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