1 /*
2 * Copyright (c) 2012, 2014, 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 // extension, 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/systemDictionary.hpp"
55 #include "code/codeCache.hpp"
56 #include "memory/gcLocker.hpp"
57 #include "memory/metadataFactory.hpp"
58 #include "memory/metaspaceShared.hpp"
59 #include "memory/oopFactory.hpp"
60 #include "runtime/jniHandles.hpp"
61 #include "runtime/mutex.hpp"
62 #include "runtime/safepoint.hpp"
63 #include "runtime/synchronizer.hpp"
64 #include "utilities/growableArray.hpp"
65 #include "utilities/macros.hpp"
66 #include "utilities/ostream.hpp"
67
68 #if INCLUDE_TRACE
69 #include "trace/tracing.hpp"
70 #endif
71
72 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
73
74 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
75 _class_loader(h_class_loader()),
76 _is_anonymous(is_anonymous),
77 // An anonymous class loader data doesn't have anything to keep
78 // it from being unloaded during parsing of the anonymous class.
79 // The null-class-loader should always be kept alive.
80 _keep_alive(is_anonymous || h_class_loader.is_null()),
81 _metaspace(NULL), _unloading(false), _klasses(NULL),
82 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
83 _next(NULL), _dependencies(dependencies),
84 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {
85 // empty
86 }
87
88 void ClassLoaderData::init_dependencies(TRAPS) {
89 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
90 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
91 _dependencies.init(CHECK);
92 }
93
94 void ClassLoaderData::Dependencies::init(TRAPS) {
95 // Create empty dependencies array to add to. CMS requires this to be
96 // an oop so that it can track additions via card marks. We think.
97 _list_head = oopFactory::new_objectArray(2, CHECK);
98 }
99
100 bool ClassLoaderData::claim() {
101 if (_claimed == 1) {
102 return false;
103 }
104
105 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
106 }
107
108 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
109 if (must_claim && !claim()) {
110 return;
111 }
112
113 f->do_oop(&_class_loader);
114 _dependencies.oops_do(f);
115 _handles->oops_do(f);
116 if (klass_closure != NULL) {
117 classes_do(klass_closure);
118 }
119 }
120
121 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
122 f->do_oop((oop*)&_list_head);
123 }
124
125 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
126 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
127 klass_closure->do_klass(k);
128 assert(k != k->next_link(), "no loops!");
129 }
130 }
131
132 void ClassLoaderData::classes_do(void f(Klass * const)) {
133 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
134 f(k);
135 }
136 }
137
138 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
139 // Lock to avoid classes being modified/added/removed during iteration
140 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
141 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
142 // Do not filter ArrayKlass oops here...
143 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) {
144 klass_closure->do_klass(k);
145 }
146 }
147 }
148
149 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
150 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
151 if (k->oop_is_instance()) {
152 f(InstanceKlass::cast(k));
153 }
154 assert(k != k->next_link(), "no loops!");
155 }
156 }
157
158 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
159 ClassLoaderData * const from_cld = this;
160 ClassLoaderData * const to_cld = k->class_loader_data();
161
162 // Dependency to the null class loader data doesn't need to be recorded
163 // because the null class loader data never goes away.
164 if (to_cld->is_the_null_class_loader_data()) {
165 return;
166 }
167
168 oop to;
169 if (to_cld->is_anonymous()) {
170 // Anonymous class dependencies are through the mirror.
171 to = k->java_mirror();
172 } else {
173 to = to_cld->class_loader();
174
175 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
176 // we still have to add it. The class_loader won't keep from_cld alive.
177 if (!from_cld->is_anonymous()) {
178 // Check that this dependency isn't from the same or parent class_loader
179 oop from = from_cld->class_loader();
180
181 oop curr = from;
182 while (curr != NULL) {
183 if (curr == to) {
184 return; // this class loader is in the parent list, no need to add it.
185 }
186 curr = java_lang_ClassLoader::parent(curr);
187 }
188 }
189 }
190
191 // It's a dependency we won't find through GC, add it. This is relatively rare
192 // Must handle over GC point.
193 Handle dependency(THREAD, to);
194 from_cld->_dependencies.add(dependency, CHECK);
195 }
196
197
198 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
199 // Check first if this dependency is already in the list.
200 // Save a pointer to the last to add to under the lock.
