1 /*
2 * Copyright (c) 2012, 2016, 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 "gc/shared/gcLocker.hpp"
57 #include "logging/log.hpp"
58 #include "memory/metadataFactory.hpp"
59 #include "memory/metaspaceShared.hpp"
60 #include "memory/oopFactory.hpp"
61 #include "memory/resourceArea.hpp"
62 #include "oops/objArrayOop.inline.hpp"
63 #include "oops/oop.inline.hpp"
64 #include "runtime/atomic.inline.hpp"
65 #include "runtime/javaCalls.hpp"
66 #include "runtime/jniHandles.hpp"
67 #include "runtime/mutex.hpp"
68 #include "runtime/safepoint.hpp"
69 #include "runtime/synchronizer.hpp"
70 #include "utilities/growableArray.hpp"
71 #include "utilities/macros.hpp"
72 #include "utilities/ostream.hpp"
73 #if INCLUDE_TRACE
74 #include "trace/tracing.hpp"
75 #endif
76
77 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
78
79 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
80 _class_loader(h_class_loader()),
81 _is_anonymous(is_anonymous),
82 // An anonymous class loader data doesn't have anything to keep
83 // it from being unloaded during parsing of the anonymous class.
84 // The null-class-loader should always be kept alive.
85 _keep_alive(is_anonymous || h_class_loader.is_null()),
86 _metaspace(NULL), _unloading(false), _klasses(NULL),
87 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
88 _next(NULL), _dependencies(dependencies), _shared_class_loader_id(-1),
89 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
90 Monitor::_safepoint_check_never)) {
91 // empty
92 }
93
94 void ClassLoaderData::init_dependencies(TRAPS) {
95 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
96 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
97 _dependencies.init(CHECK);
98 }
99
100 void ClassLoaderData::Dependencies::init(TRAPS) {
101 // Create empty dependencies array to add to. CMS requires this to be
102 // an oop so that it can track additions via card marks. We think.
103 _list_head = oopFactory::new_objectArray(2, CHECK);
104 }
105
106 bool ClassLoaderData::claim() {
107 if (_claimed == 1) {
108 return false;
109 }
110
111 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
112 }
113
114 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
115 if (must_claim && !claim()) {
116 return;
117 }
118
119 f->do_oop(&_class_loader);
120 _dependencies.oops_do(f);
121 _handles->oops_do(f);
122 if (klass_closure != NULL) {
123 classes_do(klass_closure);
124 }
125 }
126
127 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
128 f->do_oop((oop*)&_list_head);
129 }
130
131 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
132 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
133 klass_closure->do_klass(k);
134 assert(k != k->next_link(), "no loops!");
135 }
136 }
137
138 void ClassLoaderData::classes_do(void f(Klass * const)) {
139 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
140 f(k);
141 }
142 }
143
144 void ClassLoaderData::methods_do(void f(Method*)) {
145 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
146 if (k->is_instance_klass()) {
147 InstanceKlass::cast(k)->methods_do(f);
148 }
149 }
150 }
151
152 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
153 // Lock to avoid classes being modified/added/removed during iteration
154 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
155 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
156 // Do not filter ArrayKlass oops here...
157 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
158 klass_closure->do_klass(k);
159 }
160 }
161 }
162
163 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
164 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
165 if (k->is_instance_klass()) {
166 f(InstanceKlass::cast(k));
167 }
168 assert(k != k->next_link(), "no loops!");
169 }
170 }
171
172 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
173 assert(k != NULL, "invariant");
174
175 ClassLoaderData * const from_cld = this;
176 ClassLoaderData * const to_cld = k->class_loader_data();
177
178 // Dependency to the null class loader data doesn't need to be recorded
179 // because the null class loader data never goes away.
180 if (to_cld->is_the_null_class_loader_data()) {
181 return;
182 }
183
184 oop to;
185 if (to_cld->is_anonymous()) {
186 // Anonymous class dependencies are through the mirror.
