1 /*
2 * Copyright (c) 2012, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 // A ClassLoaderData identifies the full set of class types that a class
26 // loader's name resolution strategy produces for a given configuration of the
27 // class loader.
28 // Class types in the ClassLoaderData may be defined by from class file binaries
29 // provided by the class loader, or from other class loader it interacts with
30 // according to its name resolution strategy.
31 //
32 // Class loaders that implement a deterministic name resolution strategy
33 // (including with respect to their delegation behavior), such as the boot, the
34 // extension, and the system loaders of the JDK's built-in class loader
35 // hierarchy, always produce the same linkset for a given configuration.
36 //
37 // ClassLoaderData carries information related to a linkset (e.g.,
38 // metaspace holding its klass definitions).
39 // The System Dictionary and related data structures (e.g., placeholder table,
40 // loader constraints table) as well as the runtime representation of classes
41 // only reference ClassLoaderData.
42 //
43 // Instances of java.lang.ClassLoader holds a pointer to a ClassLoaderData that
44 // that represent the loader's "linking domain" in the JVM.
45 //
46 // The bootstrap loader (represented by NULL) also has a ClassLoaderData,
47 // the singleton class the_null_class_loader_data().
48
49 #include "precompiled.hpp"
50 #include "classfile/classLoaderData.hpp"
51 #include "classfile/classLoaderData.inline.hpp"
52 #include "classfile/javaClasses.hpp"
53 #include "classfile/metadataOnStackMark.hpp"
54 #include "classfile/systemDictionary.hpp"
55 #include "code/codeCache.hpp"
56 #include "memory/gcLocker.hpp"
57 #include "memory/metadataFactory.hpp"
58 #include "memory/metaspaceShared.hpp"
59 #include "memory/oopFactory.hpp"
60 #include "runtime/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(NULL), _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 bool ClassLoaderData::claim() {
100 if (_claimed == 1) {
101 return false;
102 }
103
104 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
105 }
106
107 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
108 if (must_claim && !claim()) {
109 return;
110 }
111
112 f->do_oop(&_class_loader);
113 _dependencies.oops_do(f);
114 _handles->oops_do(f);
115 if (klass_closure != NULL) {
116 classes_do(klass_closure);
117 }
118 }
119
120 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
121 f->do_oop((oop*)&_list_head);
122 }
123
124 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
125 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
126 klass_closure->do_klass(k);
127 assert(k != k->next_link(), "no loops!");
128 }
129 }
130
131 void ClassLoaderData::classes_do(void f(Klass * const)) {
132 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
133 f(k);
134 }
135 }
136
137 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
138 // Lock to avoid classes being modified/added/removed during iteration
139 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
140 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
141 // Do not filter ArrayKlass oops here...
142 if (k->oop_is_array() || (k->oop_is_instance() && InstanceKlass::cast(k)->is_loaded())) {
143 klass_closure->do_klass(k);
144 }
145 }
146 }
147
148 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
149 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
150 if (k->oop_is_instance()) {
151 f(InstanceKlass::cast(k));
152 }
153 assert(k != k->next_link(), "no loops!");
154 }
155 }
156
157 void ClassLoaderData::record_dependency(Klass* k, TRAPS) {
158 ClassLoaderData * const from_cld = this;
159 ClassLoaderData * const to_cld = k->class_loader_data();
160
161 // Dependency to the null class loader data doesn't need to be recorded
162 // because the null class loader data never goes away.
163 if (to_cld->is_the_null_class_loader_data()) {
164 return;
165 }
166
167 oop to;
168 if (to_cld->is_anonymous()) {
169 // Anonymous class dependencies are through the mirror.
170 to = k->java_mirror();
171 } else {
172 to = to_cld->class_loader();
173
174 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
175 // we still have to add it. The class_loader won't keep from_cld alive.
176 if (!from_cld->is_anonymous()) {
177 // Check that this dependency isn't from the same or parent class_loader
178 oop from = from_cld->class_loader();
179
180 oop curr = from;
181 while (curr != NULL) {
182 if (oopDesc::equals(curr, to)) {
183 return; // this class loader is in the parent list, no need to add it.
184 }
185 curr = java_lang_ClassLoader::parent(curr);
186 }
187 }
188 }
189
190 // It's a dependency we won't find through GC, add it. This is relatively rare
191 // Must handle over GC point.
