Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 1997-2008 Sun Microsystems, Inc.  All Rights Reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

  * have any questions.

  *

  */

 # include "incls/_precompiled.incl"

 # include "incls/_systemDictionary.cpp.incl"

 Dictionary*       SystemDictionary::_dictionary = NULL;

 PlaceholderTable* SystemDictionary::_placeholders = NULL;

 Dictionary*       SystemDictionary::_shared_dictionary = NULL;

 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;

 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;

 int         SystemDictionary::_number_of_modifications = 0;

 oop         SystemDictionary::_system_loader_lock_obj     =  NULL;

 klassOop    SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]

                                                           =  { NULL /*, NULL...*/ };

 klassOop    SystemDictionary::_box_klasses[T_VOID+1]      =  { NULL /*, NULL...*/ };

 oop         SystemDictionary::_java_system_loader         =  NULL;

 bool        SystemDictionary::_has_loadClassInternal      =  false;

 bool        SystemDictionary::_has_checkPackageAccess     =  false;

 // lazily initialized klass variables

 volatile klassOop    SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;

 // ----------------------------------------------------------------------------

 // Java-level SystemLoader

 oop SystemDictionary::java_system_loader() {

   return _java_system_loader;

 }

 void SystemDictionary::compute_java_system_loader(TRAPS) {

   KlassHandle system_klass(THREAD, WK_KLASS(classloader_klass));

   JavaValue result(T_OBJECT);

   JavaCalls::call_static(&result,

                          KlassHandle(THREAD, WK_KLASS(classloader_klass)),

                          vmSymbolHandles::getSystemClassLoader_name(),

                          vmSymbolHandles::void_classloader_signature(),

                          CHECK);

   _java_system_loader = (oop)result.get_jobject();

 }

 // ----------------------------------------------------------------------------

 // debugging

 #ifdef ASSERT

 // return true if class_name contains no '.' (internal format is '/')

 bool SystemDictionary::is_internal_format(symbolHandle class_name) {

   if (class_name.not_null()) {

     ResourceMark rm;

     char* name = class_name->as_C_string();

     return strchr(name, '.') == NULL;

   } else {

     return true;

   }

 }

 #endif

 // ----------------------------------------------------------------------------

 // Resolving of classes

 // Forwards to resolve_or_null

 klassOop SystemDictionary::resolve_or_fail(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {

   klassOop klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);

   if (HAS_PENDING_EXCEPTION || klass == NULL) {

     KlassHandle k_h(THREAD, klass);

     // can return a null klass

     klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);

   }

   return klass;

 }

 klassOop SystemDictionary::handle_resolution_exception(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {

   if (HAS_PENDING_EXCEPTION) {

     // If we have a pending exception we forward it to the caller, unless throw_error is true,

     // in which case we have to check whether the pending exception is a ClassNotFoundException,

     // and if so convert it to a NoClassDefFoundError

     // And chain the original ClassNotFoundException

     if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::classNotFoundException_klass())) {

       ResourceMark rm(THREAD);

       assert(klass_h() == NULL, "Should not have result with exception pending");

       Handle e(THREAD, PENDING_EXCEPTION);

       CLEAR_PENDING_EXCEPTION;

       THROW_MSG_CAUSE_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);

     } else {

       return NULL;

     }

   }

   // Class not found, throw appropriate error or exception depending on value of throw_error

   if (klass_h() == NULL) {

     ResourceMark rm(THREAD);

     if (throw_error) {

       THROW_MSG_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());

     } else {

       THROW_MSG_0(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());

     }

   }

   return (klassOop)klass_h();

 }

 klassOop SystemDictionary::resolve_or_fail(symbolHandle class_name,

                                            bool throw_error, TRAPS)

 {

   return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);

 }

 // Forwards to resolve_instance_class_or_null

 klassOop SystemDictionary::resolve_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS) {

   assert(!THREAD->is_Compiler_thread(), "Can not load classes with the Compiler thread");

   if (FieldType::is_array(class_name())) {

     return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);

   } else {

     return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);

   }

 }

 klassOop SystemDictionary::resolve_or_null(symbolHandle class_name, TRAPS) {

   return resolve_or_null(class_name, Handle(), Handle(), THREAD);

 }

 // Forwards to resolve_instance_class_or_null

 klassOop SystemDictionary::resolve_array_class_or_null(symbolHandle class_name,

                                                        Handle class_loader,

                                                        Handle protection_domain,

                                                        TRAPS) {

   assert(FieldType::is_array(class_name()), "must be array");

   jint dimension;

   symbolOop object_key;

   klassOop k = NULL;

   // dimension and object_key are assigned as a side-effect of this call

   BasicType t = FieldType::get_array_info(class_name(),

                                           &dimension,

                                           &object_key,

                                           CHECK_NULL);

   if (t == T_OBJECT) {

     symbolHandle h_key(THREAD, object_key);

     // naked oop "k" is OK here -- we assign back into it

     k = SystemDictionary::resolve_instance_class_or_null(h_key,

                                                          class_loader,

                                                          protection_domain,

                                                          CHECK_NULL);

     if (k != NULL) {

       k = Klass::cast(k)->array_klass(dimension, CHECK_NULL);

     }

   } else {

     k = Universe::typeArrayKlassObj(t);

     k = typeArrayKlass::cast(k)->array_klass(dimension, CHECK_NULL);

   }

   return k;

 }

 // Must be called for any super-class or super-interface resolution

 // during class definition to allow class circularity checking

 // super-interface callers:

 //    parse_interfaces - for defineClass & jvmtiRedefineClasses

 // super-class callers:

 //   ClassFileParser - for defineClass & jvmtiRedefineClasses

 //   load_shared_class - while loading a class from shared archive

 //   resolve_instance_class_or_fail:

 //      when resolving a class that has an existing placeholder with

 //      a saved superclass [i.e. a defineClass is currently in progress]

 //      if another thread is trying to resolve the class, it must do

 //      super-class checks on its own thread to catch class circularity

 // This last call is critical in class circularity checking for cases

 // where classloading is delegated to different threads and the

 // classloader lock is released.

 // Take the case: Base->Super->Base

 //   1. If thread T1 tries to do a defineClass of class Base

 //    resolve_super_or_fail creates placeholder: T1, Base (super Super)

 //   2. resolve_instance_class_or_null does not find SD or placeholder for Super

 //    so it tries to load Super

 //   3. If we load the class internally, or user classloader uses same thread

 //      loadClassFromxxx or defineClass via parseClassFile Super ...

 //      3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)

 //      3.3 resolve_instance_class_or_null Base, finds placeholder for Base

 //      3.4 calls resolve_super_or_fail Base

 //      3.5 finds T1,Base -> throws class circularity

 //OR 4. If T2 tries to resolve Super via defineClass Super ...

 //      4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)

 //      4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)

 //      4.3 calls resolve_super_or_fail Super in parallel on own thread T2

 //      4.4 finds T2, Super -> throws class circularity

 // Must be called, even if superclass is null, since this is

 // where the placeholder entry is created which claims this

 // thread is loading this class/classloader.

 klassOop SystemDictionary::resolve_super_or_fail(symbolHandle child_name,

                                                  symbolHandle class_name,

                                                  Handle class_loader,

                                                  Handle protection_domain,

                                                  bool is_superclass,

                                                  TRAPS) {

   // Try to get one of the well-known klasses.

   // They are trusted, and do not participate in circularities.

   if (LinkWellKnownClasses) {

     klassOop k = find_well_known_klass(class_name());

     if (k != NULL) {

       return k;

     }

   }

   // Double-check, if child class is already loaded, just return super-class,interface

   // Don't add a placedholder if already loaded, i.e. already in system dictionary

   // Make sure there's a placeholder for the *child* before resolving.

   // Used as a claim that this thread is currently loading superclass/classloader

   // Used here for ClassCircularity checks and also for heap verification

   // (every instanceKlass in the heap needs to be in the system dictionary

   // or have a placeholder).

   // Must check ClassCircularity before checking if super class is already loaded

   //

   // We might not already have a placeholder if this child_name was

   // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);

   // the name of the class might not be known until the stream is actually

   // parsed.

   // Bugs 4643874, 4715493

   // compute_hash can have a safepoint

   unsigned int d_hash = dictionary()->compute_hash(child_name, class_loader);

   int d_index = dictionary()->hash_to_index(d_hash);

   unsigned int p_hash = placeholders()->compute_hash(child_name, class_loader);

   int p_index = placeholders()->hash_to_index(p_hash);

   // can't throw error holding a lock

   bool child_already_loaded = false;

   bool throw_circularity_error = false;

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     klassOop childk = find_class(d_index, d_hash, child_name, class_loader);

     klassOop quicksuperk;

     // to support // loading: if child done loading, just return superclass

     // if class_name, & class_loader don't match:

     // if initial define, SD update will give LinkageError

     // if redefine: compare_class_versions will give HIERARCHY_CHANGED

     // so we don't throw an exception here.

     // see: nsk redefclass014 & java.lang.instrument Instrument032

     if ((childk != NULL ) && (is_superclass) &&

        ((quicksuperk = instanceKlass::cast(childk)->super()) != NULL) &&

          ((Klass::cast(quicksuperk)->name() == class_name()) &&

             (Klass::cast(quicksuperk)->class_loader()  == class_loader()))) {

            return quicksuperk;

     } else {

       PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, class_loader);

       if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {

           throw_circularity_error = true;

       }

       // add placeholder entry even if error - callers will remove on error

       PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, class_loader, PlaceholderTable::LOAD_SUPER, class_name, THREAD);

       if (throw_circularity_error) {

          newprobe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER);

       }

     }

   }

   if (throw_circularity_error) {

       ResourceMark rm(THREAD);

       THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());

   }

 // java.lang.Object should have been found above

   assert(class_name() != NULL, "null super class for resolving");

   // Resolve the super class or interface, check results on return

   klassOop superk = NULL;

   superk = SystemDictionary::resolve_or_null(class_name,

                                                  class_loader,

                                                  protection_domain,

                                                  THREAD);

   KlassHandle superk_h(THREAD, superk);

   // Note: clean up of placeholders currently in callers of

   // resolve_super_or_fail - either at update_dictionary time

   // or on error

   {

   MutexLocker mu(SystemDictionary_lock, THREAD);

    PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, class_loader);

    if (probe != NULL) {

       probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER);

    }

   }

   if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {

     // can null superk

     superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));

   }

   return superk_h();

 }

 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,

                                                   Handle class_loader,

                                                   Handle protection_domain,

                                                   TRAPS) {

   if(!has_checkPackageAccess()) return;

   // Now we have to call back to java to check if the initating class has access

   JavaValue result(T_VOID);

   if (TraceProtectionDomainVerification) {

     // Print out trace information

     tty->print_cr("Checking package access");

     tty->print(" - class loader:      "); class_loader()->print_value_on(tty);      tty->cr();

     tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();

     tty->print(" - loading:           "); klass()->print_value_on(tty);             tty->cr();

   }

   assert(class_loader() != NULL, "should not have non-null protection domain for null classloader");

   KlassHandle system_loader(THREAD, SystemDictionary::classloader_klass());

   JavaCalls::call_special(&result,

                          class_loader,

                          system_loader,

                          vmSymbolHandles::checkPackageAccess_name(),

                          vmSymbolHandles::class_protectiondomain_signature(),

                          Handle(THREAD, klass->java_mirror()),

                          protection_domain,

                          THREAD);

   if (TraceProtectionDomainVerification) {

     if (HAS_PENDING_EXCEPTION) {

       tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");

     } else {

      tty->print_cr(" -> granted");

     }

     tty->cr();

   }

   if (HAS_PENDING_EXCEPTION) return;

   // If no exception has been thrown, we have validated the protection domain

   // Insert the protection domain of the initiating class into the set.

