1 /*
2 * Copyright (c) 1997, 2011, 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/dictionary.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/loaderConstraints.hpp"
29 #include "classfile/placeholders.hpp"
30 #include "classfile/resolutionErrors.hpp"
31 #include "classfile/systemDictionary.hpp"
32 #include "classfile/vmSymbols.hpp"
33 #include "interpreter/bytecodeStream.hpp"
34 #include "interpreter/interpreter.hpp"
35 #include "memory/gcLocker.hpp"
36 #include "memory/oopFactory.hpp"
37 #include "oops/instanceKlass.hpp"
38 #include "oops/instanceRefKlass.hpp"
39 #include "oops/klass.inline.hpp"
40 #include "oops/methodDataOop.hpp"
41 #include "oops/objArrayKlass.hpp"
42 #include "oops/oop.inline.hpp"
43 #include "oops/oop.inline2.hpp"
44 #include "oops/typeArrayKlass.hpp"
45 #include "prims/jvmtiEnvBase.hpp"
46 #include "prims/methodHandles.hpp"
47 #include "runtime/biasedLocking.hpp"
48 #include "runtime/fieldType.hpp"
49 #include "runtime/handles.inline.hpp"
50 #include "runtime/java.hpp"
51 #include "runtime/javaCalls.hpp"
52 #include "runtime/mutexLocker.hpp"
53 #include "runtime/signature.hpp"
54 #include "services/classLoadingService.hpp"
55 #include "services/threadService.hpp"
56
57
58 Dictionary* SystemDictionary::_dictionary = NULL;
59 PlaceholderTable* SystemDictionary::_placeholders = NULL;
60 Dictionary* SystemDictionary::_shared_dictionary = NULL;
61 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
62 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
63 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
64
65
66 int SystemDictionary::_number_of_modifications = 0;
67
68 oop SystemDictionary::_system_loader_lock_obj = NULL;
69
70 klassOop SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
71 = { NULL /*, NULL...*/ };
72
73 klassOop SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
74
75 oop SystemDictionary::_java_system_loader = NULL;
76
77 bool SystemDictionary::_has_loadClassInternal = false;
78 bool SystemDictionary::_has_checkPackageAccess = false;
79
80 // lazily initialized klass variables
81 volatile klassOop SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
82
83
84 // ----------------------------------------------------------------------------
85 // Java-level SystemLoader
86
87 oop SystemDictionary::java_system_loader() {
88 return _java_system_loader;
89 }
90
91 void SystemDictionary::compute_java_system_loader(TRAPS) {
92 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
93 JavaValue result(T_OBJECT);
94 JavaCalls::call_static(&result,
95 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
96 vmSymbols::getSystemClassLoader_name(),
97 vmSymbols::void_classloader_signature(),
98 CHECK);
99
100 _java_system_loader = (oop)result.get_jobject();
101 }
102
103
104 // ----------------------------------------------------------------------------
105 // debugging
106
107 #ifdef ASSERT
108
109 // return true if class_name contains no '.' (internal format is '/')
110 bool SystemDictionary::is_internal_format(Symbol* class_name) {
111 if (class_name != NULL) {
112 ResourceMark rm;
113 char* name = class_name->as_C_string();
114 return strchr(name, '.') == NULL;
115 } else {
116 return true;
117 }
118 }
119
120 #endif
121
122 // ----------------------------------------------------------------------------
123 // Parallel class loading check
124
125 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
126 if (UnsyncloadClass || class_loader.is_null()) return true;
127 if (AlwaysLockClassLoader) return false;
128 return java_lang_Class::parallelCapable(class_loader());
129 }
130 // ----------------------------------------------------------------------------
131 // ParallelDefineClass flag does not apply to bootclass loader
132 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
133 if (class_loader.is_null()) return false;
134 if (AllowParallelDefineClass && java_lang_Class::parallelCapable(class_loader())) {
135 return true;
136 }
137 return false;
138 }
139 // ----------------------------------------------------------------------------
140 // Resolving of classes
141
142 // Forwards to resolve_or_null
143
144 klassOop SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
145 klassOop klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
146 if (HAS_PENDING_EXCEPTION || klass == NULL) {
147 KlassHandle k_h(THREAD, klass);
148 // can return a null klass
149 klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);
150 }
151 return klass;
152 }
153
154 klassOop SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {
155 if (HAS_PENDING_EXCEPTION) {
156 // If we have a pending exception we forward it to the caller, unless throw_error is true,
157 // in which case we have to check whether the pending exception is a ClassNotFoundException,
158 // and if so convert it to a NoClassDefFoundError
159 // And chain the original ClassNotFoundException
160 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
161 ResourceMark rm(THREAD);
162 assert(klass_h() == NULL, "Should not have result with exception pending");
163 Handle e(THREAD, PENDING_EXCEPTION);
164 CLEAR_PENDING_EXCEPTION;
165 THROW_MSG_CAUSE_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
166 } else {
167 return NULL;
168 }
169 }
170 // Class not found, throw appropriate error or exception depending on value of throw_error
171 if (klass_h() == NULL) {
172 ResourceMark rm(THREAD);
173 if (throw_error) {
174 THROW_MSG_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
175 } else {
176 THROW_MSG_0(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
177 }
178 }
179 return (klassOop)klass_h();
180 }
181
182
183 klassOop SystemDictionary::resolve_or_fail(Symbol* class_name,
184 bool throw_error, TRAPS)
185 {
186 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
187 }
188
189
190 // Forwards to resolve_instance_class_or_null
191
192 klassOop SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
193 assert(!THREAD->is_Compiler_thread(), "Can not load classes with the Compiler thread");
194 if (FieldType::is_array(class_name)) {
195 return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
196 } else if (FieldType::is_obj(class_name)) {
197 ResourceMark rm(THREAD);
198 // Ignore wrapping L and ;.
199 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
200 class_name->utf8_length() - 2, CHECK_NULL);
201 return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL);
202 } else {
203 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
204 }
205 }
206
207 klassOop SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
208 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
209 }
210
211 // Forwards to resolve_instance_class_or_null
212
213 klassOop SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
214 Handle class_loader,
215 Handle protection_domain,
216 TRAPS) {
217 assert(FieldType::is_array(class_name), "must be array");
218 klassOop k = NULL;
219 FieldArrayInfo fd;
220 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
221 // of this call
222 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
223 if (t == T_OBJECT) {
224 // naked oop "k" is OK here -- we assign back into it
225 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
226 class_loader,
227 protection_domain,
228 CHECK_NULL);
229 if (k != NULL) {
230 k = Klass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
231 }
232 } else {
233 k = Universe::typeArrayKlassObj(t);
234 k = typeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
235 }
236 return k;
237 }
238
239
240 // Must be called for any super-class or super-interface resolution
241 // during class definition to allow class circularity checking
242 // super-interface callers:
243 // parse_interfaces - for defineClass & jvmtiRedefineClasses
244 // super-class callers:
245 // ClassFileParser - for defineClass & jvmtiRedefineClasses
246 // load_shared_class - while loading a class from shared archive
247 // resolve_instance_class_or_null:
248 // via: handle_parallel_super_load
249 // when resolving a class that has an existing placeholder with
250 // a saved superclass [i.e. a defineClass is currently in progress]
251 // if another thread is trying to resolve the class, it must do
252 // super-class checks on its own thread to catch class circularity
253 // This last call is critical in class circularity checking for cases
254 // where classloading is delegated to different threads and the
255 // classloader lock is released.
256 // Take the case: Base->Super->Base
257 // 1. If thread T1 tries to do a defineClass of class Base
258 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
259 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
260 // so it tries to load Super
261 // 3. If we load the class internally, or user classloader uses same thread
262 // loadClassFromxxx or defineClass via parseClassFile Super ...
263 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
264 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
265 // 3.4 calls resolve_super_or_fail Base
266 // 3.5 finds T1,Base -> throws class circularity
267 //OR 4. If T2 tries to resolve Super via defineClass Super ...
268 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
269 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
270 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
271 // 4.4 finds T2, Super -> throws class circularity
272 // Must be called, even if superclass is null, since this is
273 // where the placeholder entry is created which claims this
274 // thread is loading this class/classloader.
275 klassOop SystemDictionary::resolve_super_or_fail(Symbol* child_name,
276 Symbol* class_name,
277 Handle class_loader,
278 Handle protection_domain,
279 bool is_superclass,
280 TRAPS) {
281
282 // Try to get one of the well-known klasses.
283 // They are trusted, and do not participate in circularities.
284 if (LinkWellKnownClasses) {
285 klassOop k = find_well_known_klass(class_name);
286 if (k != NULL) {
287 return k;
288 }
289 }
290
291 // Double-check, if child class is already loaded, just return super-class,interface
292 // Don't add a placedholder if already loaded, i.e. already in system dictionary
293 // Make sure there's a placeholder for the *child* before resolving.
294 // Used as a claim that this thread is currently loading superclass/classloader
295 // Used here for ClassCircularity checks and also for heap verification
296 // (every instanceKlass in the heap needs to be in the system dictionary
297 // or have a placeholder).
298 // Must check ClassCircularity before checking if super class is already loaded
299 //
300 // We might not already have a placeholder if this child_name was
301 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
302 // the name of the class might not be known until the stream is actually
303 // parsed.
304 // Bugs 4643874, 4715493
305 // compute_hash can have a safepoint
306
307 unsigned int d_hash = dictionary()->compute_hash(child_name, class_loader);
308 int d_index = dictionary()->hash_to_index(d_hash);
309 unsigned int p_hash = placeholders()->compute_hash(child_name, class_loader);
310 int p_index = placeholders()->hash_to_index(p_hash);
311 // can't throw error holding a lock
312 bool child_already_loaded = false;
313 bool throw_circularity_error = false;
314 {
315 MutexLocker mu(SystemDictionary_lock, THREAD);
316 klassOop childk = find_class(d_index, d_hash, child_name, class_loader);
317 klassOop quicksuperk;
318 // to support // loading: if child done loading, just return superclass
319 // if class_name, & class_loader don't match:
320 // if initial define, SD update will give LinkageError
321 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
322 // so we don't throw an exception here.
323 // see: nsk redefclass014 & java.lang.instrument Instrument032
324 if ((childk != NULL ) && (is_superclass) &&
325 ((quicksuperk = instanceKlass::cast(childk)->super()) != NULL) &&
326
327 ((Klass::cast(quicksuperk)->name() == class_name) &&
328 (Klass::cast(quicksuperk)->class_loader() == class_loader()))) {
329 return quicksuperk;
330 } else {
331 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, class_loader);
332 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
333 throw_circularity_error = true;
334 }
335 }
336 if (!throw_circularity_error) {
337 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, class_loader, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
338 }
339 }
340 if (throw_circularity_error) {
341 ResourceMark rm(THREAD);
342 THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
343 }
344
345 // java.lang.Object should have been found above
346 assert(class_name != NULL, "null super class for resolving");
347 // Resolve the super class or interface, check results on return
348 klassOop superk = NULL;
349 superk = SystemDictionary::resolve_or_null(class_name,
350 class_loader,
351 protection_domain,
352 THREAD);
353
354 KlassHandle superk_h(THREAD, superk);
355
356 // Note: clean up of placeholders currently in callers of
357 // resolve_super_or_fail - either at update_dictionary time
358 // or on error
359 {
360 MutexLocker mu(SystemDictionary_lock, THREAD);
361 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, class_loader);
362 if (probe != NULL) {
363 probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER);
364 }
365 }
366 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
367 // can null superk
368 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));
369 }
370
371 return superk_h();
372 }
373
374 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
375 Handle class_loader,
376 Handle protection_domain,
377 TRAPS) {
378 if(!has_checkPackageAccess()) return;
379
380 // Now we have to call back to java to check if the initating class has access
381 JavaValue result(T_VOID);
382 if (TraceProtectionDomainVerification) {
383 // Print out trace information
384 tty->print_cr("Checking package access");
385 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
386 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
387 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
388 }
389
390 assert(class_loader() != NULL, "should not have non-null protection domain for null classloader");
391
392 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
393 JavaCalls::call_special(&result,
394 class_loader,
395 system_loader,
396 vmSymbols::checkPackageAccess_name(),
397 vmSymbols::class_protectiondomain_signature(),
398 Handle(THREAD, klass->java_mirror()),
399 protection_domain,
400 THREAD);
401
402 if (TraceProtectionDomainVerification) {
403 if (HAS_PENDING_EXCEPTION) {
404 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
405 } else {
406 tty->print_cr(" -> granted");
407 }
408 tty->cr();
409 }
410
411 if (HAS_PENDING_EXCEPTION) return;
412
413 // If no exception has been thrown, we have validated the protection domain
414 // Insert the protection domain of the initiating class into the set.
415 {
416 // We recalculate the entry here -- we've called out to java since
417 // the last time it was calculated.
418 Symbol* kn = klass->name();
419 unsigned int d_hash = dictionary()->compute_hash(kn, class_loader);
420 int d_index = dictionary()->hash_to_index(d_hash);
421
422 MutexLocker mu(SystemDictionary_lock, THREAD);
423 {
424 // Note that we have an entry, and entries can be deleted only during GC,
425 // so we cannot allow GC to occur while we're holding this entry.
