1 /*
2 * Copyright 1997-2009 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_systemDictionary.cpp.incl"
27
28
29 Dictionary* SystemDictionary::_dictionary = NULL;
30 PlaceholderTable* SystemDictionary::_placeholders = NULL;
31 Dictionary* SystemDictionary::_shared_dictionary = NULL;
32 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
33 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
34 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
35
36
37 int SystemDictionary::_number_of_modifications = 0;
38
39 oop SystemDictionary::_system_loader_lock_obj = NULL;
40
41 klassOop SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
42 = { NULL /*, NULL...*/ };
43
44 klassOop SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
45
46 oop SystemDictionary::_java_system_loader = NULL;
47
48 bool SystemDictionary::_has_loadClassInternal = false;
49 bool SystemDictionary::_has_checkPackageAccess = false;
50
51 // lazily initialized klass variables
52 volatile klassOop SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
53
54
55 // ----------------------------------------------------------------------------
56 // Java-level SystemLoader
57
58 oop SystemDictionary::java_system_loader() {
59 return _java_system_loader;
60 }
61
62 void SystemDictionary::compute_java_system_loader(TRAPS) {
63 KlassHandle system_klass(THREAD, WK_KLASS(classloader_klass));
64 JavaValue result(T_OBJECT);
65 JavaCalls::call_static(&result,
66 KlassHandle(THREAD, WK_KLASS(classloader_klass)),
67 vmSymbolHandles::getSystemClassLoader_name(),
68 vmSymbolHandles::void_classloader_signature(),
69 CHECK);
70
71 _java_system_loader = (oop)result.get_jobject();
72 }
73
74
75 // ----------------------------------------------------------------------------
76 // debugging
77
78 #ifdef ASSERT
79
80 // return true if class_name contains no '.' (internal format is '/')
81 bool SystemDictionary::is_internal_format(symbolHandle class_name) {
82 if (class_name.not_null()) {
83 ResourceMark rm;
84 char* name = class_name->as_C_string();
85 return strchr(name, '.') == NULL;
86 } else {
87 return true;
88 }
89 }
90
91 #endif
92
93 // ----------------------------------------------------------------------------
94 // Parallel class loading check
95
96 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
97 if (UnsyncloadClass || class_loader.is_null()) return true;
98 if (AlwaysLockClassLoader) return false;
99 return java_lang_Class::parallelCapable(class_loader());
100 }
101 // ----------------------------------------------------------------------------
102 // ParallelDefineClass flag does not apply to bootclass loader
103 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
104 if (class_loader.is_null()) return false;
105 if (AllowParallelDefineClass && java_lang_Class::parallelCapable(class_loader())) {
106 return true;
107 }
108 return false;
109 }
110 // ----------------------------------------------------------------------------
111 // Resolving of classes
112
113 // Forwards to resolve_or_null
114
115 klassOop SystemDictionary::resolve_or_fail(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
116 klassOop klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
117 if (HAS_PENDING_EXCEPTION || klass == NULL) {
118 KlassHandle k_h(THREAD, klass);
119 // can return a null klass
120 klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);
121 }
122 return klass;
123 }
124
125 klassOop SystemDictionary::handle_resolution_exception(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {
126 if (HAS_PENDING_EXCEPTION) {
127 // If we have a pending exception we forward it to the caller, unless throw_error is true,
128 // in which case we have to check whether the pending exception is a ClassNotFoundException,
129 // and if so convert it to a NoClassDefFoundError
130 // And chain the original ClassNotFoundException
131 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::classNotFoundException_klass())) {
132 ResourceMark rm(THREAD);
133 assert(klass_h() == NULL, "Should not have result with exception pending");
134 Handle e(THREAD, PENDING_EXCEPTION);
135 CLEAR_PENDING_EXCEPTION;
136 THROW_MSG_CAUSE_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
137 } else {
138 return NULL;
139 }
140 }
141 // Class not found, throw appropriate error or exception depending on value of throw_error
142 if (klass_h() == NULL) {
143 ResourceMark rm(THREAD);
144 if (throw_error) {
145 THROW_MSG_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
146 } else {
147 THROW_MSG_0(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
148 }
149 }
150 return (klassOop)klass_h();
151 }
152
153
154 klassOop SystemDictionary::resolve_or_fail(symbolHandle class_name,
155 bool throw_error, TRAPS)
156 {
157 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
158 }
159
160
161 // Forwards to resolve_instance_class_or_null
162
163 klassOop SystemDictionary::resolve_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS) {
164 assert(!THREAD->is_Compiler_thread(), "Can not load classes with the Compiler thread");
165 if (FieldType::is_array(class_name())) {
166 return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
167 } else {
168 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
169 }
170 }
171
172 klassOop SystemDictionary::resolve_or_null(symbolHandle class_name, TRAPS) {
173 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
174 }
175
176 // Forwards to resolve_instance_class_or_null
177
178 klassOop SystemDictionary::resolve_array_class_or_null(symbolHandle class_name,
179 Handle class_loader,
180 Handle protection_domain,
181 TRAPS) {
182 assert(FieldType::is_array(class_name()), "must be array");
183 jint dimension;
184 symbolOop object_key;
185 klassOop k = NULL;
186 // dimension and object_key are assigned as a side-effect of this call
187 BasicType t = FieldType::get_array_info(class_name(),
188 &dimension,
189 &object_key,
190 CHECK_NULL);
191
192 if (t == T_OBJECT) {
193 symbolHandle h_key(THREAD, object_key);
194 // naked oop "k" is OK here -- we assign back into it
195 k = SystemDictionary::resolve_instance_class_or_null(h_key,
196 class_loader,
197 protection_domain,
198 CHECK_NULL);
199 if (k != NULL) {
200 k = Klass::cast(k)->array_klass(dimension, CHECK_NULL);
201 }
202 } else {
203 k = Universe::typeArrayKlassObj(t);
204 k = typeArrayKlass::cast(k)->array_klass(dimension, CHECK_NULL);
205 }
206 return k;
207 }
208
209
210 // Must be called for any super-class or super-interface resolution
211 // during class definition to allow class circularity checking
212 // super-interface callers:
213 // parse_interfaces - for defineClass & jvmtiRedefineClasses
214 // super-class callers:
215 // ClassFileParser - for defineClass & jvmtiRedefineClasses
216 // load_shared_class - while loading a class from shared archive
217 // resolve_instance_class_or_null:
218 // via: handle_parallel_super_load
219 // when resolving a class that has an existing placeholder with
220 // a saved superclass [i.e. a defineClass is currently in progress]
221 // if another thread is trying to resolve the class, it must do
222 // super-class checks on its own thread to catch class circularity
223 // This last call is critical in class circularity checking for cases
224 // where classloading is delegated to different threads and the
225 // classloader lock is released.
226 // Take the case: Base->Super->Base
227 // 1. If thread T1 tries to do a defineClass of class Base
228 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
229 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
230 // so it tries to load Super
231 // 3. If we load the class internally, or user classloader uses same thread
232 // loadClassFromxxx or defineClass via parseClassFile Super ...
233 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
234 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
235 // 3.4 calls resolve_super_or_fail Base
236 // 3.5 finds T1,Base -> throws class circularity
237 //OR 4. If T2 tries to resolve Super via defineClass Super ...
238 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
239 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
240 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
241 // 4.4 finds T2, Super -> throws class circularity
242 // Must be called, even if superclass is null, since this is
243 // where the placeholder entry is created which claims this
244 // thread is loading this class/classloader.
245 klassOop SystemDictionary::resolve_super_or_fail(symbolHandle child_name,
246 symbolHandle class_name,
247 Handle class_loader,
248 Handle protection_domain,
249 bool is_superclass,
250 TRAPS) {
251
252 // Try to get one of the well-known klasses.
253 // They are trusted, and do not participate in circularities.
254 if (LinkWellKnownClasses) {
255 klassOop k = find_well_known_klass(class_name());
256 if (k != NULL) {
257 return k;
258 }
259 }
260
261 // Double-check, if child class is already loaded, just return super-class,interface
262 // Don't add a placedholder if already loaded, i.e. already in system dictionary
263 // Make sure there's a placeholder for the *child* before resolving.
264 // Used as a claim that this thread is currently loading superclass/classloader
265 // Used here for ClassCircularity checks and also for heap verification
266 // (every instanceKlass in the heap needs to be in the system dictionary
267 // or have a placeholder).
268 // Must check ClassCircularity before checking if super class is already loaded
269 //
270 // We might not already have a placeholder if this child_name was
271 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
272 // the name of the class might not be known until the stream is actually
273 // parsed.
274 // Bugs 4643874, 4715493
275 // compute_hash can have a safepoint
276
277 unsigned int d_hash = dictionary()->compute_hash(child_name, class_loader);
278 int d_index = dictionary()->hash_to_index(d_hash);
279 unsigned int p_hash = placeholders()->compute_hash(child_name, class_loader);
280 int p_index = placeholders()->hash_to_index(p_hash);
281 // can't throw error holding a lock
282 bool child_already_loaded = false;
283 bool throw_circularity_error = false;
284 {
285 MutexLocker mu(SystemDictionary_lock, THREAD);
286 klassOop childk = find_class(d_index, d_hash, child_name, class_loader);
287 klassOop quicksuperk;
288 // to support // loading: if child done loading, just return superclass
289 // if class_name, & class_loader don't match:
290 // if initial define, SD update will give LinkageError
291 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
292 // so we don't throw an exception here.
293 // see: nsk redefclass014 & java.lang.instrument Instrument032
294 if ((childk != NULL ) && (is_superclass) &&
295 ((quicksuperk = instanceKlass::cast(childk)->super()) != NULL) &&
296
297 ((Klass::cast(quicksuperk)->name() == class_name()) &&
298 (Klass::cast(quicksuperk)->class_loader() == class_loader()))) {
299 return quicksuperk;
300 } else {
301 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, class_loader);
302 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
303 throw_circularity_error = true;
304 }
305 }
306 if (!throw_circularity_error) {
307 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, class_loader, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
308 }
309 }
310 if (throw_circularity_error) {
311 ResourceMark rm(THREAD);
312 THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
313 }
314
315 // java.lang.Object should have been found above
316 assert(class_name() != NULL, "null super class for resolving");
317 // Resolve the super class or interface, check results on return
318 klassOop superk = NULL;
319 superk = SystemDictionary::resolve_or_null(class_name,
320 class_loader,
321 protection_domain,
322 THREAD);
323
324 KlassHandle superk_h(THREAD, superk);
325
326 // Note: clean up of placeholders currently in callers of
327 // resolve_super_or_fail - either at update_dictionary time
328 // or on error
329 {
330 MutexLocker mu(SystemDictionary_lock, THREAD);
331 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, class_loader);
332 if (probe != NULL) {
333 probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER);
334 }
335 }
336 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
337 // can null superk
338 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));
339 }
340
341 return superk_h();
342 }
343
344 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
345 Handle class_loader,
346 Handle protection_domain,
347 TRAPS) {
348 if(!has_checkPackageAccess()) return;
349
350 // Now we have to call back to java to check if the initating class has access
351 JavaValue result(T_VOID);
352 if (TraceProtectionDomainVerification) {
353 // Print out trace information
354 tty->print_cr("Checking package access");
355 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
356 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
357 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
358 }
359
360 assert(class_loader() != NULL, "should not have non-null protection domain for null classloader");
361
362 KlassHandle system_loader(THREAD, SystemDictionary::classloader_klass());
363 JavaCalls::call_special(&result,
364 class_loader,
365 system_loader,
366 vmSymbolHandles::checkPackageAccess_name(),
367 vmSymbolHandles::class_protectiondomain_signature(),
368 Handle(THREAD, klass->java_mirror()),
369 protection_domain,
370 THREAD);
371
372 if (TraceProtectionDomainVerification) {
373 if (HAS_PENDING_EXCEPTION) {
374 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
375 } else {
376 tty->print_cr(" -> granted");
377 }
378 tty->cr();
379 }
380
381 if (HAS_PENDING_EXCEPTION) return;
382
383 // If no exception has been thrown, we have validated the protection domain
384 // Insert the protection domain of the initiating class into the set.
385 {
386 // We recalculate the entry here -- we've called out to java since
387 // the last time it was calculated.
388 symbolHandle kn(THREAD, klass->name());
389 unsigned int d_hash = dictionary()->compute_hash(kn, class_loader);
390 int d_index = dictionary()->hash_to_index(d_hash);
391
392 MutexLocker mu(SystemDictionary_lock, THREAD);
393 {
394 // Note that we have an entry, and entries can be deleted only during GC,
395 // so we cannot allow GC to occur while we're holding this entry.
396
397 // We're using a No_Safepoint_Verifier to catch any place where we
398 // might potentially do a GC at all.
399 // SystemDictionary::do_unloading() asserts that classes are only
400 // unloaded at a safepoint.
