/*

 * 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.

 *

 */

// 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) \

  template(InvokeDynamic_klass,          java_dyn_InvokeDynamic,         Opt) \

  /* Note: MethodHandle must be first, and InvokeDynamic 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& return_bcp_flag,

                                           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(KlassHandle caller, 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: