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 // Resolving of classes
103
104 // Forwards to resolve_or_null
105
106 klassOop SystemDictionary::resolve_or_fail(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
107 klassOop klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
108 if (HAS_PENDING_EXCEPTION || klass == NULL) {
109 KlassHandle k_h(THREAD, klass);
110 // can return a null klass
111 klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);
112 }
113 return klass;
114 }
115
116 klassOop SystemDictionary::handle_resolution_exception(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {
117 if (HAS_PENDING_EXCEPTION) {
118 // If we have a pending exception we forward it to the caller, unless throw_error is true,
119 // in which case we have to check whether the pending exception is a ClassNotFoundException,
120 // and if so convert it to a NoClassDefFoundError
121 // And chain the original ClassNotFoundException
122 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::classNotFoundException_klass())) {
123 ResourceMark rm(THREAD);
124 assert(klass_h() == NULL, "Should not have result with exception pending");
125 Handle e(THREAD, PENDING_EXCEPTION);
126 CLEAR_PENDING_EXCEPTION;
127 THROW_MSG_CAUSE_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
128 } else {
129 return NULL;
130 }
131 }
132 // Class not found, throw appropriate error or exception depending on value of throw_error
133 if (klass_h() == NULL) {
134 ResourceMark rm(THREAD);
135 if (throw_error) {
136 THROW_MSG_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
137 } else {
138 THROW_MSG_0(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
139 }
140 }
141 return (klassOop)klass_h();
142 }
143
144
145 klassOop SystemDictionary::resolve_or_fail(symbolHandle class_name,
146 bool throw_error, TRAPS)
147 {
148 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
149 }
150
151
152 // Forwards to resolve_instance_class_or_null
153
154 klassOop SystemDictionary::resolve_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS) {
155 assert(!THREAD->is_Compiler_thread(), "Can not load classes with the Compiler thread");
156 if (FieldType::is_array(class_name())) {
157 return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
158 } else {
159 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
160 }
161 }
162
163 klassOop SystemDictionary::resolve_or_null(symbolHandle class_name, TRAPS) {
164 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
165 }
166
167 // Forwards to resolve_instance_class_or_null
168
169 klassOop SystemDictionary::resolve_array_class_or_null(symbolHandle class_name,
170 Handle class_loader,
171 Handle protection_domain,
172 TRAPS) {
173 assert(FieldType::is_array(class_name()), "must be array");
174 jint dimension;
175 symbolOop object_key;
176 klassOop k = NULL;
177 // dimension and object_key are assigned as a side-effect of this call
178 BasicType t = FieldType::get_array_info(class_name(),
179 &dimension,
180 &object_key,
181 CHECK_NULL);
182
183 if (t == T_OBJECT) {
184 symbolHandle h_key(THREAD, object_key);
185 // naked oop "k" is OK here -- we assign back into it
186 k = SystemDictionary::resolve_instance_class_or_null(h_key,
187 class_loader,
188 protection_domain,
189 CHECK_NULL);
190 if (k != NULL) {
191 k = Klass::cast(k)->array_klass(dimension, CHECK_NULL);
192 }
193 } else {
194 k = Universe::typeArrayKlassObj(t);
195 k = typeArrayKlass::cast(k)->array_klass(dimension, CHECK_NULL);
196 }
197 return k;
198 }
199
200
201 // Must be called for any super-class or super-interface resolution
202 // during class definition to allow class circularity checking
203 // super-interface callers:
204 // parse_interfaces - for defineClass & jvmtiRedefineClasses
205 // super-class callers:
206 // ClassFileParser - for defineClass & jvmtiRedefineClasses
207 // load_shared_class - while loading a class from shared archive
208 // resolve_instance_class_or_null:
209 // via: handle_parallel_super_load
210 // when resolving a class that has an existing placeholder with
211 // a saved superclass [i.e. a defineClass is currently in progress]
212 // if another thread is trying to resolve the class, it must do
213 // super-class checks on its own thread to catch class circularity
214 // This last call is critical in class circularity checking for cases
215 // where classloading is delegated to different threads and the
216 // classloader lock is released.
217 // Take the case: Base->Super->Base
218 // 1. If thread T1 tries to do a defineClass of class Base
219 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
220 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
221 // so it tries to load Super
222 // 3. If we load the class internally, or user classloader uses same thread
223 // loadClassFromxxx or defineClass via parseClassFile Super ...
224 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
225 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
226 // 3.4 calls resolve_super_or_fail Base
227 // 3.5 finds T1,Base -> throws class circularity
228 //OR 4. If T2 tries to resolve Super via defineClass Super ...
229 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
230 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
231 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
232 // 4.4 finds T2, Super -> throws class circularity
233 // Must be called, even if superclass is null, since this is
234 // where the placeholder entry is created which claims this
235 // thread is loading this class/classloader.
236 klassOop SystemDictionary::resolve_super_or_fail(symbolHandle child_name,
237 symbolHandle class_name,
238 Handle class_loader,
239 Handle protection_domain,
240 bool is_superclass,
241 TRAPS) {
242
243 // Try to get one of the well-known klasses.
244 // They are trusted, and do not participate in circularities.
245 if (LinkWellKnownClasses) {
246 klassOop k = find_well_known_klass(class_name());
247 if (k != NULL) {
248 return k;
249 }
250 }
251
252 // Double-check, if child class is already loaded, just return super-class,interface
253 // Don't add a placedholder if already loaded, i.e. already in system dictionary
254 // Make sure there's a placeholder for the *child* before resolving.
255 // Used as a claim that this thread is currently loading superclass/classloader
256 // Used here for ClassCircularity checks and also for heap verification
257 // (every instanceKlass in the heap needs to be in the system dictionary
258 // or have a placeholder).
259 // Must check ClassCircularity before checking if super class is already loaded
260 //
261 // We might not already have a placeholder if this child_name was
262 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
263 // the name of the class might not be known until the stream is actually
264 // parsed.
265 // Bugs 4643874, 4715493
266 // compute_hash can have a safepoint
267
268 unsigned int d_hash = dictionary()->compute_hash(child_name, class_loader);
269 int d_index = dictionary()->hash_to_index(d_hash);
270 unsigned int p_hash = placeholders()->compute_hash(child_name, class_loader);
271 int p_index = placeholders()->hash_to_index(p_hash);
272 // can't throw error holding a lock
273 bool child_already_loaded = false;
274 bool throw_circularity_error = false;
275 {
276 MutexLocker mu(SystemDictionary_lock, THREAD);
277 klassOop childk = find_class(d_index, d_hash, child_name, class_loader);
278 klassOop quicksuperk;
279 // to support // loading: if child done loading, just return superclass
280 // if class_name, & class_loader don't match:
281 // if initial define, SD update will give LinkageError
282 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
283 // so we don't throw an exception here.
284 // see: nsk redefclass014 & java.lang.instrument Instrument032
285 if ((childk != NULL ) && (is_superclass) &&
286 ((quicksuperk = instanceKlass::cast(childk)->super()) != NULL) &&
287
288 ((Klass::cast(quicksuperk)->name() == class_name()) &&
289 (Klass::cast(quicksuperk)->class_loader() == class_loader()))) {
290 return quicksuperk;
291 } else {
292 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, class_loader);
293 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
294 throw_circularity_error = true;
295 }
296 }
297 if (!throw_circularity_error) {
298 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, class_loader, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
299 }
300 }
301 if (throw_circularity_error) {
302 ResourceMark rm(THREAD);
303 THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
304 }
305
306 // java.lang.Object should have been found above
307 assert(class_name() != NULL, "null super class for resolving");
308 // Resolve the super class or interface, check results on return
309 klassOop superk = NULL;
310 superk = SystemDictionary::resolve_or_null(class_name,
311 class_loader,
312 protection_domain,
313 THREAD);
314
315 KlassHandle superk_h(THREAD, superk);
316
317 // Note: clean up of placeholders currently in callers of
318 // resolve_super_or_fail - either at update_dictionary time
319 // or on error
320 {
321 MutexLocker mu(SystemDictionary_lock, THREAD);
322 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, class_loader);
323 if (probe != NULL) {
324 probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER);
325 }
326 }
327 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
328 // can null superk
329 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));
330 }
331
332 return superk_h();
333 }
334
335 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
336 Handle class_loader,
337 Handle protection_domain,
338 TRAPS) {
339 if(!has_checkPackageAccess()) return;
340
341 // Now we have to call back to java to check if the initating class has access
342 JavaValue result(T_VOID);
343 if (TraceProtectionDomainVerification) {
344 // Print out trace information
345 tty->print_cr("Checking package access");
346 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
347 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
348 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
349 }
350
351 assert(class_loader() != NULL, "should not have non-null protection domain for null classloader");
352
353 KlassHandle system_loader(THREAD, SystemDictionary::classloader_klass());
354 JavaCalls::call_special(&result,
355 class_loader,
356 system_loader,
357 vmSymbolHandles::checkPackageAccess_name(),
358 vmSymbolHandles::class_protectiondomain_signature(),
359 Handle(THREAD, klass->java_mirror()),
360 protection_domain,
361 THREAD);
362
363 if (TraceProtectionDomainVerification) {
364 if (HAS_PENDING_EXCEPTION) {
365 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
366 } else {
367 tty->print_cr(" -> granted");
368 }
369 tty->cr();
370 }
371
372 if (HAS_PENDING_EXCEPTION) return;
373
374 // If no exception has been thrown, we have validated the protection domain
375 // Insert the protection domain of the initiating class into the set.
376 {
377 // We recalculate the entry here -- we've called out to java since
378 // the last time it was calculated.
379 symbolHandle kn(THREAD, klass->name());
380 unsigned int d_hash = dictionary()->compute_hash(kn, class_loader);
381 int d_index = dictionary()->hash_to_index(d_hash);
382
383 MutexLocker mu(SystemDictionary_lock, THREAD);
384 {
385 // Note that we have an entry, and entries can be deleted only during GC,
386 // so we cannot allow GC to occur while we're holding this entry.
387
388 // We're using a No_Safepoint_Verifier to catch any place where we
389 // might potentially do a GC at all.
390 // SystemDictionary::do_unloading() asserts that classes are only
391 // unloaded at a safepoint.
392 No_Safepoint_Verifier nosafepoint;
393 dictionary()->add_protection_domain(d_index, d_hash, klass, class_loader,
394 protection_domain, THREAD);
395 }
396 }
397 }
398
399 // We only get here if this thread finds that another thread
400 // has already claimed the placeholder token for the current operation,
401 // but that other thread either never owned or gave up the
402 // object lock
403 // Waits on SystemDictionary_lock to indicate placeholder table updated
404 // On return, caller must recheck placeholder table state
405 //
406 // We only get here if
407 // 1) custom classLoader, i.e. not bootstrap classloader
408 // 2) UnsyncloadClass not set
409 // 3) custom classLoader has broken the class loader objectLock
410 // so another thread got here in parallel
411 //
412 // lockObject must be held.
413 // Complicated dance due to lock ordering:
414 // Must first release the classloader object lock to
415 // allow initial definer to complete the class definition
416 // and to avoid deadlock
417 // Reclaim classloader lock object with same original recursion count
418 // Must release SystemDictionary_lock after notify, since
419 // class loader lock must be claimed before SystemDictionary_lock
420 // to prevent deadlocks
421 //
422 // The notify allows applications that did an untimed wait() on
423 // the classloader object lock to not hang.
424 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
425 assert_lock_strong(SystemDictionary_lock);
426
427 bool calledholdinglock
428 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
429 assert(calledholdinglock,"must hold lock for notify");
430 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
431 ObjectSynchronizer::notifyall(lockObject, THREAD);
432 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
433 SystemDictionary_lock->wait();
434 SystemDictionary_lock->unlock();
435 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
436 SystemDictionary_lock->lock();
437 }
438
439 // If the class in is in the placeholder table, class loading is in progress
440 // For cases where the application changes threads to load classes, it
441 // is critical to ClassCircularity detection that we try loading
442 // the superclass on the same thread internally, so we do parallel
443 // super class loading here.
444 // This also is critical in cases where the original thread gets stalled
445 // even in non-circularity situations.
446 // Note: only one thread can define the class, but multiple can resolve
447 // Note: must call resolve_super_or_fail even if null super -
448 // to force placeholder entry creation for this class for circularity detection
449 // Caller must check for pending exception
450 // Returns non-null klassOop if other thread has completed load
451 // and we are done,
452 // If return null klassOop and no pending exception, the caller must load the class
453 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
454 symbolHandle name, symbolHandle superclassname, Handle class_loader,
455 Handle protection_domain, Handle lockObject, TRAPS) {
456
457 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
458 unsigned int d_hash = dictionary()->compute_hash(name, class_loader);
459 int d_index = dictionary()->hash_to_index(d_hash);
460 unsigned int p_hash = placeholders()->compute_hash(name, class_loader);
461 int p_index = placeholders()->hash_to_index(p_hash);
462
463 // superk is not used, resolve_super called for circularity check only
464 // This code is reached in two situations. One if this thread
465 // is loading the same class twice (e.g. ClassCircularity, or
466 // java.lang.instrument).