   {

     // We recalculate the entry here -- we've called out to java since

     // the last time it was calculated.

     symbolHandle kn(THREAD, klass->name());

     unsigned int d_hash = dictionary()->compute_hash(kn, class_loader);

     int d_index = dictionary()->hash_to_index(d_hash);

     MutexLocker mu(SystemDictionary_lock, THREAD);

     {

       // Note that we have an entry, and entries can be deleted only during GC,

       // so we cannot allow GC to occur while we're holding this entry.

       // We're using a No_Safepoint_Verifier to catch any place where we

       // might potentially do a GC at all.

       // SystemDictionary::do_unloading() asserts that classes are only

       // unloaded at a safepoint.

       No_Safepoint_Verifier nosafepoint;

       dictionary()->add_protection_domain(d_index, d_hash, klass, class_loader,

                                           protection_domain, THREAD);

     }

   }

 }

 // We only get here if this thread finds that another thread

 // has already claimed the placeholder token for the current operation,

 // but that other thread either never owned or gave up the

 // object lock

 // Waits on SystemDictionary_lock to indicate placeholder table updated

 // On return, caller must recheck placeholder table state

 //

 // We only get here if

 //  1) custom classLoader, i.e. not bootstrap classloader

 //  2) UnsyncloadClass not set

 //  3) custom classLoader has broken the class loader objectLock

 //     so another thread got here in parallel

 //

 // lockObject must be held.

 // Complicated dance due to lock ordering:

 // Must first release the classloader object lock to

 // allow initial definer to complete the class definition

 // and to avoid deadlock

 // Reclaim classloader lock object with same original recursion count

 // Must release SystemDictionary_lock after notify, since

 // class loader lock must be claimed before SystemDictionary_lock

 // to prevent deadlocks

 //

 // The notify allows applications that did an untimed wait() on

 // the classloader object lock to not hang.

 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {

   assert_lock_strong(SystemDictionary_lock);

   bool calledholdinglock

       = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);

   assert(calledholdinglock,"must hold lock for notify");

   assert(!UnsyncloadClass, "unexpected double_lock_wait");

   ObjectSynchronizer::notifyall(lockObject, THREAD);

   intptr_t recursions =  ObjectSynchronizer::complete_exit(lockObject, THREAD);

   SystemDictionary_lock->wait();

   SystemDictionary_lock->unlock();

   ObjectSynchronizer::reenter(lockObject, recursions, THREAD);

   SystemDictionary_lock->lock();

 }

 // If the class in is in the placeholder table, class loading is in progress

 // For cases where the application changes threads to load classes, it

 // is critical to ClassCircularity detection that we try loading

 // the superclass on the same thread internally, so we do parallel

 // super class loading here.

 // This also is critical in cases where the original thread gets stalled

 // even in non-circularity situations.

 // Note: only one thread can define the class, but multiple can resolve

 // Note: must call resolve_super_or_fail even if null super -

 // to force placeholder entry creation for this class

 // Caller must check for pending exception

 // Returns non-null klassOop if other thread has completed load

 // and we are done,

 // If return null klassOop and no pending exception, the caller must load the class

 instanceKlassHandle SystemDictionary::handle_parallel_super_load(

     symbolHandle name, symbolHandle superclassname, Handle class_loader,

     Handle protection_domain, Handle lockObject, TRAPS) {

   instanceKlassHandle nh = instanceKlassHandle(); // null Handle

   unsigned int d_hash = dictionary()->compute_hash(name, class_loader);

   int d_index = dictionary()->hash_to_index(d_hash);

   unsigned int p_hash = placeholders()->compute_hash(name, class_loader);

   int p_index = placeholders()->hash_to_index(p_hash);

   // superk is not used, resolve_super called for circularity check only

   // This code is reached in two situations. One if this thread

   // is loading the same class twice (e.g. ClassCircularity, or

   // java.lang.instrument).

   // The second is if another thread started the resolve_super first

   // and has not yet finished.

   // In both cases the original caller will clean up the placeholder

   // entry on error.

   klassOop superk = SystemDictionary::resolve_super_or_fail(name,

                                                           superclassname,

                                                           class_loader,

                                                           protection_domain,

                                                           true,

                                                           CHECK_(nh));

   // We don't redefine the class, so we just need to clean up if there

   // was not an error (don't want to modify any system dictionary

   // data structures).

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);

     SystemDictionary_lock->notify_all();

   }

   // UnsyncloadClass does NOT wait for parallel superclass loads to complete

   // Bootstrap classloader does wait for parallel superclass loads

  if (UnsyncloadClass) {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     // Check if classloading completed while we were loading superclass or waiting

     klassOop check = find_class(d_index, d_hash, name, class_loader);

     if (check != NULL) {

       // Klass is already loaded, so just return it

       return(instanceKlassHandle(THREAD, check));

     } else {

       return nh;

     }

   }

   // must loop to both handle other placeholder updates

   // and spurious notifications

   bool super_load_in_progress = true;

   PlaceholderEntry* placeholder;

   while (super_load_in_progress) {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     // Check if classloading completed while we were loading superclass or waiting

     klassOop check = find_class(d_index, d_hash, name, class_loader);

     if (check != NULL) {

       // Klass is already loaded, so just return it

       return(instanceKlassHandle(THREAD, check));

     } else {

       placeholder = placeholders()->get_entry(p_index, p_hash, name, class_loader);

       if (placeholder && placeholder->super_load_in_progress() ){

         // Before UnsyncloadClass:

         // We only get here if the application has released the

         // classloader lock when another thread was in the middle of loading a

         // superclass/superinterface for this class, and now

         // this thread is also trying to load this class.

         // To minimize surprises, the first thread that started to

         // load a class should be the one to complete the loading

         // with the classfile it initially expected.

         // This logic has the current thread wait once it has done

         // all the superclass/superinterface loading it can, until

         // the original thread completes the class loading or fails

         // If it completes we will use the resulting instanceKlass

         // which we will find below in the systemDictionary.

         // We also get here for parallel bootstrap classloader

         if (class_loader.is_null()) {

           SystemDictionary_lock->wait();

         } else {

           double_lock_wait(lockObject, THREAD);

         }

       } else {

         // If not in SD and not in PH, other thread's load must have failed

         super_load_in_progress = false;

       }

     }

   }

   return (nh);

 }

 klassOop SystemDictionary::resolve_instance_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS) {

   assert(class_name.not_null() && !FieldType::is_array(class_name()), "invalid class name");

   // First check to see if we should remove wrapping L and ;

   symbolHandle name;

   if (FieldType::is_obj(class_name())) {

     ResourceMark rm(THREAD);

     // Ignore wrapping L and ;.

     name = oopFactory::new_symbol_handle(class_name()->as_C_string() + 1, class_name()->utf8_length() - 2, CHECK_NULL);

   } else {

     name = class_name;

   }

   // UseNewReflection

   // Fix for 4474172; see evaluation for more details

   class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));

   // Do lookup to see if class already exist and the protection domain

   // has the right access

   unsigned int d_hash = dictionary()->compute_hash(name, class_loader);

   int d_index = dictionary()->hash_to_index(d_hash);

   klassOop probe = dictionary()->find(d_index, d_hash, name, class_loader,

                                       protection_domain, THREAD);

   if (probe != NULL) return probe;

   // Non-bootstrap class loaders will call out to class loader and

   // define via jvm/jni_DefineClass which will acquire the

   // class loader object lock to protect against multiple threads

   // defining the class in parallel by accident.

   // This lock must be acquired here so the waiter will find

   // any successful result in the SystemDictionary and not attempt

   // the define

   // Classloaders that support parallelism, e.g. bootstrap classloader,

   // or all classloaders with UnsyncloadClass do not acquire lock here

   bool DoObjectLock = true;

   if (UnsyncloadClass || (class_loader.is_null())) {

     DoObjectLock = false;

   }

   unsigned int p_hash = placeholders()->compute_hash(name, class_loader);

   int p_index = placeholders()->hash_to_index(p_hash);

   // Class is not in SystemDictionary so we have to do loading.

   // Make sure we are synchronized on the class loader before we proceed

   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);

   check_loader_lock_contention(lockObject, THREAD);

   ObjectLocker ol(lockObject, THREAD, DoObjectLock);

   // Check again (after locking) if class already exist in SystemDictionary

   bool class_has_been_loaded   = false;

   bool super_load_in_progress  = false;

   bool havesupername = false;

   instanceKlassHandle k;

   PlaceholderEntry* placeholder;

   symbolHandle superclassname;

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     klassOop check = find_class(d_index, d_hash, name, class_loader);

     if (check != NULL) {

       // Klass is already loaded, so just return it

       class_has_been_loaded = true;

       k = instanceKlassHandle(THREAD, check);

     } else {

       placeholder = placeholders()->get_entry(p_index, p_hash, name, class_loader);

       if (placeholder && placeholder->super_load_in_progress()) {

          super_load_in_progress = true;

          if (placeholder->havesupername() == true) {

            superclassname = symbolHandle(THREAD, placeholder->supername());

            havesupername = true;

          }

       }

     }

   }

   // If the class in is in the placeholder table, class loading is in progress

   if (super_load_in_progress && havesupername==true) {

     k = SystemDictionary::handle_parallel_super_load(name, superclassname,

         class_loader, protection_domain, lockObject, THREAD);

     if (HAS_PENDING_EXCEPTION) {

       return NULL;

     }

     if (!k.is_null()) {

       class_has_been_loaded = true;

     }

   }

   if (!class_has_been_loaded) {

     // add placeholder entry to record loading instance class

     // Five cases:

     // All cases need to prevent modifying bootclasssearchpath

     // in parallel with a classload of same classname

     // case 1. traditional classloaders that rely on the classloader object lock

     //   - no other need for LOAD_INSTANCE

     // case 2. traditional classloaders that break the classloader object lock

     //    as a deadlock workaround. Detection of this case requires that

     //    this check is done while holding the classloader object lock,

     //    and that lock is still held when calling classloader's loadClass.

