systemDictionary.cpp revision 4405:cd3089a56438
1/* 2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25#include "precompiled.hpp" 26#include "classfile/classLoaderData.inline.hpp" 27#include "classfile/dictionary.hpp" 28#include "classfile/javaClasses.hpp" 29#include "classfile/loaderConstraints.hpp" 30#include "classfile/placeholders.hpp" 31#include "classfile/resolutionErrors.hpp" 32#include "classfile/systemDictionary.hpp" 33#include "classfile/vmSymbols.hpp" 34#include "compiler/compileBroker.hpp" 35#include "interpreter/bytecodeStream.hpp" 36#include "interpreter/interpreter.hpp" 37#include "memory/gcLocker.hpp" 38#include "memory/oopFactory.hpp" 39#include "oops/instanceKlass.hpp" 40#include "oops/instanceRefKlass.hpp" 41#include "oops/klass.inline.hpp" 42#include "oops/methodData.hpp" 43#include "oops/objArrayKlass.hpp" 44#include "oops/oop.inline.hpp" 45#include "oops/oop.inline2.hpp" 46#include "oops/typeArrayKlass.hpp" 47#include "prims/jvmtiEnvBase.hpp" 48#include "prims/methodHandles.hpp" 49#include "runtime/biasedLocking.hpp" 50#include "runtime/fieldType.hpp" 51#include "runtime/handles.inline.hpp" 52#include "runtime/java.hpp" 53#include "runtime/javaCalls.hpp" 54#include "runtime/mutexLocker.hpp" 55#include "runtime/signature.hpp" 56#include "services/classLoadingService.hpp" 57#include "services/threadService.hpp" 58 59 60Dictionary* SystemDictionary::_dictionary = NULL; 61PlaceholderTable* SystemDictionary::_placeholders = NULL; 62Dictionary* SystemDictionary::_shared_dictionary = NULL; 63LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL; 64ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL; 65SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL; 66 67 68int SystemDictionary::_number_of_modifications = 0; 69int SystemDictionary::_sdgeneration = 0; 70const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103, 71 20201,40423,99991}; 72 73oop SystemDictionary::_system_loader_lock_obj = NULL; 74 75Klass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT] 76 = { NULL /*, NULL...*/ }; 77 78Klass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ }; 79 80oop SystemDictionary::_java_system_loader = NULL; 81 82bool SystemDictionary::_has_loadClassInternal = false; 83bool SystemDictionary::_has_checkPackageAccess = false; 84 85// lazily initialized klass variables 86Klass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL; 87 88 89// ---------------------------------------------------------------------------- 90// Java-level SystemLoader 91 92oop SystemDictionary::java_system_loader() { 93 return _java_system_loader; 94} 95 96void SystemDictionary::compute_java_system_loader(TRAPS) { 97 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass)); 98 JavaValue result(T_OBJECT); 99 JavaCalls::call_static(&result, 100 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)), 101 vmSymbols::getSystemClassLoader_name(), 102 vmSymbols::void_classloader_signature(), 103 CHECK); 104 105 _java_system_loader = (oop)result.get_jobject(); 106} 107 108 109ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) { 110 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data(); 111 return ClassLoaderDataGraph::find_or_create(class_loader, CHECK_NULL); 112} 113 114// ---------------------------------------------------------------------------- 115// debugging 116 117#ifdef ASSERT 118 119// return true if class_name contains no '.' (internal format is '/') 120bool SystemDictionary::is_internal_format(Symbol* class_name) { 121 if (class_name != NULL) { 122 ResourceMark rm; 123 char* name = class_name->as_C_string(); 124 return strchr(name, '.') == NULL; 125 } else { 126 return true; 127 } 128} 129 130#endif 131 132// ---------------------------------------------------------------------------- 133// Parallel class loading check 134 135bool SystemDictionary::is_parallelCapable(Handle class_loader) { 136 if (UnsyncloadClass || class_loader.is_null()) return true; 137 if (AlwaysLockClassLoader) return false; 138 return java_lang_ClassLoader::parallelCapable(class_loader()); 139} 140// ---------------------------------------------------------------------------- 141// ParallelDefineClass flag does not apply to bootclass loader 142bool SystemDictionary::is_parallelDefine(Handle class_loader) { 143 if (class_loader.is_null()) return false; 144 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) { 145 return true; 146 } 147 return false; 148} 149// ---------------------------------------------------------------------------- 150// Resolving of classes 151 152// Forwards to resolve_or_null 153 154Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) { 155 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD); 156 if (HAS_PENDING_EXCEPTION || klass == NULL) { 157 KlassHandle k_h(THREAD, klass); 158 // can return a null klass 159 klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD); 160 } 161 return klass; 162} 163 164Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) { 165 if (HAS_PENDING_EXCEPTION) { 166 // If we have a pending exception we forward it to the caller, unless throw_error is true, 167 // in which case we have to check whether the pending exception is a ClassNotFoundException, 168 // and if so convert it to a NoClassDefFoundError 169 // And chain the original ClassNotFoundException 170 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) { 171 ResourceMark rm(THREAD); 172 assert(klass_h() == NULL, "Should not have result with exception pending"); 173 Handle e(THREAD, PENDING_EXCEPTION); 174 CLEAR_PENDING_EXCEPTION; 175 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e); 176 } else { 177 return NULL; 178 } 179 } 180 // Class not found, throw appropriate error or exception depending on value of throw_error 181 if (klass_h() == NULL) { 182 ResourceMark rm(THREAD); 183 if (throw_error) { 184 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string()); 185 } else { 186 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string()); 187 } 188 } 189 return (Klass*)klass_h(); 190} 191 192 193Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, 194 bool throw_error, TRAPS) 195{ 196 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD); 197} 198 199 200// Forwards to resolve_instance_class_or_null 201 202Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) { 203 assert(!THREAD->is_Compiler_thread(), 204 err_msg("can not load classes with compiler thread: class=%s, classloader=%s", 205 class_name->as_C_string(), 206 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string())); 207 if (FieldType::is_array(class_name)) { 208 return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL); 209 } else if (FieldType::is_obj(class_name)) { 210 ResourceMark rm(THREAD); 211 // Ignore wrapping L and ;. 212 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1, 213 class_name->utf8_length() - 2, CHECK_NULL); 214 return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL); 215 } else { 216 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL); 217 } 218} 219 220Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) { 221 return resolve_or_null(class_name, Handle(), Handle(), THREAD); 222} 223 224// Forwards to resolve_instance_class_or_null 225 226Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name, 227 Handle class_loader, 228 Handle protection_domain, 229 TRAPS) { 230 assert(FieldType::is_array(class_name), "must be array"); 231 Klass* k = NULL; 232 FieldArrayInfo fd; 233 // dimension and object_key in FieldArrayInfo are assigned as a side-effect 234 // of this call 235 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL); 236 if (t == T_OBJECT) { 237 // naked oop "k" is OK here -- we assign back into it 238 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(), 239 class_loader, 240 protection_domain, 241 CHECK_NULL); 242 if (k != NULL) { 243 k = k->array_klass(fd.dimension(), CHECK_NULL); 244 } 245 } else { 246 k = Universe::typeArrayKlassObj(t); 247 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL); 248 } 249 return k; 250} 251 252 253// Must be called for any super-class or super-interface resolution 254// during class definition to allow class circularity checking 255// super-interface callers: 256// parse_interfaces - for defineClass & jvmtiRedefineClasses 257// super-class callers: 258// ClassFileParser - for defineClass & jvmtiRedefineClasses 259// load_shared_class - while loading a class from shared archive 260// resolve_instance_class_or_null: 261// via: handle_parallel_super_load 262// when resolving a class that has an existing placeholder with 263// a saved superclass [i.e. a defineClass is currently in progress] 264// if another thread is trying to resolve the class, it must do 265// super-class checks on its own thread to catch class circularity 266// This last call is critical in class circularity checking for cases 267// where classloading is delegated to different threads and the 268// classloader lock is released. 269// Take the case: Base->Super->Base 270// 1. If thread T1 tries to do a defineClass of class Base 271// resolve_super_or_fail creates placeholder: T1, Base (super Super) 272// 2. resolve_instance_class_or_null does not find SD or placeholder for Super 273// so it tries to load Super 274// 3. If we load the class internally, or user classloader uses same thread 275// loadClassFromxxx or defineClass via parseClassFile Super ... 276// 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base) 277// 3.3 resolve_instance_class_or_null Base, finds placeholder for Base 278// 3.4 calls resolve_super_or_fail Base 279// 3.5 finds T1,Base -> throws class circularity 280//OR 4. If T2 tries to resolve Super via defineClass Super ... 281// 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base) 282// 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super) 283// 4.3 calls resolve_super_or_fail Super in parallel on own thread T2 284// 4.4 finds T2, Super -> throws class circularity 285// Must be called, even if superclass is null, since this is 286// where the placeholder entry is created which claims this 287// thread is loading this class/classloader. 288Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name, 289 Symbol* class_name, 290 Handle class_loader, 291 Handle protection_domain, 292 bool is_superclass, 293 TRAPS) { 294 // Double-check, if child class is already loaded, just return super-class,interface 295 // Don't add a placedholder if already loaded, i.e. already in system dictionary 296 // Make sure there's a placeholder for the *child* before resolving. 297 // Used as a claim that this thread is currently loading superclass/classloader 298 // Used here for ClassCircularity checks and also for heap verification 299 // (every InstanceKlass in the heap needs to be in the system dictionary 300 // or have a placeholder). 301 // Must check ClassCircularity before checking if super class is already loaded 302 // 303 // We might not already have a placeholder if this child_name was 304 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass); 305 // the name of the class might not be known until the stream is actually 306 // parsed. 307 // Bugs 4643874, 4715493 308 // compute_hash can have a safepoint 309 310 ClassLoaderData* loader_data = class_loader_data(class_loader); 311 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data); 312 int d_index = dictionary()->hash_to_index(d_hash); 313 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data); 314 int p_index = placeholders()->hash_to_index(p_hash); 315 // can't throw error holding a lock 316 bool child_already_loaded = false; 317 bool throw_circularity_error = false; 318 { 319 MutexLocker mu(SystemDictionary_lock, THREAD); 320 Klass* childk = find_class(d_index, d_hash, child_name, loader_data); 321 Klass* quicksuperk; 322 // to support // loading: if child done loading, just return superclass 323 // if class_name, & class_loader don't match: 324 // if initial define, SD update will give LinkageError 325 // if redefine: compare_class_versions will give HIERARCHY_CHANGED 326 // so we don't throw an exception here. 327 // see: nsk redefclass014 & java.lang.instrument Instrument032 328 if ((childk != NULL ) && (is_superclass) && 329 ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) && 330 331 ((quicksuperk->name() == class_name) && 332 (quicksuperk->class_loader() == class_loader()))) { 333 return quicksuperk; 334 } else { 335 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data); 336 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) { 337 throw_circularity_error = true; 338 } 339 } 340 if (!throw_circularity_error) { 341 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD); 342 } 343 } 344 if (throw_circularity_error) { 345 ResourceMark rm(THREAD); 346 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string()); 347 } 348 349// java.lang.Object should have been found above 350 assert(class_name != NULL, "null super class for resolving"); 351 // Resolve the super class or interface, check results on return 352 Klass* superk = SystemDictionary::resolve_or_null(class_name, 353 class_loader, 354 protection_domain, 355 THREAD); 356 357 KlassHandle superk_h(THREAD, superk); 358 359 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up 360 // It is no longer necessary to keep the placeholder table alive until update_dictionary 361 // or error. GC used to walk the placeholder table as strong roots. 