1 /*
2 * Copyright (c) 2012, 2016, 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/javaClasses.hpp"
53 #include "classfile/metadataOnStackMark.hpp"
54 #include "classfile/moduleEntry.hpp"
55 #include "classfile/packageEntry.hpp"
56 #include "classfile/systemDictionary.hpp"
57 #include "code/codeCache.hpp"
58 #include "gc/shared/gcLocker.hpp"
59 #include "logging/log.hpp"
60 #include "memory/metadataFactory.hpp"
61 #include "memory/metaspaceShared.hpp"
62 #include "memory/oopFactory.hpp"
63 #include "memory/resourceArea.hpp"
64 #include "oops/objArrayOop.inline.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "runtime/atomic.inline.hpp"
67 #include "runtime/javaCalls.hpp"
68 #include "runtime/jniHandles.hpp"
69 #include "runtime/mutex.hpp"
70 #include "runtime/safepoint.hpp"
71 #include "runtime/synchronizer.hpp"
72 #include "utilities/growableArray.hpp"
73 #include "utilities/macros.hpp"
74 #include "utilities/ostream.hpp"
75 #if INCLUDE_TRACE
76 #include "trace/tracing.hpp"
77 #endif
78
79 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
80
81 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
82 _class_loader(h_class_loader()),
83 _is_anonymous(is_anonymous),
84 // An anonymous class loader data doesn't have anything to keep
85 // it from being unloaded during parsing of the anonymous class.
86 // The null-class-loader should always be kept alive.
87 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
88 _metaspace(NULL), _unloading(false), _klasses(NULL),
89 _modules(NULL), _packages(NULL),
90 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
91 _next(NULL), _dependencies(dependencies), _shared_class_loader_id(-1),
92 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
93 Monitor::_safepoint_check_never)) {
94 // empty
95 }
96
97 void ClassLoaderData::init_dependencies(TRAPS) {
98 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
99 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
100 _dependencies.init(CHECK);
101 }
102
103 void ClassLoaderData::Dependencies::init(TRAPS) {
104 // Create empty dependencies array to add to. CMS requires this to be
105 // an oop so that it can track additions via card marks. We think.
106 _list_head = oopFactory::new_objectArray(2, CHECK);
107 }
108
109 bool ClassLoaderData::claim() {
110 if (_claimed == 1) {
111 return false;
112 }
113
114 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
115 }
116
117 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
118 // while the class is being parsed, and if the class appears on the module fixup list.
119 // Due to the uniqueness that no other class shares the anonymous class' name or
120 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
121 // it is being defined, therefore _keep_alive is not volatile or atomic.
122 void ClassLoaderData::inc_keep_alive() {
123 assert(_keep_alive >= 0, "Invalid keep alive count");
124 _keep_alive++;
125 }
126
127 void ClassLoaderData::dec_keep_alive() {
128 assert(_keep_alive > 0, "Invalid keep alive count");
129 _keep_alive--;
130 }
131
132 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
133 if (must_claim && !claim()) {
134 return;
135 }
136
137 f->do_oop(&_class_loader);
138 _dependencies.oops_do(f);
139 _handles->oops_do(f);
140 if (klass_closure != NULL) {
141 classes_do(klass_closure);
142 }
143 }
144
145 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
146 f->do_oop((oop*)&_list_head);
147 }
148
149 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
150 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
151 klass_closure->do_klass(k);
152 assert(k != k->next_link(), "no loops!");
153 }
154 }
155
156 void ClassLoaderData::classes_do(void f(Klass * const)) {
157 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
158 f(k);
159 }
160 }
161
162 void ClassLoaderData::methods_do(void f(Method*)) {
163 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
164 if (k->is_instance_klass()) {
165 InstanceKlass::cast(k)->methods_do(f);
166 }
167 }
168 }
169
170 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
171 // Lock to avoid classes being modified/added/removed during iteration
172 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
173 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
174 // Do not filter ArrayKlass oops here...
