Wed, 12 Dec 2012 22:41:13 +0100
8005002: Crash because of a raw oop in ClassLoaderData::add_dependency
Summary: Move the handelization of 'last' to a point before the GC might enter.
Reviewed-by: dholmes, sspitsyn, coleenp
1 /*
2 * Copyright (c) 2012, 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.
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23 */
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().
49 #include "precompiled.hpp"
50 #include "classfile/classLoaderData.hpp"
51 #include "classfile/classLoaderData.inline.hpp"
52 #include "classfile/javaClasses.hpp"
53 #include "classfile/systemDictionary.hpp"
54 #include "code/codeCache.hpp"
55 #include "memory/metadataFactory.hpp"
56 #include "memory/metaspaceShared.hpp"
57 #include "prims/jvmtiRedefineClasses.hpp"
58 #include "runtime/jniHandles.hpp"
59 #include "runtime/mutex.hpp"
60 #include "runtime/safepoint.hpp"
61 #include "runtime/synchronizer.hpp"
62 #include "utilities/growableArray.hpp"
63 #include "utilities/ostream.hpp"
65 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
67 ClassLoaderData::ClassLoaderData(Handle h_class_loader) : _class_loader(h_class_loader()),
68 _metaspace(NULL), _unloading(false), _keep_alive(false), _klasses(NULL),
69 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
70 _next(NULL), _dependencies(NULL),
71 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {
72 // empty
73 }
75 void ClassLoaderData::init_dependencies(TRAPS) {
76 // Create empty dependencies array to add to. CMS requires this to be
77 // an oop so that it can track additions via card marks. We think.
78 _dependencies = (oop)oopFactory::new_objectArray(2, CHECK);
79 }
81 bool ClassLoaderData::claim() {
82 if (_claimed == 1) {
83 return false;
84 }
86 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
87 }
89 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
90 if (must_claim && !claim()) {
91 return;
92 }
94 f->do_oop(&_class_loader);
95 f->do_oop(&_dependencies);
96 _handles->oops_do(f);
97 if (klass_closure != NULL) {
98 classes_do(klass_closure);
99 }
100 }
102 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
103 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
104 klass_closure->do_klass(k);
105 }
106 }
108 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
109 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
110 if (k->oop_is_instance()) {
111 f(InstanceKlass::cast(k));
112 }
113 }
114 }
116 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
117 ClassLoaderData * const from_cld = this;
118 ClassLoaderData * const to_cld = k->class_loader_data();
120 // Dependency to the null class loader data doesn't need to be recorded
121 // because the null class loader data never goes away.
122 if (to_cld->is_the_null_class_loader_data()) {
123 return;
124 }
126 oop to;
127 if (to_cld->is_anonymous()) {
128 // Anonymous class dependencies are through the mirror.
129 to = k->java_mirror();
130 } else {
131 to = to_cld->class_loader();
133 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
134 // we still have to add it. The class_loader won't keep from_cld alive.
135 if (!from_cld->is_anonymous()) {
136 // Check that this dependency isn't from the same or parent class_loader
137 oop from = from_cld->class_loader();
139 oop curr = from;
140 while (curr != NULL) {
141 if (curr == to) {
142 return; // this class loader is in the parent list, no need to add it.
143 }
144 curr = java_lang_ClassLoader::parent(curr);
145 }
146 }
147 }
149 // It's a dependency we won't find through GC, add it. This is relatively rare
150 // Must handle over GC point.
151 Handle dependency(THREAD, to);
152 from_cld->add_dependency(dependency, CHECK);
153 }
156 void ClassLoaderData::add_dependency(Handle dependency, TRAPS) {
157 // Check first if this dependency is already in the list.
158 // Save a pointer to the last to add to under the lock.