467 // The second is if another thread started the resolve_super first
468 // and has not yet finished.
469 // In both cases the original caller will clean up the placeholder
470 // entry on error.
471 klassOop superk = SystemDictionary::resolve_super_or_fail(name,
472 superclassname,
473 class_loader,
474 protection_domain,
475 true,
476 CHECK_(nh));
477 // We don't redefine the class, so we just need to clean up if there
478 // was not an error (don't want to modify any system dictionary
479 // data structures).
480 {
481 MutexLocker mu(SystemDictionary_lock, THREAD);
482 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
483 SystemDictionary_lock->notify_all();
484 }
485
486 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
487 // Serial class loaders and bootstrap classloader do wait for superclass loads
488 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
489 MutexLocker mu(SystemDictionary_lock, THREAD);
490 // Check if classloading completed while we were loading superclass or waiting
491 klassOop check = find_class(d_index, d_hash, name, class_loader);
492 if (check != NULL) {
493 // Klass is already loaded, so just return it
494 return(instanceKlassHandle(THREAD, check));
495 } else {
496 return nh;
497 }
498 }
499
500 // must loop to both handle other placeholder updates
501 // and spurious notifications
502 bool super_load_in_progress = true;
503 PlaceholderEntry* placeholder;
504 while (super_load_in_progress) {
505 MutexLocker mu(SystemDictionary_lock, THREAD);
506 // Check if classloading completed while we were loading superclass or waiting
507 klassOop check = find_class(d_index, d_hash, name, class_loader);
508 if (check != NULL) {
509 // Klass is already loaded, so just return it
510 return(instanceKlassHandle(THREAD, check));
511 } else {
512 placeholder = placeholders()->get_entry(p_index, p_hash, name, class_loader);
513 if (placeholder && placeholder->super_load_in_progress() ){
514 // Before UnsyncloadClass:
515 // We only get here if the application has released the
516 // classloader lock when another thread was in the middle of loading a
517 // superclass/superinterface for this class, and now
518 // this thread is also trying to load this class.
519 // To minimize surprises, the first thread that started to
520 // load a class should be the one to complete the loading
521 // with the classfile it initially expected.
522 // This logic has the current thread wait once it has done
523 // all the superclass/superinterface loading it can, until
524 // the original thread completes the class loading or fails
525 // If it completes we will use the resulting instanceKlass
526 // which we will find below in the systemDictionary.
527 // We also get here for parallel bootstrap classloader
528 if (class_loader.is_null()) {
529 SystemDictionary_lock->wait();
530 } else {
531 double_lock_wait(lockObject, THREAD);
532 }
533 } else {
534 // If not in SD and not in PH, other thread's load must have failed
535 super_load_in_progress = false;
536 }
537 }
538 }
539 return (nh);
540 }
541
542
543 klassOop SystemDictionary::resolve_instance_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS) {
544 assert(class_name.not_null() && !FieldType::is_array(class_name()), "invalid class name");
545 // First check to see if we should remove wrapping L and ;
546 symbolHandle name;
547 if (FieldType::is_obj(class_name())) {
548 ResourceMark rm(THREAD);
549 // Ignore wrapping L and ;.
550 name = oopFactory::new_symbol_handle(class_name()->as_C_string() + 1, class_name()->utf8_length() - 2, CHECK_NULL);
551 } else {
552 name = class_name;
553 }
554
555 // UseNewReflection
556 // Fix for 4474172; see evaluation for more details
557 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
558
559 // Do lookup to see if class already exist and the protection domain
560 // has the right access
561 unsigned int d_hash = dictionary()->compute_hash(name, class_loader);
562 int d_index = dictionary()->hash_to_index(d_hash);
563 klassOop probe = dictionary()->find(d_index, d_hash, name, class_loader,
564 protection_domain, THREAD);
565 if (probe != NULL) return probe;
566
567
568 // Non-bootstrap class loaders will call out to class loader and
569 // define via jvm/jni_DefineClass which will acquire the
570 // class loader object lock to protect against multiple threads
571 // defining the class in parallel by accident.
572 // This lock must be acquired here so the waiter will find
573 // any successful result in the SystemDictionary and not attempt
574 // the define
575 // ParallelCapable Classloaders and the bootstrap classloader,
576 // or all classloaders with UnsyncloadClass do not acquire lock here
577 bool DoObjectLock = true;
578 if (is_parallelCapable(class_loader)) {
579 DoObjectLock = false;
580 }
581
582 unsigned int p_hash = placeholders()->compute_hash(name, class_loader);
583 int p_index = placeholders()->hash_to_index(p_hash);
584
585 // Class is not in SystemDictionary so we have to do loading.
586 // Make sure we are synchronized on the class loader before we proceed
587 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
588 check_loader_lock_contention(lockObject, THREAD);
589 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
590
591 // Check again (after locking) if class already exist in SystemDictionary
592 bool class_has_been_loaded = false;
593 bool super_load_in_progress = false;
594 bool havesupername = false;
595 instanceKlassHandle k;
596 PlaceholderEntry* placeholder;
597 symbolHandle superclassname;
598
599 {
600 MutexLocker mu(SystemDictionary_lock, THREAD);
601 klassOop check = find_class(d_index, d_hash, name, class_loader);
602 if (check != NULL) {
603 // Klass is already loaded, so just return it
604 class_has_been_loaded = true;
605 k = instanceKlassHandle(THREAD, check);
606 } else {
607 placeholder = placeholders()->get_entry(p_index, p_hash, name, class_loader);
608 if (placeholder && placeholder->super_load_in_progress()) {
609 super_load_in_progress = true;
610 if (placeholder->havesupername() == true) {
611 superclassname = symbolHandle(THREAD, placeholder->supername());
612 havesupername = true;
613 }
614 }
615 }
616 }
617
618 // If the class in is in the placeholder table, class loading is in progress
619 if (super_load_in_progress && havesupername==true) {
620 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
621 class_loader, protection_domain, lockObject, THREAD);
622 if (HAS_PENDING_EXCEPTION) {
623 return NULL;
624 }
625 if (!k.is_null()) {
626 class_has_been_loaded = true;
627 }
628 }
629
630 if (!class_has_been_loaded) {
631
632 // add placeholder entry to record loading instance class
633 // Five cases:
634 // All cases need to prevent modifying bootclasssearchpath
635 // in parallel with a classload of same classname
636 // Redefineclasses uses existence of the placeholder for the duration
637 // of the class load to prevent concurrent redefinition of not completely
638 // defined classes.
639 // case 1. traditional classloaders that rely on the classloader object lock
640 // - no other need for LOAD_INSTANCE
641 // case 2. traditional classloaders that break the classloader object lock
642 // as a deadlock workaround. Detection of this case requires that
643 // this check is done while holding the classloader object lock,
644 // and that lock is still held when calling classloader's loadClass.
645 // For these classloaders, we ensure that the first requestor
646 // completes the load and other requestors wait for completion.
647 // case 3. UnsyncloadClass - don't use objectLocker
648 // With this flag, we allow parallel classloading of a
649 // class/classloader pair
650 // case4. Bootstrap classloader - don't own objectLocker
651 // This classloader supports parallelism at the classloader level,
652 // but only allows a single load of a class/classloader pair.
653 // No performance benefit and no deadlock issues.
654 // case 5. parallelCapable user level classloaders - without objectLocker
655 // Allow parallel classloading of a class/classloader pair
656 symbolHandle nullsymbolHandle;
657 bool throw_circularity_error = false;
658 {
659 MutexLocker mu(SystemDictionary_lock, THREAD);
660 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
661 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
662 if (oldprobe) {
663 // only need check_seen_thread once, not on each loop
664 // 6341374 java/lang/Instrument with -Xcomp
665 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
666 throw_circularity_error = true;
667 } else {
668 // case 1: traditional: should never see load_in_progress.
669 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
670
671 // case 4: bootstrap classloader: prevent futile classloading,
672 // wait on first requestor
673 if (class_loader.is_null()) {
674 SystemDictionary_lock->wait();
675 } else {
676 // case 2: traditional with broken classloader lock. wait on first
677 // requestor.
678 double_lock_wait(lockObject, THREAD);
679 }
680 // Check if classloading completed while we were waiting
681 klassOop check = find_class(d_index, d_hash, name, class_loader);
682 if (check != NULL) {
683 // Klass is already loaded, so just return it
684 k = instanceKlassHandle(THREAD, check);
685 class_has_been_loaded = true;
686 }
687 // check if other thread failed to load and cleaned up
688 oldprobe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
689 }
690 }
691 }
692 }
693 // All cases: add LOAD_INSTANCE
694 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
695 // LOAD_INSTANCE in parallel
696 // add placeholder entry even if error - callers will remove on error
697 if (!throw_circularity_error && !class_has_been_loaded) {
698 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, class_loader, PlaceholderTable::LOAD_INSTANCE, nullsymbolHandle, THREAD);
699 // For class loaders that do not acquire the classloader object lock,
700 // if they did not catch another thread holding LOAD_INSTANCE,
701 // need a check analogous to the acquire ObjectLocker/find_class
702 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
703 // one final check if the load has already completed
704 // class loaders holding the ObjectLock shouldn't find the class here
705 klassOop check = find_class(d_index, d_hash, name, class_loader);
706 if (check != NULL) {
707 // Klass is already loaded, so just return it
708 k = instanceKlassHandle(THREAD, check);
709 class_has_been_loaded = true;
710 newprobe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);
711 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
712 SystemDictionary_lock->notify_all();
713 }
714 }
715 }
716 // must throw error outside of owning lock
717 if (throw_circularity_error) {
718 ResourceMark rm(THREAD);
719 THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
720 }
721
722 if (!class_has_been_loaded) {
723
724 // Do actual loading
725 k = load_instance_class(name, class_loader, THREAD);
726
727 // For UnsyncloadClass and AllowParallelDefineClass only:
728 // If they got a linkageError, check if a parallel class load succeeded.
729 // If it did, then for bytecode resolution the specification requires
730 // that we return the same result we did for the other thread, i.e. the
731 // successfully loaded instanceKlass
732 // Should not get here for classloaders that support parallelism
733 // with the new cleaner mechanism
734 // Bootstrap goes through here to allow for an extra guarantee check
735 if (UnsyncloadClass || (class_loader.is_null())) {
736 if (k.is_null() && HAS_PENDING_EXCEPTION
737 && PENDING_EXCEPTION->is_a(SystemDictionary::linkageError_klass())) {
738 MutexLocker mu(SystemDictionary_lock, THREAD);
739 klassOop check = find_class(d_index, d_hash, name, class_loader);
740 if (check != NULL) {
741 // Klass is already loaded, so just use it
742 k = instanceKlassHandle(THREAD, check);
743 CLEAR_PENDING_EXCEPTION;
744 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
745 }
746 }
747 }
748
749 // clean up placeholder entries for success or error
750 // This cleans up LOAD_INSTANCE entries
751 // It also cleans up LOAD_SUPER entries on errors from
752 // calling load_instance_class
753 {
754 MutexLocker mu(SystemDictionary_lock, THREAD);
755 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
756 if (probe != NULL) {
757 probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);
758 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
759 SystemDictionary_lock->notify_all();
760 }
761 }
762
763 // If everything was OK (no exceptions, no null return value), and
764 // class_loader is NOT the defining loader, do a little more bookkeeping.
765 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
766 k->class_loader() != class_loader()) {
767
768 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
769
770 // Need to check for a PENDING_EXCEPTION again; check_constraints
771 // can throw and doesn't use the CHECK macro.
772 if (!HAS_PENDING_EXCEPTION) {
773 { // Grabbing the Compile_lock prevents systemDictionary updates
774 // during compilations.
