1 /*
2 * Copyright (c) 2012, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // A ClassLoaderData identifies the full set of class types that a class
26 // loader's name resolution strategy produces for a given configuration of the
27 // class loader.
28 // Class types in the ClassLoaderData may be defined by from class file binaries
29 // provided by the class loader, or from other class loader it interacts with
30 // according to its name resolution strategy.
31 //
32 // Class loaders that implement a deterministic name resolution strategy
33 // (including with respect to their delegation behavior), such as the boot, the
34 // extension, and the system loaders of the JDK's built-in class loader
35 // hierarchy, always produce the same linkset for a given configuration.
36 //
37 // ClassLoaderData carries information related to a linkset (e.g.,
38 // metaspace holding its klass definitions).
39 // The System Dictionary and related data structures (e.g., placeholder table,
40 // loader constraints table) as well as the runtime representation of classes
41 // only reference ClassLoaderData.
42 //
43 // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that
44 // that represent the loader's "linking domain" in the JVM.
45 //
46 // The bootstrap loader (represented by NULL) also has a ClassLoaderData,
47 // the singleton class the_null_class_loader_data().
48
49 #include "precompiled.hpp"
50 #include "classfile/classLoaderData.hpp"
51 #include "classfile/classLoaderData.inline.hpp"
52 #include "classfile/javaClasses.hpp"
53 #include "classfile/metadataOnStackMark.hpp"
54 #include "classfile/systemDictionary.hpp"
55 #include "code/codeCache.hpp"
56 #include "memory/gcLocker.hpp"
57 #include "memory/metadataFactory.hpp"
58 #include "memory/metaspaceShared.hpp"
59 #include "memory/oopFactory.hpp"
60 #include "runtime/atomic.inline.hpp"
61 #include "runtime/jniHandles.hpp"
62 #include "runtime/mutex.hpp"
63 #include "runtime/safepoint.hpp"
64 #include "runtime/synchronizer.hpp"
65 #include "utilities/growableArray.hpp"
66 #include "utilities/macros.hpp"
67 #include "utilities/ostream.hpp"
68
69 #if INCLUDE_TRACE
70 #include "trace/tracing.hpp"
71 #endif
72
73 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
74
75 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
76 _class_loader(h_class_loader()),
77 _is_anonymous(is_anonymous),
78 // An anonymous class loader data doesn't have anything to keep
79 // it from being unloaded during parsing of the anonymous class.
80 // The null-class-loader should always be kept alive.
81 _keep_alive(is_anonymous || h_class_loader.is_null()),
82 _metaspace(NULL), _unloading(false), _klasses(NULL),
83 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
84 _next(NULL), _dependencies(dependencies),
85 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {
86 // empty
87 }
88
89 void ClassLoaderData::init_dependencies(TRAPS) {
90 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
91 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
92 _dependencies.init(CHECK);
93 }
94
95 void ClassLoaderData::Dependencies::init(TRAPS) {
96 // Create empty dependencies array to add to. CMS requires this to be
97 // an oop so that it can track additions via card marks. We think.
98 _list_head = oopFactory::new_objectArray(2, CHECK);
99 }
100
101 bool ClassLoaderData::claim() {
102 if (_claimed == 1) {
103 return false;
104 }
105
106 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
107 }
108
109 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
110 if (must_claim && !claim()) {
111 return;
112 }
113
114 f->do_oop(&_class_loader);
115 _dependencies.oops_do(f);
116 _handles->oops_do(f);
117 if (klass_closure != NULL) {
118 classes_do(klass_closure);
119 }
120 }
121
122 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
123 f->do_oop((oop*)&_list_head);
124 }
125
126 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
127 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
128 klass_closure->do_klass(k);
129 assert(k != k->next_link(), "no loops!");
130 }
131 }
132
133 void ClassLoaderData::classes_do(void f(Klass * const)) {
134 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
135 f(k);
136 }
137 }
138
139 void ClassLoaderData::methods_do(void f(Method*)) {
140 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
141 if (k->oop_is_instance()) {
142 InstanceKlass::cast(k)->methods_do(f);
143 }
144 }
145 }
146
147 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
148 // Lock to avoid classes being modified/added/removed during iteration
149 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
150 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
151 // Do not filter ArrayKlass oops here...
