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.hpp"
67 #include "runtime/javaCalls.hpp"
68 #include "runtime/jniHandles.hpp"
69 #include "runtime/mutex.hpp"
70 #include "runtime/orderAccess.hpp"
71 #include "runtime/safepoint.hpp"
72 #include "runtime/synchronizer.hpp"
73 #include "utilities/growableArray.hpp"
74 #include "utilities/macros.hpp"
75 #include "utilities/ostream.hpp"
76 #if INCLUDE_TRACE
77 #include "trace/tracing.hpp"
78 #endif
79
80 // helper function to avoid in-line casts
81 template <typename T> static T* load_ptr_acquire(T* volatile *p) {
82 return static_cast<T*>(OrderAccess::load_ptr_acquire(p));
83 }
84
85 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
86
87 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
88 _class_loader(h_class_loader()),
89 _is_anonymous(is_anonymous),
90 // An anonymous class loader data doesn't have anything to keep
91 // it from being unloaded during parsing of the anonymous class.
92 // The null-class-loader should always be kept alive.
93 _keep_alive((is_anonymous || h_class_loader.is_null()) ? 1 : 0),
94 _metaspace(NULL), _unloading(false), _klasses(NULL),
95 _modules(NULL), _packages(NULL),
96 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
97 _next(NULL), _dependencies(dependencies), _shared_class_loader_id(-1),
98 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
99 Monitor::_safepoint_check_never)) {
100 TRACE_INIT_ID(this);
101 }
102
103 void ClassLoaderData::init_dependencies(TRAPS) {
104 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
105 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
106 _dependencies.init(CHECK);
107 }
108
109 void ClassLoaderData::Dependencies::init(TRAPS) {
110 // Create empty dependencies array to add to. CMS requires this to be
111 // an oop so that it can track additions via card marks. We think.
112 _list_head = oopFactory::new_objectArray(2, CHECK);
113 }
114
115 bool ClassLoaderData::claim() {
116 if (_claimed == 1) {
117 return false;
118 }
119
120 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
121 }
122
123 // Anonymous classes have their own ClassLoaderData that is marked to keep alive
124 // while the class is being parsed, and if the class appears on the module fixup list.
125 // Due to the uniqueness that no other class shares the anonymous class' name or
126 // ClassLoaderData, no other non-GC thread has knowledge of the anonymous class while
127 // it is being defined, therefore _keep_alive is not volatile or atomic.
128 void ClassLoaderData::inc_keep_alive() {
129 if (is_anonymous()) {
130 assert(_keep_alive >= 0, "Invalid keep alive increment count");
131 _keep_alive++;
132 }
133 }
134
135 void ClassLoaderData::dec_keep_alive() {
136 if (is_anonymous()) {
137 assert(_keep_alive > 0, "Invalid keep alive decrement count");
138 _keep_alive--;
139 }
140 }
141
142 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
143 if (must_claim && !claim()) {
144 return;
145 }
146
147 f->do_oop(&_class_loader);
148 _dependencies.oops_do(f);
149 if (_handles != NULL) {
150 _handles->oops_do(f);
151 }
152 if (klass_closure != NULL) {
153 classes_do(klass_closure);
154 }
155 }
156
157 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
158 f->do_oop((oop*)&_list_head);
159 }
160
161 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
162 // Lock-free access requires load_ptr_acquire
163 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
164 klass_closure->do_klass(k);
165 assert(k != k->next_link(), "no loops!");
166 }
167 }
168
169 void ClassLoaderData::classes_do(void f(Klass * const)) {
170 // Lock-free access requires load_ptr_acquire
171 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
172 f(k);
173 assert(k != k->next_link(), "no loops!");
174 }
175 }
176
177 void ClassLoaderData::methods_do(void f(Method*)) {
178 // Lock-free access requires load_ptr_acquire
179 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
180 if (k->is_instance_klass()) {
181 InstanceKlass::cast(k)->methods_do(f);
182 }
183 }
184 }
185
186 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
187 // Lock to avoid classes being modified/added/removed during iteration
188 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
189 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
190 // Do not filter ArrayKlass oops here...
