Mon, 07 Jul 2014 10:12:40 +0200
8049421: G1 Class Unloading after completing a concurrent mark cycle
Reviewed-by: tschatzl, ehelin, brutisso, coleenp, roland, iveresov
Contributed-by: stefan.karlsson@oracle.com, mikael.gerdin@oracle.com
1 /*
2 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
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/orderAccess.inline.hpp"
56 #include "runtime/signature.hpp"
57 #include "services/classLoadingService.hpp"
58 #include "services/threadService.hpp"
59 #include "utilities/macros.hpp"
60 #include "utilities/ticks.hpp"
62 #if INCLUDE_TRACE
63 #include "trace/tracing.hpp"
64 #endif
66 Dictionary* SystemDictionary::_dictionary = NULL;
67 PlaceholderTable* SystemDictionary::_placeholders = NULL;
68 Dictionary* SystemDictionary::_shared_dictionary = NULL;
69 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
70 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
71 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
74 int SystemDictionary::_number_of_modifications = 0;
75 int SystemDictionary::_sdgeneration = 0;
76 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
77 20201,40423,99991};
79 oop SystemDictionary::_system_loader_lock_obj = NULL;
81 Klass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
82 = { NULL /*, NULL...*/ };
84 Klass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
86 oop SystemDictionary::_java_system_loader = NULL;
88 bool SystemDictionary::_has_loadClassInternal = false;
89 bool SystemDictionary::_has_checkPackageAccess = false;
91 // lazily initialized klass variables
92 Klass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
95 // ----------------------------------------------------------------------------
96 // Java-level SystemLoader
98 oop SystemDictionary::java_system_loader() {
99 return _java_system_loader;
100 }
102 void SystemDictionary::compute_java_system_loader(TRAPS) {
103 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
104 JavaValue result(T_OBJECT);
105 JavaCalls::call_static(&result,
106 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
107 vmSymbols::getSystemClassLoader_name(),
108 vmSymbols::void_classloader_signature(),
109 CHECK);
111 _java_system_loader = (oop)result.get_jobject();
112 }
115 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
116 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
117 return ClassLoaderDataGraph::find_or_create(class_loader, CHECK_NULL);
118 }
120 // ----------------------------------------------------------------------------
121 // debugging
123 #ifdef ASSERT
125 // return true if class_name contains no '.' (internal format is '/')
126 bool SystemDictionary::is_internal_format(Symbol* class_name) {
127 if (class_name != NULL) {
128 ResourceMark rm;
129 char* name = class_name->as_C_string();
130 return strchr(name, '.') == NULL;
131 } else {
132 return true;
133 }
134 }
136 #endif
138 // ----------------------------------------------------------------------------
139 // Parallel class loading check
141 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
142 if (UnsyncloadClass || class_loader.is_null()) return true;
143 if (AlwaysLockClassLoader) return false;
144 return java_lang_ClassLoader::parallelCapable(class_loader());
145 }
146 // ----------------------------------------------------------------------------
147 // ParallelDefineClass flag does not apply to bootclass loader
148 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
149 if (class_loader.is_null()) return false;
150 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
151 return true;
152 }
153 return false;
154 }
156 /**
157 * Returns true if the passed class loader is the extension class loader.
158 */
159 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
160 if (class_loader.is_null()) {
161 return false;
162 }
163 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
164 }
166 // ----------------------------------------------------------------------------
167 // Resolving of classes
169 // Forwards to resolve_or_null
171 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
172 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
173 if (HAS_PENDING_EXCEPTION || klass == NULL) {
174 KlassHandle k_h(THREAD, klass);
175 // can return a null klass
176 klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);
177 }
178 return klass;
179 }
181 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {
182 if (HAS_PENDING_EXCEPTION) {
183 // If we have a pending exception we forward it to the caller, unless throw_error is true,
184 // in which case we have to check whether the pending exception is a ClassNotFoundException,
185 // and if so convert it to a NoClassDefFoundError
186 // And chain the original ClassNotFoundException
187 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
188 ResourceMark rm(THREAD);
189 assert(klass_h() == NULL, "Should not have result with exception pending");
190 Handle e(THREAD, PENDING_EXCEPTION);
191 CLEAR_PENDING_EXCEPTION;
192 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
193 } else {
194 return NULL;
195 }
196 }
197 // Class not found, throw appropriate error or exception depending on value of throw_error
198 if (klass_h() == NULL) {
199 ResourceMark rm(THREAD);
200 if (throw_error) {
201 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
202 } else {
203 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
204 }
205 }
206 return (Klass*)klass_h();
207 }
210 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
211 bool throw_error, TRAPS)
212 {
213 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
214 }
217 // Forwards to resolve_instance_class_or_null
219 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
220 assert(!THREAD->is_Compiler_thread(),
221 err_msg("can not load classes with compiler thread: class=%s, classloader=%s",
222 class_name->as_C_string(),
223 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()));
224 if (FieldType::is_array(class_name)) {
225 return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
226 } else if (FieldType::is_obj(class_name)) {
227 ResourceMark rm(THREAD);
228 // Ignore wrapping L and ;.
229 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
230 class_name->utf8_length() - 2, CHECK_NULL);
231 return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL);
232 } else {
233 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
234 }
235 }
237 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
238 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
239 }
241 // Forwards to resolve_instance_class_or_null
243 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
244 Handle class_loader,
245 Handle protection_domain,
246 TRAPS) {
247 assert(FieldType::is_array(class_name), "must be array");
248 Klass* k = NULL;
249 FieldArrayInfo fd;
250 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
251 // of this call
252 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
253 if (t == T_OBJECT) {
254 // naked oop "k" is OK here -- we assign back into it
255 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
256 class_loader,
257 protection_domain,
258 CHECK_NULL);
259 if (k != NULL) {
260 k = k->array_klass(fd.dimension(), CHECK_NULL);
261 }
262 } else {
263 k = Universe::typeArrayKlassObj(t);
264 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
265 }
266 return k;
267 }
270 // Must be called for any super-class or super-interface resolution
271 // during class definition to allow class circularity checking
272 // super-interface callers:
273 // parse_interfaces - for defineClass & jvmtiRedefineClasses
274 // super-class callers:
275 // ClassFileParser - for defineClass & jvmtiRedefineClasses
276 // load_shared_class - while loading a class from shared archive
277 // resolve_instance_class_or_null:
278 // via: handle_parallel_super_load
279 // when resolving a class that has an existing placeholder with
280 // a saved superclass [i.e. a defineClass is currently in progress]
281 // if another thread is trying to resolve the class, it must do
282 // super-class checks on its own thread to catch class circularity
283 // This last call is critical in class circularity checking for cases
284 // where classloading is delegated to different threads and the
285 // classloader lock is released.
286 // Take the case: Base->Super->Base
287 // 1. If thread T1 tries to do a defineClass of class Base
288 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
289 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
290 // so it tries to load Super
291 // 3. If we load the class internally, or user classloader uses same thread
292 // loadClassFromxxx or defineClass via parseClassFile Super ...
293 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
294 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
295 // 3.4 calls resolve_super_or_fail Base
296 // 3.5 finds T1,Base -> throws class circularity
297 //OR 4. If T2 tries to resolve Super via defineClass Super ...
298 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
299 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
300 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
301 // 4.4 finds T2, Super -> throws class circularity
302 // Must be called, even if superclass is null, since this is
303 // where the placeholder entry is created which claims this
304 // thread is loading this class/classloader.
305 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
306 Symbol* class_name,
307 Handle class_loader,
308 Handle protection_domain,
309 bool is_superclass,
310 TRAPS) {
311 // Double-check, if child class is already loaded, just return super-class,interface
312 // Don't add a placedholder if already loaded, i.e. already in system dictionary
313 // Make sure there's a placeholder for the *child* before resolving.
314 // Used as a claim that this thread is currently loading superclass/classloader
315 // Used here for ClassCircularity checks and also for heap verification
316 // (every InstanceKlass in the heap needs to be in the system dictionary
317 // or have a placeholder).
318 // Must check ClassCircularity before checking if super class is already loaded
319 //
320 // We might not already have a placeholder if this child_name was
321 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
322 // the name of the class might not be known until the stream is actually
323 // parsed.
324 // Bugs 4643874, 4715493
325 // compute_hash can have a safepoint
327 ClassLoaderData* loader_data = class_loader_data(class_loader);
328 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
329 int d_index = dictionary()->hash_to_index(d_hash);
330 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
331 int p_index = placeholders()->hash_to_index(p_hash);
332 // can't throw error holding a lock
333 bool child_already_loaded = false;
334 bool throw_circularity_error = false;
335 {
336 MutexLocker mu(SystemDictionary_lock, THREAD);
337 Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
338 Klass* quicksuperk;
339 // to support // loading: if child done loading, just return superclass
340 // if class_name, & class_loader don't match:
341 // if initial define, SD update will give LinkageError
342 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
343 // so we don't throw an exception here.
344 // see: nsk redefclass014 & java.lang.instrument Instrument032
345 if ((childk != NULL ) && (is_superclass) &&
346 ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) &&
348 ((quicksuperk->name() == class_name) &&
349 (quicksuperk->class_loader() == class_loader()))) {
350 return quicksuperk;
351 } else {
352 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
353 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
354 throw_circularity_error = true;
355 }
356 }
357 if (!throw_circularity_error) {
358 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
359 }
360 }
361 if (throw_circularity_error) {
362 ResourceMark rm(THREAD);
363 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
364 }
366 // java.lang.Object should have been found above
367 assert(class_name != NULL, "null super class for resolving");
368 // Resolve the super class or interface, check results on return
369 Klass* superk = SystemDictionary::resolve_or_null(class_name,
370 class_loader,
371 protection_domain,
372 THREAD);
374 KlassHandle superk_h(THREAD, superk);
376 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
377 // It is no longer necessary to keep the placeholder table alive until update_dictionary
378 // or error. GC used to walk the placeholder table as strong roots.
379 // The instanceKlass is kept alive because the class loader is on the stack,
380 // which keeps the loader_data alive, as well as all instanceKlasses in
381 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
382 {
383 MutexLocker mu(SystemDictionary_lock, THREAD);
384 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
385 SystemDictionary_lock->notify_all();
386 }
387 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
388 // can null superk
389 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));
390 }
392 return superk_h();
393 }
395 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
396 Handle class_loader,
397 Handle protection_domain,
398 TRAPS) {
399 if(!has_checkPackageAccess()) return;
401 // Now we have to call back to java to check if the initating class has access
402 JavaValue result(T_VOID);
403 if (TraceProtectionDomainVerification) {
404 // Print out trace information
405 tty->print_cr("Checking package access");
406 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
407 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
408 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
409 }
411 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
412 JavaCalls::call_special(&result,
413 class_loader,
414 system_loader,
415 vmSymbols::checkPackageAccess_name(),
416 vmSymbols::class_protectiondomain_signature(),
417 Handle(THREAD, klass->java_mirror()),
418 protection_domain,
419 THREAD);
421 if (TraceProtectionDomainVerification) {
422 if (HAS_PENDING_EXCEPTION) {
423 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
424 } else {
425 tty->print_cr(" -> granted");
426 }
427 tty->cr();
428 }
430 if (HAS_PENDING_EXCEPTION) return;
432 // If no exception has been thrown, we have validated the protection domain
433 // Insert the protection domain of the initiating class into the set.
