultiArray_lock held, but the _klasses list still has lock free reads.
359 assert_locked_or_safepoint(MultiArray_lock);
360
361 // Lock-free access requires load_acquire
362 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
363 // Filter out InstanceKlasses (or their ObjArrayKlasses) that have not entered the
364 // loaded state.
365 if (k->is_instance_klass()) {
366 if (!InstanceKlass::cast(k)->is_loaded()) {
367 continue;
368 }
369 } else if (k->is_shared() && k->is_objArray_klass()) {
370 Klass* bottom = ObjArrayKlass::cast(k)->bottom_klass();
371 if (bottom->is_instance_klass() && !InstanceKlass::cast(bottom)->is_loaded()) {
372 // This could happen if <bottom> is a shared class that has been restored
373 // but is not yet marked as loaded. All archived array classes of the
374 // bottom class are already restored and placed in the _klasses list.
375 continue;
376 }
377 }
378
379 #ifdef ASSERT
380 oop m = k->java_mirror();
381 assert(m != NULL, "NULL mirror");
382 assert(m->is_a(vmClasses::Class_klass()), "invalid mirror");
383 #endif
384 klass_closure->do_klass(k);
385 }
386 }
387
388 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
389 // Lock-free access requires load_acquire
390 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
391 if (k->is_instance_klass()) {
392 f(InstanceKlass::cast(k));
393 }
394 assert(k != k->next_link(), "no loops!");
395 }
396 }
397
398 void ClassLoaderData::inline_classes_do(void f(InlineKlass*)) {
399 // Lock-free access requires load_acquire
400 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
401 if (k->is_inline_klass()) {
402 f(InlineKlass::cast(k));
403 }
404 assert(k != k->next_link(), "no loops!");
405 }
406 }
407
408 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
409 assert_locked_or_safepoint(Module_lock);
410 if (_unnamed_module != NULL) {
411 f(_unnamed_module);
412 }
413 if (_modules != NULL) {
414 for (int i = 0; i < _modules->table_size(); i++) {
415 for (ModuleEntry* entry = _modules->bucket(i);
416 entry != NULL;
417 entry = entry->next()) {
418 f(entry);
419 }
420 }
421 }
422 }
423
424 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
425 assert_locked_or_safepoint(Module_lock);
426 if (_packages != NULL) {
427 for (int i = 0; i < _packages->table_size(); i++) {
428 for (PackageEntry* entry = _packages->bucket(i);
429 entry != NULL;
430 entry = entry->next()) {
431 f(entry);
432 }
433 }
434 }
435 }
436
437 void ClassLoaderData::record_dependency(const Klass* k) {
438 assert(k != NULL, "invariant");
439
440 ClassLoaderData * const from_cld = this;
441 ClassLoaderData * const to_cld = k->class_loader_data();
442
443 // Do not need to record dependency if the dependency is to a class whose
444 // class loader data is never freed. (i.e. the dependency's class loader
445 // is one of the three builtin class loaders and the dependency's class
446 // loader data has a ClassLoader holder, not a Class holder.)
447 if (to_cld->is_permanent_class_loader_data()) {
448 return;
449 }
450
451 oop to;
452 if (to_cld->has_class_mirror_holder()) {
453 // Just return if a non-strong hidden class class is attempting to record a dependency
454 // to itself. (Note that every non-strong hidden class has its own unique class
455 // loader data.)
456 if (to_cld == from_cld) {
457 return;
458 }
459 // Hidden class dependencies are through the mirror.
460 to = k->java_mirror();
461 } else {
462 to = to_cld->class_loader();
463 oop from = from_cld->class_loader();
464
465 // Just return if this dependency is to a class with the same or a parent
466 // class_loader.
467 if (from == to || java_lang_ClassLoader::isAncestor(from, to)) {
468 return; // this class loader is in the parent list, no need to add it.
469 }
470 }
471
472 // It's a dependency we won't find through GC, add it.
