Wed, 23 Jan 2013 10:34:29 -0500
8006040: NPG: on_stack processing wastes space in ConstantPool
Summary: Added on_stack bit to flags. Also MetadataMarkOnStack is used for more than JVMTI so had to be moved.
Reviewed-by: dholmes, stefank
1 /*
2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
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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).
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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23 */
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderData.inline.hpp"
27 #include "classfile/dictionary.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/loaderConstraints.hpp"
30 #include "classfile/placeholders.hpp"
31 #include "classfile/resolutionErrors.hpp"
32 #include "classfile/systemDictionary.hpp"
33 #include "classfile/vmSymbols.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "interpreter/bytecodeStream.hpp"
36 #include "interpreter/interpreter.hpp"
37 #include "memory/gcLocker.hpp"
38 #include "memory/oopFactory.hpp"
39 #include "oops/instanceKlass.hpp"
40 #include "oops/instanceRefKlass.hpp"
41 #include "oops/klass.inline.hpp"
42 #include "oops/methodData.hpp"
43 #include "oops/objArrayKlass.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "oops/oop.inline2.hpp"
46 #include "oops/typeArrayKlass.hpp"
47 #include "prims/jvmtiEnvBase.hpp"
48 #include "prims/methodHandles.hpp"
49 #include "runtime/biasedLocking.hpp"
50 #include "runtime/fieldType.hpp"
51 #include "runtime/handles.inline.hpp"
52 #include "runtime/java.hpp"
53 #include "runtime/javaCalls.hpp"
54 #include "runtime/mutexLocker.hpp"
55 #include "runtime/signature.hpp"
56 #include "services/classLoadingService.hpp"
57 #include "services/threadService.hpp"
60 Dictionary* SystemDictionary::_dictionary = NULL;
61 PlaceholderTable* SystemDictionary::_placeholders = NULL;
62 Dictionary* SystemDictionary::_shared_dictionary = NULL;
63 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
64 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
65 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
68 int SystemDictionary::_number_of_modifications = 0;
69 int SystemDictionary::_sdgeneration = 0;
70 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
71 20201,40423,99991};
73 oop SystemDictionary::_system_loader_lock_obj = NULL;
75 Klass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
76 = { NULL /*, NULL...*/ };
78 Klass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
80 oop SystemDictionary::_java_system_loader = NULL;
82 bool SystemDictionary::_has_loadClassInternal = false;
83 bool SystemDictionary::_has_checkPackageAccess = false;
85 // lazily initialized klass variables
86 Klass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
89 // ----------------------------------------------------------------------------
90 // Java-level SystemLoader
92 oop SystemDictionary::java_system_loader() {
93 return _java_system_loader;
94 }
96 void SystemDictionary::compute_java_system_loader(TRAPS) {
97 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
98 JavaValue result(T_OBJECT);
99 JavaCalls::call_static(&result,
100 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
101 vmSymbols::getSystemClassLoader_name(),
102 vmSymbols::void_classloader_signature(),
103 CHECK);
105 _java_system_loader = (oop)result.get_jobject();
106 }
109 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
110 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
111 return ClassLoaderDataGraph::find_or_create(class_loader, CHECK_NULL);
112 }
114 // ----------------------------------------------------------------------------
115 // debugging
117 #ifdef ASSERT
119 // return true if class_name contains no '.' (internal format is '/')
120 bool SystemDictionary::is_internal_format(Symbol* class_name) {
121 if (class_name != NULL) {
122 ResourceMark rm;
123 char* name = class_name->as_C_string();
124 return strchr(name, '.') == NULL;
125 } else {
126 return true;
127 }
128 }
130 #endif
132 // ----------------------------------------------------------------------------
133 // Parallel class loading check
135 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
136 if (UnsyncloadClass || class_loader.is_null()) return true;
137 if (AlwaysLockClassLoader) return false;
138 return java_lang_ClassLoader::parallelCapable(class_loader());
139 }
140 // ----------------------------------------------------------------------------
141 // ParallelDefineClass flag does not apply to bootclass loader
142 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
143 if (class_loader.is_null()) return false;
144 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
145 return true;
146 }
147 return false;
148 }
149 // ----------------------------------------------------------------------------
150 // Resolving of classes
152 // Forwards to resolve_or_null
154 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
155 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
156 if (HAS_PENDING_EXCEPTION || klass == NULL) {
157 KlassHandle k_h(THREAD, klass);
158 // can return a null klass
159 klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);
160 }
161 return klass;
162 }
164 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {
165 if (HAS_PENDING_EXCEPTION) {
166 // If we have a pending exception we forward it to the caller, unless throw_error is true,
167 // in which case we have to check whether the pending exception is a ClassNotFoundException,
168 // and if so convert it to a NoClassDefFoundError
169 // And chain the original ClassNotFoundException
170 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
171 ResourceMark rm(THREAD);
172 assert(klass_h() == NULL, "Should not have result with exception pending");
173 Handle e(THREAD, PENDING_EXCEPTION);
174 CLEAR_PENDING_EXCEPTION;
175 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
176 } else {
177 return NULL;
178 }
179 }
180 // Class not found, throw appropriate error or exception depending on value of throw_error
181 if (klass_h() == NULL) {
182 ResourceMark rm(THREAD);
183 if (throw_error) {
184 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
185 } else {
186 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
187 }
188 }
189 return (Klass*)klass_h();
190 }
193 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
194 bool throw_error, TRAPS)
195 {
196 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
197 }
200 // Forwards to resolve_instance_class_or_null
202 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
203 assert(!THREAD->is_Compiler_thread(),
204 err_msg("can not load classes with compiler thread: class=%s, classloader=%s",
205 class_name->as_C_string(),
206 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()));
207 if (FieldType::is_array(class_name)) {
208 return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
209 } else if (FieldType::is_obj(class_name)) {
210 ResourceMark rm(THREAD);
211 // Ignore wrapping L and ;.
212 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
213 class_name->utf8_length() - 2, CHECK_NULL);
214 return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL);
215 } else {
216 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
217 }
218 }
220 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
221 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
222 }
224 // Forwards to resolve_instance_class_or_null
226 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
227 Handle class_loader,
228 Handle protection_domain,
229 TRAPS) {
230 assert(FieldType::is_array(class_name), "must be array");
231 Klass* k = NULL;
232 FieldArrayInfo fd;
233 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
234 // of this call
235 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
236 if (t == T_OBJECT) {
237 // naked oop "k" is OK here -- we assign back into it
238 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
239 class_loader,
240 protection_domain,
241 CHECK_NULL);
242 if (k != NULL) {
243 k = k->array_klass(fd.dimension(), CHECK_NULL);
244 }
245 } else {
246 k = Universe::typeArrayKlassObj(t);
247 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
248 }
249 return k;
250 }
253 // Must be called for any super-class or super-interface resolution
254 // during class definition to allow class circularity checking
255 // super-interface callers:
256 // parse_interfaces - for defineClass & jvmtiRedefineClasses
257 // super-class callers:
258 // ClassFileParser - for defineClass & jvmtiRedefineClasses
259 // load_shared_class - while loading a class from shared archive
260 // resolve_instance_class_or_null:
261 // via: handle_parallel_super_load
262 // when resolving a class that has an existing placeholder with
263 // a saved superclass [i.e. a defineClass is currently in progress]
264 // if another thread is trying to resolve the class, it must do
265 // super-class checks on its own thread to catch class circularity
266 // This last call is critical in class circularity checking for cases
267 // where classloading is delegated to different threads and the
268 // classloader lock is released.
269 // Take the case: Base->Super->Base
270 // 1. If thread T1 tries to do a defineClass of class Base
271 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
272 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
273 // so it tries to load Super
274 // 3. If we load the class internally, or user classloader uses same thread
275 // loadClassFromxxx or defineClass via parseClassFile Super ...
276 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
277 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
278 // 3.4 calls resolve_super_or_fail Base
279 // 3.5 finds T1,Base -> throws class circularity
280 //OR 4. If T2 tries to resolve Super via defineClass Super ...
281 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
282 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
283 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
284 // 4.4 finds T2, Super -> throws class circularity
285 // Must be called, even if superclass is null, since this is
286 // where the placeholder entry is created which claims this
287 // thread is loading this class/classloader.
288 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
289 Symbol* class_name,
290 Handle class_loader,
291 Handle protection_domain,
292 bool is_superclass,
293 TRAPS) {
294 // Double-check, if child class is already loaded, just return super-class,interface
295 // Don't add a placedholder if already loaded, i.e. already in system dictionary
296 // Make sure there's a placeholder for the *child* before resolving.
297 // Used as a claim that this thread is currently loading superclass/classloader
298 // Used here for ClassCircularity checks and also for heap verification
299 // (every InstanceKlass in the heap needs to be in the system dictionary
300 // or have a placeholder).
301 // Must check ClassCircularity before checking if super class is already loaded
302 //
303 // We might not already have a placeholder if this child_name was
304 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
305 // the name of the class might not be known until the stream is actually
306 // parsed.
307 // Bugs 4643874, 4715493
308 // compute_hash can have a safepoint
310 ClassLoaderData* loader_data = class_loader_data(class_loader);
311 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
312 int d_index = dictionary()->hash_to_index(d_hash);
313 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
314 int p_index = placeholders()->hash_to_index(p_hash);
315 // can't throw error holding a lock
316 bool child_already_loaded = false;
317 bool throw_circularity_error = false;
318 {
319 MutexLocker mu(SystemDictionary_lock, THREAD);
320 Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
321 Klass* quicksuperk;
322 // to support // loading: if child done loading, just return superclass
323 // if class_name, & class_loader don't match:
324 // if initial define, SD update will give LinkageError
325 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
326 // so we don't throw an exception here.
327 // see: nsk redefclass014 & java.lang.instrument Instrument032
328 if ((childk != NULL ) && (is_superclass) &&
329 ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) &&
331 ((quicksuperk->name() == class_name) &&
332 (quicksuperk->class_loader() == class_loader()))) {
333 return quicksuperk;
334 } else {
335 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
336 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
337 throw_circularity_error = true;
338 }
339 }
340 if (!throw_circularity_error) {
341 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
342 }
343 }
344 if (throw_circularity_error) {
345 ResourceMark rm(THREAD);
346 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
347 }
349 // java.lang.Object should have been found above
350 assert(class_name != NULL, "null super class for resolving");
351 // Resolve the super class or interface, check results on return
352 Klass* superk = SystemDictionary::resolve_or_null(class_name,
353 class_loader,
354 protection_domain,
355 THREAD);
357 KlassHandle superk_h(THREAD, superk);
359 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
360 // It is no longer necessary to keep the placeholder table alive until update_dictionary
361 // or error. GC used to walk the placeholder table as strong roots.
362 // The instanceKlass is kept alive because the class loader is on the stack,
363 // which keeps the loader_data alive, as well as all instanceKlasses in
364 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
365 {
366 MutexLocker mu(SystemDictionary_lock, THREAD);
367 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
368 SystemDictionary_lock->notify_all();
369 }
370 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
371 // can null superk
372 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));
373 }
375 return superk_h();
376 }
378 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
379 Handle class_loader,
380 Handle protection_domain,
381 TRAPS) {
382 if(!has_checkPackageAccess()) return;
384 // Now we have to call back to java to check if the initating class has access
385 JavaValue result(T_VOID);
386 if (TraceProtectionDomainVerification) {
387 // Print out trace information
388 tty->print_cr("Checking package access");
389 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
390 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
391 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
392 }
394 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
395 JavaCalls::call_special(&result,
396 class_loader,
397 system_loader,
398 vmSymbols::checkPackageAccess_name(),
399 vmSymbols::class_protectiondomain_signature(),
400 Handle(THREAD, klass->java_mirror()),
401 protection_domain,
402 THREAD);
404 if (TraceProtectionDomainVerification) {
405 if (HAS_PENDING_EXCEPTION) {
406 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
407 } else {
408 tty->print_cr(" -> granted");
409 }
410 tty->cr();
411 }
413 if (HAS_PENDING_EXCEPTION) return;
415 // If no exception has been thrown, we have validated the protection domain
416 // Insert the protection domain of the initiating class into the set.