434 {
435 // We recalculate the entry here -- we've called out to java since
436 // the last time it was calculated.
437 ClassLoaderData* loader_data = class_loader_data(class_loader);
439 Symbol* kn = klass->name();
440 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
441 int d_index = dictionary()->hash_to_index(d_hash);
443 MutexLocker mu(SystemDictionary_lock, THREAD);
444 {
445 // Note that we have an entry, and entries can be deleted only during GC,
446 // so we cannot allow GC to occur while we're holding this entry.
448 // We're using a No_Safepoint_Verifier to catch any place where we
449 // might potentially do a GC at all.
450 // Dictionary::do_unloading() asserts that classes in SD are only
451 // unloaded at a safepoint. Anonymous classes are not in SD.
452 No_Safepoint_Verifier nosafepoint;
453 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
454 protection_domain, THREAD);
455 }
456 }
457 }
459 // We only get here if this thread finds that another thread
460 // has already claimed the placeholder token for the current operation,
461 // but that other thread either never owned or gave up the
462 // object lock
463 // Waits on SystemDictionary_lock to indicate placeholder table updated
464 // On return, caller must recheck placeholder table state
465 //
466 // We only get here if
467 // 1) custom classLoader, i.e. not bootstrap classloader
468 // 2) UnsyncloadClass not set
469 // 3) custom classLoader has broken the class loader objectLock
470 // so another thread got here in parallel
471 //
472 // lockObject must be held.
473 // Complicated dance due to lock ordering:
474 // Must first release the classloader object lock to
475 // allow initial definer to complete the class definition
476 // and to avoid deadlock
477 // Reclaim classloader lock object with same original recursion count
478 // Must release SystemDictionary_lock after notify, since
479 // class loader lock must be claimed before SystemDictionary_lock
480 // to prevent deadlocks
481 //
482 // The notify allows applications that did an untimed wait() on
483 // the classloader object lock to not hang.
484 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
485 assert_lock_strong(SystemDictionary_lock);
487 bool calledholdinglock
488 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
489 assert(calledholdinglock,"must hold lock for notify");
490 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
491 ObjectSynchronizer::notifyall(lockObject, THREAD);
492 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
493 SystemDictionary_lock->wait();
494 SystemDictionary_lock->unlock();
495 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
496 SystemDictionary_lock->lock();
497 }
499 // If the class in is in the placeholder table, class loading is in progress
500 // For cases where the application changes threads to load classes, it
501 // is critical to ClassCircularity detection that we try loading
502 // the superclass on the same thread internally, so we do parallel
503 // super class loading here.
504 // This also is critical in cases where the original thread gets stalled
505 // even in non-circularity situations.
506 // Note: must call resolve_super_or_fail even if null super -
507 // to force placeholder entry creation for this class for circularity detection
508 // Caller must check for pending exception
509 // Returns non-null Klass* if other thread has completed load
510 // and we are done,
511 // If return null Klass* and no pending exception, the caller must load the class
512 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
513 Symbol* name, Symbol* superclassname, Handle class_loader,
514 Handle protection_domain, Handle lockObject, TRAPS) {
516 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
517 ClassLoaderData* loader_data = class_loader_data(class_loader);
518 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
519 int d_index = dictionary()->hash_to_index(d_hash);
520 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
521 int p_index = placeholders()->hash_to_index(p_hash);
523 // superk is not used, resolve_super called for circularity check only
524 // This code is reached in two situations. One if this thread
525 // is loading the same class twice (e.g. ClassCircularity, or
526 // java.lang.instrument).
527 // The second is if another thread started the resolve_super first
528 // and has not yet finished.
529 // In both cases the original caller will clean up the placeholder
530 // entry on error.
531 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
532 superclassname,
533 class_loader,
534 protection_domain,
535 true,
536 CHECK_(nh));
538 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
539 // Serial class loaders and bootstrap classloader do wait for superclass loads
540 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
541 MutexLocker mu(SystemDictionary_lock, THREAD);
542 // Check if classloading completed while we were loading superclass or waiting
543 Klass* check = find_class(d_index, d_hash, name, loader_data);
544 if (check != NULL) {
545 // Klass is already loaded, so just return it
546 return(instanceKlassHandle(THREAD, check));
547 } else {
548 return nh;
549 }
550 }
552 // must loop to both handle other placeholder updates
553 // and spurious notifications
554 bool super_load_in_progress = true;
555 PlaceholderEntry* placeholder;
556 while (super_load_in_progress) {
557 MutexLocker mu(SystemDictionary_lock, THREAD);
558 // Check if classloading completed while we were loading superclass or waiting
559 Klass* check = find_class(d_index, d_hash, name, loader_data);
560 if (check != NULL) {
561 // Klass is already loaded, so just return it
562 return(instanceKlassHandle(THREAD, check));
563 } else {
564 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
565 if (placeholder && placeholder->super_load_in_progress() ){
566 // Before UnsyncloadClass:
567 // We only get here if the application has released the
568 // classloader lock when another thread was in the middle of loading a
569 // superclass/superinterface for this class, and now
570 // this thread is also trying to load this class.
571 // To minimize surprises, the first thread that started to
572 // load a class should be the one to complete the loading
573 // with the classfile it initially expected.
574 // This logic has the current thread wait once it has done
575 // all the superclass/superinterface loading it can, until
576 // the original thread completes the class loading or fails
577 // If it completes we will use the resulting InstanceKlass
578 // which we will find below in the systemDictionary.
579 // We also get here for parallel bootstrap classloader
580 if (class_loader.is_null()) {
581 SystemDictionary_lock->wait();
582 } else {
583 double_lock_wait(lockObject, THREAD);
584 }
585 } else {
586 // If not in SD and not in PH, other thread's load must have failed
587 super_load_in_progress = false;
588 }
589 }
590 }
591 return (nh);
592 }
595 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
596 Handle class_loader,
597 Handle protection_domain,
598 TRAPS) {
599 assert(name != NULL && !FieldType::is_array(name) &&
600 !FieldType::is_obj(name), "invalid class name");
602 Ticks class_load_start_time = Ticks::now();
604 // UseNewReflection
605 // Fix for 4474172; see evaluation for more details
606 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
607 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
609 // Do lookup to see if class already exist and the protection domain
610 // has the right access
611 // This call uses find which checks protection domain already matches
612 // All subsequent calls use find_class, and set has_loaded_class so that
613 // before we return a result we call out to java to check for valid protection domain
614 // to allow returning the Klass* and add it to the pd_set if it is valid
615 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
616 int d_index = dictionary()->hash_to_index(d_hash);
617 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
618 protection_domain, THREAD);
619 if (probe != NULL) return probe;
622 // Non-bootstrap class loaders will call out to class loader and
623 // define via jvm/jni_DefineClass which will acquire the
624 // class loader object lock to protect against multiple threads
625 // defining the class in parallel by accident.
626 // This lock must be acquired here so the waiter will find
627 // any successful result in the SystemDictionary and not attempt
628 // the define
629 // ParallelCapable Classloaders and the bootstrap classloader,
630 // or all classloaders with UnsyncloadClass do not acquire lock here
631 bool DoObjectLock = true;
632 if (is_parallelCapable(class_loader)) {
633 DoObjectLock = false;
634 }
636 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
637 int p_index = placeholders()->hash_to_index(p_hash);
639 // Class is not in SystemDictionary so we have to do loading.
640 // Make sure we are synchronized on the class loader before we proceed
641 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
642 check_loader_lock_contention(lockObject, THREAD);
643 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
645 // Check again (after locking) if class already exist in SystemDictionary
646 bool class_has_been_loaded = false;
647 bool super_load_in_progress = false;
648 bool havesupername = false;
649 instanceKlassHandle k;
650 PlaceholderEntry* placeholder;
651 Symbol* superclassname = NULL;
653 {
654 MutexLocker mu(SystemDictionary_lock, THREAD);
655 Klass* check = find_class(d_index, d_hash, name, loader_data);
656 if (check != NULL) {
657 // Klass is already loaded, so just return it
658 class_has_been_loaded = true;
659 k = instanceKlassHandle(THREAD, check);
660 } else {
661 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
662 if (placeholder && placeholder->super_load_in_progress()) {
663 super_load_in_progress = true;
664 if (placeholder->havesupername() == true) {
665 superclassname = placeholder->supername();
666 havesupername = true;
667 }
668 }
669 }
670 }
672 // If the class is in the placeholder table, class loading is in progress
673 if (super_load_in_progress && havesupername==true) {
674 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
675 class_loader, protection_domain, lockObject, THREAD);
676 if (HAS_PENDING_EXCEPTION) {
677 return NULL;
678 }
679 if (!k.is_null()) {
680 class_has_been_loaded = true;
681 }
682 }
684 bool throw_circularity_error = false;
685 if (!class_has_been_loaded) {
686 bool load_instance_added = false;
688 // add placeholder entry to record loading instance class
689 // Five cases:
690 // All cases need to prevent modifying bootclasssearchpath
691 // in parallel with a classload of same classname
692 // Redefineclasses uses existence of the placeholder for the duration
693 // of the class load to prevent concurrent redefinition of not completely
694 // defined classes.
695 // case 1. traditional classloaders that rely on the classloader object lock
696 // - no other need for LOAD_INSTANCE
697 // case 2. traditional classloaders that break the classloader object lock
698 // as a deadlock workaround. Detection of this case requires that
699 // this check is done while holding the classloader object lock,
700 // and that lock is still held when calling classloader's loadClass.
701 // For these classloaders, we ensure that the first requestor
702 // completes the load and other requestors wait for completion.
703 // case 3. UnsyncloadClass - don't use objectLocker
704 // With this flag, we allow parallel classloading of a
705 // class/classloader pair
706 // case4. Bootstrap classloader - don't own objectLocker
707 // This classloader supports parallelism at the classloader level,
708 // but only allows a single load of a class/classloader pair.
709 // No performance benefit and no deadlock issues.
710 // case 5. parallelCapable user level classloaders - without objectLocker
711 // Allow parallel classloading of a class/classloader pair
713 {
714 MutexLocker mu(SystemDictionary_lock, THREAD);
715 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
716 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
717 if (oldprobe) {
718 // only need check_seen_thread once, not on each loop
719 // 6341374 java/lang/Instrument with -Xcomp
720 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
721 throw_circularity_error = true;
722 } else {
723 // case 1: traditional: should never see load_in_progress.
724 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
726 // case 4: bootstrap classloader: prevent futile classloading,
727 // wait on first requestor
728 if (class_loader.is_null()) {
729 SystemDictionary_lock->wait();
730 } else {
731 // case 2: traditional with broken classloader lock. wait on first
732 // requestor.
