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 "oops/objArrayOop.inline.hpp"
62 #include "oops/oop.inline.hpp"
63 #include "runtime/atomic.inline.hpp"
64 #include "runtime/javaCalls.hpp"
65 #include "runtime/jniHandles.hpp"
66 #include "runtime/mutex.hpp"
67 #include "runtime/safepoint.hpp"
68 #include "runtime/synchronizer.hpp"
69 #include "utilities/growableArray.hpp"
70 #include "utilities/macros.hpp"
71 #include "utilities/ostream.hpp"
72 #if INCLUDE_TRACE
73 #include "trace/tracing.hpp"
74 #endif
75
76 ClassLoaderData * ClassLoaderData::_the_null_class_loader_data = NULL;
77
78 ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool is_anonymous, Dependencies dependencies) :
79 _class_loader(h_class_loader()),
80 _is_anonymous(is_anonymous),
81 // An anonymous class loader data doesn't have anything to keep
82 // it from being unloaded during parsing of the anonymous class.
83 // The null-class-loader should always be kept alive.
84 _keep_alive(is_anonymous || h_class_loader.is_null()),
85 _metaspace(NULL), _unloading(false), _klasses(NULL),
86 _claimed(0), _jmethod_ids(NULL), _handles(NULL), _deallocate_list(NULL),
87 _next(NULL), _dependencies(dependencies), _shared_class_loader_id(-1),
88 _metaspace_lock(new Mutex(Monitor::leaf+1, "Metaspace allocation lock", true,
89 Monitor::_safepoint_check_never)) {
90 // empty
91 }
92
93 void ClassLoaderData::init_dependencies(TRAPS) {
94 assert(!Universe::is_fully_initialized(), "should only be called when initializing");
95 assert(is_the_null_class_loader_data(), "should only call this for the null class loader");
96 _dependencies.init(CHECK);
97 }
98
99 void ClassLoaderData::Dependencies::init(TRAPS) {
100 // Create empty dependencies array to add to. CMS requires this to be
101 // an oop so that it can track additions via card marks. We think.
102 _list_head = oopFactory::new_objectArray(2, CHECK);
103 }
104
105 bool ClassLoaderData::claim() {
106 if (_claimed == 1) {
107 return false;
108 }
109
110 return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
111 }
112
113 void ClassLoaderData::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
114 if (must_claim && !claim()) {
115 return;
116 }
117
118 f->do_oop(&_class_loader);
119 _dependencies.oops_do(f);
120 _handles->oops_do(f);
121 if (klass_closure != NULL) {
122 classes_do(klass_closure);
123 }
124 }
125
126 void ClassLoaderData::Dependencies::oops_do(OopClosure* f) {
127 f->do_oop((oop*)&_list_head);
128 }
129
130 void ClassLoaderData::classes_do(KlassClosure* klass_closure) {
131 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
132 klass_closure->do_klass(k);
133 assert(k != k->next_link(), "no loops!");
134 }
135 }
136
137 void ClassLoaderData::classes_do(void f(Klass * const)) {
138 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
139 f(k);
140 }
141 }
142
143 void ClassLoaderData::methods_do(void f(Method*)) {
144 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
145 if (k->is_instance_klass()) {
146 InstanceKlass::cast(k)->methods_do(f);
147 }
148 }
149 }
150
151 void ClassLoaderData::loaded_classes_do(KlassClosure* klass_closure) {
152 // Lock to avoid classes being modified/added/removed during iteration
153 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
154 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
155 // Do not filter ArrayKlass oops here...
156 if (k->is_array_klass() || (k->is_instance_klass() && InstanceKlass::cast(k)->is_loaded())) {
157 klass_closure->do_klass(k);
158 }
159 }
160 }
161
162 void ClassLoaderData::classes_do(void f(InstanceKlass*)) {
163 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
164 if (k->is_instance_klass()) {
165 f(InstanceKlass::cast(k));
166 }
167 assert(k != k->next_link(), "no loops!");
168 }
169 }
170
171 void ClassLoaderData::record_dependency(const Klass* k, TRAPS) {
172 assert(k != NULL, "invariant");
173
174 ClassLoaderData * const from_cld = this;
175 ClassLoaderData * const to_cld = k->class_loader_data();
176
177 // Dependency to the null class loader data doesn't need to be recorded
178 // because the null class loader data never goes away.
