1 /*
2 * Copyright (c) 2012, 2015, 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 "gc/shared/gcLocker.hpp"
57 #include "memory/metadataFactory.hpp"
58 #include "memory/metaspaceShared.hpp"
59 #include "memory/oopFactory.hpp"
60 #include "oops/objArrayOop.inline.hpp"
61 #include "oops/oop.inline.hpp"
62 #include "runtime/atomic.inline.hpp"
63 #include "runtime/jniHandles.hpp"
64 #include "runtime/mutex.hpp"
65 #include "runtime/safepoint.hpp"
66 #include "runtime/synchronizer.hpp"
67 #include "utilities/growableArray.hpp"
68 #include "utilities/macros.hpp"
69 #include "utilities/ostream.hpp"
70 #if INCLUDE_TRACE
71 #include "trace/tracing.hpp"
72 #endif
73
74 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
75
76 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
77 _class_loader(h_class_loader()),
78 _is_anonymous(is_anonymous),
79 // An anonymous class loader data doesn't have anything to keep
80 // it from being unloaded during parsing of the anonymous class.
81 // The null-class-loader should always be kept alive.
82 _keep_alive(is_anonymous || h_class_loader.is_null()),
83 _metaspace(NULL), _unloading(false), _klasses(NULL),
84 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
85 _next(NULL), _dependencies(dependencies),
86 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
87 Monitor::_safepoint_check_never)) {
88 // empty
89 }
90
91 void ClassLoaderData::init_dependencies(TRAPS) {
92 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
93 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
94 _dependencies.init(CHECK);
95 }
96
97 void ClassLoaderData::Dependencies::init(TRAPS) {
98 // Create empty dependencies array to add to. CMS requires this to be
99 // an oop so that it can track additions via card marks. We think.
100 _list_head = oopFactory::new_objectArray(2, CHECK);
101 }
102
103 bool ClassLoaderData::claim() {
104 if (_claimed == 1) {
105 return false;
106 }
107
108 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
109 }
110
111 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
112 if (must_claim && !claim()) {
113 return;
114 }
115
116 f->do_oop(&_class_loader);
117 _dependencies.oops_do(f);
118 _handles->oops_do(f);
119 if (klass_closure != NULL) {
120 classes_do(klass_closure);
121 }
122 }
123
124 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
125 f->do_oop((oop*)&_list_head);
126 }
127
128 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
129 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
130 klass_closure->do_klass(k);
131 assert(k != k->next_link(), "no loops!");
132 }
133 }
134
135 void ClassLoaderData::classes_do(void f(Klass * const)) {
136 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
137 f(k);
138 }
139 }
140
141 void ClassLoaderData::methods_do(void f(Method*)) {
142 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
143 if (k->oop_is_instance()) {
144 InstanceKlass::cast(k)->methods_do(f);
145 }
146 }
147 }
148
149 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
150 // Lock to avoid classes being modified/added/removed during iteration
151 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
152 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
153 // Do not filter ArrayKlass oops here...
154 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) {
155 klass_closure->do_klass(k);
156 }
157 }
158 }
159
160 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
161 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
162 if (k->oop_is_instance()) {
163 f(InstanceKlass::cast(k));
164 }
165 assert(k != k->next_link(), "no loops!");
166 }
167 }
168
169 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
170 ClassLoaderData * const from_cld = this;
171 ClassLoaderData * const to_cld = k->class_loader_data();
172
173 // Dependency to the null class loader data doesn't need to be recorded
174 // because the null class loader data never goes away.
175 if (to_cld->is_the_null_class_loader_data()) {
176 return;
177 }
178
179 oop to;
180 if (to_cld->is_anonymous()) {
181 // Anonymous class dependencies are through the mirror.
182 to = k->java_mirror();
183 } else {
184 to = to_cld->class_loader();
185
186 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
187 // we still have to add it. The class_loader won't keep from_cld alive.
188 if (!from_cld->is_anonymous()) {
189 // Check that this dependency isn't from the same or parent class_loader
190 oop from = from_cld->class_loader();
191
192 oop curr = from;
193 while (curr != NULL) {
194 if (curr == to) {
195 return; // this class loader is in the parent list, no need to add it.