     //    For these classloaders, we ensure that the first requestor

     //    completes the load and other requestors wait for completion.

     // case 3. UnsyncloadClass - don't use objectLocker

     //    With this flag, we allow parallel classloading of a

     //    class/classloader pair

     // case4. Bootstrap classloader - don't own objectLocker

     //    This classloader supports parallelism at the classloader level,

     //    but only allows a single load of a class/classloader pair.

     //    No performance benefit and no deadlock issues.

     // case 5. Future: parallel user level classloaders - without objectLocker

     symbolHandle nullsymbolHandle;

     bool throw_circularity_error = false;

     {

       MutexLocker mu(SystemDictionary_lock, THREAD);

       if (!UnsyncloadClass) {

         PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, class_loader);

         if (oldprobe) {

           // only need check_seen_thread once, not on each loop

           // 6341374 java/lang/Instrument with -Xcomp

           if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {

             throw_circularity_error = true;

           } else {

             // case 1: traditional: should never see load_in_progress.

             while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {

               // case 4: bootstrap classloader: prevent futile classloading,

               // wait on first requestor

               if (class_loader.is_null()) {

                 SystemDictionary_lock->wait();

               } else {

               // case 2: traditional with broken classloader lock. wait on first

               // requestor.

                 double_lock_wait(lockObject, THREAD);

               }

               // Check if classloading completed while we were waiting

               klassOop check = find_class(d_index, d_hash, name, class_loader);

               if (check != NULL) {

                 // Klass is already loaded, so just return it

                 k = instanceKlassHandle(THREAD, check);

                 class_has_been_loaded = true;

               }

               // check if other thread failed to load and cleaned up

               oldprobe = placeholders()->get_entry(p_index, p_hash, name, class_loader);

             }

           }

         }

       }

       // All cases: add LOAD_INSTANCE

       // case 3: UnsyncloadClass: allow competing threads to try

       // LOAD_INSTANCE in parallel

       // add placeholder entry even if error - callers will remove on error

       if (!class_has_been_loaded) {

         PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, class_loader, PlaceholderTable::LOAD_INSTANCE, nullsymbolHandle, THREAD);

         if (throw_circularity_error) {

           newprobe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);

         }

         // For class loaders that do not acquire the classloader object lock,

         // if they did not catch another thread holding LOAD_INSTANCE,

         // need a check analogous to the acquire ObjectLocker/find_class

         // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL

         // one final check if the load has already completed

         klassOop check = find_class(d_index, d_hash, name, class_loader);

         if (check != NULL) {

         // Klass is already loaded, so just return it

           k = instanceKlassHandle(THREAD, check);

           class_has_been_loaded = true;

           newprobe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);

         }

       }

     }

     // must throw error outside of owning lock

     if (throw_circularity_error) {

       ResourceMark rm(THREAD);

       THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());

     }

     if (!class_has_been_loaded) {

       // Do actual loading

       k = load_instance_class(name, class_loader, THREAD);

       // In custom class loaders, the usual findClass calls

       // findLoadedClass, which directly searches  the SystemDictionary, then

       // defineClass. If these are not atomic with respect to other threads,

       // the findLoadedClass can fail, but the defineClass can get a

       // LinkageError:: duplicate class definition.

       // If they got a linkageError, check if a parallel class load succeeded.

       // If it did, then for bytecode resolution the specification requires

       // that we return the same result we did for the other thread, i.e. the

       // successfully loaded instanceKlass

       // Note: Class can not be unloaded as long as any classloader refs exist

       // Should not get here for classloaders that support parallelism

       // with the new cleaner mechanism, e.g. bootstrap classloader

       if (UnsyncloadClass || (class_loader.is_null())) {

         if (k.is_null() && HAS_PENDING_EXCEPTION

           && PENDING_EXCEPTION->is_a(SystemDictionary::linkageError_klass())) {

           MutexLocker mu(SystemDictionary_lock, THREAD);

           klassOop check = find_class(d_index, d_hash, name, class_loader);

           if (check != NULL) {

             // Klass is already loaded, so just use it

             k = instanceKlassHandle(THREAD, check);

             CLEAR_PENDING_EXCEPTION;

             guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");

           }

         }

       }

       // clean up placeholder entries for success or error

       // This cleans up LOAD_INSTANCE entries

       // It also cleans up LOAD_SUPER entries on errors from

       // calling load_instance_class

       {

         MutexLocker mu(SystemDictionary_lock, THREAD);

         PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name, class_loader);

         if (probe != NULL) {

           probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);

           placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);

           SystemDictionary_lock->notify_all();

         }

       }

       // If everything was OK (no exceptions, no null return value), and

       // class_loader is NOT the defining loader, do a little more bookkeeping.

       if (!HAS_PENDING_EXCEPTION && !k.is_null() &&

         k->class_loader() != class_loader()) {

         check_constraints(d_index, d_hash, k, class_loader, false, THREAD);

         // Need to check for a PENDING_EXCEPTION again; check_constraints

         // can throw and doesn't use the CHECK macro.

         if (!HAS_PENDING_EXCEPTION) {

           { // Grabbing the Compile_lock prevents systemDictionary updates

             // during compilations.

             MutexLocker mu(Compile_lock, THREAD);

             update_dictionary(d_index, d_hash, p_index, p_hash,

                             k, class_loader, THREAD);

           }

           if (JvmtiExport::should_post_class_load()) {

             Thread *thread = THREAD;

             assert(thread->is_Java_thread(), "thread->is_Java_thread()");

             JvmtiExport::post_class_load((JavaThread *) thread, k());

           }

         }

       }

       if (HAS_PENDING_EXCEPTION || k.is_null()) {

         // On error, clean up placeholders

         {

           MutexLocker mu(SystemDictionary_lock, THREAD);

           placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);

           SystemDictionary_lock->notify_all();

         }

         return NULL;

       }

     }

   }

 #ifdef ASSERT

   {

     Handle loader (THREAD, k->class_loader());

     MutexLocker mu(SystemDictionary_lock, THREAD);

     oop kk = find_class_or_placeholder(name, loader);

     assert(kk == k(), "should be present in dictionary");

   }

 #endif

   // return if the protection domain in NULL

   if (protection_domain() == NULL) return k();

   // Check the protection domain has the right access

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     // Note that we have an entry, and entries can be deleted only during GC,

     // so we cannot allow GC to occur while we're holding this entry.

     // We're using a No_Safepoint_Verifier to catch any place where we

     // might potentially do a GC at all.

     // SystemDictionary::do_unloading() asserts that classes are only

     // unloaded at a safepoint.

     No_Safepoint_Verifier nosafepoint;

     if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,

                                                  class_loader,

                                                  protection_domain)) {

       return k();

     }

   }

   // Verify protection domain. If it fails an exception is thrown

   validate_protection_domain(k, class_loader, protection_domain, CHECK_(klassOop(NULL)));

   return k();

 }

 // This routine does not lock the system dictionary.

 //

 // Since readers don't hold a lock, we must make sure that system

 // dictionary entries are only removed at a safepoint (when only one

 // thread is running), and are added to in a safe way (all links must

 // be updated in an MT-safe manner).

 //

 // Callers should be aware that an entry could be added just after

 // _dictionary->bucket(index) is read here, so the caller will not see

 // the new entry.

 klassOop SystemDictionary::find(symbolHandle class_name,

                                 Handle class_loader,

                                 Handle protection_domain,

                                 TRAPS) {

   unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);

   int d_index = dictionary()->hash_to_index(d_hash);

   {

     // Note that we have an entry, and entries can be deleted only during GC,

     // so we cannot allow GC to occur while we're holding this entry.

     // We're using a No_Safepoint_Verifier to catch any place where we

     // might potentially do a GC at all.

     // SystemDictionary::do_unloading() asserts that classes are only

     // unloaded at a safepoint.

     No_Safepoint_Verifier nosafepoint;

     return dictionary()->find(d_index, d_hash, class_name, class_loader,

                               protection_domain, THREAD);

   }

 }

 // Look for a loaded instance or array klass by name.  Do not do any loading.

 // return NULL in case of error.

 klassOop SystemDictionary::find_instance_or_array_klass(symbolHandle class_name,

                                                         Handle class_loader,

                                                         Handle protection_domain,

                                                         TRAPS) {

   klassOop k = NULL;

   assert(class_name() != NULL, "class name must be non NULL");

   // Try to get one of the well-known klasses.

   if (LinkWellKnownClasses) {

     k = find_well_known_klass(class_name());

     if (k != NULL) {

       return k;

     }

   }

   if (FieldType::is_array(class_name())) {

     // The name refers to an array.  Parse the name.

     jint dimension;

     symbolOop object_key;

     // dimension and object_key are assigned as a side-effect of this call

     BasicType t = FieldType::get_array_info(class_name(), &dimension,

                                             &object_key, CHECK_(NULL));

     if (t != T_OBJECT) {

       k = Universe::typeArrayKlassObj(t);

     } else {

       symbolHandle h_key(THREAD, object_key);

       k = SystemDictionary::find(h_key, class_loader, protection_domain, THREAD);

     }

     if (k != NULL) {

       k = Klass::cast(k)->array_klass_or_null(dimension);

     }

   } else {

     k = find(class_name, class_loader, protection_domain, THREAD);

   }

   return k;

 }

 // Quick range check for names of well-known classes:

 static symbolOop wk_klass_name_limits[2] = {NULL, NULL};

 #ifndef PRODUCT

 static int find_wkk_calls, find_wkk_probes, find_wkk_wins;

 // counts for "hello world": 3983, 1616, 1075

 //  => 60% hit after limit guard, 25% total win rate

 #endif

 klassOop SystemDictionary::find_well_known_klass(symbolOop class_name) {

   // A bounds-check on class_name will quickly get a negative result.

