1 /*
2 * Copyright (c) 2012, 2015, 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 "oops/objArrayOop.inline.hpp"
61 #include "oops/oop.inline.hpp"
62 #include "runtime/atomic.inline.hpp"
63 #include "runtime/jniHandles.hpp"
64 #include "runtime/mutex.hpp"
65 #include "runtime/safepoint.hpp"
66 #include "runtime/synchronizer.hpp"
67 #include "utilities/growableArray.hpp"
68 #include "utilities/macros.hpp"
69 #include "utilities/ostream.hpp"
70 #if INCLUDE_TRACE
71 #include "trace/tracing.hpp"
72 #endif
73
74 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
75
76 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
77 _class_loader(h_class_loader()),
78 _is_anonymous(is_anonymous),
79 // An anonymous class loader data doesn't have anything to keep
80 // it from being unloaded during parsing of the anonymous class.
81 // The null-class-loader should always be kept alive.
82 _keep_alive(is_anonymous || h_class_loader.is_null()),
83 _metaspace(NULL), _unloading(false), _klasses(NULL),
84 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
85 _next(NULL), _dependencies(dependencies),
86 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
87 Monitor::_safepoint_check_never)) {
88 // empty
89 }
90
91 void ClassLoaderData::init_dependencies(TRAPS) {
92 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
93 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
94 _dependencies.init(CHECK);
95 }
96
97 void ClassLoaderData::Dependencies::init(TRAPS) {
98 // Create empty dependencies array to add to. CMS requires this to be
99 // an oop so that it can track additions via card marks. We think.
100 _list_head = oopFactory::new_objectArray(2, CHECK);
101 }
102
103 bool ClassLoaderData::claim() {
104 if (_claimed == 1) {
105 return false;
106 }
107
108 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
109 }
110
111 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
112 if (must_claim && !claim()) {
113 return;
114 }
115
116 f->do_oop(&_class_loader);
117 _dependencies.oops_do(f);
118 _handles->oops_do(f);
119 if (klass_closure != NULL) {
120 classes_do(klass_closure);
121 }
122 }
123
124 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
125 f->do_oop((oop*)&_list_head);
126 }
127
128 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
129 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
130 klass_closure->do_klass(k);
131 assert(k != k->next_link(), "no loops!");
132 }
133 }
134
135 void ClassLoaderData::classes_do(void f(Klass * const)) {
136 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
137 f(k);
138 }
139 }
140
141 void ClassLoaderData::methods_do(void f(Method*)) {
142 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
143 if (k->oop_is_instance()) {
144 InstanceKlass::cast(k)->methods_do(f);
145 }
146 }
147 }
148
149 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
150 // Lock to avoid classes being modified/added/removed during iteration
151 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
152 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
153 // Do not filter ArrayKlass oops here...
154 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) {
155 klass_closure->do_klass(k);
156 }
157 }
158 }
159
160 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
161 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
162 if (k->oop_is_instance()) {
163 f(InstanceKlass::cast(k));
164 }
165 assert(k != k->next_link(), "no loops!");
166 }
167 }
168
169 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
170 ClassLoaderData * const from_cld = this;
171 ClassLoaderData * const to_cld = k->class_loader_data();
172
173 // Dependency to the null class loader data doesn't need to be recorded
174 // because the null class loader data never goes away.
175 if (to_cld->is_the_null_class_loader_data()) {
176 return;
177 }
178
179 oop to;
180 if (to_cld->is_anonymous()) {
181 // Anonymous class dependencies are through the mirror.
182 to = k->java_mirror();
183 } else {
184 to = to_cld->class_loader();
185
186 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
187 // we still have to add it. The class_loader won't keep from_cld alive.
188 if (!from_cld->is_anonymous()) {
189 // Check that this dependency isn't from the same or parent class_loader
190 oop from = from_cld->class_loader();
191
192 oop curr = from;
193 while (curr != NULL) {
194 if (curr == to) {
195 return; // this class loader is in the parent list, no need to add it.
196 }
197 curr = java_lang_ClassLoader::parent(curr);
198 }
199 }
200 }
201
202 // It's a dependency we won't find through GC, add it. This is relatively rare
203 // Must handle over GC point.