473 if (!_handles.contains(to)) {
474 NOT_PRODUCT(Atomic::inc(&_dependency_count));
475 LogTarget(Trace, class, loader, data) lt;
476 if (lt.is_enabled()) {
477 ResourceMark rm;
478 LogStream ls(lt);
479 ls.print("adding dependency from ");
480 print_value_on(&ls);
481 ls.print(" to ");
482 to_cld->print_value_on(&ls);
483 ls.cr();
484 }
485 Handle dependency(Thread::current(), to);
486 add_handle(dependency);
487 // Added a potentially young gen oop to the ClassLoaderData
488 record_modified_oops();
489 }
490 }
491
492 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
493 {
494 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
495 Klass* old_value = _klasses;
496 k->set_next_link(old_value);
497 // Link the new item into the list, making sure the linked class is stable
498 // since the list can be walked without a lock
499 Atomic::release_store(&_klasses, k);
500 if (k->is_array_klass()) {
501 ClassLoaderDataGraph::inc_array_classes(1);
502 } else {
503 ClassLoaderDataGraph::inc_instance_classes(1);
504 }
505 }
506
507 if (publicize) {
508 LogTarget(Trace, class, loader, data) lt;
509 if (lt.is_enabled()) {
510 ResourceMark rm;
511 LogStream ls(lt);
512 ls.print("Adding k: " PTR_FORMAT " %s to ", p2i(k), k->external_name());
513 print_value_on(&ls);
514 ls.cr();
515 }
516 }
517 }
518
519 void ClassLoaderData::initialize_holder(Handle loader_or_mirror) {
520 if (loader_or_mirror() != NULL) {
521 assert(_holder.is_null(), "never replace holders");
522 _holder = WeakHandle(Universe::vm_weak(), loader_or_mirror);
523 }
524 }
525
526 // Remove a klass from the _klasses list for scratch_class during redefinition
527 // or parsed class in the case of an error.
528 void ClassLoaderData::remove_class(Klass* scratch_class) {
529 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
530
531 // Adjust global class iterator.
532 ClassLoaderDataGraph::adjust_saved_class(scratch_class);
533
534 Klass* prev = NULL;
535 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
536 if (k == scratch_class) {
537 if (prev == NULL) {
538 _klasses = k->next_link();
539 } else {
540 Klass* next = k->next_link();
541 prev->set_next_link(next);
542 }
543
544 if (k->is_array_klass()) {
545 ClassLoaderDataGraph::dec_array_classes(1);
546 } else {
547 ClassLoaderDataGraph::dec_instance_classes(1);
548 }
549
550 return;
551 }
552 prev = k;
553 assert(k != k->next_link(), "no loops!");
554 }
555 ShouldNotReachHere(); // should have found this class!!
556 }
557
558 void ClassLoaderData::unload() {
559 _unloading = true;
560
561 LogTarget(Trace, class, loader, data) lt;
562 if (lt.is_enabled()) {
563 ResourceMark rm;
564 LogStream ls(lt);
565 ls.print("unload");
566 print_value_on(&ls);
567 ls.cr();
568 }
569
570 // Some items on the _deallocate_list need to free their C heap structures
571 // if they are not already on the _klasses list.
572 free_deallocate_list_C_heap_structures();
573
574 inline_classes_do(InlineKlass::cleanup);
575
576 // Clean up class dependencies and tell serviceability tools
577 // these classes are unloading. Must be called
578 // after erroneous classes are released.
579 classes_do(InstanceKlass::unload_class);
580
581 // Method::clear_jmethod_ids only sets the jmethod_ids to NULL without
582 // releasing the memory for related JNIMethodBlocks and JNIMethodBlockNodes.
583 // This is done intentionally because native code (e.g. JVMTI agent) holding
584 // jmethod_ids may access them after the associated classes and class loader
585 // are unloaded. The Java Native Interface Specification says "method ID
586 // does not prevent the VM from unloading the class from which the ID has
587 // been derived. After the class is unloaded, the method or field ID becomes
588 // invalid". In real world usages, the native code may rely on jmethod_ids
589 // being NULL after class unloading. Hence, it is unsafe to free the memory
590 // from the VM side without knowing when native code is going to stop using
591 // them.
592 if (_jmethod_ids != NULL) {
593 Method::clear_jmethod_ids(this);
594 }
595
596 // Clean up global class iterator for compiler
597 ClassLoaderDataGraph::adjust_saved_class(this);
598 }
599
600 ModuleEntryTable* ClassLoaderData::modules() {
601 // Lazily create the module entry table at first request.
602 // Lock-free access requires load_acquire.
603 ModuleEntryTable* modules = Atomic::load_acquire(&_modules);
604 if (modules == NULL) {
605 MutexLocker m1(Module_lock);
606 // Check if _modules got allocated while we were waiting for this lock.