159 objArrayOop ok = (objArrayOop)_dependencies;
160 objArrayOop last = NULL;
161 while (ok != NULL) {
162 last = ok;
163 if (ok->obj_at(0) == dependency()) {
164 // Don't need to add it
165 return;
166 }
167 ok = (objArrayOop)ok->obj_at(1);
168 }
170 // Must handle over GC points
171 assert (last != NULL, "dependencies should be initialized");
172 objArrayHandle last_handle(THREAD, last);
174 // Create a new dependency node with fields for (class_loader or mirror, next)
175 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
176 deps->obj_at_put(0, dependency());
178 // Must handle over GC points
179 objArrayHandle new_dependency(THREAD, deps);
181 // Add the dependency under lock
182 locked_add_dependency(last_handle, new_dependency);
183 }
185 void ClassLoaderData::locked_add_dependency(objArrayHandle last_handle,
186 objArrayHandle new_dependency) {
188 // Have to lock and put the new dependency on the end of the dependency
189 // array so the card mark for CMS sees that this dependency is new.
190 // Can probably do this lock free with some effort.
191 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
193 oop loader_or_mirror = new_dependency->obj_at(0);
195 // Since the dependencies are only added, add to the end.
196 objArrayOop end = last_handle();
197 objArrayOop last = NULL;
198 while (end != NULL) {
199 last = end;
200 // check again if another thread added it to the end.
201 if (end->obj_at(0) == loader_or_mirror) {
202 // Don't need to add it
203 return;
204 }
205 end = (objArrayOop)end->obj_at(1);
206 }
207 assert (last != NULL, "dependencies should be initialized");
208 // fill in the first element with the oop in new_dependency.
209 if (last->obj_at(0) == NULL) {
210 last->obj_at_put(0, new_dependency->obj_at(0));
211 } else {
212 last->obj_at_put(1, new_dependency());
213 }
214 }
216 void ClassLoaderDataGraph::clear_claimed_marks() {
217 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
218 cld->clear_claimed();
219 }
220 }
222 void ClassLoaderData::add_class(Klass* k) {
223 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
224 Klass* old_value = _klasses;
225 k->set_next_link(old_value);
226 // link the new item into the list
227 _klasses = k;
229 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
230 ResourceMark rm;
231 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
232 PTR_FORMAT " loader: " PTR_FORMAT " %s",
233 k,
234 k->external_name(),
235 k->class_loader_data(),
236 k->class_loader(),
237 loader_name());
238 }
239 }
241 // This is called by InstanceKlass::deallocate_contents() to remove the
242 // scratch_class for redefine classes. We need a lock because there it may not
243 // be called at a safepoint if there's an error.
244 void ClassLoaderData::remove_class(Klass* scratch_class) {
245 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
246 Klass* prev = NULL;
247 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
248 if (k == scratch_class) {
249 if (prev == NULL) {
250 _klasses = k->next_link();
251 } else {
252 Klass* next = k->next_link();
253 prev->set_next_link(next);
254 }
255 return;
256 }
257 prev = k;
258 }
259 ShouldNotReachHere(); // should have found this class!!
260 }
263 bool ClassLoaderData::is_anonymous() const {
264 Klass* k = _klasses;
265 return (_keep_alive || (k != NULL && k->oop_is_instance() &&
266 InstanceKlass::cast(k)->is_anonymous()));
267 }
269 void ClassLoaderData::unload() {
270 _unloading = true;
272 if (TraceClassLoaderData) {
273 ResourceMark rm;
274 tty->print("[ClassLoaderData: unload loader data "PTR_FORMAT, this);
275 tty->print(" for instance "PTR_FORMAT" of %s", class_loader(),
276 loader_name());
277 if (is_anonymous()) {
278 tty->print(" for anonymous class "PTR_FORMAT " ", _klasses);
279 }
280 tty->print_cr("]");
281 }
282 }
284 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
285 bool alive =
286 is_anonymous() ?
287 is_alive_closure->do_object_b(_klasses->java_mirror()) :
288 class_loader() == NULL || is_alive_closure->do_object_b(class_loader());
289 assert(!alive || claimed(), "must be claimed");
290 return alive;
291 }
294 ClassLoaderData::~ClassLoaderData() {
295 Metaspace *m = _metaspace;
296 if (m != NULL) {
297 _metaspace = NULL;
298 // release the metaspace
299 delete m;
300 // release the handles
301 if (_handles != NULL) {
302 JNIHandleBlock::release_block(_handles);
303 _handles = NULL;
304 }
305 }
307 // Clear all the JNI handles for methods
308 // These aren't deallocated and are going to look like a leak, but that's
309 // needed because we can't really get rid of jmethodIDs because we don't
310 // know when native code is going to stop using them. The spec says that
311 // they're "invalid" but existing programs likely rely on their being
312 // NULL after class unloading.
