Sat, 28 Sep 2013 12:42:22 -0700
8025613: clang: remove -Wno-unused-value
Reviewed-by: iveresov
1 /*
2 * Copyright (c) 1997, 2013, 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 */
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderData.inline.hpp"
27 #include "classfile/dictionary.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/loaderConstraints.hpp"
30 #include "classfile/placeholders.hpp"
31 #include "classfile/resolutionErrors.hpp"
32 #include "classfile/systemDictionary.hpp"
33 #include "classfile/vmSymbols.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "interpreter/bytecodeStream.hpp"
36 #include "interpreter/interpreter.hpp"
37 #include "memory/gcLocker.hpp"
38 #include "memory/oopFactory.hpp"
39 #include "oops/instanceKlass.hpp"
40 #include "oops/instanceRefKlass.hpp"
41 #include "oops/klass.inline.hpp"
42 #include "oops/methodData.hpp"
43 #include "oops/objArrayKlass.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "oops/oop.inline2.hpp"
46 #include "oops/typeArrayKlass.hpp"
47 #include "prims/jvmtiEnvBase.hpp"
48 #include "prims/methodHandles.hpp"
49 #include "runtime/biasedLocking.hpp"
50 #include "runtime/fieldType.hpp"
51 #include "runtime/handles.inline.hpp"
52 #include "runtime/java.hpp"
53 #include "runtime/javaCalls.hpp"
54 #include "runtime/mutexLocker.hpp"
55 #include "runtime/signature.hpp"
56 #include "services/classLoadingService.hpp"
57 #include "services/threadService.hpp"
59 #if INCLUDE_TRACE
60 #include "trace/tracing.hpp"
61 #include "trace/traceMacros.hpp"
62 #endif
65 Dictionary* SystemDictionary::_dictionary = NULL;
66 PlaceholderTable* SystemDictionary::_placeholders = NULL;
67 Dictionary* SystemDictionary::_shared_dictionary = NULL;
68 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
69 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
70 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
73 int SystemDictionary::_number_of_modifications = 0;
74 int SystemDictionary::_sdgeneration = 0;
75 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
76 20201,40423,99991};
78 oop SystemDictionary::_system_loader_lock_obj = NULL;
80 Klass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
81 = { NULL /*, NULL...*/ };
83 Klass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
85 oop SystemDictionary::_java_system_loader = NULL;
87 bool SystemDictionary::_has_loadClassInternal = false;
88 bool SystemDictionary::_has_checkPackageAccess = false;
90 // lazily initialized klass variables
91 Klass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
94 // ----------------------------------------------------------------------------
95 // Java-level SystemLoader
97 oop SystemDictionary::java_system_loader() {
98 return _java_system_loader;
99 }
101 void SystemDictionary::compute_java_system_loader(TRAPS) {
102 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
103 JavaValue result(T_OBJECT);
104 JavaCalls::call_static(&result,
105 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
106 vmSymbols::getSystemClassLoader_name(),
107 vmSymbols::void_classloader_signature(),
108 CHECK);
110 _java_system_loader = (oop)result.get_jobject();
111 }
114 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
115 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
116 return ClassLoaderDataGraph::find_or_create(class_loader, CHECK_NULL);
117 }
119 // ----------------------------------------------------------------------------
120 // debugging
122 #ifdef ASSERT
124 // return true if class_name contains no '.' (internal format is '/')
125 bool SystemDictionary::is_internal_format(Symbol* class_name) {
126 if (class_name != NULL) {
127 ResourceMark rm;
128 char* name = class_name->as_C_string();
129 return strchr(name, '.') == NULL;
130 } else {
131 return true;
132 }
133 }
135 #endif
137 // ----------------------------------------------------------------------------
138 // Parallel class loading check
140 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
141 if (UnsyncloadClass || class_loader.is_null()) return true;
142 if (AlwaysLockClassLoader) return false;
143 return java_lang_ClassLoader::parallelCapable(class_loader());
144 }
145 // ----------------------------------------------------------------------------
146 // ParallelDefineClass flag does not apply to bootclass loader
147 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
148 if (class_loader.is_null()) return false;
149 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
150 return true;
151 }
152 return false;
153 }
155 /**
156 * Returns true if the passed class loader is the extension class loader.
157 */
158 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
159 if (class_loader.is_null()) {
160 return false;
161 }
162 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
163 }
165 // ----------------------------------------------------------------------------
166 // Resolving of classes
168 // Forwards to resolve_or_null
170 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
171 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
172 if (HAS_PENDING_EXCEPTION || klass == NULL) {
173 KlassHandle k_h(THREAD, klass);
174 // can return a null klass
175 klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);
176 }
177 return klass;
178 }
180 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {
181 if (HAS_PENDING_EXCEPTION) {
182 // If we have a pending exception we forward it to the caller, unless throw_error is true,
183 // in which case we have to check whether the pending exception is a ClassNotFoundException,
184 // and if so convert it to a NoClassDefFoundError
185 // And chain the original ClassNotFoundException
186 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
187 ResourceMark rm(THREAD);
188 assert(klass_h() == NULL, "Should not have result with exception pending");
189 Handle e(THREAD, PENDING_EXCEPTION);
190 CLEAR_PENDING_EXCEPTION;
191 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
192 } else {
193 return NULL;
194 }
195 }
196 // Class not found, throw appropriate error or exception depending on value of throw_error
197 if (klass_h() == NULL) {
198 ResourceMark rm(THREAD);
199 if (throw_error) {
200 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
201 } else {
202 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
203 }
204 }
205 return (Klass*)klass_h();
206 }
209 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
210 bool throw_error, TRAPS)
211 {
212 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
213 }
216 // Forwards to resolve_instance_class_or_null
218 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
219 assert(!THREAD->is_Compiler_thread(),
220 err_msg("can not load classes with compiler thread: class=%s, classloader=%s",
221 class_name->as_C_string(),
222 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()));
223 if (FieldType::is_array(class_name)) {
224 return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
225 } else if (FieldType::is_obj(class_name)) {
226 ResourceMark rm(THREAD);
227 // Ignore wrapping L and ;.
228 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
229 class_name->utf8_length() - 2, CHECK_NULL);
230 return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL);
231 } else {
232 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
233 }
234 }
236 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
237 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
238 }
240 // Forwards to resolve_instance_class_or_null
242 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
243 Handle class_loader,
244 Handle protection_domain,
245 TRAPS) {
246 assert(FieldType::is_array(class_name), "must be array");
247 Klass* k = NULL;
248 FieldArrayInfo fd;
249 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
250 // of this call
251 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
252 if (t == T_OBJECT) {
253 // naked oop "k" is OK here -- we assign back into it
254 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
255 class_loader,
256 protection_domain,
257 CHECK_NULL);
258 if (k != NULL) {
259 k = k->array_klass(fd.dimension(), CHECK_NULL);
260 }
261 } else {
262 k = Universe::typeArrayKlassObj(t);
263 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
264 }
265 return k;
266 }
269 // Must be called for any super-class or super-interface resolution
270 // during class definition to allow class circularity checking
271 // super-interface callers:
272 // parse_interfaces - for defineClass & jvmtiRedefineClasses
273 // super-class callers:
274 // ClassFileParser - for defineClass & jvmtiRedefineClasses
275 // load_shared_class - while loading a class from shared archive
276 // resolve_instance_class_or_null:
277 // via: handle_parallel_super_load
278 // when resolving a class that has an existing placeholder with
279 // a saved superclass [i.e. a defineClass is currently in progress]
280 // if another thread is trying to resolve the class, it must do
281 // super-class checks on its own thread to catch class circularity
282 // This last call is critical in class circularity checking for cases
283 // where classloading is delegated to different threads and the
284 // classloader lock is released.
285 // Take the case: Base->Super->Base
286 // 1. If thread T1 tries to do a defineClass of class Base
287 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
288 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
289 // so it tries to load Super
290 // 3. If we load the class internally, or user classloader uses same thread
291 // loadClassFromxxx or defineClass via parseClassFile Super ...
292 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
293 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
294 // 3.4 calls resolve_super_or_fail Base
295 // 3.5 finds T1,Base -> throws class circularity
296 //OR 4. If T2 tries to resolve Super via defineClass Super ...
297 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
298 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
299 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
300 // 4.4 finds T2, Super -> throws class circularity
301 // Must be called, even if superclass is null, since this is
302 // where the placeholder entry is created which claims this
303 // thread is loading this class/classloader.
304 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
305 Symbol* class_name,
306 Handle class_loader,
307 Handle protection_domain,
308 bool is_superclass,
309 TRAPS) {
310 // Double-check, if child class is already loaded, just return super-class,interface
311 // Don't add a placedholder if already loaded, i.e. already in system dictionary
312 // Make sure there's a placeholder for the *child* before resolving.
313 // Used as a claim that this thread is currently loading superclass/classloader
314 // Used here for ClassCircularity checks and also for heap verification
315 // (every InstanceKlass in the heap needs to be in the system dictionary
316 // or have a placeholder).
317 // Must check ClassCircularity before checking if super class is already loaded
318 //
319 // We might not already have a placeholder if this child_name was
320 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
321 // the name of the class might not be known until the stream is actually
322 // parsed.
323 // Bugs 4643874, 4715493
324 // compute_hash can have a safepoint
326 ClassLoaderData* loader_data = class_loader_data(class_loader);
327 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
328 int d_index = dictionary()->hash_to_index(d_hash);
329 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
330 int p_index = placeholders()->hash_to_index(p_hash);
331 // can't throw error holding a lock
332 bool child_already_loaded = false;
333 bool throw_circularity_error = false;
334 {
335 MutexLocker mu(SystemDictionary_lock, THREAD);
336 Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
337 Klass* quicksuperk;
338 // to support // loading: if child done loading, just return superclass
339 // if class_name, & class_loader don't match:
340 // if initial define, SD update will give LinkageError
341 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
342 // so we don't throw an exception here.
343 // see: nsk redefclass014 & java.lang.instrument Instrument032
344 if ((childk != NULL ) && (is_superclass) &&
345 ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) &&
347 ((quicksuperk->name() == class_name) &&
348 (quicksuperk->class_loader() == class_loader()))) {
349 return quicksuperk;
350 } else {
351 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
352 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
353 throw_circularity_error = true;
354 }
355 }
356 if (!throw_circularity_error) {
357 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
358 }
359 }
360 if (throw_circularity_error) {
361 ResourceMark rm(THREAD);
362 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
363 }
365 // java.lang.Object should have been found above
366 assert(class_name != NULL, "null super class for resolving");
367 // Resolve the super class or interface, check results on return
368 Klass* superk = SystemDictionary::resolve_or_null(class_name,
369 class_loader,
370 protection_domain,
371 THREAD);
373 KlassHandle superk_h(THREAD, superk);
375 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
376 // It is no longer necessary to keep the placeholder table alive until update_dictionary
377 // or error. GC used to walk the placeholder table as strong roots.