426
427 // We're using a No_Safepoint_Verifier to catch any place where we
428 // might potentially do a GC at all.
429 // SystemDictionary::do_unloading() asserts that classes are only
430 // unloaded at a safepoint.
431 No_Safepoint_Verifier nosafepoint;
432 dictionary()->add_protection_domain(d_index, d_hash, klass, class_loader,
433 protection_domain, THREAD);
434 }
435 }
436 }
437
438 // We only get here if this thread finds that another thread
439 // has already claimed the placeholder token for the current operation,
440 // but that other thread either never owned or gave up the
441 // object lock
442 // Waits on SystemDictionary_lock to indicate placeholder table updated
443 // On return, caller must recheck placeholder table state
444 //
445 // We only get here if
446 // 1) custom classLoader, i.e. not bootstrap classloader
447 // 2) UnsyncloadClass not set
448 // 3) custom classLoader has broken the class loader objectLock
449 // so another thread got here in parallel
450 //
451 // lockObject must be held.
452 // Complicated dance due to lock ordering:
453 // Must first release the classloader object lock to
454 // allow initial definer to complete the class definition
455 // and to avoid deadlock
456 // Reclaim classloader lock object with same original recursion count
457 // Must release SystemDictionary_lock after notify, since
458 // class loader lock must be claimed before SystemDictionary_lock
459 // to prevent deadlocks
460 //
461 // The notify allows applications that did an untimed wait() on
462 // the classloader object lock to not hang.
463 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
464 assert_lock_strong(SystemDictionary_lock);
465
466 bool calledholdinglock
467 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
468 assert(calledholdinglock,"must hold lock for notify");
469 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
470 ObjectSynchronizer::notifyall(lockObject, THREAD);
471 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
472 SystemDictionary_lock->wait();
473 SystemDictionary_lock->unlock();
474 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
475 SystemDictionary_lock->lock();
476 }
477
478 // If the class in is in the placeholder table, class loading is in progress
479 // For cases where the application changes threads to load classes, it
480 // is critical to ClassCircularity detection that we try loading
481 // the superclass on the same thread internally, so we do parallel
482 // super class loading here.
483 // This also is critical in cases where the original thread gets stalled
484 // even in non-circularity situations.
485 // Note: only one thread can define the class, but multiple can resolve
486 // Note: must call resolve_super_or_fail even if null super -
487 // to force placeholder entry creation for this class for circularity detection
488 // Caller must check for pending exception
489 // Returns non-null klassOop if other thread has completed load
490 // and we are done,
491 // If return null klassOop and no pending exception, the caller must load the class
492 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
493 Symbol* name, Symbol* superclassname, Handle class_loader,
494 Handle protection_domain, Handle lockObject, TRAPS) {
495
496 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
497 unsigned int d_hash = dictionary()->compute_hash(name, class_loader);
498 int d_index = dictionary()->hash_to_index(d_hash);
499 unsigned int p_hash = placeholders()->compute_hash(name, class_loader);
500 int p_index = placeholders()->hash_to_index(p_hash);
501
502 // superk is not used, resolve_super called for circularity check only
503 // This code is reached in two situations. One if this thread
504 // is loading the same class twice (e.g. ClassCircularity, or
505 // java.lang.instrument).
506 // The second is if another thread started the resolve_super first
507 // and has not yet finished.
508 // In both cases the original caller will clean up the placeholder
509 // entry on error.
510 klassOop superk = SystemDictionary::resolve_super_or_fail(name,
511 superclassname,
512 class_loader,
513 protection_domain,
514 true,
515 CHECK_(nh));
516 // We don't redefine the class, so we just need to clean up if there
517 // was not an error (don't want to modify any system dictionary
518 // data structures).
519 {
520 MutexLocker mu(SystemDictionary_lock, THREAD);
521 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
522 SystemDictionary_lock->notify_all();
523 }
524
525 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
526 // Serial class loaders and bootstrap classloader do wait for superclass loads
527 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
528 MutexLocker mu(SystemDictionary_lock, THREAD);
529 // Check if classloading completed while we were loading superclass or waiting
530 klassOop check = find_class(d_index, d_hash, name, class_loader);
531 if (check != NULL) {
532 // Klass is already loaded, so just return it
533 return(instanceKlassHandle(THREAD, check));
534 } else {
535 return nh;
536 }
537 }
538
539 // must loop to both handle other placeholder updates
540 // and spurious notifications
541 bool super_load_in_progress = true;
542 PlaceholderEntry* placeholder;
543 while (super_load_in_progress) {
544 MutexLocker mu(SystemDictionary_lock, THREAD);
545 // Check if classloading completed while we were loading superclass or waiting
546 klassOop check = find_class(d_index, d_hash, name, class_loader);
547 if (check != NULL) {
548 // Klass is already loaded, so just return it
549 return(instanceKlassHandle(THREAD, check));
550 } else {
551 placeholder = placeholders()->get_entry(p_index, p_hash, name, class_loader);
552 if (placeholder && placeholder->super_load_in_progress() ){
553 // Before UnsyncloadClass:
554 // We only get here if the application has released the
555 // classloader lock when another thread was in the middle of loading a
556 // superclass/superinterface for this class, and now
557 // this thread is also trying to load this class.
558 // To minimize surprises, the first thread that started to
559 // load a class should be the one to complete the loading
560 // with the classfile it initially expected.
561 // This logic has the current thread wait once it has done
562 // all the superclass/superinterface loading it can, until
563 // the original thread completes the class loading or fails
564 // If it completes we will use the resulting instanceKlass
565 // which we will find below in the systemDictionary.
566 // We also get here for parallel bootstrap classloader
567 if (class_loader.is_null()) {
568 SystemDictionary_lock->wait();
569 } else {
570 double_lock_wait(lockObject, THREAD);
571 }
572 } else {
573 // If not in SD and not in PH, other thread's load must have failed
574 super_load_in_progress = false;
575 }
576 }
577 }
578 return (nh);
579 }
580
581
582 klassOop SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle class_loader, Handle protection_domain, TRAPS) {
583 assert(name != NULL && !FieldType::is_array(name) &&
584 !FieldType::is_obj(name), "invalid class name");
585
586 // UseNewReflection
587 // Fix for 4474172; see evaluation for more details
588 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
589
590 // Do lookup to see if class already exist and the protection domain
591 // has the right access
592 unsigned int d_hash = dictionary()->compute_hash(name, class_loader);
593 int d_index = dictionary()->hash_to_index(d_hash);
594 klassOop probe = dictionary()->find(d_index, d_hash, name, class_loader,
595 protection_domain, THREAD);
596 if (probe != NULL) return probe;
597
598
599 // Non-bootstrap class loaders will call out to class loader and
600 // define via jvm/jni_DefineClass which will acquire the
601 // class loader object lock to protect against multiple threads
602 // defining the class in parallel by accident.
603 // This lock must be acquired here so the waiter will find
604 // any successful result in the SystemDictionary and not attempt
605 // the define
606 // ParallelCapable Classloaders and the bootstrap classloader,
607 // or all classloaders with UnsyncloadClass do not acquire lock here
608 bool DoObjectLock = true;
609 if (is_parallelCapable(class_loader)) {
610 DoObjectLock = false;
611 }
612
613 unsigned int p_hash = placeholders()->compute_hash(name, class_loader);
614 int p_index = placeholders()->hash_to_index(p_hash);
615
616 // Class is not in SystemDictionary so we have to do loading.
617 // Make sure we are synchronized on the class loader before we proceed
618 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
619 check_loader_lock_contention(lockObject, THREAD);
620 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
621
622 // Check again (after locking) if class already exist in SystemDictionary
623 bool class_has_been_loaded = false;
624 bool super_load_in_progress = false;
625 bool havesupername = false;
626 instanceKlassHandle k;
627 PlaceholderEntry* placeholder;
628 Symbol* superclassname = NULL;
629
630 {
631 MutexLocker mu(SystemDictionary_lock, THREAD);
632 klassOop check = find_class(d_index, d_hash, name, class_loader);
633 if (check != NULL) {
634 // Klass is already loaded, so just return it
635 class_has_been_loaded = true;
636 k = instanceKlassHandle(THREAD, check);
637 } else {
638 placeholder = placeholders()->get_entry(p_index, p_hash, name, class_loader);
639 if (placeholder && placeholder->super_load_in_progress()) {
640 super_load_in_progress = true;
641 if (placeholder->havesupername() == true) {
642 superclassname = placeholder->supername();
643 havesupername = true;
644 }
645 }
646 }
647 }
648
649 // If the class in is in the placeholder table, class loading is in progress
650 if (super_load_in_progress && havesupername==true) {
651 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
652 class_loader, protection_domain, lockObject, THREAD);
653 if (HAS_PENDING_EXCEPTION) {
654 return NULL;
655 }
656 if (!k.is_null()) {
657 class_has_been_loaded = true;
658 }
659 }
660
661 if (!class_has_been_loaded) {
662
663 // add placeholder entry to record loading instance class
664 // Five cases:
665 // All cases need to prevent modifying bootclasssearchpath
666 // in parallel with a classload of same classname
667 // Redefineclasses uses existence of the placeholder for the duration
668 // of the class load to prevent concurrent redefinition of not completely
669 // defined classes.
670 // case 1. traditional classloaders that rely on the classloader object lock
671 // - no other need for LOAD_INSTANCE
672 // case 2. traditional classloaders that break the classloader object lock
673 // as a deadlock workaround. Detection of this case requires that
674 // this check is done while holding the classloader object lock,
675 // and that lock is still held when calling classloader's loadClass.
676 // For these classloaders, we ensure that the first requestor
677 // completes the load and other requestors wait for completion.
678 // case 3. UnsyncloadClass - don't use objectLocker
679 // With this flag, we allow parallel classloading of a
680 // class/classloader pair
681 // case4. Bootstrap classloader - don't own objectLocker
682 // This classloader supports parallelism at the classloader level,
683 // but only allows a single load of a class/classloader pair.
684 // No performance benefit and no deadlock issues.
685 // case 5. parallelCapable user level classloaders - without objectLocker
686 // Allow parallel classloading of a class/classloader pair
687 bool throw_circularity_error = false;
688 {
689 MutexLocker mu(SystemDictionary_lock, THREAD);
690 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
691 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
692 if (oldprobe) {
693 // only need check_seen_thread once, not on each loop
694 // 6341374 java/lang/Instrument with -Xcomp
695 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
696 throw_circularity_error = true;
697 } else {
698 // case 1: traditional: should never see load_in_progress.
699 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
700
701 // case 4: bootstrap classloader: prevent futile classloading,
702 // wait on first requestor
703 if (class_loader.is_null()) {
704 SystemDictionary_lock->wait();
705 } else {
706 // case 2: traditional with broken classloader lock. wait on first
707 // requestor.
708 double_lock_wait(lockObject, THREAD);
709 }
710 // Check if classloading completed while we were waiting
711 klassOop check = find_class(d_index, d_hash, name, class_loader);
712 if (check != NULL) {
713 // Klass is already loaded, so just return it
714 k = instanceKlassHandle(THREAD, check);
715 class_has_been_loaded = true;
716 }
717 // check if other thread failed to load and cleaned up
718 oldprobe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
719 }
720 }
721 }
722 }
723 // All cases: add LOAD_INSTANCE
724 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
725 // LOAD_INSTANCE in parallel
726 // add placeholder entry even if error - callers will remove on error
727 if (!throw_circularity_error && !class_has_been_loaded) {
728 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, class_loader, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
729 // For class loaders that do not acquire the classloader object lock,
730 // if they did not catch another thread holding LOAD_INSTANCE,
731 // need a check analogous to the acquire ObjectLocker/find_class
732 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
733 // one final check if the load has already completed
734 // class loaders holding the ObjectLock shouldn't find the class here
735 klassOop check = find_class(d_index, d_hash, name, class_loader);
736 if (check != NULL) {
737 // Klass is already loaded, so just return it
738 k = instanceKlassHandle(THREAD, check);
739 class_has_been_loaded = true;
740 newprobe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);
741 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
742 SystemDictionary_lock->notify_all();
743 }
744 }
745 }
746 // must throw error outside of owning lock
747 if (throw_circularity_error) {
748 ResourceMark rm(THREAD);
749 THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
750 }
751
752 if (!class_has_been_loaded) {
753
754 // Do actual loading
755 k = load_instance_class(name, class_loader, THREAD);
756
757 // For UnsyncloadClass only
758 // If they got a linkageError, check if a parallel class load succeeded.
