systemDictionary.cpp revision 6402:2377269bd73d
1/* 2 * Copyright (c) 1997, 2014, 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/orderAccess.inline.hpp" 56#include "runtime/signature.hpp" 57#include "services/classLoadingService.hpp" 58#include "services/threadService.hpp" 59#include "utilities/macros.hpp" 60#include "utilities/ticks.hpp" 61 62#if INCLUDE_TRACE 63 #include "trace/tracing.hpp" 64#endif 65 66Dictionary* SystemDictionary::_dictionary = NULL; 67PlaceholderTable* SystemDictionary::_placeholders = NULL; 68Dictionary* SystemDictionary::_shared_dictionary = NULL; 69LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL; 70ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL; 71SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL; 72 73 74int SystemDictionary::_number_of_modifications = 0; 75int SystemDictionary::_sdgeneration = 0; 76const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103, 77 20201,40423,99991}; 78 79oop SystemDictionary::_system_loader_lock_obj = NULL; 80 81Klass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT] 82 = { NULL /*, NULL...*/ }; 83 84Klass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ }; 85 86oop SystemDictionary::_java_system_loader = NULL; 87 88bool SystemDictionary::_has_loadClassInternal = false; 89bool SystemDictionary::_has_checkPackageAccess = false; 90 91// lazily initialized klass variables 92Klass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL; 93 94 95// ---------------------------------------------------------------------------- 96// Java-level SystemLoader 97 98oop SystemDictionary::java_system_loader() { 99 return _java_system_loader; 100} 101 102void SystemDictionary::compute_java_system_loader(TRAPS) { 103 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass)); 104 JavaValue result(T_OBJECT); 105 JavaCalls::call_static(&result, 106 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)), 107 vmSymbols::getSystemClassLoader_name(), 108 vmSymbols::void_classloader_signature(), 109 CHECK); 110 111 _java_system_loader = (oop)result.get_jobject(); 112} 113 114 115ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) { 116 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data(); 117 return ClassLoaderDataGraph::find_or_create(class_loader, CHECK_NULL); 118} 119 120// ---------------------------------------------------------------------------- 121// debugging 122 123#ifdef ASSERT 124 125// return true if class_name contains no '.' (internal format is '/') 126bool SystemDictionary::is_internal_format(Symbol* class_name) { 127 if (class_name != NULL) { 128 ResourceMark rm; 129 char* name = class_name->as_C_string(); 130 return strchr(name, '.') == NULL; 131 } else { 132 return true; 133 } 134} 135 136#endif 137 138// ---------------------------------------------------------------------------- 139// Parallel class loading check 140 141bool SystemDictionary::is_parallelCapable(Handle class_loader) { 142 if (UnsyncloadClass || class_loader.is_null()) return true; 143 if (AlwaysLockClassLoader) return false; 144 return java_lang_ClassLoader::parallelCapable(class_loader()); 145} 146// ---------------------------------------------------------------------------- 147// ParallelDefineClass flag does not apply to bootclass loader 148bool SystemDictionary::is_parallelDefine(Handle class_loader) { 149 if (class_loader.is_null()) return false; 150 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) { 151 return true; 152 } 153 return false; 154} 155 156/** 157 * Returns true if the passed class loader is the extension class loader. 158 */ 159bool SystemDictionary::is_ext_class_loader(Handle class_loader) { 160 if (class_loader.is_null()) { 161 return false; 162 } 163 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader()); 164} 165 166// ---------------------------------------------------------------------------- 167// Resolving of classes 168 169// Forwards to resolve_or_null 170 171Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) { 172 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD); 173 if (HAS_PENDING_EXCEPTION || klass == NULL) { 174 KlassHandle k_h(THREAD, klass); 175 // can return a null klass 176 klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD); 177 } 178 return klass; 179} 180 181Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) { 182 if (HAS_PENDING_EXCEPTION) { 183 // If we have a pending exception we forward it to the caller, unless throw_error is true, 184 // in which case we have to check whether the pending exception is a ClassNotFoundException, 185 // and if so convert it to a NoClassDefFoundError 186 // And chain the original ClassNotFoundException 187 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) { 188 ResourceMark rm(THREAD); 189 assert(klass_h() == NULL, "Should not have result with exception pending"); 190 Handle e(THREAD, PENDING_EXCEPTION); 191 CLEAR_PENDING_EXCEPTION; 192 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e); 193 } else { 194 return NULL; 195 } 196 } 197 // Class not found, throw appropriate error or exception depending on value of throw_error 198 if (klass_h() == NULL) { 199 ResourceMark rm(THREAD); 200 if (throw_error) { 201 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string()); 202 } else { 203 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string()); 204 } 205 } 206 return (Klass*)klass_h(); 207} 208 209 210Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, 211 bool throw_error, TRAPS) 212{ 213 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD); 214} 215 216 217// Forwards to resolve_instance_class_or_null 218 219Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) { 220 assert(!THREAD->is_Compiler_thread(), 221 err_msg("can not load classes with compiler thread: class=%s, classloader=%s", 222 class_name->as_C_string(), 223 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string())); 224 if (FieldType::is_array(class_name)) { 225 return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL); 226 } else if (FieldType::is_obj(class_name)) { 227 ResourceMark rm(THREAD); 228 // Ignore wrapping L and ;. 229 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1, 230 class_name->utf8_length() - 2, CHECK_NULL); 231 return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL); 232 } else { 233 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL); 234 } 235} 236 237Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) { 238 return resolve_or_null(class_name, Handle(), Handle(), THREAD); 239} 240 241// Forwards to resolve_instance_class_or_null 242 243Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name, 244 Handle class_loader, 245 Handle protection_domain, 246 TRAPS) { 247 assert(FieldType::is_array(class_name), "must be array"); 248 Klass* k = NULL; 249 FieldArrayInfo fd; 250 // dimension and object_key in FieldArrayInfo are assigned as a side-effect 251 // of this call 252 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL); 253 if (t == T_OBJECT) { 254 // naked oop "k" is OK here -- we assign back into it 255 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(), 256 class_loader, 257 protection_domain, 258 CHECK_NULL); 259 if (k != NULL) { 260 k = k->array_klass(fd.dimension(), CHECK_NULL); 261 } 262 } else { 263 k = Universe::typeArrayKlassObj(t); 264 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL); 265 } 266 return k; 267} 268 269 270// Must be called for any super-class or super-interface resolution 271// during class definition to allow class circularity checking 272// super-interface callers: 273// parse_interfaces - for defineClass & jvmtiRedefineClasses 274// super-class callers: 275// ClassFileParser - for defineClass & jvmtiRedefineClasses 276// load_shared_class - while loading a class from shared archive 277// resolve_instance_class_or_null: 278// via: handle_parallel_super_load 279// when resolving a class that has an existing placeholder with 280// a saved superclass [i.e. a defineClass is currently in progress] 281// if another thread is trying to resolve the class, it must do 282// super-class checks on its own thread to catch class circularity 283// This last call is critical in class circularity checking for cases 284// where classloading is delegated to different threads and the 285// classloader lock is released. 286// Take the case: Base->Super->Base 287// 1. If thread T1 tries to do a defineClass of class Base 288// resolve_super_or_fail creates placeholder: T1, Base (super Super) 289// 2. resolve_instance_class_or_null does not find SD or placeholder for Super 290// so it tries to load Super 291// 3. If we load the class internally, or user classloader uses same thread 292// loadClassFromxxx or defineClass via parseClassFile Super ... 293// 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base) 294// 3.3 resolve_instance_class_or_null Base, finds placeholder for Base 295// 3.4 calls resolve_super_or_fail Base 296// 3.5 finds T1,Base -> throws class circularity 297//OR 4. If T2 tries to resolve Super via defineClass Super ... 298// 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base) 299// 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super) 300// 4.3 calls resolve_super_or_fail Super in parallel on own thread T2 301// 4.4 finds T2, Super -> throws class circularity 302// Must be called, even if superclass is null, since this is 303// where the placeholder entry is created which claims this 304// thread is loading this class/classloader. 305Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name, 306 Symbol* class_name, 307 Handle class_loader, 308 Handle protection_domain, 309 bool is_superclass, 310 TRAPS) { 311 // Double-check, if child class is already loaded, just return super-class,interface 312 // Don't add a placedholder if already loaded, i.e. already in system dictionary 313 // Make sure there's a placeholder for the *child* before resolving. 314 // Used as a claim that this thread is currently loading superclass/classloader 315 // Used here for ClassCircularity checks and also for heap verification 316 // (every InstanceKlass in the heap needs to be in the system dictionary 317 // or have a placeholder). 318 // Must check ClassCircularity before checking if super class is already loaded 319 // 320 // We might not already have a placeholder if this child_name was 321 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass); 322 // the name of the class might not be known until the stream is actually 323 // parsed. 324 // Bugs 4643874, 4715493 325 // compute_hash can have a safepoint 326 327 ClassLoaderData* loader_data = class_loader_data(class_loader); 328 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data); 329 int d_index = dictionary()->hash_to_index(d_hash); 330 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data); 331 int p_index = placeholders()->hash_to_index(p_hash); 332 // can't throw error holding a lock 333 bool child_already_loaded = false; 334 bool throw_circularity_error = false; 335 { 336 MutexLocker mu(SystemDictionary_lock, THREAD); 337 Klass* childk = find_class(d_index, d_hash, child_name, loader_data); 338 Klass* quicksuperk; 339 // to support // loading: if child done loading, just return superclass 340 // if class_name, & class_loader don't match: 341 // if initial define, SD update will give LinkageError 342 // if redefine: compare_class_versions will give HIERARCHY_CHANGED 343 // so we don't throw an exception here. 344 // see: nsk redefclass014 & java.lang.instrument Instrument032 345 if ((childk != NULL ) && (is_superclass) && 346 ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) && 347 348 ((quicksuperk->name() == class_name) && 349 (quicksuperk->class_loader() == class_loader()))) { 350 return quicksuperk; 351 } else { 352 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data); 353 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) { 354 throw_circularity_error = true; 355 } 356 } 357 if (!throw_circularity_error) { 358 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD); 359 } 360 } 361 if (throw_circularity_error) { 362 ResourceMark rm(THREAD); 363 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string()); 364 } 365 366// java.lang.Object should have been found above 367 assert(class_name != NULL, "null super class for resolving"); 368 // Resolve the super class or interface, check results on return 369 Klass* superk = SystemDictionary::resolve_or_null(class_name, 370 class_loader, 371 protection_domain, 372 THREAD); 373 374 KlassHandle superk_h(THREAD, superk); 375 376 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up 377 // It is no longer necessary to keep the placeholder table alive until update_dictionary 378 // or error. GC used to walk the placeholder table as strong roots. 