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
69 #if INCLUDE_TRACE
70 #include "trace/tracing.hpp"
71 #endif
72
73 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
74
75 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
76 _class_loader(h_class_loader()),
77 _is_anonymous(is_anonymous),
78 // An anonymous class loader data doesn't have anything to keep
79 // it from being unloaded during parsing of the anonymous class.
80 // The null-class-loader should always be kept alive.
81 _keep_alive(is_anonymous || h_class_loader.is_null()),
82 _metaspace(NULL), _unloading(false), _klasses(NULL),
83 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
84 _next(NULL), _dependencies(dependencies),
85 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true)) {
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 assert(!alive || claimed(), "must be claimed");
345 return alive;
346 }
347
348
349 ClassLoaderData::~ClassLoaderData() {
350 // Release C heap structures for all the classes.
351 classes_do(InstanceKlass::release_C_heap_structures);
352
353 Metaspace *m = _metaspace;
354 if (m != NULL) {
355 _metaspace = NULL;
356 // release the metaspace
357 delete m;
358 // release the handles
359 if (_handles != NULL) {
360 JNIHandleBlock::release_block(_handles);
361 _handles = NULL;
362 }
363 }
364
365 // Clear all the JNI handles for methods
366 // These aren't deallocated and are going to look like a leak, but that's
367 // needed because we can't really get rid of jmethodIDs because we don't
368 // know when native code is going to stop using them. The spec says that
369 // they're "invalid" but existing programs likely rely on their being
370 // NULL after class unloading.
371 if (_jmethod_ids != NULL) {
372 Method::clear_jmethod_ids(this);
373 }
374 // Delete lock
375 delete _metaspace_lock;
376
377 // Delete free list
378 if (_deallocate_list != NULL) {
379 delete _deallocate_list;
380 }
381 }
382
383 /**
384 * Returns true if this class loader data is for the extension class loader.
385 */
386 bool ClassLoaderData::is_ext_class_loader_data() const {
387 return SystemDictionary::is_ext_class_loader(class_loader());
388 }
389
390 Metaspace* ClassLoaderData::metaspace_non_null() {
391 assert(!DumpSharedSpaces, "wrong metaspace!");
392 // If the metaspace has not been allocated, create a new one. Might want
393 // to create smaller arena for Reflection class loaders also.
394 // The reason for the delayed allocation is because some class loaders are
395 // simply for delegating with no metadata of their own.
396 if (_metaspace == NULL) {
397 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
398 // Check again if metaspace has been allocated while we were getting this lock.
399 if (_metaspace != NULL) {
400 return _metaspace;
401 }
402 if (this == the_null_class_loader_data()) {
403 assert (class_loader() == NULL, "Must be");
404 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
405 } else if (is_anonymous()) {
406 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
407 tty->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
408 }
409 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
410 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
411 if (TraceClassLoaderData && Verbose && class_loader() != NULL) {
412 tty->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
413 }
414 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
415 } else {
416 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
417 }
418 }
419 return _metaspace;
420 }
421
422 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
423 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
424
425 jobject ClassLoaderData::add_handle(Handle h) {
426 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
427 if (handles() == NULL) {
428 set_handles(JNIHandleBlock::allocate_block());
429 }
430 return handles()->allocate_handle(h());
431 }
432
433 // Add this metadata pointer to be freed when it's safe. This is only during
434 // class unloading because Handles might point to this metadata field.
435 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
436 // Metadata in shared region isn't deleted.
437 if (!m->is_shared()) {
438 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
439 if (_deallocate_list == NULL) {
440 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
441 }
442 _deallocate_list->append_if_missing(m);
443 }
444 }
445
446 // Deallocate free metadata on the free list. How useful the PermGen was!
447 void ClassLoaderData::free_deallocate_list() {
448 // Don't need lock, at safepoint
449 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
450 if (_deallocate_list == NULL) {
451 return;
452 }
453 // Go backwards because this removes entries that are freed.
454 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
455 Metadata* m = _deallocate_list->at(i);
456 if (!m->on_stack()) {
457 _deallocate_list->remove_at(i);
458 // There are only three types of metadata that we deallocate directly.
459 // Cast them so they can be used by the template function.