775 MutexLocker mu(Compile_lock, THREAD);
776 update_dictionary(d_index, d_hash, p_index, p_hash,
777 k, class_loader, THREAD);
778 }
779 if (JvmtiExport::should_post_class_load()) {
780 Thread *thread = THREAD;
781 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
782 JvmtiExport::post_class_load((JavaThread *) thread, k());
783 }
784 }
785 }
786 if (HAS_PENDING_EXCEPTION || k.is_null()) {
787 // On error, clean up placeholders
788 {
789 MutexLocker mu(SystemDictionary_lock, THREAD);
790 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
791 SystemDictionary_lock->notify_all();
792 }
793 return NULL;
794 }
795 }
796 }
797
798 #ifdef ASSERT
799 {
800 Handle loader (THREAD, k->class_loader());
801 MutexLocker mu(SystemDictionary_lock, THREAD);
802 oop kk = find_class_or_placeholder(name, loader);
803 assert(kk == k(), "should be present in dictionary");
804 }
805 #endif
806
807 // return if the protection domain in NULL
808 if (protection_domain() == NULL) return k();
809
810 // Check the protection domain has the right access
811 {
812 MutexLocker mu(SystemDictionary_lock, THREAD);
813 // Note that we have an entry, and entries can be deleted only during GC,
814 // so we cannot allow GC to occur while we're holding this entry.
815 // We're using a No_Safepoint_Verifier to catch any place where we
816 // might potentially do a GC at all.
817 // SystemDictionary::do_unloading() asserts that classes are only
818 // unloaded at a safepoint.
819 No_Safepoint_Verifier nosafepoint;
820 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
821 class_loader,
822 protection_domain)) {
823 return k();
824 }
825 }
826
827 // Verify protection domain. If it fails an exception is thrown
828 validate_protection_domain(k, class_loader, protection_domain, CHECK_(klassOop(NULL)));
829
830 return k();
831 }
832
833
834 // This routine does not lock the system dictionary.
835 //
836 // Since readers don't hold a lock, we must make sure that system
837 // dictionary entries are only removed at a safepoint (when only one
838 // thread is running), and are added to in a safe way (all links must
839 // be updated in an MT-safe manner).
840 //
841 // Callers should be aware that an entry could be added just after
842 // _dictionary->bucket(index) is read here, so the caller will not see
843 // the new entry.
844
845 klassOop SystemDictionary::find(symbolHandle class_name,
846 Handle class_loader,
847 Handle protection_domain,
848 TRAPS) {
849
850 // UseNewReflection
851 // The result of this call should be consistent with the result
852 // of the call to resolve_instance_class_or_null().
853 // See evaluation 6790209 and 4474172 for more details.
854 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
855
856 unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);
857 int d_index = dictionary()->hash_to_index(d_hash);
858
859 {
860 // Note that we have an entry, and entries can be deleted only during GC,
861 // so we cannot allow GC to occur while we're holding this entry.
862 // We're using a No_Safepoint_Verifier to catch any place where we
863 // might potentially do a GC at all.
864 // SystemDictionary::do_unloading() asserts that classes are only
865 // unloaded at a safepoint.
866 No_Safepoint_Verifier nosafepoint;
867 return dictionary()->find(d_index, d_hash, class_name, class_loader,
868 protection_domain, THREAD);
869 }
870 }
871
872
873 // Look for a loaded instance or array klass by name. Do not do any loading.
874 // return NULL in case of error.
875 klassOop SystemDictionary::find_instance_or_array_klass(symbolHandle class_name,
876 Handle class_loader,
877 Handle protection_domain,
878 TRAPS) {
879 klassOop k = NULL;
880 assert(class_name() != NULL, "class name must be non NULL");
881
882 // Try to get one of the well-known klasses.
883 if (LinkWellKnownClasses) {
884 k = find_well_known_klass(class_name());
885 if (k != NULL) {
886 return k;
887 }
888 }
889
890 if (FieldType::is_array(class_name())) {
891 // The name refers to an array. Parse the name.
892 jint dimension;
893 symbolOop object_key;
894
895 // dimension and object_key are assigned as a side-effect of this call
896 BasicType t = FieldType::get_array_info(class_name(), &dimension,
897 &object_key, CHECK_(NULL));
898 if (t != T_OBJECT) {
899 k = Universe::typeArrayKlassObj(t);
900 } else {
901 symbolHandle h_key(THREAD, object_key);
902 k = SystemDictionary::find(h_key, class_loader, protection_domain, THREAD);
903 }
904 if (k != NULL) {
905 k = Klass::cast(k)->array_klass_or_null(dimension);
906 }
907 } else {
908 k = find(class_name, class_loader, protection_domain, THREAD);
909 }
910 return k;
911 }
912
913 // Quick range check for names of well-known classes:
914 static symbolOop wk_klass_name_limits[2] = {NULL, NULL};
915
916 #ifndef PRODUCT
917 static int find_wkk_calls, find_wkk_probes, find_wkk_wins;
918 // counts for "hello world": 3983, 1616, 1075
919 // => 60% hit after limit guard, 25% total win rate
920 #endif
921
922 klassOop SystemDictionary::find_well_known_klass(symbolOop class_name) {
923 // A bounds-check on class_name will quickly get a negative result.
924 NOT_PRODUCT(find_wkk_calls++);
925 if (class_name >= wk_klass_name_limits[0] &&
926 class_name <= wk_klass_name_limits[1]) {
927 NOT_PRODUCT(find_wkk_probes++);
928 vmSymbols::SID sid = vmSymbols::find_sid(class_name);
929 if (sid != vmSymbols::NO_SID) {
930 klassOop k = NULL;
931 switch (sid) {
932 #define WK_KLASS_CASE(name, symbol, ignore_option) \
933 case vmSymbols::VM_SYMBOL_ENUM_NAME(symbol): \
934 k = WK_KLASS(name); break;
935 WK_KLASSES_DO(WK_KLASS_CASE)
936 #undef WK_KLASS_CASE
937 }
938 NOT_PRODUCT(if (k != NULL) find_wkk_wins++);
939 return k;
940 }
941 }
942 return NULL;
943 }
944
945 // Note: this method is much like resolve_from_stream, but
946 // updates no supplemental data structures.
947 // TODO consolidate the two methods with a helper routine?
948 klassOop SystemDictionary::parse_stream(symbolHandle class_name,
949 Handle class_loader,
950 Handle protection_domain,
951 ClassFileStream* st,
952 KlassHandle host_klass,
953 GrowableArray<Handle>* cp_patches,
954 TRAPS) {
955 symbolHandle parsed_name;
956
957 // Parse the stream. Note that we do this even though this klass might
958 // already be present in the SystemDictionary, otherwise we would not
959 // throw potential ClassFormatErrors.
960 //
961 // Note: "name" is updated.
962 // Further note: a placeholder will be added for this class when
963 // super classes are loaded (resolve_super_or_fail). We expect this
964 // to be called for all classes but java.lang.Object; and we preload
965 // java.lang.Object through resolve_or_fail, not this path.
966
967 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
968 class_loader,
969 protection_domain,
970 host_klass,
971 cp_patches,
972 parsed_name,
973 true,
974 THREAD);
975
976
977 // We don't redefine the class, so we just need to clean up whether there
978 // was an error or not (don't want to modify any system dictionary
979 // data structures).
980 // Parsed name could be null if we threw an error before we got far
981 // enough along to parse it -- in that case, there is nothing to clean up.
982 if (!parsed_name.is_null()) {
983 unsigned int p_hash = placeholders()->compute_hash(parsed_name,
984 class_loader);
985 int p_index = placeholders()->hash_to_index(p_hash);
986 {
987 MutexLocker mu(SystemDictionary_lock, THREAD);
988 placeholders()->find_and_remove(p_index, p_hash, parsed_name, class_loader, THREAD);
989 SystemDictionary_lock->notify_all();
990 }
991 }
992
993 if (host_klass.not_null() && k.not_null()) {
994 assert(AnonymousClasses, "");
995 // If it's anonymous, initialize it now, since nobody else will.
996 k->set_host_klass(host_klass());
997
998 {
999 MutexLocker mu_r(Compile_lock, THREAD);
1000
1001 // Add to class hierarchy, initialize vtables, and do possible
1002 // deoptimizations.
1003 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1004
1005 // But, do not add to system dictionary.
1006 }
1007
1008 k->eager_initialize(THREAD);
1009
1010 // notify jvmti
1011 if (JvmtiExport::should_post_class_load()) {
1012 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1013 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1014 }
1015 }
1016
1017 return k();
1018 }
1019
1020 // Add a klass to the system from a stream (called by jni_DefineClass and
1021 // JVM_DefineClass).
1022 // Note: class_name can be NULL. In that case we do not know the name of
1023 // the class until we have parsed the stream.
1024
1025 klassOop SystemDictionary::resolve_from_stream(symbolHandle class_name,
1026 Handle class_loader,
1027 Handle protection_domain,
1028 ClassFileStream* st,
1029 bool verify,
1030 TRAPS) {
1031
1032 // Classloaders that support parallelism, e.g. bootstrap classloader,
1033 // or all classloaders with UnsyncloadClass do not acquire lock here
1034 bool DoObjectLock = true;
1035 if (is_parallelCapable(class_loader)) {
1036 DoObjectLock = false;
1037 }
1038
1039 // Make sure we are synchronized on the class loader before we proceed
1040 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1041 check_loader_lock_contention(lockObject, THREAD);
1042 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1043
1044 symbolHandle parsed_name;
1045
1046 // Parse the stream. Note that we do this even though this klass might
1047 // already be present in the SystemDictionary, otherwise we would not
1048 // throw potential ClassFormatErrors.
1049 //
1050 // Note: "name" is updated.
1051 // Further note: a placeholder will be added for this class when
1052 // super classes are loaded (resolve_super_or_fail). We expect this
1053 // to be called for all classes but java.lang.Object; and we preload
1054 // java.lang.Object through resolve_or_fail, not this path.
1055
1056 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1057 class_loader,
1058 protection_domain,
1059 parsed_name,
1060 verify,
1061 THREAD);
1062
1063 const char* pkg = "java/";
1064 if (!HAS_PENDING_EXCEPTION &&
1065 !class_loader.is_null() &&
1066 !parsed_name.is_null() &&
1067 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1068 // It is illegal to define classes in the "java." package from
1069 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1070 ResourceMark rm(THREAD);
1071 char* name = parsed_name->as_C_string();
1072 char* index = strrchr(name, '/');
1073 *index = '\0'; // chop to just the package name
1074 while ((index = strchr(name, '/')) != NULL) {
1075 *index = '.'; // replace '/' with '.' in package name
1076 }
1077 const char* fmt = "Prohibited package name: %s";
1078 size_t len = strlen(fmt) + strlen(name);
1079 char* message = NEW_RESOURCE_ARRAY(char, len);
1080 jio_snprintf(message, len, fmt, name);
1081 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1082 vmSymbols::java_lang_SecurityException(), message);
1083 }
1084
1085 if (!HAS_PENDING_EXCEPTION) {
1086 assert(!parsed_name.is_null(), "Sanity");
1087 assert(class_name.is_null() || class_name() == parsed_name(),
1088 "name mismatch");
1089 // Verification prevents us from creating names with dots in them, this
1090 // asserts that that's the case.
1091 assert(is_internal_format(parsed_name),
1092 "external class name format used internally");
1093
1094 // Add class just loaded
1095 // If a class loader supports parallel classloading handle parallel define requests
1096 // find_or_define_instance_class may return a different instanceKlass
1097 if (is_parallelCapable(class_loader)) {
1098 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1099 } else {
1100 define_instance_class(k, THREAD);
1101 }
1102 }
1103
1104 // If parsing the class file or define_instance_class failed, we
1105 // need to remove the placeholder added on our behalf. But we
1106 // must make sure parsed_name is valid first (it won't be if we had
1107 // a format error before the class was parsed far enough to
1108 // find the name).
1109 if (HAS_PENDING_EXCEPTION && !parsed_name.is_null()) {
1110 unsigned int p_hash = placeholders()->compute_hash(parsed_name,
1111 class_loader);
1112 int p_index = placeholders()->hash_to_index(p_hash);
1113 {
1114 MutexLocker mu(SystemDictionary_lock, THREAD);
1115 placeholders()->find_and_remove(p_index, p_hash, parsed_name, class_loader, THREAD);
1116 SystemDictionary_lock->notify_all();
1117 }
1118 return NULL;
1119 }
1120
1121 // Make sure that we didn't leave a place holder in the
1122 // SystemDictionary; this is only done on success
1123 debug_only( {
1124 if (!HAS_PENDING_EXCEPTION) {
1125 assert(!parsed_name.is_null(), "parsed_name is still null?");
1126 symbolHandle h_name (THREAD, k->name());
1127 Handle h_loader (THREAD, k->class_loader());
1128
1129 MutexLocker mu(SystemDictionary_lock, THREAD);
1130
1131 oop check = find_class_or_placeholder(parsed_name, class_loader);
1132 assert(check == k(), "should be present in the dictionary");
1133
1134 oop check2 = find_class_or_placeholder(h_name, h_loader);
1135 assert(check == check2, "name inconsistancy in SystemDictionary");
1136 }
1137 } );
1138
1139 return k();
1140 }
1141
1142
1143 void SystemDictionary::set_shared_dictionary(HashtableBucket* t, int length,
1144 int number_of_entries) {
1145 assert(length == _nof_buckets * sizeof(HashtableBucket),
1146 "bad shared dictionary size.");
1147 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1148 }
1149
1150
1151 // If there is a shared dictionary, then find the entry for the
1152 // given shared system class, if any.