759 // If it did, then for bytecode resolution the specification requires
760 // that we return the same result we did for the other thread, i.e. the
761 // successfully loaded instanceKlass
762 // Should not get here for classloaders that support parallelism
763 // with the new cleaner mechanism, even with AllowParallelDefineClass
764 // Bootstrap goes through here to allow for an extra guarantee check
765 if (UnsyncloadClass || (class_loader.is_null())) {
766 if (k.is_null() && HAS_PENDING_EXCEPTION
767 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
768 MutexLocker mu(SystemDictionary_lock, THREAD);
769 klassOop check = find_class(d_index, d_hash, name, class_loader);
770 if (check != NULL) {
771 // Klass is already loaded, so just use it
772 k = instanceKlassHandle(THREAD, check);
773 CLEAR_PENDING_EXCEPTION;
774 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
775 }
776 }
777 }
778
779 // clean up placeholder entries for success or error
780 // This cleans up LOAD_INSTANCE entries
781 // It also cleans up LOAD_SUPER entries on errors from
782 // calling load_instance_class
783 {
784 MutexLocker mu(SystemDictionary_lock, THREAD);
785 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
786 if (probe != NULL) {
787 probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);
788 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
789 SystemDictionary_lock->notify_all();
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 if (HAS_PENDING_EXCEPTION || k.is_null()) {
817 // On error, clean up placeholders
818 {
819 MutexLocker mu(SystemDictionary_lock, THREAD);
820 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
821 SystemDictionary_lock->notify_all();
822 }
823 return NULL;
824 }
825 }
826 }
827
828 #ifdef ASSERT
829 {
830 Handle loader (THREAD, k->class_loader());
831 MutexLocker mu(SystemDictionary_lock, THREAD);
832 oop kk = find_class(name, loader);
833 assert(kk == k(), "should be present in dictionary");
834 }
835 #endif
836
837 // return if the protection domain in NULL
838 if (protection_domain() == NULL) return k();
839
840 // Check the protection domain has the right access
841 {
842 MutexLocker mu(SystemDictionary_lock, THREAD);
843 // Note that we have an entry, and entries can be deleted only during GC,
844 // so we cannot allow GC to occur while we're holding this entry.
845 // We're using a No_Safepoint_Verifier to catch any place where we
846 // might potentially do a GC at all.
847 // SystemDictionary::do_unloading() asserts that classes are only
848 // unloaded at a safepoint.
849 No_Safepoint_Verifier nosafepoint;
850 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
851 class_loader,
852 protection_domain)) {
853 return k();
854 }
855 }
856
857 // Verify protection domain. If it fails an exception is thrown
858 validate_protection_domain(k, class_loader, protection_domain, CHECK_(klassOop(NULL)));
859
860 return k();
861 }
862
863
864 // This routine does not lock the system dictionary.
865 //
866 // Since readers don't hold a lock, we must make sure that system
867 // dictionary entries are only removed at a safepoint (when only one
868 // thread is running), and are added to in a safe way (all links must
869 // be updated in an MT-safe manner).
870 //
871 // Callers should be aware that an entry could be added just after
872 // _dictionary->bucket(index) is read here, so the caller will not see
873 // the new entry.
874
875 klassOop SystemDictionary::find(Symbol* class_name,
876 Handle class_loader,
877 Handle protection_domain,
878 TRAPS) {
879
880 // UseNewReflection
881 // The result of this call should be consistent with the result
882 // of the call to resolve_instance_class_or_null().
883 // See evaluation 6790209 and 4474172 for more details.
884 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
885
886 unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);
887 int d_index = dictionary()->hash_to_index(d_hash);
888
889 {
890 // Note that we have an entry, and entries can be deleted only during GC,
891 // so we cannot allow GC to occur while we're holding this entry.
892 // We're using a No_Safepoint_Verifier to catch any place where we
893 // might potentially do a GC at all.
894 // SystemDictionary::do_unloading() asserts that classes are only
895 // unloaded at a safepoint.
896 No_Safepoint_Verifier nosafepoint;
897 return dictionary()->find(d_index, d_hash, class_name, class_loader,
898 protection_domain, THREAD);
899 }
900 }
901
902
903 // Look for a loaded instance or array klass by name. Do not do any loading.
904 // return NULL in case of error.
905 klassOop SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
906 Handle class_loader,
907 Handle protection_domain,
908 TRAPS) {
909 klassOop k = NULL;
910 assert(class_name != NULL, "class name must be non NULL");
911
912 // Try to get one of the well-known klasses.
913 if (LinkWellKnownClasses) {
914 k = find_well_known_klass(class_name);
915 if (k != NULL) {
916 return k;
917 }
918 }
919
920 if (FieldType::is_array(class_name)) {
921 // The name refers to an array. Parse the name.
922 // dimension and object_key in FieldArrayInfo are assigned as a
923 // side-effect of this call
924 FieldArrayInfo fd;
925 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
926 if (t != T_OBJECT) {
927 k = Universe::typeArrayKlassObj(t);
928 } else {
929 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
930 }
931 if (k != NULL) {
932 k = Klass::cast(k)->array_klass_or_null(fd.dimension());
933 }
934 } else {
935 k = find(class_name, class_loader, protection_domain, THREAD);
936 }
937 return k;
938 }
939
940 // Quick range check for names of well-known classes:
941 static Symbol* wk_klass_name_limits[2] = {NULL, NULL};
942
943 #ifndef PRODUCT
944 static int find_wkk_calls, find_wkk_probes, find_wkk_wins;
945 // counts for "hello world": 3983, 1616, 1075
946 // => 60% hit after limit guard, 25% total win rate
947 #endif
948
949 klassOop SystemDictionary::find_well_known_klass(Symbol* class_name) {
950 // A bounds-check on class_name will quickly get a negative result.
951 NOT_PRODUCT(find_wkk_calls++);
952 if (class_name >= wk_klass_name_limits[0] &&
953 class_name <= wk_klass_name_limits[1]) {
954 NOT_PRODUCT(find_wkk_probes++);
955 vmSymbols::SID sid = vmSymbols::find_sid(class_name);
956 if (sid != vmSymbols::NO_SID) {
957 klassOop k = NULL;
958 switch (sid) {
959 #define WK_KLASS_CASE(name, symbol, ignore_option) \
960 case vmSymbols::VM_SYMBOL_ENUM_NAME(symbol): \
961 k = WK_KLASS(name); break;
962 WK_KLASSES_DO(WK_KLASS_CASE)
963 #undef WK_KLASS_CASE
964 }
965 NOT_PRODUCT(if (k != NULL) find_wkk_wins++);
966 return k;
967 }
968 }
969 return NULL;
970 }
971
972 // Note: this method is much like resolve_from_stream, but
973 // updates no supplemental data structures.
974 // TODO consolidate the two methods with a helper routine?
975 klassOop SystemDictionary::parse_stream(Symbol* class_name,
976 Handle class_loader,
977 Handle protection_domain,
978 ClassFileStream* st,
979 KlassHandle host_klass,
980 GrowableArray<Handle>* cp_patches,
981 TRAPS) {
982 TempNewSymbol parsed_name = NULL;
983
984 // Parse the stream. Note that we do this even though this klass might
985 // already be present in the SystemDictionary, otherwise we would not
986 // throw potential ClassFormatErrors.
987 //
988 // Note: "name" is updated.
989 // Further note: a placeholder will be added for this class when
990 // super classes are loaded (resolve_super_or_fail). We expect this
991 // to be called for all classes but java.lang.Object; and we preload
992 // java.lang.Object through resolve_or_fail, not this path.
993
994 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
995 class_loader,
996 protection_domain,
997 host_klass,
998 cp_patches,
999 parsed_name,
1000 true,
1001 THREAD);
1002
1003 // We don't redefine the class, so we just need to clean up whether there
1004 // was an error or not (don't want to modify any system dictionary
1005 // data structures).
1006 // Parsed name could be null if we threw an error before we got far
1007 // enough along to parse it -- in that case, there is nothing to clean up.
1008 if (parsed_name != NULL) {
1009 unsigned int p_hash = placeholders()->compute_hash(parsed_name,
1010 class_loader);
1011 int p_index = placeholders()->hash_to_index(p_hash);
1012 {
1013 MutexLocker mu(SystemDictionary_lock, THREAD);
1014 placeholders()->find_and_remove(p_index, p_hash, parsed_name, class_loader, THREAD);
1015 SystemDictionary_lock->notify_all();
1016 }
1017 }
1018
1019 if (host_klass.not_null() && k.not_null()) {
1020 assert(EnableInvokeDynamic, "");
1021 // If it's anonymous, initialize it now, since nobody else will.
1022 k->set_host_klass(host_klass());
1023
1024 {
1025 MutexLocker mu_r(Compile_lock, THREAD);
1026
1027 // Add to class hierarchy, initialize vtables, and do possible
1028 // deoptimizations.
1029 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1030
1031 // But, do not add to system dictionary.
1032 }
1033
1034 k->eager_initialize(THREAD);
1035
1036 // notify jvmti
1037 if (JvmtiExport::should_post_class_load()) {
1038 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1039 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1040 }
1041 }
1042
1043 return k();
1044 }
1045
1046 // Add a klass to the system from a stream (called by jni_DefineClass and
1047 // JVM_DefineClass).
1048 // Note: class_name can be NULL. In that case we do not know the name of
1049 // the class until we have parsed the stream.
1050
1051 klassOop SystemDictionary::resolve_from_stream(Symbol* class_name,
1052 Handle class_loader,
1053 Handle protection_domain,
1054 ClassFileStream* st,
1055 bool verify,
1056 TRAPS) {
1057
1058 // Classloaders that support parallelism, e.g. bootstrap classloader,
1059 // or all classloaders with UnsyncloadClass do not acquire lock here
1060 bool DoObjectLock = true;
1061 if (is_parallelCapable(class_loader)) {
1062 DoObjectLock = false;
1063 }
1064
1065 // Make sure we are synchronized on the class loader before we proceed
1066 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1067 check_loader_lock_contention(lockObject, THREAD);
1068 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1069
1070 TempNewSymbol parsed_name = NULL;
1071
1072 // Parse the stream. Note that we do this even though this klass might
1073 // already be present in the SystemDictionary, otherwise we would not
1074 // throw potential ClassFormatErrors.
1075 //
1076 // Note: "name" is updated.
1077 // Further note: a placeholder will be added for this class when
1078 // super classes are loaded (resolve_super_or_fail). We expect this
1079 // to be called for all classes but java.lang.Object; and we preload
1080 // java.lang.Object through resolve_or_fail, not this path.
1081
1082 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1083 class_loader,
1084 protection_domain,
1085 parsed_name,
1086 verify,
1087 THREAD);
1088
1089 const char* pkg = "java/";
1090 if (!HAS_PENDING_EXCEPTION &&
1091 !class_loader.is_null() &&
1092 parsed_name != NULL &&
1093 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1094 // It is illegal to define classes in the "java." package from
1095 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1096 ResourceMark rm(THREAD);
1097 char* name = parsed_name->as_C_string();
1098 char* index = strrchr(name, '/');
1099 *index = '\0'; // chop to just the package name
1100 while ((index = strchr(name, '/')) != NULL) {
1101 *index = '.'; // replace '/' with '.' in package name
1102 }
1103 const char* fmt = "Prohibited package name: %s";
1104 size_t len = strlen(fmt) + strlen(name);
1105 char* message = NEW_RESOURCE_ARRAY(char, len);
1106 jio_snprintf(message, len, fmt, name);
1107 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1108 vmSymbols::java_lang_SecurityException(), message);
1109 }
1110
1111 if (!HAS_PENDING_EXCEPTION) {
1112 assert(parsed_name != NULL, "Sanity");
1113 assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1114 // Verification prevents us from creating names with dots in them, this
1115 // asserts that that's the case.
1116 assert(is_internal_format(parsed_name),
1117 "external class name format used internally");
1118
1119 // Add class just loaded
1120 // If a class loader supports parallel classloading handle parallel define requests
1121 // find_or_define_instance_class may return a different instanceKlass
1122 if (is_parallelCapable(class_loader)) {
1123 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1124 } else {
1125 define_instance_class(k, THREAD);
1126 }
1127 }
1128
1129 // If parsing the class file or define_instance_class failed, we
1130 // need to remove the placeholder added on our behalf. But we
1131 // must make sure parsed_name is valid first (it won't be if we had
1132 // a format error before the class was parsed far enough to
1133 // find the name).
1134 if (HAS_PENDING_EXCEPTION && parsed_name != NULL) {
1135 unsigned int p_hash = placeholders()->compute_hash(parsed_name,
1136 class_loader);
1137 int p_index = placeholders()->hash_to_index(p_hash);
1138 {
1139 MutexLocker mu(SystemDictionary_lock, THREAD);
1140 placeholders()->find_and_remove(p_index, p_hash, parsed_name, class_loader, THREAD);
1141 SystemDictionary_lock->notify_all();
1142 }
1143 return NULL;
1144 }
1145
1146 // Make sure that we didn't leave a place holder in the
1147 // SystemDictionary; this is only done on success
1148 debug_only( {
1149 if (!HAS_PENDING_EXCEPTION) {
1150 assert(parsed_name != NULL, "parsed_name is still null?");
1151 Symbol* h_name = k->name();
1152 Handle h_loader (THREAD, k->class_loader());
1153
1154 MutexLocker mu(SystemDictionary_lock, THREAD);
1155
1156 klassOop check = find_class(parsed_name, class_loader);
1157 assert(check == k(), "should be present in the dictionary");
1158
1159 klassOop check2 = find_class(h_name, h_loader);
1160 assert(check == check2, "name inconsistancy in SystemDictionary");
1161 }
1162 } );
1163
1164 return k();
1165 }
1166
1167
1168 void SystemDictionary::set_shared_dictionary(HashtableBucket* t, int length,
1169 int number_of_entries) {
1170 assert(length == _nof_buckets * sizeof(HashtableBucket),
1171 "bad shared dictionary size.");
1172 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1173 }
1174
1175
1176 // If there is a shared dictionary, then find the entry for the
1177 // given shared system class, if any.
