Thu, 25 Aug 2016 09:23:45 -0400
8148854: Class names "SomeClass" and "LSomeClass;" treated by JVM as an equivalent
Summary: Added default format checking of class names loaded by the app class loader
Reviewed-by: andrew
1 /*
2 * Copyright (c) 2012, 2018, 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/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"
68 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
70 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
71 _class_loader(h_class_loader()),
72 _is_anonymous(is_anonymous),
73 // An anonymous class loader data doesn't have anything to keep
74 // it from being unloaded during parsing of the anonymous class.
75 // The null-class-loader should always be kept alive.
76 _keep_alive(is_anonymous || h_class_loader.is_null()),
77 _metaspace(NULL), _unloading(false), _klasses(NULL),
78 _claimed(0), _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
79 _next(NULL), _dependencies(dependencies),
80 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {
82 JFR_ONLY(INIT_ID(this);)
83 }
85 void ClassLoaderData::init_dependencies(TRAPS) {
86 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
87 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
88 _dependencies.init(CHECK);
89 }
91 void ClassLoaderData::Dependencies::init(TRAPS) {
92 // Create empty dependencies array to add to. CMS requires this to be
93 // an oop so that it can track additions via card marks. We think.
94 _list_head = oopFactory::new_objectArray(2, CHECK);
95 }
97 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
98 Chunk* c = _head;
99 while (c != NULL) {
100 Chunk* next = c->_next;
101 delete c;
102 c = next;
103 }
104 }
106 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
107 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
108 Chunk* next = new Chunk(_head);
109 OrderAccess::release_store_ptr(&_head, next);
110 }
111 oop* handle = &_head->_data[_head->_size];
112 *handle = o;
113 OrderAccess::release_store(&_head->_size, _head->_size + 1);
114 return handle;
115 }
117 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
118 for (juint i = 0; i < size; i++) {
119 if (c->_data[i] != NULL) {
120 f->do_oop(&c->_data[i]);
121 }
122 }
123 }
125 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
126 Chunk* head = (Chunk*) OrderAccess::load_ptr_acquire(&_head);
127 if (head != NULL) {
128 // Must be careful when reading size of head
129 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
130 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
131 oops_do_chunk(f, c, c->_size);
132 }
133 }
134 }
136 bool ClassLoaderData::claim() {
137 if (_claimed == 1) {
138 return false;
139 }
141 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
142 }
144 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
145 if (must_claim && !claim()) {
146 return;
147 }
149 f->do_oop(&_class_loader);
150 _dependencies.oops_do(f);
151 _handles.oops_do(f);
152 if (klass_closure != NULL) {
153 classes_do(klass_closure);
154 }
155 }
157 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
158 f->do_oop((oop*)&_list_head);
159 }
161 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
162 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
163 klass_closure->do_klass(k);
164 assert(k != k->next_link(), "no loops!");
165 }
166 }
168 void ClassLoaderData::classes_do(void f(Klass * const)) {
169 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
170 f(k);
171 }
172 }
174 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
175 // Lock to avoid classes being modified/added/removed during iteration
176 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
177 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
178 // Do not filter ArrayKlass oops here...
179 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) {
180 klass_closure->do_klass(k);
181 }
182 }
183 }
185 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
186 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
187 if (k->oop_is_instance()) {
188 f(InstanceKlass::cast(k));
189 }
190 assert(k != k->next_link(), "no loops!");
191 }
192 }
194 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
195 ClassLoaderData * const from_cld = this;
196 ClassLoaderData * const to_cld = k->class_loader_data();
198 // Dependency to the null class loader data doesn't need to be recorded
199 // because the null class loader data never goes away.
200 if (to_cld->is_the_null_class_loader_data()) {
201 return;
202 }
204 oop to;
205 if (to_cld->is_anonymous()) {
206 // Anonymous class dependencies are through the mirror.