   NOT_PRODUCT(find_wkk_calls++);

   if (class_name >= wk_klass_name_limits[0] &&

       class_name <= wk_klass_name_limits[1]) {

     NOT_PRODUCT(find_wkk_probes++);

     vmSymbols::SID sid = vmSymbols::find_sid(class_name);

     if (sid != vmSymbols::NO_SID) {

       klassOop k = NULL;

       switch (sid) {

         #define WK_KLASS_CASE(name, symbol, ignore_option) \

         case vmSymbols::VM_SYMBOL_ENUM_NAME(symbol): \

           k = WK_KLASS(name); break;

         WK_KLASSES_DO(WK_KLASS_CASE)

         #undef WK_KLASS_CASE

       }

       NOT_PRODUCT(if (k != NULL)  find_wkk_wins++);

       return k;

     }

   }

   return NULL;

 }

 // Note: this method is much like resolve_from_stream, but

 // updates no supplemental data structures.

 // TODO consolidate the two methods with a helper routine?

 klassOop SystemDictionary::parse_stream(symbolHandle class_name,

                                         Handle class_loader,

                                         Handle protection_domain,

                                         ClassFileStream* st,

                                         TRAPS) {

   symbolHandle parsed_name;

   // Parse the stream. Note that we do this even though this klass might

   // already be present in the SystemDictionary, otherwise we would not

   // throw potential ClassFormatErrors.

   //

   // Note: "name" is updated.

   // Further note:  a placeholder will be added for this class when

   //   super classes are loaded (resolve_super_or_fail). We expect this

   //   to be called for all classes but java.lang.Object; and we preload

   //   java.lang.Object through resolve_or_fail, not this path.

   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,

                                                              class_loader,

                                                              protection_domain,

                                                              parsed_name,

                                                              THREAD);

   // We don't redefine the class, so we just need to clean up whether there

   // was an error or not (don't want to modify any system dictionary

   // data structures).

   // Parsed name could be null if we threw an error before we got far

   // enough along to parse it -- in that case, there is nothing to clean up.

   if (!parsed_name.is_null()) {

     unsigned int p_hash = placeholders()->compute_hash(parsed_name,

                                                        class_loader);

     int p_index = placeholders()->hash_to_index(p_hash);

     {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     placeholders()->find_and_remove(p_index, p_hash, parsed_name, class_loader, THREAD);

     SystemDictionary_lock->notify_all();

     }

   }

   return k();

 }

 // Add a klass to the system from a stream (called by jni_DefineClass and

 // JVM_DefineClass).

 // Note: class_name can be NULL. In that case we do not know the name of

 // the class until we have parsed the stream.

 klassOop SystemDictionary::resolve_from_stream(symbolHandle class_name,

                                                Handle class_loader,

                                                Handle protection_domain,

                                                ClassFileStream* st,

                                                TRAPS) {

   // Make sure we are synchronized on the class loader before we initiate

   // loading.

   Handle lockObject = compute_loader_lock_object(class_loader, THREAD);

   check_loader_lock_contention(lockObject, THREAD);

   ObjectLocker ol(lockObject, THREAD);

   symbolHandle parsed_name;

   // Parse the stream. Note that we do this even though this klass might

   // already be present in the SystemDictionary, otherwise we would not

   // throw potential ClassFormatErrors.

   //

   // Note: "name" is updated.

   // Further note:  a placeholder will be added for this class when

   //   super classes are loaded (resolve_super_or_fail). We expect this

   //   to be called for all classes but java.lang.Object; and we preload

   //   java.lang.Object through resolve_or_fail, not this path.

   instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,

                                                              class_loader,

                                                              protection_domain,

                                                              parsed_name,

                                                              THREAD);

   const char* pkg = "java/";

   if (!HAS_PENDING_EXCEPTION &&

       !class_loader.is_null() &&

       !parsed_name.is_null() &&

       !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {

     // It is illegal to define classes in the "java." package from

     // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader

     ResourceMark rm(THREAD);

     char* name = parsed_name->as_C_string();

     char* index = strrchr(name, '/');

     *index = '\0'; // chop to just the package name

     while ((index = strchr(name, '/')) != NULL) {

       *index = '.'; // replace '/' with '.' in package name

     }

     const char* fmt = "Prohibited package name: %s";

     size_t len = strlen(fmt) + strlen(name);

     char* message = NEW_RESOURCE_ARRAY(char, len);

     jio_snprintf(message, len, fmt, name);

     Exceptions::_throw_msg(THREAD_AND_LOCATION,

       vmSymbols::java_lang_SecurityException(), message);

   }

   if (!HAS_PENDING_EXCEPTION) {

     assert(!parsed_name.is_null(), "Sanity");

     assert(class_name.is_null() || class_name() == parsed_name(),

            "name mismatch");

     // Verification prevents us from creating names with dots in them, this

     // asserts that that's the case.

     assert(is_internal_format(parsed_name),

            "external class name format used internally");

     // Add class just loaded

     define_instance_class(k, THREAD);

   }

   // If parsing the class file or define_instance_class failed, we

   // need to remove the placeholder added on our behalf. But we

   // must make sure parsed_name is valid first (it won't be if we had

   // a format error before the class was parsed far enough to

   // find the name).

   if (HAS_PENDING_EXCEPTION && !parsed_name.is_null()) {

     unsigned int p_hash = placeholders()->compute_hash(parsed_name,

                                                        class_loader);

     int p_index = placeholders()->hash_to_index(p_hash);

     {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     placeholders()->find_and_remove(p_index, p_hash, parsed_name, class_loader, THREAD);

     SystemDictionary_lock->notify_all();

     }

     return NULL;

   }

   // Make sure that we didn't leave a place holder in the

   // SystemDictionary; this is only done on success

   debug_only( {

     if (!HAS_PENDING_EXCEPTION) {

       assert(!parsed_name.is_null(), "parsed_name is still null?");

       symbolHandle h_name   (THREAD, k->name());

       Handle h_loader (THREAD, k->class_loader());

       MutexLocker mu(SystemDictionary_lock, THREAD);

       oop check = find_class_or_placeholder(parsed_name, class_loader);

       assert(check == k(), "should be present in the dictionary");

       oop check2 = find_class_or_placeholder(h_name, h_loader);

       assert(check == check2, "name inconsistancy in SystemDictionary");

     }

   } );

   return k();

 }

 void SystemDictionary::set_shared_dictionary(HashtableBucket* t, int length,

                                              int number_of_entries) {

   assert(length == _nof_buckets * sizeof(HashtableBucket),

          "bad shared dictionary size.");

   _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);

 }

 // If there is a shared dictionary, then find the entry for the

 // given shared system class, if any.

 klassOop SystemDictionary::find_shared_class(symbolHandle class_name) {

   if (shared_dictionary() != NULL) {

     unsigned int d_hash = dictionary()->compute_hash(class_name, Handle());

     int d_index = dictionary()->hash_to_index(d_hash);

     return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);

   } else {

     return NULL;

   }

 }

 // Load a class from the shared spaces (found through the shared system

 // dictionary).  Force the superclass and all interfaces to be loaded.

 // Update the class definition to include sibling classes and no

 // subclasses (yet).  [Classes in the shared space are not part of the

 // object hierarchy until loaded.]

 instanceKlassHandle SystemDictionary::load_shared_class(

                  symbolHandle class_name, Handle class_loader, TRAPS) {

   instanceKlassHandle ik (THREAD, find_shared_class(class_name));

   return load_shared_class(ik, class_loader, THREAD);

 }

 // Note well!  Changes to this method may affect oop access order

 // in the shared archive.  Please take care to not make changes that

 // adversely affect cold start time by changing the oop access order

 // that is specified in dump.cpp MarkAndMoveOrderedReadOnly and

 // MarkAndMoveOrderedReadWrite closures.

 instanceKlassHandle SystemDictionary::load_shared_class(

                  instanceKlassHandle ik, Handle class_loader, TRAPS) {

   assert(class_loader.is_null(), "non-null classloader for shared class?");

   if (ik.not_null()) {

     instanceKlassHandle nh = instanceKlassHandle(); // null Handle

     symbolHandle class_name(THREAD, ik->name());

     // Found the class, now load the superclass and interfaces.  If they

     // are shared, add them to the main system dictionary and reset

     // their hierarchy references (supers, subs, and interfaces).

     if (ik->super() != NULL) {

       symbolHandle cn(THREAD, ik->super()->klass_part()->name());

       resolve_super_or_fail(class_name, cn,

                             class_loader, Handle(), true, CHECK_(nh));

     }

     objArrayHandle interfaces (THREAD, ik->local_interfaces());

     int num_interfaces = interfaces->length();

     for (int index = 0; index < num_interfaces; index++) {

       klassOop k = klassOop(interfaces->obj_at(index));

       // Note: can not use instanceKlass::cast here because

       // interfaces' instanceKlass's C++ vtbls haven't been

       // reinitialized yet (they will be once the interface classes

       // are loaded)

       symbolHandle name (THREAD, k->klass_part()->name());

       resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(nh));

     }

     // Adjust methods to recover missing data.  They need addresses for

     // interpreter entry points and their default native method address

     // must be reset.

     // Updating methods must be done under a lock so multiple

     // threads don't update these in parallel

     // Shared classes are all currently loaded by the bootstrap

     // classloader, so this will never cause a deadlock on

     // a custom class loader lock.

     {

       Handle lockObject = compute_loader_lock_object(class_loader, THREAD);

       check_loader_lock_contention(lockObject, THREAD);

       ObjectLocker ol(lockObject, THREAD, true);

       objArrayHandle methods (THREAD, ik->methods());

       int num_methods = methods->length();

       for (int index2 = 0; index2 < num_methods; ++index2) {

         methodHandle m(THREAD, methodOop(methods->obj_at(index2)));

         m()->link_method(m, CHECK_(nh));

       }

     }

     if (TraceClassLoading) {

       ResourceMark rm;

       tty->print("[Loaded %s", ik->external_name());

       tty->print(" from shared objects file");

       tty->print_cr("]");

     }

     // notify a class loaded from shared object

     ClassLoadingService::notify_class_loaded(instanceKlass::cast(ik()),

                                              true /* shared class */);

   }

   return ik;

 }

 #ifdef KERNEL

 // Some classes on the bootstrap class path haven't been installed on the

 // system yet.  Call the DownloadManager method to make them appear in the

 // bootstrap class path and try again to load the named class.

