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