196 }
197 curr = java_lang_ClassLoader::parent(curr);
198 }
199 }
200 }
201
202 // It's a dependency we won't find through GC, add it. This is relatively rare
203 // Must handle over GC point.
204 Handle dependency(THREAD, to);
205 from_cld->_dependencies.add(dependency, CHECK);
206 }
207
208
209 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
210 // Check first if this dependency is already in the list.
211 // Save a pointer to the last to add to under the lock.
212 objArrayOop ok = _list_head;
213 objArrayOop last = NULL;
214 while (ok != NULL) {
215 last = ok;
216 if (ok->obj_at(0) == dependency()) {
217 // Don't need to add it
218 return;
219 }
220 ok = (objArrayOop)ok->obj_at(1);
221 }
222
223 // Must handle over GC points
224 assert (last != NULL, "dependencies should be initialized");
225 objArrayHandle last_handle(THREAD, last);
226
227 // Create a new dependency node with fields for (class_loader or mirror, next)
228 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
229 deps->obj_at_put(0, dependency());
230
231 // Must handle over GC points
232 objArrayHandle new_dependency(THREAD, deps);
233
234 // Add the dependency under lock
235 locked_add(last_handle, new_dependency, THREAD);
236 }
237
238 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
239 objArrayHandle new_dependency,
240 Thread* THREAD) {
241
242 // Have to lock and put the new dependency on the end of the dependency
243 // array so the card mark for CMS sees that this dependency is new.
244 // Can probably do this lock free with some effort.
245 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
246
247 oop loader_or_mirror = new_dependency->obj_at(0);
248
249 // Since the dependencies are only added, add to the end.
250 objArrayOop end = last_handle();
251 objArrayOop last = NULL;
252 while (end != NULL) {
253 last = end;
254 // check again if another thread added it to the end.
255 if (end->obj_at(0) == loader_or_mirror) {
256 // Don't need to add it
257 return;
258 }
259 end = (objArrayOop)end->obj_at(1);
260 }
261 assert (last != NULL, "dependencies should be initialized");
262 // fill in the first element with the oop in new_dependency.
263 if (last->obj_at(0) == NULL) {
264 last->obj_at_put(0, new_dependency->obj_at(0));
265 } else {
266 last->obj_at_put(1, new_dependency());
267 }
268 }
269
270 void ClassLoaderDataGraph::clear_claimed_marks() {
271 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
272 cld->clear_claimed();
273 }
274 }
275
276 void ClassLoaderData::add_class(Klass* k) {
277 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
278 Klass* old_value = _klasses;
279 k->set_next_link(old_value);
280 // Make sure linked class is stable, since the class list is walked without a lock
281 OrderAccess::storestore();
282 // link the new item into the list
283 _klasses = k;
284
285 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
286 ResourceMark rm;
287 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
288 PTR_FORMAT " loader: " PTR_FORMAT " %s",
289 p2i(k),
290 k->external_name(),
291 p2i(k->class_loader_data()),
292 p2i((void *)k->class_loader()),
293 loader_name());
294 }
295 }
296
297 // This is called by InstanceKlass::deallocate_contents() to remove the
298 // scratch_class for redefine classes. We need a lock because there it may not
299 // be called at a safepoint if there's an error.
300 void ClassLoaderData::remove_class(Klass* scratch_class) {
301 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
302 Klass* prev = NULL;
303 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
304 if (k == scratch_class) {
305 if (prev == NULL) {
306 _klasses = k->next_link();
307 } else {
308 Klass* next = k->next_link();
309 prev->set_next_link(next);
310 }
311 return;
312 }
313 prev = k;
314 assert(k != k->next_link(), "no loops!");
315 }
316 ShouldNotReachHere(); // should have found this class!!
317 }
318
319 void ClassLoaderData::unload() {
320 _unloading = true;
321
322 // Tell serviceability tools these classes are unloading
323 classes_do(InstanceKlass::notify_unload_class);
324
325 if (TraceClassLoaderData) {
326 ResourceMark rm;
327 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this));
328 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
329 loader_name());
330 if (is_anonymous()) {
331 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
332 }
333 tty->print_cr("]");
334 }
335 }
336
337 oop ClassLoaderData::keep_alive_object() const {
338 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
339 return is_anonymous() ? _klasses->java_mirror() : class_loader();
340 }
341
342 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
343 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
344 || is_alive_closure->do_object_b(keep_alive_object());
345
346 return alive;
347 }
348
349
350 ClassLoaderData::~ClassLoaderData() {
351 // Release C heap structures for all the classes.