733 double_lock_wait(lockObject, THREAD);
734 }
735 // Check if classloading completed while we were waiting
736 Klass* check = find_class(d_index, d_hash, name, loader_data);
737 if (check != NULL) {
738 // Klass is already loaded, so just return it
739 k = instanceKlassHandle(THREAD, check);
740 class_has_been_loaded = true;
741 }
742 // check if other thread failed to load and cleaned up
743 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
744 }
745 }
746 }
747 }
748 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
749 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
750 // LOAD_INSTANCE in parallel
752 if (!throw_circularity_error && !class_has_been_loaded) {
753 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
754 load_instance_added = true;
755 // For class loaders that do not acquire the classloader object lock,
756 // if they did not catch another thread holding LOAD_INSTANCE,
757 // need a check analogous to the acquire ObjectLocker/find_class
758 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
759 // one final check if the load has already completed
760 // class loaders holding the ObjectLock shouldn't find the class here
761 Klass* check = find_class(d_index, d_hash, name, loader_data);
762 if (check != NULL) {
763 // Klass is already loaded, so return it after checking/adding protection domain
764 k = instanceKlassHandle(THREAD, check);
765 class_has_been_loaded = true;
766 }
767 }
768 }
770 // must throw error outside of owning lock
771 if (throw_circularity_error) {
772 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
773 ResourceMark rm(THREAD);
774 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
775 }
777 if (!class_has_been_loaded) {
779 // Do actual loading
780 k = load_instance_class(name, class_loader, THREAD);
782 // For UnsyncloadClass only
783 // If they got a linkageError, check if a parallel class load succeeded.
784 // If it did, then for bytecode resolution the specification requires
785 // that we return the same result we did for the other thread, i.e. the
786 // successfully loaded InstanceKlass
787 // Should not get here for classloaders that support parallelism
788 // with the new cleaner mechanism, even with AllowParallelDefineClass
789 // Bootstrap goes through here to allow for an extra guarantee check
790 if (UnsyncloadClass || (class_loader.is_null())) {
791 if (k.is_null() && HAS_PENDING_EXCEPTION
792 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
793 MutexLocker mu(SystemDictionary_lock, THREAD);
794 Klass* check = find_class(d_index, d_hash, name, loader_data);
795 if (check != NULL) {
796 // Klass is already loaded, so just use it
797 k = instanceKlassHandle(THREAD, check);
798 CLEAR_PENDING_EXCEPTION;
799 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
800 }
801 }
802 }
804 // If everything was OK (no exceptions, no null return value), and
805 // class_loader is NOT the defining loader, do a little more bookkeeping.
806 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
807 k->class_loader() != class_loader()) {
809 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
811 // Need to check for a PENDING_EXCEPTION again; check_constraints
812 // can throw and doesn't use the CHECK macro.
813 if (!HAS_PENDING_EXCEPTION) {
814 { // Grabbing the Compile_lock prevents systemDictionary updates
815 // during compilations.
816 MutexLocker mu(Compile_lock, THREAD);
817 update_dictionary(d_index, d_hash, p_index, p_hash,
818 k, class_loader, THREAD);
819 }
821 if (JvmtiExport::should_post_class_load()) {
822 Thread *thread = THREAD;
823 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
824 JvmtiExport::post_class_load((JavaThread *) thread, k());
825 }
826 }
827 }
828 } // load_instance_class loop
830 if (load_instance_added == true) {
831 // clean up placeholder entries for LOAD_INSTANCE success or error
832 // This brackets the SystemDictionary updates for both defining
833 // and initiating loaders
834 MutexLocker mu(SystemDictionary_lock, THREAD);
835 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
836 SystemDictionary_lock->notify_all();
837 }
838 }
840 if (HAS_PENDING_EXCEPTION || k.is_null()) {
841 return NULL;
842 }
844 post_class_load_event(class_load_start_time, k, class_loader);
846 #ifdef ASSERT
847 {
848 ClassLoaderData* loader_data = k->class_loader_data();
849 MutexLocker mu(SystemDictionary_lock, THREAD);
850 Klass* kk = find_class(name, loader_data);
851 assert(kk == k(), "should be present in dictionary");
852 }
853 #endif
855 // return if the protection domain in NULL
856 if (protection_domain() == NULL) return k();
858 // Check the protection domain has the right access
859 {
860 MutexLocker mu(SystemDictionary_lock, THREAD);
861 // Note that we have an entry, and entries can be deleted only during GC,
862 // so we cannot allow GC to occur while we're holding this entry.
863 // We're using a No_Safepoint_Verifier to catch any place where we
864 // might potentially do a GC at all.
865 // Dictionary::do_unloading() asserts that classes in SD are only
866 // unloaded at a safepoint. Anonymous classes are not in SD.
867 No_Safepoint_Verifier nosafepoint;
868 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
869 loader_data,
870 protection_domain)) {
871 return k();
872 }
873 }
875 // Verify protection domain. If it fails an exception is thrown
876 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
878 return k();
879 }
882 // This routine does not lock the system dictionary.
883 //
884 // Since readers don't hold a lock, we must make sure that system
885 // dictionary entries are only removed at a safepoint (when only one
886 // thread is running), and are added to in a safe way (all links must
887 // be updated in an MT-safe manner).
888 //
889 // Callers should be aware that an entry could be added just after
890 // _dictionary->bucket(index) is read here, so the caller will not see
891 // the new entry.
893 Klass* SystemDictionary::find(Symbol* class_name,
894 Handle class_loader,
895 Handle protection_domain,
896 TRAPS) {
898 // UseNewReflection
899 // The result of this call should be consistent with the result
900 // of the call to resolve_instance_class_or_null().
901 // See evaluation 6790209 and 4474172 for more details.
902 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
903 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
905 if (loader_data == NULL) {
906 // If the ClassLoaderData has not been setup,
907 // then the class loader has no entries in the dictionary.
908 return NULL;
909 }
911 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
912 int d_index = dictionary()->hash_to_index(d_hash);
914 {
915 // Note that we have an entry, and entries can be deleted only during GC,
916 // so we cannot allow GC to occur while we're holding this entry.
917 // We're using a No_Safepoint_Verifier to catch any place where we
918 // might potentially do a GC at all.
919 // Dictionary::do_unloading() asserts that classes in SD are only
920 // unloaded at a safepoint. Anonymous classes are not in SD.
921 No_Safepoint_Verifier nosafepoint;
922 return dictionary()->find(d_index, d_hash, class_name, loader_data,
923 protection_domain, THREAD);
924 }
925 }
928 // Look for a loaded instance or array klass by name. Do not do any loading.
929 // return NULL in case of error.
930 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
931 Handle class_loader,
932 Handle protection_domain,
933 TRAPS) {
934 Klass* k = NULL;
935 assert(class_name != NULL, "class name must be non NULL");
937 if (FieldType::is_array(class_name)) {
938 // The name refers to an array. Parse the name.
939 // dimension and object_key in FieldArrayInfo are assigned as a
940 // side-effect of this call
941 FieldArrayInfo fd;
942 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
943 if (t != T_OBJECT) {
944 k = Universe::typeArrayKlassObj(t);
945 } else {
946 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
947 }
948 if (k != NULL) {
949 k = k->array_klass_or_null(fd.dimension());
950 }
951 } else {
952 k = find(class_name, class_loader, protection_domain, THREAD);
953 }
954 return k;
955 }
957 // Note: this method is much like resolve_from_stream, but
958 // updates no supplemental data structures.
959 // TODO consolidate the two methods with a helper routine?
960 Klass* SystemDictionary::parse_stream(Symbol* class_name,
961 Handle class_loader,
962 Handle protection_domain,
963 ClassFileStream* st,
964 KlassHandle host_klass,
965 GrowableArray<Handle>* cp_patches,
966 TRAPS) {
967 TempNewSymbol parsed_name = NULL;
969 Ticks class_load_start_time = Ticks::now();
971 ClassLoaderData* loader_data;
972 if (host_klass.not_null()) {
973 // Create a new CLD for anonymous class, that uses the same class loader
974 // as the host_klass
975 assert(EnableInvokeDynamic, "");
976 guarantee(host_klass->class_loader() == class_loader(), "should be the same");
977 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
978 loader_data->record_dependency(host_klass(), CHECK_NULL);
979 } else {
980 loader_data = ClassLoaderData::class_loader_data(class_loader());
981 }
983 // Parse the stream. Note that we do this even though this klass might
984 // already be present in the SystemDictionary, otherwise we would not
985 // throw potential ClassFormatErrors.
986 //
987 // Note: "name" is updated.
989 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
990 loader_data,
991 protection_domain,
992 host_klass,
993 cp_patches,
994 parsed_name,
995 true,
996 THREAD);
999 if (host_klass.not_null() && k.not_null()) {
1000 assert(EnableInvokeDynamic, "");
1001 // If it's anonymous, initialize it now, since nobody else will.
1003 {
1004 MutexLocker mu_r(Compile_lock, THREAD);
1006 // Add to class hierarchy, initialize vtables, and do possible
1007 // deoptimizations.
1008 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1010 // But, do not add to system dictionary.
1012 // compiled code dependencies need to be validated anyway
1013 notice_modification();
1014 }
1016 // Rewrite and patch constant pool here.
1017 k->link_class(CHECK_NULL);
1018 if (cp_patches != NULL) {
1019 k->constants()->patch_resolved_references(cp_patches);
1020 }
1021 k->eager_initialize(CHECK_NULL);
1023 // notify jvmti
1024 if (JvmtiExport::should_post_class_load()) {
1025 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1026 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1027 }
1029 post_class_load_event(class_load_start_time, k, class_loader);
1030 }
1031 assert(host_klass.not_null() || cp_patches == NULL,
1032 "cp_patches only found with host_klass");
1034 return k();
1035 }
1037 // Add a klass to the system from a stream (called by jni_DefineClass and
1038 // JVM_DefineClass).
1039 // Note: class_name can be NULL. In that case we do not know the name of
1040 // the class until we have parsed the stream.
1042 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1043 Handle class_loader,
1044 Handle protection_domain,
1045 ClassFileStream* st,
1046 bool verify,
1047 TRAPS) {
1049 // Classloaders that support parallelism, e.g. bootstrap classloader,
1050 // or all classloaders with UnsyncloadClass do not acquire lock here
1051 bool DoObjectLock = true;
1052 if (is_parallelCapable(class_loader)) {
1053 DoObjectLock = false;
1054 }
1056 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1058 // Make sure we are synchronized on the class loader before we proceed
1059 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1060 check_loader_lock_contention(lockObject, THREAD);
1061 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1063 TempNewSymbol parsed_name = NULL;
1065 // Parse the stream. Note that we do this even though this klass might
1066 // already be present in the SystemDictionary, otherwise we would not
1067 // throw potential ClassFormatErrors.
1068 //
1069 // Note: "name" is updated.