204 Handle dependency(THREAD, to);
205 from_cld->_dependencies.add(dependency, CHECK);
206 }
207
208
209 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
210 // Check first if this dependency is already in the list.
211 // Save a pointer to the last to add to under the lock.
212 objArrayOop ok = _list_head;
213 objArrayOop last = NULL;
214 while (ok != NULL) {
215 last = ok;
216 if (ok->obj_at(0) == dependency()) {
217 // Don't need to add it
218 return;
219 }
220 ok = (objArrayOop)ok->obj_at(1);
221 }
222
223 // Must handle over GC points
224 assert (last != NULL, "dependencies should be initialized");
225 objArrayHandle last_handle(THREAD, last);
226
227 // Create a new dependency node with fields for (class_loader or mirror, next)
228 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
229 deps->obj_at_put(0, dependency());
230
231 // Must handle over GC points
232 objArrayHandle new_dependency(THREAD, deps);
233
234 // Add the dependency under lock
235 locked_add(last_handle, new_dependency, THREAD);
236 }
237
238 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
239 objArrayHandle new_dependency,
240 Thread* THREAD) {
241
242 // Have to lock and put the new dependency on the end of the dependency
243 // array so the card mark for CMS sees that this dependency is new.
244 // Can probably do this lock free with some effort.
245 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
246
247 oop loader_or_mirror = new_dependency->obj_at(0);
248
249 // Since the dependencies are only added, add to the end.
250 objArrayOop end = last_handle();
251 objArrayOop last = NULL;
252 while (end != NULL) {
253 last = end;
254 // check again if another thread added it to the end.
255 if (end->obj_at(0) == loader_or_mirror) {
256 // Don't need to add it
257 return;
258 }
259 end = (objArrayOop)end->obj_at(1);
260 }
261 assert (last != NULL, "dependencies should be initialized");
262 // fill in the first element with the oop in new_dependency.
263 if (last->obj_at(0) == NULL) {
264 last->obj_at_put(0, new_dependency->obj_at(0));
265 } else {
266 last->obj_at_put(1, new_dependency());
267 }
268 }
269
270 void ClassLoaderDataGraph::clear_claimed_marks() {
271 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
272 cld->clear_claimed();
273 }
274 }
275
276 void ClassLoaderData::add_class(Klass* k) {
277 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
278 Klass* old_value = _klasses;
279 k->set_next_link(old_value);
280 // Make sure linked class is stable, since the class list is walked without a lock
281 OrderAccess::storestore();
282 // link the new item into the list
283 _klasses = k;
284
285 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
286 ResourceMark rm;
287 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
288 PTR_FORMAT " loader: " PTR_FORMAT " %s",
289 p2i(k),
290 k->external_name(),
291 p2i(k->class_loader_data()),
292 p2i((void *)k->class_loader()),
293 loader_name());
294 }
295 }
296
297 // This is called by InstanceKlass::deallocate_contents() to remove the
298 // scratch_class for redefine classes. We need a lock because there it may not
299 // be called at a safepoint if there's an error.
300 void ClassLoaderData::remove_class(Klass* scratch_class) {
301 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
302 Klass* prev = NULL;
303 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
304 if (k == scratch_class) {
305 if (prev == NULL) {
306 _klasses = k->next_link();
307 } else {
308 Klass* next = k->next_link();
309 prev->set_next_link(next);
310 }
311 return;
312 }
313 prev = k;
314 assert(k != k->next_link(), "no loops!");
315 }
316 ShouldNotReachHere(); // should have found this class!!
317 }
318
319 void ClassLoaderData::unload() {
320 _unloading = true;
321
322 // Tell serviceability tools these classes are unloading
323 classes_do(InstanceKlass::notify_unload_class);
324
325 if (TraceClassLoaderData) {
326 ResourceMark rm;
327 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this));
328 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
329 loader_name());
330 if (is_anonymous()) {
331 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
332 }
333 tty->print_cr("]");
334 }
335 }
336
337 oop ClassLoaderData::keep_alive_object() const {
338 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
339 return is_anonymous() ? _klasses->java_mirror() : class_loader();
340 }
341
342 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
343 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
344 || is_alive_closure->do_object_b(keep_alive_object());
345
346 return alive;
347 }
348
349
350 ClassLoaderData::~ClassLoaderData() {
351 // Release C heap structures for all the classes.