352 classes_do(InstanceKlass::release_C_heap_structures);
353
354 Metaspace *m = _metaspace;
355 if (m != NULL) {
356 _metaspace = NULL;
357 // release the metaspace
358 delete m;
359 // release the handles
360 if (_handles != NULL) {
361 JNIHandleBlock::release_block(_handles);
362 _handles = NULL;
363 }
364 }
365
366 // Clear all the JNI handles for methods
367 // These aren't deallocated and are going to look like a leak, but that's
368 // needed because we can't really get rid of jmethodIDs because we don't
369 // know when native code is going to stop using them. The spec says that
370 // they're "invalid" but existing programs likely rely on their being
371 // NULL after class unloading.
372 if (_jmethod_ids != NULL) {
373 Method::clear_jmethod_ids(this);
374 }
375 // Delete lock
376 delete _metaspace_lock;
377
378 // Delete free list
379 if (_deallocate_list != NULL) {
380 delete _deallocate_list;
381 }
382 }
383
384 /**
385 * Returns true if this class loader data is for the extension class loader.
386 */
387 bool ClassLoaderData::is_ext_class_loader_data() const {
388 return SystemDictionary::is_ext_class_loader(class_loader());
389 }
390
391 Metaspace* ClassLoaderData::metaspace_non_null() {
392 assert(!DumpSharedSpaces, "wrong metaspace!");
393 // If the metaspace has not been allocated, create a new one. Might want
394 // to create smaller arena for Reflection class loaders also.
395 // The reason for the delayed allocation is because some class loaders are
396 // simply for delegating with no metadata of their own.
397 if (_metaspace == NULL) {
398 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
399 // Check again if metaspace has been allocated while we were getting this lock.
400 if (_metaspace != NULL) {
401 return _metaspace;
402 }
403 if (this == the_null_class_loader_data()) {
404 assert (class_loader() == NULL, "Must be");
405 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
406 } else if (is_anonymous()) {
407 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
408 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
409 }
410 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
411 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
412 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
413 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
414 }
415 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
416 } else {
417 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
418 }
419 }
420 return _metaspace;
421 }
422
423 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
424 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
425
426 jobject ClassLoaderData::add_handle(Handle h) {
427 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
428 if (handles() == NULL) {
429 set_handles(JNIHandleBlock::allocate_block());
430 }
431 return handles()->allocate_handle(h());
432 }
433
434 // Add this metadata pointer to be freed when it's safe. This is only during
435 // class unloading because Handles might point to this metadata field.
436 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
437 // Metadata in shared region isn't deleted.
438 if (!m->is_shared()) {
439 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
440 if (_deallocate_list == NULL) {
441 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
442 }
443 _deallocate_list->append_if_missing(m);
444 }
445 }
446
447 // Deallocate free metadata on the free list. How useful the PermGen was!
448 void ClassLoaderData::free_deallocate_list() {
449 // Don't need lock, at safepoint
450 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
451 if (_deallocate_list == NULL) {
452 return;
453 }
454 // Go backwards because this removes entries that are freed.
455 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
456 Metadata* m = _deallocate_list->at(i);
457 if (!m->on_stack()) {
458 _deallocate_list->remove_at(i);
459 // There are only three types of metadata that we deallocate directly.
460 // Cast them so they can be used by the template function.
461 if (m->is_method()) {
462 MetadataFactory::free_metadata(this, (Method*)m);
463 } else if (m->is_constantPool()) {
464 MetadataFactory::free_metadata(this, (ConstantPool*)m);
465 } else if (m->is_klass()) {
466 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
467 } else {
468 ShouldNotReachHere();
469 }
470 } else {
471 // Metadata is alive.
472 // If scratch_class is on stack then it shouldn't be on this list!
