Mon, 03 Dec 2012 15:09:39 -0800
8005082: NPG: Add specialized Metachunk sizes for reflection and anonymous classloaders
Reviewed-by: johnc, 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.
22 *
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, bool is_anonymous) :
68 _class_loader(h_class_loader()),
69 _is_anonymous(is_anonymous), _keep_alive(is_anonymous), // initially
70 _metaspace(NULL), _unloading(false), _klasses(NULL),
71 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
72 _next(NULL), _dependencies(NULL),
73 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {
74 // empty
75 }
77 void ClassLoaderData::init_dependencies(TRAPS) {
78 // Create empty dependencies array to add to. CMS requires this to be
79 // an oop so that it can track additions via card marks. We think.
80 _dependencies = (oop)oopFactory::new_objectArray(2, CHECK);
81 }
83 bool ClassLoaderData::claim() {
84 if (_claimed == 1) {
85 return false;
86 }
88 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
89 }
91 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
92 if (must_claim && !claim()) {
93 return;
94 }
96 f->do_oop(&_class_loader);
97 f->do_oop(&_dependencies);
98 _handles->oops_do(f);
99 if (klass_closure != NULL) {
100 classes_do(klass_closure);
101 }
102 }
104 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
105 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
106 klass_closure->do_klass(k);
107 }
108 }
110 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
111 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
112 if (k->oop_is_instance()) {
113 f(InstanceKlass::cast(k));
114 }
115 }
116 }
118 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
119 ClassLoaderData * const from_cld = this;
120 ClassLoaderData * const to_cld = k->class_loader_data();
122 // Dependency to the null class loader data doesn't need to be recorded
123 // because the null class loader data never goes away.
124 if (to_cld->is_the_null_class_loader_data()) {
125 return;
126 }
128 oop to;
129 if (to_cld->is_anonymous()) {
130 // Anonymous class dependencies are through the mirror.
131 to = k->java_mirror();
132 } else {
133 to = to_cld->class_loader();
135 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
136 // we still have to add it. The class_loader won't keep from_cld alive.
137 if (!from_cld->is_anonymous()) {
138 // Check that this dependency isn't from the same or parent class_loader
139 oop from = from_cld->class_loader();
141 oop curr = from;
142 while (curr != NULL) {
143 if (curr == to) {
144 return; // this class loader is in the parent list, no need to add it.
145 }
146 curr = java_lang_ClassLoader::parent(curr);
147 }
148 }
149 }
151 // It's a dependency we won't find through GC, add it. This is relatively rare
152 // Must handle over GC point.
153 Handle dependency(THREAD, to);
154 from_cld->add_dependency(dependency, CHECK);
155 }
158 void ClassLoaderData::add_dependency(Handle dependency, TRAPS) {
159 // Check first if this dependency is already in the list.
160 // Save a pointer to the last to add to under the lock.
161 objArrayOop ok = (objArrayOop)_dependencies;
162 objArrayOop last = NULL;
163 while (ok != NULL) {
164 last = ok;
165 if (ok->obj_at(0) == dependency()) {
166 // Don't need to add it
167 return;
168 }
169 ok = (objArrayOop)ok->obj_at(1);
170 }
172 // Must handle over GC points
173 assert (last != NULL, "dependencies should be initialized");
174 objArrayHandle last_handle(THREAD, last);
176 // Create a new dependency node with fields for (class_loader or mirror, next)
177 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
178 deps->obj_at_put(0, dependency());
180 // Must handle over GC points
181 objArrayHandle new_dependency(THREAD, deps);
183 // Add the dependency under lock
184 locked_add_dependency(last_handle, new_dependency);
185 }
187 void ClassLoaderData::locked_add_dependency(objArrayHandle last_handle,
188 objArrayHandle new_dependency) {
190 // Have to lock and put the new dependency on the end of the dependency
191 // array so the card mark for CMS sees that this dependency is new.
