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