207 to = k->java_mirror();
208 } else {
209 to = to_cld->class_loader();
211 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
212 // we still have to add it. The class_loader won't keep from_cld alive.
213 if (!from_cld->is_anonymous()) {
214 // Check that this dependency isn't from the same or parent class_loader
215 oop from = from_cld->class_loader();
217 oop curr = from;
218 while (curr != NULL) {
219 if (curr == to) {
220 return; // this class loader is in the parent list, no need to add it.
221 }
222 curr = java_lang_ClassLoader::parent(curr);
223 }
224 }
225 }
227 // It's a dependency we won't find through GC, add it. This is relatively rare
228 // Must handle over GC point.
229 Handle dependency(THREAD, to);
230 from_cld->_dependencies.add(dependency, CHECK);
231 }
234 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
235 // Check first if this dependency is already in the list.
236 // Save a pointer to the last to add to under the lock.
237 objArrayOop ok = _list_head;
238 objArrayOop last = NULL;
239 while (ok != NULL) {
240 last = ok;
241 if (ok->obj_at(0) == dependency()) {
242 // Don't need to add it
243 return;
244 }
245 ok = (objArrayOop)ok->obj_at(1);
246 }
248 // Must handle over GC points
249 assert (last != NULL, "dependencies should be initialized");
250 objArrayHandle last_handle(THREAD, last);
252 // Create a new dependency node with fields for (class_loader or mirror, next)
253 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
254 deps->obj_at_put(0, dependency());
256 // Must handle over GC points
257 objArrayHandle new_dependency(THREAD, deps);
259 // Add the dependency under lock
260 locked_add(last_handle, new_dependency, THREAD);
261 }
263 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
264 objArrayHandle new_dependency,
265 Thread* THREAD) {
267 // Have to lock and put the new dependency on the end of the dependency
268 // array so the card mark for CMS sees that this dependency is new.
269 // Can probably do this lock free with some effort.
270 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
272 oop loader_or_mirror = new_dependency->obj_at(0);
274 // Since the dependencies are only added, add to the end.
275 objArrayOop end = last_handle();
276 objArrayOop last = NULL;
277 while (end != NULL) {
278 last = end;
279 // check again if another thread added it to the end.
280 if (end->obj_at(0) == loader_or_mirror) {
281 // Don't need to add it
282 return;
283 }
284 end = (objArrayOop)end->obj_at(1);
285 }
286 assert (last != NULL, "dependencies should be initialized");
287 // fill in the first element with the oop in new_dependency.
288 if (last->obj_at(0) == NULL) {
289 last->obj_at_put(0, new_dependency->obj_at(0));
290 } else {
291 last->obj_at_put(1, new_dependency());
292 }
293 }
295 void ClassLoaderDataGraph::clear_claimed_marks() {
296 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
297 cld->clear_claimed();
298 }
299 }
301 void ClassLoaderData::add_class(Klass* k) {
302 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
303 Klass* old_value = _klasses;
304 k->set_next_link(old_value);
305 // link the new item into the list
306 _klasses = k;
308 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
309 ResourceMark rm;
310 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
311 PTR_FORMAT " loader: " PTR_FORMAT " %s",
312 p2i(k),
313 k->external_name(),
314 p2i(k->class_loader_data()),
315 p2i((void *)k->class_loader()),
316 loader_name());
317 }
318 }
320 // This is called by InstanceKlass::deallocate_contents() to remove the
321 // scratch_class for redefine classes. We need a lock because there it may not
322 // be called at a safepoint if there's an error.
