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