401 No_Safepoint_Verifier nosafepoint;
402 dictionary()->add_protection_domain(d_index, d_hash, klass, class_loader,
403 protection_domain, THREAD);
404 }
405 }
406 }
407
408 // We only get here if this thread finds that another thread
409 // has already claimed the placeholder token for the current operation,
410 // but that other thread either never owned or gave up the
411 // object lock
412 // Waits on SystemDictionary_lock to indicate placeholder table updated
413 // On return, caller must recheck placeholder table state
414 //
415 // We only get here if
416 // 1) custom classLoader, i.e. not bootstrap classloader
417 // 2) UnsyncloadClass not set
418 // 3) custom classLoader has broken the class loader objectLock
419 // so another thread got here in parallel
420 //
421 // lockObject must be held.
422 // Complicated dance due to lock ordering:
423 // Must first release the classloader object lock to
424 // allow initial definer to complete the class definition
425 // and to avoid deadlock
426 // Reclaim classloader lock object with same original recursion count
427 // Must release SystemDictionary_lock after notify, since
428 // class loader lock must be claimed before SystemDictionary_lock
429 // to prevent deadlocks
430 //
431 // The notify allows applications that did an untimed wait() on
432 // the classloader object lock to not hang.
433 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
434 assert_lock_strong(SystemDictionary_lock);
435
436 bool calledholdinglock
437 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
438 assert(calledholdinglock,"must hold lock for notify");
439 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
440 ObjectSynchronizer::notifyall(lockObject, THREAD);
441 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
442 SystemDictionary_lock->wait();
443 SystemDictionary_lock->unlock();
444 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
445 SystemDictionary_lock->lock();
446 }
447
448 // If the class in is in the placeholder table, class loading is in progress
449 // For cases where the application changes threads to load classes, it
450 // is critical to ClassCircularity detection that we try loading
451 // the superclass on the same thread internally, so we do parallel
452 // super class loading here.
453 // This also is critical in cases where the original thread gets stalled
454 // even in non-circularity situations.
455 // Note: only one thread can define the class, but multiple can resolve
456 // Note: must call resolve_super_or_fail even if null super -
457 // to force placeholder entry creation for this class for circularity detection
458 // Caller must check for pending exception
459 // Returns non-null klassOop if other thread has completed load
460 // and we are done,
461 // If return null klassOop and no pending exception, the caller must load the class
462 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
463 symbolHandle name, symbolHandle superclassname, Handle class_loader,
464 Handle protection_domain, Handle lockObject, TRAPS) {
465
466 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
467 unsigned int d_hash = dictionary()->compute_hash(name, class_loader);
468 int d_index = dictionary()->hash_to_index(d_hash);
469 unsigned int p_hash = placeholders()->compute_hash(name, class_loader);
470 int p_index = placeholders()->hash_to_index(p_hash);
471
472 // superk is not used, resolve_super called for circularity check only
473 // This code is reached in two situations. One if this thread
474 // is loading the same class twice (e.g. ClassCircularity, or
475 // java.lang.instrument).
476 // The second is if another thread started the resolve_super first
477 // and has not yet finished.
478 // In both cases the original caller will clean up the placeholder
479 // entry on error.
480 klassOop superk = SystemDictionary::resolve_super_or_fail(name,
481 superclassname,
482 class_loader,
483 protection_domain,
484 true,
485 CHECK_(nh));
486 // We don't redefine the class, so we just need to clean up if there
487 // was not an error (don't want to modify any system dictionary
488 // data structures).
489 {
490 MutexLocker mu(SystemDictionary_lock, THREAD);
491 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
492 SystemDictionary_lock->notify_all();
493 }
494
495 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
496 // Serial class loaders and bootstrap classloader do wait for superclass loads
497 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
498 MutexLocker mu(SystemDictionary_lock, THREAD);
499 // Check if classloading completed while we were loading superclass or waiting
500 klassOop check = find_class(d_index, d_hash, name, class_loader);
501 if (check != NULL) {
502 // Klass is already loaded, so just return it
503 return(instanceKlassHandle(THREAD, check));
504 } else {
505 return nh;
506 }
507 }
508
509 // must loop to both handle other placeholder updates
510 // and spurious notifications
511 bool super_load_in_progress = true;
512 PlaceholderEntry* placeholder;
513 while (super_load_in_progress) {
514 MutexLocker mu(SystemDictionary_lock, THREAD);
515 // Check if classloading completed while we were loading superclass or waiting
516 klassOop check = find_class(d_index, d_hash, name, class_loader);
517 if (check != NULL) {
518 // Klass is already loaded, so just return it
519 return(instanceKlassHandle(THREAD, check));
520 } else {
521 placeholder = placeholders()->get_entry(p_index, p_hash, name, class_loader);
522 if (placeholder && placeholder->super_load_in_progress() ){
523 // Before UnsyncloadClass:
524 // We only get here if the application has released the
525 // classloader lock when another thread was in the middle of loading a
526 // superclass/superinterface for this class, and now
527 // this thread is also trying to load this class.
528 // To minimize surprises, the first thread that started to
529 // load a class should be the one to complete the loading
530 // with the classfile it initially expected.
531 // This logic has the current thread wait once it has done
532 // all the superclass/superinterface loading it can, until
533 // the original thread completes the class loading or fails
534 // If it completes we will use the resulting instanceKlass
535 // which we will find below in the systemDictionary.
536 // We also get here for parallel bootstrap classloader
537 if (class_loader.is_null()) {
538 SystemDictionary_lock->wait();
539 } else {
540 double_lock_wait(lockObject, THREAD);
541 }
542 } else {
543 // If not in SD and not in PH, other thread's load must have failed
544 super_load_in_progress = false;
545 }
546 }
547 }
548 return (nh);
549 }
550
551
552 klassOop SystemDictionary::resolve_instance_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS) {
553 assert(class_name.not_null() && !FieldType::is_array(class_name()), "invalid class name");
554 // First check to see if we should remove wrapping L and ;
555 symbolHandle name;
556 if (FieldType::is_obj(class_name())) {
557 ResourceMark rm(THREAD);
558 // Ignore wrapping L and ;.
559 name = oopFactory::new_symbol_handle(class_name()->as_C_string() + 1, class_name()->utf8_length() - 2, CHECK_NULL);
560 } else {
561 name = class_name;
562 }
563
564 // UseNewReflection
565 // Fix for 4474172; see evaluation for more details
566 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
567
568 // Do lookup to see if class already exist and the protection domain
569 // has the right access
570 unsigned int d_hash = dictionary()->compute_hash(name, class_loader);
571 int d_index = dictionary()->hash_to_index(d_hash);
572 klassOop probe = dictionary()->find(d_index, d_hash, name, class_loader,
573 protection_domain, THREAD);
574 if (probe != NULL) return probe;
575
576
577 // Non-bootstrap class loaders will call out to class loader and
578 // define via jvm/jni_DefineClass which will acquire the
579 // class loader object lock to protect against multiple threads
580 // defining the class in parallel by accident.
581 // This lock must be acquired here so the waiter will find
582 // any successful result in the SystemDictionary and not attempt
583 // the define
584 // ParallelCapable Classloaders and the bootstrap classloader,
585 // or all classloaders with UnsyncloadClass do not acquire lock here
586 bool DoObjectLock = true;
587 if (is_parallelCapable(class_loader)) {
588 DoObjectLock = false;
589 }
590
591 unsigned int p_hash = placeholders()->compute_hash(name, class_loader);
592 int p_index = placeholders()->hash_to_index(p_hash);
593
594 // Class is not in SystemDictionary so we have to do loading.
595 // Make sure we are synchronized on the class loader before we proceed
596 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
597 check_loader_lock_contention(lockObject, THREAD);
598 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
599
600 // Check again (after locking) if class already exist in SystemDictionary
601 bool class_has_been_loaded = false;
602 bool super_load_in_progress = false;
603 bool havesupername = false;
604 instanceKlassHandle k;
605 PlaceholderEntry* placeholder;
606 symbolHandle superclassname;
607
608 {
609 MutexLocker mu(SystemDictionary_lock, THREAD);
610 klassOop check = find_class(d_index, d_hash, name, class_loader);
611 if (check != NULL) {
612 // Klass is already loaded, so just return it
613 class_has_been_loaded = true;
614 k = instanceKlassHandle(THREAD, check);
615 } else {
616 placeholder = placeholders()->get_entry(p_index, p_hash, name, class_loader);
617 if (placeholder && placeholder->super_load_in_progress()) {
618 super_load_in_progress = true;
619 if (placeholder->havesupername() == true) {
620 superclassname = symbolHandle(THREAD, placeholder->supername());
621 havesupername = true;
622 }
623 }
624 }
625 }
626
627 // If the class in is in the placeholder table, class loading is in progress
628 if (super_load_in_progress && havesupername==true) {
629 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
630 class_loader, protection_domain, lockObject, THREAD);
631 if (HAS_PENDING_EXCEPTION) {
632 return NULL;
633 }
634 if (!k.is_null()) {
635 class_has_been_loaded = true;
636 }
637 }
638
639 if (!class_has_been_loaded) {
640
641 // add placeholder entry to record loading instance class
642 // Five cases:
643 // All cases need to prevent modifying bootclasssearchpath
644 // in parallel with a classload of same classname
645 // Redefineclasses uses existence of the placeholder for the duration
646 // of the class load to prevent concurrent redefinition of not completely
647 // defined classes.
648 // case 1. traditional classloaders that rely on the classloader object lock
649 // - no other need for LOAD_INSTANCE
650 // case 2. traditional classloaders that break the classloader object lock
651 // as a deadlock workaround. Detection of this case requires that
652 // this check is done while holding the classloader object lock,
653 // and that lock is still held when calling classloader's loadClass.
654 // For these classloaders, we ensure that the first requestor
655 // completes the load and other requestors wait for completion.
656 // case 3. UnsyncloadClass - don't use objectLocker
657 // With this flag, we allow parallel classloading of a
658 // class/classloader pair
659 // case4. Bootstrap classloader - don't own objectLocker
660 // This classloader supports parallelism at the classloader level,
661 // but only allows a single load of a class/classloader pair.
662 // No performance benefit and no deadlock issues.
663 // case 5. parallelCapable user level classloaders - without objectLocker
664 // Allow parallel classloading of a class/classloader pair
665 symbolHandle nullsymbolHandle;
666 bool throw_circularity_error = false;
667 {
668 MutexLocker mu(SystemDictionary_lock, THREAD);
669 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
670 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
671 if (oldprobe) {
672 // only need check_seen_thread once, not on each loop
673 // 6341374 java/lang/Instrument with -Xcomp
674 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
675 throw_circularity_error = true;
676 } else {
677 // case 1: traditional: should never see load_in_progress.
678 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
679
680 // case 4: bootstrap classloader: prevent futile classloading,
681 // wait on first requestor
682 if (class_loader.is_null()) {
683 SystemDictionary_lock->wait();
684 } else {
685 // case 2: traditional with broken classloader lock. wait on first
686 // requestor.
687 double_lock_wait(lockObject, THREAD);
688 }
689 // Check if classloading completed while we were waiting
690 klassOop check = find_class(d_index, d_hash, name, class_loader);
691 if (check != NULL) {
692 // Klass is already loaded, so just return it
693 k = instanceKlassHandle(THREAD, check);
694 class_has_been_loaded = true;
695 }
696 // check if other thread failed to load and cleaned up
697 oldprobe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
698 }
699 }
700 }
701 }
702 // All cases: add LOAD_INSTANCE
703 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
704 // LOAD_INSTANCE in parallel
705 // add placeholder entry even if error - callers will remove on error
706 if (!throw_circularity_error && !class_has_been_loaded) {
707 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, class_loader, PlaceholderTable::LOAD_INSTANCE, nullsymbolHandle, THREAD);
708 // For class loaders that do not acquire the classloader object lock,
709 // if they did not catch another thread holding LOAD_INSTANCE,
710 // need a check analogous to the acquire ObjectLocker/find_class
711 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
712 // one final check if the load has already completed
713 // class loaders holding the ObjectLock shouldn't find the class here
714 klassOop check = find_class(d_index, d_hash, name, class_loader);
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 newprobe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);
720 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
721 SystemDictionary_lock->notify_all();
722 }
723 }
724 }
725 // must throw error outside of owning lock
726 if (throw_circularity_error) {
727 ResourceMark rm(THREAD);
728 THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
729 }
730
731 if (!class_has_been_loaded) {
732
733 // Do actual loading
734 k = load_instance_class(name, class_loader, THREAD);
735
736 // For UnsyncloadClass only
737 // If they got a linkageError, check if a parallel class load succeeded.