201 objArrayOop ok = _list_head;
202 objArrayOop last = NULL;
203 while (ok != NULL) {
204 last = ok;
205 if (ok->obj_at(0) == dependency()) {
206 // Don't need to add it
207 return;
208 }
209 ok = (objArrayOop)ok->obj_at(1);
210 }
211
212 // Must handle over GC points
213 assert (last != NULL, "dependencies should be initialized");
214 objArrayHandle last_handle(THREAD, last);
215
216 // Create a new dependency node with fields for (class_loader or mirror, next)
217 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
218 deps->obj_at_put(0, dependency());
219
220 // Must handle over GC points
221 objArrayHandle new_dependency(THREAD, deps);
222
223 // Add the dependency under lock
224 locked_add(last_handle, new_dependency, THREAD);
225 }
226
227 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
228 objArrayHandle new_dependency,
229 Thread* THREAD) {
230
231 // Have to lock and put the new dependency on the end of the dependency
232 // array so the card mark for CMS sees that this dependency is new.
233 // Can probably do this lock free with some effort.
234 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
235
236 oop loader_or_mirror = new_dependency->obj_at(0);
237
238 // Since the dependencies are only added, add to the end.
239 objArrayOop end = last_handle();
240 objArrayOop last = NULL;
241 while (end != NULL) {
242 last = end;
243 // check again if another thread added it to the end.
244 if (end->obj_at(0) == loader_or_mirror) {
245 // Don't need to add it
246 return;
247 }
248 end = (objArrayOop)end->obj_at(1);
249 }
250 assert (last != NULL, "dependencies should be initialized");
251 // fill in the first element with the oop in new_dependency.
252 if (last->obj_at(0) == NULL) {
253 last->obj_at_put(0, new_dependency->obj_at(0));
254 } else {
255 last->obj_at_put(1, new_dependency());
256 }
257 }
258
259 void ClassLoaderDataGraph::clear_claimed_marks() {
260 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
261 cld->clear_claimed();
262 }
263 }
264
265 void ClassLoaderData::add_class(Klass* k) {
266 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
267 Klass* old_value = _klasses;
268 k->set_next_link(old_value);
269 // link the new item into the list
270 _klasses = k;
271
272 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
273 ResourceMark rm;
274 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
275 PTR_FORMAT " loader: " PTR_FORMAT " %s",
276 p2i(k),
277 k->external_name(),
278 p2i(k->class_loader_data()),
279 p2i((void *)k->class_loader()),
280 loader_name());
281 }
282 }
283
284 // This is called by InstanceKlass::deallocate_contents() to remove the
285 // scratch_class for redefine classes. We need a lock because there it may not
286 // be called at a safepoint if there's an error.
287 void ClassLoaderData::remove_class(Klass* scratch_class) {
288 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
289 Klass* prev = NULL;
290 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
291 if (k == scratch_class) {
292 if (prev == NULL) {
293 _klasses = k->next_link();
294 } else {
295 Klass* next = k->next_link();
296 prev->set_next_link(next);
297 }
298 return;
299 }
300 prev = k;
301 assert(k != k->next_link(), "no loops!");
302 }
303 ShouldNotReachHere(); // should have found this class!!
304 }
305
306 void ClassLoaderData::unload() {
307 _unloading = true;
308
309 // Tell serviceability tools these classes are unloading
310 classes_do(InstanceKlass::notify_unload_class);
311
312 if (TraceClassLoaderData) {
313 ResourceMark rm;
314 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this));
315 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
316 loader_name());
317 if (is_anonymous()) {
318 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
319 }
320 tty->print_cr("]");
321 }
322 }
323
324 #ifdef ASSERT
325 class AllAliveClosure : public OopClosure {
326 BoolObjectClosure* _is_alive_closure;
327 bool _found_dead;
328 public:
329 AllAliveClosure(BoolObjectClosure* is_alive_closure) : _is_alive_closure(is_alive_closure), _found_dead(false) {}
330 template <typename T> void do_oop_work(T* p) {
331 T heap_oop = oopDesc::load_heap_oop(p);
332 if (!oopDesc::is_null(heap_oop)) {
333 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
334 if (!_is_alive_closure->do_object_b(obj)) {
335 _found_dead = true;
336 }
337 }
338 }
339 void do_oop(oop* p) { do_oop_work<oop>(p); }
340 void do_oop(narrowOop* p) { do_oop_work<narrowOop>(p); }
341 bool found_dead() { return _found_dead; }
342 };
343 #endif
344
345 oop ClassLoaderData::keep_alive_object() const {
346 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
347 return is_anonymous() ? _klasses->java_mirror() : class_loader();
348 }
349
350 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
351 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
352 || is_alive_closure->do_object_b(keep_alive_object());
353
354 #ifdef ASSERT
355 if (alive) {
356 AllAliveClosure all_alive_closure(is_alive_closure);
357 KlassToOopClosure klass_closure(&all_alive_closure);
358 const_cast<ClassLoaderData*>(this)->oops_do(&all_alive_closure, &klass_closure, false);
359 assert(!all_alive_closure.found_dead(), err_msg("Found dead oop in alive cld: " PTR_FORMAT, p2i(this)));
360 }
361 #endif
362
363 return alive;
364 }
365
366
367 ClassLoaderData::~ClassLoaderData() {
368 // Release C heap structures for all the classes.