192 Handle dependency(THREAD, to);
193 from_cld->_dependencies.add(dependency, CHECK);
194 }
195
196
197 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
198 // Check first if this dependency is already in the list.
199 // Save a pointer to the last to add to under the lock.
200 objArrayOop ok = _list_head;
201 objArrayOop last = NULL;
202 while (ok != NULL) {
203 last = ok;
204 if (oopDesc::equals(ok->obj_at(0), dependency())) {
205 // Don't need to add it
206 return;
207 }
208 ok = (objArrayOop)ok->obj_at(1);
209 }
210
211 // Must handle over GC points
212 assert (last != NULL, "dependencies should be initialized");
213 objArrayHandle last_handle(THREAD, last);
214
215 // Create a new dependency node with fields for (class_loader or mirror, next)
216 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
217 deps->obj_at_put(0, dependency());
218
219 // Must handle over GC points
220 objArrayHandle new_dependency(THREAD, deps);
221
222 // Add the dependency under lock
223 locked_add(last_handle, new_dependency, THREAD);
224 }
225
226 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
227 objArrayHandle new_dependency,
228 Thread* THREAD) {
229
230 // Have to lock and put the new dependency on the end of the dependency
231 // array so the card mark for CMS sees that this dependency is new.
232 // Can probably do this lock free with some effort.
233 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
234
235 oop loader_or_mirror = new_dependency->obj_at(0);
236
237 // Since the dependencies are only added, add to the end.
238 objArrayOop end = last_handle();
239 objArrayOop last = NULL;
240 while (end != NULL) {
241 last = end;
242 // check again if another thread added it to the end.
243 if (oopDesc::equals(end->obj_at(0), loader_or_mirror)) {
244 // Don't need to add it
245 return;
246 }
247 end = (objArrayOop)end->obj_at(1);
248 }
249 assert (last != NULL, "dependencies should be initialized");
250 // fill in the first element with the oop in new_dependency.
251 if (last->obj_at(0) == NULL) {
252 last->obj_at_put(0, new_dependency->obj_at(0));
253 } else {
254 last->obj_at_put(1, new_dependency());
255 }
256 }
257
258 void ClassLoaderDataGraph::clear_claimed_marks() {
259 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
260 cld->clear_claimed();
261 }
262 }
263
264 void ClassLoaderData::add_class(Klass* k) {
265 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
266 Klass* old_value = _klasses;
267 k->set_next_link(old_value);
268 // link the new item into the list
269 _klasses = k;
270
271 if (TraceClassLoaderData && Verbose && k->class_loader_data() != NULL) {
272 ResourceMark rm;
273 tty->print_cr("[TraceClassLoaderData] Adding k: " PTR_FORMAT " %s to CLD: "
274 PTR_FORMAT " loader: " PTR_FORMAT " %s",
275 p2i(k),
276 k->external_name(),
277 p2i(k->class_loader_data()),
278 p2i((void *)k->class_loader()),
279 loader_name());
280 }
281 }
282
283 // This is called by InstanceKlass::deallocate_contents() to remove the
284 // scratch_class for redefine classes. We need a lock because there it may not
285 // be called at a safepoint if there's an error.
286 void ClassLoaderData::remove_class(Klass* scratch_class) {
287 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
288 Klass* prev = NULL;
289 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
290 if (k == scratch_class) {
291 if (prev == NULL) {
292 _klasses = k->next_link();
293 } else {
294 Klass* next = k->next_link();
295 prev->set_next_link(next);
296 }
297 return;
298 }
299 prev = k;
300 assert(k != k->next_link(), "no loops!");
301 }
302 ShouldNotReachHere(); // should have found this class!!
303 }
304
305 void ClassLoaderData::unload() {
306 _unloading = true;
307
308 // Tell serviceability tools these classes are unloading
309 classes_do(InstanceKlass::notify_unload_class);
310
311 if (TraceClassLoaderData) {
312 ResourceMark rm;
313 tty->print("[ClassLoaderData: unload loader data " INTPTR_FORMAT, p2i(this));
314 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
315 loader_name());
316 if (is_anonymous()) {
317 tty->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
318 }
319 tty->print_cr("]");
320 }
321 }
322
323 oop ClassLoaderData::keep_alive_object() const {
324 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
325 return is_anonymous() ? _klasses->java_mirror() : class_loader();
326 }
327
328 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
329 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
330 || is_alive_closure->do_object_b(keep_alive_object());
331
332 return alive;
333 }
334
335
336 ClassLoaderData::~ClassLoaderData() {
337 // Release C heap structures for all the classes.
