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 /*

  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

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  */

 #ifndef SHARE_VM_CLASSFILE_SYSTEMDICTIONARY_HPP

 #define SHARE_VM_CLASSFILE_SYSTEMDICTIONARY_HPP

 #include "classfile/classFileStream.hpp"

 #include "classfile/classLoader.hpp"

 #include "oops/objArrayOop.hpp"

 #include "oops/symbolOop.hpp"

 #include "runtime/java.hpp"

 #include "runtime/reflectionUtils.hpp"

 #include "utilities/hashtable.hpp"

 // The system dictionary stores all loaded classes and maps:

 //

 //   [class name,class loader] -> class   i.e.  [symbolOop,oop] -> klassOop

 //

 // Classes are loaded lazily. The default VM class loader is

 // represented as NULL.

 // The underlying data structure is an open hash table with a fixed number

 // of buckets. During loading the loader object is locked, (for the VM loader

 // a private lock object is used). Class loading can thus be done concurrently,

 // but only by different loaders.

 //

 // During loading a placeholder (name, loader) is temporarily placed in

 // a side data structure, and is used to detect ClassCircularityErrors

 // and to perform verification during GC.  A GC can occur in the midst

 // of class loading, as we call out to Java, have to take locks, etc.

 //

 // When class loading is finished, a new entry is added to the system

 // dictionary and the place holder is removed. Note that the protection

 // domain field of the system dictionary has not yet been filled in when

 // the "real" system dictionary entry is created.

 //

 // Clients of this class who are interested in finding if a class has

 // been completely loaded -- not classes in the process of being loaded --

 // can read the SystemDictionary unlocked. This is safe because

 //    - entries are only deleted at safepoints

 //    - readers cannot come to a safepoint while actively examining

 //         an entry  (an entry cannot be deleted from under a reader)

 //    - entries must be fully formed before they are available to concurrent

 //         readers (we must ensure write ordering)

 //

 // Note that placeholders are deleted at any time, as they are removed

 // when a class is completely loaded. Therefore, readers as well as writers

 // of placeholders must hold the SystemDictionary_lock.

 //

 class Dictionary;

 class PlaceholderTable;

 class LoaderConstraintTable;

 class HashtableBucket;

 class ResolutionErrorTable;

 class SymbolPropertyTable;

 // Certain classes are preloaded, such as java.lang.Object and java.lang.String.

 // They are all "well-known", in the sense that no class loader is allowed

 // to provide a different definition.

 //

 // These klasses must all have names defined in vmSymbols.

 #define WK_KLASS_ENUM_NAME(kname)    kname##_knum

 // Each well-known class has a short klass name (like object_klass),

 // a vmSymbol name (like java_lang_Object), and a flag word

 // that makes some minor distinctions, like whether the klass

 // is preloaded, optional, release-specific, etc.

 // The order of these definitions is significant; it is the order in which

 // preloading is actually performed by initialize_preloaded_classes.

 #define WK_KLASSES_DO(template)                                               \

   /* well-known classes */                                                    \

   template(Object_klass,                 java_lang_Object,               Pre) \

   template(String_klass,                 java_lang_String,               Pre) \

   template(Class_klass,                  java_lang_Class,                Pre) \

   template(Cloneable_klass,              java_lang_Cloneable,            Pre) \

   template(ClassLoader_klass,            java_lang_ClassLoader,          Pre) \

   template(Serializable_klass,           java_io_Serializable,           Pre) \

   template(System_klass,                 java_lang_System,               Pre) \

   template(Throwable_klass,              java_lang_Throwable,            Pre) \

   template(Error_klass,                  java_lang_Error,                Pre) \

   template(ThreadDeath_klass,            java_lang_ThreadDeath,          Pre) \

   template(Exception_klass,              java_lang_Exception,            Pre) \

   template(RuntimeException_klass,       java_lang_RuntimeException,     Pre) \

   template(ProtectionDomain_klass,       java_security_ProtectionDomain, Pre) \

   template(AccessControlContext_klass,   java_security_AccessControlContext, Pre) \