1153
1154 klassOop SystemDictionary::find_shared_class(symbolHandle class_name) {
1155 if (shared_dictionary() != NULL) {
1156 unsigned int d_hash = dictionary()->compute_hash(class_name, Handle());
1157 int d_index = dictionary()->hash_to_index(d_hash);
1158 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1159 } else {
1160 return NULL;
1161 }
1162 }
1163
1164
1165 // Load a class from the shared spaces (found through the shared system
1166 // dictionary). Force the superclass and all interfaces to be loaded.
1167 // Update the class definition to include sibling classes and no
1168 // subclasses (yet). [Classes in the shared space are not part of the
1169 // object hierarchy until loaded.]
1170
1171 instanceKlassHandle SystemDictionary::load_shared_class(
1172 symbolHandle class_name, Handle class_loader, TRAPS) {
1173 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1174 return load_shared_class(ik, class_loader, THREAD);
1175 }
1176
1177 // Note well! Changes to this method may affect oop access order
1178 // in the shared archive. Please take care to not make changes that
1179 // adversely affect cold start time by changing the oop access order
1180 // that is specified in dump.cpp MarkAndMoveOrderedReadOnly and
1181 // MarkAndMoveOrderedReadWrite closures.
1182 instanceKlassHandle SystemDictionary::load_shared_class(
1183 instanceKlassHandle ik, Handle class_loader, TRAPS) {
1184 assert(class_loader.is_null(), "non-null classloader for shared class?");
1185 if (ik.not_null()) {
1186 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1187 symbolHandle class_name(THREAD, ik->name());
1188
1189 // Found the class, now load the superclass and interfaces. If they
1190 // are shared, add them to the main system dictionary and reset
1191 // their hierarchy references (supers, subs, and interfaces).
1192
1193 if (ik->super() != NULL) {
1194 symbolHandle cn(THREAD, ik->super()->klass_part()->name());
1195 resolve_super_or_fail(class_name, cn,
1196 class_loader, Handle(), true, CHECK_(nh));
1197 }
1198
1199 objArrayHandle interfaces (THREAD, ik->local_interfaces());
1200 int num_interfaces = interfaces->length();
1201 for (int index = 0; index < num_interfaces; index++) {
1202 klassOop k = klassOop(interfaces->obj_at(index));
1203
1204 // Note: can not use instanceKlass::cast here because
1205 // interfaces' instanceKlass's C++ vtbls haven't been
1206 // reinitialized yet (they will be once the interface classes
1207 // are loaded)
1208 symbolHandle name (THREAD, k->klass_part()->name());
1209 resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(nh));
1210 }
1211
1212 // Adjust methods to recover missing data. They need addresses for
1213 // interpreter entry points and their default native method address
1214 // must be reset.
1215
1216 // Updating methods must be done under a lock so multiple
1217 // threads don't update these in parallel
1218 // Shared classes are all currently loaded by the bootstrap
1219 // classloader, so this will never cause a deadlock on
1220 // a custom class loader lock.
1221
1222 {
1223 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1224 check_loader_lock_contention(lockObject, THREAD);
1225 ObjectLocker ol(lockObject, THREAD, true);
1226
1227 objArrayHandle methods (THREAD, ik->methods());
1228 int num_methods = methods->length();
1229 for (int index2 = 0; index2 < num_methods; ++index2) {
1230 methodHandle m(THREAD, methodOop(methods->obj_at(index2)));
1231 m()->link_method(m, CHECK_(nh));
1232 }
1233 }
1234
1235 if (TraceClassLoading) {
1236 ResourceMark rm;
1237 tty->print("[Loaded %s", ik->external_name());
1238 tty->print(" from shared objects file");
1239 tty->print_cr("]");
1240 }
1241 // notify a class loaded from shared object
1242 ClassLoadingService::notify_class_loaded(instanceKlass::cast(ik()),
1243 true /* shared class */);
1244 }
1245 return ik;
1246 }
1247
1248 #ifdef KERNEL
1249 // Some classes on the bootstrap class path haven't been installed on the
1250 // system yet. Call the DownloadManager method to make them appear in the
1251 // bootstrap class path and try again to load the named class.
1252 // Note that with delegation class loaders all classes in another loader will
1253 // first try to call this so it'd better be fast!!
1254 static instanceKlassHandle download_and_retry_class_load(
1255 symbolHandle class_name,
1256 TRAPS) {
1257
1258 klassOop dlm = SystemDictionary::sun_jkernel_DownloadManager_klass();
1259 instanceKlassHandle nk;
1260
1261 // If download manager class isn't loaded just return.
1262 if (dlm == NULL) return nk;
1263
1264 { HandleMark hm(THREAD);
1265 ResourceMark rm(THREAD);
1266 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nk));
1267 Handle class_string = java_lang_String::externalize_classname(s, CHECK_(nk));
1268
1269 // return value
1270 JavaValue result(T_OBJECT);
1271
1272 // Call the DownloadManager. We assume that it has a lock because
1273 // multiple classes could be not found and downloaded at the same time.
1274 // class sun.misc.DownloadManager;
1275 // public static String getBootClassPathEntryForClass(String className);
1276 JavaCalls::call_static(&result,
1277 KlassHandle(THREAD, dlm),
1278 vmSymbolHandles::getBootClassPathEntryForClass_name(),
1279 vmSymbolHandles::string_string_signature(),
1280 class_string,
1281 CHECK_(nk));
1282
1283 // Get result.string and add to bootclasspath
1284 assert(result.get_type() == T_OBJECT, "just checking");
1285 oop obj = (oop) result.get_jobject();
1286 if (obj == NULL) { return nk; }
1287
1288 Handle h_obj(THREAD, obj);
1289 char* new_class_name = java_lang_String::as_platform_dependent_str(h_obj,
1290 CHECK_(nk));
1291
1292 // lock the loader
1293 // we use this lock because JVMTI does.
1294 Handle loader_lock(THREAD, SystemDictionary::system_loader_lock());
1295
1296 ObjectLocker ol(loader_lock, THREAD);
1297 // add the file to the bootclasspath
1298 ClassLoader::update_class_path_entry_list(new_class_name, true);
1299 } // end HandleMark
1300
1301 if (TraceClassLoading) {
1302 ClassLoader::print_bootclasspath();
1303 }
1304 return ClassLoader::load_classfile(class_name, CHECK_(nk));
1305 }
1306 #endif // KERNEL
1307
1308
1309 instanceKlassHandle SystemDictionary::load_instance_class(symbolHandle class_name, Handle class_loader, TRAPS) {
1310 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1311 if (class_loader.is_null()) {
1312
1313 // Search the shared system dictionary for classes preloaded into the
1314 // shared spaces.
1315 instanceKlassHandle k;
1316 {
1317 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1318 k = load_shared_class(class_name, class_loader, THREAD);
1319 }
1320
1321 if (k.is_null()) {
1322 // Use VM class loader
1323 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1324 k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1325 }
1326
1327 #ifdef KERNEL
1328 // If the VM class loader has failed to load the class, call the
1329 // DownloadManager class to make it magically appear on the classpath
1330 // and try again. This is only configured with the Kernel VM.
1331 if (k.is_null()) {
1332 k = download_and_retry_class_load(class_name, CHECK_(nh));
1333 }
1334 #endif // KERNEL
1335
1336 // find_or_define_instance_class may return a different instanceKlass
1337 if (!k.is_null()) {
1338 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1339 }
1340 return k;
1341 } else {
1342 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1343 ResourceMark rm(THREAD);
1344
1345 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1346 JavaThread* jt = (JavaThread*) THREAD;
1347
1348 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1349 ClassLoader::perf_app_classload_selftime(),
1350 ClassLoader::perf_app_classload_count(),
1351 jt->get_thread_stat()->perf_recursion_counts_addr(),
1352 jt->get_thread_stat()->perf_timers_addr(),
1353 PerfClassTraceTime::CLASS_LOAD);
1354
1355 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1356 // Translate to external class name format, i.e., convert '/' chars to '.'
1357 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1358
1359 JavaValue result(T_OBJECT);
1360
1361 KlassHandle spec_klass (THREAD, SystemDictionary::classloader_klass());
1362
1363 // Call public unsynchronized loadClass(String) directly for all class loaders
1364 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1365 // acquire a class-name based lock rather than the class loader object lock.
1366 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1367 // so the call to loadClassInternal() was not required.
1368 //
1369 // UnsyncloadClass flag means both call loadClass(String) and do
1370 // not acquire the class loader lock even for class loaders that are
1371 // not parallelCapable. This was a risky transitional
1372 // flag for diagnostic purposes only. It is risky to call
1373 // custom class loaders without synchronization.
1374 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1375 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1376 // Do NOT assume this will be supported in future releases.
1377 //
1378 // Added MustCallLoadClassInternal in case we discover in the field
1379 // a customer that counts on this call
1380 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1381 JavaCalls::call_special(&result,
1382 class_loader,
1383 spec_klass,
1384 vmSymbolHandles::loadClassInternal_name(),
1385 vmSymbolHandles::string_class_signature(),
1386 string,
1387 CHECK_(nh));
1388 } else {
1389 JavaCalls::call_virtual(&result,
1390 class_loader,
1391 spec_klass,
1392 vmSymbolHandles::loadClass_name(),
1393 vmSymbolHandles::string_class_signature(),
1394 string,
1395 CHECK_(nh));
1396 }
1397
1398 assert(result.get_type() == T_OBJECT, "just checking");
1399 oop obj = (oop) result.get_jobject();
1400
1401 // Primitive classes return null since forName() can not be
1402 // used to obtain any of the Class objects representing primitives or void
1403 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1404 instanceKlassHandle k =
1405 instanceKlassHandle(THREAD, java_lang_Class::as_klassOop(obj));
1406 // For user defined Java class loaders, check that the name returned is
1407 // the same as that requested. This check is done for the bootstrap
1408 // loader when parsing the class file.
1409 if (class_name() == k->name()) {
1410 return k;
1411 }
1412 }
1413 // Class is not found or has the wrong name, return NULL
1414 return nh;
1415 }
1416 }
1417
1418 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1419
1420 Handle class_loader_h(THREAD, k->class_loader());
1421
1422 // for bootstrap and other parallel classloaders don't acquire lock,
1423 // use placeholder token
1424 // If a parallelCapable class loader calls define_instance_class instead of
1425 // find_or_define_instance_class to get here, we have a timing
1426 // hole with systemDictionary updates and check_constraints
1427 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1428 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1429 compute_loader_lock_object(class_loader_h, THREAD)),
1430 "define called without lock");
1431 }
1432
1433 // Check class-loading constraints. Throw exception if violation is detected.
1434 // Grabs and releases SystemDictionary_lock
1435 // The check_constraints/find_class call and update_dictionary sequence
1436 // must be "atomic" for a specific class/classloader pair so we never
1437 // define two different instanceKlasses for that class/classloader pair.
1438 // Existing classloaders will call define_instance_class with the
1439 // classloader lock held
1440 // Parallel classloaders will call find_or_define_instance_class
1441 // which will require a token to perform the define class
1442 symbolHandle name_h(THREAD, k->name());
1443 unsigned int d_hash = dictionary()->compute_hash(name_h, class_loader_h);
1444 int d_index = dictionary()->hash_to_index(d_hash);
1445 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1446
1447 // Register class just loaded with class loader (placed in Vector)
1448 // Note we do this before updating the dictionary, as this can
1449 // fail with an OutOfMemoryError (if it does, we will *not* put this
1450 // class in the dictionary and will not update the class hierarchy).
1451 if (k->class_loader() != NULL) {
1452 methodHandle m(THREAD, Universe::loader_addClass_method());
1453 JavaValue result(T_VOID);
1454 JavaCallArguments args(class_loader_h);
1455 args.push_oop(Handle(THREAD, k->java_mirror()));
1456 JavaCalls::call(&result, m, &args, CHECK);
1457 }
1458
1459 // Add the new class. We need recompile lock during update of CHA.
1460 {
1461 unsigned int p_hash = placeholders()->compute_hash(name_h, class_loader_h);
1462 int p_index = placeholders()->hash_to_index(p_hash);
1463
1464 MutexLocker mu_r(Compile_lock, THREAD);
1465
1466 // Add to class hierarchy, initialize vtables, and do possible
1467 // deoptimizations.
1468 add_to_hierarchy(k, CHECK); // No exception, but can block
1469
1470 // Add to systemDictionary - so other classes can see it.