369 classes_do(InstanceKlass::release_C_heap_structures);
370
371 Metaspace *m = _metaspace;
372 if (m != NULL) {
373 _metaspace = NULL;
374 // release the metaspace
375 delete m;
376 // release the handles
377 if (_handles != NULL) {
378 JNIHandleBlock::release_block(_handles);
379 _handles = NULL;
380 }
381 }
382
383 // Clear all the JNI handles for methods
384 // These aren't deallocated and are going to look like a leak, but that's
385 // needed because we can't really get rid of jmethodIDs because we don't
386 // know when native code is going to stop using them. The spec says that
387 // they're "invalid" but existing programs likely rely on their being
388 // NULL after class unloading.
389 if (_jmethod_ids != NULL) {
390 Method::clear_jmethod_ids(this);
391 }
392 // Delete lock
393 delete _metaspace_lock;
394
395 // Delete free list
396 if (_deallocate_list != NULL) {
397 delete _deallocate_list;
398 }
399 }
400
401 /**
402 * Returns true if this class loader data is for the extension class loader.
403 */
404 bool ClassLoaderData::is_ext_class_loader_data() const {
405 return SystemDictionary::is_ext_class_loader(class_loader());
406 }
407
408 Metaspace* ClassLoaderData::metaspace_non_null() {
409 assert(!DumpSharedSpaces, "wrong metaspace!");
410 // If the metaspace has not been allocated, create a new one. Might want
411 // to create smaller arena for Reflection class loaders also.
412 // The reason for the delayed allocation is because some class loaders are
413 // simply for delegating with no metadata of their own.
414 if (_metaspace == NULL) {
415 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
416 // Check again if metaspace has been allocated while we were getting this lock.
417 if (_metaspace != NULL) {
418 return _metaspace;
419 }
420 if (this == the_null_class_loader_data()) {
421 assert (class_loader() == NULL, "Must be");
422 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
423 } else if (is_anonymous()) {
424 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
425 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
426 }
427 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
428 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
429 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
430 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
431 }
432 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
433 } else {
434 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
435 }
436 }
437 return _metaspace;
438 }
439
440 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
441 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
442
443 jobject ClassLoaderData::add_handle(Handle h) {
444 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
445 if (handles() == NULL) {
446 set_handles(JNIHandleBlock::allocate_block());
447 }
448 return handles()->allocate_handle(h());
449 }
450
451 // Add this metadata pointer to be freed when it's safe. This is only during
452 // class unloading because Handles might point to this metadata field.
453 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
454 // Metadata in shared region isn't deleted.
455 if (!m->is_shared()) {
456 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
457 if (_deallocate_list == NULL) {
458 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
459 }
460 _deallocate_list->append_if_missing(m);
461 }
462 }
463
464 // Deallocate free metadata on the free list. How useful the PermGen was!
465 void ClassLoaderData::free_deallocate_list() {
466 // Don't need lock, at safepoint
467 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
468 if (_deallocate_list == NULL) {
469 return;
470 }
471 // Go backwards because this removes entries that are freed.
472 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
473 Metadata* m = _deallocate_list->at(i);
474 if (!m->on_stack()) {
475 _deallocate_list->remove_at(i);
476 // There are only three types of metadata that we deallocate directly.
477 // Cast them so they can be used by the template function.