1071 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1072 loader_data,
1073 protection_domain,
1074 parsed_name,
1075 verify,
1076 THREAD);
1078 const char* pkg = "java/";
1079 if (!HAS_PENDING_EXCEPTION &&
1080 !class_loader.is_null() &&
1081 parsed_name != NULL &&
1082 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1083 // It is illegal to define classes in the "java." package from
1084 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1085 ResourceMark rm(THREAD);
1086 char* name = parsed_name->as_C_string();
1087 char* index = strrchr(name, '/');
1088 *index = '\0'; // chop to just the package name
1089 while ((index = strchr(name, '/')) != NULL) {
1090 *index = '.'; // replace '/' with '.' in package name
1091 }
1092 const char* fmt = "Prohibited package name: %s";
1093 size_t len = strlen(fmt) + strlen(name);
1094 char* message = NEW_RESOURCE_ARRAY(char, len);
1095 jio_snprintf(message, len, fmt, name);
1096 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1097 vmSymbols::java_lang_SecurityException(), message);
1098 }
1100 if (!HAS_PENDING_EXCEPTION) {
1101 assert(parsed_name != NULL, "Sanity");
1102 assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1103 // Verification prevents us from creating names with dots in them, this
1104 // asserts that that's the case.
1105 assert(is_internal_format(parsed_name),
1106 "external class name format used internally");
1108 // Add class just loaded
1109 // If a class loader supports parallel classloading handle parallel define requests
1110 // find_or_define_instance_class may return a different InstanceKlass
1111 if (is_parallelCapable(class_loader)) {
1112 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1113 } else {
1114 define_instance_class(k, THREAD);
1115 }
1116 }
1118 // Make sure we have an entry in the SystemDictionary on success
1119 debug_only( {
1120 if (!HAS_PENDING_EXCEPTION) {
1121 assert(parsed_name != NULL, "parsed_name is still null?");
1122 Symbol* h_name = k->name();
1123 ClassLoaderData *defining_loader_data = k->class_loader_data();
1125 MutexLocker mu(SystemDictionary_lock, THREAD);
1127 Klass* check = find_class(parsed_name, loader_data);
1128 assert(check == k(), "should be present in the dictionary");
1130 Klass* check2 = find_class(h_name, defining_loader_data);
1131 assert(check == check2, "name inconsistancy in SystemDictionary");
1132 }
1133 } );
1135 return k();
1136 }
1139 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1140 int number_of_entries) {
1141 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1142 "bad shared dictionary size.");
1143 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1144 }
1147 // If there is a shared dictionary, then find the entry for the
1148 // given shared system class, if any.
1150 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1151 if (shared_dictionary() != NULL) {
1152 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1153 int d_index = shared_dictionary()->hash_to_index(d_hash);
1155 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1156 } else {
1157 return NULL;
1158 }
1159 }
1162 // Load a class from the shared spaces (found through the shared system
1163 // dictionary). Force the superclass and all interfaces to be loaded.
1164 // Update the class definition to include sibling classes and no
1165 // subclasses (yet). [Classes in the shared space are not part of the
1166 // object hierarchy until loaded.]
1168 instanceKlassHandle SystemDictionary::load_shared_class(
1169 Symbol* class_name, Handle class_loader, TRAPS) {
1170 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1171 return load_shared_class(ik, class_loader, THREAD);
1172 }
1174 instanceKlassHandle SystemDictionary::load_shared_class(
1175 instanceKlassHandle ik, Handle class_loader, TRAPS) {
1176 assert(class_loader.is_null(), "non-null classloader for shared class?");
1177 if (ik.not_null()) {
1178 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1179 Symbol* class_name = ik->name();
1181 // Found the class, now load the superclass and interfaces. If they
1182 // are shared, add them to the main system dictionary and reset
1183 // their hierarchy references (supers, subs, and interfaces).
1185 if (ik->super() != NULL) {
1186 Symbol* cn = ik->super()->name();
1187 resolve_super_or_fail(class_name, cn,
1188 class_loader, Handle(), true, CHECK_(nh));
1189 }
1191 Array<Klass*>* interfaces = ik->local_interfaces();
1192 int num_interfaces = interfaces->length();
1193 for (int index = 0; index < num_interfaces; index++) {
1194 Klass* k = interfaces->at(index);
1196 // Note: can not use InstanceKlass::cast here because
1197 // interfaces' InstanceKlass's C++ vtbls haven't been
1198 // reinitialized yet (they will be once the interface classes
1199 // are loaded)
1200 Symbol* name = k->name();
1201 resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(nh));
1202 }
1204 // Adjust methods to recover missing data. They need addresses for
1205 // interpreter entry points and their default native method address
1206 // must be reset.
1208 // Updating methods must be done under a lock so multiple
1209 // threads don't update these in parallel
1210 // Shared classes are all currently loaded by the bootstrap
1211 // classloader, so this will never cause a deadlock on
1212 // a custom class loader lock.
1214 {
1215 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1216 check_loader_lock_contention(lockObject, THREAD);
1217 ObjectLocker ol(lockObject, THREAD, true);
1218 ik->restore_unshareable_info(CHECK_(nh));
1219 }
1221 if (TraceClassLoading) {
1222 ResourceMark rm;
1223 tty->print("[Loaded %s", ik->external_name());
1224 tty->print(" from shared objects file");
1225 tty->print_cr("]");
1226 }
1227 // notify a class loaded from shared object
1228 ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()),
1229 true /* shared class */);
1230 }
1231 return ik;
1232 }
1235 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1236 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1237 if (class_loader.is_null()) {
1239 // Search the shared system dictionary for classes preloaded into the
1240 // shared spaces.
1241 instanceKlassHandle k;
1242 {
1243 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1244 k = load_shared_class(class_name, class_loader, THREAD);
1245 }
1247 if (k.is_null()) {
1248 // Use VM class loader
1249 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1250 k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1251 }
1253 // find_or_define_instance_class may return a different InstanceKlass
1254 if (!k.is_null()) {
1255 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1256 }
1257 return k;
1258 } else {
1259 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1260 ResourceMark rm(THREAD);
1262 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1263 JavaThread* jt = (JavaThread*) THREAD;
1265 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1266 ClassLoader::perf_app_classload_selftime(),
1267 ClassLoader::perf_app_classload_count(),
1268 jt->get_thread_stat()->perf_recursion_counts_addr(),
1269 jt->get_thread_stat()->perf_timers_addr(),
1270 PerfClassTraceTime::CLASS_LOAD);
1272 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1273 // Translate to external class name format, i.e., convert '/' chars to '.'
1274 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1276 JavaValue result(T_OBJECT);
1278 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1280 // Call public unsynchronized loadClass(String) directly for all class loaders
1281 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1282 // acquire a class-name based lock rather than the class loader object lock.
1283 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1284 // so the call to loadClassInternal() was not required.
1285 //
1286 // UnsyncloadClass flag means both call loadClass(String) and do
1287 // not acquire the class loader lock even for class loaders that are
1288 // not parallelCapable. This was a risky transitional
1289 // flag for diagnostic purposes only. It is risky to call
1290 // custom class loaders without synchronization.
1291 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1292 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1293 // Do NOT assume this will be supported in future releases.
1294 //
1295 // Added MustCallLoadClassInternal in case we discover in the field
1296 // a customer that counts on this call
1297 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1298 JavaCalls::call_special(&result,
1299 class_loader,
1300 spec_klass,
1301 vmSymbols::loadClassInternal_name(),
1302 vmSymbols::string_class_signature(),
1303 string,
1304 CHECK_(nh));
1305 } else {
1306 JavaCalls::call_virtual(&result,
1307 class_loader,
1308 spec_klass,
1309 vmSymbols::loadClass_name(),
1310 vmSymbols::string_class_signature(),
1311 string,
1312 CHECK_(nh));
1313 }
1315 assert(result.get_type() == T_OBJECT, "just checking");
1316 oop obj = (oop) result.get_jobject();
1318 // Primitive classes return null since forName() can not be
1319 // used to obtain any of the Class objects representing primitives or void
1320 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1321 instanceKlassHandle k =
1322 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1323 // For user defined Java class loaders, check that the name returned is
1324 // the same as that requested. This check is done for the bootstrap
1325 // loader when parsing the class file.
1326 if (class_name == k->name()) {
1327 return k;
1328 }
1329 }
1330 // Class is not found or has the wrong name, return NULL
1331 return nh;
1332 }
1333 }
1335 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1337 ClassLoaderData* loader_data = k->class_loader_data();
1338 Handle class_loader_h(THREAD, loader_data->class_loader());
1340 for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){}
1342 // for bootstrap and other parallel classloaders don't acquire lock,
1343 // use placeholder token
1344 // If a parallelCapable class loader calls define_instance_class instead of
1345 // find_or_define_instance_class to get here, we have a timing
1346 // hole with systemDictionary updates and check_constraints
1347 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1348 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1349 compute_loader_lock_object(class_loader_h, THREAD)),
1350 "define called without lock");
1351 }
1353 // Check class-loading constraints. Throw exception if violation is detected.
1354 // Grabs and releases SystemDictionary_lock
1355 // The check_constraints/find_class call and update_dictionary sequence
1356 // must be "atomic" for a specific class/classloader pair so we never
1357 // define two different instanceKlasses for that class/classloader pair.
1358 // Existing classloaders will call define_instance_class with the
1359 // classloader lock held
1360 // Parallel classloaders will call find_or_define_instance_class
1361 // which will require a token to perform the define class
1362 Symbol* name_h = k->name();
1363 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1364 int d_index = dictionary()->hash_to_index(d_hash);
1365 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1367 // Register class just loaded with class loader (placed in Vector)
1368 // Note we do this before updating the dictionary, as this can
1369 // fail with an OutOfMemoryError (if it does, we will *not* put this
1370 // class in the dictionary and will not update the class hierarchy).
1371 // JVMTI FollowReferences needs to find the classes this way.
1372 if (k->class_loader() != NULL) {
1373 methodHandle m(THREAD, Universe::loader_addClass_method());
1374 JavaValue result(T_VOID);
1375 JavaCallArguments args(class_loader_h);
1376 args.push_oop(Handle(THREAD, k->java_mirror()));
1377 JavaCalls::call(&result, m, &args, CHECK);
1378 }
1380 // Add the new class. We need recompile lock during update of CHA.
1381 {
1382 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1383 int p_index = placeholders()->hash_to_index(p_hash);
1385 MutexLocker mu_r(Compile_lock, THREAD);
1387 // Add to class hierarchy, initialize vtables, and do possible
1388 // deoptimizations.
1389 add_to_hierarchy(k, CHECK); // No exception, but can block
1391 // Add to systemDictionary - so other classes can see it.
1392 // Grabs and releases SystemDictionary_lock
1393 update_dictionary(d_index, d_hash, p_index, p_hash,
1394 k, class_loader_h, THREAD);
1395 }
1396 k->eager_initialize(THREAD);
1398 // notify jvmti
1399 if (JvmtiExport::should_post_class_load()) {
1400 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1401 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1403 }
1405 }
1407 // Support parallel classloading
1408 // All parallel class loaders, including bootstrap classloader
1409 // lock a placeholder entry for this class/class_loader pair
1410 // to allow parallel defines of different classes for this class loader
1411 // With AllowParallelDefine flag==true, in case they do not synchronize around
1412 // FindLoadedClass/DefineClass, calls, we check for parallel
1413 // loading for them, wait if a defineClass is in progress
1414 // and return the initial requestor's results
1415 // This flag does not apply to the bootstrap classloader.
1416 // With AllowParallelDefine flag==false, call through to define_instance_class
1417 // which will throw LinkageError: duplicate class definition.
1418 // False is the requested default.