323 void ClassLoaderData::remove_class(Klass* scratch_class) {
324 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
325 Klass* prev = NULL;
326 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
327 if (k == scratch_class) {
328 if (prev == NULL) {
329 _klasses = k->next_link();
330 } else {
331 Klass* next = k->next_link();
332 prev->set_next_link(next);
333 }
334 return;
335 }
336 prev = k;
337 assert(k != k->next_link(), "no loops!");
338 }
339 ShouldNotReachHere(); // should have found this class!!
340 }
342 void ClassLoaderData::unload() {
343 _unloading = true;
345 // Tell serviceability tools these classes are unloading
346 classes_do(InstanceKlass::notify_unload_class);
348 if (TraceClassLoaderData) {
349 ResourceMark rm;
350 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this));
351 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
352 loader_name());
353 if (is_anonymous()) {
354 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
355 }
356 tty->print_cr("]");
357 }
358 }
360 oop ClassLoaderData::keep_alive_object() const {
361 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
362 return is_anonymous() ? _klasses->java_mirror() : class_loader();
363 }
365 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
366 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
367 || is_alive_closure->do_object_b(keep_alive_object());
369 return alive;
370 }
373 ClassLoaderData::~ClassLoaderData() {
374 // Release C heap structures for all the classes.
375 classes_do(InstanceKlass::release_C_heap_structures);
377 Metaspace *m = _metaspace;
378 if (m != NULL) {
379 _metaspace = NULL;
380 // release the metaspace
381 delete m;
382 }
384 // Clear all the JNI handles for methods
385 // These aren't deallocated and are going to look like a leak, but that's
386 // needed because we can't really get rid of jmethodIDs because we don't
387 // know when native code is going to stop using them. The spec says that
388 // they're "invalid" but existing programs likely rely on their being
389 // NULL after class unloading.
390 if (_jmethod_ids != NULL) {
391 Method::clear_jmethod_ids(this);
392 }
393 // Delete lock
394 delete _metaspace_lock;
396 // Delete free list
397 if (_deallocate_list != NULL) {
398 delete _deallocate_list;
399 }
400 }
402 /**
403 * Returns true if this class loader data is for the extension class loader.
404 */
405 bool ClassLoaderData::is_ext_class_loader_data() const {
406 return SystemDictionary::is_ext_class_loader(class_loader());
407 }
409 Metaspace* ClassLoaderData::metaspace_non_null() {
410 assert(!DumpSharedSpaces, "wrong metaspace!");
411 // If the metaspace has not been allocated, create a new one. Might want
412 // to create smaller arena for Reflection class loaders also.
413 // The reason for the delayed allocation is because some class loaders are
414 // simply for delegating with no metadata of their own.
415 if (_metaspace == NULL) {
416 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
417 // Check again if metaspace has been allocated while we were getting this lock.
418 if (_metaspace != NULL) {
419 return _metaspace;
420 }
421 if (this == the_null_class_loader_data()) {
422 assert (class_loader() == NULL, "Must be");
423 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
424 } else if (is_anonymous()) {
425 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
426 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
427 }
428 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
429 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
430 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
431 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
432 }
433 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
434 } else {
435 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
436 }
437 }
438 return _metaspace;
439 }
441 jobject ClassLoaderData::add_handle(Handle h) {
442 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
443 return (jobject) _handles.add(h());
444 }
446 // Add this metadata pointer to be freed when it's safe. This is only during
447 // class unloading because Handles might point to this metadata field.
448 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
449 // Metadata in shared region isn't deleted.
450 if (!m->is_shared()) {
451 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
452 if (_deallocate_list == NULL) {
453 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
454 }
455 _deallocate_list->append_if_missing(m);
456 }
457 }
459 // Deallocate free metadata on the free list. How useful the PermGen was!
460 void ClassLoaderData::free_deallocate_list() {
461 // Don't need lock, at safepoint
462 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
463 if (_deallocate_list == NULL) {
464 return;
465 }
466 // Go backwards because this removes entries that are freed.
467 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
468 Metadata* m = _deallocate_list->at(i);
469 if (!m->on_stack()) {
470 _deallocate_list->remove_at(i);
471 // There are only three types of metadata that we deallocate directly.
472 // Cast them so they can be used by the template function.