1471 // Grabs and releases SystemDictionary_lock
1472 update_dictionary(d_index, d_hash, p_index, p_hash,
1473 k, class_loader_h, THREAD);
1474 }
1475 k->eager_initialize(THREAD);
1476
1477 // notify jvmti
1478 if (JvmtiExport::should_post_class_load()) {
1479 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1480 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1481
1482 }
1483 }
1484
1485 // Support parallel classloading
1486 // Initial implementation for bootstrap classloader
1487 // For custom class loaders that support parallel classloading,
1488 // With AllowParallelDefine flag==true, in case they do not synchronize around
1489 // FindLoadedClass/DefineClass, calls, we check for parallel
1490 // loading for them, wait if a defineClass is in progress
1491 // and return the initial requestor's results
1492 // With AllowParallelDefine flag==false, call through to define_instance_class
1493 // which will throw LinkageError: duplicate class definition.
1494 // For better performance, the class loaders should synchronize
1495 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1496 // potentially waste time reading and parsing the bytestream.
1497 // Note: VM callers should ensure consistency of k/class_name,class_loader
1498 instanceKlassHandle SystemDictionary::find_or_define_instance_class(symbolHandle class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1499
1500 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1501 symbolHandle name_h(THREAD, k->name()); // passed in class_name may be null
1502
1503 unsigned int d_hash = dictionary()->compute_hash(name_h, class_loader);
1504 int d_index = dictionary()->hash_to_index(d_hash);
1505
1506 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1507 unsigned int p_hash = placeholders()->compute_hash(name_h, class_loader);
1508 int p_index = placeholders()->hash_to_index(p_hash);
1509 PlaceholderEntry* probe;
1510
1511 {
1512 MutexLocker mu(SystemDictionary_lock, THREAD);
1513 // First check if class already defined
1514 klassOop check = find_class(d_index, d_hash, name_h, class_loader);
1515 if (check != NULL) {
1516 return(instanceKlassHandle(THREAD, check));
1517 }
1518
1519 // Acquire define token for this class/classloader
1520 symbolHandle nullsymbolHandle;
1521 probe = placeholders()->find_and_add(p_index, p_hash, name_h, class_loader, PlaceholderTable::DEFINE_CLASS, nullsymbolHandle, THREAD);
1522 // Wait if another thread defining in parallel
1523 // All threads wait - even those that will throw duplicate class: otherwise
1524 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1525 // if other thread has not finished updating dictionary
1526 while (probe->definer() != NULL) {
1527 SystemDictionary_lock->wait();
1528 }
1529 // Only special cases allow parallel defines and can use other thread's results
1530 // Other cases fall through, and may run into duplicate defines
1531 // caught by finding an entry in the SystemDictionary
1532 if ((UnsyncloadClass || AllowParallelDefineClass) && (probe->instanceKlass() != NULL)) {
1533 probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);
1534 placeholders()->find_and_remove(p_index, p_hash, name_h, class_loader, THREAD);
1535 SystemDictionary_lock->notify_all();
1536 #ifdef ASSERT
1537 klassOop check = find_class(d_index, d_hash, name_h, class_loader);
1538 assert(check != NULL, "definer missed recording success");
1539 #endif
1540 return(instanceKlassHandle(THREAD, probe->instanceKlass()));
1541 } else {
1542 // This thread will define the class (even if earlier thread tried and had an error)
1543 probe->set_definer(THREAD);
1544 }
1545 }
1546
1547 define_instance_class(k, THREAD);
1548
1549 Handle linkage_exception = Handle(); // null handle
1550
1551 // definer must notify any waiting threads
1552 {
1553 MutexLocker mu(SystemDictionary_lock, THREAD);
1554 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, class_loader);
1555 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1556 if (probe != NULL) {
1557 if (HAS_PENDING_EXCEPTION) {
1558 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1559 CLEAR_PENDING_EXCEPTION;
1560 } else {
1561 probe->set_instanceKlass(k());
1562 }
1563 probe->set_definer(NULL);
1564 probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);
1565 placeholders()->find_and_remove(p_index, p_hash, name_h, class_loader, THREAD);
1566 SystemDictionary_lock->notify_all();
1567 }
1568 }
1569
1570 // Can't throw exception while holding lock due to rank ordering
1571 if (linkage_exception() != NULL) {
1572 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1573 }
1574
1575 return k;
1576 }
1577 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1578 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1579 if (class_loader.is_null()) {
1580 return Handle(THREAD, _system_loader_lock_obj);
1581 } else {
1582 return class_loader;
1583 }
1584 }
1585
1586 // This method is added to check how often we have to wait to grab loader
1587 // lock. The results are being recorded in the performance counters defined in
1588 // ClassLoader::_sync_systemLoaderLockContentionRate and
1589 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1590 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1591 if (!UsePerfData) {
1592 return;
1593 }
1594
1595 assert(!loader_lock.is_null(), "NULL lock object");
1596
1597 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1598 == ObjectSynchronizer::owner_other) {
1599 // contention will likely happen, so increment the corresponding
1600 // contention counter.
1601 if (loader_lock() == _system_loader_lock_obj) {
1602 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1603 } else {
1604 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1605 }
1606 }
1607 }
1608
1609 // ----------------------------------------------------------------------------
1610 // Lookup
1611
1612 klassOop SystemDictionary::find_class(int index, unsigned int hash,
1613 symbolHandle class_name,
1614 Handle class_loader) {
1615 assert_locked_or_safepoint(SystemDictionary_lock);
1616 assert (index == dictionary()->index_for(class_name, class_loader),
1617 "incorrect index?");
1618
1619 klassOop k = dictionary()->find_class(index, hash, class_name, class_loader);
1620 return k;
1621 }
1622
1623
1624 // Basic find on classes in the midst of being loaded
1625 symbolOop SystemDictionary::find_placeholder(int index, unsigned int hash,
1626 symbolHandle class_name,
1627 Handle class_loader) {
1628 assert_locked_or_safepoint(SystemDictionary_lock);
1629
1630 return placeholders()->find_entry(index, hash, class_name, class_loader);
1631 }
1632
1633
1634 // Used for assertions and verification only
1635 oop SystemDictionary::find_class_or_placeholder(symbolHandle class_name,
1636 Handle class_loader) {
1637 #ifndef ASSERT
1638 guarantee(VerifyBeforeGC ||
1639 VerifyDuringGC ||
1640 VerifyBeforeExit ||
1641 VerifyAfterGC, "too expensive");
1642 #endif
1643 assert_locked_or_safepoint(SystemDictionary_lock);
1644 symbolOop class_name_ = class_name();
1645 oop class_loader_ = class_loader();
1646
1647 // First look in the loaded class array
1648 unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);
1649 int d_index = dictionary()->hash_to_index(d_hash);
1650 oop lookup = find_class(d_index, d_hash, class_name, class_loader);
1651
1652 if (lookup == NULL) {
1653 // Next try the placeholders
1654 unsigned int p_hash = placeholders()->compute_hash(class_name,class_loader);
1655 int p_index = placeholders()->hash_to_index(p_hash);
1656 lookup = find_placeholder(p_index, p_hash, class_name, class_loader);
1657 }
1658
1659 return lookup;
1660 }
1661
1662
1663 // Get the next class in the diictionary.
1664 klassOop SystemDictionary::try_get_next_class() {
1665 return dictionary()->try_get_next_class();
1666 }
1667
1668
1669 // ----------------------------------------------------------------------------
1670 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1671 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1672 // before a new class is used.
1673
1674 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1675 assert(k.not_null(), "just checking");
1676 // Link into hierachy. Make sure the vtables are initialized before linking into
1677 k->append_to_sibling_list(); // add to superklass/sibling list
1678 k->process_interfaces(THREAD); // handle all "implements" declarations
1679 k->set_init_state(instanceKlass::loaded);
1680 // Now flush all code that depended on old class hierarchy.
1681 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1682 // Also, first reinitialize vtable because it may have gotten out of synch
1683 // while the new class wasn't connected to the class hierarchy.
1684 Universe::flush_dependents_on(k);
1685 }
1686
1687
1688 // ----------------------------------------------------------------------------
1689 // GC support
1690
1691 // Following roots during mark-sweep is separated in two phases.
1692 //
1693 // The first phase follows preloaded classes and all other system
1694 // classes, since these will never get unloaded anyway.
1695 //
1696 // The second phase removes (unloads) unreachable classes from the
1697 // system dictionary and follows the remaining classes' contents.
1698
1699 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1700 // Follow preloaded classes/mirrors and system loader object
1701 blk->do_oop(&_java_system_loader);
1702 preloaded_oops_do(blk);
1703 always_strong_classes_do(blk);
1704 }
1705
1706
1707 void SystemDictionary::always_strong_classes_do(OopClosure* blk) {
1708 // Follow all system classes and temporary placeholders in dictionary
1709 dictionary()->always_strong_classes_do(blk);
1710
1711 // Placeholders. These are *always* strong roots, as they
1712 // represent classes we're actively loading.
1713 placeholders_do(blk);
1714
1715 // Visit extra methods
1716 if (invoke_method_table() != NULL)
1717 invoke_method_table()->oops_do(blk);
1718
1719 // Loader constraints. We must keep the symbolOop used in the name alive.
1720 constraints()->always_strong_classes_do(blk);
1721
1722 // Resolution errors keep the symbolOop for the error alive
1723 resolution_errors()->always_strong_classes_do(blk);
1724 }
1725
1726
1727 void SystemDictionary::placeholders_do(OopClosure* blk) {
1728 placeholders()->oops_do(blk);
1729 }
1730
1731
1732 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
1733 bool result = dictionary()->do_unloading(is_alive);
1734 constraints()->purge_loader_constraints(is_alive);
1735 resolution_errors()->purge_resolution_errors(is_alive);
1736 return result;
1737 }
1738
1739
1740 // The mirrors are scanned by shared_oops_do() which is
1741 // not called by oops_do(). In order to process oops in
1742 // a necessary order, shared_oops_do() is call by
1743 // Universe::oops_do().
1744 void SystemDictionary::oops_do(OopClosure* f) {
1745 // Adjust preloaded classes and system loader object
1746 f->do_oop(&_java_system_loader);
1747 preloaded_oops_do(f);
1748
1749 lazily_loaded_oops_do(f);
1750
1751 // Adjust dictionary
1752 dictionary()->oops_do(f);
1753
1754 // Visit extra methods
1755 if (invoke_method_table() != NULL)
1756 invoke_method_table()->oops_do(f);
1757
1758 // Partially loaded classes
1759 placeholders()->oops_do(f);
1760
1761 // Adjust constraint table
1762 constraints()->oops_do(f);
1763
1764 // Adjust resolution error table
1765 resolution_errors()->oops_do(f);
1766 }
1767
1768
1769 void SystemDictionary::preloaded_oops_do(OopClosure* f) {
1770 f->do_oop((oop*) &wk_klass_name_limits[0]);
1771 f->do_oop((oop*) &wk_klass_name_limits[1]);
1772
1773 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1774 f->do_oop((oop*) &_well_known_klasses[k]);
1775 }
1776
1777 {
1778 for (int i = 0; i < T_VOID+1; i++) {
1779 if (_box_klasses[i] != NULL) {
1780 assert(i >= T_BOOLEAN, "checking");
1781 f->do_oop((oop*) &_box_klasses[i]);
1782 }
1783 }
1784 }
1785
1786 // The basic type mirrors would have already been processed in
1787 // Universe::oops_do(), via a call to shared_oops_do(), so should
1788 // not be processed again.
1789
1790 f->do_oop((oop*) &_system_loader_lock_obj);
1791 FilteredFieldsMap::klasses_oops_do(f);
1792 }
1793
1794 void SystemDictionary::lazily_loaded_oops_do(OopClosure* f) {
1795 f->do_oop((oop*) &_abstract_ownable_synchronizer_klass);
1796 }
1797
1798 // Just the classes from defining class loaders
1799 // Don't iterate over placeholders
1800 void SystemDictionary::classes_do(void f(klassOop)) {
1801 dictionary()->classes_do(f);
1802 }
1803
1804 // Added for initialize_itable_for_klass
1805 // Just the classes from defining class loaders
1806 // Don't iterate over placeholders
1807 void SystemDictionary::classes_do(void f(klassOop, TRAPS), TRAPS) {
1808 dictionary()->classes_do(f, CHECK);
1809 }
1810
1811 // All classes, and their class loaders
1812 // Don't iterate over placeholders
1813 void SystemDictionary::classes_do(void f(klassOop, oop)) {
1814 dictionary()->classes_do(f);
1815 }
1816
1817 // All classes, and their class loaders
1818 // (added for helpers that use HandleMarks and ResourceMarks)
1819 // Don't iterate over placeholders
1820 void SystemDictionary::classes_do(void f(klassOop, oop, TRAPS), TRAPS) {
1821 dictionary()->classes_do(f, CHECK);
1822 }
1823
1824 void SystemDictionary::placeholders_do(void f(symbolOop, oop)) {
1825 placeholders()->entries_do(f);
1826 }
1827
1828 void SystemDictionary::methods_do(void f(methodOop)) {
1829 dictionary()->methods_do(f);
1830 if (invoke_method_table() != NULL)
1831 invoke_method_table()->methods_do(f);
1832 }
1833
1834 // ----------------------------------------------------------------------------
1835 // Lazily load klasses
1836
1837 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1838 assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");
1839
1840 // if multiple threads calling this function, only one thread will load
1841 // the class. The other threads will find the loaded version once the
1842 // class is loaded.