187 to = k->java_mirror();
188 } else {
189 to = to_cld->class_loader();
190
191 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
192 // we still have to add it. The class_loader won't keep from_cld alive.
193 if (!from_cld->is_anonymous()) {
194 // Check that this dependency isn't from the same or parent class_loader
195 oop from = from_cld->class_loader();
196
197 oop curr = from;
198 while (curr != NULL) {
199 if (curr == to) {
200 return; // this class loader is in the parent list, no need to add it.
201 }
202 curr = java_lang_ClassLoader::parent(curr);
203 }
204 }
205 }
206
207 // It's a dependency we won't find through GC, add it. This is relatively rare
208 // Must handle over GC point.
209 Handle dependency(THREAD, to);
210 from_cld->_dependencies.add(dependency, CHECK);
211 }
212
213
214 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
215 // Check first if this dependency is already in the list.
216 // Save a pointer to the last to add to under the lock.
217 objArrayOop ok = _list_head;
218 objArrayOop last = NULL;
219 while (ok != NULL) {
220 last = ok;
221 if (ok->obj_at(0) == dependency()) {
222 // Don't need to add it
223 return;
224 }
225 ok = (objArrayOop)ok->obj_at(1);
226 }
227
228 // Must handle over GC points
229 assert (last != NULL, "dependencies should be initialized");
230 objArrayHandle last_handle(THREAD, last);
231
232 // Create a new dependency node with fields for (class_loader or mirror, next)
233 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
234 deps->obj_at_put(0, dependency());
235
236 // Must handle over GC points
237 objArrayHandle new_dependency(THREAD, deps);
238
239 // Add the dependency under lock
240 locked_add(last_handle, new_dependency, THREAD);
241 }
242
243 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
244 objArrayHandle new_dependency,
245 Thread* THREAD) {
246
247 // Have to lock and put the new dependency on the end of the dependency
248 // array so the card mark for CMS sees that this dependency is new.
249 // Can probably do this lock free with some effort.
250 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
251
252 oop loader_or_mirror = new_dependency->obj_at(0);
253
254 // Since the dependencies are only added, add to the end.
255 objArrayOop end = last_handle();
256 objArrayOop last = NULL;
257 while (end != NULL) {
258 last = end;
259 // check again if another thread added it to the end.
260 if (end->obj_at(0) == loader_or_mirror) {
261 // Don't need to add it
262 return;
263 }
264 end = (objArrayOop)end->obj_at(1);
265 }
266 assert (last != NULL, "dependencies should be initialized");
267 // fill in the first element with the oop in new_dependency.
268 if (last->obj_at(0) == NULL) {
269 last->obj_at_put(0, new_dependency->obj_at(0));
270 } else {
271 last->obj_at_put(1, new_dependency());
272 }
273 }
274
275 void ClassLoaderDataGraph::clear_claimed_marks() {
276 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
277 cld->clear_claimed();
278 }
279 }
280
281 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
282 {
283 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
284 Klass* old_value = _klasses;
285 k->set_next_link(old_value);
286 // Make sure linked class is stable, since the class list is walked without a lock
287 OrderAccess::storestore();
288 // link the new item into the list
289 _klasses = k;
290 }
291
292 if (publicize && k->class_loader_data() != NULL) {
293 ResourceMark rm;
294 log_trace(classloaderdata)("Adding k: " PTR_FORMAT " %s to CLD: "
295 PTR_FORMAT " loader: " PTR_FORMAT " %s",
296 p2i(k),
297 k->external_name(),
298 p2i(k->class_loader_data()),
299 p2i((void *)k->class_loader()),
300 loader_name());
301 }
302 }
303
304 // This is called by InstanceKlass::deallocate_contents() to remove the
305 // scratch_class for redefine classes. We need a lock because there it may not
306 // be called at a safepoint if there's an error.