417 {
418 // We recalculate the entry here -- we've called out to java since
419 // the last time it was calculated.
420 ClassLoaderData* loader_data = class_loader_data(class_loader);
422 Symbol* kn = klass->name();
423 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
424 int d_index = dictionary()->hash_to_index(d_hash);
426 MutexLocker mu(SystemDictionary_lock, THREAD);
427 {
428 // Note that we have an entry, and entries can be deleted only during GC,
429 // so we cannot allow GC to occur while we're holding this entry.
431 // We're using a No_Safepoint_Verifier to catch any place where we
432 // might potentially do a GC at all.
433 // Dictionary::do_unloading() asserts that classes in SD are only
434 // unloaded at a safepoint. Anonymous classes are not in SD.
435 No_Safepoint_Verifier nosafepoint;
436 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
437 protection_domain, THREAD);
438 }
439 }
440 }
442 // We only get here if this thread finds that another thread
443 // has already claimed the placeholder token for the current operation,
444 // but that other thread either never owned or gave up the
445 // object lock
446 // Waits on SystemDictionary_lock to indicate placeholder table updated
447 // On return, caller must recheck placeholder table state
448 //
449 // We only get here if
450 // 1) custom classLoader, i.e. not bootstrap classloader
451 // 2) UnsyncloadClass not set
452 // 3) custom classLoader has broken the class loader objectLock
453 // so another thread got here in parallel
454 //
455 // lockObject must be held.
456 // Complicated dance due to lock ordering:
457 // Must first release the classloader object lock to
458 // allow initial definer to complete the class definition
459 // and to avoid deadlock
460 // Reclaim classloader lock object with same original recursion count
461 // Must release SystemDictionary_lock after notify, since
462 // class loader lock must be claimed before SystemDictionary_lock
463 // to prevent deadlocks
464 //
465 // The notify allows applications that did an untimed wait() on
466 // the classloader object lock to not hang.
467 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
468 assert_lock_strong(SystemDictionary_lock);
470 bool calledholdinglock
471 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
472 assert(calledholdinglock,"must hold lock for notify");
473 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
474 ObjectSynchronizer::notifyall(lockObject, THREAD);
475 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
476 SystemDictionary_lock->wait();
477 SystemDictionary_lock->unlock();
478 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
479 SystemDictionary_lock->lock();
480 }
482 // If the class in is in the placeholder table, class loading is in progress
483 // For cases where the application changes threads to load classes, it
484 // is critical to ClassCircularity detection that we try loading
485 // the superclass on the same thread internally, so we do parallel
486 // super class loading here.
487 // This also is critical in cases where the original thread gets stalled
488 // even in non-circularity situations.
489 // Note: must call resolve_super_or_fail even if null super -
490 // to force placeholder entry creation for this class for circularity detection
491 // Caller must check for pending exception
492 // Returns non-null Klass* if other thread has completed load
493 // and we are done,
494 // If return null Klass* and no pending exception, the caller must load the class
495 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
496 Symbol* name, Symbol* superclassname, Handle class_loader,
497 Handle protection_domain, Handle lockObject, TRAPS) {
499 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
500 ClassLoaderData* loader_data = class_loader_data(class_loader);
501 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
502 int d_index = dictionary()->hash_to_index(d_hash);
503 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
504 int p_index = placeholders()->hash_to_index(p_hash);
506 // superk is not used, resolve_super called for circularity check only
507 // This code is reached in two situations. One if this thread
508 // is loading the same class twice (e.g. ClassCircularity, or
509 // java.lang.instrument).
510 // The second is if another thread started the resolve_super first
511 // and has not yet finished.
512 // In both cases the original caller will clean up the placeholder
513 // entry on error.
514 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
515 superclassname,
516 class_loader,
517 protection_domain,
518 true,
519 CHECK_(nh));
521 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
522 // Serial class loaders and bootstrap classloader do wait for superclass loads
523 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
524 MutexLocker mu(SystemDictionary_lock, THREAD);
525 // Check if classloading completed while we were loading superclass or waiting
526 Klass* check = find_class(d_index, d_hash, name, loader_data);
527 if (check != NULL) {
528 // Klass is already loaded, so just return it
529 return(instanceKlassHandle(THREAD, check));
530 } else {
531 return nh;
532 }
533 }
535 // must loop to both handle other placeholder updates
536 // and spurious notifications
537 bool super_load_in_progress = true;
538 PlaceholderEntry* placeholder;
539 while (super_load_in_progress) {
540 MutexLocker mu(SystemDictionary_lock, THREAD);
541 // Check if classloading completed while we were loading superclass or waiting
542 Klass* check = find_class(d_index, d_hash, name, loader_data);
543 if (check != NULL) {
544 // Klass is already loaded, so just return it
545 return(instanceKlassHandle(THREAD, check));
546 } else {
547 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
548 if (placeholder && placeholder->super_load_in_progress() ){
549 // Before UnsyncloadClass:
550 // We only get here if the application has released the
551 // classloader lock when another thread was in the middle of loading a
552 // superclass/superinterface for this class, and now
553 // this thread is also trying to load this class.
554 // To minimize surprises, the first thread that started to
555 // load a class should be the one to complete the loading
556 // with the classfile it initially expected.
557 // This logic has the current thread wait once it has done
558 // all the superclass/superinterface loading it can, until
559 // the original thread completes the class loading or fails
560 // If it completes we will use the resulting InstanceKlass
561 // which we will find below in the systemDictionary.
562 // We also get here for parallel bootstrap classloader
563 if (class_loader.is_null()) {
564 SystemDictionary_lock->wait();
565 } else {
566 double_lock_wait(lockObject, THREAD);
567 }
568 } else {
569 // If not in SD and not in PH, other thread's load must have failed
570 super_load_in_progress = false;
571 }
572 }
573 }
574 return (nh);
575 }
578 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle class_loader, Handle protection_domain, TRAPS) {
579 assert(name != NULL && !FieldType::is_array(name) &&
580 !FieldType::is_obj(name), "invalid class name");
582 // UseNewReflection
583 // Fix for 4474172; see evaluation for more details
584 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
585 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
587 // Do lookup to see if class already exist and the protection domain
588 // has the right access
589 // This call uses find which checks protection domain already matches
590 // All subsequent calls use find_class, and set has_loaded_class so that
591 // before we return a result we call out to java to check for valid protection domain
592 // to allow returning the Klass* and add it to the pd_set if it is valid
593 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
594 int d_index = dictionary()->hash_to_index(d_hash);
595 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
596 protection_domain, THREAD);
597 if (probe != NULL) return probe;
600 // Non-bootstrap class loaders will call out to class loader and
601 // define via jvm/jni_DefineClass which will acquire the
602 // class loader object lock to protect against multiple threads
603 // defining the class in parallel by accident.
604 // This lock must be acquired here so the waiter will find
605 // any successful result in the SystemDictionary and not attempt
606 // the define
607 // ParallelCapable Classloaders and the bootstrap classloader,
608 // or all classloaders with UnsyncloadClass do not acquire lock here
609 bool DoObjectLock = true;
610 if (is_parallelCapable(class_loader)) {
611 DoObjectLock = false;
612 }
614 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
615 int p_index = placeholders()->hash_to_index(p_hash);
617 // Class is not in SystemDictionary so we have to do loading.
618 // Make sure we are synchronized on the class loader before we proceed
619 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
620 check_loader_lock_contention(lockObject, THREAD);
621 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
623 // Check again (after locking) if class already exist in SystemDictionary
624 bool class_has_been_loaded = false;
625 bool super_load_in_progress = false;
626 bool havesupername = false;
627 instanceKlassHandle k;
628 PlaceholderEntry* placeholder;
629 Symbol* superclassname = NULL;
631 {
632 MutexLocker mu(SystemDictionary_lock, THREAD);
633 Klass* check = find_class(d_index, d_hash, name, loader_data);
634 if (check != NULL) {
635 // Klass is already loaded, so just return it
636 class_has_been_loaded = true;
637 k = instanceKlassHandle(THREAD, check);
638 } else {
639 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
640 if (placeholder && placeholder->super_load_in_progress()) {
641 super_load_in_progress = true;
642 if (placeholder->havesupername() == true) {
643 superclassname = placeholder->supername();
644 havesupername = true;
645 }
646 }
647 }
648 }
650 // If the class is in the placeholder table, class loading is in progress
651 if (super_load_in_progress && havesupername==true) {
652 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
653 class_loader, protection_domain, lockObject, THREAD);
654 if (HAS_PENDING_EXCEPTION) {
655 return NULL;
656 }
657 if (!k.is_null()) {
658 class_has_been_loaded = true;
659 }
660 }
662 bool throw_circularity_error = false;
663 if (!class_has_been_loaded) {
664 bool load_instance_added = false;
666 // add placeholder entry to record loading instance class
667 // Five cases:
668 // All cases need to prevent modifying bootclasssearchpath
669 // in parallel with a classload of same classname
670 // Redefineclasses uses existence of the placeholder for the duration
671 // of the class load to prevent concurrent redefinition of not completely
672 // defined classes.
673 // case 1. traditional classloaders that rely on the classloader object lock
674 // - no other need for LOAD_INSTANCE
675 // case 2. traditional classloaders that break the classloader object lock
676 // as a deadlock workaround. Detection of this case requires that
677 // this check is done while holding the classloader object lock,
678 // and that lock is still held when calling classloader's loadClass.
679 // For these classloaders, we ensure that the first requestor
680 // completes the load and other requestors wait for completion.
681 // case 3. UnsyncloadClass - don't use objectLocker
682 // With this flag, we allow parallel classloading of a
683 // class/classloader pair
684 // case4. Bootstrap classloader - don't own objectLocker
685 // This classloader supports parallelism at the classloader level,
686 // but only allows a single load of a class/classloader pair.
687 // No performance benefit and no deadlock issues.
688 // case 5. parallelCapable user level classloaders - without objectLocker
689 // Allow parallel classloading of a class/classloader pair
691 {
692 MutexLocker mu(SystemDictionary_lock, THREAD);
693 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
694 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
695 if (oldprobe) {
696 // only need check_seen_thread once, not on each loop
697 // 6341374 java/lang/Instrument with -Xcomp
698 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
699 throw_circularity_error = true;
700 } else {
701 // case 1: traditional: should never see load_in_progress.
702 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
704 // case 4: bootstrap classloader: prevent futile classloading,
705 // wait on first requestor
706 if (class_loader.is_null()) {
707 SystemDictionary_lock->wait();
708 } else {
709 // case 2: traditional with broken classloader lock. wait on first
710 // requestor.
