1 /*
2 * Copyright (c) 2012, 2013, 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/ostream.hpp"
66
67 #if INCLUDE_TRACE
68 #include "trace/tracing.hpp"
69 #endif
70
71
72 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
73
74 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
75 _class_loader(h_class_loader()),
76 _is_anonymous(is_anonymous), _keep_alive(is_anonymous), // initially
77 _metaspace(NULL), _unloading(false), _klasses(NULL),
78 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
79 _next(NULL), _dependencies(dependencies),
80 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {
81 // empty
82 }
83
84 void ClassLoaderData::init_dependencies(TRAPS) {
85 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
86 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
87 _dependencies.init(CHECK);
88 }
89
90 void ClassLoaderData::Dependencies::init(TRAPS) {
91 // Create empty dependencies array to add to. CMS requires this to be
92 // an oop so that it can track additions via card marks. We think.
93 _list_head = oopFactory::new_objectArray(2, CHECK);
94 }
95
96 bool ClassLoaderData::claim() {
97 if (_claimed == 1) {
98 return false;
99 }
100
101 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
102 }
103
104 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
105 if (must_claim && !claim()) {
106 return;
107 }
108
109 f->do_oop(&_class_loader);
110 _dependencies.oops_do(f);
111 _handles->oops_do(f);
112 if (klass_closure != NULL) {
113 classes_do(klass_closure);
114 }
115 }
116
117 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
118 f->do_oop((oop*)&_list_head);
119 }
120
121 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
122 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
123 klass_closure->do_klass(k);
124 assert(k != k->next_link(), "no loops!");
125 }
126 }
127
128 void ClassLoaderData::classes_do(void f(Klass * const)) {
129 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
130 f(k);
131 }
132 }
133
134 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
135 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
136 if (k->oop_is_instance()) {
137 f(InstanceKlass::cast(k));
138 }
139 assert(k != k->next_link(), "no loops!");
140 }
141 }
142
143 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
144 ClassLoaderData * const from_cld = this;
145 ClassLoaderData * const to_cld = k->class_loader_data();
146
147 // Dependency to the null class loader data doesn't need to be recorded
148 // because the null class loader data never goes away.
149 if (to_cld->is_the_null_class_loader_data()) {
150 return;
151 }
152
153 oop to;
154 if (to_cld->is_anonymous()) {
155 // Anonymous class dependencies are through the mirror.
156 to = k->java_mirror();
157 } else {
158 to = to_cld->class_loader();
159
160 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
161 // we still have to add it. The class_loader won't keep from_cld alive.
162 if (!from_cld->is_anonymous()) {
163 // Check that this dependency isn't from the same or parent class_loader
164 oop from = from_cld->class_loader();
165
166 oop curr = from;
167 while (curr != NULL) {
168 if (curr == to) {
169 return; // this class loader is in the parent list, no need to add it.
170 }
171 curr = java_lang_ClassLoader::parent(curr);
172 }
173 }
174 }
175
176 // It's a dependency we won't find through GC, add it. This is relatively rare
177 // Must handle over GC point.
178 Handle dependency(THREAD, to);
179 from_cld->_dependencies.add(dependency, CHECK);
180 }
181
182
183 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
184 // Check first if this dependency is already in the list.
185 // Save a pointer to the last to add to under the lock.
186 objArrayOop ok = _list_head;
187 objArrayOop last = NULL;
188 while (ok != NULL) {
189 last = ok;
190 if (ok->obj_at(0) == dependency()) {
191 // Don't need to add it
192 return;
193 }
194 ok = (objArrayOop)ok->obj_at(1);
195 }
196
197 // Must handle over GC points
198 assert (last != NULL, "dependencies should be initialized");
199 objArrayHandle last_handle(THREAD, last);
200
201 // Create a new dependency node with fields for (class_loader or mirror, next)
202 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
203 deps->obj_at_put(0, dependency());
204
205 // Must handle over GC points
206 objArrayHandle new_dependency(THREAD, deps);
207
208 // Add the dependency under lock
209 locked_add(last_handle, new_dependency, THREAD);
210 }
211
212 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
213 objArrayHandle new_dependency,
214 Thread* THREAD) {
215
216 // Have to lock and put the new dependency on the end of the dependency
217 // array so the card mark for CMS sees that this dependency is new.
218 // Can probably do this lock free with some effort.