473 if (m->is_method()) {
474 MetadataFactory::free_metadata(this, (Method*)m);
475 } else if (m->is_constantPool()) {
476 MetadataFactory::free_metadata(this, (ConstantPool*)m);
477 } else if (m->is_klass()) {
478 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
479 } else {
480 ShouldNotReachHere();
481 }
482 }
483 }
484 }
486 // These anonymous class loaders are to contain classes used for JSR292
487 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
488 // Add a new class loader data to the graph.
489 return ClassLoaderDataGraph::add(loader, true, THREAD);
490 }
492 const char* ClassLoaderData::loader_name() {
493 // Handles null class loader
494 return SystemDictionary::loader_name(class_loader());
495 }
497 #ifndef PRODUCT
498 // Define to dump klasses
499 #undef CLD_DUMP_KLASSES
501 void ClassLoaderData::dump(outputStream * const out) {
502 ResourceMark rm;
503 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
504 p2i(this), p2i((void *)class_loader()),
505 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
506 if (claimed()) out->print(" claimed ");
507 if (is_unloading()) out->print(" unloading ");
508 out->cr();
509 if (metaspace_or_null() != NULL) {
510 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
511 metaspace_or_null()->dump(out);
512 } else {
513 out->print_cr("metaspace: NULL");
514 }
516 #ifdef CLD_DUMP_KLASSES
517 if (Verbose) {
518 ResourceMark rm;
519 Klass* k = _klasses;
520 while (k != NULL) {
521 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
522 k->has_modified_oops(), k->has_accumulated_modified_oops());
523 assert(k != k->next_link(), "no loops!");
524 k = k->next_link();
525 }
526 }
527 #endif // CLD_DUMP_KLASSES
528 #undef CLD_DUMP_KLASSES
529 if (_jmethod_ids != NULL) {
530 Method::print_jmethod_ids(this, out);
531 }
532 out->print_cr("}");
533 }
534 #endif // PRODUCT
536 void ClassLoaderData::verify() {
537 oop cl = class_loader();
539 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
540 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
542 // Verify the integrity of the allocated space.
543 if (metaspace_or_null() != NULL) {
544 metaspace_or_null()->verify();
545 }
547 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
548 guarantee(k->class_loader_data() == this, "Must be the same");
549 k->verify();
550 assert(k != k->next_link(), "no loops!");
551 }
552 }
554 bool ClassLoaderData::contains_klass(Klass* klass) {
555 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
556 if (k == klass) return true;
557 }
558 return false;
559 }
562 // GC root of class loader data created.
563 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
564 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
565 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
566 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
568 bool ClassLoaderDataGraph::_should_purge = false;
570 // Add a new class loader data node to the list. Assign the newly created
571 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
572 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
573 // We need to allocate all the oops for the ClassLoaderData before allocating the
574 // actual ClassLoaderData object.
575 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
577 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
578 // ClassLoaderData in the graph since the CLD
579 // contains unhandled oops
581 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
584 if (!is_anonymous) {
585 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
586 // First, Atomically set it
587 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
588 if (old != NULL) {
589 delete cld;
590 // Returns the data.
591 return old;
592 }
593 }
595 // We won the race, and therefore the task of adding the data to the list of
596 // class loader data
597 ClassLoaderData** list_head = &_head;
598 ClassLoaderData* next = _head;
600 do {
601 cld->set_next(next);
602 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
603 if (exchanged == next) {
604 if (TraceClassLoaderData) {
605 ResourceMark rm;
606 tty->print("[ClassLoaderData: ");
607 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld));
608 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
609 cld->loader_name());
610 tty->print_cr("]");
611 }
612 return cld;
613 }
614 next = exchanged;
615 } while (true);
617 }
619 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
620 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
621 cld->oops_do(f, klass_closure, must_claim);
622 }
623 }
625 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
626 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
627 if (cld->keep_alive()) {
628 cld->oops_do(f, klass_closure, must_claim);
629 }
630 }
631 }
633 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
634 if (ClassUnloading) {
635 keep_alive_oops_do(f, klass_closure, must_claim);
636 } else {
637 oops_do(f, klass_closure, must_claim);
638 }
639 }
641 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
642 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
643 cl->do_cld(cld);
644 }
645 }
647 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
648 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
649 // Only walk the head until any clds not purged from prior unloading
650 // (CMS doesn't purge right away).