378 // The instanceKlass is kept alive because the class loader is on the stack,
379 // which keeps the loader_data alive, as well as all instanceKlasses in
380 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
381 {
382 MutexLocker mu(SystemDictionary_lock, THREAD);
383 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
384 SystemDictionary_lock->notify_all();
385 }
386 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
387 // can null superk
388 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));
389 }
391 return superk_h();
392 }
394 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
395 Handle class_loader,
396 Handle protection_domain,
397 TRAPS) {
398 if(!has_checkPackageAccess()) return;
400 // Now we have to call back to java to check if the initating class has access
401 JavaValue result(T_VOID);
402 if (TraceProtectionDomainVerification) {
403 // Print out trace information
404 tty->print_cr("Checking package access");
405 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
406 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
407 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
408 }
410 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
411 JavaCalls::call_special(&result,
412 class_loader,
413 system_loader,
414 vmSymbols::checkPackageAccess_name(),
415 vmSymbols::class_protectiondomain_signature(),
416 Handle(THREAD, klass->java_mirror()),
417 protection_domain,
418 THREAD);
420 if (TraceProtectionDomainVerification) {
421 if (HAS_PENDING_EXCEPTION) {
422 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
423 } else {
424 tty->print_cr(" -> granted");
425 }
426 tty->cr();
427 }
429 if (HAS_PENDING_EXCEPTION) return;
431 // If no exception has been thrown, we have validated the protection domain
432 // Insert the protection domain of the initiating class into the set.
433 {
434 // We recalculate the entry here -- we've called out to java since
435 // the last time it was calculated.
436 ClassLoaderData* loader_data = class_loader_data(class_loader);
438 Symbol* kn = klass->name();
439 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
440 int d_index = dictionary()->hash_to_index(d_hash);
442 MutexLocker mu(SystemDictionary_lock, THREAD);
443 {
444 // Note that we have an entry, and entries can be deleted only during GC,
445 // so we cannot allow GC to occur while we're holding this entry.
447 // We're using a No_Safepoint_Verifier to catch any place where we
448 // might potentially do a GC at all.
449 // Dictionary::do_unloading() asserts that classes in SD are only
450 // unloaded at a safepoint. Anonymous classes are not in SD.
451 No_Safepoint_Verifier nosafepoint;
452 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
453 protection_domain, THREAD);
454 }
455 }
456 }
458 // We only get here if this thread finds that another thread
459 // has already claimed the placeholder token for the current operation,
460 // but that other thread either never owned or gave up the
461 // object lock
462 // Waits on SystemDictionary_lock to indicate placeholder table updated
463 // On return, caller must recheck placeholder table state
464 //
465 // We only get here if
466 // 1) custom classLoader, i.e. not bootstrap classloader
467 // 2) UnsyncloadClass not set
468 // 3) custom classLoader has broken the class loader objectLock
469 // so another thread got here in parallel
470 //
471 // lockObject must be held.
472 // Complicated dance due to lock ordering:
473 // Must first release the classloader object lock to
474 // allow initial definer to complete the class definition
475 // and to avoid deadlock
476 // Reclaim classloader lock object with same original recursion count
477 // Must release SystemDictionary_lock after notify, since
478 // class loader lock must be claimed before SystemDictionary_lock
479 // to prevent deadlocks
480 //
481 // The notify allows applications that did an untimed wait() on
482 // the classloader object lock to not hang.
483 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
484 assert_lock_strong(SystemDictionary_lock);
486 bool calledholdinglock
487 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
488 assert(calledholdinglock,"must hold lock for notify");
489 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
490 ObjectSynchronizer::notifyall(lockObject, THREAD);
491 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
492 SystemDictionary_lock->wait();
493 SystemDictionary_lock->unlock();
494 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
495 SystemDictionary_lock->lock();
496 }
498 // If the class in is in the placeholder table, class loading is in progress
499 // For cases where the application changes threads to load classes, it
500 // is critical to ClassCircularity detection that we try loading
501 // the superclass on the same thread internally, so we do parallel
502 // super class loading here.
503 // This also is critical in cases where the original thread gets stalled
504 // even in non-circularity situations.
505 // Note: must call resolve_super_or_fail even if null super -
506 // to force placeholder entry creation for this class for circularity detection
507 // Caller must check for pending exception
508 // Returns non-null Klass* if other thread has completed load
509 // and we are done,
510 // If return null Klass* and no pending exception, the caller must load the class
511 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
512 Symbol* name, Symbol* superclassname, Handle class_loader,
513 Handle protection_domain, Handle lockObject, TRAPS) {
515 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
516 ClassLoaderData* loader_data = class_loader_data(class_loader);
517 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
518 int d_index = dictionary()->hash_to_index(d_hash);
519 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
520 int p_index = placeholders()->hash_to_index(p_hash);
522 // superk is not used, resolve_super called for circularity check only
523 // This code is reached in two situations. One if this thread
524 // is loading the same class twice (e.g. ClassCircularity, or
525 // java.lang.instrument).
526 // The second is if another thread started the resolve_super first
527 // and has not yet finished.
528 // In both cases the original caller will clean up the placeholder
529 // entry on error.
530 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
531 superclassname,
532 class_loader,
533 protection_domain,
534 true,
535 CHECK_(nh));
537 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
538 // Serial class loaders and bootstrap classloader do wait for superclass loads
539 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
540 MutexLocker mu(SystemDictionary_lock, THREAD);
541 // Check if classloading completed while we were loading superclass or waiting
542 Klass* check = find_class(d_index, d_hash, name, loader_data);
543 if (check != NULL) {
544 // Klass is already loaded, so just return it
545 return(instanceKlassHandle(THREAD, check));
546 } else {
547 return nh;
548 }
549 }
551 // must loop to both handle other placeholder updates
552 // and spurious notifications
553 bool super_load_in_progress = true;
554 PlaceholderEntry* placeholder;
555 while (super_load_in_progress) {
556 MutexLocker mu(SystemDictionary_lock, THREAD);
557 // Check if classloading completed while we were loading superclass or waiting
558 Klass* check = find_class(d_index, d_hash, name, loader_data);
559 if (check != NULL) {
560 // Klass is already loaded, so just return it
561 return(instanceKlassHandle(THREAD, check));
562 } else {
563 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
564 if (placeholder && placeholder->super_load_in_progress() ){
565 // Before UnsyncloadClass:
566 // We only get here if the application has released the
567 // classloader lock when another thread was in the middle of loading a
568 // superclass/superinterface for this class, and now
569 // this thread is also trying to load this class.
570 // To minimize surprises, the first thread that started to
571 // load a class should be the one to complete the loading
572 // with the classfile it initially expected.
573 // This logic has the current thread wait once it has done
574 // all the superclass/superinterface loading it can, until
575 // the original thread completes the class loading or fails
576 // If it completes we will use the resulting InstanceKlass
577 // which we will find below in the systemDictionary.
578 // We also get here for parallel bootstrap classloader
579 if (class_loader.is_null()) {
580 SystemDictionary_lock->wait();
581 } else {
582 double_lock_wait(lockObject, THREAD);
583 }
584 } else {
585 // If not in SD and not in PH, other thread's load must have failed
586 super_load_in_progress = false;
587 }
588 }
589 }
590 return (nh);
591 }
594 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
595 Handle class_loader,
596 Handle protection_domain,
597 TRAPS) {
598 assert(name != NULL && !FieldType::is_array(name) &&
599 !FieldType::is_obj(name), "invalid class name");
601 TracingTime class_load_start_time = Tracing::time();
603 // UseNewReflection
604 // Fix for 4474172; see evaluation for more details
605 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
606 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
608 // Do lookup to see if class already exist and the protection domain
609 // has the right access
610 // This call uses find which checks protection domain already matches
611 // All subsequent calls use find_class, and set has_loaded_class so that
612 // before we return a result we call out to java to check for valid protection domain
613 // to allow returning the Klass* and add it to the pd_set if it is valid
614 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
615 int d_index = dictionary()->hash_to_index(d_hash);
616 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
617 protection_domain, THREAD);
618 if (probe != NULL) return probe;
621 // Non-bootstrap class loaders will call out to class loader and
622 // define via jvm/jni_DefineClass which will acquire the
623 // class loader object lock to protect against multiple threads
624 // defining the class in parallel by accident.
625 // This lock must be acquired here so the waiter will find
626 // any successful result in the SystemDictionary and not attempt
627 // the define
628 // ParallelCapable Classloaders and the bootstrap classloader,
629 // or all classloaders with UnsyncloadClass do not acquire lock here
630 bool DoObjectLock = true;
631 if (is_parallelCapable(class_loader)) {
632 DoObjectLock = false;
633 }
635 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
636 int p_index = placeholders()->hash_to_index(p_hash);
638 // Class is not in SystemDictionary so we have to do loading.
639 // Make sure we are synchronized on the class loader before we proceed
640 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
641 check_loader_lock_contention(lockObject, THREAD);
642 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
644 // Check again (after locking) if class already exist in SystemDictionary
645 bool class_has_been_loaded = false;
646 bool super_load_in_progress = false;
647 bool havesupername = false;
648 instanceKlassHandle k;
649 PlaceholderEntry* placeholder;
650 Symbol* superclassname = NULL;
652 {
653 MutexLocker mu(SystemDictionary_lock, THREAD);
654 Klass* check = find_class(d_index, d_hash, name, loader_data);
655 if (check != NULL) {
656 // Klass is already loaded, so just return it
657 class_has_been_loaded = true;
658 k = instanceKlassHandle(THREAD, check);
659 } else {
660 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
661 if (placeholder && placeholder->super_load_in_progress()) {
662 super_load_in_progress = true;
663 if (placeholder->havesupername() == true) {
664 superclassname = placeholder->supername();
665 havesupername = true;
666 }
667 }
668 }
669 }
671 // If the class is in the placeholder table, class loading is in progress
672 if (super_load_in_progress && havesupername==true) {
673 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
674 class_loader, protection_domain, lockObject, THREAD);
675 if (HAS_PENDING_EXCEPTION) {
676 return NULL;
677 }
678 if (!k.is_null()) {
679 class_has_been_loaded = true;
680 }
681 }
683 bool throw_circularity_error = false;
684 if (!class_has_been_loaded) {
685 bool load_instance_added = false;
687 // add placeholder entry to record loading instance class
688 // Five cases:
689 // All cases need to prevent modifying bootclasssearchpath
690 // in parallel with a classload of same classname
691 // Redefineclasses uses existence of the placeholder for the duration
692 // of the class load to prevent concurrent redefinition of not completely
693 // defined classes.
694 // case 1. traditional classloaders that rely on the classloader object lock
695 // - no other need for LOAD_INSTANCE
696 // case 2. traditional classloaders that break the classloader object lock
697 // as a deadlock workaround. Detection of this case requires that
698 // this check is done while holding the classloader object lock,
699 // and that lock is still held when calling classloader's loadClass.
700 // For these classloaders, we ensure that the first requestor
701 // completes the load and other requestors wait for completion.
702 // case 3. UnsyncloadClass - don't use objectLocker
703 // With this flag, we allow parallel classloading of a
704 // class/classloader pair
705 // case4. Bootstrap classloader - don't own objectLocker
706 // This classloader supports parallelism at the classloader level,
707 // but only allows a single load of a class/classloader pair.
708 // No performance benefit and no deadlock issues.
709 // case 5. parallelCapable user level classloaders - without objectLocker
710 // Allow parallel classloading of a class/classloader pair
712 {
713 MutexLocker mu(SystemDictionary_lock, THREAD);
714 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
715 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
716 if (oldprobe) {
717 // only need check_seen_thread once, not on each loop
718 // 6341374 java/lang/Instrument with -Xcomp
719 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
720 throw_circularity_error = true;
721 } else {
722 // case 1: traditional: should never see load_in_progress.
723 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
725 // case 4: bootstrap classloader: prevent futile classloading,
726 // wait on first requestor
727 if (class_loader.is_null()) {
728 SystemDictionary_lock->wait();
729 } else {
730 // case 2: traditional with broken classloader lock. wait on first
731 // requestor.