1419 // For better performance, the class loaders should synchronize
1420 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1421 // potentially waste time reading and parsing the bytestream.
1422 // Note: VM callers should ensure consistency of k/class_name,class_loader
1423 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1425 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1426 Symbol* name_h = k->name(); // passed in class_name may be null
1427 ClassLoaderData* loader_data = class_loader_data(class_loader);
1429 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1430 int d_index = dictionary()->hash_to_index(d_hash);
1432 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1433 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1434 int p_index = placeholders()->hash_to_index(p_hash);
1435 PlaceholderEntry* probe;
1437 {
1438 MutexLocker mu(SystemDictionary_lock, THREAD);
1439 // First check if class already defined
1440 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1441 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1442 if (check != NULL) {
1443 return(instanceKlassHandle(THREAD, check));
1444 }
1445 }
1447 // Acquire define token for this class/classloader
1448 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1449 // Wait if another thread defining in parallel
1450 // All threads wait - even those that will throw duplicate class: otherwise
1451 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1452 // if other thread has not finished updating dictionary
1453 while (probe->definer() != NULL) {
1454 SystemDictionary_lock->wait();
1455 }
1456 // Only special cases allow parallel defines and can use other thread's results
1457 // Other cases fall through, and may run into duplicate defines
1458 // caught by finding an entry in the SystemDictionary
1459 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1460 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1461 SystemDictionary_lock->notify_all();
1462 #ifdef ASSERT
1463 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1464 assert(check != NULL, "definer missed recording success");
1465 #endif
1466 return(instanceKlassHandle(THREAD, probe->instance_klass()));
1467 } else {
1468 // This thread will define the class (even if earlier thread tried and had an error)
1469 probe->set_definer(THREAD);
1470 }
1471 }
1473 define_instance_class(k, THREAD);
1475 Handle linkage_exception = Handle(); // null handle
1477 // definer must notify any waiting threads
1478 {
1479 MutexLocker mu(SystemDictionary_lock, THREAD);
1480 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1481 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1482 if (probe != NULL) {
1483 if (HAS_PENDING_EXCEPTION) {
1484 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1485 CLEAR_PENDING_EXCEPTION;
1486 } else {
1487 probe->set_instance_klass(k());
1488 }
1489 probe->set_definer(NULL);
1490 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1491 SystemDictionary_lock->notify_all();
1492 }
1493 }
1495 // Can't throw exception while holding lock due to rank ordering
1496 if (linkage_exception() != NULL) {
1497 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1498 }
1500 return k;
1501 }
1502 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1503 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1504 if (class_loader.is_null()) {
1505 return Handle(THREAD, _system_loader_lock_obj);
1506 } else {
1507 return class_loader;
1508 }
1509 }
1511 // This method is added to check how often we have to wait to grab loader
1512 // lock. The results are being recorded in the performance counters defined in
1513 // ClassLoader::_sync_systemLoaderLockContentionRate and
1514 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1515 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1516 if (!UsePerfData) {
1517 return;
1518 }
1520 assert(!loader_lock.is_null(), "NULL lock object");
1522 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1523 == ObjectSynchronizer::owner_other) {
1524 // contention will likely happen, so increment the corresponding
1525 // contention counter.
1526 if (loader_lock() == _system_loader_lock_obj) {
1527 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1528 } else {
1529 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1530 }
1531 }
1532 }
1534 // ----------------------------------------------------------------------------
1535 // Lookup
1537 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1538 Symbol* class_name,
1539 ClassLoaderData* loader_data) {
1540 assert_locked_or_safepoint(SystemDictionary_lock);
1541 assert (index == dictionary()->index_for(class_name, loader_data),
1542 "incorrect index?");
1544 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1545 return k;
1546 }
1549 // Basic find on classes in the midst of being loaded
1550 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1551 ClassLoaderData* loader_data) {
1552 assert_locked_or_safepoint(SystemDictionary_lock);
1553 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1554 int p_index = placeholders()->hash_to_index(p_hash);
1555 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1556 }
1559 // Used for assertions and verification only
1560 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1561 #ifndef ASSERT
1562 guarantee(VerifyBeforeGC ||
1563 VerifyDuringGC ||
1564 VerifyBeforeExit ||
1565 VerifyDuringStartup ||
1566 VerifyAfterGC, "too expensive");
1567 #endif
1568 assert_locked_or_safepoint(SystemDictionary_lock);
1570 // First look in the loaded class array
1571 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1572 int d_index = dictionary()->hash_to_index(d_hash);
1573 return find_class(d_index, d_hash, class_name, loader_data);
1574 }
1577 // Get the next class in the diictionary.
1578 Klass* SystemDictionary::try_get_next_class() {
1579 return dictionary()->try_get_next_class();
1580 }
1583 // ----------------------------------------------------------------------------
1584 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1585 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1586 // before a new class is used.
1588 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1589 assert(k.not_null(), "just checking");
1590 assert_locked_or_safepoint(Compile_lock);
1592 // Link into hierachy. Make sure the vtables are initialized before linking into
1593 k->append_to_sibling_list(); // add to superklass/sibling list
1594 k->process_interfaces(THREAD); // handle all "implements" declarations
1595 k->set_init_state(InstanceKlass::loaded);
1596 // Now flush all code that depended on old class hierarchy.
1597 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1598 // Also, first reinitialize vtable because it may have gotten out of synch
1599 // while the new class wasn't connected to the class hierarchy.
1600 Universe::flush_dependents_on(k);
1601 }
1604 // ----------------------------------------------------------------------------
1605 // GC support
1607 // Following roots during mark-sweep is separated in two phases.
1608 //
1609 // The first phase follows preloaded classes and all other system
1610 // classes, since these will never get unloaded anyway.
1611 //
1612 // The second phase removes (unloads) unreachable classes from the
1613 // system dictionary and follows the remaining classes' contents.
1615 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1616 roots_oops_do(blk, NULL);
1617 }
1619 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1620 // Follow all system classes and temporary placeholders in dictionary
1621 dictionary()->always_strong_classes_do(closure);
1623 // Placeholders. These represent classes we're actively loading.
1624 placeholders()->classes_do(closure);
1625 }
1627 // Calculate a "good" systemdictionary size based
1628 // on predicted or current loaded classes count
1629 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1630 int newsize = _old_default_sdsize;
1631 if ((classcount > 0) && !DumpSharedSpaces) {
1632 int desiredsize = classcount/_average_depth_goal;
1633 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1634 newsize = _primelist[++_sdgeneration]) {
1635 if (desiredsize <= newsize) {
1636 break;
1637 }
1638 }
1639 }
1640 return newsize;
1641 }
1643 #ifdef ASSERT
1644 class VerifySDReachableAndLiveClosure : public OopClosure {
1645 private:
1646 BoolObjectClosure* _is_alive;
1648 template <class T> void do_oop_work(T* p) {
1649 oop obj = oopDesc::load_decode_heap_oop(p);
1650 guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
1651 }
1653 public:
1654 VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1656 virtual void do_oop(oop* p) { do_oop_work(p); }
1657 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1658 };
1659 #endif
1661 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1662 // Note: anonymous classes are not in the SD.
1663 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
1664 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1665 bool has_dead_loaders = ClassLoaderDataGraph::do_unloading(is_alive);
1666 bool unloading_occurred = false;
1667 if (has_dead_loaders) {
1668 unloading_occurred = dictionary()->do_unloading();
1669 constraints()->purge_loader_constraints();
1670 resolution_errors()->purge_resolution_errors();
1671 }
1672 // Oops referenced by the system dictionary may get unreachable independently
1673 // of the class loader (eg. cached protection domain oops). So we need to
1674 // explicitly unlink them here instead of in Dictionary::do_unloading.
1675 dictionary()->unlink(is_alive);
1676 #ifdef ASSERT
1677 VerifySDReachableAndLiveClosure cl(is_alive);
1678 dictionary()->oops_do(&cl);
1679 #endif
1680 return unloading_occurred;
1681 }
1683 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1684 strong->do_oop(&_java_system_loader);
1685 strong->do_oop(&_system_loader_lock_obj);
1687 // Adjust dictionary
1688 dictionary()->roots_oops_do(strong, weak);
1690 // Visit extra methods
1691 invoke_method_table()->oops_do(strong);
1692 }
1694 void SystemDictionary::oops_do(OopClosure* f) {
1695 f->do_oop(&_java_system_loader);
1696 f->do_oop(&_system_loader_lock_obj);
1698 // Adjust dictionary
1699 dictionary()->oops_do(f);
1701 // Visit extra methods
1702 invoke_method_table()->oops_do(f);
1703 }
1705 // Extended Class redefinition support.
1706 // If one of these classes is replaced, we need to replace it in these places.
1707 // KlassClosure::do_klass should take the address of a class but we can
1708 // change that later.
1709 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1710 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1711 f->do_klass(_well_known_klasses[k]);
1712 }
1714 {
1715 for (int i = 0; i < T_VOID+1; i++) {
1716 if (_box_klasses[i] != NULL) {
1717 assert(i >= T_BOOLEAN, "checking");
1718 f->do_klass(_box_klasses[i]);
1719 }
1720 }
1721 }
1723 FilteredFieldsMap::classes_do(f);
1724 }
1726 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1727 f->do_klass(_abstract_ownable_synchronizer_klass);
1728 }
1730 // Just the classes from defining class loaders
1731 // Don't iterate over placeholders
1732 void SystemDictionary::classes_do(void f(Klass*)) {
1733 dictionary()->classes_do(f);
1734 }
1736 // Added for initialize_itable_for_klass
1737 // Just the classes from defining class loaders
1738 // Don't iterate over placeholders
1739 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1740 dictionary()->classes_do(f, CHECK);
1741 }
1743 // All classes, and their class loaders
1744 // Don't iterate over placeholders
1745 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1746 dictionary()->classes_do(f);
1747 }
1749 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1750 placeholders()->entries_do(f);
1751 }
1753 void SystemDictionary::methods_do(void f(Method*)) {
1754 dictionary()->methods_do(f);
1755 invoke_method_table()->methods_do(f);
1756 }
1758 // ----------------------------------------------------------------------------
1759 // Lazily load klasses
1761 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1762 assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");
1764 // if multiple threads calling this function, only one thread will load
1765 // the class. The other threads will find the loaded version once the
1766 // class is loaded.
