1 /*
2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderData.inline.hpp"
27 #include "classfile/dictionary.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/loaderConstraints.hpp"
30 #include "classfile/placeholders.hpp"
31 #include "classfile/resolutionErrors.hpp"
32 #include "classfile/systemDictionary.hpp"
33 #include "classfile/vmSymbols.hpp"
34 #include "compiler/compileBroker.hpp"
35 #include "interpreter/bytecodeStream.hpp"
36 #include "interpreter/interpreter.hpp"
37 #include "memory/gcLocker.hpp"
38 #include "memory/oopFactory.hpp"
39 #include "oops/instanceKlass.hpp"
40 #include "oops/instanceRefKlass.hpp"
41 #include "oops/klass.inline.hpp"
42 #include "oops/methodData.hpp"
43 #include "oops/objArrayKlass.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "oops/oop.inline2.hpp"
46 #include "oops/typeArrayKlass.hpp"
47 #include "prims/jvmtiEnvBase.hpp"
48 #include "prims/methodHandles.hpp"
49 #include "runtime/biasedLocking.hpp"
50 #include "runtime/fieldType.hpp"
51 #include "runtime/handles.inline.hpp"
52 #include "runtime/java.hpp"
53 #include "runtime/javaCalls.hpp"
54 #include "runtime/mutexLocker.hpp"
55 #include "runtime/signature.hpp"
56 #include "services/classLoadingService.hpp"
57 #include "services/threadService.hpp"
58
59
60 Dictionary* SystemDictionary::_dictionary = NULL;
61 PlaceholderTable* SystemDictionary::_placeholders = NULL;
62 Dictionary* SystemDictionary::_shared_dictionary = NULL;
63 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
64 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
65 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
66
67
68 int SystemDictionary::_number_of_modifications = 0;
69 int SystemDictionary::_sdgeneration = 0;
70 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
71 20201,40423,99991};
72
73 oop SystemDictionary::_system_loader_lock_obj = NULL;
74
75 Klass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
76 = { NULL /*, NULL...*/ };
77
78 Klass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
79
80 oop SystemDictionary::_java_system_loader = NULL;
81
82 bool SystemDictionary::_has_loadClassInternal = false;
83 bool SystemDictionary::_has_checkPackageAccess = false;
84
85 // lazily initialized klass variables
86 Klass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
87
88
89 // ----------------------------------------------------------------------------
90 // Java-level SystemLoader
91
92 oop SystemDictionary::java_system_loader() {
93 return _java_system_loader;
94 }
95
96 void SystemDictionary::compute_java_system_loader(TRAPS) {
97 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
98 JavaValue result(T_OBJECT);
99 JavaCalls::call_static(&result,
100 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
101 vmSymbols::getSystemClassLoader_name(),
102 vmSymbols::void_classloader_signature(),
103 CHECK);
104
105 _java_system_loader = (oop)result.get_jobject();
106 }
107
108
109 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
110 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
111 return ClassLoaderDataGraph::find_or_create(class_loader, CHECK_NULL);
112 }
113
114 // ----------------------------------------------------------------------------
115 // debugging
116
117 #ifdef ASSERT
118
119 // return true if class_name contains no '.' (internal format is '/')
120 bool SystemDictionary::is_internal_format(Symbol* class_name) {
121 if (class_name != NULL) {
122 ResourceMark rm;
123 char* name = class_name->as_C_string();
124 return strchr(name, '.') == NULL;
125 } else {
126 return true;
127 }
128 }
129
130 #endif
131
132 // ----------------------------------------------------------------------------
133 // Parallel class loading check
134
135 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
136 if (UnsyncloadClass || class_loader.is_null()) return true;
137 if (AlwaysLockClassLoader) return false;
138 return java_lang_ClassLoader::parallelCapable(class_loader());
139 }
140 // ----------------------------------------------------------------------------
141 // ParallelDefineClass flag does not apply to bootclass loader
142 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
143 if (class_loader.is_null()) return false;
144 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
145 return true;
146 }
147 return false;
148 }
149
150 /**
151 * Returns true if the passed class loader is the extension class loader.
152 */
153 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
154 if (class_loader.is_null()) {
155 return false;
156 }
157 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
158 }
159
160 // ----------------------------------------------------------------------------
161 // Resolving of classes
162
163 // Forwards to resolve_or_null
164
165 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
166 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
167 if (HAS_PENDING_EXCEPTION || klass == NULL) {
168 KlassHandle k_h(THREAD, klass);
169 // can return a null klass
170 klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);
171 }
172 return klass;
173 }
174
175 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {
176 if (HAS_PENDING_EXCEPTION) {
177 // If we have a pending exception we forward it to the caller, unless throw_error is true,
178 // in which case we have to check whether the pending exception is a ClassNotFoundException,
179 // and if so convert it to a NoClassDefFoundError
180 // And chain the original ClassNotFoundException
181 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
182 ResourceMark rm(THREAD);
183 assert(klass_h() == NULL, "Should not have result with exception pending");
184 Handle e(THREAD, PENDING_EXCEPTION);
185 CLEAR_PENDING_EXCEPTION;
186 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
187 } else {
188 return NULL;
189 }
190 }
191 // Class not found, throw appropriate error or exception depending on value of throw_error
192 if (klass_h() == NULL) {
193 ResourceMark rm(THREAD);
194 if (throw_error) {
195 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
196 } else {
197 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
198 }
199 }
200 return (Klass*)klass_h();
201 }
202
203
204 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
205 bool throw_error, TRAPS)
206 {
207 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
208 }
209
210
211 // Forwards to resolve_instance_class_or_null
212
213 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
214 assert(!THREAD->is_Compiler_thread(),
215 err_msg("can not load classes with compiler thread: class=%s, classloader=%s",
216 class_name->as_C_string(),
217 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()));
218 if (FieldType::is_array(class_name)) {
219 return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
220 } else if (FieldType::is_obj(class_name)) {
221 ResourceMark rm(THREAD);
222 // Ignore wrapping L and ;.
223 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
224 class_name->utf8_length() - 2, CHECK_NULL);
225 return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL);
226 } else {
227 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
228 }
229 }
230
231 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
232 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
233 }
234
235 // Forwards to resolve_instance_class_or_null
236
237 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
238 Handle class_loader,
239 Handle protection_domain,
240 TRAPS) {
241 assert(FieldType::is_array(class_name), "must be array");
242 Klass* k = NULL;
243 FieldArrayInfo fd;
244 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
245 // of this call
246 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
247 if (t == T_OBJECT) {
248 // naked oop "k" is OK here -- we assign back into it
249 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
250 class_loader,
251 protection_domain,
252 CHECK_NULL);
253 if (k != NULL) {
254 k = k->array_klass(fd.dimension(), CHECK_NULL);
255 }
256 } else {
257 k = Universe::typeArrayKlassObj(t);
258 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
259 }
260 return k;
261 }
262
263
264 // Must be called for any super-class or super-interface resolution
265 // during class definition to allow class circularity checking
266 // super-interface callers:
267 // parse_interfaces - for defineClass & jvmtiRedefineClasses
268 // super-class callers:
269 // ClassFileParser - for defineClass & jvmtiRedefineClasses
270 // load_shared_class - while loading a class from shared archive
271 // resolve_instance_class_or_null:
272 // via: handle_parallel_super_load
273 // when resolving a class that has an existing placeholder with
274 // a saved superclass [i.e. a defineClass is currently in progress]
275 // if another thread is trying to resolve the class, it must do
276 // super-class checks on its own thread to catch class circularity
277 // This last call is critical in class circularity checking for cases
278 // where classloading is delegated to different threads and the
279 // classloader lock is released.
280 // Take the case: Base->Super->Base
281 // 1. If thread T1 tries to do a defineClass of class Base
282 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
283 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
284 // so it tries to load Super
285 // 3. If we load the class internally, or user classloader uses same thread
286 // loadClassFromxxx or defineClass via parseClassFile Super ...
287 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
288 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
289 // 3.4 calls resolve_super_or_fail Base
290 // 3.5 finds T1,Base -> throws class circularity
291 //OR 4. If T2 tries to resolve Super via defineClass Super ...
292 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
293 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
294 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
295 // 4.4 finds T2, Super -> throws class circularity
296 // Must be called, even if superclass is null, since this is
297 // where the placeholder entry is created which claims this
298 // thread is loading this class/classloader.
299 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
300 Symbol* class_name,
301 Handle class_loader,
302 Handle protection_domain,
303 bool is_superclass,
304 TRAPS) {
305 // Double-check, if child class is already loaded, just return super-class,interface
306 // Don't add a placedholder if already loaded, i.e. already in system dictionary
307 // Make sure there's a placeholder for the *child* before resolving.
308 // Used as a claim that this thread is currently loading superclass/classloader
309 // Used here for ClassCircularity checks and also for heap verification
310 // (every InstanceKlass in the heap needs to be in the system dictionary
311 // or have a placeholder).
312 // Must check ClassCircularity before checking if super class is already loaded
313 //
314 // We might not already have a placeholder if this child_name was
315 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
316 // the name of the class might not be known until the stream is actually
317 // parsed.
318 // Bugs 4643874, 4715493
319 // compute_hash can have a safepoint
320
321 ClassLoaderData* loader_data = class_loader_data(class_loader);
322 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
323 int d_index = dictionary()->hash_to_index(d_hash);
324 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
325 int p_index = placeholders()->hash_to_index(p_hash);
326 // can't throw error holding a lock
327 bool child_already_loaded = false;
328 bool throw_circularity_error = false;
329 {
330 MutexLocker mu(SystemDictionary_lock, THREAD);
331 Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
332 Klass* quicksuperk;
333 // to support // loading: if child done loading, just return superclass
334 // if class_name, & class_loader don't match:
335 // if initial define, SD update will give LinkageError
336 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
337 // so we don't throw an exception here.
338 // see: nsk redefclass014 & java.lang.instrument Instrument032
339 if ((childk != NULL ) && (is_superclass) &&
340 ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) &&
341
342 ((quicksuperk->name() == class_name) &&
343 (quicksuperk->class_loader() == class_loader()))) {
344 return quicksuperk;
345 } else {
346 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
347 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
348 throw_circularity_error = true;
349 }
350 }
351 if (!throw_circularity_error) {
352 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
353 }
354 }
355 if (throw_circularity_error) {
356 ResourceMark rm(THREAD);
357 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
358 }
359
360 // java.lang.Object should have been found above
361 assert(class_name != NULL, "null super class for resolving");
362 // Resolve the super class or interface, check results on return
363 Klass* superk = SystemDictionary::resolve_or_null(class_name,
364 class_loader,
365 protection_domain,
366 THREAD);
367
368 KlassHandle superk_h(THREAD, superk);
369
370 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
371 // It is no longer necessary to keep the placeholder table alive until update_dictionary
372 // or error. GC used to walk the placeholder table as strong roots.