   template(ClassNotFoundException_klass, java_lang_ClassNotFoundException, Pre) \

   template(NoClassDefFoundError_klass,   java_lang_NoClassDefFoundError, Pre) \

   template(LinkageError_klass,           java_lang_LinkageError,         Pre) \

   template(ClassCastException_klass,     java_lang_ClassCastException,   Pre) \

   template(ArrayStoreException_klass,    java_lang_ArrayStoreException,  Pre) \

   template(VirtualMachineError_klass,    java_lang_VirtualMachineError,  Pre) \

   template(OutOfMemoryError_klass,       java_lang_OutOfMemoryError,     Pre) \

   template(StackOverflowError_klass,     java_lang_StackOverflowError,   Pre) \

   template(IllegalMonitorStateException_klass, java_lang_IllegalMonitorStateException, Pre) \

   template(Reference_klass,              java_lang_ref_Reference,        Pre) \

                                                                               \

   /* Preload ref klasses and set reference types */                           \

   template(SoftReference_klass,          java_lang_ref_SoftReference,    Pre) \

   template(WeakReference_klass,          java_lang_ref_WeakReference,    Pre) \

   template(FinalReference_klass,         java_lang_ref_FinalReference,   Pre) \

   template(PhantomReference_klass,       java_lang_ref_PhantomReference, Pre) \

   template(Finalizer_klass,              java_lang_ref_Finalizer,        Pre) \

                                                                               \

   template(Thread_klass,                 java_lang_Thread,               Pre) \

   template(ThreadGroup_klass,            java_lang_ThreadGroup,          Pre) \

   template(Properties_klass,             java_util_Properties,           Pre) \

   template(reflect_AccessibleObject_klass, java_lang_reflect_AccessibleObject, Pre) \

   template(reflect_Field_klass,          java_lang_reflect_Field,        Pre) \

   template(reflect_Method_klass,         java_lang_reflect_Method,       Pre) \

   template(reflect_Constructor_klass,    java_lang_reflect_Constructor,  Pre) \

                                                                               \

   /* NOTE: needed too early in bootstrapping process to have checks based on JDK version */ \

   /* Universe::is_gte_jdk14x_version() is not set up by this point. */        \

   /* It's okay if this turns out to be NULL in non-1.4 JDKs. */               \

   template(reflect_MagicAccessorImpl_klass,          sun_reflect_MagicAccessorImpl,  Opt) \

   template(reflect_MethodAccessorImpl_klass, sun_reflect_MethodAccessorImpl, Opt_Only_JDK14NewRef) \

   template(reflect_ConstructorAccessorImpl_klass, sun_reflect_ConstructorAccessorImpl, Opt_Only_JDK14NewRef) \

   template(reflect_DelegatingClassLoader_klass, sun_reflect_DelegatingClassLoader, Opt) \

   template(reflect_ConstantPool_klass,  sun_reflect_ConstantPool,       Opt_Only_JDK15) \

   template(reflect_UnsafeStaticFieldAccessorImpl_klass, sun_reflect_UnsafeStaticFieldAccessorImpl, Opt_Only_JDK15) \

                                                                               \

   /* support for dynamic typing; it's OK if these are NULL in earlier JDKs */ \

   template(MethodHandle_klass,           java_dyn_MethodHandle,          Opt) \

   template(MemberName_klass,             sun_dyn_MemberName,             Opt) \

   template(MethodHandleImpl_klass,       sun_dyn_MethodHandleImpl,       Opt) \

   template(MethodHandleNatives_klass,    sun_dyn_MethodHandleNatives,    Opt) \

   template(AdapterMethodHandle_klass,    sun_dyn_AdapterMethodHandle,    Opt) \

   template(BoundMethodHandle_klass,      sun_dyn_BoundMethodHandle,      Opt) \

   template(DirectMethodHandle_klass,     sun_dyn_DirectMethodHandle,     Opt) \

   template(MethodType_klass,             java_dyn_MethodType,            Opt) \

   template(MethodTypeForm_klass,         java_dyn_MethodTypeForm,        Opt) \

   template(WrongMethodTypeException_klass, java_dyn_WrongMethodTypeException, Opt) \