738 // If it did, then for bytecode resolution the specification requires
739 // that we return the same result we did for the other thread, i.e. the
740 // successfully loaded instanceKlass
741 // Should not get here for classloaders that support parallelism
742 // with the new cleaner mechanism, even with AllowParallelDefineClass
743 // Bootstrap goes through here to allow for an extra guarantee check
744 if (UnsyncloadClass || (class_loader.is_null())) {
745 if (k.is_null() && HAS_PENDING_EXCEPTION
746 && PENDING_EXCEPTION->is_a(SystemDictionary::linkageError_klass())) {
747 MutexLocker mu(SystemDictionary_lock, THREAD);
748 klassOop check = find_class(d_index, d_hash, name, class_loader);
749 if (check != NULL) {
750 // Klass is already loaded, so just use it
751 k = instanceKlassHandle(THREAD, check);
752 CLEAR_PENDING_EXCEPTION;
753 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
754 }
755 }
756 }
757
758 // clean up placeholder entries for success or error
759 // This cleans up LOAD_INSTANCE entries
760 // It also cleans up LOAD_SUPER entries on errors from
761 // calling load_instance_class
762 {
763 MutexLocker mu(SystemDictionary_lock, THREAD);
764 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
765 if (probe != NULL) {
766 probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);
767 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
768 SystemDictionary_lock->notify_all();
769 }
770 }
771
772 // If everything was OK (no exceptions, no null return value), and
773 // class_loader is NOT the defining loader, do a little more bookkeeping.
774 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
775 k->class_loader() != class_loader()) {
776
777 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
778
779 // Need to check for a PENDING_EXCEPTION again; check_constraints
780 // can throw and doesn't use the CHECK macro.
781 if (!HAS_PENDING_EXCEPTION) {
782 { // Grabbing the Compile_lock prevents systemDictionary updates
783 // during compilations.
784 MutexLocker mu(Compile_lock, THREAD);
785 update_dictionary(d_index, d_hash, p_index, p_hash,
786 k, class_loader, THREAD);
787 }
788 if (JvmtiExport::should_post_class_load()) {
789 Thread *thread = THREAD;
790 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
791 JvmtiExport::post_class_load((JavaThread *) thread, k());
792 }
793 }
794 }
795 if (HAS_PENDING_EXCEPTION || k.is_null()) {
796 // On error, clean up placeholders
797 {
798 MutexLocker mu(SystemDictionary_lock, THREAD);
799 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
800 SystemDictionary_lock->notify_all();
801 }
802 return NULL;
803 }
804 }
805 }
806
807 #ifdef ASSERT
808 {
809 Handle loader (THREAD, k->class_loader());
810 MutexLocker mu(SystemDictionary_lock, THREAD);
811 oop kk = find_class_or_placeholder(name, loader);
812 assert(kk == k(), "should be present in dictionary");
813 }
814 #endif
815
816 // return if the protection domain in NULL
817 if (protection_domain() == NULL) return k();
818
819 // Check the protection domain has the right access
820 {
821 MutexLocker mu(SystemDictionary_lock, THREAD);
822 // Note that we have an entry, and entries can be deleted only during GC,
823 // so we cannot allow GC to occur while we're holding this entry.
824 // We're using a No_Safepoint_Verifier to catch any place where we
825 // might potentially do a GC at all.
826 // SystemDictionary::do_unloading() asserts that classes are only
827 // unloaded at a safepoint.
828 No_Safepoint_Verifier nosafepoint;
829 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
830 class_loader,
831 protection_domain)) {
832 return k();
833 }
834 }
835
836 // Verify protection domain. If it fails an exception is thrown
837 validate_protection_domain(k, class_loader, protection_domain, CHECK_(klassOop(NULL)));
838
839 return k();
840 }
841
842
843 // This routine does not lock the system dictionary.
844 //
845 // Since readers don't hold a lock, we must make sure that system
846 // dictionary entries are only removed at a safepoint (when only one
847 // thread is running), and are added to in a safe way (all links must
848 // be updated in an MT-safe manner).
849 //
850 // Callers should be aware that an entry could be added just after
851 // _dictionary->bucket(index) is read here, so the caller will not see
852 // the new entry.
853
854 klassOop SystemDictionary::find(symbolHandle class_name,
855 Handle class_loader,
856 Handle protection_domain,
857 TRAPS) {
858
859 // UseNewReflection
860 // The result of this call should be consistent with the result
861 // of the call to resolve_instance_class_or_null().
862 // See evaluation 6790209 and 4474172 for more details.
863 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
864
865 unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);
866 int d_index = dictionary()->hash_to_index(d_hash);
867
868 {
869 // Note that we have an entry, and entries can be deleted only during GC,
870 // so we cannot allow GC to occur while we're holding this entry.
871 // We're using a No_Safepoint_Verifier to catch any place where we
872 // might potentially do a GC at all.
873 // SystemDictionary::do_unloading() asserts that classes are only
874 // unloaded at a safepoint.
875 No_Safepoint_Verifier nosafepoint;
876 return dictionary()->find(d_index, d_hash, class_name, class_loader,
877 protection_domain, THREAD);
878 }
879 }
880
881
882 // Look for a loaded instance or array klass by name. Do not do any loading.
883 // return NULL in case of error.
884 klassOop SystemDictionary::find_instance_or_array_klass(symbolHandle class_name,
885 Handle class_loader,
886 Handle protection_domain,
887 TRAPS) {
888 klassOop k = NULL;
889 assert(class_name() != NULL, "class name must be non NULL");
890
891 // Try to get one of the well-known klasses.
892 if (LinkWellKnownClasses) {
893 k = find_well_known_klass(class_name());
894 if (k != NULL) {
895 return k;
896 }
897 }
898
899 if (FieldType::is_array(class_name())) {
900 // The name refers to an array. Parse the name.
901 jint dimension;
902 symbolOop object_key;
903
904 // dimension and object_key are assigned as a side-effect of this call
905 BasicType t = FieldType::get_array_info(class_name(), &dimension,
906 &object_key, CHECK_(NULL));
907 if (t != T_OBJECT) {
908 k = Universe::typeArrayKlassObj(t);
909 } else {
910 symbolHandle h_key(THREAD, object_key);
911 k = SystemDictionary::find(h_key, class_loader, protection_domain, THREAD);
912 }
913 if (k != NULL) {
914 k = Klass::cast(k)->array_klass_or_null(dimension);
915 }
916 } else {
917 k = find(class_name, class_loader, protection_domain, THREAD);
918 }
919 return k;
920 }
921
922 // Quick range check for names of well-known classes:
923 static symbolOop wk_klass_name_limits[2] = {NULL, NULL};
924
925 #ifndef PRODUCT
926 static int find_wkk_calls, find_wkk_probes, find_wkk_wins;
927 // counts for "hello world": 3983, 1616, 1075
928 // => 60% hit after limit guard, 25% total win rate
929 #endif
930
931 klassOop SystemDictionary::find_well_known_klass(symbolOop class_name) {
932 // A bounds-check on class_name will quickly get a negative result.
933 NOT_PRODUCT(find_wkk_calls++);
934 if (class_name >= wk_klass_name_limits[0] &&
935 class_name <= wk_klass_name_limits[1]) {
936 NOT_PRODUCT(find_wkk_probes++);
937 vmSymbols::SID sid = vmSymbols::find_sid(class_name);
938 if (sid != vmSymbols::NO_SID) {
939 klassOop k = NULL;
940 switch (sid) {
941 #define WK_KLASS_CASE(name, symbol, ignore_option) \
942 case vmSymbols::VM_SYMBOL_ENUM_NAME(symbol): \
943 k = WK_KLASS(name); break;
944 WK_KLASSES_DO(WK_KLASS_CASE)
945 #undef WK_KLASS_CASE
946 }
947 NOT_PRODUCT(if (k != NULL) find_wkk_wins++);
948 return k;
949 }
950 }
951 return NULL;
952 }
953
954 // Note: this method is much like resolve_from_stream, but
955 // updates no supplemental data structures.
956 // TODO consolidate the two methods with a helper routine?
957 klassOop SystemDictionary::parse_stream(symbolHandle class_name,
958 Handle class_loader,
959 Handle protection_domain,
960 ClassFileStream* st,
961 KlassHandle host_klass,
962 GrowableArray<Handle>* cp_patches,
963 TRAPS) {
964 symbolHandle parsed_name;
965
966 // Parse the stream. Note that we do this even though this klass might
967 // already be present in the SystemDictionary, otherwise we would not
968 // throw potential ClassFormatErrors.
969 //
970 // Note: "name" is updated.
971 // Further note: a placeholder will be added for this class when
972 // super classes are loaded (resolve_super_or_fail). We expect this
973 // to be called for all classes but java.lang.Object; and we preload
974 // java.lang.Object through resolve_or_fail, not this path.
975
976 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
977 class_loader,
978 protection_domain,
979 host_klass,
980 cp_patches,
981 parsed_name,
982 true,
983 THREAD);
984
985
986 // We don't redefine the class, so we just need to clean up whether there
987 // was an error or not (don't want to modify any system dictionary
988 // data structures).
989 // Parsed name could be null if we threw an error before we got far
990 // enough along to parse it -- in that case, there is nothing to clean up.
991 if (!parsed_name.is_null()) {
992 unsigned int p_hash = placeholders()->compute_hash(parsed_name,
993 class_loader);
994 int p_index = placeholders()->hash_to_index(p_hash);
995 {
996 MutexLocker mu(SystemDictionary_lock, THREAD);
997 placeholders()->find_and_remove(p_index, p_hash, parsed_name, class_loader, THREAD);
998 SystemDictionary_lock->notify_all();
999 }
1000 }
1001
1002 if (host_klass.not_null() && k.not_null()) {
1003 assert(AnonymousClasses, "");
1004 // If it's anonymous, initialize it now, since nobody else will.
1005 k->set_host_klass(host_klass());
1006
1007 {
1008 MutexLocker mu_r(Compile_lock, THREAD);
1009
1010 // Add to class hierarchy, initialize vtables, and do possible
1011 // deoptimizations.
1012 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1013
1014 // But, do not add to system dictionary.
1015 }
1016
1017 k->eager_initialize(THREAD);
1018
1019 // notify jvmti
1020 if (JvmtiExport::should_post_class_load()) {
1021 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1022 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1023 }
1024 }
1025
1026 return k();
1027 }
1028
1029 // Add a klass to the system from a stream (called by jni_DefineClass and
1030 // JVM_DefineClass).
1031 // Note: class_name can be NULL. In that case we do not know the name of
1032 // the class until we have parsed the stream.
1033
1034 klassOop SystemDictionary::resolve_from_stream(symbolHandle class_name,
1035 Handle class_loader,
1036 Handle protection_domain,
1037 ClassFileStream* st,
1038 bool verify,
1039 TRAPS) {
1040
1041 // Classloaders that support parallelism, e.g. bootstrap classloader,
1042 // or all classloaders with UnsyncloadClass do not acquire lock here
1043 bool DoObjectLock = true;
1044 if (is_parallelCapable(class_loader)) {
1045 DoObjectLock = false;
1046 }
1047
1048 // Make sure we are synchronized on the class loader before we proceed
1049 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1050 check_loader_lock_contention(lockObject, THREAD);
1051 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1052
1053 symbolHandle parsed_name;
1054
1055 // Parse the stream. Note that we do this even though this klass might
1056 // already be present in the SystemDictionary, otherwise we would not
1057 // throw potential ClassFormatErrors.
1058 //
1059 // Note: "name" is updated.
1060 // Further note: a placeholder will be added for this class when
1061 // super classes are loaded (resolve_super_or_fail). We expect this
1062 // to be called for all classes but java.lang.Object; and we preload
1063 // java.lang.Object through resolve_or_fail, not this path.
1064
1065 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1066 class_loader,
1067 protection_domain,
1068 parsed_name,
1069 verify,
1070 THREAD);
1071
1072 const char* pkg = "java/";
1073 if (!HAS_PENDING_EXCEPTION &&
1074 !class_loader.is_null() &&
1075 !parsed_name.is_null() &&
1076 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1077 // It is illegal to define classes in the "java." package from
1078 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1079 ResourceMark rm(THREAD);
1080 char* name = parsed_name->as_C_string();
1081 char* index = strrchr(name, '/');
1082 *index = '\0'; // chop to just the package name
1083 while ((index = strchr(name, '/')) != NULL) {
1084 *index = '.'; // replace '/' with '.' in package name
1085 }
1086 const char* fmt = "Prohibited package name: %s";
1087 size_t len = strlen(fmt) + strlen(name);
1088 char* message = NEW_RESOURCE_ARRAY(char, len);
1089 jio_snprintf(message, len, fmt, name);
1090 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1091 vmSymbols::java_lang_SecurityException(), message);
1092 }
1093
1094 if (!HAS_PENDING_EXCEPTION) {
1095 assert(!parsed_name.is_null(), "Sanity");
1096 assert(class_name.is_null() || class_name() == parsed_name(),
1097 "name mismatch");
1098 // Verification prevents us from creating names with dots in them, this
1099 // asserts that that's the case.
1100 assert(is_internal_format(parsed_name),
1101 "external class name format used internally");
1102
1103 // Add class just loaded
1104 // If a class loader supports parallel classloading handle parallel define requests
1105 // find_or_define_instance_class may return a different instanceKlass
1106 if (is_parallelCapable(class_loader)) {
1107 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1108 } else {
1109 define_instance_class(k, THREAD);
1110 }
1111 }
1112
1113 // If parsing the class file or define_instance_class failed, we
1114 // need to remove the placeholder added on our behalf. But we
1115 // must make sure parsed_name is valid first (it won't be if we had
1116 // a format error before the class was parsed far enough to
1117 // find the name).