1843 klassOop aos = _abstract_ownable_synchronizer_klass;
1844 if (aos == NULL) {
1845 klassOop k = resolve_or_fail(vmSymbolHandles::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1846 // Force a fence to prevent any read before the write completes
1847 OrderAccess::fence();
1848 _abstract_ownable_synchronizer_klass = k;
1849 }
1850 }
1851
1852 // ----------------------------------------------------------------------------
1853 // Initialization
1854
1855 void SystemDictionary::initialize(TRAPS) {
1856 // Allocate arrays
1857 assert(dictionary() == NULL,
1858 "SystemDictionary should only be initialized once");
1859 _dictionary = new Dictionary(_nof_buckets);
1860 _placeholders = new PlaceholderTable(_nof_buckets);
1861 _number_of_modifications = 0;
1862 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1863 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1864 // _invoke_method_table is allocated lazily in find_method_handle_invoke()
1865
1866 // Allocate private object used as system class loader lock
1867 _system_loader_lock_obj = oopFactory::new_system_objArray(0, CHECK);
1868 // Initialize basic classes
1869 initialize_preloaded_classes(CHECK);
1870 }
1871
1872 // Compact table of directions on the initialization of klasses:
1873 static const short wk_init_info[] = {
1874 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1875 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1876 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1877 | (int)SystemDictionary::option ),
1878 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1879 #undef WK_KLASS_INIT_INFO
1880 0
1881 };
1882
1883 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1884 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1885 int info = wk_init_info[id - FIRST_WKID];
1886 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1887 symbolHandle symbol = vmSymbolHandles::symbol_handle_at((vmSymbols::SID)sid);
1888 klassOop* klassp = &_well_known_klasses[id];
1889 bool must_load = (init_opt < SystemDictionary::Opt);
1890 bool try_load = true;
1891 if (init_opt == SystemDictionary::Opt_Kernel) {
1892 #ifndef KERNEL
1893 try_load = false;
1894 #endif //KERNEL
1895 }
1896 if ((*klassp) == NULL && try_load) {
1897 if (must_load) {
1898 (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class
1899 } else {
1900 (*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass
1901 }
1902 }
1903 return ((*klassp) != NULL);
1904 }
1905
1906 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1907 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1908 for (int id = (int)start_id; id < (int)limit_id; id++) {
1909 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1910 int info = wk_init_info[id - FIRST_WKID];
1911 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1912 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1913
1914 initialize_wk_klass((WKID)id, opt, CHECK);
1915
1916 // Update limits, so find_well_known_klass can be very fast:
1917 symbolOop s = vmSymbols::symbol_at((vmSymbols::SID)sid);
1918 if (wk_klass_name_limits[1] == NULL) {
1919 wk_klass_name_limits[0] = wk_klass_name_limits[1] = s;
1920 } else if (wk_klass_name_limits[1] < s) {
1921 wk_klass_name_limits[1] = s;
1922 } else if (wk_klass_name_limits[0] > s) {
1923 wk_klass_name_limits[0] = s;
1924 }
1925 }
1926
1927 // move the starting value forward to the limit:
1928 start_id = limit_id;
1929 }
1930
1931
1932 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1933 assert(WK_KLASS(object_klass) == NULL, "preloaded classes should only be initialized once");
1934 // Preload commonly used klasses
1935 WKID scan = FIRST_WKID;
1936 // first do Object, String, Class
1937 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(class_klass), scan, CHECK);
1938
1939 debug_only(instanceKlass::verify_class_klass_nonstatic_oop_maps(WK_KLASS(class_klass)));
1940
1941 // Fixup mirrors for classes loaded before java.lang.Class.
1942 // These calls iterate over the objects currently in the perm gen
1943 // so calling them at this point is matters (not before when there
1944 // are fewer objects and not later after there are more objects
1945 // in the perm gen.
1946 Universe::initialize_basic_type_mirrors(CHECK);
1947 Universe::fixup_mirrors(CHECK);
1948
1949 // do a bunch more:
1950 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(reference_klass), scan, CHECK);
1951
1952 // Preload ref klasses and set reference types
1953 instanceKlass::cast(WK_KLASS(reference_klass))->set_reference_type(REF_OTHER);
1954 instanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(reference_klass));
1955
1956 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(phantom_reference_klass), scan, CHECK);
1957 instanceKlass::cast(WK_KLASS(soft_reference_klass))->set_reference_type(REF_SOFT);
1958 instanceKlass::cast(WK_KLASS(weak_reference_klass))->set_reference_type(REF_WEAK);
1959 instanceKlass::cast(WK_KLASS(final_reference_klass))->set_reference_type(REF_FINAL);
1960 instanceKlass::cast(WK_KLASS(phantom_reference_klass))->set_reference_type(REF_PHANTOM);
1961
1962 WKID meth_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1963 WKID meth_group_end = WK_KLASS_ENUM_NAME(WrongMethodTypeException_klass);
1964 initialize_wk_klasses_until(meth_group_start, scan, CHECK);
1965 if (EnableMethodHandles) {
1966 initialize_wk_klasses_through(meth_group_end, scan, CHECK);
1967 }
1968 if (_well_known_klasses[meth_group_start] == NULL) {
1969 // Skip the rest of the method handle classes, if MethodHandle is not loaded.
1970 scan = WKID(meth_group_end+1);
1971 }
1972 WKID indy_group_start = WK_KLASS_ENUM_NAME(Linkage_klass);
1973 WKID indy_group_end = WK_KLASS_ENUM_NAME(InvokeDynamic_klass);
1974 initialize_wk_klasses_until(indy_group_start, scan, CHECK);
1975 if (EnableInvokeDynamic) {
1976 initialize_wk_klasses_through(indy_group_end, scan, CHECK);
1977 }
1978 if (_well_known_klasses[indy_group_start] == NULL) {
1979 // Skip the rest of the dynamic typing classes, if Linkage is not loaded.
1980 scan = WKID(indy_group_end+1);
1981 }
1982
1983 initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);
1984
1985 _box_klasses[T_BOOLEAN] = WK_KLASS(boolean_klass);
1986 _box_klasses[T_CHAR] = WK_KLASS(char_klass);
1987 _box_klasses[T_FLOAT] = WK_KLASS(float_klass);
1988 _box_klasses[T_DOUBLE] = WK_KLASS(double_klass);
1989 _box_klasses[T_BYTE] = WK_KLASS(byte_klass);
1990 _box_klasses[T_SHORT] = WK_KLASS(short_klass);
1991 _box_klasses[T_INT] = WK_KLASS(int_klass);
1992 _box_klasses[T_LONG] = WK_KLASS(long_klass);
1993 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
1994 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
1995
1996 #ifdef KERNEL
1997 if (sun_jkernel_DownloadManager_klass() == NULL) {
1998 warning("Cannot find sun/jkernel/DownloadManager");
1999 }
2000 #endif // KERNEL
2001
2002 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
2003 methodOop method = instanceKlass::cast(classloader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
2004 _has_loadClassInternal = (method != NULL);
2005 }
2006 { // Compute whether we should use checkPackageAccess or NOT
2007 methodOop method = instanceKlass::cast(classloader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2008 _has_checkPackageAccess = (method != NULL);
2009 }
2010 }
2011
2012 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2013 // If so, returns the basic type it holds. If not, returns T_OBJECT.
2014 BasicType SystemDictionary::box_klass_type(klassOop k) {
2015 assert(k != NULL, "");
2016 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2017 if (_box_klasses[i] == k)
2018 return (BasicType)i;
2019 }
2020 return T_OBJECT;
2021 }
2022
2023 KlassHandle SystemDictionaryHandles::box_klass(BasicType t) {
2024 if (t >= T_BOOLEAN && t <= T_VOID)
2025 return KlassHandle(&SystemDictionary::_box_klasses[t], true);
2026 else
2027 return KlassHandle();
2028 }
2029
2030 // Constraints on class loaders. The details of the algorithm can be
2031 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2032 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
2033 // that the system dictionary needs to maintain a set of contraints that
2034 // must be satisfied by all classes in the dictionary.
2035 // if defining is true, then LinkageError if already in systemDictionary
2036 // if initiating loader, then ok if instanceKlass matches existing entry
2037
2038 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
2039 instanceKlassHandle k,
2040 Handle class_loader, bool defining,
2041 TRAPS) {
2042 const char *linkage_error = NULL;
2043 {
2044 symbolHandle name (THREAD, k->name());
2045 MutexLocker mu(SystemDictionary_lock, THREAD);
2046
2047 klassOop check = find_class(d_index, d_hash, name, class_loader);
2048 if (check != (klassOop)NULL) {
2049 // if different instanceKlass - duplicate class definition,
2050 // else - ok, class loaded by a different thread in parallel,
2051 // we should only have found it if it was done loading and ok to use
2052 // system dictionary only holds instance classes, placeholders
2053 // also holds array classes
2054
2055 assert(check->klass_part()->oop_is_instance(), "noninstance in systemdictionary");
2056 if ((defining == true) || (k() != check)) {
2057 linkage_error = "loader (instance of %s): attempted duplicate class "
2058 "definition for name: \"%s\"";
2059 } else {
2060 return;
2061 }
2062 }
2063
2064 #ifdef ASSERT
2065 unsigned int p_hash = placeholders()->compute_hash(name, class_loader);
2066 int p_index = placeholders()->hash_to_index(p_hash);
2067 symbolOop ph_check = find_placeholder(p_index, p_hash, name, class_loader);
2068 assert(ph_check == NULL || ph_check == name(), "invalid symbol");
2069 #endif
2070
2071 if (linkage_error == NULL) {
2072 if (constraints()->check_or_update(k, class_loader, name) == false) {
2073 linkage_error = "loader constraint violation: loader (instance of %s)"
2074 " previously initiated loading for a different type with name \"%s\"";
2075 }
2076 }
2077 }
2078
2079 // Throw error now if needed (cannot throw while holding
2080 // SystemDictionary_lock because of rank ordering)
2081
2082 if (linkage_error) {
2083 ResourceMark rm(THREAD);
2084 const char* class_loader_name = loader_name(class_loader());
2085 char* type_name = k->name()->as_C_string();
2086 size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +
2087 strlen(type_name);
2088 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2089 jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);
2090 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2091 }
2092 }
2093
2094
2095 // Update system dictionary - done after check_constraint and add_to_hierachy
2096 // have been called.
2097 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2098 int p_index, unsigned int p_hash,
2099 instanceKlassHandle k,
2100 Handle class_loader,
2101 TRAPS) {
2102 // Compile_lock prevents systemDictionary updates during compilations
2103 assert_locked_or_safepoint(Compile_lock);
2104 symbolHandle name (THREAD, k->name());
2105
2106 {
2107 MutexLocker mu1(SystemDictionary_lock, THREAD);
2108
2109 // See whether biased locking is enabled and if so set it for this
2110 // klass.
2111 // Note that this must be done past the last potential blocking
2112 // point / safepoint. We enable biased locking lazily using a
2113 // VM_Operation to iterate the SystemDictionary and installing the
2114 // biasable mark word into each instanceKlass's prototype header.
2115 // To avoid race conditions where we accidentally miss enabling the
2116 // optimization for one class in the process of being added to the
2117 // dictionary, we must not safepoint after the test of
2118 // BiasedLocking::enabled().
2119 if (UseBiasedLocking && BiasedLocking::enabled()) {
2120 // Set biased locking bit for all loaded classes; it will be
2121 // cleared if revocation occurs too often for this type
2122 // NOTE that we must only do this when the class is initally
2123 // defined, not each time it is referenced from a new class loader
2124 if (k->class_loader() == class_loader()) {
2125 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2126 }
2127 }
2128
2129 // Check for a placeholder. If there, remove it and make a
2130 // new system dictionary entry.