460 if (m->is_method()) {
461 MetadataFactory::free_metadata(this, (Method*)m);
462 } else if (m->is_constantPool()) {
463 MetadataFactory::free_metadata(this, (ConstantPool*)m);
464 } else if (m->is_klass()) {
465 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
466 } else {
467 ShouldNotReachHere();
468 }
469 }
470 }
471 }
472
473 // These anonymous class loaders are to contain classes used for JSR292
474 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
475 // Add a new class loader data to the graph.
476 return ClassLoaderDataGraph::add(loader, true, CHECK_NULL);
477 }
478
479 const char* ClassLoaderData::loader_name() {
480 // Handles null class loader
481 return SystemDictionary::loader_name(class_loader());
482 }
483
484 #ifndef PRODUCT
485 // Define to dump klasses
486 #undef CLD_DUMP_KLASSES
487
488 void ClassLoaderData::dump(outputStream * const out) {
489 ResourceMark rm;
490 out->print("ClassLoaderData CLD: "PTR_FORMAT", loader: "PTR_FORMAT", loader_klass: "PTR_FORMAT" %s {",
491 p2i(this), p2i((void *)class_loader()),
492 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
493 if (claimed()) out->print(" claimed ");
494 if (is_unloading()) out->print(" unloading ");
495 out->print(" handles " INTPTR_FORMAT, p2i(handles()));
496 out->cr();
497 if (metaspace_or_null() != NULL) {
498 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
499 metaspace_or_null()->dump(out);
500 } else {
501 out->print_cr("metaspace: NULL");
502 }
503
504 #ifdef CLD_DUMP_KLASSES
505 if (Verbose) {
506 ResourceMark rm;
507 Klass* k = _klasses;
508 while (k != NULL) {
509 out->print_cr("klass "PTR_FORMAT", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
510 k->has_modified_oops(), k->has_accumulated_modified_oops());
511 assert(k != k->next_link(), "no loops!");
512 k = k->next_link();
513 }
514 }
515 #endif // CLD_DUMP_KLASSES
516 #undef CLD_DUMP_KLASSES
517 if (_jmethod_ids != NULL) {
518 Method::print_jmethod_ids(this, out);
519 }
520 out->print_cr("}");
521 }
522 #endif // PRODUCT
523
524 void ClassLoaderData::verify() {
525 oop cl = class_loader();
526
527 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
528 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
529
530 // Verify the integrity of the allocated space.
531 if (metaspace_or_null() != NULL) {
532 metaspace_or_null()->verify();
533 }
534
535 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
536 guarantee(k->class_loader_data() == this, "Must be the same");
537 k->verify();
538 assert(k != k->next_link(), "no loops!");
539 }
540 }
541
542 bool ClassLoaderData::contains_klass(Klass* klass) {
543 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
544 if (k == klass) return true;
545 }
546 return false;
547 }
548
549
550 // GC root of class loader data created.
551 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
552 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
553 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
554
555 bool ClassLoaderDataGraph::_should_purge = 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 ClassLoaderDataGraph::keep_alive_oops_do(f, klass_closure, must_claim);
623 } else {
624 ClassLoaderDataGraph::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::classes_do(KlassClosure* klass_closure) {
635 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
636 cld->classes_do(klass_closure);
637 }
638 }
639
640 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
641 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
642 cld->classes_do(f);
643 }
644 }
645
646 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
647 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
648 cld->methods_do(f);
649 }
650 }
651
652 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
653 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
654 cld->loaded_classes_do(klass_closure);
655 }
656 }
657
658 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
659 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
660 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
661 cld->classes_do(f);
662 }
663 }
664
665 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
666 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
667
668 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
669
670 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
671 ClassLoaderData* curr = _head;
672 while (curr != _saved_head) {
673 if (!curr->claimed()) {
674 array->push(curr);
675
676 if (TraceClassLoaderData) {
677 tty->print("[ClassLoaderData] found new CLD: ");
678 curr->print_value_on(tty);
679 tty->cr();
680 }
681 }
682
683 curr = curr->_next;
684 }
685
686 return array;
687 }
688
689 #ifndef PRODUCT
690 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
691 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
692 if (loader_data == data) {
693 return true;
694 }
695 }
696
697 return false;
698 }
699 #endif // PRODUCT
700
701
702 // Move class loader data from main list to the unloaded list for unloading
703 // and deallocation later.
704 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure) {
705 ClassLoaderData* data = _head;
706 ClassLoaderData* prev = NULL;
707 bool seen_dead_loader = false;
708 // mark metadata seen on the stack and code cache so we can delete
709 // unneeded entries.