362 // The instanceKlass is kept alive because the class loader is on the stack, 363 // which keeps the loader_data alive, as well as all instanceKlasses in 364 // the loader_data. parseClassFile adds the instanceKlass to loader_data. 365 { 366 MutexLocker mu(SystemDictionary_lock, THREAD); 367 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD); 368 SystemDictionary_lock->notify_all(); 369 } 370 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) { 371 // can null superk 372 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD)); 373 } 374 375 return superk_h(); 376} 377 378void SystemDictionary::validate_protection_domain(instanceKlassHandle klass, 379 Handle class_loader, 380 Handle protection_domain, 381 TRAPS) { 382 if(!has_checkPackageAccess()) return; 383 384 // Now we have to call back to java to check if the initating class has access 385 JavaValue result(T_VOID); 386 if (TraceProtectionDomainVerification) { 387 // Print out trace information 388 tty->print_cr("Checking package access"); 389 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr(); 390 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr(); 391 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr(); 392 } 393 394 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass()); 395 JavaCalls::call_special(&result, 396 class_loader, 397 system_loader, 398 vmSymbols::checkPackageAccess_name(), 399 vmSymbols::class_protectiondomain_signature(), 400 Handle(THREAD, klass->java_mirror()), 401 protection_domain, 402 THREAD); 403 404 if (TraceProtectionDomainVerification) { 405 if (HAS_PENDING_EXCEPTION) { 406 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!"); 407 } else { 408 tty->print_cr(" -> granted"); 409 } 410 tty->cr(); 411 } 412 413 if (HAS_PENDING_EXCEPTION) return; 414 415 // If no exception has been thrown, we have validated the protection domain 416 // Insert the protection domain of the initiating class into the set. 417 { 418 // We recalculate the entry here -- we've called out to java since 419 // the last time it was calculated. 420 ClassLoaderData* loader_data = class_loader_data(class_loader); 421 422 Symbol* kn = klass->name(); 423 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data); 424 int d_index = dictionary()->hash_to_index(d_hash); 425 426 MutexLocker mu(SystemDictionary_lock, THREAD); 427 { 428 // Note that we have an entry, and entries can be deleted only during GC, 429 // so we cannot allow GC to occur while we're holding this entry. 430 431 // We're using a No_Safepoint_Verifier to catch any place where we 432 // might potentially do a GC at all. 433 // Dictionary::do_unloading() asserts that classes in SD are only 434 // unloaded at a safepoint. Anonymous classes are not in SD. 435 No_Safepoint_Verifier nosafepoint; 436 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data, 437 protection_domain, THREAD); 438 } 439 } 440} 441 442// We only get here if this thread finds that another thread 443// has already claimed the placeholder token for the current operation, 444// but that other thread either never owned or gave up the 445// object lock 446// Waits on SystemDictionary_lock to indicate placeholder table updated 447// On return, caller must recheck placeholder table state 448// 449// We only get here if 450// 1) custom classLoader, i.e. not bootstrap classloader 451// 2) UnsyncloadClass not set 452// 3) custom classLoader has broken the class loader objectLock 453// so another thread got here in parallel 454// 455// lockObject must be held. 456// Complicated dance due to lock ordering: 457// Must first release the classloader object lock to 458// allow initial definer to complete the class definition 459// and to avoid deadlock 460// Reclaim classloader lock object with same original recursion count 461// Must release SystemDictionary_lock after notify, since 462// class loader lock must be claimed before SystemDictionary_lock 463// to prevent deadlocks 464// 465// The notify allows applications that did an untimed wait() on 466// the classloader object lock to not hang. 467void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) { 468 assert_lock_strong(SystemDictionary_lock); 469 470 bool calledholdinglock 471 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject); 472 assert(calledholdinglock,"must hold lock for notify"); 473 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait"); 474 ObjectSynchronizer::notifyall(lockObject, THREAD); 475 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD); 476 SystemDictionary_lock->wait(); 477 SystemDictionary_lock->unlock(); 478 ObjectSynchronizer::reenter(lockObject, recursions, THREAD); 479 SystemDictionary_lock->lock(); 480} 481 482// If the class in is in the placeholder table, class loading is in progress 483// For cases where the application changes threads to load classes, it 484// is critical to ClassCircularity detection that we try loading 485// the superclass on the same thread internally, so we do parallel 486// super class loading here. 487// This also is critical in cases where the original thread gets stalled 488// even in non-circularity situations. 489// Note: must call resolve_super_or_fail even if null super - 490// to force placeholder entry creation for this class for circularity detection 491// Caller must check for pending exception 492// Returns non-null Klass* if other thread has completed load 493// and we are done, 494// If return null Klass* and no pending exception, the caller must load the class 495instanceKlassHandle SystemDictionary::handle_parallel_super_load( 496 Symbol* name, Symbol* superclassname, Handle class_loader, 497 Handle protection_domain, Handle lockObject, TRAPS) { 498 499 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 500 ClassLoaderData* loader_data = class_loader_data(class_loader); 501 unsigned int d_hash = dictionary()->compute_hash(name, loader_data); 502 int d_index = dictionary()->hash_to_index(d_hash); 503 unsigned int p_hash = placeholders()->compute_hash(name, loader_data); 504 int p_index = placeholders()->hash_to_index(p_hash); 505 506 // superk is not used, resolve_super called for circularity check only 507 // This code is reached in two situations. One if this thread 508 // is loading the same class twice (e.g. ClassCircularity, or 509 // java.lang.instrument). 510 // The second is if another thread started the resolve_super first 511 // and has not yet finished. 512 // In both cases the original caller will clean up the placeholder 513 // entry on error. 514 Klass* superk = SystemDictionary::resolve_super_or_fail(name, 515 superclassname, 516 class_loader, 517 protection_domain, 518 true, 519 CHECK_(nh)); 520 521 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete 522 // Serial class loaders and bootstrap classloader do wait for superclass loads 523 if (!class_loader.is_null() && is_parallelCapable(class_loader)) { 524 MutexLocker mu(SystemDictionary_lock, THREAD); 525 // Check if classloading completed while we were loading superclass or waiting 526 Klass* check = find_class(d_index, d_hash, name, loader_data); 527 if (check != NULL) { 528 // Klass is already loaded, so just return it 529 return(instanceKlassHandle(THREAD, check)); 530 } else { 531 return nh; 532 } 533 } 534 535 // must loop to both handle other placeholder updates 536 // and spurious notifications 537 bool super_load_in_progress = true; 538 PlaceholderEntry* placeholder; 539 while (super_load_in_progress) { 540 MutexLocker mu(SystemDictionary_lock, THREAD); 541 // Check if classloading completed while we were loading superclass or waiting 542 Klass* check = find_class(d_index, d_hash, name, loader_data); 543 if (check != NULL) { 544 // Klass is already loaded, so just return it 545 return(instanceKlassHandle(THREAD, check)); 546 } else { 547 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 548 if (placeholder && placeholder->super_load_in_progress() ){ 549 // Before UnsyncloadClass: 550 // We only get here if the application has released the 551 // classloader lock when another thread was in the middle of loading a 552 // superclass/superinterface for this class, and now 553 // this thread is also trying to load this class. 554 // To minimize surprises, the first thread that started to 555 // load a class should be the one to complete the loading 556 // with the classfile it initially expected. 557 // This logic has the current thread wait once it has done 558 // all the superclass/superinterface loading it can, until 559 // the original thread completes the class loading or fails 560 // If it completes we will use the resulting InstanceKlass 561 // which we will find below in the systemDictionary. 562 // We also get here for parallel bootstrap classloader 563 if (class_loader.is_null()) { 564 SystemDictionary_lock->wait(); 565 } else { 566 double_lock_wait(lockObject, THREAD); 567 } 568 } else { 569 // If not in SD and not in PH, other thread's load must have failed 570 super_load_in_progress = false; 571 } 572 } 573 } 574 return (nh); 575} 576 577 578Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, Handle class_loader, Handle protection_domain, TRAPS) { 579 assert(name != NULL && !FieldType::is_array(name) && 580 !FieldType::is_obj(name), "invalid class name"); 581 582 // UseNewReflection 583 // Fix for 4474172; see evaluation for more details 584 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 585 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL); 586 587 // Do lookup to see if class already exist and the protection domain 588 // has the right access 589 // This call uses find which checks protection domain already matches 590 // All subsequent calls use find_class, and set has_loaded_class so that 591 // before we return a result we call out to java to check for valid protection domain 592 // to allow returning the Klass* and add it to the pd_set if it is valid 593 unsigned int d_hash = dictionary()->compute_hash(name, loader_data); 594 int d_index = dictionary()->hash_to_index(d_hash); 595 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data, 596 protection_domain, THREAD); 597 if (probe != NULL) return probe; 598 599 600 // Non-bootstrap class loaders will call out to class loader and 601 // define via jvm/jni_DefineClass which will acquire the 602 // class loader object lock to protect against multiple threads 603 // defining the class in parallel by accident. 604 // This lock must be acquired here so the waiter will find 605 // any successful result in the SystemDictionary and not attempt 606 // the define 607 // ParallelCapable Classloaders and the bootstrap classloader, 608 // or all classloaders with UnsyncloadClass do not acquire lock here 609 bool DoObjectLock = true; 610 if (is_parallelCapable(class_loader)) { 611 DoObjectLock = false; 612 } 613 614 unsigned int p_hash = placeholders()->compute_hash(name, loader_data); 615 int p_index = placeholders()->hash_to_index(p_hash); 616 617 // Class is not in SystemDictionary so we have to do loading. 618 // Make sure we are synchronized on the class loader before we proceed 619 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 620 check_loader_lock_contention(lockObject, THREAD); 621 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 622 623 // Check again (after locking) if class already exist in SystemDictionary 624 bool class_has_been_loaded = false; 625 bool super_load_in_progress = false; 626 bool havesupername = false; 627 instanceKlassHandle k; 628 PlaceholderEntry* placeholder; 629 Symbol* superclassname = NULL; 630 631 { 632 MutexLocker mu(SystemDictionary_lock, THREAD); 633 Klass* check = find_class(d_index, d_hash, name, loader_data); 634 if (check != NULL) { 635 // Klass is already loaded, so just return it 636 class_has_been_loaded = true; 637 k = instanceKlassHandle(THREAD, check); 638 } else { 639 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 640 if (placeholder && placeholder->super_load_in_progress()) { 641 super_load_in_progress = true; 642 if (placeholder->havesupername() == true) { 643 superclassname = placeholder->supername(); 644 havesupername = true; 645 } 646 } 647 } 648 } 649 650 // If the class is in the placeholder table, class loading is in progress 651 if (super_load_in_progress && havesupername==true) { 652 k = SystemDictionary::handle_parallel_super_load(name, superclassname, 653 class_loader, protection_domain, lockObject, THREAD); 654 if (HAS_PENDING_EXCEPTION) { 655 return NULL; 656 } 657 if (!k.is_null()) { 658 class_has_been_loaded = true; 659 } 660 } 661 662 bool throw_circularity_error = false; 663 if (!class_has_been_loaded) { 664 bool load_instance_added = false; 665 666 // add placeholder entry to record loading instance class 667 // Five cases: 668 // All cases need to prevent modifying bootclasssearchpath 669 // in parallel with a classload of same classname 670 // Redefineclasses uses existence of the placeholder for the duration 671 // of the class load to prevent concurrent redefinition of not completely 672 // defined classes. 673 // case 1. traditional classloaders that rely on the classloader object lock 674 // - no other need for LOAD_INSTANCE 675 // case 2. traditional classloaders that break the classloader object lock 676 // as a deadlock workaround. Detection of this case requires that 677 // this check is done while holding the classloader object lock, 678 // and that lock is still held when calling classloader's loadClass. 679 // For these classloaders, we ensure that the first requestor 680 // completes the load and other requestors wait for completion. 