219 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
220
221 oop loader_or_mirror = new_dependency->obj_at(0);
222
223 // Since the dependencies are only added, add to the end.
224 objArrayOop end = last_handle();
225 objArrayOop last = NULL;
226 while (end != NULL) {
227 last = end;
228 // check again if another thread added it to the end.
229 if (end->obj_at(0) == loader_or_mirror) {
230 // Don't need to add it
231 return;
232 }
233 end = (objArrayOop)end->obj_at(1);
234 }
235 assert (last != NULL, "dependencies should be initialized");
236 // fill in the first element with the oop in new_dependency.
237 if (last->obj_at(0) == NULL) {
238 last->obj_at_put(0, new_dependency->obj_at(0));
239 } else {
240 last->obj_at_put(1, new_dependency());
241 }
242 }
243
244 void ClassLoaderDataGraph::clear_claimed_marks() {
245 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
246 cld->clear_claimed();
247 }
248 }
249
250 void ClassLoaderData::add_class(Klass* k) {
251 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
252 Klass* old_value = _klasses;
253 k->set_next_link(old_value);
254 // link the new item into the list
255 _klasses = k;
256
257 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
258 ResourceMark rm;
259 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
260 PTR_FORMAT " loader: " PTR_FORMAT " %s",
261 k,
262 k->external_name(),
263 k->class_loader_data(),
264 k->class_loader(),
265 loader_name());
266 }
267 }
268
269 // This is called by InstanceKlass::deallocate_contents() to remove the
270 // scratch_class for redefine classes. We need a lock because there it may not
271 // be called at a safepoint if there's an error.
272 void ClassLoaderData::remove_class(Klass* scratch_class) {
273 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
274 Klass* prev = NULL;
275 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
276 if (k == scratch_class) {
277 if (prev == NULL) {
278 _klasses = k->next_link();
279 } else {
280 Klass* next = k->next_link();
281 prev->set_next_link(next);
282 }
283 return;
284 }
285 prev = k;
286 assert(k != k->next_link(), "no loops!");
287 }
288 ShouldNotReachHere(); // should have found this class!!
289 }
290
291 void ClassLoaderData::unload() {
292 _unloading = true;
293
294 // Tell serviceability tools these classes are unloading
295 classes_do(InstanceKlass::notify_unload_class);
296
297 if (TraceClassLoaderData) {
298 ResourceMark rm;
299 tty->print("[ClassLoaderData: unload loader data "PTR_FORMAT, this);
300 tty->print(" for instance "PTR_FORMAT" of %s", class_loader(),
301 loader_name());
302 if (is_anonymous()) {
303 tty->print(" for anonymous class "PTR_FORMAT " ", _klasses);
304 }
305 tty->print_cr("]");
306 }
307 }
308
309 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
310 bool alive =
311 is_anonymous() ?
312 is_alive_closure->do_object_b(_klasses->java_mirror()) :
313 class_loader() == NULL || is_alive_closure->do_object_b(class_loader());
314 assert(!alive || claimed(), "must be claimed");
315 return alive;
316 }
317
318
319 ClassLoaderData::~ClassLoaderData() {
320 // Release C heap structures for all the classes.
321 classes_do(InstanceKlass::release_C_heap_structures);
322
323 Metaspace *m = _metaspace;
324 if (m != NULL) {
325 _metaspace = NULL;
326 // release the metaspace
327 delete m;
328 // release the handles
329 if (_handles != NULL) {
330 JNIHandleBlock::release_block(_handles);
331 _handles = NULL;
332 }
333 }
334
335 // Clear all the JNI handles for methods
336 // These aren't deallocated and are going to look like a leak, but that's
337 // needed because we can't really get rid of jmethodIDs because we don't
338 // know when native code is going to stop using them. The spec says that
339 // they're "invalid" but existing programs likely rely on their being
340 // NULL after class unloading.
341 if (_jmethod_ids != NULL) {
342 Method::clear_jmethod_ids(this);
343 }
344 // Delete lock
345 delete _metaspace_lock;
346
347 // Delete free list
348 if (_deallocate_list != NULL) {
349 delete _deallocate_list;
350 }
351 }
352
353 /**
354 * Returns true if this class loader data is for the extension class loader.
355 */
356 bool ClassLoaderData::is_ext_class_loader_data() const {
357 return SystemDictionary::is_ext_class_loader(class_loader());
358 }
359
360 Metaspace* ClassLoaderData::metaspace_non_null() {
361 assert(!DumpSharedSpaces, "wrong metaspace!");
362 // If the metaspace has not been allocated, create a new one. Might want
363 // to create smaller arena for Reflection class loaders also.