338 classes_do(InstanceKlass::release_C_heap_structures);
339
340 Metaspace *m = _metaspace;
341 if (m != NULL) {
342 _metaspace = NULL;
343 // release the metaspace
344 delete m;
345 // release the handles
346 if (_handles != NULL) {
347 JNIHandleBlock::release_block(_handles);
348 _handles = NULL;
349 }
350 }
351
352 // Clear all the JNI handles for methods
353 // These aren't deallocated and are going to look like a leak, but that's
354 // needed because we can't really get rid of jmethodIDs because we don't
355 // know when native code is going to stop using them. The spec says that
356 // they're "invalid" but existing programs likely rely on their being
357 // NULL after class unloading.
358 if (_jmethod_ids != NULL) {
359 Method::clear_jmethod_ids(this);
360 }
361 // Delete lock
362 delete _metaspace_lock;
363
364 // Delete free list
365 if (_deallocate_list != NULL) {
366 delete _deallocate_list;
367 }
368 }
369
370 /**
371 * Returns true if this class loader data is for the extension class loader.
372 */
373 bool ClassLoaderData::is_ext_class_loader_data() const {
374 return SystemDictionary::is_ext_class_loader(class_loader());
375 }
376
377 Metaspace* ClassLoaderData::metaspace_non_null() {
378 assert(!DumpSharedSpaces, "wrong metaspace!");
379 // If the metaspace has not been allocated, create a new one. Might want
380 // to create smaller arena for Reflection class loaders also.
381 // The reason for the delayed allocation is because some class loaders are
382 // simply for delegating with no metadata of their own.
383 if (_metaspace == NULL) {
384 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
385 // Check again if metaspace has been allocated while we were getting this lock.
386 if (_metaspace != NULL) {
387 return _metaspace;
388 }
389 if (this == the_null_class_loader_data()) {
390 assert (class_loader() == NULL, "Must be");
391 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
392 } else if (is_anonymous()) {
393 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
394 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
395 }
396 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
397 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
398 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
399 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
400 }
401 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
402 } else {
403 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
404 }
405 }
406 return _metaspace;
407 }
408
409 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
410 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
411
412 jobject ClassLoaderData::add_handle(Handle h) {
413 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
414 if (handles() == NULL) {
415 set_handles(JNIHandleBlock::allocate_block());
416 }
417 return handles()->allocate_handle(h());
418 }
419
420 // Add this metadata pointer to be freed when it's safe. This is only during
421 // class unloading because Handles might point to this metadata field.
422 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
423 // Metadata in shared region isn't deleted.
424 if (!m->is_shared()) {
425 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
426 if (_deallocate_list == NULL) {
427 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
428 }
429 _deallocate_list->append_if_missing(m);
430 }
431 }
432
433 // Deallocate free metadata on the free list. How useful the PermGen was!
434 void ClassLoaderData::free_deallocate_list() {
435 // Don't need lock, at safepoint
436 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
437 if (_deallocate_list == NULL) {
438 return;
439 }
440 // Go backwards because this removes entries that are freed.
441 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
442 Metadata* m = _deallocate_list->at(i);
443 if (!m->on_stack()) {
444 _deallocate_list->remove_at(i);
445 // There are only three types of metadata that we deallocate directly.
446 // Cast them so they can be used by the template function.
447 if (m->is_method()) {
448 MetadataFactory::free_metadata(this, (Method*)m);
449 } else if (m->is_constantPool()) {
450 MetadataFactory::free_metadata(this, (ConstantPool*)m);
451 } else if (m->is_klass()) {
452 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
453 } else {
454 ShouldNotReachHere();
455 }
456 }
457 }
458 }
459
460 // These anonymous class loaders are to contain classes used for JSR292
461 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
462 // Add a new class loader data to the graph.