152 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) {
153 klass_closure->do_klass(k);
154 }
155 }
156 }
157
158 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
159 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
160 if (k->oop_is_instance()) {
161 f(InstanceKlass::cast(k));
162 }
163 assert(k != k->next_link(), "no loops!");
164 }
165 }
166
167 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
168 ClassLoaderData * const from_cld = this;
169 ClassLoaderData * const to_cld = k->class_loader_data();
170
171 // Dependency to the null class loader data doesn't need to be recorded
172 // because the null class loader data never goes away.
173 if (to_cld->is_the_null_class_loader_data()) {
174 return;
175 }
176
177 oop to;
178 if (to_cld->is_anonymous()) {
179 // Anonymous class dependencies are through the mirror.
180 to = k->java_mirror();
181 } else {
182 to = to_cld->class_loader();
183
184 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
185 // we still have to add it. The class_loader won't keep from_cld alive.
186 if (!from_cld->is_anonymous()) {
187 // Check that this dependency isn't from the same or parent class_loader
188 oop from = from_cld->class_loader();
189
190 oop curr = from;
191 while (curr != NULL) {
192 if (curr == to) {
193 return; // this class loader is in the parent list, no need to add it.
194 }
195 curr = java_lang_ClassLoader::parent(curr);
196 }
197 }
198 }
199
200 // It's a dependency we won't find through GC, add it. This is relatively rare
201 // Must handle over GC point.
202 Handle dependency(THREAD, to);
203 from_cld->_dependencies.add(dependency, CHECK);
204 }
205
206
207 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
208 // Check first if this dependency is already in the list.
209 // Save a pointer to the last to add to under the lock.
210 objArrayOop ok = _list_head;
211 objArrayOop last = NULL;
212 while (ok != NULL) {
213 last = ok;
214 if (ok->obj_at(0) == dependency()) {
215 // Don't need to add it
216 return;
217 }
218 ok = (objArrayOop)ok->obj_at(1);
219 }
220
221 // Must handle over GC points
222 assert (last != NULL, "dependencies should be initialized");
223 objArrayHandle last_handle(THREAD, last);
224
225 // Create a new dependency node with fields for (class_loader or mirror, next)
226 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
227 deps->obj_at_put(0, dependency());
228
229 // Must handle over GC points
230 objArrayHandle new_dependency(THREAD, deps);
231
232 // Add the dependency under lock
233 locked_add(last_handle, new_dependency, THREAD);
234 }
235
236 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
237 objArrayHandle new_dependency,
238 Thread* THREAD) {
239
240 // Have to lock and put the new dependency on the end of the dependency
241 // array so the card mark for CMS sees that this dependency is new.
242 // Can probably do this lock free with some effort.
243 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
244
245 oop loader_or_mirror = new_dependency->obj_at(0);
246
247 // Since the dependencies are only added, add to the end.
248 objArrayOop end = last_handle();
249 objArrayOop last = NULL;
250 while (end != NULL) {
251 last = end;
252 // check again if another thread added it to the end.
253 if (end->obj_at(0) == loader_or_mirror) {
254 // Don't need to add it
255 return;
256 }
257 end = (objArrayOop)end->obj_at(1);
258 }
259 assert (last != NULL, "dependencies should be initialized");
260 // fill in the first element with the oop in new_dependency.
261 if (last->obj_at(0) == NULL) {
262 last->obj_at_put(0, new_dependency->obj_at(0));
263 } else {
264 last->obj_at_put(1, new_dependency());
265 }
266 }
267
268 void ClassLoaderDataGraph::clear_claimed_marks() {
269 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
270 cld->clear_claimed();
271 }
272 }
273
274 void ClassLoaderData::add_class(Klass* k) {
275 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
276 Klass* old_value = _klasses;
277 k->set_next_link(old_value);
278 // Make sure linked class is stable, since the class list is walked without a lock
279 OrderAccess::storestore();
280 // link the new item into the list
281 _klasses = k;
282
283 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
284 ResourceMark rm;
285 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
286 PTR_FORMAT " loader: " PTR_FORMAT " %s",
287 p2i(k),
288 k->external_name(),
289 p2i(k->class_loader_data()),
290 p2i((void *)k->class_loader()),
291 loader_name());
292 }
293 }
294
295 // This is called by InstanceKlass::deallocate_contents() to remove the
296 // scratch_class for redefine classes. We need a lock because there it may not
297 // be called at a safepoint if there's an error.
