1 /*
2 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // A ClassLoaderData identifies the full set of class types that a class
26 // loader's name resolution strategy produces for a given configuration of the
27 // class loader.
28 // Class types in the ClassLoaderData may be defined by from class file binaries
29 // provided by the class loader, or from other class loader it interacts with
30 // according to its name resolution strategy.
31 //
32 // Class loaders that implement a deterministic name resolution strategy
33 // (including with respect to their delegation behavior), such as the boot, the
34 // extension, and the system loaders of the JDK's built-in class loader
35 // hierarchy, always produce the same linkset for a given configuration.
36 //
37 // ClassLoaderData carries information related to a linkset (e.g.,
38 // metaspace holding its klass definitions).
39 // The System Dictionary and related data structures (e.g., placeholder table,
40 // loader constraints table) as well as the runtime representation of classes
41 // only reference ClassLoaderData.
42 //
43 // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that
44 // that represent the loader's "linking domain" in the JVM.
45 //
46 // The bootstrap loader (represented by NULL) also has a ClassLoaderData,
47 // the singleton class the_null_class_loader_data().
48
49 #include "precompiled.hpp"
50 #include "classfile/classLoaderData.hpp"
51 #include "classfile/classLoaderData.inline.hpp"
52 #include "classfile/javaClasses.hpp"
53 #include "classfile/metadataOnStackMark.hpp"
54 #include "classfile/systemDictionary.hpp"
55 #include "code/codeCache.hpp"
56 #include "memory/gcLocker.hpp"
57 #include "memory/metadataFactory.hpp"
58 #include "memory/metaspaceShared.hpp"
59 #include "memory/oopFactory.hpp"
60 #include "runtime/jniHandles.hpp"
61 #include "runtime/mutex.hpp"
62 #include "runtime/safepoint.hpp"
63 #include "runtime/synchronizer.hpp"
64 #include "utilities/growableArray.hpp"
65 #include "utilities/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), _keep_alive(is_anonymous), // initially
77 _metaspace(NULL), _unloading(false), _klasses(NULL),
78 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
79 _next(NULL), _dependencies(dependencies),
80 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {
81 // empty
82 }
83
84 void ClassLoaderData::init_dependencies(TRAPS) {
85 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
86 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
87 _dependencies.init(CHECK);
88 }
89
90 void ClassLoaderData::Dependencies::init(TRAPS) {
91 // Create empty dependencies array to add to. CMS requires this to be
92 // an oop so that it can track additions via card marks. We think.
93 _list_head = oopFactory::new_objectArray(2, CHECK);
94 }
95
96 bool ClassLoaderData::claim() {
97 if (_claimed == 1) {
98 return false;
99 }
100
101 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
102 }
103
104 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
105 if (must_claim && !claim()) {
106 return;
107 }
108
109 f->do_oop(&_class_loader);
110 _dependencies.oops_do(f);
111 _handles->oops_do(f);
112 if (klass_closure != NULL) {
113 classes_do(klass_closure);
114 }
115 }
116
117 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
118 f->do_oop((oop*)&_list_head);
119 }
120
121 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
122 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
123 klass_closure->do_klass(k);
124 assert(k != k->next_link(), "no loops!");
125 }
126 }
127
128 void ClassLoaderData::classes_do(void f(Klass * const)) {
129 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
130 f(k);
131 }
132 }
133
134 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
135 // Lock to avoid classes being modified/added/removed during iteration
136 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
137 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
138 // Do not filter ArrayKlass oops here...
139 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) {
140 klass_closure->do_klass(k);
141 }
142 }
143 }
144
145 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
146 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
147 if (k->oop_is_instance()) {
148 f(InstanceKlass::cast(k));
149 }
150 assert(k != k->next_link(), "no loops!");
151 }
152 }
153
154 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
155 ClassLoaderData * const from_cld = this;
156 ClassLoaderData * const to_cld = k->class_loader_data();
157
158 // Dependency to the null class loader data doesn't need to be recorded
159 // because the null class loader data never goes away.