373 // The instanceKlass is kept alive because the class loader is on the stack,
374 // which keeps the loader_data alive, as well as all instanceKlasses in
375 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
376 {
377 MutexLocker mu(SystemDictionary_lock, THREAD);
378 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
379 SystemDictionary_lock->notify_all();
380 }
381 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
382 // can null superk
383 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));
384 }
385
386 return superk_h();
387 }
388
389 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
390 Handle class_loader,
391 Handle protection_domain,
392 TRAPS) {
393 if(!has_checkPackageAccess()) return;
394
395 // Now we have to call back to java to check if the initating class has access
396 JavaValue result(T_VOID);
397 if (TraceProtectionDomainVerification) {
398 // Print out trace information
399 tty->print_cr("Checking package access");
400 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
401 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
402 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
403 }
404
405 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
406 JavaCalls::call_special(&result,
407 class_loader,
408 system_loader,
409 vmSymbols::checkPackageAccess_name(),
410 vmSymbols::class_protectiondomain_signature(),
411 Handle(THREAD, klass->java_mirror()),
412 protection_domain,
413 THREAD);
414
415 if (TraceProtectionDomainVerification) {
416 if (HAS_PENDING_EXCEPTION) {
417 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
418 } else {
419 tty->print_cr(" -> granted");
420 }
421 tty->cr();
422 }
423
424 if (HAS_PENDING_EXCEPTION) return;
425
426 // If no exception has been thrown, we have validated the protection domain
427 // Insert the protection domain of the initiating class into the set.
428 {
429 // We recalculate the entry here -- we've called out to java since
430 // the last time it was calculated.
431 ClassLoaderData* loader_data = class_loader_data(class_loader);
432
433 Symbol* kn = klass->name();
434 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
435 int d_index = dictionary()->hash_to_index(d_hash);
436
437 MutexLocker mu(SystemDictionary_lock, THREAD);
438 {
439 // Note that we have an entry, and entries can be deleted only during GC,
440 // so we cannot allow GC to occur while we're holding this entry.
441
442 // We're using a No_Safepoint_Verifier to catch any place where we
443 // might potentially do a GC at all.
444 // Dictionary::do_unloading() asserts that classes in SD are only
445 // unloaded at a safepoint. Anonymous classes are not in SD.
446 No_Safepoint_Verifier nosafepoint;
447 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
448 protection_domain, THREAD);
449 }
450 }
451 }
452
453 // We only get here if this thread finds that another thread
454 // has already claimed the placeholder token for the current operation,
455 // but that other thread either never owned or gave up the
456 // object lock
457 // Waits on SystemDictionary_lock to indicate placeholder table updated
458 // On return, caller must recheck placeholder table state
459 //
460 // We only get here if
461 // 1) custom classLoader, i.e. not bootstrap classloader
462 // 2) UnsyncloadClass not set
463 // 3) custom classLoader has broken the class loader objectLock
464 // so another thread got here in parallel
465 //
466 // lockObject must be held.
467 // Complicated dance due to lock ordering:
468 // Must first release the classloader object lock to
469 // allow initial definer to complete the class definition
470 // and to avoid deadlock
471 // Reclaim classloader lock object with same original recursion count
472 // Must release SystemDictionary_lock after notify, since
473 // class loader lock must be claimed before SystemDictionary_lock
474 // to prevent deadlocks
475 //
476 // The notify allows applications that did an untimed wait() on
477 // the classloader object lock to not hang.
478 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
479 assert_lock_strong(SystemDictionary_lock);
480
481 bool calledholdinglock
482 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
483 assert(calledholdinglock,"must hold lock for notify");
484 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
485 ObjectSynchronizer::notifyall(lockObject, THREAD);
486 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
487 SystemDictionary_lock->wait();
488 SystemDictionary_lock->unlock();
489 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
490 SystemDictionary_lock->lock();
491 }
492
493 // If the class in is in the placeholder table, class loading is in progress
494 // For cases where the application changes threads to load classes, it
495 // is critical to ClassCircularity detection that we try loading
496 // the superclass on the same thread internally, so we do parallel
497 // super class loading here.
498 // This also is critical in cases where the original thread gets stalled
499 // even in non-circularity situations.
500 // Note: must call resolve_super_or_fail even if null super -
501 // to force placeholder entry creation for this class for circularity detection
502 // Caller must check for pending exception
503 // Returns non-null Klass* if other thread has completed load
504 // and we are done,
505 // If return null Klass* and no pending exception, the caller must load the class
506 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
507 Symbol* name, Symbol* superclassname, Handle class_loader,
508 Handle protection_domain, Handle lockObject, TRAPS) {
509
510 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
511 ClassLoaderData* loader_data = class_loader_data(class_loader);
512 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
513 int d_index = dictionary()->hash_to_index(d_hash);
514 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
515 int p_index = placeholders()->hash_to_index(p_hash);
516
517 // superk is not used, resolve_super called for circularity check only
518 // This code is reached in two situations. One if this thread
519 // is loading the same class twice (e.g. ClassCircularity, or
520 // java.lang.instrument).
521 // The second is if another thread started the resolve_super first
522 // and has not yet finished.
523 // In both cases the original caller will clean up the placeholder
524 // entry on error.
525 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
526 superclassname,
527 class_loader,
528 protection_domain,
529 true,
530 CHECK_(nh));
531
532 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
533 // Serial class loaders and bootstrap classloader do wait for superclass loads
534 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
535 MutexLocker mu(SystemDictionary_lock, THREAD);
536 // Check if classloading completed while we were loading superclass or waiting
537 Klass* check = find_class(d_index, d_hash, name, loader_data);
538 if (check != NULL) {
539 // Klass is already loaded, so just return it
540 return(instanceKlassHandle(THREAD, check));
541 } else {
542 return nh;
543 }
544 }
545
546 // must loop to both handle other placeholder updates
547 // and spurious notifications
548 bool super_load_in_progress = true;
549 PlaceholderEntry* placeholder;
550 while (super_load_in_progress) {
551 MutexLocker mu(SystemDictionary_lock, THREAD);
552 // Check if classloading completed while we were loading superclass or waiting
553 Klass* check = find_class(d_index, d_hash, name, loader_data);
554 if (check != NULL) {
555 // Klass is already loaded, so just return it
556 return(instanceKlassHandle(THREAD, check));
557 } else {
558 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
559 if (placeholder && placeholder->super_load_in_progress() ){
560 // Before UnsyncloadClass:
561 // We only get here if the application has released the
562 // classloader lock when another thread was in the middle of loading a
563 // superclass/superinterface for this class, and now
564 // this thread is also trying to load this class.
565 // To minimize surprises, the first thread that started to
566 // load a class should be the one to complete the loading
567 // with the classfile it initially expected.
568 // This logic has the current thread wait once it has done
569 // all the superclass/superinterface loading it can, until
570 // the original thread completes the class loading or fails
571 // If it completes we will use the resulting InstanceKlass
572 // which we will find below in the systemDictionary.
573 // We also get here for parallel bootstrap classloader
574 if (class_loader.is_null()) {
575 SystemDictionary_lock->wait();
576 } else {
577 double_lock_wait(lockObject, THREAD);
578 }
579 } else {
580 // If not in SD and not in PH, other thread's load must have failed
581 super_load_in_progress = false;
582 }
583 }
584 }
585 return (nh);
586 }
587
588
589 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle class_loader, Handle protection_domain, TRAPS) {
590 assert(name != NULL && !FieldType::is_array(name) &&
591 !FieldType::is_obj(name), "invalid class name");
592
593 // UseNewReflection
594 // Fix for 4474172; see evaluation for more details
595 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
596 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
597
598 // Do lookup to see if class already exist and the protection domain
599 // has the right access
600 // This call uses find which checks protection domain already matches
601 // All subsequent calls use find_class, and set has_loaded_class so that
602 // before we return a result we call out to java to check for valid protection domain
603 // to allow returning the Klass* and add it to the pd_set if it is valid
604 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
605 int d_index = dictionary()->hash_to_index(d_hash);
606 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
607 protection_domain, THREAD);
608 if (probe != NULL) return probe;
609
610
611 // Non-bootstrap class loaders will call out to class loader and
612 // define via jvm/jni_DefineClass which will acquire the
613 // class loader object lock to protect against multiple threads
614 // defining the class in parallel by accident.
615 // This lock must be acquired here so the waiter will find
616 // any successful result in the SystemDictionary and not attempt
617 // the define
618 // ParallelCapable Classloaders and the bootstrap classloader,
619 // or all classloaders with UnsyncloadClass do not acquire lock here
620 bool DoObjectLock = true;
621 if (is_parallelCapable(class_loader)) {
622 DoObjectLock = false;
623 }
624
625 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
626 int p_index = placeholders()->hash_to_index(p_hash);
627
628 // Class is not in SystemDictionary so we have to do loading.
629 // Make sure we are synchronized on the class loader before we proceed
630 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
631 check_loader_lock_contention(lockObject, THREAD);
632 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
633
634 // Check again (after locking) if class already exist in SystemDictionary
635 bool class_has_been_loaded = false;
636 bool super_load_in_progress = false;
637 bool havesupername = false;
638 instanceKlassHandle k;
639 PlaceholderEntry* placeholder;
640 Symbol* superclassname = NULL;
641
642 {
643 MutexLocker mu(SystemDictionary_lock, THREAD);
644 Klass* check = find_class(d_index, d_hash, name, loader_data);
645 if (check != NULL) {
646 // Klass is already loaded, so just return it
647 class_has_been_loaded = true;
648 k = instanceKlassHandle(THREAD, check);
649 } else {
650 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
651 if (placeholder && placeholder->super_load_in_progress()) {
652 super_load_in_progress = true;
653 if (placeholder->havesupername() == true) {
654 superclassname = placeholder->supername();
655 havesupername = true;
656 }
657 }
658 }
659 }
660
661 // If the class is in the placeholder table, class loading is in progress
662 if (super_load_in_progress && havesupername==true) {
663 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
664 class_loader, protection_domain, lockObject, THREAD);
665 if (HAS_PENDING_EXCEPTION) {
666 return NULL;
667 }
668 if (!k.is_null()) {
669 class_has_been_loaded = true;
670 }
671 }
672
673 bool throw_circularity_error = false;
674 if (!class_has_been_loaded) {
675 bool load_instance_added = false;
676
677 // add placeholder entry to record loading instance class
678 // Five cases:
679 // All cases need to prevent modifying bootclasssearchpath
680 // in parallel with a classload of same classname
681 // Redefineclasses uses existence of the placeholder for the duration
682 // of the class load to prevent concurrent redefinition of not completely
683 // defined classes.
684 // case 1. traditional classloaders that rely on the classloader object lock
685 // - no other need for LOAD_INSTANCE
686 // case 2. traditional classloaders that break the classloader object lock
687 // as a deadlock workaround. Detection of this case requires that
688 // this check is done while holding the classloader object lock,
689 // and that lock is still held when calling classloader's loadClass.
690 // For these classloaders, we ensure that the first requestor
691 // completes the load and other requestors wait for completion.
692 // case 3. UnsyncloadClass - don't use objectLocker
693 // With this flag, we allow parallel classloading of a
694 // class/classloader pair
695 // case4. Bootstrap classloader - don't own objectLocker
696 // This classloader supports parallelism at the classloader level,
697 // but only allows a single load of a class/classloader pair.
698 // No performance benefit and no deadlock issues.
699 // case 5. parallelCapable user level classloaders - without objectLocker
700 // Allow parallel classloading of a class/classloader pair
701
702 {
703 MutexLocker mu(SystemDictionary_lock, THREAD);
704 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
705 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
706 if (oldprobe) {
707 // only need check_seen_thread once, not on each loop
708 // 6341374 java/lang/Instrument with -Xcomp
709 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
710 throw_circularity_error = true;
711 } else {
712 // case 1: traditional: should never see load_in_progress.
713 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
714
715 // case 4: bootstrap classloader: prevent futile classloading,
716 // wait on first requestor
717 if (class_loader.is_null()) {
718 SystemDictionary_lock->wait();
719 } else {
720 // case 2: traditional with broken classloader lock. wait on first
721 // requestor.