364 // The reason for the delayed allocation is because some class loaders are
365 // simply for delegating with no metadata of their own.
366 if (_metaspace == NULL) {
367 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
368 // Check again if metaspace has been allocated while we were getting this lock.
369 if (_metaspace != NULL) {
370 return _metaspace;
371 }
372 if (this == the_null_class_loader_data()) {
373 assert (class_loader() == NULL, "Must be");
374 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
375 } else if (is_anonymous()) {
376 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
377 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
378 }
379 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
380 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
381 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
382 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
383 }
384 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
385 } else {
386 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
387 }
388 }
389 return _metaspace;
390 }
391
392 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
393 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
394
395 jobject ClassLoaderData::add_handle(Handle h) {
396 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
397 if (handles() == NULL) {
398 set_handles(JNIHandleBlock::allocate_block());
399 }
400 return handles()->allocate_handle(h());
401 }
402
403 // Add this metadata pointer to be freed when it's safe. This is only during
404 // class unloading because Handles might point to this metadata field.
405 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
406 // Metadata in shared region isn't deleted.
407 if (!m->is_shared()) {
408 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
409 if (_deallocate_list == NULL) {
410 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
411 }
412 _deallocate_list->append_if_missing(m);
413 }
414 }
415
416 // Deallocate free metadata on the free list. How useful the PermGen was!
417 void ClassLoaderData::free_deallocate_list() {
418 // Don't need lock, at safepoint
419 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
420 if (_deallocate_list == NULL) {
421 return;
422 }
423 // Go backwards because this removes entries that are freed.
424 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
425 Metadata* m = _deallocate_list->at(i);
426 if (!m->on_stack()) {
427 _deallocate_list->remove_at(i);
428 // There are only three types of metadata that we deallocate directly.
429 // Cast them so they can be used by the template function.
430 if (m->is_method()) {
431 MetadataFactory::free_metadata(this, (Method*)m);
432 } else if (m->is_constantPool()) {
433 MetadataFactory::free_metadata(this, (ConstantPool*)m);
434 } else if (m->is_klass()) {
435 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
436 } else {
437 ShouldNotReachHere();
438 }
439 }
440 }
441 }
442
443 // These anonymous class loaders are to contain classes used for JSR292
444 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
445 // Add a new class loader data to the graph.
446 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL);
447 }
448
449 const char* ClassLoaderData::loader_name() {
450 // Handles null class loader
451 return SystemDictionary::loader_name(class_loader());
452 }
453
454 #ifndef PRODUCT
455 // Define to dump klasses
456 #undef CLD_DUMP_KLASSES
457
458 void ClassLoaderData::dump(outputStream * const out) {
459 ResourceMark rm;
460 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {",
461 this, class_loader(),
462 class_loader() != NULL ? class_loader()->klass() : NULL, loader_name());
463 if (claimed()) out->print(" claimed ");
464 if (is_unloading()) out->print(" unloading ");
465 out->print(" handles " INTPTR_FORMAT, handles());
466 out->cr();
467 if (metaspace_or_null() != NULL) {
468 out->print_cr("metaspace: " PTR_FORMAT, metaspace_or_null());
469 metaspace_or_null()->dump(out);
470 } else {
471 out->print_cr("metaspace: NULL");
472 }
473
474 #ifdef CLD_DUMP_KLASSES
475 if (Verbose) {
476 ResourceMark rm;
477 Klass* k = _klasses;
478 while (k != NULL) {
479 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
480 k->has_modified_oops(), k->has_accumulated_modified_oops());
481 assert(k != k->next_link(), "no loops!");
482 k = k->next_link();
483 }
484 }
485 #endif // CLD_DUMP_KLASSES
486 #undef CLD_DUMP_KLASSES
487 if (_jmethod_ids != NULL) {
488 Method::print_jmethod_ids(this, out);
489 }
490 out->print_cr("}");
491 }
492 #endif // PRODUCT
493
494 void ClassLoaderData::verify() {
495 oop cl = class_loader();
496
497 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
498 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
499
500 // Verify the integrity of the allocated space.