313 if (_jmethod_ids != NULL) {
314 Method::clear_jmethod_ids(this);
315 }
316 // Delete lock
317 delete _metaspace_lock;
319 // Delete free list
320 if (_deallocate_list != NULL) {
321 delete _deallocate_list;
322 }
323 }
325 Metaspace* ClassLoaderData::metaspace_non_null() {
326 // If the metaspace has not been allocated, create a new one. Might want
327 // to create smaller arena for Reflection class loaders also.
328 // The reason for the delayed allocation is because some class loaders are
329 // simply for delegating with no metadata of their own.
330 if (_metaspace == NULL) {
331 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
332 // Check again if metaspace has been allocated while we were getting this lock.
333 if (_metaspace != NULL) {
334 return _metaspace;
335 }
336 if (this == the_null_class_loader_data()) {
337 assert (class_loader() == NULL, "Must be");
338 size_t word_size = Metaspace::first_chunk_word_size();
339 set_metaspace(new Metaspace(_metaspace_lock, word_size));
340 } else {
341 set_metaspace(new Metaspace(_metaspace_lock)); // default size for now.
342 }
343 }
344 return _metaspace;
345 }
347 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
348 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
350 jobject ClassLoaderData::add_handle(Handle h) {
351 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
352 if (handles() == NULL) {
353 set_handles(JNIHandleBlock::allocate_block());
354 }
355 return handles()->allocate_handle(h());
356 }
358 // Add this metadata pointer to be freed when it's safe. This is only during
359 // class unloading because Handles might point to this metadata field.
360 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
361 // Metadata in shared region isn't deleted.
362 if (!m->is_shared()) {
363 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
364 if (_deallocate_list == NULL) {
365 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
366 }
367 _deallocate_list->append_if_missing(m);
368 }
369 }
371 // Deallocate free metadata on the free list. How useful the PermGen was!
372 void ClassLoaderData::free_deallocate_list() {
373 // Don't need lock, at safepoint
374 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
375 if (_deallocate_list == NULL) {
376 return;
377 }
378 // Go backwards because this removes entries that are freed.
379 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
380 Metadata* m = _deallocate_list->at(i);
381 if (!m->on_stack()) {
382 _deallocate_list->remove_at(i);
383 // There are only three types of metadata that we deallocate directly.
384 // Cast them so they can be used by the template function.
385 if (m->is_method()) {
386 MetadataFactory::free_metadata(this, (Method*)m);
387 } else if (m->is_constantPool()) {
388 MetadataFactory::free_metadata(this, (ConstantPool*)m);
389 } else if (m->is_klass()) {
390 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
391 } else {
392 ShouldNotReachHere();
393 }
394 }
395 }
396 }
398 // These anonymous class loaders are to contain classes used for JSR292
399 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
400 // Add a new class loader data to the graph.
401 ClassLoaderData* cld = ClassLoaderDataGraph::add(NULL, loader, CHECK_NULL);
402 return cld;
403 }
405 const char* ClassLoaderData::loader_name() {
406 // Handles null class loader
407 return SystemDictionary::loader_name(class_loader());
408 }
410 #ifndef PRODUCT
411 // Define to dump klasses
412 #undef CLD_DUMP_KLASSES
414 void ClassLoaderData::dump(outputStream * const out) {
415 ResourceMark rm;
416 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {",
417 this, class_loader(),
418 class_loader() != NULL ? class_loader()->klass() : NULL, loader_name());
419 if (claimed()) out->print(" claimed ");
420 if (is_unloading()) out->print(" unloading ");
421 out->print(" handles " INTPTR_FORMAT, handles());
422 out->cr();
423 if (metaspace_or_null() != NULL) {
424 out->print_cr("metaspace: " PTR_FORMAT, metaspace_or_null());
425 metaspace_or_null()->dump(out);
426 } else {
427 out->print_cr("metaspace: NULL");
428 }
430 #ifdef CLD_DUMP_KLASSES
431 if (Verbose) {
432 ResourceMark rm;
433 Klass* k = _klasses;
434 while (k != NULL) {
435 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
436 k->has_modified_oops(), k->has_accumulated_modified_oops());
437 k = k->next_link();
438 }
439 }
440 #endif // CLD_DUMP_KLASSES
441 #undef CLD_DUMP_KLASSES
442 if (_jmethod_ids != NULL) {
443 Method::print_jmethod_ids(this, out);
444 }
445 out->print_cr("}");
446 }
447 #endif // PRODUCT
449 void ClassLoaderData::verify() {
450 oop cl = class_loader();
452 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
453 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
455 // Verify the integrity of the allocated space.