   template(Linkage_klass,                java_dyn_Linkage,               Opt) \

   template(CallSite_klass,               java_dyn_CallSite,              Opt) \

   /* Note: MethodHandle must be first, and CallSite last in group */          \

                                                                               \

   template(StringBuffer_klass,           java_lang_StringBuffer,         Pre) \

   template(StringBuilder_klass,          java_lang_StringBuilder,        Pre) \

                                                                               \

   /* It's NULL in non-1.4 JDKs. */                                            \

   template(StackTraceElement_klass,      java_lang_StackTraceElement,    Opt) \

   /* Universe::is_gte_jdk14x_version() is not set up by this point. */        \

   /* It's okay if this turns out to be NULL in non-1.4 JDKs. */               \

   template(java_nio_Buffer_klass,        java_nio_Buffer,                Opt) \

                                                                               \

   /* If this class isn't present, it won't be referenced. */                  \

   template(sun_misc_AtomicLongCSImpl_klass, sun_misc_AtomicLongCSImpl,   Opt) \

                                                                               \

   template(sun_jkernel_DownloadManager_klass, sun_jkernel_DownloadManager, Opt_Kernel) \

                                                                               \

   /* Preload boxing klasses */                                                \

   template(Boolean_klass,                java_lang_Boolean,              Pre) \

   template(Character_klass,              java_lang_Character,            Pre) \

   template(Float_klass,                  java_lang_Float,                Pre) \

   template(Double_klass,                 java_lang_Double,               Pre) \

   template(Byte_klass,                   java_lang_Byte,                 Pre) \

   template(Short_klass,                  java_lang_Short,                Pre) \

   template(Integer_klass,                java_lang_Integer,              Pre) \

   template(Long_klass,                   java_lang_Long,                 Pre) \

   /*end*/

 class SystemDictionary : AllStatic {

   friend class VMStructs;

   friend class CompactingPermGenGen;

   friend class SystemDictionaryHandles;

   NOT_PRODUCT(friend class instanceKlassKlass;)

  public:

   enum WKID {

     NO_WKID = 0,

     #define WK_KLASS_ENUM(name, ignore_s, ignore_o) WK_KLASS_ENUM_NAME(name),

     WK_KLASSES_DO(WK_KLASS_ENUM)

     #undef WK_KLASS_ENUM

     WKID_LIMIT,

     FIRST_WKID = NO_WKID + 1

   };

   enum InitOption {

     Pre,                        // preloaded; error if not present

     // Order is significant.  Options before this point require resolve_or_fail.

     // Options after this point will use resolve_or_null instead.

     Opt,                        // preload tried; NULL if not present

     Opt_Only_JDK14NewRef,       // preload tried; use only with NewReflection

     Opt_Only_JDK15,             // preload tried; use only with JDK1.5+

     Opt_Kernel,                 // preload tried only #ifdef KERNEL

     OPTION_LIMIT,

     CEIL_LG_OPTION_LIMIT = 4    // OPTION_LIMIT <= (1<<CEIL_LG_OPTION_LIMIT)

   };

   // Returns a class with a given class name and class loader.  Loads the

   // class if needed. If not found a NoClassDefFoundError or a

   // ClassNotFoundException is thrown, depending on the value on the

   // throw_error flag.  For most uses the throw_error argument should be set

   // to true.

   static klassOop resolve_or_fail(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS);

   // Convenient call for null loader and protection domain.

   static klassOop resolve_or_fail(symbolHandle class_name, bool throw_error, TRAPS);

 private:

   // handle error translation for resolve_or_null results

   static klassOop handle_resolution_exception(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS);

 public:

   // Returns a class with a given class name and class loader.

   // Loads the class if needed. If not found NULL is returned.

   static klassOop resolve_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);

   // Version with null loader and protection domain

   static klassOop resolve_or_null(symbolHandle class_name, TRAPS);

   // Resolve a superclass or superinterface. Called from ClassFileParser,

   // parse_interfaces, resolve_instance_class_or_null, load_shared_class

   // "child_name" is the class whose super class or interface is being resolved.

   static klassOop resolve_super_or_fail(symbolHandle child_name,

                                         symbolHandle class_name,

                                         Handle class_loader,

                                         Handle protection_domain,

                                         bool is_superclass,

                                         TRAPS);

   // Parse new stream. This won't update the system dictionary or

   // class hierarchy, simply parse the stream. Used by JVMTI RedefineClasses.

   static klassOop parse_stream(symbolHandle class_name,

                                Handle class_loader,

                                Handle protection_domain,

                                ClassFileStream* st,

                                TRAPS) {

     KlassHandle nullHandle;

     return parse_stream(class_name, class_loader, protection_domain, st, nullHandle, NULL, THREAD);