179 if (to_cld->is_the_null_class_loader_data()) {
180 return;
181 }
182
183 oop to;
184 if (to_cld->is_anonymous()) {
185 // Anonymous class dependencies are through the mirror.
186 to = k->java_mirror();
187 } else {
188 to = to_cld->class_loader();
189
190 // If from_cld is anonymous, even if it's class_loader is a parent of 'to'
191 // we still have to add it. The class_loader won't keep from_cld alive.
192 if (!from_cld->is_anonymous()) {
193 // Check that this dependency isn't from the same or parent class_loader
194 oop from = from_cld->class_loader();
195
196 oop curr = from;
197 while (curr != NULL) {
198 if (curr == to) {
199 return; // this class loader is in the parent list, no need to add it.
200 }
201 curr = java_lang_ClassLoader::parent(curr);
202 }
203 }
204 }
205
206 // It's a dependency we won't find through GC, add it. This is relatively rare
207 // Must handle over GC point.
208 Handle dependency(THREAD, to);
209 from_cld->_dependencies.add(dependency, CHECK);
210 }
211
212
213 void ClassLoaderData::Dependencies::add(Handle dependency, TRAPS) {
214 // Check first if this dependency is already in the list.
215 // Save a pointer to the last to add to under the lock.
216 objArrayOop ok = _list_head;
217 objArrayOop last = NULL;
218 while (ok != NULL) {
219 last = ok;
220 if (ok->obj_at(0) == dependency()) {
221 // Don't need to add it
222 return;
223 }
224 ok = (objArrayOop)ok->obj_at(1);
225 }
226
227 // Must handle over GC points
228 assert (last != NULL, "dependencies should be initialized");
229 objArrayHandle last_handle(THREAD, last);
230
231 // Create a new dependency node with fields for (class_loader or mirror, next)
232 objArrayOop deps = oopFactory::new_objectArray(2, CHECK);
233 deps->obj_at_put(0, dependency());
234
235 // Must handle over GC points
236 objArrayHandle new_dependency(THREAD, deps);
237
238 // Add the dependency under lock
239 locked_add(last_handle, new_dependency, THREAD);
240 }
241
242 void ClassLoaderData::Dependencies::locked_add(objArrayHandle last_handle,
243 objArrayHandle new_dependency,
244 Thread* THREAD) {
245
246 // Have to lock and put the new dependency on the end of the dependency
247 // array so the card mark for CMS sees that this dependency is new.
248 // Can probably do this lock free with some effort.
249 ObjectLocker ol(Handle(THREAD, _list_head), THREAD);
250
251 oop loader_or_mirror = new_dependency->obj_at(0);
252
253 // Since the dependencies are only added, add to the end.
254 objArrayOop end = last_handle();
255 objArrayOop last = NULL;
256 while (end != NULL) {
257 last = end;
258 // check again if another thread added it to the end.
259 if (end->obj_at(0) == loader_or_mirror) {
260 // Don't need to add it
261 return;
262 }
263 end = (objArrayOop)end->obj_at(1);
264 }
265 assert (last != NULL, "dependencies should be initialized");
266 // fill in the first element with the oop in new_dependency.
267 if (last->obj_at(0) == NULL) {
268 last->obj_at_put(0, new_dependency->obj_at(0));
269 } else {
270 last->obj_at_put(1, new_dependency());
271 }
272 }
273
274 void ClassLoaderDataGraph::clear_claimed_marks() {
275 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
276 cld->clear_claimed();
277 }
278 }
279
280 void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
281 {
282 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
283 Klass* old_value = _klasses;
284 k->set_next_link(old_value);
285 // Make sure linked class is stable, since the class list is walked without a lock
286 OrderAccess::storestore();
287 // link the new item into the list
288 _klasses = k;
289 }
290
291 if (publicize && log_is_enabled(Trace, classloaderdata) && k->class_loader_data() != NULL) {
292 ResourceMark rm;
293 outputStream* log = LogHandle(classloaderdata)::trace_stream();
294 log->print_cr("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 (log_is_enabled(Trace, classloaderdata) && class_loader() != NULL) {
416 outputStream* log = LogHandle(classloaderdata)::trace_stream();
417 log->print_cr("is_anonymous: %s", class_loader()->klass()->internal_name());
418 }
419 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::AnonymousMetaspaceType));
420 } else if (class_loader()->is_a(SystemDictionary::reflect_DelegatingClassLoader_klass())) {
421 if (log_is_enabled(Trace, classloaderdata) && class_loader() != NULL) {
422 outputStream* log = LogHandle(classloaderdata)::trace_stream();
423 log->print_cr("is_reflection: %s", class_loader()->klass()->internal_name());
424 }
425 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::ReflectionMetaspaceType));
426 } else {
427 set_metaspace(new Metaspace(_metaspace_lock, Metaspace::StandardMetaspaceType));
428 }
429 }
430 return _metaspace;
431 }
432
433 JNIHandleBlock* ClassLoaderData::handles() const { return _handles; }
434 void ClassLoaderData::set_handles(JNIHandleBlock* handles) { _handles = handles; }
435
436 jobject ClassLoaderData::add_handle(Handle h) {
437 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
438 if (handles() == NULL) {
439 set_handles(JNIHandleBlock::allocate_block());
440 }
441 return handles()->allocate_handle(h());
442 }
443
444 // Add this metadata pointer to be freed when it's safe. This is only during
445 // class unloading because Handles might point to this metadata field.
