1 /*
2 * Copyright (c) 2012, 2017, 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 }
86
87 void ClassLoaderData::init_dependencies(TRAPS) {
88 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
89 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
90 _dependencies.init(CHECK);
91 }
92
93 void ClassLoaderData::Dependencies::init(TRAPS) {
94 // Create empty dependencies array to add to. CMS requires this to be
95 // an oop so that it can track additions via card marks. We think.
96 _list_head = oopFactory::new_objectArray(2, CHECK);
97 }
98
99 ClassLoaderData::ChunkedHandleList::~ChunkedHandleList() {
100 Chunk* c = _head;
101 while (c != NULL) {
102 Chunk* next = c->_next;
103 delete c;
104 c = next;
105 }
106 }
107
108 oop* ClassLoaderData::ChunkedHandleList::add(oop o) {
109 if (_head == NULL || _head->_size == Chunk::CAPACITY) {
110 Chunk* next = new Chunk(_head);
111 OrderAccess::release_store_ptr(&_head, next);
112 }
113 oop* handle = &_head->_data[_head->_size];
114 *handle = o;
115 OrderAccess::release_store(&_head->_size, _head->_size + 1);
116 return handle;
117 }
118
119 inline void ClassLoaderData::ChunkedHandleList::oops_do_chunk(OopClosure* f, Chunk* c, const juint size) {
120 for (juint i = 0; i < size; i++) {
121 if (c->_data[i] != NULL) {
122 f->do_oop(&c->_data[i]);
123 }
124 }
125 }
126
127 void ClassLoaderData::ChunkedHandleList::oops_do(OopClosure* f) {
128 Chunk* head = (Chunk*) OrderAccess::load_ptr_acquire(&_head);
129 if (head != NULL) {
130 // Must be careful when reading size of head
131 oops_do_chunk(f, head, OrderAccess::load_acquire(&head->_size));
132 for (Chunk* c = head->_next; c != NULL; c = c->_next) {
133 oops_do_chunk(f, c, c->_size);
134 }
135 }
136 }
137
138 #ifdef ASSERT
139 class VerifyContainsOopClosure : public OopClosure {
140 oop* _target;
141 bool _found;
142
143 public:
144 VerifyContainsOopClosure(oop* target) : _target(target), _found(false) {}
145
146 void do_oop(oop* p) {
147 if (p == _target) {
148 _found = true;
149 }
150 }
151
152 void do_oop(narrowOop* p) {
153 // The ChunkedHandleList should not contain any narrowOop
154 ShouldNotReachHere();
155 }
156
157 bool found() const {
158 return _found;
159 }
160 };
161
162 bool ClassLoaderData::ChunkedHandleList::contains(oop* p) {
163 VerifyContainsOopClosure cl(p);
164 oops_do(&cl);
165 return cl.found();
166 }
167 #endif
168
169 bool ClassLoaderData::claim() {
170 if (_claimed == 1) {
171 return false;
172 }
173
174 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
175 }
176
177 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
178 if (must_claim && !claim()) {
179 return;
180 }
181
182 f->do_oop(&_class_loader);
183 _dependencies.oops_do(f);
184 _handles.oops_do(f);
185 if (klass_closure != NULL) {
186 classes_do(klass_closure);
187 }
188 }
189
190 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
191 f->do_oop((oop*)&_list_head);
192 }
193
194 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
195 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
196 klass_closure->do_klass(k);
197 assert(k != k->next_link(), "no loops!");
198 }
199 }
200
201 void ClassLoaderData::classes_do(void f(Klass * const)) {
202 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
203 f(k);
204 }
205 }
206
207 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
208 // Lock to avoid classes being modified/added/removed during iteration
209 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
210 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
211 // Do not filter ArrayKlass oops here...
212 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) {
213 klass_closure->do_klass(k);
214 }
215 }
216 }
217
218 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
219 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
220 if (k->oop_is_instance()) {
221 f(InstanceKlass::cast(k));
222 }
223 assert(k != k->next_link(), "no loops!");
224 }
225 }
226
227 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
228 ClassLoaderData * const from_cld = this;
229 ClassLoaderData * const to_cld = k->class_loader_data();
230
231 // Dependency to the null class loader data doesn't need to be recorded
232 // because the null class loader data never goes away.
233 if (to_cld->is_the_null_class_loader_data()) {
234 return;
235 }
236
237 oop to;
238 if (to_cld->is_anonymous()) {
239 // Anonymous class dependencies are through the mirror.
240 to = k->java_mirror();
241 } else {
242 to = to_cld->class_loader();
243
244 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
245 // we still have to add it. The class_loader won't keep from_cld alive.
246 if (!from_cld->is_anonymous()) {
247 // Check that this dependency isn't from the same or parent class_loader
248 oop from = from_cld->class_loader();
249
250 oop curr = from;
251 while (curr != NULL) {
252 if (curr == to) {
253 return; // this class loader is in the parent list, no need to add it.
254 }
255 curr = java_lang_ClassLoader::parent(curr);
256 }
257 }
258 }
259
260 // It's a dependency we won't find through GC, add it. This is relatively rare
261 // Must handle over GC point.
262 Handle dependency(THREAD, to);
263 from_cld->_dependencies.add(dependency, CHECK);
264 }
265
266
267 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
268 // Check first if this dependency is already in the list.
269 // Save a pointer to the last to add to under the lock.
270 objArrayOop ok = _list_head;
271 objArrayOop last = NULL;
272 while (ok != NULL) {
273 last = ok;
274 if (ok->obj_at(0) == dependency()) {
275 // Don't need to add it
276 return;
277 }
278 ok = (objArrayOop)ok->obj_at(1);
279 }
280
281 // Must handle over GC points
282 assert (last != NULL, "dependencies should be initialized");
283 objArrayHandle last_handle(THREAD, last);
284
285 // Create a new dependency node with fields for (class_loader or mirror, next)
286 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
287 deps->obj_at_put(0, dependency());
288
289 // Must handle over GC points
290 objArrayHandle new_dependency(THREAD, deps);
291
292 // Add the dependency under lock
293 locked_add(last_handle, new_dependency, THREAD);
294 }
295
296 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
297 objArrayHandle new_dependency,
298 Thread* THREAD) {
299
300 // Have to lock and put the new dependency on the end of the dependency
301 // array so the card mark for CMS sees that this dependency is new.
302 // Can probably do this lock free with some effort.
303 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
304
305 oop loader_or_mirror = new_dependency->obj_at(0);
306
307 // Since the dependencies are only added, add to the end.
308 objArrayOop end = last_handle();
309 objArrayOop last = NULL;
310 while (end != NULL) {
311 last = end;
312 // check again if another thread added it to the end.
313 if (end->obj_at(0) == loader_or_mirror) {
314 // Don't need to add it
315 return;
316 }
317 end = (objArrayOop)end->obj_at(1);
318 }
319 assert (last != NULL, "dependencies should be initialized");
320 // fill in the first element with the oop in new_dependency.
321 if (last->obj_at(0) == NULL) {
322 last->obj_at_put(0, new_dependency->obj_at(0));
323 } else {
324 last->obj_at_put(1, new_dependency());
325 }
326 }
327
328 void ClassLoaderDataGraph::clear_claimed_marks() {
329 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
330 cld->clear_claimed();
331 }
332 }
333
334 void ClassLoaderData::add_class(Klass* k) {
335 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
336 Klass* old_value = _klasses;
337 k->set_next_link(old_value);
338 // link the new item into the list
339 _klasses = k;
340
341 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
342 ResourceMark rm;
343 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
344 PTR_FORMAT " loader: " PTR_FORMAT " %s",
345 p2i(k),
346 k->external_name(),
347 p2i(k->class_loader_data()),
348 p2i((void *)k->class_loader()),
349 loader_name());
350 }
351 }
352
353 // This is called by InstanceKlass::deallocate_contents() to remove the
354 // scratch_class for redefine classes. We need a lock because there it may not
355 // be called at a safepoint if there's an error.
356 void ClassLoaderData::remove_class(Klass* scratch_class) {
357 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
358 Klass* prev = NULL;
359 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
360 if (k == scratch_class) {
361 if (prev == NULL) {
362 _klasses = k->next_link();
363 } else {
364 Klass* next = k->next_link();
365 prev->set_next_link(next);
366 }
367 return;
368 }
369 prev = k;
370 assert(k != k->next_link(), "no loops!");
371 }
372 ShouldNotReachHere(); // should have found this class!!
373 }
374
375 void ClassLoaderData::unload() {
376 _unloading = true;
377
378 // Tell serviceability tools these classes are unloading
379 classes_do(InstanceKlass::notify_unload_class);
380
381 if (TraceClassLoaderData) {
382 ResourceMark rm;
383 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this));
384 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
385 loader_name());
386 if (is_anonymous()) {
387 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
388 }
389 tty->print_cr("]");
390 }
391 }
392
393 oop ClassLoaderData::keep_alive_object() const {
394 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
395 return is_anonymous() ? _klasses->java_mirror() : class_loader();
396 }
397
398 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
399 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
400 || is_alive_closure->do_object_b(keep_alive_object());
401
402 return alive;
403 }
404
405
406 ClassLoaderData::~ClassLoaderData() {
407 // Release C heap structures for all the classes.
408 classes_do(InstanceKlass::release_C_heap_structures);
409
410 Metaspace *m = _metaspace;
411 if (m != NULL) {
412 _metaspace = NULL;
413 // release the metaspace
414 delete m;
415 }
416
417 // Clear all the JNI handles for methods
418 // These aren't deallocated and are going to look like a leak, but that's
419 // needed because we can't really get rid of jmethodIDs because we don't
420 // know when native code is going to stop using them. The spec says that
421 // they're "invalid" but existing programs likely rely on their being
422 // NULL after class unloading.
423 if (_jmethod_ids != NULL) {
424 Method::clear_jmethod_ids(this);
425 }
426 // Delete lock
427 delete _metaspace_lock;
428
429 // Delete free list
430 if (_deallocate_list != NULL) {
431 delete _deallocate_list;
432 }
433 }
434
435 /**
436 * Returns true if this class loader data is for the extension class loader.
437 */
438 bool ClassLoaderData::is_ext_class_loader_data() const {
439 return SystemDictionary::is_ext_class_loader(class_loader());
440 }
441
442 Metaspace* ClassLoaderData::metaspace_non_null() {
443 assert(!DumpSharedSpaces, "wrong metaspace!");
444 // If the metaspace has not been allocated, create a new one. Might want
445 // to create smaller arena for Reflection class loaders also.
446 // The reason for the delayed allocation is because some class loaders are
447 // simply for delegating with no metadata of their own.
448 if (_metaspace == NULL) {
449 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
450 // Check again if metaspace has been allocated while we were getting this lock.
451 if (_metaspace != NULL) {
452 return _metaspace;
453 }
454 if (this == the_null_class_loader_data()) {
455 assert (class_loader() == NULL, "Must be");
456 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
457 } else if (is_anonymous()) {
458 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
459 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
460 }
461 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
462 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
463 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
464 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
465 }
466 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
467 } else {
468 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
469 }
470 }
471 return _metaspace;
472 }
473
474 jobject ClassLoaderData::add_handle(Handle h) {
475 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
476 return (jobject) _handles.add(h());
477 }
478
479 // Add this metadata pointer to be freed when it's safe. This is only during
480 // class unloading because Handles might point to this metadata field.
481 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
482 // Metadata in shared region isn't deleted.
483 if (!m->is_shared()) {
484 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
485 if (_deallocate_list == NULL) {
486 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
487 }
488 _deallocate_list->append_if_missing(m);
489 }
490 }
491
492 // Deallocate free metadata on the free list. How useful the PermGen was!
493 void ClassLoaderData::free_deallocate_list() {
494 // Don't need lock, at safepoint
495 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
496 if (_deallocate_list == NULL) {
497 return;
498 }
499 // Go backwards because this removes entries that are freed.
500 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
501 Metadata* m = _deallocate_list->at(i);
502 if (!m->on_stack()) {
503 _deallocate_list->remove_at(i);
504 // There are only three types of metadata that we deallocate directly.
505 // Cast them so they can be used by the template function.
506 if (m->is_method()) {
507 MetadataFactory::free_metadata(this, (Method*)m);
508 } else if (m->is_constantPool()) {
509 MetadataFactory::free_metadata(this, (ConstantPool*)m);
510 } else if (m->is_klass()) {
511 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
512 } else {
513 ShouldNotReachHere();
514 }
515 }
516 }
517 }
518
519 // These anonymous class loaders are to contain classes used for JSR292
520 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
521 // Add a new class loader data to the graph.
522 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL);
523 }
524
525 const char* ClassLoaderData::loader_name() {
526 // Handles null class loader
527 return SystemDictionary::loader_name(class_loader());
528 }
529
530 #ifndef PRODUCT
531 // Define to dump klasses
532 #undef CLD_DUMP_KLASSES
533
534 void ClassLoaderData::dump(outputStream * const out) {
535 ResourceMark rm;
536 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {",
537 p2i(this), p2i((void *)class_loader()),
538 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
539 if (claimed()) out->print(" claimed ");
540 if (is_unloading()) out->print(" unloading ");
541 out->cr();
542 if (metaspace_or_null() != NULL) {
543 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
544 metaspace_or_null()->dump(out);
545 } else {
546 out->print_cr("metaspace: NULL");
547 }
548
549 #ifdef CLD_DUMP_KLASSES
550 if (Verbose) {
551 ResourceMark rm;
552 Klass* k = _klasses;
553 while (k != NULL) {
554 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
555 k->has_modified_oops(), k->has_accumulated_modified_oops());
556 assert(k != k->next_link(), "no loops!");
557 k = k->next_link();
558 }
559 }
560 #endif // CLD_DUMP_KLASSES
561 #undef CLD_DUMP_KLASSES
562 if (_jmethod_ids != NULL) {
563 Method::print_jmethod_ids(this, out);
564 }
565 out->print_cr("}");
566 }
567 #endif // PRODUCT
568
569 void ClassLoaderData::verify() {
570 oop cl = class_loader();
571
572 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
573 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
574
575 // Verify the integrity of the allocated space.
576 if (metaspace_or_null() != NULL) {
577 metaspace_or_null()->verify();
578 }
579
580 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
581 guarantee(k->class_loader_data() == this, "Must be the same");
582 k->verify();
583 assert(k != k->next_link(), "no loops!");
584 }
585 }
586
587 bool ClassLoaderData::contains_klass(Klass* klass) {
588 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
589 if (k == klass) return true;
590 }
591 return false;
592 }
593
594
595 // GC root of class loader data created.
596 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
597 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
598 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
599 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
600
601 bool ClassLoaderDataGraph::_should_purge = false;
602
603 // Add a new class loader data node to the list. Assign the newly created
604 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
605 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
606 // We need to allocate all the oops for the ClassLoaderData before allocating the
607 // actual ClassLoaderData object.
608 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
609
610 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
611 // ClassLoaderData in the graph since the CLD
612 // contains unhandled oops
613
614 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
615
616
617 if (!is_anonymous) {
618 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
619 // First, Atomically set it
620 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
621 if (old != NULL) {
622 delete cld;
623 // Returns the data.
624 return old;
625 }
626 }
627
628 // We won the race, and therefore the task of adding the data to the list of
629 // class loader data
630 ClassLoaderData** list_head = &_head;
631 ClassLoaderData* next = _head;
632
633 do {
634 cld->set_next(next);
635 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
636 if (exchanged == next) {
637 if (TraceClassLoaderData) {
638 ResourceMark rm;
639 tty->print("[ClassLoaderData: ");
640 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld));
641 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
642 cld->loader_name());
643 tty->print_cr("]");
644 }
645 return cld;
646 }
647 next = exchanged;
648 } while (true);
649
650 }
651
652 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
653 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
654 cld->oops_do(f, klass_closure, must_claim);
655 }
656 }
657
658 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
659 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
660 if (cld->keep_alive()) {
661 cld->oops_do(f, klass_closure, must_claim);
662 }
663 }
664 }
665
666 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
667 if (ClassUnloading) {
668 keep_alive_oops_do(f, klass_closure, must_claim);
669 } else {
670 oops_do(f, klass_closure, must_claim);
671 }
672 }
673
674 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
675 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
676 cl->do_cld(cld);
677 }
678 }
679
680 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
681 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
682 CLDClosure* closure = cld->keep_alive() ? strong : weak;
683 if (closure != NULL) {
684 closure->do_cld(cld);
685 }
686 }
687 }
688
689 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
690 roots_cld_do(cl, NULL);
691 }
692
693 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
694 if (ClassUnloading) {
695 keep_alive_cld_do(cl);
696 } else {
697 cld_do(cl);
698 }
699 }
700
701 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
702 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
703 cld->classes_do(klass_closure);
704 }
705 }
706
707 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
708 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
709 cld->classes_do(f);
710 }
711 }
712
713 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
714 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
715 cld->loaded_classes_do(klass_closure);
716 }
717 }
718
719 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
720 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
721 // Only walk the head until any clds not purged from prior unloading
722 // (CMS doesn't purge right away).
723 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
724 cld->classes_do(f);
725 }
726 }
727
728 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
729 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
730
731 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
732
733 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
734 ClassLoaderData* curr = _head;
735 while (curr != _saved_head) {
736 if (!curr->claimed()) {
737 array->push(curr);
738
739 if (TraceClassLoaderData) {
740 tty->print("[ClassLoaderData] found new CLD: ");
741 curr->print_value_on(tty);
742 tty->cr();
743 }
744 }
745
746 curr = curr->_next;
747 }
748
749 return array;
750 }
751
752 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
753 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
754 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
755 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
756 return true;
757 }
758 }
759 return false;
760 }
761
762 #ifndef PRODUCT
763 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
764 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
765 if (loader_data == data) {
766 return true;
767 }
768 }
769
770 return false;
771 }
772 #endif // PRODUCT
773
774
775 // Move class loader data from main list to the unloaded list for unloading
776 // and deallocation later.
777 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, bool clean_alive) {
778 ClassLoaderData* data = _head;
779 ClassLoaderData* prev = NULL;
780 bool seen_dead_loader = false;
781
782 // Save previous _unloading pointer for CMS which may add to unloading list before
783 // purging and we don't want to rewalk the previously unloaded class loader data.
784 _saved_unloading = _unloading;
785
786 while (data != NULL) {
787 if (data->is_alive(is_alive_closure)) {
788 prev = data;
789 data = data->next();
790 continue;
791 }
792 seen_dead_loader = true;
793 ClassLoaderData* dead = data;
794 dead->unload();
795 data = data->next();
796 // Remove from loader list.
797 // This class loader data will no longer be found
798 // in the ClassLoaderDataGraph.
799 if (prev != NULL) {
800 prev->set_next(data);
801 } else {
802 assert(dead == _head, "sanity check");
803 _head = data;
804 }
805 dead->set_next(_unloading);
806 _unloading = dead;
807 }
808
809 if (clean_alive) {
810 // Clean previous versions and the deallocate list.
811 ClassLoaderDataGraph::clean_metaspaces();
812 }
813
814 if (seen_dead_loader) {
815 post_class_unload_events();
816 }
817
818 return seen_dead_loader;
819 }
820
821 void ClassLoaderDataGraph::clean_metaspaces() {
822 // mark metadata seen on the stack and code cache so we can delete unneeded entries.
823 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
824 MetadataOnStackMark md_on_stack(has_redefined_a_class);
825
826 if (has_redefined_a_class) {
827 // purge_previous_versions also cleans weak method links. Because
828 // one method's MDO can reference another method from another
829 // class loader, we need to first clean weak method links for all
830 // class loaders here. Below, we can then free redefined methods
831 // for all class loaders.
832 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
833 data->classes_do(InstanceKlass::purge_previous_versions);
834 }
835 }
836
837 // Need to purge the previous version before deallocating.
838 free_deallocate_lists();
839 }
840
841 void ClassLoaderDataGraph::purge() {
842 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
843 ClassLoaderData* list = _unloading;
844 _unloading = NULL;
845 ClassLoaderData* next = list;
846 while (next != NULL) {
847 ClassLoaderData* purge_me = next;
848 next = purge_me->next();
849 delete purge_me;
850 }
851 Metaspace::purge();
852 }
853
854 void ClassLoaderDataGraph::post_class_unload_events(void) {
855 #if INCLUDE_TRACE
856 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
857 if (Tracing::enabled()) {
858 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
859 assert(_unloading != NULL, "need class loader data unload list!");
860 _class_unload_time = Ticks::now();
861 classes_unloading_do(&class_unload_event);
862 }
863 Tracing::on_unloading_classes();
864 }
865 #endif
866 }
867
868 void ClassLoaderDataGraph::free_deallocate_lists() {
869 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
870 // We need to keep this data until InstanceKlass::purge_previous_version has been
871 // called on all alive classes. See the comment in ClassLoaderDataGraph::clean_metaspaces.
872 cld->free_deallocate_list();
873 }
874
875 // In some rare cases items added to the unloading list will not be freed elsewhere.
876 // To keep it simple, walk the _unloading list also.
877 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
878 cld->free_deallocate_list();
879 }
880 }
881
882 // CDS support
883
884 // Global metaspaces for writing information to the shared archive. When
885 // application CDS is supported, we may need one per metaspace, so this
886 // sort of looks like it.
887 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
888 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
889 static bool _shared_metaspaces_initialized = false;
890
891 // Initialize shared metaspaces (change to call from somewhere not lazily)
892 void ClassLoaderData::initialize_shared_metaspaces() {
893 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
894 assert(this == ClassLoaderData::the_null_class_loader_data(),
895 "only supported for null loader data for now");
896 assert (!_shared_metaspaces_initialized, "only initialize once");
897 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
898 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
899 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
900 _shared_metaspaces_initialized = true;
901 }
902
903 Metaspace* ClassLoaderData::ro_metaspace() {
904 assert(_ro_metaspace != NULL, "should already be initialized");
905 return _ro_metaspace;
906 }
907
908 Metaspace* ClassLoaderData::rw_metaspace() {
909 assert(_rw_metaspace != NULL, "should already be initialized");
910 return _rw_metaspace;
911 }
912
913 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
914 : _next_klass(NULL) {
915 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
916 Klass* klass = NULL;
917
918 // Find the first klass in the CLDG.
919 while (cld != NULL) {
920 klass = cld->_klasses;
921 if (klass != NULL) {
922 _next_klass = klass;
923 return;
924 }
925 cld = cld->next();
926 }
927 }
928
929 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
930 Klass* next = klass->next_link();
931 if (next != NULL) {
932 return next;
933 }
934
935 // No more klasses in the current CLD. Time to find a new CLD.
936 ClassLoaderData* cld = klass->class_loader_data();
937 while (next == NULL) {
938 cld = cld->next();
939 if (cld == NULL) {
940 break;
941 }
942 next = cld->_klasses;
943 }
944
945 return next;
946 }
947
948 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
949 Klass* head = _next_klass;
950
951 while (head != NULL) {
952 Klass* next = next_klass_in_cldg(head);
953
954 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
955
956 if (old_head == head) {
957 return head; // Won the CAS.
958 }
959
960 head = old_head;
961 }
962
963 // Nothing more for the iterator to hand out.
964 assert(head == NULL, err_msg("head is " PTR_FORMAT ", expected not null:", p2i(head)));
965 return NULL;
966 }
967
968 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
969 _data = ClassLoaderDataGraph::_head;
970 }
971
972 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
973
974 #ifndef PRODUCT
975 // callable from debugger
976 extern "C" int print_loader_data_graph() {
977 ClassLoaderDataGraph::dump_on(tty);
978 return 0;
979 }
980
981 void ClassLoaderDataGraph::verify() {
982 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
983 data->verify();
984 }
985 }
986
987 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
988 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
989 data->dump(out);
990 }
991 MetaspaceAux::dump(out);
992 }
993 #endif // PRODUCT
994
995 void ClassLoaderData::print_value_on(outputStream* out) const {
996 if (class_loader() == NULL) {
997 out->print("NULL class_loader");
998 } else {
999 out->print("class loader " INTPTR_FORMAT, p2i(this));
1000 class_loader()->print_value_on(out);
1001 }
1002 }
1003
1004 #if INCLUDE_TRACE
1005
1006 Ticks ClassLoaderDataGraph::_class_unload_time;
1007
1008 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1009
1010 // post class unload event
1011 EventClassUnload event(UNTIMED);
1012 event.set_endtime(_class_unload_time);
1013 event.set_unloadedClass(k);
1014 oop defining_class_loader = k->class_loader();
1015 event.set_definingClassLoader(defining_class_loader != NULL ?
1016 defining_class_loader->klass() : (Klass*)NULL);
1017 event.commit();
1018 }
1019
1020 #endif // INCLUDE_TRACE