191 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
192 klass_closure->do_klass(k);
193 }
194 }
195 }
196
197 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
198 // Lock-free access requires load_ptr_acquire
199 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
200 if (k->is_instance_klass()) {
201 f(InstanceKlass::cast(k));
202 }
203 assert(k != k->next_link(), "no loops!");
204 }
205 }
206
207 void ClassLoaderData::modules_do(void f(ModuleEntry*)) {
208 // Lock-free access requires load_ptr_acquire
209 ModuleEntryTable* modules = load_ptr_acquire(&_modules);
210 if (modules != NULL) {
211 for (int i = 0; i < modules->table_size(); i++) {
212 for (ModuleEntry* entry = modules->bucket(i);
213 entry != NULL;
214 entry = entry->next()) {
215 f(entry);
216 }
217 }
218 }
219 }
220
221 void ClassLoaderData::packages_do(void f(PackageEntry*)) {
222 // Lock-free access requires load_ptr_acquire
223 PackageEntryTable* packages = load_ptr_acquire(&_packages);
224 if (packages != NULL) {
225 for (int i = 0; i < packages->table_size(); i++) {
226 for (PackageEntry* entry = packages->bucket(i);
227 entry != NULL;
228 entry = entry->next()) {
229 f(entry);
230 }
231 }
232 }
233 }
234
235 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
236 assert(k != NULL, "invariant");
237
238 ClassLoaderData * const from_cld = this;
239 ClassLoaderData * const to_cld = k->class_loader_data();
240
241 // Dependency to the null class loader data doesn't need to be recorded
242 // because the null class loader data never goes away.
243 if (to_cld->is_the_null_class_loader_data()) {
244 return;
245 }
246
247 oop to;
248 if (to_cld->is_anonymous()) {
249 // Anonymous class dependencies are through the mirror.
250 to = k->java_mirror();
251 } else {
252 to = to_cld->class_loader();
253
254 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
255 // we still have to add it. The class_loader won't keep from_cld alive.
256 if (!from_cld->is_anonymous()) {
257 // Check that this dependency isn't from the same or parent class_loader
258 oop from = from_cld->class_loader();
259
260 oop curr = from;
261 while (curr != NULL) {
262 if (curr == to) {
263 return; // this class loader is in the parent list, no need to add it.
264 }
265 curr = java_lang_ClassLoader::parent(curr);
266 }
267 }
268 }
269
270 // It's a dependency we won't find through GC, add it. This is relatively rare
271 // Must handle over GC point.
272 Handle dependency(THREAD, to);
273 from_cld->_dependencies.add(dependency, CHECK);
274 }
275
276
277 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
278 // Check first if this dependency is already in the list.
279 // Save a pointer to the last to add to under the lock.
280 objArrayOop ok = _list_head;
281 objArrayOop last = NULL;
282 while (ok != NULL) {
283 last = ok;
284 if (ok->obj_at(0) == dependency()) {
285 // Don't need to add it
286 return;
287 }
288 ok = (objArrayOop)ok->obj_at(1);
289 }
290
291 // Must handle over GC points
292 assert (last != NULL, "dependencies should be initialized");
293 objArrayHandle last_handle(THREAD, last);
294
295 // Create a new dependency node with fields for (class_loader or mirror, next)
296 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
297 deps->obj_at_put(0, dependency());
298
299 // Must handle over GC points
300 objArrayHandle new_dependency(THREAD, deps);
301
302 // Add the dependency under lock
303 locked_add(last_handle, new_dependency, THREAD);
304 }
305
306 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
307 objArrayHandle new_dependency,
308 Thread* THREAD) {
309
310 // Have to lock and put the new dependency on the end of the dependency
311 // array so the card mark for CMS sees that this dependency is new.
312 // Can probably do this lock free with some effort.
313 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
314
315 oop loader_or_mirror = new_dependency->obj_at(0);
316
317 // Since the dependencies are only added, add to the end.
318 objArrayOop end = last_handle();
319 objArrayOop last = NULL;
320 while (end != NULL) {
321 last = end;
322 // check again if another thread added it to the end.
323 if (end->obj_at(0) == loader_or_mirror) {
324 // Don't need to add it
325 return;
326 }
327 end = (objArrayOop)end->obj_at(1);
328 }
329 assert (last != NULL, "dependencies should be initialized");
330 // fill in the first element with the oop in new_dependency.
