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