   }

   static klassOop parse_stream(symbolHandle class_name,

                                Handle class_loader,

                                Handle protection_domain,

                                ClassFileStream* st,

                                KlassHandle host_klass,

                                GrowableArray<Handle>* cp_patches,

                                TRAPS);

   // Resolve from stream (called by jni_DefineClass and JVM_DefineClass)

   static klassOop resolve_from_stream(symbolHandle class_name, Handle class_loader,

                                       Handle protection_domain,

                                       ClassFileStream* st, bool verify, TRAPS);

   // Lookup an already loaded class. If not found NULL is returned.

   static klassOop find(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);

   // Lookup an already loaded instance or array class.

   // Do not make any queries to class loaders; consult only the cache.

   // If not found NULL is returned.

   static klassOop find_instance_or_array_klass(symbolHandle class_name,

                                                Handle class_loader,

                                                Handle protection_domain,

                                                TRAPS);

   // If the given name is known to vmSymbols, return the well-know klass:

   static klassOop find_well_known_klass(symbolOop class_name);

   // Lookup an instance or array class that has already been loaded

   // either into the given class loader, or else into another class

   // loader that is constrained (via loader constraints) to produce

   // a consistent class.  Do not take protection domains into account.

   // Do not make any queries to class loaders; consult only the cache.

   // Return NULL if the class is not found.

   //

   // This function is a strict superset of find_instance_or_array_klass.

   // This function (the unchecked version) makes a conservative prediction

   // of the result of the checked version, assuming successful lookup.

   // If both functions return non-null, they must return the same value.

   // Also, the unchecked version may sometimes be non-null where the

   // checked version is null.  This can occur in several ways:

   //   1. No query has yet been made to the class loader.

   //   2. The class loader was queried, but chose not to delegate.

   //   3. ClassLoader.checkPackageAccess rejected a proposed protection domain.

   //   4. Loading was attempted, but there was a linkage error of some sort.

   // In all of these cases, the loader constraints on this type are

   // satisfied, and it is safe for classes in the given class loader

   // to manipulate strongly-typed values of the found class, subject

   // to local linkage and access checks.

   static klassOop find_constrained_instance_or_array_klass(symbolHandle class_name,

                                                            Handle class_loader,

                                                            TRAPS);

   // Iterate over all klasses in dictionary

   //   Just the classes from defining class loaders

   static void classes_do(void f(klassOop));

   // Added for initialize_itable_for_klass to handle exceptions

   static void classes_do(void f(klassOop, TRAPS), TRAPS);

   //   All classes, and their class loaders

   static void classes_do(void f(klassOop, oop));

   //   All classes, and their class loaders

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

   static void classes_do(void f(klassOop, oop, TRAPS), TRAPS);

   // All entries in the placeholder table and their class loaders

   static void placeholders_do(void f(symbolOop, oop));

   // Iterate over all methods in all klasses in dictionary

   static void methods_do(void f(methodOop));

   // Garbage collection support

   // This method applies "blk->do_oop" to all the pointers to "system"

   // classes and loaders.

   static void always_strong_oops_do(OopClosure* blk);

   static void always_strong_classes_do(OopClosure* blk);

   // This method applies "blk->do_oop" to all the placeholders.

   static void placeholders_do(OopClosure* blk);

   // Unload (that is, break root links to) all unmarked classes and

   // loaders.  Returns "true" iff something was unloaded.

   static bool do_unloading(BoolObjectClosure* is_alive);

   // Applies "f->do_oop" to all root oops in the system dictionary.

   static void oops_do(OopClosure* f);

   // System loader lock

   static oop system_loader_lock()           { return _system_loader_lock_obj; }

 private:

   //    Traverses preloaded oops: various system classes.  These are

   //    guaranteed to be in the perm gen.

   static void preloaded_oops_do(OopClosure* f);

   static void lazily_loaded_oops_do(OopClosure* f);

 public:

   // Sharing support.

   static void reorder_dictionary();

   static void copy_buckets(char** top, char* end);

   static void copy_table(char** top, char* end);

   static void reverse();

   static void set_shared_dictionary(HashtableBucket* t, int length,

                                     int number_of_entries);