710 bool has_redefined_a_class = JvmtiExport::has_redefined_a_class();
711 MetadataOnStackMark md_on_stack;
712 while (data != NULL) {
713 if (data->is_alive(is_alive_closure)) {
714 if (has_redefined_a_class) {
715 data->classes_do(InstanceKlass::purge_previous_versions);
716 }
717 data->free_deallocate_list();
718 prev = data;
719 data = data->next();
720 continue;
721 }
722 seen_dead_loader = true;
723 ClassLoaderData* dead = data;
724 dead->unload();
725 data = data->next();
726 // Remove from loader list.
727 // This class loader data will no longer be found
728 // in the ClassLoaderDataGraph.
729 if (prev != NULL) {
730 prev->set_next(data);
731 } else {
732 assert(dead == _head, "sanity check");
733 _head = data;
734 }
735 dead->set_next(_unloading);
736 _unloading = dead;
737 }
738
739 if (seen_dead_loader) {
740 post_class_unload_events();
741 }
742
743 return seen_dead_loader;
744 }
745
746 void ClassLoaderDataGraph::purge() {
747 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
748 ClassLoaderData* list = _unloading;
749 _unloading = NULL;
750 ClassLoaderData* next = list;
751 while (next != NULL) {
752 ClassLoaderData* purge_me = next;
753 next = purge_me->next();
754 delete purge_me;
755 }
756 Metaspace::purge();
757 }
758
759 void ClassLoaderDataGraph::post_class_unload_events(void) {
760 #if INCLUDE_TRACE
761 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
762 if (Tracing::enabled()) {
763 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
764 assert(_unloading != NULL, "need class loader data unload list!");
765 _class_unload_time = Ticks::now();
766 classes_unloading_do(&class_unload_event);
767 }
768 Tracing::on_unloading_classes();
769 }
770 #endif
771 }
772
773 // CDS support
774
775 // Global metaspaces for writing information to the shared archive. When
776 // application CDS is supported, we may need one per metaspace, so this
777 // sort of looks like it.
778 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
779 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
780 static bool _shared_metaspaces_initialized = false;
781
782 // Initialize shared metaspaces (change to call from somewhere not lazily)
783 void ClassLoaderData::initialize_shared_metaspaces() {
784 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
785 assert(this == ClassLoaderData::the_null_class_loader_data(),
786 "only supported for null loader data for now");
787 assert (!_shared_metaspaces_initialized, "only initialize once");
788 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
789 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
790 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
791 _shared_metaspaces_initialized = true;
792 }
793
794 Metaspace* ClassLoaderData::ro_metaspace() {
795 assert(_ro_metaspace != NULL, "should already be initialized");
796 return _ro_metaspace;
797 }
798
799 Metaspace* ClassLoaderData::rw_metaspace() {
800 assert(_rw_metaspace != NULL, "should already be initialized");
801 return _rw_metaspace;
802 }
803
804
805 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
806 _data = ClassLoaderDataGraph::_head;
807 }
808
809 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
810
811 #ifndef PRODUCT
812 // callable from debugger
813 extern "C" int print_loader_data_graph() {
814 ClassLoaderDataGraph::dump_on(tty);
815 return 0;
816 }
817
818 void ClassLoaderDataGraph::verify() {
819 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
820 data->verify();
821 }
822 }
823
824 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
825 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
826 data->dump(out);
827 }
828 MetaspaceAux::dump(out);
829 }
830 #endif // PRODUCT
831
832 void ClassLoaderData::print_value_on(outputStream* out) const {
833 if (class_loader() == NULL) {
834 out->print("NULL class_loader");
835 } else {
836 out->print("class loader " INTPTR_FORMAT, p2i(this));
837 class_loader()->print_value_on(out);
838 }
839 }
840
841 #if INCLUDE_TRACE
842
843 Ticks ClassLoaderDataGraph::_class_unload_time;
844
845 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
846
847 // post class unload event
848 EventClassUnload event(UNTIMED);
849 event.set_endtime(_class_unload_time);
850 event.set_unloadedClass(k);
851 oop defining_class_loader = k->class_loader();
852 event.set_definingClassLoader(defining_class_loader != NULL ?
853 defining_class_loader->klass() : (Klass*)NULL);
854 event.commit();
855 }
856
857 #endif /* INCLUDE_TRACE */