732 double_lock_wait(lockObject, THREAD);
733 }
734 // Check if classloading completed while we were waiting
735 Klass* check = find_class(d_index, d_hash, name, loader_data);
736 if (check != NULL) {
737 // Klass is already loaded, so just return it
738 k = instanceKlassHandle(THREAD, check);
739 class_has_been_loaded = true;
740 }
741 // check if other thread failed to load and cleaned up
742 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
743 }
744 }
745 }
746 }
747 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
748 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
749 // LOAD_INSTANCE in parallel
751 if (!throw_circularity_error && !class_has_been_loaded) {
752 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
753 load_instance_added = true;
754 // For class loaders that do not acquire the classloader object lock,
755 // if they did not catch another thread holding LOAD_INSTANCE,
756 // need a check analogous to the acquire ObjectLocker/find_class
757 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
758 // one final check if the load has already completed
759 // class loaders holding the ObjectLock shouldn't find the class here
760 Klass* check = find_class(d_index, d_hash, name, loader_data);
761 if (check != NULL) {
762 // Klass is already loaded, so return it after checking/adding protection domain
763 k = instanceKlassHandle(THREAD, check);
764 class_has_been_loaded = true;
765 }
766 }
767 }
769 // must throw error outside of owning lock
770 if (throw_circularity_error) {
771 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
772 ResourceMark rm(THREAD);
773 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
774 }
776 if (!class_has_been_loaded) {
778 // Do actual loading
779 k = load_instance_class(name, class_loader, THREAD);
781 // For UnsyncloadClass only
782 // If they got a linkageError, check if a parallel class load succeeded.
783 // If it did, then for bytecode resolution the specification requires
784 // that we return the same result we did for the other thread, i.e. the
785 // successfully loaded InstanceKlass
786 // Should not get here for classloaders that support parallelism
787 // with the new cleaner mechanism, even with AllowParallelDefineClass
788 // Bootstrap goes through here to allow for an extra guarantee check
789 if (UnsyncloadClass || (class_loader.is_null())) {
790 if (k.is_null() && HAS_PENDING_EXCEPTION
791 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
792 MutexLocker mu(SystemDictionary_lock, THREAD);
793 Klass* check = find_class(d_index, d_hash, name, loader_data);
794 if (check != NULL) {
795 // Klass is already loaded, so just use it
796 k = instanceKlassHandle(THREAD, check);
797 CLEAR_PENDING_EXCEPTION;
798 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
799 }
800 }
801 }
803 // If everything was OK (no exceptions, no null return value), and
804 // class_loader is NOT the defining loader, do a little more bookkeeping.
805 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
806 k->class_loader() != class_loader()) {
808 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
810 // Need to check for a PENDING_EXCEPTION again; check_constraints
811 // can throw and doesn't use the CHECK macro.
812 if (!HAS_PENDING_EXCEPTION) {
813 { // Grabbing the Compile_lock prevents systemDictionary updates
814 // during compilations.
815 MutexLocker mu(Compile_lock, THREAD);
816 update_dictionary(d_index, d_hash, p_index, p_hash,
817 k, class_loader, THREAD);
818 }
820 if (JvmtiExport::should_post_class_load()) {
821 Thread *thread = THREAD;
822 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
823 JvmtiExport::post_class_load((JavaThread *) thread, k());
824 }
825 }
826 }
827 } // load_instance_class loop
829 if (HAS_PENDING_EXCEPTION) {
830 // An exception, such as OOM could have happened at various places inside
831 // load_instance_class. We might have partially initialized a shared class
832 // and need to clean it up.
833 if (class_loader.is_null()) {
834 // In some cases k may be null. Let's find the shared class again.
835 instanceKlassHandle ik(THREAD, find_shared_class(name));
836 if (ik.not_null()) {
837 if (ik->class_loader_data() == NULL) {
838 // We didn't go as far as Klass::restore_unshareable_info(),
839 // so nothing to clean up.
840 } else {
841 Klass *kk;
842 {
843 MutexLocker mu(SystemDictionary_lock, THREAD);
844 kk = find_class(d_index, d_hash, name, ik->class_loader_data());
845 }
846 if (kk != NULL) {
847 // No clean up is needed if the shared class has been entered
848 // into system dictionary, as load_shared_class() won't be called
849 // again.
850 } else {
851 // This must be done outside of the SystemDictionary_lock to
852 // avoid deadlock.
853 //
854 // Note that Klass::restore_unshareable_info (called via
855 // load_instance_class above) is also called outside
856 // of SystemDictionary_lock. Other threads are blocked from
857 // loading this class because they are waiting on the
858 // SystemDictionary_lock until this thread removes
859 // the placeholder below.
860 //
861 // This need to be re-thought when parallel-capable non-boot
862 // classloaders are supported by CDS (today they're not).
863 clean_up_shared_class(ik, class_loader, THREAD);
864 }
865 }
866 }
867 }
868 }
870 if (load_instance_added == true) {
871 // clean up placeholder entries for LOAD_INSTANCE success or error
872 // This brackets the SystemDictionary updates for both defining
873 // and initiating loaders
874 MutexLocker mu(SystemDictionary_lock, THREAD);
875 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
876 SystemDictionary_lock->notify_all();
877 }
878 }
880 if (HAS_PENDING_EXCEPTION || k.is_null()) {
881 return NULL;
882 }
884 post_class_load_event(class_load_start_time, k, class_loader);
886 #ifdef ASSERT
887 {
888 ClassLoaderData* loader_data = k->class_loader_data();
889 MutexLocker mu(SystemDictionary_lock, THREAD);
890 Klass* kk = find_class(name, loader_data);
891 assert(kk == k(), "should be present in dictionary");
892 }
893 #endif
895 // return if the protection domain in NULL
896 if (protection_domain() == NULL) return k();
898 // Check the protection domain has the right access
899 {
900 MutexLocker mu(SystemDictionary_lock, THREAD);
901 // Note that we have an entry, and entries can be deleted only during GC,
902 // so we cannot allow GC to occur while we're holding this entry.
903 // We're using a No_Safepoint_Verifier to catch any place where we
904 // might potentially do a GC at all.
905 // Dictionary::do_unloading() asserts that classes in SD are only
906 // unloaded at a safepoint. Anonymous classes are not in SD.
907 No_Safepoint_Verifier nosafepoint;
908 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
909 loader_data,
910 protection_domain)) {
911 return k();
912 }
913 }
915 // Verify protection domain. If it fails an exception is thrown
916 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
918 return k();
919 }
922 // This routine does not lock the system dictionary.
923 //
924 // Since readers don't hold a lock, we must make sure that system
925 // dictionary entries are only removed at a safepoint (when only one
926 // thread is running), and are added to in a safe way (all links must
927 // be updated in an MT-safe manner).
928 //
929 // Callers should be aware that an entry could be added just after
930 // _dictionary->bucket(index) is read here, so the caller will not see
931 // the new entry.
933 Klass* SystemDictionary::find(Symbol* class_name,
934 Handle class_loader,
935 Handle protection_domain,
936 TRAPS) {
938 // UseNewReflection
939 // The result of this call should be consistent with the result
940 // of the call to resolve_instance_class_or_null().
941 // See evaluation 6790209 and 4474172 for more details.
942 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
943 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
945 if (loader_data == NULL) {
946 // If the ClassLoaderData has not been setup,
947 // then the class loader has no entries in the dictionary.
948 return NULL;
949 }
951 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
952 int d_index = dictionary()->hash_to_index(d_hash);
954 {
955 // Note that we have an entry, and entries can be deleted only during GC,
956 // so we cannot allow GC to occur while we're holding this entry.
957 // We're using a No_Safepoint_Verifier to catch any place where we
958 // might potentially do a GC at all.
959 // Dictionary::do_unloading() asserts that classes in SD are only
960 // unloaded at a safepoint. Anonymous classes are not in SD.
961 No_Safepoint_Verifier nosafepoint;
962 return dictionary()->find(d_index, d_hash, class_name, loader_data,
963 protection_domain, THREAD);
964 }
965 }
968 // Look for a loaded instance or array klass by name. Do not do any loading.
969 // return NULL in case of error.
970 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
971 Handle class_loader,
972 Handle protection_domain,
973 TRAPS) {
974 Klass* k = NULL;
975 assert(class_name != NULL, "class name must be non NULL");
977 if (FieldType::is_array(class_name)) {
978 // The name refers to an array. Parse the name.
979 // dimension and object_key in FieldArrayInfo are assigned as a
980 // side-effect of this call
981 FieldArrayInfo fd;
982 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
983 if (t != T_OBJECT) {
984 k = Universe::typeArrayKlassObj(t);
985 } else {
986 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
987 }
988 if (k != NULL) {
989 k = k->array_klass_or_null(fd.dimension());
990 }
991 } else {
992 k = find(class_name, class_loader, protection_domain, THREAD);
993 }
994 return k;
995 }
997 // Note: this method is much like resolve_from_stream, but
998 // updates no supplemental data structures.
999 // TODO consolidate the two methods with a helper routine?
1000 Klass* SystemDictionary::parse_stream(Symbol* class_name,
1001 Handle class_loader,
1002 Handle protection_domain,
1003 ClassFileStream* st,
1004 KlassHandle host_klass,
1005 GrowableArray<Handle>* cp_patches,
1006 TRAPS) {
1007 TempNewSymbol parsed_name = NULL;
1009 TracingTime class_load_start_time = Tracing::time();
1011 ClassLoaderData* loader_data;
1012 if (host_klass.not_null()) {
1013 // Create a new CLD for anonymous class, that uses the same class loader
1014 // as the host_klass
1015 assert(EnableInvokeDynamic, "");
1016 guarantee(host_klass->class_loader() == class_loader(), "should be the same");
1017 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1018 loader_data->record_dependency(host_klass(), CHECK_NULL);
1019 } else {
1020 loader_data = ClassLoaderData::class_loader_data(class_loader());
1021 }
1023 // Parse the stream. Note that we do this even though this klass might
1024 // already be present in the SystemDictionary, otherwise we would not
1025 // throw potential ClassFormatErrors.
1026 //
1027 // Note: "name" is updated.
1029 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1030 loader_data,
1031 protection_domain,
1032 host_klass,
1033 cp_patches,
1034 parsed_name,
1035 true,
1036 THREAD);
1039 if (host_klass.not_null() && k.not_null()) {
1040 assert(EnableInvokeDynamic, "");
1041 k->set_host_klass(host_klass());
1042 // If it's anonymous, initialize it now, since nobody else will.
1044 {
1045 MutexLocker mu_r(Compile_lock, THREAD);
1047 // Add to class hierarchy, initialize vtables, and do possible
1048 // deoptimizations.
1049 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1051 // But, do not add to system dictionary.
1052 }
1054 // Rewrite and patch constant pool here.
1055 k->link_class(CHECK_NULL);
1056 if (cp_patches != NULL) {
1057 k->constants()->patch_resolved_references(cp_patches);
1058 }
1059 k->eager_initialize(CHECK_NULL);
1061 // notify jvmti
1062 if (JvmtiExport::should_post_class_load()) {
1063 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1064 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1065 }
1067 post_class_load_event(class_load_start_time, k, class_loader);
1068 }
1069 assert(host_klass.not_null() || cp_patches == NULL,
1070 "cp_patches only found with host_klass");
1072 return k();
1073 }
1075 // Add a klass to the system from a stream (called by jni_DefineClass and
1076 // JVM_DefineClass).