1118 if (HAS_PENDING_EXCEPTION && !parsed_name.is_null()) {
1119 unsigned int p_hash = placeholders()->compute_hash(parsed_name,
1120 class_loader);
1121 int p_index = placeholders()->hash_to_index(p_hash);
1122 {
1123 MutexLocker mu(SystemDictionary_lock, THREAD);
1124 placeholders()->find_and_remove(p_index, p_hash, parsed_name, class_loader, THREAD);
1125 SystemDictionary_lock->notify_all();
1126 }
1127 return NULL;
1128 }
1129
1130 // Make sure that we didn't leave a place holder in the
1131 // SystemDictionary; this is only done on success
1132 debug_only( {
1133 if (!HAS_PENDING_EXCEPTION) {
1134 assert(!parsed_name.is_null(), "parsed_name is still null?");
1135 symbolHandle h_name (THREAD, k->name());
1136 Handle h_loader (THREAD, k->class_loader());
1137
1138 MutexLocker mu(SystemDictionary_lock, THREAD);
1139
1140 oop check = find_class_or_placeholder(parsed_name, class_loader);
1141 assert(check == k(), "should be present in the dictionary");
1142
1143 oop check2 = find_class_or_placeholder(h_name, h_loader);
1144 assert(check == check2, "name inconsistancy in SystemDictionary");
1145 }
1146 } );
1147
1148 return k();
1149 }
1150
1151
1152 void SystemDictionary::set_shared_dictionary(HashtableBucket* t, int length,
1153 int number_of_entries) {
1154 assert(length == _nof_buckets * sizeof(HashtableBucket),
1155 "bad shared dictionary size.");
1156 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1157 }
1158
1159
1160 // If there is a shared dictionary, then find the entry for the
1161 // given shared system class, if any.
1162
1163 klassOop SystemDictionary::find_shared_class(symbolHandle class_name) {
1164 if (shared_dictionary() != NULL) {
1165 unsigned int d_hash = dictionary()->compute_hash(class_name, Handle());
1166 int d_index = dictionary()->hash_to_index(d_hash);
1167 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1168 } else {
1169 return NULL;
1170 }
1171 }
1172
1173
1174 // Load a class from the shared spaces (found through the shared system
1175 // dictionary). Force the superclass and all interfaces to be loaded.
1176 // Update the class definition to include sibling classes and no
1177 // subclasses (yet). [Classes in the shared space are not part of the
1178 // object hierarchy until loaded.]
1179
1180 instanceKlassHandle SystemDictionary::load_shared_class(
1181 symbolHandle class_name, Handle class_loader, TRAPS) {
1182 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1183 return load_shared_class(ik, class_loader, THREAD);
1184 }
1185
1186 // Note well! Changes to this method may affect oop access order
1187 // in the shared archive. Please take care to not make changes that
1188 // adversely affect cold start time by changing the oop access order
1189 // that is specified in dump.cpp MarkAndMoveOrderedReadOnly and
1190 // MarkAndMoveOrderedReadWrite closures.
1191 instanceKlassHandle SystemDictionary::load_shared_class(
1192 instanceKlassHandle ik, Handle class_loader, TRAPS) {
1193 assert(class_loader.is_null(), "non-null classloader for shared class?");
1194 if (ik.not_null()) {
1195 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1196 symbolHandle class_name(THREAD, ik->name());
1197
1198 // Found the class, now load the superclass and interfaces. If they
1199 // are shared, add them to the main system dictionary and reset
1200 // their hierarchy references (supers, subs, and interfaces).
1201
1202 if (ik->super() != NULL) {
1203 symbolHandle cn(THREAD, ik->super()->klass_part()->name());
1204 resolve_super_or_fail(class_name, cn,
1205 class_loader, Handle(), true, CHECK_(nh));
1206 }
1207
1208 objArrayHandle interfaces (THREAD, ik->local_interfaces());
1209 int num_interfaces = interfaces->length();
1210 for (int index = 0; index < num_interfaces; index++) {
1211 klassOop k = klassOop(interfaces->obj_at(index));
1212
1213 // Note: can not use instanceKlass::cast here because
1214 // interfaces' instanceKlass's C++ vtbls haven't been
1215 // reinitialized yet (they will be once the interface classes
1216 // are loaded)
1217 symbolHandle name (THREAD, k->klass_part()->name());
1218 resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(nh));
1219 }
1220
1221 // Adjust methods to recover missing data. They need addresses for
1222 // interpreter entry points and their default native method address
1223 // must be reset.
1224
1225 // Updating methods must be done under a lock so multiple
1226 // threads don't update these in parallel
1227 // Shared classes are all currently loaded by the bootstrap
1228 // classloader, so this will never cause a deadlock on
1229 // a custom class loader lock.
1230
1231 {
1232 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1233 check_loader_lock_contention(lockObject, THREAD);
1234 ObjectLocker ol(lockObject, THREAD, true);
1235
1236 objArrayHandle methods (THREAD, ik->methods());
1237 int num_methods = methods->length();
1238 for (int index2 = 0; index2 < num_methods; ++index2) {
1239 methodHandle m(THREAD, methodOop(methods->obj_at(index2)));
1240 m()->link_method(m, CHECK_(nh));
1241 }
1242 }
1243
1244 if (TraceClassLoading) {
1245 ResourceMark rm;
1246 tty->print("[Loaded %s", ik->external_name());
1247 tty->print(" from shared objects file");
1248 tty->print_cr("]");
1249 }
1250 // notify a class loaded from shared object
1251 ClassLoadingService::notify_class_loaded(instanceKlass::cast(ik()),
1252 true /* shared class */);
1253 }
1254 return ik;
1255 }
1256
1257 #ifdef KERNEL
1258 // Some classes on the bootstrap class path haven't been installed on the
1259 // system yet. Call the DownloadManager method to make them appear in the
1260 // bootstrap class path and try again to load the named class.
1261 // Note that with delegation class loaders all classes in another loader will
1262 // first try to call this so it'd better be fast!!
1263 static instanceKlassHandle download_and_retry_class_load(
1264 symbolHandle class_name,
1265 TRAPS) {
1266
1267 klassOop dlm = SystemDictionary::sun_jkernel_DownloadManager_klass();
1268 instanceKlassHandle nk;
1269
1270 // If download manager class isn't loaded just return.
1271 if (dlm == NULL) return nk;
1272
1273 { HandleMark hm(THREAD);
1274 ResourceMark rm(THREAD);
1275 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nk));
1276 Handle class_string = java_lang_String::externalize_classname(s, CHECK_(nk));
1277
1278 // return value
1279 JavaValue result(T_OBJECT);
1280
1281 // Call the DownloadManager. We assume that it has a lock because
1282 // multiple classes could be not found and downloaded at the same time.
1283 // class sun.misc.DownloadManager;
1284 // public static String getBootClassPathEntryForClass(String className);
1285 JavaCalls::call_static(&result,
1286 KlassHandle(THREAD, dlm),
1287 vmSymbolHandles::getBootClassPathEntryForClass_name(),
1288 vmSymbolHandles::string_string_signature(),
1289 class_string,
1290 CHECK_(nk));
1291
1292 // Get result.string and add to bootclasspath
1293 assert(result.get_type() == T_OBJECT, "just checking");
1294 oop obj = (oop) result.get_jobject();
1295 if (obj == NULL) { return nk; }
1296
1297 Handle h_obj(THREAD, obj);
1298 char* new_class_name = java_lang_String::as_platform_dependent_str(h_obj,
1299 CHECK_(nk));
1300
1301 // lock the loader
1302 // we use this lock because JVMTI does.
1303 Handle loader_lock(THREAD, SystemDictionary::system_loader_lock());
1304
1305 ObjectLocker ol(loader_lock, THREAD);
1306 // add the file to the bootclasspath
1307 ClassLoader::update_class_path_entry_list(new_class_name, true);
1308 } // end HandleMark
1309
1310 if (TraceClassLoading) {
1311 ClassLoader::print_bootclasspath();
1312 }
1313 return ClassLoader::load_classfile(class_name, CHECK_(nk));
1314 }
1315 #endif // KERNEL
1316
1317
1318 instanceKlassHandle SystemDictionary::load_instance_class(symbolHandle class_name, Handle class_loader, TRAPS) {
1319 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1320 if (class_loader.is_null()) {
1321
1322 // Search the shared system dictionary for classes preloaded into the
1323 // shared spaces.
1324 instanceKlassHandle k;
1325 {
1326 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1327 k = load_shared_class(class_name, class_loader, THREAD);
1328 }
1329
1330 if (k.is_null()) {
1331 // Use VM class loader
1332 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1333 k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1334 }
1335
1336 #ifdef KERNEL
1337 // If the VM class loader has failed to load the class, call the
1338 // DownloadManager class to make it magically appear on the classpath
1339 // and try again. This is only configured with the Kernel VM.
1340 if (k.is_null()) {
1341 k = download_and_retry_class_load(class_name, CHECK_(nh));
1342 }
1343 #endif // KERNEL
1344
1345 // find_or_define_instance_class may return a different instanceKlass
1346 if (!k.is_null()) {
1347 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1348 }
1349 return k;
1350 } else {
1351 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1352 ResourceMark rm(THREAD);
1353
1354 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1355 JavaThread* jt = (JavaThread*) THREAD;
1356
1357 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1358 ClassLoader::perf_app_classload_selftime(),
1359 ClassLoader::perf_app_classload_count(),
1360 jt->get_thread_stat()->perf_recursion_counts_addr(),
1361 jt->get_thread_stat()->perf_timers_addr(),
1362 PerfClassTraceTime::CLASS_LOAD);
1363
1364 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1365 // Translate to external class name format, i.e., convert '/' chars to '.'
1366 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1367
1368 JavaValue result(T_OBJECT);
1369
1370 KlassHandle spec_klass (THREAD, SystemDictionary::classloader_klass());
1371
1372 // Call public unsynchronized loadClass(String) directly for all class loaders
1373 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1374 // acquire a class-name based lock rather than the class loader object lock.
1375 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1376 // so the call to loadClassInternal() was not required.
1377 //
1378 // UnsyncloadClass flag means both call loadClass(String) and do
1379 // not acquire the class loader lock even for class loaders that are
1380 // not parallelCapable. This was a risky transitional
1381 // flag for diagnostic purposes only. It is risky to call
1382 // custom class loaders without synchronization.
1383 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1384 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1385 // Do NOT assume this will be supported in future releases.
1386 //
1387 // Added MustCallLoadClassInternal in case we discover in the field
1388 // a customer that counts on this call
1389 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1390 JavaCalls::call_special(&result,
1391 class_loader,
1392 spec_klass,
1393 vmSymbolHandles::loadClassInternal_name(),
1394 vmSymbolHandles::string_class_signature(),
1395 string,
1396 CHECK_(nh));
1397 } else {
1398 JavaCalls::call_virtual(&result,
1399 class_loader,
1400 spec_klass,
1401 vmSymbolHandles::loadClass_name(),
1402 vmSymbolHandles::string_class_signature(),
1403 string,
1404 CHECK_(nh));
1405 }
1406
1407 assert(result.get_type() == T_OBJECT, "just checking");
1408 oop obj = (oop) result.get_jobject();
1409
1410 // Primitive classes return null since forName() can not be
1411 // used to obtain any of the Class objects representing primitives or void
1412 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1413 instanceKlassHandle k =
1414 instanceKlassHandle(THREAD, java_lang_Class::as_klassOop(obj));
1415 // For user defined Java class loaders, check that the name returned is
1416 // the same as that requested. This check is done for the bootstrap
1417 // loader when parsing the class file.
1418 if (class_name() == k->name()) {
1419 return k;
1420 }
1421 }
1422 // Class is not found or has the wrong name, return NULL
1423 return nh;
1424 }
1425 }
1426
1427 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1428
1429 Handle class_loader_h(THREAD, k->class_loader());
1430
1431 // for bootstrap and other parallel classloaders don't acquire lock,
1432 // use placeholder token
1433 // If a parallelCapable class loader calls define_instance_class instead of
1434 // find_or_define_instance_class to get here, we have a timing
1435 // hole with systemDictionary updates and check_constraints
1436 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1437 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1438 compute_loader_lock_object(class_loader_h, THREAD)),
1439 "define called without lock");
1440 }
1441
1442 // Check class-loading constraints. Throw exception if violation is detected.
1443 // Grabs and releases SystemDictionary_lock
1444 // The check_constraints/find_class call and update_dictionary sequence
1445 // must be "atomic" for a specific class/classloader pair so we never
1446 // define two different instanceKlasses for that class/classloader pair.
1447 // Existing classloaders will call define_instance_class with the
1448 // classloader lock held
1449 // Parallel classloaders will call find_or_define_instance_class
1450 // which will require a token to perform the define class
1451 symbolHandle name_h(THREAD, k->name());
1452 unsigned int d_hash = dictionary()->compute_hash(name_h, class_loader_h);
1453 int d_index = dictionary()->hash_to_index(d_hash);
1454 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1455
1456 // Register class just loaded with class loader (placed in Vector)
1457 // Note we do this before updating the dictionary, as this can
1458 // fail with an OutOfMemoryError (if it does, we will *not* put this
1459 // class in the dictionary and will not update the class hierarchy).