331 if (last->obj_at(0) == NULL) {
332 last->obj_at_put(0, new_dependency->obj_at(0));
333 } else {
334 last->obj_at_put(1, new_dependency());
335 }
336 }
337
338 void ClassLoaderDataGraph::clear_claimed_marks() {
339 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
340 cld->clear_claimed();
341 }
342 }
343
344 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
345 {
346 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
347 Klass* old_value = _klasses;
348 k->set_next_link(old_value);
349 // Link the new item into the list, making sure the linked class is stable
350 // since the list can be walked without a lock
351 OrderAccess::release_store_ptr(&_klasses, k);
352 }
353
354 if (publicize && k->class_loader_data() != NULL) {
355 ResourceMark rm;
356 log_trace(class, loader, data)("Adding k: " PTR_FORMAT " %s to CLD: "
357 PTR_FORMAT " loader: " PTR_FORMAT " %s",
358 p2i(k),
359 k->external_name(),
360 p2i(k->class_loader_data()),
361 p2i((void *)k->class_loader()),
362 loader_name());
363 }
364 }
365
366 // Remove a klass from the _klasses list for scratch_class during redefinition
367 // or parsed class in the case of an error.
368 void ClassLoaderData::remove_class(Klass* scratch_class) {
369 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
370 Klass* prev = NULL;
371 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
372 if (k == scratch_class) {
373 if (prev == NULL) {
374 _klasses = k->next_link();
375 } else {
376 Klass* next = k->next_link();
377 prev->set_next_link(next);
378 }
379 return;
380 }
381 prev = k;
382 assert(k != k->next_link(), "no loops!");
383 }
384 ShouldNotReachHere(); // should have found this class!!
385 }
386
387 void ClassLoaderData::unload() {
388 _unloading = true;
389
390 // Tell serviceability tools these classes are unloading
391 classes_do(InstanceKlass::notify_unload_class);
392
393 if (log_is_enabled(Debug, class, loader, data)) {
394 ResourceMark rm;
395 outputStream* log = Log(class, loader, data)::debug_stream();
396 log->print(": unload loader data " INTPTR_FORMAT, p2i(this));
397 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
398 loader_name());
399 if (is_anonymous()) {
400 log->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
401 }
402 log->cr();
403 }
404
405 // In some rare cases items added to this list will not be freed elsewhere.
406 // To keep it simple, just free everything in it here.
407 free_deallocate_list();
408 }
409
410 PackageEntryTable* ClassLoaderData::packages() {
411 // Lazily create the package entry table at first request.
412 // Lock-free access requires load_ptr_acquire.
413 PackageEntryTable* packages = load_ptr_acquire(&_packages);
414 if (packages == NULL) {
415 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
416 // Check if _packages got allocated while we were waiting for this lock.
417 if ((packages = _packages) == NULL) {
418 packages = new PackageEntryTable(PackageEntryTable::_packagetable_entry_size);
419 // Ensure _packages is stable, since it is examined without a lock
420 OrderAccess::release_store_ptr(&_packages, packages);
421 }
422 }
423 return packages;
424 }
425
426 ModuleEntryTable* ClassLoaderData::modules() {
427 // Lazily create the module entry table at first request.
428 // Lock-free access requires load_ptr_acquire.
429 ModuleEntryTable* modules = load_ptr_acquire(&_modules);
430 if (modules == NULL) {
431 MutexLocker m1(Module_lock);
432 // Check if _modules got allocated while we were waiting for this lock.
433 if ((modules = _modules) == NULL) {
434 modules = new ModuleEntryTable(ModuleEntryTable::_moduletable_entry_size);
435 // Each loader has one unnamed module entry. Create it before
436 // any classes, loaded by this loader, are defined in case
437 // they end up being defined in loader's unnamed module.
438 modules->create_unnamed_module(this);
439
440 {
441 MutexLockerEx m1(metaspace_lock(), Mutex::_no_safepoint_check_flag);
442 // Ensure _modules is stable, since it is examined without a lock
443 OrderAccess::release_store_ptr(&_modules, modules);
444 }
445 }
446 }
447 return modules;
448 }
449
450 oop ClassLoaderData::keep_alive_object() const {
451 assert_locked_or_safepoint(_metaspace_lock);
452 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
453 return is_anonymous() ? _klasses->java_mirror() : class_loader();
454 }
455
456 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
457 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
458 || is_alive_closure->do_object_b(keep_alive_object());
459
460 return alive;
461 }
462
463
464 ClassLoaderData::~ClassLoaderData() {
465 // Release C heap structures for all the classes.
466 classes_do(InstanceKlass::release_C_heap_structures);
467
468 // Release C heap allocated hashtable for all the packages.
