1 /*
   2  * Copyright (c) 1997, 2018, 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 #if INCLUDE_CDS
  34 #include "classfile/sharedClassUtil.hpp"
  35 #include "classfile/systemDictionaryShared.hpp"
  36 #endif
  37 #include "classfile/vmSymbols.hpp"
  38 #include "compiler/compileBroker.hpp"
  39 #include "interpreter/bytecodeStream.hpp"
  40 #include "interpreter/interpreter.hpp"


  41 #include "memory/filemap.hpp"
  42 #include "memory/gcLocker.hpp"
  43 #include "memory/oopFactory.hpp"
  44 #include "oops/instanceKlass.hpp"
  45 #include "oops/instanceRefKlass.hpp"
  46 #include "oops/klass.inline.hpp"
  47 #include "oops/methodData.hpp"
  48 #include "oops/objArrayKlass.hpp"
  49 #include "oops/oop.inline.hpp"
  50 #include "oops/oop.inline2.hpp"
  51 #include "oops/typeArrayKlass.hpp"
  52 #include "prims/jvmtiEnvBase.hpp"
  53 #include "prims/methodHandles.hpp"
  54 #include "runtime/arguments.hpp"
  55 #include "runtime/biasedLocking.hpp"
  56 #include "runtime/fieldType.hpp"
  57 #include "runtime/handles.inline.hpp"
  58 #include "runtime/java.hpp"
  59 #include "runtime/javaCalls.hpp"
  60 #include "runtime/mutexLocker.hpp"
  61 #include "runtime/orderAccess.inline.hpp"
  62 #include "runtime/signature.hpp"
  63 #include "services/classLoadingService.hpp"
  64 #include "services/threadService.hpp"
  65 #include "utilities/macros.hpp"
  66 #include "utilities/ticks.hpp"
  67 #if INCLUDE_TRACE
  68 #include "trace/tracing.hpp"
  69 #endif
  70 
  71 Dictionary*            SystemDictionary::_dictionary          = NULL;
  72 PlaceholderTable*      SystemDictionary::_placeholders        = NULL;
  73 Dictionary*            SystemDictionary::_shared_dictionary   = NULL;
  74 LoaderConstraintTable* SystemDictionary::_loader_constraints  = NULL;
  75 ResolutionErrorTable*  SystemDictionary::_resolution_errors   = NULL;
  76 SymbolPropertyTable*   SystemDictionary::_invoke_method_table = NULL;
  77 
  78 
  79 int         SystemDictionary::_number_of_modifications = 0;
  80 int         SystemDictionary::_sdgeneration               = 0;
  81 const int   SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
  82               20201,40423,99991};
  83 
  84 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;
  85 
  86 Klass*      SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
  87                                                           =  { NULL /*, NULL...*/ };
  88 
  89 Klass*      SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };
  90 
  91 oop         SystemDictionary::_java_system_loader         =  NULL;
  92 
  93 bool        SystemDictionary::_has_loadClassInternal      =  false;
  94 bool        SystemDictionary::_has_checkPackageAccess     =  false;
  95 
  96 // lazily initialized klass variables
  97 Klass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
  98 



  99 
 100 // ----------------------------------------------------------------------------
 101 // Java-level SystemLoader
 102 
 103 oop SystemDictionary::java_system_loader() {
 104   return _java_system_loader;
 105 }
 106 
 107 void SystemDictionary::compute_java_system_loader(TRAPS) {
 108   KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
 109   JavaValue result(T_OBJECT);
 110   JavaCalls::call_static(&result,
 111                          KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
 112                          vmSymbols::getSystemClassLoader_name(),
 113                          vmSymbols::void_classloader_signature(),
 114                          CHECK);
 115 
 116   _java_system_loader = (oop)result.get_jobject();
 117 
 118   CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)
 119 }
 120 
 121 
 122 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
 123   if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
 124   return ClassLoaderDataGraph::find_or_create(class_loader, THREAD);
 125 }
 126 
 127 // ----------------------------------------------------------------------------
 128 // debugging
 129 
 130 #ifdef ASSERT
 131 
 132 // return true if class_name contains no '.' (internal format is '/')
 133 bool SystemDictionary::is_internal_format(Symbol* class_name) {
 134   if (class_name != NULL) {
 135     ResourceMark rm;
 136     char* name = class_name->as_C_string();
 137     return strchr(name, '.') == NULL;
 138   } else {
 139     return true;
 140   }
 141 }
 142 
 143 #endif



 144 
 145 // ----------------------------------------------------------------------------
 146 // Parallel class loading check
 147 
 148 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
 149   if (UnsyncloadClass || class_loader.is_null()) return true;
 150   if (AlwaysLockClassLoader) return false;
 151   return java_lang_ClassLoader::parallelCapable(class_loader());
 152 }
 153 // ----------------------------------------------------------------------------
 154 // ParallelDefineClass flag does not apply to bootclass loader
 155 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
 156    if (class_loader.is_null()) return false;
 157    if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
 158      return true;
 159    }
 160    return false;
 161 }
 162 
 163 /**
 164  * Returns true if the passed class loader is the extension class loader.
 165  */
 166 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
 167   if (class_loader.is_null()) {
 168     return false;
 169   }
 170   return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
 171 }
 172 
 173 // ----------------------------------------------------------------------------
 174 // Resolving of classes
 175 
 176 // Forwards to resolve_or_null
 177 
 178 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
 179   Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
 180   if (HAS_PENDING_EXCEPTION || klass == NULL) {
 181     KlassHandle k_h(THREAD, klass);
 182     // can return a null klass
 183     klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);
 184   }
 185   return klass;
 186 }
 187 
 188 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {
 189   if (HAS_PENDING_EXCEPTION) {
 190     // If we have a pending exception we forward it to the caller, unless throw_error is true,
 191     // in which case we have to check whether the pending exception is a ClassNotFoundException,
 192     // and if so convert it to a NoClassDefFoundError
 193     // And chain the original ClassNotFoundException
 194     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
 195       ResourceMark rm(THREAD);
 196       assert(klass_h() == NULL, "Should not have result with exception pending");
 197       Handle e(THREAD, PENDING_EXCEPTION);
 198       CLEAR_PENDING_EXCEPTION;
 199       THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
 200     } else {
 201       return NULL;
 202     }
 203   }
 204   // Class not found, throw appropriate error or exception depending on value of throw_error
 205   if (klass_h() == NULL) {
 206     ResourceMark rm(THREAD);
 207     if (throw_error) {
 208       THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
 209     } else {
 210       THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
 211     }
 212   }
 213   return (Klass*)klass_h();
 214 }
 215 
 216 
 217 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
 218                                            bool throw_error, TRAPS)
 219 {
 220   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
 221 }
 222 
 223 
 224 // Forwards to resolve_instance_class_or_null
 225 
 226 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
 227   assert(!THREAD->is_Compiler_thread(),
 228          err_msg("can not load classes with compiler thread: class=%s, classloader=%s",
 229                  class_name->as_C_string(),
 230                  class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()));
 231   if (FieldType::is_array(class_name)) {
 232     return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
 233   } else if (FieldType::is_obj(class_name)) {
 234     ResourceMark rm(THREAD);
 235     // Ignore wrapping L and ;.
 236     TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
 237                                    class_name->utf8_length() - 2, CHECK_NULL);
 238     return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL);
 239   } else {
 240     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
 241   }
 242 }
 243 
 244 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
 245   return resolve_or_null(class_name, Handle(), Handle(), THREAD);
 246 }
 247 
 248 // Forwards to resolve_instance_class_or_null
 249 
 250 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
 251                                                        Handle class_loader,
 252                                                        Handle protection_domain,
 253                                                        TRAPS) {
 254   assert(FieldType::is_array(class_name), "must be array");
 255   Klass* k = NULL;
 256   FieldArrayInfo fd;
 257   // dimension and object_key in FieldArrayInfo are assigned as a side-effect
 258   // of this call
 259   BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
 260   if (t == T_OBJECT) {
 261     // naked oop "k" is OK here -- we assign back into it
 262     k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
 263                                                          class_loader,
 264                                                          protection_domain,
 265                                                          CHECK_NULL);
 266     if (k != NULL) {
 267       k = k->array_klass(fd.dimension(), CHECK_NULL);
 268     }
 269   } else {
 270     k = Universe::typeArrayKlassObj(t);
 271     k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
 272   }
 273   return k;
 274 }
 275 
 276 
 277 // Must be called for any super-class or super-interface resolution
 278 // during class definition to allow class circularity checking
 279 // super-interface callers:
 280 //    parse_interfaces - for defineClass & jvmtiRedefineClasses
 281 // super-class callers:
 282 //   ClassFileParser - for defineClass & jvmtiRedefineClasses
 283 //   load_shared_class - while loading a class from shared archive
 284 //   resolve_instance_class_or_null:
 285 //     via: handle_parallel_super_load
 286 //      when resolving a class that has an existing placeholder with
 287 //      a saved superclass [i.e. a defineClass is currently in progress]
 288 //      if another thread is trying to resolve the class, it must do
 289 //      super-class checks on its own thread to catch class circularity
 290 // This last call is critical in class circularity checking for cases
 291 // where classloading is delegated to different threads and the
 292 // classloader lock is released.
 293 // Take the case: Base->Super->Base
 294 //   1. If thread T1 tries to do a defineClass of class Base
 295 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)
 296 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super
 297 //    so it tries to load Super
 298 //   3. If we load the class internally, or user classloader uses same thread
 299 //      loadClassFromxxx or defineClass via parseClassFile Super ...
 300 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
 301 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base
 302 //      3.4 calls resolve_super_or_fail Base
 303 //      3.5 finds T1,Base -> throws class circularity
 304 //OR 4. If T2 tries to resolve Super via defineClass Super ...
 305 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
 306 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
 307 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2
 308 //      4.4 finds T2, Super -> throws class circularity
 309 // Must be called, even if superclass is null, since this is
 310 // where the placeholder entry is created which claims this
 311 // thread is loading this class/classloader.
 312 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
 313                                                  Symbol* class_name,
 314                                                  Handle class_loader,
 315                                                  Handle protection_domain,
 316                                                  bool is_superclass,
 317                                                  TRAPS) {
 318   // Double-check, if child class is already loaded, just return super-class,interface
 319   // Don't add a placedholder if already loaded, i.e. already in system dictionary
 320   // Make sure there's a placeholder for the *child* before resolving.
 321   // Used as a claim that this thread is currently loading superclass/classloader
 322   // Used here for ClassCircularity checks and also for heap verification
 323   // (every InstanceKlass in the heap needs to be in the system dictionary
 324   // or have a placeholder).
 325   // Must check ClassCircularity before checking if super class is already loaded
 326   //
 327   // We might not already have a placeholder if this child_name was
 328   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
 329   // the name of the class might not be known until the stream is actually
 330   // parsed.
 331   // Bugs 4643874, 4715493
 332   // compute_hash can have a safepoint
 333 
 334   ClassLoaderData* loader_data = class_loader_data(class_loader);
 335   unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
 336   int d_index = dictionary()->hash_to_index(d_hash);
 337   unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
 338   int p_index = placeholders()->hash_to_index(p_hash);
 339   // can't throw error holding a lock
 340   bool child_already_loaded = false;
 341   bool throw_circularity_error = false;
 342   {
 343     MutexLocker mu(SystemDictionary_lock, THREAD);
 344     Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
 345     Klass* quicksuperk;
 346     // to support // loading: if child done loading, just return superclass
 347     // if class_name, & class_loader don't match:
 348     // if initial define, SD update will give LinkageError
 349     // if redefine: compare_class_versions will give HIERARCHY_CHANGED
 350     // so we don't throw an exception here.
 351     // see: nsk redefclass014 & java.lang.instrument Instrument032
 352     if ((childk != NULL ) && (is_superclass) &&
 353        ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) &&
 354 
 355          ((quicksuperk->name() == class_name) &&
 356             (quicksuperk->class_loader()  == class_loader()))) {
 357            return quicksuperk;
 358     } else {
 359       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
 360       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
 361           throw_circularity_error = true;
 362       }
 363     }
 364     if (!throw_circularity_error) {
 365       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
 366     }
 367   }
 368   if (throw_circularity_error) {
 369       ResourceMark rm(THREAD);
 370       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
 371   }
 372 
 373 // java.lang.Object should have been found above
 374   assert(class_name != NULL, "null super class for resolving");
 375   // Resolve the super class or interface, check results on return
 376   Klass* superk = SystemDictionary::resolve_or_null(class_name,
 377                                                  class_loader,
 378                                                  protection_domain,
 379                                                  THREAD);
 380 
 381   KlassHandle superk_h(THREAD, superk);
 382 
 383   // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
 384   // It is no longer necessary to keep the placeholder table alive until update_dictionary
 385   // or error. GC used to walk the placeholder table as strong roots.