722 double_lock_wait(lockObject, THREAD);
723 }
724 // Check if classloading completed while we were waiting
725 Klass* check = find_class(d_index, d_hash, name, loader_data);
726 if (check != NULL) {
727 // Klass is already loaded, so just return it
728 k = instanceKlassHandle(THREAD, check);
729 class_has_been_loaded = true;
730 }
731 // check if other thread failed to load and cleaned up
732 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
733 }
734 }
735 }
736 }
737 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
738 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
739 // LOAD_INSTANCE in parallel
740
741 if (!throw_circularity_error && !class_has_been_loaded) {
742 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
743 load_instance_added = true;
744 // For class loaders that do not acquire the classloader object lock,
745 // if they did not catch another thread holding LOAD_INSTANCE,
746 // need a check analogous to the acquire ObjectLocker/find_class
747 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
748 // one final check if the load has already completed
749 // class loaders holding the ObjectLock shouldn't find the class here
750 Klass* check = find_class(d_index, d_hash, name, loader_data);
751 if (check != NULL) {
752 // Klass is already loaded, so return it after checking/adding protection domain
753 k = instanceKlassHandle(THREAD, check);
754 class_has_been_loaded = true;
755 }
756 }
757 }
758
759 // must throw error outside of owning lock
760 if (throw_circularity_error) {
761 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
762 ResourceMark rm(THREAD);
763 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
764 }
765
766 if (!class_has_been_loaded) {
767
768 // Do actual loading
769 k = load_instance_class(name, class_loader, THREAD);
770
771 // For UnsyncloadClass only
772 // If they got a linkageError, check if a parallel class load succeeded.
773 // If it did, then for bytecode resolution the specification requires
774 // that we return the same result we did for the other thread, i.e. the
775 // successfully loaded InstanceKlass
776 // Should not get here for classloaders that support parallelism
777 // with the new cleaner mechanism, even with AllowParallelDefineClass
778 // Bootstrap goes through here to allow for an extra guarantee check
779 if (UnsyncloadClass || (class_loader.is_null())) {
780 if (k.is_null() && HAS_PENDING_EXCEPTION
781 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
782 MutexLocker mu(SystemDictionary_lock, THREAD);
783 Klass* check = find_class(d_index, d_hash, name, loader_data);
784 if (check != NULL) {
785 // Klass is already loaded, so just use it
786 k = instanceKlassHandle(THREAD, check);
787 CLEAR_PENDING_EXCEPTION;
788 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
789 }
790 }
791 }
792
793 // If everything was OK (no exceptions, no null return value), and
794 // class_loader is NOT the defining loader, do a little more bookkeeping.
795 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
796 k->class_loader() != class_loader()) {
797
798 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
799
800 // Need to check for a PENDING_EXCEPTION again; check_constraints
801 // can throw and doesn't use the CHECK macro.
802 if (!HAS_PENDING_EXCEPTION) {
803 { // Grabbing the Compile_lock prevents systemDictionary updates
804 // during compilations.
805 MutexLocker mu(Compile_lock, THREAD);
806 update_dictionary(d_index, d_hash, p_index, p_hash,
807 k, class_loader, THREAD);
808 }
809 if (JvmtiExport::should_post_class_load()) {
810 Thread *thread = THREAD;
811 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
812 JvmtiExport::post_class_load((JavaThread *) thread, k());
813 }
814 }
815 }
816 } // load_instance_class loop
817
818 if (HAS_PENDING_EXCEPTION) {
819 // An exception, such as OOM could have happened at various places inside
820 // load_instance_class. We might have partially initialized a shared class
821 // and need to clean it up.
822 if (class_loader.is_null()) {
823 // In some cases k may be null. Let's find the shared class again.
824 instanceKlassHandle ik(THREAD, find_shared_class(name));
825 if (ik.not_null()) {
826 if (ik->class_loader_data() == NULL) {
827 // We didn't go as far as Klass::restore_unshareable_info(),
828 // so nothing to clean up.
829 } else {
830 Klass *kk;
831 {
832 MutexLocker mu(SystemDictionary_lock, THREAD);
833 kk = find_class(d_index, d_hash, name, ik->class_loader_data());
834 }
835 if (kk != NULL) {
836 // No clean up is needed if the shared class has been entered
837 // into system dictionary, as load_shared_class() won't be called
838 // again.
839 } else {
840 // This must be done outside of the SystemDictionary_lock to
841 // avoid deadlock.
842 //
843 // Note that Klass::restore_unshareable_info (called via
844 // load_instance_class above) is also called outside
845 // of SystemDictionary_lock. Other threads are blocked from
846 // loading this class because they are waiting on the
847 // SystemDictionary_lock until this thread removes
848 // the placeholder below.
849 //
850 // This need to be re-thought when parallel-capable non-boot
851 // classloaders are supported by CDS (today they're not).
852 clean_up_shared_class(ik, class_loader, THREAD);
853 }
854 }
855 }
856 }
857 }
858
859 if (load_instance_added == true) {
860 // clean up placeholder entries for LOAD_INSTANCE success or error
861 // This brackets the SystemDictionary updates for both defining
862 // and initiating loaders
863 MutexLocker mu(SystemDictionary_lock, THREAD);
864 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
865 SystemDictionary_lock->notify_all();
866 }
867 }
868
869 if (HAS_PENDING_EXCEPTION || k.is_null()) {
870 return NULL;
871 }
872
873 #ifdef ASSERT
874 {
875 ClassLoaderData* loader_data = k->class_loader_data();
876 MutexLocker mu(SystemDictionary_lock, THREAD);
877 Klass* kk = find_class(name, loader_data);
878 assert(kk == k(), "should be present in dictionary");
879 }
880 #endif
881
882 // return if the protection domain in NULL
883 if (protection_domain() == NULL) return k();
884
885 // Check the protection domain has the right access
886 {
887 MutexLocker mu(SystemDictionary_lock, THREAD);
888 // Note that we have an entry, and entries can be deleted only during GC,
889 // so we cannot allow GC to occur while we're holding this entry.
890 // We're using a No_Safepoint_Verifier to catch any place where we
891 // might potentially do a GC at all.
892 // Dictionary::do_unloading() asserts that classes in SD are only
893 // unloaded at a safepoint. Anonymous classes are not in SD.
894 No_Safepoint_Verifier nosafepoint;
895 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
896 loader_data,
897 protection_domain)) {
898 return k();
899 }
900 }
901
902 // Verify protection domain. If it fails an exception is thrown
903 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
904
905 return k();
906 }
907
908
909 // This routine does not lock the system dictionary.
910 //
911 // Since readers don't hold a lock, we must make sure that system
912 // dictionary entries are only removed at a safepoint (when only one
913 // thread is running), and are added to in a safe way (all links must
914 // be updated in an MT-safe manner).
915 //
916 // Callers should be aware that an entry could be added just after
917 // _dictionary->bucket(index) is read here, so the caller will not see
918 // the new entry.
919
920 Klass* SystemDictionary::find(Symbol* class_name,
921 Handle class_loader,
922 Handle protection_domain,
923 TRAPS) {
924
925 // UseNewReflection
926 // The result of this call should be consistent with the result
927 // of the call to resolve_instance_class_or_null().
928 // See evaluation 6790209 and 4474172 for more details.
929 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
930 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
931
932 if (loader_data == NULL) {
933 // If the ClassLoaderData has not been setup,
934 // then the class loader has no entries in the dictionary.
935 return NULL;
936 }
937
938 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
939 int d_index = dictionary()->hash_to_index(d_hash);
940
941 {
942 // Note that we have an entry, and entries can be deleted only during GC,
943 // so we cannot allow GC to occur while we're holding this entry.
944 // We're using a No_Safepoint_Verifier to catch any place where we
945 // might potentially do a GC at all.
946 // Dictionary::do_unloading() asserts that classes in SD are only
947 // unloaded at a safepoint. Anonymous classes are not in SD.
948 No_Safepoint_Verifier nosafepoint;
949 return dictionary()->find(d_index, d_hash, class_name, loader_data,
950 protection_domain, THREAD);
951 }
952 }
953
954
955 // Look for a loaded instance or array klass by name. Do not do any loading.
956 // return NULL in case of error.
957 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
958 Handle class_loader,
959 Handle protection_domain,
960 TRAPS) {
961 Klass* k = NULL;
962 assert(class_name != NULL, "class name must be non NULL");
963
964 if (FieldType::is_array(class_name)) {
965 // The name refers to an array. Parse the name.
966 // dimension and object_key in FieldArrayInfo are assigned as a
967 // side-effect of this call
968 FieldArrayInfo fd;
969 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
970 if (t != T_OBJECT) {
971 k = Universe::typeArrayKlassObj(t);
972 } else {
973 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
974 }
975 if (k != NULL) {
976 k = k->array_klass_or_null(fd.dimension());
977 }
978 } else {
979 k = find(class_name, class_loader, protection_domain, THREAD);
980 }
981 return k;
982 }
983
984 // Note: this method is much like resolve_from_stream, but
985 // updates no supplemental data structures.
986 // TODO consolidate the two methods with a helper routine?
987 Klass* SystemDictionary::parse_stream(Symbol* class_name,
988 Handle class_loader,
989 Handle protection_domain,
990 ClassFileStream* st,
991 KlassHandle host_klass,
992 GrowableArray<Handle>* cp_patches,
993 TRAPS) {
994 TempNewSymbol parsed_name = NULL;
995
996 ClassLoaderData* loader_data;
997 if (host_klass.not_null()) {
998 // Create a new CLD for anonymous class, that uses the same class loader
999 // as the host_klass
1000 assert(EnableInvokeDynamic, "");
1001 guarantee(host_klass->class_loader() == class_loader(), "should be the same");
1002 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
1003 loader_data->record_dependency(host_klass(), CHECK_NULL);
1004 } else {
1005 loader_data = ClassLoaderData::class_loader_data(class_loader());
1006 }
1007
1008 // Parse the stream. Note that we do this even though this klass might
1009 // already be present in the SystemDictionary, otherwise we would not
1010 // throw potential ClassFormatErrors.
1011 //
1012 // Note: "name" is updated.
1013
1014 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1015 loader_data,
1016 protection_domain,
1017 host_klass,
1018 cp_patches,
1019 parsed_name,
1020 true,
1021 THREAD);
1022
1023
1024 if (host_klass.not_null() && k.not_null()) {
1025 assert(EnableInvokeDynamic, "");
1026 k->set_host_klass(host_klass());
1027 // If it's anonymous, initialize it now, since nobody else will.
1028
1029 {
1030 MutexLocker mu_r(Compile_lock, THREAD);
1031
1032 // Add to class hierarchy, initialize vtables, and do possible
1033 // deoptimizations.
1034 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1035
1036 // But, do not add to system dictionary.
1037 }
1038
1039 // Rewrite and patch constant pool here.
1040 k->link_class(CHECK_NULL);
1041 if (cp_patches != NULL) {
1042 k->constants()->patch_resolved_references(cp_patches);
1043 }
1044 k->eager_initialize(CHECK_NULL);
1045
1046 // notify jvmti
1047 if (JvmtiExport::should_post_class_load()) {
1048 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1049 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1050 }
1051 }
1052 assert(host_klass.not_null() || cp_patches == NULL,
1053 "cp_patches only found with host_klass");
1054
1055 return k();
1056 }
1057
1058 // Add a klass to the system from a stream (called by jni_DefineClass and
1059 // JVM_DefineClass).
1060 // Note: class_name can be NULL. In that case we do not know the name of
1061 // the class until we have parsed the stream.
