1 /*
2 * Copyright (c) 1997, 2019, 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 #include "precompiled.hpp"
26 #include "jvm.h"
27 #include "aot/aotLoader.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/classLoaderExt.hpp"
34 #include "classfile/dictionary.hpp"
35 #include "classfile/javaClasses.inline.hpp"
36 #include "classfile/klassFactory.hpp"
37 #include "classfile/loaderConstraints.hpp"
38 #include "classfile/packageEntry.hpp"
39 #include "classfile/placeholders.hpp"
40 #include "classfile/protectionDomainCache.hpp"
41 #include "classfile/resolutionErrors.hpp"
42 #include "classfile/stringTable.hpp"
43 #include "classfile/symbolTable.hpp"
44 #include "classfile/systemDictionary.hpp"
45 #include "classfile/vmSymbols.hpp"
46 #include "code/codeCache.hpp"
47 #include "compiler/compileBroker.hpp"
48 #include "gc/shared/gcTraceTime.inline.hpp"
49 #include "gc/shared/oopStorage.inline.hpp"
50 #include "gc/shared/oopStorageSet.hpp"
51 #include "interpreter/bytecodeStream.hpp"
52 #include "interpreter/interpreter.hpp"
53 #include "jfr/jfrEvents.hpp"
54 #include "logging/log.hpp"
55 #include "logging/logStream.hpp"
56 #include "memory/filemap.hpp"
57 #include "memory/heapShared.hpp"
58 #include "memory/metaspaceClosure.hpp"
59 #include "memory/oopFactory.hpp"
60 #include "memory/resourceArea.hpp"
61 #include "memory/universe.hpp"
62 #include "oops/access.inline.hpp"
63 #include "oops/instanceKlass.hpp"
64 #include "oops/instanceRefKlass.hpp"
65 #include "oops/klass.inline.hpp"
66 #include "oops/method.inline.hpp"
67 #include "oops/methodData.hpp"
68 #include "oops/objArrayKlass.hpp"
69 #include "oops/objArrayOop.inline.hpp"
70 #include "oops/oop.inline.hpp"
71 #include "oops/symbol.hpp"
72 #include "oops/typeArrayKlass.hpp"
73 #include "prims/jvmtiExport.hpp"
74 #include "prims/methodHandles.hpp"
75 #include "runtime/arguments.hpp"
76 #include "runtime/biasedLocking.hpp"
77 #include "runtime/fieldType.hpp"
78 #include "runtime/handles.inline.hpp"
79 #include "runtime/java.hpp"
80 #include "runtime/javaCalls.hpp"
81 #include "runtime/mutexLocker.hpp"
82 #include "runtime/sharedRuntime.hpp"
83 #include "runtime/signature.hpp"
84 #include "services/classLoadingService.hpp"
85 #include "services/diagnosticCommand.hpp"
86 #include "services/threadService.hpp"
87 #include "utilities/macros.hpp"
88 #if INCLUDE_CDS
89 #include "classfile/systemDictionaryShared.hpp"
90 #endif
91 #if INCLUDE_JFR
92 #include "jfr/jfr.hpp"
93 #endif
94
95 PlaceholderTable* SystemDictionary::_placeholders = NULL;
96 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
97 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
98 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
99 ProtectionDomainCacheTable* SystemDictionary::_pd_cache_table = NULL;
100
101 oop SystemDictionary::_system_loader_lock_obj = NULL;
102
103 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
104 = { NULL /*, NULL...*/ };
105
106 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
107
108 oop SystemDictionary::_java_system_loader = NULL;
109 oop SystemDictionary::_java_platform_loader = NULL;
110
111 // Default ProtectionDomainCacheSize value
112
113 const int defaultProtectionDomainCacheSize = 1009;
114
115 // ----------------------------------------------------------------------------
116 // Java-level SystemLoader and PlatformLoader
117
118 oop SystemDictionary::java_system_loader() {
119 return _java_system_loader;
120 }
121
122 oop SystemDictionary::java_platform_loader() {
123 return _java_platform_loader;
124 }
125
126 void SystemDictionary::compute_java_loaders(TRAPS) {
127 JavaValue result(T_OBJECT);
128 InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
129 JavaCalls::call_static(&result,
130 class_loader_klass,
131 vmSymbols::getSystemClassLoader_name(),
132 vmSymbols::void_classloader_signature(),
133 CHECK);
134
135 _java_system_loader = (oop)result.get_jobject();
136
137 JavaCalls::call_static(&result,
138 class_loader_klass,
139 vmSymbols::getPlatformClassLoader_name(),
140 vmSymbols::void_classloader_signature(),
141 CHECK);
142
143 _java_platform_loader = (oop)result.get_jobject();
144 }
145
146 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader) {
147 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
148 return ClassLoaderDataGraph::find_or_create(class_loader);
149 }
150
151 // ----------------------------------------------------------------------------
152 // Parallel class loading check
153
154 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
155 if (class_loader.is_null()) return true;
156 if (AlwaysLockClassLoader) return false;
157 return java_lang_ClassLoader::parallelCapable(class_loader());
158 }
159 // ----------------------------------------------------------------------------
160 // ParallelDefineClass flag does not apply to bootclass loader
161 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
162 if (class_loader.is_null()) return false;
163 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
164 return true;
165 }
166 return false;
167 }
168
169 // Returns true if the passed class loader is the builtin application class loader
170 // or a custom system class loader. A customer system class loader can be
171 // specified via -Djava.system.class.loader.
172 bool SystemDictionary::is_system_class_loader(oop class_loader) {
173 if (class_loader == NULL) {
174 return false;
175 }
176 return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
177 class_loader == _java_system_loader);
178 }
179
180 // Returns true if the passed class loader is the platform class loader.
181 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
182 if (class_loader == NULL) {
183 return false;
184 }
185 return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
186 }
187
188 // ----------------------------------------------------------------------------
189 // Resolving of classes
190
191 // Forwards to resolve_or_null
192
193 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
194 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
195 if (HAS_PENDING_EXCEPTION || klass == NULL) {
196 // can return a null klass
197 klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
198 }
199 return klass;
200 }
201
202 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
203 bool throw_error,
204 Klass* klass, TRAPS) {
205 if (HAS_PENDING_EXCEPTION) {
206 // If we have a pending exception we forward it to the caller, unless throw_error is true,
207 // in which case we have to check whether the pending exception is a ClassNotFoundException,
208 // and if so convert it to a NoClassDefFoundError
209 // And chain the original ClassNotFoundException
210 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
211 ResourceMark rm(THREAD);
212 assert(klass == NULL, "Should not have result with exception pending");
213 Handle e(THREAD, PENDING_EXCEPTION);
214 CLEAR_PENDING_EXCEPTION;
215 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
216 } else {
217 return NULL;
218 }
219 }
220 // Class not found, throw appropriate error or exception depending on value of throw_error
221 if (klass == NULL) {
222 ResourceMark rm(THREAD);
223 if (throw_error) {
224 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
225 } else {
226 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
227 }
228 }
229 return klass;
230 }
231
232
233 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
234 bool throw_error, TRAPS)
235 {
236 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
237 }
238
239
240 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
241
242 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
243 if (FieldType::is_array(class_name)) {
244 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
245 } else {
246 return resolve_instance_class_or_null_helper(class_name, class_loader, protection_domain, THREAD);
247 }
248 }
249
250 // name may be in the form of "java/lang/Object" or "Ljava/lang/Object;"
251 InstanceKlass* SystemDictionary::resolve_instance_class_or_null_helper(Symbol* class_name,
252 Handle class_loader,
253 Handle protection_domain,
254 TRAPS) {
255 assert(class_name != NULL && !FieldType::is_array(class_name), "must be");
256 if (FieldType::is_obj(class_name)) {
257 ResourceMark rm(THREAD);
258 // Ignore wrapping L and ;.
259 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
260 class_name->utf8_length() - 2);
261 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
262 } else {
263 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
264 }
265 }
266
267 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
268 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
269 }
270
271 // Forwards to resolve_instance_class_or_null
272
273 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
274 Handle class_loader,
275 Handle protection_domain,
276 TRAPS) {
277 assert(FieldType::is_array(class_name), "must be array");
278 Klass* k = NULL;
279 FieldArrayInfo fd;
280 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
281 // of this call
282 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
283 if (t == T_OBJECT) {
284 // naked oop "k" is OK here -- we assign back into it
285 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
286 class_loader,
287 protection_domain,
288 CHECK_NULL);
289 if (k != NULL) {
290 k = k->array_klass(fd.dimension(), CHECK_NULL);
291 }
292 } else {
293 k = Universe::typeArrayKlassObj(t);
294 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
295 }
296 return k;
297 }
298
299
300 // Must be called for any super-class or super-interface resolution
301 // during class definition to allow class circularity checking
302 // super-interface callers:
303 // parse_interfaces - for defineClass & jvmtiRedefineClasses
304 // super-class callers:
305 // ClassFileParser - for defineClass & jvmtiRedefineClasses
306 // load_shared_class - while loading a class from shared archive
307 // resolve_instance_class_or_null:
308 // via: handle_parallel_super_load
309 // when resolving a class that has an existing placeholder with
310 // a saved superclass [i.e. a defineClass is currently in progress]
311 // if another thread is trying to resolve the class, it must do
312 // super-class checks on its own thread to catch class circularity
313 // This last call is critical in class circularity checking for cases
314 // where classloading is delegated to different threads and the
315 // classloader lock is released.
316 // Take the case: Base->Super->Base
317 // 1. If thread T1 tries to do a defineClass of class Base
318 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
319 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
320 // so it tries to load Super
321 // 3. If we load the class internally, or user classloader uses same thread
322 // loadClassFromxxx or defineClass via parseClassFile Super ...
323 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
324 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
325 // 3.4 calls resolve_super_or_fail Base
326 // 3.5 finds T1,Base -> throws class circularity
327 //OR 4. If T2 tries to resolve Super via defineClass Super ...
328 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
329 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
330 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
331 // 4.4 finds T2, Super -> throws class circularity
332 // Must be called, even if superclass is null, since this is
333 // where the placeholder entry is created which claims this
334 // thread is loading this class/classloader.
335 // Be careful when modifying this code: once you have run
336 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
337 // you need to find_and_remove it before returning.
338 // So be careful to not exit with a CHECK_ macro betweeen these calls.
339 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
340 Symbol* super_name,
341 Handle class_loader,
342 Handle protection_domain,
343 bool is_superclass,
344 TRAPS) {
345 assert(!FieldType::is_array(super_name), "invalid super class name");
346 #if INCLUDE_CDS
347 if (DumpSharedSpaces) {
348 // Special processing for handling UNREGISTERED shared classes.
349 InstanceKlass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
350 super_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
351 if (k) {
352 return k;
353 }
354 }
355 #endif // INCLUDE_CDS
356
357 // Double-check, if child class is already loaded, just return super-class,interface
358 // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
359 // dictionary.
360 // Make sure there's a placeholder for the *child* before resolving.
361 // Used as a claim that this thread is currently loading superclass/classloader
362 // Used here for ClassCircularity checks and also for heap verification
363 // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
364 // Must check ClassCircularity before checking if super class is already loaded.
365 //
366 // We might not already have a placeholder if this child_name was
367 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
368 // the name of the class might not be known until the stream is actually
369 // parsed.
370 // Bugs 4643874, 4715493
371
372 ClassLoaderData* loader_data = class_loader_data(class_loader);
373 Dictionary* dictionary = loader_data->dictionary();
374 unsigned int d_hash = dictionary->compute_hash(child_name);
375 unsigned int p_hash = placeholders()->compute_hash(child_name);
376 int p_index = placeholders()->hash_to_index(p_hash);
377 // can't throw error holding a lock
378 bool child_already_loaded = false;
379 bool throw_circularity_error = false;
380 {
381 MutexLocker mu(SystemDictionary_lock, THREAD);
382 InstanceKlass* childk = find_class(d_hash, child_name, dictionary);
383 InstanceKlass* quicksuperk;
384 // to support // loading: if child done loading, just return superclass
385 // if super_name, & class_loader don't match:
386 // if initial define, SD update will give LinkageError
387 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
388 // so we don't throw an exception here.
