1 /*
2 * Copyright (c) 2012, 2019, 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 #if INCLUDE_TRACE
68 #include "trace/tracing.hpp"
69 #endif
70
71 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
72
73 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
74 _class_loader(h_class_loader()),
75 _is_anonymous(is_anonymous),
76 // An anonymous class loader data doesn't have anything to keep
77 // it from being unloaded during parsing of the anonymous class.
78 // The null-class-loader should always be kept alive.
79 _keep_alive(is_anonymous || h_class_loader.is_null()),
80 _metaspace(NULL), _unloading(false), _klasses(NULL),
81 _claimed(0), _jmethod_ids(NULL), _handles(), _deallocate_list(NULL),
82 _next(NULL), _dependencies(dependencies),
83 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {
84 // empty
85 TRACE_INIT_ID(this);
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 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
101 Chunk* c = _head;
102 while (c != NULL) {
103 Chunk* next = c->_next;
104 delete c;
105 c = next;
106 }
107 }
108
109 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
110 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
111 Chunk* next = new Chunk(_head);
112 OrderAccess::release_store_ptr(&_head, next);
113 }
114 oop* handle = &_head->_data[_head->_size];
115 *handle = o;
116 OrderAccess::release_store(&_head->_size, _head->_size + 1);
117 return handle;
118 }
119
120 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
121 for (juint i = 0; i < size; i++) {
122 if (c->_data[i] != NULL) {
123 f->do_oop(&c->_data[i]);
124 }
125 }
126 }
127
128 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
129 Chunk* head = (Chunk*) OrderAccess::load_ptr_acquire(&_head);
130 if (head != NULL) {
131 // Must be careful when reading size of head
132 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
133 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
134 oops_do_chunk(f, c, c->_size);
135 }
136 }
137 }
138
139 bool ClassLoaderData::claim() {
140 if (_claimed == 1) {
141 return false;
142 }
143
144 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
145 }
146
147 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
148 if (must_claim && !claim()) {
149 return;
150 }
151
152 f->do_oop(&_class_loader);
153 _dependencies.oops_do(f);
154 _handles.oops_do(f);
155 if (klass_closure != NULL) {
156 classes_do(klass_closure);
157 }
158 }
159
160 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
161 f->do_oop((oop*)&_list_head);
162 }
163
164 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
165 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
166 klass_closure->do_klass(k);
167 assert(k != k->next_link(), "no loops!");
168 }
169 }
170
171 void ClassLoaderData::classes_do(void f(Klass * const)) {
172 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
173 f(k);
174 }
175 }
176
177 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
178 // Lock to avoid classes being modified/added/removed during iteration
179 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
180 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
181 // Do not filter ArrayKlass oops here...
182 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) {
183 klass_closure->do_klass(k);
184 }
185 }
186 }
187
188 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
189 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
190 if (k->oop_is_instance()) {
191 f(InstanceKlass::cast(k));
192 }
193 assert(k != k->next_link(), "no loops!");
194 }
195 }
196
197 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
198 ClassLoaderData * const from_cld = this;
199 ClassLoaderData * const to_cld = k->class_loader_data();
200
201 // Dependency to the null class loader data doesn't need to be recorded
202 // because the null class loader data never goes away.
203 if (to_cld->is_the_null_class_loader_data()) {
204 return;
205 }
206
207 oop to;
208 if (to_cld->is_anonymous()) {
209 // Anonymous class dependencies are through the mirror.
210 to = k->java_mirror();
211 } else {
212 to = to_cld->class_loader();
213
214 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
215 // we still have to add it. The class_loader won't keep from_cld alive.
216 if (!from_cld->is_anonymous()) {
217 // Check that this dependency isn't from the same or parent class_loader
218 oop from = from_cld->class_loader();
219
220 oop curr = from;
221 while (curr != NULL) {
222 if (curr == to) {
223 return; // this class loader is in the parent list, no need to add it.
224 }
225 curr = java_lang_ClassLoader::parent(curr);
226 }
227 }
228 }
229
230 // It's a dependency we won't find through GC, add it. This is relatively rare
231 // Must handle over GC point.
