1 /*
2 * Copyright (c) 2012, 2017, 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 #if INCLUDE_TRACE
68 #include "trace/tracing.hpp"
69 #endif
70
71 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
72
73 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
74 _class_loader(h_class_loader()),
75 _is_anonymous(is_anonymous),
76 // An anonymous class loader data doesn't have anything to keep
77 // it from being unloaded during parsing of the anonymous class.
78 // The null-class-loader should always be kept alive.
79 _keep_alive(is_anonymous || h_class_loader.is_null()),
80 _metaspace(NULL), _unloading(false), _klasses(NULL),
81 _claimed(0), _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
82 _next(NULL), _dependencies(dependencies),
83 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {
84 // empty
85 }
86
87 void ClassLoaderData::init_dependencies(TRAPS) {
88 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
89 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
90 _dependencies.init(CHECK);
91 }
92
93 void ClassLoaderData::Dependencies::init(TRAPS) {
94 // Create empty dependencies array to add to. CMS requires this to be
95 // an oop so that it can track additions via card marks. We think.
96 _list_head = oopFactory::new_objectArray(2, CHECK);
97 }
98
99 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
100 Chunk* c = _head;
101 while (c != NULL) {
102 Chunk* next = c->_next;
103 delete c;
104 c = next;
105 }
106 }
107
108 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
109 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
110 Chunk* next = new Chunk(_head);
111 OrderAccess::release_store_ptr(&_head, next);
112 }
113 oop* handle = &_head->_data[_head->_size];
114 *handle = o;
115 OrderAccess::release_store(&_head->_size, _head->_size + 1);
116 return handle;
117 }
118
119 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
120 for (juint i = 0; i < size; i++) {
121 if (c->_data[i] != NULL) {
122 f->do_oop(&c->_data[i]);
123 }
124 }
125 }
126
127 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
128 Chunk* head = (Chunk*) OrderAccess::load_ptr_acquire(&_head);
129 if (head != NULL) {
130 // Must be careful when reading size of head
131 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
132 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
133 oops_do_chunk(f, c, c->_size);
134 }
135 }
136 }
137
138 bool ClassLoaderData::claim() {
139 if (_claimed == 1) {
140 return false;
141 }
142
143 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
144 }
145
146 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
147 if (must_claim && !claim()) {
148 return;
149 }
150
151 f->do_oop(&_class_loader);
152 _dependencies.oops_do(f);
153 _handles.oops_do(f);
154 if (klass_closure != NULL) {
155 classes_do(klass_closure);
156 }
157 }
158
159 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
160 f->do_oop((oop*)&_list_head);
161 }
162
163 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
164 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
165 klass_closure->do_klass(k);
166 assert(k != k->next_link(), "no loops!");
167 }
168 }
169
170 void ClassLoaderData::classes_do(void f(Klass * const)) {
171 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
172 f(k);
173 }
174 }
175
176 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
177 // Lock to avoid classes being modified/added/removed during iteration
178 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
179 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
180 // Do not filter ArrayKlass oops here...
181 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) {
182 klass_closure->do_klass(k);
183 }
184 }
185 }
186
187 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
188 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
189 if (k->oop_is_instance()) {
190 f(InstanceKlass::cast(k));
191 }
192 assert(k != k->next_link(), "no loops!");
193 }
194 }
195
196 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
197 ClassLoaderData * const from_cld = this;
198 ClassLoaderData * const to_cld = k->class_loader_data();
199
200 // Dependency to the null class loader data doesn't need to be recorded
201 // because the null class loader data never goes away.
202 if (to_cld->is_the_null_class_loader_data()) {
203 return;
204 }
205
206 oop to;
207 if (to_cld->is_anonymous()) {
208 // Anonymous class dependencies are through the mirror.
209 to = k->java_mirror();
210 } else {
211 to = to_cld->class_loader();
212
213 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
214 // we still have to add it. The class_loader won't keep from_cld alive.
215 if (!from_cld->is_anonymous()) {
216 // Check that this dependency isn't from the same or parent class_loader
217 oop from = from_cld->class_loader();
218
219 oop curr = from;
220 while (curr != NULL) {
221 if (curr == to) {
222 return; // this class loader is in the parent list, no need to add it.