711 double_lock_wait(lockObject, THREAD);
712 }
713 // Check if classloading completed while we were waiting
714 Klass* check = find_class(d_index, d_hash, name, loader_data);
715 if (check != NULL) {
716 // Klass is already loaded, so just return it
717 k = instanceKlassHandle(THREAD, check);
718 class_has_been_loaded = true;
719 }
720 // check if other thread failed to load and cleaned up
721 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
722 }
723 }
724 }
725 }
726 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
727 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
728 // LOAD_INSTANCE in parallel
730 if (!throw_circularity_error && !class_has_been_loaded) {
731 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
732 load_instance_added = true;
733 // For class loaders that do not acquire the classloader object lock,
734 // if they did not catch another thread holding LOAD_INSTANCE,
735 // need a check analogous to the acquire ObjectLocker/find_class
736 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
737 // one final check if the load has already completed
738 // class loaders holding the ObjectLock shouldn't find the class here
739 Klass* check = find_class(d_index, d_hash, name, loader_data);
740 if (check != NULL) {
741 // Klass is already loaded, so return it after checking/adding protection domain
742 k = instanceKlassHandle(THREAD, check);
743 class_has_been_loaded = true;
744 }
745 }
746 }
748 // must throw error outside of owning lock
749 if (throw_circularity_error) {
750 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
751 ResourceMark rm(THREAD);
752 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
753 }
755 if (!class_has_been_loaded) {
757 // Do actual loading
758 k = load_instance_class(name, class_loader, THREAD);
760 // For UnsyncloadClass only
761 // If they got a linkageError, check if a parallel class load succeeded.
762 // If it did, then for bytecode resolution the specification requires
763 // that we return the same result we did for the other thread, i.e. the
764 // successfully loaded InstanceKlass
765 // Should not get here for classloaders that support parallelism
766 // with the new cleaner mechanism, even with AllowParallelDefineClass
767 // Bootstrap goes through here to allow for an extra guarantee check
768 if (UnsyncloadClass || (class_loader.is_null())) {
769 if (k.is_null() && HAS_PENDING_EXCEPTION
770 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
771 MutexLocker mu(SystemDictionary_lock, THREAD);
772 Klass* check = find_class(d_index, d_hash, name, loader_data);
773 if (check != NULL) {
774 // Klass is already loaded, so just use it
775 k = instanceKlassHandle(THREAD, check);
776 CLEAR_PENDING_EXCEPTION;
777 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
778 }
779 }
780 }
782 // If everything was OK (no exceptions, no null return value), and
783 // class_loader is NOT the defining loader, do a little more bookkeeping.
784 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
785 k->class_loader() != class_loader()) {
787 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
789 // Need to check for a PENDING_EXCEPTION again; check_constraints
790 // can throw and doesn't use the CHECK macro.
791 if (!HAS_PENDING_EXCEPTION) {
792 { // Grabbing the Compile_lock prevents systemDictionary updates
793 // during compilations.
794 MutexLocker mu(Compile_lock, THREAD);
795 update_dictionary(d_index, d_hash, p_index, p_hash,
796 k, class_loader, THREAD);
797 }
798 if (JvmtiExport::should_post_class_load()) {
799 Thread *thread = THREAD;
800 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
801 JvmtiExport::post_class_load((JavaThread *) thread, k());
802 }
803 }
804 }
805 } // load_instance_class loop
807 if (load_instance_added == true) {
808 // clean up placeholder entries for LOAD_INSTANCE success or error
809 // This brackets the SystemDictionary updates for both defining
810 // and initiating loaders
811 MutexLocker mu(SystemDictionary_lock, THREAD);
812 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
813 SystemDictionary_lock->notify_all();
814 }
815 }
817 if (HAS_PENDING_EXCEPTION || k.is_null()) {
818 return NULL;
819 }
821 #ifdef ASSERT
822 {
823 ClassLoaderData* loader_data = k->class_loader_data();
824 MutexLocker mu(SystemDictionary_lock, THREAD);
825 Klass* kk = find_class(name, loader_data);
826 assert(kk == k(), "should be present in dictionary");
827 }
828 #endif
830 // return if the protection domain in NULL
831 if (protection_domain() == NULL) return k();
833 // Check the protection domain has the right access
834 {
835 MutexLocker mu(SystemDictionary_lock, THREAD);
836 // Note that we have an entry, and entries can be deleted only during GC,
837 // so we cannot allow GC to occur while we're holding this entry.
838 // We're using a No_Safepoint_Verifier to catch any place where we
839 // might potentially do a GC at all.
840 // Dictionary::do_unloading() asserts that classes in SD are only
841 // unloaded at a safepoint. Anonymous classes are not in SD.
842 No_Safepoint_Verifier nosafepoint;
843 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
844 loader_data,
845 protection_domain)) {
846 return k();
847 }
848 }
850 // Verify protection domain. If it fails an exception is thrown
851 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
853 return k();
854 }
857 // This routine does not lock the system dictionary.
858 //
859 // Since readers don't hold a lock, we must make sure that system
860 // dictionary entries are only removed at a safepoint (when only one
861 // thread is running), and are added to in a safe way (all links must
862 // be updated in an MT-safe manner).
863 //
864 // Callers should be aware that an entry could be added just after
865 // _dictionary->bucket(index) is read here, so the caller will not see
866 // the new entry.
868 Klass* SystemDictionary::find(Symbol* class_name,
869 Handle class_loader,
870 Handle protection_domain,
871 TRAPS) {
873 // UseNewReflection
874 // The result of this call should be consistent with the result
875 // of the call to resolve_instance_class_or_null().
876 // See evaluation 6790209 and 4474172 for more details.
877 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
878 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
880 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
881 int d_index = dictionary()->hash_to_index(d_hash);
883 {
884 // Note that we have an entry, and entries can be deleted only during GC,
885 // so we cannot allow GC to occur while we're holding this entry.
886 // We're using a No_Safepoint_Verifier to catch any place where we
887 // might potentially do a GC at all.
888 // Dictionary::do_unloading() asserts that classes in SD are only
889 // unloaded at a safepoint. Anonymous classes are not in SD.
890 No_Safepoint_Verifier nosafepoint;
891 return dictionary()->find(d_index, d_hash, class_name, loader_data,
892 protection_domain, THREAD);
893 }
894 }
897 // Look for a loaded instance or array klass by name. Do not do any loading.
898 // return NULL in case of error.
899 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
900 Handle class_loader,
901 Handle protection_domain,
902 TRAPS) {
903 Klass* k = NULL;
904 assert(class_name != NULL, "class name must be non NULL");
906 if (FieldType::is_array(class_name)) {
907 // The name refers to an array. Parse the name.
908 // dimension and object_key in FieldArrayInfo are assigned as a
909 // side-effect of this call
910 FieldArrayInfo fd;
911 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
912 if (t != T_OBJECT) {
913 k = Universe::typeArrayKlassObj(t);
914 } else {
915 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
916 }
917 if (k != NULL) {
918 k = k->array_klass_or_null(fd.dimension());
919 }
920 } else {
921 k = find(class_name, class_loader, protection_domain, THREAD);
922 }
923 return k;
924 }
926 // Note: this method is much like resolve_from_stream, but
927 // updates no supplemental data structures.
928 // TODO consolidate the two methods with a helper routine?
929 Klass* SystemDictionary::parse_stream(Symbol* class_name,
930 Handle class_loader,
931 Handle protection_domain,
932 ClassFileStream* st,
933 KlassHandle host_klass,
934 GrowableArray<Handle>* cp_patches,
935 TRAPS) {
936 TempNewSymbol parsed_name = NULL;
938 ClassLoaderData* loader_data;
939 if (host_klass.not_null()) {
940 // Create a new CLD for anonymous class, that uses the same class loader
941 // as the host_klass
942 assert(EnableInvokeDynamic, "");
943 guarantee(host_klass->class_loader() == class_loader(), "should be the same");
944 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
945 loader_data->record_dependency(host_klass(), CHECK_NULL);
946 } else {
947 loader_data = ClassLoaderData::class_loader_data(class_loader());
948 }
950 // Parse the stream. Note that we do this even though this klass might
951 // already be present in the SystemDictionary, otherwise we would not
952 // throw potential ClassFormatErrors.
953 //
954 // Note: "name" is updated.
956 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
957 loader_data,
958 protection_domain,
959 host_klass,
960 cp_patches,
961 parsed_name,
962 true,
963 THREAD);
966 if (host_klass.not_null() && k.not_null()) {
967 assert(EnableInvokeDynamic, "");
968 k->set_host_klass(host_klass());
969 // If it's anonymous, initialize it now, since nobody else will.
971 {
972 MutexLocker mu_r(Compile_lock, THREAD);
974 // Add to class hierarchy, initialize vtables, and do possible
975 // deoptimizations.
976 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
978 // But, do not add to system dictionary.
979 }
981 // Rewrite and patch constant pool here.
982 k->link_class(CHECK_NULL);
983 if (cp_patches != NULL) {
984 k->constants()->patch_resolved_references(cp_patches);
985 }
986 k->eager_initialize(CHECK_NULL);
988 // notify jvmti
989 if (JvmtiExport::should_post_class_load()) {
990 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
991 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
992 }
993 }
994 assert(host_klass.not_null() || cp_patches == NULL,
995 "cp_patches only found with host_klass");
997 return k();
998 }
1000 // Add a klass to the system from a stream (called by jni_DefineClass and
1001 // JVM_DefineClass).
1002 // Note: class_name can be NULL. In that case we do not know the name of
1003 // the class until we have parsed the stream.
1005 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1006 Handle class_loader,
1007 Handle protection_domain,
1008 ClassFileStream* st,
1009 bool verify,
1010 TRAPS) {
1012 // Classloaders that support parallelism, e.g. bootstrap classloader,
1013 // or all classloaders with UnsyncloadClass do not acquire lock here
1014 bool DoObjectLock = true;
1015 if (is_parallelCapable(class_loader)) {
1016 DoObjectLock = false;
1017 }
1019 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1021 // Make sure we are synchronized on the class loader before we proceed
1022 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1023 check_loader_lock_contention(lockObject, THREAD);
1024 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1026 TempNewSymbol parsed_name = NULL;
1028 // Parse the stream. Note that we do this even though this klass might
1029 // already be present in the SystemDictionary, otherwise we would not
1030 // throw potential ClassFormatErrors.
1031 //
1032 // Note: "name" is updated.
1034 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1035 loader_data,
1036 protection_domain,
1037 parsed_name,
1038 verify,
1039 THREAD);
1041 const char* pkg = "java/";
1042 if (!HAS_PENDING_EXCEPTION &&
1043 !class_loader.is_null() &&
1044 parsed_name != NULL &&
1045 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1046 // It is illegal to define classes in the "java." package from
1047 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1048 ResourceMark rm(THREAD);
1049 char* name = parsed_name->as_C_string();
1050 char* index = strrchr(name, '/');
1051 *index = '\0'; // chop to just the package name
1052 while ((index = strchr(name, '/')) != NULL) {
1053 *index = '.'; // replace '/' with '.' in package name
1054 }
1055 const char* fmt = "Prohibited package name: %s";
1056 size_t len = strlen(fmt) + strlen(name);
1057 char* message = NEW_RESOURCE_ARRAY(char, len);
1058 jio_snprintf(message, len, fmt, name);
1059 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1060 vmSymbols::java_lang_SecurityException(), message);
1061 }
1063 if (!HAS_PENDING_EXCEPTION) {
1064 assert(parsed_name != NULL, "Sanity");
1065 assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1066 // Verification prevents us from creating names with dots in them, this
1067 // asserts that that's the case.