473 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
474 "scratch classes on this list should be dead");
475 // Also should assert that other metadata on the list was found in handles.
476 }
477 }
478 }
479
480 // These anonymous class loaders are to contain classes used for JSR292
481 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
482 // Add a new class loader data to the graph.
483 return ClassLoaderDataGraph::add(loader, true, THREAD);
484 }
485
486 const char* ClassLoaderData::loader_name() {
487 // Handles null class loader
488 return SystemDictionary::loader_name(class_loader());
489 }
490
491 #ifndef PRODUCT
492 // Define to dump klasses
493 #undef CLD_DUMP_KLASSES
494
495 void ClassLoaderData::dump(outputStream * const out) {
496 ResourceMark rm;
497 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
498 p2i(this), p2i((void *)class_loader()),
499 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
500 if (claimed()) out->print(" claimed ");
501 if (is_unloading()) out->print(" unloading ");
502 out->print(" handles " INTPTR_FORMAT, p2i(handles()));
503 out->cr();
504 if (metaspace_or_null() != NULL) {
505 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
506 metaspace_or_null()->dump(out);
507 } else {
508 out->print_cr("metaspace: NULL");
509 }
510
511 #ifdef CLD_DUMP_KLASSES
512 if (Verbose) {
513 ResourceMark rm;
514 Klass* k = _klasses;
515 while (k != NULL) {
516 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
517 k->has_modified_oops(), k->has_accumulated_modified_oops());
518 assert(k != k->next_link(), "no loops!");
519 k = k->next_link();
520 }
521 }
522 #endif // CLD_DUMP_KLASSES
523 #undef CLD_DUMP_KLASSES
524 if (_jmethod_ids != NULL) {
525 Method::print_jmethod_ids(this, out);
526 }
527 out->print_cr("}");
528 }
529 #endif // PRODUCT
530
531 void ClassLoaderData::verify() {
532 oop cl = class_loader();
533
534 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
535 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
536
537 // Verify the integrity of the allocated space.
538 if (metaspace_or_null() != NULL) {
539 metaspace_or_null()->verify();
540 }
541
542 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
543 guarantee(k->class_loader_data() == this, "Must be the same");
544 k->verify();
545 assert(k != k->next_link(), "no loops!");
546 }
547 }
548
549 bool ClassLoaderData::contains_klass(Klass* klass) {
550 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
551 if (k == klass) return true;
552 }
553 return false;
554 }
555
556
557 // GC root of class loader data created.
558 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
559 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
560 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
561 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
562
563 bool ClassLoaderDataGraph::_should_purge = false;
564 bool ClassLoaderDataGraph::_metaspace_oom = false;
565
566 // Add a new class loader data node to the list. Assign the newly created
567 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
568 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
569 // We need to allocate all the oops for the ClassLoaderData before allocating the
570 // actual ClassLoaderData object.
571 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
572
573 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
574 // ClassLoaderData in the graph since the CLD
575 // contains unhandled oops
576
577 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
578
579
580 if (!is_anonymous) {
581 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
582 // First, Atomically set it
583 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
584 if (old != NULL) {
585 delete cld;
586 // Returns the data.
587 return old;
588 }
589 }
590
591 // We won the race, and therefore the task of adding the data to the list of
592 // class loader data
593 ClassLoaderData** list_head = &_head;
594 ClassLoaderData* next = _head;
595
596 do {
597 cld->set_next(next);
598 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
599 if (exchanged == next) {
600 if (TraceClassLoaderData) {
601 ResourceMark rm;
602 tty->print("[ClassLoaderData: ");
603 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld));
604 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
605 cld->loader_name());
606 tty->print_cr("]");
607 }
608 return cld;
609 }
610 next = exchanged;
611 } while (true);
612
613 }
614
615 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
616 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
617 cld->oops_do(f, klass_closure, must_claim);
618 }
619 }
620
621 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
622 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
623 if (cld->keep_alive()) {
624 cld->oops_do(f, klass_closure, must_claim);
625 }
626 }
627 }
628
629 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
630 if (ClassUnloading) {
631 keep_alive_oops_do(f, klass_closure, must_claim);
632 } else {
633 oops_do(f, klass_closure, must_claim);
634 }
635 }
636
637 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
638 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
639 cl->do_cld(cld);
640 }
641 }
642
643 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
644 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
645 CLDClosure* closure = cld->keep_alive() ? strong : weak;
646 if (closure != NULL) {
647 closure->do_cld(cld);
648 }
649 }
650 }
651
652 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
653 roots_cld_do(cl, NULL);
654 }
655
656 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
657 if (ClassUnloading) {
658 keep_alive_cld_do(cl);
659 } else {
660 cld_do(cl);
661 }
662 }
663
664 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
665 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
666 cld->classes_do(klass_closure);
667 }
668 }
669
670 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
671 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
672 cld->classes_do(f);
673 }
674 }
675
676 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
677 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
678 cld->methods_do(f);
679 }
680 }
681
682 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
683 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
684 cld->loaded_classes_do(klass_closure);
685 }
686 }
687
688 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
689 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
690 // Only walk the head until any clds not purged from prior unloading
691 // (CMS doesn't purge right away).
