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(AnonymousClasses, ""); 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 } 1259 1260 if (TraceClassLoading) { 1261 ResourceMark rm; 1262 tty->print("[Loaded %s", ik->external_name()); 1263 tty->print(" from shared objects file"); 1264 tty->print_cr("]"); 1265 } 1266 // notify a class loaded from shared object 1267 ClassLoadingService::notify_class_loaded(instanceKlass::cast(ik()), 1268 true /* shared class */); 1269 } 1270 return ik; 1271 } 1272 1273 #ifdef KERNEL 1274 // Some classes on the bootstrap class path haven't been installed on the 1275 // system yet. Call the DownloadManager method to make them appear in the 1276 // bootstrap class path and try again to load the named class. 1277 // Note that with delegation class loaders all classes in another loader will 1278 // first try to call this so it'd better be fast!! 1279 static instanceKlassHandle download_and_retry_class_load( 1280 Symbol* class_name, 1281 TRAPS) { 1282 1283 klassOop dlm = SystemDictionary::sun_jkernel_DownloadManager_klass(); 1284 instanceKlassHandle nk; 1285 1286 // If download manager class isn't loaded just return. 1287 if (dlm == NULL) return nk; 1288 1289 { HandleMark hm(THREAD); 1290 ResourceMark rm(THREAD); 1291 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nk)); 1292 Handle class_string = java_lang_String::externalize_classname(s, CHECK_(nk)); 1293 1294 // return value 1295 JavaValue result(T_OBJECT); 1296 1297 // Call the DownloadManager. We assume that it has a lock because 1298 // multiple classes could be not found and downloaded at the same time. 1299 // class sun.misc.DownloadManager; 1300 // public static String getBootClassPathEntryForClass(String className); 1301 JavaCalls::call_static(&result, 1302 KlassHandle(THREAD, dlm), 1303 vmSymbols::getBootClassPathEntryForClass_name(), 1304 vmSymbols::string_string_signature(), 1305 class_string, 1306 CHECK_(nk)); 1307 1308 // Get result.string and add to bootclasspath 1309 assert(result.get_type() == T_OBJECT, "just checking"); 1310 oop obj = (oop) result.get_jobject(); 1311 if (obj == NULL) { return nk; } 1312 1313 Handle h_obj(THREAD, obj); 1314 char* new_class_name = java_lang_String::as_platform_dependent_str(h_obj, 1315 CHECK_(nk)); 1316 1317 // lock the loader 1318 // we use this lock because JVMTI does. 1319 Handle loader_lock(THREAD, SystemDictionary::system_loader_lock()); 1320 1321 ObjectLocker ol(loader_lock, THREAD); 1322 // add the file to the bootclasspath 1323 ClassLoader::update_class_path_entry_list(new_class_name, true); 1324 } // end HandleMark 1325 1326 if (TraceClassLoading) { 1327 ClassLoader::print_bootclasspath(); 1328 } 1329 return ClassLoader::load_classfile(class_name, CHECK_(nk)); 1330 } 1331 #endif // KERNEL 1332 1333 1334 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) { 1335 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1336 if (class_loader.is_null()) { 1337 1338 // Search the shared system dictionary for classes preloaded into the 1339 // shared spaces. 1340 instanceKlassHandle k; 1341 { 1342 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time()); 1343 k = load_shared_class(class_name, class_loader, THREAD); 1344 } 1345 1346 if (k.is_null()) { 1347 // Use VM class loader 1348 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time()); 1349 k = ClassLoader::load_classfile(class_name, CHECK_(nh)); 1350 } 1351 1352 #ifdef KERNEL 1353 // If the VM class loader has failed to load the class, call the 1354 // DownloadManager class to make it magically appear on the classpath 1355 // and try again. This is only configured with the Kernel VM. 1356 if (k.is_null()) { 1357 k = download_and_retry_class_load(class_name, CHECK_(nh)); 1358 } 1359 #endif // KERNEL 1360 1361 // find_or_define_instance_class may return a different instanceKlass 1362 if (!k.is_null()) { 1363 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh)); 1364 } 1365 return k; 1366 } else { 1367 // Use user specified class loader to load class. Call loadClass operation on class_loader. 1368 ResourceMark rm(THREAD); 1369 1370 assert(THREAD->is_Java_thread(), "must be a JavaThread"); 1371 JavaThread* jt = (JavaThread*) THREAD; 1372 1373 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(), 1374 ClassLoader::perf_app_classload_selftime(), 1375 ClassLoader::perf_app_classload_count(), 1376 jt->get_thread_stat()->perf_recursion_counts_addr(), 1377 jt->get_thread_stat()->perf_timers_addr(), 1378 PerfClassTraceTime::CLASS_LOAD); 1379 1380 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh)); 1381 // Translate to external class name format, i.e., convert '/' chars to '.' 1382 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh)); 1383 1384 JavaValue result(T_OBJECT); 1385 1386 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass()); 1387 1388 // Call public unsynchronized loadClass(String) directly for all class loaders 1389 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will 1390 // acquire a class-name based lock rather than the class loader object lock. 1391 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean), 1392 // so the call to loadClassInternal() was not required. 1393 // 1394 // UnsyncloadClass flag means both call loadClass(String) and do 1395 // not acquire the class loader lock even for class loaders that are 1396 // not parallelCapable. This was a risky transitional 1397 // flag for diagnostic purposes only. It is risky to call 1398 // custom class loaders without synchronization. 1399 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of 1400 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field. 1401 // Do NOT assume this will be supported in future releases. 1402 // 1403 // Added MustCallLoadClassInternal in case we discover in the field 1404 // a customer that counts on this call 1405 if (MustCallLoadClassInternal && has_loadClassInternal()) { 1406 JavaCalls::call_special(&result, 1407 class_loader, 1408 spec_klass, 1409 vmSymbols::loadClassInternal_name(), 1410 vmSymbols::string_class_signature(), 1411 string, 1412 CHECK_(nh)); 1413 } else { 1414 JavaCalls::call_virtual(&result, 1415 class_loader, 1416 spec_klass, 1417 vmSymbols::loadClass_name(), 1418 vmSymbols::string_class_signature(), 1419 string, 1420 CHECK_(nh)); 1421 } 1422 1423 assert(result.get_type() == T_OBJECT, "just checking"); 1424 oop obj = (oop) result.get_jobject(); 1425 1426 // Primitive classes return null since forName() can not be 1427 // used to obtain any of the Class objects representing primitives or void 1428 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) { 1429 instanceKlassHandle k = 1430 instanceKlassHandle(THREAD, java_lang_Class::as_klassOop(obj)); 1431 // For user defined Java class loaders, check that the name returned is 1432 // the same as that requested. This check is done for the bootstrap 1433 // loader when parsing the class file. 1434 if (class_name == k->name()) { 1435 return k; 1436 } 1437 } 1438 // Class is not found or has the wrong name, return NULL 1439 return nh; 1440 } 1441 } 1442 1443 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) { 1444 1445 Handle class_loader_h(THREAD, k->class_loader()); 1446 1447 // for bootstrap and other parallel classloaders don't acquire lock, 1448 // use placeholder token 1449 // If a parallelCapable class loader calls define_instance_class instead of 1450 // find_or_define_instance_class to get here, we have a timing 1451 // hole with systemDictionary updates and check_constraints 1452 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) { 1453 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, 1454 compute_loader_lock_object(class_loader_h, THREAD)), 1455 "define called without lock"); 1456 } 1457 1458 // Check class-loading constraints. Throw exception if violation is detected. 1459 // Grabs and releases SystemDictionary_lock 1460 // The check_constraints/find_class call and update_dictionary sequence 1461 // must be "atomic" for a specific class/classloader pair so we never 1462 // define two different instanceKlasses for that class/classloader pair. 1463 // Existing classloaders will call define_instance_class with the 1464 // classloader lock held 1465 // Parallel classloaders will call find_or_define_instance_class 1466 // which will require a token to perform the define class 1467 Symbol* name_h = k->name(); 1468 unsigned int d_hash = dictionary()->compute_hash(name_h, class_loader_h); 1469 int d_index = dictionary()->hash_to_index(d_hash); 1470 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK); 1471 1472 // Register class just loaded with class loader (placed in Vector) 1473 // Note we do this before updating the dictionary, as this can 1474 // fail with an OutOfMemoryError (if it does, we will *not* put this 1475 // class in the dictionary and will not update the class hierarchy). 