1178
1179 klassOop SystemDictionary::find_shared_class(Symbol* class_name) {
1180 if (shared_dictionary() != NULL) {
1181 unsigned int d_hash = dictionary()->compute_hash(class_name, Handle());
1182 int d_index = dictionary()->hash_to_index(d_hash);
1183 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1184 } else {
1185 return NULL;
1186 }
1187 }
1188
1189
1190 // Load a class from the shared spaces (found through the shared system
1191 // dictionary). Force the superclass and all interfaces to be loaded.
1192 // Update the class definition to include sibling classes and no
1193 // subclasses (yet). [Classes in the shared space are not part of the
1194 // object hierarchy until loaded.]
1195
1196 instanceKlassHandle SystemDictionary::load_shared_class(
1197 Symbol* class_name, Handle class_loader, TRAPS) {
1198 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1199 return load_shared_class(ik, class_loader, THREAD);
1200 }
1201
1202 // Note well! Changes to this method may affect oop access order
1203 // in the shared archive. Please take care to not make changes that
1204 // adversely affect cold start time by changing the oop access order
1205 // that is specified in dump.cpp MarkAndMoveOrderedReadOnly and
1206 // MarkAndMoveOrderedReadWrite closures.
1207 instanceKlassHandle SystemDictionary::load_shared_class(
1208 instanceKlassHandle ik, Handle class_loader, TRAPS) {
1209 assert(class_loader.is_null(), "non-null classloader for shared class?");
1210 if (ik.not_null()) {
1211 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1212 Symbol* class_name = ik->name();
1213
1214 // Found the class, now load the superclass and interfaces. If they
1215 // are shared, add them to the main system dictionary and reset
1216 // their hierarchy references (supers, subs, and interfaces).
1217
1218 if (ik->super() != NULL) {
1219 Symbol* cn = ik->super()->klass_part()->name();
1220 resolve_super_or_fail(class_name, cn,
1221 class_loader, Handle(), true, CHECK_(nh));
1222 }
1223
1224 objArrayHandle interfaces (THREAD, ik->local_interfaces());
1225 int num_interfaces = interfaces->length();
1226 for (int index = 0; index < num_interfaces; index++) {
1227 klassOop k = klassOop(interfaces->obj_at(index));
1228
1229 // Note: can not use instanceKlass::cast here because
1230 // interfaces' instanceKlass's C++ vtbls haven't been
1231 // reinitialized yet (they will be once the interface classes
1232 // are loaded)
1233 Symbol* name = k->klass_part()->name();
1234 resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(nh));
1235 }
1236
1237 // Adjust methods to recover missing data. They need addresses for
1238 // interpreter entry points and their default native method address
1239 // must be reset.
1240
1241 // Updating methods must be done under a lock so multiple
1242 // threads don't update these in parallel
1243 // Shared classes are all currently loaded by the bootstrap
1244 // classloader, so this will never cause a deadlock on
1245 // a custom class loader lock.
1246
1247 {
1248 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1249 check_loader_lock_contention(lockObject, THREAD);
1250 ObjectLocker ol(lockObject, THREAD, true);
1251
1252 objArrayHandle methods (THREAD, ik->methods());
1253 int num_methods = methods->length();
1254 for (int index2 = 0; index2 < num_methods; ++index2) {
1255 methodHandle m(THREAD, methodOop(methods->obj_at(index2)));
1256 m()->link_method(m, CHECK_(nh));
1257 }
1258 if (JvmtiExport::has_redefined_a_class()) {
1259 // Reinitialize vtable because RedefineClasses may have changed some
1260 // entries in this vtable for super classes so the CDS vtable might
1261 // point to old or obsolete entries. RedefineClasses doesn't fix up
1262 // vtables in the shared system dictionary, only the main one.
1263 // It also redefines the itable too so fix that too.
1264 ResourceMark rm(THREAD);
1265 ik->vtable()->initialize_vtable(false, CHECK_(nh));
1266 ik->itable()->initialize_itable(false, CHECK_(nh));
1267 }
1268 }
1269
1270 if (TraceClassLoading) {
1271 ResourceMark rm;
1272 tty->print("[Loaded %s", ik->external_name());
1273 tty->print(" from shared objects file");
1274 tty->print_cr("]");
1275 }
1276 // notify a class loaded from shared object
1277 ClassLoadingService::notify_class_loaded(instanceKlass::cast(ik()),
1278 true /* shared class */);
1279 }
1280 return ik;
1281 }
1282
1283 #ifdef KERNEL
1284 // Some classes on the bootstrap class path haven't been installed on the
1285 // system yet. Call the DownloadManager method to make them appear in the
1286 // bootstrap class path and try again to load the named class.
1287 // Note that with delegation class loaders all classes in another loader will
1288 // first try to call this so it'd better be fast!!
1289 static instanceKlassHandle download_and_retry_class_load(
1290 Symbol* class_name,
1291 TRAPS) {
1292
1293 klassOop dlm = SystemDictionary::sun_jkernel_DownloadManager_klass();
1294 instanceKlassHandle nk;
1295
1296 // If download manager class isn't loaded just return.
1297 if (dlm == NULL) return nk;
1298
1299 { HandleMark hm(THREAD);
1300 ResourceMark rm(THREAD);
1301 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nk));
1302 Handle class_string = java_lang_String::externalize_classname(s, CHECK_(nk));
1303
1304 // return value
1305 JavaValue result(T_OBJECT);
1306
1307 // Call the DownloadManager. We assume that it has a lock because
1308 // multiple classes could be not found and downloaded at the same time.
1309 // class sun.misc.DownloadManager;
1310 // public static String getBootClassPathEntryForClass(String className);
1311 JavaCalls::call_static(&result,
1312 KlassHandle(THREAD, dlm),
1313 vmSymbols::getBootClassPathEntryForClass_name(),
1314 vmSymbols::string_string_signature(),
1315 class_string,
1316 CHECK_(nk));
1317
1318 // Get result.string and add to bootclasspath
1319 assert(result.get_type() == T_OBJECT, "just checking");
1320 oop obj = (oop) result.get_jobject();
1321 if (obj == NULL) { return nk; }
1322
1323 Handle h_obj(THREAD, obj);
1324 char* new_class_name = java_lang_String::as_platform_dependent_str(h_obj,
1325 CHECK_(nk));
1326
1327 // lock the loader
1328 // we use this lock because JVMTI does.
1329 Handle loader_lock(THREAD, SystemDictionary::system_loader_lock());
1330
1331 ObjectLocker ol(loader_lock, THREAD);
1332 // add the file to the bootclasspath
1333 ClassLoader::update_class_path_entry_list(new_class_name, true);
1334 } // end HandleMark
1335
1336 if (TraceClassLoading) {
1337 ClassLoader::print_bootclasspath();
1338 }
1339 return ClassLoader::load_classfile(class_name, CHECK_(nk));
1340 }
1341 #endif // KERNEL
1342
1343
1344 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1345 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1346 if (class_loader.is_null()) {
1347
1348 // Search the shared system dictionary for classes preloaded into the
1349 // shared spaces.
1350 instanceKlassHandle k;
1351 {
1352 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1353 k = load_shared_class(class_name, class_loader, THREAD);
1354 }
1355
1356 if (k.is_null()) {
1357 // Use VM class loader
1358 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1359 k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1360 }
1361
1362 #ifdef KERNEL
1363 // If the VM class loader has failed to load the class, call the
1364 // DownloadManager class to make it magically appear on the classpath
1365 // and try again. This is only configured with the Kernel VM.
1366 if (k.is_null()) {
1367 k = download_and_retry_class_load(class_name, CHECK_(nh));
1368 }
1369 #endif // KERNEL
1370
1371 // find_or_define_instance_class may return a different instanceKlass
1372 if (!k.is_null()) {
1373 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1374 }
1375 return k;
1376 } else {
1377 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1378 ResourceMark rm(THREAD);
1379
1380 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1381 JavaThread* jt = (JavaThread*) THREAD;
1382
1383 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1384 ClassLoader::perf_app_classload_selftime(),
1385 ClassLoader::perf_app_classload_count(),
1386 jt->get_thread_stat()->perf_recursion_counts_addr(),
1387 jt->get_thread_stat()->perf_timers_addr(),
1388 PerfClassTraceTime::CLASS_LOAD);
1389
1390 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1391 // Translate to external class name format, i.e., convert '/' chars to '.'
1392 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1393
1394 JavaValue result(T_OBJECT);
1395
1396 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1397
1398 // Call public unsynchronized loadClass(String) directly for all class loaders
1399 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1400 // acquire a class-name based lock rather than the class loader object lock.
1401 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1402 // so the call to loadClassInternal() was not required.
1403 //
1404 // UnsyncloadClass flag means both call loadClass(String) and do
1405 // not acquire the class loader lock even for class loaders that are
1406 // not parallelCapable. This was a risky transitional
1407 // flag for diagnostic purposes only. It is risky to call
1408 // custom class loaders without synchronization.
1409 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1410 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1411 // Do NOT assume this will be supported in future releases.
1412 //
1413 // Added MustCallLoadClassInternal in case we discover in the field
1414 // a customer that counts on this call
1415 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1416 JavaCalls::call_special(&result,
1417 class_loader,
1418 spec_klass,
1419 vmSymbols::loadClassInternal_name(),
1420 vmSymbols::string_class_signature(),
1421 string,
1422 CHECK_(nh));
1423 } else {
1424 JavaCalls::call_virtual(&result,
1425 class_loader,
1426 spec_klass,
1427 vmSymbols::loadClass_name(),
1428 vmSymbols::string_class_signature(),
1429 string,
1430 CHECK_(nh));
1431 }
1432
1433 assert(result.get_type() == T_OBJECT, "just checking");
1434 oop obj = (oop) result.get_jobject();
1435
1436 // Primitive classes return null since forName() can not be
1437 // used to obtain any of the Class objects representing primitives or void
1438 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1439 instanceKlassHandle k =
1440 instanceKlassHandle(THREAD, java_lang_Class::as_klassOop(obj));
1441 // For user defined Java class loaders, check that the name returned is
1442 // the same as that requested. This check is done for the bootstrap
1443 // loader when parsing the class file.
1444 if (class_name == k->name()) {
1445 return k;
1446 }
1447 }
1448 // Class is not found or has the wrong name, return NULL
1449 return nh;
1450 }
1451 }
1452
1453 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1454
1455 Handle class_loader_h(THREAD, k->class_loader());
1456
1457 // for bootstrap and other parallel classloaders don't acquire lock,
1458 // use placeholder token
1459 // If a parallelCapable class loader calls define_instance_class instead of
1460 // find_or_define_instance_class to get here, we have a timing
1461 // hole with systemDictionary updates and check_constraints
1462 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1463 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1464 compute_loader_lock_object(class_loader_h, THREAD)),
1465 "define called without lock");
1466 }
1467
1468 // Check class-loading constraints. Throw exception if violation is detected.
1469 // Grabs and releases SystemDictionary_lock
1470 // The check_constraints/find_class call and update_dictionary sequence
1471 // must be "atomic" for a specific class/classloader pair so we never
1472 // define two different instanceKlasses for that class/classloader pair.
1473 // Existing classloaders will call define_instance_class with the
1474 // classloader lock held
1475 // Parallel classloaders will call find_or_define_instance_class
1476 // which will require a token to perform the define class
1477 Symbol* name_h = k->name();
1478 unsigned int d_hash = dictionary()->compute_hash(name_h, class_loader_h);
1479 int d_index = dictionary()->hash_to_index(d_hash);
1480 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1481
1482 // Register class just loaded with class loader (placed in Vector)
1483 // Note we do this before updating the dictionary, as this can
1484 // fail with an OutOfMemoryError (if it does, we will *not* put this
1485 // class in the dictionary and will not update the class hierarchy).
1486 if (k->class_loader() != NULL) {
1487 methodHandle m(THREAD, Universe::loader_addClass_method());
1488 JavaValue result(T_VOID);
1489 JavaCallArguments args(class_loader_h);
1490 args.push_oop(Handle(THREAD, k->java_mirror()));
1491 JavaCalls::call(&result, m, &args, CHECK);
1492 }
1493
1494 // Add the new class. We need recompile lock during update of CHA.
1495 {
1496 unsigned int p_hash = placeholders()->compute_hash(name_h, class_loader_h);
1497 int p_index = placeholders()->hash_to_index(p_hash);
1498
1499 MutexLocker mu_r(Compile_lock, THREAD);
1500
1501 // Add to class hierarchy, initialize vtables, and do possible
1502 // deoptimizations.
1503 add_to_hierarchy(k, CHECK); // No exception, but can block
1504
1505 // Add to systemDictionary - so other classes can see it.