2131 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
2132 klassOop sd_check = find_class(d_index, d_hash, name, class_loader);
2133 if (sd_check == NULL) {
2134 dictionary()->add_klass(name, class_loader, k);
2135 notice_modification();
2136 }
2137 #ifdef ASSERT
2138 sd_check = find_class(d_index, d_hash, name, class_loader);
2139 assert (sd_check != NULL, "should have entry in system dictionary");
2140 // Changed to allow PH to remain to complete class circularity checking
2141 // while only one thread can define a class at one time, multiple
2142 // classes can resolve the superclass for a class at one time,
2143 // and the placeholder is used to track that
2144 // symbolOop ph_check = find_placeholder(p_index, p_hash, name, class_loader);
2145 // assert (ph_check == NULL, "should not have a placeholder entry");
2146 #endif
2147 SystemDictionary_lock->notify_all();
2148 }
2149 }
2150
2151
2152 klassOop SystemDictionary::find_constrained_instance_or_array_klass(
2153 symbolHandle class_name, Handle class_loader, TRAPS) {
2154
2155 // First see if it has been loaded directly.
2156 // Force the protection domain to be null. (This removes protection checks.)
2157 Handle no_protection_domain;
2158 klassOop klass = find_instance_or_array_klass(class_name, class_loader,
2159 no_protection_domain, CHECK_NULL);
2160 if (klass != NULL)
2161 return klass;
2162
2163 // Now look to see if it has been loaded elsewhere, and is subject to
2164 // a loader constraint that would require this loader to return the
2165 // klass that is already loaded.
2166 if (FieldType::is_array(class_name())) {
2167 // Array classes are hard because their klassOops are not kept in the
2168 // constraint table. The array klass may be constrained, but the elem class
2169 // may not be.
2170 jint dimension;
2171 symbolOop object_key;
2172 BasicType t = FieldType::get_array_info(class_name(), &dimension,
2173 &object_key, CHECK_(NULL));
2174 if (t != T_OBJECT) {
2175 klass = Universe::typeArrayKlassObj(t);
2176 } else {
2177 symbolHandle elem_name(THREAD, object_key);
2178 MutexLocker mu(SystemDictionary_lock, THREAD);
2179 klass = constraints()->find_constrained_elem_klass(class_name, elem_name, class_loader, THREAD);
2180 }
2181 if (klass != NULL) {
2182 klass = Klass::cast(klass)->array_klass_or_null(dimension);
2183 }
2184 } else {
2185 MutexLocker mu(SystemDictionary_lock, THREAD);
2186 // Non-array classes are easy: simply check the constraint table.
2187 klass = constraints()->find_constrained_klass(class_name, class_loader);
2188 }
2189
2190 return klass;
2191 }
2192
2193
2194 bool SystemDictionary::add_loader_constraint(symbolHandle class_name,
2195 Handle class_loader1,
2196 Handle class_loader2,
2197 Thread* THREAD) {
2198 unsigned int d_hash1 = dictionary()->compute_hash(class_name, class_loader1);
2199 int d_index1 = dictionary()->hash_to_index(d_hash1);
2200
2201 unsigned int d_hash2 = dictionary()->compute_hash(class_name, class_loader2);
2202 int d_index2 = dictionary()->hash_to_index(d_hash2);
2203
2204 {
2205 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2206
2207 // Better never do a GC while we're holding these oops
2208 No_Safepoint_Verifier nosafepoint;
2209
2210 klassOop klass1 = find_class(d_index1, d_hash1, class_name, class_loader1);
2211 klassOop klass2 = find_class(d_index2, d_hash2, class_name, class_loader2);
2212 return constraints()->add_entry(class_name, klass1, class_loader1,
2213 klass2, class_loader2);
2214 }
2215 }
2216
2217 // Add entry to resolution error table to record the error when the first
2218 // attempt to resolve a reference to a class has failed.
2219 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, symbolHandle error) {
2220 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2221 int index = resolution_errors()->hash_to_index(hash);
2222 {
2223 MutexLocker ml(SystemDictionary_lock, Thread::current());
2224 resolution_errors()->add_entry(index, hash, pool, which, error);
2225 }
2226 }
2227
2228 // Lookup resolution error table. Returns error if found, otherwise NULL.
2229 symbolOop SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {
2230 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2231 int index = resolution_errors()->hash_to_index(hash);
2232 {
2233 MutexLocker ml(SystemDictionary_lock, Thread::current());
2234 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2235 return (entry != NULL) ? entry->error() : (symbolOop)NULL;
2236 }
2237 }
2238
2239
2240 // Signature constraints ensure that callers and callees agree about
2241 // the meaning of type names in their signatures. This routine is the
2242 // intake for constraints. It collects them from several places:
2243 //
2244 // * LinkResolver::resolve_method (if check_access is true) requires
2245 // that the resolving class (the caller) and the defining class of
2246 // the resolved method (the callee) agree on each type in the
2247 // method's signature.
2248 //
2249 // * LinkResolver::resolve_interface_method performs exactly the same
2250 // checks.
2251 //
2252 // * LinkResolver::resolve_field requires that the constant pool
2253 // attempting to link to a field agree with the field's defining
2254 // class about the type of the field signature.
2255 //
2256 // * klassVtable::initialize_vtable requires that, when a class
2257 // overrides a vtable entry allocated by a superclass, that the
2258 // overriding method (i.e., the callee) agree with the superclass
2259 // on each type in the method's signature.
2260 //
2261 // * klassItable::initialize_itable requires that, when a class fills
2262 // in its itables, for each non-abstract method installed in an
2263 // itable, the method (i.e., the callee) agree with the interface
2264 // on each type in the method's signature.
2265 //
2266 // All those methods have a boolean (check_access, checkconstraints)
2267 // which turns off the checks. This is used from specialized contexts
2268 // such as bootstrapping, dumping, and debugging.
2269 //
2270 // No direct constraint is placed between the class and its
2271 // supertypes. Constraints are only placed along linked relations
2272 // between callers and callees. When a method overrides or implements
2273 // an abstract method in a supertype (superclass or interface), the
2274 // constraints are placed as if the supertype were the caller to the
2275 // overriding method. (This works well, since callers to the
2276 // supertype have already established agreement between themselves and
2277 // the supertype.) As a result of all this, a class can disagree with
2278 // its supertype about the meaning of a type name, as long as that
2279 // class neither calls a relevant method of the supertype, nor is
2280 // called (perhaps via an override) from the supertype.
2281 //
2282 //
2283 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2284 //
2285 // Make sure all class components (including arrays) in the given
2286 // signature will be resolved to the same class in both loaders.
2287 // Returns the name of the type that failed a loader constraint check, or
2288 // NULL if no constraint failed. The returned C string needs cleaning up
2289 // with a ResourceMark in the caller. No exception except OOME is thrown.
2290 char* SystemDictionary::check_signature_loaders(symbolHandle signature,
2291 Handle loader1, Handle loader2,
2292 bool is_method, TRAPS) {
2293 // Nothing to do if loaders are the same.
2294 if (loader1() == loader2()) {
2295 return NULL;
2296 }
2297
2298 SignatureStream sig_strm(signature, is_method);
2299 while (!sig_strm.is_done()) {
2300 if (sig_strm.is_object()) {
2301 symbolOop s = sig_strm.as_symbol(CHECK_NULL);
2302 symbolHandle sig (THREAD, s);
2303 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2304 return sig()->as_C_string();
2305 }
2306 }
2307 sig_strm.next();
2308 }
2309 return NULL;
2310 }
2311
2312
2313 methodOop SystemDictionary::find_method_handle_invoke(symbolHandle signature,
2314 Handle class_loader,
2315 Handle protection_domain,
2316 TRAPS) {
2317 if (!EnableMethodHandles) return NULL;
2318 assert(class_loader.is_null() && protection_domain.is_null(),
2319 "cannot load specialized versions of MethodHandle.invoke");
2320 if (invoke_method_table() == NULL) {
2321 // create this side table lazily
2322 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
2323 }
2324 unsigned int hash = invoke_method_table()->compute_hash(signature);
2325 int index = invoke_method_table()->hash_to_index(hash);
2326 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature);
2327 if (spe == NULL || spe->property_oop() == NULL) {
2328 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2329 if (THREAD->is_Compiler_thread())
2330 return NULL; // do not attempt from within compiler
2331 Handle mt = compute_method_handle_type(signature(),
2332 class_loader, protection_domain,
2333 CHECK_NULL);
2334 KlassHandle mh_klass = SystemDictionaryHandles::MethodHandle_klass();
2335 methodHandle m = methodOopDesc::make_invoke_method(mh_klass, signature,
2336 mt, CHECK_NULL);
2337 // Now grab the lock. We might have to throw away the new method,
2338 // if a racing thread has managed to install one at the same time.
2339 {
2340 MutexLocker ml(SystemDictionary_lock, Thread::current());
2341 spe = invoke_method_table()->find_entry(index, hash, signature);
2342 if (spe == NULL)
2343 spe = invoke_method_table()->add_entry(index, hash, signature);
2344 if (spe->property_oop() == NULL)
2345 spe->set_property_oop(m());
2346 }
2347 }
2348 methodOop m = (methodOop) spe->property_oop();
2349 assert(m->is_method(), "");
2350 return m;
2351 }
2352
2353 // Ask Java code to find or construct a java.dyn.MethodType for the given
2354 // signature, as interpreted relative to the given class loader.
2355 // Because of class loader constraints, all method handle usage must be
2356 // consistent with this loader.
2357 Handle SystemDictionary::compute_method_handle_type(symbolHandle signature,
2358 Handle class_loader,
2359 Handle protection_domain,
2360 TRAPS) {
2361 Handle empty;
2362 int npts = ArgumentCount(signature()).size();
2363 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::class_klass(), npts, CHECK_(empty));
2364 int arg = 0;
2365 Handle rt; // the return type from the signature
2366 for (SignatureStream ss(signature()); !ss.is_done(); ss.next()) {
2367 oop mirror;
2368 if (!ss.is_object()) {
2369 mirror = Universe::java_mirror(ss.type());
2370 } else {
2371 symbolOop name_oop = ss.as_symbol(CHECK_(empty));
2372 symbolHandle name(THREAD, name_oop);
2373 klassOop klass = resolve_or_fail(name,
2374 class_loader, protection_domain,
2375 true, CHECK_(empty));
2376 mirror = Klass::cast(klass)->java_mirror();
2377 }
2378 if (ss.at_return_type())
2379 rt = Handle(THREAD, mirror);
2380 else
2381 pts->obj_at_put(arg++, mirror);
2382 }
2383 assert(arg == npts, "");
2384
2385 // call MethodType java.dyn.MethodType::makeImpl(Class rt, Class[] pts, false, true)
2386 bool varargs = false, trusted = true;
2387 JavaCallArguments args(Handle(THREAD, rt()));
2388 args.push_oop(pts());
2389 args.push_int(false);
2390 args.push_int(trusted);
2391 JavaValue result(T_OBJECT);
2392 JavaCalls::call_static(&result,
2393 SystemDictionary::MethodType_klass(),
2394 vmSymbols::makeImpl_name(), vmSymbols::makeImpl_signature(),
2395 &args, CHECK_(empty));
2396 return Handle(THREAD, (oop) result.get_jobject());
2397 }
2398
2399
2400 // Ask Java code to find or construct a java.dyn.CallSite for the given
2401 // name and signature, as interpreted relative to the given class loader.
2402 Handle SystemDictionary::make_dynamic_call_site(KlassHandle caller,
2403 int caller_method_idnum,
2404 int caller_bci,
2405 symbolHandle name,
2406 methodHandle mh_invdyn,
2407 TRAPS) {
2408 Handle empty;
2409 // call java.dyn.CallSite::makeSite(caller, name, mtype, cmid, cbci)
2410 oop name_str_oop = StringTable::intern(name(), CHECK_(empty)); // not a handle!