 386   // The instanceKlass is kept alive because the class loader is on the stack,
 387   // which keeps the loader_data alive, as well as all instanceKlasses in
 388   // the loader_data. parseClassFile adds the instanceKlass to loader_data.
 389   {
 390     MutexLocker mu(SystemDictionary_lock, THREAD);
 391     placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
 392     SystemDictionary_lock->notify_all();
 393   }
 394   if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
 395     // can null superk
 396     superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));
 397   }
 398 
 399   return superk_h();
 400 }
 401 
 402 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
 403                                                   Handle class_loader,
 404                                                   Handle protection_domain,
 405                                                   TRAPS) {
 406   if(!has_checkPackageAccess()) return;
 407 
 408   // Now we have to call back to java to check if the initating class has access
 409   JavaValue result(T_VOID);
 410   if (TraceProtectionDomainVerification) {
 411     // Print out trace information
 412     tty->print_cr("Checking package access");
 413     tty->print(" - class loader:      "); class_loader()->print_value_on(tty);      tty->cr();
 414     tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
 415     tty->print(" - loading:           "); klass()->print_value_on(tty);             tty->cr();
 416   }
 417 
 418   KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
 419   JavaCalls::call_special(&result,
 420                          class_loader,
 421                          system_loader,
 422                          vmSymbols::checkPackageAccess_name(),
 423                          vmSymbols::class_protectiondomain_signature(),
 424                          Handle(THREAD, klass->java_mirror()),
 425                          protection_domain,
 426                          THREAD);
 427 
 428   if (TraceProtectionDomainVerification) {
 429     if (HAS_PENDING_EXCEPTION) {
 430       tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
 431     } else {
 432      tty->print_cr(" -> granted");
 433     }
 434     tty->cr();
 435   }
 436 
 437   if (HAS_PENDING_EXCEPTION) return;
 438 
 439   // If no exception has been thrown, we have validated the protection domain
 440   // Insert the protection domain of the initiating class into the set.
 441   {
 442     // We recalculate the entry here -- we've called out to java since
 443     // the last time it was calculated.
 444     ClassLoaderData* loader_data = class_loader_data(class_loader);
 445 
 446     Symbol*  kn = klass->name();
 447     unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
 448     int d_index = dictionary()->hash_to_index(d_hash);
 449 
 450     MutexLocker mu(SystemDictionary_lock, THREAD);
 451     {
 452       // Note that we have an entry, and entries can be deleted only during GC,
 453       // so we cannot allow GC to occur while we're holding this entry.
 454 
 455       // We're using a No_Safepoint_Verifier to catch any place where we
 456       // might potentially do a GC at all.
 457       // Dictionary::do_unloading() asserts that classes in SD are only
 458       // unloaded at a safepoint. Anonymous classes are not in SD.
 459       No_Safepoint_Verifier nosafepoint;
 460       dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
 461                                           protection_domain, THREAD);
 462     }
 463   }
 464 }
 465 
 466 // We only get here if this thread finds that another thread
 467 // has already claimed the placeholder token for the current operation,
 468 // but that other thread either never owned or gave up the
 469 // object lock
 470 // Waits on SystemDictionary_lock to indicate placeholder table updated
 471 // On return, caller must recheck placeholder table state
 472 //
 473 // We only get here if
 474 //  1) custom classLoader, i.e. not bootstrap classloader
 475 //  2) UnsyncloadClass not set
 476 //  3) custom classLoader has broken the class loader objectLock
 477 //     so another thread got here in parallel
 478 //
 479 // lockObject must be held.
 480 // Complicated dance due to lock ordering:
 481 // Must first release the classloader object lock to
 482 // allow initial definer to complete the class definition
 483 // and to avoid deadlock
 484 // Reclaim classloader lock object with same original recursion count
 485 // Must release SystemDictionary_lock after notify, since
 486 // class loader lock must be claimed before SystemDictionary_lock
 487 // to prevent deadlocks
 488 //
 489 // The notify allows applications that did an untimed wait() on
 490 // the classloader object lock to not hang.
 491 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
 492   assert_lock_strong(SystemDictionary_lock);
 493 
 494   bool calledholdinglock
 495       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
 496   assert(calledholdinglock,"must hold lock for notify");
 497   assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
 498   ObjectSynchronizer::notifyall(lockObject, THREAD);
 499   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);
 500   SystemDictionary_lock->wait();
 501   SystemDictionary_lock->unlock();
 502   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
 503   SystemDictionary_lock->lock();
 504 }
 505 
 506 // If the class in is in the placeholder table, class loading is in progress
 507 // For cases where the application changes threads to load classes, it
 508 // is critical to ClassCircularity detection that we try loading
 509 // the superclass on the same thread internally, so we do parallel
 510 // super class loading here.
 511 // This also is critical in cases where the original thread gets stalled
 512 // even in non-circularity situations.
 513 // Note: must call resolve_super_or_fail even if null super -
 514 // to force placeholder entry creation for this class for circularity detection
 515 // Caller must check for pending exception
 516 // Returns non-null Klass* if other thread has completed load
 517 // and we are done,
 518 // If return null Klass* and no pending exception, the caller must load the class
 519 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
 520     Symbol* name, Symbol* superclassname, Handle class_loader,
 521     Handle protection_domain, Handle lockObject, TRAPS) {
 522 
 523   instanceKlassHandle nh = instanceKlassHandle(); // null Handle
 524   ClassLoaderData* loader_data = class_loader_data(class_loader);
 525   unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
 526   int d_index = dictionary()->hash_to_index(d_hash);
 527   unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
 528   int p_index = placeholders()->hash_to_index(p_hash);
 529 
 530   // superk is not used, resolve_super called for circularity check only
 531   // This code is reached in two situations. One if this thread
 532   // is loading the same class twice (e.g. ClassCircularity, or
 533   // java.lang.instrument).
 534   // The second is if another thread started the resolve_super first
 535   // and has not yet finished.
 536   // In both cases the original caller will clean up the placeholder
 537   // entry on error.
 538   Klass* superk = SystemDictionary::resolve_super_or_fail(name,
 539                                                           superclassname,
 540                                                           class_loader,
 541                                                           protection_domain,
 542                                                           true,
 543                                                           CHECK_(nh));
 544 
 545   // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
 546   // Serial class loaders and bootstrap classloader do wait for superclass loads
 547  if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
 548     MutexLocker mu(SystemDictionary_lock, THREAD);
 549     // Check if classloading completed while we were loading superclass or waiting
 550     Klass* check = find_class(d_index, d_hash, name, loader_data);
 551     if (check != NULL) {
 552       // Klass is already loaded, so just return it
 553       return(instanceKlassHandle(THREAD, check));
 554     } else {
 555       return nh;
 556     }
 557   }
 558 
 559   // must loop to both handle other placeholder updates
 560   // and spurious notifications
 561   bool super_load_in_progress = true;
 562   PlaceholderEntry* placeholder;
 563   while (super_load_in_progress) {
 564     MutexLocker mu(SystemDictionary_lock, THREAD);
 565     // Check if classloading completed while we were loading superclass or waiting
 566     Klass* check = find_class(d_index, d_hash, name, loader_data);
 567     if (check != NULL) {
 568       // Klass is already loaded, so just return it
 569       return(instanceKlassHandle(THREAD, check));
 570     } else {
 571       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 572       if (placeholder && placeholder->super_load_in_progress() ){
 573         // Before UnsyncloadClass:
 574         // We only get here if the application has released the
 575         // classloader lock when another thread was in the middle of loading a
 576         // superclass/superinterface for this class, and now
 577         // this thread is also trying to load this class.
 578         // To minimize surprises, the first thread that started to
 579         // load a class should be the one to complete the loading
 580         // with the classfile it initially expected.
 581         // This logic has the current thread wait once it has done
 582         // all the superclass/superinterface loading it can, until
 583         // the original thread completes the class loading or fails
 584         // If it completes we will use the resulting InstanceKlass
 585         // which we will find below in the systemDictionary.
 586         // We also get here for parallel bootstrap classloader
 587         if (class_loader.is_null()) {
 588           SystemDictionary_lock->wait();
 589         } else {
 590           double_lock_wait(lockObject, THREAD);
 591         }
 592       } else {
 593         // If not in SD and not in PH, other thread's load must have failed
 594         super_load_in_progress = false;
 595       }
 596     }
 597   }
 598   return (nh);
 599 }
 600 
















 601 
 602 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
 603                                                         Handle class_loader,
 604                                                         Handle protection_domain,
 605                                                         TRAPS) {
 606   assert(name != NULL && !FieldType::is_array(name) &&
 607          !FieldType::is_obj(name), "invalid class name");
 608 
 609   Ticks class_load_start_time = Ticks::now();
 610 
 611   // UseNewReflection
 612   // Fix for 4474172; see evaluation for more details
 613   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 614   ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
 615 
 616   // Do lookup to see if class already exist and the protection domain
 617   // has the right access
 618   // This call uses find which checks protection domain already matches
 619   // All subsequent calls use find_class, and set has_loaded_class so that
 620   // before we return a result we call out to java to check for valid protection domain
 621   // to allow returning the Klass* and add it to the pd_set if it is valid
 622   unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
 623   int d_index = dictionary()->hash_to_index(d_hash);
 624   Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
 625                                       protection_domain, THREAD);
 626   if (probe != NULL) return probe;
 627 
 628 
 629   // Non-bootstrap class loaders will call out to class loader and
 630   // define via jvm/jni_DefineClass which will acquire the
 631   // class loader object lock to protect against multiple threads
 632   // defining the class in parallel by accident.
 633   // This lock must be acquired here so the waiter will find
 634   // any successful result in the SystemDictionary and not attempt
 635   // the define
 636   // ParallelCapable Classloaders and the bootstrap classloader,
 637   // or all classloaders with UnsyncloadClass do not acquire lock here
 638   bool DoObjectLock = true;
 639   if (is_parallelCapable(class_loader)) {
 640     DoObjectLock = false;
 641   }
 642 
 643   unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
 644   int p_index = placeholders()->hash_to_index(p_hash);
 645 
 646   // Class is not in SystemDictionary so we have to do loading.
 647   // Make sure we are synchronized on the class loader before we proceed
 648   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
 649   check_loader_lock_contention(lockObject, THREAD);
 650   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
 651 
 652   // Check again (after locking) if class already exist in SystemDictionary
 653   bool class_has_been_loaded   = false;
 654   bool super_load_in_progress  = false;
 655   bool havesupername = false;
 656   instanceKlassHandle k;
 657   PlaceholderEntry* placeholder;
 658   Symbol* superclassname = NULL;
 659 
 660   {
 661     MutexLocker mu(SystemDictionary_lock, THREAD);
 662     Klass* check = find_class(d_index, d_hash, name, loader_data);
 663     if (check != NULL) {
 664       // Klass is already loaded, so just return it
 665       class_has_been_loaded = true;
 666       k = instanceKlassHandle(THREAD, check);
 667     } else {
 668       placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 669       if (placeholder && placeholder->super_load_in_progress()) {
 670          super_load_in_progress = true;
 671          if (placeholder->havesupername() == true) {
 672            superclassname = placeholder->supername();
 673            havesupername = true;
 674          }
 675       }
 676     }
 677   }
 678 
 679   // If the class is in the placeholder table, class loading is in progress
 680   if (super_load_in_progress && havesupername==true) {
 681     k = SystemDictionary::handle_parallel_super_load(name, superclassname,
 682         class_loader, protection_domain, lockObject, THREAD);
 683     if (HAS_PENDING_EXCEPTION) {
 684       return NULL;
 685     }
 686     if (!k.is_null()) {
 687       class_has_been_loaded = true;
 688     }
 689   }
 690 
 691   bool throw_circularity_error = false;
 692   if (!class_has_been_loaded) {
 693     bool load_instance_added = false;
 694 
 695     // add placeholder entry to record loading instance class
 696     // Five cases:
 697     // All cases need to prevent modifying bootclasssearchpath
 698     // in parallel with a classload of same classname
 699     // Redefineclasses uses existence of the placeholder for the duration
 700     // of the class load to prevent concurrent redefinition of not completely
 701     // defined classes.
 702     // case 1. traditional classloaders that rely on the classloader object lock
 703     //   - no other need for LOAD_INSTANCE
 704     // case 2. traditional classloaders that break the classloader object lock
 705     //    as a deadlock workaround. Detection of this case requires that
 706     //    this check is done while holding the classloader object lock,
 707     //    and that lock is still held when calling classloader's loadClass.
 708     //    For these classloaders, we ensure that the first requestor
 709     //    completes the load and other requestors wait for completion.
 710     // case 3. UnsyncloadClass - don't use objectLocker
 711     //    With this flag, we allow parallel classloading of a
 712     //    class/classloader pair
 713     // case4. Bootstrap classloader - don't own objectLocker
 714     //    This classloader supports parallelism at the classloader level,
 715     //    but only allows a single load of a class/classloader pair.