1062
1063 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1064 Handle class_loader,
1065 Handle protection_domain,
1066 ClassFileStream* st,
1067 bool verify,
1068 TRAPS) {
1069
1070 // Classloaders that support parallelism, e.g. bootstrap classloader,
1071 // or all classloaders with UnsyncloadClass do not acquire lock here
1072 bool DoObjectLock = true;
1073 if (is_parallelCapable(class_loader)) {
1074 DoObjectLock = false;
1075 }
1076
1077 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1078
1079 // Make sure we are synchronized on the class loader before we proceed
1080 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1081 check_loader_lock_contention(lockObject, THREAD);
1082 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1083
1084 TempNewSymbol parsed_name = NULL;
1085
1086 // Parse the stream. Note that we do this even though this klass might
1087 // already be present in the SystemDictionary, otherwise we would not
1088 // throw potential ClassFormatErrors.
1089 //
1090 // Note: "name" is updated.
1091
1092 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1093 loader_data,
1094 protection_domain,
1095 parsed_name,
1096 verify,
1097 THREAD);
1098
1099 const char* pkg = "java/";
1100 if (!HAS_PENDING_EXCEPTION &&
1101 !class_loader.is_null() &&
1102 parsed_name != NULL &&
1103 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1104 // It is illegal to define classes in the "java." package from
1105 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1106 ResourceMark rm(THREAD);
1107 char* name = parsed_name->as_C_string();
1108 char* index = strrchr(name, '/');
1109 *index = '\0'; // chop to just the package name
1110 while ((index = strchr(name, '/')) != NULL) {
1111 *index = '.'; // replace '/' with '.' in package name
1112 }
1113 const char* fmt = "Prohibited package name: %s";
1114 size_t len = strlen(fmt) + strlen(name);
1115 char* message = NEW_RESOURCE_ARRAY(char, len);
1116 jio_snprintf(message, len, fmt, name);
1117 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1118 vmSymbols::java_lang_SecurityException(), message);
1119 }
1120
1121 if (!HAS_PENDING_EXCEPTION) {
1122 assert(parsed_name != NULL, "Sanity");
1123 assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1124 // Verification prevents us from creating names with dots in them, this
1125 // asserts that that's the case.
1126 assert(is_internal_format(parsed_name),
1127 "external class name format used internally");
1128
1129 // Add class just loaded
1130 // If a class loader supports parallel classloading handle parallel define requests
1131 // find_or_define_instance_class may return a different InstanceKlass
1132 if (is_parallelCapable(class_loader)) {
1133 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1134 } else {
1135 define_instance_class(k, THREAD);
1136 }
1137 }
1138
1139 // Make sure we have an entry in the SystemDictionary on success
1140 debug_only( {
1141 if (!HAS_PENDING_EXCEPTION) {
1142 assert(parsed_name != NULL, "parsed_name is still null?");
1143 Symbol* h_name = k->name();
1144 ClassLoaderData *defining_loader_data = k->class_loader_data();
1145
1146 MutexLocker mu(SystemDictionary_lock, THREAD);
1147
1148 Klass* check = find_class(parsed_name, loader_data);
1149 assert(check == k(), "should be present in the dictionary");
1150
1151 Klass* check2 = find_class(h_name, defining_loader_data);
1152 assert(check == check2, "name inconsistancy in SystemDictionary");
1153 }
1154 } );
1155
1156 return k();
1157 }
1158
1159
1160 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1161 int number_of_entries) {
1162 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1163 "bad shared dictionary size.");
1164 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1165 }
1166
1167
1168 // If there is a shared dictionary, then find the entry for the
1169 // given shared system class, if any.
1170
1171 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1172 if (shared_dictionary() != NULL) {
1173 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1174 int d_index = shared_dictionary()->hash_to_index(d_hash);
1175
1176 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1177 } else {
1178 return NULL;
1179 }
1180 }
1181
1182
1183 // Load a class from the shared spaces (found through the shared system
1184 // dictionary). Force the superclass and all interfaces to be loaded.
1185 // Update the class definition to include sibling classes and no
1186 // subclasses (yet). [Classes in the shared space are not part of the
1187 // object hierarchy until loaded.]
1188
1189 instanceKlassHandle SystemDictionary::load_shared_class(
1190 Symbol* class_name, Handle class_loader, TRAPS) {
1191 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1192 return load_shared_class(ik, class_loader, THREAD);
1193 }
1194
1195 instanceKlassHandle SystemDictionary::load_shared_class(
1196 instanceKlassHandle ik, Handle class_loader, TRAPS) {
1197 assert(class_loader.is_null(), "non-null classloader for shared class?");
1198 if (ik.not_null()) {
1199 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1200 Symbol* class_name = ik->name();
1201
1202 // Found the class, now load the superclass and interfaces. If they
1203 // are shared, add them to the main system dictionary and reset
1204 // their hierarchy references (supers, subs, and interfaces).
1205
1206 if (ik->super() != NULL) {
1207 Symbol* cn = ik->super()->name();
1208 resolve_super_or_fail(class_name, cn,
1209 class_loader, Handle(), true, CHECK_(nh));
1210 }
1211
1212 Array<Klass*>* interfaces = ik->local_interfaces();
1213 int num_interfaces = interfaces->length();
1214 for (int index = 0; index < num_interfaces; index++) {
1215 Klass* k = interfaces->at(index);
1216
1217 // Note: can not use InstanceKlass::cast here because
1218 // interfaces' InstanceKlass's C++ vtbls haven't been
1219 // reinitialized yet (they will be once the interface classes
1220 // are loaded)
1221 Symbol* name = k->name();
1222 resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(nh));
1223 }
1224
1225 // Adjust methods to recover missing data. They need addresses for
1226 // interpreter entry points and their default native method address
1227 // must be reset.
1228
1229 // Updating methods must be done under a lock so multiple
1230 // threads don't update these in parallel
1231 // Shared classes are all currently loaded by the bootstrap
1232 // classloader, so this will never cause a deadlock on
1233 // a custom class loader lock.
1234
1235 {
1236 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1237 check_loader_lock_contention(lockObject, THREAD);
1238 ObjectLocker ol(lockObject, THREAD, true);
1239 ik->restore_unshareable_info(CHECK_(nh));
1240 }
1241
1242 if (TraceClassLoading) {
1243 ResourceMark rm;
1244 tty->print("[Loaded %s", ik->external_name());
1245 tty->print(" from shared objects file");
1246 tty->print_cr("]");
1247 }
1248 // notify a class loaded from shared object
1249 ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()),
1250 true /* shared class */);
1251 }
1252 return ik;
1253 }
1254
1255 void SystemDictionary::clean_up_shared_class(instanceKlassHandle ik, Handle class_loader, TRAPS) {
1256 // Updating methods must be done under a lock so multiple
1257 // threads don't update these in parallel
1258 // Shared classes are all currently loaded by the bootstrap
1259 // classloader, so this will never cause a deadlock on
1260 // a custom class loader lock.
1261 {
1262 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1263 check_loader_lock_contention(lockObject, THREAD);
1264 ObjectLocker ol(lockObject, THREAD, true);
1265 ik->remove_unshareable_info();
1266 }
1267 }
1268
1269 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1270 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1271 if (class_loader.is_null()) {
1272
1273 // Search the shared system dictionary for classes preloaded into the
1274 // shared spaces.
1275 instanceKlassHandle k;
1276 {
1277 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1278 k = load_shared_class(class_name, class_loader, THREAD);
1279 }
1280
1281 if (k.is_null()) {
1282 // Use VM class loader
1283 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1284 k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1285 }
1286
1287 // find_or_define_instance_class may return a different InstanceKlass
1288 if (!k.is_null()) {
1289 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1290 }
1291 return k;
1292 } else {
1293 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1294 ResourceMark rm(THREAD);
1295
1296 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1297 JavaThread* jt = (JavaThread*) THREAD;
1298
1299 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1300 ClassLoader::perf_app_classload_selftime(),
1301 ClassLoader::perf_app_classload_count(),
1302 jt->get_thread_stat()->perf_recursion_counts_addr(),
1303 jt->get_thread_stat()->perf_timers_addr(),
1304 PerfClassTraceTime::CLASS_LOAD);
1305
1306 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1307 // Translate to external class name format, i.e., convert '/' chars to '.'
1308 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1309
1310 JavaValue result(T_OBJECT);
1311
1312 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1313
1314 // Call public unsynchronized loadClass(String) directly for all class loaders
1315 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1316 // acquire a class-name based lock rather than the class loader object lock.
1317 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1318 // so the call to loadClassInternal() was not required.
1319 //
1320 // UnsyncloadClass flag means both call loadClass(String) and do
1321 // not acquire the class loader lock even for class loaders that are
1322 // not parallelCapable. This was a risky transitional
1323 // flag for diagnostic purposes only. It is risky to call
1324 // custom class loaders without synchronization.
1325 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1326 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1327 // Do NOT assume this will be supported in future releases.
1328 //
1329 // Added MustCallLoadClassInternal in case we discover in the field
1330 // a customer that counts on this call
1331 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1332 JavaCalls::call_special(&result,
1333 class_loader,
1334 spec_klass,
1335 vmSymbols::loadClassInternal_name(),
1336 vmSymbols::string_class_signature(),
1337 string,
1338 CHECK_(nh));
1339 } else {
1340 JavaCalls::call_virtual(&result,
1341 class_loader,
1342 spec_klass,
1343 vmSymbols::loadClass_name(),
1344 vmSymbols::string_class_signature(),
1345 string,
1346 CHECK_(nh));
1347 }
1348
1349 assert(result.get_type() == T_OBJECT, "just checking");
1350 oop obj = (oop) result.get_jobject();
1351
1352 // Primitive classes return null since forName() can not be
1353 // used to obtain any of the Class objects representing primitives or void
1354 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1355 instanceKlassHandle k =
1356 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1357 // For user defined Java class loaders, check that the name returned is
1358 // the same as that requested. This check is done for the bootstrap
1359 // loader when parsing the class file.
1360 if (class_name == k->name()) {
1361 return k;
1362 }
1363 }
1364 // Class is not found or has the wrong name, return NULL
1365 return nh;
1366 }
1367 }
1368
1369 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1370
1371 ClassLoaderData* loader_data = k->class_loader_data();
1372 Handle class_loader_h(THREAD, loader_data->class_loader());
1373
1374 for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){}
1375
1376 // for bootstrap and other parallel classloaders don't acquire lock,
1377 // use placeholder token
1378 // If a parallelCapable class loader calls define_instance_class instead of
1379 // find_or_define_instance_class to get here, we have a timing
1380 // hole with systemDictionary updates and check_constraints
1381 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1382 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1383 compute_loader_lock_object(class_loader_h, THREAD)),
1384 "define called without lock");
1385 }
1386
1387 // Check class-loading constraints. Throw exception if violation is detected.
1388 // Grabs and releases SystemDictionary_lock
1389 // The check_constraints/find_class call and update_dictionary sequence
1390 // must be "atomic" for a specific class/classloader pair so we never
1391 // define two different instanceKlasses for that class/classloader pair.
1392 // Existing classloaders will call define_instance_class with the
1393 // classloader lock held
1394 // Parallel classloaders will call find_or_define_instance_class
1395 // which will require a token to perform the define class
1396 Symbol* name_h = k->name();
1397 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1398 int d_index = dictionary()->hash_to_index(d_hash);
1399 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1400
1401 // Register class just loaded with class loader (placed in Vector)
1402 // Note we do this before updating the dictionary, as this can
1403 // fail with an OutOfMemoryError (if it does, we will *not* put this
1404 // class in the dictionary and will not update the class hierarchy).
1405 // JVMTI FollowReferences needs to find the classes this way.