469 if (_packages != NULL) {
470 // Destroy the table itself
471 delete _packages;
472 _packages = NULL;
473 }
474
475 // Release C heap allocated hashtable for all the modules.
476 if (_modules != NULL) {
477 // Destroy the table itself
478 delete _modules;
479 _modules = NULL;
480 }
481
482 // release the metaspace
483 Metaspace *m = _metaspace;
484 if (m != NULL) {
485 _metaspace = NULL;
486 delete m;
487 }
488 // release the handles
489 if (_handles != NULL) {
490 JNIHandleBlock::release_block(_handles);
491 _handles = NULL;
492 }
493
494 // Clear all the JNI handles for methods
495 // These aren't deallocated and are going to look like a leak, but that's
496 // needed because we can't really get rid of jmethodIDs because we don't
497 // know when native code is going to stop using them. The spec says that
498 // they're "invalid" but existing programs likely rely on their being
499 // NULL after class unloading.
500 if (_jmethod_ids != NULL) {
501 Method::clear_jmethod_ids(this);
502 }
503 // Delete lock
504 delete _metaspace_lock;
505
506 // Delete free list
507 if (_deallocate_list != NULL) {
508 delete _deallocate_list;
509 }
510 }
511
512 // Returns true if this class loader data is for the system class loader.
513 bool ClassLoaderData::is_system_class_loader_data() const {
514 return SystemDictionary::is_system_class_loader(class_loader());
515 }
516
517 // Returns true if this class loader data is for the platform class loader.
518 bool ClassLoaderData::is_platform_class_loader_data() const {
519 return SystemDictionary::is_platform_class_loader(class_loader());
520 }
521
522 // Returns true if this class loader data is one of the 3 builtin
523 // (boot, application/system or platform) class loaders. Note, the
524 // builtin loaders are not freed by a GC.
525 bool ClassLoaderData::is_builtin_class_loader_data() const {
526 Handle classLoaderHandle = class_loader();
527 return (is_the_null_class_loader_data() ||
528 SystemDictionary::is_system_class_loader(classLoaderHandle) ||
529 SystemDictionary::is_platform_class_loader(classLoaderHandle));
530 }
531
532 Metaspace* ClassLoaderData::metaspace_non_null() {
533 assert(!DumpSharedSpaces, "wrong metaspace!");
534 // If the metaspace has not been allocated, create a new one. Might want
535 // to create smaller arena for Reflection class loaders also.
536 // The reason for the delayed allocation is because some class loaders are
537 // simply for delegating with no metadata of their own.
538 // Lock-free access requires load_ptr_acquire.
539 Metaspace* metaspace = load_ptr_acquire(&_metaspace);
540 if (metaspace == NULL) {
541 MutexLockerEx ml(_metaspace_lock, Mutex::_no_safepoint_check_flag);
542 // Check if _metaspace got allocated while we were waiting for this lock.
543 if ((metaspace = _metaspace) == NULL) {
544 if (this == the_null_class_loader_data()) {
545 assert (class_loader() == NULL, "Must be");
546 metaspace = new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType);
547 } else if (is_anonymous()) {
548 if (class_loader() != NULL) {
549 log_trace(class, loader, data)("is_anonymous: %s", class_loader()->klass()->internal_name());
550 }
551 metaspace = new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType);
552 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
553 if (class_loader() != NULL) {
554 log_trace(class, loader, data)("is_reflection: %s", class_loader()->klass()->internal_name());
555 }
556 metaspace = new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType);
557 } else {
558 metaspace = new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType);
559 }
560 // Ensure _metaspace is stable, since it is examined without a lock
561 OrderAccess::release_store_ptr(&_metaspace, metaspace);
562 }
563 }
564 return metaspace;
565 }
566
567 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
568 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
569
570 jobject ClassLoaderData::add_handle(Handle h) {
571 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
572 if (handles() == NULL) {
573 set_handles(JNIHandleBlock::allocate_block());
574 }
575 return handles()->allocate_handle(h());
576 }
577
578 void ClassLoaderData::remove_handle(jobject h) {
579 _handles->release_handle(h);
580 }
581
582 // Add this metadata pointer to be freed when it's safe. This is only during
583 // class unloading because Handles might point to this metadata field.
584 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
585 // Metadata in shared region isn't deleted.