1476 if (k->class_loader() != NULL) { 1477 methodHandle m(THREAD, Universe::loader_addClass_method()); 1478 JavaValue result(T_VOID); 1479 JavaCallArguments args(class_loader_h); 1480 args.push_oop(Handle(THREAD, k->java_mirror())); 1481 JavaCalls::call(&result, m, &args, CHECK); 1482 } 1483 1484 // Add the new class. We need recompile lock during update of CHA. 1485 { 1486 unsigned int p_hash = placeholders()->compute_hash(name_h, class_loader_h); 1487 int p_index = placeholders()->hash_to_index(p_hash); 1488 1489 MutexLocker mu_r(Compile_lock, THREAD); 1490 1491 // Add to class hierarchy, initialize vtables, and do possible 1492 // deoptimizations. 1493 add_to_hierarchy(k, CHECK); // No exception, but can block 1494 1495 // Add to systemDictionary - so other classes can see it. 1496 // Grabs and releases SystemDictionary_lock 1497 update_dictionary(d_index, d_hash, p_index, p_hash, 1498 k, class_loader_h, THREAD); 1499 } 1500 k->eager_initialize(THREAD); 1501 1502 // notify jvmti 1503 if (JvmtiExport::should_post_class_load()) { 1504 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1505 JvmtiExport::post_class_load((JavaThread *) THREAD, k()); 1506 1507 } 1508 } 1509 1510 // Support parallel classloading 1511 // All parallel class loaders, including bootstrap classloader 1512 // lock a placeholder entry for this class/class_loader pair 1513 // to allow parallel defines of different classes for this class loader 1514 // With AllowParallelDefine flag==true, in case they do not synchronize around 1515 // FindLoadedClass/DefineClass, calls, we check for parallel 1516 // loading for them, wait if a defineClass is in progress 1517 // and return the initial requestor's results 1518 // This flag does not apply to the bootstrap classloader. 1519 // With AllowParallelDefine flag==false, call through to define_instance_class 1520 // which will throw LinkageError: duplicate class definition. 1521 // False is the requested default. 1522 // For better performance, the class loaders should synchronize 1523 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they 1524 // potentially waste time reading and parsing the bytestream. 1525 // Note: VM callers should ensure consistency of k/class_name,class_loader 1526 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) { 1527 1528 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1529 Symbol* name_h = k->name(); // passed in class_name may be null 1530 1531 unsigned int d_hash = dictionary()->compute_hash(name_h, class_loader); 1532 int d_index = dictionary()->hash_to_index(d_hash); 1533 1534 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS 1535 unsigned int p_hash = placeholders()->compute_hash(name_h, class_loader); 1536 int p_index = placeholders()->hash_to_index(p_hash); 1537 PlaceholderEntry* probe; 1538 1539 { 1540 MutexLocker mu(SystemDictionary_lock, THREAD); 1541 // First check if class already defined 1542 if (UnsyncloadClass || (is_parallelDefine(class_loader))) { 1543 klassOop check = find_class(d_index, d_hash, name_h, class_loader); 1544 if (check != NULL) { 1545 return(instanceKlassHandle(THREAD, check)); 1546 } 1547 } 1548 1549 // Acquire define token for this class/classloader 1550 probe = placeholders()->find_and_add(p_index, p_hash, name_h, class_loader, PlaceholderTable::DEFINE_CLASS, NULL, THREAD); 1551 // Wait if another thread defining in parallel 1552 // All threads wait - even those that will throw duplicate class: otherwise 1553 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails 1554 // if other thread has not finished updating dictionary 1555 while (probe->definer() != NULL) { 1556 SystemDictionary_lock->wait(); 1557 } 1558 // Only special cases allow parallel defines and can use other thread's results 1559 // Other cases fall through, and may run into duplicate defines 1560 // caught by finding an entry in the SystemDictionary 1561 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instanceKlass() != NULL)) { 1562 probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS); 1563 placeholders()->find_and_remove(p_index, p_hash, name_h, class_loader, THREAD); 1564 SystemDictionary_lock->notify_all(); 1565 #ifdef ASSERT 1566 klassOop check = find_class(d_index, d_hash, name_h, class_loader); 1567 assert(check != NULL, "definer missed recording success"); 1568 #endif 1569 return(instanceKlassHandle(THREAD, probe->instanceKlass())); 1570 } else { 1571 // This thread will define the class (even if earlier thread tried and had an error) 1572 probe->set_definer(THREAD); 1573 } 1574 } 1575 1576 define_instance_class(k, THREAD); 1577 1578 Handle linkage_exception = Handle(); // null handle 1579 1580 // definer must notify any waiting threads 1581 { 1582 MutexLocker mu(SystemDictionary_lock, THREAD); 1583 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, class_loader); 1584 assert(probe != NULL, "DEFINE_CLASS placeholder lost?"); 1585 if (probe != NULL) { 1586 if (HAS_PENDING_EXCEPTION) { 1587 linkage_exception = Handle(THREAD,PENDING_EXCEPTION); 1588 CLEAR_PENDING_EXCEPTION; 1589 } else { 1590 probe->set_instanceKlass(k()); 1591 } 1592 probe->set_definer(NULL); 1593 probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS); 1594 placeholders()->find_and_remove(p_index, p_hash, name_h, class_loader, THREAD); 1595 SystemDictionary_lock->notify_all(); 1596 } 1597 } 1598 1599 // Can't throw exception while holding lock due to rank ordering 1600 if (linkage_exception() != NULL) { 1601 THROW_OOP_(linkage_exception(), nh); // throws exception and returns 1602 } 1603 1604 return k; 1605 } 1606 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) { 1607 // If class_loader is NULL we synchronize on _system_loader_lock_obj 1608 if (class_loader.is_null()) { 1609 return Handle(THREAD, _system_loader_lock_obj); 1610 } else { 1611 return class_loader; 1612 } 1613 } 1614 1615 // This method is added to check how often we have to wait to grab loader 1616 // lock. The results are being recorded in the performance counters defined in 1617 // ClassLoader::_sync_systemLoaderLockContentionRate and 1618 // ClassLoader::_sync_nonSystemLoaderLockConteionRate. 1619 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) { 1620 if (!UsePerfData) { 1621 return; 1622 } 1623 1624 assert(!loader_lock.is_null(), "NULL lock object"); 1625 1626 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock) 1627 == ObjectSynchronizer::owner_other) { 1628 // contention will likely happen, so increment the corresponding 1629 // contention counter. 1630 if (loader_lock() == _system_loader_lock_obj) { 1631 ClassLoader::sync_systemLoaderLockContentionRate()->inc(); 1632 } else { 1633 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc(); 1634 } 1635 } 1636 } 1637 1638 // ---------------------------------------------------------------------------- 1639 // Lookup 1640 1641 klassOop SystemDictionary::find_class(int index, unsigned int hash, 1642 Symbol* class_name, 1643 Handle class_loader) { 1644 assert_locked_or_safepoint(SystemDictionary_lock); 1645 assert (index == dictionary()->index_for(class_name, class_loader), 1646 "incorrect index?"); 1647 1648 klassOop k = dictionary()->find_class(index, hash, class_name, class_loader); 1649 return k; 1650 } 1651 1652 1653 // Basic find on classes in the midst of being loaded 1654 Symbol* SystemDictionary::find_placeholder(Symbol* class_name, 1655 Handle class_loader) { 1656 assert_locked_or_safepoint(SystemDictionary_lock); 1657 unsigned int p_hash = placeholders()->compute_hash(class_name, class_loader); 1658 int p_index = placeholders()->hash_to_index(p_hash); 1659 return placeholders()->find_entry(p_index, p_hash, class_name, class_loader); 1660 } 1661 1662 1663 // Used for assertions and verification only 1664 klassOop SystemDictionary::find_class(Symbol* class_name, Handle class_loader) { 1665 #ifndef ASSERT 1666 guarantee(VerifyBeforeGC || 1667 VerifyDuringGC || 1668 VerifyBeforeExit || 1669 VerifyAfterGC, "too expensive"); 1670 #endif 1671 assert_locked_or_safepoint(SystemDictionary_lock); 1672 1673 // First look in the loaded class array 1674 unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader); 1675 int d_index = dictionary()->hash_to_index(d_hash); 1676 return find_class(d_index, d_hash, class_name, class_loader); 1677 } 1678 1679 1680 // Get the next class in the diictionary. 