1 /*
   2  * Copyright 1997-2008 Sun Microsystems, Inc.  All Rights Reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 // The system dictionary stores all loaded classes and maps:
  26 //
  27 //   [class name,class loader] -> class   i.e.  [symbolOop,oop] -> klassOop
  28 //
  29 // Classes are loaded lazily. The default VM class loader is
  30 // represented as NULL.
  31 
  32 // The underlying data structure is an open hash table with a fixed number
  33 // of buckets. During loading the loader object is locked, (for the VM loader
  34 // a private lock object is used). Class loading can thus be done concurrently,
  35 // but only by different loaders.
  36 //
  37 // During loading a placeholder (name, loader) is temporarily placed in
  38 // a side data structure, and is used to detect ClassCircularityErrors
  39 // and to perform verification during GC.  A GC can occur in the midst
  40 // of class loading, as we call out to Java, have to take locks, etc.
  41 //
  42 // When class loading is finished, a new entry is added to the system
  43 // dictionary and the place holder is removed. Note that the protection
  44 // domain field of the system dictionary has not yet been filled in when
  45 // the "real" system dictionary entry is created.
  46 //
  47 // Clients of this class who are interested in finding if a class has
  48 // been completely loaded -- not classes in the process of being loaded --
  49 // can read the SystemDictionary unlocked. This is safe because
  50 //    - entries are only deleted at safepoints
  51 //    - readers cannot come to a safepoint while actively examining
  52 //         an entry  (an entry cannot be deleted from under a reader)
  53 //    - entries must be fully formed before they are available to concurrent
  54 //         readers (we must ensure write ordering)
  55 //
  56 // Note that placeholders are deleted at any time, as they are removed
  57 // when a class is completely loaded. Therefore, readers as well as writers
  58 // of placeholders must hold the SystemDictionary_lock.
  59 //
  60 
  61 class Dictionary;
  62 class PlaceholderTable;
  63 class LoaderConstraintTable;
  64 class HashtableBucket;
  65 class ResolutionErrorTable;
  66 
  67 // Certain classes are preloaded, such as java.lang.Object and java.lang.String.
  68 // They are all "well-known", in the sense that no class loader is allowed
  69 // to provide a different definition.
  70 //
  71 // These klasses must all have names defined in vmSymbols.
  72 
  73 #define WK_KLASS_ENUM_NAME(kname)    kname##_knum
  74 
  75 // Each well-known class has a short klass name (like object_klass),
  76 // a vmSymbol name (like java_lang_Object), and a flag word
  77 // that makes some minor distinctions, like whether the klass
  78 // is preloaded, optional, release-specific, etc.
  79 // The order of these definitions is significant; it is the order in which
  80 // preloading is actually performed by initialize_preloaded_classes.
  81 
  82 #define WK_KLASSES_DO(template)                                               \
  83   /* well-known classes */                                                    \
  84   template(object_klass,                 java_lang_Object,               Pre) \
  85   template(string_klass,                 java_lang_String,               Pre) \
  86   template(class_klass,                  java_lang_Class,                Pre) \
  87   template(cloneable_klass,              java_lang_Cloneable,            Pre) \
  88   template(classloader_klass,            java_lang_ClassLoader,          Pre) \
  89   template(serializable_klass,           java_io_Serializable,           Pre) \
  90   template(system_klass,                 java_lang_System,               Pre) \
  91   template(throwable_klass,              java_lang_Throwable,            Pre) \
  92   template(error_klass,                  java_lang_Error,                Pre) \
  93   template(threaddeath_klass,            java_lang_ThreadDeath,          Pre) \
  94   template(exception_klass,              java_lang_Exception,            Pre) \
  95   template(runtime_exception_klass,      java_lang_RuntimeException,     Pre) \
  96   template(protectionDomain_klass,       java_security_ProtectionDomain, Pre) \
  97   template(AccessControlContext_klass,   java_security_AccessControlContext, Pre) \
  98   template(classNotFoundException_klass, java_lang_ClassNotFoundException, Pre) \
  99   template(noClassDefFoundError_klass,   java_lang_NoClassDefFoundError, Pre) \
 100   template(linkageError_klass,           java_lang_LinkageError,         Pre) \
 101   template(ClassCastException_klass,     java_lang_ClassCastException,   Pre) \
 102   template(ArrayStoreException_klass,    java_lang_ArrayStoreException,  Pre) \
 103   template(virtualMachineError_klass,    java_lang_VirtualMachineError,  Pre) \
 104   template(OutOfMemoryError_klass,       java_lang_OutOfMemoryError,     Pre) \
 105   template(StackOverflowError_klass,     java_lang_StackOverflowError,   Pre) \
 106   template(IllegalMonitorStateException_klass, java_lang_IllegalMonitorStateException, Pre) \