352 classes_do(InstanceKlass::release_C_heap_structures);
353
354 Metaspace *m = _metaspace;
355 if (m != NULL) {
356 _metaspace = NULL;
357 // release the metaspace
358 delete m;
359 // release the handles
360 if (_handles != NULL) {
361 JNIHandleBlock::release_block(_handles);
362 _handles = NULL;
363 }
364 }
365
366 // Clear all the JNI handles for methods
367 // These aren't deallocated and are going to look like a leak, but that's
368 // needed because we can't really get rid of jmethodIDs because we don't
369 // know when native code is going to stop using them. The spec says that
370 // they're "invalid" but existing programs likely rely on their being
371 // NULL after class unloading.
372 if (_jmethod_ids != NULL) {
373 Method::clear_jmethod_ids(this);
374 }
375 // Delete lock
376 delete _metaspace_lock;
377
378 // Delete free list
379 if (_deallocate_list != NULL) {
380 delete _deallocate_list;
381 }
382 }
383
384 /**
385 * Returns true if this class loader data is for the extension class loader.
386 */
387 bool ClassLoaderData::is_ext_class_loader_data() const {
388 return SystemDictionary::is_ext_class_loader(class_loader());
389 }
390
391 Metaspace* ClassLoaderData::metaspace_non_null() {
392 assert(!DumpSharedSpaces, "wrong metaspace!");
393 // If the metaspace has not been allocated, create a new one. Might want
394 // to create smaller arena for Reflection class loaders also.
395 // The reason for the delayed allocation is because some class loaders are
396 // simply for delegating with no metadata of their own.
397 if (_metaspace == NULL) {
398 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
399 // Check again if metaspace has been allocated while we were getting this lock.
400 if (_metaspace != NULL) {
401 return _metaspace;
402 }
403 if (this == the_null_class_loader_data()) {
404 assert (class_loader() == NULL, "Must be");
405 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
406 } else if (is_anonymous()) {
407 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
408 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
409 }
410 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
411 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
412 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
413 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
414 }
415 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
416 } else {
417 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
418 }
419 }
420 return _metaspace;
421 }
422
423 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
424 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
425
426 jobject ClassLoaderData::add_handle(Handle h) {
427 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
428 if (handles() == NULL) {
429 set_handles(JNIHandleBlock::allocate_block());
430 }
431 return handles()->allocate_handle(h());
432 }
433
434 // Add this metadata pointer to be freed when it's safe. This is only during
435 // class unloading because Handles might point to this metadata field.
436 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
437 // Metadata in shared region isn't deleted.
438 if (!m->is_shared()) {
439 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
440 if (_deallocate_list == NULL) {
441 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
442 }
443 _deallocate_list->append_if_missing(m);
444 }
445 }
446
447 // Deallocate free metadata on the free list. How useful the PermGen was!
448 void ClassLoaderData::free_deallocate_list() {
449 // Don't need lock, at safepoint
450 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
451 if (_deallocate_list == NULL) {
452 return;
453 }
454 // Go backwards because this removes entries that are freed.
455 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
456 Metadata* m = _deallocate_list->at(i);
457 if (!m->on_stack()) {
458 _deallocate_list->remove_at(i);
459 // There are only three types of metadata that we deallocate directly.
460 // Cast them so they can be used by the template function.
461 if (m->is_method()) {
462 MetadataFactory::free_metadata(this, (Method*)m);
463 } else if (m->is_constantPool()) {
464 MetadataFactory::free_metadata(this, (ConstantPool*)m);
465 } else if (m->is_klass()) {
466 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
467 } else {
468 ShouldNotReachHere();
469 }
470 }
471 }
472 }
473
474 // These anonymous class loaders are to contain classes used for JSR292
475 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
476 // Add a new class loader data to the graph.