1681 klassOop SystemDictionary::try_get_next_class() { 1682 return dictionary()->try_get_next_class(); 1683 } 1684 1685 1686 // ---------------------------------------------------------------------------- 1687 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock 1688 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in 1689 // before a new class is used. 1690 1691 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) { 1692 assert(k.not_null(), "just checking"); 1693 assert_locked_or_safepoint(Compile_lock); 1694 1695 // Link into hierachy. Make sure the vtables are initialized before linking into 1696 k->append_to_sibling_list(); // add to superklass/sibling list 1697 k->process_interfaces(THREAD); // handle all "implements" declarations 1698 k->set_init_state(instanceKlass::loaded); 1699 // Now flush all code that depended on old class hierarchy. 1700 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97) 1701 // Also, first reinitialize vtable because it may have gotten out of synch 1702 // while the new class wasn't connected to the class hierarchy. 1703 Universe::flush_dependents_on(k); 1704 } 1705 1706 1707 // ---------------------------------------------------------------------------- 1708 // GC support 1709 1710 // Following roots during mark-sweep is separated in two phases. 1711 // 1712 // The first phase follows preloaded classes and all other system 1713 // classes, since these will never get unloaded anyway. 1714 // 1715 // The second phase removes (unloads) unreachable classes from the 1716 // system dictionary and follows the remaining classes' contents. 1717 1718 void SystemDictionary::always_strong_oops_do(OopClosure* blk) { 1719 // Follow preloaded classes/mirrors and system loader object 1720 blk->do_oop(&_java_system_loader); 1721 preloaded_oops_do(blk); 1722 always_strong_classes_do(blk); 1723 } 1724 1725 1726 void SystemDictionary::always_strong_classes_do(OopClosure* blk) { 1727 // Follow all system classes and temporary placeholders in dictionary 1728 dictionary()->always_strong_classes_do(blk); 1729 1730 // Placeholders. These are *always* strong roots, as they 1731 // represent classes we're actively loading. 1732 placeholders_do(blk); 1733 1734 // Visit extra methods 1735 invoke_method_table()->oops_do(blk); 1736 } 1737 1738 1739 void SystemDictionary::placeholders_do(OopClosure* blk) { 1740 placeholders()->oops_do(blk); 1741 } 1742 1743 1744 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) { 1745 bool result = dictionary()->do_unloading(is_alive); 1746 constraints()->purge_loader_constraints(is_alive); 1747 resolution_errors()->purge_resolution_errors(is_alive); 1748 return result; 1749 } 1750 1751 1752 // The mirrors are scanned by shared_oops_do() which is 1753 // not called by oops_do(). In order to process oops in 1754 // a necessary order, shared_oops_do() is call by 1755 // Universe::oops_do(). 1756 void SystemDictionary::oops_do(OopClosure* f) { 1757 // Adjust preloaded classes and system loader object 1758 f->do_oop(&_java_system_loader); 1759 preloaded_oops_do(f); 1760 1761 lazily_loaded_oops_do(f); 1762 1763 // Adjust dictionary 1764 dictionary()->oops_do(f); 1765 1766 // Visit extra methods 1767 invoke_method_table()->oops_do(f); 1768 1769 // Partially loaded classes 1770 placeholders()->oops_do(f); 1771 1772 // Adjust constraint table 1773 constraints()->oops_do(f); 1774 1775 // Adjust resolution error table 1776 resolution_errors()->oops_do(f); 1777 } 1778 1779 1780 void SystemDictionary::preloaded_oops_do(OopClosure* f) { 1781 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) { 1782 f->do_oop((oop*) &_well_known_klasses[k]); 1783 } 1784 1785 { 1786 for (int i = 0; i < T_VOID+1; i++) { 1787 if (_box_klasses[i] != NULL) { 1788 assert(i >= T_BOOLEAN, "checking"); 1789 f->do_oop((oop*) &_box_klasses[i]); 1790 } 1791 } 1792 } 1793 1794 // The basic type mirrors would have already been processed in 1795 // Universe::oops_do(), via a call to shared_oops_do(), so should 1796 // not be processed again. 1797 1798 f->do_oop((oop*) &_system_loader_lock_obj); 1799 FilteredFieldsMap::klasses_oops_do(f); 1800 } 1801 1802 void SystemDictionary::lazily_loaded_oops_do(OopClosure* f) { 1803 f->do_oop((oop*) &_abstract_ownable_synchronizer_klass); 1804 } 1805 1806 // Just the classes from defining class loaders 1807 // Don't iterate over placeholders 1808 void SystemDictionary::classes_do(void f(klassOop)) { 1809 dictionary()->classes_do(f); 1810 } 1811 1812 // Added for initialize_itable_for_klass 1813 // Just the classes from defining class loaders 1814 // Don't iterate over placeholders 1815 void SystemDictionary::classes_do(void f(klassOop, TRAPS), TRAPS) { 1816 dictionary()->classes_do(f, CHECK); 1817 } 1818 1819 // All classes, and their class loaders 1820 // Don't iterate over placeholders 1821 void SystemDictionary::classes_do(void f(klassOop, oop)) { 1822 dictionary()->classes_do(f); 1823 } 1824 1825 // All classes, and their class loaders 1826 // (added for helpers that use HandleMarks and ResourceMarks) 1827 // Don't iterate over placeholders 1828 void SystemDictionary::classes_do(void f(klassOop, oop, TRAPS), TRAPS) { 1829 dictionary()->classes_do(f, CHECK); 1830 } 1831 1832 void SystemDictionary::placeholders_do(void f(Symbol*, oop)) { 1833 placeholders()->entries_do(f); 1834 } 1835 1836 void SystemDictionary::methods_do(void f(methodOop)) { 1837 dictionary()->methods_do(f); 1838 invoke_method_table()->methods_do(f); 1839 } 1840 1841 // ---------------------------------------------------------------------------- 1842 // Lazily load klasses 1843 1844 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) { 1845 assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later"); 1846 1847 // if multiple threads calling this function, only one thread will load 1848 // the class. The other threads will find the loaded version once the 1849 // class is loaded. 1850 klassOop aos = _abstract_ownable_synchronizer_klass; 1851 if (aos == NULL) { 1852 klassOop k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK); 1853 // Force a fence to prevent any read before the write completes 1854 OrderAccess::fence(); 1855 _abstract_ownable_synchronizer_klass = k; 1856 } 1857 } 1858 1859 // ---------------------------------------------------------------------------- 1860 // Initialization 1861 1862 void SystemDictionary::initialize(TRAPS) { 1863 // Allocate arrays 1864 assert(dictionary() == NULL, 1865 "SystemDictionary should only be initialized once"); 1866 _dictionary = new Dictionary(_nof_buckets); 1867 _placeholders = new PlaceholderTable(_nof_buckets); 1868 _number_of_modifications = 0; 1869 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size); 1870 _resolution_errors = new ResolutionErrorTable(_resolution_error_size); 1871 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size); 1872 1873 // Allocate private object used as system class loader lock 1874 _system_loader_lock_obj = oopFactory::new_system_objArray(0, CHECK); 1875 // Initialize basic classes 1876 initialize_preloaded_classes(CHECK); 1877 } 1878 1879 // Compact table of directions on the initialization of klasses: 1880 static const short wk_init_info[] = { 1881 #define WK_KLASS_INIT_INFO(name, symbol, option) \ 1882 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \ 1883 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \ 1884 | (int)SystemDictionary::option ), 1885 WK_KLASSES_DO(WK_KLASS_INIT_INFO) 1886 #undef WK_KLASS_INIT_INFO 1887 0 1888 }; 1889 1890 Symbol* SystemDictionary::find_backup_symbol(Symbol* symbol, 1891 const char* from_prefix, 1892 const char* to_prefix) { 1893 assert(AllowTransitionalJSR292, ""); // delete this subroutine 1894 Symbol* backup_symbol = NULL; 1895 size_t from_len = strlen(from_prefix); 1896 if (strncmp((const char*) symbol->base(), from_prefix, from_len) != 0) 1897 return NULL; 1898 char buf[100]; 1899 size_t to_len = strlen(to_prefix); 1900 size_t tail_len = symbol->utf8_length() - from_len; 1901 size_t new_len = to_len + tail_len; 1902 guarantee(new_len < sizeof(buf), "buf too small"); 1903 memcpy(buf, to_prefix, to_len); 1904 memcpy(buf + to_len, symbol->base() + from_len, tail_len); 1905 buf[new_len] = '\0'; 1906 vmSymbols::SID backup_sid = vmSymbols::find_sid(buf); 1907 if (backup_sid != vmSymbols::NO_SID) { 1908 backup_symbol = vmSymbols::symbol_at(backup_sid); 1909 } 1910 return backup_symbol; 1911 } 1912 1913 Symbol* SystemDictionary::find_backup_class_name(Symbol* symbol) { 1914 assert(AllowTransitionalJSR292, ""); // delete this subroutine 1915 if (symbol == NULL) return NULL; 1916 Symbol* backup_symbol = find_backup_symbol(symbol, "java/lang/invoke/", "java/dyn/"); // AllowTransitionalJSR292 ONLY 1917 if (backup_symbol == NULL) 1918 backup_symbol = find_backup_symbol(symbol, "java/dyn/", "sun/dyn/"); // AllowTransitionalJSR292 ONLY 1919 return backup_symbol; 1920 } 1921 1922 Symbol* SystemDictionary::find_backup_signature(Symbol* symbol) { 1923 assert(AllowTransitionalJSR292, ""); // delete this subroutine 1924 if (symbol == NULL) return NULL; 1925 return find_backup_symbol(symbol, "Ljava/lang/invoke/", "Ljava/dyn/"); 1926 } 1927 1928 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) { 1929 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 1930 int info = wk_init_info[id - FIRST_WKID]; 1931 int sid = (info >> CEIL_LG_OPTION_LIMIT); 1932 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid); 1933 klassOop* klassp = &_well_known_klasses[id]; 1934 bool pre_load = (init_opt < SystemDictionary::Opt); 1935 bool try_load = true; 1936 if (init_opt == SystemDictionary::Opt_Kernel) { 1937 #ifndef KERNEL 1938 try_load = false; 1939 #endif //KERNEL 1940 } 1941 Symbol* backup_symbol = NULL; // symbol to try if the current symbol fails 1942 if (init_opt == SystemDictionary::Pre_JSR292) { 1943 if (!EnableMethodHandles) try_load = false; // do not bother to load such classes 1944 if (AllowTransitionalJSR292) { 1945 backup_symbol = find_backup_class_name(symbol); 1946 if (try_load && PreferTransitionalJSR292) { 1947 while (backup_symbol != NULL) { 1948 (*klassp) = resolve_or_null(backup_symbol, CHECK_0); // try backup early 1949 if (TraceMethodHandles) { 1950 ResourceMark rm; 1951 tty->print_cr("MethodHandles: try backup first for %s => %s (%s)", 1952 symbol->as_C_string(), backup_symbol->as_C_string(), 1953 ((*klassp) == NULL) ? "no such class" : "backup load succeeded"); 1954 } 1955 if ((*klassp) != NULL) return true; 1956 backup_symbol = find_backup_class_name(backup_symbol); // find next backup 1957 } 1958 } 1959 } 1960 } 1961 if ((*klassp) != NULL) return true; 1962 if (!try_load) return false; 1963 while (symbol != NULL) { 1964 bool must_load = (pre_load && (backup_symbol == NULL)); 1965 if (must_load) { 1966 (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class 1967 } else { 1968 (*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass 1969 } 1970 if ((*klassp) != NULL) return true; 1971 // Go around again. Example of long backup sequence: 1972 // java.lang.invoke.MemberName, java.dyn.MemberName, sun.dyn.MemberName, ONLY if AllowTransitionalJSR292 1973 if (TraceMethodHandles && (backup_symbol != NULL)) { 1974 ResourceMark rm; 1975 tty->print_cr("MethodHandles: backup for %s => %s", 1976 symbol->as_C_string(), backup_symbol->as_C_string()); 1977 } 1978 symbol = backup_symbol; 1979 if (AllowTransitionalJSR292) 1980 backup_symbol = find_backup_class_name(symbol); 1981 } 1982 return false; 1983 } 1984 1985 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) { 1986 assert((int)start_id <= (int)limit_id, "IDs are out of order!"); 1987 for (int id = (int)start_id; id < (int)limit_id; id++) { 1988 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 1989 int info = wk_init_info[id - FIRST_WKID]; 1990 int sid = (info >> CEIL_LG_OPTION_LIMIT); 1991 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT)); 1992 1993 initialize_wk_klass((WKID)id, opt, CHECK); 1994 1995 // Update limits, so find_well_known_klass can be very fast: 1996 Symbol* s = vmSymbols::symbol_at((vmSymbols::SID)sid); 1997 if (wk_klass_name_limits[1] == NULL) { 1998 wk_klass_name_limits[0] = wk_klass_name_limits[1] = s; 1999 } else if (wk_klass_name_limits[1] < s) { 2000 wk_klass_name_limits[1] = s; 2001 } else if (wk_klass_name_limits[0] > s) { 2002 wk_klass_name_limits[0] = s; 2003 } 2004 } 2005 2006 // move the starting value forward to the limit: 2007 start_id = limit_id; 2008 } 2009 2010 2011 void SystemDictionary::initialize_preloaded_classes(TRAPS) { 2012 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once"); 2013 // Preload commonly used klasses 2014 WKID scan = FIRST_WKID; 2015 // first do Object, String, Class 2016 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 2017 2018 debug_only(instanceKlass::verify_class_klass_nonstatic_oop_maps(WK_KLASS(Class_klass))); 2019 2020 // Fixup mirrors for classes loaded before java.lang.Class. 2021 // These calls iterate over the objects currently in the perm gen 2022 // so calling them at this point is matters (not before when there 2023 // are fewer objects and not later after there are more objects 2024 // in the perm gen. 2025 Universe::initialize_basic_type_mirrors(CHECK); 2026 Universe::fixup_mirrors(CHECK); 2027 2028 // do a bunch more: 2029 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK); 2030 2031 // Preload ref klasses and set reference types 2032 instanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER); 2033 instanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass)); 2034 2035 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK); 2036 instanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT); 2037 instanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK); 2038 instanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL); 2039 instanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM); 2040 2041 WKID meth_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass); 2042 WKID meth_group_end = WK_KLASS_ENUM_NAME(WrongMethodTypeException_klass); 2043 initialize_wk_klasses_until(meth_group_start, scan, CHECK); 2044 if (EnableMethodHandles) { 2045 initialize_wk_klasses_through(meth_group_end, scan, CHECK); 2046 } 2047 if (_well_known_klasses[meth_group_start] == NULL) { 2048 // Skip the rest of the method handle classes, if MethodHandle is not loaded. 2049 scan = WKID(meth_group_end+1); 2050 } 2051 WKID indy_group_start = WK_KLASS_ENUM_NAME(Linkage_klass); 2052 WKID indy_group_end = WK_KLASS_ENUM_NAME(CallSite_klass); 2053 initialize_wk_klasses_until(indy_group_start, scan, CHECK); 2054 if (EnableInvokeDynamic) { 2055 initialize_wk_klasses_through(indy_group_end, scan, CHECK); 2056 } 2057 if (_well_known_klasses[indy_group_start] == NULL) { 2058 // Skip the rest of the dynamic typing classes, if Linkage is not loaded. 2059 scan = WKID(indy_group_end+1); 2060 } 2061 2062 initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK); 2063 2064 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass); 2065 _box_klasses[T_CHAR] = WK_KLASS(Character_klass); 2066 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass); 2067 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass); 2068 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass); 2069 _box_klasses[T_SHORT] = WK_KLASS(Short_klass); 2070 _box_klasses[T_INT] = WK_KLASS(Integer_klass); 2071 _box_klasses[T_LONG] = WK_KLASS(Long_klass); 2072 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass); 2073 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass); 2074 2075 #ifdef KERNEL 2076 if (sun_jkernel_DownloadManager_klass() == NULL) { 2077 warning("Cannot find sun/jkernel/DownloadManager"); 2078 } 2079 #endif // KERNEL 2080 2081 { // Compute whether we should use loadClass or loadClassInternal when loading classes. 2082 methodOop method = instanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature()); 2083 _has_loadClassInternal = (method != NULL); 2084 } 2085 { // Compute whether we should use checkPackageAccess or NOT 2086 methodOop method = instanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature()); 2087 _has_checkPackageAccess = (method != NULL); 2088 } 2089 } 2090 2091 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer). 2092 // If so, returns the basic type it holds. If not, returns T_OBJECT. 2093 BasicType SystemDictionary::box_klass_type(klassOop k) { 2094 assert(k != NULL, ""); 2095 for (int i = T_BOOLEAN; i < T_VOID+1; i++) { 2096 if (_box_klasses[i] == k) 2097 return (BasicType)i; 2098 } 2099 return T_OBJECT; 2100 } 2101 2102 KlassHandle SystemDictionaryHandles::box_klass(BasicType t) { 2103 if (t >= T_BOOLEAN && t <= T_VOID) 2104 return KlassHandle(&SystemDictionary::_box_klasses[t], true); 2105 else 2106 return KlassHandle(); 2107 } 2108 2109 // Constraints on class loaders. The details of the algorithm can be 2110 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java 2111 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is 2112 // that the system dictionary needs to maintain a set of contraints that 2113 // must be satisfied by all classes in the dictionary. 