160 if (to_cld->is_the_null_class_loader_data()) {
161 return;
162 }
163
164 oop to;
165 if (to_cld->is_anonymous()) {
166 // Anonymous class dependencies are through the mirror.
167 to = k->java_mirror();
168 } else {
169 to = to_cld->class_loader();
170
171 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
172 // we still have to add it. The class_loader won't keep from_cld alive.
173 if (!from_cld->is_anonymous()) {
174 // Check that this dependency isn't from the same or parent class_loader
175 oop from = from_cld->class_loader();
176
177 oop curr = from;
178 while (curr != NULL) {
179 if (curr == to) {
180 return; // this class loader is in the parent list, no need to add it.
181 }
182 curr = java_lang_ClassLoader::parent(curr);
183 }
184 }
185 }
186
187 // It's a dependency we won't find through GC, add it. This is relatively rare
188 // Must handle over GC point.
189 Handle dependency(THREAD, to);
190 from_cld->_dependencies.add(dependency, CHECK);
191 }
192
193
194 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
195 // Check first if this dependency is already in the list.
196 // Save a pointer to the last to add to under the lock.
197 objArrayOop ok = _list_head;
198 objArrayOop last = NULL;
199 while (ok != NULL) {
200 last = ok;
201 if (ok->obj_at(0) == dependency()) {
202 // Don't need to add it
203 return;
204 }
205 ok = (objArrayOop)ok->obj_at(1);
206 }
207
208 // Must handle over GC points
209 assert (last != NULL, "dependencies should be initialized");
210 objArrayHandle last_handle(THREAD, last);
211
212 // Create a new dependency node with fields for (class_loader or mirror, next)
213 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
214 deps->obj_at_put(0, dependency());
215
216 // Must handle over GC points
217 objArrayHandle new_dependency(THREAD, deps);
218
219 // Add the dependency under lock
220 locked_add(last_handle, new_dependency, THREAD);
221 }
222
223 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
224 objArrayHandle new_dependency,
225 Thread* THREAD) {
226
227 // Have to lock and put the new dependency on the end of the dependency
228 // array so the card mark for CMS sees that this dependency is new.
229 // Can probably do this lock free with some effort.
230 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
231
232 oop loader_or_mirror = new_dependency->obj_at(0);
233
234 // Since the dependencies are only added, add to the end.
235 objArrayOop end = last_handle();
236 objArrayOop last = NULL;
237 while (end != NULL) {
238 last = end;
239 // check again if another thread added it to the end.
240 if (end->obj_at(0) == loader_or_mirror) {
241 // Don't need to add it
242 return;
243 }
244 end = (objArrayOop)end->obj_at(1);
245 }
246 assert (last != NULL, "dependencies should be initialized");
247 // fill in the first element with the oop in new_dependency.
248 if (last->obj_at(0) == NULL) {
249 last->obj_at_put(0, new_dependency->obj_at(0));
250 } else {
251 last->obj_at_put(1, new_dependency());
252 }
253 }
254
255 void ClassLoaderDataGraph::clear_claimed_marks() {
256 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
257 cld->clear_claimed();
258 }
259 }
260
261 void ClassLoaderData::add_class(Klass* k) {
262 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
263 Klass* old_value = _klasses;
264 k->set_next_link(old_value);
265 // link the new item into the list
266 _klasses = k;
267
268 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
269 ResourceMark rm;
270 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
271 PTR_FORMAT " loader: " PTR_FORMAT " %s",
272 k,
273 k->external_name(),
274 k->class_loader_data(),
275 (void *)k->class_loader(),
276 loader_name());
277 }
278 }
279
280 // This is called by InstanceKlass::deallocate_contents() to remove the
281 // scratch_class for redefine classes. We need a lock because there it may not
282 // be called at a safepoint if there's an error.