446 void ClassLoaderData::add_to_deallocate_list(Metadata* m) {
447 // Metadata in shared region isn't deleted.
448 if (!m->is_shared()) {
449 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
450 if (_deallocate_list == NULL) {
451 _deallocate_list = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(100, true);
452 }
453 _deallocate_list->append_if_missing(m);
454 }
455 }
456
457 // Deallocate free metadata on the free list. How useful the PermGen was!
458 void ClassLoaderData::free_deallocate_list() {
459 // Don't need lock, at safepoint
460 assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
461 if (_deallocate_list == NULL) {
462 return;
463 }
464 // Go backwards because this removes entries that are freed.
465 for (int i = _deallocate_list->length() - 1; i >= 0; i--) {
466 Metadata* m = _deallocate_list->at(i);
467 if (!m->on_stack()) {
468 _deallocate_list->remove_at(i);
469 // There are only three types of metadata that we deallocate directly.
470 // Cast them so they can be used by the template function.
471 if (m->is_method()) {
472 MetadataFactory::free_metadata(this, (Method*)m);
473 } else if (m->is_constantPool()) {
474 MetadataFactory::free_metadata(this, (ConstantPool*)m);
475 } else if (m->is_klass()) {
476 MetadataFactory::free_metadata(this, (InstanceKlass*)m);
477 } else {
478 ShouldNotReachHere();
479 }
480 } else {
481 // Metadata is alive.
482 // If scratch_class is on stack then it shouldn't be on this list!
483 assert(!m->is_klass() || !((InstanceKlass*)m)->is_scratch_class(),
484 "scratch classes on this list should be dead");
485 // Also should assert that other metadata on the list was found in handles.
486 }
487 }
488 }
489
490 // These anonymous class loaders are to contain classes used for JSR292
491 ClassLoaderData* ClassLoaderData::anonymous_class_loader_data(oop loader, TRAPS) {
492 // Add a new class loader data to the graph.
493 return ClassLoaderDataGraph::add(loader, true, THREAD);
494 }
495
496 const char* ClassLoaderData::loader_name() {
497 // Handles null class loader
498 return SystemDictionary::loader_name(class_loader());
499 }
500
501 #ifndef PRODUCT
502 // Define to dump klasses
503 #undef CLD_DUMP_KLASSES
504
505 void ClassLoaderData::dump(outputStream * const out) {
506 ResourceMark rm;
507 out->print("ClassLoaderData CLD: " PTR_FORMAT ", loader: " PTR_FORMAT ", loader_klass: " PTR_FORMAT " %s {",
508 p2i(this), p2i((void *)class_loader()),
509 p2i(class_loader() != NULL ? class_loader()->klass() : NULL), loader_name());
510 if (claimed()) out->print(" claimed ");
511 if (is_unloading()) out->print(" unloading ");
512 out->print(" handles " INTPTR_FORMAT, p2i(handles()));
513 out->cr();
514 if (metaspace_or_null() != NULL) {
515 out->print_cr("metaspace: " INTPTR_FORMAT, p2i(metaspace_or_null()));
516 metaspace_or_null()->dump(out);
517 } else {
518 out->print_cr("metaspace: NULL");
519 }
520
521 #ifdef CLD_DUMP_KLASSES
522 if (Verbose) {
523 ResourceMark rm;
524 Klass* k = _klasses;
525 while (k != NULL) {
526 out->print_cr("klass " PTR_FORMAT ", %s, CT: %d, MUT: %d", k, k->name()->as_C_string(),
527 k->has_modified_oops(), k->has_accumulated_modified_oops());
528 assert(k != k->next_link(), "no loops!");
529 k = k->next_link();
530 }
531 }
532 #endif // CLD_DUMP_KLASSES
533 #undef CLD_DUMP_KLASSES
534 if (_jmethod_ids != NULL) {
535 Method::print_jmethod_ids(this, out);
536 }
537 out->print_cr("}");
538 }
539 #endif // PRODUCT
540
541 void ClassLoaderData::verify() {
542 oop cl = class_loader();
543
544 guarantee(this == class_loader_data(cl) || is_anonymous(), "Must be the same");
545 guarantee(cl != NULL || this == ClassLoaderData::the_null_class_loader_data() || is_anonymous(), "must be");
546
547 // Verify the integrity of the allocated space.