463 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL);
464 }
465
466 const char* ClassLoaderData::loader_name() {
467 // Handles null class loader
468 return SystemDictionary::loader_name(class_loader());
469 }
470
471 #ifndef PRODUCT
472 // Define to dump klasses
473 #undef CLD_DUMP_KLASSES
474
475 void ClassLoaderData::dump(outputStream * const out) {
476 ResourceMark rm;
477 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {",
478 p2i(this), p2i((void *)class_loader()),
479 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
480 if (claimed()) out->print(" claimed ");
481 if (is_unloading()) out->print(" unloading ");
482 out->print(" handles " INTPTR_FORMAT, p2i(handles()));
483 out->cr();
484 if (metaspace_or_null() != NULL) {
485 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
486 metaspace_or_null()->dump(out);
487 } else {
488 out->print_cr("metaspace: NULL");
489 }
490
491 #ifdef CLD_DUMP_KLASSES
492 if (Verbose) {
493 ResourceMark rm;
494 Klass* k = _klasses;
495 while (k != NULL) {
496 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
497 k->has_modified_oops(), k->has_accumulated_modified_oops());
498 assert(k != k->next_link(), "no loops!");
499 k = k->next_link();
500 }
501 }
502 #endif // CLD_DUMP_KLASSES
503 #undef CLD_DUMP_KLASSES
504 if (_jmethod_ids != NULL) {
505 Method::print_jmethod_ids(this, out);
506 }
507 out->print_cr("}");
508 }
509 #endif // PRODUCT
510
511 void ClassLoaderData::verify() {
512 oop cl = class_loader();
513
514 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
515 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
516
517 // Verify the integrity of the allocated space.
518 if (metaspace_or_null() != NULL) {
519 metaspace_or_null()->verify();
520 }
521
522 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
523 guarantee(k->class_loader_data() == this, "Must be the same");
524 k->verify();
525 assert(k != k->next_link(), "no loops!");
526 }
527 }
528
529 bool ClassLoaderData::contains_klass(Klass* klass) {
530 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
531 if (k == klass) return true;
532 }
533 return false;
534 }
535
536
537 // GC root of class loader data created.
538 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
539 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
540 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
541 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
542
543 bool ClassLoaderDataGraph::_should_purge = false;
544
545 // Add a new class loader data node to the list. Assign the newly created
546 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
547 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
548 // We need to allocate all the oops for the ClassLoaderData before allocating the
549 // actual ClassLoaderData object.
550 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
551
552 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
553 // ClassLoaderData in the graph since the CLD
554 // contains unhandled oops
555
556 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
557
558
559 if (!is_anonymous) {
560 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(oopDesc::bs()->write_barrier(loader()));
561 // First, Atomically set it
562 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
563 if (old != NULL) {
564 delete cld;
565 // Returns the data.
566 return old;
567 }
568 }
569
570 // We won the race, and therefore the task of adding the data to the list of
571 // class loader data
572 ClassLoaderData** list_head = &_head;
573 ClassLoaderData* next = _head;
574
575 do {
576 cld->set_next(next);
577 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
578 if (exchanged == next) {
579 if (TraceClassLoaderData) {
580 ResourceMark rm;
581 tty->print("[ClassLoaderData: ");
582 tty->print("create class loader data " INTPTR_FORMAT, p2i(cld));
583 tty->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
584 cld->loader_name());
585 tty->print_cr("]");
586 }
587 return cld;
588 }
589 next = exchanged;
590 } while (true);
591
592 }
593
594 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
595 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
596 cld->oops_do(f, klass_closure, must_claim);
597 }
598 }
599
600 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
601 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
602 if (cld->keep_alive()) {
603 cld->oops_do(f, klass_closure, must_claim);
604 }
605 }
606 }
607
608 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
609 if (ClassUnloading) {
610 keep_alive_oops_do(f, klass_closure, must_claim);
611 } else {
612 oops_do(f, klass_closure, must_claim);
613 }
614 }
615
616 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
617 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
618 cl->do_cld(cld);
619 }
620 }
621
622 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
623 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
624 CLDClosure* closure = cld->keep_alive() ? strong : weak;
625 if (closure != NULL) {
626 closure->do_cld(cld);
627 }
628 }
629 }
630
631 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
632 roots_cld_do(cl, NULL);
633 }
634
635 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
636 if (ClassUnloading) {
637 keep_alive_cld_do(cl);
638 } else {
639 cld_do(cl);
640 }
641 }
642
643 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
644 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
645 cld->classes_do(klass_closure);
646 }
647 }
648
649 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
650 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
651 cld->classes_do(f);
652 }
653 }
654
655 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
656 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
657 cld->loaded_classes_do(klass_closure);
658 }
659 }
660
661 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
662 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
663 // Only walk the head until any clds not purged from prior unloading
664 // (CMS doesn't purge right away).