379 // The instanceKlass is kept alive because the class loader is on the stack, 380 // which keeps the loader_data alive, as well as all instanceKlasses in 381 // the loader_data. parseClassFile adds the instanceKlass to loader_data. 382 { 383 MutexLocker mu(SystemDictionary_lock, THREAD); 384 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD); 385 SystemDictionary_lock->notify_all(); 386 } 387 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) { 388 // can null superk 389 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD)); 390 } 391 392 return superk_h(); 393} 394 395void SystemDictionary::validate_protection_domain(instanceKlassHandle klass, 396 Handle class_loader, 397 Handle protection_domain, 398 TRAPS) { 399 if(!has_checkPackageAccess()) return; 400 401 // Now we have to call back to java to check if the initating class has access 402 JavaValue result(T_VOID); 403 if (TraceProtectionDomainVerification) { 404 // Print out trace information 405 tty->print_cr("Checking package access"); 406 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr(); 407 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr(); 408 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr(); 409 } 410 411 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass()); 412 JavaCalls::call_special(&result, 413 class_loader, 414 system_loader, 415 vmSymbols::checkPackageAccess_name(), 416 vmSymbols::class_protectiondomain_signature(), 417 Handle(THREAD, klass->java_mirror()), 418 protection_domain, 419 THREAD); 420 421 if (TraceProtectionDomainVerification) { 422 if (HAS_PENDING_EXCEPTION) { 423 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!"); 424 } else { 425 tty->print_cr(" -> granted"); 426 } 427 tty->cr(); 428 } 429 430 if (HAS_PENDING_EXCEPTION) return; 431 432 // If no exception has been thrown, we have validated the protection domain 433 // Insert the protection domain of the initiating class into the set. 434 { 435 // We recalculate the entry here -- we've called out to java since 436 // the last time it was calculated. 437 ClassLoaderData* loader_data = class_loader_data(class_loader); 438 439 Symbol* kn = klass->name(); 440 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data); 441 int d_index = dictionary()->hash_to_index(d_hash); 442 443 MutexLocker mu(SystemDictionary_lock, THREAD); 444 { 445 // Note that we have an entry, and entries can be deleted only during GC, 446 // so we cannot allow GC to occur while we're holding this entry. 447 448 // We're using a No_Safepoint_Verifier to catch any place where we 449 // might potentially do a GC at all. 450 // Dictionary::do_unloading() asserts that classes in SD are only 451 // unloaded at a safepoint. Anonymous classes are not in SD. 452 No_Safepoint_Verifier nosafepoint; 453 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data, 454 protection_domain, THREAD); 455 } 456 } 457} 458 459// We only get here if this thread finds that another thread 460// has already claimed the placeholder token for the current operation, 461// but that other thread either never owned or gave up the 462// object lock 463// Waits on SystemDictionary_lock to indicate placeholder table updated 464// On return, caller must recheck placeholder table state 465// 466// We only get here if 467// 1) custom classLoader, i.e. not bootstrap classloader 468// 2) UnsyncloadClass not set 469// 3) custom classLoader has broken the class loader objectLock 470// so another thread got here in parallel 471// 472// lockObject must be held. 473// Complicated dance due to lock ordering: 474// Must first release the classloader object lock to 475// allow initial definer to complete the class definition 476// and to avoid deadlock 477// Reclaim classloader lock object with same original recursion count 478// Must release SystemDictionary_lock after notify, since 479// class loader lock must be claimed before SystemDictionary_lock 480// to prevent deadlocks 481// 482// The notify allows applications that did an untimed wait() on 483// the classloader object lock to not hang. 484void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) { 485 assert_lock_strong(SystemDictionary_lock); 486 487 bool calledholdinglock 488 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject); 489 assert(calledholdinglock,"must hold lock for notify"); 490 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait"); 491 ObjectSynchronizer::notifyall(lockObject, THREAD); 492 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD); 493 SystemDictionary_lock->wait(); 494 SystemDictionary_lock->unlock(); 495 ObjectSynchronizer::reenter(lockObject, recursions, THREAD); 496 SystemDictionary_lock->lock(); 497} 498 499// If the class in is in the placeholder table, class loading is in progress 500// For cases where the application changes threads to load classes, it 501// is critical to ClassCircularity detection that we try loading 502// the superclass on the same thread internally, so we do parallel 503// super class loading here. 504// This also is critical in cases where the original thread gets stalled 505// even in non-circularity situations. 506// Note: must call resolve_super_or_fail even if null super - 507// to force placeholder entry creation for this class for circularity detection 508// Caller must check for pending exception 509// Returns non-null Klass* if other thread has completed load 510// and we are done, 511// If return null Klass* and no pending exception, the caller must load the class 512instanceKlassHandle SystemDictionary::handle_parallel_super_load( 513 Symbol* name, Symbol* superclassname, Handle class_loader, 514 Handle protection_domain, Handle lockObject, TRAPS) { 515 516 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 517 ClassLoaderData* loader_data = class_loader_data(class_loader); 518 unsigned int d_hash = dictionary()->compute_hash(name, loader_data); 519 int d_index = dictionary()->hash_to_index(d_hash); 520 unsigned int p_hash = placeholders()->compute_hash(name, loader_data); 521 int p_index = placeholders()->hash_to_index(p_hash); 522 523 // superk is not used, resolve_super called for circularity check only 524 // This code is reached in two situations. One if this thread 525 // is loading the same class twice (e.g. ClassCircularity, or 526 // java.lang.instrument). 527 // The second is if another thread started the resolve_super first 528 // and has not yet finished. 529 // In both cases the original caller will clean up the placeholder 530 // entry on error. 531 Klass* superk = SystemDictionary::resolve_super_or_fail(name, 532 superclassname, 533 class_loader, 534 protection_domain, 535 true, 536 CHECK_(nh)); 537 538 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete 539 // Serial class loaders and bootstrap classloader do wait for superclass loads 540 if (!class_loader.is_null() && is_parallelCapable(class_loader)) { 541 MutexLocker mu(SystemDictionary_lock, THREAD); 542 // Check if classloading completed while we were loading superclass or waiting 543 Klass* check = find_class(d_index, d_hash, name, loader_data); 544 if (check != NULL) { 545 // Klass is already loaded, so just return it 546 return(instanceKlassHandle(THREAD, check)); 547 } else { 548 return nh; 549 } 550 } 551 552 // must loop to both handle other placeholder updates 553 // and spurious notifications 554 bool super_load_in_progress = true; 555 PlaceholderEntry* placeholder; 556 while (super_load_in_progress) { 557 MutexLocker mu(SystemDictionary_lock, THREAD); 558 // Check if classloading completed while we were loading superclass or waiting 559 Klass* check = find_class(d_index, d_hash, name, loader_data); 560 if (check != NULL) { 561 // Klass is already loaded, so just return it 562 return(instanceKlassHandle(THREAD, check)); 563 } else { 564 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 565 if (placeholder && placeholder->super_load_in_progress() ){ 566 // Before UnsyncloadClass: 567 // We only get here if the application has released the 568 // classloader lock when another thread was in the middle of loading a 569 // superclass/superinterface for this class, and now 570 // this thread is also trying to load this class. 571 // To minimize surprises, the first thread that started to 572 // load a class should be the one to complete the loading 573 // with the classfile it initially expected. 574 // This logic has the current thread wait once it has done 575 // all the superclass/superinterface loading it can, until 576 // the original thread completes the class loading or fails 577 // If it completes we will use the resulting InstanceKlass 578 // which we will find below in the systemDictionary. 579 // We also get here for parallel bootstrap classloader 580 if (class_loader.is_null()) { 581 SystemDictionary_lock->wait(); 582 } else { 583 double_lock_wait(lockObject, THREAD); 584 } 585 } else { 586 // If not in SD and not in PH, other thread's load must have failed 587 super_load_in_progress = false; 588 } 589 } 590 } 591 return (nh); 592} 593 594 595Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, 596 Handle class_loader, 597 Handle protection_domain, 598 TRAPS) { 599 assert(name != NULL && !FieldType::is_array(name) && 600 !FieldType::is_obj(name), "invalid class name"); 601 602 Ticks class_load_start_time = Ticks::now(); 603 604 // UseNewReflection 605 // Fix for 4474172; see evaluation for more details 606 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 607 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL); 608 609 // Do lookup to see if class already exist and the protection domain 610 // has the right access 611 // This call uses find which checks protection domain already matches 612 // All subsequent calls use find_class, and set has_loaded_class so that 613 // before we return a result we call out to java to check for valid protection domain 614 // to allow returning the Klass* and add it to the pd_set if it is valid 615 unsigned int d_hash = dictionary()->compute_hash(name, loader_data); 616 int d_index = dictionary()->hash_to_index(d_hash); 617 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data, 618 protection_domain, THREAD); 619 if (probe != NULL) return probe; 620 621 622 // Non-bootstrap class loaders will call out to class loader and 623 // define via jvm/jni_DefineClass which will acquire the 624 // class loader object lock to protect against multiple threads 625 // defining the class in parallel by accident. 626 // This lock must be acquired here so the waiter will find 627 // any successful result in the SystemDictionary and not attempt 628 // the define 629 // ParallelCapable Classloaders and the bootstrap classloader, 630 // or all classloaders with UnsyncloadClass do not acquire lock here 631 bool DoObjectLock = true; 632 if (is_parallelCapable(class_loader)) { 633 DoObjectLock = false; 634 } 635 636 unsigned int p_hash = placeholders()->compute_hash(name, loader_data); 637 int p_index = placeholders()->hash_to_index(p_hash); 638 639 // Class is not in SystemDictionary so we have to do loading. 640 // Make sure we are synchronized on the class loader before we proceed 641 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 642 check_loader_lock_contention(lockObject, THREAD); 643 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 644 645 // Check again (after locking) if class already exist in SystemDictionary 646 bool class_has_been_loaded = false; 647 bool super_load_in_progress = false; 648 bool havesupername = false; 649 instanceKlassHandle k; 650 PlaceholderEntry* placeholder; 651 Symbol* superclassname = NULL; 652 653 { 654 MutexLocker mu(SystemDictionary_lock, THREAD); 655 Klass* check = find_class(d_index, d_hash, name, loader_data); 656 if (check != NULL) { 657 // Klass is already loaded, so just return it 658 class_has_been_loaded = true; 659 k = instanceKlassHandle(THREAD, check); 660 } else { 661 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 662 if (placeholder && placeholder->super_load_in_progress()) { 663 super_load_in_progress = true; 664 if (placeholder->havesupername() == true) { 665 superclassname = placeholder->supername(); 666 havesupername = true; 667 } 668 } 669 } 670 } 671 672 // If the class is in the placeholder table, class loading is in progress 673 if (super_load_in_progress && havesupername==true) { 674 k = SystemDictionary::handle_parallel_super_load(name, superclassname, 675 class_loader, protection_domain, lockObject, THREAD); 676 if (HAS_PENDING_EXCEPTION) { 677 return NULL; 678 } 679 if (!k.is_null()) { 680 class_has_been_loaded = true; 681 } 682 } 683 684 bool throw_circularity_error = false; 685 if (!class_has_been_loaded) { 686 bool load_instance_added = false; 687 688 // add placeholder entry to record loading instance class 689 // Five cases: 690 // All cases need to prevent modifying bootclasssearchpath 691 // in parallel with a classload of same classname 692 // Redefineclasses uses existence of the placeholder for the duration 693 // of the class load to prevent concurrent redefinition of not completely 694 // defined classes. 