651 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
652 assert(cld->is_unloading(), "invariant");
653 cl->do_cld(cld);
654 }
655 }
657 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
658 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
659 CLDClosure* closure = cld->keep_alive() ? strong : weak;
660 if (closure != NULL) {
661 closure->do_cld(cld);
662 }
663 }
664 }
666 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
667 roots_cld_do(cl, NULL);
668 }
670 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
671 if (ClassUnloading) {
672 keep_alive_cld_do(cl);
673 } else {
674 cld_do(cl);
675 }
676 }
678 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
679 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
680 cld->classes_do(klass_closure);
681 }
682 }
684 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
685 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
686 cld->classes_do(f);
687 }
688 }
690 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
691 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
692 cld->loaded_classes_do(klass_closure);
693 }
694 }
696 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
697 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
698 // Only walk the head until any clds not purged from prior unloading
699 // (CMS doesn't purge right away).
700 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
701 cld->classes_do(f);
702 }
703 }
705 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
706 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
708 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
710 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
711 ClassLoaderData* curr = _head;
712 while (curr != _saved_head) {
713 if (!curr->claimed()) {
714 array->push(curr);
716 if (TraceClassLoaderData) {
717 tty->print("[ClassLoaderData] found new CLD: ");
718 curr->print_value_on(tty);
719 tty->cr();
720 }
721 }
723 curr = curr->_next;
724 }
726 return array;
727 }
729 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
730 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
731 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
732 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
733 return true;
734 }
735 }
736 return false;
737 }
739 #ifndef PRODUCT
740 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
741 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
742 if (loader_data == data) {
743 return true;
744 }
745 }
747 return false;
748 }
749 #endif // PRODUCT
751 // Move class loader data from main list to the unloaded list for unloading
752 // and deallocation later.
753 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, bool clean_alive) {
754 ClassLoaderData* data = _head;
755 ClassLoaderData* prev = NULL;
756 bool seen_dead_loader = false;
758 // Save previous _unloading pointer for CMS which may add to unloading list before
759 // purging and we don't want to rewalk the previously unloaded class loader data.
760 _saved_unloading = _unloading;
762 while (data != NULL) {
763 if (data->is_alive(is_alive_closure)) {
764 prev = data;
765 data = data->next();
766 continue;
767 }
768 seen_dead_loader = true;
769 ClassLoaderData* dead = data;
770 dead->unload();
771 data = data->next();
772 // Remove from loader list.
773 // This class loader data will no longer be found
774 // in the ClassLoaderDataGraph.
775 if (prev != NULL) {
776 prev->set_next(data);
777 } else {
778 assert(dead == _head, "sanity check");
779 _head = data;
780 }
781 dead->set_next(_unloading);
782 _unloading = dead;
783 }
785 if (clean_alive) {
786 // Clean previous versions and the deallocate list.
787 ClassLoaderDataGraph::clean_metaspaces();
788 }
790 return seen_dead_loader;
791 }
793 void ClassLoaderDataGraph::clean_metaspaces() {
794 // mark metadata seen on the stack and code cache so we can delete unneeded entries.
795 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
796 MetadataOnStackMark md_on_stack(has_redefined_a_class);
798 if (has_redefined_a_class) {
799 // purge_previous_versions also cleans weak method links. Because
800 // one method's MDO can reference another method from another
801 // class loader, we need to first clean weak method links for all
802 // class loaders here. Below, we can then free redefined methods
803 // for all class loaders.
804 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
805 data->classes_do(InstanceKlass::purge_previous_versions);
806 }
807 }
809 // Need to purge the previous version before deallocating.