389 // see: nsk redefclass014 & java.lang.instrument Instrument032
390 if ((childk != NULL ) && (is_superclass) &&
391 ((quicksuperk = childk->java_super()) != NULL) &&
392 ((quicksuperk->name() == super_name) &&
393 (quicksuperk->class_loader() == class_loader()))) {
394 return quicksuperk;
395 } else {
396 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
397 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
398 throw_circularity_error = true;
399 }
400 }
401 if (!throw_circularity_error) {
402 // Be careful not to exit resolve_super
403 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, super_name, THREAD);
404 }
405 }
406 if (throw_circularity_error) {
407 ResourceMark rm(THREAD);
408 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
409 }
410
411 // java.lang.Object should have been found above
412 assert(super_name != NULL, "null super class for resolving");
413 // Resolve the super class or interface, check results on return
414 InstanceKlass* superk =
415 SystemDictionary::resolve_instance_class_or_null_helper(super_name,
416 class_loader,
417 protection_domain,
418 THREAD);
419
420 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
421 // It is no longer necessary to keep the placeholder table alive until update_dictionary
422 // or error. GC used to walk the placeholder table as strong roots.
423 // The instanceKlass is kept alive because the class loader is on the stack,
424 // which keeps the loader_data alive, as well as all instanceKlasses in
425 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
426 {
427 MutexLocker mu(SystemDictionary_lock, THREAD);
428 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
429 SystemDictionary_lock->notify_all();
430 }
431 if (HAS_PENDING_EXCEPTION || superk == NULL) {
432 // can null superk
433 Klass* k = handle_resolution_exception(super_name, true, superk, THREAD);
434 assert(k == NULL || k == superk, "must be");
435 if (k == NULL) {
436 superk = NULL;
437 }
438 }
439
440 return superk;
441 }
442
443 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
444 Handle class_loader,
445 Handle protection_domain,
446 TRAPS) {
447 // Now we have to call back to java to check if the initating class has access
448 JavaValue result(T_VOID);
449 LogTarget(Debug, protectiondomain) lt;
450 if (lt.is_enabled()) {
451 ResourceMark rm;
452 // Print out trace information
453 LogStream ls(lt);
454 ls.print_cr("Checking package access");
455 if (class_loader() != NULL) {
456 ls.print("class loader: ");
457 class_loader()->print_value_on(&ls);
458 } else {
459 ls.print_cr("class loader: NULL");
460 }
461 if (protection_domain() != NULL) {
462 ls.print(" protection domain: ");
463 protection_domain()->print_value_on(&ls);
464 } else {
465 ls.print_cr(" protection domain: NULL");
466 }
467 ls.print(" loading: "); klass->print_value_on(&ls);
468 ls.cr();
469 }
470
471 // This handle and the class_loader handle passed in keeps this class from
472 // being unloaded through several GC points.
473 // The class_loader handle passed in is the initiating loader.
474 Handle mirror(THREAD, klass->java_mirror());
475
476 InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
477 JavaCalls::call_special(&result,
478 class_loader,
479 system_loader,
480 vmSymbols::checkPackageAccess_name(),
481 vmSymbols::class_protectiondomain_signature(),
482 mirror,
483 protection_domain,
484 THREAD);
485
486 if (HAS_PENDING_EXCEPTION) {
487 log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
488 } else {
489 log_debug(protectiondomain)("granted");
490 }
491
492 if (HAS_PENDING_EXCEPTION) return;
493
494 // If no exception has been thrown, we have validated the protection domain
495 // Insert the protection domain of the initiating class into the set.
496 {
497 ClassLoaderData* loader_data = class_loader_data(class_loader);
498 Dictionary* dictionary = loader_data->dictionary();
499
500 Symbol* kn = klass->name();
501 unsigned int d_hash = dictionary->compute_hash(kn);
502
503 MutexLocker mu(SystemDictionary_lock, THREAD);
504 int d_index = dictionary->hash_to_index(d_hash);
505 dictionary->add_protection_domain(d_index, d_hash, klass,
506 protection_domain, THREAD);
507 }
508 }
509
510 // We only get here if this thread finds that another thread
511 // has already claimed the placeholder token for the current operation,
512 // but that other thread either never owned or gave up the
513 // object lock
514 // Waits on SystemDictionary_lock to indicate placeholder table updated
515 // On return, caller must recheck placeholder table state
516 //
517 // We only get here if
518 // 1) custom classLoader, i.e. not bootstrap classloader
519 // 2) custom classLoader has broken the class loader objectLock
520 // so another thread got here in parallel
521 //
522 // lockObject must be held.
523 // Complicated dance due to lock ordering:
524 // Must first release the classloader object lock to
525 // allow initial definer to complete the class definition
526 // and to avoid deadlock
527 // Reclaim classloader lock object with same original recursion count
528 // Must release SystemDictionary_lock after notify, since
529 // class loader lock must be claimed before SystemDictionary_lock
530 // to prevent deadlocks
531 //
532 // The notify allows applications that did an untimed wait() on
533 // the classloader object lock to not hang.
534 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
535 assert_lock_strong(SystemDictionary_lock);
536
537 bool calledholdinglock
538 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
539 assert(calledholdinglock,"must hold lock for notify");
540 assert((lockObject() != _system_loader_lock_obj && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
541 ObjectSynchronizer::notifyall(lockObject, THREAD);
542 intx recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
543 SystemDictionary_lock->wait();
544 SystemDictionary_lock->unlock();
545 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
546 SystemDictionary_lock->lock();
547 }
548
549 // If the class in is in the placeholder table, class loading is in progress
550 // For cases where the application changes threads to load classes, it
551 // is critical to ClassCircularity detection that we try loading
552 // the superclass on the same thread internally, so we do parallel
553 // super class loading here.
554 // This also is critical in cases where the original thread gets stalled
555 // even in non-circularity situations.
556 // Note: must call resolve_super_or_fail even if null super -
557 // to force placeholder entry creation for this class for circularity detection
558 // Caller must check for pending exception
559 // Returns non-null Klass* if other thread has completed load
560 // and we are done,
561 // If return null Klass* and no pending exception, the caller must load the class
562 InstanceKlass* SystemDictionary::handle_parallel_super_load(
563 Symbol* name, Symbol* superclassname, Handle class_loader,
564 Handle protection_domain, Handle lockObject, TRAPS) {
565
566 ClassLoaderData* loader_data = class_loader_data(class_loader);
567 Dictionary* dictionary = loader_data->dictionary();
568 unsigned int d_hash = dictionary->compute_hash(name);
569 unsigned int p_hash = placeholders()->compute_hash(name);
570 int p_index = placeholders()->hash_to_index(p_hash);
571
572 // superk is not used, resolve_super called for circularity check only
573 // This code is reached in two situations. One if this thread
574 // is loading the same class twice (e.g. ClassCircularity, or
575 // java.lang.instrument).
576 // The second is if another thread started the resolve_super first
577 // and has not yet finished.
578 // In both cases the original caller will clean up the placeholder
579 // entry on error.
580 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
581 superclassname,
582 class_loader,
583 protection_domain,
584 true,
585 CHECK_NULL);
586
587 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
588 // Serial class loaders and bootstrap classloader do wait for superclass loads
589 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
590 MutexLocker mu(SystemDictionary_lock, THREAD);
591 // Check if classloading completed while we were loading superclass or waiting
592 return find_class(d_hash, name, dictionary);
593 }
594
595 // must loop to both handle other placeholder updates
596 // and spurious notifications
597 bool super_load_in_progress = true;
598 PlaceholderEntry* placeholder;
599 while (super_load_in_progress) {
600 MutexLocker mu(SystemDictionary_lock, THREAD);
601 // Check if classloading completed while we were loading superclass or waiting
602 InstanceKlass* check = find_class(d_hash, name, dictionary);
603 if (check != NULL) {
604 // Klass is already loaded, so just return it
605 return check;
606 } else {
607 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
608 if (placeholder && placeholder->super_load_in_progress() ){
609 // We only get here if the application has released the
610 // classloader lock when another thread was in the middle of loading a
611 // superclass/superinterface for this class, and now
612 // this thread is also trying to load this class.
613 // To minimize surprises, the first thread that started to
614 // load a class should be the one to complete the loading
615 // with the classfile it initially expected.
616 // This logic has the current thread wait once it has done
617 // all the superclass/superinterface loading it can, until
618 // the original thread completes the class loading or fails
619 // If it completes we will use the resulting InstanceKlass
620 // which we will find below in the systemDictionary.
621 // We also get here for parallel bootstrap classloader
622 if (class_loader.is_null()) {
623 SystemDictionary_lock->wait();
624 } else {
625 double_lock_wait(lockObject, THREAD);
626 }
627 } else {
628 // If not in SD and not in PH, other thread's load must have failed
629 super_load_in_progress = false;
630 }
631 }
632 }
633 return NULL;
634 }
635
636 static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
637 assert(event != NULL, "invariant");
638 assert(k != NULL, "invariant");
639 assert(event->should_commit(), "invariant");
640 event->set_loadedClass(k);
641 event->set_definingClassLoader(k->class_loader_data());
642 event->set_initiatingClassLoader(init_cld);
643 event->commit();
644 }
645
646
647 // Be careful when modifying this code: once you have run
648 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
649 // you need to find_and_remove it before returning.
650 // So be careful to not exit with a CHECK_ macro betweeen these calls.
651 //
652 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
653 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
654 Handle class_loader,
655 Handle protection_domain,
656 TRAPS) {
657 assert(name != NULL && !FieldType::is_array(name) &&
658 !FieldType::is_obj(name), "invalid class name");
659
660 EventClassLoad class_load_start_event;
661
662 HandleMark hm(THREAD);
663
664 // Fix for 4474172; see evaluation for more details
665 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
666 ClassLoaderData* loader_data = register_loader(class_loader);
667 Dictionary* dictionary = loader_data->dictionary();
668 unsigned int d_hash = dictionary->compute_hash(name);
669
670 // Do lookup to see if class already exist and the protection domain
671 // has the right access
672 // This call uses find which checks protection domain already matches
673 // All subsequent calls use find_class, and set has_loaded_class so that
674 // before we return a result we call out to java to check for valid protection domain
675 // to allow returning the Klass* and add it to the pd_set if it is valid
676 {
677 InstanceKlass* probe = dictionary->find(d_hash, name, protection_domain);
678 if (probe != NULL) return probe;
679 }
680
681 // Non-bootstrap class loaders will call out to class loader and
682 // define via jvm/jni_DefineClass which will acquire the
683 // class loader object lock to protect against multiple threads
684 // defining the class in parallel by accident.
685 // This lock must be acquired here so the waiter will find
686 // any successful result in the SystemDictionary and not attempt
687 // the define.
688 // ParallelCapable Classloaders and the bootstrap classloader
689 // do not acquire lock here.
690 bool DoObjectLock = true;
691 if (is_parallelCapable(class_loader)) {
692 DoObjectLock = false;
693 }
694
695 unsigned int p_hash = placeholders()->compute_hash(name);
696 int p_index = placeholders()->hash_to_index(p_hash);
697
698 // Class is not in SystemDictionary so we have to do loading.
699 // Make sure we are synchronized on the class loader before we proceed
700 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
701 check_loader_lock_contention(lockObject, THREAD);
702 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
703
704 // Check again (after locking) if class already exist in SystemDictionary
705 bool class_has_been_loaded = false;
706 bool super_load_in_progress = false;
707 bool havesupername = false;
708 InstanceKlass* k = NULL;
709 PlaceholderEntry* placeholder;
710 Symbol* superclassname = NULL;
711
712 assert(THREAD->can_call_java(),
713 "can not load classes with compiler thread: class=%s, classloader=%s",
714 name->as_C_string(),
715 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
716 {
717 MutexLocker mu(SystemDictionary_lock, THREAD);
718 InstanceKlass* check = find_class(d_hash, name, dictionary);
719 if (check != NULL) {
720 // InstanceKlass is already loaded, so just return it
721 class_has_been_loaded = true;
722 k = check;
723 } else {
724 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
725 if (placeholder && placeholder->super_load_in_progress()) {
726 super_load_in_progress = true;
727 if (placeholder->havesupername() == true) {
728 superclassname = placeholder->supername();
729 havesupername = true;
730 }
731 }
732 }
733 }
734
735 // If the class is in the placeholder table, class loading is in progress
736 if (super_load_in_progress && havesupername==true) {
737 k = handle_parallel_super_load(name,
738 superclassname,
739 class_loader,
740 protection_domain,
741 lockObject, THREAD);
742 if (HAS_PENDING_EXCEPTION) {
743 return NULL;
744 }
745 if (k != NULL) {
746 class_has_been_loaded = true;
747 }
748 }
749
750 bool throw_circularity_error = false;
751 if (!class_has_been_loaded) {
752 bool load_instance_added = false;
753
754 // add placeholder entry to record loading instance class
755 // Five cases:
756 // All cases need to prevent modifying bootclasssearchpath
757 // in parallel with a classload of same classname
758 // Redefineclasses uses existence of the placeholder for the duration
759 // of the class load to prevent concurrent redefinition of not completely
760 // defined classes.