 716     //    No performance benefit and no deadlock issues.
 717     // case 5. parallelCapable user level classloaders - without objectLocker
 718     //    Allow parallel classloading of a class/classloader pair
 719 
 720     {
 721       MutexLocker mu(SystemDictionary_lock, THREAD);
 722       if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
 723         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 724         if (oldprobe) {
 725           // only need check_seen_thread once, not on each loop
 726           // 6341374 java/lang/Instrument with -Xcomp
 727           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
 728             throw_circularity_error = true;
 729           } else {
 730             // case 1: traditional: should never see load_in_progress.
 731             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
 732 
 733               // case 4: bootstrap classloader: prevent futile classloading,
 734               // wait on first requestor
 735               if (class_loader.is_null()) {
 736                 SystemDictionary_lock->wait();
 737               } else {
 738               // case 2: traditional with broken classloader lock. wait on first
 739               // requestor.
 740                 double_lock_wait(lockObject, THREAD);
 741               }
 742               // Check if classloading completed while we were waiting
 743               Klass* check = find_class(d_index, d_hash, name, loader_data);
 744               if (check != NULL) {
 745                 // Klass is already loaded, so just return it
 746                 k = instanceKlassHandle(THREAD, check);
 747                 class_has_been_loaded = true;
 748               }
 749               // check if other thread failed to load and cleaned up
 750               oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
 751             }
 752           }
 753         }
 754       }
 755       // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
 756       // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
 757       // LOAD_INSTANCE in parallel
 758 
 759       if (!throw_circularity_error && !class_has_been_loaded) {
 760         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
 761         load_instance_added = true;
 762         // For class loaders that do not acquire the classloader object lock,
 763         // if they did not catch another thread holding LOAD_INSTANCE,
 764         // need a check analogous to the acquire ObjectLocker/find_class
 765         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
 766         // one final check if the load has already completed
 767         // class loaders holding the ObjectLock shouldn't find the class here
 768         Klass* check = find_class(d_index, d_hash, name, loader_data);
 769         if (check != NULL) {
 770         // Klass is already loaded, so return it after checking/adding protection domain
 771           k = instanceKlassHandle(THREAD, check);
 772           class_has_been_loaded = true;
 773         }
 774       }
 775     }
 776 
 777     // must throw error outside of owning lock
 778     if (throw_circularity_error) {
 779       assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
 780       ResourceMark rm(THREAD);
 781       THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
 782     }
 783 
 784     if (!class_has_been_loaded) {
 785 
 786       // Do actual loading
 787       k = load_instance_class(name, class_loader, THREAD);
 788 
 789       // For UnsyncloadClass only
 790       // If they got a linkageError, check if a parallel class load succeeded.
 791       // If it did, then for bytecode resolution the specification requires
 792       // that we return the same result we did for the other thread, i.e. the
 793       // successfully loaded InstanceKlass
 794       // Should not get here for classloaders that support parallelism
 795       // with the new cleaner mechanism, even with AllowParallelDefineClass
 796       // Bootstrap goes through here to allow for an extra guarantee check
 797       if (UnsyncloadClass || (class_loader.is_null())) {
 798         if (k.is_null() && HAS_PENDING_EXCEPTION
 799           && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
 800           MutexLocker mu(SystemDictionary_lock, THREAD);
 801           Klass* check = find_class(d_index, d_hash, name, loader_data);
 802           if (check != NULL) {
 803             // Klass is already loaded, so just use it
 804             k = instanceKlassHandle(THREAD, check);
 805             CLEAR_PENDING_EXCEPTION;
 806             guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
 807           }
 808         }
 809       }
 810 
 811       // If everything was OK (no exceptions, no null return value), and
 812       // class_loader is NOT the defining loader, do a little more bookkeeping.
 813       if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
 814         k->class_loader() != class_loader()) {
 815 
 816         check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
 817 
 818         // Need to check for a PENDING_EXCEPTION again; check_constraints
 819         // can throw but we may have to remove entry from the placeholder table below.
 820         if (!HAS_PENDING_EXCEPTION) {
 821           // Record dependency for non-parent delegation.
 822           // This recording keeps the defining class loader of the klass (k) found
 823           // from being unloaded while the initiating class loader is loaded
 824           // even if the reference to the defining class loader is dropped
 825           // before references to the initiating class loader.
 826           loader_data->record_dependency(k(), THREAD);
 827         }
 828 
 829         if (!HAS_PENDING_EXCEPTION) {
 830           { // Grabbing the Compile_lock prevents systemDictionary updates
 831             // during compilations.
 832             MutexLocker mu(Compile_lock, THREAD);
 833             update_dictionary(d_index, d_hash, p_index, p_hash,
 834                               k, class_loader, THREAD);
 835           }
 836 
 837           if (JvmtiExport::should_post_class_load()) {
 838             Thread *thread = THREAD;
 839             assert(thread->is_Java_thread(), "thread->is_Java_thread()");
 840             JvmtiExport::post_class_load((JavaThread *) thread, k());
 841           }
 842         }
 843       }
 844     } // load_instance_class loop
 845 
 846     if (load_instance_added == true) {
 847       // clean up placeholder entries for LOAD_INSTANCE success or error
 848       // This brackets the SystemDictionary updates for both defining
 849       // and initiating loaders
 850       MutexLocker mu(SystemDictionary_lock, THREAD);
 851       placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
 852       SystemDictionary_lock->notify_all();
 853     }
 854   }
 855 
 856   if (HAS_PENDING_EXCEPTION || k.is_null()) {
 857     return NULL;
 858   }
 859 
 860   post_class_load_event(class_load_start_time, k, class_loader);
 861 
 862 #ifdef ASSERT
 863   {
 864     ClassLoaderData* loader_data = k->class_loader_data();
 865     MutexLocker mu(SystemDictionary_lock, THREAD);
 866     Klass* kk = find_class(name, loader_data);
 867     assert(kk == k(), "should be present in dictionary");
 868   }
 869 #endif
 870 
 871   // return if the protection domain in NULL
 872   if (protection_domain() == NULL) return k();
 873 
 874   // Check the protection domain has the right access
 875   {
 876     MutexLocker mu(SystemDictionary_lock, THREAD);
 877     // Note that we have an entry, and entries can be deleted only during GC,
 878     // so we cannot allow GC to occur while we're holding this entry.
 879     // We're using a No_Safepoint_Verifier to catch any place where we
 880     // might potentially do a GC at all.
 881     // Dictionary::do_unloading() asserts that classes in SD are only
 882     // unloaded at a safepoint. Anonymous classes are not in SD.
 883     No_Safepoint_Verifier nosafepoint;
 884     if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
 885                                                  loader_data,
 886                                                  protection_domain)) {
 887       return k();
 888     }
 889   }
 890 
 891   // Verify protection domain. If it fails an exception is thrown
 892   validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
 893 
 894   return k();
 895 }
 896 
 897 
 898 // This routine does not lock the system dictionary.
 899 //
 900 // Since readers don't hold a lock, we must make sure that system
 901 // dictionary entries are only removed at a safepoint (when only one
 902 // thread is running), and are added to in a safe way (all links must
 903 // be updated in an MT-safe manner).
 904 //
 905 // Callers should be aware that an entry could be added just after
 906 // _dictionary->bucket(index) is read here, so the caller will not see
 907 // the new entry.
 908 
 909 Klass* SystemDictionary::find(Symbol* class_name,
 910                               Handle class_loader,
 911                               Handle protection_domain,
 912                               TRAPS) {
 913 
 914   // UseNewReflection
 915   // The result of this call should be consistent with the result
 916   // of the call to resolve_instance_class_or_null().
 917   // See evaluation 6790209 and 4474172 for more details.
 918   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
 919   ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
 920 
 921   if (loader_data == NULL) {
 922     // If the ClassLoaderData has not been setup,
 923     // then the class loader has no entries in the dictionary.
 924     return NULL;
 925   }
 926 
 927   unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
 928   int d_index = dictionary()->hash_to_index(d_hash);
 929 
 930   {
 931     // Note that we have an entry, and entries can be deleted only during GC,
 932     // so we cannot allow GC to occur while we're holding this entry.
 933     // We're using a No_Safepoint_Verifier to catch any place where we
 934     // might potentially do a GC at all.
 935     // Dictionary::do_unloading() asserts that classes in SD are only
 936     // unloaded at a safepoint. Anonymous classes are not in SD.
 937     No_Safepoint_Verifier nosafepoint;
 938     return dictionary()->find(d_index, d_hash, class_name, loader_data,
 939                               protection_domain, THREAD);
 940   }
 941 }
 942 
 943 
 944 // Look for a loaded instance or array klass by name.  Do not do any loading.
 945 // return NULL in case of error.
 946 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
 947                                                       Handle class_loader,
 948                                                       Handle protection_domain,
 949                                                       TRAPS) {
 950   Klass* k = NULL;
 951   assert(class_name != NULL, "class name must be non NULL");
 952 
 953   if (FieldType::is_array(class_name)) {
 954     // The name refers to an array.  Parse the name.
 955     // dimension and object_key in FieldArrayInfo are assigned as a
 956     // side-effect of this call
 957     FieldArrayInfo fd;
 958     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
 959     if (t != T_OBJECT) {
 960       k = Universe::typeArrayKlassObj(t);
 961     } else {
 962       k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
 963     }
 964     if (k != NULL) {
 965       k = k->array_klass_or_null(fd.dimension());
 966     }
 967   } else {
 968     k = find(class_name, class_loader, protection_domain, THREAD);
 969   }
 970   return k;
 971 }
 972 
 973 // Note: this method is much like resolve_from_stream, but
 974 // updates no supplemental data structures.
 975 // TODO consolidate the two methods with a helper routine?
 976 Klass* SystemDictionary::parse_stream(Symbol* class_name,
 977                                       Handle class_loader,
 978                                       Handle protection_domain,
 979                                       ClassFileStream* st,
 980                                       KlassHandle host_klass,
 981                                       GrowableArray<Handle>* cp_patches,
 982                                       TRAPS) {
 983   TempNewSymbol parsed_name = NULL;
 984 
 985   Ticks class_load_start_time = Ticks::now();
 986 
 987   ClassLoaderData* loader_data;
 988   if (host_klass.not_null()) {
 989     // Create a new CLD for anonymous class, that uses the same class loader
 990     // as the host_klass
 991     assert(EnableInvokeDynamic, "");
 992     guarantee(host_klass->class_loader() == class_loader(), "should be the same");
 993     guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping");
 994     loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
 995     loader_data->record_dependency(host_klass(), CHECK_NULL);
 996   } else {
 997     loader_data = ClassLoaderData::class_loader_data(class_loader());
 998   }
 999 
1000   // Parse the stream. Note that we do this even though this klass might
1001   // already be present in the SystemDictionary, otherwise we would not
1002   // throw potential ClassFormatErrors.
1003   //
1004   // Note: "name" is updated.
1005 
1006   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1007                                                              loader_data,
1008                                                              protection_domain,
1009                                                              host_klass,
1010                                                              cp_patches,
1011                                                              parsed_name,
1012                                                              true,
1013                                                              THREAD);
1014 
1015 
1016   if (host_klass.not_null() && k.not_null()) {
1017     assert(EnableInvokeDynamic, "");
1018     // If it's anonymous, initialize it now, since nobody else will.
1019 
1020     {
1021       MutexLocker mu_r(Compile_lock, THREAD);
1022 
1023       // Add to class hierarchy, initialize vtables, and do possible
1024       // deoptimizations.
1025       add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1026 
1027       // But, do not add to system dictionary.
1028 
1029       // compiled code dependencies need to be validated anyway
1030       notice_modification();
1031     }
1032 
1033     // Rewrite and patch constant pool here.
1034     k->link_class(CHECK_NULL);
1035     if (cp_patches != NULL) {
1036       k->constants()->patch_resolved_references(cp_patches);
1037     }
1038     k->eager_initialize(CHECK_NULL);
1039 
1040     // notify jvmti
1041     if (JvmtiExport::should_post_class_load()) {
1042         assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1043         JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1044     }
1045 
1046     post_class_load_event(class_load_start_time, k, class_loader);
1047   }
1048   assert(host_klass.not_null() || cp_patches == NULL,
1049          "cp_patches only found with host_klass");
1050 
1051   return k();
1052 }
1053 
1054 // Add a klass to the system from a stream (called by jni_DefineClass and
1055 // JVM_DefineClass).
1056 // Note: class_name can be NULL. In that case we do not know the name of
1057 // the class until we have parsed the stream.