695 // case 1. traditional classloaders that rely on the classloader object lock 696 // - no other need for LOAD_INSTANCE 697 // case 2. traditional classloaders that break the classloader object lock 698 // as a deadlock workaround. Detection of this case requires that 699 // this check is done while holding the classloader object lock, 700 // and that lock is still held when calling classloader's loadClass. 701 // For these classloaders, we ensure that the first requestor 702 // completes the load and other requestors wait for completion. 703 // case 3. UnsyncloadClass - don't use objectLocker 704 // With this flag, we allow parallel classloading of a 705 // class/classloader pair 706 // case4. Bootstrap classloader - don't own objectLocker 707 // This classloader supports parallelism at the classloader level, 708 // but only allows a single load of a class/classloader pair. 709 // No performance benefit and no deadlock issues. 710 // case 5. parallelCapable user level classloaders - without objectLocker 711 // Allow parallel classloading of a class/classloader pair 712 713 { 714 MutexLocker mu(SystemDictionary_lock, THREAD); 715 if (class_loader.is_null() || !is_parallelCapable(class_loader)) { 716 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 717 if (oldprobe) { 718 // only need check_seen_thread once, not on each loop 719 // 6341374 java/lang/Instrument with -Xcomp 720 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) { 721 throw_circularity_error = true; 722 } else { 723 // case 1: traditional: should never see load_in_progress. 724 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) { 725 726 // case 4: bootstrap classloader: prevent futile classloading, 727 // wait on first requestor 728 if (class_loader.is_null()) { 729 SystemDictionary_lock->wait(); 730 } else { 731 // case 2: traditional with broken classloader lock. wait on first 732 // requestor. 733 double_lock_wait(lockObject, THREAD); 734 } 735 // Check if classloading completed while we were waiting 736 Klass* check = find_class(d_index, d_hash, name, loader_data); 737 if (check != NULL) { 738 // Klass is already loaded, so just return it 739 k = instanceKlassHandle(THREAD, check); 740 class_has_been_loaded = true; 741 } 742 // check if other thread failed to load and cleaned up 743 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 744 } 745 } 746 } 747 } 748 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock 749 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try 750 // LOAD_INSTANCE in parallel 751 752 if (!throw_circularity_error && !class_has_been_loaded) { 753 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD); 754 load_instance_added = true; 755 // For class loaders that do not acquire the classloader object lock, 756 // if they did not catch another thread holding LOAD_INSTANCE, 757 // need a check analogous to the acquire ObjectLocker/find_class 758 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL 759 // one final check if the load has already completed 760 // class loaders holding the ObjectLock shouldn't find the class here 761 Klass* check = find_class(d_index, d_hash, name, loader_data); 762 if (check != NULL) { 763 // Klass is already loaded, so return it after checking/adding protection domain 764 k = instanceKlassHandle(THREAD, check); 765 class_has_been_loaded = true; 766 } 767 } 768 } 769 770 // must throw error outside of owning lock 771 if (throw_circularity_error) { 772 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup"); 773 ResourceMark rm(THREAD); 774 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string()); 775 } 776 777 if (!class_has_been_loaded) { 778 779 // Do actual loading 780 k = load_instance_class(name, class_loader, THREAD); 781 782 // For UnsyncloadClass only 783 // If they got a linkageError, check if a parallel class load succeeded. 784 // If it did, then for bytecode resolution the specification requires 785 // that we return the same result we did for the other thread, i.e. the 786 // successfully loaded InstanceKlass 787 // Should not get here for classloaders that support parallelism 788 // with the new cleaner mechanism, even with AllowParallelDefineClass 789 // Bootstrap goes through here to allow for an extra guarantee check 790 if (UnsyncloadClass || (class_loader.is_null())) { 791 if (k.is_null() && HAS_PENDING_EXCEPTION 792 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) { 793 MutexLocker mu(SystemDictionary_lock, THREAD); 794 Klass* check = find_class(d_index, d_hash, name, loader_data); 795 if (check != NULL) { 796 // Klass is already loaded, so just use it 797 k = instanceKlassHandle(THREAD, check); 798 CLEAR_PENDING_EXCEPTION; 799 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?"); 800 } 801 } 802 } 803 804 // If everything was OK (no exceptions, no null return value), and 805 // class_loader is NOT the defining loader, do a little more bookkeeping. 806 if (!HAS_PENDING_EXCEPTION && !k.is_null() && 807 k->class_loader() != class_loader()) { 808 809 check_constraints(d_index, d_hash, k, class_loader, false, THREAD); 810 811 // Need to check for a PENDING_EXCEPTION again; check_constraints 812 // can throw and doesn't use the CHECK macro. 813 if (!HAS_PENDING_EXCEPTION) { 814 { // Grabbing the Compile_lock prevents systemDictionary updates 815 // during compilations. 816 MutexLocker mu(Compile_lock, THREAD); 817 update_dictionary(d_index, d_hash, p_index, p_hash, 818 k, class_loader, THREAD); 819 } 820 821 if (JvmtiExport::should_post_class_load()) { 822 Thread *thread = THREAD; 823 assert(thread->is_Java_thread(), "thread->is_Java_thread()"); 824 JvmtiExport::post_class_load((JavaThread *) thread, k()); 825 } 826 } 827 } 828 } // load_instance_class loop 829 830 if (load_instance_added == true) { 831 // clean up placeholder entries for LOAD_INSTANCE success or error 832 // This brackets the SystemDictionary updates for both defining 833 // and initiating loaders 834 MutexLocker mu(SystemDictionary_lock, THREAD); 835 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD); 836 SystemDictionary_lock->notify_all(); 837 } 838 } 839 840 if (HAS_PENDING_EXCEPTION || k.is_null()) { 841 return NULL; 842 } 843 844 post_class_load_event(class_load_start_time, k, class_loader); 845 846#ifdef ASSERT 847 { 848 ClassLoaderData* loader_data = k->class_loader_data(); 849 MutexLocker mu(SystemDictionary_lock, THREAD); 850 Klass* kk = find_class(name, loader_data); 851 assert(kk == k(), "should be present in dictionary"); 852 } 853#endif 854 855 // return if the protection domain in NULL 856 if (protection_domain() == NULL) return k(); 857 858 // Check the protection domain has the right access 859 { 860 MutexLocker mu(SystemDictionary_lock, THREAD); 861 // Note that we have an entry, and entries can be deleted only during GC, 862 // so we cannot allow GC to occur while we're holding this entry. 863 // We're using a No_Safepoint_Verifier to catch any place where we 864 // might potentially do a GC at all. 865 // Dictionary::do_unloading() asserts that classes in SD are only 866 // unloaded at a safepoint. Anonymous classes are not in SD. 867 No_Safepoint_Verifier nosafepoint; 868 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name, 869 loader_data, 870 protection_domain)) { 871 return k(); 872 } 873 } 874 875 // Verify protection domain. If it fails an exception is thrown 876 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL); 877 878 return k(); 879} 880 881 882// This routine does not lock the system dictionary. 883// 884// Since readers don't hold a lock, we must make sure that system 885// dictionary entries are only removed at a safepoint (when only one 886// thread is running), and are added to in a safe way (all links must 887// be updated in an MT-safe manner). 888// 889// Callers should be aware that an entry could be added just after 890// _dictionary->bucket(index) is read here, so the caller will not see 891// the new entry. 892 893Klass* SystemDictionary::find(Symbol* class_name, 894 Handle class_loader, 895 Handle protection_domain, 896 TRAPS) { 897 898 // UseNewReflection 899 // The result of this call should be consistent with the result 900 // of the call to resolve_instance_class_or_null(). 901 // See evaluation 6790209 and 4474172 for more details. 902 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 903 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader()); 904 905 if (loader_data == NULL) { 906 // If the ClassLoaderData has not been setup, 907 // then the class loader has no entries in the dictionary. 908 return NULL; 909 } 910 911 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data); 912 int d_index = dictionary()->hash_to_index(d_hash); 913 914 { 915 // Note that we have an entry, and entries can be deleted only during GC, 916 // so we cannot allow GC to occur while we're holding this entry. 917 // We're using a No_Safepoint_Verifier to catch any place where we 918 // might potentially do a GC at all. 919 // Dictionary::do_unloading() asserts that classes in SD are only 920 // unloaded at a safepoint. Anonymous classes are not in SD. 921 No_Safepoint_Verifier nosafepoint; 922 return dictionary()->find(d_index, d_hash, class_name, loader_data, 923 protection_domain, THREAD); 924 } 925} 926 927 928// Look for a loaded instance or array klass by name. Do not do any loading. 929// return NULL in case of error. 930Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name, 931 Handle class_loader, 932 Handle protection_domain, 933 TRAPS) { 934 Klass* k = NULL; 935 assert(class_name != NULL, "class name must be non NULL"); 936 937 if (FieldType::is_array(class_name)) { 938 // The name refers to an array. Parse the name. 939 // dimension and object_key in FieldArrayInfo are assigned as a 940 // side-effect of this call 941 FieldArrayInfo fd; 942 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL)); 943 if (t != T_OBJECT) { 944 k = Universe::typeArrayKlassObj(t); 945 } else { 946 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD); 947 } 948 if (k != NULL) { 949 k = k->array_klass_or_null(fd.dimension()); 950 } 951 } else { 952 k = find(class_name, class_loader, protection_domain, THREAD); 953 } 954 return k; 955} 956 957// Note: this method is much like resolve_from_stream, but 958// updates no supplemental data structures. 959// TODO consolidate the two methods with a helper routine? 960Klass* SystemDictionary::parse_stream(Symbol* class_name, 961 Handle class_loader, 962 Handle protection_domain, 963 ClassFileStream* st, 964 KlassHandle host_klass, 965 GrowableArray<Handle>* cp_patches, 966 TRAPS) { 967 TempNewSymbol parsed_name = NULL; 968 969 Ticks class_load_start_time = Ticks::now(); 970 971 ClassLoaderData* loader_data; 972 if (host_klass.not_null()) { 973 // Create a new CLD for anonymous class, that uses the same class loader 974 // as the host_klass 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 k->set_host_klass(host_klass()); 1000 // If it's anonymous, initialize it now, since nobody else will. 1001 1002 { 1003 MutexLocker mu_r(Compile_lock, THREAD); 1004 1005 // Add to class hierarchy, initialize vtables, and do possible 1006 // deoptimizations. 1007 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block 1008 1009 // But, do not add to system dictionary. 1010 1011 // compiled code dependencies need to be validated anyway 1012 notice_modification(); 1013 } 1014 1015 // Rewrite and patch constant pool here. 1016 k->link_class(CHECK_NULL); 1017 if (cp_patches != NULL) { 1018 k->constants()->patch_resolved_references(cp_patches); 1019 } 1020 k->eager_initialize(CHECK_NULL); 1021 1022 // notify jvmti 1023 if (JvmtiExport::should_post_class_load()) { 1024 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1025 JvmtiExport::post_class_load((JavaThread *) THREAD, k()); 1026 } 1027 1028 post_class_load_event(class_load_start_time, k, class_loader); 1029 } 1030 assert(host_klass.not_null() || cp_patches == NULL, 1031 "cp_patches only found with host_klass"); 1032 1033 return k(); 1034} 1035 1036// Add a klass to the system from a stream (called by jni_DefineClass and 1037// JVM_DefineClass). 1038// Note: class_name can be NULL. In that case we do not know the name of 1039// the class until we have parsed the stream. 1040 1041Klass* SystemDictionary::resolve_from_stream(Symbol* class_name, 1042 Handle class_loader, 1043 Handle protection_domain, 1044 ClassFileStream* st, 1045 bool verify, 1046 TRAPS) { 1047 1048 // Classloaders that support parallelism, e.g. bootstrap classloader, 1049 // or all classloaders with UnsyncloadClass do not acquire lock here 1050 bool DoObjectLock = true; 1051 if (is_parallelCapable(class_loader)) { 1052 DoObjectLock = false; 1053 } 1054 1055 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL); 1056 1057 // Make sure we are synchronized on the class loader before we proceed 1058 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1059 check_loader_lock_contention(lockObject, THREAD); 1060 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 1061 1062 TempNewSymbol parsed_name = NULL; 1063 1064 // Parse the stream. Note that we do this even though this klass might 1065 // already be present in the SystemDictionary, otherwise we would not 1066 // throw potential ClassFormatErrors. 