223 }
224 curr = java_lang_ClassLoader::parent(curr);
225 }
226 }
227 }
228
229 // It's a dependency we won't find through GC, add it. This is relatively rare
230 // Must handle over GC point.
231 Handle dependency(THREAD, to);
232 from_cld->_dependencies.add(dependency, CHECK);
233 }
234
235
236 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
237 // Check first if this dependency is already in the list.
238 // Save a pointer to the last to add to under the lock.
239 objArrayOop ok = _list_head;
240 objArrayOop last = NULL;
241 while (ok != NULL) {
242 last = ok;
243 if (ok->obj_at(0) == dependency()) {
244 // Don't need to add it
245 return;
246 }
247 ok = (objArrayOop)ok->obj_at(1);
248 }
249
250 // Must handle over GC points
251 assert (last != NULL, "dependencies should be initialized");
252 objArrayHandle last_handle(THREAD, last);
253
254 // Create a new dependency node with fields for (class_loader or mirror, next)
255 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
256 deps->obj_at_put(0, dependency());
257
258 // Must handle over GC points
259 objArrayHandle new_dependency(THREAD, deps);
260
261 // Add the dependency under lock
262 locked_add(last_handle, new_dependency, THREAD);
263 }
264
265 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
266 objArrayHandle new_dependency,
267 Thread* THREAD) {
268
269 // Have to lock and put the new dependency on the end of the dependency
270 // array so the card mark for CMS sees that this dependency is new.
271 // Can probably do this lock free with some effort.
272 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
273
274 oop loader_or_mirror = new_dependency->obj_at(0);
275
276 // Since the dependencies are only added, add to the end.
277 objArrayOop end = last_handle();
278 objArrayOop last = NULL;
279 while (end != NULL) {
280 last = end;
281 // check again if another thread added it to the end.
282 if (end->obj_at(0) == loader_or_mirror) {
283 // Don't need to add it
284 return;
285 }
286 end = (objArrayOop)end->obj_at(1);
287 }
288 assert (last != NULL, "dependencies should be initialized");
289 // fill in the first element with the oop in new_dependency.
290 if (last->obj_at(0) == NULL) {
291 last->obj_at_put(0, new_dependency->obj_at(0));
292 } else {
293 last->obj_at_put(1, new_dependency());
294 }
295 }
296
297 void ClassLoaderDataGraph::clear_claimed_marks() {
298 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
299 cld->clear_claimed();
300 }
301 }
302
303 void ClassLoaderData::add_class(Klass* k) {
304 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
305 Klass* old_value = _klasses;
306 k->set_next_link(old_value);
307 // link the new item into the list
308 _klasses = k;
309
310 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
311 ResourceMark rm;
312 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
313 PTR_FORMAT " loader: " PTR_FORMAT " %s",
314 p2i(k),
315 k->external_name(),
316 p2i(k->class_loader_data()),
317 p2i((void *)k->class_loader()),
318 loader_name());
319 }
320 }
321
322 // This is called by InstanceKlass::deallocate_contents() to remove the
323 // scratch_class for redefine classes. We need a lock because there it may not
324 // be called at a safepoint if there's an error.
325 void ClassLoaderData::remove_class(Klass* scratch_class) {
326 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
327 Klass* prev = NULL;
328 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
329 if (k == scratch_class) {
330 if (prev == NULL) {
331 _klasses = k->next_link();
332 } else {
333 Klass* next = k->next_link();
334 prev->set_next_link(next);
335 }
336 return;
337 }
338 prev = k;
339 assert(k != k->next_link(), "no loops!");
340 }
341 ShouldNotReachHere(); // should have found this class!!
342 }
343
344 void ClassLoaderData::unload() {
345 _unloading = true;
346
347 // Tell serviceability tools these classes are unloading
348 classes_do(InstanceKlass::notify_unload_class);
349
350 if (TraceClassLoaderData) {
351 ResourceMark rm;
352 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this));
353 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
354 loader_name());
355 if (is_anonymous()) {
356 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
357 }
358 tty->print_cr("]");
359 }
360 }
361
362 oop ClassLoaderData::keep_alive_object() const {
363 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
364 return is_anonymous() ? _klasses->java_mirror() : class_loader();
365 }
366
367 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
368 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
369 || is_alive_closure->do_object_b(keep_alive_object());
370
371 return alive;
372 }
373
374
375 ClassLoaderData::~ClassLoaderData() {
376 // Release C heap structures for all the classes.