 // Note that with delegation class loaders all classes in another loader will

 // first try to call this so it'd better be fast!!

 static instanceKlassHandle download_and_retry_class_load(

                                                     symbolHandle class_name,

                                                     TRAPS) {

   klassOop dlm = SystemDictionary::sun_jkernel_DownloadManager_klass();

   instanceKlassHandle nk;

   // If download manager class isn't loaded just return.

   if (dlm == NULL) return nk;

   { HandleMark hm(THREAD);

     ResourceMark rm(THREAD);

     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nk));

     Handle class_string = java_lang_String::externalize_classname(s, CHECK_(nk));

     // return value

     JavaValue result(T_OBJECT);

     // Call the DownloadManager.  We assume that it has a lock because

     // multiple classes could be not found and downloaded at the same time.

     // class sun.misc.DownloadManager;

     // public static String getBootClassPathEntryForClass(String className);

     JavaCalls::call_static(&result,

                        KlassHandle(THREAD, dlm),

                        vmSymbolHandles::getBootClassPathEntryForClass_name(),

                        vmSymbolHandles::string_string_signature(),

                        class_string,

                        CHECK_(nk));

     // Get result.string and add to bootclasspath

     assert(result.get_type() == T_OBJECT, "just checking");

     oop obj = (oop) result.get_jobject();

     if (obj == NULL) { return nk; }

     Handle h_obj(THREAD, obj);

     char* new_class_name = java_lang_String::as_platform_dependent_str(h_obj,

                                                                   CHECK_(nk));

     // lock the loader

     // we use this lock because JVMTI does.

     Handle loader_lock(THREAD, SystemDictionary::system_loader_lock());

     ObjectLocker ol(loader_lock, THREAD);

     // add the file to the bootclasspath

     ClassLoader::update_class_path_entry_list(new_class_name, true);

   } // end HandleMark

   if (TraceClassLoading) {

     ClassLoader::print_bootclasspath();

   }

   return ClassLoader::load_classfile(class_name, CHECK_(nk));

 }

 #endif // KERNEL

 instanceKlassHandle SystemDictionary::load_instance_class(symbolHandle class_name, Handle class_loader, TRAPS) {

   instanceKlassHandle nh = instanceKlassHandle(); // null Handle

   if (class_loader.is_null()) {

     // Search the shared system dictionary for classes preloaded into the

     // shared spaces.

     instanceKlassHandle k;

     k = load_shared_class(class_name, class_loader, THREAD);

     if (k.is_null()) {

       // Use VM class loader

       k = ClassLoader::load_classfile(class_name, CHECK_(nh));

     }

 #ifdef KERNEL

     // If the VM class loader has failed to load the class, call the

     // DownloadManager class to make it magically appear on the classpath

     // and try again.  This is only configured with the Kernel VM.

     if (k.is_null()) {

       k = download_and_retry_class_load(class_name, CHECK_(nh));

     }

 #endif // KERNEL

     // find_or_define_instance_class may return a different k

     if (!k.is_null()) {

       k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));

     }

     return k;

   } else {

     // Use user specified class loader to load class. Call loadClass operation on class_loader.

     ResourceMark rm(THREAD);

     Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));

     // Translate to external class name format, i.e., convert '/' chars to '.'

     Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));

     JavaValue result(T_OBJECT);

     KlassHandle spec_klass (THREAD, SystemDictionary::classloader_klass());

     // UnsyncloadClass option means don't synchronize loadClass() calls.

     // loadClassInternal() is synchronized and public loadClass(String) is not.

     // This flag is for diagnostic purposes only. It is risky to call

     // custom class loaders without synchronization.

     // WARNING If a custom class loader does NOT synchronizer findClass, or callers of

     // findClass, this flag risks unexpected timing bugs in the field.

     // Do NOT assume this will be supported in future releases.

     if (!UnsyncloadClass && has_loadClassInternal()) {

       JavaCalls::call_special(&result,

                               class_loader,

                               spec_klass,

                               vmSymbolHandles::loadClassInternal_name(),

                               vmSymbolHandles::string_class_signature(),

                               string,

                               CHECK_(nh));

     } else {

       JavaCalls::call_virtual(&result,

                               class_loader,

                               spec_klass,

                               vmSymbolHandles::loadClass_name(),

                               vmSymbolHandles::string_class_signature(),

                               string,

                               CHECK_(nh));

     }

     assert(result.get_type() == T_OBJECT, "just checking");

     oop obj = (oop) result.get_jobject();

     // Primitive classes return null since forName() can not be

     // used to obtain any of the Class objects representing primitives or void

     if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {

       instanceKlassHandle k =

                 instanceKlassHandle(THREAD, java_lang_Class::as_klassOop(obj));

       // For user defined Java class loaders, check that the name returned is

       // the same as that requested.  This check is done for the bootstrap

       // loader when parsing the class file.

       if (class_name() == k->name()) {

         return k;

       }

     }

     // Class is not found or has the wrong name, return NULL

     return nh;

   }

 }

 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {

   Handle class_loader_h(THREAD, k->class_loader());

   // for bootstrap classloader don't acquire lock

   if (!class_loader_h.is_null()) {

     assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,

          compute_loader_lock_object(class_loader_h, THREAD)),

          "define called without lock");

   }

   // Check class-loading constraints. Throw exception if violation is detected.

   // Grabs and releases SystemDictionary_lock

   // The check_constraints/find_class call and update_dictionary sequence

   // must be "atomic" for a specific class/classloader pair so we never

   // define two different instanceKlasses for that class/classloader pair.

   // Existing classloaders will call define_instance_class with the

   // classloader lock held

   // Parallel classloaders will call find_or_define_instance_class

   // which will require a token to perform the define class

   symbolHandle name_h(THREAD, k->name());

   unsigned int d_hash = dictionary()->compute_hash(name_h, class_loader_h);

   int d_index = dictionary()->hash_to_index(d_hash);

   check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);

   // Register class just loaded with class loader (placed in Vector)

   // Note we do this before updating the dictionary, as this can

   // fail with an OutOfMemoryError (if it does, we will *not* put this

   // class in the dictionary and will not update the class hierarchy).

   if (k->class_loader() != NULL) {

     methodHandle m(THREAD, Universe::loader_addClass_method());

     JavaValue result(T_VOID);

     JavaCallArguments args(class_loader_h);

     args.push_oop(Handle(THREAD, k->java_mirror()));

     JavaCalls::call(&result, m, &args, CHECK);

   }

   // Add the new class. We need recompile lock during update of CHA.

   {

     unsigned int p_hash = placeholders()->compute_hash(name_h, class_loader_h);

     int p_index = placeholders()->hash_to_index(p_hash);

     MutexLocker mu_r(Compile_lock, THREAD);

     // Add to class hierarchy, initialize vtables, and do possible

     // deoptimizations.

     add_to_hierarchy(k, CHECK); // No exception, but can block

     // Add to systemDictionary - so other classes can see it.

     // Grabs and releases SystemDictionary_lock

     update_dictionary(d_index, d_hash, p_index, p_hash,

                       k, class_loader_h, THREAD);

   }

   k->eager_initialize(THREAD);

   // notify jvmti

   if (JvmtiExport::should_post_class_load()) {

       assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");

       JvmtiExport::post_class_load((JavaThread *) THREAD, k());

   }

 }

 // Support parallel classloading

 // Initial implementation for bootstrap classloader

 // For future:

 // For custom class loaders that support parallel classloading,

 // in case they do not synchronize around

 // FindLoadedClass/DefineClass calls, we check for parallel

 // loading for them, wait if a defineClass is in progress

 // and return the initial requestor's results

 // For better performance, the class loaders should synchronize

 // findClass(), i.e. FindLoadedClass/DefineClass or they

 // potentially waste time reading and parsing the bytestream.

 // Note: VM callers should ensure consistency of k/class_name,class_loader

 instanceKlassHandle SystemDictionary::find_or_define_instance_class(symbolHandle class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {

   instanceKlassHandle nh = instanceKlassHandle(); // null Handle

   unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);

   int d_index = dictionary()->hash_to_index(d_hash);

 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS

   unsigned int p_hash = placeholders()->compute_hash(class_name, class_loader);

   int p_index = placeholders()->hash_to_index(p_hash);

   PlaceholderEntry* probe;

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     // First check if class already defined

     klassOop check = find_class(d_index, d_hash, class_name, class_loader);

     if (check != NULL) {

       return(instanceKlassHandle(THREAD, check));

     }

     // Acquire define token for this class/classloader

     symbolHandle nullsymbolHandle;

     probe = placeholders()->find_and_add(p_index, p_hash, class_name, class_loader, PlaceholderTable::DEFINE_CLASS, nullsymbolHandle, THREAD);

     // Check if another thread defining in parallel

     if (probe->definer() == NULL) {

       // Thread will define the class

       probe->set_definer(THREAD);

     } else {

       // Wait for defining thread to finish and return results

       while (probe->definer() != NULL) {

         SystemDictionary_lock->wait();

       }

       if (probe->instanceKlass() != NULL) {

         probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);

         return(instanceKlassHandle(THREAD, probe->instanceKlass()));

       } else {

         // If definer had an error, try again as any new thread would

         probe->set_definer(THREAD);

 #ifdef ASSERT

         klassOop check = find_class(d_index, d_hash, class_name, class_loader);

         assert(check == NULL, "definer missed recording success");

 #endif

       }

     }

   }

   define_instance_class(k, THREAD);

   Handle linkage_exception = Handle(); // null handle

   // definer must notify any waiting threads

   {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, class_name, class_loader);

     assert(probe != NULL, "DEFINE_CLASS placeholder lost?");

     if (probe != NULL) {

       if (HAS_PENDING_EXCEPTION) {

         linkage_exception = Handle(THREAD,PENDING_EXCEPTION);

         CLEAR_PENDING_EXCEPTION;

       } else {

         probe->set_instanceKlass(k());

       }

       probe->set_definer(NULL);

       probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);

       SystemDictionary_lock->notify_all();

     }

   }

   // Can't throw exception while holding lock due to rank ordering

   if (linkage_exception() != NULL) {

     THROW_OOP_(linkage_exception(), nh); // throws exception and returns

   }

   return k;

 }

 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {

   // If class_loader is NULL we synchronize on _system_loader_lock_obj

   if (class_loader.is_null()) {

     return Handle(THREAD, _system_loader_lock_obj);

   } else {

     return class_loader;

   }

 }

 // This method is added to check how often we have to wait to grab loader

 // lock. The results are being recorded in the performance counters defined in

 // ClassLoader::_sync_systemLoaderLockContentionRate and

 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.