501 if (metaspace_or_null() != NULL) {
502 metaspace_or_null()->verify();
503 }
504
505 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
506 guarantee(k->class_loader_data() == this, "Must be the same");
507 k->verify();
508 assert(k != k->next_link(), "no loops!");
509 }
510 }
511
512
513 // GC root of class loader data created.
514 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
515 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
516 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
517
518 // Add a new class loader data node to the list. Assign the newly created
519 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
520 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
521 // We need to allocate all the oops for the ClassLoaderData before allocating the
522 // actual ClassLoaderData object.
523 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
524
525 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
526 // ClassLoaderData in the graph since the CLD
527 // contains unhandled oops
528
529 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
530
531
532 if (!is_anonymous) {
533 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
534 // First, Atomically set it
535 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
536 if (old != NULL) {
537 delete cld;
538 // Returns the data.
539 return old;
540 }
541 }
542
543 // We won the race, and therefore the task of adding the data to the list of
544 // class loader data
545 ClassLoaderData** list_head = &_head;
546 ClassLoaderData* next = _head;
547
548 do {
549 cld->set_next(next);
550 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
551 if (exchanged == next) {
552 if (TraceClassLoaderData) {
553 ResourceMark rm;
554 tty->print("[ClassLoaderData: ");
555 tty->print("create class loader data "PTR_FORMAT, cld);
556 tty->print(" for instance "PTR_FORMAT" of %s", cld->class_loader(),
557 cld->loader_name());
558 tty->print_cr("]");
559 }
560 return cld;
561 }
562 next = exchanged;
563 } while (true);
564
565 }
566
567 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
568 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
569 cld->oops_do(f, klass_closure, must_claim);
570 }
571 }
572
573 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
574 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
575 if (cld->keep_alive()) {
576 cld->oops_do(f, klass_closure, must_claim);
577 }
578 }
579 }
580
581 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
582 if (ClassUnloading) {
583 ClassLoaderData::the_null_class_loader_data()->oops_do(f, klass_closure, must_claim);
584 // keep any special CLDs alive.
585 ClassLoaderDataGraph::keep_alive_oops_do(f, klass_closure, must_claim);
586 } else {
587 ClassLoaderDataGraph::oops_do(f, klass_closure, must_claim);
588 }
589 }
590
591 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
592 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
593 cld->classes_do(klass_closure);
594 }
595 }
596
597 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
598 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
599 cld->classes_do(f);
600 }
601 }
602
603 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
604 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
605 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
606 cld->classes_do(f);
607 }
608 }
609
610 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
611 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
612
613 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
614
615 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
616 ClassLoaderData* curr = _head;
617 while (curr != _saved_head) {
618 if (!curr->claimed()) {
619 array->push(curr);
620
621 if (TraceClassLoaderData) {
622 tty->print("[ClassLoaderData] found new CLD: ");
623 curr->print_value_on(tty);
624 tty->cr();
625 }
626 }
627
628 curr = curr->_next;
629 }
630
631 return array;
632 }
633
634 #ifndef PRODUCT
635 // for debugging and hsfind(x)
636 bool ClassLoaderDataGraph::contains(address x) {
637 // I think we need the _metaspace_lock taken here because the class loader
638 // data graph could be changing while we are walking it (new entries added,
639 // new entries being unloaded, etc).
640 if (DumpSharedSpaces) {
641 // There are only two metaspaces to worry about.
642 ClassLoaderData* ncld = ClassLoaderData::the_null_class_loader_data();
643 return (ncld->ro_metaspace()->contains(x) || ncld->rw_metaspace()->contains(x));
644 }
645
646 if (UseSharedSpaces && MetaspaceShared::is_in_shared_space(x)) {
647 return true;
648 }
649
650 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
651 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
652 return true;
653 }
654 }
655
656 // Could also be on an unloading list which is okay, ie. still allocated
657 // for a little while.
658 for (ClassLoaderData* ucld = _unloading; ucld != NULL; ucld = ucld->next()) {
659 if (ucld->metaspace_or_null() != NULL && ucld->metaspace_or_null()->contains(x)) {
660 return true;
661 }
662 }
663 return false;
664 }
665
666 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
667 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
668 if (loader_data == data) {
669 return true;
670 }
671 }
672
673 return false;
674 }
675 #endif // PRODUCT
676
677
678 // Move class loader data from main list to the unloaded list for unloading
679 // and deallocation later.