283 void ClassLoaderData::remove_class(Klass* scratch_class) {
284 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
285 Klass* prev = NULL;
286 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
287 if (k == scratch_class) {
288 if (prev == NULL) {
289 _klasses = k->next_link();
290 } else {
291 Klass* next = k->next_link();
292 prev->set_next_link(next);
293 }
294 return;
295 }
296 prev = k;
297 assert(k != k->next_link(), "no loops!");
298 }
299 ShouldNotReachHere(); // should have found this class!!
300 }
301
302 void ClassLoaderData::unload() {
303 _unloading = true;
304
305 // Tell serviceability tools these classes are unloading
306 classes_do(InstanceKlass::notify_unload_class);
307
308 if (TraceClassLoaderData) {
309 ResourceMark rm;
310 tty->print("[ClassLoaderData: unload loader data "PTR_FORMAT, this);
311 tty->print(" for instance "PTR_FORMAT" of %s", (void *)class_loader(),
312 loader_name());
313 if (is_anonymous()) {
314 tty->print(" for anonymous class "PTR_FORMAT " ", _klasses);
315 }
316 tty->print_cr("]");
317 }
318 }
319
320 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
321 bool alive =
322 is_anonymous() ?
323 is_alive_closure->do_object_b(_klasses->java_mirror()) :
324 class_loader() == NULL || is_alive_closure->do_object_b(class_loader());
325 assert(!alive || claimed(), "must be claimed");
326 return alive;
327 }
328
329
330 ClassLoaderData::~ClassLoaderData() {
331 // Release C heap structures for all the classes.
332 classes_do(InstanceKlass::release_C_heap_structures);
333
334 Metaspace *m = _metaspace;
335 if (m != NULL) {
336 _metaspace = NULL;
337 // release the metaspace
338 delete m;
339 // release the handles
340 if (_handles != NULL) {
341 JNIHandleBlock::release_block(_handles);
342 _handles = NULL;
343 }
344 }
345
346 // Clear all the JNI handles for methods
347 // These aren't deallocated and are going to look like a leak, but that's
348 // needed because we can't really get rid of jmethodIDs because we don't
349 // know when native code is going to stop using them. The spec says that
350 // they're "invalid" but existing programs likely rely on their being
351 // NULL after class unloading.
352 if (_jmethod_ids != NULL) {
353 Method::clear_jmethod_ids(this);
354 }
355 // Delete lock
356 delete _metaspace_lock;
357
358 // Delete free list
359 if (_deallocate_list != NULL) {
360 delete _deallocate_list;
361 }
362 }
363
364 /**
365 * Returns true if this class loader data is for the extension class loader.
366 */
367 bool ClassLoaderData::is_ext_class_loader_data() const {
368 return SystemDictionary::is_ext_class_loader(class_loader());
369 }
370
371 Metaspace* ClassLoaderData::metaspace_non_null() {
372 assert(!DumpSharedSpaces, "wrong metaspace!");
373 // If the metaspace has not been allocated, create a new one. Might want
374 // to create smaller arena for Reflection class loaders also.
375 // The reason for the delayed allocation is because some class loaders are
376 // simply for delegating with no metadata of their own.
377 if (_metaspace == NULL) {
378 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
379 // Check again if metaspace has been allocated while we were getting this lock.
380 if (_metaspace != NULL) {
381 return _metaspace;
382 }
383 if (this == the_null_class_loader_data()) {
384 assert (class_loader() == NULL, "Must be");
385 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
386 } else if (is_anonymous()) {
387 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
388 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
389 }
390 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
391 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
392 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
393 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
394 }
395 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
396 } else {
397 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
398 }
399 }
400 return _metaspace;
401 }
402
403 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
404 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
405
406 jobject ClassLoaderData::add_handle(Handle h) {
407 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
408 if (handles() == NULL) {
409 set_handles(JNIHandleBlock::allocate_block());
410 }
411 return handles()->allocate_handle(h());
412 }
413
414 // Add this metadata pointer to be freed when it's safe. This is only during
415 // class unloading because Handles might point to this metadata field.
416 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
417 // Metadata in shared region isn't deleted.