 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {

   if (!UsePerfData) {

     return;

   }

   assert(!loader_lock.is_null(), "NULL lock object");

   if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)

       == ObjectSynchronizer::owner_other) {

     // contention will likely happen, so increment the corresponding

     // contention counter.

     if (loader_lock() == _system_loader_lock_obj) {

       ClassLoader::sync_systemLoaderLockContentionRate()->inc();

     } else {

       ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();

     }

   }

 }

 // ----------------------------------------------------------------------------

 // Lookup

 klassOop SystemDictionary::find_class(int index, unsigned int hash,

                                       symbolHandle class_name,

                                       Handle class_loader) {

   assert_locked_or_safepoint(SystemDictionary_lock);

   assert (index == dictionary()->index_for(class_name, class_loader),

           "incorrect index?");

   klassOop k = dictionary()->find_class(index, hash, class_name, class_loader);

   return k;

 }

 // Basic find on classes in the midst of being loaded

 symbolOop SystemDictionary::find_placeholder(int index, unsigned int hash,

                                              symbolHandle class_name,

                                              Handle class_loader) {

   assert_locked_or_safepoint(SystemDictionary_lock);

   return placeholders()->find_entry(index, hash, class_name, class_loader);

 }

 // Used for assertions and verification only

 oop SystemDictionary::find_class_or_placeholder(symbolHandle class_name,

                                                 Handle class_loader) {

   #ifndef ASSERT

   guarantee(VerifyBeforeGC   ||

             VerifyDuringGC   ||

             VerifyBeforeExit ||

             VerifyAfterGC, "too expensive");

   #endif

   assert_locked_or_safepoint(SystemDictionary_lock);

   symbolOop class_name_ = class_name();

   oop class_loader_ = class_loader();

   // First look in the loaded class array

   unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);

   int d_index = dictionary()->hash_to_index(d_hash);

   oop lookup = find_class(d_index, d_hash, class_name, class_loader);

   if (lookup == NULL) {

     // Next try the placeholders

     unsigned int p_hash = placeholders()->compute_hash(class_name,class_loader);

     int p_index = placeholders()->hash_to_index(p_hash);

     lookup = find_placeholder(p_index, p_hash, class_name, class_loader);

   }

   return lookup;

 }

 // Get the next class in the diictionary.

 klassOop SystemDictionary::try_get_next_class() {

   return dictionary()->try_get_next_class();

 }

 // ----------------------------------------------------------------------------

 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock

 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in

 // before a new class is used.

 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {

   assert(k.not_null(), "just checking");

   // Link into hierachy. Make sure the vtables are initialized before linking into

   k->append_to_sibling_list();                    // add to superklass/sibling list

   k->process_interfaces(THREAD);                  // handle all "implements" declarations

   k->set_init_state(instanceKlass::loaded);

   // Now flush all code that depended on old class hierarchy.

   // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)

   // Also, first reinitialize vtable because it may have gotten out of synch

   // while the new class wasn't connected to the class hierarchy.

   Universe::flush_dependents_on(k);

 }

 // ----------------------------------------------------------------------------

 // GC support

 // Following roots during mark-sweep is separated in two phases.

 //

 // The first phase follows preloaded classes and all other system

 // classes, since these will never get unloaded anyway.

 //

 // The second phase removes (unloads) unreachable classes from the

 // system dictionary and follows the remaining classes' contents.

 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {

   // Follow preloaded classes/mirrors and system loader object

   blk->do_oop(&_java_system_loader);

   preloaded_oops_do(blk);

   always_strong_classes_do(blk);

 }

 void SystemDictionary::always_strong_classes_do(OopClosure* blk) {

   // Follow all system classes and temporary placeholders in dictionary

   dictionary()->always_strong_classes_do(blk);

   // Placeholders. These are *always* strong roots, as they

   // represent classes we're actively loading.

   placeholders_do(blk);

   // Loader constraints. We must keep the symbolOop used in the name alive.

   constraints()->always_strong_classes_do(blk);

   // Resolution errors keep the symbolOop for the error alive

   resolution_errors()->always_strong_classes_do(blk);

 }

 void SystemDictionary::placeholders_do(OopClosure* blk) {

   placeholders()->oops_do(blk);

 }

 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {

   bool result = dictionary()->do_unloading(is_alive);

   constraints()->purge_loader_constraints(is_alive);

   resolution_errors()->purge_resolution_errors(is_alive);

   return result;

 }

 // The mirrors are scanned by shared_oops_do() which is

 // not called by oops_do().  In order to process oops in

 // a necessary order, shared_oops_do() is call by

 // Universe::oops_do().

 void SystemDictionary::oops_do(OopClosure* f) {

   // Adjust preloaded classes and system loader object

   f->do_oop(&_java_system_loader);

   preloaded_oops_do(f);

   lazily_loaded_oops_do(f);

   // Adjust dictionary

   dictionary()->oops_do(f);

   // Partially loaded classes

   placeholders()->oops_do(f);

   // Adjust constraint table

   constraints()->oops_do(f);

   // Adjust resolution error table

   resolution_errors()->oops_do(f);

 }

 void SystemDictionary::preloaded_oops_do(OopClosure* f) {

   f->do_oop((oop*) &wk_klass_name_limits[0]);

   f->do_oop((oop*) &wk_klass_name_limits[1]);

   for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {

     f->do_oop((oop*) &_well_known_klasses[k]);

   }

   {

     for (int i = 0; i < T_VOID+1; i++) {

       if (_box_klasses[i] != NULL) {

         assert(i >= T_BOOLEAN, "checking");

         f->do_oop((oop*) &_box_klasses[i]);

       }

     }

   }

   // The basic type mirrors would have already been processed in

   // Universe::oops_do(), via a call to shared_oops_do(), so should

   // not be processed again.

   f->do_oop((oop*) &_system_loader_lock_obj);

   FilteredFieldsMap::klasses_oops_do(f);

 }

 void SystemDictionary::lazily_loaded_oops_do(OopClosure* f) {

   f->do_oop((oop*) &_abstract_ownable_synchronizer_klass);

 }

 // Just the classes from defining class loaders

 // Don't iterate over placeholders

 void SystemDictionary::classes_do(void f(klassOop)) {

   dictionary()->classes_do(f);

 }

 // Added for initialize_itable_for_klass

 //   Just the classes from defining class loaders

 // Don't iterate over placeholders

 void SystemDictionary::classes_do(void f(klassOop, TRAPS), TRAPS) {

   dictionary()->classes_do(f, CHECK);

 }

 //   All classes, and their class loaders

 // Don't iterate over placeholders

 void SystemDictionary::classes_do(void f(klassOop, oop)) {

   dictionary()->classes_do(f);

 }

 //   All classes, and their class loaders

 //   (added for helpers that use HandleMarks and ResourceMarks)

 // Don't iterate over placeholders

 void SystemDictionary::classes_do(void f(klassOop, oop, TRAPS), TRAPS) {

   dictionary()->classes_do(f, CHECK);

 }

 void SystemDictionary::placeholders_do(void f(symbolOop, oop)) {

   placeholders()->entries_do(f);

 }

 void SystemDictionary::methods_do(void f(methodOop)) {

   dictionary()->methods_do(f);

 }

 // ----------------------------------------------------------------------------

 // Lazily load klasses

 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {

   assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");

   // if multiple threads calling this function, only one thread will load

   // the class.  The other threads will find the loaded version once the

   // class is loaded.

   klassOop aos = _abstract_ownable_synchronizer_klass;

   if (aos == NULL) {

     klassOop k = resolve_or_fail(vmSymbolHandles::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);

     // Force a fence to prevent any read before the write completes

     OrderAccess::fence();

     _abstract_ownable_synchronizer_klass = k;

   }

 }

 // ----------------------------------------------------------------------------

 // Initialization

 void SystemDictionary::initialize(TRAPS) {

   // Allocate arrays

   assert(dictionary() == NULL,

          "SystemDictionary should only be initialized once");

   _dictionary = new Dictionary(_nof_buckets);

   _placeholders = new PlaceholderTable(_nof_buckets);

   _number_of_modifications = 0;

   _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);

   _resolution_errors = new ResolutionErrorTable(_resolution_error_size);

   // Allocate private object used as system class loader lock

   _system_loader_lock_obj = oopFactory::new_system_objArray(0, CHECK);

   // Initialize basic classes

   initialize_preloaded_classes(CHECK);

 }

 // Compact table of directions on the initialization of klasses:

 static const short wk_init_info[] = {

   #define WK_KLASS_INIT_INFO(name, symbol, option) \

     ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \

           << SystemDictionary::CEIL_LG_OPTION_LIMIT) \

       | (int)SystemDictionary::option ),

   WK_KLASSES_DO(WK_KLASS_INIT_INFO)

   #undef WK_KLASS_INIT_INFO

   0

 };

 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {

   assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");

   int  info = wk_init_info[id - FIRST_WKID];

   int  sid  = (info >> CEIL_LG_OPTION_LIMIT);

   symbolHandle symbol = vmSymbolHandles::symbol_handle_at((vmSymbols::SID)sid);

   klassOop*    klassp = &_well_known_klasses[id];

   bool must_load = (init_opt < SystemDictionary::Opt);

   bool try_load  = true;

   if (init_opt == SystemDictionary::Opt_Kernel) {

 #ifndef KERNEL

     try_load = false;

 #endif //KERNEL

   }

   if ((*klassp) == NULL && try_load) {

     if (must_load) {

       (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class

     } else {

       (*klassp) = resolve_or_null(symbol,       CHECK_0); // load optional klass

     }

   }

   return ((*klassp) != NULL);

 }

 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {

   assert((int)start_id <= (int)limit_id, "IDs are out of order!");

   for (int id = (int)start_id; id < (int)limit_id; id++) {

     assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");

     int info = wk_init_info[id - FIRST_WKID];

     int sid  = (info >> CEIL_LG_OPTION_LIMIT);

     int opt  = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));

     initialize_wk_klass((WKID)id, opt, CHECK);

     // Update limits, so find_well_known_klass can be very fast:

     symbolOop s = vmSymbols::symbol_at((vmSymbols::SID)sid);

     if (wk_klass_name_limits[1] == NULL) {

       wk_klass_name_limits[0] = wk_klass_name_limits[1] = s;

     } else if (wk_klass_name_limits[1] < s) {

       wk_klass_name_limits[1] = s;

     } else if (wk_klass_name_limits[0] > s) {

       wk_klass_name_limits[0] = s;

     }

   }

 }

 void SystemDictionary::initialize_preloaded_classes(TRAPS) {

   assert(WK_KLASS(object_klass) == NULL, "preloaded classes should only be initialized once");

   // Preload commonly used klasses

   WKID scan = FIRST_WKID;

   // first do Object, String, Class

   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(class_klass), scan, CHECK);

   debug_only(instanceKlass::verify_class_klass_nonstatic_oop_maps(WK_KLASS(class_klass)));

   // Fixup mirrors for classes loaded before java.lang.Class.