307 void ClassLoaderData::remove_class(Klass* scratch_class) {
308 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
309 Klass* prev = NULL;
310 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
311 if (k == scratch_class) {
312 if (prev == NULL) {
313 _klasses = k->next_link();
314 } else {
315 Klass* next = k->next_link();
316 prev->set_next_link(next);
317 }
318 return;
319 }
320 prev = k;
321 assert(k != k->next_link(), "no loops!");
322 }
323 ShouldNotReachHere(); // should have found this class!!
324 }
325
326 void ClassLoaderData::unload() {
327 _unloading = true;
328
329 // Tell serviceability tools these classes are unloading
330 classes_do(InstanceKlass::notify_unload_class);
331
332 if (log_is_enabled(Debug, classloaderdata)) {
333 ResourceMark rm;
334 outputStream* log = LogHandle(classloaderdata)::debug_stream();
335 log->print(": unload loader data " INTPTR_FORMAT, p2i(this));
336 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)class_loader()),
337 loader_name());
338 if (is_anonymous()) {
339 log->print(" for anonymous class " INTPTR_FORMAT " ", p2i(_klasses));
340 }
341 log->cr();
342 }
343 }
344
345 oop ClassLoaderData::keep_alive_object() const {
346 assert(!keep_alive(), "Don't use with CLDs that are artificially kept alive");
347 return is_anonymous() ? _klasses->java_mirror() : class_loader();
348 }
349
350 bool ClassLoaderData::is_alive(BoolObjectClosure* is_alive_closure) const {
351 bool alive = keep_alive() // null class loader and incomplete anonymous klasses.
352 || is_alive_closure->do_object_b(keep_alive_object());
353
354 return alive;
355 }
356
357
358 ClassLoaderData::~ClassLoaderData() {
359 // Release C heap structures for all the classes.
360 classes_do(InstanceKlass::release_C_heap_structures);
361
362 Metaspace *m = _metaspace;
363 if (m != NULL) {
364 _metaspace = NULL;
365 // release the metaspace
366 delete m;
367 // release the handles
368 if (_handles != NULL) {
369 JNIHandleBlock::release_block(_handles);
370 _handles = NULL;
371 }
372 }
373
374 // Clear all the JNI handles for methods
375 // These aren't deallocated and are going to look like a leak, but that's
376 // needed because we can't really get rid of jmethodIDs because we don't
377 // know when native code is going to stop using them. The spec says that
378 // they're "invalid" but existing programs likely rely on their being
379 // NULL after class unloading.
380 if (_jmethod_ids != NULL) {
381 Method::clear_jmethod_ids(this);
382 }
383 // Delete lock
384 delete _metaspace_lock;
385
386 // Delete free list
387 if (_deallocate_list != NULL) {
388 delete _deallocate_list;
389 }
390 }
391
392 /**
393 * Returns true if this class loader data is for the extension class loader.
394 */
395 bool ClassLoaderData::is_ext_class_loader_data() const {
396 return SystemDictionary::is_ext_class_loader(class_loader());
397 }
398
399 Metaspace* ClassLoaderData::metaspace_non_null() {
400 assert(!DumpSharedSpaces, "wrong metaspace!");
401 // If the metaspace has not been allocated, create a new one. Might want
402 // to create smaller arena for Reflection class loaders also.
403 // The reason for the delayed allocation is because some class loaders are
404 // simply for delegating with no metadata of their own.
405 if (_metaspace == NULL) {
406 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
407 // Check again if metaspace has been allocated while we were getting this lock.