810 free_deallocate_lists();
811 }
813 void ClassLoaderDataGraph::purge() {
814 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
815 ClassLoaderData* list = _unloading;
816 _unloading = NULL;
817 ClassLoaderData* next = list;
818 while (next != NULL) {
819 ClassLoaderData* purge_me = next;
820 next = purge_me->next();
821 delete purge_me;
822 }
823 Metaspace::purge();
824 }
826 void ClassLoaderDataGraph::free_deallocate_lists() {
827 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
828 // We need to keep this data until InstanceKlass::purge_previous_version has been
829 // called on all alive classes. See the comment in ClassLoaderDataGraph::clean_metaspaces.
830 cld->free_deallocate_list();
831 }
833 // In some rare cases items added to the unloading list will not be freed elsewhere.
834 // To keep it simple, walk the _unloading list also.
835 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
836 cld->free_deallocate_list();
837 }
838 }
840 // CDS support
842 // Global metaspaces for writing information to the shared archive. When
843 // application CDS is supported, we may need one per metaspace, so this
844 // sort of looks like it.
845 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
846 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
847 static bool _shared_metaspaces_initialized = false;
849 // Initialize shared metaspaces (change to call from somewhere not lazily)
850 void ClassLoaderData::initialize_shared_metaspaces() {
851 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
852 assert(this == ClassLoaderData::the_null_class_loader_data(),
853 "only supported for null loader data for now");
854 assert (!_shared_metaspaces_initialized, "only initialize once");
855 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
856 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
857 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
858 _shared_metaspaces_initialized = true;
859 }
861 Metaspace* ClassLoaderData::ro_metaspace() {
862 assert(_ro_metaspace != NULL, "should already be initialized");
863 return _ro_metaspace;
864 }
866 Metaspace* ClassLoaderData::rw_metaspace() {
867 assert(_rw_metaspace != NULL, "should already be initialized");
868 return _rw_metaspace;
869 }
871 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
872 : _next_klass(NULL) {
873 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
874 Klass* klass = NULL;
876 // Find the first klass in the CLDG.
877 while (cld != NULL) {
878 klass = cld->_klasses;
879 if (klass != NULL) {
880 _next_klass = klass;
881 return;
882 }
883 cld = cld->next();
884 }
885 }
887 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
888 Klass* next = klass->next_link();
889 if (next != NULL) {
890 return next;
891 }
893 // No more klasses in the current CLD. Time to find a new CLD.
894 ClassLoaderData* cld = klass->class_loader_data();
895 while (next == NULL) {
896 cld = cld->next();
897 if (cld == NULL) {
898 break;
899 }
900 next = cld->_klasses;
901 }
903 return next;
904 }
906 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
907 Klass* head = _next_klass;
909 while (head != NULL) {
910 Klass* next = next_klass_in_cldg(head);
912 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
914 if (old_head == head) {
915 return head; // Won the CAS.
916 }
918 head = old_head;
919 }
921 // Nothing more for the iterator to hand out.
922 assert(head == NULL, err_msg("head is " PTR_FORMAT ", expected not null:", p2i(head)));
923 return NULL;
924 }
926 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
927 _data = ClassLoaderDataGraph::_head;
928 }
930 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
932 #ifndef PRODUCT
933 // callable from debugger
934 extern "C" int print_loader_data_graph() {
935 ClassLoaderDataGraph::dump_on(tty);
936 return 0;
937 }
939 void ClassLoaderDataGraph::verify() {
940 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
941 data->verify();
942 }
943 }
945 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
946 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
947 data->dump(out);
948 }
949 MetaspaceAux::dump(out);
950 }
951 #endif // PRODUCT
953 void ClassLoaderData::print_value_on(outputStream* out) const {
954 if (class_loader() == NULL) {
955 out->print("NULL class_loader");
956 } else {
957 out->print("class loader " INTPTR_FORMAT, p2i(this));
958 class_loader()->print_value_on(out);
959 }
960 }