665 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
666 cld->classes_do(f);
667 }
668 }
669
670 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
671 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
672
673 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
674
675 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
676 ClassLoaderData* curr = _head;
677 while (curr != _saved_head) {
678 if (!curr->claimed()) {
679 array->push(curr);
680
681 if (TraceClassLoaderData) {
682 tty->print("[ClassLoaderData] found new CLD: ");
683 curr->print_value_on(tty);
684 tty->cr();
685 }
686 }
687
688 curr = curr->_next;
689 }
690
691 return array;
692 }
693
694 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
695 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
696 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
697 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
698 return true;
699 }
700 }
701 return false;
702 }
703
704 #ifndef PRODUCT
705 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
706 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
707 if (loader_data == data) {
708 return true;
709 }
710 }
711
712 return false;
713 }
714 #endif // PRODUCT
715
716
717 // Move class loader data from main list to the unloaded list for unloading
718 // and deallocation later.
719 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure, bool clean_alive) {
720 ClassLoaderData* data = _head;
721 ClassLoaderData* prev = NULL;
722 bool seen_dead_loader = false;
723
724 // Save previous _unloading pointer for CMS which may add to unloading list before
725 // purging and we don't want to rewalk the previously unloaded class loader data.
726 _saved_unloading = _unloading;
727
728 while (data != NULL) {
729 if (data->is_alive(is_alive_closure)) {
730 prev = data;
731 data = data->next();
732 continue;
733 }
734 seen_dead_loader = true;
735 ClassLoaderData* dead = data;
736 dead->unload();
737 data = data->next();
738 // Remove from loader list.
739 // This class loader data will no longer be found
740 // in the ClassLoaderDataGraph.
741 if (prev != NULL) {
742 prev->set_next(data);
743 } else {
744 assert(dead == _head, "sanity check");
745 _head = data;
746 }
747 dead->set_next(_unloading);
748 _unloading = dead;
749 }
750
751 if (clean_alive) {
752 // Clean previous versions and the deallocate list.
753 ClassLoaderDataGraph::clean_metaspaces();
754 }
755
756 if (seen_dead_loader) {
757 post_class_unload_events();
758 }
759
760 return seen_dead_loader;
761 }
762
763 void ClassLoaderDataGraph::clean_metaspaces() {
764 // mark metadata seen on the stack and code cache so we can delete unneeded entries.
765 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
766 MetadataOnStackMark md_on_stack(has_redefined_a_class);
767
768 if (has_redefined_a_class) {
769 // purge_previous_versions also cleans weak method links. Because
770 // one method's MDO can reference another method from another
771 // class loader, we need to first clean weak method links for all
772 // class loaders here. Below, we can then free redefined methods
773 // for all class loaders.
774 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
775 data->classes_do(InstanceKlass::purge_previous_versions);
776 }
777 }
778
779 // Need to purge the previous version before deallocating.
780 free_deallocate_lists();
781 }
782
783 void ClassLoaderDataGraph::purge() {
784 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
785 ClassLoaderData* list = _unloading;
786 _unloading = NULL;
787 ClassLoaderData* next = list;
788 while (next != NULL) {
789 ClassLoaderData* purge_me = next;
790 next = purge_me->next();
791 delete purge_me;
792 }
793 Metaspace::purge();
794 }
795
796 void ClassLoaderDataGraph::post_class_unload_events(void) {
797 #if INCLUDE_TRACE
798 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
799 if (Tracing::enabled()) {
800 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
801 assert(_unloading != NULL, "need class loader data unload list!");
802 _class_unload_time = Ticks::now();
803 classes_unloading_do(&class_unload_event);
804 }
805 Tracing::on_unloading_classes();
806 }
807 #endif
808 }
809
810 void ClassLoaderDataGraph::free_deallocate_lists() {
811 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
812 // We need to keep this data until InstanceKlass::purge_previous_version has been
813 // called on all alive classes. See the comment in ClassLoaderDataGraph::clean_metaspaces.