692 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
693 cld->classes_do(f);
694 }
695 }
696
697 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
698 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
699
700 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
701
702 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
703 ClassLoaderData* curr = _head;
704 while (curr != _saved_head) {
705 if (!curr->claimed()) {
706 array->push(curr);
707
708 if (TraceClassLoaderData) {
709 tty->print("[ClassLoaderData] found new CLD: ");
710 curr->print_value_on(tty);
711 tty->cr();
712 }
713 }
714
715 curr = curr->_next;
716 }
717
718 return array;
719 }
720
721 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
722 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
723 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
724 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
725 return true;
726 }
727 }
728 return false;
729 }
730
731 #ifndef PRODUCT
732 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
733 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
734 if (loader_data == data) {
735 return true;
736 }
737 }
738
739 return false;
740 }
741 #endif // PRODUCT
742
743
744 // Move class loader data from main list to the unloaded list for unloading
745 // and deallocation later.
746 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
747 bool clean_previous_versions) {
748
749 ClassLoaderData* data = _head;
750 ClassLoaderData* prev = NULL;
751 bool seen_dead_loader = false;
752
753 // Mark metadata seen on the stack only so we can delete unneeded entries.
754 // Only walk all metadata, including the expensive code cache walk, for Full GC
755 // and only if class redefinition and if there's previous versions of
756 // Klasses to delete.
757 bool walk_all_metadata = clean_previous_versions &&
758 JvmtiExport::has_redefined_a_class() &&
759 InstanceKlass::has_previous_versions();
760 MetadataOnStackMark md_on_stack(walk_all_metadata);
761
762 // Save previous _unloading pointer for CMS which may add to unloading list before
763 // purging and we don't want to rewalk the previously unloaded class loader data.
764 _saved_unloading = _unloading;
765
766 data = _head;
767 while (data != NULL) {
768 if (data->is_alive(is_alive_closure)) {
769 // clean metaspace
770 if (walk_all_metadata) {
771 data->classes_do(InstanceKlass::purge_previous_versions);
772 }
773 data->free_deallocate_list();
774 prev = data;
775 data = data->next();
776 continue;
777 }
778 seen_dead_loader = true;
779 ClassLoaderData* dead = data;
780 dead->unload();
781 data = data->next();
782 // Remove from loader list.
783 // This class loader data will no longer be found
784 // in the ClassLoaderDataGraph.
785 if (prev != NULL) {
786 prev->set_next(data);
787 } else {
788 assert(dead == _head, "sanity check");
789 _head = data;
790 }
791 dead->set_next(_unloading);
792 _unloading = dead;
793 }
794
795 if (seen_dead_loader) {
796 post_class_unload_events();
797 }
798
799 return seen_dead_loader;
800 }
801
802 void ClassLoaderDataGraph::purge() {
803 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
804 ClassLoaderData* list = _unloading;
805 _unloading = NULL;
806 ClassLoaderData* next = list;
807 bool classes_unloaded = false;
808 while (next != NULL) {
809 ClassLoaderData* purge_me = next;
810 next = purge_me->next();
811 delete purge_me;
812 classes_unloaded = true;
813 }
814 if (classes_unloaded) {
815 Metaspace::purge();
816 set_metaspace_oom(false);
817 }
818 }
819
820 void ClassLoaderDataGraph::post_class_unload_events(void) {
821 #if INCLUDE_TRACE
822 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
823 if (Tracing::enabled()) {
824 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
825 assert(_unloading != NULL, "need class loader data unload list!");
826 _class_unload_time = Ticks::now();
827 classes_unloading_do(&class_unload_event);
828 }
829 Tracing::on_unloading_classes();
830 }
831 #endif
832 }
833
834 // CDS support
835
836 // Global metaspaces for writing information to the shared archive. When
837 // application CDS is supported, we may need one per metaspace, so this
838 // sort of looks like it.