607 if ((modules = _modules) == NULL) {
608 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
609
610 {
611 MutexLocker m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
612 // Ensure _modules is stable, since it is examined without a lock
613 Atomic::release_store(&_modules, modules);
614 }
615 }
616 }
617 return modules;
618 }
619
620 const int _boot_loader_dictionary_size = 1009;
621 const int _default_loader_dictionary_size = 107;
622
623 Dictionary* ClassLoaderData::create_dictionary() {
624 assert(!has_class_mirror_holder(), "class mirror holder cld does not have a dictionary");
625 int size;
626 bool resizable = false;
627 if (_the_null_class_loader_data == NULL) {
628 size = _boot_loader_dictionary_size;
629 resizable = true;
630 } else if (class_loader()->is_a(vmClasses::reflect_DelegatingClassLoader_klass())) {
631 size = 1; // there's only one class in relection class loader and no initiated classes
632 } else if (is_system_class_loader_data()) {
633 size = _boot_loader_dictionary_size;
634 resizable = true;
635 } else {
636 size = _default_loader_dictionary_size;
637 resizable = true;
638 }
639 if (!DynamicallyResizeSystemDictionaries || DumpSharedSpaces) {
640 resizable = false;
641 }
642 return new Dictionary(this, size, resizable);
643 }
644
645 // Tell the GC to keep this klass alive. Needed while iterating ClassLoaderDataGraph,
646 // and any runtime code that uses klasses.
647 oop ClassLoaderData::holder() const {
648 // A klass that was previously considered dead can be looked up in the
649 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
650 // or a reachable object making it alive again. The SATB part of G1 needs
651 // to get notified about this potential resurrection, otherwise the marking
652 // might not find the object.
653 if (!_holder.is_null()) { // NULL class_loader
654 return _holder.resolve();
655 } else {
656 return NULL;
657 }
658 }
659
660 // Let the GC read the holder without keeping it alive.
661 oop ClassLoaderData::holder_no_keepalive() const {
662 if (!_holder.is_null()) { // NULL class_loader
663 return _holder.peek();
664 } else {
665 return NULL;
666 }
667 }
668
669 // Unloading support
670 bool ClassLoaderData::is_alive() const {
671 bool alive = keep_alive() // null class loader and incomplete non-strong hidden class.
672 || (_holder.peek() != NULL); // and not cleaned by the GC weak handle processing.
673
674 return alive;
675 }
676
677 class ReleaseKlassClosure: public KlassClosure {
678 private:
679 size_t _instance_class_released;
680 size_t _array_class_released;
681 public:
682 ReleaseKlassClosure() : _instance_class_released(0), _array_class_released(0) { }
683
684 size_t instance_class_released() const { return _instance_class_released; }
685 size_t array_class_released() const { return _array_class_released; }
686
687 void do_klass(Klass* k) {
688 if (k->is_array_klass()) {
689 _array_class_released ++;
690 } else {
691 assert(k->is_instance_klass(), "Must be");
692 _instance_class_released ++;
693 }
694 k->release_C_heap_structures();
695 }
696 };
697
698 ClassLoaderData::~ClassLoaderData() {
699 // Release C heap structures for all the classes.
700 ReleaseKlassClosure cl;
701 classes_do(&cl);
702
703 ClassLoaderDataGraph::dec_array_classes(cl.array_class_released());
704 ClassLoaderDataGraph::dec_instance_classes(cl.instance_class_released());
705
706 // Release the WeakHandle
707 _holder.release(Universe::vm_weak());
708
709 // Release C heap allocated hashtable for all the packages.
710 if (_packages != NULL) {
711 // Destroy the table itself
712 delete _packages;
713 _packages = NULL;
714 }
715
716 // Release C heap allocated hashtable for all the modules.
717 if (_modules != NULL) {
718 // Destroy the table itself
719 delete _modules;
720 _modules = NULL;
721 }
722
723 // Release C heap allocated hashtable for the dictionary
724 if (_dictionary != NULL) {
725 // Destroy the table itself
726 delete _dictionary;
727 _dictionary = NULL;
728 }
729
730 if (_unnamed_module != NULL) {
731 _unnamed_module->delete_unnamed_module();
732 _unnamed_module = NULL;
733 }
734
735 // release the metaspace
736 ClassLoaderMetaspace *m = _metaspace;
737 if (m != NULL) {
738 _metaspace = NULL;
739 delete m;
740 }
741
742 // Delete lock
743 delete _metaspace_lock;
744
745 // Delete free list
746 if (_deallocate_list != NULL) {
747 delete _deallocate_list;
748 }
749
750 // Decrement refcounts of Symbols if created.