1058 
1059 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1060                                              Handle class_loader,
1061                                              Handle protection_domain,
1062                                              ClassFileStream* st,
1063                                              bool verify,
1064                                              TRAPS) {
1065 
1066   // Classloaders that support parallelism, e.g. bootstrap classloader,
1067   // or all classloaders with UnsyncloadClass do not acquire lock here
1068   bool DoObjectLock = true;
1069   if (is_parallelCapable(class_loader)) {
1070     DoObjectLock = false;
1071   }
1072 
1073   ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1074 
1075   // Make sure we are synchronized on the class loader before we proceed
1076   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1077   check_loader_lock_contention(lockObject, THREAD);
1078   ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1079 
1080   TempNewSymbol parsed_name = NULL;
1081 
1082   // Parse the stream. Note that we do this even though this klass might
1083   // already be present in the SystemDictionary, otherwise we would not
1084   // throw potential ClassFormatErrors.
1085   //
1086   // Note: "name" is updated.
1087 
1088   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1089                                                              loader_data,
1090                                                              protection_domain,
1091                                                              parsed_name,
1092                                                              verify,
1093                                                              THREAD);

1094 
1095   const char* pkg = "java/";
1096   size_t pkglen = strlen(pkg);
1097   if (!HAS_PENDING_EXCEPTION &&
1098       !class_loader.is_null() &&
1099       parsed_name != NULL &&
1100       parsed_name->utf8_length() >= (int)pkglen &&
1101       !strncmp((const char*)parsed_name->bytes(), pkg, pkglen)) {
1102     // It is illegal to define classes in the "java." package from
1103     // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1104     ResourceMark rm(THREAD);
1105     char* name = parsed_name->as_C_string();
1106     char* index = strrchr(name, '/');
1107     assert(index != NULL, "must be");
1108     *index = '\0'; // chop to just the package name
1109     while ((index = strchr(name, '/')) != NULL) {
1110       *index = '.'; // replace '/' with '.' in package name
1111     }
1112     const char* fmt = "Prohibited package name: %s";
1113     size_t len = strlen(fmt) + strlen(name);
1114     char* message = NEW_RESOURCE_ARRAY(char, len);
1115     jio_snprintf(message, len, fmt, name);
1116     Exceptions::_throw_msg(THREAD_AND_LOCATION,
1117       vmSymbols::java_lang_SecurityException(), message);
1118   }
1119 
1120   if (!HAS_PENDING_EXCEPTION) {
1121     assert(parsed_name != NULL, "Sanity");
1122     assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1123     // Verification prevents us from creating names with dots in them, this
1124     // asserts that that's the case.
1125     assert(is_internal_format(parsed_name),
1126            "external class name format used internally");
1127 








1128     // Add class just loaded
1129     // If a class loader supports parallel classloading handle parallel define requests
1130     // find_or_define_instance_class may return a different InstanceKlass
1131     if (is_parallelCapable(class_loader)) {
1132       k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1133     } else {
1134       define_instance_class(k, THREAD);
1135     }
1136   }
1137 
1138   // Make sure we have an entry in the SystemDictionary on success
1139   debug_only( {
1140     if (!HAS_PENDING_EXCEPTION) {
1141       assert(parsed_name != NULL, "parsed_name is still null?");
1142       Symbol*  h_name    = k->name();
1143       ClassLoaderData *defining_loader_data = k->class_loader_data();
1144 
1145       MutexLocker mu(SystemDictionary_lock, THREAD);
1146 
1147       Klass* check = find_class(parsed_name, loader_data);
1148       assert(check == k(), "should be present in the dictionary");
1149 
1150       Klass* check2 = find_class(h_name, defining_loader_data);
1151       assert(check == check2, "name inconsistancy in SystemDictionary");
1152     }
1153   } );
1154 
1155   return k();
1156 }
1157 
1158 #if INCLUDE_CDS
1159 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1160                                              int number_of_entries) {
1161   assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1162          "bad shared dictionary size.");
1163   _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1164 }
1165 
1166 
1167 // If there is a shared dictionary, then find the entry for the
1168 // given shared system class, if any.
1169 
1170 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1171   if (shared_dictionary() != NULL) {
1172     unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1173     int d_index = shared_dictionary()->hash_to_index(d_hash);
1174 
1175     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1176   } else {
1177     return NULL;
1178   }
1179 }
1180 
1181 
1182 // Load a class from the shared spaces (found through the shared system
1183 // dictionary).  Force the superclass and all interfaces to be loaded.
1184 // Update the class definition to include sibling classes and no
1185 // subclasses (yet).  [Classes in the shared space are not part of the
1186 // object hierarchy until loaded.]
1187 
1188 instanceKlassHandle SystemDictionary::load_shared_class(
1189                  Symbol* class_name, Handle class_loader, TRAPS) {
1190   instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1191   // Make sure we only return the boot class for the NULL classloader.
1192   if (ik.not_null() &&
1193       SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) {
1194     Handle protection_domain;
1195     return load_shared_class(ik, class_loader, protection_domain, THREAD);
1196   }
1197   return instanceKlassHandle();
1198 }
1199 
1200 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik,
1201                                                         Handle class_loader,
1202                                                         Handle protection_domain, TRAPS) {
1203   if (ik.not_null()) {
1204     instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1205     Symbol* class_name = ik->name();
1206 
1207     // Found the class, now load the superclass and interfaces.  If they
1208     // are shared, add them to the main system dictionary and reset
1209     // their hierarchy references (supers, subs, and interfaces).
1210 
1211     if (ik->super() != NULL) {
1212       Symbol*  cn = ik->super()->name();
1213       Klass *s = resolve_super_or_fail(class_name, cn,
1214                                        class_loader, protection_domain, true, CHECK_(nh));
1215       if (s != ik->super()) {
1216         // The dynamically resolved super class is not the same as the one we used during dump time,
1217         // so we cannot use ik.
1218         return nh;
1219       }
1220     }
1221 
1222     Array<Klass*>* interfaces = ik->local_interfaces();
1223     int num_interfaces = interfaces->length();
1224     for (int index = 0; index < num_interfaces; index++) {
1225       Klass* k = interfaces->at(index);
1226 
1227       // Note: can not use InstanceKlass::cast here because
1228       // interfaces' InstanceKlass's C++ vtbls haven't been
1229       // reinitialized yet (they will be once the interface classes
1230       // are loaded)
1231       Symbol*  name  = k->name();
1232       Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh));
1233       if (k != i) {
1234         // The dynamically resolved interface class is not the same as the one we used during dump time,
1235         // so we cannot use ik.
1236         return nh;
1237       }
1238     }
1239 
1240     // Adjust methods to recover missing data.  They need addresses for
1241     // interpreter entry points and their default native method address
1242     // must be reset.
1243 
1244     // Updating methods must be done under a lock so multiple
1245     // threads don't update these in parallel
1246     //
1247     // Shared classes are all currently loaded by either the bootstrap or
1248     // internal parallel class loaders, so this will never cause a deadlock
1249     // on a custom class loader lock.
1250 
1251     ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1252     {
1253       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1254       check_loader_lock_contention(lockObject, THREAD);
1255       ObjectLocker ol(lockObject, THREAD, true);
1256       ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh));
1257     }
1258 
1259     if (TraceClassLoading) {
1260       ResourceMark rm;
1261       tty->print("[Loaded %s", ik->external_name());
1262       tty->print(" from shared objects file");
1263       if (class_loader.not_null()) {
1264         tty->print(" by %s", loader_data->loader_name());
1265       }
1266       tty->print_cr("]");
1267     }
1268 
1269     if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1270       // Only dump the classes that can be stored into CDS archive
1271       if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1272         ResourceMark rm(THREAD);
1273         classlist_file->print_cr("%s", ik->name()->as_C_string());
1274         classlist_file->flush();
1275       }
1276     }
1277 
1278     // notify a class loaded from shared object
1279     ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()),
1280                                              true /* shared class */);
1281   }
1282   return ik;
1283 }
1284 #endif // INCLUDE_CDS
1285 
1286 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1287   instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1288   if (class_loader.is_null()) {
1289 
1290     // Search the shared system dictionary for classes preloaded into the
1291     // shared spaces.
1292     instanceKlassHandle k;
1293     {
1294 #if INCLUDE_CDS
1295       PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1296       k = load_shared_class(class_name, class_loader, THREAD);
1297 #endif
1298     }
1299 
1300     if (k.is_null()) {
1301       // Use VM class loader
1302       PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1303       k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1304     }
1305 
1306     // find_or_define_instance_class may return a different InstanceKlass
1307     if (!k.is_null()) {
1308       k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1309     }


















1310     return k;
1311   } else {
1312     // Use user specified class loader to load class. Call loadClass operation on class_loader.
1313     ResourceMark rm(THREAD);
1314 
1315     assert(THREAD->is_Java_thread(), "must be a JavaThread");
1316     JavaThread* jt = (JavaThread*) THREAD;
1317 
1318     PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1319                                ClassLoader::perf_app_classload_selftime(),
1320                                ClassLoader::perf_app_classload_count(),
1321                                jt->get_thread_stat()->perf_recursion_counts_addr(),
1322                                jt->get_thread_stat()->perf_timers_addr(),
1323                                PerfClassTraceTime::CLASS_LOAD);
1324 
1325     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1326     // Translate to external class name format, i.e., convert '/' chars to '.'
1327     Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1328 
1329     JavaValue result(T_OBJECT);
1330 
1331     KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1332 
1333     // Call public unsynchronized loadClass(String) directly for all class loaders
1334     // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1335     // acquire a class-name based lock rather than the class loader object lock.
1336     // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1337     // so the call to loadClassInternal() was not required.
1338     //
1339     // UnsyncloadClass flag means both call loadClass(String) and do
1340     // not acquire the class loader lock even for class loaders that are
1341     // not parallelCapable. This was a risky transitional
1342     // flag for diagnostic purposes only. It is risky to call
1343     // custom class loaders without synchronization.
1344     // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1345     // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1346     // Do NOT assume this will be supported in future releases.
1347     //
1348     // Added MustCallLoadClassInternal in case we discover in the field
1349     // a customer that counts on this call
1350     if (MustCallLoadClassInternal && has_loadClassInternal()) {
1351       JavaCalls::call_special(&result,
1352                               class_loader,
1353                               spec_klass,
1354                               vmSymbols::loadClassInternal_name(),
1355                               vmSymbols::string_class_signature(),
1356                               string,
1357                               CHECK_(nh));
1358     } else {
1359       JavaCalls::call_virtual(&result,
1360                               class_loader,
1361                               spec_klass,
1362                               vmSymbols::loadClass_name(),
1363                               vmSymbols::string_class_signature(),
1364                               string,
1365                               CHECK_(nh));
1366     }
1367 
1368     assert(result.get_type() == T_OBJECT, "just checking");
1369     oop obj = (oop) result.get_jobject();
1370 
1371     // Primitive classes return null since forName() can not be
1372     // used to obtain any of the Class objects representing primitives or void
1373     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1374       instanceKlassHandle k =
1375                 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1376       // For user defined Java class loaders, check that the name returned is
1377       // the same as that requested.  This check is done for the bootstrap
1378       // loader when parsing the class file.
1379       if (class_name == k->name()) {
1380         return k;
1381       }
1382     }
1383     // Class is not found or has the wrong name, return NULL
1384     return nh;
1385   }
1386 }
1387 









1388 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1389 
1390   ClassLoaderData* loader_data = k->class_loader_data();
1391   Handle class_loader_h(THREAD, loader_data->class_loader());
1392 
1393   for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){}
1394 
1395  // for bootstrap and other parallel classloaders don't acquire lock,
1396  // use placeholder token
1397  // If a parallelCapable class loader calls define_instance_class instead of
1398  // find_or_define_instance_class to get here, we have a timing
1399  // hole with systemDictionary updates and check_constraints
1400  if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1401     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1402          compute_loader_lock_object(class_loader_h, THREAD)),
1403          "define called without lock");
1404   }
1405 
1406   // Check class-loading constraints. Throw exception if violation is detected.
1407   // Grabs and releases SystemDictionary_lock
1408   // The check_constraints/find_class call and update_dictionary sequence
1409   // must be "atomic" for a specific class/classloader pair so we never
1410   // define two different instanceKlasses for that class/classloader pair.
1411   // Existing classloaders will call define_instance_class with the
1412   // classloader lock held
1413   // Parallel classloaders will call find_or_define_instance_class
1414   // which will require a token to perform the define class
1415   Symbol*  name_h = k->name();
1416   unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1417   int d_index = dictionary()->hash_to_index(d_hash);
1418   check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1419 
1420   // Register class just loaded with class loader (placed in Vector)
1421   // Note we do this before updating the dictionary, as this can
1422   // fail with an OutOfMemoryError (if it does, we will *not* put this
1423   // class in the dictionary and will not update the class hierarchy).
1424   // JVMTI FollowReferences needs to find the classes this way.
1425   if (k->class_loader() != NULL) {
1426     methodHandle m(THREAD, Universe::loader_addClass_method());
1427     JavaValue result(T_VOID);
1428     JavaCallArguments args(class_loader_h);
1429     args.push_oop(Handle(THREAD, k->java_mirror()));
1430     JavaCalls::call(&result, m, &args, CHECK);
1431   }
1432 
1433   // Add the new class. We need recompile lock during update of CHA.