175 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
176 klass_closure->do_klass(k);
177 }
178 }
179 }
180
181 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
182 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
183 if (k->is_instance_klass()) {
184 f(InstanceKlass::cast(k));
185 }
186 assert(k != k->next_link(), "no loops!");
187 }
188 }
189
190 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
191 if (_modules != NULL) {
192 for (int i = 0; i < _modules->table_size(); i++) {
193 for (ModuleEntry* entry = _modules->bucket(i);
194 entry != NULL;
195 entry = entry->next()) {
196 f(entry);
197 }
198 }
199 }
200 }
201
202 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
203 if (_packages != NULL) {
204 for (int i = 0; i < _packages->table_size(); i++) {
205 for (PackageEntry* entry = _packages->bucket(i);
206 entry != NULL;
207 entry = entry->next()) {
208 f(entry);
209 }
210 }
211 }
212 }
213
214 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
215 assert(k != NULL, "invariant");
216
217 ClassLoaderData * const from_cld = this;
218 ClassLoaderData * const to_cld = k->class_loader_data();
219
220 // Dependency to the null class loader data doesn't need to be recorded
221 // because the null class loader data never goes away.
222 if (to_cld->is_the_null_class_loader_data()) {
223 return;
224 }
225
226 oop to;
227 if (to_cld->is_anonymous()) {
228 // Anonymous class dependencies are through the mirror.
229 to = k->java_mirror();
230 } else {
231 to = to_cld->class_loader();
232
233 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
234 // we still have to add it. The class_loader won't keep from_cld alive.
235 if (!from_cld->is_anonymous()) {
236 // Check that this dependency isn't from the same or parent class_loader
237 oop from = from_cld->class_loader();
238
239 oop curr = from;
240 while (curr != NULL) {
241 if (curr == to) {
242 return; // this class loader is in the parent list, no need to add it.
243 }
244 curr = java_lang_ClassLoader::parent(curr);
245 }
246 }
247 }
248
249 // It's a dependency we won't find through GC, add it. This is relatively rare
250 // Must handle over GC point.
251 Handle dependency(THREAD, to);
252 from_cld->_dependencies.add(dependency, CHECK);
253 }
254
255
256 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
257 // Check first if this dependency is already in the list.
258 // Save a pointer to the last to add to under the lock.
259 objArrayOop ok = _list_head;
260 objArrayOop last = NULL;
261 while (ok != NULL) {
262 last = ok;
263 if (ok->obj_at(0) == dependency()) {
264 // Don't need to add it
265 return;
266 }
267 ok = (objArrayOop)ok->obj_at(1);
268 }
269
270 // Must handle over GC points
271 assert (last != NULL, "dependencies should be initialized");
272 objArrayHandle last_handle(THREAD, last);
273
274 // Create a new dependency node with fields for (class_loader or mirror, next)
275 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
276 deps->obj_at_put(0, dependency());
277
278 // Must handle over GC points
279 objArrayHandle new_dependency(THREAD, deps);
280
281 // Add the dependency under lock
282 locked_add(last_handle, new_dependency, THREAD);
283 }
284
285 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
286 objArrayHandle new_dependency,
287 Thread* THREAD) {
288
289 // Have to lock and put the new dependency on the end of the dependency
290 // array so the card mark for CMS sees that this dependency is new.
291 // Can probably do this lock free with some effort.
292 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
293
294 oop loader_or_mirror = new_dependency->obj_at(0);
295
296 // Since the dependencies are only added, add to the end.
297 objArrayOop end = last_handle();
298 objArrayOop last = NULL;
299 while (end != NULL) {
300 last = end;
301 // check again if another thread added it to the end.
302 if (end->obj_at(0) == loader_or_mirror) {
303 // Don't need to add it
304 return;
305 }
306 end = (objArrayOop)end->obj_at(1);
307 }
308 assert (last != NULL, "dependencies should be initialized");
309 // fill in the first element with the oop in new_dependency.