377 classes_do(InstanceKlass::release_C_heap_structures);
378
379 Metaspace *m = _metaspace;
380 if (m != NULL) {
381 _metaspace = NULL;
382 // release the metaspace
383 delete m;
384 }
385
386 // Clear all the JNI handles for methods
387 // These aren't deallocated and are going to look like a leak, but that's
388 // needed because we can't really get rid of jmethodIDs because we don't
389 // know when native code is going to stop using them. The spec says that
390 // they're "invalid" but existing programs likely rely on their being
391 // NULL after class unloading.
392 if (_jmethod_ids != NULL) {
393 Method::clear_jmethod_ids(this);
394 }
395 // Delete lock
396 delete _metaspace_lock;
397
398 // Delete free list
399 if (_deallocate_list != NULL) {
400 delete _deallocate_list;
401 }
402 }
403
404 /**
405 * Returns true if this class loader data is for the extension class loader.
406 */
407 bool ClassLoaderData::is_ext_class_loader_data() const {
408 return SystemDictionary::is_ext_class_loader(class_loader());
409 }
410
411 Metaspace* ClassLoaderData::metaspace_non_null() {
412 assert(!DumpSharedSpaces, "wrong metaspace!");
413 // If the metaspace has not been allocated, create a new one. Might want
414 // to create smaller arena for Reflection class loaders also.
415 // The reason for the delayed allocation is because some class loaders are
416 // simply for delegating with no metadata of their own.
417 if (_metaspace == NULL) {
418 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
419 // Check again if metaspace has been allocated while we were getting this lock.
420 if (_metaspace != NULL) {
421 return _metaspace;
422 }
423 if (this == the_null_class_loader_data()) {
424 assert (class_loader() == NULL, "Must be");
425 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
426 } else if (is_anonymous()) {
427 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
428 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
429 }
430 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
431 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
432 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
433 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
434 }
435 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
436 } else {
437 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
438 }
439 }
440 return _metaspace;
441 }
442
443 jobject ClassLoaderData::add_handle(Handle h) {
444 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
445 return (jobject) _handles.add(h());
446 }
447
448 // Add this metadata pointer to be freed when it's safe. This is only during
449 // class unloading because Handles might point to this metadata field.
450 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
451 // Metadata in shared region isn't deleted.
452 if (!m->is_shared()) {
453 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
454 if (_deallocate_list == NULL) {
455 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
456 }
457 _deallocate_list->append_if_missing(m);
458 }
459 }
460
461 // Deallocate free metadata on the free list. How useful the PermGen was!
462 void ClassLoaderData::free_deallocate_list() {
463 // Don't need lock, at safepoint
464 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
465 if (_deallocate_list == NULL) {
466 return;
467 }
468 // Go backwards because this removes entries that are freed.
469 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
470 Metadata* m = _deallocate_list->at(i);
471 if (!m->on_stack()) {
472 _deallocate_list->remove_at(i);
473 // There are only three types of metadata that we deallocate directly.
474 // Cast them so they can be used by the template function.
475 if (m->is_method()) {
476 MetadataFactory::free_metadata(this, (Method*)m);
477 } else if (m->is_constantPool()) {
478 MetadataFactory::free_metadata(this, (ConstantPool*)m);
479 } else if (m->is_klass()) {
480 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
481 } else {
482 ShouldNotReachHere();
483 }
484 }
485 }
486 }
487
488 // These anonymous class loaders are to contain classes used for JSR292
489 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
490 // Add a new class loader data to the graph.