548 if (metaspace_or_null() != NULL) {
549 metaspace_or_null()->verify();
550 }
551
552 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
553 guarantee(k->class_loader_data() == this, "Must be the same");
554 k->verify();
555 assert(k != k->next_link(), "no loops!");
556 }
557 }
558
559 bool ClassLoaderData::contains_klass(Klass* klass) {
560 for (Klass* k = _klasses; k != NULL; k = k->next_link()) {
561 if (k == klass) return true;
562 }
563 return false;
564 }
565
566
567 // GC root of class loader data created.
568 ClassLoaderData* ClassLoaderDataGraph::_head = NULL;
569 ClassLoaderData* ClassLoaderDataGraph::_unloading = NULL;
570 ClassLoaderData* ClassLoaderDataGraph::_saved_unloading = NULL;
571 ClassLoaderData* ClassLoaderDataGraph::_saved_head = NULL;
572
573 bool ClassLoaderDataGraph::_should_purge = false;
574 bool ClassLoaderDataGraph::_metaspace_oom = false;
575
576 // Add a new class loader data node to the list. Assign the newly created
577 // ClassLoaderData into the java/lang/ClassLoader object as a hidden field
578 ClassLoaderData* ClassLoaderDataGraph::add(Handle loader, bool is_anonymous, TRAPS) {
579 // We need to allocate all the oops for the ClassLoaderData before allocating the
580 // actual ClassLoaderData object.
581 ClassLoaderData::Dependencies dependencies(CHECK_NULL);
582 ClassLoaderData* cld;
583
584
585 //BEGIN no_safepoints
586 {
587 No_Safepoint_Verifier no_safepoints; // we mustn't GC until we've installed the
588 // ClassLoaderData in the graph since the CLD
589 // contains unhandled oops
590
591 cld = new ClassLoaderData(loader, is_anonymous, dependencies);
592
593 if (!is_anonymous) {
594 ClassLoaderData** cld_addr = java_lang_ClassLoader::loader_data_addr(loader());
595 // First, Atomically set it
596 ClassLoaderData* old = (ClassLoaderData*) Atomic::cmpxchg_ptr(cld, cld_addr, NULL);
597 if (old != NULL) {
598 delete cld;
599 // Returns the data.
600 return old;
601 }
602 }
603
604 // We won the race, and therefore the task of adding the data to the list of
605 // class loader data
606 ClassLoaderData** list_head = &_head;
607 ClassLoaderData* next = _head;
608
609 do {
610 cld->set_next(next);
611 ClassLoaderData* exchanged = (ClassLoaderData*)Atomic::cmpxchg_ptr(cld, list_head, next);
612 if (exchanged == next) {
613 break;
614 }
615 next = exchanged;
616 } while (true);
617 }
618 //END no_safepoints
619
620 // It's OK to do safe points now (and we need to do that in JavaCalls::call_virtual)
621 if (log_is_enabled(Debug, classloaderdata)) {
622 Handle string;
623 if (loader.not_null()) {
624 // Include the result of loader.toString() in the output. This allows
625 // the user of the log to identify the class loader instance.