 107   template(reference_klass,              java_lang_ref_Reference,        Pre) \
 108                                                                               \
 109   /* Preload ref klasses and set reference types */                           \
 110   template(soft_reference_klass,         java_lang_ref_SoftReference,    Pre) \
 111   template(weak_reference_klass,         java_lang_ref_WeakReference,    Pre) \
 112   template(final_reference_klass,        java_lang_ref_FinalReference,   Pre) \
 113   template(phantom_reference_klass,      java_lang_ref_PhantomReference, Pre) \
 114   template(finalizer_klass,              java_lang_ref_Finalizer,        Pre) \
 115                                                                               \
 116   template(thread_klass,                 java_lang_Thread,               Pre) \
 117   template(threadGroup_klass,            java_lang_ThreadGroup,          Pre) \
 118   template(properties_klass,             java_util_Properties,           Pre) \
 119   template(reflect_accessible_object_klass, java_lang_reflect_AccessibleObject, Pre) \
 120   template(reflect_field_klass,          java_lang_reflect_Field,        Pre) \
 121   template(reflect_method_klass,         java_lang_reflect_Method,       Pre) \
 122   template(reflect_constructor_klass,    java_lang_reflect_Constructor,  Pre) \
 123                                                                               \
 124   /* NOTE: needed too early in bootstrapping process to have checks based on JDK version */ \
 125   /* Universe::is_gte_jdk14x_version() is not set up by this point. */        \
 126   /* It's okay if this turns out to be NULL in non-1.4 JDKs. */               \
 127   template(reflect_magic_klass,          sun_reflect_MagicAccessorImpl,  Opt) \
 128   template(reflect_method_accessor_klass, sun_reflect_MethodAccessorImpl, Opt_Only_JDK14NewRef) \
 129   template(reflect_constructor_accessor_klass, sun_reflect_ConstructorAccessorImpl, Opt_Only_JDK14NewRef) \
 130   template(reflect_delegating_classloader_klass, sun_reflect_DelegatingClassLoader, Opt) \
 131   template(reflect_constant_pool_klass,  sun_reflect_ConstantPool,       Opt_Only_JDK15) \
 132   template(reflect_unsafe_static_field_accessor_impl_klass, sun_reflect_UnsafeStaticFieldAccessorImpl, Opt_Only_JDK15) \
 133                                                                               \
 134   template(vector_klass,                 java_util_Vector,               Pre) \
 135   template(hashtable_klass,              java_util_Hashtable,            Pre) \
 136   template(stringBuffer_klass,           java_lang_StringBuffer,         Pre) \
 137                                                                               \
 138   /* It's NULL in non-1.4 JDKs. */                                            \
 139   template(stackTraceElement_klass,      java_lang_StackTraceElement,    Opt) \
 140   /* Universe::is_gte_jdk14x_version() is not set up by this point. */        \
 141   /* It's okay if this turns out to be NULL in non-1.4 JDKs. */               \
 142   template(java_nio_Buffer_klass,        java_nio_Buffer,                Opt) \
 143                                                                               \
 144   /* If this class isn't present, it won't be referenced. */                  \
 145   template(sun_misc_AtomicLongCSImpl_klass, sun_misc_AtomicLongCSImpl,   Opt) \
 146                                                                               \
 147   template(sun_jkernel_DownloadManager_klass, sun_jkernel_DownloadManager, Opt_Kernel) \
 148                                                                               \
 149   /* Preload boxing klasses */                                                \
 150   template(boolean_klass,                java_lang_Boolean,              Pre) \
 151   template(char_klass,                   java_lang_Character,            Pre) \
 152   template(float_klass,                  java_lang_Float,                Pre) \
 153   template(double_klass,                 java_lang_Double,               Pre) \
 154   template(byte_klass,                   java_lang_Byte,                 Pre) \
 155   template(short_klass,                  java_lang_Short,                Pre) \
 156   template(int_klass,                    java_lang_Integer,              Pre) \
 157   template(long_klass,                   java_lang_Long,                 Pre) \
 158   /*end*/
 159 
 160 
 161 class SystemDictionary : AllStatic {
 162   friend class VMStructs;
 163   friend class CompactingPermGenGen;
 164   NOT_PRODUCT(friend class instanceKlassKlass;)
 165 
 166  public:
 167   enum WKID {
 168     NO_WKID = 0,
 169 
 170     #define WK_KLASS_ENUM(name, ignore_s, ignore_o) WK_KLASS_ENUM_NAME(name),
 171     WK_KLASSES_DO(WK_KLASS_ENUM)
 172     #undef WK_KLASS_ENUM
 173 
 174     WKID_LIMIT,
 175 
 176     FIRST_WKID = NO_WKID + 1
 177   };
 178 
 179   enum InitOption {
 180     Pre,                        // preloaded; error if not present
 181 
 182     // Order is significant.  Options before this point require resolve_or_fail.