418 if (!m->is_shared()) {
419 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
420 if (_deallocate_list == NULL) {
421 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
422 }
423 _deallocate_list->append_if_missing(m);
424 }
425 }
426
427 // Deallocate free metadata on the free list. How useful the PermGen was!
428 void ClassLoaderData::free_deallocate_list() {
429 // Don't need lock, at safepoint
430 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
431 if (_deallocate_list == NULL) {
432 return;
433 }
434 // Go backwards because this removes entries that are freed.
435 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
436 Metadata* m = _deallocate_list->at(i);
437 if (!m->on_stack()) {
438 _deallocate_list->remove_at(i);
439 // There are only three types of metadata that we deallocate directly.
440 // Cast them so they can be used by the template function.
441 if (m->is_method()) {
442 MetadataFactory::free_metadata(this, (Method*)m);
443 } else if (m->is_constantPool()) {
444 MetadataFactory::free_metadata(this, (ConstantPool*)m);
445 } else if (m->is_klass()) {
446 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
447 } else {
448 ShouldNotReachHere();
449 }
450 }
451 }
452 }
453
454 // These anonymous class loaders are to contain classes used for JSR292
455 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
456 // Add a new class loader data to the graph.
457 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL);
458 }
459
460 const char* ClassLoaderData::loader_name() {
461 // Handles null class loader
462 return SystemDictionary::loader_name(class_loader());
463 }
464
465 #ifndef PRODUCT
466 // Define to dump klasses
467 #undef CLD_DUMP_KLASSES
468
469 void ClassLoaderData::dump(outputStream * const out) {
470 ResourceMark rm;
471 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {",
472 this, (void *)class_loader(),
473 class_loader() != NULL ? class_loader()->klass() : NULL, loader_name());
474 if (claimed()) out->print(" claimed ");
475 if (is_unloading()) out->print(" unloading ");
476 out->print(" handles " INTPTR_FORMAT, handles());
477 out->cr();
478 if (metaspace_or_null() != NULL) {
479 out->print_cr("metaspace: " PTR_FORMAT, metaspace_or_null());
480 metaspace_or_null()->dump(out);
481 } else {
482 out->print_cr("metaspace: NULL");
483 }
484
485 #ifdef CLD_DUMP_KLASSES
486 if (Verbose) {
487 ResourceMark rm;
488 Klass* k = _klasses;
489 while (k != NULL) {
490 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
491 k->has_modified_oops(), k->has_accumulated_modified_oops());
492 assert(k != k->next_link(), "no loops!");
493 k = k->next_link();
494 }
495 }
496 #endif // CLD_DUMP_KLASSES
497 #undef CLD_DUMP_KLASSES
498 if (_jmethod_ids != NULL) {
499 Method::print_jmethod_ids(this, out);
500 }
501 out->print_cr("}");
502 }
503 #endif // PRODUCT
504
505 void ClassLoaderData::verify() {
506 oop cl = class_loader();
507
508 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
509 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
510
511 // Verify the integrity of the allocated space.
512 if (metaspace_or_null() != NULL) {
513 metaspace_or_null()->verify();
514 }
515
516 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
517 guarantee(k->class_loader_data() == this, "Must be the same");
518 k->verify();
519 assert(k != k->next_link(), "no loops!");
520 }
521 }
522
523
524 // GC root of class loader data created.
525 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
526 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
527 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
528
529 // Add a new class loader data node to the list. Assign the newly created
530 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
531 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
532 // We need to allocate all the oops for the ClassLoaderData before allocating the
533 // actual ClassLoaderData object.
534 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
535
536 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
537 // ClassLoaderData in the graph since the CLD
538 // contains unhandled oops
539
540 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
541
542
543 if (!is_anonymous) {
544 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
545 // First, Atomically set it
546 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
547 if (old != NULL) {
548 delete cld;
549 // Returns the data.