626 JavaValue result(T_OBJECT);
627 KlassHandle spec_klass(THREAD, SystemDictionary::ClassLoader_klass());
628 JavaCalls::call_virtual(&result,
629 loader,
630 spec_klass,
631 vmSymbols::toString_name(),
632 vmSymbols::void_string_signature(),
633 CHECK_NULL);
634 assert(result.get_type() == T_OBJECT, "just checking");
635 string = (oop)result.get_jobject();
636 }
637
638 ResourceMark rm;
639 outputStream* log = LogHandle(classloaderdata)::debug_stream();
640 log->print("create class loader data " INTPTR_FORMAT, p2i(cld));
641 log->print(" for instance " INTPTR_FORMAT " of %s", p2i((void *)cld->class_loader()),
642 cld->loader_name());
643
644 if (string.not_null()) {
645 log->print(": ");
646 java_lang_String::print(string(), log);
647 }
648 log->cr();
649 }
650 return cld;
651 }
652
653 void ClassLoaderDataGraph::oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
654 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
655 cld->oops_do(f, klass_closure, must_claim);
656 }
657 }
658
659 void ClassLoaderDataGraph::keep_alive_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
660 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
661 if (cld->keep_alive()) {
662 cld->oops_do(f, klass_closure, must_claim);
663 }
664 }
665 }
666
667 void ClassLoaderDataGraph::always_strong_oops_do(OopClosure* f, KlassClosure* klass_closure, bool must_claim) {
668 if (ClassUnloading) {
669 keep_alive_oops_do(f, klass_closure, must_claim);
670 } else {
671 oops_do(f, klass_closure, must_claim);
672 }
673 }
674
675 void ClassLoaderDataGraph::cld_do(CLDClosure* cl) {
676 for (ClassLoaderData* cld = _head; cl != NULL && cld != NULL; cld = cld->next()) {
677 cl->do_cld(cld);
678 }
679 }
680
681 void ClassLoaderDataGraph::roots_cld_do(CLDClosure* strong, CLDClosure* weak) {
682 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->_next) {
683 CLDClosure* closure = cld->keep_alive() ? strong : weak;
684 if (closure != NULL) {
685 closure->do_cld(cld);
686 }
687 }
688 }
689
690 void ClassLoaderDataGraph::keep_alive_cld_do(CLDClosure* cl) {
691 roots_cld_do(cl, NULL);
692 }
693
694 void ClassLoaderDataGraph::always_strong_cld_do(CLDClosure* cl) {
695 if (ClassUnloading) {
696 keep_alive_cld_do(cl);
697 } else {
698 cld_do(cl);
699 }
700 }
701
702 void ClassLoaderDataGraph::classes_do(KlassClosure* klass_closure) {
703 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
704 cld->classes_do(klass_closure);
705 }
706 }
707
708 void ClassLoaderDataGraph::classes_do(void f(Klass* const)) {
709 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
710 cld->classes_do(f);
711 }
712 }
713
714 void ClassLoaderDataGraph::methods_do(void f(Method*)) {
715 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
716 cld->methods_do(f);
717 }
718 }
719
720 void ClassLoaderDataGraph::loaded_classes_do(KlassClosure* klass_closure) {
721 for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
722 cld->loaded_classes_do(klass_closure);
723 }
724 }
725
726 void ClassLoaderDataGraph::classes_unloading_do(void f(Klass* const)) {
727 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
728 // Only walk the head until any clds not purged from prior unloading
729 // (CMS doesn't purge right away).
730 for (ClassLoaderData* cld = _unloading; cld != _saved_unloading; cld = cld->next()) {
731 cld->classes_do(f);
732 }
733 }
734
735 GrowableArray<ClassLoaderData*>* ClassLoaderDataGraph::new_clds() {
736 assert(_head == NULL || _saved_head != NULL, "remember_new_clds(true) not called?");
737
738 GrowableArray<ClassLoaderData*>* array = new GrowableArray<ClassLoaderData*>();
739
740 // The CLDs in [_head, _saved_head] were all added during last call to remember_new_clds(true);
741 ClassLoaderData* curr = _head;
742 while (curr != _saved_head) {
743 if (!curr->claimed()) {
744 array->push(curr);
745
746 if (log_is_enabled(Debug, classloaderdata)) {
747 outputStream* log = LogHandle(classloaderdata)::debug_stream();
748 log->print("[ClassLoaderData] found new CLD: ");
749 curr->print_value_on(log);
750 log->cr();
751 }
752 }
753
754 curr = curr->_next;
755 }
756
757 return array;
758 }
759
760 bool ClassLoaderDataGraph::unload_list_contains(const void* x) {
761 assert(SafepointSynchronize::is_at_safepoint(), "only safe to call at safepoint");
762 for (ClassLoaderData* cld = _unloading; cld != NULL; cld = cld->next()) {
763 if (cld->metaspace_or_null() != NULL && cld->metaspace_or_null()->contains(x)) {
764 return true;
765 }
766 }
767 return false;
768 }
769
770 #ifndef PRODUCT
771 bool ClassLoaderDataGraph::contains_loader_data(ClassLoaderData* loader_data) {
772 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
773 if (loader_data == data) {
774 return true;
775 }
776 }
777
778 return false;
779 }
780 #endif // PRODUCT
781
782
783 // Move class loader data from main list to the unloaded list for unloading
784 // and deallocation later.
