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