192 // Can probably do this lock free with some effort.
193 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
195 oop loader_or_mirror = new_dependency->obj_at(0);
197 // Since the dependencies are only added, add to the end.
198 objArrayOop end = last_handle();
199 objArrayOop last = NULL;
200 while (end != NULL) {
201 last = end;
202 // check again if another thread added it to the end.
203 if (end->obj_at(0) == loader_or_mirror) {
204 // Don't need to add it
205 return;
206 }
207 end = (objArrayOop)end->obj_at(1);
208 }
209 assert (last != NULL, "dependencies should be initialized");
210 // fill in the first element with the oop in new_dependency.
211 if (last->obj_at(0) == NULL) {
212 last->obj_at_put(0, new_dependency->obj_at(0));
213 } else {
214 last->obj_at_put(1, new_dependency());
215 }
216 }
218 void ClassLoaderDataGraph::clear_claimed_marks() {
219 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
220 cld->clear_claimed();
221 }
222 }
224 void ClassLoaderData::add_class(Klass* k) {
225 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
226 Klass* old_value = _klasses;
227 k->set_next_link(old_value);
228 // link the new item into the list
229 _klasses = k;
231 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
232 ResourceMark rm;
233 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
234 PTR_FORMAT " loader: " PTR_FORMAT " %s",
235 k,
236 k->external_name(),
237 k->class_loader_data(),
238 k->class_loader(),
239 loader_name());
240 }
241 }
243 // This is called by InstanceKlass::deallocate_contents() to remove the
244 // scratch_class for redefine classes. We need a lock because there it may not
245 // be called at a safepoint if there's an error.
246 void ClassLoaderData::remove_class(Klass* scratch_class) {
247 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
248 Klass* prev = NULL;
249 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
250 if (k == scratch_class) {
251 if (prev == NULL) {
252 _klasses = k->next_link();
253 } else {
254 Klass* next = k->next_link();
255 prev->set_next_link(next);
256 }
257 return;
258 }
259 prev = k;
260 }
261 ShouldNotReachHere(); // should have found this class!!
262 }
264 void ClassLoaderData::unload() {
265 _unloading = true;
267 if (TraceClassLoaderData) {
268 ResourceMark rm;
269 tty->print("[ClassLoaderData: unload loader data "PTR_FORMAT, this);
270 tty->print(" for instance "PTR_FORMAT" of %s", class_loader(),
271 loader_name());
272 if (is_anonymous()) {
273 tty->print(" for anonymous class "PTR_FORMAT " ", _klasses);
274 }
275 tty->print_cr("]");
276 }
277 }
279 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
280 bool alive =
281 is_anonymous() ?
282 is_alive_closure->do_object_b(_klasses->java_mirror()) :
283 class_loader() == NULL || is_alive_closure->do_object_b(class_loader());
284 assert(!alive || claimed(), "must be claimed");
285 return alive;
286 }
289 ClassLoaderData::~ClassLoaderData() {
290 Metaspace *m = _metaspace;
291 if (m != NULL) {
292 _metaspace = NULL;
293 // release the metaspace
294 delete m;
295 // release the handles
296 if (_handles != NULL) {
297 JNIHandleBlock::release_block(_handles);
298 _handles = NULL;
299 }
300 }
302 // Clear all the JNI handles for methods
303 // These aren't deallocated and are going to look like a leak, but that's
304 // needed because we can't really get rid of jmethodIDs because we don't
305 // know when native code is going to stop using them. The spec says that
306 // they're "invalid" but existing programs likely rely on their being
307 // NULL after class unloading.
308 if (_jmethod_ids != NULL) {
309 Method::clear_jmethod_ids(this);
310 }
311 // Delete lock
312 delete _metaspace_lock;
314 // Delete free list
315 if (_deallocate_list != NULL) {
316 delete _deallocate_list;
317 }
318 }
320 Metaspace* ClassLoaderData::metaspace_non_null() {
321 // If the metaspace has not been allocated, create a new one. Might want
322 // to create smaller arena for Reflection class loaders also.