1077 // Note: class_name can be NULL. In that case we do not know the name of
1078 // the class until we have parsed the stream.
1080 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1081 Handle class_loader,
1082 Handle protection_domain,
1083 ClassFileStream* st,
1084 bool verify,
1085 TRAPS) {
1087 // Classloaders that support parallelism, e.g. bootstrap classloader,
1088 // or all classloaders with UnsyncloadClass do not acquire lock here
1089 bool DoObjectLock = true;
1090 if (is_parallelCapable(class_loader)) {
1091 DoObjectLock = false;
1092 }
1094 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1096 // Make sure we are synchronized on the class loader before we proceed
1097 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1098 check_loader_lock_contention(lockObject, THREAD);
1099 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1101 TempNewSymbol parsed_name = NULL;
1103 // Parse the stream. Note that we do this even though this klass might
1104 // already be present in the SystemDictionary, otherwise we would not
1105 // throw potential ClassFormatErrors.
1106 //
1107 // Note: "name" is updated.
1109 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1110 loader_data,
1111 protection_domain,
1112 parsed_name,
1113 verify,
1114 THREAD);
1116 const char* pkg = "java/";
1117 if (!HAS_PENDING_EXCEPTION &&
1118 !class_loader.is_null() &&
1119 parsed_name != NULL &&
1120 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1121 // It is illegal to define classes in the "java." package from
1122 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1123 ResourceMark rm(THREAD);
1124 char* name = parsed_name->as_C_string();
1125 char* index = strrchr(name, '/');
1126 *index = '\0'; // chop to just the package name
1127 while ((index = strchr(name, '/')) != NULL) {
1128 *index = '.'; // replace '/' with '.' in package name
1129 }
1130 const char* fmt = "Prohibited package name: %s";
1131 size_t len = strlen(fmt) + strlen(name);
1132 char* message = NEW_RESOURCE_ARRAY(char, len);
1133 jio_snprintf(message, len, fmt, name);
1134 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1135 vmSymbols::java_lang_SecurityException(), message);
1136 }
1138 if (!HAS_PENDING_EXCEPTION) {
1139 assert(parsed_name != NULL, "Sanity");
1140 assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1141 // Verification prevents us from creating names with dots in them, this
1142 // asserts that that's the case.
1143 assert(is_internal_format(parsed_name),
1144 "external class name format used internally");
1146 // Add class just loaded
1147 // If a class loader supports parallel classloading handle parallel define requests
1148 // find_or_define_instance_class may return a different InstanceKlass
1149 if (is_parallelCapable(class_loader)) {
1150 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1151 } else {
1152 define_instance_class(k, THREAD);
1153 }
1154 }
1156 // Make sure we have an entry in the SystemDictionary on success
1157 debug_only( {
1158 if (!HAS_PENDING_EXCEPTION) {
1159 assert(parsed_name != NULL, "parsed_name is still null?");
1160 Symbol* h_name = k->name();
1161 ClassLoaderData *defining_loader_data = k->class_loader_data();
1163 MutexLocker mu(SystemDictionary_lock, THREAD);
1165 Klass* check = find_class(parsed_name, loader_data);
1166 assert(check == k(), "should be present in the dictionary");
1168 Klass* check2 = find_class(h_name, defining_loader_data);
1169 assert(check == check2, "name inconsistancy in SystemDictionary");
1170 }
1171 } );
1173 return k();
1174 }
1177 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1178 int number_of_entries) {
1179 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1180 "bad shared dictionary size.");
1181 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1182 }
1185 // If there is a shared dictionary, then find the entry for the
1186 // given shared system class, if any.
1188 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1189 if (shared_dictionary() != NULL) {
1190 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1191 int d_index = shared_dictionary()->hash_to_index(d_hash);
1193 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1194 } else {
1195 return NULL;
1196 }
1197 }
1200 // Load a class from the shared spaces (found through the shared system
1201 // dictionary). Force the superclass and all interfaces to be loaded.
1202 // Update the class definition to include sibling classes and no
1203 // subclasses (yet). [Classes in the shared space are not part of the
1204 // object hierarchy until loaded.]
1206 instanceKlassHandle SystemDictionary::load_shared_class(
1207 Symbol* class_name, Handle class_loader, TRAPS) {
1208 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1209 return load_shared_class(ik, class_loader, THREAD);
1210 }
1212 instanceKlassHandle SystemDictionary::load_shared_class(
1213 instanceKlassHandle ik, Handle class_loader, TRAPS) {
1214 assert(class_loader.is_null(), "non-null classloader for shared class?");
1215 if (ik.not_null()) {
1216 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1217 Symbol* class_name = ik->name();
1219 // Found the class, now load the superclass and interfaces. If they
1220 // are shared, add them to the main system dictionary and reset
1221 // their hierarchy references (supers, subs, and interfaces).
1223 if (ik->super() != NULL) {
1224 Symbol* cn = ik->super()->name();
1225 resolve_super_or_fail(class_name, cn,
1226 class_loader, Handle(), true, CHECK_(nh));
1227 }
1229 Array<Klass*>* interfaces = ik->local_interfaces();
1230 int num_interfaces = interfaces->length();
1231 for (int index = 0; index < num_interfaces; index++) {
1232 Klass* k = interfaces->at(index);
1234 // Note: can not use InstanceKlass::cast here because
1235 // interfaces' InstanceKlass's C++ vtbls haven't been
1236 // reinitialized yet (they will be once the interface classes
1237 // are loaded)
1238 Symbol* name = k->name();
1239 resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(nh));
1240 }
1242 // Adjust methods to recover missing data. They need addresses for
1243 // interpreter entry points and their default native method address
1244 // must be reset.
1246 // Updating methods must be done under a lock so multiple
1247 // threads don't update these in parallel
1248 // Shared classes are all currently loaded by the bootstrap
1249 // classloader, so this will never cause a deadlock on
1250 // a custom class loader lock.
1252 {
1253 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1254 check_loader_lock_contention(lockObject, THREAD);
1255 ObjectLocker ol(lockObject, THREAD, true);
1256 ik->restore_unshareable_info(CHECK_(nh));
1257 }
1259 if (TraceClassLoading) {
1260 ResourceMark rm;
1261 tty->print("[Loaded %s", ik->external_name());
1262 tty->print(" from shared objects file");
1263 tty->print_cr("]");
1264 }
1265 // notify a class loaded from shared object
1266 ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()),
1267 true /* shared class */);
1268 }
1269 return ik;
1270 }
1272 void SystemDictionary::clean_up_shared_class(instanceKlassHandle ik, Handle class_loader, TRAPS) {
1273 // Updating methods must be done under a lock so multiple
1274 // threads don't update these in parallel
1275 // Shared classes are all currently loaded by the bootstrap
1276 // classloader, so this will never cause a deadlock on
1277 // a custom class loader lock.
1278 {
1279 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1280 check_loader_lock_contention(lockObject, THREAD);
1281 ObjectLocker ol(lockObject, THREAD, true);
1282 ik->remove_unshareable_info();
1283 }
1284 }
1286 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1287 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1288 if (class_loader.is_null()) {
1290 // Search the shared system dictionary for classes preloaded into the
1291 // shared spaces.
1292 instanceKlassHandle k;
1293 {
1294 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1295 k = load_shared_class(class_name, class_loader, THREAD);
1296 }
1298 if (k.is_null()) {
1299 // Use VM class loader
1300 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1301 k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1302 }
1304 // find_or_define_instance_class may return a different InstanceKlass
1305 if (!k.is_null()) {
1306 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1307 }
1308 return k;
1309 } else {
1310 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1311 ResourceMark rm(THREAD);
1313 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1314 JavaThread* jt = (JavaThread*) THREAD;
1316 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1317 ClassLoader::perf_app_classload_selftime(),
1318 ClassLoader::perf_app_classload_count(),
1319 jt->get_thread_stat()->perf_recursion_counts_addr(),
1320 jt->get_thread_stat()->perf_timers_addr(),
1321 PerfClassTraceTime::CLASS_LOAD);
1323 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1324 // Translate to external class name format, i.e., convert '/' chars to '.'
1325 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1327 JavaValue result(T_OBJECT);
1329 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1331 // Call public unsynchronized loadClass(String) directly for all class loaders
1332 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1333 // acquire a class-name based lock rather than the class loader object lock.
1334 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1335 // so the call to loadClassInternal() was not required.
1336 //
1337 // UnsyncloadClass flag means both call loadClass(String) and do
1338 // not acquire the class loader lock even for class loaders that are
1339 // not parallelCapable. This was a risky transitional
1340 // flag for diagnostic purposes only. It is risky to call
1341 // custom class loaders without synchronization.
1342 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1343 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1344 // Do NOT assume this will be supported in future releases.
1345 //
1346 // Added MustCallLoadClassInternal in case we discover in the field
1347 // a customer that counts on this call
1348 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1349 JavaCalls::call_special(&result,
1350 class_loader,
1351 spec_klass,
1352 vmSymbols::loadClassInternal_name(),
1353 vmSymbols::string_class_signature(),
1354 string,
1355 CHECK_(nh));
1356 } else {
1357 JavaCalls::call_virtual(&result,
1358 class_loader,
1359 spec_klass,
1360 vmSymbols::loadClass_name(),
1361 vmSymbols::string_class_signature(),
1362 string,
1363 CHECK_(nh));
1364 }
1366 assert(result.get_type() == T_OBJECT, "just checking");
1367 oop obj = (oop) result.get_jobject();
1369 // Primitive classes return null since forName() can not be
1370 // used to obtain any of the Class objects representing primitives or void
1371 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1372 instanceKlassHandle k =
1373 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1374 // For user defined Java class loaders, check that the name returned is
1375 // the same as that requested. This check is done for the bootstrap
1376 // loader when parsing the class file.
1377 if (class_name == k->name()) {
1378 return k;
1379 }
1380 }
1381 // Class is not found or has the wrong name, return NULL
1382 return nh;
1383 }
1384 }
1386 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1388 ClassLoaderData* loader_data = k->class_loader_data();
1389 Handle class_loader_h(THREAD, loader_data->class_loader());
1391 for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){}
1393 // for bootstrap and other parallel classloaders don't acquire lock,
1394 // use placeholder token
1395 // If a parallelCapable class loader calls define_instance_class instead of
1396 // find_or_define_instance_class to get here, we have a timing
1397 // hole with systemDictionary updates and check_constraints
1398 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1399 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1400 compute_loader_lock_object(class_loader_h, THREAD)),
1401 "define called without lock");
1402 }
1404 // Check class-loading constraints. Throw exception if violation is detected.
1405 // Grabs and releases SystemDictionary_lock
1406 // The check_constraints/find_class call and update_dictionary sequence
1407 // must be "atomic" for a specific class/classloader pair so we never
1408 // define two different instanceKlasses for that class/classloader pair.
1409 // Existing classloaders will call define_instance_class with the
1410 // classloader lock held
1411 // Parallel classloaders will call find_or_define_instance_class
1412 // which will require a token to perform the define class
1413 Symbol* name_h = k->name();
1414 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1415 int d_index = dictionary()->hash_to_index(d_hash);
1416 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1418 // Register class just loaded with class loader (placed in Vector)
1419 // Note we do this before updating the dictionary, as this can
1420 // fail with an OutOfMemoryError (if it does, we will *not* put this
1421 // class in the dictionary and will not update the class hierarchy).