   // These calls iterate over the objects currently in the perm gen

   // so calling them at this point is matters (not before when there

   // are fewer objects and not later after there are more objects

   // in the perm gen.

   Universe::initialize_basic_type_mirrors(CHECK);

   Universe::fixup_mirrors(CHECK);

   // do a bunch more:

   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(reference_klass), scan, CHECK);

   // Preload ref klasses and set reference types

   instanceKlass::cast(WK_KLASS(reference_klass))->set_reference_type(REF_OTHER);

   instanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(reference_klass));

   initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(phantom_reference_klass), scan, CHECK);

   instanceKlass::cast(WK_KLASS(soft_reference_klass))->set_reference_type(REF_SOFT);

   instanceKlass::cast(WK_KLASS(weak_reference_klass))->set_reference_type(REF_WEAK);

   instanceKlass::cast(WK_KLASS(final_reference_klass))->set_reference_type(REF_FINAL);

   instanceKlass::cast(WK_KLASS(phantom_reference_klass))->set_reference_type(REF_PHANTOM);

   initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);

   _box_klasses[T_BOOLEAN] = WK_KLASS(boolean_klass);

   _box_klasses[T_CHAR]    = WK_KLASS(char_klass);

   _box_klasses[T_FLOAT]   = WK_KLASS(float_klass);

   _box_klasses[T_DOUBLE]  = WK_KLASS(double_klass);

   _box_klasses[T_BYTE]    = WK_KLASS(byte_klass);

   _box_klasses[T_SHORT]   = WK_KLASS(short_klass);

   _box_klasses[T_INT]     = WK_KLASS(int_klass);

   _box_klasses[T_LONG]    = WK_KLASS(long_klass);

   //_box_klasses[T_OBJECT]  = WK_KLASS(object_klass);

   //_box_klasses[T_ARRAY]   = WK_KLASS(object_klass);

 #ifdef KERNEL

   if (sun_jkernel_DownloadManager_klass() == NULL) {

     warning("Cannot find sun/jkernel/DownloadManager");

   }

 #endif // KERNEL

   { // Compute whether we should use loadClass or loadClassInternal when loading classes.

     methodOop method = instanceKlass::cast(classloader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());

     _has_loadClassInternal = (method != NULL);

   }

   { // Compute whether we should use checkPackageAccess or NOT

     methodOop method = instanceKlass::cast(classloader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());

     _has_checkPackageAccess = (method != NULL);

   }

 }

 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).

 // If so, returns the basic type it holds.  If not, returns T_OBJECT.

 BasicType SystemDictionary::box_klass_type(klassOop k) {

   assert(k != NULL, "");

   for (int i = T_BOOLEAN; i < T_VOID+1; i++) {

     if (_box_klasses[i] == k)

       return (BasicType)i;

   }

   return T_OBJECT;

 }

 // Constraints on class loaders. The details of the algorithm can be

 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java

 // Virtual Machine" by Sheng Liang and Gilad Bracha.  The basic idea is

 // that the system dictionary needs to maintain a set of contraints that

 // must be satisfied by all classes in the dictionary.

 // if defining is true, then LinkageError if already in systemDictionary

 // if initiating loader, then ok if instanceKlass matches existing entry

 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,

                                          instanceKlassHandle k,

                                          Handle class_loader, bool defining,

                                          TRAPS) {

   const char *linkage_error = NULL;

   {

     symbolHandle name (THREAD, k->name());

     MutexLocker mu(SystemDictionary_lock, THREAD);

     klassOop check = find_class(d_index, d_hash, name, class_loader);

     if (check != (klassOop)NULL) {

       // if different instanceKlass - duplicate class definition,

       // else - ok, class loaded by a different thread in parallel,

       // we should only have found it if it was done loading and ok to use

       // system dictionary only holds instance classes, placeholders

       // also holds array classes

       assert(check->klass_part()->oop_is_instance(), "noninstance in systemdictionary");

       if ((defining == true) || (k() != check)) {

         linkage_error = "loader (instance of  %s): attempted  duplicate class "

           "definition for name: \"%s\"";

       } else {

         return;

       }

     }

 #ifdef ASSERT

     unsigned int p_hash = placeholders()->compute_hash(name, class_loader);

     int p_index = placeholders()->hash_to_index(p_hash);

     symbolOop ph_check = find_placeholder(p_index, p_hash, name, class_loader);

     assert(ph_check == NULL || ph_check == name(), "invalid symbol");

 #endif

     if (linkage_error == NULL) {

       if (constraints()->check_or_update(k, class_loader, name) == false) {

         linkage_error = "loader constraint violation: loader (instance of %s)"

           " previously initiated loading for a different type with name \"%s\"";

       }

     }

   }

   // Throw error now if needed (cannot throw while holding

   // SystemDictionary_lock because of rank ordering)

   if (linkage_error) {

     ResourceMark rm(THREAD);

     const char* class_loader_name = loader_name(class_loader());

     char* type_name = k->name()->as_C_string();

     size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +

       strlen(type_name);

     char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);

     jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);

     THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);

   }

 }

 // Update system dictionary - done after check_constraint and add_to_hierachy

 // have been called.

 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,

                                          int p_index, unsigned int p_hash,

                                          instanceKlassHandle k,

                                          Handle class_loader,

                                          TRAPS) {

   // Compile_lock prevents systemDictionary updates during compilations

   assert_locked_or_safepoint(Compile_lock);

   symbolHandle name (THREAD, k->name());

   {

   MutexLocker mu1(SystemDictionary_lock, THREAD);

   // See whether biased locking is enabled and if so set it for this

   // klass.

   // Note that this must be done past the last potential blocking

   // point / safepoint. We enable biased locking lazily using a

   // VM_Operation to iterate the SystemDictionary and installing the

   // biasable mark word into each instanceKlass's prototype header.

   // To avoid race conditions where we accidentally miss enabling the

   // optimization for one class in the process of being added to the

   // dictionary, we must not safepoint after the test of

   // BiasedLocking::enabled().

   if (UseBiasedLocking && BiasedLocking::enabled()) {

     // Set biased locking bit for all loaded classes; it will be

     // cleared if revocation occurs too often for this type

     // NOTE that we must only do this when the class is initally

     // defined, not each time it is referenced from a new class loader

     if (k->class_loader() == class_loader()) {

       k->set_prototype_header(markOopDesc::biased_locking_prototype());

     }

   }

   // Check for a placeholder. If there, remove it and make a

   // new system dictionary entry.

   placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);

   klassOop sd_check = find_class(d_index, d_hash, name, class_loader);

   if (sd_check == NULL) {

     dictionary()->add_klass(name, class_loader, k);

     notice_modification();

   }

 #ifdef ASSERT

   sd_check = find_class(d_index, d_hash, name, class_loader);

   assert (sd_check != NULL, "should have entry in system dictionary");

 // Changed to allow PH to remain to complete class circularity checking

 // while only one thread can define a class at one time, multiple

 // classes can resolve the superclass for a class at one time,

 // and the placeholder is used to track that

 //  symbolOop ph_check = find_placeholder(p_index, p_hash, name, class_loader);

 //  assert (ph_check == NULL, "should not have a placeholder entry");

 #endif

     SystemDictionary_lock->notify_all();

   }

 }

 klassOop SystemDictionary::find_constrained_instance_or_array_klass(

                     symbolHandle class_name, Handle class_loader, TRAPS) {

   // First see if it has been loaded directly.

   // Force the protection domain to be null.  (This removes protection checks.)

   Handle no_protection_domain;

   klassOop klass = find_instance_or_array_klass(class_name, class_loader,

                                                 no_protection_domain, CHECK_NULL);

   if (klass != NULL)

     return klass;

   // Now look to see if it has been loaded elsewhere, and is subject to

   // a loader constraint that would require this loader to return the

   // klass that is already loaded.

   if (FieldType::is_array(class_name())) {

     // Array classes are hard because their klassOops are not kept in the

     // constraint table. The array klass may be constrained, but the elem class

     // may not be.

     jint dimension;

     symbolOop object_key;

     BasicType t = FieldType::get_array_info(class_name(), &dimension,

                                             &object_key, CHECK_(NULL));

     if (t != T_OBJECT) {

       klass = Universe::typeArrayKlassObj(t);

     } else {

       symbolHandle elem_name(THREAD, object_key);

       MutexLocker mu(SystemDictionary_lock, THREAD);

       klass = constraints()->find_constrained_elem_klass(class_name, elem_name, class_loader, THREAD);

     }

     if (klass != NULL) {

       klass = Klass::cast(klass)->array_klass_or_null(dimension);

     }

   } else {

     MutexLocker mu(SystemDictionary_lock, THREAD);

     // Non-array classes are easy: simply check the constraint table.

     klass = constraints()->find_constrained_klass(class_name, class_loader);

   }

   return klass;

 }

 bool SystemDictionary::add_loader_constraint(symbolHandle class_name,

                                              Handle class_loader1,

                                              Handle class_loader2,

                                              Thread* THREAD) {

   unsigned int d_hash1 = dictionary()->compute_hash(class_name, class_loader1);

   int d_index1 = dictionary()->hash_to_index(d_hash1);

   unsigned int d_hash2 = dictionary()->compute_hash(class_name, class_loader2);

   int d_index2 = dictionary()->hash_to_index(d_hash2);

   {

     MutexLocker mu_s(SystemDictionary_lock, THREAD);

     // Better never do a GC while we're holding these oops

     No_Safepoint_Verifier nosafepoint;

     klassOop klass1 = find_class(d_index1, d_hash1, class_name, class_loader1);

     klassOop klass2 = find_class(d_index2, d_hash2, class_name, class_loader2);

     return constraints()->add_entry(class_name, klass1, class_loader1,

                                     klass2, class_loader2);

   }

 }

 // Add entry to resolution error table to record the error when the first

 // attempt to resolve a reference to a class has failed.