751 if (_name != NULL) {
752 _name->decrement_refcount();
753 }
754 if (_name_and_id != NULL) {
755 _name_and_id->decrement_refcount();
756 }
757 }
758
759 // Returns true if this class loader data is for the app class loader
760 // or a user defined system class loader. (Note that the class loader
761 // data may have a Class holder.)
762 bool ClassLoaderData::is_system_class_loader_data() const {
763 return SystemDictionary::is_system_class_loader(class_loader());
764 }
765
766 // Returns true if this class loader data is for the platform class loader.
767 // (Note that the class loader data may have a Class holder.)
768 bool ClassLoaderData::is_platform_class_loader_data() const {
769 return SystemDictionary::is_platform_class_loader(class_loader());
770 }
771
772 // Returns true if the class loader for this class loader data is one of
773 // the 3 builtin (boot application/system or platform) class loaders,
774 // including a user-defined system class loader. Note that if the class
775 // loader data is for a non-strong hidden class then it may
776 // get freed by a GC even if its class loader is one of these loaders.
777 bool ClassLoaderData::is_builtin_class_loader_data() const {
778 return (is_boot_class_loader_data() ||
779 SystemDictionary::is_system_class_loader(class_loader()) ||
780 SystemDictionary::is_platform_class_loader(class_loader()));
781 }
782
783 // Returns true if this class loader data is a class loader data
784 // that is not ever freed by a GC. It must be the CLD for one of the builtin
785 // class loaders and not the CLD for a non-strong hidden class.
786 bool ClassLoaderData::is_permanent_class_loader_data() const {
787 return is_builtin_class_loader_data() && !has_class_mirror_holder();
788 }
789
790 ClassLoaderMetaspace* ClassLoaderData::metaspace_non_null() {
791 // If the metaspace has not been allocated, create a new one. Might want
792 // to create smaller arena for Reflection class loaders also.
793 // The reason for the delayed allocation is because some class loaders are
794 // simply for delegating with no metadata of their own.
795 // Lock-free access requires load_acquire.
796 ClassLoaderMetaspace* metaspace = Atomic::load_acquire(&_metaspace);
797 if (metaspace == NULL) {
798 MutexLocker ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
799 // Check if _metaspace got allocated while we were waiting for this lock.
800 if ((metaspace = _metaspace) == NULL) {
801 if (this == the_null_class_loader_data()) {
802 assert (class_loader() == NULL, "Must be");
803 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
804 } else if (has_class_mirror_holder()) {
805 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ClassMirrorHolderMetaspaceType);
806 } else if (class_loader()->is_a(vmClasses::reflect_DelegatingClassLoader_klass())) {
807 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
808 } else {
809 metaspace = new ClassLoaderMetaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
810 }
811 // Ensure _metaspace is stable, since it is examined without a lock
812 Atomic::release_store(&_metaspace, metaspace);
813 }
814 }
815 return metaspace;
816 }
817
818 OopHandle ClassLoaderData::add_handle(Handle h) {
819 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
820 record_modified_oops();
821 return _handles.add(h());
822 }
823
824 void ClassLoaderData::remove_handle(OopHandle h) {
825 assert(!is_unloading(), "Do not remove a handle for a CLD that is unloading");
826 oop* ptr = h.ptr_raw();
827 if (ptr != NULL) {
828 assert(_handles.owner_of(ptr), "Got unexpected handle " PTR_FORMAT, p2i(ptr));
829 NativeAccess<>::oop_store(ptr, oop(NULL));
830 }
831 }
832
833 void ClassLoaderData::init_handle_locked(OopHandle& dest, Handle h) {
834 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
835 if (dest.resolve() != NULL) {
836 return;
837 } else {
838 record_modified_oops();
839 dest = _handles.add(h());
840 }
841 }
842
843 // Add this metadata pointer to be freed when it's safe. This is only during
844 // a safepoint which checks if handles point to this metadata field.
845 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
846 // Metadata in shared region isn't deleted.
847 if (!m->is_shared()) {
848 MutexLocker ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
849 if (_deallocate_list == NULL) {
850 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, mtClass);
851 }
852 _deallocate_list->append_if_missing(m);
853 log_debug(class, loader, data)("deallocate added for %s", m->print_value_string());
854 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
855 }
856 }
857
858 // Deallocate free metadata on the free list. How useful the PermGen was!