1434   {
1435     unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1436     int p_index = placeholders()->hash_to_index(p_hash);
1437 
1438     MutexLocker mu_r(Compile_lock, THREAD);
1439 
1440     // Add to class hierarchy, initialize vtables, and do possible
1441     // deoptimizations.
1442     add_to_hierarchy(k, CHECK); // No exception, but can block
1443 
1444     // Add to systemDictionary - so other classes can see it.
1445     // Grabs and releases SystemDictionary_lock
1446     update_dictionary(d_index, d_hash, p_index, p_hash,
1447                       k, class_loader_h, THREAD);
1448   }
1449   k->eager_initialize(THREAD);
1450 
1451   // notify jvmti
1452   if (JvmtiExport::should_post_class_load()) {
1453       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1454       JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1455 
1456   }
1457 

1458 }
1459 
1460 // Support parallel classloading
1461 // All parallel class loaders, including bootstrap classloader
1462 // lock a placeholder entry for this class/class_loader pair
1463 // to allow parallel defines of different classes for this class loader
1464 // With AllowParallelDefine flag==true, in case they do not synchronize around
1465 // FindLoadedClass/DefineClass, calls, we check for parallel
1466 // loading for them, wait if a defineClass is in progress
1467 // and return the initial requestor's results
1468 // This flag does not apply to the bootstrap classloader.
1469 // With AllowParallelDefine flag==false, call through to define_instance_class
1470 // which will throw LinkageError: duplicate class definition.
1471 // False is the requested default.
1472 // For better performance, the class loaders should synchronize
1473 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1474 // potentially waste time reading and parsing the bytestream.
1475 // Note: VM callers should ensure consistency of k/class_name,class_loader
1476 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1477 
1478   instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1479   Symbol*  name_h = k->name(); // passed in class_name may be null
1480   ClassLoaderData* loader_data = class_loader_data(class_loader);
1481 
1482   unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1483   int d_index = dictionary()->hash_to_index(d_hash);
1484 
1485 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1486   unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1487   int p_index = placeholders()->hash_to_index(p_hash);
1488   PlaceholderEntry* probe;
1489 
1490   {
1491     MutexLocker mu(SystemDictionary_lock, THREAD);
1492     // First check if class already defined
1493     if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1494       Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1495       if (check != NULL) {
1496         return(instanceKlassHandle(THREAD, check));
1497       }
1498     }
1499 
1500     // Acquire define token for this class/classloader
1501     probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1502     // Wait if another thread defining in parallel
1503     // All threads wait - even those that will throw duplicate class: otherwise
1504     // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1505     // if other thread has not finished updating dictionary
1506     while (probe->definer() != NULL) {
1507       SystemDictionary_lock->wait();
1508     }
1509     // Only special cases allow parallel defines and can use other thread's results
1510     // Other cases fall through, and may run into duplicate defines
1511     // caught by finding an entry in the SystemDictionary
1512     if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1513         placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1514         SystemDictionary_lock->notify_all();
1515 #ifdef ASSERT
1516         Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1517         assert(check != NULL, "definer missed recording success");
1518 #endif
1519         return(instanceKlassHandle(THREAD, probe->instance_klass()));
1520     } else {
1521       // This thread will define the class (even if earlier thread tried and had an error)
1522       probe->set_definer(THREAD);
1523     }
1524   }
1525 
1526   define_instance_class(k, THREAD);
1527 
1528   Handle linkage_exception = Handle(); // null handle
1529 
1530   // definer must notify any waiting threads
1531   {
1532     MutexLocker mu(SystemDictionary_lock, THREAD);
1533     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1534     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1535     if (probe != NULL) {
1536       if (HAS_PENDING_EXCEPTION) {
1537         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1538         CLEAR_PENDING_EXCEPTION;
1539       } else {
1540         probe->set_instance_klass(k());
1541       }
1542       probe->set_definer(NULL);
1543       placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1544       SystemDictionary_lock->notify_all();
1545     }
1546   }
1547 
1548   // Can't throw exception while holding lock due to rank ordering
1549   if (linkage_exception() != NULL) {
1550     THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1551   }
1552 
1553   return k;
1554 }
1555 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1556   // If class_loader is NULL we synchronize on _system_loader_lock_obj
1557   if (class_loader.is_null()) {
1558     return Handle(THREAD, _system_loader_lock_obj);
1559   } else {
1560     return class_loader;
1561   }
1562 }
1563 
1564 // This method is added to check how often we have to wait to grab loader
1565 // lock. The results are being recorded in the performance counters defined in
1566 // ClassLoader::_sync_systemLoaderLockContentionRate and
1567 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1568 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1569   if (!UsePerfData) {
1570     return;
1571   }
1572 
1573   assert(!loader_lock.is_null(), "NULL lock object");
1574 
1575   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1576       == ObjectSynchronizer::owner_other) {
1577     // contention will likely happen, so increment the corresponding
1578     // contention counter.
1579     if (loader_lock() == _system_loader_lock_obj) {
1580       ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1581     } else {
1582       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1583     }
1584   }
1585 }
1586 
1587 // ----------------------------------------------------------------------------
1588 // Lookup
1589 
1590 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1591                                       Symbol* class_name,
1592                                       ClassLoaderData* loader_data) {
1593   assert_locked_or_safepoint(SystemDictionary_lock);
1594   assert (index == dictionary()->index_for(class_name, loader_data),
1595           "incorrect index?");
1596 
1597   Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1598   return k;
1599 }
1600 
1601 
1602 // Basic find on classes in the midst of being loaded
1603 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1604                                            ClassLoaderData* loader_data) {
1605   assert_locked_or_safepoint(SystemDictionary_lock);
1606   unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1607   int p_index = placeholders()->hash_to_index(p_hash);
1608   return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1609 }
1610 
1611 
1612 // Used for assertions and verification only
1613 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1614   #ifndef ASSERT
1615   guarantee(VerifyBeforeGC      ||
1616             VerifyDuringGC      ||
1617             VerifyBeforeExit    ||
1618             VerifyDuringStartup ||
1619             VerifyAfterGC, "too expensive");
1620   #endif
1621   assert_locked_or_safepoint(SystemDictionary_lock);
1622 
1623   // First look in the loaded class array
1624   unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1625   int d_index = dictionary()->hash_to_index(d_hash);
1626   return find_class(d_index, d_hash, class_name, loader_data);
1627 }
1628 
1629 
1630 // Get the next class in the diictionary.
1631 Klass* SystemDictionary::try_get_next_class() {
1632   return dictionary()->try_get_next_class();
1633 }
1634 
1635 
1636 // ----------------------------------------------------------------------------
1637 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1638 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1639 // before a new class is used.
1640 
1641 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1642   assert(k.not_null(), "just checking");
1643   assert_locked_or_safepoint(Compile_lock);
1644 
1645   // Link into hierachy. Make sure the vtables are initialized before linking into
1646   k->append_to_sibling_list();                    // add to superklass/sibling list
1647   k->process_interfaces(THREAD);                  // handle all "implements" declarations
1648   k->set_init_state(InstanceKlass::loaded);
1649   // Now flush all code that depended on old class hierarchy.
1650   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1651   // Also, first reinitialize vtable because it may have gotten out of synch
1652   // while the new class wasn't connected to the class hierarchy.
1653   Universe::flush_dependents_on(k);
1654 }
1655 
1656 // ----------------------------------------------------------------------------
1657 // GC support
1658 
1659 // Following roots during mark-sweep is separated in two phases.
1660 //
1661 // The first phase follows preloaded classes and all other system
1662 // classes, since these will never get unloaded anyway.
1663 //
1664 // The second phase removes (unloads) unreachable classes from the
1665 // system dictionary and follows the remaining classes' contents.
1666 
1667 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1668   roots_oops_do(blk, NULL);
1669 }
1670 
1671 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1672   // Follow all system classes and temporary placeholders in dictionary
1673   dictionary()->always_strong_classes_do(closure);
1674 
1675   // Placeholders. These represent classes we're actively loading.
1676   placeholders()->classes_do(closure);
1677 }
1678 
1679 // Calculate a "good" systemdictionary size based
1680 // on predicted or current loaded classes count
1681 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1682   int newsize = _old_default_sdsize;
1683   if ((classcount > 0)  && !DumpSharedSpaces) {
1684     int desiredsize = classcount/_average_depth_goal;
1685     for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1686          newsize = _primelist[++_sdgeneration]) {
1687       if (desiredsize <=  newsize) {
1688         break;
1689       }
1690     }
1691   }
1692   return newsize;
1693 }
1694 
1695 #ifdef ASSERT
1696 class VerifySDReachableAndLiveClosure : public OopClosure {
1697 private:
1698   BoolObjectClosure* _is_alive;
1699 
1700   template <class T> void do_oop_work(T* p) {
1701     oop obj = oopDesc::load_decode_heap_oop(p);
1702     guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
1703   }
1704 
1705 public:
1706   VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1707 
1708   virtual void do_oop(oop* p)       { do_oop_work(p); }
1709   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1710 };
1711 #endif
1712 
1713 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1714 // Note: anonymous classes are not in the SD.
1715 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive, bool clean_alive) {
1716   // First, mark for unload all ClassLoaderData referencing a dead class loader.
1717   bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive, clean_alive);
1718   if (unloading_occurred) {

1719     dictionary()->do_unloading();
1720     constraints()->purge_loader_constraints();
1721     resolution_errors()->purge_resolution_errors();
1722   }
1723   // Oops referenced by the system dictionary may get unreachable independently
1724   // of the class loader (eg. cached protection domain oops). So we need to
1725   // explicitly unlink them here instead of in Dictionary::do_unloading.
1726   dictionary()->unlink(is_alive);
1727 #ifdef ASSERT
1728   VerifySDReachableAndLiveClosure cl(is_alive);
1729   dictionary()->oops_do(&cl);
1730 #endif
1731   return unloading_occurred;
1732 }
1733 
1734 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1735   strong->do_oop(&_java_system_loader);
1736   strong->do_oop(&_system_loader_lock_obj);
1737   CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1738 
1739   // Adjust dictionary
1740   dictionary()->roots_oops_do(strong, weak);
1741 
1742   // Visit extra methods
1743   invoke_method_table()->oops_do(strong);
1744 }
1745 
1746 void SystemDictionary::oops_do(OopClosure* f) {
1747   f->do_oop(&_java_system_loader);
1748   f->do_oop(&_system_loader_lock_obj);
1749   CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1750 
1751   // Adjust dictionary
1752   dictionary()->oops_do(f);
1753 
1754   // Visit extra methods
1755   invoke_method_table()->oops_do(f);
1756 }
1757 
1758 // Extended Class redefinition support.
1759 // If one of these classes is replaced, we need to replace it in these places.
1760 // KlassClosure::do_klass should take the address of a class but we can
1761 // change that later.
1762 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1763   for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1764     f->do_klass(_well_known_klasses[k]);
1765   }
1766 
1767   {
1768     for (int i = 0; i < T_VOID+1; i++) {
1769       if (_box_klasses[i] != NULL) {
1770         assert(i >= T_BOOLEAN, "checking");
1771         f->do_klass(_box_klasses[i]);
1772       }
1773     }
1774   }
1775 
1776   FilteredFieldsMap::classes_do(f);
1777 }
1778 
1779 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1780   f->do_klass(_abstract_ownable_synchronizer_klass);
1781 }
1782 
1783 // Just the classes from defining class loaders
1784 // Don't iterate over placeholders
1785 void SystemDictionary::classes_do(void f(Klass*)) {
1786   dictionary()->classes_do(f);
1787 }
1788 
1789 // Added for initialize_itable_for_klass
1790 //   Just the classes from defining class loaders
1791 // Don't iterate over placeholders
1792 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1793   dictionary()->classes_do(f, CHECK);
1794 }
1795 
1796 //   All classes, and their class loaders
1797 // Don't iterate over placeholders
1798 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1799   dictionary()->classes_do(f);
1800 }
1801 
1802 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1803   placeholders()->entries_do(f);
1804 }
1805 
1806 void SystemDictionary::methods_do(void f(Method*)) {
1807   dictionary()->methods_do(f);
1808   invoke_method_table()->methods_do(f);
1809 }
1810 
1811 void SystemDictionary::remove_classes_in_error_state() {
1812   dictionary()->remove_classes_in_error_state();
1813 }
1814 
1815 // ----------------------------------------------------------------------------
1816 // Lazily load klasses
1817 
1818 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1819   assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");
1820 
1821   // if multiple threads calling this function, only one thread will load
1822   // the class.  The other threads will find the loaded version once the
1823   // class is loaded.