1067 // 1068 // Note: "name" is updated. 1069 1070 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name, 1071 loader_data, 1072 protection_domain, 1073 parsed_name, 1074 verify, 1075 THREAD); 1076 1077 const char* pkg = "java/"; 1078 if (!HAS_PENDING_EXCEPTION && 1079 !class_loader.is_null() && 1080 parsed_name != NULL && 1081 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) { 1082 // It is illegal to define classes in the "java." package from 1083 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader 1084 ResourceMark rm(THREAD); 1085 char* name = parsed_name->as_C_string(); 1086 char* index = strrchr(name, '/'); 1087 *index = '\0'; // chop to just the package name 1088 while ((index = strchr(name, '/')) != NULL) { 1089 *index = '.'; // replace '/' with '.' in package name 1090 } 1091 const char* fmt = "Prohibited package name: %s"; 1092 size_t len = strlen(fmt) + strlen(name); 1093 char* message = NEW_RESOURCE_ARRAY(char, len); 1094 jio_snprintf(message, len, fmt, name); 1095 Exceptions::_throw_msg(THREAD_AND_LOCATION, 1096 vmSymbols::java_lang_SecurityException(), message); 1097 } 1098 1099 if (!HAS_PENDING_EXCEPTION) { 1100 assert(parsed_name != NULL, "Sanity"); 1101 assert(class_name == NULL || class_name == parsed_name, "name mismatch"); 1102 // Verification prevents us from creating names with dots in them, this 1103 // asserts that that's the case. 1104 assert(is_internal_format(parsed_name), 1105 "external class name format used internally"); 1106 1107 // Add class just loaded 1108 // If a class loader supports parallel classloading handle parallel define requests 1109 // find_or_define_instance_class may return a different InstanceKlass 1110 if (is_parallelCapable(class_loader)) { 1111 k = find_or_define_instance_class(class_name, class_loader, k, THREAD); 1112 } else { 1113 define_instance_class(k, THREAD); 1114 } 1115 } 1116 1117 // Make sure we have an entry in the SystemDictionary on success 1118 debug_only( { 1119 if (!HAS_PENDING_EXCEPTION) { 1120 assert(parsed_name != NULL, "parsed_name is still null?"); 1121 Symbol* h_name = k->name(); 1122 ClassLoaderData *defining_loader_data = k->class_loader_data(); 1123 1124 MutexLocker mu(SystemDictionary_lock, THREAD); 1125 1126 Klass* check = find_class(parsed_name, loader_data); 1127 assert(check == k(), "should be present in the dictionary"); 1128 1129 Klass* check2 = find_class(h_name, defining_loader_data); 1130 assert(check == check2, "name inconsistancy in SystemDictionary"); 1131 } 1132 } ); 1133 1134 return k(); 1135} 1136 1137 1138void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length, 1139 int number_of_entries) { 1140 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>), 1141 "bad shared dictionary size."); 1142 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries); 1143} 1144 1145 1146// If there is a shared dictionary, then find the entry for the 1147// given shared system class, if any. 1148 1149Klass* SystemDictionary::find_shared_class(Symbol* class_name) { 1150 if (shared_dictionary() != NULL) { 1151 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL); 1152 int d_index = shared_dictionary()->hash_to_index(d_hash); 1153 1154 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name); 1155 } else { 1156 return NULL; 1157 } 1158} 1159 1160 1161// Load a class from the shared spaces (found through the shared system 1162// dictionary). Force the superclass and all interfaces to be loaded. 1163// Update the class definition to include sibling classes and no 1164// subclasses (yet). [Classes in the shared space are not part of the 1165// object hierarchy until loaded.] 1166 1167instanceKlassHandle SystemDictionary::load_shared_class( 1168 Symbol* class_name, Handle class_loader, TRAPS) { 1169 instanceKlassHandle ik (THREAD, find_shared_class(class_name)); 1170 return load_shared_class(ik, class_loader, THREAD); 1171} 1172 1173instanceKlassHandle SystemDictionary::load_shared_class( 1174 instanceKlassHandle ik, Handle class_loader, TRAPS) { 1175 assert(class_loader.is_null(), "non-null classloader for shared class?"); 1176 if (ik.not_null()) { 1177 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1178 Symbol* class_name = ik->name(); 1179 1180 // Found the class, now load the superclass and interfaces. If they 1181 // are shared, add them to the main system dictionary and reset 1182 // their hierarchy references (supers, subs, and interfaces). 1183 1184 if (ik->super() != NULL) { 1185 Symbol* cn = ik->super()->name(); 1186 resolve_super_or_fail(class_name, cn, 1187 class_loader, Handle(), true, CHECK_(nh)); 1188 } 1189 1190 Array<Klass*>* interfaces = ik->local_interfaces(); 1191 int num_interfaces = interfaces->length(); 1192 for (int index = 0; index < num_interfaces; index++) { 1193 Klass* k = interfaces->at(index); 1194 1195 // Note: can not use InstanceKlass::cast here because 1196 // interfaces' InstanceKlass's C++ vtbls haven't been 1197 // reinitialized yet (they will be once the interface classes 1198 // are loaded) 1199 Symbol* name = k->name(); 1200 resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(nh)); 1201 } 1202 1203 // Adjust methods to recover missing data. They need addresses for 1204 // interpreter entry points and their default native method address 1205 // must be reset. 1206 1207 // Updating methods must be done under a lock so multiple 1208 // threads don't update these in parallel 1209 // Shared classes are all currently loaded by the bootstrap 1210 // classloader, so this will never cause a deadlock on 1211 // a custom class loader lock. 1212 1213 { 1214 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1215 check_loader_lock_contention(lockObject, THREAD); 1216 ObjectLocker ol(lockObject, THREAD, true); 1217 ik->restore_unshareable_info(CHECK_(nh)); 1218 } 1219 1220 if (TraceClassLoading) { 1221 ResourceMark rm; 1222 tty->print("[Loaded %s", ik->external_name()); 1223 tty->print(" from shared objects file"); 1224 tty->print_cr("]"); 1225 } 1226 // notify a class loaded from shared object 1227 ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()), 1228 true /* shared class */); 1229 } 1230 return ik; 1231} 1232 1233 1234instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) { 1235 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1236 if (class_loader.is_null()) { 1237 1238 // Search the shared system dictionary for classes preloaded into the 1239 // shared spaces. 1240 instanceKlassHandle k; 1241 { 1242 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time()); 1243 k = load_shared_class(class_name, class_loader, THREAD); 1244 } 1245 1246 if (k.is_null()) { 1247 // Use VM class loader 1248 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time()); 1249 k = ClassLoader::load_classfile(class_name, CHECK_(nh)); 1250 } 1251 1252 // find_or_define_instance_class may return a different InstanceKlass 1253 if (!k.is_null()) { 1254 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh)); 1255 } 1256 return k; 1257 } else { 1258 // Use user specified class loader to load class. Call loadClass operation on class_loader. 1259 ResourceMark rm(THREAD); 1260 1261 assert(THREAD->is_Java_thread(), "must be a JavaThread"); 1262 JavaThread* jt = (JavaThread*) THREAD; 1263 1264 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(), 1265 ClassLoader::perf_app_classload_selftime(), 1266 ClassLoader::perf_app_classload_count(), 1267 jt->get_thread_stat()->perf_recursion_counts_addr(), 1268 jt->get_thread_stat()->perf_timers_addr(), 1269 PerfClassTraceTime::CLASS_LOAD); 1270 1271 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh)); 1272 // Translate to external class name format, i.e., convert '/' chars to '.' 1273 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh)); 1274 1275 JavaValue result(T_OBJECT); 1276 1277 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass()); 1278 1279 // Call public unsynchronized loadClass(String) directly for all class loaders 1280 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will 1281 // acquire a class-name based lock rather than the class loader object lock. 1282 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean), 1283 // so the call to loadClassInternal() was not required. 1284 // 1285 // UnsyncloadClass flag means both call loadClass(String) and do 1286 // not acquire the class loader lock even for class loaders that are 1287 // not parallelCapable. This was a risky transitional 1288 // flag for diagnostic purposes only. It is risky to call 1289 // custom class loaders without synchronization. 1290 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of 1291 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field. 1292 // Do NOT assume this will be supported in future releases. 1293 // 1294 // Added MustCallLoadClassInternal in case we discover in the field 1295 // a customer that counts on this call 1296 if (MustCallLoadClassInternal && has_loadClassInternal()) { 1297 JavaCalls::call_special(&result, 1298 class_loader, 1299 spec_klass, 1300 vmSymbols::loadClassInternal_name(), 1301 vmSymbols::string_class_signature(), 1302 string, 1303 CHECK_(nh)); 1304 } else { 1305 JavaCalls::call_virtual(&result, 1306 class_loader, 1307 spec_klass, 1308 vmSymbols::loadClass_name(), 1309 vmSymbols::string_class_signature(), 1310 string, 1311 CHECK_(nh)); 1312 } 1313 1314 assert(result.get_type() == T_OBJECT, "just checking"); 1315 oop obj = (oop) result.get_jobject(); 1316 1317 // Primitive classes return null since forName() can not be 1318 // used to obtain any of the Class objects representing primitives or void 1319 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) { 1320 instanceKlassHandle k = 1321 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj)); 1322 // For user defined Java class loaders, check that the name returned is 1323 // the same as that requested. This check is done for the bootstrap 1324 // loader when parsing the class file. 1325 if (class_name == k->name()) { 1326 return k; 1327 } 1328 } 1329 // Class is not found or has the wrong name, return NULL 1330 return nh; 1331 } 1332} 1333 1334void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) { 1335 1336 ClassLoaderData* loader_data = k->class_loader_data(); 1337 Handle class_loader_h(THREAD, loader_data->class_loader()); 1338 1339 for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){} 1340 1341 // for bootstrap and other parallel classloaders don't acquire lock, 1342 // use placeholder token 1343 // If a parallelCapable class loader calls define_instance_class instead of 1344 // find_or_define_instance_class to get here, we have a timing 1345 // hole with systemDictionary updates and check_constraints 1346 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) { 1347 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, 1348 compute_loader_lock_object(class_loader_h, THREAD)), 1349 "define called without lock"); 1350 } 1351 1352 // Check class-loading constraints. Throw exception if violation is detected. 1353 // Grabs and releases SystemDictionary_lock 1354 // The check_constraints/find_class call and update_dictionary sequence 1355 // must be "atomic" for a specific class/classloader pair so we never 1356 // define two different instanceKlasses for that class/classloader pair. 1357 // Existing classloaders will call define_instance_class with the 1358 // classloader lock held 1359 // Parallel classloaders will call find_or_define_instance_class 1360 // which will require a token to perform the define class 1361 Symbol* name_h = k->name(); 1362 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data); 1363 int d_index = dictionary()->hash_to_index(d_hash); 1364 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK); 1365 1366 // Register class just loaded with class loader (placed in Vector) 1367 // Note we do this before updating the dictionary, as this can 1368 // fail with an OutOfMemoryError (if it does, we will *not* put this 1369 // class in the dictionary and will not update the class hierarchy). 1370 // JVMTI FollowReferences needs to find the classes this way. 1371 if (k->class_loader() != NULL) { 1372 methodHandle m(THREAD, Universe::loader_addClass_method()); 1373 JavaValue result(T_VOID); 1374 JavaCallArguments args(class_loader_h); 1375 args.push_oop(Handle(THREAD, k->java_mirror())); 1376 JavaCalls::call(&result, m, &args, CHECK); 1377 } 1378 1379 // Add the new class. We need recompile lock during update of CHA. 1380 { 1381 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data); 1382 int p_index = placeholders()->hash_to_index(p_hash); 1383 1384 MutexLocker mu_r(Compile_lock, THREAD); 1385 1386 // Add to class hierarchy, initialize vtables, and do possible 1387 // deoptimizations. 