408 if (_metaspace != NULL) {
409 return _metaspace;
410 }
411 if (this == the_null_class_loader_data()) {
412 assert (class_loader() == NULL, "Must be");
413 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::BootMetaspaceType));
414 } else if (is_anonymous()) {
415 if (class_loader() != NULL) {
416 log_trace(classloaderdata)("is_anonymous: %s", class_loader()->klass()->internal_name());
417 }
418 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
419 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
420 if (class_loader() != NULL) {
421 log_trace(classloaderdata)("is_reflection: %s", class_loader()->klass()->internal_name());
422 }
423 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
424 } else {
425 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
426 }
427 }
428 return _metaspace;
429 }
430
431 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
432 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
433
434 jobject ClassLoaderData::add_handle(Handle h) {
435 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
436 if (handles() == NULL) {
437 set_handles(JNIHandleBlock::allocate_block());
438 }
439 return handles()->allocate_handle(h());
440 }
441
442 // Add this metadata pointer to be freed when it's safe. This is only during
443 // class unloading because Handles might point to this metadata field.
444 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
445 // Metadata in shared region isn't deleted.
446 if (!m->is_shared()) {
447 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
448 if (_deallocate_list == NULL) {
449 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
450 }
451 _deallocate_list->append_if_missing(m);
452 }
453 }
454
455 // Deallocate free metadata on the free list. How useful the PermGen was!
456 void ClassLoaderData::free_deallocate_list() {
457 // Don't need lock, at safepoint
458 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
459 if (_deallocate_list == NULL) {
460 return;
461 }
462 // Go backwards because this removes entries that are freed.
463 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
464 Metadata* m = _deallocate_list->at(i);
465 if (!m->on_stack()) {
466 _deallocate_list->remove_at(i);
467 // There are only three types of metadata that we deallocate directly.
468 // Cast them so they can be used by the template function.
469 if (m->is_method()) {
470 MetadataFactory::free_metadata(this, (Method*)m);
471 } else if (m->is_constantPool()) {
472 MetadataFactory::free_metadata(this, (ConstantPool*)m);
473 } else if (m->is_klass()) {
474 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
475 } else {
476 ShouldNotReachHere();
477 }
478 } else {
479 // Metadata is alive.
480 // If scratch_class is on stack then it shouldn't be on this list!
481 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
482 "scratch classes on this list should be dead");
483 // Also should assert that other metadata on the list was found in handles.
484 }
485 }
486 }
487
488 // These anonymous class loaders are to contain classes used for JSR292
489 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
490 // Add a new class loader data to the graph.
491 return ClassLoaderDataGraph::add(loader, true, THREAD);
492 }
493
494 const char* ClassLoaderData::loader_name() {
495 // Handles null class loader
496 return SystemDictionary::loader_name(class_loader());
497 }
498
499 #ifndef PRODUCT
500 // Define to dump klasses
501 #undef CLD_DUMP_KLASSES
502
503 void ClassLoaderData::dump(outputStream * const out) {
504 ResourceMark rm;
505 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
506 p2i(this), p2i((void *)class_loader()),
507 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
508 if (claimed()) out->print(" claimed ");
509 if (is_unloading()) out->print(" unloading ");
510 out->print(" handles " INTPTR_FORMAT, p2i(handles()));
511 out->cr();
512 if (metaspace_or_null() != NULL) {
513 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
514 metaspace_or_null()->dump(out);
515 } else {
516 out->print_cr("metaspace: NULL");
517 }
518
519 #ifdef CLD_DUMP_KLASSES
520 if (Verbose) {
521 ResourceMark rm;
522 Klass* k = _klasses;
523 while (k != NULL) {
524 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
525 k->has_modified_oops(), k->has_accumulated_modified_oops());
526 assert(k != k->next_link(), "no loops!");
527 k = k->next_link();
528 }
529 }
530 #endif // CLD_DUMP_KLASSES
531 #undef CLD_DUMP_KLASSES
532 if (_jmethod_ids != NULL) {
533 Method::print_jmethod_ids(this, out);
534 }
535 out->print_cr("}");
536 }
537 #endif // PRODUCT
538
539 void ClassLoaderData::verify() {
540 oop cl = class_loader();
541
542 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
543 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
544
545 // Verify the integrity of the allocated space.