1824   Klass* aos = _abstract_ownable_synchronizer_klass;
1825   if (aos == NULL) {
1826     Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1827     // Force a fence to prevent any read before the write completes
1828     OrderAccess::fence();
1829     _abstract_ownable_synchronizer_klass = k;
1830   }
1831 }
1832 
1833 // ----------------------------------------------------------------------------
1834 // Initialization
1835 
1836 void SystemDictionary::initialize(TRAPS) {
1837   // Allocate arrays
1838   assert(dictionary() == NULL,
1839          "SystemDictionary should only be initialized once");
1840   _sdgeneration        = 0;
1841   _dictionary          = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1842   _placeholders        = new PlaceholderTable(_nof_buckets);
1843   _number_of_modifications = 0;
1844   _loader_constraints  = new LoaderConstraintTable(_loader_constraint_size);
1845   _resolution_errors   = new ResolutionErrorTable(_resolution_error_size);
1846   _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1847 
1848   // Allocate private object used as system class loader lock
1849   _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1850   // Initialize basic classes
1851   initialize_preloaded_classes(CHECK);



1852 }
1853 
1854 // Compact table of directions on the initialization of klasses:
1855 static const short wk_init_info[] = {
1856   #define WK_KLASS_INIT_INFO(name, symbol, option) \
1857     ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1858           << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1859       | (int)SystemDictionary::option ),
1860   WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1861   #undef WK_KLASS_INIT_INFO
1862   0
1863 };
1864 
1865 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1866   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1867   int  info = wk_init_info[id - FIRST_WKID];
1868   int  sid  = (info >> CEIL_LG_OPTION_LIMIT);
1869   Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1870   Klass**    klassp = &_well_known_klasses[id];
1871   bool must_load = (init_opt < SystemDictionary::Opt);
1872   if ((*klassp) == NULL) {
1873     if (must_load) {
1874       (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class
1875     } else {
1876       (*klassp) = resolve_or_null(symbol,       CHECK_0); // load optional klass
1877     }
1878   }
1879   return ((*klassp) != NULL);
1880 }
1881 
1882 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1883   assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1884   for (int id = (int)start_id; id < (int)limit_id; id++) {
1885     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1886     int info = wk_init_info[id - FIRST_WKID];
1887     int sid  = (info >> CEIL_LG_OPTION_LIMIT);
1888     int opt  = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1889 
1890     initialize_wk_klass((WKID)id, opt, CHECK);
1891   }
1892 
1893   // move the starting value forward to the limit:
1894   start_id = limit_id;
1895 }
1896 
1897 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1898   assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1899   // Preload commonly used klasses
1900   WKID scan = FIRST_WKID;
1901   // first do Object, then String, Class
1902   if (UseSharedSpaces) {
1903     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1904     // Initialize the constant pool for the Object_class
1905     InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1906     ik->constants()->restore_unshareable_info(CHECK);
1907     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1908   } else {
1909     initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1910   }
1911 
1912   // Calculate offsets for String and Class classes since they are loaded and
1913   // can be used after this point.
1914   java_lang_String::compute_offsets();
1915   java_lang_Class::compute_offsets();
1916 
1917   // Fixup mirrors for classes loaded before java.lang.Class.
1918   // These calls iterate over the objects currently in the perm gen
1919   // so calling them at this point is matters (not before when there
1920   // are fewer objects and not later after there are more objects
1921   // in the perm gen.
1922   Universe::initialize_basic_type_mirrors(CHECK);
1923   Universe::fixup_mirrors(CHECK);
1924 
1925   // do a bunch more:
1926   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1927 
1928   // Preload ref klasses and set reference types
1929   InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1930   InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1931 
1932   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK);
1933   InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1934   InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1935   InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1936   InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1937   InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER);
1938 
1939   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(ReferenceQueue_klass), scan, CHECK);
1940 
1941   // JSR 292 classes
1942   WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1943   WKID jsr292_group_end   = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1944   initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1945   if (EnableInvokeDynamic) {
1946     initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1947   } else {
1948     // Skip the JSR 292 classes, if not enabled.
1949     scan = WKID(jsr292_group_end + 1);
1950   }
1951 
1952   initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);
1953 
1954   _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1955   _box_klasses[T_CHAR]    = WK_KLASS(Character_klass);
1956   _box_klasses[T_FLOAT]   = WK_KLASS(Float_klass);
1957   _box_klasses[T_DOUBLE]  = WK_KLASS(Double_klass);
1958   _box_klasses[T_BYTE]    = WK_KLASS(Byte_klass);
1959   _box_klasses[T_SHORT]   = WK_KLASS(Short_klass);
1960   _box_klasses[T_INT]     = WK_KLASS(Integer_klass);
1961   _box_klasses[T_LONG]    = WK_KLASS(Long_klass);
1962   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);
1963   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);
1964 
1965   { // Compute whether we should use loadClass or loadClassInternal when loading classes.
1966     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
1967     _has_loadClassInternal = (method != NULL);
1968   }
1969   { // Compute whether we should use checkPackageAccess or NOT
1970     Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
1971     _has_checkPackageAccess = (method != NULL);
1972   }
1973 }
1974 
1975 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
1976 // If so, returns the basic type it holds.  If not, returns T_OBJECT.
1977 BasicType SystemDictionary::box_klass_type(Klass* k) {
1978   assert(k != NULL, "");
1979   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
1980     if (_box_klasses[i] == k)
1981       return (BasicType)i;
1982   }
1983   return T_OBJECT;
1984 }
1985 
1986 // Constraints on class loaders. The details of the algorithm can be
1987 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1988 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is
1989 // that the system dictionary needs to maintain a set of contraints that
1990 // must be satisfied by all classes in the dictionary.
1991 // if defining is true, then LinkageError if already in systemDictionary
1992 // if initiating loader, then ok if InstanceKlass matches existing entry
1993 
1994 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
1995                                          instanceKlassHandle k,
1996                                          Handle class_loader, bool defining,
1997                                          TRAPS) {
1998   const char *linkage_error = NULL;
1999   {
2000     Symbol*  name  = k->name();
2001     ClassLoaderData *loader_data = class_loader_data(class_loader);
2002 
2003     MutexLocker mu(SystemDictionary_lock, THREAD);
2004 
2005     Klass* check = find_class(d_index, d_hash, name, loader_data);
2006     if (check != (Klass*)NULL) {
2007       // if different InstanceKlass - duplicate class definition,
2008       // else - ok, class loaded by a different thread in parallel,
2009       // we should only have found it if it was done loading and ok to use
2010       // system dictionary only holds instance classes, placeholders
2011       // also holds array classes
2012 
2013       assert(check->oop_is_instance(), "noninstance in systemdictionary");
2014       if ((defining == true) || (k() != check)) {
2015         linkage_error = "loader (instance of  %s): attempted  duplicate class "
2016           "definition for name: \"%s\"";
2017       } else {
2018         return;
2019       }
2020     }
2021 
2022 #ifdef ASSERT
2023     Symbol* ph_check = find_placeholder(name, loader_data);
2024     assert(ph_check == NULL || ph_check == name, "invalid symbol");
2025 #endif
2026 
2027     if (linkage_error == NULL) {
2028       if (constraints()->check_or_update(k, class_loader, name) == false) {
2029         linkage_error = "loader constraint violation: loader (instance of %s)"
2030           " previously initiated loading for a different type with name \"%s\"";
2031       }
2032     }
2033   }
2034 
2035   // Throw error now if needed (cannot throw while holding
2036   // SystemDictionary_lock because of rank ordering)
2037 
2038   if (linkage_error) {
2039     ResourceMark rm(THREAD);
2040     const char* class_loader_name = loader_name(class_loader());
2041     char* type_name = k->name()->as_C_string();
2042     size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +
2043       strlen(type_name);
2044     char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2045     jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);
2046     THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2047   }
2048 }
2049 
2050 
2051 // Update system dictionary - done after check_constraint and add_to_hierachy
2052 // have been called.
2053 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2054                                          int p_index, unsigned int p_hash,
2055                                          instanceKlassHandle k,
2056                                          Handle class_loader,
2057                                          TRAPS) {
2058   // Compile_lock prevents systemDictionary updates during compilations
2059   assert_locked_or_safepoint(Compile_lock);
2060   Symbol*  name  = k->name();
2061   ClassLoaderData *loader_data = class_loader_data(class_loader);
2062 
2063   {
2064   MutexLocker mu1(SystemDictionary_lock, THREAD);
2065 
2066   // See whether biased locking is enabled and if so set it for this
2067   // klass.
2068   // Note that this must be done past the last potential blocking
2069   // point / safepoint. We enable biased locking lazily using a
2070   // VM_Operation to iterate the SystemDictionary and installing the
2071   // biasable mark word into each InstanceKlass's prototype header.
2072   // To avoid race conditions where we accidentally miss enabling the
2073   // optimization for one class in the process of being added to the
2074   // dictionary, we must not safepoint after the test of
2075   // BiasedLocking::enabled().
2076   if (UseBiasedLocking && BiasedLocking::enabled()) {
2077     // Set biased locking bit for all loaded classes; it will be
2078     // cleared if revocation occurs too often for this type
2079     // NOTE that we must only do this when the class is initally
2080     // defined, not each time it is referenced from a new class loader
2081     if (k->class_loader() == class_loader()) {
2082       k->set_prototype_header(markOopDesc::biased_locking_prototype());
2083     }
2084   }
2085 
2086   // Make a new system dictionary entry.
2087   Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2088   if (sd_check == NULL) {
2089     dictionary()->add_klass(name, loader_data, k);
2090     notice_modification();
2091   }
2092 #ifdef ASSERT
2093   sd_check = find_class(d_index, d_hash, name, loader_data);
2094   assert (sd_check != NULL, "should have entry in system dictionary");
2095   // Note: there may be a placeholder entry: for circularity testing
2096   // or for parallel defines
2097 #endif
2098     SystemDictionary_lock->notify_all();
2099   }
2100 }
2101 
2102 
2103 // Try to find a class name using the loader constraints.  The
2104 // loader constraints might know about a class that isn't fully loaded
2105 // yet and these will be ignored.
2106 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2107                     Symbol* class_name, Handle class_loader, TRAPS) {
2108 
2109   // First see if it has been loaded directly.
2110   // Force the protection domain to be null.  (This removes protection checks.)
2111   Handle no_protection_domain;
2112   Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2113                                               no_protection_domain, CHECK_NULL);
2114   if (klass != NULL)
2115     return klass;
2116 
2117   // Now look to see if it has been loaded elsewhere, and is subject to
2118   // a loader constraint that would require this loader to return the
2119   // klass that is already loaded.
2120   if (FieldType::is_array(class_name)) {
2121     // For array classes, their Klass*s are not kept in the
2122     // constraint table. The element Klass*s are.
2123     FieldArrayInfo fd;
2124     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2125     if (t != T_OBJECT) {
2126       klass = Universe::typeArrayKlassObj(t);
2127     } else {
2128       MutexLocker mu(SystemDictionary_lock, THREAD);
2129       klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2130     }
2131     // If element class already loaded, allocate array klass
2132     if (klass != NULL) {
2133       klass = klass->array_klass_or_null(fd.dimension());
2134     }
2135   } else {
2136     MutexLocker mu(SystemDictionary_lock, THREAD);
2137     // Non-array classes are easy: simply check the constraint table.
2138     klass = constraints()->find_constrained_klass(class_name, class_loader);
2139   }
2140 
2141   return klass;
2142 }
2143 
2144 
2145 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2146                                              Handle class_loader1,
2147                                              Handle class_loader2,
2148                                              Thread* THREAD) {
2149   ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2150   ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2151 
2152   Symbol* constraint_name = NULL;
2153   if (!FieldType::is_array(class_name)) {
2154     constraint_name = class_name;
2155   } else {
2156     // For array classes, their Klass*s are not kept in the
2157     // constraint table. The element classes are.
2158     FieldArrayInfo fd;
2159     BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2160     // primitive types always pass
2161     if (t != T_OBJECT) {
2162       return true;
2163     } else {
2164       constraint_name = fd.object_key();
2165     }
2166   }
2167   unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2168   int d_index1 = dictionary()->hash_to_index(d_hash1);
2169 
2170   unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2171   int d_index2 = dictionary()->hash_to_index(d_hash2);
2172   {
2173   MutexLocker mu_s(SystemDictionary_lock, THREAD);
2174 
2175   // Better never do a GC while we're holding these oops
2176   No_Safepoint_Verifier nosafepoint;
2177 
2178   Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2179   Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2180   return constraints()->add_entry(constraint_name, klass1, class_loader1,
2181                                   klass2, class_loader2);
2182   }
2183 }
2184 
2185 // Add entry to resolution error table to record the error when the first
2186 // attempt to resolve a reference to a class has failed.
2187 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, Symbol* error) {
2188   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2189   int index = resolution_errors()->hash_to_index(hash);
2190   {
2191     MutexLocker ml(SystemDictionary_lock, Thread::current());
2192     resolution_errors()->add_entry(index, hash, pool, which, error);
2193   }
2194 }
2195 
2196 // Delete a resolution error for RedefineClasses for a constant pool is going away
2197 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2198   resolution_errors()->delete_entry(pool);
2199 }
2200 
2201 // Lookup resolution error table. Returns error if found, otherwise NULL.