1388 add_to_hierarchy(k, CHECK); // No exception, but can block 1389 1390 // Add to systemDictionary - so other classes can see it. 1391 // Grabs and releases SystemDictionary_lock 1392 update_dictionary(d_index, d_hash, p_index, p_hash, 1393 k, class_loader_h, THREAD); 1394 } 1395 k->eager_initialize(THREAD); 1396 1397 // notify jvmti 1398 if (JvmtiExport::should_post_class_load()) { 1399 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1400 JvmtiExport::post_class_load((JavaThread *) THREAD, k()); 1401 1402 } 1403 1404} 1405 1406// Support parallel classloading 1407// All parallel class loaders, including bootstrap classloader 1408// lock a placeholder entry for this class/class_loader pair 1409// to allow parallel defines of different classes for this class loader 1410// With AllowParallelDefine flag==true, in case they do not synchronize around 1411// FindLoadedClass/DefineClass, calls, we check for parallel 1412// loading for them, wait if a defineClass is in progress 1413// and return the initial requestor's results 1414// This flag does not apply to the bootstrap classloader. 1415// With AllowParallelDefine flag==false, call through to define_instance_class 1416// which will throw LinkageError: duplicate class definition. 1417// False is the requested default. 1418// For better performance, the class loaders should synchronize 1419// findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they 1420// potentially waste time reading and parsing the bytestream. 1421// Note: VM callers should ensure consistency of k/class_name,class_loader 1422instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) { 1423 1424 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1425 Symbol* name_h = k->name(); // passed in class_name may be null 1426 ClassLoaderData* loader_data = class_loader_data(class_loader); 1427 1428 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data); 1429 int d_index = dictionary()->hash_to_index(d_hash); 1430 1431// Hold SD lock around find_class and placeholder creation for DEFINE_CLASS 1432 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data); 1433 int p_index = placeholders()->hash_to_index(p_hash); 1434 PlaceholderEntry* probe; 1435 1436 { 1437 MutexLocker mu(SystemDictionary_lock, THREAD); 1438 // First check if class already defined 1439 if (UnsyncloadClass || (is_parallelDefine(class_loader))) { 1440 Klass* check = find_class(d_index, d_hash, name_h, loader_data); 1441 if (check != NULL) { 1442 return(instanceKlassHandle(THREAD, check)); 1443 } 1444 } 1445 1446 // Acquire define token for this class/classloader 1447 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD); 1448 // Wait if another thread defining in parallel 1449 // All threads wait - even those that will throw duplicate class: otherwise 1450 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails 1451 // if other thread has not finished updating dictionary 1452 while (probe->definer() != NULL) { 1453 SystemDictionary_lock->wait(); 1454 } 1455 // Only special cases allow parallel defines and can use other thread's results 1456 // Other cases fall through, and may run into duplicate defines 1457 // caught by finding an entry in the SystemDictionary 1458 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) { 1459 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1460 SystemDictionary_lock->notify_all(); 1461#ifdef ASSERT 1462 Klass* check = find_class(d_index, d_hash, name_h, loader_data); 1463 assert(check != NULL, "definer missed recording success"); 1464#endif 1465 return(instanceKlassHandle(THREAD, probe->instance_klass())); 1466 } else { 1467 // This thread will define the class (even if earlier thread tried and had an error) 1468 probe->set_definer(THREAD); 1469 } 1470 } 1471 1472 define_instance_class(k, THREAD); 1473 1474 Handle linkage_exception = Handle(); // null handle 1475 1476 // definer must notify any waiting threads 1477 { 1478 MutexLocker mu(SystemDictionary_lock, THREAD); 1479 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data); 1480 assert(probe != NULL, "DEFINE_CLASS placeholder lost?"); 1481 if (probe != NULL) { 1482 if (HAS_PENDING_EXCEPTION) { 1483 linkage_exception = Handle(THREAD,PENDING_EXCEPTION); 1484 CLEAR_PENDING_EXCEPTION; 1485 } else { 1486 probe->set_instance_klass(k()); 1487 } 1488 probe->set_definer(NULL); 1489 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1490 SystemDictionary_lock->notify_all(); 1491 } 1492 } 1493 1494 // Can't throw exception while holding lock due to rank ordering 1495 if (linkage_exception() != NULL) { 1496 THROW_OOP_(linkage_exception(), nh); // throws exception and returns 1497 } 1498 1499 return k; 1500} 1501Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) { 1502 // If class_loader is NULL we synchronize on _system_loader_lock_obj 1503 if (class_loader.is_null()) { 1504 return Handle(THREAD, _system_loader_lock_obj); 1505 } else { 1506 return class_loader; 1507 } 1508} 1509 1510// This method is added to check how often we have to wait to grab loader 1511// lock. The results are being recorded in the performance counters defined in 1512// ClassLoader::_sync_systemLoaderLockContentionRate and 1513// ClassLoader::_sync_nonSystemLoaderLockConteionRate. 1514void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) { 1515 if (!UsePerfData) { 1516 return; 1517 } 1518 1519 assert(!loader_lock.is_null(), "NULL lock object"); 1520 1521 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock) 1522 == ObjectSynchronizer::owner_other) { 1523 // contention will likely happen, so increment the corresponding 1524 // contention counter. 1525 if (loader_lock() == _system_loader_lock_obj) { 1526 ClassLoader::sync_systemLoaderLockContentionRate()->inc(); 1527 } else { 1528 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc(); 1529 } 1530 } 1531} 1532 1533// ---------------------------------------------------------------------------- 1534// Lookup 1535 1536Klass* SystemDictionary::find_class(int index, unsigned int hash, 1537 Symbol* class_name, 1538 ClassLoaderData* loader_data) { 1539 assert_locked_or_safepoint(SystemDictionary_lock); 1540 assert (index == dictionary()->index_for(class_name, loader_data), 1541 "incorrect index?"); 1542 1543 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data); 1544 return k; 1545} 1546 1547 1548// Basic find on classes in the midst of being loaded 1549Symbol* SystemDictionary::find_placeholder(Symbol* class_name, 1550 ClassLoaderData* loader_data) { 1551 assert_locked_or_safepoint(SystemDictionary_lock); 1552 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data); 1553 int p_index = placeholders()->hash_to_index(p_hash); 1554 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data); 1555} 1556 1557 1558// Used for assertions and verification only 1559Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) { 1560 #ifndef ASSERT 1561 guarantee(VerifyBeforeGC || 1562 VerifyDuringGC || 1563 VerifyBeforeExit || 1564 VerifyDuringStartup || 1565 VerifyAfterGC, "too expensive"); 1566 #endif 1567 assert_locked_or_safepoint(SystemDictionary_lock); 1568 1569 // First look in the loaded class array 1570 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data); 1571 int d_index = dictionary()->hash_to_index(d_hash); 1572 return find_class(d_index, d_hash, class_name, loader_data); 1573} 1574 1575 1576// Get the next class in the diictionary. 1577Klass* SystemDictionary::try_get_next_class() { 1578 return dictionary()->try_get_next_class(); 1579} 1580 1581 1582// ---------------------------------------------------------------------------- 1583// Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock 1584// is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in 1585// before a new class is used. 1586 1587void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) { 1588 assert(k.not_null(), "just checking"); 1589 assert_locked_or_safepoint(Compile_lock); 1590 1591 // Link into hierachy. Make sure the vtables are initialized before linking into 1592 k->append_to_sibling_list(); // add to superklass/sibling list 1593 k->process_interfaces(THREAD); // handle all "implements" declarations 1594 k->set_init_state(InstanceKlass::loaded); 1595 // Now flush all code that depended on old class hierarchy. 1596 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97) 1597 // Also, first reinitialize vtable because it may have gotten out of synch 1598 // while the new class wasn't connected to the class hierarchy. 1599 Universe::flush_dependents_on(k); 1600} 1601 1602 1603// ---------------------------------------------------------------------------- 1604// GC support 1605 1606// Following roots during mark-sweep is separated in two phases. 1607// 1608// The first phase follows preloaded classes and all other system 1609// classes, since these will never get unloaded anyway. 1610// 1611// The second phase removes (unloads) unreachable classes from the 1612// system dictionary and follows the remaining classes' contents. 1613 1614void SystemDictionary::always_strong_oops_do(OopClosure* blk) { 1615 blk->do_oop(&_java_system_loader); 1616 blk->do_oop(&_system_loader_lock_obj); 1617 1618 dictionary()->always_strong_oops_do(blk); 1619 1620 // Visit extra methods 1621 invoke_method_table()->oops_do(blk); 1622} 1623 1624void SystemDictionary::always_strong_classes_do(KlassClosure* closure) { 1625 // Follow all system classes and temporary placeholders in dictionary 1626 dictionary()->always_strong_classes_do(closure); 1627 1628 // Placeholders. These represent classes we're actively loading. 1629 placeholders()->classes_do(closure); 1630} 1631 1632// Calculate a "good" systemdictionary size based 1633// on predicted or current loaded classes count 1634int SystemDictionary::calculate_systemdictionary_size(int classcount) { 1635 int newsize = _old_default_sdsize; 1636 if ((classcount > 0) && !DumpSharedSpaces) { 1637 int desiredsize = classcount/_average_depth_goal; 1638 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1; 1639 newsize = _primelist[++_sdgeneration]) { 1640 if (desiredsize <= newsize) { 1641 break; 1642 } 1643 } 1644 } 1645 return newsize; 1646} 1647 1648#ifdef ASSERT 1649class VerifySDReachableAndLiveClosure : public OopClosure { 1650private: 1651 BoolObjectClosure* _is_alive; 1652 1653 template <class T> void do_oop_work(T* p) { 1654 oop obj = oopDesc::load_decode_heap_oop(p); 1655 guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live"); 1656 } 1657 1658public: 1659 VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { } 1660 1661 virtual void do_oop(oop* p) { do_oop_work(p); } 1662 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 1663}; 1664#endif 1665 1666// Assumes classes in the SystemDictionary are only unloaded at a safepoint 1667// Note: anonymous classes are not in the SD. 1668bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) { 1669 // First, mark for unload all ClassLoaderData referencing a dead class loader. 1670 bool has_dead_loaders = ClassLoaderDataGraph::do_unloading(is_alive); 1671 bool unloading_occurred = false; 1672 if (has_dead_loaders) { 1673 unloading_occurred = dictionary()->do_unloading(); 1674 constraints()->purge_loader_constraints(); 1675 resolution_errors()->purge_resolution_errors(); 1676 } 1677 // Oops referenced by the system dictionary may get unreachable independently 1678 // of the class loader (eg. cached protection domain oops). So we need to 1679 // explicitly unlink them here instead of in Dictionary::do_unloading. 1680 dictionary()->unlink(is_alive); 1681#ifdef ASSERT 1682 VerifySDReachableAndLiveClosure cl(is_alive); 1683 dictionary()->oops_do(&cl); 1684#endif 1685 return unloading_occurred; 1686} 1687 1688void SystemDictionary::oops_do(OopClosure* f) { 1689 f->do_oop(&_java_system_loader); 1690 f->do_oop(&_system_loader_lock_obj); 1691 1692 // Adjust dictionary 1693 dictionary()->oops_do(f); 1694 1695 // Visit extra methods 1696 invoke_method_table()->oops_do(f); 1697} 1698 1699// Extended Class redefinition support. 1700// If one of these classes is replaced, we need to replace it in these places. 1701// KlassClosure::do_klass should take the address of a class but we can 1702// change that later. 