1767 Klass* aos = _abstract_ownable_synchronizer_klass;
1768 if (aos == NULL) {
1769 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1770 // Force a fence to prevent any read before the write completes
1771 OrderAccess::fence();
1772 _abstract_ownable_synchronizer_klass = k;
1773 }
1774 }
1776 // ----------------------------------------------------------------------------
1777 // Initialization
1779 void SystemDictionary::initialize(TRAPS) {
1780 // Allocate arrays
1781 assert(dictionary() == NULL,
1782 "SystemDictionary should only be initialized once");
1783 _sdgeneration = 0;
1784 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1785 _placeholders = new PlaceholderTable(_nof_buckets);
1786 _number_of_modifications = 0;
1787 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1788 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1789 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1791 // Allocate private object used as system class loader lock
1792 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1793 // Initialize basic classes
1794 initialize_preloaded_classes(CHECK);
1795 }
1797 // Compact table of directions on the initialization of klasses:
1798 static const short wk_init_info[] = {
1799 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1800 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1801 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1802 | (int)SystemDictionary::option ),
1803 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1804 #undef WK_KLASS_INIT_INFO
1805 0
1806 };
1808 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1809 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1810 int info = wk_init_info[id - FIRST_WKID];
1811 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1812 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1813 Klass** klassp = &_well_known_klasses[id];
1814 bool must_load = (init_opt < SystemDictionary::Opt);
1815 if ((*klassp) == NULL) {
1816 if (must_load) {
1817 (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class
1818 } else {
1819 (*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass
1820 }
1821 }
1822 return ((*klassp) != NULL);
1823 }
1825 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1826 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1827 for (int id = (int)start_id; id < (int)limit_id; id++) {
1828 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1829 int info = wk_init_info[id - FIRST_WKID];
1830 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1831 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1833 initialize_wk_klass((WKID)id, opt, CHECK);
1834 }
1836 // move the starting value forward to the limit:
1837 start_id = limit_id;
1838 }
1840 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1841 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1842 // Preload commonly used klasses
1843 WKID scan = FIRST_WKID;
1844 // first do Object, then String, Class
1845 if (UseSharedSpaces) {
1846 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1847 // Initialize the constant pool for the Object_class
1848 InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1849 ik->constants()->restore_unshareable_info(CHECK);
1850 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1851 } else {
1852 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1853 }
1855 // Calculate offsets for String and Class classes since they are loaded and
1856 // can be used after this point.
1857 java_lang_String::compute_offsets();
1858 java_lang_Class::compute_offsets();
1860 // Fixup mirrors for classes loaded before java.lang.Class.
1861 // These calls iterate over the objects currently in the perm gen
1862 // so calling them at this point is matters (not before when there
1863 // are fewer objects and not later after there are more objects
1864 // in the perm gen.
1865 Universe::initialize_basic_type_mirrors(CHECK);
1866 Universe::fixup_mirrors(CHECK);
1868 // do a bunch more:
1869 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1871 // Preload ref klasses and set reference types
1872 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1873 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1875 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
1876 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1877 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1878 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1879 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1881 // JSR 292 classes
1882 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1883 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1884 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1885 if (EnableInvokeDynamic) {
1886 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1887 } else {
1888 // Skip the JSR 292 classes, if not enabled.
1889 scan = WKID(jsr292_group_end + 1);
1890 }
1892 initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);
1894 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1895 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
1896 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
1897 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
1898 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
1899 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
1900 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
1901 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
1902 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
1903 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
1905 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
1906 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
1907 _has_loadClassInternal = (method != NULL);
1908 }
1909 { // Compute whether we should use checkPackageAccess or NOT
1910 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
1911 _has_checkPackageAccess = (method != NULL);
1912 }
1913 }
1915 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
1916 // If so, returns the basic type it holds. If not, returns T_OBJECT.
1917 BasicType SystemDictionary::box_klass_type(Klass* k) {
1918 assert(k != NULL, "");
1919 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
1920 if (_box_klasses[i] == k)
1921 return (BasicType)i;
1922 }
1923 return T_OBJECT;
1924 }
1926 // Constraints on class loaders. The details of the algorithm can be
1927 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1928 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1929 // that the system dictionary needs to maintain a set of contraints that
1930 // must be satisfied by all classes in the dictionary.
1931 // if defining is true, then LinkageError if already in systemDictionary
1932 // if initiating loader, then ok if InstanceKlass matches existing entry
1934 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
1935 instanceKlassHandle k,
1936 Handle class_loader, bool defining,
1937 TRAPS) {
1938 const char *linkage_error = NULL;
1939 {
1940 Symbol* name = k->name();
1941 ClassLoaderData *loader_data = class_loader_data(class_loader);
1943 MutexLocker mu(SystemDictionary_lock, THREAD);
1945 Klass* check = find_class(d_index, d_hash, name, loader_data);
1946 if (check != (Klass*)NULL) {
1947 // if different InstanceKlass - duplicate class definition,
1948 // else - ok, class loaded by a different thread in parallel,
1949 // we should only have found it if it was done loading and ok to use
1950 // system dictionary only holds instance classes, placeholders
1951 // also holds array classes
1953 assert(check->oop_is_instance(), "noninstance in systemdictionary");
1954 if ((defining == true) || (k() != check)) {
1955 linkage_error = "loader (instance of %s): attempted duplicate class "
1956 "definition for name: \"%s\"";
1957 } else {
1958 return;
1959 }
1960 }
1962 #ifdef ASSERT
1963 Symbol* ph_check = find_placeholder(name, loader_data);
1964 assert(ph_check == NULL || ph_check == name, "invalid symbol");
1965 #endif
1967 if (linkage_error == NULL) {
1968 if (constraints()->check_or_update(k, class_loader, name) == false) {
1969 linkage_error = "loader constraint violation: loader (instance of %s)"
1970 " previously initiated loading for a different type with name \"%s\"";
1971 }
1972 }
1973 }
1975 // Throw error now if needed (cannot throw while holding
1976 // SystemDictionary_lock because of rank ordering)
1978 if (linkage_error) {
1979 ResourceMark rm(THREAD);
1980 const char* class_loader_name = loader_name(class_loader());
1981 char* type_name = k->name()->as_C_string();
1982 size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +
1983 strlen(type_name);
1984 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1985 jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);
1986 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1987 }
1988 }
1991 // Update system dictionary - done after check_constraint and add_to_hierachy
1992 // have been called.
1993 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
1994 int p_index, unsigned int p_hash,
1995 instanceKlassHandle k,
1996 Handle class_loader,
1997 TRAPS) {
1998 // Compile_lock prevents systemDictionary updates during compilations
1999 assert_locked_or_safepoint(Compile_lock);
2000 Symbol* name = k->name();
2001 ClassLoaderData *loader_data = class_loader_data(class_loader);
2003 {
2004 MutexLocker mu1(SystemDictionary_lock, THREAD);
2006 // See whether biased locking is enabled and if so set it for this
2007 // klass.
2008 // Note that this must be done past the last potential blocking
2009 // point / safepoint. We enable biased locking lazily using a
2010 // VM_Operation to iterate the SystemDictionary and installing the
2011 // biasable mark word into each InstanceKlass's prototype header.
2012 // To avoid race conditions where we accidentally miss enabling the
2013 // optimization for one class in the process of being added to the
2014 // dictionary, we must not safepoint after the test of
2015 // BiasedLocking::enabled().
2016 if (UseBiasedLocking && BiasedLocking::enabled()) {
2017 // Set biased locking bit for all loaded classes; it will be
2018 // cleared if revocation occurs too often for this type
2019 // NOTE that we must only do this when the class is initally
2020 // defined, not each time it is referenced from a new class loader
2021 if (k->class_loader() == class_loader()) {
2022 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2023 }
2024 }
2026 // Make a new system dictionary entry.
2027 Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2028 if (sd_check == NULL) {
2029 dictionary()->add_klass(name, loader_data, k);
2030 notice_modification();
2031 }
2032 #ifdef ASSERT
2033 sd_check = find_class(d_index, d_hash, name, loader_data);
2034 assert (sd_check != NULL, "should have entry in system dictionary");
2035 // Note: there may be a placeholder entry: for circularity testing
2036 // or for parallel defines
2037 #endif
2038 SystemDictionary_lock->notify_all();
2039 }
2040 }
2043 // Try to find a class name using the loader constraints. The
2044 // loader constraints might know about a class that isn't fully loaded
2045 // yet and these will be ignored.
2046 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2047 Symbol* class_name, Handle class_loader, TRAPS) {
2049 // First see if it has been loaded directly.
2050 // Force the protection domain to be null. (This removes protection checks.)
2051 Handle no_protection_domain;
2052 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2053 no_protection_domain, CHECK_NULL);
2054 if (klass != NULL)
2055 return klass;
2057 // Now look to see if it has been loaded elsewhere, and is subject to
2058 // a loader constraint that would require this loader to return the
2059 // klass that is already loaded.
2060 if (FieldType::is_array(class_name)) {
2061 // For array classes, their Klass*s are not kept in the
2062 // constraint table. The element Klass*s are.
2063 FieldArrayInfo fd;
2064 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2065 if (t != T_OBJECT) {
2066 klass = Universe::typeArrayKlassObj(t);
2067 } else {
2068 MutexLocker mu(SystemDictionary_lock, THREAD);
2069 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2070 }
2071 // If element class already loaded, allocate array klass
2072 if (klass != NULL) {
2073 klass = klass->array_klass_or_null(fd.dimension());
2074 }
2075 } else {
2076 MutexLocker mu(SystemDictionary_lock, THREAD);
2077 // Non-array classes are easy: simply check the constraint table.
2078 klass = constraints()->find_constrained_klass(class_name, class_loader);
2079 }
2081 return klass;
2082 }
2085 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2086 Handle class_loader1,
2087 Handle class_loader2,
2088 Thread* THREAD) {
2089 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2090 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2092 Symbol* constraint_name = NULL;
2093 if (!FieldType::is_array(class_name)) {
2094 constraint_name = class_name;
2095 } else {
2096 // For array classes, their Klass*s are not kept in the
2097 // constraint table. The element classes are.
2098 FieldArrayInfo fd;
2099 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2100 // primitive types always pass
2101 if (t != T_OBJECT) {
2102 return true;
2103 } else {
2104 constraint_name = fd.object_key();
2105 }
2106 }
2107 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2108 int d_index1 = dictionary()->hash_to_index(d_hash1);
2110 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2111 int d_index2 = dictionary()->hash_to_index(d_hash2);
2112 {
2113 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2115 // Better never do a GC while we're holding these oops
2116 No_Safepoint_Verifier nosafepoint;
2118 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2119 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2120 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2121 klass2, class_loader2);
2122 }
2123 }
2125 // Add entry to resolution error table to record the error when the first
2126 // attempt to resolve a reference to a class has failed.
2127 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) {
2128 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2129 int index = resolution_errors()->hash_to_index(hash);
2130 {
2131 MutexLocker ml(SystemDictionary_lock, Thread::current());
2132 resolution_errors()->add_entry(index, hash, pool, which, error);
2133 }
2134 }
2136 // Delete a resolution error for RedefineClasses for a constant pool is going away
2137 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2138 resolution_errors()->delete_entry(pool);
2139 }
2141 // Lookup resolution error table. Returns error if found, otherwise NULL.
2142 Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {
2143 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2144 int index = resolution_errors()->hash_to_index(hash);
2145 {
2146 MutexLocker ml(SystemDictionary_lock, Thread::current());
2147 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2148 return (entry != NULL) ? entry->error() : (Symbol*)NULL;
2149 }
2150 }
2153 // Signature constraints ensure that callers and callees agree about
2154 // the meaning of type names in their signatures. This routine is the
2155 // intake for constraints. It collects them from several places:
2156 //
2157 // * LinkResolver::resolve_method (if check_access is true) requires
2158 // that the resolving class (the caller) and the defining class of
2159 // the resolved method (the callee) agree on each type in the
2160 // method's signature.