1406 if (k->class_loader() != NULL) {
1407 methodHandle m(THREAD, Universe::loader_addClass_method());
1408 JavaValue result(T_VOID);
1409 JavaCallArguments args(class_loader_h);
1410 args.push_oop(Handle(THREAD, k->java_mirror()));
1411 JavaCalls::call(&result, m, &args, CHECK);
1412 }
1413
1414 // Add the new class. We need recompile lock during update of CHA.
1415 {
1416 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1417 int p_index = placeholders()->hash_to_index(p_hash);
1418
1419 MutexLocker mu_r(Compile_lock, THREAD);
1420
1421 // Add to class hierarchy, initialize vtables, and do possible
1422 // deoptimizations.
1423 add_to_hierarchy(k, CHECK); // No exception, but can block
1424
1425 // Add to systemDictionary - so other classes can see it.
1426 // Grabs and releases SystemDictionary_lock
1427 update_dictionary(d_index, d_hash, p_index, p_hash,
1428 k, class_loader_h, THREAD);
1429 }
1430 k->eager_initialize(THREAD);
1431
1432 // notify jvmti
1433 if (JvmtiExport::should_post_class_load()) {
1434 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1435 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1436
1437 }
1438 }
1439
1440 // Support parallel classloading
1441 // All parallel class loaders, including bootstrap classloader
1442 // lock a placeholder entry for this class/class_loader pair
1443 // to allow parallel defines of different classes for this class loader
1444 // With AllowParallelDefine flag==true, in case they do not synchronize around
1445 // FindLoadedClass/DefineClass, calls, we check for parallel
1446 // loading for them, wait if a defineClass is in progress
1447 // and return the initial requestor's results
1448 // This flag does not apply to the bootstrap classloader.
1449 // With AllowParallelDefine flag==false, call through to define_instance_class
1450 // which will throw LinkageError: duplicate class definition.
1451 // False is the requested default.
1452 // For better performance, the class loaders should synchronize
1453 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1454 // potentially waste time reading and parsing the bytestream.
1455 // Note: VM callers should ensure consistency of k/class_name,class_loader
1456 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1457
1458 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1459 Symbol* name_h = k->name(); // passed in class_name may be null
1460 ClassLoaderData* loader_data = class_loader_data(class_loader);
1461
1462 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1463 int d_index = dictionary()->hash_to_index(d_hash);
1464
1465 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1466 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1467 int p_index = placeholders()->hash_to_index(p_hash);
1468 PlaceholderEntry* probe;
1469
1470 {
1471 MutexLocker mu(SystemDictionary_lock, THREAD);
1472 // First check if class already defined
1473 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1474 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1475 if (check != NULL) {
1476 return(instanceKlassHandle(THREAD, check));
1477 }
1478 }
1479
1480 // Acquire define token for this class/classloader
1481 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1482 // Wait if another thread defining in parallel
1483 // All threads wait - even those that will throw duplicate class: otherwise
1484 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1485 // if other thread has not finished updating dictionary
1486 while (probe->definer() != NULL) {
1487 SystemDictionary_lock->wait();
1488 }
1489 // Only special cases allow parallel defines and can use other thread's results
1490 // Other cases fall through, and may run into duplicate defines
1491 // caught by finding an entry in the SystemDictionary
1492 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1493 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1494 SystemDictionary_lock->notify_all();
1495 #ifdef ASSERT
1496 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1497 assert(check != NULL, "definer missed recording success");
1498 #endif
1499 return(instanceKlassHandle(THREAD, probe->instance_klass()));
1500 } else {
1501 // This thread will define the class (even if earlier thread tried and had an error)
1502 probe->set_definer(THREAD);
1503 }
1504 }
1505
1506 define_instance_class(k, THREAD);
1507
1508 Handle linkage_exception = Handle(); // null handle
1509
1510 // definer must notify any waiting threads
1511 {
1512 MutexLocker mu(SystemDictionary_lock, THREAD);
1513 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1514 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1515 if (probe != NULL) {
1516 if (HAS_PENDING_EXCEPTION) {
1517 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1518 CLEAR_PENDING_EXCEPTION;
1519 } else {
1520 probe->set_instance_klass(k());
1521 }
1522 probe->set_definer(NULL);
1523 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1524 SystemDictionary_lock->notify_all();
1525 }
1526 }
1527
1528 // Can't throw exception while holding lock due to rank ordering
1529 if (linkage_exception() != NULL) {
1530 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1531 }
1532
1533 return k;
1534 }
1535 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1536 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1537 if (class_loader.is_null()) {
1538 return Handle(THREAD, _system_loader_lock_obj);
1539 } else {
1540 return class_loader;
1541 }
1542 }
1543
1544 // This method is added to check how often we have to wait to grab loader
1545 // lock. The results are being recorded in the performance counters defined in
1546 // ClassLoader::_sync_systemLoaderLockContentionRate and
1547 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1548 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1549 if (!UsePerfData) {
1550 return;
1551 }
1552
1553 assert(!loader_lock.is_null(), "NULL lock object");
1554
1555 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1556 == ObjectSynchronizer::owner_other) {
1557 // contention will likely happen, so increment the corresponding
1558 // contention counter.
1559 if (loader_lock() == _system_loader_lock_obj) {
1560 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1561 } else {
1562 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1563 }
1564 }
1565 }
1566
1567 // ----------------------------------------------------------------------------
1568 // Lookup
1569
1570 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1571 Symbol* class_name,
1572 ClassLoaderData* loader_data) {
1573 assert_locked_or_safepoint(SystemDictionary_lock);
1574 assert (index == dictionary()->index_for(class_name, loader_data),
1575 "incorrect index?");
1576
1577 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1578 return k;
1579 }
1580
1581
1582 // Basic find on classes in the midst of being loaded
1583 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1584 ClassLoaderData* loader_data) {
1585 assert_locked_or_safepoint(SystemDictionary_lock);
1586 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1587 int p_index = placeholders()->hash_to_index(p_hash);
1588 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1589 }
1590
1591
1592 // Used for assertions and verification only
1593 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1594 #ifndef ASSERT
1595 guarantee(VerifyBeforeGC ||
1596 VerifyDuringGC ||
1597 VerifyBeforeExit ||
1598 VerifyDuringStartup ||
1599 VerifyAfterGC, "too expensive");
1600 #endif
1601 assert_locked_or_safepoint(SystemDictionary_lock);
1602
1603 // First look in the loaded class array
1604 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1605 int d_index = dictionary()->hash_to_index(d_hash);
1606 return find_class(d_index, d_hash, class_name, loader_data);
1607 }
1608
1609
1610 // Get the next class in the diictionary.
1611 Klass* SystemDictionary::try_get_next_class() {
1612 return dictionary()->try_get_next_class();
1613 }
1614
1615
1616 // ----------------------------------------------------------------------------
1617 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1618 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1619 // before a new class is used.
1620
1621 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1622 assert(k.not_null(), "just checking");
1623 assert_locked_or_safepoint(Compile_lock);
1624
1625 // Link into hierachy. Make sure the vtables are initialized before linking into
1626 k->append_to_sibling_list(); // add to superklass/sibling list
1627 k->process_interfaces(THREAD); // handle all "implements" declarations
1628 k->set_init_state(InstanceKlass::loaded);
1629 // Now flush all code that depended on old class hierarchy.
1630 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1631 // Also, first reinitialize vtable because it may have gotten out of synch
1632 // while the new class wasn't connected to the class hierarchy.
1633 Universe::flush_dependents_on(k);
1634 }
1635
1636
1637 // ----------------------------------------------------------------------------
1638 // GC support
1639
1640 // Following roots during mark-sweep is separated in two phases.
1641 //
1642 // The first phase follows preloaded classes and all other system
1643 // classes, since these will never get unloaded anyway.
1644 //
1645 // The second phase removes (unloads) unreachable classes from the
1646 // system dictionary and follows the remaining classes' contents.
1647
1648 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1649 blk->do_oop(&_java_system_loader);
1650 blk->do_oop(&_system_loader_lock_obj);
1651
1652 dictionary()->always_strong_oops_do(blk);
1653
1654 // Visit extra methods
1655 invoke_method_table()->oops_do(blk);
1656 }
1657
1658 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1659 // Follow all system classes and temporary placeholders in dictionary
1660 dictionary()->always_strong_classes_do(closure);
1661
1662 // Placeholders. These represent classes we're actively loading.
1663 placeholders()->classes_do(closure);
1664 }
1665
1666 // Calculate a "good" systemdictionary size based
1667 // on predicted or current loaded classes count
1668 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1669 int newsize = _old_default_sdsize;
1670 if ((classcount > 0) && !DumpSharedSpaces) {
1671 int desiredsize = classcount/_average_depth_goal;
1672 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1673 newsize = _primelist[++_sdgeneration]) {
1674 if (desiredsize <= newsize) {
1675 break;
1676 }
1677 }
1678 }
1679 return newsize;
1680 }
1681 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1682 // Note: anonymous classes are not in the SD.
1683 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
1684 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1685 bool has_dead_loaders = ClassLoaderDataGraph::do_unloading(is_alive);
1686 bool unloading_occurred = false;
1687 if (has_dead_loaders) {
1688 unloading_occurred = dictionary()->do_unloading();
1689 constraints()->purge_loader_constraints();
1690 resolution_errors()->purge_resolution_errors();
1691 }
1692 return unloading_occurred;
1693 }
1694
1695 void SystemDictionary::oops_do(OopClosure* f) {
1696 f->do_oop(&_java_system_loader);
1697 f->do_oop(&_system_loader_lock_obj);
1698
1699 // Adjust dictionary
1700 dictionary()->oops_do(f);
1701
1702 // Visit extra methods
1703 invoke_method_table()->oops_do(f);
1704 }
1705
1706 // Extended Class redefinition support.
1707 // If one of these classes is replaced, we need to replace it in these places.
1708 // KlassClosure::do_klass should take the address of a class but we can
1709 // change that later.
1710 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1711 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1712 f->do_klass(_well_known_klasses[k]);
1713 }
1714
1715 {
1716 for (int i = 0; i < T_VOID+1; i++) {
1717 if (_box_klasses[i] != NULL) {
1718 assert(i >= T_BOOLEAN, "checking");
1719 f->do_klass(_box_klasses[i]);
1720 }
1721 }
1722 }
1723
1724 FilteredFieldsMap::classes_do(f);
1725 }
1726
1727 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1728 f->do_klass(_abstract_ownable_synchronizer_klass);
1729 }
1730
1731 // Just the classes from defining class loaders
1732 // Don't iterate over placeholders
1733 void SystemDictionary::classes_do(void f(Klass*)) {
1734 dictionary()->classes_do(f);
1735 }
1736
1737 // Added for initialize_itable_for_klass
1738 // Just the classes from defining class loaders
1739 // Don't iterate over placeholders
1740 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1741 dictionary()->classes_do(f, CHECK);
1742 }
1743
1744 // All classes, and their class loaders
1745 // Don't iterate over placeholders
1746 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1747 dictionary()->classes_do(f);
1748 }
1749
1750 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1751 placeholders()->entries_do(f);
1752 }
1753
1754 void SystemDictionary::methods_do(void f(Method*)) {
1755 dictionary()->methods_do(f);
1756 invoke_method_table()->methods_do(f);
1757 }
1758
1759 // ----------------------------------------------------------------------------
1760 // Lazily load klasses
1761
1762 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1763 assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");
1764
1765 // if multiple threads calling this function, only one thread will load
1766 // the class. The other threads will find the loaded version once the
1767 // class is loaded.