814 cld->free_deallocate_list();
815 }
816
817 // In some rare cases items added to the unloading list will not be freed elsewhere.
818 // To keep it simple, walk the _unloading list also.
819 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
820 cld->free_deallocate_list();
821 }
822 }
823
824 // CDS support
825
826 // Global metaspaces for writing information to the shared archive. When
827 // application CDS is supported, we may need one per metaspace, so this
828 // sort of looks like it.
829 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
830 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
831 static bool _shared_metaspaces_initialized = false;
832
833 // Initialize shared metaspaces (change to call from somewhere not lazily)
834 void ClassLoaderData::initialize_shared_metaspaces() {
835 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
836 assert(this == ClassLoaderData::the_null_class_loader_data(),
837 "only supported for null loader data for now");
838 assert (!_shared_metaspaces_initialized, "only initialize once");
839 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
840 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
841 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
842 _shared_metaspaces_initialized = true;
843 }
844
845 Metaspace* ClassLoaderData::ro_metaspace() {
846 assert(_ro_metaspace != NULL, "should already be initialized");
847 return _ro_metaspace;
848 }
849
850 Metaspace* ClassLoaderData::rw_metaspace() {
851 assert(_rw_metaspace != NULL, "should already be initialized");
852 return _rw_metaspace;
853 }
854
855 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
856 : _next_klass(NULL) {
857 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
858 Klass* klass = NULL;
859
860 // Find the first klass in the CLDG.
861 while (cld != NULL) {
862 klass = cld->_klasses;
863 if (klass != NULL) {
864 _next_klass = klass;
865 return;
866 }
867 cld = cld->next();
868 }
869 }
870
871 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
872 Klass* next = klass->next_link();
873 if (next != NULL) {
874 return next;
875 }
876
877 // No more klasses in the current CLD. Time to find a new CLD.
878 ClassLoaderData* cld = klass->class_loader_data();
879 while (next == NULL) {
880 cld = cld->next();
881 if (cld == NULL) {
882 break;
883 }
884 next = cld->_klasses;
885 }
886
887 return next;
888 }
889
890 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
891 Klass* head = _next_klass;
892
893 while (head != NULL) {
894 Klass* next = next_klass_in_cldg(head);
895
896 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
897
898 if (old_head == head) {
899 return head; // Won the CAS.
900 }
901
902 head = old_head;
903 }
904
905 // Nothing more for the iterator to hand out.
906 assert(head == NULL, err_msg("head is " PTR_FORMAT ", expected not null:", p2i(head)));
907 return NULL;
908 }
909
910 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
911 _data = ClassLoaderDataGraph::_head;
912 }
913
914 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
915
916 #ifndef PRODUCT
917 // callable from debugger
918 extern "C" int print_loader_data_graph() {
919 ClassLoaderDataGraph::dump_on(tty);
920 return 0;
921 }
922
923 void ClassLoaderDataGraph::verify() {
924 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
925 data->verify();
926 }
927 }
928
929 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
930 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
931 data->dump(out);
932 }
933 MetaspaceAux::dump(out);
934 }
935 #endif // PRODUCT
936
937 void ClassLoaderData::print_value_on(outputStream* out) const {
938 if (class_loader() == NULL) {
939 out->print("NULL class_loader");
940 } else {
941 out->print("class loader " INTPTR_FORMAT, p2i(this));
942 class_loader()->print_value_on(out);
943 }
944 }
945
946 #if INCLUDE_TRACE
947
948 Ticks ClassLoaderDataGraph::_class_unload_time;
949
950 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
951
952 // post class unload event
953 EventClassUnload event(UNTIMED);
954 event.set_endtime(_class_unload_time);
955 event.set_unloadedClass(k);
956 oop defining_class_loader = k->class_loader();
957 event.set_definingClassLoader(defining_class_loader != NULL ?
958 defining_class_loader->klass() : (Klass*)NULL);
959 event.commit();
960 }
961
962
963 #endif // INCLUDE_TRACE