2202 Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {
2203   unsigned int hash = resolution_errors()->compute_hash(pool, which);
2204   int index = resolution_errors()->hash_to_index(hash);
2205   {
2206     MutexLocker ml(SystemDictionary_lock, Thread::current());
2207     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2208     return (entry != NULL) ? entry->error() : (Symbol*)NULL;
2209   }
2210 }
2211 
2212 
2213 // Signature constraints ensure that callers and callees agree about
2214 // the meaning of type names in their signatures.  This routine is the
2215 // intake for constraints.  It collects them from several places:
2216 //
2217 //  * LinkResolver::resolve_method (if check_access is true) requires
2218 //    that the resolving class (the caller) and the defining class of
2219 //    the resolved method (the callee) agree on each type in the
2220 //    method's signature.
2221 //
2222 //  * LinkResolver::resolve_interface_method performs exactly the same
2223 //    checks.
2224 //
2225 //  * LinkResolver::resolve_field requires that the constant pool
2226 //    attempting to link to a field agree with the field's defining
2227 //    class about the type of the field signature.
2228 //
2229 //  * klassVtable::initialize_vtable requires that, when a class
2230 //    overrides a vtable entry allocated by a superclass, that the
2231 //    overriding method (i.e., the callee) agree with the superclass
2232 //    on each type in the method's signature.
2233 //
2234 //  * klassItable::initialize_itable requires that, when a class fills
2235 //    in its itables, for each non-abstract method installed in an
2236 //    itable, the method (i.e., the callee) agree with the interface
2237 //    on each type in the method's signature.
2238 //
2239 // All those methods have a boolean (check_access, checkconstraints)
2240 // which turns off the checks.  This is used from specialized contexts
2241 // such as bootstrapping, dumping, and debugging.
2242 //
2243 // No direct constraint is placed between the class and its
2244 // supertypes.  Constraints are only placed along linked relations
2245 // between callers and callees.  When a method overrides or implements
2246 // an abstract method in a supertype (superclass or interface), the
2247 // constraints are placed as if the supertype were the caller to the
2248 // overriding method.  (This works well, since callers to the
2249 // supertype have already established agreement between themselves and
2250 // the supertype.)  As a result of all this, a class can disagree with
2251 // its supertype about the meaning of a type name, as long as that
2252 // class neither calls a relevant method of the supertype, nor is
2253 // called (perhaps via an override) from the supertype.
2254 //
2255 //
2256 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2257 //
2258 // Make sure all class components (including arrays) in the given
2259 // signature will be resolved to the same class in both loaders.
2260 // Returns the name of the type that failed a loader constraint check, or
2261 // NULL if no constraint failed.  No exception except OOME is thrown.
2262 // Arrays are not added to the loader constraint table, their elements are.
2263 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2264                                                Handle loader1, Handle loader2,
2265                                                bool is_method, TRAPS)  {
2266   // Nothing to do if loaders are the same.
2267   if (loader1() == loader2()) {
2268     return NULL;
2269   }
2270 
2271   SignatureStream sig_strm(signature, is_method);
2272   while (!sig_strm.is_done()) {
2273     if (sig_strm.is_object()) {
2274       Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2275       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2276         return sig;
2277       }
2278     }
2279     sig_strm.next();
2280   }
2281   return NULL;
2282 }
2283 
2284 
2285 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2286                                                             Symbol* signature,
2287                                                             TRAPS) {
2288   methodHandle empty;
2289   assert(EnableInvokeDynamic, "");
2290   assert(MethodHandles::is_signature_polymorphic(iid) &&
2291          MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2292          iid != vmIntrinsics::_invokeGeneric,
2293          err_msg("must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)));
2294 
2295   unsigned int hash  = invoke_method_table()->compute_hash(signature, iid);
2296   int          index = invoke_method_table()->hash_to_index(hash);
2297   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2298   methodHandle m;
2299   if (spe == NULL || spe->method() == NULL) {
2300     spe = NULL;
2301     // Must create lots of stuff here, but outside of the SystemDictionary lock.
2302     m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2303     if (!Arguments::is_interpreter_only()) {
2304       // Generate a compiled form of the MH intrinsic.
2305       AdapterHandlerLibrary::create_native_wrapper(m);
2306       // Check if have the compiled code.
2307       if (!m->has_compiled_code()) {
2308         THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2309                    "out of space in CodeCache for method handle intrinsic", empty);
2310       }
2311     }
2312     // Now grab the lock.  We might have to throw away the new method,
2313     // if a racing thread has managed to install one at the same time.
2314     {
2315       MutexLocker ml(SystemDictionary_lock, THREAD);
2316       spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2317       if (spe == NULL)
2318         spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2319       if (spe->method() == NULL)
2320         spe->set_method(m());
2321     }
2322   }
2323 
2324   assert(spe != NULL && spe->method() != NULL, "");
2325   assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2326          spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2327          "MH intrinsic invariant");
2328   return spe->method();
2329 }
2330 
2331 // Helper for unpacking the return value from linkMethod and linkCallSite.
2332 static methodHandle unpack_method_and_appendix(Handle mname,
2333                                                KlassHandle accessing_klass,
2334                                                objArrayHandle appendix_box,
2335                                                Handle* appendix_result,
2336                                                TRAPS) {
2337   methodHandle empty;
2338   if (mname.not_null()) {
2339     Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2340     if (vmtarget != NULL && vmtarget->is_method()) {
2341       Method* m = (Method*)vmtarget;
2342       oop appendix = appendix_box->obj_at(0);
2343       if (TraceMethodHandles) {
2344     #ifndef PRODUCT
2345         tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2346         m->print();
2347         if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2348         tty->cr();
2349     #endif //PRODUCT
2350       }
2351       (*appendix_result) = Handle(THREAD, appendix);
2352       // the target is stored in the cpCache and if a reference to this
2353       // MethodName is dropped we need a way to make sure the
2354       // class_loader containing this method is kept alive.
2355       // FIXME: the appendix might also preserve this dependency.
2356       ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2357       this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2358       return methodHandle(THREAD, m);
2359     }
2360   }
2361   THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2362   return empty;
2363 }
2364 
2365 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2366                                                           Symbol* signature,
2367                                                           KlassHandle accessing_klass,
2368                                                           Handle *appendix_result,
2369                                                           Handle *method_type_result,
2370                                                           TRAPS) {
2371   methodHandle empty;
2372   assert(EnableInvokeDynamic, "");
2373   assert(!THREAD->is_Compiler_thread(), "");
2374   Handle method_type =
2375     SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2376 
2377   KlassHandle  mh_klass = SystemDictionary::MethodHandle_klass();
2378   int ref_kind = JVM_REF_invokeVirtual;
2379   Handle name_str = StringTable::intern(name, CHECK_(empty));
2380   objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2381   assert(appendix_box->obj_at(0) == NULL, "");
2382 
2383   // This should not happen.  JDK code should take care of that.
2384   if (accessing_klass.is_null() || method_type.is_null()) {
2385     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2386   }
2387 
2388   // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2389   JavaCallArguments args;
2390   args.push_oop(accessing_klass()->java_mirror());
2391   args.push_int(ref_kind);
2392   args.push_oop(mh_klass()->java_mirror());
2393   args.push_oop(name_str());
2394   args.push_oop(method_type());
2395   args.push_oop(appendix_box());
2396   JavaValue result(T_OBJECT);
2397   JavaCalls::call_static(&result,
2398                          SystemDictionary::MethodHandleNatives_klass(),
2399                          vmSymbols::linkMethod_name(),
2400                          vmSymbols::linkMethod_signature(),
2401                          &args, CHECK_(empty));
2402   Handle mname(THREAD, (oop) result.get_jobject());
2403   (*method_type_result) = method_type;
2404   return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2405 }
2406 
2407 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2408 // We must ensure that all class loaders everywhere will reach this class, for any client.
2409 // This is a safe bet for public classes in java.lang, such as Object and String.
2410 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2411 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2412 static bool is_always_visible_class(oop mirror) {
2413   Klass* klass = java_lang_Class::as_Klass(mirror);
2414   if (klass->oop_is_objArray()) {
2415     klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2416   }
2417   if (klass->oop_is_typeArray()) {
2418     return true; // primitive array
2419   }
2420   assert(klass->oop_is_instance(), klass->external_name());
2421   return klass->is_public() &&
2422          (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) ||       // java.lang
2423           InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass()));  // java.lang.invoke
2424 }
2425 
2426 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2427 // signature, as interpreted relative to the given class loader.
2428 // Because of class loader constraints, all method handle usage must be
2429 // consistent with this loader.
2430 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2431                                                  KlassHandle accessing_klass,
2432                                                  TRAPS) {
2433   Handle empty;
2434   vmIntrinsics::ID null_iid = vmIntrinsics::_none;  // distinct from all method handle invoker intrinsics
2435   unsigned int hash  = invoke_method_table()->compute_hash(signature, null_iid);
2436   int          index = invoke_method_table()->hash_to_index(hash);
2437   SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2438   if (spe != NULL && spe->method_type() != NULL) {
2439     assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2440     return Handle(THREAD, spe->method_type());
2441   } else if (THREAD->is_Compiler_thread()) {
2442     warning("SystemDictionary::find_method_handle_type called from compiler thread");  // FIXME
2443     return Handle();  // do not attempt from within compiler, unless it was cached
2444   }
2445 
2446   Handle class_loader, protection_domain;
2447   if (accessing_klass.not_null()) {
2448     class_loader      = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2449     protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2450   }
2451   bool can_be_cached = true;
2452   int npts = ArgumentCount(signature).size();
2453   objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2454   int arg = 0;
2455   Handle rt; // the return type from the signature
2456   ResourceMark rm(THREAD);
2457   for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2458     oop mirror = NULL;
2459     if (can_be_cached) {
2460       // Use neutral class loader to lookup candidate classes to be placed in the cache.
2461       mirror = ss.as_java_mirror(Handle(), Handle(),
2462                                  SignatureStream::ReturnNull, CHECK_(empty));
2463       if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2464         // Fall back to accessing_klass context.
2465         can_be_cached = false;
2466       }
2467     }
2468     if (!can_be_cached) {
2469       // Resolve, throwing a real error if it doesn't work.
2470       mirror = ss.as_java_mirror(class_loader, protection_domain,
2471                                  SignatureStream::NCDFError, CHECK_(empty));
2472     }
2473     assert(!oopDesc::is_null(mirror), ss.as_symbol(THREAD)->as_C_string());
2474     if (ss.at_return_type())
2475       rt = Handle(THREAD, mirror);
2476     else
2477       pts->obj_at_put(arg++, mirror);
2478 
2479     // Check accessibility.
2480     if (ss.is_object() && accessing_klass.not_null()) {
2481       Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2482       mirror = NULL;  // safety
2483       // Emulate ConstantPool::verify_constant_pool_resolve.
2484       if (sel_klass->oop_is_objArray())
2485         sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2486       if (sel_klass->oop_is_instance()) {
2487         KlassHandle sel_kh(THREAD, sel_klass);
2488         LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2489       }
2490     }
2491   }
2492   assert(arg == npts, "");
2493 
2494   // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2495   JavaCallArguments args(Handle(THREAD, rt()));
2496   args.push_oop(pts());
2497   JavaValue result(T_OBJECT);
2498   JavaCalls::call_static(&result,
2499                          SystemDictionary::MethodHandleNatives_klass(),
2500                          vmSymbols::findMethodHandleType_name(),
2501                          vmSymbols::findMethodHandleType_signature(),
2502                          &args, CHECK_(empty));
2503   Handle method_type(THREAD, (oop) result.get_jobject());
2504 
2505   if (can_be_cached) {
2506     // We can cache this MethodType inside the JVM.
2507     MutexLocker ml(SystemDictionary_lock, THREAD);
2508     spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2509     if (spe == NULL)
2510       spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2511     if (spe->method_type() == NULL) {
2512       spe->set_method_type(method_type());
2513     }
2514   }
2515 
2516   // report back to the caller with the MethodType
2517   return method_type;
2518 }
2519 
2520 // Ask Java code to find or construct a method handle constant.
2521 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2522                                                      int ref_kind, //e.g., JVM_REF_invokeVirtual
2523                                                      KlassHandle callee,
2524                                                      Symbol* name_sym,
2525                                                      Symbol* signature,
2526                                                      TRAPS) {
2527   Handle empty;
2528   Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2529   Handle type;
2530   if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2531     type = find_method_handle_type(signature, caller, CHECK_(empty));
2532   } else if (caller.is_null()) {
2533     // This should not happen.  JDK code should take care of that.