1506 // Grabs and releases SystemDictionary_lock
1507 update_dictionary(d_index, d_hash, p_index, p_hash,
1508 k, class_loader_h, THREAD);
1509 }
1510 k->eager_initialize(THREAD);
1511
1512 // notify jvmti
1513 if (JvmtiExport::should_post_class_load()) {
1514 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1515 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1516
1517 }
1518 }
1519
1520 // Support parallel classloading
1521 // All parallel class loaders, including bootstrap classloader
1522 // lock a placeholder entry for this class/class_loader pair
1523 // to allow parallel defines of different classes for this class loader
1524 // With AllowParallelDefine flag==true, in case they do not synchronize around
1525 // FindLoadedClass/DefineClass, calls, we check for parallel
1526 // loading for them, wait if a defineClass is in progress
1527 // and return the initial requestor's results
1528 // This flag does not apply to the bootstrap classloader.
1529 // With AllowParallelDefine flag==false, call through to define_instance_class
1530 // which will throw LinkageError: duplicate class definition.
1531 // False is the requested default.
1532 // For better performance, the class loaders should synchronize
1533 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1534 // potentially waste time reading and parsing the bytestream.
1535 // Note: VM callers should ensure consistency of k/class_name,class_loader
1536 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1537
1538 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1539 Symbol* name_h = k->name(); // passed in class_name may be null
1540
1541 unsigned int d_hash = dictionary()->compute_hash(name_h, class_loader);
1542 int d_index = dictionary()->hash_to_index(d_hash);
1543
1544 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1545 unsigned int p_hash = placeholders()->compute_hash(name_h, class_loader);
1546 int p_index = placeholders()->hash_to_index(p_hash);
1547 PlaceholderEntry* probe;
1548
1549 {
1550 MutexLocker mu(SystemDictionary_lock, THREAD);
1551 // First check if class already defined
1552 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1553 klassOop check = find_class(d_index, d_hash, name_h, class_loader);
1554 if (check != NULL) {
1555 return(instanceKlassHandle(THREAD, check));
1556 }
1557 }
1558
1559 // Acquire define token for this class/classloader
1560 probe = placeholders()->find_and_add(p_index, p_hash, name_h, class_loader, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1561 // Wait if another thread defining in parallel
1562 // All threads wait - even those that will throw duplicate class: otherwise
1563 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1564 // if other thread has not finished updating dictionary
1565 while (probe->definer() != NULL) {
1566 SystemDictionary_lock->wait();
1567 }
1568 // Only special cases allow parallel defines and can use other thread's results
1569 // Other cases fall through, and may run into duplicate defines
1570 // caught by finding an entry in the SystemDictionary
1571 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instanceKlass() != NULL)) {
1572 probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);
1573 placeholders()->find_and_remove(p_index, p_hash, name_h, class_loader, THREAD);
1574 SystemDictionary_lock->notify_all();
1575 #ifdef ASSERT
1576 klassOop check = find_class(d_index, d_hash, name_h, class_loader);
1577 assert(check != NULL, "definer missed recording success");
1578 #endif
1579 return(instanceKlassHandle(THREAD, probe->instanceKlass()));
1580 } else {
1581 // This thread will define the class (even if earlier thread tried and had an error)
1582 probe->set_definer(THREAD);
1583 }
1584 }
1585
1586 define_instance_class(k, THREAD);
1587
1588 Handle linkage_exception = Handle(); // null handle
1589
1590 // definer must notify any waiting threads
1591 {
1592 MutexLocker mu(SystemDictionary_lock, THREAD);
1593 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, class_loader);
1594 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1595 if (probe != NULL) {
1596 if (HAS_PENDING_EXCEPTION) {
1597 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1598 CLEAR_PENDING_EXCEPTION;
1599 } else {
1600 probe->set_instanceKlass(k());
1601 }
1602 probe->set_definer(NULL);
1603 probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);
1604 placeholders()->find_and_remove(p_index, p_hash, name_h, class_loader, THREAD);
1605 SystemDictionary_lock->notify_all();
1606 }
1607 }
1608
1609 // Can't throw exception while holding lock due to rank ordering
1610 if (linkage_exception() != NULL) {
1611 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1612 }
1613
1614 return k;
1615 }
1616 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1617 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1618 if (class_loader.is_null()) {
1619 return Handle(THREAD, _system_loader_lock_obj);
1620 } else {
1621 return class_loader;
1622 }
1623 }
1624
1625 // This method is added to check how often we have to wait to grab loader
1626 // lock. The results are being recorded in the performance counters defined in
1627 // ClassLoader::_sync_systemLoaderLockContentionRate and
1628 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1629 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1630 if (!UsePerfData) {
1631 return;
1632 }
1633
1634 assert(!loader_lock.is_null(), "NULL lock object");
1635
1636 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1637 == ObjectSynchronizer::owner_other) {
1638 // contention will likely happen, so increment the corresponding
1639 // contention counter.
1640 if (loader_lock() == _system_loader_lock_obj) {
1641 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1642 } else {
1643 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1644 }
1645 }
1646 }
1647
1648 // ----------------------------------------------------------------------------
1649 // Lookup
1650
1651 klassOop SystemDictionary::find_class(int index, unsigned int hash,
1652 Symbol* class_name,
1653 Handle class_loader) {
1654 assert_locked_or_safepoint(SystemDictionary_lock);
1655 assert (index == dictionary()->index_for(class_name, class_loader),
1656 "incorrect index?");
1657
1658 klassOop k = dictionary()->find_class(index, hash, class_name, class_loader);
1659 return k;
1660 }
1661
1662
1663 // Basic find on classes in the midst of being loaded
1664 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1665 Handle class_loader) {
1666 assert_locked_or_safepoint(SystemDictionary_lock);
1667 unsigned int p_hash = placeholders()->compute_hash(class_name, class_loader);
1668 int p_index = placeholders()->hash_to_index(p_hash);
1669 return placeholders()->find_entry(p_index, p_hash, class_name, class_loader);
1670 }
1671
1672
1673 // Used for assertions and verification only
1674 klassOop SystemDictionary::find_class(Symbol* class_name, Handle class_loader) {
1675 #ifndef ASSERT
1676 guarantee(VerifyBeforeGC ||
1677 VerifyDuringGC ||
1678 VerifyBeforeExit ||
1679 VerifyAfterGC, "too expensive");
1680 #endif
1681 assert_locked_or_safepoint(SystemDictionary_lock);
1682
1683 // First look in the loaded class array
1684 unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);
1685 int d_index = dictionary()->hash_to_index(d_hash);
1686 return find_class(d_index, d_hash, class_name, class_loader);
1687 }
1688
1689
1690 // Get the next class in the diictionary.
1691 klassOop SystemDictionary::try_get_next_class() {
1692 return dictionary()->try_get_next_class();
1693 }
1694
1695
1696 // ----------------------------------------------------------------------------
1697 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1698 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1699 // before a new class is used.
1700
1701 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1702 assert(k.not_null(), "just checking");
1703 assert_locked_or_safepoint(Compile_lock);
1704
1705 // Link into hierachy. Make sure the vtables are initialized before linking into
1706 k->append_to_sibling_list(); // add to superklass/sibling list
1707 k->process_interfaces(THREAD); // handle all "implements" declarations
1708 k->set_init_state(instanceKlass::loaded);
1709 // Now flush all code that depended on old class hierarchy.
1710 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1711 // Also, first reinitialize vtable because it may have gotten out of synch
1712 // while the new class wasn't connected to the class hierarchy.
1713 Universe::flush_dependents_on(k);
1714 }
1715
1716
1717 // ----------------------------------------------------------------------------
1718 // GC support
1719
1720 // Following roots during mark-sweep is separated in two phases.
1721 //
1722 // The first phase follows preloaded classes and all other system
1723 // classes, since these will never get unloaded anyway.
1724 //
1725 // The second phase removes (unloads) unreachable classes from the
1726 // system dictionary and follows the remaining classes' contents.
1727
1728 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1729 // Follow preloaded classes/mirrors and system loader object
1730 blk->do_oop(&_java_system_loader);
1731 preloaded_oops_do(blk);
1732 always_strong_classes_do(blk);
1733 }
1734
1735
1736 void SystemDictionary::always_strong_classes_do(OopClosure* blk) {
1737 // Follow all system classes and temporary placeholders in dictionary
1738 dictionary()->always_strong_classes_do(blk);
1739
1740 // Placeholders. These are *always* strong roots, as they
1741 // represent classes we're actively loading.
1742 placeholders_do(blk);
1743
1744 // Visit extra methods
1745 invoke_method_table()->oops_do(blk);
1746 }
1747
1748
1749 void SystemDictionary::placeholders_do(OopClosure* blk) {
1750 placeholders()->oops_do(blk);
1751 }
1752
1753
1754 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
1755 bool result = dictionary()->do_unloading(is_alive);
1756 constraints()->purge_loader_constraints(is_alive);
1757 resolution_errors()->purge_resolution_errors(is_alive);
1758 return result;
1759 }
1760
1761
1762 // The mirrors are scanned by shared_oops_do() which is
1763 // not called by oops_do(). In order to process oops in
1764 // a necessary order, shared_oops_do() is call by
1765 // Universe::oops_do().
1766 void SystemDictionary::oops_do(OopClosure* f) {
1767 // Adjust preloaded classes and system loader object
1768 f->do_oop(&_java_system_loader);
1769 preloaded_oops_do(f);
1770
1771 lazily_loaded_oops_do(f);
1772
1773 // Adjust dictionary
1774 dictionary()->oops_do(f);
1775
1776 // Visit extra methods
1777 invoke_method_table()->oops_do(f);
1778
1779 // Partially loaded classes
1780 placeholders()->oops_do(f);
1781
1782 // Adjust constraint table
1783 constraints()->oops_do(f);
1784
1785 // Adjust resolution error table
1786 resolution_errors()->oops_do(f);
1787 }
1788
1789
1790 void SystemDictionary::preloaded_oops_do(OopClosure* f) {
1791 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1792 f->do_oop((oop*) &_well_known_klasses[k]);
1793 }
1794
1795 {
1796 for (int i = 0; i < T_VOID+1; i++) {
1797 if (_box_klasses[i] != NULL) {
1798 assert(i >= T_BOOLEAN, "checking");
1799 f->do_oop((oop*) &_box_klasses[i]);
1800 }
1801 }
1802 }
1803
1804 // The basic type mirrors would have already been processed in
1805 // Universe::oops_do(), via a call to shared_oops_do(), so should
1806 // not be processed again.
1807
1808 f->do_oop((oop*) &_system_loader_lock_obj);
1809 FilteredFieldsMap::klasses_oops_do(f);
1810 }
1811
1812 void SystemDictionary::lazily_loaded_oops_do(OopClosure* f) {
1813 f->do_oop((oop*) &_abstract_ownable_synchronizer_klass);
1814 }
1815
1816 // Just the classes from defining class loaders
1817 // Don't iterate over placeholders
1818 void SystemDictionary::classes_do(void f(klassOop)) {
1819 dictionary()->classes_do(f);
1820 }
1821
1822 // Added for initialize_itable_for_klass
1823 // Just the classes from defining class loaders
1824 // Don't iterate over placeholders
1825 void SystemDictionary::classes_do(void f(klassOop, TRAPS), TRAPS) {
1826 dictionary()->classes_do(f, CHECK);
1827 }
1828
1829 // All classes, and their class loaders
1830 // Don't iterate over placeholders
1831 void SystemDictionary::classes_do(void f(klassOop, oop)) {
1832 dictionary()->classes_do(f);
1833 }
1834
1835 // All classes, and their class loaders
1836 // (added for helpers that use HandleMarks and ResourceMarks)
1837 // Don't iterate over placeholders
1838 void SystemDictionary::classes_do(void f(klassOop, oop, TRAPS), TRAPS) {
1839 dictionary()->classes_do(f, CHECK);
1840 }
1841
1842 void SystemDictionary::placeholders_do(void f(Symbol*, oop)) {
1843 placeholders()->entries_do(f);
1844 }
1845
1846 void SystemDictionary::methods_do(void f(methodOop)) {
1847 dictionary()->methods_do(f);
1848 invoke_method_table()->methods_do(f);
1849 }
1850
1851 // ----------------------------------------------------------------------------
1852 // Lazily load klasses
1853
1854 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1855 assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");
1856
1857 // if multiple threads calling this function, only one thread will load
1858 // the class. The other threads will find the loaded version once the
1859 // class is loaded.
