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