491 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL);
492 }
493
494 const char* ClassLoaderData::loader_name() {
495 // Handles null class loader
496 return SystemDictionary::loader_name(class_loader());
497 }
498
499 #ifndef PRODUCT
500 // Define to dump klasses
501 #undef CLD_DUMP_KLASSES
502
503 void ClassLoaderData::dump(outputStream * const out) {
504 ResourceMark rm;
505 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
506 p2i(this), p2i((void *)class_loader()),
507 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
508 if (claimed()) out->print(" claimed ");
509 if (is_unloading()) out->print(" unloading ");
510 out->cr();
511 if (metaspace_or_null() != NULL) {
512 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
513 metaspace_or_null()->dump(out);
514 } else {
515 out->print_cr("metaspace: NULL");
516 }
517
518 #ifdef CLD_DUMP_KLASSES
519 if (Verbose) {
520 ResourceMark rm;
521 Klass* k = _klasses;
522 while (k != NULL) {
523 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
524 k->has_modified_oops(), k->has_accumulated_modified_oops());
525 assert(k != k->next_link(), "no loops!");
526 k = k->next_link();
527 }
528 }
529 #endif // CLD_DUMP_KLASSES
530 #undef CLD_DUMP_KLASSES
531 if (_jmethod_ids != NULL) {
532 Method::print_jmethod_ids(this, out);
533 }
534 out->print_cr("}");
535 }
536 #endif // PRODUCT
537
538 void ClassLoaderData::verify() {
539 oop cl = class_loader();
540
541 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
542 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
543
544 // Verify the integrity of the allocated space.
545 if (metaspace_or_null() != NULL) {
546 metaspace_or_null()->verify();
547 }
548
549 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
550 guarantee(k->class_loader_data() == this, "Must be the same");
551 k->verify();
552 assert(k != k->next_link(), "no loops!");
553 }
554 }
555
556 bool ClassLoaderData::contains_klass(Klass* klass) {
557 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
558 if (k == klass) return true;
559 }
560 return false;
561 }
562
563
564 // GC root of class loader data created.
565 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
566 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
567 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
568 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
569
570 bool ClassLoaderDataGraph::_should_purge = false;
571
572 // Add a new class loader data node to the list. Assign the newly created
573 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
574 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
575 // We need to allocate all the oops for the ClassLoaderData before allocating the
576 // actual ClassLoaderData object.
577 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
578
579 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
580 // ClassLoaderData in the graph since the CLD
581 // contains unhandled oops
582
583 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
584
585
586 if (!is_anonymous) {
587 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
588 // First, Atomically set it
589 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
590 if (old != NULL) {
591 delete cld;
592 // Returns the data.
593 return old;
594 }
595 }
596
597 // We won the race, and therefore the task of adding the data to the list of
598 // class loader data
599 ClassLoaderData** list_head = &_head;
600 ClassLoaderData* next = _head;
601
602 do {
603 cld->set_next(next);
604 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
605 if (exchanged == next) {
606 if (TraceClassLoaderData) {
607 ResourceMark rm;
608 tty->print("[ClassLoaderData: ");
609 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld));
610 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
611 cld->loader_name());
612 tty->print_cr("]");
613 }
614 return cld;
615 }
616 next = exchanged;
617 } while (true);
618
619 }
620
621 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
622 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
623 cld->oops_do(f, klass_closure, must_claim);
624 }
625 }
626
627 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
628 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
629 if (cld->keep_alive()) {
630 cld->oops_do(f, klass_closure, must_claim);
631 }
632 }
633 }
634
635 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
636 if (ClassUnloading) {
637 keep_alive_oops_do(f, klass_closure, must_claim);
638 } else {
639 oops_do(f, klass_closure, must_claim);
640 }
641 }
642
643 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
644 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
645 cl->do_cld(cld);
646 }
647 }
648
649 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
650 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
651 CLDClosure* closure = cld->keep_alive() ? strong : weak;
652 if (closure != NULL) {
653 closure->do_cld(cld);
654 }
655 }
656 }
657
658 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
659 roots_cld_do(cl, NULL);
660 }
661
662 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
663 if (ClassUnloading) {
664 keep_alive_cld_do(cl);
665 } else {
666 cld_do(cl);
667 }
668 }
669
670 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
671 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
672 cld->classes_do(klass_closure);
673 }
674 }
675
676 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
677 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
678 cld->classes_do(f);
679 }
680 }
681
682 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
683 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
684 cld->loaded_classes_do(klass_closure);
685 }
686 }
687
688 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
689 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
690 // Only walk the head until any clds not purged from prior unloading
691 // (CMS doesn't purge right away).