298 void ClassLoaderData::remove_class(Klass* scratch_class) {
299 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
300 Klass* prev = NULL;
301 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
302 if (k == scratch_class) {
303 if (prev == NULL) {
304 _klasses = k->next_link();
305 } else {
306 Klass* next = k->next_link();
307 prev->set_next_link(next);
308 }
309 return;
310 }
311 prev = k;
312 assert(k != k->next_link(), "no loops!");
313 }
314 ShouldNotReachHere(); // should have found this class!!
315 }
316
317 void ClassLoaderData::unload() {
318 _unloading = true;
319
320 // Tell serviceability tools these classes are unloading
321 classes_do(InstanceKlass::notify_unload_class);
322
323 if (TraceClassLoaderData) {
324 ResourceMark rm;
325 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this));
326 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
327 loader_name());
328 if (is_anonymous()) {
329 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
330 }
331 tty->print_cr("]");
332 }
333 }
334
335 #ifdef ASSERT
336 class AllAliveClosure : public OopClosure {
337 BoolObjectClosure* _is_alive_closure;
338 bool _found_dead;
339 public:
340 AllAliveClosure(BoolObjectClosure* is_alive_closure) : _is_alive_closure(is_alive_closure), _found_dead(false) {}
341 template <typename T> void do_oop_work(T* p) {
342 T heap_oop = oopDesc::load_heap_oop(p);
343 if (!oopDesc::is_null(heap_oop)) {
344 oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
345 if (!_is_alive_closure->do_object_b(obj)) {
346 _found_dead = true;
347 }
348 }
349 }
350 void do_oop(oop* p) { do_oop_work<oop>(p); }
351 void do_oop(narrowOop* p) { do_oop_work<narrowOop>(p); }
352 bool found_dead() { return _found_dead; }
353 };
354 #endif
355
356 oop ClassLoaderData::keep_alive_object() const {
357 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
358 return is_anonymous() ? _klasses->java_mirror() : class_loader();
359 }
360
361 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
362 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
363 || is_alive_closure->do_object_b(keep_alive_object());
364
365 #ifdef ASSERT
366 if (alive) {
367 AllAliveClosure all_alive_closure(is_alive_closure);
368 KlassToOopClosure klass_closure(&all_alive_closure);
369 const_cast<ClassLoaderData*>(this)->oops_do(&all_alive_closure, &klass_closure, false);
370 assert(!all_alive_closure.found_dead(), err_msg("Found dead oop in alive cld: " PTR_FORMAT, p2i(this)));
371 }
372 #endif
373
374 return alive;
375 }
376
377
378 ClassLoaderData::~ClassLoaderData() {
379 // Release C heap structures for all the classes.
380 classes_do(InstanceKlass::release_C_heap_structures);
381
382 Metaspace *m = _metaspace;
383 if (m != NULL) {
384 _metaspace = NULL;
385 // release the metaspace
386 delete m;
387 // release the handles
388 if (_handles != NULL) {
389 JNIHandleBlock::release_block(_handles);
390 _handles = NULL;
391 }
392 }
393
394 // Clear all the JNI handles for methods
395 // These aren't deallocated and are going to look like a leak, but that's
396 // needed because we can't really get rid of jmethodIDs because we don't
397 // know when native code is going to stop using them. The spec says that
398 // they're "invalid" but existing programs likely rely on their being
399 // NULL after class unloading.
400 if (_jmethod_ids != NULL) {
401 Method::clear_jmethod_ids(this);
402 }
403 // Delete lock
404 delete _metaspace_lock;
405
406 // Delete free list
407 if (_deallocate_list != NULL) {
408 delete _deallocate_list;
409 }
410 }
411
412 /**
413 * Returns true if this class loader data is for the extension class loader.
414 */
415 bool ClassLoaderData::is_ext_class_loader_data() const {
416 return SystemDictionary::is_ext_class_loader(class_loader());
417 }
418
419 Metaspace* ClassLoaderData::metaspace_non_null() {
420 assert(!DumpSharedSpaces, "wrong metaspace!");
421 // If the metaspace has not been allocated, create a new one. Might want
422 // to create smaller arena for Reflection class loaders also.
423 // The reason for the delayed allocation is because some class loaders are
424 // simply for delegating with no metadata of their own.
425 if (_metaspace == NULL) {
426 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
427 // Check again if metaspace has been allocated while we were getting this lock.