1860 klassOop aos = _abstract_ownable_synchronizer_klass;
1861 if (aos == NULL) {
1862 klassOop k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1863 // Force a fence to prevent any read before the write completes
1864 OrderAccess::fence();
1865 _abstract_ownable_synchronizer_klass = k;
1866 }
1867 }
1868
1869 // ----------------------------------------------------------------------------
1870 // Initialization
1871
1872 void SystemDictionary::initialize(TRAPS) {
1873 // Allocate arrays
1874 assert(dictionary() == NULL,
1875 "SystemDictionary should only be initialized once");
1876 _dictionary = new Dictionary(_nof_buckets);
1877 _placeholders = new PlaceholderTable(_nof_buckets);
1878 _number_of_modifications = 0;
1879 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1880 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1881 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1882
1883 // Allocate private object used as system class loader lock
1884 _system_loader_lock_obj = oopFactory::new_system_objArray(0, CHECK);
1885 // Initialize basic classes
1886 initialize_preloaded_classes(CHECK);
1887 }
1888
1889 // Compact table of directions on the initialization of klasses:
1890 static const short wk_init_info[] = {
1891 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1892 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1893 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1894 | (int)SystemDictionary::option ),
1895 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1896 #undef WK_KLASS_INIT_INFO
1897 0
1898 };
1899
1900 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1901 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1902 int info = wk_init_info[id - FIRST_WKID];
1903 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1904 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1905 klassOop* klassp = &_well_known_klasses[id];
1906 bool must_load = (init_opt < SystemDictionary::Opt);
1907 bool try_load = true;
1908 if (init_opt == SystemDictionary::Opt_Kernel) {
1909 #ifndef KERNEL
1910 try_load = false;
1911 #endif //KERNEL
1912 }
1913 if ((*klassp) == NULL && try_load) {
1914 if (must_load) {
1915 (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class
1916 } else {
1917 (*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass
1918 }
1919 }
1920 return ((*klassp) != NULL);
1921 }
1922
1923 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1924 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1925 for (int id = (int)start_id; id < (int)limit_id; id++) {
1926 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1927 int info = wk_init_info[id - FIRST_WKID];
1928 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1929 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1930
1931 initialize_wk_klass((WKID)id, opt, CHECK);
1932
1933 // Update limits, so find_well_known_klass can be very fast:
1934 Symbol* s = vmSymbols::symbol_at((vmSymbols::SID)sid);
1935 if (wk_klass_name_limits[1] == NULL) {
1936 wk_klass_name_limits[0] = wk_klass_name_limits[1] = s;
1937 } else if (wk_klass_name_limits[1] < s) {
1938 wk_klass_name_limits[1] = s;
1939 } else if (wk_klass_name_limits[0] > s) {
1940 wk_klass_name_limits[0] = s;
1941 }
1942 }
1943
1944 // move the starting value forward to the limit:
1945 start_id = limit_id;
1946 }
1947
1948
1949 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1950 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1951 // Preload commonly used klasses
1952 WKID scan = FIRST_WKID;
1953 // first do Object, String, Class
1954 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1955
1956 debug_only(instanceKlass::verify_class_klass_nonstatic_oop_maps(WK_KLASS(Class_klass)));
1957
1958 // Fixup mirrors for classes loaded before java.lang.Class.
1959 // These calls iterate over the objects currently in the perm gen
1960 // so calling them at this point is matters (not before when there
1961 // are fewer objects and not later after there are more objects
1962 // in the perm gen.
1963 Universe::initialize_basic_type_mirrors(CHECK);
1964 Universe::fixup_mirrors(CHECK);
1965
1966 // do a bunch more:
1967 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1968
1969 // Preload ref klasses and set reference types
1970 instanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1971 instanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1972
1973 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
1974 instanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1975 instanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1976 instanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1977 instanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1978
1979 // JSR 292 classes
1980 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1981 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1982 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1983 if (EnableInvokeDynamic) {
1984 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1985 } else {
1986 // Skip the JSR 292 classes, if not enabled.
1987 scan = WKID(jsr292_group_end + 1);
1988 }
1989
1990 initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);
1991
1992 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1993 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
1994 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
1995 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
1996 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
1997 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
1998 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
1999 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
2000 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
2001 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
2002
2003 #ifdef KERNEL
2004 if (sun_jkernel_DownloadManager_klass() == NULL) {
2005 warning("Cannot find sun/jkernel/DownloadManager");
2006 }
2007 #endif // KERNEL
2008
2009 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
2010 methodOop method = instanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
2011 _has_loadClassInternal = (method != NULL);
2012 }
2013 { // Compute whether we should use checkPackageAccess or NOT
2014 methodOop method = instanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
2015 _has_checkPackageAccess = (method != NULL);
2016 }
2017 }
2018
2019 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2020 // If so, returns the basic type it holds. If not, returns T_OBJECT.
2021 BasicType SystemDictionary::box_klass_type(klassOop k) {
2022 assert(k != NULL, "");
2023 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2024 if (_box_klasses[i] == k)
2025 return (BasicType)i;
2026 }
2027 return T_OBJECT;
2028 }
2029
2030 KlassHandle SystemDictionaryHandles::box_klass(BasicType t) {
2031 if (t >= T_BOOLEAN && t <= T_VOID)
2032 return KlassHandle(&SystemDictionary::_box_klasses[t], true);
2033 else
2034 return KlassHandle();
2035 }
2036
2037 // Constraints on class loaders. The details of the algorithm can be
2038 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2039 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
2040 // that the system dictionary needs to maintain a set of contraints that
2041 // must be satisfied by all classes in the dictionary.
2042 // if defining is true, then LinkageError if already in systemDictionary
2043 // if initiating loader, then ok if instanceKlass matches existing entry
2044
2045 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
2046 instanceKlassHandle k,
2047 Handle class_loader, bool defining,
2048 TRAPS) {
2049 const char *linkage_error = NULL;
2050 {
2051 Symbol* name = k->name();
2052 MutexLocker mu(SystemDictionary_lock, THREAD);
2053
2054 klassOop check = find_class(d_index, d_hash, name, class_loader);
2055 if (check != (klassOop)NULL) {
2056 // if different instanceKlass - duplicate class definition,
2057 // else - ok, class loaded by a different thread in parallel,
2058 // we should only have found it if it was done loading and ok to use
2059 // system dictionary only holds instance classes, placeholders
2060 // also holds array classes
2061
2062 assert(check->klass_part()->oop_is_instance(), "noninstance in systemdictionary");
2063 if ((defining == true) || (k() != check)) {
2064 linkage_error = "loader (instance of %s): attempted duplicate class "
2065 "definition for name: \"%s\"";
2066 } else {
2067 return;
2068 }
2069 }
2070
2071 #ifdef ASSERT
2072 Symbol* ph_check = find_placeholder(name, class_loader);
2073 assert(ph_check == NULL || ph_check == name, "invalid symbol");
2074 #endif
2075
2076 if (linkage_error == NULL) {
2077 if (constraints()->check_or_update(k, class_loader, name) == false) {
2078 linkage_error = "loader constraint violation: loader (instance of %s)"
2079 " previously initiated loading for a different type with name \"%s\"";
2080 }
2081 }
2082 }
2083
2084 // Throw error now if needed (cannot throw while holding
2085 // SystemDictionary_lock because of rank ordering)
2086
2087 if (linkage_error) {
2088 ResourceMark rm(THREAD);
2089 const char* class_loader_name = loader_name(class_loader());
2090 char* type_name = k->name()->as_C_string();
2091 size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +
2092 strlen(type_name);
2093 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2094 jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);
2095 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2096 }
2097 }
2098
2099
2100 // Update system dictionary - done after check_constraint and add_to_hierachy
2101 // have been called.
2102 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2103 int p_index, unsigned int p_hash,
2104 instanceKlassHandle k,
2105 Handle class_loader,
2106 TRAPS) {
2107 // Compile_lock prevents systemDictionary updates during compilations
2108 assert_locked_or_safepoint(Compile_lock);
2109 Symbol* name = k->name();
2110
2111 {
2112 MutexLocker mu1(SystemDictionary_lock, THREAD);
2113
2114 // See whether biased locking is enabled and if so set it for this
2115 // klass.
2116 // Note that this must be done past the last potential blocking
2117 // point / safepoint. We enable biased locking lazily using a
2118 // VM_Operation to iterate the SystemDictionary and installing the
2119 // biasable mark word into each instanceKlass's prototype header.
2120 // To avoid race conditions where we accidentally miss enabling the
2121 // optimization for one class in the process of being added to the
2122 // dictionary, we must not safepoint after the test of
2123 // BiasedLocking::enabled().
2124 if (UseBiasedLocking && BiasedLocking::enabled()) {
2125 // Set biased locking bit for all loaded classes; it will be
2126 // cleared if revocation occurs too often for this type
2127 // NOTE that we must only do this when the class is initally
2128 // defined, not each time it is referenced from a new class loader
2129 if (k->class_loader() == class_loader()) {
2130 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2131 }
2132 }
2133
2134 // Check for a placeholder. If there, remove it and make a
2135 // new system dictionary entry.
2136 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
2137 klassOop sd_check = find_class(d_index, d_hash, name, class_loader);
2138 if (sd_check == NULL) {
2139 dictionary()->add_klass(name, class_loader, k);
2140 notice_modification();
2141 }
2142 #ifdef ASSERT
2143 sd_check = find_class(d_index, d_hash, name, class_loader);
2144 assert (sd_check != NULL, "should have entry in system dictionary");
2145 // Changed to allow PH to remain to complete class circularity checking
2146 // while only one thread can define a class at one time, multiple
2147 // classes can resolve the superclass for a class at one time,
2148 // and the placeholder is used to track that
2149 // Symbol* ph_check = find_placeholder(name, class_loader);
2150 // assert (ph_check == NULL, "should not have a placeholder entry");
2151 #endif
2152 SystemDictionary_lock->notify_all();
2153 }
2154 }
2155
2156
2157 // Try to find a class name using the loader constraints. The
2158 // loader constraints might know about a class that isn't fully loaded
2159 // yet and these will be ignored.
2160 klassOop SystemDictionary::find_constrained_instance_or_array_klass(
2161 Symbol* class_name, Handle class_loader, TRAPS) {
2162
2163 // First see if it has been loaded directly.
2164 // Force the protection domain to be null. (This removes protection checks.)
2165 Handle no_protection_domain;
2166 klassOop klass = find_instance_or_array_klass(class_name, class_loader,
2167 no_protection_domain, CHECK_NULL);
2168 if (klass != NULL)
2169 return klass;
2170
2171 // Now look to see if it has been loaded elsewhere, and is subject to
2172 // a loader constraint that would require this loader to return the
2173 // klass that is already loaded.
2174 if (FieldType::is_array(class_name)) {
2175 // For array classes, their klassOops are not kept in the
2176 // constraint table. The element klassOops are.
2177 FieldArrayInfo fd;
2178 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2179 if (t != T_OBJECT) {
2180 klass = Universe::typeArrayKlassObj(t);
2181 } else {
2182 MutexLocker mu(SystemDictionary_lock, THREAD);
2183 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2184 }
2185 // If element class already loaded, allocate array klass
2186 if (klass != NULL) {
2187 klass = Klass::cast(klass)->array_klass_or_null(fd.dimension());
2188 }
2189 } else {
2190 MutexLocker mu(SystemDictionary_lock, THREAD);
2191 // Non-array classes are easy: simply check the constraint table.
2192 klass = constraints()->find_constrained_klass(class_name, class_loader);
2193 }
2194
2195 return klass;
2196 }
2197
2198
2199 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2200 Handle class_loader1,
2201 Handle class_loader2,
2202 Thread* THREAD) {
2203 Symbol* constraint_name = NULL;
2204 if (!FieldType::is_array(class_name)) {
2205 constraint_name = class_name;
2206 } else {
2207 // For array classes, their klassOops are not kept in the
2208 // constraint table. The element classes are.
2209 FieldArrayInfo fd;
2210 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2211 // primitive types always pass
2212 if (t != T_OBJECT) {
2213 return true;
2214 } else {
2215 constraint_name = fd.object_key();
2216 }
2217 }
2218 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, class_loader1);
2219 int d_index1 = dictionary()->hash_to_index(d_hash1);
2220
2221 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, class_loader2);
2222 int d_index2 = dictionary()->hash_to_index(d_hash2);
2223 {
2224 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2225
2226 // Better never do a GC while we're holding these oops
2227 No_Safepoint_Verifier nosafepoint;
2228
2229 klassOop klass1 = find_class(d_index1, d_hash1, constraint_name, class_loader1);
2230 klassOop klass2 = find_class(d_index2, d_hash2, constraint_name, class_loader2);
2231 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2232 klass2, class_loader2);
2233 }
2234 }
2235
2236 // Add entry to resolution error table to record the error when the first
2237 // attempt to resolve a reference to a class has failed.
2238 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) {
2239 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2240 int index = resolution_errors()->hash_to_index(hash);
2241 {
2242 MutexLocker ml(SystemDictionary_lock, Thread::current());
2243 resolution_errors()->add_entry(index, hash, pool, which, error);
2244 }
2245 }
2246
2247 // Lookup resolution error table. Returns error if found, otherwise NULL.
2248 Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {
2249 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2250 int index = resolution_errors()->hash_to_index(hash);
2251 {
2252 MutexLocker ml(SystemDictionary_lock, Thread::current());
2253 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2254 return (entry != NULL) ? entry->error() : (Symbol*)NULL;
2255 }
2256 }
2257
2258
2259 // Signature constraints ensure that callers and callees agree about
2260 // the meaning of type names in their signatures. This routine is the
2261 // intake for constraints. It collects them from several places:
2262 //
2263 // * LinkResolver::resolve_method (if check_access is true) requires
2264 // that the resolving class (the caller) and the defining class of
2265 // the resolved method (the callee) agree on each type in the
2266 // method's signature.