1068 assert(is_internal_format(parsed_name),
1069 "external class name format used internally");
1071 // Add class just loaded
1072 // If a class loader supports parallel classloading handle parallel define requests
1073 // find_or_define_instance_class may return a different InstanceKlass
1074 if (is_parallelCapable(class_loader)) {
1075 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1076 } else {
1077 define_instance_class(k, THREAD);
1078 }
1079 }
1081 // Make sure we have an entry in the SystemDictionary on success
1082 debug_only( {
1083 if (!HAS_PENDING_EXCEPTION) {
1084 assert(parsed_name != NULL, "parsed_name is still null?");
1085 Symbol* h_name = k->name();
1086 ClassLoaderData *defining_loader_data = k->class_loader_data();
1088 MutexLocker mu(SystemDictionary_lock, THREAD);
1090 Klass* check = find_class(parsed_name, loader_data);
1091 assert(check == k(), "should be present in the dictionary");
1093 Klass* check2 = find_class(h_name, defining_loader_data);
1094 assert(check == check2, "name inconsistancy in SystemDictionary");
1095 }
1096 } );
1098 return k();
1099 }
1102 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1103 int number_of_entries) {
1104 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1105 "bad shared dictionary size.");
1106 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1107 }
1110 // If there is a shared dictionary, then find the entry for the
1111 // given shared system class, if any.
1113 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1114 if (shared_dictionary() != NULL) {
1115 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1116 int d_index = shared_dictionary()->hash_to_index(d_hash);
1118 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1119 } else {
1120 return NULL;
1121 }
1122 }
1125 // Load a class from the shared spaces (found through the shared system
1126 // dictionary). Force the superclass and all interfaces to be loaded.
1127 // Update the class definition to include sibling classes and no
1128 // subclasses (yet). [Classes in the shared space are not part of the
1129 // object hierarchy until loaded.]
1131 instanceKlassHandle SystemDictionary::load_shared_class(
1132 Symbol* class_name, Handle class_loader, TRAPS) {
1133 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1134 return load_shared_class(ik, class_loader, THREAD);
1135 }
1137 // Note well! Changes to this method may affect oop access order
1138 // in the shared archive. Please take care to not make changes that
1139 // adversely affect cold start time by changing the oop access order
1140 // that is specified in dump.cpp MarkAndMoveOrderedReadOnly and
1141 // MarkAndMoveOrderedReadWrite closures.
1142 instanceKlassHandle SystemDictionary::load_shared_class(
1143 instanceKlassHandle ik, Handle class_loader, TRAPS) {
1144 assert(class_loader.is_null(), "non-null classloader for shared class?");
1145 if (ik.not_null()) {
1146 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1147 Symbol* class_name = ik->name();
1149 // Found the class, now load the superclass and interfaces. If they
1150 // are shared, add them to the main system dictionary and reset
1151 // their hierarchy references (supers, subs, and interfaces).
1153 if (ik->super() != NULL) {
1154 Symbol* cn = ik->super()->name();
1155 resolve_super_or_fail(class_name, cn,
1156 class_loader, Handle(), true, CHECK_(nh));
1157 }
1159 Array<Klass*>* interfaces = ik->local_interfaces();
1160 int num_interfaces = interfaces->length();
1161 for (int index = 0; index < num_interfaces; index++) {
1162 Klass* k = interfaces->at(index);
1164 // Note: can not use InstanceKlass::cast here because
1165 // interfaces' InstanceKlass's C++ vtbls haven't been
1166 // reinitialized yet (they will be once the interface classes
1167 // are loaded)
1168 Symbol* name = k->name();
1169 resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(nh));
1170 }
1172 // Adjust methods to recover missing data. They need addresses for
1173 // interpreter entry points and their default native method address
1174 // must be reset.
1176 // Updating methods must be done under a lock so multiple
1177 // threads don't update these in parallel
1178 // Shared classes are all currently loaded by the bootstrap
1179 // classloader, so this will never cause a deadlock on
1180 // a custom class loader lock.
1182 {
1183 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1184 check_loader_lock_contention(lockObject, THREAD);
1185 ObjectLocker ol(lockObject, THREAD, true);
1186 ik->restore_unshareable_info(CHECK_(nh));
1187 }
1189 if (TraceClassLoading) {
1190 ResourceMark rm;
1191 tty->print("[Loaded %s", ik->external_name());
1192 tty->print(" from shared objects file");
1193 tty->print_cr("]");
1194 }
1195 // notify a class loaded from shared object
1196 ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()),
1197 true /* shared class */);
1198 }
1199 return ik;
1200 }
1202 #ifdef KERNEL
1203 // Some classes on the bootstrap class path haven't been installed on the
1204 // system yet. Call the DownloadManager method to make them appear in the
1205 // bootstrap class path and try again to load the named class.
1206 // Note that with delegation class loaders all classes in another loader will
1207 // first try to call this so it'd better be fast!!
1208 static instanceKlassHandle download_and_retry_class_load(
1209 Symbol* class_name,
1210 TRAPS) {
1212 Klass* dlm = SystemDictionary::DownloadManager_klass();
1213 instanceKlassHandle nk;
1215 // If download manager class isn't loaded just return.
1216 if (dlm == NULL) return nk;
1218 { HandleMark hm(THREAD);
1219 ResourceMark rm(THREAD);
1220 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nk));
1221 Handle class_string = java_lang_String::externalize_classname(s, CHECK_(nk));
1223 // return value
1224 JavaValue result(T_OBJECT);
1226 // Call the DownloadManager. We assume that it has a lock because
1227 // multiple classes could be not found and downloaded at the same time.
1228 // class sun.misc.DownloadManager;
1229 // public static String getBootClassPathEntryForClass(String className);
1230 JavaCalls::call_static(&result,
1231 KlassHandle(THREAD, dlm),
1232 vmSymbols::getBootClassPathEntryForClass_name(),
1233 vmSymbols::string_string_signature(),
1234 class_string,
1235 CHECK_(nk));
1237 // Get result.string and add to bootclasspath
1238 assert(result.get_type() == T_OBJECT, "just checking");
1239 oop obj = (oop) result.get_jobject();
1240 if (obj == NULL) { return nk; }
1242 Handle h_obj(THREAD, obj);
1243 char* new_class_name = java_lang_String::as_platform_dependent_str(h_obj,
1244 CHECK_(nk));
1246 // lock the loader
1247 // we use this lock because JVMTI does.
1248 Handle loader_lock(THREAD, SystemDictionary::system_loader_lock());
1250 ObjectLocker ol(loader_lock, THREAD);
1251 // add the file to the bootclasspath
1252 ClassLoader::update_class_path_entry_list(new_class_name, true);
1253 } // end HandleMark
1255 if (TraceClassLoading) {
1256 ClassLoader::print_bootclasspath();
1257 }
1258 return ClassLoader::load_classfile(class_name, CHECK_(nk));
1259 }
1260 #endif // KERNEL
1263 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1264 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1265 if (class_loader.is_null()) {
1267 // Search the shared system dictionary for classes preloaded into the
1268 // shared spaces.
1269 instanceKlassHandle k;
1270 {
1271 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1272 k = load_shared_class(class_name, class_loader, THREAD);
1273 }
1275 if (k.is_null()) {
1276 // Use VM class loader
1277 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1278 k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1279 }
1281 #ifdef KERNEL
1282 // If the VM class loader has failed to load the class, call the
1283 // DownloadManager class to make it magically appear on the classpath
1284 // and try again. This is only configured with the Kernel VM.
1285 if (k.is_null()) {
1286 k = download_and_retry_class_load(class_name, CHECK_(nh));
1287 }
1288 #endif // KERNEL
1290 // find_or_define_instance_class may return a different InstanceKlass
1291 if (!k.is_null()) {
1292 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1293 }
1294 return k;
1295 } else {
1296 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1297 ResourceMark rm(THREAD);
1299 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1300 JavaThread* jt = (JavaThread*) THREAD;
1302 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1303 ClassLoader::perf_app_classload_selftime(),
1304 ClassLoader::perf_app_classload_count(),
1305 jt->get_thread_stat()->perf_recursion_counts_addr(),
1306 jt->get_thread_stat()->perf_timers_addr(),
1307 PerfClassTraceTime::CLASS_LOAD);
1309 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1310 // Translate to external class name format, i.e., convert '/' chars to '.'
1311 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1313 JavaValue result(T_OBJECT);
1315 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1317 // Call public unsynchronized loadClass(String) directly for all class loaders
1318 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1319 // acquire a class-name based lock rather than the class loader object lock.
1320 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1321 // so the call to loadClassInternal() was not required.
1322 //
1323 // UnsyncloadClass flag means both call loadClass(String) and do
1324 // not acquire the class loader lock even for class loaders that are
1325 // not parallelCapable. This was a risky transitional
1326 // flag for diagnostic purposes only. It is risky to call
1327 // custom class loaders without synchronization.
1328 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1329 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1330 // Do NOT assume this will be supported in future releases.
1331 //
1332 // Added MustCallLoadClassInternal in case we discover in the field
1333 // a customer that counts on this call
1334 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1335 JavaCalls::call_special(&result,
1336 class_loader,
1337 spec_klass,
1338 vmSymbols::loadClassInternal_name(),
1339 vmSymbols::string_class_signature(),
1340 string,
1341 CHECK_(nh));
1342 } else {
1343 JavaCalls::call_virtual(&result,
1344 class_loader,
1345 spec_klass,
1346 vmSymbols::loadClass_name(),
1347 vmSymbols::string_class_signature(),
1348 string,
1349 CHECK_(nh));
1350 }
1352 assert(result.get_type() == T_OBJECT, "just checking");
1353 oop obj = (oop) result.get_jobject();
1355 // Primitive classes return null since forName() can not be
1356 // used to obtain any of the Class objects representing primitives or void
1357 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1358 instanceKlassHandle k =
1359 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1360 // For user defined Java class loaders, check that the name returned is
1361 // the same as that requested. This check is done for the bootstrap
1362 // loader when parsing the class file.
1363 if (class_name == k->name()) {
1364 return k;
1365 }
1366 }
1367 // Class is not found or has the wrong name, return NULL
1368 return nh;
1369 }
1370 }
1372 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1374 ClassLoaderData* loader_data = k->class_loader_data();
1375 Handle class_loader_h(THREAD, loader_data->class_loader());
1377 for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){}
1379 // for bootstrap and other parallel classloaders don't acquire lock,
1380 // use placeholder token
1381 // If a parallelCapable class loader calls define_instance_class instead of
1382 // find_or_define_instance_class to get here, we have a timing
1383 // hole with systemDictionary updates and check_constraints
1384 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1385 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1386 compute_loader_lock_object(class_loader_h, THREAD)),
1387 "define called without lock");
1388 }
1390 // Check class-loading constraints. Throw exception if violation is detected.
1391 // Grabs and releases SystemDictionary_lock
1392 // The check_constraints/find_class call and update_dictionary sequence
1393 // must be "atomic" for a specific class/classloader pair so we never
1394 // define two different instanceKlasses for that class/classloader pair.
1395 // Existing classloaders will call define_instance_class with the
1396 // classloader lock held
1397 // Parallel classloaders will call find_or_define_instance_class
1398 // which will require a token to perform the define class
1399 Symbol* name_h = k->name();
1400 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1401 int d_index = dictionary()->hash_to_index(d_hash);
1402 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1404 // Register class just loaded with class loader (placed in Vector)
1405 // Note we do this before updating the dictionary, as this can
1406 // fail with an OutOfMemoryError (if it does, we will *not* put this
1407 // class in the dictionary and will not update the class hierarchy).
1408 // JVMTI FollowReferences needs to find the classes this way.