1703void SystemDictionary::preloaded_classes_do(KlassClosure* f) { 1704 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) { 1705 f->do_klass(_well_known_klasses[k]); 1706 } 1707 1708 { 1709 for (int i = 0; i < T_VOID+1; i++) { 1710 if (_box_klasses[i] != NULL) { 1711 assert(i >= T_BOOLEAN, "checking"); 1712 f->do_klass(_box_klasses[i]); 1713 } 1714 } 1715 } 1716 1717 FilteredFieldsMap::classes_do(f); 1718} 1719 1720void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) { 1721 f->do_klass(_abstract_ownable_synchronizer_klass); 1722} 1723 1724// Just the classes from defining class loaders 1725// Don't iterate over placeholders 1726void SystemDictionary::classes_do(void f(Klass*)) { 1727 dictionary()->classes_do(f); 1728} 1729 1730// Added for initialize_itable_for_klass 1731// Just the classes from defining class loaders 1732// Don't iterate over placeholders 1733void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) { 1734 dictionary()->classes_do(f, CHECK); 1735} 1736 1737// All classes, and their class loaders 1738// Don't iterate over placeholders 1739void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) { 1740 dictionary()->classes_do(f); 1741} 1742 1743void SystemDictionary::placeholders_do(void f(Symbol*)) { 1744 placeholders()->entries_do(f); 1745} 1746 1747void SystemDictionary::methods_do(void f(Method*)) { 1748 dictionary()->methods_do(f); 1749 invoke_method_table()->methods_do(f); 1750} 1751 1752// ---------------------------------------------------------------------------- 1753// Lazily load klasses 1754 1755void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) { 1756 assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later"); 1757 1758 // if multiple threads calling this function, only one thread will load 1759 // the class. The other threads will find the loaded version once the 1760 // class is loaded. 1761 Klass* aos = _abstract_ownable_synchronizer_klass; 1762 if (aos == NULL) { 1763 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK); 1764 // Force a fence to prevent any read before the write completes 1765 OrderAccess::fence(); 1766 _abstract_ownable_synchronizer_klass = k; 1767 } 1768} 1769 1770// ---------------------------------------------------------------------------- 1771// Initialization 1772 1773void SystemDictionary::initialize(TRAPS) { 1774 // Allocate arrays 1775 assert(dictionary() == NULL, 1776 "SystemDictionary should only be initialized once"); 1777 _sdgeneration = 0; 1778 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount)); 1779 _placeholders = new PlaceholderTable(_nof_buckets); 1780 _number_of_modifications = 0; 1781 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size); 1782 _resolution_errors = new ResolutionErrorTable(_resolution_error_size); 1783 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size); 1784 1785 // Allocate private object used as system class loader lock 1786 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK); 1787 // Initialize basic classes 1788 initialize_preloaded_classes(CHECK); 1789} 1790 1791// Compact table of directions on the initialization of klasses: 1792static const short wk_init_info[] = { 1793 #define WK_KLASS_INIT_INFO(name, symbol, option) \ 1794 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \ 1795 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \ 1796 | (int)SystemDictionary::option ), 1797 WK_KLASSES_DO(WK_KLASS_INIT_INFO) 1798 #undef WK_KLASS_INIT_INFO 1799 0 1800}; 1801 1802bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) { 1803 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 1804 int info = wk_init_info[id - FIRST_WKID]; 1805 int sid = (info >> CEIL_LG_OPTION_LIMIT); 1806 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid); 1807 Klass** klassp = &_well_known_klasses[id]; 1808 bool must_load = (init_opt < SystemDictionary::Opt); 1809 if ((*klassp) == NULL) { 1810 if (must_load) { 1811 (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class 1812 } else { 1813 (*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass 1814 } 1815 } 1816 return ((*klassp) != NULL); 1817} 1818 1819void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) { 1820 assert((int)start_id <= (int)limit_id, "IDs are out of order!"); 1821 for (int id = (int)start_id; id < (int)limit_id; id++) { 1822 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 1823 int info = wk_init_info[id - FIRST_WKID]; 1824 int sid = (info >> CEIL_LG_OPTION_LIMIT); 1825 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT)); 1826 1827 initialize_wk_klass((WKID)id, opt, CHECK); 1828 } 1829 1830 // move the starting value forward to the limit: 1831 start_id = limit_id; 1832} 1833 1834void SystemDictionary::initialize_preloaded_classes(TRAPS) { 1835 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once"); 1836 // Preload commonly used klasses 1837 WKID scan = FIRST_WKID; 1838 // first do Object, then String, Class 1839 if (UseSharedSpaces) { 1840 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK); 1841 // Initialize the constant pool for the Object_class 1842 InstanceKlass* ik = InstanceKlass::cast(Object_klass()); 1843 ik->constants()->restore_unshareable_info(CHECK); 1844 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 1845 } else { 1846 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 1847 } 1848 1849 // Calculate offsets for String and Class classes since they are loaded and 1850 // can be used after this point. 1851 java_lang_String::compute_offsets(); 1852 java_lang_Class::compute_offsets(); 1853 1854 // Fixup mirrors for classes loaded before java.lang.Class. 1855 // These calls iterate over the objects currently in the perm gen 1856 // so calling them at this point is matters (not before when there 1857 // are fewer objects and not later after there are more objects 1858 // in the perm gen. 1859 Universe::initialize_basic_type_mirrors(CHECK); 1860 Universe::fixup_mirrors(CHECK); 1861 1862 // do a bunch more: 1863 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK); 1864 1865 // Preload ref klasses and set reference types 1866 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER); 1867 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass)); 1868 1869 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK); 1870 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT); 1871 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK); 1872 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL); 1873 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM); 1874 1875 // JSR 292 classes 1876 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass); 1877 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass); 1878 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK); 1879 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK); 1880 initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK); 1881 1882 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass); 1883 _box_klasses[T_CHAR] = WK_KLASS(Character_klass); 1884 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass); 1885 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass); 1886 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass); 1887 _box_klasses[T_SHORT] = WK_KLASS(Short_klass); 1888 _box_klasses[T_INT] = WK_KLASS(Integer_klass); 1889 _box_klasses[T_LONG] = WK_KLASS(Long_klass); 1890 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass); 1891 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass); 1892 1893 { // Compute whether we should use loadClass or loadClassInternal when loading classes. 1894 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature()); 1895 _has_loadClassInternal = (method != NULL); 1896 } 1897 { // Compute whether we should use checkPackageAccess or NOT 1898 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature()); 1899 _has_checkPackageAccess = (method != NULL); 1900 } 1901} 1902 1903// Tells if a given klass is a box (wrapper class, such as java.lang.Integer). 1904// If so, returns the basic type it holds. If not, returns T_OBJECT. 1905BasicType SystemDictionary::box_klass_type(Klass* k) { 1906 assert(k != NULL, ""); 1907 for (int i = T_BOOLEAN; i < T_VOID+1; i++) { 1908 if (_box_klasses[i] == k) 1909 return (BasicType)i; 1910 } 1911 return T_OBJECT; 1912} 1913 1914// Constraints on class loaders. The details of the algorithm can be 1915// found in the OOPSLA'98 paper "Dynamic Class Loading in the Java 1916// Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is 1917// that the system dictionary needs to maintain a set of contraints that 1918// must be satisfied by all classes in the dictionary. 1919// if defining is true, then LinkageError if already in systemDictionary 1920// if initiating loader, then ok if InstanceKlass matches existing entry 1921 1922void SystemDictionary::check_constraints(int d_index, unsigned int d_hash, 1923 instanceKlassHandle k, 1924 Handle class_loader, bool defining, 1925 TRAPS) { 1926 const char *linkage_error = NULL; 1927 { 1928 Symbol* name = k->name(); 1929 ClassLoaderData *loader_data = class_loader_data(class_loader); 1930 1931 MutexLocker mu(SystemDictionary_lock, THREAD); 1932 1933 Klass* check = find_class(d_index, d_hash, name, loader_data); 1934 if (check != (Klass*)NULL) { 1935 // if different InstanceKlass - duplicate class definition, 1936 // else - ok, class loaded by a different thread in parallel, 1937 // we should only have found it if it was done loading and ok to use 1938 // system dictionary only holds instance classes, placeholders 1939 // also holds array classes 1940 1941 assert(check->oop_is_instance(), "noninstance in systemdictionary"); 1942 if ((defining == true) || (k() != check)) { 1943 linkage_error = "loader (instance of %s): attempted duplicate class " 1944 "definition for name: \"%s\""; 1945 } else { 1946 return; 1947 } 1948 } 1949 1950#ifdef ASSERT 1951 Symbol* ph_check = find_placeholder(name, loader_data); 1952 assert(ph_check == NULL || ph_check == name, "invalid symbol"); 1953#endif 1954 1955 if (linkage_error == NULL) { 1956 if (constraints()->check_or_update(k, class_loader, name) == false) { 1957 linkage_error = "loader constraint violation: loader (instance of %s)" 1958 " previously initiated loading for a different type with name \"%s\""; 1959 } 1960 } 1961 } 1962 1963 // Throw error now if needed (cannot throw while holding 1964 // SystemDictionary_lock because of rank ordering) 1965 1966 if (linkage_error) { 1967 ResourceMark rm(THREAD); 1968 const char* class_loader_name = loader_name(class_loader()); 1969 char* type_name = k->name()->as_C_string(); 1970 size_t buflen = strlen(linkage_error) + strlen(class_loader_name) + 1971 strlen(type_name); 1972 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 1973 jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name); 1974 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 1975 } 1976} 1977 1978 1979// Update system dictionary - done after check_constraint and add_to_hierachy 1980// have been called. 1981void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash, 1982 int p_index, unsigned int p_hash, 1983 instanceKlassHandle k, 1984 Handle class_loader, 1985 TRAPS) { 1986 // Compile_lock prevents systemDictionary updates during compilations 1987 assert_locked_or_safepoint(Compile_lock); 1988 Symbol* name = k->name(); 1989 ClassLoaderData *loader_data = class_loader_data(class_loader); 1990 1991 { 1992 MutexLocker mu1(SystemDictionary_lock, THREAD); 1993 1994 // See whether biased locking is enabled and if so set it for this 1995 // klass. 1996 // Note that this must be done past the last potential blocking 1997 // point / safepoint. We enable biased locking lazily using a 1998 // VM_Operation to iterate the SystemDictionary and installing the 1999 // biasable mark word into each InstanceKlass's prototype header. 2000 // To avoid race conditions where we accidentally miss enabling the 2001 // optimization for one class in the process of being added to the 2002 // dictionary, we must not safepoint after the test of 2003 // BiasedLocking::enabled(). 2004 if (UseBiasedLocking && BiasedLocking::enabled()) { 2005 // Set biased locking bit for all loaded classes; it will be 2006 // cleared if revocation occurs too often for this type 2007 // NOTE that we must only do this when the class is initally 2008 // defined, not each time it is referenced from a new class loader 2009 if (k->class_loader() == class_loader()) { 2010 k->set_prototype_header(markOopDesc::biased_locking_prototype()); 2011 } 2012 } 2013 2014 // Make a new system dictionary entry. 2015 Klass* sd_check = find_class(d_index, d_hash, name, loader_data); 2016 if (sd_check == NULL) { 2017 dictionary()->add_klass(name, loader_data, k); 2018 notice_modification(); 2019 } 2020#ifdef ASSERT 2021 sd_check = find_class(d_index, d_hash, name, loader_data); 2022 assert (sd_check != NULL, "should have entry in system dictionary"); 2023 // Note: there may be a placeholder entry: for circularity testing 2024 // or for parallel defines 2025#endif 2026 SystemDictionary_lock->notify_all(); 2027 } 2028} 2029 2030 2031// Try to find a class name using the loader constraints. The 2032// loader constraints might know about a class that isn't fully loaded 2033// yet and these will be ignored. 2034Klass* SystemDictionary::find_constrained_instance_or_array_klass( 2035 Symbol* class_name, Handle class_loader, TRAPS) { 2036 2037 // First see if it has been loaded directly. 2038 // Force the protection domain to be null. (This removes protection checks.) 