 183     // Options after this point will use resolve_or_null instead.
 184 
 185     Opt,                        // preload tried; NULL if not present
 186     Opt_Only_JDK14NewRef,       // preload tried; use only with NewReflection
 187     Opt_Only_JDK15,             // preload tried; use only with JDK1.5+
 188     Opt_Kernel,                 // preload tried only #ifdef KERNEL
 189     OPTION_LIMIT,
 190     CEIL_LG_OPTION_LIMIT = 4    // OPTION_LIMIT <= (1<<CEIL_LG_OPTION_LIMIT)
 191   };
 192 
 193 
 194   // Returns a class with a given class name and class loader.  Loads the
 195   // class if needed. If not found a NoClassDefFoundError or a
 196   // ClassNotFoundException is thrown, depending on the value on the
 197   // throw_error flag.  For most uses the throw_error argument should be set
 198   // to true.
 199 
 200   static klassOop resolve_or_fail(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS);
 201   // Convenient call for null loader and protection domain.
 202   static klassOop resolve_or_fail(symbolHandle class_name, bool throw_error, TRAPS);
 203 private:
 204   // handle error translation for resolve_or_null results
 205   static klassOop handle_resolution_exception(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS);
 206 
 207 public:
 208 
 209   // Returns a class with a given class name and class loader.
 210   // Loads the class if needed. If not found NULL is returned.
 211   static klassOop resolve_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
 212   // Version with null loader and protection domain
 213   static klassOop resolve_or_null(symbolHandle class_name, TRAPS);
 214 
 215   // Resolve a superclass or superinterface. Called from ClassFileParser,
 216   // parse_interfaces, resolve_instance_class_or_null, load_shared_class
 217   // "child_name" is the class whose super class or interface is being resolved.
 218   static klassOop resolve_super_or_fail(symbolHandle child_name,
 219                                         symbolHandle class_name,
 220                                         Handle class_loader,
 221                                         Handle protection_domain,
 222                                         bool is_superclass,
 223                                         TRAPS);
 224 
 225   // Parse new stream. This won't update the system dictionary or
 226   // class hierarchy, simply parse the stream. Used by JVMTI RedefineClasses.
 227   static klassOop parse_stream(symbolHandle class_name,
 228                                Handle class_loader,
 229                                Handle protection_domain,
 230                                ClassFileStream* st,
 231                                TRAPS) {
 232     KlassHandle nullHandle;
 233     return parse_stream(class_name, class_loader, protection_domain, st, nullHandle, NULL, THREAD);
 234   }
 235   static klassOop parse_stream(symbolHandle class_name,
 236                                Handle class_loader,
 237                                Handle protection_domain,
 238                                ClassFileStream* st,
 239                                KlassHandle host_klass,
 240                                GrowableArray<Handle>* cp_patches,
 241                                TRAPS);
 242 
 243   // Resolve from stream (called by jni_DefineClass and JVM_DefineClass)
 244   static klassOop resolve_from_stream(symbolHandle class_name, Handle class_loader, Handle protection_domain, ClassFileStream* st, TRAPS);
 245 
 246   // Lookup an already loaded class. If not found NULL is returned.