323 // The reason for the delayed allocation is because some class loaders are
324 // simply for delegating with no metadata of their own.
325 if (_metaspace == NULL) {
326 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
327 // Check again if metaspace has been allocated while we were getting this lock.
328 if (_metaspace != NULL) {
329 return _metaspace;
330 }
331 if (this == the_null_class_loader_data()) {
332 assert (class_loader() == NULL, "Must be");
333 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
334 } else if (is_anonymous()) {
335 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
336 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
337 }
338 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
339 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
340 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
341 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
342 }
343 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
344 } else {
345 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
346 }
347 }
348 return _metaspace;
349 }
351 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
352 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
354 jobject ClassLoaderData::add_handle(Handle h) {
355 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
356 if (handles() == NULL) {
357 set_handles(JNIHandleBlock::allocate_block());
358 }
359 return handles()->allocate_handle(h());
360 }
362 // Add this metadata pointer to be freed when it's safe. This is only during
363 // class unloading because Handles might point to this metadata field.
364 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
365 // Metadata in shared region isn't deleted.
366 if (!m->is_shared()) {
367 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
368 if (_deallocate_list == NULL) {
369 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
370 }
371 _deallocate_list->append_if_missing(m);
372 }
373 }
375 // Deallocate free metadata on the free list. How useful the PermGen was!
376 void ClassLoaderData::free_deallocate_list() {
377 // Don't need lock, at safepoint
378 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
379 if (_deallocate_list == NULL) {
380 return;
381 }
382 // Go backwards because this removes entries that are freed.
383 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
384 Metadata* m = _deallocate_list->at(i);
385 if (!m->on_stack()) {
386 _deallocate_list->remove_at(i);
387 // There are only three types of metadata that we deallocate directly.
388 // Cast them so they can be used by the template function.
389 if (m->is_method()) {
390 MetadataFactory::free_metadata(this, (Method*)m);
391 } else if (m->is_constantPool()) {
392 MetadataFactory::free_metadata(this, (ConstantPool*)m);
393 } else if (m->is_klass()) {
394 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
395 } else {
396 ShouldNotReachHere();
397 }
398 }
399 }
400 }
402 // These anonymous class loaders are to contain classes used for JSR292
403 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
404 // Add a new class loader data to the graph.
405 return ClassLoaderDataGraph::add(NULL, loader, CHECK_NULL);
406 }
408 const char* ClassLoaderData::loader_name() {
409 // Handles null class loader
410 return SystemDictionary::loader_name(class_loader());
411 }
413 #ifndef PRODUCT
414 // Define to dump klasses
415 #undef CLD_DUMP_KLASSES
417 void ClassLoaderData::dump(outputStream * const out) {
418 ResourceMark rm;
419 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {",
420 this, class_loader(),
421 class_loader() != NULL ? class_loader()->klass() : NULL, loader_name());
422 if (claimed()) out->print(" claimed ");
423 if (is_unloading()) out->print(" unloading ");
424 out->print(" handles " INTPTR_FORMAT, handles());
425 out->cr();
426 if (metaspace_or_null() != NULL) {
427 out->print_cr("metaspace: " PTR_FORMAT, metaspace_or_null());
428 metaspace_or_null()->dump(out);
429 } else {
430 out->print_cr("metaspace: NULL");
431 }
433 #ifdef CLD_DUMP_KLASSES
434 if (Verbose) {
435 ResourceMark rm;
436 Klass* k = _klasses;
437 while (k != NULL) {
438 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
439 k->has_modified_oops(), k->has_accumulated_modified_oops());
440 k = k->next_link();
441 }
442 }
443 #endif // CLD_DUMP_KLASSES
444 #undef CLD_DUMP_KLASSES
445 if (_jmethod_ids != NULL) {
446 Method::print_jmethod_ids(this, out);
447 }
448 out->print_cr("}");
449 }
450 #endif // PRODUCT
452 void ClassLoaderData::verify() {
453 oop cl = class_loader();
455 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
456 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
458 // Verify the integrity of the allocated space.