546 if (metaspace_or_null() != NULL) {
547 metaspace_or_null()->verify();
548 }
549
550 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
551 guarantee(k->class_loader_data() == this, "Must be the same");
552 k->verify();
553 assert(k != k->next_link(), "no loops!");
554 }
555 }
556
557 bool ClassLoaderData::contains_klass(Klass* klass) {
558 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
559 if (k == klass) return true;
560 }
561 return false;
562 }
563
564
565 // GC root of class loader data created.
566 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
567 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
568 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
569 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
570
571 bool ClassLoaderDataGraph::_should_purge = false;
572 bool ClassLoaderDataGraph::_metaspace_oom = false;
573
574 // Add a new class loader data node to the list. Assign the newly created
575 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
576 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
577 // We need to allocate all the oops for the ClassLoaderData before allocating the
578 // actual ClassLoaderData object.
579 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
580
581 NoSafepointVerifier no_safepoints; // we mustn't GC until we've installed the
582 // ClassLoaderData in the graph since the CLD
583 // contains unhandled oops
584
585 ClassLoaderData* cld = new ClassLoaderData(loader, is_anonymous, dependencies);
586
587
588 if (!is_anonymous) {
589 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
590 // First, Atomically set it
591 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
592 if (old != NULL) {
593 delete cld;
594 // Returns the data.
595 return old;
596 }
597 }
598
599 // We won the race, and therefore the task of adding the data to the list of
600 // class loader data
601 ClassLoaderData** list_head = &_head;
602 ClassLoaderData* next = _head;
603
604 do {
605 cld->set_next(next);
606 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
607 if (exchanged == next) {
608 if (log_is_enabled(Debug, classloaderdata)) {
609 PauseNoSafepointVerifier pnsv(&no_safepoints); // Need safe points for JavaCalls::call_virtual
610 log_creation(loader, cld, CHECK_NULL);
611 }
612 return cld;
613 }
614 next = exchanged;
615 } while (true);
616 }
617
618 void ClassLoaderDataGraph::log_creation(Handle loader, ClassLoaderData* cld, TRAPS) {
619 Handle string;
620 if (loader.not_null()) {
621 // Include the result of loader.toString() in the output. This allows
622 // the user of the log to identify the class loader instance.
623 JavaValue result(T_OBJECT);
624 KlassHandle spec_klass(THREAD, SystemDictionary::ClassLoader_klass());
625 JavaCalls::call_virtual(&result,
626 loader,
627 spec_klass,
628 vmSymbols::toString_name(),
629 vmSymbols::void_string_signature(),
630 CHECK);
631 assert(result.get_type() == T_OBJECT, "just checking");
632 string = (oop)result.get_jobject();
633 }
634
635 ResourceMark rm;
636 outputStream* log = LogHandle(classloaderdata)::debug_stream();
637 log->print("create class loader data " INTPTR_FORMAT, p2i(cld));
638 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
639 cld->loader_name());
640
641 if (string.not_null()) {
642 log->print(": ");
643 java_lang_String::print(string(), log);
644 }
645 log->cr();
646 }
647
648
649 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
650 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
651 cld->oops_do(f, klass_closure, must_claim);
652 }
653 }
654
655 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
656 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
657 if (cld->keep_alive()) {
658 cld->oops_do(f, klass_closure, must_claim);
659 }
660 }
661 }
662
663 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
664 if (ClassUnloading) {
665 keep_alive_oops_do(f, klass_closure, must_claim);
666 } else {
667 oops_do(f, klass_closure, must_claim);
668 }
669 }
670
671 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
672 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
673 cl->do_cld(cld);
674 }
675 }
676
677 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
678 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
679 CLDClosure* closure = cld->keep_alive() ? strong : weak;
680 if (closure != NULL) {
681 closure->do_cld(cld);
682 }
683 }
684 }
685
686 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
687 roots_cld_do(cl, NULL);
688 }
689
690 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
691 if (ClassUnloading) {
692 keep_alive_cld_do(cl);
693 } else {
694 cld_do(cl);
695 }
696 }
697
698 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
699 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
700 cld->classes_do(klass_closure);
701 }
702 }
703
704 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
705 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
706 cld->classes_do(f);
707 }
708 }
709
710 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
711 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
712 cld->methods_do(f);
713 }
714 }
715
716 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
717 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
718 cld->loaded_classes_do(klass_closure);
719 }
720 }
721
722 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
723 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
724 // Only walk the head until any clds not purged from prior unloading
725 // (CMS doesn't purge right away).