681 // case 3. UnsyncloadClass - don't use objectLocker 682 // With this flag, we allow parallel classloading of a 683 // class/classloader pair 684 // case4. Bootstrap classloader - don't own objectLocker 685 // This classloader supports parallelism at the classloader level, 686 // but only allows a single load of a class/classloader pair. 687 // No performance benefit and no deadlock issues. 688 // case 5. parallelCapable user level classloaders - without objectLocker 689 // Allow parallel classloading of a class/classloader pair 690 691 { 692 MutexLocker mu(SystemDictionary_lock, THREAD); 693 if (class_loader.is_null() || !is_parallelCapable(class_loader)) { 694 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 695 if (oldprobe) { 696 // only need check_seen_thread once, not on each loop 697 // 6341374 java/lang/Instrument with -Xcomp 698 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) { 699 throw_circularity_error = true; 700 } else { 701 // case 1: traditional: should never see load_in_progress. 702 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) { 703 704 // case 4: bootstrap classloader: prevent futile classloading, 705 // wait on first requestor 706 if (class_loader.is_null()) { 707 SystemDictionary_lock->wait(); 708 } else { 709 // case 2: traditional with broken classloader lock. wait on first 710 // requestor. 711 double_lock_wait(lockObject, THREAD); 712 } 713 // Check if classloading completed while we were waiting 714 Klass* check = find_class(d_index, d_hash, name, loader_data); 715 if (check != NULL) { 716 // Klass is already loaded, so just return it 717 k = instanceKlassHandle(THREAD, check); 718 class_has_been_loaded = true; 719 } 720 // check if other thread failed to load and cleaned up 721 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 722 } 723 } 724 } 725 } 726 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock 727 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try 728 // LOAD_INSTANCE in parallel 729 730 if (!throw_circularity_error && !class_has_been_loaded) { 731 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD); 732 load_instance_added = true; 733 // For class loaders that do not acquire the classloader object lock, 734 // if they did not catch another thread holding LOAD_INSTANCE, 735 // need a check analogous to the acquire ObjectLocker/find_class 736 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL 737 // one final check if the load has already completed 738 // class loaders holding the ObjectLock shouldn't find the class here 739 Klass* check = find_class(d_index, d_hash, name, loader_data); 740 if (check != NULL) { 741 // Klass is already loaded, so return it after checking/adding protection domain 742 k = instanceKlassHandle(THREAD, check); 743 class_has_been_loaded = true; 744 } 745 } 746 } 747 748 // must throw error outside of owning lock 749 if (throw_circularity_error) { 750 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup"); 751 ResourceMark rm(THREAD); 752 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string()); 753 } 754 755 if (!class_has_been_loaded) { 756 757 // Do actual loading 758 k = load_instance_class(name, class_loader, THREAD); 759 760 // For UnsyncloadClass only 761 // If they got a linkageError, check if a parallel class load succeeded. 762 // If it did, then for bytecode resolution the specification requires 763 // that we return the same result we did for the other thread, i.e. the 764 // successfully loaded InstanceKlass 765 // Should not get here for classloaders that support parallelism 766 // with the new cleaner mechanism, even with AllowParallelDefineClass 767 // Bootstrap goes through here to allow for an extra guarantee check 768 if (UnsyncloadClass || (class_loader.is_null())) { 769 if (k.is_null() && HAS_PENDING_EXCEPTION 770 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) { 771 MutexLocker mu(SystemDictionary_lock, THREAD); 772 Klass* check = find_class(d_index, d_hash, name, loader_data); 773 if (check != NULL) { 774 // Klass is already loaded, so just use it 775 k = instanceKlassHandle(THREAD, check); 776 CLEAR_PENDING_EXCEPTION; 777 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?"); 778 } 779 } 780 } 781 782 // If everything was OK (no exceptions, no null return value), and 783 // class_loader is NOT the defining loader, do a little more bookkeeping. 784 if (!HAS_PENDING_EXCEPTION && !k.is_null() && 785 k->class_loader() != class_loader()) { 786 787 check_constraints(d_index, d_hash, k, class_loader, false, THREAD); 788 789 // Need to check for a PENDING_EXCEPTION again; check_constraints 790 // can throw and doesn't use the CHECK macro. 791 if (!HAS_PENDING_EXCEPTION) { 792 { // Grabbing the Compile_lock prevents systemDictionary updates 793 // during compilations. 794 MutexLocker mu(Compile_lock, THREAD); 795 update_dictionary(d_index, d_hash, p_index, p_hash, 796 k, class_loader, THREAD); 797 } 798 if (JvmtiExport::should_post_class_load()) { 799 Thread *thread = THREAD; 800 assert(thread->is_Java_thread(), "thread->is_Java_thread()"); 801 JvmtiExport::post_class_load((JavaThread *) thread, k()); 802 } 803 } 804 } 805 } // load_instance_class loop 806 807 if (HAS_PENDING_EXCEPTION) { 808 // An exception, such as OOM could have happened at various places inside 809 // load_instance_class. We might have partially initialized a shared class 810 // and need to clean it up. 811 if (class_loader.is_null()) { 812 // In some cases k may be null. Let's find the shared class again. 813 instanceKlassHandle ik(THREAD, find_shared_class(name)); 814 if (ik.not_null()) { 815 if (ik->class_loader_data() == NULL) { 816 // We didn't go as far as Klass::restore_unshareable_info(), 817 // so nothing to clean up. 818 } else { 819 MutexLocker mu(SystemDictionary_lock, THREAD); 820 Klass* kk = find_class(name, ik->class_loader_data()); 821 if (kk != NULL) { 822 // No clean up is needed if the shared class has been entered 823 // into system dictionary, as load_shared_class() won't be called 824 // again. 825 } else { 826 clean_up_shared_class(ik, class_loader, THREAD); 827 } 828 } 829 } 830 } 831 } 832 833 if (load_instance_added == true) { 834 // clean up placeholder entries for LOAD_INSTANCE success or error 835 // This brackets the SystemDictionary updates for both defining 836 // and initiating loaders 837 MutexLocker mu(SystemDictionary_lock, THREAD); 838 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD); 839 SystemDictionary_lock->notify_all(); 840 } 841 } 842 843 if (HAS_PENDING_EXCEPTION || k.is_null()) { 844 return NULL; 845 } 846 847#ifdef ASSERT 848 { 849 ClassLoaderData* loader_data = k->class_loader_data(); 850 MutexLocker mu(SystemDictionary_lock, THREAD); 851 Klass* kk = find_class(name, loader_data); 852 assert(kk == k(), "should be present in dictionary"); 853 } 854#endif 855 856 // return if the protection domain in NULL 857 if (protection_domain() == NULL) return k(); 858 859 // Check the protection domain has the right access 860 { 861 MutexLocker mu(SystemDictionary_lock, THREAD); 862 // Note that we have an entry, and entries can be deleted only during GC, 863 // so we cannot allow GC to occur while we're holding this entry. 864 // We're using a No_Safepoint_Verifier to catch any place where we 865 // might potentially do a GC at all. 866 // Dictionary::do_unloading() asserts that classes in SD are only 867 // unloaded at a safepoint. Anonymous classes are not in SD. 868 No_Safepoint_Verifier nosafepoint; 869 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name, 870 loader_data, 871 protection_domain)) { 872 return k(); 873 } 874 } 875 876 // Verify protection domain. If it fails an exception is thrown 877 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL); 878 879 return k(); 880} 881 882 883// This routine does not lock the system dictionary. 884// 885// Since readers don't hold a lock, we must make sure that system 886// dictionary entries are only removed at a safepoint (when only one 887// thread is running), and are added to in a safe way (all links must 888// be updated in an MT-safe manner). 889// 890// Callers should be aware that an entry could be added just after 891// _dictionary->bucket(index) is read here, so the caller will not see 892// the new entry. 893 894Klass* SystemDictionary::find(Symbol* class_name, 895 Handle class_loader, 896 Handle protection_domain, 897 TRAPS) { 898 899 // UseNewReflection 900 // The result of this call should be consistent with the result 901 // of the call to resolve_instance_class_or_null(). 902 // See evaluation 6790209 and 4474172 for more details. 903 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 904 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader()); 905 906 if (loader_data == NULL) { 907 // If the ClassLoaderData has not been setup, 908 // then the class loader has no entries in the dictionary. 909 return NULL; 910 } 911 912 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data); 913 int d_index = dictionary()->hash_to_index(d_hash); 914 915 { 916 // Note that we have an entry, and entries can be deleted only during GC, 917 // so we cannot allow GC to occur while we're holding this entry. 918 // We're using a No_Safepoint_Verifier to catch any place where we 919 // might potentially do a GC at all. 920 // Dictionary::do_unloading() asserts that classes in SD are only 921 // unloaded at a safepoint. Anonymous classes are not in SD. 922 No_Safepoint_Verifier nosafepoint; 923 return dictionary()->find(d_index, d_hash, class_name, loader_data, 924 protection_domain, THREAD); 925 } 926} 927 928 929// Look for a loaded instance or array klass by name. Do not do any loading. 930// return NULL in case of error. 931Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name, 932 Handle class_loader, 933 Handle protection_domain, 934 TRAPS) { 935 Klass* k = NULL; 936 assert(class_name != NULL, "class name must be non NULL"); 937 938 if (FieldType::is_array(class_name)) { 939 // The name refers to an array. Parse the name. 940 // dimension and object_key in FieldArrayInfo are assigned as a 941 // side-effect of this call 942 FieldArrayInfo fd; 943 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL)); 944 if (t != T_OBJECT) { 945 k = Universe::typeArrayKlassObj(t); 946 } else { 947 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD); 948 } 949 if (k != NULL) { 950 k = k->array_klass_or_null(fd.dimension()); 951 } 952 } else { 953 k = find(class_name, class_loader, protection_domain, THREAD); 954 } 955 return k; 956} 957 958// Note: this method is much like resolve_from_stream, but 959// updates no supplemental data structures. 960// TODO consolidate the two methods with a helper routine? 961Klass* SystemDictionary::parse_stream(Symbol* class_name, 962 Handle class_loader, 963 Handle protection_domain, 964 ClassFileStream* st, 965 KlassHandle host_klass, 966 GrowableArray<Handle>* cp_patches, 967 TRAPS) { 968 TempNewSymbol parsed_name = NULL; 969 970 ClassLoaderData* loader_data; 971 if (host_klass.not_null()) { 972 // Create a new CLD for anonymous class, that uses the same class loader 973 // as the host_klass 974 assert(EnableInvokeDynamic, ""); 975 guarantee(host_klass->class_loader() == class_loader(), "should be the same"); 976 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL); 977 loader_data->record_dependency(host_klass(), CHECK_NULL); 978 } else { 979 loader_data = ClassLoaderData::class_loader_data(class_loader()); 980 } 981 982 // Parse the stream. Note that we do this even though this klass might 983 // already be present in the SystemDictionary, otherwise we would not 984 // throw potential ClassFormatErrors. 985 // 986 // Note: "name" is updated. 987 988 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name, 989 loader_data, 990 protection_domain, 991 host_klass, 992 cp_patches, 993 parsed_name, 994 true, 995 THREAD); 996 997 998 if (host_klass.not_null() && k.not_null()) { 999 assert(EnableInvokeDynamic, ""); 1000 k->set_host_klass(host_klass()); 1001 // If it's anonymous, initialize it now, since nobody else will. 1002 1003 { 1004 MutexLocker mu_r(Compile_lock, THREAD); 1005 1006 // Add to class hierarchy, initialize vtables, and do possible 1007 // deoptimizations. 1008 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block 1009 1010 // But, do not add to system dictionary. 1011 } 1012 1013 // Rewrite and patch constant pool here. 1014 k->link_class(CHECK_NULL); 1015 if (cp_patches != NULL) { 1016 k->constants()->patch_resolved_references(cp_patches); 1017 } 1018 k->eager_initialize(CHECK_NULL); 1019 1020 // notify jvmti 1021 if (JvmtiExport::should_post_class_load()) { 1022 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1023 JvmtiExport::post_class_load((JavaThread *) THREAD, k()); 1024 } 1025 } 1026 assert(host_klass.not_null() || cp_patches == NULL, 1027 "cp_patches only found with host_klass"); 1028 1029 return k(); 1030} 1031 1032// Add a klass to the system from a stream (called by jni_DefineClass and 1033// JVM_DefineClass). 1034// Note: class_name can be NULL. In that case we do not know the name of 1035// the class until we have parsed the stream. 