586 if (!m->is_shared()) {
587 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
588 if (_deallocate_list == NULL) {
589 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
590 }
591 _deallocate_list->append_if_missing(m);
592 }
593 }
594
595 // Deallocate free metadata on the free list. How useful the PermGen was!
596 void ClassLoaderData::free_deallocate_list() {
597 // Don't need lock, at safepoint
598 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
599 if (_deallocate_list == NULL) {
600 return;
601 }
602 // Go backwards because this removes entries that are freed.
603 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
604 Metadata* m = _deallocate_list->at(i);
605 if (!m->on_stack()) {
606 _deallocate_list->remove_at(i);
607 // There are only three types of metadata that we deallocate directly.
608 // Cast them so they can be used by the template function.
609 if (m->is_method()) {
610 MetadataFactory::free_metadata(this, (Method*)m);
611 } else if (m->is_constantPool()) {
612 MetadataFactory::free_metadata(this, (ConstantPool*)m);
613 } else if (m->is_klass()) {
614 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
615 } else {
616 ShouldNotReachHere();
617 }
618 } else {
619 // Metadata is alive.
620 // If scratch_class is on stack then it shouldn't be on this list!
621 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
622 "scratch classes on this list should be dead");
623 // Also should assert that other metadata on the list was found in handles.
624 }
625 }
626 }
627
628 // These anonymous class loaders are to contain classes used for JSR292
629 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
630 // Add a new class loader data to the graph.
631 return ClassLoaderDataGraph::add(loader, true, THREAD);
632 }
633
634 const char* ClassLoaderData::loader_name() {
635 // Handles null class loader
636 return SystemDictionary::loader_name(class_loader());
637 }
638
639 #ifndef PRODUCT
640 // Define to dump klasses
641 #undef CLD_DUMP_KLASSES
642
643 void ClassLoaderData::dump(outputStream * const out) {
644 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
645 p2i(this), p2i((void *)class_loader()),
646 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
647 if (claimed()) out->print(" claimed ");
648 if (is_unloading()) out->print(" unloading ");
649 out->print(" handles " INTPTR_FORMAT, p2i(handles()));
650 out->cr();
651 if (metaspace_or_null() != NULL) {
652 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
653 metaspace_or_null()->dump(out);
654 } else {
655 out->print_cr("metaspace: NULL");
656 }
657
658 #ifdef CLD_DUMP_KLASSES
659 if (Verbose) {
660 Klass* k = _klasses;
661 while (k != NULL) {
662 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
663 k->has_modified_oops(), k->has_accumulated_modified_oops());
664 assert(k != k->next_link(), "no loops!");
665 k = k->next_link();
666 }
667 }
668 #endif // CLD_DUMP_KLASSES
669 #undef CLD_DUMP_KLASSES
670 if (_jmethod_ids != NULL) {
671 Method::print_jmethod_ids(this, out);
672 }
673 out->print_cr("}");
674 }
675 #endif // PRODUCT
676
677 void ClassLoaderData::verify() {
678 assert_locked_or_safepoint(_metaspace_lock);
679 oop cl = class_loader();
680
681 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
682 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
683
684 // Verify the integrity of the allocated space.
685 if (metaspace_or_null() != NULL) {
686 metaspace_or_null()->verify();
687 }
688
689 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
690 guarantee(k->class_loader_data() == this, "Must be the same");
691 k->verify();
692 assert(k != k->next_link(), "no loops!");
693 }
694 }
695
696 bool ClassLoaderData::contains_klass(Klass* klass) {
697 // Lock-free access requires load_ptr_acquire
698 for (Klass* k = load_ptr_acquire(&_klasses); k != NULL; k = k->next_link()) {
699 if (k == klass) return true;
700 }
701 return false;
702 }
703
704
705 // GC root of class loader data created.
706 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
707 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
708 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
709 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
710
711 bool ClassLoaderDataGraph::_should_purge = false;
712 bool ClassLoaderDataGraph::_metaspace_oom = false;
713
714 // Add a new class loader data node to the list. Assign the newly created
715 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
716 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
717 // We need to allocate all the oops for the ClassLoaderData before allocating the
718 // actual ClassLoaderData object.
719 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
720
721 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
722 // ClassLoaderData in the graph since the CLD
723 // contains unhandled oops
724
725 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
726
727
728 if (!is_anonymous) {
729 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
730 // First, Atomically set it
731 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
732 if (old != NULL) {
733 delete cld;
734 // Returns the data.