456 if (metaspace_or_null() != NULL) {
457 metaspace_or_null()->verify();
458 }
460 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
461 guarantee(k->class_loader_data() == this, "Must be the same");
462 k->verify();
463 }
464 }
467 // GC root of class loader data created.
468 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
469 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
470 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
473 // Add a new class loader data node to the list. Assign the newly created
474 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
475 ClassLoaderData* ClassLoaderDataGraph::add(ClassLoaderData** cld_addr, Handle loader, TRAPS) {
476 // Not assigned a class loader data yet.
477 // Create one.
478 ClassLoaderData* *list_head = &_head;
479 ClassLoaderData* next = _head;
480 ClassLoaderData* cld = new ClassLoaderData(loader);
482 if (cld_addr != NULL) {
483 // First, Atomically set it
484 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
485 if (old != NULL) {
486 delete cld;
487 // Returns the data.
488 return old;
489 }
490 } else {
491 // Disallow unloading for this CLD during initialization if there is no
492 // class_loader oop to link this to.
493 cld->set_keep_alive(true);
494 }
496 // We won the race, and therefore the task of adding the data to the list of
497 // class loader data
498 do {
499 cld->set_next(next);
500 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
501 if (exchanged == next) {
502 if (TraceClassLoaderData) {
503 ResourceMark rm;
504 tty->print("[ClassLoaderData: ");
505 tty->print("create class loader data "PTR_FORMAT, cld);
506 tty->print(" for instance "PTR_FORMAT" of %s", cld->class_loader(),
507 cld->loader_name());
508 tty->print_cr("]");
509 }
510 // Create dependencies after the CLD is added to the list. Otherwise,
511 // the GC GC will not find the CLD and the _class_loader field will
512 // not be updated.
513 cld->init_dependencies(CHECK_NULL);
514 return cld;
515 }
516 next = exchanged;
517 } while (true);
519 }
521 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
522 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
523 cld->oops_do(f, klass_closure, must_claim);
524 }
525 }
527 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
528 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
529 if (cld->keep_alive()) {
530 cld->oops_do(f, klass_closure, must_claim);
531 }
532 }
533 }
535 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
536 if (ClassUnloading) {
537 ClassLoaderData::the_null_class_loader_data()->oops_do(f, klass_closure, must_claim);
538 // keep any special CLDs alive.
539 ClassLoaderDataGraph::keep_alive_oops_do(f, klass_closure, must_claim);
540 } else {
541 ClassLoaderDataGraph::oops_do(f, klass_closure, must_claim);
542 }
543 }
545 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
546 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
547 cld->classes_do(klass_closure);
548 }
549 }
551 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
552 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
554 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
556 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
557 ClassLoaderData* curr = _head;
558 while (curr != _saved_head) {
559 if (!curr->claimed()) {
560 array->push(curr);
562 if (TraceClassLoaderData) {
563 tty->print("[ClassLoaderData] found new CLD: ");
564 curr->print_value_on(tty);
565 tty->cr();
566 }
567 }
569 curr = curr->_next;
570 }
572 return array;
573 }
575 #ifndef PRODUCT
576 // for debugging and hsfind(x)
577 bool ClassLoaderDataGraph::contains(address x) {
578 // I think we need the _metaspace_lock taken here because the class loader
579 // data graph could be changing while we are walking it (new entries added,
580 // new entries being unloaded, etc).
581 if (DumpSharedSpaces) {
582 // There are only two metaspaces to worry about.