478 if (m->is_method()) {
479 MetadataFactory::free_metadata(this, (Method*)m);
480 } else if (m->is_constantPool()) {
481 MetadataFactory::free_metadata(this, (ConstantPool*)m);
482 } else if (m->is_klass()) {
483 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
484 } else {
485 ShouldNotReachHere();
486 }
487 }
488 }
489 }
490
491 // These anonymous class loaders are to contain classes used for JSR292
492 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
493 // Add a new class loader data to the graph.
494 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL);
495 }
496
497 const char* ClassLoaderData::loader_name() {
498 // Handles null class loader
499 return SystemDictionary::loader_name(class_loader());
500 }
501
502 #ifndef PRODUCT
503 // Define to dump klasses
504 #undef CLD_DUMP_KLASSES
505
506 void ClassLoaderData::dump(outputStream * const out) {
507 ResourceMark rm;
508 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {",
509 p2i(this), p2i((void *)class_loader()),
510 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
511 if (claimed()) out->print(" claimed ");
512 if (is_unloading()) out->print(" unloading ");
513 out->print(" handles " INTPTR_FORMAT, p2i(handles()));
514 out->cr();
515 if (metaspace_or_null() != NULL) {
516 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
517 metaspace_or_null()->dump(out);
518 } else {
519 out->print_cr("metaspace: NULL");
520 }
521
522 #ifdef CLD_DUMP_KLASSES
523 if (Verbose) {
524 ResourceMark rm;
525 Klass* k = _klasses;
526 while (k != NULL) {
527 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
528 k->has_modified_oops(), k->has_accumulated_modified_oops());
529 assert(k != k->next_link(), "no loops!");
530 k = k->next_link();
531 }
532 }
533 #endif // CLD_DUMP_KLASSES
534 #undef CLD_DUMP_KLASSES
535 if (_jmethod_ids != NULL) {
536 Method::print_jmethod_ids(this, out);
537 }
538 out->print_cr("}");
539 }
540 #endif // PRODUCT
541
542 void ClassLoaderData::verify() {
543 oop cl = class_loader();
544
545 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
546 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
547
548 // Verify the integrity of the allocated space.
549 if (metaspace_or_null() != NULL) {
550 metaspace_or_null()->verify();
551 }
552
553 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
554 guarantee(k->class_loader_data() == this, "Must be the same");
555 k->verify();
556 assert(k != k->next_link(), "no loops!");
557 }
558 }
559
560 bool ClassLoaderData::contains_klass(Klass* klass) {
561 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
562 if (k == klass) return true;
563 }
564 return false;
565 }
566
567
568 // GC root of class loader data created.
569 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
570 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
571 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
572 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
573
574 bool ClassLoaderDataGraph::_should_purge = false;
575
576 // Add a new class loader data node to the list. Assign the newly created
577 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
578 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
579 // We need to allocate all the oops for the ClassLoaderData before allocating the
580 // actual ClassLoaderData object.
581 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
582
583 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
584 // ClassLoaderData in the graph since the CLD
585 // contains unhandled oops
586
587 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
588
589
590 if (!is_anonymous) {
591 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
592 // First, Atomically set it
593 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
594 if (old != NULL) {
595 delete cld;
596 // Returns the data.
597 return old;
598 }
599 }
600
601 // We won the race, and therefore the task of adding the data to the list of
602 // class loader data
603 ClassLoaderData** list_head = &_head;
604 ClassLoaderData* next = _head;
605
606 do {
607 cld->set_next(next);
608 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
609 if (exchanged == next) {
610 if (TraceClassLoaderData) {
611 ResourceMark rm;
612 tty->print("[ClassLoaderData: ");
613 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld));
614 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
615 cld->loader_name());
616 tty->print_cr("]");
617 }
618 return cld;
619 }
620 next = exchanged;
621 } while (true);
622
623 }
624
625 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
626 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
627 cld->oops_do(f, klass_closure, must_claim);
628 }
629 }
630
631 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
632 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
633 if (cld->keep_alive()) {
634 cld->oops_do(f, klass_closure, must_claim);
635 }
636 }
637 }
638
639 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
640 if (ClassUnloading) {
641 keep_alive_oops_do(f, klass_closure, must_claim);
642 } else {
643 oops_do(f, klass_closure, must_claim);
644 }
645 }
646
647 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
648 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
649 cl->do_cld(cld);
650 }
651 }
652
653 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
654 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
655 CLDClosure* closure = cld->keep_alive() ? strong : weak;
656 if (closure != NULL) {
657 closure->do_cld(cld);
658 }
659 }
660 }
661
662 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
663 roots_cld_do(cl, NULL);
664 }
665
666 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
667 if (ClassUnloading) {
668 keep_alive_cld_do(cl);
669 } else {
670 cld_do(cl);
671 }
672 }
673
674 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
675 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
676 cld->classes_do(klass_closure);
677 }
678 }
679
680 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
681 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
682 cld->classes_do(f);
683 }
684 }
685
686 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
687 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
688 cld->loaded_classes_do(klass_closure);
689 }
690 }
691
692 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
693 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
694 // Only walk the head until any clds not purged from prior unloading
695 // (CMS doesn't purge right away).