428 if (_metaspace != NULL) {
429 return _metaspace;
430 }
431 if (this == the_null_class_loader_data()) {
432 assert (class_loader() == NULL, "Must be");
433 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
434 } else if (is_anonymous()) {
435 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
436 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
437 }
438 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
439 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
440 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
441 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
442 }
443 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
444 } else {
445 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
446 }
447 }
448 return _metaspace;
449 }
450
451 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
452 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
453
454 jobject ClassLoaderData::add_handle(Handle h) {
455 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
456 if (handles() == NULL) {
457 set_handles(JNIHandleBlock::allocate_block());
458 }
459 return handles()->allocate_handle(h());
460 }
461
462 // Add this metadata pointer to be freed when it's safe. This is only during
463 // class unloading because Handles might point to this metadata field.
464 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
465 // Metadata in shared region isn't deleted.
466 if (!m->is_shared()) {
467 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
468 if (_deallocate_list == NULL) {
469 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
470 }
471 _deallocate_list->append_if_missing(m);
472 }
473 }
474
475 // Deallocate free metadata on the free list. How useful the PermGen was!
476 void ClassLoaderData::free_deallocate_list() {
477 // Don't need lock, at safepoint
478 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
479 if (_deallocate_list == NULL) {
480 return;
481 }
482 // Go backwards because this removes entries that are freed.
483 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
484 Metadata* m = _deallocate_list->at(i);
485 if (!m->on_stack()) {
486 _deallocate_list->remove_at(i);
487 // There are only three types of metadata that we deallocate directly.
488 // Cast them so they can be used by the template function.
489 if (m->is_method()) {
490 MetadataFactory::free_metadata(this, (Method*)m);
491 } else if (m->is_constantPool()) {
492 MetadataFactory::free_metadata(this, (ConstantPool*)m);
493 } else if (m->is_klass()) {
494 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
495 } else {
496 ShouldNotReachHere();
497 }
498 }
499 }
500 }
501
502 // These anonymous class loaders are to contain classes used for JSR292
503 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
504 // Add a new class loader data to the graph.
505 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL);
506 }
507
508 const char* ClassLoaderData::loader_name() {
509 // Handles null class loader
510 return SystemDictionary::loader_name(class_loader());
511 }
512
513 #ifndef PRODUCT
514 // Define to dump klasses
515 #undef CLD_DUMP_KLASSES
516
517 void ClassLoaderData::dump(outputStream * const out) {
518 ResourceMark rm;
519 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {",
520 p2i(this), p2i((void *)class_loader()),
521 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
522 if (claimed()) out->print(" claimed ");
523 if (is_unloading()) out->print(" unloading ");
524 out->print(" handles " INTPTR_FORMAT, p2i(handles()));
525 out->cr();
526 if (metaspace_or_null() != NULL) {
527 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
528 metaspace_or_null()->dump(out);
529 } else {
530 out->print_cr("metaspace: NULL");
531 }
532
533 #ifdef CLD_DUMP_KLASSES
534 if (Verbose) {
535 ResourceMark rm;
536 Klass* k = _klasses;
537 while (k != NULL) {
538 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
539 k->has_modified_oops(), k->has_accumulated_modified_oops());
540 assert(k != k->next_link(), "no loops!");
541 k = k->next_link();
542 }
543 }
544 #endif // CLD_DUMP_KLASSES
545 #undef CLD_DUMP_KLASSES
546 if (_jmethod_ids != NULL) {
547 Method::print_jmethod_ids(this, out);
548 }
549 out->print_cr("}");
550 }
551 #endif // PRODUCT
552
553 void ClassLoaderData::verify() {
554 oop cl = class_loader();
555
556 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
557 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
558
559 // Verify the integrity of the allocated space.
560 if (metaspace_or_null() != NULL) {
561 metaspace_or_null()->verify();
562 }
563
564 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
565 guarantee(k->class_loader_data() == this, "Must be the same");
566 k->verify();
567 assert(k != k->next_link(), "no loops!");
568 }
569 }
570
571 bool ClassLoaderData::contains_klass(Klass* klass) {
572 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
573 if (k == klass) return true;
574 }
575 return false;
576 }
577
578
579 // GC root of class loader data created.
580 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
581 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
582 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
583
584 bool ClassLoaderDataGraph::_should_purge = false;
585
586 // Add a new class loader data node to the list. Assign the newly created
587 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
588 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
589 // We need to allocate all the oops for the ClassLoaderData before allocating the
590 // actual ClassLoaderData object.