310 if (last->obj_at(0) == NULL) {
311 last->obj_at_put(0, new_dependency->obj_at(0));
312 } else {
313 last->obj_at_put(1, new_dependency());
314 }
315 }
316
317 void ClassLoaderDataGraph::clear_claimed_marks() {
318 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
319 cld->clear_claimed();
320 }
321 }
322
323 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
324 {
325 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
326 Klass* old_value = _klasses;
327 k->set_next_link(old_value);
328 // Make sure linked class is stable, since the class list is walked without a lock
329 OrderAccess::storestore();
330 // link the new item into the list
331 _klasses = k;
332 }
333
334 if (publicize && k->class_loader_data() != NULL) {
335 ResourceMark rm;
336 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
337 PTR_FORMAT " loader: " PTR_FORMAT " %s",
338 p2i(k),
339 k->external_name(),
340 p2i(k->class_loader_data()),
341 p2i((void *)k->class_loader()),
342 loader_name());
343 }
344 }
345
346 // This is called by InstanceKlass::deallocate_contents() to remove the
347 // scratch_class for redefine classes. We need a lock because there it may not
348 // be called at a safepoint if there's an error.
349 void ClassLoaderData::remove_class(Klass* scratch_class) {
350 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
351 Klass* prev = NULL;
352 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
353 if (k == scratch_class) {
354 if (prev == NULL) {
355 _klasses = k->next_link();
356 } else {
357 Klass* next = k->next_link();
358 prev->set_next_link(next);
359 }
360 return;
361 }
362 prev = k;
363 assert(k != k->next_link(), "no loops!");
364 }
365 ShouldNotReachHere(); // should have found this class!!
366 }
367
368 void ClassLoaderData::unload() {
369 _unloading = true;
370
371 // Tell serviceability tools these classes are unloading
372 classes_do(InstanceKlass::notify_unload_class);
373
374 if (log_is_enabled(Debug, class, loader, data)) {
375 ResourceMark rm;
376 outputStream* log = Log(class, loader, data)::debug_stream();
377 log->print(": unload loader data " INTPTR_FORMAT, p2i(this));
378 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
379 loader_name());
380 if (is_anonymous()) {
381 log->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
382 }
383 log->cr();
384 }
385
386 // In some rare cases items added to this list will not be freed elsewhere.
387 // To keep it simple, just free everything in it here.
388 free_deallocate_list();
389 }
390
391 PackageEntryTable* ClassLoaderData::packages() {
392 // Lazily create the package entry table at first request.
393 if (_packages == NULL) {
394 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
395 // Check if _packages got allocated while we were waiting for this lock.
396 if (_packages == NULL) {
397 _packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
398 }
399 }
400 return _packages;
401 }
402
403 ModuleEntryTable* ClassLoaderData::modules() {
404 // Lazily create the module entry table at first request.
405 if (_modules == NULL) {
406 MutexLocker m1(Module_lock);
407 // Check again if _modules has been allocated while we were getting this lock.
408 if (_modules != NULL) {
409 return _modules;
410 }
411
412 ModuleEntryTable* temp_table = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
413 // Each loader has one unnamed module entry. Create it before
414 // any classes, loaded by this loader, are defined in case
415 // they end up being defined in loader's unnamed module.
416 temp_table->create_unnamed_module(this);
417
418 {
419 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
420 // Ensure _modules is stable, since it is examined without a lock
421 OrderAccess::storestore();
422 _modules = temp_table;
423 }
424 }
425 return _modules;
426 }
427
428 oop ClassLoaderData::keep_alive_object() const {
429 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
430 return is_anonymous() ? _klasses->java_mirror() : class_loader();
431 }
432
433 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
434 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
435 || is_alive_closure->do_object_b(keep_alive_object());
436
437 return alive;
438 }
439
440
441 ClassLoaderData::~ClassLoaderData() {
442 // Release C heap structures for all the classes.