761 // case 1. traditional classloaders that rely on the classloader object lock
762 // - no other need for LOAD_INSTANCE
763 // case 2. traditional classloaders that break the classloader object lock
764 // as a deadlock workaround. Detection of this case requires that
765 // this check is done while holding the classloader object lock,
766 // and that lock is still held when calling classloader's loadClass.
767 // For these classloaders, we ensure that the first requestor
768 // completes the load and other requestors wait for completion.
769 // case 3. Bootstrap classloader - don't own objectLocker
770 // This classloader supports parallelism at the classloader level,
771 // but only allows a single load of a class/classloader pair.
772 // No performance benefit and no deadlock issues.
773 // case 4. parallelCapable user level classloaders - without objectLocker
774 // Allow parallel classloading of a class/classloader pair
775
776 {
777 MutexLocker mu(SystemDictionary_lock, THREAD);
778 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
779 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
780 if (oldprobe) {
781 // only need check_seen_thread once, not on each loop
782 // 6341374 java/lang/Instrument with -Xcomp
783 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
784 throw_circularity_error = true;
785 } else {
786 // case 1: traditional: should never see load_in_progress.
787 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
788
789 // case 3: bootstrap classloader: prevent futile classloading,
790 // wait on first requestor
791 if (class_loader.is_null()) {
792 SystemDictionary_lock->wait();
793 } else {
794 // case 2: traditional with broken classloader lock. wait on first
795 // requestor.
796 double_lock_wait(lockObject, THREAD);
797 }
798 // Check if classloading completed while we were waiting
799 InstanceKlass* check = find_class(d_hash, name, dictionary);
800 if (check != NULL) {
801 // Klass is already loaded, so just return it
802 k = check;
803 class_has_been_loaded = true;
804 }
805 // check if other thread failed to load and cleaned up
806 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
807 }
808 }
809 }
810 }
811 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
812 // case 4: parallelCapable: allow competing threads to try
813 // LOAD_INSTANCE in parallel
814
815 if (!throw_circularity_error && !class_has_been_loaded) {
816 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
817 load_instance_added = true;
818 // For class loaders that do not acquire the classloader object lock,
819 // if they did not catch another thread holding LOAD_INSTANCE,
820 // need a check analogous to the acquire ObjectLocker/find_class
821 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
822 // one final check if the load has already completed
823 // class loaders holding the ObjectLock shouldn't find the class here
824 InstanceKlass* check = find_class(d_hash, name, dictionary);
825 if (check != NULL) {
826 // Klass is already loaded, so return it after checking/adding protection domain
827 k = check;
828 class_has_been_loaded = true;
829 }
830 }
831 }
832
833 // must throw error outside of owning lock
834 if (throw_circularity_error) {
835 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
836 ResourceMark rm(THREAD);
837 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
838 }
839
840 if (!class_has_been_loaded) {
841
842 // Do actual loading
843 k = load_instance_class(name, class_loader, THREAD);
844
845 // If everything was OK (no exceptions, no null return value), and
846 // class_loader is NOT the defining loader, do a little more bookkeeping.
847 if (!HAS_PENDING_EXCEPTION && k != NULL &&
848 k->class_loader() != class_loader()) {
849
850 check_constraints(d_hash, k, class_loader, false, THREAD);
851
852 // Need to check for a PENDING_EXCEPTION again; check_constraints
853 // can throw but we may have to remove entry from the placeholder table below.
854 if (!HAS_PENDING_EXCEPTION) {
855 // Record dependency for non-parent delegation.
856 // This recording keeps the defining class loader of the klass (k) found
857 // from being unloaded while the initiating class loader is loaded
858 // even if the reference to the defining class loader is dropped
859 // before references to the initiating class loader.
860 loader_data->record_dependency(k);
861
862 { // Grabbing the Compile_lock prevents systemDictionary updates
863 // during compilations.
864 MutexLocker mu(Compile_lock, THREAD);
865 update_dictionary(d_hash, p_index, p_hash,
866 k, class_loader, THREAD);
867 }
868
869 if (JvmtiExport::should_post_class_load()) {
870 Thread *thread = THREAD;
871 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
872 JvmtiExport::post_class_load((JavaThread *) thread, k);
873 }
874 }
875 }
876 } // load_instance_class
877
878 if (load_instance_added == true) {
879 // clean up placeholder entries for LOAD_INSTANCE success or error
880 // This brackets the SystemDictionary updates for both defining
881 // and initiating loaders
882 MutexLocker mu(SystemDictionary_lock, THREAD);
883 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
884 SystemDictionary_lock->notify_all();
885 }
886 }
887
888 if (HAS_PENDING_EXCEPTION || k == NULL) {
889 return NULL;
890 }
891 if (class_load_start_event.should_commit()) {
892 post_class_load_event(&class_load_start_event, k, loader_data);
893 }
894 #ifdef ASSERT
895 {
896 ClassLoaderData* loader_data = k->class_loader_data();
897 MutexLocker mu(SystemDictionary_lock, THREAD);
898 InstanceKlass* kk = find_class(name, loader_data);
899 assert(kk == k, "should be present in dictionary");
900 }
901 #endif
902
903 // return if the protection domain in NULL
904 if (protection_domain() == NULL) return k;
905
906 // Check the protection domain has the right access
907 if (dictionary->is_valid_protection_domain(d_hash, name,
908 protection_domain)) {
909 return k;
910 }
911
912 // Verify protection domain. If it fails an exception is thrown
913 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
914
915 return k;
916 }
917
918
919 // This routine does not lock the system dictionary.
920 //
921 // Since readers don't hold a lock, we must make sure that system
922 // dictionary entries are only removed at a safepoint (when only one
923 // thread is running), and are added to in a safe way (all links must
924 // be updated in an MT-safe manner).
925 //
926 // Callers should be aware that an entry could be added just after
927 // _dictionary->bucket(index) is read here, so the caller will not see
928 // the new entry.
929
930 Klass* SystemDictionary::find(Symbol* class_name,
931 Handle class_loader,
932 Handle protection_domain,
933 TRAPS) {
934
935 // The result of this call should be consistent with the result
936 // of the call to resolve_instance_class_or_null().
937 // See evaluation 6790209 and 4474172 for more details.
938 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
939 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
940
941 if (loader_data == NULL) {
942 // If the ClassLoaderData has not been setup,
943 // then the class loader has no entries in the dictionary.
944 return NULL;
945 }
946
947 Dictionary* dictionary = loader_data->dictionary();
948 unsigned int d_hash = dictionary->compute_hash(class_name);
949 return dictionary->find(d_hash, class_name,
950 protection_domain);
951 }
952
953
954 // Look for a loaded instance or array klass by name. Do not do any loading.
955 // return NULL in case of error.
956 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
957 Handle class_loader,
958 Handle protection_domain,
959 TRAPS) {
960 Klass* k = NULL;
961 assert(class_name != NULL, "class name must be non NULL");
962
963 if (FieldType::is_array(class_name)) {
964 // The name refers to an array. Parse the name.
965 // dimension and object_key in FieldArrayInfo are assigned as a
966 // side-effect of this call
967 FieldArrayInfo fd;
968 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
969 if (t != T_OBJECT) {
970 k = Universe::typeArrayKlassObj(t);
971 } else {
972 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
973 }
974 if (k != NULL) {
975 k = k->array_klass_or_null(fd.dimension());
976 }
977 } else {
978 k = find(class_name, class_loader, protection_domain, THREAD);
979 }
980 return k;
981 }
982
983 // Note: this method is much like resolve_from_stream, but
984 // does not publish the classes via the SystemDictionary.
985 // Handles unsafe_DefineAnonymousClass and redefineclasses
986 // RedefinedClasses do not add to the class hierarchy
987 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
988 Handle class_loader,
989 Handle protection_domain,
990 ClassFileStream* st,
991 const InstanceKlass* unsafe_anonymous_host,
992 GrowableArray<Handle>* cp_patches,
993 TRAPS) {
994
995 EventClassLoad class_load_start_event;
996
997 ClassLoaderData* loader_data;
998 if (unsafe_anonymous_host != NULL) {
999 // Create a new CLD for an unsafe anonymous class, that uses the same class loader
1000 // as the unsafe_anonymous_host
1001 guarantee(unsafe_anonymous_host->class_loader() == class_loader(), "should be the same");
1002 loader_data = ClassLoaderData::unsafe_anonymous_class_loader_data(class_loader);
1003 } else {
1004 loader_data = ClassLoaderData::class_loader_data(class_loader());
1005 }
1006
1007 assert(st != NULL, "invariant");
1008 assert(st->need_verify(), "invariant");
1009
1010 // Parse stream and create a klass.
1011 // Note that we do this even though this klass might
1012 // already be present in the SystemDictionary, otherwise we would not
1013 // throw potential ClassFormatErrors.
1014
1015 InstanceKlass* k = KlassFactory::create_from_stream(st,
1016 class_name,
1017 loader_data,
1018 protection_domain,
1019 unsafe_anonymous_host,
1020 cp_patches,
1021 CHECK_NULL);
1022
1023 if (unsafe_anonymous_host != NULL && k != NULL) {
1024 // Unsafe anonymous classes must update ClassLoaderData holder (was unsafe_anonymous_host loader)
1025 // so that they can be unloaded when the mirror is no longer referenced.
1026 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
1027
1028 {
1029 MutexLocker mu_r(Compile_lock, THREAD);
1030
1031 // Add to class hierarchy, initialize vtables, and do possible
1032 // deoptimizations.
1033 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1034 // But, do not add to dictionary.
1035 }
1036
1037 // Rewrite and patch constant pool here.
1038 k->link_class(CHECK_NULL);
1039 if (cp_patches != NULL) {
1040 k->constants()->patch_resolved_references(cp_patches);
1041 }
1042
1043 // If it's anonymous, initialize it now, since nobody else will.
1044 k->eager_initialize(CHECK_NULL);
1045
1046 // notify jvmti
1047 if (JvmtiExport::should_post_class_load()) {
1048 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1049 JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1050 }
1051 if (class_load_start_event.should_commit()) {
1052 post_class_load_event(&class_load_start_event, k, loader_data);
1053 }
1054 }
1055 assert(unsafe_anonymous_host != NULL || NULL == cp_patches,
1056 "cp_patches only found with unsafe_anonymous_host");
1057
1058 return k;
1059 }
1060
1061 // Add a klass to the system from a stream (called by jni_DefineClass and
1062 // JVM_DefineClass).
1063 // Note: class_name can be NULL. In that case we do not know the name of
1064 // the class until we have parsed the stream.
1065
1066 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1067 Handle class_loader,
1068 Handle protection_domain,
1069 ClassFileStream* st,
1070 TRAPS) {
1071
1072 HandleMark hm(THREAD);
1073
1074 // Classloaders that support parallelism, e.g. bootstrap classloader,
1075 // do not acquire lock here
1076 bool DoObjectLock = true;
1077 if (is_parallelCapable(class_loader)) {
1078 DoObjectLock = false;
1079 }
1080
1081 ClassLoaderData* loader_data = register_loader(class_loader);
1082
1083 // Make sure we are synchronized on the class loader before we proceed
1084 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1085 check_loader_lock_contention(lockObject, THREAD);
1086 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1087
1088 assert(st != NULL, "invariant");
1089
1090 // Parse the stream and create a klass.