1768 Klass* aos = _abstract_ownable_synchronizer_klass;
1769 if (aos == NULL) {
1770 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1771 // Force a fence to prevent any read before the write completes
1772 OrderAccess::fence();
1773 _abstract_ownable_synchronizer_klass = k;
1774 }
1775 }
1776
1777 // ----------------------------------------------------------------------------
1778 // Initialization
1779
1780 void SystemDictionary::initialize(TRAPS) {
1781 // Allocate arrays
1782 assert(dictionary() == NULL,
1783 "SystemDictionary should only be initialized once");
1784 _sdgeneration = 0;
1785 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1786 _placeholders = new PlaceholderTable(_nof_buckets);
1787 _number_of_modifications = 0;
1788 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1789 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1790 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1791
1792 // Allocate private object used as system class loader lock
1793 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1794 // Initialize basic classes
1795 initialize_preloaded_classes(CHECK);
1796 }
1797
1798 // Compact table of directions on the initialization of klasses:
1799 static const short wk_init_info[] = {
1800 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1801 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1802 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1803 | (int)SystemDictionary::option ),
1804 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1805 #undef WK_KLASS_INIT_INFO
1806 0
1807 };
1808
1809 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1810 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1811 int info = wk_init_info[id - FIRST_WKID];
1812 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1813 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1814 Klass** klassp = &_well_known_klasses[id];
1815 bool must_load = (init_opt < SystemDictionary::Opt);
1816 if ((*klassp) == NULL) {
1817 if (must_load) {
1818 (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class
1819 } else {
1820 (*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass
1821 }
1822 }
1823 return ((*klassp) != NULL);
1824 }
1825
1826 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1827 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1828 for (int id = (int)start_id; id < (int)limit_id; id++) {
1829 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1830 int info = wk_init_info[id - FIRST_WKID];
1831 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1832 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1833
1834 initialize_wk_klass((WKID)id, opt, CHECK);
1835 }
1836
1837 // move the starting value forward to the limit:
1838 start_id = limit_id;
1839 }
1840
1841 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1842 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1843 // Preload commonly used klasses
1844 WKID scan = FIRST_WKID;
1845 // first do Object, then String, Class
1846 if (UseSharedSpaces) {
1847 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1848 // Initialize the constant pool for the Object_class
1849 InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1850 ik->constants()->restore_unshareable_info(CHECK);
1851 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1852 } else {
1853 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1854 }
1855
1856 // Calculate offsets for String and Class classes since they are loaded and
1857 // can be used after this point.
1858 java_lang_String::compute_offsets();
1859 java_lang_Class::compute_offsets();
1860
1861 // Fixup mirrors for classes loaded before java.lang.Class.
1862 // These calls iterate over the objects currently in the perm gen
1863 // so calling them at this point is matters (not before when there
1864 // are fewer objects and not later after there are more objects
1865 // in the perm gen.
1866 Universe::initialize_basic_type_mirrors(CHECK);
1867 Universe::fixup_mirrors(CHECK);
1868
1869 // do a bunch more:
1870 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1871
1872 // Preload ref klasses and set reference types
1873 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1874 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1875
1876 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
1877 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1878 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1879 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1880 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1881
1882 // JSR 292 classes
1883 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1884 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1885 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1886 if (EnableInvokeDynamic) {
1887 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1888 } else {
1889 // Skip the JSR 292 classes, if not enabled.
1890 scan = WKID(jsr292_group_end + 1);
1891 }
1892
1893 initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);
1894
1895 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1896 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
1897 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
1898 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
1899 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
1900 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
1901 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
1902 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
1903 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
1904 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
1905
1906 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
1907 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
1908 _has_loadClassInternal = (method != NULL);
1909 }
1910 { // Compute whether we should use checkPackageAccess or NOT
1911 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
1912 _has_checkPackageAccess = (method != NULL);
1913 }
1914 }
1915
1916 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
1917 // If so, returns the basic type it holds. If not, returns T_OBJECT.
1918 BasicType SystemDictionary::box_klass_type(Klass* k) {
1919 assert(k != NULL, "");
1920 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
1921 if (_box_klasses[i] == k)
1922 return (BasicType)i;
1923 }
1924 return T_OBJECT;
1925 }
1926
1927 // Constraints on class loaders. The details of the algorithm can be
1928 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1929 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1930 // that the system dictionary needs to maintain a set of contraints that
1931 // must be satisfied by all classes in the dictionary.
1932 // if defining is true, then LinkageError if already in systemDictionary
1933 // if initiating loader, then ok if InstanceKlass matches existing entry
1934
1935 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
1936 instanceKlassHandle k,
1937 Handle class_loader, bool defining,
1938 TRAPS) {
1939 const char *linkage_error = NULL;
1940 {
1941 Symbol* name = k->name();
1942 ClassLoaderData *loader_data = class_loader_data(class_loader);
1943
1944 MutexLocker mu(SystemDictionary_lock, THREAD);
1945
1946 Klass* check = find_class(d_index, d_hash, name, loader_data);
1947 if (check != (Klass*)NULL) {
1948 // if different InstanceKlass - duplicate class definition,
1949 // else - ok, class loaded by a different thread in parallel,
1950 // we should only have found it if it was done loading and ok to use
1951 // system dictionary only holds instance classes, placeholders
1952 // also holds array classes
1953
1954 assert(check->oop_is_instance(), "noninstance in systemdictionary");
1955 if ((defining == true) || (k() != check)) {
1956 linkage_error = "loader (instance of %s): attempted duplicate class "
1957 "definition for name: \"%s\"";
1958 } else {
1959 return;
1960 }
1961 }
1962
1963 #ifdef ASSERT
1964 Symbol* ph_check = find_placeholder(name, loader_data);
1965 assert(ph_check == NULL || ph_check == name, "invalid symbol");
1966 #endif
1967
1968 if (linkage_error == NULL) {
1969 if (constraints()->check_or_update(k, class_loader, name) == false) {
1970 linkage_error = "loader constraint violation: loader (instance of %s)"
1971 " previously initiated loading for a different type with name \"%s\"";
1972 }
1973 }
1974 }
1975
1976 // Throw error now if needed (cannot throw while holding
1977 // SystemDictionary_lock because of rank ordering)
1978
1979 if (linkage_error) {
1980 ResourceMark rm(THREAD);
1981 const char* class_loader_name = loader_name(class_loader());
1982 char* type_name = k->name()->as_C_string();
1983 size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +
1984 strlen(type_name);
1985 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
1986 jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);
1987 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
1988 }
1989 }
1990
1991
1992 // Update system dictionary - done after check_constraint and add_to_hierachy
1993 // have been called.
1994 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
1995 int p_index, unsigned int p_hash,
1996 instanceKlassHandle k,
1997 Handle class_loader,
1998 TRAPS) {
1999 // Compile_lock prevents systemDictionary updates during compilations
2000 assert_locked_or_safepoint(Compile_lock);
2001 Symbol* name = k->name();
2002 ClassLoaderData *loader_data = class_loader_data(class_loader);
2003
2004 {
2005 MutexLocker mu1(SystemDictionary_lock, THREAD);
2006
2007 // See whether biased locking is enabled and if so set it for this
2008 // klass.
2009 // Note that this must be done past the last potential blocking
2010 // point / safepoint. We enable biased locking lazily using a
2011 // VM_Operation to iterate the SystemDictionary and installing the
2012 // biasable mark word into each InstanceKlass's prototype header.
2013 // To avoid race conditions where we accidentally miss enabling the
2014 // optimization for one class in the process of being added to the
2015 // dictionary, we must not safepoint after the test of
2016 // BiasedLocking::enabled().
2017 if (UseBiasedLocking && BiasedLocking::enabled()) {
2018 // Set biased locking bit for all loaded classes; it will be
2019 // cleared if revocation occurs too often for this type
2020 // NOTE that we must only do this when the class is initally
2021 // defined, not each time it is referenced from a new class loader
2022 if (k->class_loader() == class_loader()) {
2023 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2024 }
2025 }
2026
2027 // Assign a classid if one has not already been assigned. The
2028 // counter does not need to be atomically incremented since this
2029 // is only done while holding the SystemDictionary_lock.
2030 // All loaded classes get a unique ID.
2031 TRACE_INIT_ID(k);
2032
2033 // Make a new system dictionary entry.
2034 Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2035 if (sd_check == NULL) {
2036 dictionary()->add_klass(name, loader_data, k);
2037 notice_modification();
2038 }
2039 #ifdef ASSERT
2040 sd_check = find_class(d_index, d_hash, name, loader_data);
2041 assert (sd_check != NULL, "should have entry in system dictionary");
2042 // Note: there may be a placeholder entry: for circularity testing
2043 // or for parallel defines
2044 #endif
2045 SystemDictionary_lock->notify_all();
2046 }
2047 }
2048
2049
2050 // Try to find a class name using the loader constraints. The
2051 // loader constraints might know about a class that isn't fully loaded
2052 // yet and these will be ignored.
2053 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2054 Symbol* class_name, Handle class_loader, TRAPS) {
2055
2056 // First see if it has been loaded directly.
2057 // Force the protection domain to be null. (This removes protection checks.)
2058 Handle no_protection_domain;
2059 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2060 no_protection_domain, CHECK_NULL);
2061 if (klass != NULL)
2062 return klass;
2063
2064 // Now look to see if it has been loaded elsewhere, and is subject to
2065 // a loader constraint that would require this loader to return the
2066 // klass that is already loaded.
2067 if (FieldType::is_array(class_name)) {
2068 // For array classes, their Klass*s are not kept in the
2069 // constraint table. The element Klass*s are.
2070 FieldArrayInfo fd;
2071 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2072 if (t != T_OBJECT) {
2073 klass = Universe::typeArrayKlassObj(t);
2074 } else {
2075 MutexLocker mu(SystemDictionary_lock, THREAD);
2076 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2077 }
2078 // If element class already loaded, allocate array klass
2079 if (klass != NULL) {
2080 klass = klass->array_klass_or_null(fd.dimension());
2081 }
2082 } else {
2083 MutexLocker mu(SystemDictionary_lock, THREAD);
2084 // Non-array classes are easy: simply check the constraint table.
2085 klass = constraints()->find_constrained_klass(class_name, class_loader);
2086 }
2087
2088 return klass;
2089 }
2090
2091
2092 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2093 Handle class_loader1,
2094 Handle class_loader2,
2095 Thread* THREAD) {
2096 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2097 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2098
2099 Symbol* constraint_name = NULL;
2100 if (!FieldType::is_array(class_name)) {
2101 constraint_name = class_name;
2102 } else {
2103 // For array classes, their Klass*s are not kept in the
2104 // constraint table. The element classes are.
2105 FieldArrayInfo fd;
2106 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2107 // primitive types always pass
2108 if (t != T_OBJECT) {
2109 return true;
2110 } else {
2111 constraint_name = fd.object_key();
2112 }
2113 }
2114 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2115 int d_index1 = dictionary()->hash_to_index(d_hash1);
2116
2117 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2118 int d_index2 = dictionary()->hash_to_index(d_hash2);
2119 {
2120 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2121
2122 // Better never do a GC while we're holding these oops
2123 No_Safepoint_Verifier nosafepoint;
2124
2125 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2126 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2127 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2128 klass2, class_loader2);
2129 }
2130 }
2131
2132 // Add entry to resolution error table to record the error when the first
2133 // attempt to resolve a reference to a class has failed.