726 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
727 cld->classes_do(f);
728 }
729 }
730
731 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
732 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
733
734 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
735
736 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
737 ClassLoaderData* curr = _head;
738 while (curr != _saved_head) {
739 if (!curr->claimed()) {
740 array->push(curr);
741
742 if (log_is_enabled(Debug, classloaderdata)) {
743 outputStream* log = LogHandle(classloaderdata)::debug_stream();
744 log->print("found new CLD: ");
745 curr->print_value_on(log);
746 log->cr();
747 }
748 }
749
750 curr = curr->_next;
751 }
752
753 return array;
754 }
755
756 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
757 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
758 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
759 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
760 return true;
761 }
762 }
763 return false;
764 }
765
766 #ifndef PRODUCT
767 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
768 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
769 if (loader_data == data) {
770 return true;
771 }
772 }
773
774 return false;
775 }
776 #endif // PRODUCT
777
778
779 // Move class loader data from main list to the unloaded list for unloading
780 // and deallocation later.
781 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
782 bool clean_previous_versions) {
783
784 ClassLoaderData* data = _head;
785 ClassLoaderData* prev = NULL;
786 bool seen_dead_loader = false;
787
788 // Mark metadata seen on the stack only so we can delete unneeded entries.
789 // Only walk all metadata, including the expensive code cache walk, for Full GC
790 // and only if class redefinition and if there's previous versions of
791 // Klasses to delete.
792 bool walk_all_metadata = clean_previous_versions &&
793 JvmtiExport::has_redefined_a_class() &&
794 InstanceKlass::has_previous_versions();
795 MetadataOnStackMark md_on_stack(walk_all_metadata);
796
797 // Save previous _unloading pointer for CMS which may add to unloading list before
798 // purging and we don't want to rewalk the previously unloaded class loader data.
799 _saved_unloading = _unloading;
800
801 data = _head;
802 while (data != NULL) {
803 if (data->is_alive(is_alive_closure)) {
804 // clean metaspace
805 if (walk_all_metadata) {
806 data->classes_do(InstanceKlass::purge_previous_versions);
807 }
808 data->free_deallocate_list();
809 prev = data;
810 data = data->next();
811 continue;
812 }
813 seen_dead_loader = true;
814 ClassLoaderData* dead = data;
815 dead->unload();
816 data = data->next();
817 // Remove from loader list.
818 // This class loader data will no longer be found
819 // in the ClassLoaderDataGraph.
820 if (prev != NULL) {
821 prev->set_next(data);
822 } else {
823 assert(dead == _head, "sanity check");
824 _head = data;
825 }
826 dead->set_next(_unloading);
827 _unloading = dead;
828 }
829
830 if (seen_dead_loader) {
831 post_class_unload_events();
832 }
833
834 return seen_dead_loader;
835 }
836
837 void ClassLoaderDataGraph::purge() {
838 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
839 ClassLoaderData* list = _unloading;
840 _unloading = NULL;
841 ClassLoaderData* next = list;
842 bool classes_unloaded = false;
843 while (next != NULL) {
844 ClassLoaderData* purge_me = next;
845 next = purge_me->next();
846 delete purge_me;
847 classes_unloaded = true;
848 }
849 if (classes_unloaded) {
850 Metaspace::purge();
851 set_metaspace_oom(false);
852 }
853 }
854
855 void ClassLoaderDataGraph::post_class_unload_events(void) {
856 #if INCLUDE_TRACE
857 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
858 if (Tracing::enabled()) {
859 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
860 assert(_unloading != NULL, "need class loader data unload list!");
861 _class_unload_time = Ticks::now();
862 classes_unloading_do(&class_unload_event);
863 }
864 Tracing::on_unloading_classes();
865 }
866 #endif
867 }
868
869 // CDS support
870
871 // Global metaspaces for writing information to the shared archive. When
872 // application CDS is supported, we may need one per metaspace, so this
873 // sort of looks like it.