1091 // Note that we do this even though this klass might
1092 // already be present in the SystemDictionary, otherwise we would not
1093 // throw potential ClassFormatErrors.
1094 InstanceKlass* k = NULL;
1095
1096 #if INCLUDE_CDS
1097 if (!DumpSharedSpaces) {
1098 k = SystemDictionaryShared::lookup_from_stream(class_name,
1099 class_loader,
1100 protection_domain,
1101 st,
1102 CHECK_NULL);
1103 }
1104 #endif
1105
1106 if (k == NULL) {
1107 if (st->buffer() == NULL) {
1108 return NULL;
1109 }
1110 k = KlassFactory::create_from_stream(st,
1111 class_name,
1112 loader_data,
1113 protection_domain,
1114 NULL, // unsafe_anonymous_host
1115 NULL, // cp_patches
1116 CHECK_NULL);
1117 }
1118
1119 assert(k != NULL, "no klass created");
1120 Symbol* h_name = k->name();
1121 assert(class_name == NULL || class_name == h_name, "name mismatch");
1122
1123 // Add class just loaded
1124 // If a class loader supports parallel classloading handle parallel define requests
1125 // find_or_define_instance_class may return a different InstanceKlass
1126 if (is_parallelCapable(class_loader)) {
1127 InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1128 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1129 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1130 assert(defined_k != NULL, "Should have a klass if there's no exception");
1131 loader_data->add_to_deallocate_list(k);
1132 k = defined_k;
1133 }
1134 } else {
1135 define_instance_class(k, THREAD);
1136 }
1137
1138 // If defining the class throws an exception register 'k' for cleanup.
1139 if (HAS_PENDING_EXCEPTION) {
1140 assert(k != NULL, "Must have an instance klass here!");
1141 loader_data->add_to_deallocate_list(k);
1142 return NULL;
1143 }
1144
1145 // Make sure we have an entry in the SystemDictionary on success
1146 debug_only( {
1147 MutexLocker mu(SystemDictionary_lock, THREAD);
1148
1149 Klass* check = find_class(h_name, k->class_loader_data());
1150 assert(check == k, "should be present in the dictionary");
1151 } );
1152
1153 return k;
1154 }
1155
1156 #if INCLUDE_CDS
1157 // Load a class for boot loader from the shared spaces. This also
1158 // forces the super class and all interfaces to be loaded.
1159 InstanceKlass* SystemDictionary::load_shared_boot_class(Symbol* class_name,
1160 TRAPS) {
1161 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1162 if (ik != NULL && ik->is_shared_boot_class()) {
1163 return load_shared_class(ik, Handle(), Handle(), NULL, THREAD);
1164 }
1165 return NULL;
1166 }
1167
1168 // Check if a shared class can be loaded by the specific classloader:
1169 //
1170 // NULL classloader:
1171 // - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1172 // - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1173 // be defined in an unnamed module.
1174 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1175 InstanceKlass* ik,
1176 Handle class_loader, TRAPS) {
1177 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1178 "Cannot use sharing if java.base is patched");
1179 ResourceMark rm;
1180 int path_index = ik->shared_classpath_index();
1181 ClassLoaderData* loader_data = class_loader_data(class_loader);
1182 if (path_index < 0) {
1183 // path_index < 0 indicates that the class is intended for a custom loader
1184 // and should not be loaded by boot/platform/app loaders
1185 if (loader_data->is_builtin_class_loader_data()) {
1186 return false;
1187 } else {
1188 return true;
1189 }
1190 }
1191 SharedClassPathEntry* ent =
1192 (SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
1193 if (!Universe::is_module_initialized()) {
1194 assert(ent != NULL && ent->is_modules_image(),
1195 "Loading non-bootstrap classes before the module system is initialized");
1196 assert(class_loader.is_null(), "sanity");
1197 return true;
1198 }
1199 // Get the pkg_entry from the classloader
1200 TempNewSymbol pkg_name = NULL;
1201 PackageEntry* pkg_entry = NULL;
1202 ModuleEntry* mod_entry = NULL;
1203 pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
1204 if (pkg_name != NULL) {
1205 if (loader_data != NULL) {
1206 pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1207 }
1208 if (pkg_entry != NULL) {
1209 mod_entry = pkg_entry->module();
1210 }
1211 }
1212
1213 // If the archived class is from a module that has been patched at runtime,
1214 // the class cannot be loaded from the archive.
1215 if (mod_entry != NULL && mod_entry->is_patched()) {
1216 return false;
1217 }
1218
1219 if (class_loader.is_null()) {
1220 assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1221 // The NULL classloader can load archived class originated from the
1222 // "modules" jimage and the -Xbootclasspath/a. For class from the
1223 // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1224 // by the NULL classloader.
1225 if (mod_entry != NULL) {
1226 // PackageEntry/ModuleEntry is found in the classloader. Check if the
1227 // ModuleEntry's location agrees with the archived class' origination.
1228 if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1229 return true; // Module class from the "module" jimage
1230 }
1231 }
1232
1233 // If the archived class is not from the "module" jimage, the class can be
1234 // loaded by the NULL classloader if
1235 //
1236 // 1. the class is from the unamed package
1237 // 2. or, the class is not from a module defined in the NULL classloader
1238 // 3. or, the class is from an unamed module
1239 if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1240 // the class is from the -Xbootclasspath/a
1241 if (pkg_name == NULL ||
1242 pkg_entry == NULL ||
1243 pkg_entry->in_unnamed_module()) {
1244 assert(mod_entry == NULL ||
1245 mod_entry == loader_data->unnamed_module(),
1246 "the unnamed module is not defined in the classloader");
1247 return true;
1248 }
1249 }
1250 return false;
1251 } else {
1252 bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1253 ik, class_loader, pkg_name, pkg_entry, mod_entry, CHECK_(false));
1254 return res;
1255 }
1256 }
1257
1258 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1259 Handle class_loader,
1260 Handle protection_domain,
1261 const ClassFileStream *cfs,
1262 TRAPS) {
1263 assert(ik != NULL, "sanity");
1264 assert(!ik->is_unshareable_info_restored(), "shared class can be loaded only once");
1265 Symbol* class_name = ik->name();
1266
1267 bool visible = is_shared_class_visible(
1268 class_name, ik, class_loader, CHECK_NULL);
1269 if (!visible) {
1270 return NULL;
1271 }
1272
1273 // Resolve the superclass and interfaces. They must be the same
1274 // as in dump time, because the layout of <ik> depends on
1275 // the specific layout of ik->super() and ik->local_interfaces().
1276 //
1277 // If unexpected superclass or interfaces are found, we cannot
1278 // load <ik> from the shared archive.
1279
1280 if (ik->super() != NULL) {
1281 Symbol* cn = ik->super()->name();
1282 Klass *s = resolve_super_or_fail(class_name, cn,
1283 class_loader, protection_domain, true, CHECK_NULL);
1284 if (s != ik->super()) {
1285 // The dynamically resolved super class is not the same as the one we used during dump time,
1286 // so we cannot use ik.
1287 return NULL;
1288 } else {
1289 assert(s->is_shared(), "must be");
1290 }
1291 }
1292
1293 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1294 int num_interfaces = interfaces->length();
1295 for (int index = 0; index < num_interfaces; index++) {
1296 InstanceKlass* k = interfaces->at(index);
1297 Symbol* name = k->name();
1298 Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
1299 if (k != i) {
1300 // The dynamically resolved interface class is not the same as the one we used during dump time,
1301 // so we cannot use ik.
1302 return NULL;
1303 } else {
1304 assert(i->is_shared(), "must be");
1305 }
1306 }
1307
1308 InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1309 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1310 if (new_ik != NULL) {
1311 // The class is changed by CFLH. Return the new class. The shared class is
1312 // not used.
1313 return new_ik;
1314 }
1315
1316 // Adjust methods to recover missing data. They need addresses for
1317 // interpreter entry points and their default native method address
1318 // must be reset.
1319
1320 // Updating methods must be done under a lock so multiple
1321 // threads don't update these in parallel
1322 //
1323 // Shared classes are all currently loaded by either the bootstrap or
1324 // internal parallel class loaders, so this will never cause a deadlock
1325 // on a custom class loader lock.
1326
1327 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1328 {
1329 HandleMark hm(THREAD);
1330 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1331 check_loader_lock_contention(lockObject, THREAD);
1332 ObjectLocker ol(lockObject, THREAD, true);
1333 // prohibited package check assumes all classes loaded from archive call
1334 // restore_unshareable_info which calls ik->set_package()
1335 ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
1336 }
1337
1338 ik->print_class_load_logging(loader_data, NULL, NULL);
1339
1340 // For boot loader, ensure that GetSystemPackage knows that a class in this
1341 // package was loaded.
1342 if (class_loader.is_null()) {
1343 int path_index = ik->shared_classpath_index();
1344 ResourceMark rm;
1345 ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
1346 }
1347
1348 if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1349 // Only dump the classes that can be stored into CDS archive
1350 if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1351 ResourceMark rm(THREAD);
1352 classlist_file->print_cr("%s", ik->name()->as_C_string());
1353 classlist_file->flush();
1354 }
1355 }
1356
1357 // notify a class loaded from shared object
1358 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1359
1360 ik->set_has_passed_fingerprint_check(false);
1361 if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1362 uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1363 uint64_t cds_fp = ik->get_stored_fingerprint();
1364 if (aot_fp != 0 && aot_fp == cds_fp) {
1365 // This class matches with a class saved in an AOT library
1366 ik->set_has_passed_fingerprint_check(true);
1367 } else {
1368 ResourceMark rm;
1369 log_info(class, fingerprint)("%s : expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1370 }
1371 }
1372
1373 return ik;
1374 }
1375 #endif // INCLUDE_CDS
1376
1377 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1378
1379 if (class_loader.is_null()) {
1380 ResourceMark rm;
1381 PackageEntry* pkg_entry = NULL;
1382 bool search_only_bootloader_append = false;
1383 ClassLoaderData *loader_data = class_loader_data(class_loader);
1384
1385 // Find the package in the boot loader's package entry table.
1386 TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
1387 if (pkg_name != NULL) {
1388 pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1389 }
1390
1391 // Prior to attempting to load the class, enforce the boot loader's
1392 // visibility boundaries.
1393 if (!Universe::is_module_initialized()) {
1394 // During bootstrapping, prior to module initialization, any
1395 // class attempting to be loaded must be checked against the
1396 // java.base packages in the boot loader's PackageEntryTable.
1397 // No class outside of java.base is allowed to be loaded during
1398 // this bootstrapping window.
1399 if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1400 // Class is either in the unnamed package or in
1401 // a named package within the unnamed module. Either
1402 // case is outside of java.base, do not attempt to
1403 // load the class post java.base definition. If
1404 // java.base has not been defined, let the class load
1405 // and its package will be checked later by
1406 // ModuleEntryTable::verify_javabase_packages.
1407 if (ModuleEntryTable::javabase_defined()) {
1408 return NULL;
1409 }
1410 } else {
1411 // Check that the class' package is defined within java.base.
1412 ModuleEntry* mod_entry = pkg_entry->module();
1413 Symbol* mod_entry_name = mod_entry->name();
1414 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1415 return NULL;
1416 }
1417 }
1418 } else {
1419 // After the module system has been initialized, check if the class'
1420 // package is in a module defined to the boot loader.
1421 if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1422 // Class is either in the unnamed package, in a named package
1423 // within a module not defined to the boot loader or in a
1424 // a named package within the unnamed module. In all cases,
1425 // limit visibility to search for the class only in the boot
1426 // loader's append path.
1427 if (!ClassLoader::has_bootclasspath_append()) {
1428 // If there is no bootclasspath append entry, no need to continue
1429 // searching.
1430 return NULL;
1431 }
1432 search_only_bootloader_append = true;
1433 }
1434 }
1435
1436 // Prior to bootstrapping's module initialization, never load a class outside
1437 // of the boot loader's module path
1438 assert(Universe::is_module_initialized() ||
1439 !search_only_bootloader_append,
1440 "Attempt to load a class outside of boot loader's module path");
1441
1442 // Search for classes in the CDS archive.