1460 if (k->class_loader() != NULL) {
1461 methodHandle m(THREAD, Universe::loader_addClass_method());
1462 JavaValue result(T_VOID);
1463 JavaCallArguments args(class_loader_h);
1464 args.push_oop(Handle(THREAD, k->java_mirror()));
1465 JavaCalls::call(&result, m, &args, CHECK);
1466 }
1467
1468 // Add the new class. We need recompile lock during update of CHA.
1469 {
1470 unsigned int p_hash = placeholders()->compute_hash(name_h, class_loader_h);
1471 int p_index = placeholders()->hash_to_index(p_hash);
1472
1473 MutexLocker mu_r(Compile_lock, THREAD);
1474
1475 // Add to class hierarchy, initialize vtables, and do possible
1476 // deoptimizations.
1477 add_to_hierarchy(k, CHECK); // No exception, but can block
1478
1479 // Add to systemDictionary - so other classes can see it.
1480 // Grabs and releases SystemDictionary_lock
1481 update_dictionary(d_index, d_hash, p_index, p_hash,
1482 k, class_loader_h, THREAD);
1483 }
1484 k->eager_initialize(THREAD);
1485
1486 // notify jvmti
1487 if (JvmtiExport::should_post_class_load()) {
1488 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1489 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1490
1491 }
1492 }
1493
1494 // Support parallel classloading
1495 // All parallel class loaders, including bootstrap classloader
1496 // lock a placeholder entry for this class/class_loader pair
1497 // to allow parallel defines of different classes for this class loader
1498 // With AllowParallelDefine flag==true, in case they do not synchronize around
1499 // FindLoadedClass/DefineClass, calls, we check for parallel
1500 // loading for them, wait if a defineClass is in progress
1501 // and return the initial requestor's results
1502 // This flag does not apply to the bootstrap classloader.
1503 // With AllowParallelDefine flag==false, call through to define_instance_class
1504 // which will throw LinkageError: duplicate class definition.
1505 // False is the requested default.
1506 // For better performance, the class loaders should synchronize
1507 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1508 // potentially waste time reading and parsing the bytestream.
1509 // Note: VM callers should ensure consistency of k/class_name,class_loader
1510 instanceKlassHandle SystemDictionary::find_or_define_instance_class(symbolHandle class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1511
1512 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1513 symbolHandle name_h(THREAD, k->name()); // passed in class_name may be null
1514
1515 unsigned int d_hash = dictionary()->compute_hash(name_h, class_loader);
1516 int d_index = dictionary()->hash_to_index(d_hash);
1517
1518 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1519 unsigned int p_hash = placeholders()->compute_hash(name_h, class_loader);
1520 int p_index = placeholders()->hash_to_index(p_hash);
1521 PlaceholderEntry* probe;
1522
1523 {
1524 MutexLocker mu(SystemDictionary_lock, THREAD);
1525 // First check if class already defined
1526 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1527 klassOop check = find_class(d_index, d_hash, name_h, class_loader);
1528 if (check != NULL) {
1529 return(instanceKlassHandle(THREAD, check));
1530 }
1531 }
1532
1533 // Acquire define token for this class/classloader
1534 symbolHandle nullsymbolHandle;
1535 probe = placeholders()->find_and_add(p_index, p_hash, name_h, class_loader, PlaceholderTable::DEFINE_CLASS, nullsymbolHandle, THREAD);
1536 // Wait if another thread defining in parallel
1537 // All threads wait - even those that will throw duplicate class: otherwise
1538 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1539 // if other thread has not finished updating dictionary
1540 while (probe->definer() != NULL) {
1541 SystemDictionary_lock->wait();
1542 }
1543 // Only special cases allow parallel defines and can use other thread's results
1544 // Other cases fall through, and may run into duplicate defines
1545 // caught by finding an entry in the SystemDictionary
1546 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instanceKlass() != NULL)) {
1547 probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);
1548 placeholders()->find_and_remove(p_index, p_hash, name_h, class_loader, THREAD);
1549 SystemDictionary_lock->notify_all();
1550 #ifdef ASSERT
1551 klassOop check = find_class(d_index, d_hash, name_h, class_loader);
1552 assert(check != NULL, "definer missed recording success");
1553 #endif
1554 return(instanceKlassHandle(THREAD, probe->instanceKlass()));
1555 } else {
1556 // This thread will define the class (even if earlier thread tried and had an error)
1557 probe->set_definer(THREAD);
1558 }
1559 }
1560
1561 define_instance_class(k, THREAD);
1562
1563 Handle linkage_exception = Handle(); // null handle
1564
1565 // definer must notify any waiting threads
1566 {
1567 MutexLocker mu(SystemDictionary_lock, THREAD);
1568 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, class_loader);
1569 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1570 if (probe != NULL) {
1571 if (HAS_PENDING_EXCEPTION) {
1572 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1573 CLEAR_PENDING_EXCEPTION;
1574 } else {
1575 probe->set_instanceKlass(k());
1576 }
1577 probe->set_definer(NULL);
1578 probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);
1579 placeholders()->find_and_remove(p_index, p_hash, name_h, class_loader, THREAD);
1580 SystemDictionary_lock->notify_all();
1581 }
1582 }
1583
1584 // Can't throw exception while holding lock due to rank ordering
1585 if (linkage_exception() != NULL) {
1586 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1587 }
1588
1589 return k;
1590 }
1591 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1592 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1593 if (class_loader.is_null()) {
1594 return Handle(THREAD, _system_loader_lock_obj);
1595 } else {
1596 return class_loader;
1597 }
1598 }
1599
1600 // This method is added to check how often we have to wait to grab loader
1601 // lock. The results are being recorded in the performance counters defined in
1602 // ClassLoader::_sync_systemLoaderLockContentionRate and
1603 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1604 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1605 if (!UsePerfData) {
1606 return;
1607 }
1608
1609 assert(!loader_lock.is_null(), "NULL lock object");
1610
1611 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1612 == ObjectSynchronizer::owner_other) {
1613 // contention will likely happen, so increment the corresponding
1614 // contention counter.
1615 if (loader_lock() == _system_loader_lock_obj) {
1616 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1617 } else {
1618 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1619 }
1620 }
1621 }
1622
1623 // ----------------------------------------------------------------------------
1624 // Lookup
1625
1626 klassOop SystemDictionary::find_class(int index, unsigned int hash,
1627 symbolHandle class_name,
1628 Handle class_loader) {
1629 assert_locked_or_safepoint(SystemDictionary_lock);
1630 assert (index == dictionary()->index_for(class_name, class_loader),
1631 "incorrect index?");
1632
1633 klassOop k = dictionary()->find_class(index, hash, class_name, class_loader);
1634 return k;
1635 }
1636
1637
1638 // Basic find on classes in the midst of being loaded
1639 symbolOop SystemDictionary::find_placeholder(int index, unsigned int hash,
1640 symbolHandle class_name,
1641 Handle class_loader) {
1642 assert_locked_or_safepoint(SystemDictionary_lock);
1643
1644 return placeholders()->find_entry(index, hash, class_name, class_loader);
1645 }
1646
1647
1648 // Used for assertions and verification only
1649 oop SystemDictionary::find_class_or_placeholder(symbolHandle class_name,
1650 Handle class_loader) {
1651 #ifndef ASSERT
1652 guarantee(VerifyBeforeGC ||
1653 VerifyDuringGC ||
1654 VerifyBeforeExit ||
1655 VerifyAfterGC, "too expensive");
1656 #endif
1657 assert_locked_or_safepoint(SystemDictionary_lock);
1658 symbolOop class_name_ = class_name();
1659 oop class_loader_ = class_loader();
1660
1661 // First look in the loaded class array
1662 unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);
1663 int d_index = dictionary()->hash_to_index(d_hash);
1664 oop lookup = find_class(d_index, d_hash, class_name, class_loader);
1665
1666 if (lookup == NULL) {
1667 // Next try the placeholders
1668 unsigned int p_hash = placeholders()->compute_hash(class_name,class_loader);
1669 int p_index = placeholders()->hash_to_index(p_hash);
1670 lookup = find_placeholder(p_index, p_hash, class_name, class_loader);
1671 }
1672
1673 return lookup;
1674 }
1675
1676
1677 // Get the next class in the diictionary.
1678 klassOop SystemDictionary::try_get_next_class() {
1679 return dictionary()->try_get_next_class();
1680 }
1681
1682
1683 // ----------------------------------------------------------------------------
1684 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1685 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1686 // before a new class is used.
1687
1688 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1689 assert(k.not_null(), "just checking");
1690 // Link into hierachy. Make sure the vtables are initialized before linking into
1691 k->append_to_sibling_list(); // add to superklass/sibling list
1692 k->process_interfaces(THREAD); // handle all "implements" declarations
1693 k->set_init_state(instanceKlass::loaded);
1694 // Now flush all code that depended on old class hierarchy.
1695 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1696 // Also, first reinitialize vtable because it may have gotten out of synch
1697 // while the new class wasn't connected to the class hierarchy.
1698 Universe::flush_dependents_on(k);
1699 }
1700
1701
1702 // ----------------------------------------------------------------------------
1703 // GC support
1704
1705 // Following roots during mark-sweep is separated in two phases.
1706 //
1707 // The first phase follows preloaded classes and all other system
1708 // classes, since these will never get unloaded anyway.
1709 //
1710 // The second phase removes (unloads) unreachable classes from the
1711 // system dictionary and follows the remaining classes' contents.
1712
1713 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1714 // Follow preloaded classes/mirrors and system loader object
1715 blk->do_oop(&_java_system_loader);
1716 preloaded_oops_do(blk);
1717 always_strong_classes_do(blk);
1718 }
1719
1720
1721 void SystemDictionary::always_strong_classes_do(OopClosure* blk) {
1722 // Follow all system classes and temporary placeholders in dictionary
1723 dictionary()->always_strong_classes_do(blk);
1724
1725 // Placeholders. These are *always* strong roots, as they
1726 // represent classes we're actively loading.
1727 placeholders_do(blk);
1728
1729 // Visit extra methods
1730 if (invoke_method_table() != NULL)
1731 invoke_method_table()->oops_do(blk);
1732
1733 // Loader constraints. We must keep the symbolOop used in the name alive.
1734 constraints()->always_strong_classes_do(blk);
1735
1736 // Resolution errors keep the symbolOop for the error alive
1737 resolution_errors()->always_strong_classes_do(blk);
1738 }
1739
1740
1741 void SystemDictionary::placeholders_do(OopClosure* blk) {
1742 placeholders()->oops_do(blk);
1743 }
1744
1745
1746 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
1747 bool result = dictionary()->do_unloading(is_alive);
1748 constraints()->purge_loader_constraints(is_alive);
1749 resolution_errors()->purge_resolution_errors(is_alive);
1750 return result;
1751 }
1752
1753
1754 // The mirrors are scanned by shared_oops_do() which is
1755 // not called by oops_do(). In order to process oops in
1756 // a necessary order, shared_oops_do() is call by
1757 // Universe::oops_do().
1758 void SystemDictionary::oops_do(OopClosure* f) {
1759 // Adjust preloaded classes and system loader object
1760 f->do_oop(&_java_system_loader);
1761 preloaded_oops_do(f);
1762
1763 lazily_loaded_oops_do(f);
1764
1765 // Adjust dictionary
1766 dictionary()->oops_do(f);
1767
1768 // Visit extra methods
1769 if (invoke_method_table() != NULL)
1770 invoke_method_table()->oops_do(f);
1771
1772 // Partially loaded classes
1773 placeholders()->oops_do(f);
1774
1775 // Adjust constraint table
1776 constraints()->oops_do(f);
1777
1778 // Adjust resolution error table
1779 resolution_errors()->oops_do(f);
1780 }
1781
1782
1783 void SystemDictionary::preloaded_oops_do(OopClosure* f) {
1784 f->do_oop((oop*) &wk_klass_name_limits[0]);
1785 f->do_oop((oop*) &wk_klass_name_limits[1]);
1786
1787 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1788 f->do_oop((oop*) &_well_known_klasses[k]);
1789 }
1790
1791 {
1792 for (int i = 0; i < T_VOID+1; i++) {
1793 if (_box_klasses[i] != NULL) {
1794 assert(i >= T_BOOLEAN, "checking");
1795 f->do_oop((oop*) &_box_klasses[i]);
1796 }
1797 }
1798 }
1799
1800 // The basic type mirrors would have already been processed in
1801 // Universe::oops_do(), via a call to shared_oops_do(), so should
1802 // not be processed again.