550 return old;
551 }
552 }
553
554 // We won the race, and therefore the task of adding the data to the list of
555 // class loader data
556 ClassLoaderData** list_head = &_head;
557 ClassLoaderData* next = _head;
558
559 do {
560 cld->set_next(next);
561 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
562 if (exchanged == next) {
563 if (TraceClassLoaderData) {
564 ResourceMark rm;
565 tty->print("[ClassLoaderData: ");
566 tty->print("create class loader data "PTR_FORMAT, cld);
567 tty->print(" for instance "PTR_FORMAT" of %s", (void *)cld->class_loader(),
568 cld->loader_name());
569 tty->print_cr("]");
570 }
571 return cld;
572 }
573 next = exchanged;
574 } while (true);
575
576 }
577
578 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
579 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
580 cld->oops_do(f, klass_closure, must_claim);
581 }
582 }
583
584 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
585 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
586 if (cld->keep_alive()) {
587 cld->oops_do(f, klass_closure, must_claim);
588 }
589 }
590 }
591
592 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
593 if (ClassUnloading) {
594 ClassLoaderData::the_null_class_loader_data()->oops_do(f, klass_closure, must_claim);
595 // keep any special CLDs alive.
596 ClassLoaderDataGraph::keep_alive_oops_do(f, klass_closure, must_claim);
597 } else {
598 ClassLoaderDataGraph::oops_do(f, klass_closure, must_claim);
599 }
600 }
601
602 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
603 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
604 cld->classes_do(klass_closure);
605 }
606 }
607
608 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
609 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
610 cld->classes_do(f);
611 }
612 }
613
614 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
615 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
616 cld->loaded_classes_do(klass_closure);
617 }
618 }
619
620 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
621 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
622 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
623 cld->classes_do(f);
624 }
625 }
626
627 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
628 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
629
630 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
631
632 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
633 ClassLoaderData* curr = _head;
634 while (curr != _saved_head) {
635 if (!curr->claimed()) {
636 array->push(curr);
637
638 if (TraceClassLoaderData) {
639 tty->print("[ClassLoaderData] found new CLD: ");
640 curr->print_value_on(tty);
641 tty->cr();
642 }
643 }
644
645 curr = curr->_next;
646 }
647
648 return array;
649 }
650
651 #ifndef PRODUCT
652 // for debugging and hsfind(x)
653 bool ClassLoaderDataGraph::contains(address x) {
654 // I think we need the _metaspace_lock taken here because the class loader
655 // data graph could be changing while we are walking it (new entries added,
656 // new entries being unloaded, etc).
657 if (DumpSharedSpaces) {
658 // There are only two metaspaces to worry about.
659 ClassLoaderData* ncld = ClassLoaderData::the_null_class_loader_data();
660 return (ncld->ro_metaspace()->contains(x) || ncld->rw_metaspace()->contains(x));
661 }
662
663 if (UseSharedSpaces && MetaspaceShared::is_in_shared_space(x)) {
664 return true;
665 }
666
667 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
668 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
669 return true;
670 }
671 }
672
673 // Could also be on an unloading list which is okay, ie. still allocated
674 // for a little while.
675 for (ClassLoaderData* ucld = _unloading; ucld != NULL; ucld = ucld->next()) {
676 if (ucld->metaspace_or_null() != NULL && ucld->metaspace_or_null()->contains(x)) {
677 return true;
678 }
679 }
680 return false;
681 }
682
683 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
684 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
685 if (loader_data == data) {
686 return true;
687 }
688 }
689
690 return false;
691 }
692 #endif // PRODUCT
693
694
695 // Move class loader data from main list to the unloaded list for unloading
696 // and deallocation later.
697 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure) {
698 ClassLoaderData* data = _head;
699 ClassLoaderData* prev = NULL;
700 bool seen_dead_loader = false;
701 // mark metadata seen on the stack and code cache so we can delete
702 // unneeded entries.