735 return old;
736 }
737 }
738
739 // We won the race, and therefore the task of adding the data to the list of
740 // class loader data
741 ClassLoaderData** list_head = &_head;
742 ClassLoaderData* next = _head;
743
744 do {
745 cld->set_next(next);
746 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
747 if (exchanged == next) {
748 if (log_is_enabled(Debug, class, loader, data)) {
749 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
750 log_creation(loader, cld, CHECK_NULL);
751 }
752 return cld;
753 }
754 next = exchanged;
755 } while (true);
756 }
757
758 void ClassLoaderDataGraph::log_creation(Handle loader, ClassLoaderData* cld, TRAPS) {
759 Handle string;
760 if (loader.not_null()) {
761 // Include the result of loader.toString() in the output. This allows
762 // the user of the log to identify the class loader instance.
763 JavaValue result(T_OBJECT);
764 KlassHandle spec_klass(THREAD, SystemDictionary::ClassLoader_klass());
765 JavaCalls::call_virtual(&result,
766 loader,
767 spec_klass,
768 vmSymbols::toString_name(),
769 vmSymbols::void_string_signature(),
770 CHECK);
771 assert(result.get_type() == T_OBJECT, "just checking");
772 string = (oop)result.get_jobject();
773 }
774
775 ResourceMark rm;
776 outputStream* log = Log(class, loader, data)::debug_stream();
777 log->print("create class loader data " INTPTR_FORMAT, p2i(cld));
778 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
779 cld->loader_name());
780
781 if (string.not_null()) {
782 log->print(": ");
783 java_lang_String::print(string(), log);
784 }
785 log->cr();
786 }
787
788
789 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
790 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
791 cld->oops_do(f, klass_closure, must_claim);
792 }
793 }
794
795 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
796 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
797 if (cld->keep_alive()) {
798 cld->oops_do(f, klass_closure, must_claim);
799 }
800 }
801 }
802
803 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
804 if (ClassUnloading) {
805 keep_alive_oops_do(f, klass_closure, must_claim);
806 } else {
807 oops_do(f, klass_closure, must_claim);
808 }
809 }
810
811 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
812 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
813 cl->do_cld(cld);
814 }
815 }
816
817 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
818 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
819 // Only walk the head until any clds not purged from prior unloading
820 // (CMS doesn't purge right away).
821 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
822 assert(cld->is_unloading(), "invariant");
823 cl->do_cld(cld);
824 }
825 }
826
827 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
828 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
829 CLDClosure* closure = cld->keep_alive() ? strong : weak;
830 if (closure != NULL) {
831 closure->do_cld(cld);
832 }
833 }
834 }
835
836 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
837 roots_cld_do(cl, NULL);
838 }
839
840 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
841 if (ClassUnloading) {
842 keep_alive_cld_do(cl);
843 } else {
844 cld_do(cl);
845 }
846 }
847
848 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
849 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
850 cld->classes_do(klass_closure);
851 }
852 }
853
854 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
855 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
856 cld->classes_do(f);
857 }
858 }
859
860 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
861 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
862 cld->methods_do(f);
863 }
864 }
865
866 void ClassLoaderDataGraph::modules_do(void f(ModuleEntry*)) {
867 assert_locked_or_safepoint(Module_lock);
868 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
869 cld->modules_do(f);
870 }
871 }
872
873 void ClassLoaderDataGraph::modules_unloading_do(void f(ModuleEntry*)) {
874 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
875 // Only walk the head until any clds not purged from prior unloading
876 // (CMS doesn't purge right away).
877 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
878 assert(cld->is_unloading(), "invariant");
879 cld->modules_do(f);
880 }
881 }
882
883 void ClassLoaderDataGraph::packages_do(void f(PackageEntry*)) {
884 assert_locked_or_safepoint(Module_lock);
885 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
886 cld->packages_do(f);
887 }
888 }
889
890 void ClassLoaderDataGraph::packages_unloading_do(void f(PackageEntry*)) {
891 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
892 // Only walk the head until any clds not purged from prior unloading
893 // (CMS doesn't purge right away).
894 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
895 assert(cld->is_unloading(), "invariant");
896 cld->packages_do(f);
897 }
898 }
899
900 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
901 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
902 cld->loaded_classes_do(klass_closure);
903 }
904 }
905
906 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
907 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
908 // Only walk the head until any clds not purged from prior unloading
909 // (CMS doesn't purge right away).