1443 InstanceKlass* k = NULL;
1444 {
1445 #if INCLUDE_CDS
1446 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1447 k = load_shared_boot_class(class_name, THREAD);
1448 #endif
1449 }
1450
1451 if (k == NULL) {
1452 // Use VM class loader
1453 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1454 k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1455 }
1456
1457 // find_or_define_instance_class may return a different InstanceKlass
1458 if (k != NULL) {
1459 InstanceKlass* defined_k =
1460 find_or_define_instance_class(class_name, class_loader, k, THREAD);
1461 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1462 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1463 assert(defined_k != NULL, "Should have a klass if there's no exception");
1464 loader_data->add_to_deallocate_list(k);
1465 k = defined_k;
1466 } else if (HAS_PENDING_EXCEPTION) {
1467 loader_data->add_to_deallocate_list(k);
1468 return NULL;
1469 }
1470 }
1471 return k;
1472 } else {
1473 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1474 ResourceMark rm(THREAD);
1475
1476 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1477 JavaThread* jt = (JavaThread*) THREAD;
1478
1479 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1480 ClassLoader::perf_app_classload_selftime(),
1481 ClassLoader::perf_app_classload_count(),
1482 jt->get_thread_stat()->perf_recursion_counts_addr(),
1483 jt->get_thread_stat()->perf_timers_addr(),
1484 PerfClassTraceTime::CLASS_LOAD);
1485
1486 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1487 // Translate to external class name format, i.e., convert '/' chars to '.'
1488 Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1489
1490 JavaValue result(T_OBJECT);
1491
1492 InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1493
1494 // Call public unsynchronized loadClass(String) directly for all class loaders.
1495 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1496 // acquire a class-name based lock rather than the class loader object lock.
1497 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1498 JavaCalls::call_virtual(&result,
1499 class_loader,
1500 spec_klass,
1501 vmSymbols::loadClass_name(),
1502 vmSymbols::string_class_signature(),
1503 string,
1504 CHECK_NULL);
1505
1506 assert(result.get_type() == T_OBJECT, "just checking");
1507 oop obj = (oop) result.get_jobject();
1508
1509 // Primitive classes return null since forName() can not be
1510 // used to obtain any of the Class objects representing primitives or void
1511 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1512 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1513 // For user defined Java class loaders, check that the name returned is
1514 // the same as that requested. This check is done for the bootstrap
1515 // loader when parsing the class file.
1516 if (class_name == k->name()) {
1517 return k;
1518 }
1519 }
1520 // Class is not found or has the wrong name, return NULL
1521 return NULL;
1522 }
1523 }
1524
1525 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1526 EventClassDefine event;
1527 if (event.should_commit()) {
1528 event.set_definedClass(k);
1529 event.set_definingClassLoader(def_cld);
1530 event.commit();
1531 }
1532 }
1533
1534 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1535
1536 HandleMark hm(THREAD);
1537 ClassLoaderData* loader_data = k->class_loader_data();
1538 Handle class_loader_h(THREAD, loader_data->class_loader());
1539
1540 // for bootstrap and other parallel classloaders don't acquire lock,
1541 // use placeholder token
1542 // If a parallelCapable class loader calls define_instance_class instead of
1543 // find_or_define_instance_class to get here, we have a timing
1544 // hole with systemDictionary updates and check_constraints
1545 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1546 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1547 compute_loader_lock_object(class_loader_h, THREAD)),
1548 "define called without lock");
1549 }
1550
1551 // Check class-loading constraints. Throw exception if violation is detected.
1552 // Grabs and releases SystemDictionary_lock
1553 // The check_constraints/find_class call and update_dictionary sequence
1554 // must be "atomic" for a specific class/classloader pair so we never
1555 // define two different instanceKlasses for that class/classloader pair.
1556 // Existing classloaders will call define_instance_class with the
1557 // classloader lock held
1558 // Parallel classloaders will call find_or_define_instance_class
1559 // which will require a token to perform the define class
1560 Symbol* name_h = k->name();
1561 Dictionary* dictionary = loader_data->dictionary();
1562 unsigned int d_hash = dictionary->compute_hash(name_h);
1563 check_constraints(d_hash, k, class_loader_h, true, CHECK);
1564
1565 // Register class just loaded with class loader (placed in Vector)
1566 // Note we do this before updating the dictionary, as this can
1567 // fail with an OutOfMemoryError (if it does, we will *not* put this
1568 // class in the dictionary and will not update the class hierarchy).
1569 // JVMTI FollowReferences needs to find the classes this way.
1570 if (k->class_loader() != NULL) {
1571 methodHandle m(THREAD, Universe::loader_addClass_method());
1572 JavaValue result(T_VOID);
1573 JavaCallArguments args(class_loader_h);
1574 args.push_oop(Handle(THREAD, k->java_mirror()));
1575 JavaCalls::call(&result, m, &args, CHECK);
1576 }
1577
1578 // Add the new class. We need recompile lock during update of CHA.
1579 {
1580 unsigned int p_hash = placeholders()->compute_hash(name_h);
1581 int p_index = placeholders()->hash_to_index(p_hash);
1582
1583 MutexLocker mu_r(Compile_lock, THREAD);
1584
1585 // Add to class hierarchy, initialize vtables, and do possible
1586 // deoptimizations.
1587 add_to_hierarchy(k, CHECK); // No exception, but can block
1588
1589 // Add to systemDictionary - so other classes can see it.
1590 // Grabs and releases SystemDictionary_lock
1591 update_dictionary(d_hash, p_index, p_hash,
1592 k, class_loader_h, THREAD);
1593 }
1594 k->eager_initialize(THREAD);
1595
1596 // notify jvmti
1597 if (JvmtiExport::should_post_class_load()) {
1598 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1599 JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1600
1601 }
1602 post_class_define_event(k, loader_data);
1603 }
1604
1605 // Support parallel classloading
1606 // All parallel class loaders, including bootstrap classloader
1607 // lock a placeholder entry for this class/class_loader pair
1608 // to allow parallel defines of different classes for this class loader
1609 // With AllowParallelDefine flag==true, in case they do not synchronize around
1610 // FindLoadedClass/DefineClass, calls, we check for parallel
1611 // loading for them, wait if a defineClass is in progress
1612 // and return the initial requestor's results
1613 // This flag does not apply to the bootstrap classloader.
1614 // With AllowParallelDefine flag==false, call through to define_instance_class
1615 // which will throw LinkageError: duplicate class definition.
1616 // False is the requested default.
1617 // For better performance, the class loaders should synchronize
1618 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1619 // potentially waste time reading and parsing the bytestream.
1620 // Note: VM callers should ensure consistency of k/class_name,class_loader
1621 // Be careful when modifying this code: once you have run
1622 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1623 // you need to find_and_remove it before returning.
1624 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1625 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1626 InstanceKlass* k, TRAPS) {
1627
1628 Symbol* name_h = k->name(); // passed in class_name may be null
1629 ClassLoaderData* loader_data = class_loader_data(class_loader);
1630 Dictionary* dictionary = loader_data->dictionary();
1631
1632 unsigned int d_hash = dictionary->compute_hash(name_h);
1633
1634 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1635 unsigned int p_hash = placeholders()->compute_hash(name_h);
1636 int p_index = placeholders()->hash_to_index(p_hash);
1637 PlaceholderEntry* probe;
1638
1639 {
1640 MutexLocker mu(SystemDictionary_lock, THREAD);
1641 // First check if class already defined
1642 if (is_parallelDefine(class_loader)) {
1643 InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1644 if (check != NULL) {
1645 return check;
1646 }
1647 }
1648
1649 // Acquire define token for this class/classloader
1650 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1651 // Wait if another thread defining in parallel
1652 // All threads wait - even those that will throw duplicate class: otherwise
1653 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1654 // if other thread has not finished updating dictionary
1655 while (probe->definer() != NULL) {
1656 SystemDictionary_lock->wait();
1657 }
1658 // Only special cases allow parallel defines and can use other thread's results
1659 // Other cases fall through, and may run into duplicate defines
1660 // caught by finding an entry in the SystemDictionary
1661 if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1662 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1663 SystemDictionary_lock->notify_all();
1664 #ifdef ASSERT
1665 InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1666 assert(check != NULL, "definer missed recording success");
1667 #endif
1668 return probe->instance_klass();
1669 } else {
1670 // This thread will define the class (even if earlier thread tried and had an error)
1671 probe->set_definer(THREAD);
1672 }
1673 }
1674
1675 define_instance_class(k, THREAD);
1676
1677 Handle linkage_exception = Handle(); // null handle
1678
1679 // definer must notify any waiting threads
1680 {
1681 MutexLocker mu(SystemDictionary_lock, THREAD);
1682 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1683 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1684 if (probe != NULL) {
1685 if (HAS_PENDING_EXCEPTION) {
1686 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1687 CLEAR_PENDING_EXCEPTION;
1688 } else {
1689 probe->set_instance_klass(k);
1690 }
1691 probe->set_definer(NULL);
1692 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1693 SystemDictionary_lock->notify_all();
1694 }
1695 }
1696
1697 // Can't throw exception while holding lock due to rank ordering
1698 if (linkage_exception() != NULL) {
1699 THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1700 }
1701
1702 return k;
1703 }
1704
1705 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1706 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1707 if (class_loader.is_null()) {
1708 return Handle(THREAD, _system_loader_lock_obj);
1709 } else {
1710 return class_loader;
1711 }
1712 }
1713
1714 // This method is added to check how often we have to wait to grab loader
1715 // lock. The results are being recorded in the performance counters defined in
1716 // ClassLoader::_sync_systemLoaderLockContentionRate and
1717 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1718 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1719 if (!UsePerfData) {
1720 return;
1721 }
1722
1723 assert(!loader_lock.is_null(), "NULL lock object");
1724
1725 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1726 == ObjectSynchronizer::owner_other) {
1727 // contention will likely happen, so increment the corresponding
1728 // contention counter.
1729 if (loader_lock() == _system_loader_lock_obj) {
1730 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1731 } else {
1732 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1733 }
1734 }
1735 }
1736
1737 // ----------------------------------------------------------------------------
1738 // Lookup
1739
1740 InstanceKlass* SystemDictionary::find_class(unsigned int hash,
1741 Symbol* class_name,
1742 Dictionary* dictionary) {
1743 assert_locked_or_safepoint(SystemDictionary_lock);
1744 int index = dictionary->hash_to_index(hash);
1745 return dictionary->find_class(index, hash, class_name);
1746 }
1747
1748
1749 // Basic find on classes in the midst of being loaded
1750 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1751 ClassLoaderData* loader_data) {
1752 assert_locked_or_safepoint(SystemDictionary_lock);
1753 unsigned int p_hash = placeholders()->compute_hash(class_name);
1754 int p_index = placeholders()->hash_to_index(p_hash);
1755 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1756 }
1757
1758
1759 // Used for assertions and verification only
1760 // Precalculating the hash and index is an optimization because there are many lookups
1761 // before adding the class.
1762 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1763 assert_locked_or_safepoint(SystemDictionary_lock);
1764 #ifndef ASSERT
1765 guarantee(VerifyBeforeGC ||
1766 VerifyDuringGC ||
1767 VerifyBeforeExit ||
1768 VerifyDuringStartup ||
1769 VerifyAfterGC, "too expensive");
1770 #endif
1771
1772 Dictionary* dictionary = loader_data->dictionary();
1773 unsigned int d_hash = dictionary->compute_hash(class_name);
1774 return find_class(d_hash, class_name, dictionary);
1775 }
1776
1777
1778 // ----------------------------------------------------------------------------
1779 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1780 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1781 // before a new class is used.
1782
1783 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1784 assert(k != NULL, "just checking");
1785 assert_locked_or_safepoint(Compile_lock);
1786
1787 k->set_init_state(InstanceKlass::loaded);
1788 // make sure init_state store is already done.
1789 // The compiler reads the hierarchy outside of the Compile_lock.
1790 // Access ordering is used to add to hierarchy.
1791
1792 // Link into hierachy.
1793 k->append_to_sibling_list(); // add to superklass/sibling list
1794 k->process_interfaces(THREAD); // handle all "implements" declarations
1795
1796 // Now flush all code that depended on old class hierarchy.