 247   static klassOop find(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
 248 
 249   // Lookup an already loaded instance or array class.
 250   // Do not make any queries to class loaders; consult only the cache.
 251   // If not found NULL is returned.
 252   static klassOop find_instance_or_array_klass(symbolHandle class_name,
 253                                                Handle class_loader,
 254                                                Handle protection_domain,
 255                                                TRAPS);
 256 
 257   // If the given name is known to vmSymbols, return the well-know klass:
 258   static klassOop find_well_known_klass(symbolOop class_name);
 259 
 260   // Lookup an instance or array class that has already been loaded
 261   // either into the given class loader, or else into another class
 262   // loader that is constrained (via loader constraints) to produce
 263   // a consistent class.  Do not take protection domains into account.
 264   // Do not make any queries to class loaders; consult only the cache.
 265   // Return NULL if the class is not found.
 266   //
 267   // This function is a strict superset of find_instance_or_array_klass.
 268   // This function (the unchecked version) makes a conservative prediction
 269   // of the result of the checked version, assuming successful lookup.
 270   // If both functions return non-null, they must return the same value.
 271   // Also, the unchecked version may sometimes be non-null where the
 272   // checked version is null.  This can occur in several ways:
 273   //   1. No query has yet been made to the class loader.
 274   //   2. The class loader was queried, but chose not to delegate.
 275   //   3. ClassLoader.checkPackageAccess rejected a proposed protection domain.
 276   //   4. Loading was attempted, but there was a linkage error of some sort.
 277   // In all of these cases, the loader constraints on this type are
 278   // satisfied, and it is safe for classes in the given class loader
 279   // to manipulate strongly-typed values of the found class, subject
 280   // to local linkage and access checks.
 281   static klassOop find_constrained_instance_or_array_klass(symbolHandle class_name,
 282                                                            Handle class_loader,
 283                                                            TRAPS);
 284 
 285   // Iterate over all klasses in dictionary
 286   //   Just the classes from defining class loaders
 287   static void classes_do(void f(klassOop));
 288   // Added for initialize_itable_for_klass to handle exceptions
 289   static void classes_do(void f(klassOop, TRAPS), TRAPS);
 290   //   All classes, and their class loaders
 291   static void classes_do(void f(klassOop, oop));
 292   //   All classes, and their class loaders
 293   //   (added for helpers that use HandleMarks and ResourceMarks)
 294   static void classes_do(void f(klassOop, oop, TRAPS), TRAPS);
 295   // All entries in the placeholder table and their class loaders
 296   static void placeholders_do(void f(symbolOop, oop));
 297 
 298   // Iterate over all methods in all klasses in dictionary
 299   static void methods_do(void f(methodOop));
 300 
 301   // Garbage collection support
 302 
 303   // This method applies "blk->do_oop" to all the pointers to "system"
 304   // classes and loaders.
 305   static void always_strong_oops_do(OopClosure* blk);
 306   static void always_strong_classes_do(OopClosure* blk);
 307   // This method applies "blk->do_oop" to all the placeholders.
 308   static void placeholders_do(OopClosure* blk);
 309 
 310   // Unload (that is, break root links to) all unmarked classes and
 311   // loaders.  Returns "true" iff something was unloaded.
 312   static bool do_unloading(BoolObjectClosure* is_alive);
 313 
 314   // Applies "f->do_oop" to all root oops in the system dictionary.
 315   static void oops_do(OopClosure* f);
 316 
 317   // System loader lock
 318   static oop system_loader_lock()           { return _system_loader_lock_obj; }
 319 
 320 private:
 321   //    Traverses preloaded oops: various system classes.  These are
 322   //    guaranteed to be in the perm gen.
 323   static void preloaded_oops_do(OopClosure* f);
 324   static void lazily_loaded_oops_do(OopClosure* f);
 325 
 326 public:
 327   // Sharing support.