692 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
693 cld->classes_do(f);
694 }
695 }
696
697 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
698 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
699
700 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
701
702 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
703 ClassLoaderData* curr = _head;
704 while (curr != _saved_head) {
705 if (!curr->claimed()) {
706 array->push(curr);
707
708 if (TraceClassLoaderData) {
709 tty->print("[ClassLoaderData] found new CLD: ");
710 curr->print_value_on(tty);
711 tty->cr();
712 }
713 }
714
715 curr = curr->_next;
716 }
717
718 return array;
719 }
720
721 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
722 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
723 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
724 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
725 return true;
726 }
727 }
728 return false;
729 }
730
731 #ifndef PRODUCT
732 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
733 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
734 if (loader_data == data) {
735 return true;
736 }
737 }
738
739 return false;
740 }
741 #endif // PRODUCT
742
743
744 // Move class loader data from main list to the unloaded list for unloading
745 // and deallocation later.
746 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, bool clean_alive) {
747 ClassLoaderData* data = _head;
748 ClassLoaderData* prev = NULL;
749 bool seen_dead_loader = false;
750
751 // Save previous _unloading pointer for CMS which may add to unloading list before
752 // purging and we don't want to rewalk the previously unloaded class loader data.
753 _saved_unloading = _unloading;
754
755 while (data != NULL) {
756 if (data->is_alive(is_alive_closure)) {
757 prev = data;
758 data = data->next();
759 continue;
760 }
761 seen_dead_loader = true;
762 ClassLoaderData* dead = data;
763 dead->unload();
764 data = data->next();
765 // Remove from loader list.
766 // This class loader data will no longer be found
767 // in the ClassLoaderDataGraph.
768 if (prev != NULL) {
769 prev->set_next(data);
770 } else {
771 assert(dead == _head, "sanity check");
772 _head = data;
773 }
774 dead->set_next(_unloading);
775 _unloading = dead;
776 }
777
778 if (clean_alive) {
779 // Clean previous versions and the deallocate list.
780 ClassLoaderDataGraph::clean_metaspaces();
781 }
782
783 if (seen_dead_loader) {
784 post_class_unload_events();
785 }
786
787 return seen_dead_loader;
788 }
789
790 void ClassLoaderDataGraph::clean_metaspaces() {
791 // mark metadata seen on the stack and code cache so we can delete unneeded entries.
792 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
793 MetadataOnStackMark md_on_stack(has_redefined_a_class);
794
795 if (has_redefined_a_class) {
796 // purge_previous_versions also cleans weak method links. Because
797 // one method's MDO can reference another method from another
798 // class loader, we need to first clean weak method links for all
799 // class loaders here. Below, we can then free redefined methods
800 // for all class loaders.
801 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
802 data->classes_do(InstanceKlass::purge_previous_versions);
803 }
804 }
805
806 // Need to purge the previous version before deallocating.
807 free_deallocate_lists();
808 }
809
810 void ClassLoaderDataGraph::purge() {
811 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
812 ClassLoaderData* list = _unloading;
813 _unloading = NULL;
814 ClassLoaderData* next = list;
815 while (next != NULL) {
816 ClassLoaderData* purge_me = next;
817 next = purge_me->next();
818 delete purge_me;
819 }
820 Metaspace::purge();
821 }
822
823 void ClassLoaderDataGraph::post_class_unload_events(void) {
824 #if INCLUDE_TRACE
825 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
826 if (Tracing::enabled()) {
827 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
828 assert(_unloading != NULL, "need class loader data unload list!");
829 _class_unload_time = Ticks::now();
830 classes_unloading_do(&class_unload_event);
831 }
832 Tracing::on_unloading_classes();
833 }
834 #endif
835 }
836
837 void ClassLoaderDataGraph::free_deallocate_lists() {
838 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
839 // We need to keep this data until InstanceKlass::purge_previous_version has been
840 // called on all alive classes. See the comment in ClassLoaderDataGraph::clean_metaspaces.