1803
1804 f->do_oop((oop*) &_system_loader_lock_obj);
1805 FilteredFieldsMap::klasses_oops_do(f);
1806 }
1807
1808 void SystemDictionary::lazily_loaded_oops_do(OopClosure* f) {
1809 f->do_oop((oop*) &_abstract_ownable_synchronizer_klass);
1810 }
1811
1812 // Just the classes from defining class loaders
1813 // Don't iterate over placeholders
1814 void SystemDictionary::classes_do(void f(klassOop)) {
1815 dictionary()->classes_do(f);
1816 }
1817
1818 // Added for initialize_itable_for_klass
1819 // Just the classes from defining class loaders
1820 // Don't iterate over placeholders
1821 void SystemDictionary::classes_do(void f(klassOop, TRAPS), TRAPS) {
1822 dictionary()->classes_do(f, CHECK);
1823 }
1824
1825 // All classes, and their class loaders
1826 // Don't iterate over placeholders
1827 void SystemDictionary::classes_do(void f(klassOop, oop)) {
1828 dictionary()->classes_do(f);
1829 }
1830
1831 // All classes, and their class loaders
1832 // (added for helpers that use HandleMarks and ResourceMarks)
1833 // Don't iterate over placeholders
1834 void SystemDictionary::classes_do(void f(klassOop, oop, TRAPS), TRAPS) {
1835 dictionary()->classes_do(f, CHECK);
1836 }
1837
1838 void SystemDictionary::placeholders_do(void f(symbolOop, oop)) {
1839 placeholders()->entries_do(f);
1840 }
1841
1842 void SystemDictionary::methods_do(void f(methodOop)) {
1843 dictionary()->methods_do(f);
1844 if (invoke_method_table() != NULL)
1845 invoke_method_table()->methods_do(f);
1846 }
1847
1848 // ----------------------------------------------------------------------------
1849 // Lazily load klasses
1850
1851 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1852 assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");
1853
1854 // if multiple threads calling this function, only one thread will load
1855 // the class. The other threads will find the loaded version once the
1856 // class is loaded.
1857 klassOop aos = _abstract_ownable_synchronizer_klass;
1858 if (aos == NULL) {
1859 klassOop k = resolve_or_fail(vmSymbolHandles::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1860 // Force a fence to prevent any read before the write completes
1861 OrderAccess::fence();
1862 _abstract_ownable_synchronizer_klass = k;
1863 }
1864 }
1865
1866 // ----------------------------------------------------------------------------
1867 // Initialization
1868
1869 void SystemDictionary::initialize(TRAPS) {
1870 // Allocate arrays
1871 assert(dictionary() == NULL,
1872 "SystemDictionary should only be initialized once");
1873 _dictionary = new Dictionary(_nof_buckets);
1874 _placeholders = new PlaceholderTable(_nof_buckets);
1875 _number_of_modifications = 0;
1876 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1877 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1878 // _invoke_method_table is allocated lazily in find_method_handle_invoke()
1879
1880 // Allocate private object used as system class loader lock
1881 _system_loader_lock_obj = oopFactory::new_system_objArray(0, CHECK);
1882 // Initialize basic classes
1883 initialize_preloaded_classes(CHECK);
1884 }
1885
1886 // Compact table of directions on the initialization of klasses:
1887 static const short wk_init_info[] = {
1888 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1889 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1890 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1891 | (int)SystemDictionary::option ),
1892 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1893 #undef WK_KLASS_INIT_INFO
1894 0
1895 };
1896
1897 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1898 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1899 int info = wk_init_info[id - FIRST_WKID];
1900 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1901 symbolHandle symbol = vmSymbolHandles::symbol_handle_at((vmSymbols::SID)sid);
1902 klassOop* klassp = &_well_known_klasses[id];
1903 bool must_load = (init_opt < SystemDictionary::Opt);
1904 bool try_load = true;
1905 if (init_opt == SystemDictionary::Opt_Kernel) {
1906 #ifndef KERNEL
1907 try_load = false;
1908 #endif //KERNEL
1909 }
1910 if ((*klassp) == NULL && try_load) {
1911 if (must_load) {
1912 (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class
1913 } else {
1914 (*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass
1915 }
1916 }
1917 return ((*klassp) != NULL);
1918 }
1919
1920 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1921 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1922 for (int id = (int)start_id; id < (int)limit_id; id++) {
1923 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1924 int info = wk_init_info[id - FIRST_WKID];
1925 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1926 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1927
1928 initialize_wk_klass((WKID)id, opt, CHECK);
1929
1930 // Update limits, so find_well_known_klass can be very fast:
1931 symbolOop s = vmSymbols::symbol_at((vmSymbols::SID)sid);
1932 if (wk_klass_name_limits[1] == NULL) {
1933 wk_klass_name_limits[0] = wk_klass_name_limits[1] = s;
1934 } else if (wk_klass_name_limits[1] < s) {
1935 wk_klass_name_limits[1] = s;
1936 } else if (wk_klass_name_limits[0] > s) {
1937 wk_klass_name_limits[0] = s;
1938 }
1939 }
1940
1941 // move the starting value forward to the limit:
1942 start_id = limit_id;
1943 }
1944
1945
1946 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1947 assert(WK_KLASS(object_klass) == NULL, "preloaded classes should only be initialized once");
1948 // Preload commonly used klasses
1949 WKID scan = FIRST_WKID;
1950 // first do Object, String, Class
1951 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(class_klass), scan, CHECK);
1952
1953 debug_only(instanceKlass::verify_class_klass_nonstatic_oop_maps(WK_KLASS(class_klass)));
1954
1955 // Fixup mirrors for classes loaded before java.lang.Class.
1956 // These calls iterate over the objects currently in the perm gen
1957 // so calling them at this point is matters (not before when there
1958 // are fewer objects and not later after there are more objects
1959 // in the perm gen.
1960 Universe::initialize_basic_type_mirrors(CHECK);
1961 Universe::fixup_mirrors(CHECK);
1962
1963 // do a bunch more:
1964 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(reference_klass), scan, CHECK);
1965
1966 // Preload ref klasses and set reference types
1967 instanceKlass::cast(WK_KLASS(reference_klass))->set_reference_type(REF_OTHER);
1968 instanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(reference_klass));
1969
1970 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(phantom_reference_klass), scan, CHECK);
1971 instanceKlass::cast(WK_KLASS(soft_reference_klass))->set_reference_type(REF_SOFT);
1972 instanceKlass::cast(WK_KLASS(weak_reference_klass))->set_reference_type(REF_WEAK);
1973 instanceKlass::cast(WK_KLASS(final_reference_klass))->set_reference_type(REF_FINAL);
1974 instanceKlass::cast(WK_KLASS(phantom_reference_klass))->set_reference_type(REF_PHANTOM);
1975
1976 WKID meth_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1977 WKID meth_group_end = WK_KLASS_ENUM_NAME(WrongMethodTypeException_klass);
1978 initialize_wk_klasses_until(meth_group_start, scan, CHECK);
1979 if (EnableMethodHandles) {
1980 initialize_wk_klasses_through(meth_group_end, scan, CHECK);
1981 }
1982 if (_well_known_klasses[meth_group_start] == NULL) {
1983 // Skip the rest of the method handle classes, if MethodHandle is not loaded.
1984 scan = WKID(meth_group_end+1);
1985 }
1986 WKID indy_group_start = WK_KLASS_ENUM_NAME(Linkage_klass);
1987 WKID indy_group_end = WK_KLASS_ENUM_NAME(InvokeDynamic_klass);
1988 initialize_wk_klasses_until(indy_group_start, scan, CHECK);
1989 if (EnableInvokeDynamic) {
1990 initialize_wk_klasses_through(indy_group_end, scan, CHECK);
1991 }
1992 if (_well_known_klasses[indy_group_start] == NULL) {
1993 // Skip the rest of the dynamic typing classes, if Linkage is not loaded.
1994 scan = WKID(indy_group_end+1);
1995 }
1996
1997 initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);
1998
1999 _box_klasses[T_BOOLEAN] = WK_KLASS(boolean_klass);
2000 _box_klasses[T_CHAR] = WK_KLASS(char_klass);
2001 _box_klasses[T_FLOAT] = WK_KLASS(float_klass);
2002 _box_klasses[T_DOUBLE] = WK_KLASS(double_klass);
2003 _box_klasses[T_BYTE] = WK_KLASS(byte_klass);
2004 _box_klasses[T_SHORT] = WK_KLASS(short_klass);
2005 _box_klasses[T_INT] = WK_KLASS(int_klass);
2006 _box_klasses[T_LONG] = WK_KLASS(long_klass);
2007 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
2008 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
2009
2010 #ifdef KERNEL
2011 if (sun_jkernel_DownloadManager_klass() == NULL) {
2012 warning("Cannot find sun/jkernel/DownloadManager");
2013 }
2014 #endif // KERNEL
2015
2016 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
2017 methodOop method = instanceKlass::cast(classloader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
2018 _has_loadClassInternal = (method != NULL);
2019 }
2020 { // Compute whether we should use checkPackageAccess or NOT
2021 methodOop method = instanceKlass::cast(classloader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2022 _has_checkPackageAccess = (method != NULL);
2023 }
2024 }
2025
2026 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2027 // If so, returns the basic type it holds. If not, returns T_OBJECT.
2028 BasicType SystemDictionary::box_klass_type(klassOop k) {
2029 assert(k != NULL, "");
2030 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2031 if (_box_klasses[i] == k)
2032 return (BasicType)i;
2033 }
2034 return T_OBJECT;
2035 }
2036
2037 KlassHandle SystemDictionaryHandles::box_klass(BasicType t) {
2038 if (t >= T_BOOLEAN && t <= T_VOID)
2039 return KlassHandle(&SystemDictionary::_box_klasses[t], true);
2040 else
2041 return KlassHandle();
2042 }
2043
2044 // Constraints on class loaders. The details of the algorithm can be
2045 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2046 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
2047 // that the system dictionary needs to maintain a set of contraints that
2048 // must be satisfied by all classes in the dictionary.
2049 // if defining is true, then LinkageError if already in systemDictionary
2050 // if initiating loader, then ok if instanceKlass matches existing entry
2051
2052 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
2053 instanceKlassHandle k,
2054 Handle class_loader, bool defining,
2055 TRAPS) {
2056 const char *linkage_error = NULL;
2057 {
2058 symbolHandle name (THREAD, k->name());
2059 MutexLocker mu(SystemDictionary_lock, THREAD);
2060
2061 klassOop check = find_class(d_index, d_hash, name, class_loader);
2062 if (check != (klassOop)NULL) {
2063 // if different instanceKlass - duplicate class definition,
2064 // else - ok, class loaded by a different thread in parallel,
2065 // we should only have found it if it was done loading and ok to use
2066 // system dictionary only holds instance classes, placeholders
2067 // also holds array classes
2068
2069 assert(check->klass_part()->oop_is_instance(), "noninstance in systemdictionary");
2070 if ((defining == true) || (k() != check)) {
2071 linkage_error = "loader (instance of %s): attempted duplicate class "
2072 "definition for name: \"%s\"";
2073 } else {
2074 return;
2075 }
2076 }
2077
2078 #ifdef ASSERT
2079 unsigned int p_hash = placeholders()->compute_hash(name, class_loader);
2080 int p_index = placeholders()->hash_to_index(p_hash);
2081 symbolOop ph_check = find_placeholder(p_index, p_hash, name, class_loader);
2082 assert(ph_check == NULL || ph_check == name(), "invalid symbol");
2083 #endif
2084
2085 if (linkage_error == NULL) {
2086 if (constraints()->check_or_update(k, class_loader, name) == false) {
2087 linkage_error = "loader constraint violation: loader (instance of %s)"
2088 " previously initiated loading for a different type with name \"%s\"";
2089 }
2090 }
2091 }
2092
2093 // Throw error now if needed (cannot throw while holding
2094 // SystemDictionary_lock because of rank ordering)
2095
2096 if (linkage_error) {
2097 ResourceMark rm(THREAD);
2098 const char* class_loader_name = loader_name(class_loader());
2099 char* type_name = k->name()->as_C_string();
2100 size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +
2101 strlen(type_name);
2102 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2103 jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);
2104 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2105 }
2106 }
2107
2108
2109 // Update system dictionary - done after check_constraint and add_to_hierachy
2110 // have been called.
2111 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2112 int p_index, unsigned int p_hash,
2113 instanceKlassHandle k,
2114 Handle class_loader,
2115 TRAPS) {
2116 // Compile_lock prevents systemDictionary updates during compilations
2117 assert_locked_or_safepoint(Compile_lock);
2118 symbolHandle name (THREAD, k->name());
2119
2120 {
2121 MutexLocker mu1(SystemDictionary_lock, THREAD);
2122
2123 // See whether biased locking is enabled and if so set it for this
2124 // klass.
2125 // Note that this must be done past the last potential blocking
2126 // point / safepoint. We enable biased locking lazily using a
2127 // VM_Operation to iterate the SystemDictionary and installing the
2128 // biasable mark word into each instanceKlass's prototype header.
2129 // To avoid race conditions where we accidentally miss enabling the
2130 // optimization for one class in the process of being added to the
2131 // dictionary, we must not safepoint after the test of
2132 // BiasedLocking::enabled().