459 if (metaspace_or_null() != NULL) {
460 metaspace_or_null()->verify();
461 }
463 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
464 guarantee(k->class_loader_data() == this, "Must be the same");
465 k->verify();
466 }
467 }
470 // GC root of class loader data created.
471 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
472 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
473 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
476 // Add a new class loader data node to the list. Assign the newly created
477 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
478 ClassLoaderData* ClassLoaderDataGraph::add(ClassLoaderData** cld_addr, Handle loader, TRAPS) {
479 // Not assigned a class loader data yet.
480 // Create one.
481 ClassLoaderData* *list_head = &_head;
482 ClassLoaderData* next = _head;
484 bool is_anonymous = (cld_addr == NULL);
485 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous);
487 if (cld_addr != NULL) {
488 // First, Atomically set it
489 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
490 if (old != NULL) {
491 delete cld;
492 // Returns the data.
493 return old;
494 }
495 }
497 // We won the race, and therefore the task of adding the data to the list of
498 // class loader data
499 do {
500 cld->set_next(next);
501 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
502 if (exchanged == next) {
503 if (TraceClassLoaderData) {
504 ResourceMark rm;
505 tty->print("[ClassLoaderData: ");
506 tty->print("create class loader data "PTR_FORMAT, cld);
507 tty->print(" for instance "PTR_FORMAT" of %s", cld->class_loader(),
508 cld->loader_name());
509 tty->print_cr("]");
510 }
511 // Create dependencies after the CLD is added to the list. Otherwise,
512 // the GC GC will not find the CLD and the _class_loader field will
513 // not be updated.
514 cld->init_dependencies(CHECK_NULL);
515 return cld;
516 }
517 next = exchanged;
518 } while (true);
520 }
522 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
523 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
524 cld->oops_do(f, klass_closure, must_claim);
525 }
526 }
528 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
529 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
530 if (cld->keep_alive()) {
531 cld->oops_do(f, klass_closure, must_claim);
532 }
533 }
534 }
536 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
537 if (ClassUnloading) {
538 ClassLoaderData::the_null_class_loader_data()->oops_do(f, klass_closure, must_claim);
539 // keep any special CLDs alive.
540 ClassLoaderDataGraph::keep_alive_oops_do(f, klass_closure, must_claim);
541 } else {
542 ClassLoaderDataGraph::oops_do(f, klass_closure, must_claim);
543 }
544 }
546 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
547 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
548 cld->classes_do(klass_closure);
549 }
550 }
552 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
553 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
555 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
557 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
558 ClassLoaderData* curr = _head;
559 while (curr != _saved_head) {
560 if (!curr->claimed()) {
561 array->push(curr);
563 if (TraceClassLoaderData) {
564 tty->print("[ClassLoaderData] found new CLD: ");
565 curr->print_value_on(tty);
566 tty->cr();
567 }
568 }
570 curr = curr->_next;
571 }
573 return array;
574 }
576 #ifndef PRODUCT
577 // for debugging and hsfind(x)
578 bool ClassLoaderDataGraph::contains(address x) {
579 // I think we need the _metaspace_lock taken here because the class loader
580 // data graph could be changing while we are walking it (new entries added,
581 // new entries being unloaded, etc).
582 if (DumpSharedSpaces) {
583 // There are only two metaspaces to worry about.
584 ClassLoaderData* ncld = ClassLoaderData::the_null_class_loader_data();
585 return (ncld->ro_metaspace()->contains(x) || ncld->rw_metaspace()->contains(x));
586 }
588 if (UseSharedSpaces && MetaspaceShared::is_in_shared_space(x)) {
589 return true;
590 }
592 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
593 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
594 return true;
595 }
596 }
598 // Could also be on an unloading list which is okay, ie. still allocated
599 // for a little while.