2161 //
2162 // * LinkResolver::resolve_interface_method performs exactly the same
2163 // checks.
2164 //
2165 // * LinkResolver::resolve_field requires that the constant pool
2166 // attempting to link to a field agree with the field's defining
2167 // class about the type of the field signature.
2168 //
2169 // * klassVtable::initialize_vtable requires that, when a class
2170 // overrides a vtable entry allocated by a superclass, that the
2171 // overriding method (i.e., the callee) agree with the superclass
2172 // on each type in the method's signature.
2173 //
2174 // * klassItable::initialize_itable requires that, when a class fills
2175 // in its itables, for each non-abstract method installed in an
2176 // itable, the method (i.e., the callee) agree with the interface
2177 // on each type in the method's signature.
2178 //
2179 // All those methods have a boolean (check_access, checkconstraints)
2180 // which turns off the checks. This is used from specialized contexts
2181 // such as bootstrapping, dumping, and debugging.
2182 //
2183 // No direct constraint is placed between the class and its
2184 // supertypes. Constraints are only placed along linked relations
2185 // between callers and callees. When a method overrides or implements
2186 // an abstract method in a supertype (superclass or interface), the
2187 // constraints are placed as if the supertype were the caller to the
2188 // overriding method. (This works well, since callers to the
2189 // supertype have already established agreement between themselves and
2190 // the supertype.) As a result of all this, a class can disagree with
2191 // its supertype about the meaning of a type name, as long as that
2192 // class neither calls a relevant method of the supertype, nor is
2193 // called (perhaps via an override) from the supertype.
2194 //
2195 //
2196 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2197 //
2198 // Make sure all class components (including arrays) in the given
2199 // signature will be resolved to the same class in both loaders.
2200 // Returns the name of the type that failed a loader constraint check, or
2201 // NULL if no constraint failed. No exception except OOME is thrown.
2202 // Arrays are not added to the loader constraint table, their elements are.
2203 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2204 Handle loader1, Handle loader2,
2205 bool is_method, TRAPS) {
2206 // Nothing to do if loaders are the same.
2207 if (loader1() == loader2()) {
2208 return NULL;
2209 }
2211 SignatureStream sig_strm(signature, is_method);
2212 while (!sig_strm.is_done()) {
2213 if (sig_strm.is_object()) {
2214 Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2215 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2216 return sig;
2217 }
2218 }
2219 sig_strm.next();
2220 }
2221 return NULL;
2222 }
2225 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2226 Symbol* signature,
2227 TRAPS) {
2228 methodHandle empty;
2229 assert(EnableInvokeDynamic, "");
2230 assert(MethodHandles::is_signature_polymorphic(iid) &&
2231 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2232 iid != vmIntrinsics::_invokeGeneric,
2233 err_msg("must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)));
2235 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2236 int index = invoke_method_table()->hash_to_index(hash);
2237 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2238 methodHandle m;
2239 if (spe == NULL || spe->method() == NULL) {
2240 spe = NULL;
2241 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2242 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2243 CompileBroker::compile_method(m, InvocationEntryBci, CompLevel_highest_tier,
2244 methodHandle(), CompileThreshold, "MH", CHECK_(empty));
2246 // Now grab the lock. We might have to throw away the new method,
2247 // if a racing thread has managed to install one at the same time.
2248 {
2249 MutexLocker ml(SystemDictionary_lock, THREAD);
2250 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2251 if (spe == NULL)
2252 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2253 if (spe->method() == NULL)
2254 spe->set_method(m());
2255 }
2256 }
2258 assert(spe != NULL && spe->method() != NULL, "");
2259 return spe->method();
2260 }
2262 // Helper for unpacking the return value from linkMethod and linkCallSite.
2263 static methodHandle unpack_method_and_appendix(Handle mname,
2264 KlassHandle accessing_klass,
2265 objArrayHandle appendix_box,
2266 Handle* appendix_result,
2267 TRAPS) {
2268 methodHandle empty;
2269 if (mname.not_null()) {
2270 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2271 if (vmtarget != NULL && vmtarget->is_method()) {
2272 Method* m = (Method*)vmtarget;
2273 oop appendix = appendix_box->obj_at(0);
2274 if (TraceMethodHandles) {
2275 #ifndef PRODUCT
2276 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2277 m->print();
2278 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2279 tty->cr();
2280 #endif //PRODUCT
2281 }
2282 (*appendix_result) = Handle(THREAD, appendix);
2283 // the target is stored in the cpCache and if a reference to this
2284 // MethodName is dropped we need a way to make sure the
2285 // class_loader containing this method is kept alive.
2286 // FIXME: the appendix might also preserve this dependency.
2287 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2288 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2289 return methodHandle(THREAD, m);
2290 }
2291 }
2292 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2293 return empty;
2294 }
2296 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2297 Symbol* signature,
2298 KlassHandle accessing_klass,
2299 Handle *appendix_result,
2300 Handle *method_type_result,
2301 TRAPS) {
2302 methodHandle empty;
2303 assert(EnableInvokeDynamic, "");
2304 assert(!THREAD->is_Compiler_thread(), "");
2305 Handle method_type =
2306 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2307 if (false) { // FIXME: Decide if the Java upcall should resolve signatures.
2308 method_type = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2309 }
2311 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass();
2312 int ref_kind = JVM_REF_invokeVirtual;
2313 Handle name_str = StringTable::intern(name, CHECK_(empty));
2314 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2315 assert(appendix_box->obj_at(0) == NULL, "");
2317 // This should not happen. JDK code should take care of that.
2318 if (accessing_klass.is_null() || method_type.is_null()) {
2319 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2320 }
2322 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2323 JavaCallArguments args;
2324 args.push_oop(accessing_klass()->java_mirror());
2325 args.push_int(ref_kind);
2326 args.push_oop(mh_klass()->java_mirror());
2327 args.push_oop(name_str());
2328 args.push_oop(method_type());
2329 args.push_oop(appendix_box());
2330 JavaValue result(T_OBJECT);
2331 JavaCalls::call_static(&result,
2332 SystemDictionary::MethodHandleNatives_klass(),
2333 vmSymbols::linkMethod_name(),
2334 vmSymbols::linkMethod_signature(),
2335 &args, CHECK_(empty));
2336 Handle mname(THREAD, (oop) result.get_jobject());
2337 (*method_type_result) = method_type;
2338 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2339 }
2342 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2343 // signature, as interpreted relative to the given class loader.
2344 // Because of class loader constraints, all method handle usage must be
2345 // consistent with this loader.
2346 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2347 KlassHandle accessing_klass,
2348 TRAPS) {
2349 Handle empty;
2350 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2351 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2352 int index = invoke_method_table()->hash_to_index(hash);
2353 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2354 if (spe != NULL && spe->method_type() != NULL) {
2355 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2356 return Handle(THREAD, spe->method_type());
2357 } else if (THREAD->is_Compiler_thread()) {
2358 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2359 return Handle(); // do not attempt from within compiler, unless it was cached
2360 }
2362 Handle class_loader, protection_domain;
2363 bool is_on_bcp = true; // keep this true as long as we can materialize from the boot classloader
2364 int npts = ArgumentCount(signature).size();
2365 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2366 int arg = 0;
2367 Handle rt; // the return type from the signature
2368 ResourceMark rm(THREAD);
2369 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2370 oop mirror = NULL;
2371 if (is_on_bcp) {
2372 // Note: class_loader & protection_domain are both null at this point.
2373 mirror = ss.as_java_mirror(class_loader, protection_domain,
2374 SignatureStream::ReturnNull, CHECK_(empty));
2375 if (mirror == NULL) {
2376 // fall back from BCP to accessing_klass
2377 if (accessing_klass.not_null()) {
2378 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2379 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2380 }
2381 is_on_bcp = false;
2382 }
2383 }
2384 if (!is_on_bcp) {
2385 // Resolve, throwing a real error if it doesn't work.
2386 mirror = ss.as_java_mirror(class_loader, protection_domain,
2387 SignatureStream::NCDFError, CHECK_(empty));
2388 }
2389 if (ss.at_return_type())
2390 rt = Handle(THREAD, mirror);
2391 else
2392 pts->obj_at_put(arg++, mirror);
2394 // Check accessibility.
2395 if (ss.is_object() && accessing_klass.not_null()) {
2396 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2397 mirror = NULL; // safety
2398 // Emulate ConstantPool::verify_constant_pool_resolve.
2399 if (sel_klass->oop_is_objArray())
2400 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2401 if (sel_klass->oop_is_instance()) {
2402 KlassHandle sel_kh(THREAD, sel_klass);
2403 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2404 }
2405 }
2406 }
2407 assert(arg == npts, "");
2409 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2410 JavaCallArguments args(Handle(THREAD, rt()));
2411 args.push_oop(pts());
2412 JavaValue result(T_OBJECT);
2413 JavaCalls::call_static(&result,
2414 SystemDictionary::MethodHandleNatives_klass(),
2415 vmSymbols::findMethodHandleType_name(),
2416 vmSymbols::findMethodHandleType_signature(),
2417 &args, CHECK_(empty));
2418 Handle method_type(THREAD, (oop) result.get_jobject());
2420 if (is_on_bcp) {
2421 // We can cache this MethodType inside the JVM.
2422 MutexLocker ml(SystemDictionary_lock, THREAD);
2423 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2424 if (spe == NULL)
2425 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2426 if (spe->method_type() == NULL) {
2427 spe->set_method_type(method_type());
2428 }
2429 }
2431 // report back to the caller with the MethodType
2432 return method_type;
2433 }
2435 // Ask Java code to find or construct a method handle constant.
2436 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2437 int ref_kind, //e.g., JVM_REF_invokeVirtual
2438 KlassHandle callee,
2439 Symbol* name_sym,
2440 Symbol* signature,
2441 TRAPS) {
2442 Handle empty;
2443 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2444 Handle type;
2445 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2446 type = find_method_handle_type(signature, caller, CHECK_(empty));
2447 } else if (caller.is_null()) {
2448 // This should not happen. JDK code should take care of that.
2449 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2450 } else {
2451 ResourceMark rm(THREAD);
2452 SignatureStream ss(signature, false);
2453 if (!ss.is_done()) {
2454 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2455 SignatureStream::NCDFError, CHECK_(empty));
2456 type = Handle(THREAD, mirror);
2457 ss.next();
2458 if (!ss.is_done()) type = Handle(); // error!
2459 }
2460 }
2461 if (type.is_null()) {
2462 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2463 }
2465 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2466 JavaCallArguments args;
2467 args.push_oop(caller->java_mirror()); // the referring class
2468 args.push_int(ref_kind);
2469 args.push_oop(callee->java_mirror()); // the target class
2470 args.push_oop(name());
2471 args.push_oop(type());
2472 JavaValue result(T_OBJECT);
2473 JavaCalls::call_static(&result,
2474 SystemDictionary::MethodHandleNatives_klass(),
2475 vmSymbols::linkMethodHandleConstant_name(),
2476 vmSymbols::linkMethodHandleConstant_signature(),
2477 &args, CHECK_(empty));
2478 return Handle(THREAD, (oop) result.get_jobject());
2479 }
2481 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2482 // name and signature, as interpreted relative to the given class loader.