   // Printing

   static void print()                   PRODUCT_RETURN;

   static void print_class_statistics()  PRODUCT_RETURN;

   static void print_method_statistics() PRODUCT_RETURN;

   // Number of contained klasses

   // This is both fully loaded classes and classes in the process

   // of being loaded

   static int number_of_classes();

   // Monotonically increasing counter which grows as classes are

   // loaded or modifications such as hot-swapping or setting/removing

   // of breakpoints are performed

   static inline int number_of_modifications()     { assert_locked_or_safepoint(Compile_lock); return _number_of_modifications; }

   // Needed by evolution and breakpoint code

   static inline void notice_modification()        { assert_locked_or_safepoint(Compile_lock); ++_number_of_modifications;      }

   // Verification

   static void verify();

 #ifdef ASSERT

   static bool is_internal_format(symbolHandle class_name);

 #endif

   // Verify class is in dictionary

   static void verify_obj_klass_present(Handle obj,

                                        symbolHandle class_name,

                                        Handle class_loader);

   // Initialization

   static void initialize(TRAPS);

   // Fast access to commonly used classes (preloaded)

   static klassOop check_klass(klassOop k) {

     assert(k != NULL, "preloaded klass not initialized");

     return k;

   }

   static klassOop check_klass_Pre(klassOop k) { return check_klass(k); }

   static klassOop check_klass_Opt(klassOop k) { return k; }

   static klassOop check_klass_Opt_Kernel(klassOop k) { return k; } //== Opt

   static klassOop check_klass_Opt_Only_JDK15(klassOop k) {

     assert(JDK_Version::is_gte_jdk15x_version(), "JDK 1.5 only");

     return k;

   }

   static klassOop check_klass_Opt_Only_JDK14NewRef(klassOop k) {

     assert(JDK_Version::is_gte_jdk14x_version() && UseNewReflection, "JDK 1.4 only");

     // despite the optional loading, if you use this it must be present:

     return check_klass(k);

   }

   static bool initialize_wk_klass(WKID id, int init_opt, TRAPS);

   static void initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS);

   static void initialize_wk_klasses_through(WKID end_id, WKID &start_id, TRAPS) {

     int limit = (int)end_id + 1;

     initialize_wk_klasses_until((WKID) limit, start_id, THREAD);

   }

 public:

   #define WK_KLASS_DECLARE(name, ignore_symbol, option) \

     static klassOop name() { return check_klass_##option(_well_known_klasses[WK_KLASS_ENUM_NAME(name)]); }

   WK_KLASSES_DO(WK_KLASS_DECLARE);

   #undef WK_KLASS_DECLARE

   // Local definition for direct access to the private array:

   #define WK_KLASS(name) _well_known_klasses[SystemDictionary::WK_KLASS_ENUM_NAME(name)]

   static klassOop box_klass(BasicType t) {

     assert((uint)t < T_VOID+1, "range check");

     return check_klass(_box_klasses[t]);

   }

   static BasicType box_klass_type(klassOop k);  // inverse of box_klass

   // methods returning lazily loaded klasses

   // The corresponding method to load the class must be called before calling them.

   static klassOop abstract_ownable_synchronizer_klass() { return check_klass(_abstract_ownable_synchronizer_klass); }

   static void load_abstract_ownable_synchronizer_klass(TRAPS);

 private:

   // Tells whether ClassLoader.loadClassInternal is present

   static bool has_loadClassInternal()       { return _has_loadClassInternal; }

 public:

   // Tells whether ClassLoader.checkPackageAccess is present

   static bool has_checkPackageAccess()      { return _has_checkPackageAccess; }

   static bool Class_klass_loaded()          { return WK_KLASS(Class_klass) != NULL; }

   static bool Cloneable_klass_loaded()      { return WK_KLASS(Cloneable_klass) != NULL; }

   // Returns default system loader

   static oop java_system_loader();

   // Compute the default system loader

   static void compute_java_system_loader(TRAPS);

 private:

   // Mirrors for primitive classes (created eagerly)

   static oop check_mirror(oop m) {

     assert(m != NULL, "mirror not initialized");

     return m;

   }

 public:

   // Note:  java_lang_Class::primitive_type is the inverse of java_mirror

   // Check class loader constraints

   static bool add_loader_constraint(symbolHandle name, Handle loader1,

                                     Handle loader2, TRAPS);

   static char* check_signature_loaders(symbolHandle signature, Handle loader1,

                                        Handle loader2, bool is_method, TRAPS);