477 return ClassLoaderDataGraph::add(loader, true, THREAD);
478 }
479
480 const char* ClassLoaderData::loader_name() {
481 // Handles null class loader
482 return SystemDictionary::loader_name(class_loader());
483 }
484
485 #ifndef PRODUCT
486 // Define to dump klasses
487 #undef CLD_DUMP_KLASSES
488
489 void ClassLoaderData::dump(outputStream * const out) {
490 ResourceMark rm;
491 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {",
492 p2i(this), p2i((void *)class_loader()),
493 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
494 if (claimed()) out->print(" claimed ");
495 if (is_unloading()) out->print(" unloading ");
496 out->print(" handles " INTPTR_FORMAT, p2i(handles()));
497 out->cr();
498 if (metaspace_or_null() != NULL) {
499 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
500 metaspace_or_null()->dump(out);
501 } else {
502 out->print_cr("metaspace: NULL");
503 }
504
505 #ifdef CLD_DUMP_KLASSES
506 if (Verbose) {
507 ResourceMark rm;
508 Klass* k = _klasses;
509 while (k != NULL) {
510 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
511 k->has_modified_oops(), k->has_accumulated_modified_oops());
512 assert(k != k->next_link(), "no loops!");
513 k = k->next_link();
514 }
515 }
516 #endif // CLD_DUMP_KLASSES
517 #undef CLD_DUMP_KLASSES
518 if (_jmethod_ids != NULL) {
519 Method::print_jmethod_ids(this, out);
520 }
521 out->print_cr("}");
522 }
523 #endif // PRODUCT
524
525 void ClassLoaderData::verify() {
526 oop cl = class_loader();
527
528 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
529 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
530
531 // Verify the integrity of the allocated space.
532 if (metaspace_or_null() != NULL) {
533 metaspace_or_null()->verify();
534 }
535
536 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
537 guarantee(k->class_loader_data() == this, "Must be the same");
538 k->verify();
539 assert(k != k->next_link(), "no loops!");
540 }
541 }
542
543 bool ClassLoaderData::contains_klass(Klass* klass) {
544 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
545 if (k == klass) return true;
546 }
547 return false;
548 }
549
550
551 // GC root of class loader data created.
552 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
553 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
554 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
555 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
556
557 bool ClassLoaderDataGraph::_should_purge = false;
558 bool ClassLoaderDataGraph::_metaspace_oom = false;
559
560 // Add a new class loader data node to the list. Assign the newly created
561 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
562 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
563 // We need to allocate all the oops for the ClassLoaderData before allocating the
564 // actual ClassLoaderData object.
565 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
566
567 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
568 // ClassLoaderData in the graph since the CLD
569 // contains unhandled oops
570
571 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
572
573
574 if (!is_anonymous) {
575 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
576 // First, Atomically set it
577 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
578 if (old != NULL) {
579 delete cld;
580 // Returns the data.
581 return old;
582 }
583 }
584
585 // We won the race, and therefore the task of adding the data to the list of
586 // class loader data
587 ClassLoaderData** list_head = &_head;
588 ClassLoaderData* next = _head;
589
590 do {
591 cld->set_next(next);
592 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
593 if (exchanged == next) {
594 if (TraceClassLoaderData) {
595 ResourceMark rm;
596 tty->print("[ClassLoaderData: ");
597 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld));
598 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
599 cld->loader_name());
600 tty->print_cr("]");
601 }
602 return cld;
603 }
604 next = exchanged;
605 } while (true);
606
607 }
608
609 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
610 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
611 cld->oops_do(f, klass_closure, must_claim);
612 }
613 }
614
615 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
616 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
617 if (cld->keep_alive()) {
618 cld->oops_do(f, klass_closure, must_claim);
619 }
620 }
621 }
622
623 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
624 if (ClassUnloading) {
625 keep_alive_oops_do(f, klass_closure, must_claim);
626 } else {
627 oops_do(f, klass_closure, must_claim);
628 }
629 }
630
631 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
632 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
633 cl->do_cld(cld);
634 }
635 }
636
637 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
638 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
639 CLDClosure* closure = cld->keep_alive() ? strong : weak;
640 if (closure != NULL) {
641 closure->do_cld(cld);
642 }
643 }
644 }
645
646 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
647 roots_cld_do(cl, NULL);
648 }
649
650 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
651 if (ClassUnloading) {
652 keep_alive_cld_do(cl);
653 } else {
654 cld_do(cl);
655 }
656 }
657
658 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
659 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
660 cld->classes_do(klass_closure);
661 }
662 }
663
664 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
665 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
666 cld->classes_do(f);
667 }
668 }
669
670 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
671 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
672 cld->methods_do(f);
673 }
674 }
675
676 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
677 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
678 cld->loaded_classes_do(klass_closure);
679 }
680 }
681
682 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
683 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
684 // Only walk the head until any clds not purged from prior unloading
685 // (CMS doesn't purge right away).