1422 // JVMTI FollowReferences needs to find the classes this way.
1423 if (k->class_loader() != NULL) {
1424 methodHandle m(THREAD, Universe::loader_addClass_method());
1425 JavaValue result(T_VOID);
1426 JavaCallArguments args(class_loader_h);
1427 args.push_oop(Handle(THREAD, k->java_mirror()));
1428 JavaCalls::call(&result, m, &args, CHECK);
1429 }
1431 // Add the new class. We need recompile lock during update of CHA.
1432 {
1433 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1434 int p_index = placeholders()->hash_to_index(p_hash);
1436 MutexLocker mu_r(Compile_lock, THREAD);
1438 // Add to class hierarchy, initialize vtables, and do possible
1439 // deoptimizations.
1440 add_to_hierarchy(k, CHECK); // No exception, but can block
1442 // Add to systemDictionary - so other classes can see it.
1443 // Grabs and releases SystemDictionary_lock
1444 update_dictionary(d_index, d_hash, p_index, p_hash,
1445 k, class_loader_h, THREAD);
1446 }
1447 k->eager_initialize(THREAD);
1449 // notify jvmti
1450 if (JvmtiExport::should_post_class_load()) {
1451 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1452 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1454 }
1456 }
1458 // Support parallel classloading
1459 // All parallel class loaders, including bootstrap classloader
1460 // lock a placeholder entry for this class/class_loader pair
1461 // to allow parallel defines of different classes for this class loader
1462 // With AllowParallelDefine flag==true, in case they do not synchronize around
1463 // FindLoadedClass/DefineClass, calls, we check for parallel
1464 // loading for them, wait if a defineClass is in progress
1465 // and return the initial requestor's results
1466 // This flag does not apply to the bootstrap classloader.
1467 // With AllowParallelDefine flag==false, call through to define_instance_class
1468 // which will throw LinkageError: duplicate class definition.
1469 // False is the requested default.
1470 // For better performance, the class loaders should synchronize
1471 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1472 // potentially waste time reading and parsing the bytestream.
1473 // Note: VM callers should ensure consistency of k/class_name,class_loader
1474 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1476 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1477 Symbol* name_h = k->name(); // passed in class_name may be null
1478 ClassLoaderData* loader_data = class_loader_data(class_loader);
1480 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1481 int d_index = dictionary()->hash_to_index(d_hash);
1483 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1484 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1485 int p_index = placeholders()->hash_to_index(p_hash);
1486 PlaceholderEntry* probe;
1488 {
1489 MutexLocker mu(SystemDictionary_lock, THREAD);
1490 // First check if class already defined
1491 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1492 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1493 if (check != NULL) {
1494 return(instanceKlassHandle(THREAD, check));
1495 }
1496 }
1498 // Acquire define token for this class/classloader
1499 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1500 // Wait if another thread defining in parallel
1501 // All threads wait - even those that will throw duplicate class: otherwise
1502 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1503 // if other thread has not finished updating dictionary
1504 while (probe->definer() != NULL) {
1505 SystemDictionary_lock->wait();
1506 }
1507 // Only special cases allow parallel defines and can use other thread's results
1508 // Other cases fall through, and may run into duplicate defines
1509 // caught by finding an entry in the SystemDictionary
1510 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1511 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1512 SystemDictionary_lock->notify_all();
1513 #ifdef ASSERT
1514 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1515 assert(check != NULL, "definer missed recording success");
1516 #endif
1517 return(instanceKlassHandle(THREAD, probe->instance_klass()));
1518 } else {
1519 // This thread will define the class (even if earlier thread tried and had an error)
1520 probe->set_definer(THREAD);
1521 }
1522 }
1524 define_instance_class(k, THREAD);
1526 Handle linkage_exception = Handle(); // null handle
1528 // definer must notify any waiting threads
1529 {
1530 MutexLocker mu(SystemDictionary_lock, THREAD);
1531 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1532 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1533 if (probe != NULL) {
1534 if (HAS_PENDING_EXCEPTION) {
1535 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1536 CLEAR_PENDING_EXCEPTION;
1537 } else {
1538 probe->set_instance_klass(k());
1539 }
1540 probe->set_definer(NULL);
1541 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1542 SystemDictionary_lock->notify_all();
1543 }
1544 }
1546 // Can't throw exception while holding lock due to rank ordering
1547 if (linkage_exception() != NULL) {
1548 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1549 }
1551 return k;
1552 }
1553 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1554 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1555 if (class_loader.is_null()) {
1556 return Handle(THREAD, _system_loader_lock_obj);
1557 } else {
1558 return class_loader;
1559 }
1560 }
1562 // This method is added to check how often we have to wait to grab loader
1563 // lock. The results are being recorded in the performance counters defined in
1564 // ClassLoader::_sync_systemLoaderLockContentionRate and
1565 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1566 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1567 if (!UsePerfData) {
1568 return;
1569 }
1571 assert(!loader_lock.is_null(), "NULL lock object");
1573 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1574 == ObjectSynchronizer::owner_other) {
1575 // contention will likely happen, so increment the corresponding
1576 // contention counter.
1577 if (loader_lock() == _system_loader_lock_obj) {
1578 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1579 } else {
1580 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1581 }
1582 }
1583 }
1585 // ----------------------------------------------------------------------------
1586 // Lookup
1588 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1589 Symbol* class_name,
1590 ClassLoaderData* loader_data) {
1591 assert_locked_or_safepoint(SystemDictionary_lock);
1592 assert (index == dictionary()->index_for(class_name, loader_data),
1593 "incorrect index?");
1595 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1596 return k;
1597 }
1600 // Basic find on classes in the midst of being loaded
1601 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1602 ClassLoaderData* loader_data) {
1603 assert_locked_or_safepoint(SystemDictionary_lock);
1604 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1605 int p_index = placeholders()->hash_to_index(p_hash);
1606 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1607 }
1610 // Used for assertions and verification only
1611 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1612 #ifndef ASSERT
1613 guarantee(VerifyBeforeGC ||
1614 VerifyDuringGC ||
1615 VerifyBeforeExit ||
1616 VerifyDuringStartup ||
1617 VerifyAfterGC, "too expensive");
1618 #endif
1619 assert_locked_or_safepoint(SystemDictionary_lock);
1621 // First look in the loaded class array
1622 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1623 int d_index = dictionary()->hash_to_index(d_hash);
1624 return find_class(d_index, d_hash, class_name, loader_data);
1625 }
1628 // Get the next class in the diictionary.
1629 Klass* SystemDictionary::try_get_next_class() {
1630 return dictionary()->try_get_next_class();
1631 }
1634 // ----------------------------------------------------------------------------
1635 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1636 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1637 // before a new class is used.
1639 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1640 assert(k.not_null(), "just checking");
1641 assert_locked_or_safepoint(Compile_lock);
1643 // Link into hierachy. Make sure the vtables are initialized before linking into
1644 k->append_to_sibling_list(); // add to superklass/sibling list
1645 k->process_interfaces(THREAD); // handle all "implements" declarations
1646 k->set_init_state(InstanceKlass::loaded);
1647 // Now flush all code that depended on old class hierarchy.
1648 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1649 // Also, first reinitialize vtable because it may have gotten out of synch
1650 // while the new class wasn't connected to the class hierarchy.
1651 Universe::flush_dependents_on(k);
1652 }
1655 // ----------------------------------------------------------------------------
1656 // GC support
1658 // Following roots during mark-sweep is separated in two phases.
1659 //
1660 // The first phase follows preloaded classes and all other system
1661 // classes, since these will never get unloaded anyway.
1662 //
1663 // The second phase removes (unloads) unreachable classes from the
1664 // system dictionary and follows the remaining classes' contents.
1666 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1667 blk->do_oop(&_java_system_loader);
1668 blk->do_oop(&_system_loader_lock_obj);
1670 dictionary()->always_strong_oops_do(blk);
1672 // Visit extra methods
1673 invoke_method_table()->oops_do(blk);
1674 }
1676 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1677 // Follow all system classes and temporary placeholders in dictionary
1678 dictionary()->always_strong_classes_do(closure);
1680 // Placeholders. These represent classes we're actively loading.
1681 placeholders()->classes_do(closure);
1682 }
1684 // Calculate a "good" systemdictionary size based
1685 // on predicted or current loaded classes count
1686 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1687 int newsize = _old_default_sdsize;
1688 if ((classcount > 0) && !DumpSharedSpaces) {
1689 int desiredsize = classcount/_average_depth_goal;
1690 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1691 newsize = _primelist[++_sdgeneration]) {
1692 if (desiredsize <= newsize) {
1693 break;
1694 }
1695 }
1696 }
1697 return newsize;
1698 }
1700 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1701 // Note: anonymous classes are not in the SD.
1702 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
1703 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1704 bool has_dead_loaders = ClassLoaderDataGraph::do_unloading(is_alive);
1705 bool unloading_occurred = false;
1706 if (has_dead_loaders) {
1707 unloading_occurred = dictionary()->do_unloading();
1708 constraints()->purge_loader_constraints();
1709 resolution_errors()->purge_resolution_errors();
1710 }
1711 return unloading_occurred;
1712 }
1714 void SystemDictionary::oops_do(OopClosure* f) {
1715 f->do_oop(&_java_system_loader);
1716 f->do_oop(&_system_loader_lock_obj);
1718 // Adjust dictionary
1719 dictionary()->oops_do(f);
1721 // Visit extra methods
1722 invoke_method_table()->oops_do(f);
1723 }
1725 // Extended Class redefinition support.
1726 // If one of these classes is replaced, we need to replace it in these places.
1727 // KlassClosure::do_klass should take the address of a class but we can
1728 // change that later.
1729 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1730 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1731 f->do_klass(_well_known_klasses[k]);
1732 }
1734 {
1735 for (int i = 0; i < T_VOID+1; i++) {
1736 if (_box_klasses[i] != NULL) {
1737 assert(i >= T_BOOLEAN, "checking");
1738 f->do_klass(_box_klasses[i]);
1739 }
1740 }
1741 }
1743 FilteredFieldsMap::classes_do(f);
1744 }
1746 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1747 f->do_klass(_abstract_ownable_synchronizer_klass);
1748 }
1750 // Just the classes from defining class loaders
1751 // Don't iterate over placeholders
1752 void SystemDictionary::classes_do(void f(Klass*)) {
1753 dictionary()->classes_do(f);
1754 }
1756 // Added for initialize_itable_for_klass
1757 // Just the classes from defining class loaders
1758 // Don't iterate over placeholders
1759 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1760 dictionary()->classes_do(f, CHECK);
1761 }
1763 // All classes, and their class loaders
1764 // Don't iterate over placeholders
1765 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1766 dictionary()->classes_do(f);
1767 }
1769 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1770 placeholders()->entries_do(f);
1771 }
1773 void SystemDictionary::methods_do(void f(Method*)) {
1774 dictionary()->methods_do(f);
1775 invoke_method_table()->methods_do(f);
1776 }
1778 // ----------------------------------------------------------------------------
1779 // Lazily load klasses
1781 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1782 assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");
1784 // if multiple threads calling this function, only one thread will load
1785 // the class. The other threads will find the loaded version once the
1786 // class is loaded.