2411 JavaCallArguments args(Handle(THREAD, caller->java_mirror()));
2412 args.push_oop(name_str_oop);
2413 args.push_oop(mh_invdyn->method_handle_type());
2414 args.push_int(caller_method_idnum);
2415 args.push_int(caller_bci);
2416 JavaValue result(T_OBJECT);
2417 JavaCalls::call_static(&result,
2418 SystemDictionary::CallSite_klass(),
2419 vmSymbols::makeSite_name(), vmSymbols::makeSite_signature(),
2420 &args, CHECK_(empty));
2421 oop call_site_oop = (oop) result.get_jobject();
2422 assert(call_site_oop->is_oop()
2423 /*&& java_dyn_CallSite::is_instance(call_site_oop)*/, "must be sane");
2424 java_dyn_CallSite::set_vmmethod(call_site_oop, mh_invdyn());
2425 if (TraceMethodHandles) {
2426 #ifndef PRODUCT
2427 tty->print_cr("Linked invokedynamic bci=%d site="INTPTR_FORMAT":", caller_bci, call_site_oop);
2428 call_site_oop->print();
2429 tty->cr();
2430 }
2431 #endif //PRODUCT
2432 return call_site_oop;
2433 }
2434
2435 Handle SystemDictionary::find_bootstrap_method(KlassHandle caller,
2436 KlassHandle search_bootstrap_klass,
2437 TRAPS) {
2438 Handle empty;
2439 if (!caller->oop_is_instance()) return empty;
2440
2441 instanceKlassHandle ik(THREAD, caller());
2442
2443 oop boot_method_oop = ik->bootstrap_method();
2444 if (boot_method_oop != NULL) {
2445 if (TraceMethodHandles) {
2446 tty->print_cr("bootstrap method for "PTR_FORMAT" cached as "PTR_FORMAT":", ik(), boot_method_oop);
2447 }
2448 NOT_PRODUCT(if (!boot_method_oop->is_oop()) { tty->print_cr("*** boot MH of "PTR_FORMAT" = "PTR_FORMAT, ik(), boot_method_oop); ik()->print(); });
2449 assert(boot_method_oop->is_oop()
2450 && java_dyn_MethodHandle::is_instance(boot_method_oop), "must be sane");
2451 return Handle(THREAD, boot_method_oop);
2452 }
2453 boot_method_oop = NULL; // GC safety
2454
2455 // call java.dyn.Linkage::findBootstrapMethod(caller, sbk)
2456 JavaCallArguments args(Handle(THREAD, ik->java_mirror()));
2457 if (search_bootstrap_klass.is_null())
2458 args.push_oop(Handle());
2459 else
2460 args.push_oop(search_bootstrap_klass->java_mirror());
2461 JavaValue result(T_OBJECT);
2462 JavaCalls::call_static(&result,
2463 SystemDictionary::Linkage_klass(),
2464 vmSymbols::findBootstrapMethod_name(),
2465 vmSymbols::findBootstrapMethod_signature(),
2466 &args, CHECK_(empty));
2467 boot_method_oop = (oop) result.get_jobject();
2468
2469 if (boot_method_oop != NULL) {
2470 if (TraceMethodHandles) {
2471 #ifndef PRODUCT
2472 tty->print_cr("--------");
2473 tty->print_cr("bootstrap method for "PTR_FORMAT" computed as "PTR_FORMAT":", ik(), boot_method_oop);
2474 ik()->print();
2475 boot_method_oop->print();
2476 tty->print_cr("========");
2477 #endif //PRODUCT
2478 }
2479 assert(boot_method_oop->is_oop()
2480 && java_dyn_MethodHandle::is_instance(boot_method_oop), "must be sane");
2481 // probably no race conditions, but let's be careful:
2482 if (Atomic::cmpxchg_ptr(boot_method_oop, ik->adr_bootstrap_method(), NULL) == NULL)
2483 ik->set_bootstrap_method(boot_method_oop);
2484 else
2485 boot_method_oop = ik->bootstrap_method();
2486 } else {
2487 if (TraceMethodHandles) {
2488 #ifndef PRODUCT
2489 tty->print_cr("--------");
2490 tty->print_cr("bootstrap method for "PTR_FORMAT" computed as NULL:", ik());
2491 ik()->print();
2492 tty->print_cr("========");
2493 #endif //PRODUCT
2494 }
2495 boot_method_oop = ik->bootstrap_method();
2496 }
2497
2498 return Handle(THREAD, boot_method_oop);
2499 }
2500
2501 // Since the identity hash code for symbols changes when the symbols are
2502 // moved from the regular perm gen (hash in the mark word) to the shared
2503 // spaces (hash is the address), the classes loaded into the dictionary
2504 // may be in the wrong buckets.
2505
2506 void SystemDictionary::reorder_dictionary() {
2507 dictionary()->reorder_dictionary();
2508 }
2509
2510
2511 void SystemDictionary::copy_buckets(char** top, char* end) {
2512 dictionary()->copy_buckets(top, end);
2513 }
2514
2515
2516 void SystemDictionary::copy_table(char** top, char* end) {
2517 dictionary()->copy_table(top, end);
2518 }
2519
2520
2521 void SystemDictionary::reverse() {
2522 dictionary()->reverse();
2523 }
2524
2525 int SystemDictionary::number_of_classes() {
2526 return dictionary()->number_of_entries();
2527 }
2528
2529
2530 // ----------------------------------------------------------------------------
2531 #ifndef PRODUCT
2532
2533 void SystemDictionary::print() {
2534 dictionary()->print();
2535
2536 // Placeholders
2537 GCMutexLocker mu(SystemDictionary_lock);
2538 placeholders()->print();
2539
2540 // loader constraints - print under SD_lock
2541 constraints()->print();
2542 }
2543
2544 #endif
2545
2546 void SystemDictionary::verify() {
2547 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2548 guarantee(constraints() != NULL,
2549 "Verify of loader constraints failed");
2550 guarantee(dictionary()->number_of_entries() >= 0 &&
2551 placeholders()->number_of_entries() >= 0,
2552 "Verify of system dictionary failed");
2553
2554 // Verify dictionary
2555 dictionary()->verify();
2556
2557 GCMutexLocker mu(SystemDictionary_lock);
2558 placeholders()->verify();
2559
2560 // Verify constraint table
2561 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2562 constraints()->verify(dictionary());
2563 }
2564
2565
2566 void SystemDictionary::verify_obj_klass_present(Handle obj,
2567 symbolHandle class_name,
2568 Handle class_loader) {
2569 GCMutexLocker mu(SystemDictionary_lock);
2570 oop probe = find_class_or_placeholder(class_name, class_loader);
2571 if (probe == NULL) {
2572 probe = SystemDictionary::find_shared_class(class_name);
2573 }
2574 guarantee(probe != NULL &&
2575 (!probe->is_klass() || probe == obj()),
2576 "Loaded klasses should be in SystemDictionary");
2577 }
2578
2579 #ifndef PRODUCT
2580
2581 // statistics code
2582 class ClassStatistics: AllStatic {
2583 private:
2584 static int nclasses; // number of classes
2585 static int nmethods; // number of methods
2586 static int nmethoddata; // number of methodData
2587 static int class_size; // size of class objects in words
2588 static int method_size; // size of method objects in words
2589 static int debug_size; // size of debug info in methods
2590 static int methoddata_size; // size of methodData objects in words
2591
2592 static void do_class(klassOop k) {
2593 nclasses++;
2594 class_size += k->size();
2595 if (k->klass_part()->oop_is_instance()) {
2596 instanceKlass* ik = (instanceKlass*)k->klass_part();
2597 class_size += ik->methods()->size();
2598 class_size += ik->constants()->size();
2599 class_size += ik->local_interfaces()->size();
2600 class_size += ik->transitive_interfaces()->size();
2601 // We do not have to count implementors, since we only store one!
2602 class_size += ik->fields()->size();
2603 }
2604 }
2605
2606 static void do_method(methodOop m) {
2607 nmethods++;
2608 method_size += m->size();
2609 // class loader uses same objArray for empty vectors, so don't count these
2610 if (m->exception_table()->length() != 0) method_size += m->exception_table()->size();
2611 if (m->has_stackmap_table()) {
2612 method_size += m->stackmap_data()->size();
2613 }
2614
2615 methodDataOop mdo = m->method_data();
2616 if (mdo != NULL) {
2617 nmethoddata++;
2618 methoddata_size += mdo->size();
2619 }
2620 }
2621
2622 public:
2623 static void print() {
2624 SystemDictionary::classes_do(do_class);
2625 SystemDictionary::methods_do(do_method);
2626 tty->print_cr("Class statistics:");
2627 tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
2628 tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
2629 (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
2630 tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
2631 }
2632 };
2633
2634
2635 int ClassStatistics::nclasses = 0;
2636 int ClassStatistics::nmethods = 0;
2637 int ClassStatistics::nmethoddata = 0;
2638 int ClassStatistics::class_size = 0;
2639 int ClassStatistics::method_size = 0;
2640 int ClassStatistics::debug_size = 0;
2641 int ClassStatistics::methoddata_size = 0;
2642
2643 void SystemDictionary::print_class_statistics() {
2644 ResourceMark rm;
2645 ClassStatistics::print();
2646 }
2647
2648
2649 class MethodStatistics: AllStatic {
2650 public:
2651 enum {
2652 max_parameter_size = 10
2653 };
2654 private:
2655
2656 static int _number_of_methods;
2657 static int _number_of_final_methods;
2658 static int _number_of_static_methods;
2659 static int _number_of_native_methods;
2660 static int _number_of_synchronized_methods;
2661 static int _number_of_profiled_methods;
2662 static int _number_of_bytecodes;
2663 static int _parameter_size_profile[max_parameter_size];
2664 static int _bytecodes_profile[Bytecodes::number_of_java_codes];
2665
2666 static void initialize() {
2667 _number_of_methods = 0;
2668 _number_of_final_methods = 0;
2669 _number_of_static_methods = 0;
2670 _number_of_native_methods = 0;
2671 _number_of_synchronized_methods = 0;
2672 _number_of_profiled_methods = 0;
2673 _number_of_bytecodes = 0;
2674 for (int i = 0; i < max_parameter_size ; i++) _parameter_size_profile[i] = 0;
2675 for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile [j] = 0;
2676 };
2677
2678 static void do_method(methodOop m) {
2679 _number_of_methods++;
2680 // collect flag info
2681 if (m->is_final() ) _number_of_final_methods++;
2682 if (m->is_static() ) _number_of_static_methods++;
2683 if (m->is_native() ) _number_of_native_methods++;
2684 if (m->is_synchronized()) _number_of_synchronized_methods++;
2685 if (m->method_data() != NULL) _number_of_profiled_methods++;
2686 // collect parameter size info (add one for receiver, if any)
2687 _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
2688 // collect bytecodes info
2689 {
2690 Thread *thread = Thread::current();
2691 HandleMark hm(thread);
2692 BytecodeStream s(methodHandle(thread, m));
2693 Bytecodes::Code c;
2694 while ((c = s.next()) >= 0) {
2695 _number_of_bytecodes++;
2696 _bytecodes_profile[c]++;
2697 }
2698 }
2699 }
2700
2701 public:
2702 static void print() {
2703 initialize();
2704 SystemDictionary::methods_do(do_method);
2705 // generate output
2706 tty->cr();
2707 tty->print_cr("Method statistics (static):");
2708 // flag distribution
2709 tty->cr();
2710 tty->print_cr("%6d final methods %6.1f%%", _number_of_final_methods , _number_of_final_methods * 100.0F / _number_of_methods);
2711 tty->print_cr("%6d static methods %6.1f%%", _number_of_static_methods , _number_of_static_methods * 100.0F / _number_of_methods);
2712 tty->print_cr("%6d native methods %6.1f%%", _number_of_native_methods , _number_of_native_methods * 100.0F / _number_of_methods);
2713 tty->print_cr("%6d synchronized methods %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
2714 tty->print_cr("%6d profiled methods %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
2715 // parameter size profile
2716 tty->cr();
2717 { int tot = 0;
2718 int avg = 0;
2719 for (int i = 0; i < max_parameter_size; i++) {
2720 int n = _parameter_size_profile[i];
2721 tot += n;
2722 avg += n*i;
2723 tty->print_cr("parameter size = %1d: %6d methods %5.1f%%", i, n, n * 100.0F / _number_of_methods);
2724 }
2725 assert(tot == _number_of_methods, "should be the same");
2726 tty->print_cr(" %6d methods 100.0%%", _number_of_methods);
2727 tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
2728 }
2729 // bytecodes profile
2730 tty->cr();
2731 { int tot = 0;
2732 for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
2733 if (Bytecodes::is_defined(i)) {
2734 Bytecodes::Code c = Bytecodes::cast(i);
2735 int n = _bytecodes_profile[c];
2736 tot += n;
2737 tty->print_cr("%9d %7.3f%% %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
2738 }
2739 }
2740 assert(tot == _number_of_bytecodes, "should be the same");
2741 tty->print_cr("%9d 100.000%%", _number_of_bytecodes);
2742 }
2743 tty->cr();
2744 }
2745 };
2746
2747 int MethodStatistics::_number_of_methods;
2748 int MethodStatistics::_number_of_final_methods;
2749 int MethodStatistics::_number_of_static_methods;
2750 int MethodStatistics::_number_of_native_methods;
2751 int MethodStatistics::_number_of_synchronized_methods;
2752 int MethodStatistics::_number_of_profiled_methods;
2753 int MethodStatistics::_number_of_bytecodes;
2754 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
2755 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
2756
2757
2758 void SystemDictionary::print_method_statistics() {
2759 MethodStatistics::print();
2760 }
2761
2762 #endif // PRODUCT