1409 if (k->class_loader() != NULL) {
1410 methodHandle m(THREAD, Universe::loader_addClass_method());
1411 JavaValue result(T_VOID);
1412 JavaCallArguments args(class_loader_h);
1413 args.push_oop(Handle(THREAD, k->java_mirror()));
1414 JavaCalls::call(&result, m, &args, CHECK);
1415 }
1417 // Add the new class. We need recompile lock during update of CHA.
1418 {
1419 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1420 int p_index = placeholders()->hash_to_index(p_hash);
1422 MutexLocker mu_r(Compile_lock, THREAD);
1424 // Add to class hierarchy, initialize vtables, and do possible
1425 // deoptimizations.
1426 add_to_hierarchy(k, CHECK); // No exception, but can block
1428 // Add to systemDictionary - so other classes can see it.
1429 // Grabs and releases SystemDictionary_lock
1430 update_dictionary(d_index, d_hash, p_index, p_hash,
1431 k, class_loader_h, THREAD);
1432 }
1433 k->eager_initialize(THREAD);
1435 // notify jvmti
1436 if (JvmtiExport::should_post_class_load()) {
1437 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1438 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1440 }
1441 }
1443 // Support parallel classloading
1444 // All parallel class loaders, including bootstrap classloader
1445 // lock a placeholder entry for this class/class_loader pair
1446 // to allow parallel defines of different classes for this class loader
1447 // With AllowParallelDefine flag==true, in case they do not synchronize around
1448 // FindLoadedClass/DefineClass, calls, we check for parallel
1449 // loading for them, wait if a defineClass is in progress
1450 // and return the initial requestor's results
1451 // This flag does not apply to the bootstrap classloader.
1452 // With AllowParallelDefine flag==false, call through to define_instance_class
1453 // which will throw LinkageError: duplicate class definition.
1454 // False is the requested default.
1455 // For better performance, the class loaders should synchronize
1456 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1457 // potentially waste time reading and parsing the bytestream.
1458 // Note: VM callers should ensure consistency of k/class_name,class_loader
1459 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1461 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1462 Symbol* name_h = k->name(); // passed in class_name may be null
1463 ClassLoaderData* loader_data = class_loader_data(class_loader);
1465 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1466 int d_index = dictionary()->hash_to_index(d_hash);
1468 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1469 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1470 int p_index = placeholders()->hash_to_index(p_hash);
1471 PlaceholderEntry* probe;
1473 {
1474 MutexLocker mu(SystemDictionary_lock, THREAD);
1475 // First check if class already defined
1476 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1477 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1478 if (check != NULL) {
1479 return(instanceKlassHandle(THREAD, check));
1480 }
1481 }
1483 // Acquire define token for this class/classloader
1484 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1485 // Wait if another thread defining in parallel
1486 // All threads wait - even those that will throw duplicate class: otherwise
1487 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1488 // if other thread has not finished updating dictionary
1489 while (probe->definer() != NULL) {
1490 SystemDictionary_lock->wait();
1491 }
1492 // Only special cases allow parallel defines and can use other thread's results
1493 // Other cases fall through, and may run into duplicate defines
1494 // caught by finding an entry in the SystemDictionary
1495 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1496 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1497 SystemDictionary_lock->notify_all();
1498 #ifdef ASSERT
1499 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1500 assert(check != NULL, "definer missed recording success");
1501 #endif
1502 return(instanceKlassHandle(THREAD, probe->instance_klass()));
1503 } else {
1504 // This thread will define the class (even if earlier thread tried and had an error)
1505 probe->set_definer(THREAD);
1506 }
1507 }
1509 define_instance_class(k, THREAD);
1511 Handle linkage_exception = Handle(); // null handle
1513 // definer must notify any waiting threads
1514 {
1515 MutexLocker mu(SystemDictionary_lock, THREAD);
1516 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1517 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1518 if (probe != NULL) {
1519 if (HAS_PENDING_EXCEPTION) {
1520 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1521 CLEAR_PENDING_EXCEPTION;
1522 } else {
1523 probe->set_instance_klass(k());
1524 }
1525 probe->set_definer(NULL);
1526 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1527 SystemDictionary_lock->notify_all();
1528 }
1529 }
1531 // Can't throw exception while holding lock due to rank ordering
1532 if (linkage_exception() != NULL) {
1533 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1534 }
1536 return k;
1537 }
1538 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1539 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1540 if (class_loader.is_null()) {
1541 return Handle(THREAD, _system_loader_lock_obj);
1542 } else {
1543 return class_loader;
1544 }
1545 }
1547 // This method is added to check how often we have to wait to grab loader
1548 // lock. The results are being recorded in the performance counters defined in
1549 // ClassLoader::_sync_systemLoaderLockContentionRate and
1550 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1551 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1552 if (!UsePerfData) {
1553 return;
1554 }
1556 assert(!loader_lock.is_null(), "NULL lock object");
1558 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1559 == ObjectSynchronizer::owner_other) {
1560 // contention will likely happen, so increment the corresponding
1561 // contention counter.
1562 if (loader_lock() == _system_loader_lock_obj) {
1563 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1564 } else {
1565 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1566 }
1567 }
1568 }
1570 // ----------------------------------------------------------------------------
1571 // Lookup
1573 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1574 Symbol* class_name,
1575 ClassLoaderData* loader_data) {
1576 assert_locked_or_safepoint(SystemDictionary_lock);
1577 assert (index == dictionary()->index_for(class_name, loader_data),
1578 "incorrect index?");
1580 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1581 return k;
1582 }
1585 // Basic find on classes in the midst of being loaded
1586 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1587 ClassLoaderData* loader_data) {
1588 assert_locked_or_safepoint(SystemDictionary_lock);
1589 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1590 int p_index = placeholders()->hash_to_index(p_hash);
1591 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1592 }
1595 // Used for assertions and verification only
1596 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1597 #ifndef ASSERT
1598 guarantee(VerifyBeforeGC ||
1599 VerifyDuringGC ||
1600 VerifyBeforeExit ||
1601 VerifyAfterGC, "too expensive");
1602 #endif
1603 assert_locked_or_safepoint(SystemDictionary_lock);
1605 // First look in the loaded class array
1606 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1607 int d_index = dictionary()->hash_to_index(d_hash);
1608 return find_class(d_index, d_hash, class_name, loader_data);
1609 }
1612 // Get the next class in the diictionary.
1613 Klass* SystemDictionary::try_get_next_class() {
1614 return dictionary()->try_get_next_class();
1615 }
1618 // ----------------------------------------------------------------------------
1619 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1620 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1621 // before a new class is used.
1623 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1624 assert(k.not_null(), "just checking");
1625 assert_locked_or_safepoint(Compile_lock);
1627 // Link into hierachy. Make sure the vtables are initialized before linking into
1628 k->append_to_sibling_list(); // add to superklass/sibling list
1629 k->process_interfaces(THREAD); // handle all "implements" declarations
1630 k->set_init_state(InstanceKlass::loaded);
1631 // Now flush all code that depended on old class hierarchy.
1632 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1633 // Also, first reinitialize vtable because it may have gotten out of synch
1634 // while the new class wasn't connected to the class hierarchy.
1635 Universe::flush_dependents_on(k);
1636 }
1639 // ----------------------------------------------------------------------------
1640 // GC support
1642 // Following roots during mark-sweep is separated in two phases.
1643 //
1644 // The first phase follows preloaded classes and all other system
1645 // classes, since these will never get unloaded anyway.
1646 //
1647 // The second phase removes (unloads) unreachable classes from the
1648 // system dictionary and follows the remaining classes' contents.
1650 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1651 blk->do_oop(&_java_system_loader);
1652 blk->do_oop(&_system_loader_lock_obj);
1654 dictionary()->always_strong_oops_do(blk);
1656 // Visit extra methods
1657 invoke_method_table()->oops_do(blk);
1658 }
1660 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1661 // Follow all system classes and temporary placeholders in dictionary
1662 dictionary()->always_strong_classes_do(closure);
1664 // Placeholders. These represent classes we're actively loading.
1665 placeholders()->classes_do(closure);
1666 }
1668 // Calculate a "good" systemdictionary size based
1669 // on predicted or current loaded classes count
1670 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1671 int newsize = _old_default_sdsize;
1672 if ((classcount > 0) && !DumpSharedSpaces) {
1673 int desiredsize = classcount/_average_depth_goal;
1674 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1675 newsize = _primelist[++_sdgeneration]) {
1676 if (desiredsize <= newsize) {
1677 break;
1678 }
1679 }
1680 }
1681 return newsize;
1682 }
1683 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1684 // Note: anonymous classes are not in the SD.
1685 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
1686 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1687 bool has_dead_loaders = ClassLoaderDataGraph::do_unloading(is_alive);
1688 bool unloading_occurred = false;
1689 if (has_dead_loaders) {
1690 unloading_occurred = dictionary()->do_unloading();
1691 constraints()->purge_loader_constraints();
1692 resolution_errors()->purge_resolution_errors();
1693 }
1694 return unloading_occurred;
1695 }
1697 void SystemDictionary::oops_do(OopClosure* f) {
1698 f->do_oop(&_java_system_loader);
1699 f->do_oop(&_system_loader_lock_obj);
1701 // Adjust dictionary
1702 dictionary()->oops_do(f);
1704 // Visit extra methods
1705 invoke_method_table()->oops_do(f);
1706 }
1708 // Extended Class redefinition support.
1709 // If one of these classes is replaced, we need to replace it in these places.
1710 // KlassClosure::do_klass should take the address of a class but we can
1711 // change that later.
1712 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1713 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1714 f->do_klass(_well_known_klasses[k]);
1715 }
1717 {
1718 for (int i = 0; i < T_VOID+1; i++) {
1719 if (_box_klasses[i] != NULL) {
1720 assert(i >= T_BOOLEAN, "checking");
1721 f->do_klass(_box_klasses[i]);
1722 }
1723 }
1724 }
1726 FilteredFieldsMap::classes_do(f);
1727 }
1729 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1730 f->do_klass(_abstract_ownable_synchronizer_klass);
1731 }
1733 // Just the classes from defining class loaders
1734 // Don't iterate over placeholders
1735 void SystemDictionary::classes_do(void f(Klass*)) {
1736 dictionary()->classes_do(f);
1737 }
1739 // Added for initialize_itable_for_klass
1740 // Just the classes from defining class loaders
1741 // Don't iterate over placeholders
1742 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1743 dictionary()->classes_do(f, CHECK);
1744 }
1746 // All classes, and their class loaders
1747 // Don't iterate over placeholders
1748 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1749 dictionary()->classes_do(f);
1750 }
1752 // All classes, and their class loaders
1753 // (added for helpers that use HandleMarks and ResourceMarks)
1754 // Don't iterate over placeholders
1755 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*, TRAPS), TRAPS) {
1756 dictionary()->classes_do(f, CHECK);
1757 }
1759 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1760 placeholders()->entries_do(f);
1761 }
1763 void SystemDictionary::methods_do(void f(Method*)) {
1764 dictionary()->methods_do(f);
1765 invoke_method_table()->methods_do(f);
1766 }
1768 // ----------------------------------------------------------------------------
1769 // Lazily load klasses
1771 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1772 assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");
1774 // if multiple threads calling this function, only one thread will load
1775 // the class. The other threads will find the loaded version once the
1776 // class is loaded.