874 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
875 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
876 static bool _shared_metaspaces_initialized = false;
877
878 // Initialize shared metaspaces (change to call from somewhere not lazily)
879 void ClassLoaderData::initialize_shared_metaspaces() {
880 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
881 assert(this == ClassLoaderData::the_null_class_loader_data(),
882 "only supported for null loader data for now");
883 assert (!_shared_metaspaces_initialized, "only initialize once");
884 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
885 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
886 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
887 _shared_metaspaces_initialized = true;
888 }
889
890 Metaspace* ClassLoaderData::ro_metaspace() {
891 assert(_ro_metaspace != NULL, "should already be initialized");
892 return _ro_metaspace;
893 }
894
895 Metaspace* ClassLoaderData::rw_metaspace() {
896 assert(_rw_metaspace != NULL, "should already be initialized");
897 return _rw_metaspace;
898 }
899
900 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
901 : _next_klass(NULL) {
902 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
903 Klass* klass = NULL;
904
905 // Find the first klass in the CLDG.
906 while (cld != NULL) {
907 klass = cld->_klasses;
908 if (klass != NULL) {
909 _next_klass = klass;
910 return;
911 }
912 cld = cld->next();
913 }
914 }
915
916 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
917 Klass* next = klass->next_link();
918 if (next != NULL) {
919 return next;
920 }
921
922 // No more klasses in the current CLD. Time to find a new CLD.
923 ClassLoaderData* cld = klass->class_loader_data();
924 while (next == NULL) {
925 cld = cld->next();
926 if (cld == NULL) {
927 break;
928 }
929 next = cld->_klasses;
930 }
931
932 return next;
933 }
934
935 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
936 Klass* head = _next_klass;
937
938 while (head != NULL) {
939 Klass* next = next_klass_in_cldg(head);
940
941 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
942
943 if (old_head == head) {
944 return head; // Won the CAS.
945 }
946
947 head = old_head;
948 }
949
950 // Nothing more for the iterator to hand out.
951 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
952 return NULL;
953 }
954
955 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
956 _data = ClassLoaderDataGraph::_head;
957 }
958
959 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
960
961 #ifndef PRODUCT
962 // callable from debugger
963 extern "C" int print_loader_data_graph() {
964 ClassLoaderDataGraph::dump_on(tty);
965 return 0;
966 }
967
968 void ClassLoaderDataGraph::verify() {
969 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
970 data->verify();
971 }
972 }
973
974 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
975 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
976 data->dump(out);
977 }
978 MetaspaceAux::dump(out);
979 }
980 #endif // PRODUCT
981
982 void ClassLoaderData::print_value_on(outputStream* out) const {
983 if (class_loader() == NULL) {
984 out->print("NULL class_loader");
985 } else {
986 out->print("class loader " INTPTR_FORMAT, p2i(this));
987 class_loader()->print_value_on(out);
988 }
989 }
990
991 #if INCLUDE_TRACE
992
993 Ticks ClassLoaderDataGraph::_class_unload_time;
994
995 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
996
997 // post class unload event
998 EventClassUnload event(UNTIMED);
999 event.set_endtime(_class_unload_time);
1000 event.set_unloadedClass(k);
1001 oop defining_class_loader = k->class_loader();
1002 event.set_definingClassLoader(defining_class_loader != NULL ?
1003 defining_class_loader->klass() : (Klass*)NULL);
1004 event.commit();
1005 }
1006
1007 #endif // INCLUDE_TRACE