1036 1037Klass* SystemDictionary::resolve_from_stream(Symbol* class_name, 1038 Handle class_loader, 1039 Handle protection_domain, 1040 ClassFileStream* st, 1041 bool verify, 1042 TRAPS) { 1043 1044 // Classloaders that support parallelism, e.g. bootstrap classloader, 1045 // or all classloaders with UnsyncloadClass do not acquire lock here 1046 bool DoObjectLock = true; 1047 if (is_parallelCapable(class_loader)) { 1048 DoObjectLock = false; 1049 } 1050 1051 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL); 1052 1053 // Make sure we are synchronized on the class loader before we proceed 1054 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1055 check_loader_lock_contention(lockObject, THREAD); 1056 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 1057 1058 TempNewSymbol parsed_name = NULL; 1059 1060 // Parse the stream. Note that we do this even though this klass might 1061 // already be present in the SystemDictionary, otherwise we would not 1062 // throw potential ClassFormatErrors. 1063 // 1064 // Note: "name" is updated. 1065 1066 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name, 1067 loader_data, 1068 protection_domain, 1069 parsed_name, 1070 verify, 1071 THREAD); 1072 1073 const char* pkg = "java/"; 1074 if (!HAS_PENDING_EXCEPTION && 1075 !class_loader.is_null() && 1076 parsed_name != NULL && 1077 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) { 1078 // It is illegal to define classes in the "java." package from 1079 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader 1080 ResourceMark rm(THREAD); 1081 char* name = parsed_name->as_C_string(); 1082 char* index = strrchr(name, '/'); 1083 *index = '\0'; // chop to just the package name 1084 while ((index = strchr(name, '/')) != NULL) { 1085 *index = '.'; // replace '/' with '.' in package name 1086 } 1087 const char* fmt = "Prohibited package name: %s"; 1088 size_t len = strlen(fmt) + strlen(name); 1089 char* message = NEW_RESOURCE_ARRAY(char, len); 1090 jio_snprintf(message, len, fmt, name); 1091 Exceptions::_throw_msg(THREAD_AND_LOCATION, 1092 vmSymbols::java_lang_SecurityException(), message); 1093 } 1094 1095 if (!HAS_PENDING_EXCEPTION) { 1096 assert(parsed_name != NULL, "Sanity"); 1097 assert(class_name == NULL || class_name == parsed_name, "name mismatch"); 1098 // Verification prevents us from creating names with dots in them, this 1099 // asserts that that's the case. 1100 assert(is_internal_format(parsed_name), 1101 "external class name format used internally"); 1102 1103 // Add class just loaded 1104 // If a class loader supports parallel classloading handle parallel define requests 1105 // find_or_define_instance_class may return a different InstanceKlass 1106 if (is_parallelCapable(class_loader)) { 1107 k = find_or_define_instance_class(class_name, class_loader, k, THREAD); 1108 } else { 1109 define_instance_class(k, THREAD); 1110 } 1111 } 1112 1113 // Make sure we have an entry in the SystemDictionary on success 1114 debug_only( { 1115 if (!HAS_PENDING_EXCEPTION) { 1116 assert(parsed_name != NULL, "parsed_name is still null?"); 1117 Symbol* h_name = k->name(); 1118 ClassLoaderData *defining_loader_data = k->class_loader_data(); 1119 1120 MutexLocker mu(SystemDictionary_lock, THREAD); 1121 1122 Klass* check = find_class(parsed_name, loader_data); 1123 assert(check == k(), "should be present in the dictionary"); 1124 1125 Klass* check2 = find_class(h_name, defining_loader_data); 1126 assert(check == check2, "name inconsistancy in SystemDictionary"); 1127 } 1128 } ); 1129 1130 return k(); 1131} 1132 1133 1134void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length, 1135 int number_of_entries) { 1136 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>), 1137 "bad shared dictionary size."); 1138 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries); 1139} 1140 1141 1142// If there is a shared dictionary, then find the entry for the 1143// given shared system class, if any. 1144 1145Klass* SystemDictionary::find_shared_class(Symbol* class_name) { 1146 if (shared_dictionary() != NULL) { 1147 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL); 1148 int d_index = shared_dictionary()->hash_to_index(d_hash); 1149 1150 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name); 1151 } else { 1152 return NULL; 1153 } 1154} 1155 1156 1157// Load a class from the shared spaces (found through the shared system 1158// dictionary). Force the superclass and all interfaces to be loaded. 1159// Update the class definition to include sibling classes and no 1160// subclasses (yet). [Classes in the shared space are not part of the 1161// object hierarchy until loaded.] 1162 1163instanceKlassHandle SystemDictionary::load_shared_class( 1164 Symbol* class_name, Handle class_loader, TRAPS) { 1165 instanceKlassHandle ik (THREAD, find_shared_class(class_name)); 1166 return load_shared_class(ik, class_loader, THREAD); 1167} 1168 1169instanceKlassHandle SystemDictionary::load_shared_class( 1170 instanceKlassHandle ik, Handle class_loader, TRAPS) { 1171 assert(class_loader.is_null(), "non-null classloader for shared class?"); 1172 if (ik.not_null()) { 1173 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1174 Symbol* class_name = ik->name(); 1175 1176 // Found the class, now load the superclass and interfaces. If they 1177 // are shared, add them to the main system dictionary and reset 1178 // their hierarchy references (supers, subs, and interfaces). 1179 1180 if (ik->super() != NULL) { 1181 Symbol* cn = ik->super()->name(); 1182 resolve_super_or_fail(class_name, cn, 1183 class_loader, Handle(), true, CHECK_(nh)); 1184 } 1185 1186 Array<Klass*>* interfaces = ik->local_interfaces(); 1187 int num_interfaces = interfaces->length(); 1188 for (int index = 0; index < num_interfaces; index++) { 1189 Klass* k = interfaces->at(index); 1190 1191 // Note: can not use InstanceKlass::cast here because 1192 // interfaces' InstanceKlass's C++ vtbls haven't been 1193 // reinitialized yet (they will be once the interface classes 1194 // are loaded) 1195 Symbol* name = k->name(); 1196 resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(nh)); 1197 } 1198 1199 // Adjust methods to recover missing data. They need addresses for 1200 // interpreter entry points and their default native method address 1201 // must be reset. 1202 1203 // Updating methods must be done under a lock so multiple 1204 // threads don't update these in parallel 1205 // Shared classes are all currently loaded by the bootstrap 1206 // classloader, so this will never cause a deadlock on 1207 // a custom class loader lock. 1208 1209 { 1210 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1211 check_loader_lock_contention(lockObject, THREAD); 1212 ObjectLocker ol(lockObject, THREAD, true); 1213 ik->restore_unshareable_info(CHECK_(nh)); 1214 } 1215 1216 if (TraceClassLoading) { 1217 ResourceMark rm; 1218 tty->print("[Loaded %s", ik->external_name()); 1219 tty->print(" from shared objects file"); 1220 tty->print_cr("]"); 1221 } 1222 // notify a class loaded from shared object 1223 ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()), 1224 true /* shared class */); 1225 } 1226 return ik; 1227} 1228 1229void SystemDictionary::clean_up_shared_class(instanceKlassHandle ik, Handle class_loader, TRAPS) { 1230 // Updating methods must be done under a lock so multiple 1231 // threads don't update these in parallel 1232 // Shared classes are all currently loaded by the bootstrap 1233 // classloader, so this will never cause a deadlock on 1234 // a custom class loader lock. 1235 { 1236 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1237 check_loader_lock_contention(lockObject, THREAD); 1238 ObjectLocker ol(lockObject, THREAD, true); 1239 ik->remove_unshareable_info(); 1240 } 1241} 1242 1243instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) { 1244 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1245 if (class_loader.is_null()) { 1246 1247 // Search the shared system dictionary for classes preloaded into the 1248 // shared spaces. 1249 instanceKlassHandle k; 1250 { 1251 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time()); 1252 k = load_shared_class(class_name, class_loader, THREAD); 1253 } 1254 1255 if (k.is_null()) { 1256 // Use VM class loader 1257 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time()); 1258 k = ClassLoader::load_classfile(class_name, CHECK_(nh)); 1259 } 1260 1261 // find_or_define_instance_class may return a different InstanceKlass 1262 if (!k.is_null()) { 1263 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh)); 1264 } 1265 return k; 1266 } else { 1267 // Use user specified class loader to load class. Call loadClass operation on class_loader. 1268 ResourceMark rm(THREAD); 1269 1270 assert(THREAD->is_Java_thread(), "must be a JavaThread"); 1271 JavaThread* jt = (JavaThread*) THREAD; 1272 1273 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(), 1274 ClassLoader::perf_app_classload_selftime(), 1275 ClassLoader::perf_app_classload_count(), 1276 jt->get_thread_stat()->perf_recursion_counts_addr(), 1277 jt->get_thread_stat()->perf_timers_addr(), 1278 PerfClassTraceTime::CLASS_LOAD); 1279 1280 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh)); 1281 // Translate to external class name format, i.e., convert '/' chars to '.' 1282 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh)); 1283 1284 JavaValue result(T_OBJECT); 1285 1286 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass()); 1287 1288 // Call public unsynchronized loadClass(String) directly for all class loaders 1289 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will 1290 // acquire a class-name based lock rather than the class loader object lock. 1291 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean), 1292 // so the call to loadClassInternal() was not required. 1293 // 1294 // UnsyncloadClass flag means both call loadClass(String) and do 1295 // not acquire the class loader lock even for class loaders that are 1296 // not parallelCapable. This was a risky transitional 1297 // flag for diagnostic purposes only. It is risky to call 1298 // custom class loaders without synchronization. 1299 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of 1300 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field. 1301 // Do NOT assume this will be supported in future releases. 1302 // 1303 // Added MustCallLoadClassInternal in case we discover in the field 1304 // a customer that counts on this call 1305 if (MustCallLoadClassInternal && has_loadClassInternal()) { 1306 JavaCalls::call_special(&result, 1307 class_loader, 1308 spec_klass, 1309 vmSymbols::loadClassInternal_name(), 1310 vmSymbols::string_class_signature(), 1311 string, 1312 CHECK_(nh)); 1313 } else { 1314 JavaCalls::call_virtual(&result, 1315 class_loader, 1316 spec_klass, 1317 vmSymbols::loadClass_name(), 1318 vmSymbols::string_class_signature(), 1319 string, 1320 CHECK_(nh)); 1321 } 1322 1323 assert(result.get_type() == T_OBJECT, "just checking"); 1324 oop obj = (oop) result.get_jobject(); 1325 1326 // Primitive classes return null since forName() can not be 1327 // used to obtain any of the Class objects representing primitives or void 1328 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) { 1329 instanceKlassHandle k = 1330 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj)); 1331 // For user defined Java class loaders, check that the name returned is 1332 // the same as that requested. This check is done for the bootstrap 1333 // loader when parsing the class file. 1334 if (class_name == k->name()) { 1335 return k; 1336 } 1337 } 1338 // Class is not found or has the wrong name, return NULL 1339 return nh; 1340 } 1341} 1342 1343void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) { 1344 1345 ClassLoaderData* loader_data = k->class_loader_data(); 1346 Handle class_loader_h(THREAD, loader_data->class_loader()); 1347 1348 for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){} 1349 1350 // for bootstrap and other parallel classloaders don't acquire lock, 1351 // use placeholder token 1352 // If a parallelCapable class loader calls define_instance_class instead of 1353 // find_or_define_instance_class to get here, we have a timing 1354 // hole with systemDictionary updates and check_constraints 1355 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) { 1356 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, 1357 compute_loader_lock_object(class_loader_h, THREAD)), 1358 "define called without lock"); 1359 } 1360 1361 // Check class-loading constraints. Throw exception if violation is detected. 1362 // Grabs and releases SystemDictionary_lock 1363 // The check_constraints/find_class call and update_dictionary sequence 1364 // must be "atomic" for a specific class/classloader pair so we never 1365 // define two different instanceKlasses for that class/classloader pair. 1366 // Existing classloaders will call define_instance_class with the 1367 // classloader lock held 1368 // Parallel classloaders will call find_or_define_instance_class 1369 // which will require a token to perform the define class 1370 Symbol* name_h = k->name(); 1371 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data); 1372 int d_index = dictionary()->hash_to_index(d_hash); 1373 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK); 1374 1375 // Register class just loaded with class loader (placed in Vector) 1376 // Note we do this before updating the dictionary, as this can 1377 // fail with an OutOfMemoryError (if it does, we will *not* put this 1378 // class in the dictionary and will not update the class hierarchy). 