 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, symbolHandle error) {

   unsigned int hash = resolution_errors()->compute_hash(pool, which);

   int index = resolution_errors()->hash_to_index(hash);

   {

     MutexLocker ml(SystemDictionary_lock, Thread::current());

     resolution_errors()->add_entry(index, hash, pool, which, error);

   }

 }

 // Lookup resolution error table. Returns error if found, otherwise NULL.

 symbolOop SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {

   unsigned int hash = resolution_errors()->compute_hash(pool, which);

   int index = resolution_errors()->hash_to_index(hash);

   {

     MutexLocker ml(SystemDictionary_lock, Thread::current());

     ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);

     return (entry != NULL) ? entry->error() : (symbolOop)NULL;

   }

 }

 // Make sure all class components (including arrays) in the given

 // signature will be resolved to the same class in both loaders.

 // Returns the name of the type that failed a loader constraint check, or

 // NULL if no constraint failed. The returned C string needs cleaning up

 // with a ResourceMark in the caller

 char* SystemDictionary::check_signature_loaders(symbolHandle signature,

                                                Handle loader1, Handle loader2,

                                                bool is_method, TRAPS)  {

   // Nothing to do if loaders are the same.

   if (loader1() == loader2()) {

     return NULL;

   }

   SignatureStream sig_strm(signature, is_method);

   while (!sig_strm.is_done()) {

     if (sig_strm.is_object()) {

       symbolOop s = sig_strm.as_symbol(CHECK_NULL);

       symbolHandle sig (THREAD, s);

       if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {

         return sig()->as_C_string();

       }

     }

     sig_strm.next();

   }

   return NULL;

 }

 // Since the identity hash code for symbols changes when the symbols are

 // moved from the regular perm gen (hash in the mark word) to the shared

 // spaces (hash is the address), the classes loaded into the dictionary

 // may be in the wrong buckets.

 void SystemDictionary::reorder_dictionary() {

   dictionary()->reorder_dictionary();

 }

 void SystemDictionary::copy_buckets(char** top, char* end) {

   dictionary()->copy_buckets(top, end);

 }

 void SystemDictionary::copy_table(char** top, char* end) {

   dictionary()->copy_table(top, end);

 }

 void SystemDictionary::reverse() {

   dictionary()->reverse();

 }

 int SystemDictionary::number_of_classes() {

   return dictionary()->number_of_entries();

 }

 // ----------------------------------------------------------------------------

 #ifndef PRODUCT

 void SystemDictionary::print() {

   dictionary()->print();

   // Placeholders

   GCMutexLocker mu(SystemDictionary_lock);

   placeholders()->print();

   // loader constraints - print under SD_lock

   constraints()->print();

 }

 #endif

 void SystemDictionary::verify() {

   guarantee(dictionary() != NULL, "Verify of system dictionary failed");

   guarantee(constraints() != NULL,

             "Verify of loader constraints failed");

   guarantee(dictionary()->number_of_entries() >= 0 &&

             placeholders()->number_of_entries() >= 0,

             "Verify of system dictionary failed");

   // Verify dictionary

   dictionary()->verify();

   GCMutexLocker mu(SystemDictionary_lock);

   placeholders()->verify();

   // Verify constraint table

   guarantee(constraints() != NULL, "Verify of loader constraints failed");

   constraints()->verify(dictionary());

 }

 void SystemDictionary::verify_obj_klass_present(Handle obj,

                                                 symbolHandle class_name,

                                                 Handle class_loader) {

   GCMutexLocker mu(SystemDictionary_lock);

   oop probe = find_class_or_placeholder(class_name, class_loader);

   if (probe == NULL) {

     probe = SystemDictionary::find_shared_class(class_name);

   }

   guarantee(probe != NULL &&

             (!probe->is_klass() || probe == obj()),

                      "Loaded klasses should be in SystemDictionary");

 }

 #ifndef PRODUCT

 // statistics code

 class ClassStatistics: AllStatic {

  private:

   static int nclasses;        // number of classes

   static int nmethods;        // number of methods

   static int nmethoddata;     // number of methodData

   static int class_size;      // size of class objects in words

   static int method_size;     // size of method objects in words

   static int debug_size;      // size of debug info in methods

   static int methoddata_size; // size of methodData objects in words

   static void do_class(klassOop k) {

     nclasses++;

     class_size += k->size();

     if (k->klass_part()->oop_is_instance()) {

       instanceKlass* ik = (instanceKlass*)k->klass_part();

       class_size += ik->methods()->size();

       class_size += ik->constants()->size();

       class_size += ik->local_interfaces()->size();

       class_size += ik->transitive_interfaces()->size();

       // We do not have to count implementors, since we only store one!

       class_size += ik->fields()->size();

     }

   }

   static void do_method(methodOop m) {

     nmethods++;

     method_size += m->size();

     // class loader uses same objArray for empty vectors, so don't count these

     if (m->exception_table()->length() != 0)   method_size += m->exception_table()->size();

     if (m->has_stackmap_table()) {

       method_size += m->stackmap_data()->size();

     }

     methodDataOop mdo = m->method_data();

     if (mdo != NULL) {

       nmethoddata++;

       methoddata_size += mdo->size();

     }

   }

  public:

   static void print() {

     SystemDictionary::classes_do(do_class);

     SystemDictionary::methods_do(do_method);

     tty->print_cr("Class statistics:");

     tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);

     tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,

                   (method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);

     tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);

   }

 };

 int ClassStatistics::nclasses        = 0;

 int ClassStatistics::nmethods        = 0;

 int ClassStatistics::nmethoddata     = 0;

 int ClassStatistics::class_size      = 0;

 int ClassStatistics::method_size     = 0;

 int ClassStatistics::debug_size      = 0;

 int ClassStatistics::methoddata_size = 0;

 void SystemDictionary::print_class_statistics() {

   ResourceMark rm;

   ClassStatistics::print();

 }

 class MethodStatistics: AllStatic {

  public:

   enum {

     max_parameter_size = 10

   };

  private:

   static int _number_of_methods;

   static int _number_of_final_methods;

   static int _number_of_static_methods;

   static int _number_of_native_methods;

   static int _number_of_synchronized_methods;

   static int _number_of_profiled_methods;

   static int _number_of_bytecodes;

   static int _parameter_size_profile[max_parameter_size];

   static int _bytecodes_profile[Bytecodes::number_of_java_codes];

   static void initialize() {

     _number_of_methods        = 0;

     _number_of_final_methods  = 0;

     _number_of_static_methods = 0;

     _number_of_native_methods = 0;

     _number_of_synchronized_methods = 0;

     _number_of_profiled_methods = 0;

     _number_of_bytecodes      = 0;

     for (int i = 0; i < max_parameter_size             ; i++) _parameter_size_profile[i] = 0;

     for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile     [j] = 0;

   };

   static void do_method(methodOop m) {

     _number_of_methods++;

     // collect flag info

     if (m->is_final()       ) _number_of_final_methods++;

     if (m->is_static()      ) _number_of_static_methods++;

     if (m->is_native()      ) _number_of_native_methods++;

     if (m->is_synchronized()) _number_of_synchronized_methods++;

     if (m->method_data() != NULL) _number_of_profiled_methods++;

     // collect parameter size info (add one for receiver, if any)

     _parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;

     // collect bytecodes info

     {

       Thread *thread = Thread::current();

       HandleMark hm(thread);

       BytecodeStream s(methodHandle(thread, m));

       Bytecodes::Code c;

       while ((c = s.next()) >= 0) {

         _number_of_bytecodes++;

         _bytecodes_profile[c]++;

       }

     }

   }

  public:

   static void print() {

     initialize();

     SystemDictionary::methods_do(do_method);

     // generate output

     tty->cr();

     tty->print_cr("Method statistics (static):");

     // flag distribution

     tty->cr();

     tty->print_cr("%6d final        methods  %6.1f%%", _number_of_final_methods       , _number_of_final_methods        * 100.0F / _number_of_methods);

     tty->print_cr("%6d static       methods  %6.1f%%", _number_of_static_methods      , _number_of_static_methods       * 100.0F / _number_of_methods);

     tty->print_cr("%6d native       methods  %6.1f%%", _number_of_native_methods      , _number_of_native_methods       * 100.0F / _number_of_methods);

     tty->print_cr("%6d synchronized methods  %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);

     tty->print_cr("%6d profiled     methods  %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);

     // parameter size profile

     tty->cr();

     { int tot = 0;

       int avg = 0;

       for (int i = 0; i < max_parameter_size; i++) {

         int n = _parameter_size_profile[i];

         tot += n;

         avg += n*i;

         tty->print_cr("parameter size = %1d: %6d methods  %5.1f%%", i, n, n * 100.0F / _number_of_methods);

       }

       assert(tot == _number_of_methods, "should be the same");

       tty->print_cr("                    %6d methods  100.0%%", _number_of_methods);

       tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);

     }

     // bytecodes profile

     tty->cr();

     { int tot = 0;

       for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {

         if (Bytecodes::is_defined(i)) {

           Bytecodes::Code c = Bytecodes::cast(i);

           int n = _bytecodes_profile[c];

           tot += n;

           tty->print_cr("%9d  %7.3f%%  %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));

         }

       }

       assert(tot == _number_of_bytecodes, "should be the same");

       tty->print_cr("%9d  100.000%%", _number_of_bytecodes);

     }

     tty->cr();

   }

 };

 int MethodStatistics::_number_of_methods;

 int MethodStatistics::_number_of_final_methods;

 int MethodStatistics::_number_of_static_methods;

 int MethodStatistics::_number_of_native_methods;

 int MethodStatistics::_number_of_synchronized_methods;

 int MethodStatistics::_number_of_profiled_methods;

 int MethodStatistics::_number_of_bytecodes;

 int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];

 int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];

 void SystemDictionary::print_method_statistics() {

   MethodStatistics::print();

 }

 #endif // PRODUCT