2134 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) {
2135 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2136 int index = resolution_errors()->hash_to_index(hash);
2137 {
2138 MutexLocker ml(SystemDictionary_lock, Thread::current());
2139 resolution_errors()->add_entry(index, hash, pool, which, error);
2140 }
2141 }
2142
2143 // Delete a resolution error for RedefineClasses for a constant pool is going away
2144 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2145 resolution_errors()->delete_entry(pool);
2146 }
2147
2148 // Lookup resolution error table. Returns error if found, otherwise NULL.
2149 Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {
2150 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2151 int index = resolution_errors()->hash_to_index(hash);
2152 {
2153 MutexLocker ml(SystemDictionary_lock, Thread::current());
2154 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2155 return (entry != NULL) ? entry->error() : (Symbol*)NULL;
2156 }
2157 }
2158
2159
2160 // Signature constraints ensure that callers and callees agree about
2161 // the meaning of type names in their signatures. This routine is the
2162 // intake for constraints. It collects them from several places:
2163 //
2164 // * LinkResolver::resolve_method (if check_access is true) requires
2165 // that the resolving class (the caller) and the defining class of
2166 // the resolved method (the callee) agree on each type in the
2167 // method's signature.
2168 //
2169 // * LinkResolver::resolve_interface_method performs exactly the same
2170 // checks.
2171 //
2172 // * LinkResolver::resolve_field requires that the constant pool
2173 // attempting to link to a field agree with the field's defining
2174 // class about the type of the field signature.
2175 //
2176 // * klassVtable::initialize_vtable requires that, when a class
2177 // overrides a vtable entry allocated by a superclass, that the
2178 // overriding method (i.e., the callee) agree with the superclass
2179 // on each type in the method's signature.
2180 //
2181 // * klassItable::initialize_itable requires that, when a class fills
2182 // in its itables, for each non-abstract method installed in an
2183 // itable, the method (i.e., the callee) agree with the interface
2184 // on each type in the method's signature.
2185 //
2186 // All those methods have a boolean (check_access, checkconstraints)
2187 // which turns off the checks. This is used from specialized contexts
2188 // such as bootstrapping, dumping, and debugging.
2189 //
2190 // No direct constraint is placed between the class and its
2191 // supertypes. Constraints are only placed along linked relations
2192 // between callers and callees. When a method overrides or implements
2193 // an abstract method in a supertype (superclass or interface), the
2194 // constraints are placed as if the supertype were the caller to the
2195 // overriding method. (This works well, since callers to the
2196 // supertype have already established agreement between themselves and
2197 // the supertype.) As a result of all this, a class can disagree with
2198 // its supertype about the meaning of a type name, as long as that
2199 // class neither calls a relevant method of the supertype, nor is
2200 // called (perhaps via an override) from the supertype.
2201 //
2202 //
2203 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2204 //
2205 // Make sure all class components (including arrays) in the given
2206 // signature will be resolved to the same class in both loaders.
2207 // Returns the name of the type that failed a loader constraint check, or
2208 // NULL if no constraint failed. No exception except OOME is thrown.
2209 // Arrays are not added to the loader constraint table, their elements are.
2210 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2211 Handle loader1, Handle loader2,
2212 bool is_method, TRAPS) {
2213 // Nothing to do if loaders are the same.
2214 if (loader1() == loader2()) {
2215 return NULL;
2216 }
2217
2218 SignatureStream sig_strm(signature, is_method);
2219 while (!sig_strm.is_done()) {
2220 if (sig_strm.is_object()) {
2221 Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2222 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2223 return sig;
2224 }
2225 }
2226 sig_strm.next();
2227 }
2228 return NULL;
2229 }
2230
2231
2232 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2233 Symbol* signature,
2234 TRAPS) {
2235 methodHandle empty;
2236 assert(EnableInvokeDynamic, "");
2237 assert(MethodHandles::is_signature_polymorphic(iid) &&
2238 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2239 iid != vmIntrinsics::_invokeGeneric,
2240 err_msg("must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)));
2241
2242 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2243 int index = invoke_method_table()->hash_to_index(hash);
2244 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2245 methodHandle m;
2246 if (spe == NULL || spe->method() == NULL) {
2247 spe = NULL;
2248 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2249 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2250 CompileBroker::compile_method(m, InvocationEntryBci, CompLevel_highest_tier,
2251 methodHandle(), CompileThreshold, "MH", CHECK_(empty));
2252
2253 // Now grab the lock. We might have to throw away the new method,
2254 // if a racing thread has managed to install one at the same time.
2255 {
2256 MutexLocker ml(SystemDictionary_lock, THREAD);
2257 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2258 if (spe == NULL)
2259 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2260 if (spe->method() == NULL)
2261 spe->set_method(m());
2262 }
2263 }
2264
2265 assert(spe != NULL && spe->method() != NULL, "");
2266 return spe->method();
2267 }
2268
2269 // Helper for unpacking the return value from linkMethod and linkCallSite.
2270 static methodHandle unpack_method_and_appendix(Handle mname,
2271 KlassHandle accessing_klass,
2272 objArrayHandle appendix_box,
2273 Handle* appendix_result,
2274 TRAPS) {
2275 methodHandle empty;
2276 if (mname.not_null()) {
2277 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2278 if (vmtarget != NULL && vmtarget->is_method()) {
2279 Method* m = (Method*)vmtarget;
2280 oop appendix = appendix_box->obj_at(0);
2281 if (TraceMethodHandles) {
2282 #ifndef PRODUCT
2283 tty->print("Linked method="INTPTR_FORMAT": ", m);
2284 m->print();
2285 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2286 tty->cr();
2287 #endif //PRODUCT
2288 }
2289 (*appendix_result) = Handle(THREAD, appendix);
2290 // the target is stored in the cpCache and if a reference to this
2291 // MethodName is dropped we need a way to make sure the
2292 // class_loader containing this method is kept alive.
2293 // FIXME: the appendix might also preserve this dependency.
2294 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2295 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2296 return methodHandle(THREAD, m);
2297 }
2298 }
2299 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2300 return empty;
2301 }
2302
2303 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2304 Symbol* signature,
2305 KlassHandle accessing_klass,
2306 Handle *appendix_result,
2307 Handle *method_type_result,
2308 TRAPS) {
2309 methodHandle empty;
2310 assert(EnableInvokeDynamic, "");
2311 assert(!THREAD->is_Compiler_thread(), "");
2312 Handle method_type =
2313 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2314 if (false) { // FIXME: Decide if the Java upcall should resolve signatures.
2315 method_type = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2316 }
2317
2318 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass();
2319 int ref_kind = JVM_REF_invokeVirtual;
2320 Handle name_str = StringTable::intern(name, CHECK_(empty));
2321 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2322 assert(appendix_box->obj_at(0) == NULL, "");
2323
2324 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2325 JavaCallArguments args;
2326 args.push_oop(accessing_klass()->java_mirror());
2327 args.push_int(ref_kind);
2328 args.push_oop(mh_klass()->java_mirror());
2329 args.push_oop(name_str());
2330 args.push_oop(method_type());
2331 args.push_oop(appendix_box());
2332 JavaValue result(T_OBJECT);
2333 JavaCalls::call_static(&result,
2334 SystemDictionary::MethodHandleNatives_klass(),
2335 vmSymbols::linkMethod_name(),
2336 vmSymbols::linkMethod_signature(),
2337 &args, CHECK_(empty));
2338 Handle mname(THREAD, (oop) result.get_jobject());
2339 (*method_type_result) = method_type;
2340 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2341 }
2342
2343
2344 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2345 // signature, as interpreted relative to the given class loader.
2346 // Because of class loader constraints, all method handle usage must be
2347 // consistent with this loader.
2348 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2349 KlassHandle accessing_klass,
2350 TRAPS) {
2351 Handle empty;
2352 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2353 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2354 int index = invoke_method_table()->hash_to_index(hash);
2355 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2356 if (spe != NULL && spe->method_type() != NULL) {
2357 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2358 return Handle(THREAD, spe->method_type());
2359 } else if (THREAD->is_Compiler_thread()) {
2360 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2361 return Handle(); // do not attempt from within compiler, unless it was cached
2362 }
2363
2364 Handle class_loader, protection_domain;
2365 bool is_on_bcp = true; // keep this true as long as we can materialize from the boot classloader
2366 int npts = ArgumentCount(signature).size();
2367 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2368 int arg = 0;
2369 Handle rt; // the return type from the signature
2370 ResourceMark rm(THREAD);
2371 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2372 oop mirror = NULL;
2373 if (is_on_bcp) {
2374 // Note: class_loader & protection_domain are both null at this point.
2375 mirror = ss.as_java_mirror(class_loader, protection_domain,
2376 SignatureStream::ReturnNull, CHECK_(empty));
2377 if (mirror == NULL) {
2378 // fall back from BCP to accessing_klass
2379 if (accessing_klass.not_null()) {
2380 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2381 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2382 }
2383 is_on_bcp = false;
2384 }
2385 }
2386 if (!is_on_bcp) {
2387 // Resolve, throwing a real error if it doesn't work.
2388 mirror = ss.as_java_mirror(class_loader, protection_domain,
2389 SignatureStream::NCDFError, CHECK_(empty));
2390 }
2391 if (ss.at_return_type())
2392 rt = Handle(THREAD, mirror);
2393 else
2394 pts->obj_at_put(arg++, mirror);
2395
2396 // Check accessibility.
2397 if (ss.is_object() && accessing_klass.not_null()) {
2398 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2399 mirror = NULL; // safety
2400 // Emulate ConstantPool::verify_constant_pool_resolve.
2401 if (sel_klass->oop_is_objArray())
2402 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2403 if (sel_klass->oop_is_instance()) {
2404 KlassHandle sel_kh(THREAD, sel_klass);
2405 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2406 }
2407 }
2408 }
2409 assert(arg == npts, "");
2410
2411 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2412 JavaCallArguments args(Handle(THREAD, rt()));
2413 args.push_oop(pts());
2414 JavaValue result(T_OBJECT);
2415 JavaCalls::call_static(&result,
2416 SystemDictionary::MethodHandleNatives_klass(),
2417 vmSymbols::findMethodHandleType_name(),
2418 vmSymbols::findMethodHandleType_signature(),
2419 &args, CHECK_(empty));
2420 Handle method_type(THREAD, (oop) result.get_jobject());
2421
2422 if (is_on_bcp) {
2423 // We can cache this MethodType inside the JVM.
2424 MutexLocker ml(SystemDictionary_lock, THREAD);
2425 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2426 if (spe == NULL)
2427 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2428 if (spe->method_type() == NULL) {
2429 spe->set_method_type(method_type());
2430 }
2431 }
2432
2433 // report back to the caller with the MethodType
2434 return method_type;
2435 }
2436
2437 // Ask Java code to find or construct a method handle constant.
2438 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2439 int ref_kind, //e.g., JVM_REF_invokeVirtual
2440 KlassHandle callee,
2441 Symbol* name_sym,
2442 Symbol* signature,
2443 TRAPS) {
2444 Handle empty;
2445 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2446 Handle type;
2447 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2448 type = find_method_handle_type(signature, caller, CHECK_(empty));
2449 } else {
2450 ResourceMark rm(THREAD);
2451 SignatureStream ss(signature, false);
2452 if (!ss.is_done()) {
2453 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2454 SignatureStream::NCDFError, CHECK_(empty));
2455 type = Handle(THREAD, mirror);
2456 ss.next();
2457 if (!ss.is_done()) type = Handle(); // error!