2267 //
2268 // * LinkResolver::resolve_interface_method performs exactly the same
2269 // checks.
2270 //
2271 // * LinkResolver::resolve_field requires that the constant pool
2272 // attempting to link to a field agree with the field's defining
2273 // class about the type of the field signature.
2274 //
2275 // * klassVtable::initialize_vtable requires that, when a class
2276 // overrides a vtable entry allocated by a superclass, that the
2277 // overriding method (i.e., the callee) agree with the superclass
2278 // on each type in the method's signature.
2279 //
2280 // * klassItable::initialize_itable requires that, when a class fills
2281 // in its itables, for each non-abstract method installed in an
2282 // itable, the method (i.e., the callee) agree with the interface
2283 // on each type in the method's signature.
2284 //
2285 // All those methods have a boolean (check_access, checkconstraints)
2286 // which turns off the checks. This is used from specialized contexts
2287 // such as bootstrapping, dumping, and debugging.
2288 //
2289 // No direct constraint is placed between the class and its
2290 // supertypes. Constraints are only placed along linked relations
2291 // between callers and callees. When a method overrides or implements
2292 // an abstract method in a supertype (superclass or interface), the
2293 // constraints are placed as if the supertype were the caller to the
2294 // overriding method. (This works well, since callers to the
2295 // supertype have already established agreement between themselves and
2296 // the supertype.) As a result of all this, a class can disagree with
2297 // its supertype about the meaning of a type name, as long as that
2298 // class neither calls a relevant method of the supertype, nor is
2299 // called (perhaps via an override) from the supertype.
2300 //
2301 //
2302 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2303 //
2304 // Make sure all class components (including arrays) in the given
2305 // signature will be resolved to the same class in both loaders.
2306 // Returns the name of the type that failed a loader constraint check, or
2307 // NULL if no constraint failed. The returned C string needs cleaning up
2308 // with a ResourceMark in the caller. No exception except OOME is thrown.
2309 // Arrays are not added to the loader constraint table, their elements are.
2310 char* SystemDictionary::check_signature_loaders(Symbol* signature,
2311 Handle loader1, Handle loader2,
2312 bool is_method, TRAPS) {
2313 // Nothing to do if loaders are the same.
2314 if (loader1() == loader2()) {
2315 return NULL;
2316 }
2317
2318 ResourceMark rm(THREAD);
2319 SignatureStream sig_strm(signature, is_method);
2320 while (!sig_strm.is_done()) {
2321 if (sig_strm.is_object()) {
2322 Symbol* s = sig_strm.as_symbol(CHECK_NULL);
2323 Symbol* sig = s;
2324 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2325 return sig->as_C_string();
2326 }
2327 }
2328 sig_strm.next();
2329 }
2330 return NULL;
2331 }
2332
2333
2334 methodOop SystemDictionary::find_method_handle_invoke(Symbol* name,
2335 Symbol* signature,
2336 KlassHandle accessing_klass,
2337 TRAPS) {
2338 if (!EnableInvokeDynamic) return NULL;
2339 vmSymbols::SID name_id = vmSymbols::find_sid(name);
2340 assert(name_id != vmSymbols::NO_SID, "must be a known name");
2341 unsigned int hash = invoke_method_table()->compute_hash(signature, name_id);
2342 int index = invoke_method_table()->hash_to_index(hash);
2343 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, name_id);
2344 methodHandle non_cached_result;
2345 if (spe == NULL || spe->property_oop() == NULL) {
2346 spe = NULL;
2347 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2348 if (THREAD->is_Compiler_thread())
2349 return NULL; // do not attempt from within compiler
2350 bool for_invokeGeneric = (name_id != vmSymbols::VM_SYMBOL_ENUM_NAME(invokeExact_name));
2351 bool found_on_bcp = false;
2352 Handle mt = find_method_handle_type(signature, accessing_klass,
2353 for_invokeGeneric,
2354 found_on_bcp, CHECK_NULL);
2355 KlassHandle mh_klass = SystemDictionaryHandles::MethodHandle_klass();
2356 methodHandle m = methodOopDesc::make_invoke_method(mh_klass, name, signature,
2357 mt, CHECK_NULL);
2358 // Now grab the lock. We might have to throw away the new method,
2359 // if a racing thread has managed to install one at the same time.
2360 if (found_on_bcp) {
2361 MutexLocker ml(SystemDictionary_lock, Thread::current());
2362 spe = invoke_method_table()->find_entry(index, hash, signature, name_id);
2363 if (spe == NULL)
2364 spe = invoke_method_table()->add_entry(index, hash, signature, name_id);
2365 if (spe->property_oop() == NULL) {
2366 spe->set_property_oop(m());
2367 // Link m to his method type, if it is suitably generic.
2368 oop mtform = java_lang_invoke_MethodType::form(mt());
2369 if (mtform != NULL && mt() == java_lang_invoke_MethodTypeForm::erasedType(mtform)
2370 // vmlayout must be an invokeExact:
2371 && name_id == vmSymbols::VM_SYMBOL_ENUM_NAME(invokeExact_name)
2372 && java_lang_invoke_MethodTypeForm::vmlayout_offset_in_bytes() > 0) {
2373 java_lang_invoke_MethodTypeForm::init_vmlayout(mtform, m());
2374 }
2375 }
2376 } else {
2377 non_cached_result = m;
2378 }
2379 }
2380 if (spe != NULL && spe->property_oop() != NULL) {
2381 assert(spe->property_oop()->is_method(), "");
2382 return (methodOop) spe->property_oop();
2383 } else {
2384 return non_cached_result();
2385 }
2386 }
2387
2388 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2389 // signature, as interpreted relative to the given class loader.
2390 // Because of class loader constraints, all method handle usage must be
2391 // consistent with this loader.
2392 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2393 KlassHandle accessing_klass,
2394 bool for_invokeGeneric,
2395 bool& return_bcp_flag,
2396 TRAPS) {
2397 Handle class_loader, protection_domain;
2398 bool is_on_bcp = true; // keep this true as long as we can materialize from the boot classloader
2399 Handle empty;
2400 int npts = ArgumentCount(signature).size();
2401 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2402 int arg = 0;
2403 Handle rt; // the return type from the signature
2404 ResourceMark rm(THREAD);
2405 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2406 oop mirror = NULL;
2407 if (is_on_bcp) {
2408 mirror = ss.as_java_mirror(class_loader, protection_domain,
2409 SignatureStream::ReturnNull, CHECK_(empty));
2410 if (mirror == NULL) {
2411 // fall back from BCP to accessing_klass
2412 if (accessing_klass.not_null()) {
2413 class_loader = Handle(THREAD, instanceKlass::cast(accessing_klass())->class_loader());
2414 protection_domain = Handle(THREAD, instanceKlass::cast(accessing_klass())->protection_domain());
2415 }
2416 is_on_bcp = false;
2417 }
2418 }
2419 if (!is_on_bcp) {
2420 // Resolve, throwing a real error if it doesn't work.
2421 mirror = ss.as_java_mirror(class_loader, protection_domain,
2422 SignatureStream::NCDFError, CHECK_(empty));
2423 }
2424 if (ss.at_return_type())
2425 rt = Handle(THREAD, mirror);
2426 else
2427 pts->obj_at_put(arg++, mirror);
2428 // Check accessibility.
2429 if (ss.is_object() && accessing_klass.not_null()) {
2430 klassOop sel_klass = java_lang_Class::as_klassOop(mirror);
2431 // Emulate constantPoolOopDesc::verify_constant_pool_resolve.
2432 if (Klass::cast(sel_klass)->oop_is_objArray())
2433 sel_klass = objArrayKlass::cast(sel_klass)->bottom_klass();
2434 if (Klass::cast(sel_klass)->oop_is_instance()) {
2435 KlassHandle sel_kh(THREAD, sel_klass);
2436 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2437 }
2438 }
2439 }
2440 assert(arg == npts, "");
2441
2442 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2443 JavaCallArguments args(Handle(THREAD, rt()));
2444 args.push_oop(pts());
2445 JavaValue result(T_OBJECT);
2446 JavaCalls::call_static(&result,
2447 SystemDictionary::MethodHandleNatives_klass(),
2448 vmSymbols::findMethodHandleType_name(),
2449 vmSymbols::findMethodHandleType_signature(),
2450 &args, CHECK_(empty));
2451 Handle method_type(THREAD, (oop) result.get_jobject());
2452
2453 if (for_invokeGeneric) {
2454 // call java.lang.invoke.MethodHandleNatives::notifyGenericMethodType(MethodType) -> void
2455 JavaCallArguments args(Handle(THREAD, method_type()));
2456 JavaValue no_result(T_VOID);
2457 JavaCalls::call_static(&no_result,
2458 SystemDictionary::MethodHandleNatives_klass(),
2459 vmSymbols::notifyGenericMethodType_name(),
2460 vmSymbols::notifyGenericMethodType_signature(),
2461 &args, THREAD);
2462 if (HAS_PENDING_EXCEPTION) {
2463 // If the notification fails, just kill it.
2464 CLEAR_PENDING_EXCEPTION;
2465 }
2466 }
2467
2468 // report back to the caller with the MethodType and the "on_bcp" flag
2469 return_bcp_flag = is_on_bcp;
2470 return method_type;
2471 }
2472
2473 // Ask Java code to find or construct a method handle constant.
2474 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2475 int ref_kind, //e.g., JVM_REF_invokeVirtual
2476 KlassHandle callee,
2477 Symbol* name_sym,
2478 Symbol* signature,
2479 TRAPS) {
2480 Handle empty;
2481 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2482 Handle type;
2483 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2484 bool ignore_is_on_bcp = false;
2485 type = find_method_handle_type(signature, caller, false, ignore_is_on_bcp, CHECK_(empty));
2486 } else {
2487 ResourceMark rm(THREAD);
2488 SignatureStream ss(signature, false);
2489 if (!ss.is_done()) {
2490 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2491 SignatureStream::NCDFError, CHECK_(empty));
2492 type = Handle(THREAD, mirror);
2493 ss.next();
2494 if (!ss.is_done()) type = Handle(); // error!
2495 }
2496 }
2497 if (type.is_null()) {
2498 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2499 }
2500
2501 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2502 JavaCallArguments args;
2503 args.push_oop(caller->java_mirror()); // the referring class
2504 args.push_int(ref_kind);
2505 args.push_oop(callee->java_mirror()); // the target class
2506 args.push_oop(name());
2507 args.push_oop(type());
2508 JavaValue result(T_OBJECT);
2509 JavaCalls::call_static(&result,
2510 SystemDictionary::MethodHandleNatives_klass(),
2511 vmSymbols::linkMethodHandleConstant_name(),
2512 vmSymbols::linkMethodHandleConstant_signature(),
2513 &args, CHECK_(empty));
2514 return Handle(THREAD, (oop) result.get_jobject());
2515 }
2516
2517 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2518 // name and signature, as interpreted relative to the given class loader.
2519 Handle SystemDictionary::make_dynamic_call_site(Handle bootstrap_method,
2520 Symbol* name,
2521 methodHandle signature_invoker,
2522 Handle info,
2523 methodHandle caller_method,
2524 int caller_bci,
2525 TRAPS) {
2526 Handle empty;
2527 guarantee(bootstrap_method.not_null() &&
2528 java_lang_invoke_MethodHandle::is_instance(bootstrap_method()),
2529 "caller must supply a valid BSM");
2530
2531 Handle caller_mname = MethodHandles::new_MemberName(CHECK_(empty));
2532 MethodHandles::init_MemberName(caller_mname(), caller_method());
2533
2534 // call java.lang.invoke.MethodHandleNatives::makeDynamicCallSite(bootm, name, mtype, info, caller_mname, caller_pos)
2535 oop name_str_oop = StringTable::intern(name, CHECK_(empty)); // not a handle!
2536 JavaCallArguments args(Handle(THREAD, bootstrap_method()));
2537 args.push_oop(name_str_oop);
2538 args.push_oop(signature_invoker->method_handle_type());
2539 args.push_oop(info());
2540 args.push_oop(caller_mname());
2541 args.push_int(caller_bci);
2542 JavaValue result(T_OBJECT);
2543 JavaCalls::call_static(&result,
2544 SystemDictionary::MethodHandleNatives_klass(),
2545 vmSymbols::makeDynamicCallSite_name(),
2546 vmSymbols::makeDynamicCallSite_signature(),
2547 &args, CHECK_(empty));
2548 oop call_site_oop = (oop) result.get_jobject();
2549 assert(call_site_oop->is_oop()
2550 /*&& java_lang_invoke_CallSite::is_instance(call_site_oop)*/, "must be sane");
2551 if (TraceMethodHandles) {
2552 #ifndef PRODUCT
2553 tty->print_cr("Linked invokedynamic bci=%d site="INTPTR_FORMAT":", caller_bci, call_site_oop);
2554 call_site_oop->print();
2555 tty->cr();
2556 #endif //PRODUCT
2557 }
2558 return call_site_oop;
2559 }
2560
2561 Handle SystemDictionary::find_bootstrap_method(methodHandle caller_method, int caller_bci,
2562 int cache_index,
2563 Handle& argument_info_result,
2564 TRAPS) {
2565 Handle empty;
2566
2567 constantPoolHandle pool;
2568 {
2569 klassOop caller = caller_method->method_holder();
2570 if (!Klass::cast(caller)->oop_is_instance()) return empty;
2571 pool = constantPoolHandle(THREAD, instanceKlass::cast(caller)->constants());
2572 }
2573
2574 int constant_pool_index = pool->cache()->entry_at(cache_index)->constant_pool_index();
2575 constantTag tag = pool->tag_at(constant_pool_index);
2576
2577 if (tag.is_invoke_dynamic()) {
2578 // JVM_CONSTANT_InvokeDynamic is an ordered pair of [bootm, name&type], plus optional arguments
2579 // The bootm, being a JVM_CONSTANT_MethodHandle, has its own cache entry.