1379 // JVMTI FollowReferences needs to find the classes this way. 1380 if (k->class_loader() != NULL) { 1381 methodHandle m(THREAD, Universe::loader_addClass_method()); 1382 JavaValue result(T_VOID); 1383 JavaCallArguments args(class_loader_h); 1384 args.push_oop(Handle(THREAD, k->java_mirror())); 1385 JavaCalls::call(&result, m, &args, CHECK); 1386 } 1387 1388 // Add the new class. We need recompile lock during update of CHA. 1389 { 1390 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data); 1391 int p_index = placeholders()->hash_to_index(p_hash); 1392 1393 MutexLocker mu_r(Compile_lock, THREAD); 1394 1395 // Add to class hierarchy, initialize vtables, and do possible 1396 // deoptimizations. 1397 add_to_hierarchy(k, CHECK); // No exception, but can block 1398 1399 // Add to systemDictionary - so other classes can see it. 1400 // Grabs and releases SystemDictionary_lock 1401 update_dictionary(d_index, d_hash, p_index, p_hash, 1402 k, class_loader_h, THREAD); 1403 } 1404 k->eager_initialize(THREAD); 1405 1406 // notify jvmti 1407 if (JvmtiExport::should_post_class_load()) { 1408 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1409 JvmtiExport::post_class_load((JavaThread *) THREAD, k()); 1410 1411 } 1412} 1413 1414// Support parallel classloading 1415// All parallel class loaders, including bootstrap classloader 1416// lock a placeholder entry for this class/class_loader pair 1417// to allow parallel defines of different classes for this class loader 1418// With AllowParallelDefine flag==true, in case they do not synchronize around 1419// FindLoadedClass/DefineClass, calls, we check for parallel 1420// loading for them, wait if a defineClass is in progress 1421// and return the initial requestor's results 1422// This flag does not apply to the bootstrap classloader. 1423// With AllowParallelDefine flag==false, call through to define_instance_class 1424// which will throw LinkageError: duplicate class definition. 1425// False is the requested default. 1426// For better performance, the class loaders should synchronize 1427// findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they 1428// potentially waste time reading and parsing the bytestream. 1429// Note: VM callers should ensure consistency of k/class_name,class_loader 1430instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) { 1431 1432 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1433 Symbol* name_h = k->name(); // passed in class_name may be null 1434 ClassLoaderData* loader_data = class_loader_data(class_loader); 1435 1436 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data); 1437 int d_index = dictionary()->hash_to_index(d_hash); 1438 1439// Hold SD lock around find_class and placeholder creation for DEFINE_CLASS 1440 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data); 1441 int p_index = placeholders()->hash_to_index(p_hash); 1442 PlaceholderEntry* probe; 1443 1444 { 1445 MutexLocker mu(SystemDictionary_lock, THREAD); 1446 // First check if class already defined 1447 if (UnsyncloadClass || (is_parallelDefine(class_loader))) { 1448 Klass* check = find_class(d_index, d_hash, name_h, loader_data); 1449 if (check != NULL) { 1450 return(instanceKlassHandle(THREAD, check)); 1451 } 1452 } 1453 1454 // Acquire define token for this class/classloader 1455 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD); 1456 // Wait if another thread defining in parallel 1457 // All threads wait - even those that will throw duplicate class: otherwise 1458 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails 1459 // if other thread has not finished updating dictionary 1460 while (probe->definer() != NULL) { 1461 SystemDictionary_lock->wait(); 1462 } 1463 // Only special cases allow parallel defines and can use other thread's results 1464 // Other cases fall through, and may run into duplicate defines 1465 // caught by finding an entry in the SystemDictionary 1466 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) { 1467 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1468 SystemDictionary_lock->notify_all(); 1469#ifdef ASSERT 1470 Klass* check = find_class(d_index, d_hash, name_h, loader_data); 1471 assert(check != NULL, "definer missed recording success"); 1472#endif 1473 return(instanceKlassHandle(THREAD, probe->instance_klass())); 1474 } else { 1475 // This thread will define the class (even if earlier thread tried and had an error) 1476 probe->set_definer(THREAD); 1477 } 1478 } 1479 1480 define_instance_class(k, THREAD); 1481 1482 Handle linkage_exception = Handle(); // null handle 1483 1484 // definer must notify any waiting threads 1485 { 1486 MutexLocker mu(SystemDictionary_lock, THREAD); 1487 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data); 1488 assert(probe != NULL, "DEFINE_CLASS placeholder lost?"); 1489 if (probe != NULL) { 1490 if (HAS_PENDING_EXCEPTION) { 1491 linkage_exception = Handle(THREAD,PENDING_EXCEPTION); 1492 CLEAR_PENDING_EXCEPTION; 1493 } else { 1494 probe->set_instance_klass(k()); 1495 } 1496 probe->set_definer(NULL); 1497 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1498 SystemDictionary_lock->notify_all(); 1499 } 1500 } 1501 1502 // Can't throw exception while holding lock due to rank ordering 1503 if (linkage_exception() != NULL) { 1504 THROW_OOP_(linkage_exception(), nh); // throws exception and returns 1505 } 1506 1507 return k; 1508} 1509Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) { 1510 // If class_loader is NULL we synchronize on _system_loader_lock_obj 1511 if (class_loader.is_null()) { 1512 return Handle(THREAD, _system_loader_lock_obj); 1513 } else { 1514 return class_loader; 1515 } 1516} 1517 1518// This method is added to check how often we have to wait to grab loader 1519// lock. The results are being recorded in the performance counters defined in 1520// ClassLoader::_sync_systemLoaderLockContentionRate and 1521// ClassLoader::_sync_nonSystemLoaderLockConteionRate. 1522void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) { 1523 if (!UsePerfData) { 1524 return; 1525 } 1526 1527 assert(!loader_lock.is_null(), "NULL lock object"); 1528 1529 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock) 1530 == ObjectSynchronizer::owner_other) { 1531 // contention will likely happen, so increment the corresponding 1532 // contention counter. 1533 if (loader_lock() == _system_loader_lock_obj) { 1534 ClassLoader::sync_systemLoaderLockContentionRate()->inc(); 1535 } else { 1536 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc(); 1537 } 1538 } 1539} 1540 1541// ---------------------------------------------------------------------------- 1542// Lookup 1543 1544Klass* SystemDictionary::find_class(int index, unsigned int hash, 1545 Symbol* class_name, 1546 ClassLoaderData* loader_data) { 1547 assert_locked_or_safepoint(SystemDictionary_lock); 1548 assert (index == dictionary()->index_for(class_name, loader_data), 1549 "incorrect index?"); 1550 1551 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data); 1552 return k; 1553} 1554 1555 1556// Basic find on classes in the midst of being loaded 1557Symbol* SystemDictionary::find_placeholder(Symbol* class_name, 1558 ClassLoaderData* loader_data) { 1559 assert_locked_or_safepoint(SystemDictionary_lock); 1560 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data); 1561 int p_index = placeholders()->hash_to_index(p_hash); 1562 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data); 1563} 1564 1565 1566// Used for assertions and verification only 1567Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) { 1568 #ifndef ASSERT 1569 guarantee(VerifyBeforeGC || 1570 VerifyDuringGC || 1571 VerifyBeforeExit || 1572 VerifyAfterGC, "too expensive"); 1573 #endif 1574 assert_locked_or_safepoint(SystemDictionary_lock); 1575 1576 // First look in the loaded class array 1577 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data); 1578 int d_index = dictionary()->hash_to_index(d_hash); 1579 return find_class(d_index, d_hash, class_name, loader_data); 1580} 1581 1582 1583// Get the next class in the diictionary. 1584Klass* SystemDictionary::try_get_next_class() { 1585 return dictionary()->try_get_next_class(); 1586} 1587 1588 1589// ---------------------------------------------------------------------------- 1590// Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock 1591// is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in 1592// before a new class is used. 1593 1594void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) { 1595 assert(k.not_null(), "just checking"); 1596 assert_locked_or_safepoint(Compile_lock); 1597 1598 // Link into hierachy. Make sure the vtables are initialized before linking into 1599 k->append_to_sibling_list(); // add to superklass/sibling list 1600 k->process_interfaces(THREAD); // handle all "implements" declarations 1601 k->set_init_state(InstanceKlass::loaded); 1602 // Now flush all code that depended on old class hierarchy. 1603 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97) 1604 // Also, first reinitialize vtable because it may have gotten out of synch 1605 // while the new class wasn't connected to the class hierarchy. 1606 Universe::flush_dependents_on(k); 1607} 1608 1609 1610// ---------------------------------------------------------------------------- 1611// GC support 1612 1613// Following roots during mark-sweep is separated in two phases. 1614// 1615// The first phase follows preloaded classes and all other system 1616// classes, since these will never get unloaded anyway. 1617// 1618// The second phase removes (unloads) unreachable classes from the 1619// system dictionary and follows the remaining classes' contents. 1620 1621void SystemDictionary::always_strong_oops_do(OopClosure* blk) { 1622 blk->do_oop(&_java_system_loader); 1623 blk->do_oop(&_system_loader_lock_obj); 1624 1625 dictionary()->always_strong_oops_do(blk); 1626 1627 // Visit extra methods 1628 invoke_method_table()->oops_do(blk); 1629} 1630 1631void SystemDictionary::always_strong_classes_do(KlassClosure* closure) { 1632 // Follow all system classes and temporary placeholders in dictionary 1633 dictionary()->always_strong_classes_do(closure); 1634 1635 // Placeholders. These represent classes we're actively loading. 1636 placeholders()->classes_do(closure); 1637} 1638 1639// Calculate a "good" systemdictionary size based 1640// on predicted or current loaded classes count 1641int SystemDictionary::calculate_systemdictionary_size(int classcount) { 1642 int newsize = _old_default_sdsize; 1643 if ((classcount > 0) && !DumpSharedSpaces) { 1644 int desiredsize = classcount/_average_depth_goal; 1645 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1; 1646 newsize = _primelist[++_sdgeneration]) { 1647 if (desiredsize <= newsize) { 1648 break; 1649 } 1650 } 1651 } 1652 return newsize; 1653} 1654// Assumes classes in the SystemDictionary are only unloaded at a safepoint 1655// Note: anonymous classes are not in the SD. 1656bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) { 1657 // First, mark for unload all ClassLoaderData referencing a dead class loader. 1658 bool has_dead_loaders = ClassLoaderDataGraph::do_unloading(is_alive); 1659 bool unloading_occurred = false; 1660 if (has_dead_loaders) { 1661 unloading_occurred = dictionary()->do_unloading(); 1662 constraints()->purge_loader_constraints(); 1663 resolution_errors()->purge_resolution_errors(); 1664} 1665 return unloading_occurred; 1666} 1667 1668void SystemDictionary::oops_do(OopClosure* f) { 1669 f->do_oop(&_java_system_loader); 1670 f->do_oop(&_system_loader_lock_obj); 1671 1672 // Adjust dictionary 1673 dictionary()->oops_do(f); 1674 1675 // Visit extra methods 1676 invoke_method_table()->oops_do(f); 1677} 1678 1679// Extended Class redefinition support. 1680// If one of these classes is replaced, we need to replace it in these places. 1681// KlassClosure::do_klass should take the address of a class but we can 1682// change that later. 1683void SystemDictionary::preloaded_classes_do(KlassClosure* f) { 1684 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) { 1685 f->do_klass(_well_known_klasses[k]); 1686 } 1687 1688 { 1689 for (int i = 0; i < T_VOID+1; i++) { 1690 if (_box_klasses[i] != NULL) { 1691 assert(i >= T_BOOLEAN, "checking"); 1692 f->do_klass(_box_klasses[i]); 1693 } 1694 } 1695 } 1696 1697 FilteredFieldsMap::classes_do(f); 1698} 1699 1700void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) { 1701 f->do_klass(_abstract_ownable_synchronizer_klass); 1702} 1703 1704// Just the classes from defining class loaders 1705// Don't iterate over placeholders 1706void SystemDictionary::classes_do(void f(Klass*)) { 1707 dictionary()->classes_do(f); 1708} 1709 1710// Added for initialize_itable_for_klass 1711// Just the classes from defining class loaders 1712// Don't iterate over placeholders 1713void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) { 1714 dictionary()->classes_do(f, CHECK); 1715} 1716 1717// All classes, and their class loaders 1718// Don't iterate over placeholders 1719void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) { 1720 dictionary()->classes_do(f); 1721} 1722 1723// All classes, and their class loaders 1724// (added for helpers that use HandleMarks and ResourceMarks) 1725// Don't iterate over placeholders 1726void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*, TRAPS), TRAPS) { 1727 dictionary()->classes_do(f, CHECK); 1728} 1729 1730void SystemDictionary::placeholders_do(void f(Symbol*)) { 1731 placeholders()->entries_do(f); 1732} 1733 1734void SystemDictionary::methods_do(void f(Method*)) { 1735 dictionary()->methods_do(f); 1736 invoke_method_table()->methods_do(f); 1737} 1738 1739// ---------------------------------------------------------------------------- 1740// Lazily load klasses 1741 1742void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) { 1743 assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later"); 1744 1745 // if multiple threads calling this function, only one thread will load 1746 // the class. The other threads will find the loaded version once the 1747 // class is loaded. 