591 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
592
593 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
594 // ClassLoaderData in the graph since the CLD
595 // contains unhandled oops
596
597 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
598
599
600 if (!is_anonymous) {
601 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
602 // First, Atomically set it
603 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
604 if (old != NULL) {
605 delete cld;
606 // Returns the data.
607 return old;
608 }
609 }
610
611 // We won the race, and therefore the task of adding the data to the list of
612 // class loader data
613 ClassLoaderData** list_head = &_head;
614 ClassLoaderData* next = _head;
615
616 do {
617 cld->set_next(next);
618 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
619 if (exchanged == next) {
620 if (TraceClassLoaderData) {
621 ResourceMark rm;
622 tty->print("[ClassLoaderData: ");
623 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld));
624 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
625 cld->loader_name());
626 tty->print_cr("]");
627 }
628 return cld;
629 }
630 next = exchanged;
631 } while (true);
632
633 }
634
635 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
636 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
637 cld->oops_do(f, klass_closure, must_claim);
638 }
639 }
640
641 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
642 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
643 if (cld->keep_alive()) {
644 cld->oops_do(f, klass_closure, must_claim);
645 }
646 }
647 }
648
649 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
650 if (ClassUnloading) {
651 keep_alive_oops_do(f, klass_closure, must_claim);
652 } else {
653 oops_do(f, klass_closure, must_claim);
654 }
655 }
656
657 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
658 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
659 cl->do_cld(cld);
660 }
661 }
662
663 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
664 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
665 CLDClosure* closure = cld->keep_alive() ? strong : weak;
666 if (closure != NULL) {
667 closure->do_cld(cld);
668 }
669 }
670 }
671
672 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
673 roots_cld_do(cl, NULL);
674 }
675
676 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
677 if (ClassUnloading) {
678 keep_alive_cld_do(cl);
679 } else {
680 cld_do(cl);
681 }
682 }
683
684 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
685 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
686 cld->classes_do(klass_closure);
687 }
688 }
689
690 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
691 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
692 cld->classes_do(f);
693 }
694 }
695
696 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
697 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
698 cld->methods_do(f);
699 }
700 }
701
702 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
703 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
704 cld->loaded_classes_do(klass_closure);
705 }
706 }
707
708 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
709 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
710 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
711 cld->classes_do(f);
712 }
713 }
714
715 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
716 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
717
718 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
719
720 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
721 ClassLoaderData* curr = _head;
722 while (curr != _saved_head) {
723 if (!curr->claimed()) {
724 array->push(curr);
725
726 if (TraceClassLoaderData) {
727 tty->print("[ClassLoaderData] found new CLD: ");
728 curr->print_value_on(tty);
729 tty->cr();
730 }
731 }
732
733 curr = curr->_next;
734 }
735
736 return array;
737 }
738
739 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
740 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
741 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
742 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
743 return true;
744 }
745 }
746 return false;
747 }
748
749 #ifndef PRODUCT
750 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
751 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
752 if (loader_data == data) {
753 return true;
754 }
755 }
756
757 return false;
758 }
759 #endif // PRODUCT
760
761
762 // Move class loader data from main list to the unloaded list for unloading
763 // and deallocation later.
764 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure) {
765 ClassLoaderData* data = _head;
766 ClassLoaderData* prev = NULL;
767 bool seen_dead_loader = false;
768 // mark metadata seen on the stack and code cache so we can delete
769 // unneeded entries.
770 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
771 MetadataOnStackMark md_on_stack;
772 while (data != NULL) {
773 if (data->is_alive(is_alive_closure)) {
774 if (has_redefined_a_class) {
775 data->classes_do(InstanceKlass::purge_previous_versions);
776 }
777 data->free_deallocate_list();
778 prev = data;
779 data = data->next();
780 continue;
781 }
782 seen_dead_loader = true;
783 ClassLoaderData* dead = data;
784 dead->unload();
785 data = data->next();
786 // Remove from loader list.
787 // This class loader data will no longer be found
788 // in the ClassLoaderDataGraph.