443 classes_do(InstanceKlass::release_C_heap_structures);
444
445 // Release C heap allocated hashtable for all the packages.
446 if (_packages != NULL) {
447 // Destroy the table itself
448 delete _packages;
449 _packages = NULL;
450 }
451
452 // Release C heap allocated hashtable for all the modules.
453 if (_modules != NULL) {
454 // Destroy the table itself
455 delete _modules;
456 _modules = NULL;
457 }
458
459 // release the metaspace
460 Metaspace *m = _metaspace;
461 if (m != NULL) {
462 _metaspace = NULL;
463 delete m;
464 }
465 // release the handles
466 if (_handles != NULL) {
467 JNIHandleBlock::release_block(_handles);
468 _handles = NULL;
469 }
470
471 // Clear all the JNI handles for methods
472 // These aren't deallocated and are going to look like a leak, but that's
473 // needed because we can't really get rid of jmethodIDs because we don't
474 // know when native code is going to stop using them. The spec says that
475 // they're "invalid" but existing programs likely rely on their being
476 // NULL after class unloading.
477 if (_jmethod_ids != NULL) {
478 Method::clear_jmethod_ids(this);
479 }
480 // Delete lock
481 delete _metaspace_lock;
482
483 // Delete free list
484 if (_deallocate_list != NULL) {
485 delete _deallocate_list;
486 }
487 }
488
489 /**
490 * Returns true if this class loader data is for the platform class loader.
491 */
492 bool ClassLoaderData::is_platform_class_loader_data() const {
493 return SystemDictionary::is_platform_class_loader(class_loader());
494 }
495
496 Metaspace* ClassLoaderData::metaspace_non_null() {
497 assert(!DumpSharedSpaces, "wrong metaspace!");
498 // If the metaspace has not been allocated, create a new one. Might want
499 // to create smaller arena for Reflection class loaders also.
500 // The reason for the delayed allocation is because some class loaders are
501 // simply for delegating with no metadata of their own.
502 if (_metaspace == NULL) {
503 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
504 // Check again if metaspace has been allocated while we were getting this lock.
505 if (_metaspace != NULL) {
506 return _metaspace;
507 }
508 if (this == the_null_class_loader_data()) {
509 assert (class_loader() == NULL, "Must be");
510 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
511 } else if (is_anonymous()) {
512 if (class_loader() != NULL) {
513 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
514 }
515 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
516 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
517 if (class_loader() != NULL) {
518 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
519 }
520 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
521 } else {
522 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
523 }
524 }
525 return _metaspace;
526 }
527
528 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
529 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
530
531 jobject ClassLoaderData::add_handle(Handle h) {
532 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
533 if (handles() == NULL) {
534 set_handles(JNIHandleBlock::allocate_block());
535 }
536 return handles()->allocate_handle(h());
537 }
538
539 void ClassLoaderData::remove_handle(jobject h) {
540 _handles->release_handle(h);
541 }
542
543 // Add this metadata pointer to be freed when it's safe. This is only during
544 // class unloading because Handles might point to this metadata field.
545 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
546 // Metadata in shared region isn't deleted.
547 if (!m->is_shared()) {
548 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
549 if (_deallocate_list == NULL) {
550 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
551 }
552 _deallocate_list->append_if_missing(m);
553 }
554 }
555
556 // Deallocate free metadata on the free list. How useful the PermGen was!
557 void ClassLoaderData::free_deallocate_list() {
558 // Don't need lock, at safepoint
559 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
560 if (_deallocate_list == NULL) {
561 return;
562 }
563 // Go backwards because this removes entries that are freed.
564 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
565 Metadata* m = _deallocate_list->at(i);
566 if (!m->on_stack()) {
567 _deallocate_list->remove_at(i);
568 // There are only three types of metadata that we deallocate directly.