232 Handle dependency(THREAD, to);
233 from_cld->_dependencies.add(dependency, CHECK);
234 }
235
236
237 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
238 // Check first if this dependency is already in the list.
239 // Save a pointer to the last to add to under the lock.
240 objArrayOop ok = _list_head;
241 objArrayOop last = NULL;
242 while (ok != NULL) {
243 last = ok;
244 if (ok->obj_at(0) == dependency()) {
245 // Don't need to add it
246 return;
247 }
248 ok = (objArrayOop)ok->obj_at(1);
249 }
250
251 // Must handle over GC points
252 assert (last != NULL, "dependencies should be initialized");
253 objArrayHandle last_handle(THREAD, last);
254
255 // Create a new dependency node with fields for (class_loader or mirror, next)
256 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
257 deps->obj_at_put(0, dependency());
258
259 // Must handle over GC points
260 objArrayHandle new_dependency(THREAD, deps);
261
262 // Add the dependency under lock
263 locked_add(last_handle, new_dependency, THREAD);
264 }
265
266 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
267 objArrayHandle new_dependency,
268 Thread* THREAD) {
269
270 // Have to lock and put the new dependency on the end of the dependency
271 // array so the card mark for CMS sees that this dependency is new.
272 // Can probably do this lock free with some effort.
273 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
274
275 oop loader_or_mirror = new_dependency->obj_at(0);
276
277 // Since the dependencies are only added, add to the end.
278 objArrayOop end = last_handle();
279 objArrayOop last = NULL;
280 while (end != NULL) {
281 last = end;
282 // check again if another thread added it to the end.
283 if (end->obj_at(0) == loader_or_mirror) {
284 // Don't need to add it
285 return;
286 }
287 end = (objArrayOop)end->obj_at(1);
288 }
289 assert (last != NULL, "dependencies should be initialized");
290 // fill in the first element with the oop in new_dependency.
291 if (last->obj_at(0) == NULL) {
292 last->obj_at_put(0, new_dependency->obj_at(0));
293 } else {
294 last->obj_at_put(1, new_dependency());
295 }
296 }
297
298 void ClassLoaderDataGraph::clear_claimed_marks() {
299 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
300 cld->clear_claimed();
301 }
302 }
303
304 void ClassLoaderData::add_class(Klass* k) {
305 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
306 Klass* old_value = _klasses;
307 k->set_next_link(old_value);
308 // link the new item into the list
309 _klasses = k;
310
311 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
312 ResourceMark rm;
313 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
314 PTR_FORMAT " loader: " PTR_FORMAT " %s",
315 p2i(k),
316 k->external_name(),
317 p2i(k->class_loader_data()),
318 p2i((void *)k->class_loader()),
319 loader_name());
320 }
321 }
322
323 // This is called by InstanceKlass::deallocate_contents() to remove the
324 // scratch_class for redefine classes. We need a lock because there it may not
325 // be called at a safepoint if there's an error.
326 void ClassLoaderData::remove_class(Klass* scratch_class) {
327 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
328 Klass* prev = NULL;
329 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
330 if (k == scratch_class) {
331 if (prev == NULL) {
332 _klasses = k->next_link();
333 } else {
334 Klass* next = k->next_link();
335 prev->set_next_link(next);
336 }
337 return;
338 }
339 prev = k;
340 assert(k != k->next_link(), "no loops!");
341 }
342 ShouldNotReachHere(); // should have found this class!!
343 }
344
345 void ClassLoaderData::unload() {
346 _unloading = true;
347
348 // Tell serviceability tools these classes are unloading
349 classes_do(InstanceKlass::notify_unload_class);
350
351 if (TraceClassLoaderData) {
352 ResourceMark rm;
353 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this));
354 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
355 loader_name());
356 if (is_anonymous()) {
357 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
358 }
359 tty->print_cr("]");
360 }
361 }
362
363 oop ClassLoaderData::keep_alive_object() const {
364 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
365 return is_anonymous() ? _klasses->java_mirror() : class_loader();
366 }
367
368 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
369 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
370 || is_alive_closure->do_object_b(keep_alive_object());
371
372 return alive;
373 }
374
375
376 ClassLoaderData::~ClassLoaderData() {
377 // Release C heap structures for all the classes.