680 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure) {
681 ClassLoaderData* data = _head;
682 ClassLoaderData* prev = NULL;
683 bool seen_dead_loader = false;
684 // mark metadata seen on the stack and code cache so we can delete
685 // unneeded entries.
686 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
687 MetadataOnStackMark md_on_stack;
688 while (data != NULL) {
689 if (data->keep_alive() || data->is_alive(is_alive_closure)) {
690 if (has_redefined_a_class) {
691 data->classes_do(InstanceKlass::purge_previous_versions);
692 }
693 data->free_deallocate_list();
694 prev = data;
695 data = data->next();
696 continue;
697 }
698 seen_dead_loader = true;
699 ClassLoaderData* dead = data;
700 dead->unload();
701 data = data->next();
702 // Remove from loader list.
703 // This class loader data will no longer be found
704 // in the ClassLoaderDataGraph.
705 if (prev != NULL) {
706 prev->set_next(data);
707 } else {
708 assert(dead == _head, "sanity check");
709 _head = data;
710 }
711 dead->set_next(_unloading);
712 _unloading = dead;
713 }
714
715 if (seen_dead_loader) {
716 post_class_unload_events();
717 }
718
719 return seen_dead_loader;
720 }
721
722 void ClassLoaderDataGraph::purge() {
723 ClassLoaderData* list = _unloading;
724 _unloading = NULL;
725 ClassLoaderData* next = list;
726 while (next != NULL) {
727 ClassLoaderData* purge_me = next;
728 next = purge_me->next();
729 delete purge_me;
730 }
731 Metaspace::purge();
732 }
733
734 void ClassLoaderDataGraph::post_class_unload_events(void) {
735 #if INCLUDE_TRACE
736 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
737 if (Tracing::enabled()) {
738 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
739 assert(_unloading != NULL, "need class loader data unload list!");
740 _class_unload_time = Tracing::time();
741 classes_unloading_do(&class_unload_event);
742 }
743 Tracing::on_unloading_classes();
744 }
745 #endif
746 }
747
748 // CDS support
749
750 // Global metaspaces for writing information to the shared archive. When
751 // application CDS is supported, we may need one per metaspace, so this
752 // sort of looks like it.
753 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
754 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
755 static bool _shared_metaspaces_initialized = false;
756
757 // Initialize shared metaspaces (change to call from somewhere not lazily)
758 void ClassLoaderData::initialize_shared_metaspaces() {
759 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
760 assert(this == ClassLoaderData::the_null_class_loader_data(),
761 "only supported for null loader data for now");
762 assert (!_shared_metaspaces_initialized, "only initialize once");
763 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
764 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
765 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
766 _shared_metaspaces_initialized = true;
767 }
768
769 Metaspace* ClassLoaderData::ro_metaspace() {
770 assert(_ro_metaspace != NULL, "should already be initialized");
771 return _ro_metaspace;
772 }
773
774 Metaspace* ClassLoaderData::rw_metaspace() {
775 assert(_rw_metaspace != NULL, "should already be initialized");
776 return _rw_metaspace;
777 }
778
779
780 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
781 _data = ClassLoaderDataGraph::_head;
782 }
783
784 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
785
786 #ifndef PRODUCT
787 // callable from debugger
788 extern "C" int print_loader_data_graph() {
789 ClassLoaderDataGraph::dump_on(tty);
790 return 0;
791 }
792
793 void ClassLoaderDataGraph::verify() {
794 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
795 data->verify();
796 }
797 }
798
799 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
800 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
801 data->dump(out);
802 }
803 MetaspaceAux::dump(out);
804 }
805 #endif // PRODUCT
806
807 void ClassLoaderData::print_value_on(outputStream* out) const {
808 if (class_loader() == NULL) {
809 out->print("NULL class_loader");
810 } else {
811 out->print("class loader "PTR_FORMAT, this);
812 class_loader()->print_value_on(out);
813 }
814 }
815
816 #if INCLUDE_TRACE
817
818 TracingTime ClassLoaderDataGraph::_class_unload_time;
819
820 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
821
822 // post class unload event
823 EventClassUnload event(UNTIMED);
824 event.set_endtime(_class_unload_time);
825 event.set_unloadedClass(k);
826 oop defining_class_loader = k->class_loader();
827 event.set_definingClassLoader(defining_class_loader != NULL ?
828 defining_class_loader->klass() : (Klass*)NULL);
829 event.commit();
830 }
831
832 #endif /* INCLUDE_TRACE */