2114 // if defining is true, then LinkageError if already in systemDictionary 2115 // if initiating loader, then ok if instanceKlass matches existing entry 2116 2117 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash, 2118 instanceKlassHandle k, 2119 Handle class_loader, bool defining, 2120 TRAPS) { 2121 const char *linkage_error = NULL; 2122 { 2123 Symbol* name = k->name(); 2124 MutexLocker mu(SystemDictionary_lock, THREAD); 2125 2126 klassOop check = find_class(d_index, d_hash, name, class_loader); 2127 if (check != (klassOop)NULL) { 2128 // if different instanceKlass - duplicate class definition, 2129 // else - ok, class loaded by a different thread in parallel, 2130 // we should only have found it if it was done loading and ok to use 2131 // system dictionary only holds instance classes, placeholders 2132 // also holds array classes 2133 2134 assert(check->klass_part()->oop_is_instance(), "noninstance in systemdictionary"); 2135 if ((defining == true) || (k() != check)) { 2136 linkage_error = "loader (instance of %s): attempted duplicate class " 2137 "definition for name: \"%s\""; 2138 } else { 2139 return; 2140 } 2141 } 2142 2143 #ifdef ASSERT 2144 Symbol* ph_check = find_placeholder(name, class_loader); 2145 assert(ph_check == NULL || ph_check == name, "invalid symbol"); 2146 #endif 2147 2148 if (linkage_error == NULL) { 2149 if (constraints()->check_or_update(k, class_loader, name) == false) { 2150 linkage_error = "loader constraint violation: loader (instance of %s)" 2151 " previously initiated loading for a different type with name \"%s\""; 2152 } 2153 } 2154 } 2155 2156 // Throw error now if needed (cannot throw while holding 2157 // SystemDictionary_lock because of rank ordering) 2158 2159 if (linkage_error) { 2160 ResourceMark rm(THREAD); 2161 const char* class_loader_name = loader_name(class_loader()); 2162 char* type_name = k->name()->as_C_string(); 2163 size_t buflen = strlen(linkage_error) + strlen(class_loader_name) + 2164 strlen(type_name); 2165 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 2166 jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name); 2167 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 2168 } 2169 } 2170 2171 2172 // Update system dictionary - done after check_constraint and add_to_hierachy 2173 // have been called. 2174 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash, 2175 int p_index, unsigned int p_hash, 2176 instanceKlassHandle k, 2177 Handle class_loader, 2178 TRAPS) { 2179 // Compile_lock prevents systemDictionary updates during compilations 2180 assert_locked_or_safepoint(Compile_lock); 2181 Symbol* name = k->name(); 2182 2183 { 2184 MutexLocker mu1(SystemDictionary_lock, THREAD); 2185 2186 // See whether biased locking is enabled and if so set it for this 2187 // klass. 2188 // Note that this must be done past the last potential blocking 2189 // point / safepoint. We enable biased locking lazily using a 2190 // VM_Operation to iterate the SystemDictionary and installing the 2191 // biasable mark word into each instanceKlass's prototype header. 2192 // To avoid race conditions where we accidentally miss enabling the 2193 // optimization for one class in the process of being added to the 2194 // dictionary, we must not safepoint after the test of 2195 // BiasedLocking::enabled(). 2196 if (UseBiasedLocking && BiasedLocking::enabled()) { 2197 // Set biased locking bit for all loaded classes; it will be 2198 // cleared if revocation occurs too often for this type 2199 // NOTE that we must only do this when the class is initally 2200 // defined, not each time it is referenced from a new class loader 2201 if (k->class_loader() == class_loader()) { 2202 k->set_prototype_header(markOopDesc::biased_locking_prototype()); 2203 } 2204 } 2205 2206 // Check for a placeholder. If there, remove it and make a 2207 // new system dictionary entry. 2208 placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD); 2209 klassOop sd_check = find_class(d_index, d_hash, name, class_loader); 2210 if (sd_check == NULL) { 2211 dictionary()->add_klass(name, class_loader, k); 2212 notice_modification(); 2213 } 2214 #ifdef ASSERT 2215 sd_check = find_class(d_index, d_hash, name, class_loader); 2216 assert (sd_check != NULL, "should have entry in system dictionary"); 2217 // Changed to allow PH to remain to complete class circularity checking 2218 // while only one thread can define a class at one time, multiple 2219 // classes can resolve the superclass for a class at one time, 2220 // and the placeholder is used to track that 2221 // Symbol* ph_check = find_placeholder(name, class_loader); 2222 // assert (ph_check == NULL, "should not have a placeholder entry"); 2223 #endif 2224 SystemDictionary_lock->notify_all(); 2225 } 2226 } 2227 2228 2229 // Try to find a class name using the loader constraints. The 2230 // loader constraints might know about a class that isn't fully loaded 2231 // yet and these will be ignored. 2232 klassOop SystemDictionary::find_constrained_instance_or_array_klass( 2233 Symbol* class_name, Handle class_loader, TRAPS) { 2234 2235 // First see if it has been loaded directly. 2236 // Force the protection domain to be null. (This removes protection checks.) 2237 Handle no_protection_domain; 2238 klassOop klass = find_instance_or_array_klass(class_name, class_loader, 2239 no_protection_domain, CHECK_NULL); 2240 if (klass != NULL) 2241 return klass; 2242 2243 // Now look to see if it has been loaded elsewhere, and is subject to 2244 // a loader constraint that would require this loader to return the 2245 // klass that is already loaded. 2246 if (FieldType::is_array(class_name)) { 2247 // For array classes, their klassOops are not kept in the 2248 // constraint table. The element klassOops are. 2249 FieldArrayInfo fd; 2250 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL)); 2251 if (t != T_OBJECT) { 2252 klass = Universe::typeArrayKlassObj(t); 2253 } else { 2254 MutexLocker mu(SystemDictionary_lock, THREAD); 2255 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader); 2256 } 2257 // If element class already loaded, allocate array klass 2258 if (klass != NULL) { 2259 klass = Klass::cast(klass)->array_klass_or_null(fd.dimension()); 2260 } 2261 } else { 2262 MutexLocker mu(SystemDictionary_lock, THREAD); 2263 // Non-array classes are easy: simply check the constraint table. 2264 klass = constraints()->find_constrained_klass(class_name, class_loader); 2265 } 2266 2267 return klass; 2268 } 2269 2270 2271 bool SystemDictionary::add_loader_constraint(Symbol* class_name, 2272 Handle class_loader1, 2273 Handle class_loader2, 2274 Thread* THREAD) { 2275 Symbol* constraint_name = NULL; 2276 if (!FieldType::is_array(class_name)) { 2277 constraint_name = class_name; 2278 } else { 2279 // For array classes, their klassOops are not kept in the 2280 // constraint table. The element classes are. 2281 FieldArrayInfo fd; 2282 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false)); 2283 // primitive types always pass 2284 if (t != T_OBJECT) { 2285 return true; 2286 } else { 2287 constraint_name = fd.object_key(); 2288 } 2289 } 2290 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, class_loader1); 2291 int d_index1 = dictionary()->hash_to_index(d_hash1); 2292 2293 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, class_loader2); 2294 int d_index2 = dictionary()->hash_to_index(d_hash2); 2295 { 2296 MutexLocker mu_s(SystemDictionary_lock, THREAD); 2297 2298 // Better never do a GC while we're holding these oops 2299 No_Safepoint_Verifier nosafepoint; 2300 2301 klassOop klass1 = find_class(d_index1, d_hash1, constraint_name, class_loader1); 2302 klassOop klass2 = find_class(d_index2, d_hash2, constraint_name, class_loader2); 2303 return constraints()->add_entry(constraint_name, klass1, class_loader1, 2304 klass2, class_loader2); 2305 } 2306 } 2307 2308 // Add entry to resolution error table to record the error when the first 2309 // attempt to resolve a reference to a class has failed. 2310 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) { 2311 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2312 int index = resolution_errors()->hash_to_index(hash); 2313 { 2314 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2315 resolution_errors()->add_entry(index, hash, pool, which, error); 2316 } 2317 } 2318 2319 // Lookup resolution error table. Returns error if found, otherwise NULL. 2320 Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) { 2321 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2322 int index = resolution_errors()->hash_to_index(hash); 2323 { 2324 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2325 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which); 2326 return (entry != NULL) ? entry->error() : (Symbol*)NULL; 2327 } 2328 } 2329 2330 2331 // Signature constraints ensure that callers and callees agree about 2332 // the meaning of type names in their signatures. This routine is the 2333 // intake for constraints. It collects them from several places: 2334 // 2335 // * LinkResolver::resolve_method (if check_access is true) requires 2336 // that the resolving class (the caller) and the defining class of 2337 // the resolved method (the callee) agree on each type in the 2338 // method's signature. 