910 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
911 assert(cld->is_unloading(), "invariant");
912 cld->classes_do(f);
913 }
914 }
915
916 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
917 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
918
919 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
920
921 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
922 ClassLoaderData* curr = _head;
923 while (curr != _saved_head) {
924 if (!curr->claimed()) {
925 array->push(curr);
926
927 if (log_is_enabled(Debug, class, loader, data)) {
928 outputStream* log = Log(class, loader, data)::debug_stream();
929 log->print("found new CLD: ");
930 curr->print_value_on(log);
931 log->cr();
932 }
933 }
934
935 curr = curr->_next;
936 }
937
938 return array;
939 }
940
941 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
942 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
943 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
944 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
945 return true;
946 }
947 }
948 return false;
949 }
950
951 #ifndef PRODUCT
952 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
953 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
954 if (loader_data == data) {
955 return true;
956 }
957 }
958
959 return false;
960 }
961 #endif // PRODUCT
962
963
964 // Move class loader data from main list to the unloaded list for unloading
965 // and deallocation later.
966 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
967 bool clean_previous_versions) {
968
969 ClassLoaderData* data = _head;
970 ClassLoaderData* prev = NULL;
971 bool seen_dead_loader = false;
972
973 // Mark metadata seen on the stack only so we can delete unneeded entries.
974 // Only walk all metadata, including the expensive code cache walk, for Full GC
975 // and only if class redefinition and if there's previous versions of
976 // Klasses to delete.
977 bool walk_all_metadata = clean_previous_versions &&
978 JvmtiExport::has_redefined_a_class() &&
979 InstanceKlass::has_previous_versions_and_reset();
980 MetadataOnStackMark md_on_stack(walk_all_metadata);
981
982 // Save previous _unloading pointer for CMS which may add to unloading list before
983 // purging and we don't want to rewalk the previously unloaded class loader data.
984 _saved_unloading = _unloading;
985
986 data = _head;
987 while (data != NULL) {
988 if (data->is_alive(is_alive_closure)) {
989 // clean metaspace
990 if (walk_all_metadata) {
991 data->classes_do(InstanceKlass::purge_previous_versions);
992 }
993 data->free_deallocate_list();
994 prev = data;
995 data = data->next();
996 continue;
997 }
998 seen_dead_loader = true;
999 ClassLoaderData* dead = data;
1000 dead->unload();
1001 data = data->next();
1002 // Remove from loader list.
1003 // This class loader data will no longer be found
1004 // in the ClassLoaderDataGraph.
1005 if (prev != NULL) {
1006 prev->set_next(data);
1007 } else {
1008 assert(dead == _head, "sanity check");
1009 _head = data;
1010 }
1011 dead->set_next(_unloading);
1012 _unloading = dead;
1013 }
1014
1015 if (seen_dead_loader) {
1016 // Walk a ModuleEntry's reads and a PackageEntry's exports lists
1017 // to determine if there are modules on those lists that are now
1018 // dead and should be removed. A module's life cycle is equivalent
1019 // to its defining class loader's life cycle. Since a module is
1020 // considered dead if its class loader is dead, these walks must
1021 // occur after each class loader's aliveness is determined.
1022 data = _head;
1023 while (data != NULL) {
1024 if (data->packages_defined()) {
1025 data->packages()->purge_all_package_exports();
1026 }
1027 if (data->modules_defined()) {
1028 data->modules()->purge_all_module_reads();
1029 }
1030 data = data->next();
1031 }
1032
1033 post_class_unload_events();
1034 }
1035
1036 return seen_dead_loader;
1037 }
1038
1039 void ClassLoaderDataGraph::purge() {
1040 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1041 ClassLoaderData* list = _unloading;
1042 _unloading = NULL;
1043 ClassLoaderData* next = list;
1044 bool classes_unloaded = false;
1045 while (next != NULL) {
1046 ClassLoaderData* purge_me = next;
1047 next = purge_me->next();
1048 delete purge_me;
1049 classes_unloaded = true;
1050 }
1051 if (classes_unloaded) {
1052 Metaspace::purge();
1053 set_metaspace_oom(false);
1054 }
1055 }
1056
1057 void ClassLoaderDataGraph::post_class_unload_events() {
1058 #if INCLUDE_TRACE
1059 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
1060 if (Tracing::enabled()) {
1061 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
1062 assert(_unloading != NULL, "need class loader data unload list!");
1063 _class_unload_time = Ticks::now();
1064 classes_unloading_do(&class_unload_event);
1065 }
1066 Tracing::on_unloading_classes();
1067 }
1068 #endif
1069 }
1070
1071 // CDS support
1072
1073 // Global metaspaces for writing information to the shared archive. When
1074 // application CDS is supported, we may need one per metaspace, so this
1075 // sort of looks like it.