1797 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1798 CodeCache::flush_dependents_on(k);
1799 }
1800
1801 // ----------------------------------------------------------------------------
1802 // GC support
1803
1804 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1805 // Note: anonymous classes are not in the SD.
1806 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1807
1808 bool unloading_occurred;
1809 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1810 {
1811 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1812 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1813 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1814 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1815 if (unloading_occurred) {
1816 MutexLocker ml2(is_concurrent ? Module_lock : NULL);
1817 JFR_ONLY(Jfr::on_unloading_classes();)
1818
1819 MutexLocker ml1(is_concurrent ? SystemDictionary_lock : NULL);
1820 ClassLoaderDataGraph::clean_module_and_package_info();
1821 constraints()->purge_loader_constraints();
1822 resolution_errors()->purge_resolution_errors();
1823 }
1824 }
1825
1826 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1827
1828 if (unloading_occurred) {
1829 SymbolTable::trigger_cleanup();
1830
1831 // Oops referenced by the protection domain cache table may get unreachable independently
1832 // of the class loader (eg. cached protection domain oops). So we need to
1833 // explicitly unlink them here.
1834 // All protection domain oops are linked to the caller class, so if nothing
1835 // unloads, this is not needed.
1836 _pd_cache_table->trigger_cleanup();
1837 }
1838
1839 return unloading_occurred;
1840 }
1841
1842 void SystemDictionary::oops_do(OopClosure* f, bool include_handles) {
1843 f->do_oop(&_java_system_loader);
1844 f->do_oop(&_java_platform_loader);
1845 f->do_oop(&_system_loader_lock_obj);
1846 CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1847
1848 // Visit extra methods
1849 invoke_method_table()->oops_do(f);
1850
1851 if (include_handles) {
1852 OopStorageSet::vm_global()->oops_do(f);
1853 }
1854 }
1855
1856 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1857 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1858 for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1859 it->push(well_known_klass_addr((WKID)id));
1860 }
1861 }
1862
1863 void SystemDictionary::methods_do(void f(Method*)) {
1864 // Walk methods in loaded classes
1865 MutexLocker ml(ClassLoaderDataGraph_lock);
1866 ClassLoaderDataGraph::methods_do(f);
1867 // Walk method handle intrinsics
1868 invoke_method_table()->methods_do(f);
1869 }
1870
1871 // ----------------------------------------------------------------------------
1872 // Initialization
1873
1874 void SystemDictionary::initialize(TRAPS) {
1875 // Allocate arrays
1876 _placeholders = new PlaceholderTable(_placeholder_table_size);
1877 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1878 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1879 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1880 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1881
1882 // Allocate private object used as system class loader lock
1883 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1884 // Initialize basic classes
1885 resolve_well_known_classes(CHECK);
1886 }
1887
1888 // Compact table of directions on the initialization of klasses:
1889 static const short wk_init_info[] = {
1890 #define WK_KLASS_INIT_INFO(name, symbol) \
1891 ((short)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol)),
1892
1893 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1894 #undef WK_KLASS_INIT_INFO
1895 0
1896 };
1897
1898 #ifdef ASSERT
1899 bool SystemDictionary::is_well_known_klass(Symbol* class_name) {
1900 int sid;
1901 for (int i = 0; (sid = wk_init_info[i]) != 0; i++) {
1902 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1903 if (class_name == symbol) {
1904 return true;
1905 }
1906 }
1907 return false;
1908 }
1909 #endif
1910
1911 bool SystemDictionary::resolve_wk_klass(WKID id, TRAPS) {
1912 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1913 int sid = wk_init_info[id - FIRST_WKID];
1914 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1915 InstanceKlass** klassp = &_well_known_klasses[id];
1916
1917 if ((*klassp) == NULL) {
1918 Klass* k = resolve_or_fail(symbol, true, CHECK_0);
1919 (*klassp) = InstanceKlass::cast(k);
1920 }
1921 return ((*klassp) != NULL);
1922 }
1923
1924 void SystemDictionary::resolve_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1925 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1926 for (int id = (int)start_id; id < (int)limit_id; id++) {
1927 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1928 resolve_wk_klass((WKID)id, CHECK);
1929 }
1930
1931 // move the starting value forward to the limit:
1932 start_id = limit_id;
1933 }
1934
1935 void SystemDictionary::resolve_well_known_classes(TRAPS) {
1936 assert(WK_KLASS(Object_klass) == NULL, "well-known classes should only be initialized once");
1937
1938 // Create the ModuleEntry for java.base. This call needs to be done here,
1939 // after vmSymbols::initialize() is called but before any classes are pre-loaded.
1940 ClassLoader::classLoader_init2(CHECK);
1941
1942 // Preload commonly used klasses
1943 WKID scan = FIRST_WKID;
1944 // first do Object, then String, Class
1945 #if INCLUDE_CDS
1946 if (UseSharedSpaces) {
1947 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1948
1949 // It's unsafe to access the archived heap regions before they
1950 // are fixed up, so we must do the fixup as early as possible
1951 // before the archived java objects are accessed by functions
1952 // such as java_lang_Class::restore_archived_mirror and
1953 // ConstantPool::restore_unshareable_info (restores the archived
1954 // resolved_references array object).
1955 //
1956 // HeapShared::fixup_mapped_heap_regions() fills the empty
1957 // spaces in the archived heap regions and may use
1958 // SystemDictionary::Object_klass(), so we can do this only after
1959 // Object_klass is resolved. See the above resolve_wk_klasses_through()
1960 // call. No mirror objects are accessed/restored in the above call.
1961 // Mirrors are restored after java.lang.Class is loaded.
1962 HeapShared::fixup_mapped_heap_regions();
1963
1964 // Initialize the constant pool for the Object_class
1965 assert(Object_klass()->is_shared(), "must be");
1966 Object_klass()->constants()->restore_unshareable_info(CHECK);
1967 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1968 } else
1969 #endif
1970 {
1971 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1972 }
1973
1974 assert(WK_KLASS(Object_klass) != NULL, "well-known classes should now be initialized");
1975
1976 java_lang_Object::register_natives(CHECK);
1977
1978 // Calculate offsets for String and Class classes since they are loaded and
1979 // can be used after this point.
1980 java_lang_String::compute_offsets();
1981 java_lang_Class::compute_offsets();
1982
1983 // Fixup mirrors for classes loaded before java.lang.Class.
1984 // These calls iterate over the objects currently in the perm gen
1985 // so calling them at this point is matters (not before when there
1986 // are fewer objects and not later after there are more objects
1987 // in the perm gen.
1988 Universe::initialize_basic_type_mirrors(CHECK);
1989 Universe::fixup_mirrors(CHECK);
1990
1991 // do a bunch more:
1992 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1993
1994 // Preload ref klasses and set reference types
1995 WK_KLASS(Reference_klass)->set_reference_type(REF_OTHER);
1996 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1997
1998 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
1999 WK_KLASS(SoftReference_klass)->set_reference_type(REF_SOFT);
2000 WK_KLASS(WeakReference_klass)->set_reference_type(REF_WEAK);
2001 WK_KLASS(FinalReference_klass)->set_reference_type(REF_FINAL);
2002 WK_KLASS(PhantomReference_klass)->set_reference_type(REF_PHANTOM);
2003
2004 // JSR 292 classes
2005 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2006 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2007 resolve_wk_klasses_until(jsr292_group_start, scan, CHECK);
2008 resolve_wk_klasses_through(jsr292_group_end, scan, CHECK);
2009 WKID last = WKID_LIMIT;
2010 resolve_wk_klasses_until(last, scan, CHECK);
2011
2012 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2013 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
2014 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
2015 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
2016 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
2017 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
2018 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
2019 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
2020 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
2021 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
2022
2023 #ifdef ASSERT
2024 if (UseSharedSpaces) {
2025 assert(JvmtiExport::is_early_phase(),
2026 "All well known classes must be resolved in JVMTI early phase");
2027 for (int i = FIRST_WKID; i < last; i++) {
2028 InstanceKlass* k = _well_known_klasses[i];
2029 assert(k->is_shared(), "must not be replaced by JVMTI class file load hook");
2030 }
2031 }
2032 #endif
2033 }
2034
2035 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2036 // If so, returns the basic type it holds. If not, returns T_OBJECT.
2037 BasicType SystemDictionary::box_klass_type(Klass* k) {
2038 assert(k != NULL, "");
2039 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2040 if (_box_klasses[i] == k)
2041 return (BasicType)i;
2042 }
2043 return T_OBJECT;
2044 }
2045
2046 // Constraints on class loaders. The details of the algorithm can be
2047 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2048 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
2049 // that the dictionary needs to maintain a set of contraints that
2050 // must be satisfied by all classes in the dictionary.
2051 // if defining is true, then LinkageError if already in dictionary
2052 // if initiating loader, then ok if InstanceKlass matches existing entry
2053
2054 void SystemDictionary::check_constraints(unsigned int d_hash,
2055 InstanceKlass* k,
2056 Handle class_loader,
2057 bool defining,
2058 TRAPS) {
2059 ResourceMark rm(THREAD);
2060 stringStream ss;
2061 bool throwException = false;
2062
2063 {
2064 Symbol *name = k->name();
2065 ClassLoaderData *loader_data = class_loader_data(class_loader);
2066
2067 MutexLocker mu(SystemDictionary_lock, THREAD);
2068
2069 InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2070 if (check != NULL) {
2071 // If different InstanceKlass - duplicate class definition,
2072 // else - ok, class loaded by a different thread in parallel.
2073 // We should only have found it if it was done loading and ok to use.
2074 // The dictionary only holds instance classes, placeholders
2075 // also hold array classes.
2076
2077 assert(check->is_instance_klass(), "noninstance in systemdictionary");
2078 if ((defining == true) || (k != check)) {
2079 throwException = true;
2080 ss.print("loader %s", loader_data->loader_name_and_id());
2081 ss.print(" attempted duplicate %s definition for %s. (%s)",
2082 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
2083 } else {
2084 return;
2085 }
2086 }
2087
2088 #ifdef ASSERT
2089 Symbol* ph_check = find_placeholder(name, loader_data);
2090 assert(ph_check == NULL || ph_check == name, "invalid symbol");
2091 #endif
2092
2093 if (throwException == false) {
2094 if (constraints()->check_or_update(k, class_loader, name) == false) {
2095 throwException = true;
2096 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
2097 ss.print(" wants to load %s %s.",
2098 k->external_kind(), k->external_name());
2099 Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
2100 if (existing_klass != NULL && existing_klass->class_loader() != class_loader()) {
2101 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
2102 existing_klass->external_kind(),
2103 existing_klass->class_loader_data()->loader_name_and_id(),
2104 existing_klass->class_in_module_of_loader(false, true));
2105 } else {
2106 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
2107 }
2108 }
2109 }
2110 }
2111
2112 // Throw error now if needed (cannot throw while holding
2113 // SystemDictionary_lock because of rank ordering)
2114 if (throwException == true) {
2115 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
2116 }
2117 }
2118
2119 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2120 // have been called.
2121 void SystemDictionary::update_dictionary(unsigned int d_hash,
2122 int p_index, unsigned int p_hash,
2123 InstanceKlass* k,
2124 Handle class_loader,
2125 TRAPS) {
2126 // Compile_lock prevents systemDictionary updates during compilations
2127 assert_locked_or_safepoint(Compile_lock);
2128 Symbol* name = k->name();
2129 ClassLoaderData *loader_data = class_loader_data(class_loader);
2130
2131 {
2132 MutexLocker mu1(SystemDictionary_lock, THREAD);
2133
2134 // Make a new dictionary entry.
2135 Dictionary* dictionary = loader_data->dictionary();
2136 InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2137 if (sd_check == NULL) {
2138 dictionary->add_klass(d_hash, name, k);
2139 }
2140 #ifdef ASSERT
2141 sd_check = find_class(d_hash, name, dictionary);
2142 assert (sd_check != NULL, "should have entry in dictionary");
2143 // Note: there may be a placeholder entry: for circularity testing
2144 // or for parallel defines
2145 #endif
2146 SystemDictionary_lock->notify_all();
2147 }
2148 }
2149
2150
2151 // Try to find a class name using the loader constraints. The
2152 // loader constraints might know about a class that isn't fully loaded
2153 // yet and these will be ignored.