1777 Klass* aos = _abstract_ownable_synchronizer_klass;
1778 if (aos == NULL) {
1779 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1780 // Force a fence to prevent any read before the write completes
1781 OrderAccess::fence();
1782 _abstract_ownable_synchronizer_klass = k;
1783 }
1784 }
1786 // ----------------------------------------------------------------------------
1787 // Initialization
1789 void SystemDictionary::initialize(TRAPS) {
1790 // Allocate arrays
1791 assert(dictionary() == NULL,
1792 "SystemDictionary should only be initialized once");
1793 _sdgeneration = 0;
1794 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1795 _placeholders = new PlaceholderTable(_nof_buckets);
1796 _number_of_modifications = 0;
1797 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1798 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1799 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1801 // Allocate private object used as system class loader lock
1802 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1803 // Initialize basic classes
1804 initialize_preloaded_classes(CHECK);
1805 }
1807 // Compact table of directions on the initialization of klasses:
1808 static const short wk_init_info[] = {
1809 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1810 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1811 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1812 | (int)SystemDictionary::option ),
1813 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1814 #undef WK_KLASS_INIT_INFO
1815 0
1816 };
1818 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1819 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1820 int info = wk_init_info[id - FIRST_WKID];
1821 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1822 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1823 Klass** klassp = &_well_known_klasses[id];
1824 bool must_load = (init_opt < SystemDictionary::Opt);
1825 bool try_load = true;
1826 if (init_opt == SystemDictionary::Opt_Kernel) {
1827 #ifndef KERNEL
1828 try_load = false;
1829 #endif //KERNEL
1830 }
1831 if ((*klassp) == NULL && try_load) {
1832 if (must_load) {
1833 (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class
1834 } else {
1835 (*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass
1836 }
1837 }
1838 return ((*klassp) != NULL);
1839 }
1841 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1842 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1843 for (int id = (int)start_id; id < (int)limit_id; id++) {
1844 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1845 int info = wk_init_info[id - FIRST_WKID];
1846 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1847 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1849 initialize_wk_klass((WKID)id, opt, CHECK);
1850 }
1852 // move the starting value forward to the limit:
1853 start_id = limit_id;
1854 }
1856 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1857 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1858 // Preload commonly used klasses
1859 WKID scan = FIRST_WKID;
1860 // first do Object, then String, Class
1861 if (UseSharedSpaces) {
1862 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1863 // Initialize the constant pool for the Object_class
1864 InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1865 ik->constants()->restore_unshareable_info(CHECK);
1866 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1867 } else {
1868 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1869 }
1871 // Calculate offsets for String and Class classes since they are loaded and
1872 // can be used after this point.
1873 java_lang_String::compute_offsets();
1874 java_lang_Class::compute_offsets();
1876 // Fixup mirrors for classes loaded before java.lang.Class.
1877 // These calls iterate over the objects currently in the perm gen
1878 // so calling them at this point is matters (not before when there
1879 // are fewer objects and not later after there are more objects
1880 // in the perm gen.
1881 Universe::initialize_basic_type_mirrors(CHECK);
1882 Universe::fixup_mirrors(CHECK);
1884 // do a bunch more:
1885 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1887 // Preload ref klasses and set reference types
1888 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1889 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1891 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
1892 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1893 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1894 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1895 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1897 // JSR 292 classes
1898 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1899 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1900 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1901 if (EnableInvokeDynamic) {
1902 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1903 } else {
1904 // Skip the JSR 292 classes, if not enabled.
1905 scan = WKID(jsr292_group_end + 1);
1906 }
1908 initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);
1910 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1911 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
1912 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
1913 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
1914 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
1915 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
1916 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
1917 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
1918 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
1919 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
1921 #ifdef KERNEL
1922 if (DownloadManager_klass() == NULL) {
1923 warning("Cannot find sun/jkernel/DownloadManager");
1924 }
1925 #endif // KERNEL
1927 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
1928 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
1929 _has_loadClassInternal = (method != NULL);
1930 }
1931 { // Compute whether we should use checkPackageAccess or NOT
1932 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
1933 _has_checkPackageAccess = (method != NULL);
1934 }
1935 }
1937 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
1938 // If so, returns the basic type it holds. If not, returns T_OBJECT.
1939 BasicType SystemDictionary::box_klass_type(Klass* k) {
1940 assert(k != NULL, "");
1941 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
1942 if (_box_klasses[i] == k)
1943 return (BasicType)i;
1944 }
1945 return T_OBJECT;
1946 }
1948 // Constraints on class loaders. The details of the algorithm can be
1949 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1950 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1951 // that the system dictionary needs to maintain a set of contraints that
1952 // must be satisfied by all classes in the dictionary.
1953 // if defining is true, then LinkageError if already in systemDictionary
1954 // if initiating loader, then ok if InstanceKlass matches existing entry
1956 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
1957 instanceKlassHandle k,
1958 Handle class_loader, bool defining,
1959 TRAPS) {
1960 const char *linkage_error = NULL;
1961 {
1962 Symbol* name = k->name();
1963 ClassLoaderData *loader_data = class_loader_data(class_loader);
1965 MutexLocker mu(SystemDictionary_lock, THREAD);
1967 Klass* check = find_class(d_index, d_hash, name, loader_data);
1968 if (check != (Klass*)NULL) {
1969 // if different InstanceKlass - duplicate class definition,
1970 // else - ok, class loaded by a different thread in parallel,
1971 // we should only have found it if it was done loading and ok to use
1972 // system dictionary only holds instance classes, placeholders
1973 // also holds array classes
1975 assert(check->oop_is_instance(), "noninstance in systemdictionary");
1976 if ((defining == true) || (k() != check)) {
1977 linkage_error = "loader (instance of %s): attempted duplicate class "
1978 "definition for name: \"%s\"";
1979 } else {
1980 return;
1981 }
1982 }
1984 #ifdef ASSERT
1985 Symbol* ph_check = find_placeholder(name, loader_data);
1986 assert(ph_check == NULL || ph_check == name, "invalid symbol");
1987 #endif
1989 if (linkage_error == NULL) {
1990 if (constraints()->check_or_update(k, class_loader, name) == false) {
1991 linkage_error = "loader constraint violation: loader (instance of %s)"
1992 " previously initiated loading for a different type with name \"%s\"";
1993 }
1994 }
1995 }
1997 // Throw error now if needed (cannot throw while holding
1998 // SystemDictionary_lock because of rank ordering)
2000 if (linkage_error) {
2001 ResourceMark rm(THREAD);
2002 const char* class_loader_name = loader_name(class_loader());
2003 char* type_name = k->name()->as_C_string();
2004 size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +
2005 strlen(type_name);
2006 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2007 jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);
2008 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2009 }
2010 }
2013 // Update system dictionary - done after check_constraint and add_to_hierachy
2014 // have been called.
2015 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2016 int p_index, unsigned int p_hash,
2017 instanceKlassHandle k,
2018 Handle class_loader,
2019 TRAPS) {
2020 // Compile_lock prevents systemDictionary updates during compilations
2021 assert_locked_or_safepoint(Compile_lock);
2022 Symbol* name = k->name();
2023 ClassLoaderData *loader_data = class_loader_data(class_loader);
2025 {
2026 MutexLocker mu1(SystemDictionary_lock, THREAD);
2028 // See whether biased locking is enabled and if so set it for this
2029 // klass.
2030 // Note that this must be done past the last potential blocking
2031 // point / safepoint. We enable biased locking lazily using a
2032 // VM_Operation to iterate the SystemDictionary and installing the
2033 // biasable mark word into each InstanceKlass's prototype header.
2034 // To avoid race conditions where we accidentally miss enabling the
2035 // optimization for one class in the process of being added to the
2036 // dictionary, we must not safepoint after the test of
2037 // BiasedLocking::enabled().
2038 if (UseBiasedLocking && BiasedLocking::enabled()) {
2039 // Set biased locking bit for all loaded classes; it will be
2040 // cleared if revocation occurs too often for this type
2041 // NOTE that we must only do this when the class is initally
2042 // defined, not each time it is referenced from a new class loader
2043 if (k->class_loader() == class_loader()) {
2044 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2045 }
2046 }
2048 // Assign a classid if one has not already been assigned. The
2049 // counter does not need to be atomically incremented since this
2050 // is only done while holding the SystemDictionary_lock.
2051 // All loaded classes get a unique ID.
2052 TRACE_INIT_ID(k);
2054 // Make a new system dictionary entry.
2055 Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2056 if (sd_check == NULL) {
2057 dictionary()->add_klass(name, loader_data, k);
2058 notice_modification();
2059 }
2060 #ifdef ASSERT
2061 sd_check = find_class(d_index, d_hash, name, loader_data);
2062 assert (sd_check != NULL, "should have entry in system dictionary");
2063 // Note: there may be a placeholder entry: for circularity testing
2064 // or for parallel defines
2065 #endif
2066 SystemDictionary_lock->notify_all();
2067 }
2068 }
2071 // Try to find a class name using the loader constraints. The
2072 // loader constraints might know about a class that isn't fully loaded
2073 // yet and these will be ignored.
2074 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2075 Symbol* class_name, Handle class_loader, TRAPS) {
2077 // First see if it has been loaded directly.
2078 // Force the protection domain to be null. (This removes protection checks.)
2079 Handle no_protection_domain;
2080 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2081 no_protection_domain, CHECK_NULL);
2082 if (klass != NULL)
2083 return klass;
2085 // Now look to see if it has been loaded elsewhere, and is subject to
2086 // a loader constraint that would require this loader to return the
2087 // klass that is already loaded.
2088 if (FieldType::is_array(class_name)) {
2089 // For array classes, their Klass*s are not kept in the
2090 // constraint table. The element Klass*s are.
2091 FieldArrayInfo fd;
2092 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2093 if (t != T_OBJECT) {
2094 klass = Universe::typeArrayKlassObj(t);
2095 } else {
2096 MutexLocker mu(SystemDictionary_lock, THREAD);
2097 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2098 }
2099 // If element class already loaded, allocate array klass
2100 if (klass != NULL) {
2101 klass = klass->array_klass_or_null(fd.dimension());
2102 }
2103 } else {
2104 MutexLocker mu(SystemDictionary_lock, THREAD);
2105 // Non-array classes are easy: simply check the constraint table.
2106 klass = constraints()->find_constrained_klass(class_name, class_loader);
2107 }
2109 return klass;
2110 }
2113 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2114 Handle class_loader1,
2115 Handle class_loader2,
2116 Thread* THREAD) {
2117 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2118 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2120 Symbol* constraint_name = NULL;
2121 if (!FieldType::is_array(class_name)) {
2122 constraint_name = class_name;
2123 } else {
2124 // For array classes, their Klass*s are not kept in the
2125 // constraint table. The element classes are.
2126 FieldArrayInfo fd;
2127 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2128 // primitive types always pass
2129 if (t != T_OBJECT) {
2130 return true;
2131 } else {
2132 constraint_name = fd.object_key();
2133 }
2134 }
2135 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2136 int d_index1 = dictionary()->hash_to_index(d_hash1);
2138 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2139 int d_index2 = dictionary()->hash_to_index(d_hash2);
2140 {
2141 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2143 // Better never do a GC while we're holding these oops
2144 No_Safepoint_Verifier nosafepoint;
2146 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2147 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2148 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2149 klass2, class_loader2);
2150 }
2151 }
2153 // Add entry to resolution error table to record the error when the first
2154 // attempt to resolve a reference to a class has failed.