785 bool ClassLoaderDataGraph::do_unloading(BoolObjectClosure* is_alive_closure,
786 bool clean_previous_versions) {
787
788 ClassLoaderData* data = _head;
789 ClassLoaderData* prev = NULL;
790 bool seen_dead_loader = false;
791
792 // Mark metadata seen on the stack only so we can delete unneeded entries.
793 // Only walk all metadata, including the expensive code cache walk, for Full GC
794 // and only if class redefinition and if there's previous versions of
795 // Klasses to delete.
796 bool walk_all_metadata = clean_previous_versions &&
797 JvmtiExport::has_redefined_a_class() &&
798 InstanceKlass::has_previous_versions();
799 MetadataOnStackMark md_on_stack(walk_all_metadata);
800
801 // Save previous _unloading pointer for CMS which may add to unloading list before
802 // purging and we don't want to rewalk the previously unloaded class loader data.
803 _saved_unloading = _unloading;
804
805 data = _head;
806 while (data != NULL) {
807 if (data->is_alive(is_alive_closure)) {
808 // clean metaspace
809 if (walk_all_metadata) {
810 data->classes_do(InstanceKlass::purge_previous_versions);
811 }
812 data->free_deallocate_list();
813 prev = data;
814 data = data->next();
815 continue;
816 }
817 seen_dead_loader = true;
818 ClassLoaderData* dead = data;
819 dead->unload();
820 data = data->next();
821 // Remove from loader list.
822 // This class loader data will no longer be found
823 // in the ClassLoaderDataGraph.
824 if (prev != NULL) {
825 prev->set_next(data);
826 } else {
827 assert(dead == _head, "sanity check");
828 _head = data;
829 }
830 dead->set_next(_unloading);
831 _unloading = dead;
832 }
833
834 if (seen_dead_loader) {
835 post_class_unload_events();
836 }
837
838 return seen_dead_loader;
839 }
840
841 void ClassLoaderDataGraph::purge() {
842 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
843 ClassLoaderData* list = _unloading;
844 _unloading = NULL;
845 ClassLoaderData* next = list;
846 bool classes_unloaded = false;
847 while (next != NULL) {
848 ClassLoaderData* purge_me = next;
849 next = purge_me->next();
850 delete purge_me;
851 classes_unloaded = true;
852 }
853 if (classes_unloaded) {
854 Metaspace::purge();
855 set_metaspace_oom(false);
856 }
857 }
858
859 void ClassLoaderDataGraph::post_class_unload_events(void) {
860 #if INCLUDE_TRACE
861 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
862 if (Tracing::enabled()) {
863 if (Tracing::is_event_enabled(TraceClassUnloadEvent)) {
864 assert(_unloading != NULL, "need class loader data unload list!");
865 _class_unload_time = Ticks::now();
866 classes_unloading_do(&class_unload_event);
867 }
868 Tracing::on_unloading_classes();
869 }
870 #endif
871 }
872
873 // CDS support
874
875 // Global metaspaces for writing information to the shared archive. When
876 // application CDS is supported, we may need one per metaspace, so this
877 // sort of looks like it.