859 void ClassLoaderData::free_deallocate_list() {
860 // This must be called at a safepoint because it depends on metadata walking at
861 // safepoint cleanup time.
862 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
863 assert(!is_unloading(), "only called for ClassLoaderData that are not unloading");
864 if (_deallocate_list == NULL) {
865 return;
866 }
867 // Go backwards because this removes entries that are freed.
868 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
869 Metadata* m = _deallocate_list->at(i);
870 if (!m->on_stack()) {
871 _deallocate_list->remove_at(i);
872 // There are only three types of metadata that we deallocate directly.
873 // Cast them so they can be used by the template function.
874 if (m->is_method()) {
875 MetadataFactory::free_metadata(this, (Method*)m);
876 } else if (m->is_constantPool()) {
877 MetadataFactory::free_metadata(this, (ConstantPool*)m);
878 } else if (m->is_klass()) {
879 if (!((Klass*)m)->is_inline_klass()) {
880 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
881 } else {
882 MetadataFactory::free_metadata(this, (InlineKlass*)m);
883 }
884 } else {
885 ShouldNotReachHere();
886 }
887 } else {
888 // Metadata is alive.
889 // If scratch_class is on stack then it shouldn't be on this list!
890 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
891 "scratch classes on this list should be dead");
892 // Also should assert that other metadata on the list was found in handles.
893 // Some cleaning remains.
894 ClassLoaderDataGraph::set_should_clean_deallocate_lists();
895 }
896 }
897 }
898
899 // This is distinct from free_deallocate_list. For class loader data that are
900 // unloading, this frees the C heap memory for items on the list, and unlinks
901 // scratch or error classes so that unloading events aren't triggered for these
902 // classes. The metadata is removed with the unloading metaspace.
903 // There isn't C heap memory allocated for methods, so nothing is done for them.
904 void ClassLoaderData::free_deallocate_list_C_heap_structures() {
905 assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
906 assert(is_unloading(), "only called for ClassLoaderData that are unloading");
907 if (_deallocate_list == NULL) {
908 return;
909 }
910 // Go backwards because this removes entries that are freed.
911 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
912 Metadata* m = _deallocate_list->at(i);
913 _deallocate_list->remove_at(i);
914 if (m->is_constantPool()) {
915 ((ConstantPool*)m)->release_C_heap_structures();
916 } else if (m->is_klass()) {
917 InstanceKlass* ik = (InstanceKlass*)m;
918 // also releases ik->constants() C heap memory
919 ik->release_C_heap_structures();
920 // Remove the class so unloading events aren't triggered for
921 // this class (scratch or error class) in do_unloading().
922 remove_class(ik);
923 // But still have to remove it from the dumptime_table.
924 SystemDictionaryShared::handle_class_unloading(ik);
925 }
926 }
927 }
928
929 // Caller needs ResourceMark
930 // If the class loader's _name has not been explicitly set, the class loader's
931 // qualified class name is returned.
932 const char* ClassLoaderData::loader_name() const {
933 if (_class_loader_klass == NULL) {
934 return BOOTSTRAP_LOADER_NAME;
935 } else if (_name != NULL) {
936 return _name->as_C_string();
937 } else {
938 return _class_loader_klass->external_name();
939 }
940 }
941
942 // Caller needs ResourceMark
943 // Format of the _name_and_id is as follows:
944 // If the defining loader has a name explicitly set then '<loader-name>' @<id>
945 // If the defining loader has no name then <qualified-class-name> @<id>
946 // If built-in loader, then omit '@<id>' as there is only one instance.
947 const char* ClassLoaderData::loader_name_and_id() const {
948 if (_class_loader_klass == NULL) {
949 return "'" BOOTSTRAP_LOADER_NAME "'";
950 } else if (_name_and_id != NULL) {
951 return _name_and_id->as_C_string();
952 } else {
953 // May be called in a race before _name_and_id is initialized.