696 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
697 cld->classes_do(f);
698 }
699 }
700
701 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
702 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
703
704 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
705
706 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
707 ClassLoaderData* curr = _head;
708 while (curr != _saved_head) {
709 if (!curr->claimed()) {
710 array->push(curr);
711
712 if (TraceClassLoaderData) {
713 tty->print("[ClassLoaderData] found new CLD: ");
714 curr->print_value_on(tty);
715 tty->cr();
716 }
717 }
718
719 curr = curr->_next;
720 }
721
722 return array;
723 }
724
725 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
726 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
727 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
728 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
729 return true;
730 }
731 }
732 return false;
733 }
734
735 #ifndef PRODUCT
736 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
737 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
738 if (loader_data == data) {
739 return true;
740 }
741 }
742
743 return false;
744 }
745 #endif // PRODUCT
746
747
748 // Move class loader data from main list to the unloaded list for unloading
749 // and deallocation later.
750 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, bool clean_alive) {
751 ClassLoaderData* data = _head;
752 ClassLoaderData* prev = NULL;
753 bool seen_dead_loader = false;
754
755 // Save previous _unloading pointer for CMS which may add to unloading list before
756 // purging and we don't want to rewalk the previously unloaded class loader data.
757 _saved_unloading = _unloading;
758
759 while (data != NULL) {
760 if (data->is_alive(is_alive_closure)) {
761 prev = data;
762 data = data->next();
763 continue;
764 }
765 seen_dead_loader = true;
766 ClassLoaderData* dead = data;
767 dead->unload();
768 data = data->next();
769 // Remove from loader list.
770 // This class loader data will no longer be found
771 // in the ClassLoaderDataGraph.
772 if (prev != NULL) {
773 prev->set_next(data);
774 } else {
775 assert(dead == _head, "sanity check");
776 _head = data;
777 }
778 dead->set_next(_unloading);
779 _unloading = dead;
780 }
781
782 if (clean_alive) {
783 // Clean previous versions and the deallocate list.
784 ClassLoaderDataGraph::clean_metaspaces();
785 }
786
787 if (seen_dead_loader) {
788 post_class_unload_events();
789 }
790
791 return seen_dead_loader;
792 }
793
794 void ClassLoaderDataGraph::clean_metaspaces() {
795 // mark metadata seen on the stack and code cache so we can delete unneeded entries.
796 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
797 MetadataOnStackMark md_on_stack(has_redefined_a_class);
798
799 if (has_redefined_a_class) {
800 // purge_previous_versions also cleans weak method links. Because
801 // one method's MDO can reference another method from another
802 // class loader, we need to first clean weak method links for all
803 // class loaders here. Below, we can then free redefined methods
804 // for all class loaders.
805 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
806 data->classes_do(InstanceKlass::purge_previous_versions);
807 }
808 }
809
810 // Need to purge the previous version before deallocating.
811 free_deallocate_lists();
812 }
813
814 void ClassLoaderDataGraph::purge() {
815 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
816 ClassLoaderData* list = _unloading;
817 _unloading = NULL;
818 ClassLoaderData* next = list;
819 while (next != NULL) {
820 ClassLoaderData* purge_me = next;
821 next = purge_me->next();
822 delete purge_me;
823 }
824 Metaspace::purge();
825 }
826
827 void ClassLoaderDataGraph::post_class_unload_events(void) {
828 #if INCLUDE_TRACE
829 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
830 if (Tracing::enabled()) {
831 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
832 assert(_unloading != NULL, "need class loader data unload list!");
833 _class_unload_time = Ticks::now();
834 classes_unloading_do(&class_unload_event);
835 }
836 Tracing::on_unloading_classes();
837 }
838 #endif
839 }
840
841 void ClassLoaderDataGraph::free_deallocate_lists() {
842 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
843 // We need to keep this data until InstanceKlass::purge_previous_version has been
844 // called on all alive classes. See the comment in ClassLoaderDataGraph::clean_metaspaces.