1076 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
1077 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
1078 static bool _shared_metaspaces_initialized = false;
1079
1080 // Initialize shared metaspaces (change to call from somewhere not lazily)
1081 void ClassLoaderData::initialize_shared_metaspaces() {
1082 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
1083 assert(this == ClassLoaderData::the_null_class_loader_data(),
1084 "only supported for null loader data for now");
1085 assert (!_shared_metaspaces_initialized, "only initialize once");
1086 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
1087 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
1088 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
1089 _shared_metaspaces_initialized = true;
1090 }
1091
1092 Metaspace* ClassLoaderData::ro_metaspace() {
1093 assert(_ro_metaspace != NULL, "should already be initialized");
1094 return _ro_metaspace;
1095 }
1096
1097 Metaspace* ClassLoaderData::rw_metaspace() {
1098 assert(_rw_metaspace != NULL, "should already be initialized");
1099 return _rw_metaspace;
1100 }
1101
1102 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
1103 : _next_klass(NULL) {
1104 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
1105 Klass* klass = NULL;
1106
1107 // Find the first klass in the CLDG.
1108 while (cld != NULL) {
1109 assert_locked_or_safepoint(cld->metaspace_lock());
1110 klass = cld->_klasses;
1111 if (klass != NULL) {
1112 _next_klass = klass;
1113 return;
1114 }
1115 cld = cld->next();
1116 }
1117 }
1118
1119 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
1120 Klass* next = klass->next_link();
1121 if (next != NULL) {
1122 return next;
1123 }
1124
1125 // No more klasses in the current CLD. Time to find a new CLD.
1126 ClassLoaderData* cld = klass->class_loader_data();
1127 assert_locked_or_safepoint(cld->metaspace_lock());
1128 while (next == NULL) {
1129 cld = cld->next();
1130 if (cld == NULL) {
1131 break;
1132 }
1133 next = cld->_klasses;
1134 }
1135
1136 return next;
1137 }
1138
1139 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
1140 Klass* head = _next_klass;
1141
1142 while (head != NULL) {
1143 Klass* next = next_klass_in_cldg(head);
1144
1145 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
1146
1147 if (old_head == head) {
1148 return head; // Won the CAS.
1149 }
1150
1151 head = old_head;
1152 }
1153
1154 // Nothing more for the iterator to hand out.
1155 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
1156 return NULL;
1157 }
1158
1159 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
1160 _data = ClassLoaderDataGraph::_head;
1161 }
1162
1163 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
1164
1165 #ifndef PRODUCT
1166 // callable from debugger
1167 extern "C" int print_loader_data_graph() {
1168 ClassLoaderDataGraph::dump_on(tty);
1169 return 0;
1170 }
1171
1172 void ClassLoaderDataGraph::verify() {
1173 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1174 data->verify();
1175 }
1176 }
1177
1178 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
1179 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
1180 data->dump(out);
1181 }
1182 MetaspaceAux::dump(out);
1183 }
1184 #endif // PRODUCT
1185
1186 void ClassLoaderData::print_value_on(outputStream* out) const {
1187 if (class_loader() == NULL) {
1188 out->print("NULL class_loader");
1189 } else {
1190 out->print("class loader " INTPTR_FORMAT " ", p2i(this));
1191 class_loader()->print_value_on(out);
1192 }
1193 }
1194
1195 #if INCLUDE_TRACE
1196
1197 Ticks ClassLoaderDataGraph::_class_unload_time;
1198
1199 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1200 assert(k != NULL, "invariant");
1201
1202 // post class unload event
1203 EventClassUnload event(UNTIMED);
1204 event.set_endtime(_class_unload_time);
1205 event.set_unloadedClass(k);
1206 event.set_definingClassLoader(k->class_loader_data());
1207 event.commit();
1208 }
1209
1210 #endif // INCLUDE_TRACE