583 ClassLoaderData* ncld = ClassLoaderData::the_null_class_loader_data();
584 return (ncld->ro_metaspace()->contains(x) || ncld->rw_metaspace()->contains(x));
585 }
587 if (UseSharedSpaces && MetaspaceShared::is_in_shared_space(x)) {
588 return true;
589 }
591 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
592 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
593 return true;
594 }
595 }
597 // Could also be on an unloading list which is okay, ie. still allocated
598 // for a little while.
599 for (ClassLoaderData* ucld = _unloading; ucld != NULL; ucld = ucld->next()) {
600 if (ucld->metaspace_or_null() != NULL && ucld->metaspace_or_null()->contains(x)) {
601 return true;
602 }
603 }
604 return false;
605 }
607 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
608 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
609 if (loader_data == data) {
610 return true;
611 }
612 }
614 return false;
615 }
616 #endif // PRODUCT
619 // Move class loader data from main list to the unloaded list for unloading
620 // and deallocation later.
621 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure) {
622 ClassLoaderData* data = _head;
623 ClassLoaderData* prev = NULL;
624 bool seen_dead_loader = false;
625 // mark metadata seen on the stack and code cache so we can delete
626 // unneeded entries.
627 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
628 MetadataOnStackMark md_on_stack;
629 while (data != NULL) {
630 if (data->keep_alive() || data->is_alive(is_alive_closure)) {
631 if (has_redefined_a_class) {
632 data->classes_do(InstanceKlass::purge_previous_versions);
633 }
634 data->free_deallocate_list();
635 prev = data;
636 data = data->next();
637 continue;
638 }
639 seen_dead_loader = true;
640 ClassLoaderData* dead = data;
641 dead->unload();
642 data = data->next();
643 // Remove from loader list.
644 if (prev != NULL) {
645 prev->set_next(data);
646 } else {
647 assert(dead == _head, "sanity check");
648 _head = data;
649 }
650 dead->set_next(_unloading);
651 _unloading = dead;
652 }
653 return seen_dead_loader;
654 }
656 void ClassLoaderDataGraph::purge() {
657 ClassLoaderData* list = _unloading;
658 _unloading = NULL;
659 ClassLoaderData* next = list;
660 while (next != NULL) {
661 ClassLoaderData* purge_me = next;
662 next = purge_me->next();
663 delete purge_me;
664 }
665 }
667 // CDS support
669 // Global metaspaces for writing information to the shared archive. When
670 // application CDS is supported, we may need one per metaspace, so this
671 // sort of looks like it.
672 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
673 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
674 static bool _shared_metaspaces_initialized = false;
676 // Initialize shared metaspaces (change to call from somewhere not lazily)
677 void ClassLoaderData::initialize_shared_metaspaces() {
678 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
679 assert(this == ClassLoaderData::the_null_class_loader_data(),
680 "only supported for null loader data for now");
681 assert (!_shared_metaspaces_initialized, "only initialize once");
682 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
683 _ro_metaspace = new Metaspace(_metaspace_lock, SharedReadOnlySize/wordSize);
684 _rw_metaspace = new Metaspace(_metaspace_lock, SharedReadWriteSize/wordSize);
685 _shared_metaspaces_initialized = true;
686 }
688 Metaspace* ClassLoaderData::ro_metaspace() {
689 assert(_ro_metaspace != NULL, "should already be initialized");
690 return _ro_metaspace;
691 }
693 Metaspace* ClassLoaderData::rw_metaspace() {
694 assert(_rw_metaspace != NULL, "should already be initialized");
695 return _rw_metaspace;
696 }
699 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
700 _data = ClassLoaderDataGraph::_head;
701 }
703 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
705 #ifndef PRODUCT
706 // callable from debugger
707 extern "C" int print_loader_data_graph() {
708 ClassLoaderDataGraph::dump_on(tty);
709 return 0;
710 }
712 void ClassLoaderDataGraph::verify() {
713 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
714 data->verify();
715 }
716 }
718 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
719 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
720 data->dump(out);
721 }
722 MetaspaceAux::dump(out);
723 }
725 void ClassLoaderData::print_value_on(outputStream* out) const {
726 if (class_loader() == NULL) {
727 out->print_cr("NULL class_loader");
728 } else {
729 out->print("class loader "PTR_FORMAT, this);
730 class_loader()->print_value_on(out);
731 }
732 }
733 #endif // PRODUCT