1787 Klass* aos = _abstract_ownable_synchronizer_klass;
1788 if (aos == NULL) {
1789 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1790 // Force a fence to prevent any read before the write completes
1791 OrderAccess::fence();
1792 _abstract_ownable_synchronizer_klass = k;
1793 }
1794 }
1796 // ----------------------------------------------------------------------------
1797 // Initialization
1799 void SystemDictionary::initialize(TRAPS) {
1800 // Allocate arrays
1801 assert(dictionary() == NULL,
1802 "SystemDictionary should only be initialized once");
1803 _sdgeneration = 0;
1804 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1805 _placeholders = new PlaceholderTable(_nof_buckets);
1806 _number_of_modifications = 0;
1807 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1808 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1809 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1811 // Allocate private object used as system class loader lock
1812 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1813 // Initialize basic classes
1814 initialize_preloaded_classes(CHECK);
1815 }
1817 // Compact table of directions on the initialization of klasses:
1818 static const short wk_init_info[] = {
1819 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1820 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1821 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1822 | (int)SystemDictionary::option ),
1823 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1824 #undef WK_KLASS_INIT_INFO
1825 0
1826 };
1828 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1829 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1830 int info = wk_init_info[id - FIRST_WKID];
1831 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1832 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1833 Klass** klassp = &_well_known_klasses[id];
1834 bool must_load = (init_opt < SystemDictionary::Opt);
1835 if ((*klassp) == NULL) {
1836 if (must_load) {
1837 (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class
1838 } else {
1839 (*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass
1840 }
1841 }
1842 return ((*klassp) != NULL);
1843 }
1845 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1846 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1847 for (int id = (int)start_id; id < (int)limit_id; id++) {
1848 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1849 int info = wk_init_info[id - FIRST_WKID];
1850 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1851 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1853 initialize_wk_klass((WKID)id, opt, CHECK);
1854 }
1856 // move the starting value forward to the limit:
1857 start_id = limit_id;
1858 }
1860 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1861 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1862 // Preload commonly used klasses
1863 WKID scan = FIRST_WKID;
1864 // first do Object, then String, Class
1865 if (UseSharedSpaces) {
1866 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1867 // Initialize the constant pool for the Object_class
1868 InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1869 ik->constants()->restore_unshareable_info(CHECK);
1870 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1871 } else {
1872 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1873 }
1875 // Calculate offsets for String and Class classes since they are loaded and
1876 // can be used after this point.
1877 java_lang_String::compute_offsets();
1878 java_lang_Class::compute_offsets();
1880 // Fixup mirrors for classes loaded before java.lang.Class.
1881 // These calls iterate over the objects currently in the perm gen
1882 // so calling them at this point is matters (not before when there
1883 // are fewer objects and not later after there are more objects
1884 // in the perm gen.
1885 Universe::initialize_basic_type_mirrors(CHECK);
1886 Universe::fixup_mirrors(CHECK);
1888 // do a bunch more:
1889 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1891 // Preload ref klasses and set reference types
1892 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1893 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1895 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
1896 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1897 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1898 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1899 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1901 // JSR 292 classes
1902 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1903 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1904 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1905 if (EnableInvokeDynamic) {
1906 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1907 } else {
1908 // Skip the JSR 292 classes, if not enabled.
1909 scan = WKID(jsr292_group_end + 1);
1910 }
1912 initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);
1914 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1915 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
1916 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
1917 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
1918 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
1919 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
1920 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
1921 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
1922 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
1923 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
1925 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
1926 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
1927 _has_loadClassInternal = (method != NULL);
1928 }
1929 { // Compute whether we should use checkPackageAccess or NOT
1930 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
1931 _has_checkPackageAccess = (method != NULL);
1932 }
1933 }
1935 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
1936 // If so, returns the basic type it holds. If not, returns T_OBJECT.
1937 BasicType SystemDictionary::box_klass_type(Klass* k) {
1938 assert(k != NULL, "");
1939 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
1940 if (_box_klasses[i] == k)
1941 return (BasicType)i;
1942 }
1943 return T_OBJECT;
1944 }
1946 // Constraints on class loaders. The details of the algorithm can be
1947 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1948 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1949 // that the system dictionary needs to maintain a set of contraints that
1950 // must be satisfied by all classes in the dictionary.
1951 // if defining is true, then LinkageError if already in systemDictionary
1952 // if initiating loader, then ok if InstanceKlass matches existing entry
1954 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
1955 instanceKlassHandle k,
1956 Handle class_loader, bool defining,
1957 TRAPS) {
1958 const char *linkage_error = NULL;
1959 {
1960 Symbol* name = k->name();
1961 ClassLoaderData *loader_data = class_loader_data(class_loader);
1963 MutexLocker mu(SystemDictionary_lock, THREAD);
1965 Klass* check = find_class(d_index, d_hash, name, loader_data);
1966 if (check != (Klass*)NULL) {
1967 // if different InstanceKlass - duplicate class definition,
1968 // else - ok, class loaded by a different thread in parallel,
1969 // we should only have found it if it was done loading and ok to use
1970 // system dictionary only holds instance classes, placeholders
1971 // also holds array classes
1973 assert(check->oop_is_instance(), "noninstance in systemdictionary");
1974 if ((defining == true) || (k() != check)) {
1975 linkage_error = "loader (instance of %s): attempted duplicate class "
1976 "definition for name: \"%s\"";
1977 } else {
1978 return;
1979 }
1980 }
1982 #ifdef ASSERT
1983 Symbol* ph_check = find_placeholder(name, loader_data);
1984 assert(ph_check == NULL || ph_check == name, "invalid symbol");
1985 #endif
1987 if (linkage_error == NULL) {
1988 if (constraints()->check_or_update(k, class_loader, name) == false) {
1989 linkage_error = "loader constraint violation: loader (instance of %s)"
1990 " previously initiated loading for a different type with name \"%s\"";
1991 }
1992 }
1993 }
1995 // Throw error now if needed (cannot throw while holding
1996 // SystemDictionary_lock because of rank ordering)
1998 if (linkage_error) {
1999 ResourceMark rm(THREAD);
2000 const char* class_loader_name = loader_name(class_loader());
2001 char* type_name = k->name()->as_C_string();
2002 size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +
2003 strlen(type_name);
2004 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2005 jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);
2006 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2007 }
2008 }
2011 // Update system dictionary - done after check_constraint and add_to_hierachy
2012 // have been called.
2013 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2014 int p_index, unsigned int p_hash,
2015 instanceKlassHandle k,
2016 Handle class_loader,
2017 TRAPS) {
2018 // Compile_lock prevents systemDictionary updates during compilations
2019 assert_locked_or_safepoint(Compile_lock);
2020 Symbol* name = k->name();
2021 ClassLoaderData *loader_data = class_loader_data(class_loader);
2023 {
2024 MutexLocker mu1(SystemDictionary_lock, THREAD);
2026 // See whether biased locking is enabled and if so set it for this
2027 // klass.
2028 // Note that this must be done past the last potential blocking
2029 // point / safepoint. We enable biased locking lazily using a
2030 // VM_Operation to iterate the SystemDictionary and installing the
2031 // biasable mark word into each InstanceKlass's prototype header.
2032 // To avoid race conditions where we accidentally miss enabling the
2033 // optimization for one class in the process of being added to the
2034 // dictionary, we must not safepoint after the test of
2035 // BiasedLocking::enabled().
2036 if (UseBiasedLocking && BiasedLocking::enabled()) {
2037 // Set biased locking bit for all loaded classes; it will be
2038 // cleared if revocation occurs too often for this type
2039 // NOTE that we must only do this when the class is initally
2040 // defined, not each time it is referenced from a new class loader
2041 if (k->class_loader() == class_loader()) {
2042 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2043 }
2044 }
2046 // Make a new system dictionary entry.
2047 Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2048 if (sd_check == NULL) {
2049 dictionary()->add_klass(name, loader_data, k);
2050 notice_modification();
2051 }
2052 #ifdef ASSERT
2053 sd_check = find_class(d_index, d_hash, name, loader_data);
2054 assert (sd_check != NULL, "should have entry in system dictionary");
2055 // Note: there may be a placeholder entry: for circularity testing
2056 // or for parallel defines
2057 #endif
2058 SystemDictionary_lock->notify_all();
2059 }
2060 }
2063 // Try to find a class name using the loader constraints. The
2064 // loader constraints might know about a class that isn't fully loaded
2065 // yet and these will be ignored.
2066 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2067 Symbol* class_name, Handle class_loader, TRAPS) {
2069 // First see if it has been loaded directly.
2070 // Force the protection domain to be null. (This removes protection checks.)
2071 Handle no_protection_domain;
2072 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2073 no_protection_domain, CHECK_NULL);
2074 if (klass != NULL)
2075 return klass;
2077 // Now look to see if it has been loaded elsewhere, and is subject to
2078 // a loader constraint that would require this loader to return the
2079 // klass that is already loaded.
2080 if (FieldType::is_array(class_name)) {
2081 // For array classes, their Klass*s are not kept in the
2082 // constraint table. The element Klass*s are.
2083 FieldArrayInfo fd;
2084 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2085 if (t != T_OBJECT) {
2086 klass = Universe::typeArrayKlassObj(t);
2087 } else {
2088 MutexLocker mu(SystemDictionary_lock, THREAD);
2089 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2090 }
2091 // If element class already loaded, allocate array klass
2092 if (klass != NULL) {
2093 klass = klass->array_klass_or_null(fd.dimension());
2094 }
2095 } else {
2096 MutexLocker mu(SystemDictionary_lock, THREAD);
2097 // Non-array classes are easy: simply check the constraint table.
2098 klass = constraints()->find_constrained_klass(class_name, class_loader);
2099 }
2101 return klass;
2102 }
2105 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2106 Handle class_loader1,
2107 Handle class_loader2,
2108 Thread* THREAD) {
2109 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2110 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2112 Symbol* constraint_name = NULL;
2113 if (!FieldType::is_array(class_name)) {
2114 constraint_name = class_name;
2115 } else {
2116 // For array classes, their Klass*s are not kept in the
2117 // constraint table. The element classes are.
2118 FieldArrayInfo fd;
2119 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2120 // primitive types always pass
2121 if (t != T_OBJECT) {
2122 return true;
2123 } else {
2124 constraint_name = fd.object_key();
2125 }
2126 }
2127 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2128 int d_index1 = dictionary()->hash_to_index(d_hash1);
2130 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2131 int d_index2 = dictionary()->hash_to_index(d_hash2);
2132 {
2133 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2135 // Better never do a GC while we're holding these oops
2136 No_Safepoint_Verifier nosafepoint;
2138 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2139 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2140 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2141 klass2, class_loader2);
2142 }
2143 }
2145 // Add entry to resolution error table to record the error when the first
2146 // attempt to resolve a reference to a class has failed.
2147 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) {
2148 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2149 int index = resolution_errors()->hash_to_index(hash);
2150 {
2151 MutexLocker ml(SystemDictionary_lock, Thread::current());
2152 resolution_errors()->add_entry(index, hash, pool, which, error);
2153 }
2154 }
2156 // Delete a resolution error for RedefineClasses for a constant pool is going away
2157 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2158 resolution_errors()->delete_entry(pool);
2159 }
2161 // Lookup resolution error table. Returns error if found, otherwise NULL.
2162 Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {
2163 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2164 int index = resolution_errors()->hash_to_index(hash);
2165 {
2166 MutexLocker ml(SystemDictionary_lock, Thread::current());
2167 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2168 return (entry != NULL) ? entry->error() : (Symbol*)NULL;
2169 }
2170 }
2173 // Signature constraints ensure that callers and callees agree about
2174 // the meaning of type names in their signatures. This routine is the
2175 // intake for constraints. It collects them from several places:
2176 //
2177 // * LinkResolver::resolve_method (if check_access is true) requires
2178 // that the resolving class (the caller) and the defining class of
2179 // the resolved method (the callee) agree on each type in the
2180 // method's signature.