569 // Cast them so they can be used by the template function.
570 if (m->is_method()) {
571 MetadataFactory::free_metadata(this, (Method*)m);
572 } else if (m->is_constantPool()) {
573 MetadataFactory::free_metadata(this, (ConstantPool*)m);
574 } else if (m->is_klass()) {
575 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
576 } else {
577 ShouldNotReachHere();
578 }
579 } else {
580 // Metadata is alive.
581 // If scratch_class is on stack then it shouldn't be on this list!
582 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
583 "scratch classes on this list should be dead");
584 // Also should assert that other metadata on the list was found in handles.
585 }
586 }
587 }
588
589 // These anonymous class loaders are to contain classes used for JSR292
590 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
591 // Add a new class loader data to the graph.
592 return ClassLoaderDataGraph::add(loader, true, THREAD);
593 }
594
595 const char* ClassLoaderData::loader_name() {
596 // Handles null class loader
597 return SystemDictionary::loader_name(class_loader());
598 }
599
600 #ifndef PRODUCT
601 // Define to dump klasses
602 #undef CLD_DUMP_KLASSES
603
604 void ClassLoaderData::dump(outputStream * const out) {
605 ResourceMark rm;
606 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
607 p2i(this), p2i((void *)class_loader()),
608 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
609 if (claimed()) out->print(" claimed ");
610 if (is_unloading()) out->print(" unloading ");
611 out->print(" handles " INTPTR_FORMAT, p2i(handles()));
612 out->cr();
613 if (metaspace_or_null() != NULL) {
614 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
615 metaspace_or_null()->dump(out);
616 } else {
617 out->print_cr("metaspace: NULL");
618 }
619
620 #ifdef CLD_DUMP_KLASSES
621 if (Verbose) {
622 ResourceMark rm;
623 Klass* k = _klasses;
624 while (k != NULL) {
625 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
626 k->has_modified_oops(), k->has_accumulated_modified_oops());
627 assert(k != k->next_link(), "no loops!");
628 k = k->next_link();
629 }
630 }
631 #endif // CLD_DUMP_KLASSES
632 #undef CLD_DUMP_KLASSES
633 if (_jmethod_ids != NULL) {
634 Method::print_jmethod_ids(this, out);
635 }
636 out->print_cr("}");
637 }
638 #endif // PRODUCT
639
640 void ClassLoaderData::verify() {
641 oop cl = class_loader();
642
643 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
644 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
645
646 // Verify the integrity of the allocated space.
647 if (metaspace_or_null() != NULL) {
648 metaspace_or_null()->verify();
649 }
650
651 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
652 guarantee(k->class_loader_data() == this, "Must be the same");
653 k->verify();
654 assert(k != k->next_link(), "no loops!");
655 }
656 }
657
658 bool ClassLoaderData::contains_klass(Klass* klass) {
659 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
660 if (k == klass) return true;
661 }
662 return false;
663 }
664
665
666 // GC root of class loader data created.
667 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
668 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
669 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
670 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
671
672 bool ClassLoaderDataGraph::_should_purge = false;
673 bool ClassLoaderDataGraph::_metaspace_oom = false;
674
675 // Add a new class loader data node to the list. Assign the newly created
676 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
677 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
678 // We need to allocate all the oops for the ClassLoaderData before allocating the
679 // actual ClassLoaderData object.
680 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
681
682 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
683 // ClassLoaderData in the graph since the CLD
684 // contains unhandled oops
685
686 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
687
688
689 if (!is_anonymous) {
690 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
691 // First, Atomically set it
692 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
693 if (old != NULL) {
694 delete cld;
695 // Returns the data.