954 return _class_loader_klass->external_name();
955 }
956 }
957
958 void ClassLoaderData::print_value_on(outputStream* out) const {
959 if (!is_unloading() && class_loader() != NULL) {
960 out->print("loader data: " INTPTR_FORMAT " for instance ", p2i(this));
961 class_loader()->print_value_on(out); // includes loader_name_and_id() and address of class loader instance
962 } else {
963 // loader data: 0xsomeaddr of 'bootstrap'
964 out->print("loader data: " INTPTR_FORMAT " of %s", p2i(this), loader_name_and_id());
965 }
966 if (_has_class_mirror_holder) {
967 out->print(" has a class holder");
968 }
969 }
970
971 void ClassLoaderData::print_value() const { print_value_on(tty); }
972
973 #ifndef PRODUCT
974 class PrintKlassClosure: public KlassClosure {
975 outputStream* _out;
976 public:
977 PrintKlassClosure(outputStream* out): _out(out) { }
978
979 void do_klass(Klass* k) {
980 ResourceMark rm;
981 _out->print("%s,", k->external_name());
982 }
983 };
984
985 void ClassLoaderData::print_on(outputStream* out) const {
986 ResourceMark rm;
987 out->print_cr("ClassLoaderData(" INTPTR_FORMAT ")", p2i(this));
988 out->print_cr(" - name %s", loader_name_and_id());
989 if (!_holder.is_null()) {
990 out->print (" - holder ");
991 _holder.print_on(out);
992 out->print_cr("");
993 }
994 out->print_cr(" - class loader " INTPTR_FORMAT, p2i(_class_loader.ptr_raw()));
995 out->print_cr(" - metaspace " INTPTR_FORMAT, p2i(_metaspace));
996 out->print_cr(" - unloading %s", _unloading ? "true" : "false");
997 out->print_cr(" - class mirror holder %s", _has_class_mirror_holder ? "true" : "false");
998 out->print_cr(" - modified oops %s", _modified_oops ? "true" : "false");
999 out->print_cr(" - keep alive %d", _keep_alive);
1000 out->print (" - claim ");
1001 switch(_claim) {
1002 case _claim_none: out->print_cr("none"); break;
1003 case _claim_finalizable: out->print_cr("finalizable"); break;
1004 case _claim_strong: out->print_cr("strong"); break;
1005 case _claim_other: out->print_cr("other"); break;
1006 case _claim_other | _claim_finalizable: out->print_cr("other and finalizable"); break;
1007 case _claim_other | _claim_strong: out->print_cr("other and strong"); break;
1008 default: ShouldNotReachHere();
1009 }
1010 out->print_cr(" - handles %d", _handles.count());
1011 out->print_cr(" - dependency count %d", _dependency_count);
1012 out->print (" - klasses {");
1013 PrintKlassClosure closure(out);
1014 ((ClassLoaderData*)this)->classes_do(&closure);
1015 out->print_cr(" }");
1016 out->print_cr(" - packages " INTPTR_FORMAT, p2i(_packages));
1017 out->print_cr(" - module " INTPTR_FORMAT, p2i(_modules));
1018 out->print_cr(" - unnamed module " INTPTR_FORMAT, p2i(_unnamed_module));
1019 out->print_cr(" - dictionary " INTPTR_FORMAT, p2i(_dictionary));
1020 if (_jmethod_ids != NULL) {
1021 out->print (" - jmethod count ");
1022 Method::print_jmethod_ids_count(this, out);
1023 out->print_cr("");
1024 }
1025 out->print_cr(" - deallocate list " INTPTR_FORMAT, p2i(_deallocate_list));
1026 out->print_cr(" - next CLD " INTPTR_FORMAT, p2i(_next));
1027 }
1028 #endif // PRODUCT
1029
1030 void ClassLoaderData::print() const { print_on(tty); }
1031
1032 void ClassLoaderData::verify() {
1033 assert_locked_or_safepoint(_metaspace_lock);
1034 oop cl = class_loader();
1035
1036 guarantee(this == class_loader_data(cl) || has_class_mirror_holder(), "Must be the same");
1037 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || has_class_mirror_holder(), "must be");
1038
1039 // Verify the integrity of the allocated space.
1040 #ifdef ASSERT
1041 if (metaspace_or_null() != NULL) {
1042 metaspace_or_null()->verify();
1043 }
1044 #endif
1045
1046 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
1047 guarantee(k->class_loader_data() == this, "Must be the same");
1048 k->verify();
1049 assert(k != k->next_link(), "no loops!");
1050 }
1051 }
1052
1053 bool ClassLoaderData::contains_klass(Klass* klass) {
1054 // Lock-free access requires load_acquire
1055 for (Klass* k = Atomic::load_acquire(&_klasses); k != NULL; k = k->next_link()) {
1056 if (k == klass) return true;
1057 }
1058 return false;
1059 }