2339 // 2340 // * LinkResolver::resolve_interface_method performs exactly the same 2341 // checks. 2342 // 2343 // * LinkResolver::resolve_field requires that the constant pool 2344 // attempting to link to a field agree with the field's defining 2345 // class about the type of the field signature. 2346 // 2347 // * klassVtable::initialize_vtable requires that, when a class 2348 // overrides a vtable entry allocated by a superclass, that the 2349 // overriding method (i.e., the callee) agree with the superclass 2350 // on each type in the method's signature. 2351 // 2352 // * klassItable::initialize_itable requires that, when a class fills 2353 // in its itables, for each non-abstract method installed in an 2354 // itable, the method (i.e., the callee) agree with the interface 2355 // on each type in the method's signature. 2356 // 2357 // All those methods have a boolean (check_access, checkconstraints) 2358 // which turns off the checks. This is used from specialized contexts 2359 // such as bootstrapping, dumping, and debugging. 2360 // 2361 // No direct constraint is placed between the class and its 2362 // supertypes. Constraints are only placed along linked relations 2363 // between callers and callees. When a method overrides or implements 2364 // an abstract method in a supertype (superclass or interface), the 2365 // constraints are placed as if the supertype were the caller to the 2366 // overriding method. (This works well, since callers to the 2367 // supertype have already established agreement between themselves and 2368 // the supertype.) As a result of all this, a class can disagree with 2369 // its supertype about the meaning of a type name, as long as that 2370 // class neither calls a relevant method of the supertype, nor is 2371 // called (perhaps via an override) from the supertype. 2372 // 2373 // 2374 // SystemDictionary::check_signature_loaders(sig, l1, l2) 2375 // 2376 // Make sure all class components (including arrays) in the given 2377 // signature will be resolved to the same class in both loaders. 2378 // Returns the name of the type that failed a loader constraint check, or 2379 // NULL if no constraint failed. The returned C string needs cleaning up 2380 // with a ResourceMark in the caller. No exception except OOME is thrown. 2381 // Arrays are not added to the loader constraint table, their elements are. 2382 char* SystemDictionary::check_signature_loaders(Symbol* signature, 2383 Handle loader1, Handle loader2, 2384 bool is_method, TRAPS) { 2385 // Nothing to do if loaders are the same. 2386 if (loader1() == loader2()) { 2387 return NULL; 2388 } 2389 2390 ResourceMark rm(THREAD); 2391 SignatureStream sig_strm(signature, is_method); 2392 while (!sig_strm.is_done()) { 2393 if (sig_strm.is_object()) { 2394 Symbol* s = sig_strm.as_symbol(CHECK_NULL); 2395 Symbol* sig = s; 2396 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) { 2397 return sig->as_C_string(); 2398 } 2399 } 2400 sig_strm.next(); 2401 } 2402 return NULL; 2403 } 2404 2405 2406 methodOop SystemDictionary::find_method_handle_invoke(Symbol* name, 2407 Symbol* signature, 2408 KlassHandle accessing_klass, 2409 TRAPS) { 2410 if (!EnableMethodHandles) return NULL; 2411 vmSymbols::SID name_id = vmSymbols::find_sid(name); 2412 assert(name_id != vmSymbols::NO_SID, "must be a known name"); 2413 unsigned int hash = invoke_method_table()->compute_hash(signature, name_id); 2414 int index = invoke_method_table()->hash_to_index(hash); 2415 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, name_id); 2416 methodHandle non_cached_result; 2417 if (spe == NULL || spe->property_oop() == NULL) { 2418 spe = NULL; 2419 // Must create lots of stuff here, but outside of the SystemDictionary lock. 2420 if (THREAD->is_Compiler_thread()) 2421 return NULL; // do not attempt from within compiler 2422 bool for_invokeGeneric = (name_id == vmSymbols::VM_SYMBOL_ENUM_NAME(invokeGeneric_name)); 2423 if (AllowInvokeForInvokeGeneric && name_id == vmSymbols::VM_SYMBOL_ENUM_NAME(invoke_name)) 2424 for_invokeGeneric = true; 2425 bool found_on_bcp = false; 2426 Handle mt = find_method_handle_type(signature, accessing_klass, 2427 for_invokeGeneric, 2428 found_on_bcp, CHECK_NULL); 2429 KlassHandle mh_klass = SystemDictionaryHandles::MethodHandle_klass(); 2430 methodHandle m = methodOopDesc::make_invoke_method(mh_klass, name, signature, 2431 mt, CHECK_NULL); 2432 // Now grab the lock. We might have to throw away the new method, 2433 // if a racing thread has managed to install one at the same time. 2434 if (found_on_bcp) { 2435 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2436 spe = invoke_method_table()->find_entry(index, hash, signature, name_id); 2437 if (spe == NULL) 2438 spe = invoke_method_table()->add_entry(index, hash, signature, name_id); 2439 if (spe->property_oop() == NULL) 2440 spe->set_property_oop(m()); 2441 } else { 2442 non_cached_result = m; 2443 } 2444 } 2445 if (spe != NULL && spe->property_oop() != NULL) { 2446 assert(spe->property_oop()->is_method(), ""); 2447 return (methodOop) spe->property_oop(); 2448 } else { 2449 return non_cached_result(); 2450 } 2451 } 2452 2453 // Ask Java code to find or construct a java.dyn.MethodType for the given 2454 // signature, as interpreted relative to the given class loader. 2455 // Because of class loader constraints, all method handle usage must be 2456 // consistent with this loader. 2457 Handle SystemDictionary::find_method_handle_type(Symbol* signature, 2458 KlassHandle accessing_klass, 2459 bool for_invokeGeneric, 2460 bool& return_bcp_flag, 2461 TRAPS) { 2462 Handle class_loader, protection_domain; 2463 bool is_on_bcp = true; // keep this true as long as we can materialize from the boot classloader 2464 Handle empty; 2465 int npts = ArgumentCount(signature).size(); 2466 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty)); 2467 int arg = 0; 2468 Handle rt; // the return type from the signature 2469 ResourceMark rm(THREAD); 2470 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) { 2471 oop mirror = NULL; 2472 if (is_on_bcp) { 2473 mirror = ss.as_java_mirror(class_loader, protection_domain, 2474 SignatureStream::ReturnNull, CHECK_(empty)); 2475 if (mirror == NULL) { 2476 // fall back from BCP to accessing_klass 2477 if (accessing_klass.not_null()) { 2478 class_loader = Handle(THREAD, instanceKlass::cast(accessing_klass())->class_loader()); 2479 protection_domain = Handle(THREAD, instanceKlass::cast(accessing_klass())->protection_domain()); 2480 } 2481 is_on_bcp = false; 2482 } 2483 } 2484 if (!is_on_bcp) { 2485 // Resolve, throwing a real error if it doesn't work. 2486 mirror = ss.as_java_mirror(class_loader, protection_domain, 2487 SignatureStream::NCDFError, CHECK_(empty)); 2488 } 2489 if (ss.at_return_type()) 2490 rt = Handle(THREAD, mirror); 2491 else 2492 pts->obj_at_put(arg++, mirror); 2493 // Check accessibility. 2494 if (ss.is_object() && accessing_klass.not_null()) { 2495 klassOop sel_klass = java_lang_Class::as_klassOop(mirror); 2496 // Emulate constantPoolOopDesc::verify_constant_pool_resolve. 2497 if (Klass::cast(sel_klass)->oop_is_objArray()) 2498 sel_klass = objArrayKlass::cast(sel_klass)->bottom_klass(); 2499 if (Klass::cast(sel_klass)->oop_is_instance()) { 2500 KlassHandle sel_kh(THREAD, sel_klass); 2501 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty)); 2502 } 2503 } 2504 } 2505 assert(arg == npts, ""); 2506 2507 // call sun.dyn.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType 2508 JavaCallArguments args(Handle(THREAD, rt())); 2509 args.push_oop(pts()); 2510 JavaValue result(T_OBJECT); 2511 JavaCalls::call_static(&result, 2512 SystemDictionary::MethodHandleNatives_klass(), 2513 vmSymbols::findMethodHandleType_name(), 2514 vmSymbols::findMethodHandleType_signature(), 2515 &args, CHECK_(empty)); 2516 Handle method_type(THREAD, (oop) result.get_jobject()); 2517 2518 if (for_invokeGeneric) { 2519 // call sun.dyn.MethodHandleNatives::notifyGenericMethodType(MethodType) -> void 2520 JavaCallArguments args(Handle(THREAD, method_type())); 2521 JavaValue no_result(T_VOID); 2522 JavaCalls::call_static(&no_result, 2523 SystemDictionary::MethodHandleNatives_klass(), 2524 vmSymbols::notifyGenericMethodType_name(), 2525 vmSymbols::notifyGenericMethodType_signature(), 2526 &args, THREAD); 2527 if (HAS_PENDING_EXCEPTION) { 2528 // If the notification fails, just kill it. 2529 CLEAR_PENDING_EXCEPTION; 2530 } 2531 } 2532 2533 // report back to the caller with the MethodType and the "on_bcp" flag 2534 return_bcp_flag = is_on_bcp; 2535 return method_type; 2536 } 2537 2538 // Ask Java code to find or construct a method handle constant. 