696 return old;
697 }
698 }
699
700 // We won the race, and therefore the task of adding the data to the list of
701 // class loader data
702 ClassLoaderData** list_head = &_head;
703 ClassLoaderData* next = _head;
704
705 do {
706 cld->set_next(next);
707 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
708 if (exchanged == next) {
709 if (log_is_enabled(Debug, class, loader, data)) {
710 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
711 log_creation(loader, cld, CHECK_NULL);
712 }
713 return cld;
714 }
715 next = exchanged;
716 } while (true);
717 }
718
719 void ClassLoaderDataGraph::log_creation(Handle loader, ClassLoaderData* cld, TRAPS) {
720 Handle string;
721 if (loader.not_null()) {
722 // Include the result of loader.toString() in the output. This allows
723 // the user of the log to identify the class loader instance.
724 JavaValue result(T_OBJECT);
725 KlassHandle spec_klass(THREAD, SystemDictionary::ClassLoader_klass());
726 JavaCalls::call_virtual(&result,
727 loader,
728 spec_klass,
729 vmSymbols::toString_name(),
730 vmSymbols::void_string_signature(),
731 CHECK);
732 assert(result.get_type() == T_OBJECT, "just checking");
733 string = (oop)result.get_jobject();
734 }
735
736 ResourceMark rm;
737 outputStream* log = Log(class, loader, data)::debug_stream();
738 log->print("create class loader data " INTPTR_FORMAT, p2i(cld));
739 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
740 cld->loader_name());
741
742 if (string.not_null()) {
743 log->print(": ");
744 java_lang_String::print(string(), log);
745 }
746 log->cr();
747 }
748
749
750 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
751 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
752 cld->oops_do(f, klass_closure, must_claim);
753 }
754 }
755
756 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
757 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
758 if (cld->keep_alive()) {
759 cld->oops_do(f, klass_closure, must_claim);
760 }
761 }
762 }
763
764 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
765 if (ClassUnloading) {
766 keep_alive_oops_do(f, klass_closure, must_claim);
767 } else {
768 oops_do(f, klass_closure, must_claim);
769 }
770 }
771
772 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
773 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
774 cl->do_cld(cld);
775 }
776 }
777
778 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
779 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
780 CLDClosure* closure = cld->keep_alive() ? strong : weak;
781 if (closure != NULL) {
782 closure->do_cld(cld);
783 }
784 }
785 }
786
787 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
788 roots_cld_do(cl, NULL);
789 }
790
791 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
792 if (ClassUnloading) {
793 keep_alive_cld_do(cl);
794 } else {
795 cld_do(cl);
796 }
797 }
798
799 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
800 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
801 cld->classes_do(klass_closure);
802 }
803 }
804
805 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
806 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
807 cld->classes_do(f);
808 }
809 }
810
811 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
812 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
813 cld->methods_do(f);
814 }
815 }
816
817 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
818 assert_locked_or_safepoint(Module_lock);
819 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
820 cld->modules_do(f);
821 }
822 }
823
824 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
825 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
826 // Only walk the head until any clds not purged from prior unloading
827 // (CMS doesn't purge right away).
828 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
829 assert(cld->is_unloading(), "invariant");
830 cld->modules_do(f);
831 }
832 }
833
834 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
835 assert_locked_or_safepoint(Module_lock);
836 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
837 cld->packages_do(f);
838 }
839 }
840
841 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
842 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
843 // Only walk the head until any clds not purged from prior unloading
844 // (CMS doesn't purge right away).
845 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
846 assert(cld->is_unloading(), "invariant");
847 cld->packages_do(f);
848 }
849 }
850
851 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
852 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
853 cld->loaded_classes_do(klass_closure);
854 }
855 }
856
857 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
858 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
859 // Only walk the head until any clds not purged from prior unloading
860 // (CMS doesn't purge right away).