2155 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) {
2156 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2157 int index = resolution_errors()->hash_to_index(hash);
2158 {
2159 MutexLocker ml(SystemDictionary_lock, Thread::current());
2160 resolution_errors()->add_entry(index, hash, pool, which, error);
2161 }
2162 }
2164 // Delete a resolution error for RedefineClasses for a constant pool is going away
2165 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2166 resolution_errors()->delete_entry(pool);
2167 }
2169 // Lookup resolution error table. Returns error if found, otherwise NULL.
2170 Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {
2171 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2172 int index = resolution_errors()->hash_to_index(hash);
2173 {
2174 MutexLocker ml(SystemDictionary_lock, Thread::current());
2175 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2176 return (entry != NULL) ? entry->error() : (Symbol*)NULL;
2177 }
2178 }
2181 // Signature constraints ensure that callers and callees agree about
2182 // the meaning of type names in their signatures. This routine is the
2183 // intake for constraints. It collects them from several places:
2184 //
2185 // * LinkResolver::resolve_method (if check_access is true) requires
2186 // that the resolving class (the caller) and the defining class of
2187 // the resolved method (the callee) agree on each type in the
2188 // method's signature.
2189 //
2190 // * LinkResolver::resolve_interface_method performs exactly the same
2191 // checks.
2192 //
2193 // * LinkResolver::resolve_field requires that the constant pool
2194 // attempting to link to a field agree with the field's defining
2195 // class about the type of the field signature.
2196 //
2197 // * klassVtable::initialize_vtable requires that, when a class
2198 // overrides a vtable entry allocated by a superclass, that the
2199 // overriding method (i.e., the callee) agree with the superclass
2200 // on each type in the method's signature.
2201 //
2202 // * klassItable::initialize_itable requires that, when a class fills
2203 // in its itables, for each non-abstract method installed in an
2204 // itable, the method (i.e., the callee) agree with the interface
2205 // on each type in the method's signature.
2206 //
2207 // All those methods have a boolean (check_access, checkconstraints)
2208 // which turns off the checks. This is used from specialized contexts
2209 // such as bootstrapping, dumping, and debugging.
2210 //
2211 // No direct constraint is placed between the class and its
2212 // supertypes. Constraints are only placed along linked relations
2213 // between callers and callees. When a method overrides or implements
2214 // an abstract method in a supertype (superclass or interface), the
2215 // constraints are placed as if the supertype were the caller to the
2216 // overriding method. (This works well, since callers to the
2217 // supertype have already established agreement between themselves and
2218 // the supertype.) As a result of all this, a class can disagree with
2219 // its supertype about the meaning of a type name, as long as that
2220 // class neither calls a relevant method of the supertype, nor is
2221 // called (perhaps via an override) from the supertype.
2222 //
2223 //
2224 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2225 //
2226 // Make sure all class components (including arrays) in the given
2227 // signature will be resolved to the same class in both loaders.
2228 // Returns the name of the type that failed a loader constraint check, or
2229 // NULL if no constraint failed. The returned C string needs cleaning up
2230 // with a ResourceMark in the caller. No exception except OOME is thrown.
2231 // Arrays are not added to the loader constraint table, their elements are.
2232 char* SystemDictionary::check_signature_loaders(Symbol* signature,
2233 Handle loader1, Handle loader2,
2234 bool is_method, TRAPS) {
2235 // Nothing to do if loaders are the same.
2236 if (loader1() == loader2()) {
2237 return NULL;
2238 }
2240 ResourceMark rm(THREAD);
2241 SignatureStream sig_strm(signature, is_method);
2242 while (!sig_strm.is_done()) {
2243 if (sig_strm.is_object()) {
2244 Symbol* s = sig_strm.as_symbol(CHECK_NULL);
2245 Symbol* sig = s;
2246 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2247 return sig->as_C_string();
2248 }
2249 }
2250 sig_strm.next();
2251 }
2252 return NULL;
2253 }
2256 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2257 Symbol* signature,
2258 TRAPS) {
2259 methodHandle empty;
2260 assert(EnableInvokeDynamic, "");
2261 assert(MethodHandles::is_signature_polymorphic(iid) &&
2262 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2263 iid != vmIntrinsics::_invokeGeneric,
2264 err_msg("must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)));
2266 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2267 int index = invoke_method_table()->hash_to_index(hash);
2268 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2269 methodHandle m;
2270 if (spe == NULL || spe->method() == NULL) {
2271 spe = NULL;
2272 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2273 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2274 CompileBroker::compile_method(m, InvocationEntryBci, CompLevel_highest_tier,
2275 methodHandle(), CompileThreshold, "MH", CHECK_(empty));
2277 // Now grab the lock. We might have to throw away the new method,
2278 // if a racing thread has managed to install one at the same time.
2279 {
2280 MutexLocker ml(SystemDictionary_lock, THREAD);
2281 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2282 if (spe == NULL)
2283 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2284 if (spe->method() == NULL)
2285 spe->set_method(m());
2286 }
2287 }
2289 assert(spe != NULL && spe->method() != NULL, "");
2290 return spe->method();
2291 }
2293 // Helper for unpacking the return value from linkMethod and linkCallSite.
2294 static methodHandle unpack_method_and_appendix(Handle mname,
2295 KlassHandle accessing_klass,
2296 objArrayHandle appendix_box,
2297 Handle* appendix_result,
2298 TRAPS) {
2299 methodHandle empty;
2300 if (mname.not_null()) {
2301 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2302 if (vmtarget != NULL && vmtarget->is_method()) {
2303 Method* m = (Method*)vmtarget;
2304 oop appendix = appendix_box->obj_at(0);
2305 if (TraceMethodHandles) {
2306 #ifndef PRODUCT
2307 tty->print("Linked method="INTPTR_FORMAT": ", m);
2308 m->print();
2309 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2310 tty->cr();
2311 #endif //PRODUCT
2312 }
2313 (*appendix_result) = Handle(THREAD, appendix);
2314 // the target is stored in the cpCache and if a reference to this
2315 // MethodName is dropped we need a way to make sure the
2316 // class_loader containing this method is kept alive.
2317 // FIXME: the appendix might also preserve this dependency.
2318 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2319 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2320 return methodHandle(THREAD, m);
2321 }
2322 }
2323 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2324 return empty;
2325 }
2327 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2328 Symbol* signature,
2329 KlassHandle accessing_klass,
2330 Handle *appendix_result,
2331 Handle *method_type_result,
2332 TRAPS) {
2333 methodHandle empty;
2334 assert(EnableInvokeDynamic, "");
2335 assert(!THREAD->is_Compiler_thread(), "");
2336 Handle method_type =
2337 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2338 if (false) { // FIXME: Decide if the Java upcall should resolve signatures.
2339 method_type = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2340 }
2342 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass();
2343 int ref_kind = JVM_REF_invokeVirtual;
2344 Handle name_str = StringTable::intern(name, CHECK_(empty));
2345 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2346 assert(appendix_box->obj_at(0) == NULL, "");
2348 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2349 JavaCallArguments args;
2350 args.push_oop(accessing_klass()->java_mirror());
2351 args.push_int(ref_kind);
2352 args.push_oop(mh_klass()->java_mirror());
2353 args.push_oop(name_str());
2354 args.push_oop(method_type());
2355 args.push_oop(appendix_box());
2356 JavaValue result(T_OBJECT);
2357 JavaCalls::call_static(&result,
2358 SystemDictionary::MethodHandleNatives_klass(),
2359 vmSymbols::linkMethod_name(),
2360 vmSymbols::linkMethod_signature(),
2361 &args, CHECK_(empty));
2362 Handle mname(THREAD, (oop) result.get_jobject());
2363 (*method_type_result) = method_type;
2364 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2365 }
2368 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2369 // signature, as interpreted relative to the given class loader.
2370 // Because of class loader constraints, all method handle usage must be
2371 // consistent with this loader.
2372 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2373 KlassHandle accessing_klass,
2374 TRAPS) {
2375 Handle empty;
2376 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2377 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2378 int index = invoke_method_table()->hash_to_index(hash);
2379 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2380 if (spe != NULL && spe->method_type() != NULL) {
2381 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2382 return Handle(THREAD, spe->method_type());
2383 } else if (THREAD->is_Compiler_thread()) {
2384 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2385 return Handle(); // do not attempt from within compiler, unless it was cached
2386 }
2388 Handle class_loader, protection_domain;
2389 bool is_on_bcp = true; // keep this true as long as we can materialize from the boot classloader
2390 int npts = ArgumentCount(signature).size();
2391 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2392 int arg = 0;
2393 Handle rt; // the return type from the signature
2394 ResourceMark rm(THREAD);
2395 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2396 oop mirror = NULL;
2397 if (is_on_bcp) {
2398 // Note: class_loader & protection_domain are both null at this point.
2399 mirror = ss.as_java_mirror(class_loader, protection_domain,
2400 SignatureStream::ReturnNull, CHECK_(empty));
2401 if (mirror == NULL) {
2402 // fall back from BCP to accessing_klass
2403 if (accessing_klass.not_null()) {
2404 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2405 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2406 }
2407 is_on_bcp = false;
2408 }
2409 }
2410 if (!is_on_bcp) {
2411 // Resolve, throwing a real error if it doesn't work.
2412 mirror = ss.as_java_mirror(class_loader, protection_domain,
2413 SignatureStream::NCDFError, CHECK_(empty));
2414 }
2415 if (ss.at_return_type())
2416 rt = Handle(THREAD, mirror);
2417 else
2418 pts->obj_at_put(arg++, mirror);
2420 // Check accessibility.
2421 if (ss.is_object() && accessing_klass.not_null()) {
2422 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2423 mirror = NULL; // safety
2424 // Emulate ConstantPool::verify_constant_pool_resolve.
2425 if (sel_klass->oop_is_objArray())
2426 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2427 if (sel_klass->oop_is_instance()) {
2428 KlassHandle sel_kh(THREAD, sel_klass);
2429 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2430 }
2431 }
2432 }
2433 assert(arg == npts, "");
2435 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2436 JavaCallArguments args(Handle(THREAD, rt()));
2437 args.push_oop(pts());
2438 JavaValue result(T_OBJECT);
2439 JavaCalls::call_static(&result,
2440 SystemDictionary::MethodHandleNatives_klass(),
2441 vmSymbols::findMethodHandleType_name(),
2442 vmSymbols::findMethodHandleType_signature(),
2443 &args, CHECK_(empty));
2444 Handle method_type(THREAD, (oop) result.get_jobject());
2446 if (is_on_bcp) {
2447 // We can cache this MethodType inside the JVM.
2448 MutexLocker ml(SystemDictionary_lock, THREAD);
2449 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2450 if (spe == NULL)
2451 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2452 if (spe->method_type() == NULL) {
2453 spe->set_method_type(method_type());
2454 }
2455 }
2457 // report back to the caller with the MethodType
2458 return method_type;
2459 }
2461 // Ask Java code to find or construct a method handle constant.
2462 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2463 int ref_kind, //e.g., JVM_REF_invokeVirtual
2464 KlassHandle callee,
2465 Symbol* name_sym,
2466 Symbol* signature,
2467 TRAPS) {
2468 Handle empty;
2469 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2470 Handle type;
2471 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2472 type = find_method_handle_type(signature, caller, CHECK_(empty));
2473 } else {
2474 ResourceMark rm(THREAD);
2475 SignatureStream ss(signature, false);
2476 if (!ss.is_done()) {
2477 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2478 SignatureStream::NCDFError, CHECK_(empty));
2479 type = Handle(THREAD, mirror);
2480 ss.next();
2481 if (!ss.is_done()) type = Handle(); // error!