2539 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller, 2540 int ref_kind, //e.g., JVM_REF_invokeVirtual 2541 KlassHandle callee, 2542 Symbol* name_sym, 2543 Symbol* signature, 2544 TRAPS) { 2545 Handle empty; 2546 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty)); 2547 Handle type; 2548 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') { 2549 bool ignore_is_on_bcp = false; 2550 type = find_method_handle_type(signature, caller, false, ignore_is_on_bcp, CHECK_(empty)); 2551 } else { 2552 ResourceMark rm(THREAD); 2553 SignatureStream ss(signature, false); 2554 if (!ss.is_done()) { 2555 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(), 2556 SignatureStream::NCDFError, CHECK_(empty)); 2557 type = Handle(THREAD, mirror); 2558 ss.next(); 2559 if (!ss.is_done()) type = Handle(); // error! 2560 } 2561 } 2562 if (type.is_null()) { 2563 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty); 2564 } 2565 2566 // call sun.dyn.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle 2567 JavaCallArguments args; 2568 args.push_oop(caller->java_mirror()); // the referring class 2569 args.push_int(ref_kind); 2570 args.push_oop(callee->java_mirror()); // the target class 2571 args.push_oop(name()); 2572 args.push_oop(type()); 2573 JavaValue result(T_OBJECT); 2574 JavaCalls::call_static(&result, 2575 SystemDictionary::MethodHandleNatives_klass(), 2576 vmSymbols::linkMethodHandleConstant_name(), 2577 vmSymbols::linkMethodHandleConstant_signature(), 2578 &args, CHECK_(empty)); 2579 return Handle(THREAD, (oop) result.get_jobject()); 2580 } 2581 2582 // Ask Java code to find or construct a java.dyn.CallSite for the given 2583 // name and signature, as interpreted relative to the given class loader. 2584 Handle SystemDictionary::make_dynamic_call_site(Handle bootstrap_method, 2585 Symbol* name, 2586 methodHandle signature_invoker, 2587 Handle info, 2588 methodHandle caller_method, 2589 int caller_bci, 2590 TRAPS) { 2591 Handle empty; 2592 guarantee(bootstrap_method.not_null() && 2593 java_dyn_MethodHandle::is_instance(bootstrap_method()), 2594 "caller must supply a valid BSM"); 2595 2596 Handle caller_mname = MethodHandles::new_MemberName(CHECK_(empty)); 2597 MethodHandles::init_MemberName(caller_mname(), caller_method()); 2598 2599 // call sun.dyn.MethodHandleNatives::makeDynamicCallSite(bootm, name, mtype, info, caller_mname, caller_pos) 2600 oop name_str_oop = StringTable::intern(name, CHECK_(empty)); // not a handle! 2601 JavaCallArguments args(Handle(THREAD, bootstrap_method())); 2602 args.push_oop(name_str_oop); 2603 args.push_oop(signature_invoker->method_handle_type()); 2604 args.push_oop(info()); 2605 args.push_oop(caller_mname()); 2606 args.push_int(caller_bci); 2607 JavaValue result(T_OBJECT); 2608 Symbol* makeDynamicCallSite_signature = vmSymbols::makeDynamicCallSite_signature(); 2609 if (AllowTransitionalJSR292 && SystemDictionaryHandles::MethodHandleNatives_klass()->name() == vmSymbols::sun_dyn_MethodHandleNatives()) { 2610 makeDynamicCallSite_signature = vmSymbols::makeDynamicCallSite_TRANS_signature(); 2611 } 2612 JavaCalls::call_static(&result, 2613 SystemDictionary::MethodHandleNatives_klass(), 2614 vmSymbols::makeDynamicCallSite_name(), 2615 makeDynamicCallSite_signature, 2616 &args, CHECK_(empty)); 2617 oop call_site_oop = (oop) result.get_jobject(); 2618 assert(call_site_oop->is_oop() 2619 /*&& java_dyn_CallSite::is_instance(call_site_oop)*/, "must be sane"); 2620 if (TraceMethodHandles) { 2621 #ifndef PRODUCT 2622 tty->print_cr("Linked invokedynamic bci=%d site="INTPTR_FORMAT":", caller_bci, call_site_oop); 2623 call_site_oop->print(); 2624 tty->cr(); 2625 #endif //PRODUCT 2626 } 2627 return call_site_oop; 2628 } 2629 2630 Handle SystemDictionary::find_bootstrap_method(methodHandle caller_method, int caller_bci, 2631 int cache_index, 2632 Handle& argument_info_result, 2633 TRAPS) { 2634 Handle empty; 2635 2636 constantPoolHandle pool; 2637 { 2638 klassOop caller = caller_method->method_holder(); 2639 if (!Klass::cast(caller)->oop_is_instance()) return empty; 2640 pool = constantPoolHandle(THREAD, instanceKlass::cast(caller)->constants()); 2641 } 2642 2643 int constant_pool_index = pool->cache()->entry_at(cache_index)->constant_pool_index(); 2644 constantTag tag = pool->tag_at(constant_pool_index); 2645 2646 if (tag.is_invoke_dynamic()) { 2647 // JVM_CONSTANT_InvokeDynamic is an ordered pair of [bootm, name&type], plus optional arguments 2648 // The bootm, being a JVM_CONSTANT_MethodHandle, has its own cache entry. 2649 int bsm_index = pool->invoke_dynamic_bootstrap_method_ref_index_at(constant_pool_index); 2650 if (bsm_index != 0) { 2651 int bsm_index_in_cache = pool->cache()->entry_at(cache_index)->bootstrap_method_index_in_cache(); 2652 DEBUG_ONLY(int bsm_index_2 = pool->cache()->entry_at(bsm_index_in_cache)->constant_pool_index()); 2653 assert(bsm_index == bsm_index_2, "BSM constant lifted to cache"); 2654 if (TraceMethodHandles) { 2655 tty->print_cr("resolving bootstrap method for "PTR_FORMAT" at %d at cache[%d]CP[%d]...", 2656 (intptr_t) caller_method(), caller_bci, cache_index, constant_pool_index); 2657 } 2658 oop bsm_oop = pool->resolve_cached_constant_at(bsm_index_in_cache, CHECK_(empty)); 2659 if (TraceMethodHandles) { 2660 tty->print_cr("bootstrap method for "PTR_FORMAT" at %d retrieved as "PTR_FORMAT":", 2661 (intptr_t) caller_method(), caller_bci, (intptr_t) bsm_oop); 2662 } 2663 assert(bsm_oop->is_oop(), "must be sane"); 2664 // caller must verify that it is of type MethodHandle 2665 Handle bsm(THREAD, bsm_oop); 2666 bsm_oop = NULL; // safety 2667 2668 // Extract the optional static arguments. 2669 Handle argument_info; // either null, or one arg, or Object[]{arg...} 2670 int argc = pool->invoke_dynamic_argument_count_at(constant_pool_index); 2671 if (TraceInvokeDynamic) { 2672 tty->print_cr("find_bootstrap_method: [%d/%d] CONSTANT_InvokeDynamic: %d[%d]", 2673 constant_pool_index, cache_index, bsm_index, argc); 2674 } 2675 if (argc > 0) { 2676 objArrayHandle arg_array; 2677 if (argc > 1) { 2678 objArrayOop arg_array_oop = oopFactory::new_objArray(SystemDictionary::Object_klass(), argc, CHECK_(empty)); 2679 arg_array = objArrayHandle(THREAD, arg_array_oop); 2680 argument_info = arg_array; 2681 } 2682 for (int arg_i = 0; arg_i < argc; arg_i++) { 2683 int arg_index = pool->invoke_dynamic_argument_index_at(constant_pool_index, arg_i); 2684 oop arg_oop = pool->resolve_possibly_cached_constant_at(arg_index, CHECK_(empty)); 2685 if (arg_array.is_null()) { 2686 argument_info = Handle(THREAD, arg_oop); 2687 } else { 2688 arg_array->obj_at_put(arg_i, arg_oop); 2689 } 2690 } 2691 } 2692 2693 argument_info_result = argument_info; // return argument_info to caller 2694 return bsm; 2695 } 2696 // else null BSM; fall through 2697 } else if (tag.is_name_and_type()) { 2698 // JSR 292 EDR does not have JVM_CONSTANT_InvokeDynamic 2699 // a bare name&type defaults its BSM to null, so fall through... 2700 } else { 2701 ShouldNotReachHere(); // verifier does not allow this 2702 } 2703 2704 // Fall through to pick up the per-class bootstrap method. 2705 // This mechanism may go away in the PFD. 2706 assert(AllowTransitionalJSR292, "else the verifier should have stopped us already"); 2707 argument_info_result = empty; // return no argument_info to caller 2708 oop bsm_oop = instanceKlass::cast(caller_method->method_holder())->bootstrap_method(); 2709 if (bsm_oop != NULL) { 2710 if (TraceMethodHandles) { 2711 tty->print_cr("bootstrap method for "PTR_FORMAT" registered as "PTR_FORMAT":", 2712 (intptr_t) caller_method(), (intptr_t) bsm_oop); 2713 } 2714 assert(bsm_oop->is_oop(), "must be sane"); 2715 return Handle(THREAD, bsm_oop); 2716 } 2717 2718 return empty; 2719 } 2720 2721 // Since the identity hash code for symbols changes when the symbols are 2722 // moved from the regular perm gen (hash in the mark word) to the shared 2723 // spaces (hash is the address), the classes loaded into the dictionary 2724 // may be in the wrong buckets. 