2483 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2484 Handle bootstrap_specifier,
2485 Symbol* name,
2486 Symbol* type,
2487 Handle *appendix_result,
2488 Handle *method_type_result,
2489 TRAPS) {
2490 methodHandle empty;
2491 Handle bsm, info;
2492 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2493 bsm = bootstrap_specifier;
2494 } else {
2495 assert(bootstrap_specifier->is_objArray(), "");
2496 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2497 int len = args->length();
2498 assert(len >= 1, "");
2499 bsm = Handle(THREAD, args->obj_at(0));
2500 if (len > 1) {
2501 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2502 for (int i = 1; i < len; i++)
2503 args1->obj_at_put(i-1, args->obj_at(i));
2504 info = Handle(THREAD, args1);
2505 }
2506 }
2507 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2508 "caller must supply a valid BSM");
2510 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2511 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2513 // This should not happen. JDK code should take care of that.
2514 if (caller.is_null() || method_type.is_null()) {
2515 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2516 }
2518 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2519 assert(appendix_box->obj_at(0) == NULL, "");
2521 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2522 JavaCallArguments args;
2523 args.push_oop(caller->java_mirror());
2524 args.push_oop(bsm());
2525 args.push_oop(method_name());
2526 args.push_oop(method_type());
2527 args.push_oop(info());
2528 args.push_oop(appendix_box);
2529 JavaValue result(T_OBJECT);
2530 JavaCalls::call_static(&result,
2531 SystemDictionary::MethodHandleNatives_klass(),
2532 vmSymbols::linkCallSite_name(),
2533 vmSymbols::linkCallSite_signature(),
2534 &args, CHECK_(empty));
2535 Handle mname(THREAD, (oop) result.get_jobject());
2536 (*method_type_result) = method_type;
2537 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2538 }
2540 // Since the identity hash code for symbols changes when the symbols are
2541 // moved from the regular perm gen (hash in the mark word) to the shared
2542 // spaces (hash is the address), the classes loaded into the dictionary
2543 // may be in the wrong buckets.
2545 void SystemDictionary::reorder_dictionary() {
2546 dictionary()->reorder_dictionary();
2547 }
2550 void SystemDictionary::copy_buckets(char** top, char* end) {
2551 dictionary()->copy_buckets(top, end);
2552 }
2555 void SystemDictionary::copy_table(char** top, char* end) {
2556 dictionary()->copy_table(top, end);
2557 }
2560 void SystemDictionary::reverse() {
2561 dictionary()->reverse();
2562 }
2564 int SystemDictionary::number_of_classes() {
2565 return dictionary()->number_of_entries();
2566 }
2569 // ----------------------------------------------------------------------------
2570 #ifndef PRODUCT
2572 void SystemDictionary::print() {
2573 dictionary()->print();
2575 // Placeholders
2576 GCMutexLocker mu(SystemDictionary_lock);
2577 placeholders()->print();
2579 // loader constraints - print under SD_lock
2580 constraints()->print();
2581 }
2583 #endif
2585 void SystemDictionary::verify() {
2586 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2587 guarantee(constraints() != NULL,
2588 "Verify of loader constraints failed");
2589 guarantee(dictionary()->number_of_entries() >= 0 &&
2590 placeholders()->number_of_entries() >= 0,
2591 "Verify of system dictionary failed");
2593 // Verify dictionary
2594 dictionary()->verify();
2596 GCMutexLocker mu(SystemDictionary_lock);
2597 placeholders()->verify();
2599 // Verify constraint table
2600 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2601 constraints()->verify(dictionary(), placeholders());
2602 }
2604 // utility function for class load event
2605 void SystemDictionary::post_class_load_event(const Ticks& start_time,
2606 instanceKlassHandle k,
2607 Handle initiating_loader) {
2608 #if INCLUDE_TRACE
2609 EventClassLoad event(UNTIMED);
2610 if (event.should_commit()) {
2611 event.set_starttime(start_time);
2612 event.set_loadedClass(k());
2613 oop defining_class_loader = k->class_loader();
2614 event.set_definingClassLoader(defining_class_loader != NULL ?
2615 defining_class_loader->klass() : (Klass*)NULL);
2616 oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
2617 event.set_initiatingClassLoader(class_loader != NULL ?
2618 class_loader->klass() : (Klass*)NULL);
2619 event.commit();
2620 }
2621 #endif /* INCLUDE_TRACE */
2622 }
2624 #ifndef PRODUCT
2626 // statistics code
2627 class ClassStatistics: AllStatic {
2628 private:
2629 static int nclasses; // number of classes
2630 static int nmethods; // number of methods
2631 static int nmethoddata; // number of methodData
2632 static int class_size; // size of class objects in words
2633 static int method_size; // size of method objects in words
2634 static int debug_size; // size of debug info in methods
2635 static int methoddata_size; // size of methodData objects in words
2637 static void do_class(Klass* k) {
2638 nclasses++;
2639 class_size += k->size();
2640 if (k->oop_is_instance()) {
2641 InstanceKlass* ik = (InstanceKlass*)k;
2642 class_size += ik->methods()->size();
2643 class_size += ik->constants()->size();
2644 class_size += ik->local_interfaces()->size();
2645 class_size += ik->transitive_interfaces()->size();
2646 // We do not have to count implementors, since we only store one!
2647 // SSS: How should these be accounted now that they have moved?
2648 // class_size += ik->fields()->length();
2649 }
2650 }
2652 static void do_method(Method* m) {
2653 nmethods++;
2654 method_size += m->size();
2655 // class loader uses same objArray for empty vectors, so don't count these
2656 if (m->has_stackmap_table()) {
2657 method_size += m->stackmap_data()->size();
2658 }
2660 MethodData* mdo = m->method_data();
2661 if (mdo != NULL) {
2662 nmethoddata++;
2663 methoddata_size += mdo->size();
2664 }
2665 }
2667 public:
2668 static void print() {
2669 SystemDictionary::classes_do(do_class);
2670 SystemDictionary::methods_do(do_method);
2671 tty->print_cr("Class statistics:");
2672 tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
2673 tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
2674 (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
2675 tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
2676 }
2677 };
2680 int ClassStatistics::nclasses = 0;
2681 int ClassStatistics::nmethods = 0;
2682 int ClassStatistics::nmethoddata = 0;
2683 int ClassStatistics::class_size = 0;
2684 int ClassStatistics::method_size = 0;
2685 int ClassStatistics::debug_size = 0;
2686 int ClassStatistics::methoddata_size = 0;
2688 void SystemDictionary::print_class_statistics() {
2689 ResourceMark rm;
2690 ClassStatistics::print();
2691 }
2694 class MethodStatistics: AllStatic {
2695 public:
2696 enum {
2697 max_parameter_size = 10
2698 };
2699 private:
2701 static int _number_of_methods;
2702 static int _number_of_final_methods;
2703 static int _number_of_static_methods;
2704 static int _number_of_native_methods;
2705 static int _number_of_synchronized_methods;
2706 static int _number_of_profiled_methods;
2707 static int _number_of_bytecodes;
2708 static int _parameter_size_profile[max_parameter_size];
2709 static int _bytecodes_profile[Bytecodes::number_of_java_codes];
2711 static void initialize() {
2712 _number_of_methods = 0;
2713 _number_of_final_methods = 0;
2714 _number_of_static_methods = 0;
2715 _number_of_native_methods = 0;
2716 _number_of_synchronized_methods = 0;
2717 _number_of_profiled_methods = 0;
2718 _number_of_bytecodes = 0;
2719 for (int i = 0; i < max_parameter_size ; i++) _parameter_size_profile[i] = 0;
2720 for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile [j] = 0;
2721 };
2723 static void do_method(Method* m) {
2724 _number_of_methods++;
2725 // collect flag info
2726 if (m->is_final() ) _number_of_final_methods++;
2727 if (m->is_static() ) _number_of_static_methods++;
2728 if (m->is_native() ) _number_of_native_methods++;
2729 if (m->is_synchronized()) _number_of_synchronized_methods++;
2730 if (m->method_data() != NULL) _number_of_profiled_methods++;
2731 // collect parameter size info (add one for receiver, if any)
2732 _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
2733 // collect bytecodes info
2734 {
2735 Thread *thread = Thread::current();
2736 HandleMark hm(thread);
2737 BytecodeStream s(methodHandle(thread, m));
2738 Bytecodes::Code c;
2739 while ((c = s.next()) >= 0) {
2740 _number_of_bytecodes++;
2741 _bytecodes_profile[c]++;
2742 }
2743 }
2744 }
2746 public:
2747 static void print() {
2748 initialize();
2749 SystemDictionary::methods_do(do_method);
2750 // generate output
2751 tty->cr();
2752 tty->print_cr("Method statistics (static):");
2753 // flag distribution
2754 tty->cr();
2755 tty->print_cr("%6d final methods %6.1f%%", _number_of_final_methods , _number_of_final_methods * 100.0F / _number_of_methods);
2756 tty->print_cr("%6d static methods %6.1f%%", _number_of_static_methods , _number_of_static_methods * 100.0F / _number_of_methods);
2757 tty->print_cr("%6d native methods %6.1f%%", _number_of_native_methods , _number_of_native_methods * 100.0F / _number_of_methods);
2758 tty->print_cr("%6d synchronized methods %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
2759 tty->print_cr("%6d profiled methods %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
2760 // parameter size profile
2761 tty->cr();
2762 { int tot = 0;
2763 int avg = 0;
2764 for (int i = 0; i < max_parameter_size; i++) {
2765 int n = _parameter_size_profile[i];
2766 tot += n;
2767 avg += n*i;
2768 tty->print_cr("parameter size = %1d: %6d methods %5.1f%%", i, n, n * 100.0F / _number_of_methods);
2769 }
2770 assert(tot == _number_of_methods, "should be the same");
2771 tty->print_cr(" %6d methods 100.0%%", _number_of_methods);
2772 tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
2773 }
2774 // bytecodes profile
2775 tty->cr();
2776 { int tot = 0;
2777 for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
2778 if (Bytecodes::is_defined(i)) {
2779 Bytecodes::Code c = Bytecodes::cast(i);
2780 int n = _bytecodes_profile[c];
2781 tot += n;
2782 tty->print_cr("%9d %7.3f%% %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
2783 }
2784 }
2785 assert(tot == _number_of_bytecodes, "should be the same");
2786 tty->print_cr("%9d 100.000%%", _number_of_bytecodes);
2787 }
2788 tty->cr();
2789 }
2790 };
2792 int MethodStatistics::_number_of_methods;
2793 int MethodStatistics::_number_of_final_methods;
2794 int MethodStatistics::_number_of_static_methods;
2795 int MethodStatistics::_number_of_native_methods;
2796 int MethodStatistics::_number_of_synchronized_methods;
2797 int MethodStatistics::_number_of_profiled_methods;
2798 int MethodStatistics::_number_of_bytecodes;
2799 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
2800 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
2803 void SystemDictionary::print_method_statistics() {
2804 MethodStatistics::print();
2805 }
2807 #endif // PRODUCT