2133 if (UseBiasedLocking && BiasedLocking::enabled()) {
2134 // Set biased locking bit for all loaded classes; it will be
2135 // cleared if revocation occurs too often for this type
2136 // NOTE that we must only do this when the class is initally
2137 // defined, not each time it is referenced from a new class loader
2138 if (k->class_loader() == class_loader()) {
2139 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2140 }
2141 }
2142
2143 // Check for a placeholder. If there, remove it and make a
2144 // new system dictionary entry.
2145 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
2146 klassOop sd_check = find_class(d_index, d_hash, name, class_loader);
2147 if (sd_check == NULL) {
2148 dictionary()->add_klass(name, class_loader, k);
2149 notice_modification();
2150 }
2151 #ifdef ASSERT
2152 sd_check = find_class(d_index, d_hash, name, class_loader);
2153 assert (sd_check != NULL, "should have entry in system dictionary");
2154 // Changed to allow PH to remain to complete class circularity checking
2155 // while only one thread can define a class at one time, multiple
2156 // classes can resolve the superclass for a class at one time,
2157 // and the placeholder is used to track that
2158 // symbolOop ph_check = find_placeholder(p_index, p_hash, name, class_loader);
2159 // assert (ph_check == NULL, "should not have a placeholder entry");
2160 #endif
2161 SystemDictionary_lock->notify_all();
2162 }
2163 }
2164
2165
2166 klassOop SystemDictionary::find_constrained_instance_or_array_klass(
2167 symbolHandle class_name, Handle class_loader, TRAPS) {
2168
2169 // First see if it has been loaded directly.
2170 // Force the protection domain to be null. (This removes protection checks.)
2171 Handle no_protection_domain;
2172 klassOop klass = find_instance_or_array_klass(class_name, class_loader,
2173 no_protection_domain, CHECK_NULL);
2174 if (klass != NULL)
2175 return klass;
2176
2177 // Now look to see if it has been loaded elsewhere, and is subject to
2178 // a loader constraint that would require this loader to return the
2179 // klass that is already loaded.
2180 if (FieldType::is_array(class_name())) {
2181 // Array classes are hard because their klassOops are not kept in the
2182 // constraint table. The array klass may be constrained, but the elem class
2183 // may not be.
2184 jint dimension;
2185 symbolOop object_key;
2186 BasicType t = FieldType::get_array_info(class_name(), &dimension,
2187 &object_key, CHECK_(NULL));
2188 if (t != T_OBJECT) {
2189 klass = Universe::typeArrayKlassObj(t);
2190 } else {
2191 symbolHandle elem_name(THREAD, object_key);
2192 MutexLocker mu(SystemDictionary_lock, THREAD);
2193 klass = constraints()->find_constrained_elem_klass(class_name, elem_name, class_loader, THREAD);
2194 }
2195 if (klass != NULL) {
2196 klass = Klass::cast(klass)->array_klass_or_null(dimension);
2197 }
2198 } else {
2199 MutexLocker mu(SystemDictionary_lock, THREAD);
2200 // Non-array classes are easy: simply check the constraint table.
2201 klass = constraints()->find_constrained_klass(class_name, class_loader);
2202 }
2203
2204 return klass;
2205 }
2206
2207
2208 bool SystemDictionary::add_loader_constraint(symbolHandle class_name,
2209 Handle class_loader1,
2210 Handle class_loader2,
2211 Thread* THREAD) {
2212 unsigned int d_hash1 = dictionary()->compute_hash(class_name, class_loader1);
2213 int d_index1 = dictionary()->hash_to_index(d_hash1);
2214
2215 unsigned int d_hash2 = dictionary()->compute_hash(class_name, class_loader2);
2216 int d_index2 = dictionary()->hash_to_index(d_hash2);
2217
2218 {
2219 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2220
2221 // Better never do a GC while we're holding these oops
2222 No_Safepoint_Verifier nosafepoint;
2223
2224 klassOop klass1 = find_class(d_index1, d_hash1, class_name, class_loader1);
2225 klassOop klass2 = find_class(d_index2, d_hash2, class_name, class_loader2);
2226 return constraints()->add_entry(class_name, klass1, class_loader1,
2227 klass2, class_loader2);
2228 }
2229 }
2230
2231 // Add entry to resolution error table to record the error when the first
2232 // attempt to resolve a reference to a class has failed.
2233 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, symbolHandle error) {
2234 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2235 int index = resolution_errors()->hash_to_index(hash);
2236 {
2237 MutexLocker ml(SystemDictionary_lock, Thread::current());
2238 resolution_errors()->add_entry(index, hash, pool, which, error);
2239 }
2240 }
2241
2242 // Lookup resolution error table. Returns error if found, otherwise NULL.
2243 symbolOop SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {
2244 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2245 int index = resolution_errors()->hash_to_index(hash);
2246 {
2247 MutexLocker ml(SystemDictionary_lock, Thread::current());
2248 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2249 return (entry != NULL) ? entry->error() : (symbolOop)NULL;
2250 }
2251 }
2252
2253
2254 // Signature constraints ensure that callers and callees agree about
2255 // the meaning of type names in their signatures. This routine is the
2256 // intake for constraints. It collects them from several places:
2257 //
2258 // * LinkResolver::resolve_method (if check_access is true) requires
2259 // that the resolving class (the caller) and the defining class of
2260 // the resolved method (the callee) agree on each type in the
2261 // method's signature.
2262 //
2263 // * LinkResolver::resolve_interface_method performs exactly the same
2264 // checks.
2265 //
2266 // * LinkResolver::resolve_field requires that the constant pool
2267 // attempting to link to a field agree with the field's defining
2268 // class about the type of the field signature.
2269 //
2270 // * klassVtable::initialize_vtable requires that, when a class
2271 // overrides a vtable entry allocated by a superclass, that the
2272 // overriding method (i.e., the callee) agree with the superclass
2273 // on each type in the method's signature.
2274 //
2275 // * klassItable::initialize_itable requires that, when a class fills
2276 // in its itables, for each non-abstract method installed in an
2277 // itable, the method (i.e., the callee) agree with the interface
2278 // on each type in the method's signature.
2279 //
2280 // All those methods have a boolean (check_access, checkconstraints)
2281 // which turns off the checks. This is used from specialized contexts
2282 // such as bootstrapping, dumping, and debugging.
2283 //
2284 // No direct constraint is placed between the class and its
2285 // supertypes. Constraints are only placed along linked relations
2286 // between callers and callees. When a method overrides or implements
2287 // an abstract method in a supertype (superclass or interface), the
2288 // constraints are placed as if the supertype were the caller to the
2289 // overriding method. (This works well, since callers to the
2290 // supertype have already established agreement between themselves and
2291 // the supertype.) As a result of all this, a class can disagree with
2292 // its supertype about the meaning of a type name, as long as that
2293 // class neither calls a relevant method of the supertype, nor is
2294 // called (perhaps via an override) from the supertype.
2295 //
2296 //
2297 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2298 //
2299 // Make sure all class components (including arrays) in the given
2300 // signature will be resolved to the same class in both loaders.
2301 // Returns the name of the type that failed a loader constraint check, or
2302 // NULL if no constraint failed. The returned C string needs cleaning up
2303 // with a ResourceMark in the caller. No exception except OOME is thrown.
2304 char* SystemDictionary::check_signature_loaders(symbolHandle signature,
2305 Handle loader1, Handle loader2,
2306 bool is_method, TRAPS) {
2307 // Nothing to do if loaders are the same.
2308 if (loader1() == loader2()) {
2309 return NULL;
2310 }
2311
2312 SignatureStream sig_strm(signature, is_method);
2313 while (!sig_strm.is_done()) {
2314 if (sig_strm.is_object()) {
2315 symbolOop s = sig_strm.as_symbol(CHECK_NULL);
2316 symbolHandle sig (THREAD, s);
2317 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2318 return sig()->as_C_string();
2319 }
2320 }
2321 sig_strm.next();
2322 }
2323 return NULL;
2324 }
2325
2326
2327 methodOop SystemDictionary::find_method_handle_invoke(symbolHandle signature,
2328 Handle class_loader,
2329 Handle protection_domain,
2330 TRAPS) {
2331 if (!EnableMethodHandles) return NULL;
2332 assert(class_loader.is_null() && protection_domain.is_null(),
2333 "cannot load specialized versions of MethodHandle.invoke");
2334 if (invoke_method_table() == NULL) {
2335 // create this side table lazily
2336 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
2337 }
2338 unsigned int hash = invoke_method_table()->compute_hash(signature);
2339 int index = invoke_method_table()->hash_to_index(hash);
2340 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature);
2341 if (spe == NULL || spe->property_oop() == NULL) {
2342 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2343 if (THREAD->is_Compiler_thread())
2344 return NULL; // do not attempt from within compiler
2345 Handle mt = compute_method_handle_type(signature(),
2346 class_loader, protection_domain,
2347 CHECK_NULL);
2348 KlassHandle mh_klass = SystemDictionaryHandles::MethodHandle_klass();
2349 methodHandle m = methodOopDesc::make_invoke_method(mh_klass, signature,
2350 mt, CHECK_NULL);
2351 // Now grab the lock. We might have to throw away the new method,
2352 // if a racing thread has managed to install one at the same time.
2353 {
2354 MutexLocker ml(SystemDictionary_lock, Thread::current());
2355 spe = invoke_method_table()->find_entry(index, hash, signature);
2356 if (spe == NULL)
2357 spe = invoke_method_table()->add_entry(index, hash, signature);
2358 if (spe->property_oop() == NULL)
2359 spe->set_property_oop(m());
2360 }
2361 }
2362 methodOop m = (methodOop) spe->property_oop();
2363 assert(m->is_method(), "");
2364 return m;
2365 }
2366
2367 // Ask Java code to find or construct a java.dyn.MethodType for the given
2368 // signature, as interpreted relative to the given class loader.
2369 // Because of class loader constraints, all method handle usage must be
2370 // consistent with this loader.
2371 Handle SystemDictionary::compute_method_handle_type(symbolHandle signature,
2372 Handle class_loader,
2373 Handle protection_domain,
2374 TRAPS) {
2375 Handle empty;
2376 int npts = ArgumentCount(signature()).size();
2377 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::class_klass(), npts, CHECK_(empty));
2378 int arg = 0;
2379 Handle rt; // the return type from the signature
2380 for (SignatureStream ss(signature()); !ss.is_done(); ss.next()) {
2381 oop mirror;
2382 if (!ss.is_object()) {
2383 mirror = Universe::java_mirror(ss.type());
2384 } else {
2385 symbolOop name_oop = ss.as_symbol(CHECK_(empty));
2386 symbolHandle name(THREAD, name_oop);
2387 klassOop klass = resolve_or_fail(name,
2388 class_loader, protection_domain,
2389 true, CHECK_(empty));
2390 mirror = Klass::cast(klass)->java_mirror();
2391 }
2392 if (ss.at_return_type())
2393 rt = Handle(THREAD, mirror);
2394 else
2395 pts->obj_at_put(arg++, mirror);
2396 }
2397 assert(arg == npts, "");
2398
2399 // call MethodType java.dyn.MethodType::makeImpl(Class rt, Class[] pts, false, true)
2400 bool varargs = false, trusted = true;
2401 JavaCallArguments args(Handle(THREAD, rt()));
2402 args.push_oop(pts());
2403 args.push_int(false);
2404 args.push_int(trusted);
2405 JavaValue result(T_OBJECT);
2406 JavaCalls::call_static(&result,
2407 SystemDictionary::MethodType_klass(),
2408 vmSymbols::makeImpl_name(), vmSymbols::makeImpl_signature(),
2409 &args, CHECK_(empty));
2410 return Handle(THREAD, (oop) result.get_jobject());
2411 }
2412
2413
2414 // Ask Java code to find or construct a java.dyn.CallSite for the given
2415 // name and signature, as interpreted relative to the given class loader.
2416 Handle SystemDictionary::make_dynamic_call_site(KlassHandle caller,
2417 int caller_method_idnum,
2418 int caller_bci,
2419 symbolHandle name,
2420 methodHandle mh_invdyn,
2421 TRAPS) {
2422 Handle empty;
2423 // call java.dyn.CallSite::makeSite(caller, name, mtype, cmid, cbci)
2424 oop name_str_oop = StringTable::intern(name(), CHECK_(empty)); // not a handle!