861 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
862 assert(cld->is_unloading(), "invariant");
863 cld->classes_do(f);
864 }
865 }
866
867 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
868 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
869
870 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
871
872 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
873 ClassLoaderData* curr = _head;
874 while (curr != _saved_head) {
875 if (!curr->claimed()) {
876 array->push(curr);
877
878 if (log_is_enabled(Debug, class, loader, data)) {
879 outputStream* log = Log(class, loader, data)::debug_stream();
880 log->print("found new CLD: ");
881 curr->print_value_on(log);
882 log->cr();
883 }
884 }
885
886 curr = curr->_next;
887 }
888
889 return array;
890 }
891
892 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
893 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
894 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
895 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
896 return true;
897 }
898 }
899 return false;
900 }
901
902 #ifndef PRODUCT
903 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
904 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
905 if (loader_data == data) {
906 return true;
907 }
908 }
909
910 return false;
911 }
912 #endif // PRODUCT
913
914
915 // Move class loader data from main list to the unloaded list for unloading
916 // and deallocation later.
917 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
918 bool clean_previous_versions) {
919
920 ClassLoaderData* data = _head;
921 ClassLoaderData* prev = NULL;
922 bool seen_dead_loader = false;
923
924 // Mark metadata seen on the stack only so we can delete unneeded entries.
925 // Only walk all metadata, including the expensive code cache walk, for Full GC
926 // and only if class redefinition and if there's previous versions of
927 // Klasses to delete.
928 bool walk_all_metadata = clean_previous_versions &&
929 JvmtiExport::has_redefined_a_class() &&
930 InstanceKlass::has_previous_versions();
931 MetadataOnStackMark md_on_stack(walk_all_metadata);
932
933 // Save previous _unloading pointer for CMS which may add to unloading list before
934 // purging and we don't want to rewalk the previously unloaded class loader data.
935 _saved_unloading = _unloading;
936
937 data = _head;
938 while (data != NULL) {
939 if (data->is_alive(is_alive_closure)) {
940 if (data->packages_defined()) {
941 data->packages()->purge_all_package_exports();
942 }
943 if (data->modules_defined()) {
944 data->modules()->purge_all_module_reads();
945 }
946 // clean metaspace
947 if (walk_all_metadata) {
948 data->classes_do(InstanceKlass::purge_previous_versions);
949 }
950 data->free_deallocate_list();
951 prev = data;
952 data = data->next();
953 continue;
954 }
955 seen_dead_loader = true;
956 ClassLoaderData* dead = data;
957 dead->unload();
958 data = data->next();
959 // Remove from loader list.
960 // This class loader data will no longer be found
961 // in the ClassLoaderDataGraph.
962 if (prev != NULL) {
963 prev->set_next(data);
964 } else {
965 assert(dead == _head, "sanity check");
966 _head = data;
967 }
968 dead->set_next(_unloading);
969 _unloading = dead;
970 }
971
972 if (seen_dead_loader) {
973 post_class_unload_events();
974 }
975
976 return seen_dead_loader;
977 }
978
979 void ClassLoaderDataGraph::purge() {
980 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
981 ClassLoaderData* list = _unloading;
982 _unloading = NULL;
983 ClassLoaderData* next = list;
984 bool classes_unloaded = false;
985 while (next != NULL) {
986 ClassLoaderData* purge_me = next;
987 next = purge_me->next();
988 delete purge_me;
989 classes_unloaded = true;
990 }
991 if (classes_unloaded) {
992 Metaspace::purge();
993 set_metaspace_oom(false);
994 }
995 }
996
997 void ClassLoaderDataGraph::post_class_unload_events(void) {
998 #if INCLUDE_TRACE
999 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1000 if (Tracing::enabled()) {
1001 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1002 assert(_unloading != NULL, "need class loader data unload list!");
1003 _class_unload_time = Ticks::now();
1004 classes_unloading_do(&class_unload_event);
1005 }
1006 Tracing::on_unloading_classes();
1007 }
1008 #endif
1009 }
1010
1011 // CDS support
1012
1013 // Global metaspaces for writing information to the shared archive. When
1014 // application CDS is supported, we may need one per metaspace, so this
1015 // sort of looks like it.