2458 }
2459 }
2460 if (type.is_null()) {
2461 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2462 }
2463
2464 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2465 JavaCallArguments args;
2466 args.push_oop(caller->java_mirror()); // the referring class
2467 args.push_int(ref_kind);
2468 args.push_oop(callee->java_mirror()); // the target class
2469 args.push_oop(name());
2470 args.push_oop(type());
2471 JavaValue result(T_OBJECT);
2472 JavaCalls::call_static(&result,
2473 SystemDictionary::MethodHandleNatives_klass(),
2474 vmSymbols::linkMethodHandleConstant_name(),
2475 vmSymbols::linkMethodHandleConstant_signature(),
2476 &args, CHECK_(empty));
2477 return Handle(THREAD, (oop) result.get_jobject());
2478 }
2479
2480 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2481 // name and signature, as interpreted relative to the given class loader.
2482 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2483 Handle bootstrap_specifier,
2484 Symbol* name,
2485 Symbol* type,
2486 Handle *appendix_result,
2487 Handle *method_type_result,
2488 TRAPS) {
2489 methodHandle empty;
2490 Handle bsm, info;
2491 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2492 bsm = bootstrap_specifier;
2493 } else {
2494 assert(bootstrap_specifier->is_objArray(), "");
2495 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2496 int len = args->length();
2497 assert(len >= 1, "");
2498 bsm = Handle(THREAD, args->obj_at(0));
2499 if (len > 1) {
2500 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2501 for (int i = 1; i < len; i++)
2502 args1->obj_at_put(i-1, args->obj_at(i));
2503 info = Handle(THREAD, args1);
2504 }
2505 }
2506 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2507 "caller must supply a valid BSM");
2508
2509 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2510 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2511
2512 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2513 assert(appendix_box->obj_at(0) == NULL, "");
2514
2515 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2516 JavaCallArguments args;
2517 args.push_oop(caller->java_mirror());
2518 args.push_oop(bsm());
2519 args.push_oop(method_name());
2520 args.push_oop(method_type());
2521 args.push_oop(info());
2522 args.push_oop(appendix_box);
2523 JavaValue result(T_OBJECT);
2524 JavaCalls::call_static(&result,
2525 SystemDictionary::MethodHandleNatives_klass(),
2526 vmSymbols::linkCallSite_name(),
2527 vmSymbols::linkCallSite_signature(),
2528 &args, CHECK_(empty));
2529 Handle mname(THREAD, (oop) result.get_jobject());
2530 (*method_type_result) = method_type;
2531 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2532 }
2533
2534 // Since the identity hash code for symbols changes when the symbols are
2535 // moved from the regular perm gen (hash in the mark word) to the shared
2536 // spaces (hash is the address), the classes loaded into the dictionary
2537 // may be in the wrong buckets.
2538
2539 void SystemDictionary::reorder_dictionary() {
2540 dictionary()->reorder_dictionary();
2541 }
2542
2543
2544 void SystemDictionary::copy_buckets(char** top, char* end) {
2545 dictionary()->copy_buckets(top, end);
2546 }
2547
2548
2549 void SystemDictionary::copy_table(char** top, char* end) {
2550 dictionary()->copy_table(top, end);
2551 }
2552
2553
2554 void SystemDictionary::reverse() {
2555 dictionary()->reverse();
2556 }
2557
2558 int SystemDictionary::number_of_classes() {
2559 return dictionary()->number_of_entries();
2560 }
2561
2562
2563 // ----------------------------------------------------------------------------
2564 #ifndef PRODUCT
2565
2566 void SystemDictionary::print() {
2567 dictionary()->print();
2568
2569 // Placeholders
2570 GCMutexLocker mu(SystemDictionary_lock);
2571 placeholders()->print();
2572
2573 // loader constraints - print under SD_lock
2574 constraints()->print();
2575 }
2576
2577 #endif
2578
2579 void SystemDictionary::verify() {
2580 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2581 guarantee(constraints() != NULL,
2582 "Verify of loader constraints failed");
2583 guarantee(dictionary()->number_of_entries() >= 0 &&
2584 placeholders()->number_of_entries() >= 0,
2585 "Verify of system dictionary failed");
2586
2587 // Verify dictionary
2588 dictionary()->verify();
2589
2590 GCMutexLocker mu(SystemDictionary_lock);
2591 placeholders()->verify();
2592
2593 // Verify constraint table
2594 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2595 constraints()->verify(dictionary(), placeholders());
2596 }
2597
2598
2599 void SystemDictionary::verify_obj_klass_present(Symbol* class_name,
2600 ClassLoaderData* loader_data) {
2601 GCMutexLocker mu(SystemDictionary_lock);
2602 Symbol* name;
2603
2604 Klass* probe = find_class(class_name, loader_data);
2605 if (probe == NULL) {
2606 probe = SystemDictionary::find_shared_class(class_name);
2607 if (probe == NULL) {
2608 name = find_placeholder(class_name, loader_data);
2609 }
2610 }
2611 guarantee(probe != NULL || name != NULL,
2612 "Loaded klasses should be in SystemDictionary");
2613 }
2614
2615 #ifndef PRODUCT
2616
2617 // statistics code
2618 class ClassStatistics: AllStatic {
2619 private:
2620 static int nclasses; // number of classes
2621 static int nmethods; // number of methods
2622 static int nmethoddata; // number of methodData
2623 static int class_size; // size of class objects in words
2624 static int method_size; // size of method objects in words
2625 static int debug_size; // size of debug info in methods
2626 static int methoddata_size; // size of methodData objects in words
2627
2628 static void do_class(Klass* k) {
2629 nclasses++;
2630 class_size += k->size();
2631 if (k->oop_is_instance()) {
2632 InstanceKlass* ik = (InstanceKlass*)k;
2633 class_size += ik->methods()->size();
2634 class_size += ik->constants()->size();
2635 class_size += ik->local_interfaces()->size();
2636 class_size += ik->transitive_interfaces()->size();
2637 // We do not have to count implementors, since we only store one!
2638 // SSS: How should these be accounted now that they have moved?
2639 // class_size += ik->fields()->length();
2640 }
2641 }
2642
2643 static void do_method(Method* m) {
2644 nmethods++;
2645 method_size += m->size();
2646 // class loader uses same objArray for empty vectors, so don't count these
2647 if (m->has_stackmap_table()) {
2648 method_size += m->stackmap_data()->size();
2649 }
2650
2651 MethodData* mdo = m->method_data();
2652 if (mdo != NULL) {
2653 nmethoddata++;
2654 methoddata_size += mdo->size();
2655 }
2656 }
2657
2658 public:
2659 static void print() {
2660 SystemDictionary::classes_do(do_class);
2661 SystemDictionary::methods_do(do_method);
2662 tty->print_cr("Class statistics:");
2663 tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
2664 tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
2665 (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
2666 tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
2667 }
2668 };
2669
2670
2671 int ClassStatistics::nclasses = 0;
2672 int ClassStatistics::nmethods = 0;
2673 int ClassStatistics::nmethoddata = 0;
2674 int ClassStatistics::class_size = 0;
2675 int ClassStatistics::method_size = 0;
2676 int ClassStatistics::debug_size = 0;
2677 int ClassStatistics::methoddata_size = 0;
2678
2679 void SystemDictionary::print_class_statistics() {
2680 ResourceMark rm;
2681 ClassStatistics::print();
2682 }
2683
2684
2685 class MethodStatistics: AllStatic {
2686 public:
2687 enum {
2688 max_parameter_size = 10
2689 };
2690 private:
2691
2692 static int _number_of_methods;
2693 static int _number_of_final_methods;
2694 static int _number_of_static_methods;
2695 static int _number_of_native_methods;
2696 static int _number_of_synchronized_methods;
2697 static int _number_of_profiled_methods;
2698 static int _number_of_bytecodes;
2699 static int _parameter_size_profile[max_parameter_size];
2700 static int _bytecodes_profile[Bytecodes::number_of_java_codes];
2701
2702 static void initialize() {
2703 _number_of_methods = 0;
2704 _number_of_final_methods = 0;
2705 _number_of_static_methods = 0;
2706 _number_of_native_methods = 0;
2707 _number_of_synchronized_methods = 0;
2708 _number_of_profiled_methods = 0;
2709 _number_of_bytecodes = 0;
2710 for (int i = 0; i < max_parameter_size ; i++) _parameter_size_profile[i] = 0;
2711 for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile [j] = 0;
2712 };
2713
2714 static void do_method(Method* m) {
2715 _number_of_methods++;
2716 // collect flag info
2717 if (m->is_final() ) _number_of_final_methods++;
2718 if (m->is_static() ) _number_of_static_methods++;
2719 if (m->is_native() ) _number_of_native_methods++;
2720 if (m->is_synchronized()) _number_of_synchronized_methods++;
2721 if (m->method_data() != NULL) _number_of_profiled_methods++;
2722 // collect parameter size info (add one for receiver, if any)
2723 _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
2724 // collect bytecodes info
2725 {
2726 Thread *thread = Thread::current();
2727 HandleMark hm(thread);
2728 BytecodeStream s(methodHandle(thread, m));
2729 Bytecodes::Code c;
2730 while ((c = s.next()) >= 0) {
2731 _number_of_bytecodes++;
2732 _bytecodes_profile[c]++;
2733 }
2734 }
2735 }
2736
2737 public:
2738 static void print() {
2739 initialize();
2740 SystemDictionary::methods_do(do_method);
2741 // generate output
2742 tty->cr();
2743 tty->print_cr("Method statistics (static):");
2744 // flag distribution
2745 tty->cr();
2746 tty->print_cr("%6d final methods %6.1f%%", _number_of_final_methods , _number_of_final_methods * 100.0F / _number_of_methods);
2747 tty->print_cr("%6d static methods %6.1f%%", _number_of_static_methods , _number_of_static_methods * 100.0F / _number_of_methods);
2748 tty->print_cr("%6d native methods %6.1f%%", _number_of_native_methods , _number_of_native_methods * 100.0F / _number_of_methods);
2749 tty->print_cr("%6d synchronized methods %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
2750 tty->print_cr("%6d profiled methods %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
2751 // parameter size profile
2752 tty->cr();
2753 { int tot = 0;
2754 int avg = 0;
2755 for (int i = 0; i < max_parameter_size; i++) {
2756 int n = _parameter_size_profile[i];
2757 tot += n;
2758 avg += n*i;
2759 tty->print_cr("parameter size = %1d: %6d methods %5.1f%%", i, n, n * 100.0F / _number_of_methods);
2760 }
2761 assert(tot == _number_of_methods, "should be the same");
2762 tty->print_cr(" %6d methods 100.0%%", _number_of_methods);
2763 tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
2764 }
2765 // bytecodes profile
2766 tty->cr();
2767 { int tot = 0;
2768 for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
2769 if (Bytecodes::is_defined(i)) {
2770 Bytecodes::Code c = Bytecodes::cast(i);
2771 int n = _bytecodes_profile[c];
2772 tot += n;
2773 tty->print_cr("%9d %7.3f%% %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
2774 }
2775 }
2776 assert(tot == _number_of_bytecodes, "should be the same");
2777 tty->print_cr("%9d 100.000%%", _number_of_bytecodes);
2778 }
2779 tty->cr();
2780 }
2781 };
2782
2783 int MethodStatistics::_number_of_methods;
2784 int MethodStatistics::_number_of_final_methods;
2785 int MethodStatistics::_number_of_static_methods;
2786 int MethodStatistics::_number_of_native_methods;
2787 int MethodStatistics::_number_of_synchronized_methods;
2788 int MethodStatistics::_number_of_profiled_methods;
2789 int MethodStatistics::_number_of_bytecodes;
2790 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
2791 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
2792
2793
2794 void SystemDictionary::print_method_statistics() {
2795 MethodStatistics::print();
2796 }
2797
2798 #endif // PRODUCT