841 cld->free_deallocate_list();
842 }
843
844 // In some rare cases items added to the unloading list will not be freed elsewhere.
845 // To keep it simple, walk the _unloading list also.
846 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
847 cld->free_deallocate_list();
848 }
849 }
850
851 // CDS support
852
853 // Global metaspaces for writing information to the shared archive. When
854 // application CDS is supported, we may need one per metaspace, so this
855 // sort of looks like it.
856 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
857 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
858 static bool _shared_metaspaces_initialized = false;
859
860 // Initialize shared metaspaces (change to call from somewhere not lazily)
861 void ClassLoaderData::initialize_shared_metaspaces() {
862 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
863 assert(this == ClassLoaderData::the_null_class_loader_data(),
864 "only supported for null loader data for now");
865 assert (!_shared_metaspaces_initialized, "only initialize once");
866 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
867 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
868 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
869 _shared_metaspaces_initialized = true;
870 }
871
872 Metaspace* ClassLoaderData::ro_metaspace() {
873 assert(_ro_metaspace != NULL, "should already be initialized");
874 return _ro_metaspace;
875 }
876
877 Metaspace* ClassLoaderData::rw_metaspace() {
878 assert(_rw_metaspace != NULL, "should already be initialized");
879 return _rw_metaspace;
880 }
881
882 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
883 : _next_klass(NULL) {
884 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
885 Klass* klass = NULL;
886
887 // Find the first klass in the CLDG.
888 while (cld != NULL) {
889 klass = cld->_klasses;
890 if (klass != NULL) {
891 _next_klass = klass;
892 return;
893 }
894 cld = cld->next();
895 }
896 }
897
898 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
899 Klass* next = klass->next_link();
900 if (next != NULL) {
901 return next;
902 }
903
904 // No more klasses in the current CLD. Time to find a new CLD.
905 ClassLoaderData* cld = klass->class_loader_data();
906 while (next == NULL) {
907 cld = cld->next();
908 if (cld == NULL) {
909 break;
910 }
911 next = cld->_klasses;
912 }
913
914 return next;
915 }
916
917 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
918 Klass* head = _next_klass;
919
920 while (head != NULL) {
921 Klass* next = next_klass_in_cldg(head);
922
923 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
924
925 if (old_head == head) {
926 return head; // Won the CAS.
927 }
928
929 head = old_head;
930 }
931
932 // Nothing more for the iterator to hand out.
933 assert(head == NULL, err_msg("head is " PTR_FORMAT ", expected not null:", p2i(head)));
934 return NULL;
935 }
936
937 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
938 _data = ClassLoaderDataGraph::_head;
939 }
940
941 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
942
943 #ifndef PRODUCT
944 // callable from debugger
945 extern "C" int print_loader_data_graph() {
946 ClassLoaderDataGraph::dump_on(tty);
947 return 0;
948 }
949
950 void ClassLoaderDataGraph::verify() {
951 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
952 data->verify();
953 }
954 }
955
956 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
957 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
958 data->dump(out);
959 }
960 MetaspaceAux::dump(out);
961 }
962 #endif // PRODUCT
963
964 void ClassLoaderData::print_value_on(outputStream* out) const {
965 if (class_loader() == NULL) {
966 out->print("NULL class_loader");
967 } else {
968 out->print("class loader " INTPTR_FORMAT, p2i(this));
969 class_loader()->print_value_on(out);
970 }
971 }
972
973 #if INCLUDE_TRACE
974
975 Ticks ClassLoaderDataGraph::_class_unload_time;
976
977 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
978
979 // post class unload event
980 EventClassUnload event(UNTIMED);
981 event.set_endtime(_class_unload_time);
982 event.set_unloadedClass(k);
983 oop defining_class_loader = k->class_loader();
984 event.set_definingClassLoader(defining_class_loader != NULL ?
985 defining_class_loader->klass() : (Klass*)NULL);
986 event.commit();
987 }
988
989 #endif // INCLUDE_TRACE