2425 JavaCallArguments args(Handle(THREAD, caller->java_mirror()));
2426 args.push_oop(name_str_oop);
2427 args.push_oop(mh_invdyn->method_handle_type());
2428 args.push_int(caller_method_idnum);
2429 args.push_int(caller_bci);
2430 JavaValue result(T_OBJECT);
2431 JavaCalls::call_static(&result,
2432 SystemDictionary::CallSite_klass(),
2433 vmSymbols::makeSite_name(), vmSymbols::makeSite_signature(),
2434 &args, CHECK_(empty));
2435 oop call_site_oop = (oop) result.get_jobject();
2436 assert(call_site_oop->is_oop()
2437 /*&& java_dyn_CallSite::is_instance(call_site_oop)*/, "must be sane");
2438 java_dyn_CallSite::set_vmmethod(call_site_oop, mh_invdyn());
2439 if (TraceMethodHandles) {
2440 #ifndef PRODUCT
2441 tty->print_cr("Linked invokedynamic bci=%d site="INTPTR_FORMAT":", caller_bci, call_site_oop);
2442 call_site_oop->print();
2443 tty->cr();
2444 #endif //PRODUCT
2445 }
2446 return call_site_oop;
2447 }
2448
2449 Handle SystemDictionary::find_bootstrap_method(KlassHandle caller,
2450 KlassHandle search_bootstrap_klass,
2451 TRAPS) {
2452 Handle empty;
2453 if (!caller->oop_is_instance()) return empty;
2454
2455 instanceKlassHandle ik(THREAD, caller());
2456
2457 oop boot_method_oop = ik->bootstrap_method();
2458 if (boot_method_oop != NULL) {
2459 if (TraceMethodHandles) {
2460 tty->print_cr("bootstrap method for "PTR_FORMAT" cached as "PTR_FORMAT":", ik(), boot_method_oop);
2461 }
2462 NOT_PRODUCT(if (!boot_method_oop->is_oop()) { tty->print_cr("*** boot MH of "PTR_FORMAT" = "PTR_FORMAT, ik(), boot_method_oop); ik()->print(); });
2463 assert(boot_method_oop->is_oop()
2464 && java_dyn_MethodHandle::is_instance(boot_method_oop), "must be sane");
2465 return Handle(THREAD, boot_method_oop);
2466 }
2467 boot_method_oop = NULL; // GC safety
2468
2469 // call java.dyn.Linkage::findBootstrapMethod(caller, sbk)
2470 JavaCallArguments args(Handle(THREAD, ik->java_mirror()));
2471 if (search_bootstrap_klass.is_null())
2472 args.push_oop(Handle());
2473 else
2474 args.push_oop(search_bootstrap_klass->java_mirror());
2475 JavaValue result(T_OBJECT);
2476 JavaCalls::call_static(&result,
2477 SystemDictionary::Linkage_klass(),
2478 vmSymbols::findBootstrapMethod_name(),
2479 vmSymbols::findBootstrapMethod_signature(),
2480 &args, CHECK_(empty));
2481 boot_method_oop = (oop) result.get_jobject();
2482
2483 if (boot_method_oop != NULL) {
2484 if (TraceMethodHandles) {
2485 #ifndef PRODUCT
2486 tty->print_cr("--------");
2487 tty->print_cr("bootstrap method for "PTR_FORMAT" computed as "PTR_FORMAT":", ik(), boot_method_oop);
2488 ik()->print();
2489 boot_method_oop->print();
2490 tty->print_cr("========");
2491 #endif //PRODUCT
2492 }
2493 assert(boot_method_oop->is_oop()
2494 && java_dyn_MethodHandle::is_instance(boot_method_oop), "must be sane");
2495 // probably no race conditions, but let's be careful:
2496 if (Atomic::cmpxchg_ptr(boot_method_oop, ik->adr_bootstrap_method(), NULL) == NULL)
2497 ik->set_bootstrap_method(boot_method_oop);
2498 else
2499 boot_method_oop = ik->bootstrap_method();
2500 } else {
2501 if (TraceMethodHandles) {
2502 #ifndef PRODUCT
2503 tty->print_cr("--------");
2504 tty->print_cr("bootstrap method for "PTR_FORMAT" computed as NULL:", ik());
2505 ik()->print();
2506 tty->print_cr("========");
2507 #endif //PRODUCT
2508 }
2509 boot_method_oop = ik->bootstrap_method();
2510 }
2511
2512 return Handle(THREAD, boot_method_oop);
2513 }
2514
2515 // Since the identity hash code for symbols changes when the symbols are
2516 // moved from the regular perm gen (hash in the mark word) to the shared
2517 // spaces (hash is the address), the classes loaded into the dictionary
2518 // may be in the wrong buckets.
2519
2520 void SystemDictionary::reorder_dictionary() {
2521 dictionary()->reorder_dictionary();
2522 }
2523
2524
2525 void SystemDictionary::copy_buckets(char** top, char* end) {
2526 dictionary()->copy_buckets(top, end);
2527 }
2528
2529
2530 void SystemDictionary::copy_table(char** top, char* end) {
2531 dictionary()->copy_table(top, end);
2532 }
2533
2534
2535 void SystemDictionary::reverse() {
2536 dictionary()->reverse();
2537 }
2538
2539 int SystemDictionary::number_of_classes() {
2540 return dictionary()->number_of_entries();
2541 }
2542
2543
2544 // ----------------------------------------------------------------------------
2545 #ifndef PRODUCT
2546
2547 void SystemDictionary::print() {
2548 dictionary()->print();
2549
2550 // Placeholders
2551 GCMutexLocker mu(SystemDictionary_lock);
2552 placeholders()->print();
2553
2554 // loader constraints - print under SD_lock
2555 constraints()->print();
2556 }
2557
2558 #endif
2559
2560 void SystemDictionary::verify() {
2561 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2562 guarantee(constraints() != NULL,
2563 "Verify of loader constraints failed");
2564 guarantee(dictionary()->number_of_entries() >= 0 &&
2565 placeholders()->number_of_entries() >= 0,
2566 "Verify of system dictionary failed");
2567
2568 // Verify dictionary
2569 dictionary()->verify();
2570
2571 GCMutexLocker mu(SystemDictionary_lock);
2572 placeholders()->verify();
2573
2574 // Verify constraint table
2575 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2576 constraints()->verify(dictionary());
2577 }
2578
2579
2580 void SystemDictionary::verify_obj_klass_present(Handle obj,
2581 symbolHandle class_name,
2582 Handle class_loader) {
2583 GCMutexLocker mu(SystemDictionary_lock);
2584 oop probe = find_class_or_placeholder(class_name, class_loader);
2585 if (probe == NULL) {
2586 probe = SystemDictionary::find_shared_class(class_name);
2587 }
2588 guarantee(probe != NULL &&
2589 (!probe->is_klass() || probe == obj()),
2590 "Loaded klasses should be in SystemDictionary");
2591 }
2592
2593 #ifndef PRODUCT
2594
2595 // statistics code
2596 class ClassStatistics: AllStatic {
2597 private:
2598 static int nclasses; // number of classes
2599 static int nmethods; // number of methods
2600 static int nmethoddata; // number of methodData
2601 static int class_size; // size of class objects in words
2602 static int method_size; // size of method objects in words
2603 static int debug_size; // size of debug info in methods
2604 static int methoddata_size; // size of methodData objects in words
2605
2606 static void do_class(klassOop k) {
2607 nclasses++;
2608 class_size += k->size();
2609 if (k->klass_part()->oop_is_instance()) {
2610 instanceKlass* ik = (instanceKlass*)k->klass_part();
2611 class_size += ik->methods()->size();
2612 class_size += ik->constants()->size();
2613 class_size += ik->local_interfaces()->size();
2614 class_size += ik->transitive_interfaces()->size();
2615 // We do not have to count implementors, since we only store one!
2616 class_size += ik->fields()->size();
2617 }
2618 }
2619
2620 static void do_method(methodOop m) {
2621 nmethods++;
2622 method_size += m->size();
2623 // class loader uses same objArray for empty vectors, so don't count these
2624 if (m->exception_table()->length() != 0) method_size += m->exception_table()->size();
2625 if (m->has_stackmap_table()) {
2626 method_size += m->stackmap_data()->size();
2627 }
2628
2629 methodDataOop mdo = m->method_data();
2630 if (mdo != NULL) {
2631 nmethoddata++;
2632 methoddata_size += mdo->size();
2633 }
2634 }
2635
2636 public:
2637 static void print() {
2638 SystemDictionary::classes_do(do_class);
2639 SystemDictionary::methods_do(do_method);
2640 tty->print_cr("Class statistics:");
2641 tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
2642 tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
2643 (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
2644 tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
2645 }
2646 };
2647
2648
2649 int ClassStatistics::nclasses = 0;
2650 int ClassStatistics::nmethods = 0;
2651 int ClassStatistics::nmethoddata = 0;
2652 int ClassStatistics::class_size = 0;
2653 int ClassStatistics::method_size = 0;
2654 int ClassStatistics::debug_size = 0;
2655 int ClassStatistics::methoddata_size = 0;
2656
2657 void SystemDictionary::print_class_statistics() {
2658 ResourceMark rm;
2659 ClassStatistics::print();
2660 }
2661
2662
2663 class MethodStatistics: AllStatic {
2664 public:
2665 enum {
2666 max_parameter_size = 10
2667 };
2668 private:
2669
2670 static int _number_of_methods;
2671 static int _number_of_final_methods;
2672 static int _number_of_static_methods;
2673 static int _number_of_native_methods;
2674 static int _number_of_synchronized_methods;
2675 static int _number_of_profiled_methods;
2676 static int _number_of_bytecodes;
2677 static int _parameter_size_profile[max_parameter_size];
2678 static int _bytecodes_profile[Bytecodes::number_of_java_codes];
2679
2680 static void initialize() {
2681 _number_of_methods = 0;
2682 _number_of_final_methods = 0;
2683 _number_of_static_methods = 0;
2684 _number_of_native_methods = 0;
2685 _number_of_synchronized_methods = 0;
2686 _number_of_profiled_methods = 0;
2687 _number_of_bytecodes = 0;
2688 for (int i = 0; i < max_parameter_size ; i++) _parameter_size_profile[i] = 0;
2689 for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile [j] = 0;
2690 };
2691
2692 static void do_method(methodOop m) {
2693 _number_of_methods++;
2694 // collect flag info
2695 if (m->is_final() ) _number_of_final_methods++;
2696 if (m->is_static() ) _number_of_static_methods++;
2697 if (m->is_native() ) _number_of_native_methods++;
2698 if (m->is_synchronized()) _number_of_synchronized_methods++;
2699 if (m->method_data() != NULL) _number_of_profiled_methods++;
2700 // collect parameter size info (add one for receiver, if any)
2701 _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
2702 // collect bytecodes info
2703 {
2704 Thread *thread = Thread::current();
2705 HandleMark hm(thread);
2706 BytecodeStream s(methodHandle(thread, m));
2707 Bytecodes::Code c;
2708 while ((c = s.next()) >= 0) {
2709 _number_of_bytecodes++;
2710 _bytecodes_profile[c]++;
2711 }
2712 }
2713 }
2714
2715 public:
2716 static void print() {
2717 initialize();
2718 SystemDictionary::methods_do(do_method);
2719 // generate output
2720 tty->cr();
2721 tty->print_cr("Method statistics (static):");
2722 // flag distribution
2723 tty->cr();
2724 tty->print_cr("%6d final methods %6.1f%%", _number_of_final_methods , _number_of_final_methods * 100.0F / _number_of_methods);
2725 tty->print_cr("%6d static methods %6.1f%%", _number_of_static_methods , _number_of_static_methods * 100.0F / _number_of_methods);
2726 tty->print_cr("%6d native methods %6.1f%%", _number_of_native_methods , _number_of_native_methods * 100.0F / _number_of_methods);
2727 tty->print_cr("%6d synchronized methods %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
2728 tty->print_cr("%6d profiled methods %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
2729 // parameter size profile
2730 tty->cr();
2731 { int tot = 0;
2732 int avg = 0;
2733 for (int i = 0; i < max_parameter_size; i++) {
2734 int n = _parameter_size_profile[i];
2735 tot += n;
2736 avg += n*i;
2737 tty->print_cr("parameter size = %1d: %6d methods %5.1f%%", i, n, n * 100.0F / _number_of_methods);
2738 }
2739 assert(tot == _number_of_methods, "should be the same");
2740 tty->print_cr(" %6d methods 100.0%%", _number_of_methods);
2741 tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
2742 }
2743 // bytecodes profile
2744 tty->cr();
2745 { int tot = 0;
2746 for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
2747 if (Bytecodes::is_defined(i)) {
2748 Bytecodes::Code c = Bytecodes::cast(i);
2749 int n = _bytecodes_profile[c];
2750 tot += n;
2751 tty->print_cr("%9d %7.3f%% %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
2752 }
2753 }
2754 assert(tot == _number_of_bytecodes, "should be the same");
2755 tty->print_cr("%9d 100.000%%", _number_of_bytecodes);
2756 }
2757 tty->cr();
2758 }
2759 };
2760
2761 int MethodStatistics::_number_of_methods;
2762 int MethodStatistics::_number_of_final_methods;
2763 int MethodStatistics::_number_of_static_methods;
2764 int MethodStatistics::_number_of_native_methods;
2765 int MethodStatistics::_number_of_synchronized_methods;
2766 int MethodStatistics::_number_of_profiled_methods;
2767 int MethodStatistics::_number_of_bytecodes;
2768 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
2769 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
2770
2771
2772 void SystemDictionary::print_method_statistics() {
2773 MethodStatistics::print();
2774 }
2775
2776 #endif // PRODUCT