2154 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2155 Symbol* class_name, Handle class_loader, TRAPS) {
2156
2157 // First see if it has been loaded directly.
2158 // Force the protection domain to be null. (This removes protection checks.)
2159 Handle no_protection_domain;
2160 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2161 no_protection_domain, CHECK_NULL);
2162 if (klass != NULL)
2163 return klass;
2164
2165 // Now look to see if it has been loaded elsewhere, and is subject to
2166 // a loader constraint that would require this loader to return the
2167 // klass that is already loaded.
2168 if (FieldType::is_array(class_name)) {
2169 // For array classes, their Klass*s are not kept in the
2170 // constraint table. The element Klass*s are.
2171 FieldArrayInfo fd;
2172 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2173 if (t != T_OBJECT) {
2174 klass = Universe::typeArrayKlassObj(t);
2175 } else {
2176 MutexLocker mu(SystemDictionary_lock, THREAD);
2177 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2178 }
2179 // If element class already loaded, allocate array klass
2180 if (klass != NULL) {
2181 klass = klass->array_klass_or_null(fd.dimension());
2182 }
2183 } else {
2184 MutexLocker mu(SystemDictionary_lock, THREAD);
2185 // Non-array classes are easy: simply check the constraint table.
2186 klass = constraints()->find_constrained_klass(class_name, class_loader);
2187 }
2188
2189 return klass;
2190 }
2191
2192
2193 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2194 Handle class_loader1,
2195 Handle class_loader2,
2196 Thread* THREAD) {
2197 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2198 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2199
2200 Symbol* constraint_name = NULL;
2201 // Needs to be in same scope as constraint_name in case a Symbol is created and
2202 // assigned to constraint_name.
2203 FieldArrayInfo fd;
2204 if (!FieldType::is_array(class_name)) {
2205 constraint_name = class_name;
2206 } else {
2207 // For array classes, their Klass*s are not kept in the
2208 // constraint table. The element classes are.
2209 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2210 // primitive types always pass
2211 if (t != T_OBJECT) {
2212 return true;
2213 } else {
2214 constraint_name = fd.object_key();
2215 }
2216 }
2217
2218 Dictionary* dictionary1 = loader_data1->dictionary();
2219 unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2220
2221 Dictionary* dictionary2 = loader_data2->dictionary();
2222 unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2223
2224 {
2225 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2226 InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2227 InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2228 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2229 klass2, class_loader2);
2230 }
2231 }
2232
2233 // Add entry to resolution error table to record the error when the first
2234 // attempt to resolve a reference to a class has failed.
2235 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2236 Symbol* error, Symbol* message) {
2237 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2238 int index = resolution_errors()->hash_to_index(hash);
2239 {
2240 MutexLocker ml(SystemDictionary_lock, Thread::current());
2241 resolution_errors()->add_entry(index, hash, pool, which, error, message);
2242 }
2243 }
2244
2245 // Delete a resolution error for RedefineClasses for a constant pool is going away
2246 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2247 resolution_errors()->delete_entry(pool);
2248 }
2249
2250 // Lookup resolution error table. Returns error if found, otherwise NULL.
2251 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2252 Symbol** message) {
2253 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2254 int index = resolution_errors()->hash_to_index(hash);
2255 {
2256 MutexLocker ml(SystemDictionary_lock, Thread::current());
2257 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2258 if (entry != NULL) {
2259 *message = entry->message();
2260 return entry->error();
2261 } else {
2262 return NULL;
2263 }
2264 }
2265 }
2266
2267
2268 // Signature constraints ensure that callers and callees agree about
2269 // the meaning of type names in their signatures. This routine is the
2270 // intake for constraints. It collects them from several places:
2271 //
2272 // * LinkResolver::resolve_method (if check_access is true) requires
2273 // that the resolving class (the caller) and the defining class of
2274 // the resolved method (the callee) agree on each type in the
2275 // method's signature.
2276 //
2277 // * LinkResolver::resolve_interface_method performs exactly the same
2278 // checks.
2279 //
2280 // * LinkResolver::resolve_field requires that the constant pool
2281 // attempting to link to a field agree with the field's defining
2282 // class about the type of the field signature.
2283 //
2284 // * klassVtable::initialize_vtable requires that, when a class
2285 // overrides a vtable entry allocated by a superclass, that the
2286 // overriding method (i.e., the callee) agree with the superclass
2287 // on each type in the method's signature.
2288 //
2289 // * klassItable::initialize_itable requires that, when a class fills
2290 // in its itables, for each non-abstract method installed in an
2291 // itable, the method (i.e., the callee) agree with the interface
2292 // on each type in the method's signature.
2293 //
2294 // All those methods have a boolean (check_access, checkconstraints)
2295 // which turns off the checks. This is used from specialized contexts
2296 // such as bootstrapping, dumping, and debugging.
2297 //
2298 // No direct constraint is placed between the class and its
2299 // supertypes. Constraints are only placed along linked relations
2300 // between callers and callees. When a method overrides or implements
2301 // an abstract method in a supertype (superclass or interface), the
2302 // constraints are placed as if the supertype were the caller to the
2303 // overriding method. (This works well, since callers to the
2304 // supertype have already established agreement between themselves and
2305 // the supertype.) As a result of all this, a class can disagree with
2306 // its supertype about the meaning of a type name, as long as that
2307 // class neither calls a relevant method of the supertype, nor is
2308 // called (perhaps via an override) from the supertype.
2309 //
2310 //
2311 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2312 //
2313 // Make sure all class components (including arrays) in the given
2314 // signature will be resolved to the same class in both loaders.
2315 // Returns the name of the type that failed a loader constraint check, or
2316 // NULL if no constraint failed. No exception except OOME is thrown.
2317 // Arrays are not added to the loader constraint table, their elements are.
2318 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2319 Handle loader1, Handle loader2,
2320 bool is_method, TRAPS) {
2321 // Nothing to do if loaders are the same.
2322 if (loader1() == loader2()) {
2323 return NULL;
2324 }
2325
2326 SignatureStream sig_strm(signature, is_method);
2327 while (!sig_strm.is_done()) {
2328 if (sig_strm.is_object()) {
2329 Symbol* sig = sig_strm.as_symbol();
2330 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2331 return sig;
2332 }
2333 }
2334 sig_strm.next();
2335 }
2336 return NULL;
2337 }
2338
2339
2340 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2341 Symbol* signature,
2342 TRAPS) {
2343 methodHandle empty;
2344 assert(MethodHandles::is_signature_polymorphic(iid) &&
2345 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2346 iid != vmIntrinsics::_invokeGeneric,
2347 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2348
2349 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2350 int index = invoke_method_table()->hash_to_index(hash);
2351 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2352 methodHandle m;
2353 if (spe == NULL || spe->method() == NULL) {
2354 spe = NULL;
2355 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2356 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_NULL);
2357 if (!Arguments::is_interpreter_only()) {
2358 // Generate a compiled form of the MH intrinsic.
2359 AdapterHandlerLibrary::create_native_wrapper(m);
2360 // Check if have the compiled code.
2361 if (!m->has_compiled_code()) {
2362 THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
2363 "Out of space in CodeCache for method handle intrinsic");
2364 }
2365 }
2366 // Now grab the lock. We might have to throw away the new method,
2367 // if a racing thread has managed to install one at the same time.
2368 {
2369 MutexLocker ml(SystemDictionary_lock, THREAD);
2370 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2371 if (spe == NULL)
2372 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2373 if (spe->method() == NULL)
2374 spe->set_method(m());
2375 }
2376 }
2377
2378 assert(spe != NULL && spe->method() != NULL, "");
2379 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2380 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2381 "MH intrinsic invariant");
2382 return spe->method();
2383 }
2384
2385 // Helper for unpacking the return value from linkMethod and linkCallSite.
2386 static Method* unpack_method_and_appendix(Handle mname,
2387 Klass* accessing_klass,
2388 objArrayHandle appendix_box,
2389 Handle* appendix_result,
2390 TRAPS) {
2391 if (mname.not_null()) {
2392 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2393 if (m != NULL) {
2394 oop appendix = appendix_box->obj_at(0);
2395 if (TraceMethodHandles) {
2396 #ifndef PRODUCT
2397 ttyLocker ttyl;
2398 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2399 m->print();
2400 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2401 tty->cr();
2402 #endif //PRODUCT
2403 }
2404 (*appendix_result) = Handle(THREAD, appendix);
2405 // the target is stored in the cpCache and if a reference to this
2406 // MemberName is dropped we need a way to make sure the
2407 // class_loader containing this method is kept alive.
2408 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2409 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2410 this_key->record_dependency(m->method_holder());
2411 return mh();
2412 }
2413 }
2414 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2415 }
2416
2417 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2418 Symbol* name,
2419 Symbol* signature,
2420 Klass* accessing_klass,
2421 Handle *appendix_result,
2422 TRAPS) {
2423 assert(THREAD->can_call_java() ,"");
2424 Handle method_type =
2425 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2426
2427 int ref_kind = JVM_REF_invokeVirtual;
2428 oop name_oop = StringTable::intern(name, CHECK_NULL);
2429 Handle name_str (THREAD, name_oop);
2430 objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_NULL);
2431 assert(appendix_box->obj_at(0) == NULL, "");
2432
2433 // This should not happen. JDK code should take care of that.
2434 if (accessing_klass == NULL || method_type.is_null()) {
2435 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2436 }
2437
2438 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2439 JavaCallArguments args;
2440 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2441 args.push_int(ref_kind);
2442 args.push_oop(Handle(THREAD, klass->java_mirror()));
2443 args.push_oop(name_str);
2444 args.push_oop(method_type);
2445 args.push_oop(appendix_box);
2446 JavaValue result(T_OBJECT);
2447 JavaCalls::call_static(&result,
2448 SystemDictionary::MethodHandleNatives_klass(),
2449 vmSymbols::linkMethod_name(),
2450 vmSymbols::linkMethod_signature(),
2451 &args, CHECK_NULL);
2452 Handle mname(THREAD, (oop) result.get_jobject());
2453 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2454 }
2455
2456 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2457 // We must ensure that all class loaders everywhere will reach this class, for any client.
2458 // This is a safe bet for public classes in java.lang, such as Object and String.
2459 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2460 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2461 static bool is_always_visible_class(oop mirror) {
2462 Klass* klass = java_lang_Class::as_Klass(mirror);
2463 if (klass->is_objArray_klass()) {
2464 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2465 }
2466 if (klass->is_typeArray_klass()) {
2467 return true; // primitive array
2468 }
2469 assert(klass->is_instance_klass(), "%s", klass->external_name());
2470 return klass->is_public() &&
2471 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang
2472 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke
2473 }
2474
2475
2476 // Return the Java mirror (java.lang.Class instance) for a single-character
2477 // descriptor. This result, when available, is the same as produced by the
2478 // heavier API point of the same name that takes a Symbol.
2479 oop SystemDictionary::find_java_mirror_for_type(char signature_char) {
2480 return java_lang_Class::primitive_mirror(char2type(signature_char));
2481 }
2482
2483 // Find or construct the Java mirror (java.lang.Class instance) for a
2484 // for the given field type signature, as interpreted relative to the
2485 // given class loader. Handles primitives, void, references, arrays,
2486 // and all other reflectable types, except method types.
2487 // N.B. Code in reflection should use this entry point.
2488 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2489 Klass* accessing_klass,
2490 Handle class_loader,
2491 Handle protection_domain,
2492 SignatureStream::FailureMode failure_mode,
2493 TRAPS) {
2494 Handle empty;
2495
2496 assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2497 "one or the other, or perhaps neither");
2498
2499 Symbol* type = signature;
2500
2501 // What we have here must be a valid field descriptor,
2502 // and all valid field descriptors are supported.
2503 // Produce the same java.lang.Class that reflection reports.
2504 if (type->utf8_length() == 1) {
2505
2506 // It's a primitive. (Void has a primitive mirror too.)