600 for (ClassLoaderData* ucld = _unloading; ucld != NULL; ucld = ucld->next()) {
601 if (ucld->metaspace_or_null() != NULL && ucld->metaspace_or_null()->contains(x)) {
602 return true;
603 }
604 }
605 return false;
606 }
608 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
609 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
610 if (loader_data == data) {
611 return true;
612 }
613 }
615 return false;
616 }
617 #endif // PRODUCT
620 // Move class loader data from main list to the unloaded list for unloading
621 // and deallocation later.
622 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure) {
623 ClassLoaderData* data = _head;
624 ClassLoaderData* prev = NULL;
625 bool seen_dead_loader = false;
626 // mark metadata seen on the stack and code cache so we can delete
627 // unneeded entries.
628 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
629 MetadataOnStackMark md_on_stack;
630 while (data != NULL) {
631 if (data->keep_alive() || data->is_alive(is_alive_closure)) {
632 if (has_redefined_a_class) {
633 data->classes_do(InstanceKlass::purge_previous_versions);
634 }
635 data->free_deallocate_list();
636 prev = data;
637 data = data->next();
638 continue;
639 }
640 seen_dead_loader = true;
641 ClassLoaderData* dead = data;
642 dead->unload();
643 data = data->next();
644 // Remove from loader list.
645 if (prev != NULL) {
646 prev->set_next(data);
647 } else {
648 assert(dead == _head, "sanity check");
649 _head = data;
650 }
651 dead->set_next(_unloading);
652 _unloading = dead;
653 }
654 return seen_dead_loader;
655 }
657 void ClassLoaderDataGraph::purge() {
658 ClassLoaderData* list = _unloading;
659 _unloading = NULL;
660 ClassLoaderData* next = list;
661 while (next != NULL) {
662 ClassLoaderData* purge_me = next;
663 next = purge_me->next();
664 delete purge_me;
665 }
666 }
668 // CDS support
670 // Global metaspaces for writing information to the shared archive. When
671 // application CDS is supported, we may need one per metaspace, so this
672 // sort of looks like it.
673 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
674 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
675 static bool _shared_metaspaces_initialized = false;
677 // Initialize shared metaspaces (change to call from somewhere not lazily)
678 void ClassLoaderData::initialize_shared_metaspaces() {
679 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
680 assert(this == ClassLoaderData::the_null_class_loader_data(),
681 "only supported for null loader data for now");
682 assert (!_shared_metaspaces_initialized, "only initialize once");
683 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
684 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
685 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
686 _shared_metaspaces_initialized = true;
687 }
689 Metaspace* ClassLoaderData::ro_metaspace() {
690 assert(_ro_metaspace != NULL, "should already be initialized");
691 return _ro_metaspace;
692 }
694 Metaspace* ClassLoaderData::rw_metaspace() {
695 assert(_rw_metaspace != NULL, "should already be initialized");
696 return _rw_metaspace;
697 }
700 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
701 _data = ClassLoaderDataGraph::_head;
702 }
704 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
706 #ifndef PRODUCT
707 // callable from debugger
708 extern "C" int print_loader_data_graph() {
709 ClassLoaderDataGraph::dump_on(tty);
710 return 0;
711 }
713 void ClassLoaderDataGraph::verify() {
714 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
715 data->verify();
716 }
717 }
719 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
720 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
721 data->dump(out);
722 }
723 MetaspaceAux::dump(out);
724 }
726 void ClassLoaderData::print_value_on(outputStream* out) const {
727 if (class_loader() == NULL) {
728 out->print_cr("NULL class_loader");
729 } else {
730 out->print("class loader "PTR_FORMAT, this);
731 class_loader()->print_value_on(out);
732 }
733 }
734 #endif // PRODUCT