   // JSR 292

   // find the java.dyn.MethodHandles::invoke method for a given signature

   static methodOop find_method_handle_invoke(symbolHandle name,

                                              symbolHandle signature,

                                              KlassHandle accessing_klass,

                                              TRAPS);

   // ask Java to compute a java.dyn.MethodType object for a given signature

   static Handle    find_method_handle_type(symbolHandle signature,

                                            KlassHandle accessing_klass,

                                            bool for_invokeGeneric,

                                            bool& return_bcp_flag,

                                            TRAPS);

   // ask Java to compute a java.dyn.MethodHandle object for a given CP entry

   static Handle    link_method_handle_constant(KlassHandle caller,

                                                int ref_kind, //e.g., JVM_REF_invokeVirtual

                                                KlassHandle callee,

                                                symbolHandle name,

                                                symbolHandle signature,

                                                TRAPS);

   // ask Java to create a dynamic call site, while linking an invokedynamic op

   static Handle    make_dynamic_call_site(Handle bootstrap_method,

                                           // Callee information:

                                           symbolHandle name,

                                           methodHandle signature_invoker,

                                           Handle info,

                                           // Caller information:

                                           methodHandle caller_method,

                                           int caller_bci,

                                           TRAPS);

   // coordinate with Java about bootstrap methods

   static Handle    find_bootstrap_method(methodHandle caller_method,

                                          int caller_bci,  // N.B. must be an invokedynamic

                                          int cache_index, // must be corresponding main_entry

                                          Handle &argument_info_result, // static BSM arguments, if any

                                          TRAPS);

   // Utility for printing loader "name" as part of tracing constraints

   static const char* loader_name(oop loader) {

     return ((loader) == NULL ? "<bootloader>" :

             instanceKlass::cast((loader)->klass())->name()->as_C_string() );

   }

   // Record the error when the first attempt to resolve a reference from a constant

   // pool entry to a class fails.

   static void add_resolution_error(constantPoolHandle pool, int which, symbolHandle error);

   static symbolOop find_resolution_error(constantPoolHandle pool, int which);

  private:

   enum Constants {

     _loader_constraint_size = 107,                     // number of entries in constraint table

     _resolution_error_size  = 107,                     // number of entries in resolution error table

     _invoke_method_size     = 139,                     // number of entries in invoke method table

     _nof_buckets            = 1009                     // number of buckets in hash table

   };

   // Static variables

   // Hashtable holding loaded classes.

   static Dictionary*            _dictionary;

   // Hashtable holding placeholders for classes being loaded.

   static PlaceholderTable*       _placeholders;

   // Hashtable holding classes from the shared archive.

   static Dictionary*             _shared_dictionary;

   // Monotonically increasing counter which grows with

   // _number_of_classes as well as hot-swapping and breakpoint setting

   // and removal.

   static int                     _number_of_modifications;

   // Lock object for system class loader

   static oop                     _system_loader_lock_obj;

   // Constraints on class loaders

   static LoaderConstraintTable*  _loader_constraints;

   // Resolution errors

   static ResolutionErrorTable*   _resolution_errors;

   // Invoke methods (JSR 292)

   static SymbolPropertyTable*    _invoke_method_table;

 public:

   // for VM_CounterDecay iteration support

   friend class CounterDecay;

   static klassOop try_get_next_class();

 private:

   static void validate_protection_domain(instanceKlassHandle klass,

                                          Handle class_loader,

                                          Handle protection_domain, TRAPS);

   friend class VM_PopulateDumpSharedSpace;

   friend class TraversePlaceholdersClosure;

   static Dictionary*         dictionary() { return _dictionary; }

   static Dictionary*         shared_dictionary() { return _shared_dictionary; }

   static PlaceholderTable*   placeholders() { return _placeholders; }

   static LoaderConstraintTable* constraints() { return _loader_constraints; }

   static ResolutionErrorTable* resolution_errors() { return _resolution_errors; }

   static SymbolPropertyTable* invoke_method_table() { return _invoke_method_table; }

