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