2482 }
2483 }
2484 if (type.is_null()) {
2485 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2486 }
2488 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2489 JavaCallArguments args;
2490 args.push_oop(caller->java_mirror()); // the referring class
2491 args.push_int(ref_kind);
2492 args.push_oop(callee->java_mirror()); // the target class
2493 args.push_oop(name());
2494 args.push_oop(type());
2495 JavaValue result(T_OBJECT);
2496 JavaCalls::call_static(&result,
2497 SystemDictionary::MethodHandleNatives_klass(),
2498 vmSymbols::linkMethodHandleConstant_name(),
2499 vmSymbols::linkMethodHandleConstant_signature(),
2500 &args, CHECK_(empty));
2501 return Handle(THREAD, (oop) result.get_jobject());
2502 }
2504 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2505 // name and signature, as interpreted relative to the given class loader.
2506 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2507 Handle bootstrap_specifier,
2508 Symbol* name,
2509 Symbol* type,
2510 Handle *appendix_result,
2511 Handle *method_type_result,
2512 TRAPS) {
2513 methodHandle empty;
2514 Handle bsm, info;
2515 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2516 bsm = bootstrap_specifier;
2517 } else {
2518 assert(bootstrap_specifier->is_objArray(), "");
2519 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2520 int len = args->length();
2521 assert(len >= 1, "");
2522 bsm = Handle(THREAD, args->obj_at(0));
2523 if (len > 1) {
2524 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2525 for (int i = 1; i < len; i++)
2526 args1->obj_at_put(i-1, args->obj_at(i));
2527 info = Handle(THREAD, args1);
2528 }
2529 }
2530 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2531 "caller must supply a valid BSM");
2533 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2534 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2536 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2537 assert(appendix_box->obj_at(0) == NULL, "");
2539 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2540 JavaCallArguments args;
2541 args.push_oop(caller->java_mirror());
2542 args.push_oop(bsm());
2543 args.push_oop(method_name());
2544 args.push_oop(method_type());
2545 args.push_oop(info());
2546 args.push_oop(appendix_box);
2547 JavaValue result(T_OBJECT);
2548 JavaCalls::call_static(&result,
2549 SystemDictionary::MethodHandleNatives_klass(),
2550 vmSymbols::linkCallSite_name(),
2551 vmSymbols::linkCallSite_signature(),
2552 &args, CHECK_(empty));
2553 Handle mname(THREAD, (oop) result.get_jobject());
2554 (*method_type_result) = method_type;
2555 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2556 }
2558 // Since the identity hash code for symbols changes when the symbols are
2559 // moved from the regular perm gen (hash in the mark word) to the shared
2560 // spaces (hash is the address), the classes loaded into the dictionary
2561 // may be in the wrong buckets.
2563 void SystemDictionary::reorder_dictionary() {
2564 dictionary()->reorder_dictionary();
2565 }
2568 void SystemDictionary::copy_buckets(char** top, char* end) {
2569 dictionary()->copy_buckets(top, end);
2570 }
2573 void SystemDictionary::copy_table(char** top, char* end) {
2574 dictionary()->copy_table(top, end);
2575 }
2578 void SystemDictionary::reverse() {
2579 dictionary()->reverse();
2580 }
2582 int SystemDictionary::number_of_classes() {
2583 return dictionary()->number_of_entries();
2584 }
2587 // ----------------------------------------------------------------------------
2588 #ifndef PRODUCT
2590 void SystemDictionary::print() {
2591 dictionary()->print();
2593 // Placeholders
2594 GCMutexLocker mu(SystemDictionary_lock);
2595 placeholders()->print();
2597 // loader constraints - print under SD_lock
2598 constraints()->print();
2599 }
2601 #endif
2603 void SystemDictionary::verify() {
2604 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2605 guarantee(constraints() != NULL,
2606 "Verify of loader constraints failed");
2607 guarantee(dictionary()->number_of_entries() >= 0 &&
2608 placeholders()->number_of_entries() >= 0,
2609 "Verify of system dictionary failed");
2611 // Verify dictionary
2612 dictionary()->verify();
2614 GCMutexLocker mu(SystemDictionary_lock);
2615 placeholders()->verify();
2617 // Verify constraint table
2618 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2619 constraints()->verify(dictionary(), placeholders());
2620 }
2623 void SystemDictionary::verify_obj_klass_present(Symbol* class_name,
2624 ClassLoaderData* loader_data) {
2625 GCMutexLocker mu(SystemDictionary_lock);
2626 Symbol* name;
2628 Klass* probe = find_class(class_name, loader_data);
2629 if (probe == NULL) {
2630 probe = SystemDictionary::find_shared_class(class_name);
2631 if (probe == NULL) {
2632 name = find_placeholder(class_name, loader_data);
2633 }
2634 }
2635 guarantee(probe != NULL || name != NULL,
2636 "Loaded klasses should be in SystemDictionary");
2637 }
2639 #ifndef PRODUCT
2641 // statistics code
2642 class ClassStatistics: AllStatic {
2643 private:
2644 static int nclasses; // number of classes
2645 static int nmethods; // number of methods
2646 static int nmethoddata; // number of methodData
2647 static int class_size; // size of class objects in words
2648 static int method_size; // size of method objects in words
2649 static int debug_size; // size of debug info in methods
2650 static int methoddata_size; // size of methodData objects in words
2652 static void do_class(Klass* k) {
2653 nclasses++;
2654 class_size += k->size();
2655 if (k->oop_is_instance()) {
2656 InstanceKlass* ik = (InstanceKlass*)k;
2657 class_size += ik->methods()->size();
2658 class_size += ik->constants()->size();
2659 class_size += ik->local_interfaces()->size();
2660 class_size += ik->transitive_interfaces()->size();
2661 // We do not have to count implementors, since we only store one!
2662 // SSS: How should these be accounted now that they have moved?
2663 // class_size += ik->fields()->length();
2664 }
2665 }
2667 static void do_method(Method* m) {
2668 nmethods++;
2669 method_size += m->size();
2670 // class loader uses same objArray for empty vectors, so don't count these
2671 if (m->has_stackmap_table()) {
2672 method_size += m->stackmap_data()->size();
2673 }
2675 MethodData* mdo = m->method_data();
2676 if (mdo != NULL) {
2677 nmethoddata++;
2678 methoddata_size += mdo->size();
2679 }
2680 }
2682 public:
2683 static void print() {
2684 SystemDictionary::classes_do(do_class);
2685 SystemDictionary::methods_do(do_method);
2686 tty->print_cr("Class statistics:");
2687 tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
2688 tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
2689 (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
2690 tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
2691 }
2692 };
2695 int ClassStatistics::nclasses = 0;
2696 int ClassStatistics::nmethods = 0;
2697 int ClassStatistics::nmethoddata = 0;
2698 int ClassStatistics::class_size = 0;
2699 int ClassStatistics::method_size = 0;
2700 int ClassStatistics::debug_size = 0;
2701 int ClassStatistics::methoddata_size = 0;
2703 void SystemDictionary::print_class_statistics() {
2704 ResourceMark rm;
2705 ClassStatistics::print();
2706 }
2709 class MethodStatistics: AllStatic {
2710 public:
2711 enum {
2712 max_parameter_size = 10
2713 };
2714 private:
2716 static int _number_of_methods;
2717 static int _number_of_final_methods;
2718 static int _number_of_static_methods;
2719 static int _number_of_native_methods;
2720 static int _number_of_synchronized_methods;
2721 static int _number_of_profiled_methods;
2722 static int _number_of_bytecodes;
2723 static int _parameter_size_profile[max_parameter_size];
2724 static int _bytecodes_profile[Bytecodes::number_of_java_codes];
2726 static void initialize() {
2727 _number_of_methods = 0;
2728 _number_of_final_methods = 0;
2729 _number_of_static_methods = 0;
2730 _number_of_native_methods = 0;
2731 _number_of_synchronized_methods = 0;
2732 _number_of_profiled_methods = 0;
2733 _number_of_bytecodes = 0;
2734 for (int i = 0; i < max_parameter_size ; i++) _parameter_size_profile[i] = 0;
2735 for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile [j] = 0;
2736 };
2738 static void do_method(Method* m) {
2739 _number_of_methods++;
2740 // collect flag info
2741 if (m->is_final() ) _number_of_final_methods++;
2742 if (m->is_static() ) _number_of_static_methods++;
2743 if (m->is_native() ) _number_of_native_methods++;
2744 if (m->is_synchronized()) _number_of_synchronized_methods++;
2745 if (m->method_data() != NULL) _number_of_profiled_methods++;
2746 // collect parameter size info (add one for receiver, if any)
2747 _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
2748 // collect bytecodes info
2749 {
2750 Thread *thread = Thread::current();
2751 HandleMark hm(thread);
2752 BytecodeStream s(methodHandle(thread, m));
2753 Bytecodes::Code c;
2754 while ((c = s.next()) >= 0) {
2755 _number_of_bytecodes++;
2756 _bytecodes_profile[c]++;
2757 }
2758 }
2759 }
2761 public:
2762 static void print() {
2763 initialize();
2764 SystemDictionary::methods_do(do_method);
2765 // generate output
2766 tty->cr();
2767 tty->print_cr("Method statistics (static):");
2768 // flag distribution
2769 tty->cr();
2770 tty->print_cr("%6d final methods %6.1f%%", _number_of_final_methods , _number_of_final_methods * 100.0F / _number_of_methods);
2771 tty->print_cr("%6d static methods %6.1f%%", _number_of_static_methods , _number_of_static_methods * 100.0F / _number_of_methods);
2772 tty->print_cr("%6d native methods %6.1f%%", _number_of_native_methods , _number_of_native_methods * 100.0F / _number_of_methods);
2773 tty->print_cr("%6d synchronized methods %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
2774 tty->print_cr("%6d profiled methods %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
2775 // parameter size profile
2776 tty->cr();
2777 { int tot = 0;
2778 int avg = 0;
2779 for (int i = 0; i < max_parameter_size; i++) {
2780 int n = _parameter_size_profile[i];
2781 tot += n;
2782 avg += n*i;
2783 tty->print_cr("parameter size = %1d: %6d methods %5.1f%%", i, n, n * 100.0F / _number_of_methods);
2784 }
2785 assert(tot == _number_of_methods, "should be the same");
2786 tty->print_cr(" %6d methods 100.0%%", _number_of_methods);
2787 tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
2788 }
2789 // bytecodes profile
2790 tty->cr();
2791 { int tot = 0;
2792 for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
2793 if (Bytecodes::is_defined(i)) {
2794 Bytecodes::Code c = Bytecodes::cast(i);
2795 int n = _bytecodes_profile[c];
2796 tot += n;
2797 tty->print_cr("%9d %7.3f%% %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
2798 }
2799 }
2800 assert(tot == _number_of_bytecodes, "should be the same");
2801 tty->print_cr("%9d 100.000%%", _number_of_bytecodes);
2802 }
2803 tty->cr();
2804 }
2805 };
2807 int MethodStatistics::_number_of_methods;
2808 int MethodStatistics::_number_of_final_methods;
2809 int MethodStatistics::_number_of_static_methods;
2810 int MethodStatistics::_number_of_native_methods;
2811 int MethodStatistics::_number_of_synchronized_methods;
2812 int MethodStatistics::_number_of_profiled_methods;
2813 int MethodStatistics::_number_of_bytecodes;
2814 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
2815 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
2818 void SystemDictionary::print_method_statistics() {
2819 MethodStatistics::print();
2820 }
2822 #endif // PRODUCT