378 classes_do(InstanceKlass::release_C_heap_structures);
379
380 Metaspace *m = _metaspace;
381 if (m != NULL) {
382 _metaspace = NULL;
383 // release the metaspace
384 delete m;
385 }
386
387 // Clear all the JNI handles for methods
388 // These aren't deallocated and are going to look like a leak, but that's
389 // needed because we can't really get rid of jmethodIDs because we don't
390 // know when native code is going to stop using them. The spec says that
391 // they're "invalid" but existing programs likely rely on their being
392 // NULL after class unloading.
393 if (_jmethod_ids != NULL) {
394 Method::clear_jmethod_ids(this);
395 }
396 // Delete lock
397 delete _metaspace_lock;
398
399 // Delete free list
400 if (_deallocate_list != NULL) {
401 delete _deallocate_list;
402 }
403 }
404
405 /**
406 * Returns true if this class loader data is for the extension class loader.
407 */
408 bool ClassLoaderData::is_ext_class_loader_data() const {
409 return SystemDictionary::is_ext_class_loader(class_loader());
410 }
411
412 Metaspace* ClassLoaderData::metaspace_non_null() {
413 assert(!DumpSharedSpaces, "wrong metaspace!");
414 // If the metaspace has not been allocated, create a new one. Might want
415 // to create smaller arena for Reflection class loaders also.
416 // The reason for the delayed allocation is because some class loaders are
417 // simply for delegating with no metadata of their own.
418 if (_metaspace == NULL) {
419 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
420 // Check again if metaspace has been allocated while we were getting this lock.
421 if (_metaspace != NULL) {
422 return _metaspace;
423 }
424 if (this == the_null_class_loader_data()) {
425 assert (class_loader() == NULL, "Must be");
426 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
427 } else if (is_anonymous()) {
428 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
429 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
430 }
431 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
432 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
433 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
434 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
435 }
436 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
437 } else {
438 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
439 }
440 }
441 return _metaspace;
442 }
443
444 jobject ClassLoaderData::add_handle(Handle h) {
445 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
446 return (jobject) _handles.add(h());
447 }
448
449 // Add this metadata pointer to be freed when it's safe. This is only during
450 // class unloading because Handles might point to this metadata field.
451 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
452 // Metadata in shared region isn't deleted.
453 if (!m->is_shared()) {
454 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
455 if (_deallocate_list == NULL) {
456 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
457 }
458 _deallocate_list->append_if_missing(m);
459 }
460 }
461
462 // Deallocate free metadata on the free list. How useful the PermGen was!
463 void ClassLoaderData::free_deallocate_list() {
464 // Don't need lock, at safepoint
465 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
466 if (_deallocate_list == NULL) {
467 return;
468 }
469 // Go backwards because this removes entries that are freed.
470 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
471 Metadata* m = _deallocate_list->at(i);
472 if (!m->on_stack()) {
473 _deallocate_list->remove_at(i);
474 // There are only three types of metadata that we deallocate directly.
475 // Cast them so they can be used by the template function.
476 if (m->is_method()) {
477 MetadataFactory::free_metadata(this, (Method*)m);
478 } else if (m->is_constantPool()) {
479 MetadataFactory::free_metadata(this, (ConstantPool*)m);
480 } else if (m->is_klass()) {
481 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
482 } else {
483 ShouldNotReachHere();
484 }
485 }
486 }
487 }
488
489 // These anonymous class loaders are to contain classes used for JSR292
490 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
491 // Add a new class loader data to the graph.