1748 Klass* aos = _abstract_ownable_synchronizer_klass; 1749 if (aos == NULL) { 1750 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK); 1751 // Force a fence to prevent any read before the write completes 1752 OrderAccess::fence(); 1753 _abstract_ownable_synchronizer_klass = k; 1754 } 1755} 1756 1757// ---------------------------------------------------------------------------- 1758// Initialization 1759 1760void SystemDictionary::initialize(TRAPS) { 1761 // Allocate arrays 1762 assert(dictionary() == NULL, 1763 "SystemDictionary should only be initialized once"); 1764 _sdgeneration = 0; 1765 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount)); 1766 _placeholders = new PlaceholderTable(_nof_buckets); 1767 _number_of_modifications = 0; 1768 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size); 1769 _resolution_errors = new ResolutionErrorTable(_resolution_error_size); 1770 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size); 1771 1772 // Allocate private object used as system class loader lock 1773 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK); 1774 // Initialize basic classes 1775 initialize_preloaded_classes(CHECK); 1776} 1777 1778// Compact table of directions on the initialization of klasses: 1779static const short wk_init_info[] = { 1780 #define WK_KLASS_INIT_INFO(name, symbol, option) \ 1781 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \ 1782 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \ 1783 | (int)SystemDictionary::option ), 1784 WK_KLASSES_DO(WK_KLASS_INIT_INFO) 1785 #undef WK_KLASS_INIT_INFO 1786 0 1787}; 1788 1789bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) { 1790 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 1791 int info = wk_init_info[id - FIRST_WKID]; 1792 int sid = (info >> CEIL_LG_OPTION_LIMIT); 1793 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid); 1794 Klass** klassp = &_well_known_klasses[id]; 1795 bool must_load = (init_opt < SystemDictionary::Opt); 1796 if ((*klassp) == NULL) { 1797 if (must_load) { 1798 (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class 1799 } else { 1800 (*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass 1801 } 1802 } 1803 return ((*klassp) != NULL); 1804} 1805 1806void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) { 1807 assert((int)start_id <= (int)limit_id, "IDs are out of order!"); 1808 for (int id = (int)start_id; id < (int)limit_id; id++) { 1809 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 1810 int info = wk_init_info[id - FIRST_WKID]; 1811 int sid = (info >> CEIL_LG_OPTION_LIMIT); 1812 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT)); 1813 1814 initialize_wk_klass((WKID)id, opt, CHECK); 1815 } 1816 1817 // move the starting value forward to the limit: 1818 start_id = limit_id; 1819} 1820 1821void SystemDictionary::initialize_preloaded_classes(TRAPS) { 1822 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once"); 1823 // Preload commonly used klasses 1824 WKID scan = FIRST_WKID; 1825 // first do Object, then String, Class 1826 if (UseSharedSpaces) { 1827 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK); 1828 // Initialize the constant pool for the Object_class 1829 InstanceKlass* ik = InstanceKlass::cast(Object_klass()); 1830 ik->constants()->restore_unshareable_info(CHECK); 1831 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 1832 } else { 1833 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 1834 } 1835 1836 // Calculate offsets for String and Class classes since they are loaded and 1837 // can be used after this point. 1838 java_lang_String::compute_offsets(); 1839 java_lang_Class::compute_offsets(); 1840 1841 // Fixup mirrors for classes loaded before java.lang.Class. 1842 // These calls iterate over the objects currently in the perm gen 1843 // so calling them at this point is matters (not before when there 1844 // are fewer objects and not later after there are more objects 1845 // in the perm gen. 1846 Universe::initialize_basic_type_mirrors(CHECK); 1847 Universe::fixup_mirrors(CHECK); 1848 1849 // do a bunch more: 1850 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK); 1851 1852 // Preload ref klasses and set reference types 1853 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER); 1854 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass)); 1855 1856 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK); 1857 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT); 1858 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK); 1859 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL); 1860 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM); 1861 1862 // JSR 292 classes 1863 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass); 1864 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass); 1865 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK); 1866 if (EnableInvokeDynamic) { 1867 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK); 1868 } else { 1869 // Skip the JSR 292 classes, if not enabled. 1870 scan = WKID(jsr292_group_end + 1); 1871 } 1872 1873 initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK); 1874 1875 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass); 1876 _box_klasses[T_CHAR] = WK_KLASS(Character_klass); 1877 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass); 1878 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass); 1879 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass); 1880 _box_klasses[T_SHORT] = WK_KLASS(Short_klass); 1881 _box_klasses[T_INT] = WK_KLASS(Integer_klass); 1882 _box_klasses[T_LONG] = WK_KLASS(Long_klass); 1883 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass); 1884 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass); 1885 1886 { // Compute whether we should use loadClass or loadClassInternal when loading classes. 1887 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature()); 1888 _has_loadClassInternal = (method != NULL); 1889 } 1890 { // Compute whether we should use checkPackageAccess or NOT 1891 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature()); 1892 _has_checkPackageAccess = (method != NULL); 1893 } 1894} 1895 1896// Tells if a given klass is a box (wrapper class, such as java.lang.Integer). 1897// If so, returns the basic type it holds. If not, returns T_OBJECT. 1898BasicType SystemDictionary::box_klass_type(Klass* k) { 1899 assert(k != NULL, ""); 1900 for (int i = T_BOOLEAN; i < T_VOID+1; i++) { 1901 if (_box_klasses[i] == k) 1902 return (BasicType)i; 1903 } 1904 return T_OBJECT; 1905} 1906 1907// Constraints on class loaders. The details of the algorithm can be 1908// found in the OOPSLA'98 paper "Dynamic Class Loading in the Java 1909// Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is 1910// that the system dictionary needs to maintain a set of contraints that 1911// must be satisfied by all classes in the dictionary. 1912// if defining is true, then LinkageError if already in systemDictionary 1913// if initiating loader, then ok if InstanceKlass matches existing entry 1914 1915void SystemDictionary::check_constraints(int d_index, unsigned int d_hash, 1916 instanceKlassHandle k, 1917 Handle class_loader, bool defining, 1918 TRAPS) { 1919 const char *linkage_error = NULL; 1920 { 1921 Symbol* name = k->name(); 1922 ClassLoaderData *loader_data = class_loader_data(class_loader); 1923 1924 MutexLocker mu(SystemDictionary_lock, THREAD); 1925 1926 Klass* check = find_class(d_index, d_hash, name, loader_data); 1927 if (check != (Klass*)NULL) { 1928 // if different InstanceKlass - duplicate class definition, 1929 // else - ok, class loaded by a different thread in parallel, 1930 // we should only have found it if it was done loading and ok to use 1931 // system dictionary only holds instance classes, placeholders 1932 // also holds array classes 1933 1934 assert(check->oop_is_instance(), "noninstance in systemdictionary"); 1935 if ((defining == true) || (k() != check)) { 1936 linkage_error = "loader (instance of %s): attempted duplicate class " 1937 "definition for name: \"%s\""; 1938 } else { 1939 return; 1940 } 1941 } 1942 1943#ifdef ASSERT 1944 Symbol* ph_check = find_placeholder(name, loader_data); 1945 assert(ph_check == NULL || ph_check == name, "invalid symbol"); 1946#endif 1947 1948 if (linkage_error == NULL) { 1949 if (constraints()->check_or_update(k, class_loader, name) == false) { 1950 linkage_error = "loader constraint violation: loader (instance of %s)" 1951 " previously initiated loading for a different type with name \"%s\""; 1952 } 1953 } 1954 } 1955 1956 // Throw error now if needed (cannot throw while holding 1957 // SystemDictionary_lock because of rank ordering) 1958 1959 if (linkage_error) { 1960 ResourceMark rm(THREAD); 1961 const char* class_loader_name = loader_name(class_loader()); 1962 char* type_name = k->name()->as_C_string(); 1963 size_t buflen = strlen(linkage_error) + strlen(class_loader_name) + 1964 strlen(type_name); 1965 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 1966 jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name); 1967 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 1968 } 1969} 1970 1971 1972// Update system dictionary - done after check_constraint and add_to_hierachy 1973// have been called. 1974void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash, 1975 int p_index, unsigned int p_hash, 1976 instanceKlassHandle k, 1977 Handle class_loader, 1978 TRAPS) { 1979 // Compile_lock prevents systemDictionary updates during compilations 1980 assert_locked_or_safepoint(Compile_lock); 1981 Symbol* name = k->name(); 1982 ClassLoaderData *loader_data = class_loader_data(class_loader); 1983 1984 { 1985 MutexLocker mu1(SystemDictionary_lock, THREAD); 1986 1987 // See whether biased locking is enabled and if so set it for this 1988 // klass. 1989 // Note that this must be done past the last potential blocking 1990 // point / safepoint. We enable biased locking lazily using a 1991 // VM_Operation to iterate the SystemDictionary and installing the 1992 // biasable mark word into each InstanceKlass's prototype header. 1993 // To avoid race conditions where we accidentally miss enabling the 1994 // optimization for one class in the process of being added to the 1995 // dictionary, we must not safepoint after the test of 1996 // BiasedLocking::enabled(). 1997 if (UseBiasedLocking && BiasedLocking::enabled()) { 1998 // Set biased locking bit for all loaded classes; it will be 1999 // cleared if revocation occurs too often for this type 2000 // NOTE that we must only do this when the class is initally 2001 // defined, not each time it is referenced from a new class loader 2002 if (k->class_loader() == class_loader()) { 2003 k->set_prototype_header(markOopDesc::biased_locking_prototype()); 2004 } 2005 } 2006 2007 // Assign a classid if one has not already been assigned. The 2008 // counter does not need to be atomically incremented since this 2009 // is only done while holding the SystemDictionary_lock. 2010 // All loaded classes get a unique ID. 2011 TRACE_INIT_ID(k); 2012 2013 // Make a new system dictionary entry. 2014 Klass* sd_check = find_class(d_index, d_hash, name, loader_data); 2015 if (sd_check == NULL) { 2016 dictionary()->add_klass(name, loader_data, k); 2017 notice_modification(); 2018 } 2019#ifdef ASSERT 2020 sd_check = find_class(d_index, d_hash, name, loader_data); 2021 assert (sd_check != NULL, "should have entry in system dictionary"); 2022 // Note: there may be a placeholder entry: for circularity testing 2023 // or for parallel defines 2024#endif 2025 SystemDictionary_lock->notify_all(); 2026 } 2027} 2028 2029 2030// Try to find a class name using the loader constraints. The 2031// loader constraints might know about a class that isn't fully loaded 2032// yet and these will be ignored. 2033Klass* SystemDictionary::find_constrained_instance_or_array_klass( 2034 Symbol* class_name, Handle class_loader, TRAPS) { 2035 2036 // First see if it has been loaded directly. 2037 // Force the protection domain to be null. (This removes protection checks.) 2038 Handle no_protection_domain; 2039 Klass* klass = find_instance_or_array_klass(class_name, class_loader, 2040 no_protection_domain, CHECK_NULL); 2041 if (klass != NULL) 2042 return klass; 2043 2044 // Now look to see if it has been loaded elsewhere, and is subject to 2045 // a loader constraint that would require this loader to return the 2046 // klass that is already loaded. 2047 if (FieldType::is_array(class_name)) { 2048 // For array classes, their Klass*s are not kept in the 2049 // constraint table. The element Klass*s are. 2050 FieldArrayInfo fd; 2051 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL)); 2052 if (t != T_OBJECT) { 2053 klass = Universe::typeArrayKlassObj(t); 2054 } else { 2055 MutexLocker mu(SystemDictionary_lock, THREAD); 2056 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader); 2057 } 2058 // If element class already loaded, allocate array klass 2059 if (klass != NULL) { 2060 klass = klass->array_klass_or_null(fd.dimension()); 2061 } 2062 } else { 2063 MutexLocker mu(SystemDictionary_lock, THREAD); 2064 // Non-array classes are easy: simply check the constraint table. 