   // Basic loading operations

   static klassOop resolve_instance_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);

   static klassOop resolve_array_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);

   static instanceKlassHandle handle_parallel_super_load(symbolHandle class_name, symbolHandle supername, Handle class_loader, Handle protection_domain, Handle lockObject, TRAPS);

   // Wait on SystemDictionary_lock; unlocks lockObject before

   // waiting; relocks lockObject with correct recursion count

   // after waiting, but before reentering SystemDictionary_lock

   // to preserve lock order semantics.

   static void double_lock_wait(Handle lockObject, TRAPS);

   static void define_instance_class(instanceKlassHandle k, TRAPS);

   static instanceKlassHandle find_or_define_instance_class(symbolHandle class_name,

                                                 Handle class_loader,

                                                 instanceKlassHandle k, TRAPS);

   static instanceKlassHandle load_shared_class(symbolHandle class_name,

                                                Handle class_loader, TRAPS);

   static instanceKlassHandle load_shared_class(instanceKlassHandle ik,

                                                Handle class_loader, TRAPS);

   static instanceKlassHandle load_instance_class(symbolHandle class_name, Handle class_loader, TRAPS);

   static Handle compute_loader_lock_object(Handle class_loader, TRAPS);

   static void check_loader_lock_contention(Handle loader_lock, TRAPS);

   static bool is_parallelCapable(Handle class_loader);

   static bool is_parallelDefine(Handle class_loader);

   static klassOop find_shared_class(symbolHandle class_name);

   // Setup link to hierarchy

   static void add_to_hierarchy(instanceKlassHandle k, TRAPS);

 private:

   // We pass in the hashtable index so we can calculate it outside of

   // the SystemDictionary_lock.

   // Basic find on loaded classes

   static klassOop find_class(int index, unsigned int hash,

                              symbolHandle name, Handle loader);

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

   static symbolOop find_placeholder(int index, unsigned int hash,

                                     symbolHandle name, Handle loader);

   // Basic find operation of loaded classes and classes in the midst

   // of loading;  used for assertions and verification only.

   static oop find_class_or_placeholder(symbolHandle class_name,

                                        Handle class_loader);

   // Updating entry in dictionary

   // Add a completely loaded class

   static void add_klass(int index, symbolHandle class_name,

                         Handle class_loader, KlassHandle obj);

   // Add a placeholder for a class being loaded

   static void add_placeholder(int index,

                               symbolHandle class_name,

                               Handle class_loader);

   static void remove_placeholder(int index,

                                  symbolHandle class_name,

                                  Handle class_loader);

   // Performs cleanups after resolve_super_or_fail. This typically needs

   // to be called on failure.

   // Won't throw, but can block.

   static void resolution_cleanups(symbolHandle class_name,

                                   Handle class_loader,

                                   TRAPS);

   // Initialization

   static void initialize_preloaded_classes(TRAPS);

   // Class loader constraints

   static void check_constraints(int index, unsigned int hash,

                                 instanceKlassHandle k, Handle loader,

                                 bool defining, TRAPS);

   static void update_dictionary(int d_index, unsigned int d_hash,

                                 int p_index, unsigned int p_hash,

                                 instanceKlassHandle k, Handle loader, TRAPS);

   // Variables holding commonly used klasses (preloaded)

   static klassOop _well_known_klasses[];

   // Lazily loaded klasses

   static volatile klassOop _abstract_ownable_synchronizer_klass;

   // table of box klasses (int_klass, etc.)

   static klassOop _box_klasses[T_VOID+1];

   static oop  _java_system_loader;

   static bool _has_loadClassInternal;

   static bool _has_checkPackageAccess;

 };

 // Cf. vmSymbols vs. vmSymbolHandles

 class SystemDictionaryHandles : AllStatic {

 public:

   #define WK_KLASS_HANDLE_DECLARE(name, ignore_symbol, option) \

     static KlassHandle name() { \

       SystemDictionary::name(); \

       klassOop* loc = &SystemDictionary::_well_known_klasses[SystemDictionary::WK_KLASS_ENUM_NAME(name)]; \

       return KlassHandle(loc, true); \

     }

   WK_KLASSES_DO(WK_KLASS_HANDLE_DECLARE);

   #undef WK_KLASS_HANDLE_DECLARE

   static KlassHandle box_klass(BasicType t);

 };

 #endif // SHARE_VM_CLASSFILE_SYSTEMDICTIONARY_HPP