686 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
687 cld->classes_do(f);
688 }
689 }
690
691 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
692 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
693
694 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
695
696 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
697 ClassLoaderData* curr = _head;
698 while (curr != _saved_head) {
699 if (!curr->claimed()) {
700 array->push(curr);
701
702 if (TraceClassLoaderData) {
703 tty->print("[ClassLoaderData] found new CLD: ");
704 curr->print_value_on(tty);
705 tty->cr();
706 }
707 }
708
709 curr = curr->_next;
710 }
711
712 return array;
713 }
714
715 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
716 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
717 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
718 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
719 return true;
720 }
721 }
722 return false;
723 }
724
725 #ifndef PRODUCT
726 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
727 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
728 if (loader_data == data) {
729 return true;
730 }
731 }
732
733 return false;
734 }
735 #endif // PRODUCT
736
737
738 // Move class loader data from main list to the unloaded list for unloading
739 // and deallocation later.
740 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, bool clean_alive) {
741 ClassLoaderData* data = _head;
742 ClassLoaderData* prev = NULL;
743 bool seen_dead_loader = false;
744
745 // Save previous _unloading pointer for CMS which may add to unloading list before
746 // purging and we don't want to rewalk the previously unloaded class loader data.
747 _saved_unloading = _unloading;
748
749 data = _head;
750 while (data != NULL) {
751 if (data->is_alive(is_alive_closure)) {
752 prev = data;
753 data = data->next();
754 continue;
755 }
756 seen_dead_loader = true;
757 ClassLoaderData* dead = data;
758 dead->unload();
759 data = data->next();
760 // Remove from loader list.
761 // This class loader data will no longer be found
762 // in the ClassLoaderDataGraph.
763 if (prev != NULL) {
764 prev->set_next(data);
765 } else {
766 assert(dead == _head, "sanity check");
767 _head = data;
768 }
769 dead->set_next(_unloading);
770 _unloading = dead;
771 }
772
773 if (clean_alive) {
774 // Clean previous versions and the deallocate list.
775 ClassLoaderDataGraph::clean_metaspaces();
776 }
777
778 if (seen_dead_loader) {
779 post_class_unload_events();
780 }
781
782 return seen_dead_loader;
783 }
784
785 void ClassLoaderDataGraph::clean_metaspaces() {
786 // mark metadata seen on the stack and code cache so we can delete unneeded entries.
787 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
788 MetadataOnStackMark md_on_stack(has_redefined_a_class);
789
790 if (has_redefined_a_class) {
791 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
792 data->classes_do(InstanceKlass::purge_previous_versions);
793 }
794 }
795
796 // Should purge the previous version before deallocating.
797 free_deallocate_lists();
798 }
799
800 void ClassLoaderDataGraph::purge() {
801 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
802 ClassLoaderData* list = _unloading;
803 _unloading = NULL;
804 ClassLoaderData* next = list;
805 bool classes_unloaded = false;
806 while (next != NULL) {
807 ClassLoaderData* purge_me = next;
808 next = purge_me->next();
809 delete purge_me;
810 classes_unloaded = true;
811 }
812 if (classes_unloaded) {
813 Metaspace::purge();
814 set_metaspace_oom(false);
815 }
816 }
817
818 void ClassLoaderDataGraph::post_class_unload_events(void) {
819 #if INCLUDE_TRACE
820 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
821 if (Tracing::enabled()) {
822 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
823 assert(_unloading != NULL, "need class loader data unload list!");
824 _class_unload_time = Ticks::now();
825 classes_unloading_do(&class_unload_event);
826 }
827 Tracing::on_unloading_classes();
828 }
829 #endif
830 }
831
832 void ClassLoaderDataGraph::free_deallocate_lists() {
833 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
834 cld->free_deallocate_list();
835 }
836 }
837
838 // CDS support
839
840 // Global metaspaces for writing information to the shared archive. When
841 // application CDS is supported, we may need one per metaspace, so this
842 // sort of looks like it.