703 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
704 MetadataOnStackMark md_on_stack;
705 while (data != NULL) {
706 if (data->keep_alive() || data->is_alive(is_alive_closure)) {
707 if (has_redefined_a_class) {
708 data->classes_do(InstanceKlass::purge_previous_versions);
709 }
710 data->free_deallocate_list();
711 prev = data;
712 data = data->next();
713 continue;
714 }
715 seen_dead_loader = true;
716 ClassLoaderData* dead = data;
717 dead->unload();
718 data = data->next();
719 // Remove from loader list.
720 // This class loader data will no longer be found
721 // in the ClassLoaderDataGraph.
722 if (prev != NULL) {
723 prev->set_next(data);
724 } else {
725 assert(dead == _head, "sanity check");
726 _head = data;
727 }
728 dead->set_next(_unloading);
729 _unloading = dead;
730 }
731
732 if (seen_dead_loader) {
733 post_class_unload_events();
734 }
735
736 return seen_dead_loader;
737 }
738
739 void ClassLoaderDataGraph::purge() {
740 ClassLoaderData* list = _unloading;
741 _unloading = NULL;
742 ClassLoaderData* next = list;
743 while (next != NULL) {
744 ClassLoaderData* purge_me = next;
745 next = purge_me->next();
746 delete purge_me;
747 }
748 Metaspace::purge();
749 }
750
751 void ClassLoaderDataGraph::post_class_unload_events(void) {
752 #if INCLUDE_TRACE
753 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
754 if (Tracing::enabled()) {
755 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
756 assert(_unloading != NULL, "need class loader data unload list!");
757 _class_unload_time = Ticks::now();
758 classes_unloading_do(&class_unload_event);
759 }
760 Tracing::on_unloading_classes();
761 }
762 #endif
763 }
764
765 // CDS support
766
767 // Global metaspaces for writing information to the shared archive. When
768 // application CDS is supported, we may need one per metaspace, so this
769 // sort of looks like it.
770 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
771 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
772 static bool _shared_metaspaces_initialized = false;
773
774 // Initialize shared metaspaces (change to call from somewhere not lazily)
775 void ClassLoaderData::initialize_shared_metaspaces() {
776 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
777 assert(this == ClassLoaderData::the_null_class_loader_data(),
778 "only supported for null loader data for now");
779 assert (!_shared_metaspaces_initialized, "only initialize once");
780 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
781 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
782 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
783 _shared_metaspaces_initialized = true;
784 }
785
786 Metaspace* ClassLoaderData::ro_metaspace() {
787 assert(_ro_metaspace != NULL, "should already be initialized");
788 return _ro_metaspace;
789 }
790
791 Metaspace* ClassLoaderData::rw_metaspace() {
792 assert(_rw_metaspace != NULL, "should already be initialized");
793 return _rw_metaspace;
794 }
795
796
797 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
798 _data = ClassLoaderDataGraph::_head;
799 }
800
801 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
802
803 #ifndef PRODUCT
804 // callable from debugger
805 extern "C" int print_loader_data_graph() {
806 ClassLoaderDataGraph::dump_on(tty);
807 return 0;
808 }
809
810 void ClassLoaderDataGraph::verify() {
811 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
812 data->verify();
813 }
814 }
815
816 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
817 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
818 data->dump(out);
819 }
820 MetaspaceAux::dump(out);
821 }
822 #endif // PRODUCT
823
824 void ClassLoaderData::print_value_on(outputStream* out) const {
825 if (class_loader() == NULL) {
826 out->print("NULL class_loader");
827 } else {
828 out->print("class loader "PTR_FORMAT, this);
829 class_loader()->print_value_on(out);
830 }
831 }
832
833 #if INCLUDE_TRACE
834
835 Ticks ClassLoaderDataGraph::_class_unload_time;
836
837 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
838
839 // post class unload event
840 EventClassUnload event(UNTIMED);
841 event.set_endtime(_class_unload_time);
842 event.set_unloadedClass(k);
843 oop defining_class_loader = k->class_loader();
844 event.set_definingClassLoader(defining_class_loader != NULL ?
845 defining_class_loader->klass() : (Klass*)NULL);
846 event.commit();
847 }
848
849 #endif /* INCLUDE_TRACE */