2065 klass = constraints()->find_constrained_klass(class_name, class_loader); 2066 } 2067 2068 return klass; 2069} 2070 2071 2072bool SystemDictionary::add_loader_constraint(Symbol* class_name, 2073 Handle class_loader1, 2074 Handle class_loader2, 2075 Thread* THREAD) { 2076 ClassLoaderData* loader_data1 = class_loader_data(class_loader1); 2077 ClassLoaderData* loader_data2 = class_loader_data(class_loader2); 2078 2079 Symbol* constraint_name = NULL; 2080 if (!FieldType::is_array(class_name)) { 2081 constraint_name = class_name; 2082 } else { 2083 // For array classes, their Klass*s are not kept in the 2084 // constraint table. The element classes are. 2085 FieldArrayInfo fd; 2086 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false)); 2087 // primitive types always pass 2088 if (t != T_OBJECT) { 2089 return true; 2090 } else { 2091 constraint_name = fd.object_key(); 2092 } 2093 } 2094 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1); 2095 int d_index1 = dictionary()->hash_to_index(d_hash1); 2096 2097 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2); 2098 int d_index2 = dictionary()->hash_to_index(d_hash2); 2099 { 2100 MutexLocker mu_s(SystemDictionary_lock, THREAD); 2101 2102 // Better never do a GC while we're holding these oops 2103 No_Safepoint_Verifier nosafepoint; 2104 2105 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1); 2106 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2); 2107 return constraints()->add_entry(constraint_name, klass1, class_loader1, 2108 klass2, class_loader2); 2109 } 2110} 2111 2112// Add entry to resolution error table to record the error when the first 2113// attempt to resolve a reference to a class has failed. 2114void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) { 2115 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2116 int index = resolution_errors()->hash_to_index(hash); 2117 { 2118 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2119 resolution_errors()->add_entry(index, hash, pool, which, error); 2120 } 2121} 2122 2123// Delete a resolution error for RedefineClasses for a constant pool is going away 2124void SystemDictionary::delete_resolution_error(ConstantPool* pool) { 2125 resolution_errors()->delete_entry(pool); 2126} 2127 2128// Lookup resolution error table. Returns error if found, otherwise NULL. 2129Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) { 2130 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2131 int index = resolution_errors()->hash_to_index(hash); 2132 { 2133 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2134 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which); 2135 return (entry != NULL) ? entry->error() : (Symbol*)NULL; 2136 } 2137} 2138 2139 2140// Signature constraints ensure that callers and callees agree about 2141// the meaning of type names in their signatures. This routine is the 2142// intake for constraints. It collects them from several places: 2143// 2144// * LinkResolver::resolve_method (if check_access is true) requires 2145// that the resolving class (the caller) and the defining class of 2146// the resolved method (the callee) agree on each type in the 2147// method's signature. 2148// 2149// * LinkResolver::resolve_interface_method performs exactly the same 2150// checks. 2151// 2152// * LinkResolver::resolve_field requires that the constant pool 2153// attempting to link to a field agree with the field's defining 2154// class about the type of the field signature. 2155// 2156// * klassVtable::initialize_vtable requires that, when a class 2157// overrides a vtable entry allocated by a superclass, that the 2158// overriding method (i.e., the callee) agree with the superclass 2159// on each type in the method's signature. 2160// 2161// * klassItable::initialize_itable requires that, when a class fills 2162// in its itables, for each non-abstract method installed in an 2163// itable, the method (i.e., the callee) agree with the interface 2164// on each type in the method's signature. 2165// 2166// All those methods have a boolean (check_access, checkconstraints) 2167// which turns off the checks. This is used from specialized contexts 2168// such as bootstrapping, dumping, and debugging. 2169// 2170// No direct constraint is placed between the class and its 2171// supertypes. Constraints are only placed along linked relations 2172// between callers and callees. When a method overrides or implements 2173// an abstract method in a supertype (superclass or interface), the 2174// constraints are placed as if the supertype were the caller to the 2175// overriding method. (This works well, since callers to the 2176// supertype have already established agreement between themselves and 2177// the supertype.) As a result of all this, a class can disagree with 2178// its supertype about the meaning of a type name, as long as that 2179// class neither calls a relevant method of the supertype, nor is 2180// called (perhaps via an override) from the supertype. 2181// 2182// 2183// SystemDictionary::check_signature_loaders(sig, l1, l2) 2184// 2185// Make sure all class components (including arrays) in the given 2186// signature will be resolved to the same class in both loaders. 2187// Returns the name of the type that failed a loader constraint check, or 2188// NULL if no constraint failed. No exception except OOME is thrown. 2189// Arrays are not added to the loader constraint table, their elements are. 2190Symbol* SystemDictionary::check_signature_loaders(Symbol* signature, 2191 Handle loader1, Handle loader2, 2192 bool is_method, TRAPS) { 2193 // Nothing to do if loaders are the same. 2194 if (loader1() == loader2()) { 2195 return NULL; 2196 } 2197 2198 SignatureStream sig_strm(signature, is_method); 2199 while (!sig_strm.is_done()) { 2200 if (sig_strm.is_object()) { 2201 Symbol* sig = sig_strm.as_symbol(CHECK_NULL); 2202 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) { 2203 return sig; 2204 } 2205 } 2206 sig_strm.next(); 2207 } 2208 return NULL; 2209} 2210 2211 2212methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid, 2213 Symbol* signature, 2214 TRAPS) { 2215 methodHandle empty; 2216 assert(EnableInvokeDynamic, ""); 2217 assert(MethodHandles::is_signature_polymorphic(iid) && 2218 MethodHandles::is_signature_polymorphic_intrinsic(iid) && 2219 iid != vmIntrinsics::_invokeGeneric, 2220 err_msg("must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid))); 2221 2222 unsigned int hash = invoke_method_table()->compute_hash(signature, iid); 2223 int index = invoke_method_table()->hash_to_index(hash); 2224 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid); 2225 methodHandle m; 2226 if (spe == NULL || spe->method() == NULL) { 2227 spe = NULL; 2228 // Must create lots of stuff here, but outside of the SystemDictionary lock. 2229 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty)); 2230 CompileBroker::compile_method(m, InvocationEntryBci, CompLevel_highest_tier, 2231 methodHandle(), CompileThreshold, "MH", CHECK_(empty)); 2232 2233 // Now grab the lock. We might have to throw away the new method, 2234 // if a racing thread has managed to install one at the same time. 2235 { 2236 MutexLocker ml(SystemDictionary_lock, THREAD); 2237 spe = invoke_method_table()->find_entry(index, hash, signature, iid); 2238 if (spe == NULL) 2239 spe = invoke_method_table()->add_entry(index, hash, signature, iid); 2240 if (spe->method() == NULL) 2241 spe->set_method(m()); 2242 } 2243 } 2244 2245 assert(spe != NULL && spe->method() != NULL, ""); 2246 return spe->method(); 2247} 2248 2249// Helper for unpacking the return value from linkMethod and linkCallSite. 2250static methodHandle unpack_method_and_appendix(Handle mname, 2251 KlassHandle accessing_klass, 2252 objArrayHandle appendix_box, 2253 Handle* appendix_result, 2254 TRAPS) { 2255 methodHandle empty; 2256 if (mname.not_null()) { 2257 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname()); 2258 if (vmtarget != NULL && vmtarget->is_method()) { 2259 Method* m = (Method*)vmtarget; 2260 oop appendix = appendix_box->obj_at(0); 2261 if (TraceMethodHandles) { 2262 #ifndef PRODUCT 2263 tty->print("Linked method="INTPTR_FORMAT": ", m); 2264 m->print(); 2265 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); } 2266 tty->cr(); 2267 #endif //PRODUCT 2268 } 2269 (*appendix_result) = Handle(THREAD, appendix); 2270 // the target is stored in the cpCache and if a reference to this 2271 // MethodName is dropped we need a way to make sure the 2272 // class_loader containing this method is kept alive. 2273 // FIXME: the appendix might also preserve this dependency. 2274 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data(); 2275 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM 2276 return methodHandle(THREAD, m); 2277 } 2278 } 2279 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty); 2280 return empty; 2281} 2282 2283methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name, 2284 Symbol* signature, 2285 KlassHandle accessing_klass, 2286 Handle *appendix_result, 2287 Handle *method_type_result, 2288 TRAPS) { 2289 methodHandle empty; 2290 assert(EnableInvokeDynamic, ""); 2291 assert(!THREAD->is_Compiler_thread(), ""); 2292 Handle method_type = 2293 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty)); 2294 if (false) { // FIXME: Decide if the Java upcall should resolve signatures. 2295 method_type = java_lang_String::create_from_symbol(signature, CHECK_(empty)); 2296 } 2297 2298 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass(); 2299 int ref_kind = JVM_REF_invokeVirtual; 2300 Handle name_str = StringTable::intern(name, CHECK_(empty)); 2301 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty)); 2302 assert(appendix_box->obj_at(0) == NULL, ""); 2303 2304 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName 2305 JavaCallArguments args; 2306 args.push_oop(accessing_klass()->java_mirror()); 2307 args.push_int(ref_kind); 2308 args.push_oop(mh_klass()->java_mirror()); 2309 args.push_oop(name_str()); 2310 args.push_oop(method_type()); 2311 args.push_oop(appendix_box()); 2312 JavaValue result(T_OBJECT); 2313 JavaCalls::call_static(&result, 2314 SystemDictionary::MethodHandleNatives_klass(), 2315 vmSymbols::linkMethod_name(), 2316 vmSymbols::linkMethod_signature(), 2317 &args, CHECK_(empty)); 2318 Handle mname(THREAD, (oop) result.get_jobject()); 2319 (*method_type_result) = method_type; 2320 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD); 2321} 2322 2323 2324// Ask Java code to find or construct a java.lang.invoke.MethodType for the given 2325// signature, as interpreted relative to the given class loader. 2326// Because of class loader constraints, all method handle usage must be 2327// consistent with this loader. 2328Handle SystemDictionary::find_method_handle_type(Symbol* signature, 2329 KlassHandle accessing_klass, 2330 TRAPS) { 2331 Handle empty; 2332 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics 2333 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid); 2334 int index = invoke_method_table()->hash_to_index(hash); 2335 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2336 if (spe != NULL && spe->method_type() != NULL) { 2337 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), ""); 2338 return Handle(THREAD, spe->method_type()); 2339 } else if (THREAD->is_Compiler_thread()) { 2340 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME 2341 return Handle(); // do not attempt from within compiler, unless it was cached 2342 } 2343 2344 Handle class_loader, protection_domain; 2345 bool is_on_bcp = true; // keep this true as long as we can materialize from the boot classloader 2346 int npts = ArgumentCount(signature).size(); 2347 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty)); 2348 int arg = 0; 2349 Handle rt; // the return type from the signature 2350 ResourceMark rm(THREAD); 2351 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) { 2352 oop mirror = NULL; 2353 if (is_on_bcp) { 2354 // Note: class_loader & protection_domain are both null at this point. 2355 mirror = ss.as_java_mirror(class_loader, protection_domain, 2356 SignatureStream::ReturnNull, CHECK_(empty)); 2357 if (mirror == NULL) { 2358 // fall back from BCP to accessing_klass 2359 if (accessing_klass.not_null()) { 2360 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader()); 2361 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain()); 2362 } 2363 is_on_bcp = false; 2364 } 2365 } 2366 if (!is_on_bcp) { 2367 // Resolve, throwing a real error if it doesn't work. 2368 mirror = ss.as_java_mirror(class_loader, protection_domain, 2369 SignatureStream::NCDFError, CHECK_(empty)); 2370 } 2371 if (ss.at_return_type()) 2372 rt = Handle(THREAD, mirror); 2373 else 2374 pts->obj_at_put(arg++, mirror); 2375 2376 // Check accessibility. 2377 if (ss.is_object() && accessing_klass.not_null()) { 2378 Klass* sel_klass = java_lang_Class::as_Klass(mirror); 2379 mirror = NULL; // safety 2380 // Emulate ConstantPool::verify_constant_pool_resolve. 