2039 Handle no_protection_domain; 2040 Klass* klass = find_instance_or_array_klass(class_name, class_loader, 2041 no_protection_domain, CHECK_NULL); 2042 if (klass != NULL) 2043 return klass; 2044 2045 // Now look to see if it has been loaded elsewhere, and is subject to 2046 // a loader constraint that would require this loader to return the 2047 // klass that is already loaded. 2048 if (FieldType::is_array(class_name)) { 2049 // For array classes, their Klass*s are not kept in the 2050 // constraint table. The element Klass*s are. 2051 FieldArrayInfo fd; 2052 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL)); 2053 if (t != T_OBJECT) { 2054 klass = Universe::typeArrayKlassObj(t); 2055 } else { 2056 MutexLocker mu(SystemDictionary_lock, THREAD); 2057 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader); 2058 } 2059 // If element class already loaded, allocate array klass 2060 if (klass != NULL) { 2061 klass = klass->array_klass_or_null(fd.dimension()); 2062 } 2063 } else { 2064 MutexLocker mu(SystemDictionary_lock, THREAD); 2065 // Non-array classes are easy: simply check the constraint table. 2066 klass = constraints()->find_constrained_klass(class_name, class_loader); 2067 } 2068 2069 return klass; 2070} 2071 2072 2073bool SystemDictionary::add_loader_constraint(Symbol* class_name, 2074 Handle class_loader1, 2075 Handle class_loader2, 2076 Thread* THREAD) { 2077 ClassLoaderData* loader_data1 = class_loader_data(class_loader1); 2078 ClassLoaderData* loader_data2 = class_loader_data(class_loader2); 2079 2080 Symbol* constraint_name = NULL; 2081 if (!FieldType::is_array(class_name)) { 2082 constraint_name = class_name; 2083 } else { 2084 // For array classes, their Klass*s are not kept in the 2085 // constraint table. The element classes are. 2086 FieldArrayInfo fd; 2087 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false)); 2088 // primitive types always pass 2089 if (t != T_OBJECT) { 2090 return true; 2091 } else { 2092 constraint_name = fd.object_key(); 2093 } 2094 } 2095 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1); 2096 int d_index1 = dictionary()->hash_to_index(d_hash1); 2097 2098 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2); 2099 int d_index2 = dictionary()->hash_to_index(d_hash2); 2100 { 2101 MutexLocker mu_s(SystemDictionary_lock, THREAD); 2102 2103 // Better never do a GC while we're holding these oops 2104 No_Safepoint_Verifier nosafepoint; 2105 2106 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1); 2107 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2); 2108 return constraints()->add_entry(constraint_name, klass1, class_loader1, 2109 klass2, class_loader2); 2110 } 2111} 2112 2113// Add entry to resolution error table to record the error when the first 2114// attempt to resolve a reference to a class has failed. 2115void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) { 2116 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2117 int index = resolution_errors()->hash_to_index(hash); 2118 { 2119 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2120 resolution_errors()->add_entry(index, hash, pool, which, error); 2121 } 2122} 2123 2124// Delete a resolution error for RedefineClasses for a constant pool is going away 2125void SystemDictionary::delete_resolution_error(ConstantPool* pool) { 2126 resolution_errors()->delete_entry(pool); 2127} 2128 2129// Lookup resolution error table. Returns error if found, otherwise NULL. 2130Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) { 2131 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2132 int index = resolution_errors()->hash_to_index(hash); 2133 { 2134 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2135 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which); 2136 return (entry != NULL) ? entry->error() : (Symbol*)NULL; 2137 } 2138} 2139 2140 2141// Signature constraints ensure that callers and callees agree about 2142// the meaning of type names in their signatures. This routine is the 2143// intake for constraints. It collects them from several places: 2144// 2145// * LinkResolver::resolve_method (if check_access is true) requires 2146// that the resolving class (the caller) and the defining class of 2147// the resolved method (the callee) agree on each type in the 2148// method's signature. 2149// 2150// * LinkResolver::resolve_interface_method performs exactly the same 2151// checks. 2152// 2153// * LinkResolver::resolve_field requires that the constant pool 2154// attempting to link to a field agree with the field's defining 2155// class about the type of the field signature. 2156// 2157// * klassVtable::initialize_vtable requires that, when a class 2158// overrides a vtable entry allocated by a superclass, that the 2159// overriding method (i.e., the callee) agree with the superclass 2160// on each type in the method's signature. 2161// 2162// * klassItable::initialize_itable requires that, when a class fills 2163// in its itables, for each non-abstract method installed in an 2164// itable, the method (i.e., the callee) agree with the interface 2165// on each type in the method's signature. 2166// 2167// All those methods have a boolean (check_access, checkconstraints) 2168// which turns off the checks. This is used from specialized contexts 2169// such as bootstrapping, dumping, and debugging. 2170// 2171// No direct constraint is placed between the class and its 2172// supertypes. Constraints are only placed along linked relations 2173// between callers and callees. When a method overrides or implements 2174// an abstract method in a supertype (superclass or interface), the 2175// constraints are placed as if the supertype were the caller to the 2176// overriding method. (This works well, since callers to the 2177// supertype have already established agreement between themselves and 2178// the supertype.) As a result of all this, a class can disagree with 2179// its supertype about the meaning of a type name, as long as that 2180// class neither calls a relevant method of the supertype, nor is 2181// called (perhaps via an override) from the supertype. 2182// 2183// 2184// SystemDictionary::check_signature_loaders(sig, l1, l2) 2185// 2186// Make sure all class components (including arrays) in the given 2187// signature will be resolved to the same class in both loaders. 2188// Returns the name of the type that failed a loader constraint check, or 2189// NULL if no constraint failed. No exception except OOME is thrown. 2190// Arrays are not added to the loader constraint table, their elements are. 2191Symbol* SystemDictionary::check_signature_loaders(Symbol* signature, 2192 Handle loader1, Handle loader2, 2193 bool is_method, TRAPS) { 2194 // Nothing to do if loaders are the same. 2195 if (loader1() == loader2()) { 2196 return NULL; 2197 } 2198 2199 SignatureStream sig_strm(signature, is_method); 2200 while (!sig_strm.is_done()) { 2201 if (sig_strm.is_object()) { 2202 Symbol* sig = sig_strm.as_symbol(CHECK_NULL); 2203 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) { 2204 return sig; 2205 } 2206 } 2207 sig_strm.next(); 2208 } 2209 return NULL; 2210} 2211 2212 2213methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid, 2214 Symbol* signature, 2215 TRAPS) { 2216 methodHandle empty; 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(!THREAD->is_Compiler_thread(), ""); 2291 Handle method_type = 2292 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty)); 2293 if (false) { // FIXME: Decide if the Java upcall should resolve signatures. 2294 method_type = java_lang_String::create_from_symbol(signature, CHECK_(empty)); 2295 } 2296 2297 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass(); 2298 int ref_kind = JVM_REF_invokeVirtual; 2299 Handle name_str = StringTable::intern(name, CHECK_(empty)); 2300 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty)); 2301 assert(appendix_box->obj_at(0) == NULL, ""); 2302 2303 // This should not happen. JDK code should take care of that. 2304 if (accessing_klass.is_null() || method_type.is_null()) { 2305 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty); 2306 } 2307 2308 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName 2309 JavaCallArguments args; 2310 args.push_oop(accessing_klass()->java_mirror()); 2311 args.push_int(ref_kind); 2312 args.push_oop(mh_klass()->java_mirror()); 2313 args.push_oop(name_str()); 2314 args.push_oop(method_type()); 2315 args.push_oop(appendix_box()); 2316 JavaValue result(T_OBJECT); 2317 JavaCalls::call_static(&result, 2318 SystemDictionary::MethodHandleNatives_klass(), 2319 vmSymbols::linkMethod_name(), 2320 vmSymbols::linkMethod_signature(), 2321 &args, CHECK_(empty)); 2322 Handle mname(THREAD, (oop) result.get_jobject()); 2323 (*method_type_result) = method_type; 2324 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD); 2325} 2326 2327 2328// Ask Java code to find or construct a java.lang.invoke.MethodType for the given 2329// signature, as interpreted relative to the given class loader. 2330// Because of class loader constraints, all method handle usage must be 2331// consistent with this loader. 2332Handle SystemDictionary::find_method_handle_type(Symbol* signature, 2333 KlassHandle accessing_klass, 2334 TRAPS) { 2335 Handle empty; 2336 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics 2337 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid); 2338 int index = invoke_method_table()->hash_to_index(hash); 2339 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2340 if (spe != NULL && spe->method_type() != NULL) { 2341 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), ""); 2342 return Handle(THREAD, spe->method_type()); 2343 } else if (THREAD->is_Compiler_thread()) { 2344 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME 2345 return Handle(); // do not attempt from within compiler, unless it was cached 2346 } 2347 2348 Handle class_loader, protection_domain; 2349 bool is_on_bcp = true; // keep this true as long as we can materialize from the boot classloader 2350 int npts = ArgumentCount(signature).size(); 2351 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty)); 2352 int arg = 0; 2353 Handle rt; // the return type from the signature 2354 ResourceMark rm(THREAD); 2355 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) { 2356 oop mirror = NULL; 2357 if (is_on_bcp) { 2358 // Note: class_loader & protection_domain are both null at this point. 2359 mirror = ss.as_java_mirror(class_loader, protection_domain, 2360 SignatureStream::ReturnNull, CHECK_(empty)); 2361 if (mirror == NULL) { 2362 // fall back from BCP to accessing_klass 2363 if (accessing_klass.not_null()) { 2364 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader()); 2365 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain()); 2366 } 2367 is_on_bcp = false; 2368 } 2369 } 2370 if (!is_on_bcp) { 2371 // Resolve, throwing a real error if it doesn't work. 2372 mirror = ss.as_java_mirror(class_loader, protection_domain, 2373 SignatureStream::NCDFError, CHECK_(empty)); 2374 } 2375 if (ss.at_return_type()) 2376 rt = Handle(THREAD, mirror); 2377 else 2378 pts->obj_at_put(arg++, mirror); 2379 2380 // Check accessibility. 2381 if (ss.is_object() && accessing_klass.not_null()) { 2382 Klass* sel_klass = java_lang_Class::as_Klass(mirror); 2383 mirror = NULL; // safety 2384 // Emulate ConstantPool::verify_constant_pool_resolve. 2385 if (sel_klass->oop_is_objArray()) 2386 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass(); 2387 if (sel_klass->oop_is_instance()) { 2388 KlassHandle sel_kh(THREAD, sel_klass); 2389 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty)); 2390 } 2391 } 2392 } 2393 assert(arg == npts, ""); 2394 2395 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType 2396 JavaCallArguments args(Handle(THREAD, rt())); 2397 args.push_oop(pts()); 2398 JavaValue result(T_OBJECT); 2399 JavaCalls::call_static(&result, 2400 SystemDictionary::MethodHandleNatives_klass(), 2401 vmSymbols::findMethodHandleType_name(), 2402 vmSymbols::findMethodHandleType_signature(), 2403 &args, CHECK_(empty)); 2404 Handle method_type(THREAD, (oop) result.get_jobject()); 2405 2406 if (is_on_bcp) { 2407 // We can cache this MethodType inside the JVM. 2408 MutexLocker ml(SystemDictionary_lock, THREAD); 2409 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2410 if (spe == NULL) 2411 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid); 2412 if (spe->method_type() == NULL) { 2413 spe->set_method_type(method_type()); 2414 } 2415 } 2416 2417 // report back to the caller with the MethodType 2418 return method_type; 2419} 2420 2421// Ask Java code to find or construct a method handle constant. 