2507 char ch = type->char_at(0);
2508 assert(is_java_primitive(char2type(ch)) || ch == JVM_SIGNATURE_VOID, "");
2509 return Handle(THREAD, find_java_mirror_for_type(ch));
2510
2511 } else if (FieldType::is_obj(type) || FieldType::is_array(type)) {
2512
2513 // It's a reference type.
2514 if (accessing_klass != NULL) {
2515 class_loader = Handle(THREAD, accessing_klass->class_loader());
2516 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2517 }
2518 Klass* constant_type_klass;
2519 if (failure_mode == SignatureStream::ReturnNull) {
2520 constant_type_klass = resolve_or_null(type, class_loader, protection_domain,
2521 CHECK_(empty));
2522 } else {
2523 bool throw_error = (failure_mode == SignatureStream::NCDFError);
2524 constant_type_klass = resolve_or_fail(type, class_loader, protection_domain,
2525 throw_error, CHECK_(empty));
2526 }
2527 if (constant_type_klass == NULL) {
2528 return Handle(); // report failure this way
2529 }
2530 Handle mirror(THREAD, constant_type_klass->java_mirror());
2531
2532 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2533 if (accessing_klass != NULL) {
2534 Klass* sel_klass = constant_type_klass;
2535 bool fold_type_to_class = true;
2536 LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2537 fold_type_to_class, CHECK_(empty));
2538 }
2539
2540 return mirror;
2541
2542 }
2543
2544 // Fall through to an error.
2545 assert(false, "unsupported mirror syntax");
2546 THROW_MSG_(vmSymbols::java_lang_InternalError(), "unsupported mirror syntax", empty);
2547 }
2548
2549
2550 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2551 // signature, as interpreted relative to the given class loader.
2552 // Because of class loader constraints, all method handle usage must be
2553 // consistent with this loader.
2554 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2555 Klass* accessing_klass,
2556 TRAPS) {
2557 Handle empty;
2558 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2559 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2560 int index = invoke_method_table()->hash_to_index(hash);
2561 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2562 if (spe != NULL && spe->method_type() != NULL) {
2563 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2564 return Handle(THREAD, spe->method_type());
2565 } else if (!THREAD->can_call_java()) {
2566 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2567 return Handle(); // do not attempt from within compiler, unless it was cached
2568 }
2569
2570 Handle class_loader, protection_domain;
2571 if (accessing_klass != NULL) {
2572 class_loader = Handle(THREAD, accessing_klass->class_loader());
2573 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2574 }
2575 bool can_be_cached = true;
2576 int npts = ArgumentCount(signature).size();
2577 objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2578 int arg = 0;
2579 Handle rt; // the return type from the signature
2580 ResourceMark rm(THREAD);
2581 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2582 oop mirror = NULL;
2583 if (can_be_cached) {
2584 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2585 mirror = ss.as_java_mirror(Handle(), Handle(),
2586 SignatureStream::ReturnNull, CHECK_(empty));
2587 if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2588 // Fall back to accessing_klass context.
2589 can_be_cached = false;
2590 }
2591 }
2592 if (!can_be_cached) {
2593 // Resolve, throwing a real error if it doesn't work.
2594 mirror = ss.as_java_mirror(class_loader, protection_domain,
2595 SignatureStream::NCDFError, CHECK_(empty));
2596 }
2597 assert(mirror != NULL, "%s", ss.as_symbol()->as_C_string());
2598 if (ss.at_return_type())
2599 rt = Handle(THREAD, mirror);
2600 else
2601 pts->obj_at_put(arg++, mirror);
2602
2603 // Check accessibility.
2604 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2605 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2606 mirror = NULL; // safety
2607 // Emulate ConstantPool::verify_constant_pool_resolve.
2608 bool fold_type_to_class = true;
2609 LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
2610 fold_type_to_class, CHECK_(empty));
2611 }
2612 }
2613 assert(arg == npts, "");
2614
2615 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2616 JavaCallArguments args(Handle(THREAD, rt()));
2617 args.push_oop(pts);
2618 JavaValue result(T_OBJECT);
2619 JavaCalls::call_static(&result,
2620 SystemDictionary::MethodHandleNatives_klass(),
2621 vmSymbols::findMethodHandleType_name(),
2622 vmSymbols::findMethodHandleType_signature(),
2623 &args, CHECK_(empty));
2624 Handle method_type(THREAD, (oop) result.get_jobject());
2625
2626 if (can_be_cached) {
2627 // We can cache this MethodType inside the JVM.
2628 MutexLocker ml(SystemDictionary_lock, THREAD);
2629 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2630 if (spe == NULL)
2631 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2632 if (spe->method_type() == NULL) {
2633 spe->set_method_type(method_type());
2634 }
2635 }
2636
2637 // report back to the caller with the MethodType
2638 return method_type;
2639 }
2640
2641 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2642 Klass* accessing_klass,
2643 TRAPS) {
2644 Handle empty;
2645 ResourceMark rm(THREAD);
2646 SignatureStream ss(signature, /*is_method=*/ false);
2647 if (!ss.is_done()) {
2648 Handle class_loader, protection_domain;
2649 if (accessing_klass != NULL) {
2650 class_loader = Handle(THREAD, accessing_klass->class_loader());
2651 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2652 }
2653 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2654 ss.next();
2655 if (ss.is_done()) {
2656 return Handle(THREAD, mirror);
2657 }
2658 }
2659 return empty;
2660 }
2661
2662 // Ask Java code to find or construct a method handle constant.
2663 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2664 int ref_kind, //e.g., JVM_REF_invokeVirtual
2665 Klass* callee,
2666 Symbol* name,
2667 Symbol* signature,
2668 TRAPS) {
2669 Handle empty;
2670 if (caller == NULL) {
2671 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2672 }
2673 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2674 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2675
2676 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2677 Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2678 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2679 java_lang_invoke_MemberName::set_name (mname(), name_str());
2680 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2681 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2682
2683 if (ref_kind == JVM_REF_invokeVirtual &&
2684 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2685 // Skip resolution for public signature polymorphic methods such as
2686 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2687 // They require appendix argument which MemberName resolution doesn't handle.
2688 // There's special logic on JDK side to handle them
2689 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2690 } else {
2691 MethodHandles::resolve_MemberName(mname, caller, /*speculative_resolve*/false, CHECK_(empty));
2692 }
2693
2694 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2695 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2696
2697 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2698 JavaCallArguments args;
2699 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2700 args.push_int(ref_kind);
2701 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2702 args.push_oop(name_str);
2703 args.push_oop(type);
2704 JavaValue result(T_OBJECT);
2705 JavaCalls::call_static(&result,
2706 SystemDictionary::MethodHandleNatives_klass(),
2707 vmSymbols::linkMethodHandleConstant_name(),
2708 vmSymbols::linkMethodHandleConstant_signature(),
2709 &args, CHECK_(empty));
2710 return Handle(THREAD, (oop) result.get_jobject());
2711 }
2712
2713 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2714 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2715 // with linkage results being stored back into the bootstrap specifier.
2716 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2717 // Resolve the bootstrap specifier, its name, type, and static arguments
2718 bootstrap_specifier.resolve_bsm(CHECK);
2719
2720 // This should not happen. JDK code should take care of that.
2721 if (bootstrap_specifier.caller() == NULL || bootstrap_specifier.type_arg().is_null()) {
2722 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2723 }
2724
2725 bool is_indy = bootstrap_specifier.is_method_call();
2726 objArrayHandle appendix_box;
2727 if (is_indy) {
2728 // Some method calls may require an appendix argument. Arrange to receive it.
2729 appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK);
2730 assert(appendix_box->obj_at(0) == NULL, "");
2731 }
2732
2733 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, condy_index, bsm, type, info)
2734 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
2735 JavaCallArguments args;
2736 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2737 args.push_int(bootstrap_specifier.bss_index());
2738 args.push_oop(bootstrap_specifier.bsm());
2739 args.push_oop(bootstrap_specifier.name_arg());
2740 args.push_oop(bootstrap_specifier.type_arg());
2741 args.push_oop(bootstrap_specifier.arg_values());
2742 if (is_indy) {
2743 args.push_oop(appendix_box);
2744 }
2745 JavaValue result(T_OBJECT);
2746 JavaCalls::call_static(&result,
2747 SystemDictionary::MethodHandleNatives_klass(),
2748 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2749 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2750 &args, CHECK);
2751
2752 Handle value(THREAD, (oop) result.get_jobject());
2753 if (is_indy) {
2754 Handle appendix;
2755 Method* method = unpack_method_and_appendix(value,
2756 bootstrap_specifier.caller(),
2757 appendix_box,
2758 &appendix, CHECK);
2759 methodHandle mh(THREAD, method);
2760 bootstrap_specifier.set_resolved_method(mh, appendix);
2761 } else {
2762 bootstrap_specifier.set_resolved_value(value);
2763 }
2764
2765 // sanity check
2766 assert(bootstrap_specifier.is_resolved() ||
2767 (bootstrap_specifier.is_method_call() &&
2768 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2769 }
2770
2771 // Protection domain cache table handling
2772
2773 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2774 return _pd_cache_table->get(protection_domain);
2775 }
2776
2777 // ----------------------------------------------------------------------------
2778
2779 void SystemDictionary::print_on(outputStream *st) {
2780 CDS_ONLY(SystemDictionaryShared::print_on(st));
2781 GCMutexLocker mu(SystemDictionary_lock);
2782
2783 ClassLoaderDataGraph::print_dictionary(st);
2784
2785 // Placeholders
2786 placeholders()->print_on(st);
2787 st->cr();
2788
2789 // loader constraints - print under SD_lock
2790 constraints()->print_on(st);
2791 st->cr();
2792
2793 _pd_cache_table->print_on(st);
2794 st->cr();
2795 }
2796
2797 void SystemDictionary::print() { print_on(tty); }
2798
2799 void SystemDictionary::verify() {
2800 guarantee(constraints() != NULL,
2801 "Verify of loader constraints failed");
2802 guarantee(placeholders()->number_of_entries() >= 0,
2803 "Verify of placeholders failed");
2804
2805 GCMutexLocker mu(SystemDictionary_lock);
2806
2807 // Verify dictionary
2808 ClassLoaderDataGraph::verify_dictionary();
2809
2810 placeholders()->verify();
2811
2812 // Verify constraint table
2813 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2814 constraints()->verify(placeholders());
2815
2816 _pd_cache_table->verify();
2817 }
2818
2819 void SystemDictionary::dump(outputStream *st, bool verbose) {
2820 assert_locked_or_safepoint(SystemDictionary_lock);
2821 if (verbose) {
2822 print_on(st);
2823 } else {
2824 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2825 ClassLoaderDataGraph::print_table_statistics(st);
2826 placeholders()->print_table_statistics(st, "Placeholder Table");
2827 constraints()->print_table_statistics(st, "LoaderConstraints Table");
2828 pd_cache_table()->print_table_statistics(st, "ProtectionDomainCache Table");
2829 }
2830 }
2831
2832 TableStatistics SystemDictionary::placeholders_statistics() {
2833 MutexLocker ml(SystemDictionary_lock);
2834 return placeholders()->statistics_calculate();
2835 }
2836
2837 TableStatistics SystemDictionary::loader_constraints_statistics() {
2838 MutexLocker ml(SystemDictionary_lock);
2839 return constraints()->statistics_calculate();
2840 }
2841
2842 TableStatistics SystemDictionary::protection_domain_cache_statistics() {
2843 MutexLocker ml(SystemDictionary_lock);
2844 return pd_cache_table()->statistics_calculate();
2845 }
2846
2847 // Utility for dumping dictionaries.
2848 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2849 DCmdWithParser(output, heap),
2850 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2851 "BOOLEAN", false, "false") {
2852 _dcmdparser.add_dcmd_option(&_verbose);
2853 }
2854
2855 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2856 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2857 _verbose.value());
2858 VMThread::execute(&dumper);
2859 }
2860
2861 int SystemDictionaryDCmd::num_arguments() {
2862 ResourceMark rm;
2863 SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
2864 if (dcmd != NULL) {
2865 DCmdMark mark(dcmd);
2866 return dcmd->_dcmdparser.num_arguments();
2867 } else {
2868 return 0;
2869 }
2870 }