845 cld->free_deallocate_list();
846 }
847 }
848
849 // CDS support
850
851 // Global metaspaces for writing information to the shared archive. When
852 // application CDS is supported, we may need one per metaspace, so this
853 // sort of looks like it.
854 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
855 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
856 static bool _shared_metaspaces_initialized = false;
857
858 // Initialize shared metaspaces (change to call from somewhere not lazily)
859 void ClassLoaderData::initialize_shared_metaspaces() {
860 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
861 assert(this == ClassLoaderData::the_null_class_loader_data(),
862 "only supported for null loader data for now");
863 assert (!_shared_metaspaces_initialized, "only initialize once");
864 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
865 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
866 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
867 _shared_metaspaces_initialized = true;
868 }
869
870 Metaspace* ClassLoaderData::ro_metaspace() {
871 assert(_ro_metaspace != NULL, "should already be initialized");
872 return _ro_metaspace;
873 }
874
875 Metaspace* ClassLoaderData::rw_metaspace() {
876 assert(_rw_metaspace != NULL, "should already be initialized");
877 return _rw_metaspace;
878 }
879
880 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
881 : _next_klass(NULL) {
882 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
883 Klass* klass = NULL;
884
885 // Find the first klass in the CLDG.
886 while (cld != NULL) {
887 klass = cld->_klasses;
888 if (klass != NULL) {
889 _next_klass = klass;
890 return;
891 }
892 cld = cld->next();
893 }
894 }
895
896 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
897 Klass* next = klass->next_link();
898 if (next != NULL) {
899 return next;
900 }
901
902 // No more klasses in the current CLD. Time to find a new CLD.
903 ClassLoaderData* cld = klass->class_loader_data();
904 while (next == NULL) {
905 cld = cld->next();
906 if (cld == NULL) {
907 break;
908 }
909 next = cld->_klasses;
910 }
911
912 return next;
913 }
914
915 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
916 Klass* head = (Klass*)_next_klass;
917
918 while (head != NULL) {
919 Klass* next = next_klass_in_cldg(head);
920
921 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
922
923 if (old_head == head) {
924 return head; // Won the CAS.
925 }
926
927 head = old_head;
928 }
929
930 // Nothing more for the iterator to hand out.
931 assert(head == NULL, err_msg("head is " PTR_FORMAT ", expected not null:", p2i(head)));
932 return NULL;
933 }
934
935 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
936 _data = ClassLoaderDataGraph::_head;
937 }
938
939 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
940
941 #ifndef PRODUCT
942 // callable from debugger
943 extern "C" int print_loader_data_graph() {
944 ClassLoaderDataGraph::dump_on(tty);
945 return 0;
946 }
947
948 void ClassLoaderDataGraph::verify() {
949 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
950 data->verify();
951 }
952 }
953
954 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
955 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
956 data->dump(out);
957 }
958 MetaspaceAux::dump(out);
959 }
960 #endif // PRODUCT
961
962 void ClassLoaderData::print_value_on(outputStream* out) const {
963 if (class_loader() == NULL) {
964 out->print("NULL class_loader");
965 } else {
966 out->print("class loader " INTPTR_FORMAT, p2i(this));
967 class_loader()->print_value_on(out);
968 }
969 }
970
971 #if INCLUDE_TRACE
972
973 Ticks ClassLoaderDataGraph::_class_unload_time;
974
975 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
976
977 // post class unload event
978 EventClassUnload event(UNTIMED);
979 event.set_endtime(_class_unload_time);
980 event.set_unloadedClass(k);
981 oop defining_class_loader = k->class_loader();
982 event.set_definingClassLoader(defining_class_loader != NULL ?
983 defining_class_loader->klass() : (Klass*)NULL);
984 event.commit();
985 }
986
987 #endif /* INCLUDE_TRACE */