492 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL);
493 }
494
495 const char* ClassLoaderData::loader_name() {
496 // Handles null class loader
497 return SystemDictionary::loader_name(class_loader());
498 }
499
500 #ifndef PRODUCT
501 // Define to dump klasses
502 #undef CLD_DUMP_KLASSES
503
504 void ClassLoaderData::dump(outputStream * const out) {
505 ResourceMark rm;
506 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
507 p2i(this), p2i((void *)class_loader()),
508 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
509 if (claimed()) out->print(" claimed ");
510 if (is_unloading()) out->print(" unloading ");
511 out->cr();
512 if (metaspace_or_null() != NULL) {
513 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
514 metaspace_or_null()->dump(out);
515 } else {
516 out->print_cr("metaspace: NULL");
517 }
518
519 #ifdef CLD_DUMP_KLASSES
520 if (Verbose) {
521 ResourceMark rm;
522 Klass* k = _klasses;
523 while (k != NULL) {
524 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
525 k->has_modified_oops(), k->has_accumulated_modified_oops());
526 assert(k != k->next_link(), "no loops!");
527 k = k->next_link();
528 }
529 }
530 #endif // CLD_DUMP_KLASSES
531 #undef CLD_DUMP_KLASSES
532 if (_jmethod_ids != NULL) {
533 Method::print_jmethod_ids(this, out);
534 }
535 out->print_cr("}");
536 }
537 #endif // PRODUCT
538
539 void ClassLoaderData::verify() {
540 oop cl = class_loader();
541
542 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
543 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
544
545 // Verify the integrity of the allocated space.
546 if (metaspace_or_null() != NULL) {
547 metaspace_or_null()->verify();
548 }
549
550 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
551 guarantee(k->class_loader_data() == this, "Must be the same");
552 k->verify();
553 assert(k != k->next_link(), "no loops!");
554 }
555 }
556
557 bool ClassLoaderData::contains_klass(Klass* klass) {
558 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
559 if (k == klass) return true;
560 }
561 return false;
562 }
563
564
565 // GC root of class loader data created.
566 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
567 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
568 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
569 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
570
571 bool ClassLoaderDataGraph::_should_purge = false;
572
573 // Add a new class loader data node to the list. Assign the newly created
574 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
575 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
576 // We need to allocate all the oops for the ClassLoaderData before allocating the
577 // actual ClassLoaderData object.
578 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
579
580 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
581 // ClassLoaderData in the graph since the CLD
582 // contains unhandled oops
583
584 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
585
586
587 if (!is_anonymous) {
588 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
589 // First, Atomically set it
590 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
591 if (old != NULL) {
592 delete cld;
593 // Returns the data.
594 return old;
595 }
596 }
597
598 // We won the race, and therefore the task of adding the data to the list of
599 // class loader data
600 ClassLoaderData** list_head = &_head;
601 ClassLoaderData* next = _head;
602
603 do {
604 cld->set_next(next);
605 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
606 if (exchanged == next) {
607 if (TraceClassLoaderData) {
608 ResourceMark rm;
609 tty->print("[ClassLoaderData: ");
610 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld));
611 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
612 cld->loader_name());
613 tty->print_cr("]");
614 }
615 return cld;
616 }
617 next = exchanged;
618 } while (true);
619
620 }
621
622 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
623 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
624 cld->oops_do(f, klass_closure, must_claim);
625 }
626 }
627
628 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
629 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
630 if (cld->keep_alive()) {
631 cld->oops_do(f, klass_closure, must_claim);
632 }
633 }
634 }
635
636 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
637 if (ClassUnloading) {
638 keep_alive_oops_do(f, klass_closure, must_claim);
639 } else {
640 oops_do(f, klass_closure, must_claim);
641 }
642 }
643
644 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
645 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
646 cl->do_cld(cld);
647 }
648 }
649
650 void ClassLoaderDataGraph::cld_unloading_do(CLDClosure* cl) {
651 // this method is only used by jfr now, if you need to use this method in another case,
652 // this check should be removed.
653 assert(EnableJFR && FlightRecorder, "just check");
654
655 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
656 // Only walk the head until any clds not purged from prior unloading
657 // (CMS doesn't purge right away).
658 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
659 assert(cld->is_unloading(), "invariant");
660 cl->do_cld(cld);
661 }
662 }
663
664 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
665 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
666 CLDClosure* closure = cld->keep_alive() ? strong : weak;
667 if (closure != NULL) {
668 closure->do_cld(cld);
669 }
670 }
671 }
672
673 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
674 roots_cld_do(cl, NULL);
675 }
676
677 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
678 if (ClassUnloading) {
679 keep_alive_cld_do(cl);
680 } else {
681 cld_do(cl);
682 }
683 }
684
685 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
686 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
687 cld->classes_do(klass_closure);
688 }
689 }
690
691 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
692 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
693 cld->classes_do(f);
694 }
695 }
696
697 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
698 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
699 cld->loaded_classes_do(klass_closure);
700 }
701 }
702
703 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
704 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
705 // Only walk the head until any clds not purged from prior unloading
706 // (CMS doesn't purge right away).