2181 //
2182 // * LinkResolver::resolve_interface_method performs exactly the same
2183 // checks.
2184 //
2185 // * LinkResolver::resolve_field requires that the constant pool
2186 // attempting to link to a field agree with the field's defining
2187 // class about the type of the field signature.
2188 //
2189 // * klassVtable::initialize_vtable requires that, when a class
2190 // overrides a vtable entry allocated by a superclass, that the
2191 // overriding method (i.e., the callee) agree with the superclass
2192 // on each type in the method's signature.
2193 //
2194 // * klassItable::initialize_itable requires that, when a class fills
2195 // in its itables, for each non-abstract method installed in an
2196 // itable, the method (i.e., the callee) agree with the interface
2197 // on each type in the method's signature.
2198 //
2199 // All those methods have a boolean (check_access, checkconstraints)
2200 // which turns off the checks. This is used from specialized contexts
2201 // such as bootstrapping, dumping, and debugging.
2202 //
2203 // No direct constraint is placed between the class and its
2204 // supertypes. Constraints are only placed along linked relations
2205 // between callers and callees. When a method overrides or implements
2206 // an abstract method in a supertype (superclass or interface), the
2207 // constraints are placed as if the supertype were the caller to the
2208 // overriding method. (This works well, since callers to the
2209 // supertype have already established agreement between themselves and
2210 // the supertype.) As a result of all this, a class can disagree with
2211 // its supertype about the meaning of a type name, as long as that
2212 // class neither calls a relevant method of the supertype, nor is
2213 // called (perhaps via an override) from the supertype.
2214 //
2215 //
2216 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2217 //
2218 // Make sure all class components (including arrays) in the given
2219 // signature will be resolved to the same class in both loaders.
2220 // Returns the name of the type that failed a loader constraint check, or
2221 // NULL if no constraint failed. No exception except OOME is thrown.
2222 // Arrays are not added to the loader constraint table, their elements are.
2223 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2224 Handle loader1, Handle loader2,
2225 bool is_method, TRAPS) {
2226 // Nothing to do if loaders are the same.
2227 if (loader1() == loader2()) {
2228 return NULL;
2229 }
2231 SignatureStream sig_strm(signature, is_method);
2232 while (!sig_strm.is_done()) {
2233 if (sig_strm.is_object()) {
2234 Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2235 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2236 return sig;
2237 }
2238 }
2239 sig_strm.next();
2240 }
2241 return NULL;
2242 }
2245 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2246 Symbol* signature,
2247 TRAPS) {
2248 methodHandle empty;
2249 assert(EnableInvokeDynamic, "");
2250 assert(MethodHandles::is_signature_polymorphic(iid) &&
2251 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2252 iid != vmIntrinsics::_invokeGeneric,
2253 err_msg("must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)));
2255 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2256 int index = invoke_method_table()->hash_to_index(hash);
2257 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2258 methodHandle m;
2259 if (spe == NULL || spe->method() == NULL) {
2260 spe = NULL;
2261 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2262 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2263 CompileBroker::compile_method(m, InvocationEntryBci, CompLevel_highest_tier,
2264 methodHandle(), CompileThreshold, "MH", CHECK_(empty));
2266 // Now grab the lock. We might have to throw away the new method,
2267 // if a racing thread has managed to install one at the same time.
2268 {
2269 MutexLocker ml(SystemDictionary_lock, THREAD);
2270 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2271 if (spe == NULL)
2272 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2273 if (spe->method() == NULL)
2274 spe->set_method(m());
2275 }
2276 }
2278 assert(spe != NULL && spe->method() != NULL, "");
2279 return spe->method();
2280 }
2282 // Helper for unpacking the return value from linkMethod and linkCallSite.
2283 static methodHandle unpack_method_and_appendix(Handle mname,
2284 KlassHandle accessing_klass,
2285 objArrayHandle appendix_box,
2286 Handle* appendix_result,
2287 TRAPS) {
2288 methodHandle empty;
2289 if (mname.not_null()) {
2290 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2291 if (vmtarget != NULL && vmtarget->is_method()) {
2292 Method* m = (Method*)vmtarget;
2293 oop appendix = appendix_box->obj_at(0);
2294 if (TraceMethodHandles) {
2295 #ifndef PRODUCT
2296 tty->print("Linked method="INTPTR_FORMAT": ", m);
2297 m->print();
2298 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2299 tty->cr();
2300 #endif //PRODUCT
2301 }
2302 (*appendix_result) = Handle(THREAD, appendix);
2303 // the target is stored in the cpCache and if a reference to this
2304 // MethodName is dropped we need a way to make sure the
2305 // class_loader containing this method is kept alive.
2306 // FIXME: the appendix might also preserve this dependency.
2307 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2308 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2309 return methodHandle(THREAD, m);
2310 }
2311 }
2312 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2313 return empty;
2314 }
2316 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2317 Symbol* signature,
2318 KlassHandle accessing_klass,
2319 Handle *appendix_result,
2320 Handle *method_type_result,
2321 TRAPS) {
2322 methodHandle empty;
2323 assert(EnableInvokeDynamic, "");
2324 assert(!THREAD->is_Compiler_thread(), "");
2325 Handle method_type =
2326 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2327 if (false) { // FIXME: Decide if the Java upcall should resolve signatures.
2328 method_type = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2329 }
2331 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass();
2332 int ref_kind = JVM_REF_invokeVirtual;
2333 Handle name_str = StringTable::intern(name, CHECK_(empty));
2334 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2335 assert(appendix_box->obj_at(0) == NULL, "");
2337 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2338 JavaCallArguments args;
2339 args.push_oop(accessing_klass()->java_mirror());
2340 args.push_int(ref_kind);
2341 args.push_oop(mh_klass()->java_mirror());
2342 args.push_oop(name_str());
2343 args.push_oop(method_type());
2344 args.push_oop(appendix_box());
2345 JavaValue result(T_OBJECT);
2346 JavaCalls::call_static(&result,
2347 SystemDictionary::MethodHandleNatives_klass(),
2348 vmSymbols::linkMethod_name(),
2349 vmSymbols::linkMethod_signature(),
2350 &args, CHECK_(empty));
2351 Handle mname(THREAD, (oop) result.get_jobject());
2352 (*method_type_result) = method_type;
2353 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2354 }
2357 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2358 // signature, as interpreted relative to the given class loader.
2359 // Because of class loader constraints, all method handle usage must be
2360 // consistent with this loader.
2361 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2362 KlassHandle accessing_klass,
2363 TRAPS) {
2364 Handle empty;
2365 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2366 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2367 int index = invoke_method_table()->hash_to_index(hash);
2368 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2369 if (spe != NULL && spe->method_type() != NULL) {
2370 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2371 return Handle(THREAD, spe->method_type());
2372 } else if (THREAD->is_Compiler_thread()) {
2373 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2374 return Handle(); // do not attempt from within compiler, unless it was cached
2375 }
2377 Handle class_loader, protection_domain;
2378 bool is_on_bcp = true; // keep this true as long as we can materialize from the boot classloader
2379 int npts = ArgumentCount(signature).size();
2380 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2381 int arg = 0;
2382 Handle rt; // the return type from the signature
2383 ResourceMark rm(THREAD);
2384 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2385 oop mirror = NULL;
2386 if (is_on_bcp) {
2387 // Note: class_loader & protection_domain are both null at this point.
2388 mirror = ss.as_java_mirror(class_loader, protection_domain,
2389 SignatureStream::ReturnNull, CHECK_(empty));
2390 if (mirror == NULL) {
2391 // fall back from BCP to accessing_klass
2392 if (accessing_klass.not_null()) {
2393 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2394 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2395 }
2396 is_on_bcp = false;
2397 }
2398 }
2399 if (!is_on_bcp) {
2400 // Resolve, throwing a real error if it doesn't work.
2401 mirror = ss.as_java_mirror(class_loader, protection_domain,
2402 SignatureStream::NCDFError, CHECK_(empty));
2403 }
2404 if (ss.at_return_type())
2405 rt = Handle(THREAD, mirror);
2406 else
2407 pts->obj_at_put(arg++, mirror);
2409 // Check accessibility.
2410 if (ss.is_object() && accessing_klass.not_null()) {
2411 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2412 mirror = NULL; // safety
2413 // Emulate ConstantPool::verify_constant_pool_resolve.
2414 if (sel_klass->oop_is_objArray())
2415 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2416 if (sel_klass->oop_is_instance()) {
2417 KlassHandle sel_kh(THREAD, sel_klass);
2418 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2419 }
2420 }
2421 }
2422 assert(arg == npts, "");
2424 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2425 JavaCallArguments args(Handle(THREAD, rt()));
2426 args.push_oop(pts());
2427 JavaValue result(T_OBJECT);
2428 JavaCalls::call_static(&result,
2429 SystemDictionary::MethodHandleNatives_klass(),
2430 vmSymbols::findMethodHandleType_name(),
2431 vmSymbols::findMethodHandleType_signature(),
2432 &args, CHECK_(empty));
2433 Handle method_type(THREAD, (oop) result.get_jobject());
2435 if (is_on_bcp) {
2436 // We can cache this MethodType inside the JVM.
2437 MutexLocker ml(SystemDictionary_lock, THREAD);
2438 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2439 if (spe == NULL)
2440 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2441 if (spe->method_type() == NULL) {
2442 spe->set_method_type(method_type());
2443 }
2444 }
2446 // report back to the caller with the MethodType
2447 return method_type;
2448 }
2450 // Ask Java code to find or construct a method handle constant.
2451 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2452 int ref_kind, //e.g., JVM_REF_invokeVirtual
2453 KlassHandle callee,
2454 Symbol* name_sym,
2455 Symbol* signature,
2456 TRAPS) {
2457 Handle empty;
2458 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2459 Handle type;
2460 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2461 type = find_method_handle_type(signature, caller, CHECK_(empty));
2462 } else {
2463 ResourceMark rm(THREAD);
2464 SignatureStream ss(signature, false);
2465 if (!ss.is_done()) {
2466 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2467 SignatureStream::NCDFError, CHECK_(empty));
2468 type = Handle(THREAD, mirror);
2469 ss.next();
2470 if (!ss.is_done()) type = Handle(); // error!
2471 }
2472 }
2473 if (type.is_null()) {
2474 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2475 }
2477 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2478 JavaCallArguments args;
2479 args.push_oop(caller->java_mirror()); // the referring class
2480 args.push_int(ref_kind);
2481 args.push_oop(callee->java_mirror()); // the target class
2482 args.push_oop(name());
2483 args.push_oop(type());
2484 JavaValue result(T_OBJECT);
2485 JavaCalls::call_static(&result,
2486 SystemDictionary::MethodHandleNatives_klass(),
2487 vmSymbols::linkMethodHandleConstant_name(),
2488 vmSymbols::linkMethodHandleConstant_signature(),
2489 &args, CHECK_(empty));
2490 return Handle(THREAD, (oop) result.get_jobject());
2491 }
2493 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2494 // name and signature, as interpreted relative to the given class loader.