2381 if (sel_klass->oop_is_objArray()) 2382 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass(); 2383 if (sel_klass->oop_is_instance()) { 2384 KlassHandle sel_kh(THREAD, sel_klass); 2385 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty)); 2386 } 2387 } 2388 } 2389 assert(arg == npts, ""); 2390 2391 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType 2392 JavaCallArguments args(Handle(THREAD, rt())); 2393 args.push_oop(pts()); 2394 JavaValue result(T_OBJECT); 2395 JavaCalls::call_static(&result, 2396 SystemDictionary::MethodHandleNatives_klass(), 2397 vmSymbols::findMethodHandleType_name(), 2398 vmSymbols::findMethodHandleType_signature(), 2399 &args, CHECK_(empty)); 2400 Handle method_type(THREAD, (oop) result.get_jobject()); 2401 2402 if (is_on_bcp) { 2403 // We can cache this MethodType inside the JVM. 2404 MutexLocker ml(SystemDictionary_lock, THREAD); 2405 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2406 if (spe == NULL) 2407 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid); 2408 if (spe->method_type() == NULL) { 2409 spe->set_method_type(method_type()); 2410 } 2411 } 2412 2413 // report back to the caller with the MethodType 2414 return method_type; 2415} 2416 2417// Ask Java code to find or construct a method handle constant. 2418Handle SystemDictionary::link_method_handle_constant(KlassHandle caller, 2419 int ref_kind, //e.g., JVM_REF_invokeVirtual 2420 KlassHandle callee, 2421 Symbol* name_sym, 2422 Symbol* signature, 2423 TRAPS) { 2424 Handle empty; 2425 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty)); 2426 Handle type; 2427 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') { 2428 type = find_method_handle_type(signature, caller, CHECK_(empty)); 2429 } else { 2430 ResourceMark rm(THREAD); 2431 SignatureStream ss(signature, false); 2432 if (!ss.is_done()) { 2433 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(), 2434 SignatureStream::NCDFError, CHECK_(empty)); 2435 type = Handle(THREAD, mirror); 2436 ss.next(); 2437 if (!ss.is_done()) type = Handle(); // error! 2438 } 2439 } 2440 if (type.is_null()) { 2441 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty); 2442 } 2443 2444 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle 2445 JavaCallArguments args; 2446 args.push_oop(caller->java_mirror()); // the referring class 2447 args.push_int(ref_kind); 2448 args.push_oop(callee->java_mirror()); // the target class 2449 args.push_oop(name()); 2450 args.push_oop(type()); 2451 JavaValue result(T_OBJECT); 2452 JavaCalls::call_static(&result, 2453 SystemDictionary::MethodHandleNatives_klass(), 2454 vmSymbols::linkMethodHandleConstant_name(), 2455 vmSymbols::linkMethodHandleConstant_signature(), 2456 &args, CHECK_(empty)); 2457 return Handle(THREAD, (oop) result.get_jobject()); 2458} 2459 2460// Ask Java code to find or construct a java.lang.invoke.CallSite for the given 2461// name and signature, as interpreted relative to the given class loader. 2462methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller, 2463 Handle bootstrap_specifier, 2464 Symbol* name, 2465 Symbol* type, 2466 Handle *appendix_result, 2467 Handle *method_type_result, 2468 TRAPS) { 2469 methodHandle empty; 2470 Handle bsm, info; 2471 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) { 2472 bsm = bootstrap_specifier; 2473 } else { 2474 assert(bootstrap_specifier->is_objArray(), ""); 2475 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier()); 2476 int len = args->length(); 2477 assert(len >= 1, ""); 2478 bsm = Handle(THREAD, args->obj_at(0)); 2479 if (len > 1) { 2480 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty)); 2481 for (int i = 1; i < len; i++) 2482 args1->obj_at_put(i-1, args->obj_at(i)); 2483 info = Handle(THREAD, args1); 2484 } 2485 } 2486 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()), 2487 "caller must supply a valid BSM"); 2488 2489 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty)); 2490 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty)); 2491 2492 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty)); 2493 assert(appendix_box->obj_at(0) == NULL, ""); 2494 2495 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix) 2496 JavaCallArguments args; 2497 args.push_oop(caller->java_mirror()); 2498 args.push_oop(bsm()); 2499 args.push_oop(method_name()); 2500 args.push_oop(method_type()); 2501 args.push_oop(info()); 2502 args.push_oop(appendix_box); 2503 JavaValue result(T_OBJECT); 2504 JavaCalls::call_static(&result, 2505 SystemDictionary::MethodHandleNatives_klass(), 2506 vmSymbols::linkCallSite_name(), 2507 vmSymbols::linkCallSite_signature(), 2508 &args, CHECK_(empty)); 2509 Handle mname(THREAD, (oop) result.get_jobject()); 2510 (*method_type_result) = method_type; 2511 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD); 2512} 2513 2514// Since the identity hash code for symbols changes when the symbols are 2515// moved from the regular perm gen (hash in the mark word) to the shared 2516// spaces (hash is the address), the classes loaded into the dictionary 2517// may be in the wrong buckets. 2518 2519void SystemDictionary::reorder_dictionary() { 2520 dictionary()->reorder_dictionary(); 2521} 2522 2523 2524void SystemDictionary::copy_buckets(char** top, char* end) { 2525 dictionary()->copy_buckets(top, end); 2526} 2527 2528 2529void SystemDictionary::copy_table(char** top, char* end) { 2530 dictionary()->copy_table(top, end); 2531} 2532 2533 2534void SystemDictionary::reverse() { 2535 dictionary()->reverse(); 2536} 2537 2538int SystemDictionary::number_of_classes() { 2539 return dictionary()->number_of_entries(); 2540} 2541 2542 2543// ---------------------------------------------------------------------------- 2544#ifndef PRODUCT 2545 2546void SystemDictionary::print() { 2547 dictionary()->print(); 2548 2549 // Placeholders 2550 GCMutexLocker mu(SystemDictionary_lock); 2551 placeholders()->print(); 2552 2553 // loader constraints - print under SD_lock 2554 constraints()->print(); 2555} 2556 2557#endif 2558 2559void SystemDictionary::verify() { 2560 guarantee(dictionary() != NULL, "Verify of system dictionary failed"); 2561 guarantee(constraints() != NULL, 2562 "Verify of loader constraints failed"); 2563 guarantee(dictionary()->number_of_entries() >= 0 && 2564 placeholders()->number_of_entries() >= 0, 2565 "Verify of system dictionary failed"); 2566 2567 // Verify dictionary 2568 dictionary()->verify(); 2569 2570 GCMutexLocker mu(SystemDictionary_lock); 2571 placeholders()->verify(); 2572 2573 // Verify constraint table 2574 guarantee(constraints() != NULL, "Verify of loader constraints failed"); 2575 constraints()->verify(dictionary(), placeholders()); 2576} 2577 2578 2579void SystemDictionary::verify_obj_klass_present(Symbol* class_name, 2580 ClassLoaderData* loader_data) { 2581 GCMutexLocker mu(SystemDictionary_lock); 2582 Symbol* name; 2583 2584 Klass* probe = find_class(class_name, loader_data); 2585 if (probe == NULL) { 2586 probe = SystemDictionary::find_shared_class(class_name); 2587 if (probe == NULL) { 2588 name = find_placeholder(class_name, loader_data); 2589 } 2590 } 2591 guarantee(probe != NULL || name != NULL, 2592 "Loaded klasses should be in SystemDictionary"); 2593} 2594 2595#ifndef PRODUCT 2596 2597// statistics code 2598class ClassStatistics: AllStatic { 2599 private: 2600 static int nclasses; // number of classes 2601 static int nmethods; // number of methods 2602 static int nmethoddata; // number of methodData 2603 static int class_size; // size of class objects in words 2604 static int method_size; // size of method objects in words 2605 static int debug_size; // size of debug info in methods 2606 static int methoddata_size; // size of methodData objects in words 2607 2608 static void do_class(Klass* k) { 2609 nclasses++; 2610 class_size += k->size(); 2611 if (k->oop_is_instance()) { 2612 InstanceKlass* ik = (InstanceKlass*)k; 2613 class_size += ik->methods()->size(); 2614 class_size += ik->constants()->size(); 2615 class_size += ik->local_interfaces()->size(); 2616 class_size += ik->transitive_interfaces()->size(); 2617 // We do not have to count implementors, since we only store one! 2618 // SSS: How should these be accounted now that they have moved? 2619 // class_size += ik->fields()->length(); 2620 } 2621 } 2622 2623 static void do_method(Method* m) { 2624 nmethods++; 2625 method_size += m->size(); 2626 // class loader uses same objArray for empty vectors, so don't count these 2627 if (m->has_stackmap_table()) { 2628 method_size += m->stackmap_data()->size(); 2629 } 2630 2631 MethodData* mdo = m->method_data(); 2632 if (mdo != NULL) { 2633 nmethoddata++; 2634 methoddata_size += mdo->size(); 2635 } 2636 } 2637 2638 public: 2639 static void print() { 2640 SystemDictionary::classes_do(do_class); 2641 SystemDictionary::methods_do(do_method); 2642 tty->print_cr("Class statistics:"); 2643 tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize); 2644 tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods, 2645 (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize); 2646 tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize); 2647 } 2648}; 2649 2650 2651int ClassStatistics::nclasses = 0; 2652int ClassStatistics::nmethods = 0; 2653int ClassStatistics::nmethoddata = 0; 2654int ClassStatistics::class_size = 0; 2655int ClassStatistics::method_size = 0; 2656int ClassStatistics::debug_size = 0; 2657int ClassStatistics::methoddata_size = 0; 2658 2659void SystemDictionary::print_class_statistics() { 2660 ResourceMark rm; 2661 ClassStatistics::print(); 2662} 2663 2664 2665class MethodStatistics: AllStatic { 2666 public: 2667 enum { 2668 max_parameter_size = 10 2669 }; 2670 private: 2671 2672 static int _number_of_methods; 2673 static int _number_of_final_methods; 2674 static int _number_of_static_methods; 2675 static int _number_of_native_methods; 2676 static int _number_of_synchronized_methods; 2677 static int _number_of_profiled_methods; 2678 static int _number_of_bytecodes; 2679 static int _parameter_size_profile[max_parameter_size]; 2680 static int _bytecodes_profile[Bytecodes::number_of_java_codes]; 2681 2682 static void initialize() { 2683 _number_of_methods = 0; 2684 _number_of_final_methods = 0; 2685 _number_of_static_methods = 0; 2686 _number_of_native_methods = 0; 2687 _number_of_synchronized_methods = 0; 2688 _number_of_profiled_methods = 0; 2689 _number_of_bytecodes = 0; 2690 for (int i = 0; i < max_parameter_size ; i++) _parameter_size_profile[i] = 0; 2691 for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile [j] = 0; 2692 }; 2693 2694 static void do_method(Method* m) { 2695 _number_of_methods++; 2696 // collect flag info 2697 if (m->is_final() ) _number_of_final_methods++; 2698 if (m->is_static() ) _number_of_static_methods++; 2699 if (m->is_native() ) _number_of_native_methods++; 2700 if (m->is_synchronized()) _number_of_synchronized_methods++; 2701 if (m->method_data() != NULL) _number_of_profiled_methods++; 2702 // collect parameter size info (add one for receiver, if any) 2703 _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++; 2704 // collect bytecodes info 2705 { 2706 Thread *thread = Thread::current(); 2707 HandleMark hm(thread); 2708 BytecodeStream s(methodHandle(thread, m)); 2709 Bytecodes::Code c; 2710 while ((c = s.next()) >= 0) { 2711 _number_of_bytecodes++; 2712 _bytecodes_profile[c]++; 2713 } 2714 } 2715 } 2716 2717 public: 2718 static void print() { 2719 initialize(); 2720 SystemDictionary::methods_do(do_method); 2721 // generate output 2722 tty->cr(); 2723 tty->print_cr("Method statistics (static):"); 2724 // flag distribution 2725 tty->cr(); 2726 tty->print_cr("%6d final methods %6.1f%%", _number_of_final_methods , _number_of_final_methods * 100.0F / _number_of_methods); 2727 tty->print_cr("%6d static methods %6.1f%%", _number_of_static_methods , _number_of_static_methods * 100.0F / _number_of_methods); 2728 tty->print_cr("%6d native methods %6.1f%%", _number_of_native_methods , _number_of_native_methods * 100.0F / _number_of_methods); 2729 tty->print_cr("%6d synchronized methods %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods); 2730 tty->print_cr("%6d profiled methods %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods); 2731 // parameter size profile 2732 tty->cr(); 2733 { int tot = 0; 2734 int avg = 0; 2735 for (int i = 0; i < max_parameter_size; i++) { 2736 int n = _parameter_size_profile[i]; 2737 tot += n; 2738 avg += n*i; 2739 tty->print_cr("parameter size = %1d: %6d methods %5.1f%%", i, n, n * 100.0F / _number_of_methods); 2740 } 2741 assert(tot == _number_of_methods, "should be the same"); 2742 tty->print_cr(" %6d methods 100.0%%", _number_of_methods); 2743 tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods); 2744 } 2745 // bytecodes profile 2746 tty->cr(); 2747 { int tot = 0; 2748 for (int i = 0; i < Bytecodes::number_of_java_codes; i++) { 2749 if (Bytecodes::is_defined(i)) { 2750 Bytecodes::Code c = Bytecodes::cast(i); 2751 int n = _bytecodes_profile[c]; 2752 tot += n; 2753 tty->print_cr("%9d %7.3f%% %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c)); 2754 } 2755 } 2756 assert(tot == _number_of_bytecodes, "should be the same"); 2757 tty->print_cr("%9d 100.000%%", _number_of_bytecodes); 2758 } 2759 tty->cr(); 2760 } 2761}; 2762 2763int MethodStatistics::_number_of_methods; 2764int MethodStatistics::_number_of_final_methods; 2765int MethodStatistics::_number_of_static_methods; 2766int MethodStatistics::_number_of_native_methods; 2767int MethodStatistics::_number_of_synchronized_methods; 2768int MethodStatistics::_number_of_profiled_methods; 2769int MethodStatistics::_number_of_bytecodes; 2770int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size]; 2771int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes]; 2772 2773 2774void SystemDictionary::print_method_statistics() { 2775 MethodStatistics::print(); 2776} 2777 2778#endif // PRODUCT 2779