2580 int bsm_index = pool->invoke_dynamic_bootstrap_method_ref_index_at(constant_pool_index);
2581 if (bsm_index != 0) {
2582 int bsm_index_in_cache = pool->cache()->entry_at(cache_index)->bootstrap_method_index_in_cache();
2583 DEBUG_ONLY(int bsm_index_2 = pool->cache()->entry_at(bsm_index_in_cache)->constant_pool_index());
2584 assert(bsm_index == bsm_index_2, "BSM constant lifted to cache");
2585 if (TraceMethodHandles) {
2586 tty->print_cr("resolving bootstrap method for "PTR_FORMAT" at %d at cache[%d]CP[%d]...",
2587 (intptr_t) caller_method(), caller_bci, cache_index, constant_pool_index);
2588 }
2589 oop bsm_oop = pool->resolve_cached_constant_at(bsm_index_in_cache, CHECK_(empty));
2590 if (TraceMethodHandles) {
2591 tty->print_cr("bootstrap method for "PTR_FORMAT" at %d retrieved as "PTR_FORMAT":",
2592 (intptr_t) caller_method(), caller_bci, (intptr_t) bsm_oop);
2593 }
2594 assert(bsm_oop->is_oop(), "must be sane");
2595 // caller must verify that it is of type MethodHandle
2596 Handle bsm(THREAD, bsm_oop);
2597 bsm_oop = NULL; // safety
2598
2599 // Extract the optional static arguments.
2600 Handle argument_info; // either null, or one arg, or Object[]{arg...}
2601 int argc = pool->invoke_dynamic_argument_count_at(constant_pool_index);
2602 if (TraceInvokeDynamic) {
2603 tty->print_cr("find_bootstrap_method: [%d/%d] CONSTANT_InvokeDynamic: %d[%d]",
2604 constant_pool_index, cache_index, bsm_index, argc);
2605 }
2606 if (argc > 0) {
2607 objArrayHandle arg_array;
2608 if (argc > 1) {
2609 objArrayOop arg_array_oop = oopFactory::new_objArray(SystemDictionary::Object_klass(), argc, CHECK_(empty));
2610 arg_array = objArrayHandle(THREAD, arg_array_oop);
2611 argument_info = arg_array;
2612 }
2613 for (int arg_i = 0; arg_i < argc; arg_i++) {
2614 int arg_index = pool->invoke_dynamic_argument_index_at(constant_pool_index, arg_i);
2615 oop arg_oop = pool->resolve_possibly_cached_constant_at(arg_index, CHECK_(empty));
2616 if (arg_array.is_null()) {
2617 argument_info = Handle(THREAD, arg_oop);
2618 } else {
2619 arg_array->obj_at_put(arg_i, arg_oop);
2620 }
2621 }
2622 }
2623
2624 argument_info_result = argument_info; // return argument_info to caller
2625 return bsm;
2626 }
2627 } else {
2628 ShouldNotReachHere(); // verifier does not allow this
2629 }
2630
2631 return empty;
2632 }
2633
2634 // Since the identity hash code for symbols changes when the symbols are
2635 // moved from the regular perm gen (hash in the mark word) to the shared
2636 // spaces (hash is the address), the classes loaded into the dictionary
2637 // may be in the wrong buckets.
2638
2639 void SystemDictionary::reorder_dictionary() {
2640 dictionary()->reorder_dictionary();
2641 }
2642
2643
2644 void SystemDictionary::copy_buckets(char** top, char* end) {
2645 dictionary()->copy_buckets(top, end);
2646 }
2647
2648
2649 void SystemDictionary::copy_table(char** top, char* end) {
2650 dictionary()->copy_table(top, end);
2651 }
2652
2653
2654 void SystemDictionary::reverse() {
2655 dictionary()->reverse();
2656 }
2657
2658 int SystemDictionary::number_of_classes() {
2659 return dictionary()->number_of_entries();
2660 }
2661
2662
2663 // ----------------------------------------------------------------------------
2664 #ifndef PRODUCT
2665
2666 void SystemDictionary::print() {
2667 dictionary()->print();
2668
2669 // Placeholders
2670 GCMutexLocker mu(SystemDictionary_lock);
2671 placeholders()->print();
2672
2673 // loader constraints - print under SD_lock
2674 constraints()->print();
2675 }
2676
2677 #endif
2678
2679 void SystemDictionary::verify() {
2680 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2681 guarantee(constraints() != NULL,
2682 "Verify of loader constraints failed");
2683 guarantee(dictionary()->number_of_entries() >= 0 &&
2684 placeholders()->number_of_entries() >= 0,
2685 "Verify of system dictionary failed");
2686
2687 // Verify dictionary
2688 dictionary()->verify();
2689
2690 GCMutexLocker mu(SystemDictionary_lock);
2691 placeholders()->verify();
2692
2693 // Verify constraint table
2694 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2695 constraints()->verify(dictionary(), placeholders());
2696 }
2697
2698
2699 void SystemDictionary::verify_obj_klass_present(Handle obj,
2700 Symbol* class_name,
2701 Handle class_loader) {
2702 GCMutexLocker mu(SystemDictionary_lock);
2703 Symbol* name;
2704
2705 klassOop probe = find_class(class_name, class_loader);
2706 if (probe == NULL) {
2707 probe = SystemDictionary::find_shared_class(class_name);
2708 if (probe == NULL) {
2709 name = find_placeholder(class_name, class_loader);
2710 }
2711 }
2712 guarantee(probe != NULL || name != NULL,
2713 "Loaded klasses should be in SystemDictionary");
2714 }
2715
2716 #ifndef PRODUCT
2717
2718 // statistics code
2719 class ClassStatistics: AllStatic {
2720 private:
2721 static int nclasses; // number of classes
2722 static int nmethods; // number of methods
2723 static int nmethoddata; // number of methodData
2724 static int class_size; // size of class objects in words
2725 static int method_size; // size of method objects in words
2726 static int debug_size; // size of debug info in methods
2727 static int methoddata_size; // size of methodData objects in words
2728
2729 static void do_class(klassOop k) {
2730 nclasses++;
2731 class_size += k->size();
2732 if (k->klass_part()->oop_is_instance()) {
2733 instanceKlass* ik = (instanceKlass*)k->klass_part();
2734 class_size += ik->methods()->size();
2735 class_size += ik->constants()->size();
2736 class_size += ik->local_interfaces()->size();
2737 class_size += ik->transitive_interfaces()->size();
2738 // We do not have to count implementors, since we only store one!
2739 class_size += ik->fields()->size();
2740 }
2741 }
2742
2743 static void do_method(methodOop m) {
2744 nmethods++;
2745 method_size += m->size();
2746 // class loader uses same objArray for empty vectors, so don't count these
2747 if (m->exception_table()->length() != 0) method_size += m->exception_table()->size();
2748 if (m->has_stackmap_table()) {
2749 method_size += m->stackmap_data()->size();
2750 }
2751
2752 methodDataOop mdo = m->method_data();
2753 if (mdo != NULL) {
2754 nmethoddata++;
2755 methoddata_size += mdo->size();
2756 }
2757 }
2758
2759 public:
2760 static void print() {
2761 SystemDictionary::classes_do(do_class);
2762 SystemDictionary::methods_do(do_method);
2763 tty->print_cr("Class statistics:");
2764 tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
2765 tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
2766 (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
2767 tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
2768 }
2769 };
2770
2771
2772 int ClassStatistics::nclasses = 0;
2773 int ClassStatistics::nmethods = 0;
2774 int ClassStatistics::nmethoddata = 0;
2775 int ClassStatistics::class_size = 0;
2776 int ClassStatistics::method_size = 0;
2777 int ClassStatistics::debug_size = 0;
2778 int ClassStatistics::methoddata_size = 0;
2779
2780 void SystemDictionary::print_class_statistics() {
2781 ResourceMark rm;
2782 ClassStatistics::print();
2783 }
2784
2785
2786 class MethodStatistics: AllStatic {
2787 public:
2788 enum {
2789 max_parameter_size = 10
2790 };
2791 private:
2792
2793 static int _number_of_methods;
2794 static int _number_of_final_methods;
2795 static int _number_of_static_methods;
2796 static int _number_of_native_methods;
2797 static int _number_of_synchronized_methods;
2798 static int _number_of_profiled_methods;
2799 static int _number_of_bytecodes;
2800 static int _parameter_size_profile[max_parameter_size];
2801 static int _bytecodes_profile[Bytecodes::number_of_java_codes];
2802
2803 static void initialize() {
2804 _number_of_methods = 0;
2805 _number_of_final_methods = 0;
2806 _number_of_static_methods = 0;
2807 _number_of_native_methods = 0;
2808 _number_of_synchronized_methods = 0;
2809 _number_of_profiled_methods = 0;
2810 _number_of_bytecodes = 0;
2811 for (int i = 0; i < max_parameter_size ; i++) _parameter_size_profile[i] = 0;
2812 for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile [j] = 0;
2813 };
2814
2815 static void do_method(methodOop m) {
2816 _number_of_methods++;
2817 // collect flag info
2818 if (m->is_final() ) _number_of_final_methods++;
2819 if (m->is_static() ) _number_of_static_methods++;
2820 if (m->is_native() ) _number_of_native_methods++;
2821 if (m->is_synchronized()) _number_of_synchronized_methods++;
2822 if (m->method_data() != NULL) _number_of_profiled_methods++;
2823 // collect parameter size info (add one for receiver, if any)
2824 _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
2825 // collect bytecodes info
2826 {
2827 Thread *thread = Thread::current();
2828 HandleMark hm(thread);
2829 BytecodeStream s(methodHandle(thread, m));
2830 Bytecodes::Code c;
2831 while ((c = s.next()) >= 0) {
2832 _number_of_bytecodes++;
2833 _bytecodes_profile[c]++;
2834 }
2835 }
2836 }
2837
2838 public:
2839 static void print() {
2840 initialize();
2841 SystemDictionary::methods_do(do_method);
2842 // generate output
2843 tty->cr();
2844 tty->print_cr("Method statistics (static):");
2845 // flag distribution
2846 tty->cr();
2847 tty->print_cr("%6d final methods %6.1f%%", _number_of_final_methods , _number_of_final_methods * 100.0F / _number_of_methods);
2848 tty->print_cr("%6d static methods %6.1f%%", _number_of_static_methods , _number_of_static_methods * 100.0F / _number_of_methods);
2849 tty->print_cr("%6d native methods %6.1f%%", _number_of_native_methods , _number_of_native_methods * 100.0F / _number_of_methods);
2850 tty->print_cr("%6d synchronized methods %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
2851 tty->print_cr("%6d profiled methods %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
2852 // parameter size profile
2853 tty->cr();
2854 { int tot = 0;
2855 int avg = 0;
2856 for (int i = 0; i < max_parameter_size; i++) {
2857 int n = _parameter_size_profile[i];
2858 tot += n;
2859 avg += n*i;
2860 tty->print_cr("parameter size = %1d: %6d methods %5.1f%%", i, n, n * 100.0F / _number_of_methods);
2861 }
2862 assert(tot == _number_of_methods, "should be the same");
2863 tty->print_cr(" %6d methods 100.0%%", _number_of_methods);
2864 tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
2865 }
2866 // bytecodes profile
2867 tty->cr();
2868 { int tot = 0;
2869 for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
2870 if (Bytecodes::is_defined(i)) {
2871 Bytecodes::Code c = Bytecodes::cast(i);
2872 int n = _bytecodes_profile[c];
2873 tot += n;
2874 tty->print_cr("%9d %7.3f%% %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
2875 }
2876 }
2877 assert(tot == _number_of_bytecodes, "should be the same");
2878 tty->print_cr("%9d 100.000%%", _number_of_bytecodes);
2879 }
2880 tty->cr();
2881 }
2882 };
2883
2884 int MethodStatistics::_number_of_methods;
2885 int MethodStatistics::_number_of_final_methods;
2886 int MethodStatistics::_number_of_static_methods;
2887 int MethodStatistics::_number_of_native_methods;
2888 int MethodStatistics::_number_of_synchronized_methods;
2889 int MethodStatistics::_number_of_profiled_methods;
2890 int MethodStatistics::_number_of_bytecodes;
2891 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
2892 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
2893
2894
2895 void SystemDictionary::print_method_statistics() {
2896 MethodStatistics::print();
2897 }
2898
2899 #endif // PRODUCT