878 Metaspace* ClassLoaderData::_ro_metaspace = NULL;
879 Metaspace* ClassLoaderData::_rw_metaspace = NULL;
880 static bool _shared_metaspaces_initialized = false;
881
882 // Initialize shared metaspaces (change to call from somewhere not lazily)
883 void ClassLoaderData::initialize_shared_metaspaces() {
884 assert(DumpSharedSpaces, "only use this for dumping shared spaces");
885 assert(this == ClassLoaderData::the_null_class_loader_data(),
886 "only supported for null loader data for now");
887 assert (!_shared_metaspaces_initialized, "only initialize once");
888 MutexLockerEx ml(metaspace_lock(), Mutex::_no_safepoint_check_flag);
889 _ro_metaspace = new Metaspace(_metaspace_lock, Metaspace::ROMetaspaceType);
890 _rw_metaspace = new Metaspace(_metaspace_lock, Metaspace::ReadWriteMetaspaceType);
891 _shared_metaspaces_initialized = true;
892 }
893
894 Metaspace* ClassLoaderData::ro_metaspace() {
895 assert(_ro_metaspace != NULL, "should already be initialized");
896 return _ro_metaspace;
897 }
898
899 Metaspace* ClassLoaderData::rw_metaspace() {
900 assert(_rw_metaspace != NULL, "should already be initialized");
901 return _rw_metaspace;
902 }
903
904 ClassLoaderDataGraphKlassIteratorAtomic::ClassLoaderDataGraphKlassIteratorAtomic()
905 : _next_klass(NULL) {
906 ClassLoaderData* cld = ClassLoaderDataGraph::_head;
907 Klass* klass = NULL;
908
909 // Find the first klass in the CLDG.
910 while (cld != NULL) {
911 klass = cld->_klasses;
912 if (klass != NULL) {
913 _next_klass = klass;
914 return;
915 }
916 cld = cld->next();
917 }
918 }
919
920 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass_in_cldg(Klass* klass) {
921 Klass* next = klass->next_link();
922 if (next != NULL) {
923 return next;
924 }
925
926 // No more klasses in the current CLD. Time to find a new CLD.
927 ClassLoaderData* cld = klass->class_loader_data();
928 while (next == NULL) {
929 cld = cld->next();
930 if (cld == NULL) {
931 break;
932 }
933 next = cld->_klasses;
934 }
935
936 return next;
937 }
938
939 Klass* ClassLoaderDataGraphKlassIteratorAtomic::next_klass() {
940 Klass* head = _next_klass;
941
942 while (head != NULL) {
943 Klass* next = next_klass_in_cldg(head);
944
945 Klass* old_head = (Klass*)Atomic::cmpxchg_ptr(next, &_next_klass, head);
946
947 if (old_head == head) {
948 return head; // Won the CAS.
949 }
950
951 head = old_head;
952 }
953
954 // Nothing more for the iterator to hand out.
955 assert(head == NULL, "head is " PTR_FORMAT ", expected not null:", p2i(head));
956 return NULL;
957 }
958
959 ClassLoaderDataGraphMetaspaceIterator::ClassLoaderDataGraphMetaspaceIterator() {
960 _data = ClassLoaderDataGraph::_head;
961 }
962
963 ClassLoaderDataGraphMetaspaceIterator::~ClassLoaderDataGraphMetaspaceIterator() {}
964
965 #ifndef PRODUCT
966 // callable from debugger
967 extern "C" int print_loader_data_graph() {
968 ClassLoaderDataGraph::dump_on(tty);
969 return 0;
970 }
971
972 void ClassLoaderDataGraph::verify() {
973 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
974 data->verify();
975 }
976 }
977
978 void ClassLoaderDataGraph::dump_on(outputStream * const out) {
979 for (ClassLoaderData* data = _head; data != NULL; data = data->next()) {
980 data->dump(out);
981 }
982 MetaspaceAux::dump(out);
983 }
984 #endif // PRODUCT
985
986 void ClassLoaderData::print_value_on(outputStream* out) const {
987 if (class_loader() == NULL) {
988 out->print("NULL class_loader");
989 } else {
990 out->print("class loader " INTPTR_FORMAT, p2i(this));
991 class_loader()->print_value_on(out);
992 }
993 }
994
995 #if INCLUDE_TRACE
996
997 Ticks ClassLoaderDataGraph::_class_unload_time;
998
999 void ClassLoaderDataGraph::class_unload_event(Klass* const k) {
1000
1001 // post class unload event
1002 EventClassUnload event(UNTIMED);
1003 event.set_endtime(_class_unload_time);
1004 event.set_unloadedClass(k);
1005 oop defining_class_loader = k->class_loader();
1006 event.set_definingClassLoader(defining_class_loader != NULL ?
1007 defining_class_loader->klass() : (Klass*)NULL);
1008 event.commit();
1009 }
1010
1011 #endif // INCLUDE_TRACE