843 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
844 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
845 static bool _shared_metaspaces_initialized = false;
846
847 // Initialize shared metaspaces (change to call from somewhere not lazily)
848 void ClassLoaderData::initialize_shared_metaspaces() {
849 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
850 assert(this == ClassLoaderData::the_null_class_loader_data(),
851 "only supported for null loader data for now");
852 assert (!_shared_metaspaces_initialized, "only initialize once");
853 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
854 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
855 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
856 _shared_metaspaces_initialized = true;
857 }
858
859 Metaspace* ClassLoaderData::ro_metaspace() {
860 assert(_ro_metaspace != NULL, "should already be initialized");
861 return _ro_metaspace;
862 }
863
864 Metaspace* ClassLoaderData::rw_metaspace() {
865 assert(_rw_metaspace != NULL, "should already be initialized");
866 return _rw_metaspace;
867 }
868
869 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
870 : _next_klass(NULL) {
871 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
872 Klass* klass = NULL;
873
874 // Find the first klass in the CLDG.
875 while (cld != NULL) {
876 klass = cld->_klasses;
877 if (klass != NULL) {
878 _next_klass = klass;
879 return;
880 }
881 cld = cld->next();
882 }
883 }
884
885 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
886 Klass* next = klass->next_link();
887 if (next != NULL) {
888 return next;
889 }
890
891 // No more klasses in the current CLD. Time to find a new CLD.
892 ClassLoaderData* cld = klass->class_loader_data();
893 while (next == NULL) {
894 cld = cld->next();
895 if (cld == NULL) {
896 break;
897 }
898 next = cld->_klasses;
899 }
900
901 return next;
902 }
903
904 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
905 Klass* head = (Klass*)_next_klass;
906
907 while (head != NULL) {
908 Klass* next = next_klass_in_cldg(head);
909
910 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
911
912 if (old_head == head) {
913 return head; // Won the CAS.
914 }
915
916 head = old_head;
917 }
918
919 // Nothing more for the iterator to hand out.
920 assert(head == NULL, err_msg("head is " PTR_FORMAT ", expected not null:", p2i(head)));
921 return NULL;
922 }
923
924 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
925 _data = ClassLoaderDataGraph::_head;
926 }
927
928 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
929
930 #ifndef PRODUCT
931 // callable from debugger
932 extern "C" int print_loader_data_graph() {
933 ClassLoaderDataGraph::dump_on(tty);
934 return 0;
935 }
936
937 void ClassLoaderDataGraph::verify() {
938 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
939 data->verify();
940 }
941 }
942
943 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
944 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
945 data->dump(out);
946 }
947 MetaspaceAux::dump(out);
948 }
949 #endif // PRODUCT
950
951 void ClassLoaderData::print_value_on(outputStream* out) const {
952 if (class_loader() == NULL) {
953 out->print("NULL class_loader");
954 } else {
955 out->print("class loader " INTPTR_FORMAT, p2i(this));
956 class_loader()->print_value_on(out);
957 }
958 }
959
960 #if INCLUDE_TRACE
961
962 Ticks ClassLoaderDataGraph::_class_unload_time;
963
964 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
965
966 // post class unload event
967 EventClassUnload event(UNTIMED);
968 event.set_endtime(_class_unload_time);
969 event.set_unloadedClass(k);
970 oop defining_class_loader = k->class_loader();
971 event.set_definingClassLoader(defining_class_loader != NULL ?
972 defining_class_loader->klass() : (Klass*)NULL);
973 event.commit();
974 }
975
976 #endif // INCLUDE_TRACE