2422Handle SystemDictionary::link_method_handle_constant(KlassHandle caller, 2423 int ref_kind, //e.g., JVM_REF_invokeVirtual 2424 KlassHandle callee, 2425 Symbol* name_sym, 2426 Symbol* signature, 2427 TRAPS) { 2428 Handle empty; 2429 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty)); 2430 Handle type; 2431 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') { 2432 type = find_method_handle_type(signature, caller, CHECK_(empty)); 2433 } else if (caller.is_null()) { 2434 // This should not happen. JDK code should take care of that. 2435 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty); 2436 } else { 2437 ResourceMark rm(THREAD); 2438 SignatureStream ss(signature, false); 2439 if (!ss.is_done()) { 2440 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(), 2441 SignatureStream::NCDFError, CHECK_(empty)); 2442 type = Handle(THREAD, mirror); 2443 ss.next(); 2444 if (!ss.is_done()) type = Handle(); // error! 2445 } 2446 } 2447 if (type.is_null()) { 2448 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty); 2449 } 2450 2451 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle 2452 JavaCallArguments args; 2453 args.push_oop(caller->java_mirror()); // the referring class 2454 args.push_int(ref_kind); 2455 args.push_oop(callee->java_mirror()); // the target class 2456 args.push_oop(name()); 2457 args.push_oop(type()); 2458 JavaValue result(T_OBJECT); 2459 JavaCalls::call_static(&result, 2460 SystemDictionary::MethodHandleNatives_klass(), 2461 vmSymbols::linkMethodHandleConstant_name(), 2462 vmSymbols::linkMethodHandleConstant_signature(), 2463 &args, CHECK_(empty)); 2464 return Handle(THREAD, (oop) result.get_jobject()); 2465} 2466 2467// Ask Java code to find or construct a java.lang.invoke.CallSite for the given 2468// name and signature, as interpreted relative to the given class loader. 2469methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller, 2470 Handle bootstrap_specifier, 2471 Symbol* name, 2472 Symbol* type, 2473 Handle *appendix_result, 2474 Handle *method_type_result, 2475 TRAPS) { 2476 methodHandle empty; 2477 Handle bsm, info; 2478 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) { 2479 bsm = bootstrap_specifier; 2480 } else { 2481 assert(bootstrap_specifier->is_objArray(), ""); 2482 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier()); 2483 int len = args->length(); 2484 assert(len >= 1, ""); 2485 bsm = Handle(THREAD, args->obj_at(0)); 2486 if (len > 1) { 2487 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty)); 2488 for (int i = 1; i < len; i++) 2489 args1->obj_at_put(i-1, args->obj_at(i)); 2490 info = Handle(THREAD, args1); 2491 } 2492 } 2493 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()), 2494 "caller must supply a valid BSM"); 2495 2496 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty)); 2497 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty)); 2498 2499 // This should not happen. JDK code should take care of that. 2500 if (caller.is_null() || method_type.is_null()) { 2501 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty); 2502 } 2503 2504 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty)); 2505 assert(appendix_box->obj_at(0) == NULL, ""); 2506 2507 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix) 2508 JavaCallArguments args; 2509 args.push_oop(caller->java_mirror()); 2510 args.push_oop(bsm()); 2511 args.push_oop(method_name()); 2512 args.push_oop(method_type()); 2513 args.push_oop(info()); 2514 args.push_oop(appendix_box); 2515 JavaValue result(T_OBJECT); 2516 JavaCalls::call_static(&result, 2517 SystemDictionary::MethodHandleNatives_klass(), 2518 vmSymbols::linkCallSite_name(), 2519 vmSymbols::linkCallSite_signature(), 2520 &args, CHECK_(empty)); 2521 Handle mname(THREAD, (oop) result.get_jobject()); 2522 (*method_type_result) = method_type; 2523 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD); 2524} 2525 2526// Since the identity hash code for symbols changes when the symbols are 2527// moved from the regular perm gen (hash in the mark word) to the shared 2528// spaces (hash is the address), the classes loaded into the dictionary 2529// may be in the wrong buckets. 2530 2531void SystemDictionary::reorder_dictionary() { 2532 dictionary()->reorder_dictionary(); 2533} 2534 2535 2536void SystemDictionary::copy_buckets(char** top, char* end) { 2537 dictionary()->copy_buckets(top, end); 2538} 2539 2540 2541void SystemDictionary::copy_table(char** top, char* end) { 2542 dictionary()->copy_table(top, end); 2543} 2544 2545 2546void SystemDictionary::reverse() { 2547 dictionary()->reverse(); 2548} 2549 2550int SystemDictionary::number_of_classes() { 2551 return dictionary()->number_of_entries(); 2552} 2553 2554 2555// ---------------------------------------------------------------------------- 2556#ifndef PRODUCT 2557 2558void SystemDictionary::print() { 2559 dictionary()->print(); 2560 2561 // Placeholders 2562 GCMutexLocker mu(SystemDictionary_lock); 2563 placeholders()->print(); 2564 2565 // loader constraints - print under SD_lock 2566 constraints()->print(); 2567} 2568 2569#endif 2570 2571void SystemDictionary::verify() { 2572 guarantee(dictionary() != NULL, "Verify of system dictionary failed"); 2573 guarantee(constraints() != NULL, 2574 "Verify of loader constraints failed"); 2575 guarantee(dictionary()->number_of_entries() >= 0 && 2576 placeholders()->number_of_entries() >= 0, 2577 "Verify of system dictionary failed"); 2578 2579 // Verify dictionary 2580 dictionary()->verify(); 2581 2582 GCMutexLocker mu(SystemDictionary_lock); 2583 placeholders()->verify(); 2584 2585 // Verify constraint table 2586 guarantee(constraints() != NULL, "Verify of loader constraints failed"); 2587 constraints()->verify(dictionary(), placeholders()); 2588} 2589 2590// utility function for class load event 2591void SystemDictionary::post_class_load_event(const Ticks& start_time, 2592 instanceKlassHandle k, 2593 Handle initiating_loader) { 2594#if INCLUDE_TRACE 2595 EventClassLoad event(UNTIMED); 2596 if (event.should_commit()) { 2597 event.set_starttime(start_time); 2598 event.set_loadedClass(k()); 2599 oop defining_class_loader = k->class_loader(); 2600 event.set_definingClassLoader(defining_class_loader != NULL ? 2601 defining_class_loader->klass() : (Klass*)NULL); 2602 oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader(); 2603 event.set_initiatingClassLoader(class_loader != NULL ? 2604 class_loader->klass() : (Klass*)NULL); 2605 event.commit(); 2606 } 2607#endif /* INCLUDE_TRACE */ 2608} 2609 2610#ifndef PRODUCT 2611 2612// statistics code 2613class ClassStatistics: AllStatic { 2614 private: 2615 static int nclasses; // number of classes 2616 static int nmethods; // number of methods 2617 static int nmethoddata; // number of methodData 2618 static int class_size; // size of class objects in words 2619 static int method_size; // size of method objects in words 2620 static int debug_size; // size of debug info in methods 2621 static int methoddata_size; // size of methodData objects in words 2622 2623 static void do_class(Klass* k) { 2624 nclasses++; 2625 class_size += k->size(); 2626 if (k->oop_is_instance()) { 2627 InstanceKlass* ik = (InstanceKlass*)k; 2628 class_size += ik->methods()->size(); 2629 class_size += ik->constants()->size(); 2630 class_size += ik->local_interfaces()->size(); 2631 class_size += ik->transitive_interfaces()->size(); 2632 // We do not have to count implementors, since we only store one! 2633 // SSS: How should these be accounted now that they have moved? 2634 // class_size += ik->fields()->length(); 2635 } 2636 } 2637 2638 static void do_method(Method* m) { 2639 nmethods++; 2640 method_size += m->size(); 2641 // class loader uses same objArray for empty vectors, so don't count these 2642 if (m->has_stackmap_table()) { 2643 method_size += m->stackmap_data()->size(); 2644 } 2645 2646 MethodData* mdo = m->method_data(); 2647 if (mdo != NULL) { 2648 nmethoddata++; 2649 methoddata_size += mdo->size(); 2650 } 2651 } 2652 2653 public: 2654 static void print() { 2655 SystemDictionary::classes_do(do_class); 2656 SystemDictionary::methods_do(do_method); 2657 tty->print_cr("Class statistics:"); 2658 tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize); 2659 tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods, 2660 (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize); 2661 tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize); 2662 } 2663}; 2664 2665 2666int ClassStatistics::nclasses = 0; 2667int ClassStatistics::nmethods = 0; 2668int ClassStatistics::nmethoddata = 0; 2669int ClassStatistics::class_size = 0; 2670int ClassStatistics::method_size = 0; 2671int ClassStatistics::debug_size = 0; 2672int ClassStatistics::methoddata_size = 0; 2673 2674void SystemDictionary::print_class_statistics() { 2675 ResourceMark rm; 2676 ClassStatistics::print(); 2677} 2678 2679 2680class MethodStatistics: AllStatic { 2681 public: 2682 enum { 2683 max_parameter_size = 10 2684 }; 2685 private: 2686 2687 static int _number_of_methods; 2688 static int _number_of_final_methods; 2689 static int _number_of_static_methods; 2690 static int _number_of_native_methods; 2691 static int _number_of_synchronized_methods; 2692 static int _number_of_profiled_methods; 2693 static int _number_of_bytecodes; 2694 static int _parameter_size_profile[max_parameter_size]; 2695 static int _bytecodes_profile[Bytecodes::number_of_java_codes]; 2696 2697 static void initialize() { 2698 _number_of_methods = 0; 2699 _number_of_final_methods = 0; 2700 _number_of_static_methods = 0; 2701 _number_of_native_methods = 0; 2702 _number_of_synchronized_methods = 0; 2703 _number_of_profiled_methods = 0; 2704 _number_of_bytecodes = 0; 2705 for (int i = 0; i < max_parameter_size ; i++) _parameter_size_profile[i] = 0; 2706 for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile [j] = 0; 2707 }; 2708 2709 static void do_method(Method* m) { 2710 _number_of_methods++; 2711 // collect flag info 2712 if (m->is_final() ) _number_of_final_methods++; 2713 if (m->is_static() ) _number_of_static_methods++; 2714 if (m->is_native() ) _number_of_native_methods++; 2715 if (m->is_synchronized()) _number_of_synchronized_methods++; 2716 if (m->method_data() != NULL) _number_of_profiled_methods++; 2717 // collect parameter size info (add one for receiver, if any) 2718 _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++; 2719 // collect bytecodes info 2720 { 2721 Thread *thread = Thread::current(); 2722 HandleMark hm(thread); 2723 BytecodeStream s(methodHandle(thread, m)); 2724 Bytecodes::Code c; 2725 while ((c = s.next()) >= 0) { 2726 _number_of_bytecodes++; 2727 _bytecodes_profile[c]++; 2728 } 2729 } 2730 } 2731 2732 public: 2733 static void print() { 2734 initialize(); 2735 SystemDictionary::methods_do(do_method); 2736 // generate output 2737 tty->cr(); 2738 tty->print_cr("Method statistics (static):"); 2739 // flag distribution 2740 tty->cr(); 2741 tty->print_cr("%6d final methods %6.1f%%", _number_of_final_methods , _number_of_final_methods * 100.0F / _number_of_methods); 2742 tty->print_cr("%6d static methods %6.1f%%", _number_of_static_methods , _number_of_static_methods * 100.0F / _number_of_methods); 2743 tty->print_cr("%6d native methods %6.1f%%", _number_of_native_methods , _number_of_native_methods * 100.0F / _number_of_methods); 2744 tty->print_cr("%6d synchronized methods %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods); 2745 tty->print_cr("%6d profiled methods %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods); 2746 // parameter size profile 2747 tty->cr(); 2748 { int tot = 0; 2749 int avg = 0; 2750 for (int i = 0; i < max_parameter_size; i++) { 2751 int n = _parameter_size_profile[i]; 2752 tot += n; 2753 avg += n*i; 2754 tty->print_cr("parameter size = %1d: %6d methods %5.1f%%", i, n, n * 100.0F / _number_of_methods); 2755 } 2756 assert(tot == _number_of_methods, "should be the same"); 2757 tty->print_cr(" %6d methods 100.0%%", _number_of_methods); 2758 tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods); 2759 } 2760 // bytecodes profile 2761 tty->cr(); 2762 { int tot = 0; 2763 for (int i = 0; i < Bytecodes::number_of_java_codes; i++) { 2764 if (Bytecodes::is_defined(i)) { 2765 Bytecodes::Code c = Bytecodes::cast(i); 2766 int n = _bytecodes_profile[c]; 2767 tot += n; 2768 tty->print_cr("%9d %7.3f%% %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c)); 2769 } 2770 } 2771 assert(tot == _number_of_bytecodes, "should be the same"); 2772 tty->print_cr("%9d 100.000%%", _number_of_bytecodes); 2773 } 2774 tty->cr(); 2775 } 2776}; 2777 2778int MethodStatistics::_number_of_methods; 2779int MethodStatistics::_number_of_final_methods; 2780int MethodStatistics::_number_of_static_methods; 2781int MethodStatistics::_number_of_native_methods; 2782int MethodStatistics::_number_of_synchronized_methods; 2783int MethodStatistics::_number_of_profiled_methods; 2784int MethodStatistics::_number_of_bytecodes; 2785int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size]; 2786int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes]; 2787 2788 2789void SystemDictionary::print_method_statistics() { 2790 MethodStatistics::print(); 2791} 2792 2793#endif // PRODUCT 2794