1016 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
1017 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
1018 static bool _shared_metaspaces_initialized = false;
1019
1020 // Initialize shared metaspaces (change to call from somewhere not lazily)
1021 void ClassLoaderData::initialize_shared_metaspaces() {
1022 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
1023 assert(this == ClassLoaderData::the_null_class_loader_data(),
1024 "only supported for null loader data for now");
1025 assert (!_shared_metaspaces_initialized, "only initialize once");
1026 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
1027 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
1028 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
1029 _shared_metaspaces_initialized = true;
1030 }
1031
1032 Metaspace* ClassLoaderData::ro_metaspace() {
1033 assert(_ro_metaspace != NULL, "should already be initialized");
1034 return _ro_metaspace;
1035 }
1036
1037 Metaspace* ClassLoaderData::rw_metaspace() {
1038 assert(_rw_metaspace != NULL, "should already be initialized");
1039 return _rw_metaspace;
1040 }
1041
1042 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1043 : _next_klass(NULL) {
1044 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1045 Klass* klass = NULL;
1046
1047 // Find the first klass in the CLDG.
1048 while (cld != NULL) {
1049 klass = cld->_klasses;
1050 if (klass != NULL) {
1051 _next_klass = klass;
1052 return;
1053 }
1054 cld = cld->next();
1055 }
1056 }
1057
1058 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1059 Klass* next = klass->next_link();
1060 if (next != NULL) {
1061 return next;
1062 }
1063
1064 // No more klasses in the current CLD. Time to find a new CLD.
1065 ClassLoaderData* cld = klass->class_loader_data();
1066 while (next == NULL) {
1067 cld = cld->next();
1068 if (cld == NULL) {
1069 break;
1070 }
1071 next = cld->_klasses;
1072 }
1073
1074 return next;
1075 }
1076
1077 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1078 Klass* head = _next_klass;
1079
1080 while (head != NULL) {
1081 Klass* next = next_klass_in_cldg(head);
1082
1083 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
1084
1085 if (old_head == head) {
1086 return head; // Won the CAS.
1087 }
1088
1089 head = old_head;
1090 }
1091
1092 // Nothing more for the iterator to hand out.
1093 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1094 return NULL;
1095 }
1096
1097 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1098 _data = ClassLoaderDataGraph::_head;
1099 }
1100
1101 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1102
1103 #ifndef PRODUCT
1104 // callable from debugger
1105 extern "C" int print_loader_data_graph() {
1106 ClassLoaderDataGraph::dump_on(tty);
1107 return 0;
1108 }
1109
1110 void ClassLoaderDataGraph::verify() {
1111 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1112 data->verify();
1113 }
1114 }
1115
1116 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1117 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1118 data->dump(out);
1119 }
1120 MetaspaceAux::dump(out);
1121 }
1122 #endif // PRODUCT
1123
1124 void ClassLoaderData::print_value_on(outputStream* out) const {
1125 if (class_loader() == NULL) {
1126 out->print("NULL class_loader");
1127 } else {
1128 out->print("class loader " INTPTR_FORMAT, p2i(this));
1129 class_loader()->print_value_on(out);
1130 }
1131 }
1132
1133 #if INCLUDE_TRACE
1134
1135 Ticks ClassLoaderDataGraph::_class_unload_time;
1136
1137 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1138 assert(k != NULL, "invariant");
1139
1140 // post class unload event
1141 EventClassUnload event(UNTIMED);
1142 event.set_endtime(_class_unload_time);
1143 event.set_unloadedClass(k);
1144 oop defining_class_loader = k->class_loader();
1145 event.set_definingClassLoader(defining_class_loader != NULL ?
1146 defining_class_loader->klass() : (Klass*)NULL);
1147 event.commit();
1148 }
1149
1150 #endif // INCLUDE_TRACE