789 if (prev != NULL) {
790 prev->set_next(data);
791 } else {
792 assert(dead == _head, "sanity check");
793 _head = data;
794 }
795 dead->set_next(_unloading);
796 _unloading = dead;
797 }
798
799 if (seen_dead_loader) {
800 post_class_unload_events();
801 }
802
803 return seen_dead_loader;
804 }
805
806 void ClassLoaderDataGraph::purge() {
807 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
808 ClassLoaderData* list = _unloading;
809 _unloading = NULL;
810 ClassLoaderData* next = list;
811 while (next != NULL) {
812 ClassLoaderData* purge_me = next;
813 next = purge_me->next();
814 delete purge_me;
815 }
816 Metaspace::purge();
817 }
818
819 void ClassLoaderDataGraph::post_class_unload_events(void) {
820 #if INCLUDE_TRACE
821 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
822 if (Tracing::enabled()) {
823 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
824 assert(_unloading != NULL, "need class loader data unload list!");
825 _class_unload_time = Ticks::now();
826 classes_unloading_do(&class_unload_event);
827 }
828 Tracing::on_unloading_classes();
829 }
830 #endif
831 }
832
833 // CDS support
834
835 // Global metaspaces for writing information to the shared archive. When
836 // application CDS is supported, we may need one per metaspace, so this
837 // sort of looks like it.
838 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
839 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
840 static bool _shared_metaspaces_initialized = false;
841
842 // Initialize shared metaspaces (change to call from somewhere not lazily)
843 void ClassLoaderData::initialize_shared_metaspaces() {
844 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
845 assert(this == ClassLoaderData::the_null_class_loader_data(),
846 "only supported for null loader data for now");
847 assert (!_shared_metaspaces_initialized, "only initialize once");
848 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
849 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
850 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
851 _shared_metaspaces_initialized = true;
852 }
853
854 Metaspace* ClassLoaderData::ro_metaspace() {
855 assert(_ro_metaspace != NULL, "should already be initialized");
856 return _ro_metaspace;
857 }
858
859 Metaspace* ClassLoaderData::rw_metaspace() {
860 assert(_rw_metaspace != NULL, "should already be initialized");
861 return _rw_metaspace;
862 }
863
864 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
865 : _next_klass(NULL) {
866 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
867 Klass* klass = NULL;
868
869 // Find the first klass in the CLDG.
870 while (cld != NULL) {
871 klass = cld->_klasses;
872 if (klass != NULL) {
873 _next_klass = klass;
874 return;
875 }
876 cld = cld->next();
877 }
878 }
879
880 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
881 Klass* next = klass->next_link();
882 if (next != NULL) {
883 return next;
884 }
885
886 // No more klasses in the current CLD. Time to find a new CLD.
887 ClassLoaderData* cld = klass->class_loader_data();
888 while (next == NULL) {
889 cld = cld->next();
890 if (cld == NULL) {
891 break;
892 }
893 next = cld->_klasses;
894 }
895
896 return next;
897 }
898
899 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
900 Klass* head = (Klass*)_next_klass;
901
902 while (head != NULL) {
903 Klass* next = next_klass_in_cldg(head);
904
905 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
906
907 if (old_head == head) {
908 return head; // Won the CAS.
909 }
910
911 head = old_head;
912 }
913
914 // Nothing more for the iterator to hand out.
915 assert(head == NULL, err_msg("head is " PTR_FORMAT ", expected not null:", p2i(head)));
916 return NULL;
917 }
918
919 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
920 _data = ClassLoaderDataGraph::_head;
921 }
922
923 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
924
925 #ifndef PRODUCT
926 // callable from debugger
927 extern "C" int print_loader_data_graph() {
928 ClassLoaderDataGraph::dump_on(tty);
929 return 0;
930 }
931
932 void ClassLoaderDataGraph::verify() {
933 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
934 data->verify();
935 }
936 }
937
938 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
939 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
940 data->dump(out);
941 }
942 MetaspaceAux::dump(out);
943 }
944 #endif // PRODUCT
945
946 void ClassLoaderData::print_value_on(outputStream* out) const {
947 if (class_loader() == NULL) {
948 out->print("NULL class_loader");
949 } else {
950 out->print("class loader " INTPTR_FORMAT, p2i(this));
951 class_loader()->print_value_on(out);
952 }
953 }
954
955 #if INCLUDE_TRACE
956
957 Ticks ClassLoaderDataGraph::_class_unload_time;
958
959 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
960
961 // post class unload event
962 EventClassUnload event(UNTIMED);
963 event.set_endtime(_class_unload_time);
964 event.set_unloadedClass(k);
965 oop defining_class_loader = k->class_loader();
966 event.set_definingClassLoader(defining_class_loader != NULL ?
967 defining_class_loader->klass() : (Klass*)NULL);
968 event.commit();
969 }
970
971 #endif /* INCLUDE_TRACE */