707 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
708 cld->classes_do(f);
709 }
710 }
711
712 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
713 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
714
715 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
716
717 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
718 ClassLoaderData* curr = _head;
719 while (curr != _saved_head) {
720 if (!curr->claimed()) {
721 array->push(curr);
722
723 if (TraceClassLoaderData) {
724 tty->print("[ClassLoaderData] found new CLD: ");
725 curr->print_value_on(tty);
726 tty->cr();
727 }
728 }
729
730 curr = curr->_next;
731 }
732
733 return array;
734 }
735
736 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
737 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
738 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
739 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
740 return true;
741 }
742 }
743 return false;
744 }
745
746 #ifndef PRODUCT
747 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
748 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
749 if (loader_data == data) {
750 return true;
751 }
752 }
753
754 return false;
755 }
756 #endif // PRODUCT
757
758
759 // Move class loader data from main list to the unloaded list for unloading
760 // and deallocation later.
761 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, bool clean_alive) {
762 ClassLoaderData* data = _head;
763 ClassLoaderData* prev = NULL;
764 bool seen_dead_loader = false;
765
766 // Save previous _unloading pointer for CMS which may add to unloading list before
767 // purging and we don't want to rewalk the previously unloaded class loader data.
768 _saved_unloading = _unloading;
769
770 while (data != NULL) {
771 if (data->is_alive(is_alive_closure)) {
772 prev = data;
773 data = data->next();
774 continue;
775 }
776 seen_dead_loader = true;
777 ClassLoaderData* dead = data;
778 dead->unload();
779 data = data->next();
780 // Remove from loader list.
781 // This class loader data will no longer be found
782 // in the ClassLoaderDataGraph.
783 if (prev != NULL) {
784 prev->set_next(data);
785 } else {
786 assert(dead == _head, "sanity check");
787 _head = data;
788 }
789 dead->set_next(_unloading);
790 _unloading = dead;
791 }
792
793 if (clean_alive) {
794 // Clean previous versions and the deallocate list.
795 ClassLoaderDataGraph::clean_metaspaces();
796 }
797
798 if (seen_dead_loader) {
799 post_class_unload_events();
800 }
801
802 return seen_dead_loader;
803 }
804
805 void ClassLoaderDataGraph::clean_metaspaces() {
806 // mark metadata seen on the stack and code cache so we can delete unneeded entries.
807 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
808 MetadataOnStackMark md_on_stack(has_redefined_a_class);
809
810 if (has_redefined_a_class) {
811 // purge_previous_versions also cleans weak method links. Because
812 // one method's MDO can reference another method from another
813 // class loader, we need to first clean weak method links for all
814 // class loaders here. Below, we can then free redefined methods
815 // for all class loaders.
816 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
817 data->classes_do(InstanceKlass::purge_previous_versions);
818 }
819 }
820
821 // Need to purge the previous version before deallocating.
822 free_deallocate_lists();
823 }
824
825 void ClassLoaderDataGraph::purge() {
826 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
827 ClassLoaderData* list = _unloading;
828 _unloading = NULL;
829 ClassLoaderData* next = list;
830 while (next != NULL) {
831 ClassLoaderData* purge_me = next;
832 next = purge_me->next();
833 delete purge_me;
834 }
835 Metaspace::purge();
836 }
837
838 void ClassLoaderDataGraph::post_class_unload_events(void) {
839 #if INCLUDE_TRACE
840 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
841 if (Tracing::enabled()) {
842 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
843 assert(_unloading != NULL, "need class loader data unload list!");
844 _class_unload_time = Ticks::now();
845 classes_unloading_do(&class_unload_event);
846 }
847 Tracing::on_unloading_classes();
848 }
849 #endif
850 }
851
852 void ClassLoaderDataGraph::free_deallocate_lists() {
853 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
854 // We need to keep this data until InstanceKlass::purge_previous_version has been
855 // called on all alive classes. See the comment in ClassLoaderDataGraph::clean_metaspaces.