2495 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2496 Handle bootstrap_specifier,
2497 Symbol* name,
2498 Symbol* type,
2499 Handle *appendix_result,
2500 Handle *method_type_result,
2501 TRAPS) {
2502 methodHandle empty;
2503 Handle bsm, info;
2504 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2505 bsm = bootstrap_specifier;
2506 } else {
2507 assert(bootstrap_specifier->is_objArray(), "");
2508 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2509 int len = args->length();
2510 assert(len >= 1, "");
2511 bsm = Handle(THREAD, args->obj_at(0));
2512 if (len > 1) {
2513 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2514 for (int i = 1; i < len; i++)
2515 args1->obj_at_put(i-1, args->obj_at(i));
2516 info = Handle(THREAD, args1);
2517 }
2518 }
2519 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2520 "caller must supply a valid BSM");
2522 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2523 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2525 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2526 assert(appendix_box->obj_at(0) == NULL, "");
2528 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2529 JavaCallArguments args;
2530 args.push_oop(caller->java_mirror());
2531 args.push_oop(bsm());
2532 args.push_oop(method_name());
2533 args.push_oop(method_type());
2534 args.push_oop(info());
2535 args.push_oop(appendix_box);
2536 JavaValue result(T_OBJECT);
2537 JavaCalls::call_static(&result,
2538 SystemDictionary::MethodHandleNatives_klass(),
2539 vmSymbols::linkCallSite_name(),
2540 vmSymbols::linkCallSite_signature(),
2541 &args, CHECK_(empty));
2542 Handle mname(THREAD, (oop) result.get_jobject());
2543 (*method_type_result) = method_type;
2544 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2545 }
2547 // Since the identity hash code for symbols changes when the symbols are
2548 // moved from the regular perm gen (hash in the mark word) to the shared
2549 // spaces (hash is the address), the classes loaded into the dictionary
2550 // may be in the wrong buckets.
2552 void SystemDictionary::reorder_dictionary() {
2553 dictionary()->reorder_dictionary();
2554 }
2557 void SystemDictionary::copy_buckets(char** top, char* end) {
2558 dictionary()->copy_buckets(top, end);
2559 }
2562 void SystemDictionary::copy_table(char** top, char* end) {
2563 dictionary()->copy_table(top, end);
2564 }
2567 void SystemDictionary::reverse() {
2568 dictionary()->reverse();
2569 }
2571 int SystemDictionary::number_of_classes() {
2572 return dictionary()->number_of_entries();
2573 }
2576 // ----------------------------------------------------------------------------
2577 #ifndef PRODUCT
2579 void SystemDictionary::print() {
2580 dictionary()->print();
2582 // Placeholders
2583 GCMutexLocker mu(SystemDictionary_lock);
2584 placeholders()->print();
2586 // loader constraints - print under SD_lock
2587 constraints()->print();
2588 }
2590 #endif
2592 void SystemDictionary::verify() {
2593 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2594 guarantee(constraints() != NULL,
2595 "Verify of loader constraints failed");
2596 guarantee(dictionary()->number_of_entries() >= 0 &&
2597 placeholders()->number_of_entries() >= 0,
2598 "Verify of system dictionary failed");
2600 // Verify dictionary
2601 dictionary()->verify();
2603 GCMutexLocker mu(SystemDictionary_lock);
2604 placeholders()->verify();
2606 // Verify constraint table
2607 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2608 constraints()->verify(dictionary(), placeholders());
2609 }
2612 void SystemDictionary::verify_obj_klass_present(Symbol* class_name,
2613 ClassLoaderData* loader_data) {
2614 GCMutexLocker mu(SystemDictionary_lock);
2615 Symbol* name;
2617 Klass* probe = find_class(class_name, loader_data);
2618 if (probe == NULL) {
2619 probe = SystemDictionary::find_shared_class(class_name);
2620 if (probe == NULL) {
2621 name = find_placeholder(class_name, loader_data);
2622 }
2623 }
2624 guarantee(probe != NULL || name != NULL,
2625 "Loaded klasses should be in SystemDictionary");
2626 }
2628 // utility function for class load event
2629 void SystemDictionary::post_class_load_event(TracingTime start_time,
2630 instanceKlassHandle k,
2631 Handle initiating_loader) {
2632 #if INCLUDE_TRACE
2633 EventClassLoad event(UNTIMED);
2634 if (event.should_commit()) {
2635 event.set_endtime(Tracing::time());
2636 event.set_starttime(start_time);
2637 event.set_loadedClass(k());
2638 oop defining_class_loader = k->class_loader();
2639 event.set_definingClassLoader(defining_class_loader != NULL ?
2640 defining_class_loader->klass() : (Klass*)NULL);
2641 oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
2642 event.set_initiatingClassLoader(class_loader != NULL ?
2643 class_loader->klass() : (Klass*)NULL);
2644 event.commit();
2645 }
2646 #endif /* INCLUDE_TRACE */
2647 }
2649 #ifndef PRODUCT
2651 // statistics code
2652 class ClassStatistics: AllStatic {
2653 private:
2654 static int nclasses; // number of classes
2655 static int nmethods; // number of methods
2656 static int nmethoddata; // number of methodData
2657 static int class_size; // size of class objects in words
2658 static int method_size; // size of method objects in words
2659 static int debug_size; // size of debug info in methods
2660 static int methoddata_size; // size of methodData objects in words
2662 static void do_class(Klass* k) {
2663 nclasses++;
2664 class_size += k->size();
2665 if (k->oop_is_instance()) {
2666 InstanceKlass* ik = (InstanceKlass*)k;
2667 class_size += ik->methods()->size();
2668 class_size += ik->constants()->size();
2669 class_size += ik->local_interfaces()->size();
2670 class_size += ik->transitive_interfaces()->size();
2671 // We do not have to count implementors, since we only store one!
2672 // SSS: How should these be accounted now that they have moved?
2673 // class_size += ik->fields()->length();
2674 }
2675 }
2677 static void do_method(Method* m) {
2678 nmethods++;
2679 method_size += m->size();
2680 // class loader uses same objArray for empty vectors, so don't count these
2681 if (m->has_stackmap_table()) {
2682 method_size += m->stackmap_data()->size();
2683 }
2685 MethodData* mdo = m->method_data();
2686 if (mdo != NULL) {
2687 nmethoddata++;
2688 methoddata_size += mdo->size();
2689 }
2690 }
2692 public:
2693 static void print() {
2694 SystemDictionary::classes_do(do_class);
2695 SystemDictionary::methods_do(do_method);
2696 tty->print_cr("Class statistics:");
2697 tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
2698 tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
2699 (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
2700 tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
2701 }
2702 };
2705 int ClassStatistics::nclasses = 0;
2706 int ClassStatistics::nmethods = 0;
2707 int ClassStatistics::nmethoddata = 0;
2708 int ClassStatistics::class_size = 0;
2709 int ClassStatistics::method_size = 0;
2710 int ClassStatistics::debug_size = 0;
2711 int ClassStatistics::methoddata_size = 0;
2713 void SystemDictionary::print_class_statistics() {
2714 ResourceMark rm;
2715 ClassStatistics::print();
2716 }
2719 class MethodStatistics: AllStatic {
2720 public:
2721 enum {
2722 max_parameter_size = 10
2723 };
2724 private:
2726 static int _number_of_methods;
2727 static int _number_of_final_methods;
2728 static int _number_of_static_methods;
2729 static int _number_of_native_methods;
2730 static int _number_of_synchronized_methods;
2731 static int _number_of_profiled_methods;
2732 static int _number_of_bytecodes;
2733 static int _parameter_size_profile[max_parameter_size];
2734 static int _bytecodes_profile[Bytecodes::number_of_java_codes];
2736 static void initialize() {
2737 _number_of_methods = 0;
2738 _number_of_final_methods = 0;
2739 _number_of_static_methods = 0;
2740 _number_of_native_methods = 0;
2741 _number_of_synchronized_methods = 0;
2742 _number_of_profiled_methods = 0;
2743 _number_of_bytecodes = 0;
2744 for (int i = 0; i < max_parameter_size ; i++) _parameter_size_profile[i] = 0;
2745 for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile [j] = 0;
2746 };
2748 static void do_method(Method* m) {
2749 _number_of_methods++;
2750 // collect flag info
2751 if (m->is_final() ) _number_of_final_methods++;
2752 if (m->is_static() ) _number_of_static_methods++;
2753 if (m->is_native() ) _number_of_native_methods++;
2754 if (m->is_synchronized()) _number_of_synchronized_methods++;
2755 if (m->method_data() != NULL) _number_of_profiled_methods++;
2756 // collect parameter size info (add one for receiver, if any)
2757 _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
2758 // collect bytecodes info
2759 {
2760 Thread *thread = Thread::current();
2761 HandleMark hm(thread);
2762 BytecodeStream s(methodHandle(thread, m));
2763 Bytecodes::Code c;
2764 while ((c = s.next()) >= 0) {
2765 _number_of_bytecodes++;
2766 _bytecodes_profile[c]++;
2767 }
2768 }
2769 }
2771 public:
2772 static void print() {
2773 initialize();
2774 SystemDictionary::methods_do(do_method);
2775 // generate output
2776 tty->cr();
2777 tty->print_cr("Method statistics (static):");
2778 // flag distribution
2779 tty->cr();
2780 tty->print_cr("%6d final methods %6.1f%%", _number_of_final_methods , _number_of_final_methods * 100.0F / _number_of_methods);
2781 tty->print_cr("%6d static methods %6.1f%%", _number_of_static_methods , _number_of_static_methods * 100.0F / _number_of_methods);
2782 tty->print_cr("%6d native methods %6.1f%%", _number_of_native_methods , _number_of_native_methods * 100.0F / _number_of_methods);
2783 tty->print_cr("%6d synchronized methods %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
2784 tty->print_cr("%6d profiled methods %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
2785 // parameter size profile
2786 tty->cr();
2787 { int tot = 0;
2788 int avg = 0;
2789 for (int i = 0; i < max_parameter_size; i++) {
2790 int n = _parameter_size_profile[i];
2791 tot += n;
2792 avg += n*i;
2793 tty->print_cr("parameter size = %1d: %6d methods %5.1f%%", i, n, n * 100.0F / _number_of_methods);
2794 }
2795 assert(tot == _number_of_methods, "should be the same");
2796 tty->print_cr(" %6d methods 100.0%%", _number_of_methods);
2797 tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
2798 }
2799 // bytecodes profile
2800 tty->cr();
2801 { int tot = 0;
2802 for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
2803 if (Bytecodes::is_defined(i)) {
2804 Bytecodes::Code c = Bytecodes::cast(i);
2805 int n = _bytecodes_profile[c];
2806 tot += n;
2807 tty->print_cr("%9d %7.3f%% %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
2808 }
2809 }
2810 assert(tot == _number_of_bytecodes, "should be the same");
2811 tty->print_cr("%9d 100.000%%", _number_of_bytecodes);
2812 }
2813 tty->cr();
2814 }
2815 };
2817 int MethodStatistics::_number_of_methods;
2818 int MethodStatistics::_number_of_final_methods;
2819 int MethodStatistics::_number_of_static_methods;
2820 int MethodStatistics::_number_of_native_methods;
2821 int MethodStatistics::_number_of_synchronized_methods;
2822 int MethodStatistics::_number_of_profiled_methods;
2823 int MethodStatistics::_number_of_bytecodes;
2824 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
2825 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
2828 void SystemDictionary::print_method_statistics() {
2829 MethodStatistics::print();
2830 }
2832 #endif // PRODUCT