2534     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2535   } else {
2536     ResourceMark rm(THREAD);
2537     SignatureStream ss(signature, false);
2538     if (!ss.is_done()) {
2539       oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2540                                      SignatureStream::NCDFError, CHECK_(empty));
2541       type = Handle(THREAD, mirror);
2542       ss.next();
2543       if (!ss.is_done())  type = Handle();  // error!
2544     }
2545   }
2546   if (type.is_null()) {
2547     THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2548   }
2549 
2550   // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2551   JavaCallArguments args;
2552   args.push_oop(caller->java_mirror());  // the referring class
2553   args.push_int(ref_kind);
2554   args.push_oop(callee->java_mirror());  // the target class
2555   args.push_oop(name());
2556   args.push_oop(type());
2557   JavaValue result(T_OBJECT);
2558   JavaCalls::call_static(&result,
2559                          SystemDictionary::MethodHandleNatives_klass(),
2560                          vmSymbols::linkMethodHandleConstant_name(),
2561                          vmSymbols::linkMethodHandleConstant_signature(),
2562                          &args, CHECK_(empty));
2563   return Handle(THREAD, (oop) result.get_jobject());
2564 }
2565 
2566 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2567 // name and signature, as interpreted relative to the given class loader.
2568 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2569                                                               Handle bootstrap_specifier,
2570                                                               Symbol* name,
2571                                                               Symbol* type,
2572                                                               Handle *appendix_result,
2573                                                               Handle *method_type_result,
2574                                                               TRAPS) {
2575   methodHandle empty;
2576   Handle bsm, info;
2577   if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2578     bsm = bootstrap_specifier;
2579   } else {
2580     assert(bootstrap_specifier->is_objArray(), "");
2581     objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2582     int len = args->length();
2583     assert(len >= 1, "");
2584     bsm = Handle(THREAD, args->obj_at(0));
2585     if (len > 1) {
2586       objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2587       for (int i = 1; i < len; i++)
2588         args1->obj_at_put(i-1, args->obj_at(i));
2589       info = Handle(THREAD, args1);
2590     }
2591   }
2592   guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2593             "caller must supply a valid BSM");
2594 
2595   Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2596   Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2597 
2598   // This should not happen.  JDK code should take care of that.
2599   if (caller.is_null() || method_type.is_null()) {
2600     THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2601   }
2602 
2603   objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2604   assert(appendix_box->obj_at(0) == NULL, "");
2605 
2606   // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2607   JavaCallArguments args;
2608   args.push_oop(caller->java_mirror());
2609   args.push_oop(bsm());
2610   args.push_oop(method_name());
2611   args.push_oop(method_type());
2612   args.push_oop(info());
2613   args.push_oop(appendix_box);
2614   JavaValue result(T_OBJECT);
2615   JavaCalls::call_static(&result,
2616                          SystemDictionary::MethodHandleNatives_klass(),
2617                          vmSymbols::linkCallSite_name(),
2618                          vmSymbols::linkCallSite_signature(),
2619                          &args, CHECK_(empty));
2620   Handle mname(THREAD, (oop) result.get_jobject());
2621   (*method_type_result) = method_type;
2622   return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2623 }
2624 
2625 // Since the identity hash code for symbols changes when the symbols are
2626 // moved from the regular perm gen (hash in the mark word) to the shared
2627 // spaces (hash is the address), the classes loaded into the dictionary
2628 // may be in the wrong buckets.
2629 
2630 void SystemDictionary::reorder_dictionary() {
2631   dictionary()->reorder_dictionary();
2632 }
2633 
2634 
2635 void SystemDictionary::copy_buckets(char** top, char* end) {
2636   dictionary()->copy_buckets(top, end);
2637 }
2638 
2639 
2640 void SystemDictionary::copy_table(char** top, char* end) {
2641   dictionary()->copy_table(top, end);
2642 }
2643 
2644 
2645 void SystemDictionary::reverse() {
2646   dictionary()->reverse();
2647 }
2648 
2649 int SystemDictionary::number_of_classes() {
2650   return dictionary()->number_of_entries();
2651 }
2652 
2653 
2654 // ----------------------------------------------------------------------------
2655 void SystemDictionary::print_shared(bool details) {
2656   shared_dictionary()->print(details);
2657 }
2658 
2659 void SystemDictionary::print(bool details) {
2660   dictionary()->print(details);
2661 
2662   // Placeholders
2663   GCMutexLocker mu(SystemDictionary_lock);
2664   placeholders()->print();
2665 
2666   // loader constraints - print under SD_lock
2667   constraints()->print();
2668 }
2669 
2670 
2671 void SystemDictionary::verify() {
2672   guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2673   guarantee(constraints() != NULL,
2674             "Verify of loader constraints failed");
2675   guarantee(dictionary()->number_of_entries() >= 0 &&
2676             placeholders()->number_of_entries() >= 0,
2677             "Verify of system dictionary failed");
2678 
2679   // Verify dictionary
2680   dictionary()->verify();
2681 
2682   GCMutexLocker mu(SystemDictionary_lock);
2683   placeholders()->verify();
2684 
2685   // Verify constraint table
2686   guarantee(constraints() != NULL, "Verify of loader constraints failed");
2687   constraints()->verify(dictionary(), placeholders());
2688 }
2689 
2690 // utility function for class load event
2691 void SystemDictionary::post_class_load_event(const Ticks& start_time,
2692                                              instanceKlassHandle k,
2693                                              Handle initiating_loader) {
2694 #if INCLUDE_TRACE
2695   EventClassLoad event(UNTIMED);
2696   if (event.should_commit()) {
2697     event.set_starttime(start_time);
2698     event.set_loadedClass(k());
2699     oop defining_class_loader = k->class_loader();
2700     event.set_definingClassLoader(defining_class_loader !=  NULL ?
2701                                     defining_class_loader->klass() : (Klass*)NULL);
2702     oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
2703     event.set_initiatingClassLoader(class_loader != NULL ?
2704                                       class_loader->klass() : (Klass*)NULL);
2705     event.commit();
2706   }
2707 #endif // INCLUDE_TRACE
2708 }
2709 
2710 #ifndef PRODUCT
2711 
2712 // statistics code
2713 class ClassStatistics: AllStatic {
2714  private:
2715   static int nclasses;        // number of classes
2716   static int nmethods;        // number of methods
2717   static int nmethoddata;     // number of methodData
2718   static int class_size;      // size of class objects in words
2719   static int method_size;     // size of method objects in words
2720   static int debug_size;      // size of debug info in methods
2721   static int methoddata_size; // size of methodData objects in words
2722 
2723   static void do_class(Klass* k) {
2724     nclasses++;
2725     class_size += k->size();
2726     if (k->oop_is_instance()) {
2727       InstanceKlass* ik = (InstanceKlass*)k;
2728       class_size += ik->methods()->size();
2729       class_size += ik->constants()->size();
2730       class_size += ik->local_interfaces()->size();
2731       class_size += ik->transitive_interfaces()->size();
2732       // We do not have to count implementors, since we only store one!
2733       // SSS: How should these be accounted now that they have moved?
2734       // class_size += ik->fields()->length();
2735     }
2736   }
2737 
2738   static void do_method(Method* m) {
2739     nmethods++;
2740     method_size += m->size();
2741     // class loader uses same objArray for empty vectors, so don't count these
2742     if (m->has_stackmap_table()) {
2743       method_size += m->stackmap_data()->size();
2744     }
2745 
2746     MethodData* mdo = m->method_data();
2747     if (mdo != NULL) {
2748       nmethoddata++;
2749       methoddata_size += mdo->size();
2750     }
2751   }
2752 
2753  public:
2754   static void print() {
2755     SystemDictionary::classes_do(do_class);
2756     SystemDictionary::methods_do(do_method);
2757     tty->print_cr("Class statistics:");
2758     tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
2759     tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
2760                   (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
2761     tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
2762   }
2763 };
2764 
2765 
2766 int ClassStatistics::nclasses        = 0;
2767 int ClassStatistics::nmethods        = 0;
2768 int ClassStatistics::nmethoddata     = 0;
2769 int ClassStatistics::class_size      = 0;
2770 int ClassStatistics::method_size     = 0;
2771 int ClassStatistics::debug_size      = 0;
2772 int ClassStatistics::methoddata_size = 0;
2773 
2774 void SystemDictionary::print_class_statistics() {
2775   ResourceMark rm;
2776   ClassStatistics::print();
2777 }
2778 
2779 
2780 class MethodStatistics: AllStatic {
2781  public:
2782   enum {
2783     max_parameter_size = 10
2784   };
2785  private:
2786 
2787   static int _number_of_methods;
2788   static int _number_of_final_methods;
2789   static int _number_of_static_methods;
2790   static int _number_of_native_methods;
2791   static int _number_of_synchronized_methods;
2792   static int _number_of_profiled_methods;
2793   static int _number_of_bytecodes;
2794   static int _parameter_size_profile[max_parameter_size];
2795   static int _bytecodes_profile[Bytecodes::number_of_java_codes];
2796 
2797   static void initialize() {
2798     _number_of_methods        = 0;
2799     _number_of_final_methods  = 0;
2800     _number_of_static_methods = 0;
2801     _number_of_native_methods = 0;
2802     _number_of_synchronized_methods = 0;
2803     _number_of_profiled_methods = 0;
2804     _number_of_bytecodes      = 0;
2805     for (int i = 0; i < max_parameter_size             ; i++) _parameter_size_profile[i] = 0;
2806     for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile     [j] = 0;
2807   };
2808 
2809   static void do_method(Method* m) {
2810     _number_of_methods++;
2811     // collect flag info
2812     if (m->is_final()       ) _number_of_final_methods++;
2813     if (m->is_static()      ) _number_of_static_methods++;
2814     if (m->is_native()      ) _number_of_native_methods++;
2815     if (m->is_synchronized()) _number_of_synchronized_methods++;
2816     if (m->method_data() != NULL) _number_of_profiled_methods++;
2817     // collect parameter size info (add one for receiver, if any)
2818     _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
2819     // collect bytecodes info
2820     {
2821       Thread *thread = Thread::current();
2822       HandleMark hm(thread);
2823       BytecodeStream s(methodHandle(thread, m));
2824       Bytecodes::Code c;
2825       while ((c = s.next()) >= 0) {
2826         _number_of_bytecodes++;
2827         _bytecodes_profile[c]++;
2828       }
2829     }
2830   }
2831 
2832  public:
2833   static void print() {
2834     initialize();
2835     SystemDictionary::methods_do(do_method);
2836     // generate output
2837     tty->cr();
2838     tty->print_cr("Method statistics (static):");
2839     // flag distribution
2840     tty->cr();
2841     tty->print_cr("%6d final        methods  %6.1f%%", _number_of_final_methods       , _number_of_final_methods        * 100.0F / _number_of_methods);
2842     tty->print_cr("%6d static       methods  %6.1f%%", _number_of_static_methods      , _number_of_static_methods       * 100.0F / _number_of_methods);
2843     tty->print_cr("%6d native       methods  %6.1f%%", _number_of_native_methods      , _number_of_native_methods       * 100.0F / _number_of_methods);
2844     tty->print_cr("%6d synchronized methods  %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
2845     tty->print_cr("%6d profiled     methods  %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
2846     // parameter size profile
2847     tty->cr();
2848     { int tot = 0;
2849       int avg = 0;
2850       for (int i = 0; i < max_parameter_size; i++) {
2851         int n = _parameter_size_profile[i];
2852         tot += n;
2853         avg += n*i;
2854         tty->print_cr("parameter size = %1d: %6d methods  %5.1f%%", i, n, n * 100.0F / _number_of_methods);
2855       }
2856       assert(tot == _number_of_methods, "should be the same");
2857       tty->print_cr("                    %6d methods  100.0%%", _number_of_methods);
2858       tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
2859     }
2860     // bytecodes profile
2861     tty->cr();
2862     { int tot = 0;
2863       for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
2864         if (Bytecodes::is_defined(i)) {
2865           Bytecodes::Code c = Bytecodes::cast(i);
2866           int n = _bytecodes_profile[c];
2867           tot += n;
2868           tty->print_cr("%9d  %7.3f%%  %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
2869         }
2870       }
2871       assert(tot == _number_of_bytecodes, "should be the same");
2872       tty->print_cr("%9d  100.000%%", _number_of_bytecodes);
2873     }
2874     tty->cr();
2875   }
2876 };
2877 
2878 int MethodStatistics::_number_of_methods;
2879 int MethodStatistics::_number_of_final_methods;
2880 int MethodStatistics::_number_of_static_methods;
2881 int MethodStatistics::_number_of_native_methods;
2882 int MethodStatistics::_number_of_synchronized_methods;
2883 int MethodStatistics::_number_of_profiled_methods;
2884 int MethodStatistics::_number_of_bytecodes;
2885 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
2886 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
2887 
2888 
2889 void SystemDictionary::print_method_statistics() {
2890   MethodStatistics::print();
2891 }
2892 
2893 #endif // PRODUCT
--- EOF ---