856 cld->free_deallocate_list();
857 }
858
859 // In some rare cases items added to the unloading list will not be freed elsewhere.
860 // To keep it simple, walk the _unloading list also.
861 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
862 cld->free_deallocate_list();
863 }
864 }
865
866 // CDS support
867
868 // Global metaspaces for writing information to the shared archive. When
869 // application CDS is supported, we may need one per metaspace, so this
870 // sort of looks like it.
871 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
872 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
873 static bool _shared_metaspaces_initialized = false;
874
875 // Initialize shared metaspaces (change to call from somewhere not lazily)
876 void ClassLoaderData::initialize_shared_metaspaces() {
877 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
878 assert(this == ClassLoaderData::the_null_class_loader_data(),
879 "only supported for null loader data for now");
880 assert (!_shared_metaspaces_initialized, "only initialize once");
881 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
882 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
883 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
884 _shared_metaspaces_initialized = true;
885 }
886
887 Metaspace* ClassLoaderData::ro_metaspace() {
888 assert(_ro_metaspace != NULL, "should already be initialized");
889 return _ro_metaspace;
890 }
891
892 Metaspace* ClassLoaderData::rw_metaspace() {
893 assert(_rw_metaspace != NULL, "should already be initialized");
894 return _rw_metaspace;
895 }
896
897 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
898 : _next_klass(NULL) {
899 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
900 Klass* klass = NULL;
901
902 // Find the first klass in the CLDG.
903 while (cld != NULL) {
904 klass = cld->_klasses;
905 if (klass != NULL) {
906 _next_klass = klass;
907 return;
908 }
909 cld = cld->next();
910 }
911 }
912
913 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
914 Klass* next = klass->next_link();
915 if (next != NULL) {
916 return next;
917 }
918
919 // No more klasses in the current CLD. Time to find a new CLD.
920 ClassLoaderData* cld = klass->class_loader_data();
921 while (next == NULL) {
922 cld = cld->next();
923 if (cld == NULL) {
924 break;
925 }
926 next = cld->_klasses;
927 }
928
929 return next;
930 }
931
932 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
933 Klass* head = _next_klass;
934
935 while (head != NULL) {
936 Klass* next = next_klass_in_cldg(head);
937
938 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
939
940 if (old_head == head) {
941 return head; // Won the CAS.
942 }
943
944 head = old_head;
945 }
946
947 // Nothing more for the iterator to hand out.
948 assert(head == NULL, err_msg("head is " PTR_FORMAT ", expected not null:", p2i(head)));
949 return NULL;
950 }
951
952 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
953 _data = ClassLoaderDataGraph::_head;
954 }
955
956 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
957
958 #ifndef PRODUCT
959 // callable from debugger
960 extern "C" int print_loader_data_graph() {
961 ClassLoaderDataGraph::dump_on(tty);
962 return 0;
963 }
964
965 void ClassLoaderDataGraph::verify() {
966 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
967 data->verify();
968 }
969 }
970
971 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
972 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
973 data->dump(out);
974 }
975 MetaspaceAux::dump(out);
976 }
977 #endif // PRODUCT
978
979 void ClassLoaderData::print_value_on(outputStream* out) const {
980 if (class_loader() == NULL) {
981 out->print("NULL class_loader");
982 } else {
983 out->print("class loader " INTPTR_FORMAT, p2i(this));
984 class_loader()->print_value_on(out);
985 }
986 }
987
988 #if INCLUDE_TRACE
989
990 Ticks ClassLoaderDataGraph::_class_unload_time;
991
992 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
993
994 // post class unload event
995 EventClassUnload event(UNTIMED);
996 event.set_endtime(_class_unload_time);
997 event.set_unloadedClass(k);
998 event.set_definingClassLoader(k->class_loader_data());
999 event.commit();
1000 }
1001
1002 #endif // INCLUDE_TRACE