2725 2726 void SystemDictionary::reorder_dictionary() { 2727 dictionary()->reorder_dictionary(); 2728 } 2729 2730 2731 void SystemDictionary::copy_buckets(char** top, char* end) { 2732 dictionary()->copy_buckets(top, end); 2733 } 2734 2735 2736 void SystemDictionary::copy_table(char** top, char* end) { 2737 dictionary()->copy_table(top, end); 2738 } 2739 2740 2741 void SystemDictionary::reverse() { 2742 dictionary()->reverse(); 2743 } 2744 2745 int SystemDictionary::number_of_classes() { 2746 return dictionary()->number_of_entries(); 2747 } 2748 2749 2750 // ---------------------------------------------------------------------------- 2751 #ifndef PRODUCT 2752 2753 void SystemDictionary::print() { 2754 dictionary()->print(); 2755 2756 // Placeholders 2757 GCMutexLocker mu(SystemDictionary_lock); 2758 placeholders()->print(); 2759 2760 // loader constraints - print under SD_lock 2761 constraints()->print(); 2762 } 2763 2764 #endif 2765 2766 void SystemDictionary::verify() { 2767 guarantee(dictionary() != NULL, "Verify of system dictionary failed"); 2768 guarantee(constraints() != NULL, 2769 "Verify of loader constraints failed"); 2770 guarantee(dictionary()->number_of_entries() >= 0 && 2771 placeholders()->number_of_entries() >= 0, 2772 "Verify of system dictionary failed"); 2773 2774 // Verify dictionary 2775 dictionary()->verify(); 2776 2777 GCMutexLocker mu(SystemDictionary_lock); 2778 placeholders()->verify(); 2779 2780 // Verify constraint table 2781 guarantee(constraints() != NULL, "Verify of loader constraints failed"); 2782 constraints()->verify(dictionary(), placeholders()); 2783 } 2784 2785 2786 void SystemDictionary::verify_obj_klass_present(Handle obj, 2787 Symbol* class_name, 2788 Handle class_loader) { 2789 GCMutexLocker mu(SystemDictionary_lock); 2790 Symbol* name; 2791 2792 klassOop probe = find_class(class_name, class_loader); 2793 if (probe == NULL) { 2794 probe = SystemDictionary::find_shared_class(class_name); 2795 if (probe == NULL) { 2796 name = find_placeholder(class_name, class_loader); 2797 } 2798 } 2799 guarantee(probe != NULL || name != NULL, 2800 "Loaded klasses should be in SystemDictionary"); 2801 } 2802 2803 #ifndef PRODUCT 2804 2805 // statistics code 2806 class ClassStatistics: AllStatic { 2807 private: 2808 static int nclasses; // number of classes 2809 static int nmethods; // number of methods 2810 static int nmethoddata; // number of methodData 2811 static int class_size; // size of class objects in words 2812 static int method_size; // size of method objects in words 2813 static int debug_size; // size of debug info in methods 2814 static int methoddata_size; // size of methodData objects in words 2815 2816 static void do_class(klassOop k) { 2817 nclasses++; 2818 class_size += k->size(); 2819 if (k->klass_part()->oop_is_instance()) { 2820 instanceKlass* ik = (instanceKlass*)k->klass_part(); 2821 class_size += ik->methods()->size(); 2822 class_size += ik->constants()->size(); 2823 class_size += ik->local_interfaces()->size(); 2824 class_size += ik->transitive_interfaces()->size(); 2825 // We do not have to count implementors, since we only store one! 2826 class_size += ik->fields()->size(); 2827 } 2828 } 2829 2830 static void do_method(methodOop m) { 2831 nmethods++; 2832 method_size += m->size(); 2833 // class loader uses same objArray for empty vectors, so don't count these 2834 if (m->exception_table()->length() != 0) method_size += m->exception_table()->size(); 2835 if (m->has_stackmap_table()) { 2836 method_size += m->stackmap_data()->size(); 2837 } 2838 2839 methodDataOop mdo = m->method_data(); 2840 if (mdo != NULL) { 2841 nmethoddata++; 2842 methoddata_size += mdo->size(); 2843 } 2844 } 2845 2846 public: 2847 static void print() { 2848 SystemDictionary::classes_do(do_class); 2849 SystemDictionary::methods_do(do_method); 2850 tty->print_cr("Class statistics:"); 2851 tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize); 2852 tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods, 2853 (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize); 2854 tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize); 2855 } 2856 }; 2857 2858 2859 int ClassStatistics::nclasses = 0; 2860 int ClassStatistics::nmethods = 0; 2861 int ClassStatistics::nmethoddata = 0; 2862 int ClassStatistics::class_size = 0; 2863 int ClassStatistics::method_size = 0; 2864 int ClassStatistics::debug_size = 0; 2865 int ClassStatistics::methoddata_size = 0; 2866 2867 void SystemDictionary::print_class_statistics() { 2868 ResourceMark rm; 2869 ClassStatistics::print(); 2870 } 2871 2872 2873 class MethodStatistics: AllStatic { 2874 public: 2875 enum { 2876 max_parameter_size = 10 2877 }; 2878 private: 2879 2880 static int _number_of_methods; 2881 static int _number_of_final_methods; 2882 static int _number_of_static_methods; 2883 static int _number_of_native_methods; 2884 static int _number_of_synchronized_methods; 2885 static int _number_of_profiled_methods; 2886 static int _number_of_bytecodes; 2887 static int _parameter_size_profile[max_parameter_size]; 2888 static int _bytecodes_profile[Bytecodes::number_of_java_codes]; 2889 2890 static void initialize() { 2891 _number_of_methods = 0; 2892 _number_of_final_methods = 0; 2893 _number_of_static_methods = 0; 2894 _number_of_native_methods = 0; 2895 _number_of_synchronized_methods = 0; 2896 _number_of_profiled_methods = 0; 2897 _number_of_bytecodes = 0; 2898 for (int i = 0; i < max_parameter_size ; i++) _parameter_size_profile[i] = 0; 2899 for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile [j] = 0; 2900 }; 2901 2902 static void do_method(methodOop m) { 2903 _number_of_methods++; 2904 // collect flag info 2905 if (m->is_final() ) _number_of_final_methods++; 2906 if (m->is_static() ) _number_of_static_methods++; 2907 if (m->is_native() ) _number_of_native_methods++; 2908 if (m->is_synchronized()) _number_of_synchronized_methods++; 2909 if (m->method_data() != NULL) _number_of_profiled_methods++; 2910 // collect parameter size info (add one for receiver, if any) 2911 _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++; 2912 // collect bytecodes info 2913 { 2914 Thread *thread = Thread::current(); 2915 HandleMark hm(thread); 2916 BytecodeStream s(methodHandle(thread, m)); 2917 Bytecodes::Code c; 2918 while ((c = s.next()) >= 0) { 2919 _number_of_bytecodes++; 2920 _bytecodes_profile[c]++; 2921 } 2922 } 2923 } 2924 2925 public: 2926 static void print() { 2927 initialize(); 2928 SystemDictionary::methods_do(do_method); 2929 // generate output 2930 tty->cr(); 2931 tty->print_cr("Method statistics (static):"); 2932 // flag distribution 2933 tty->cr(); 2934 tty->print_cr("%6d final methods %6.1f%%", _number_of_final_methods , _number_of_final_methods * 100.0F / _number_of_methods); 2935 tty->print_cr("%6d static methods %6.1f%%", _number_of_static_methods , _number_of_static_methods * 100.0F / _number_of_methods); 2936 tty->print_cr("%6d native methods %6.1f%%", _number_of_native_methods , _number_of_native_methods * 100.0F / _number_of_methods); 2937 tty->print_cr("%6d synchronized methods %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods); 2938 tty->print_cr("%6d profiled methods %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods); 2939 // parameter size profile 2940 tty->cr(); 2941 { int tot = 0; 2942 int avg = 0; 2943 for (int i = 0; i < max_parameter_size; i++) { 2944 int n = _parameter_size_profile[i]; 2945 tot += n; 2946 avg += n*i; 2947 tty->print_cr("parameter size = %1d: %6d methods %5.1f%%", i, n, n * 100.0F / _number_of_methods); 2948 } 2949 assert(tot == _number_of_methods, "should be the same"); 2950 tty->print_cr(" %6d methods 100.0%%", _number_of_methods); 2951 tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods); 2952 } 2953 // bytecodes profile 2954 tty->cr(); 2955 { int tot = 0; 2956 for (int i = 0; i < Bytecodes::number_of_java_codes; i++) { 2957 if (Bytecodes::is_defined(i)) { 2958 Bytecodes::Code c = Bytecodes::cast(i); 2959 int n = _bytecodes_profile[c]; 2960 tot += n; 2961 tty->print_cr("%9d %7.3f%% %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c)); 2962 } 2963 } 2964 assert(tot == _number_of_bytecodes, "should be the same"); 2965 tty->print_cr("%9d 100.000%%", _number_of_bytecodes); 2966 } 2967 tty->cr(); 2968 } 2969 }; 2970 2971 int MethodStatistics::_number_of_methods; 2972 int MethodStatistics::_number_of_final_methods; 2973 int MethodStatistics::_number_of_static_methods; 2974 int MethodStatistics::_number_of_native_methods; 2975 int MethodStatistics::_number_of_synchronized_methods; 2976 int MethodStatistics::_number_of_profiled_methods; 2977 int MethodStatistics::_number_of_bytecodes; 2978 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size]; 2979 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes]; 2980 2981 2982 void SystemDictionary::print_method_statistics() { 2983 MethodStatistics::print(); 2984 } 2985 2986 #endif // PRODUCT