839 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
840 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
841 static bool _shared_metaspaces_initialized = false;
842
843 // Initialize shared metaspaces (change to call from somewhere not lazily)
844 void ClassLoaderData::initialize_shared_metaspaces() {
845 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
846 assert(this == ClassLoaderData::the_null_class_loader_data(),
847 "only supported for null loader data for now");
848 assert (!_shared_metaspaces_initialized, "only initialize once");
849 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
850 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
851 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
852 _shared_metaspaces_initialized = true;
853 }
854
855 Metaspace* ClassLoaderData::ro_metaspace() {
856 assert(_ro_metaspace != NULL, "should already be initialized");
857 return _ro_metaspace;
858 }
859
860 Metaspace* ClassLoaderData::rw_metaspace() {
861 assert(_rw_metaspace != NULL, "should already be initialized");
862 return _rw_metaspace;
863 }
864
865 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
866 : _next_klass(NULL) {
867 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
868 Klass* klass = NULL;
869
870 // Find the first klass in the CLDG.
871 while (cld != NULL) {
872 klass = cld->_klasses;
873 if (klass != NULL) {
874 _next_klass = klass;
875 return;
876 }
877 cld = cld->next();
878 }
879 }
880
881 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
882 Klass* next = klass->next_link();
883 if (next != NULL) {
884 return next;
885 }
886
887 // No more klasses in the current CLD. Time to find a new CLD.
888 ClassLoaderData* cld = klass->class_loader_data();
889 while (next == NULL) {
890 cld = cld->next();
891 if (cld == NULL) {
892 break;
893 }
894 next = cld->_klasses;
895 }
896
897 return next;
898 }
899
900 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
901 Klass* head = _next_klass;
902
903 while (head != NULL) {
904 Klass* next = next_klass_in_cldg(head);
905
906 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
907
908 if (old_head == head) {
909 return head; // Won the CAS.
910 }
911
912 head = old_head;
913 }
914
915 // Nothing more for the iterator to hand out.
916 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
917 return NULL;
918 }
919
920 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
921 _data = ClassLoaderDataGraph::_head;
922 }
923
924 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
925
926 #ifndef PRODUCT
927 // callable from debugger
928 extern "C" int print_loader_data_graph() {
929 ClassLoaderDataGraph::dump_on(tty);
930 return 0;
931 }
932
933 void ClassLoaderDataGraph::verify() {
934 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
935 data->verify();
936 }
937 }
938
939 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
940 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
941 data->dump(out);
942 }
943 MetaspaceAux::dump(out);
944 }
945 #endif // PRODUCT
946
947 void ClassLoaderData::print_value_on(outputStream* out) const {
948 if (class_loader() == NULL) {
949 out->print("NULL class_loader");
950 } else {
951 out->print("class loader " INTPTR_FORMAT, p2i(this));
952 class_loader()->print_value_on(out);
953 }
954 }
955
956 #if INCLUDE_TRACE
957
958 Ticks ClassLoaderDataGraph::_class_unload_time;
959
960 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
961
962 // post class unload event
963 EventClassUnload event(UNTIMED);
964 event.set_endtime(_class_unload_time);
965 event.set_unloadedClass(k);
966 oop defining_class_loader = k->class_loader();
967 event.set_definingClassLoader(defining_class_loader != NULL ?
968 defining_class_loader->klass() : (Klass*)NULL);
969 event.commit();
970 }
971
972 #endif // INCLUDE_TRACE