 328   static void reorder_dictionary();
 329   static void copy_buckets(char** top, char* end);
 330   static void copy_table(char** top, char* end);
 331   static void reverse();
 332   static void set_shared_dictionary(HashtableBucket* t, int length,
 333                                     int number_of_entries);
 334   // Printing
 335   static void print()                   PRODUCT_RETURN;
 336   static void print_class_statistics()  PRODUCT_RETURN;
 337   static void print_method_statistics() PRODUCT_RETURN;
 338 
 339   // Number of contained klasses
 340   // This is both fully loaded classes and classes in the process
 341   // of being loaded
 342   static int number_of_classes();
 343 
 344   // Monotonically increasing counter which grows as classes are
 345   // loaded or modifications such as hot-swapping or setting/removing
 346   // of breakpoints are performed
 347   static inline int number_of_modifications()     { assert_locked_or_safepoint(Compile_lock); return _number_of_modifications; }
 348   // Needed by evolution and breakpoint code
 349   static inline void notice_modification()        { assert_locked_or_safepoint(Compile_lock); ++_number_of_modifications;      }
 350 
 351   // Verification
 352   static void verify();
 353 
 354 #ifdef ASSERT
 355   static bool is_internal_format(symbolHandle class_name);
 356 #endif
 357 
 358   // Verify class is in dictionary
 359   static void verify_obj_klass_present(Handle obj,
 360                                        symbolHandle class_name,
 361                                        Handle class_loader);
 362 
 363   // Initialization
 364   static void initialize(TRAPS);
 365 
 366   // Fast access to commonly used classes (preloaded)
 367   static klassOop check_klass(klassOop k) {
 368     assert(k != NULL, "preloaded klass not initialized");
 369     return k;
 370   }
 371 
 372   static klassOop check_klass_Pre(klassOop k) { return check_klass(k); }
 373   static klassOop check_klass_Opt(klassOop k) { return k; }
 374   static klassOop check_klass_Opt_Kernel(klassOop k) { return k; } //== Opt
 375   static klassOop check_klass_Opt_Only_JDK15(klassOop k) {
 376     assert(JDK_Version::is_gte_jdk15x_version(), "JDK 1.5 only");
 377     return k;
 378   }
 379   static klassOop check_klass_Opt_Only_JDK14NewRef(klassOop k) {
 380     assert(JDK_Version::is_gte_jdk14x_version() && UseNewReflection, "JDK 1.4 only");
 381     // despite the optional loading, if you use this it must be present:
 382     return check_klass(k);
 383   }
 384 
 385   static bool initialize_wk_klass(WKID id, int init_opt, TRAPS);
 386   static void initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS);
 387   static void initialize_wk_klasses_through(WKID end_id, WKID &start_id, TRAPS) {
 388     int limit = (int)end_id + 1;
 389     initialize_wk_klasses_until((WKID) limit, start_id, THREAD);
 390   }
 391 
 392 public:
 393   #define WK_KLASS_DECLARE(name, ignore_symbol, option) \
 394     static klassOop name() { return check_klass_##option(_well_known_klasses[WK_KLASS_ENUM_NAME(name)]); }
 395   WK_KLASSES_DO(WK_KLASS_DECLARE);
 396   #undef WK_KLASS_DECLARE
 397 
 398   // Local definition for direct access to the private array:
 399   #define WK_KLASS(name) _well_known_klasses[SystemDictionary::WK_KLASS_ENUM_NAME(name)]
 400 
 401   static klassOop box_klass(BasicType t) {
 402     assert((uint)t < T_VOID+1, "range check");
 403     return check_klass(_box_klasses[t]);
 404   }
 405   static BasicType box_klass_type(klassOop k);  // inverse of box_klass
 406 
 407   // methods returning lazily loaded klasses
 408   // The corresponding method to load the class must be called before calling them.
 409   static klassOop abstract_ownable_synchronizer_klass() { return check_klass(_abstract_ownable_synchronizer_klass); }
 410 
 411   static void load_abstract_ownable_synchronizer_klass(TRAPS);
 412 
 413 private:
 414   // Tells whether ClassLoader.loadClassInternal is present
 415   static bool has_loadClassInternal()       { return _has_loadClassInternal; }
 416 
 417 public:
 418   // Tells whether ClassLoader.checkPackageAccess is present
 419   static bool has_checkPackageAccess()      { return _has_checkPackageAccess; }
 420 
 421   static bool class_klass_loaded()          { return WK_KLASS(class_klass) != NULL; }
 422   static bool cloneable_klass_loaded()      { return WK_KLASS(cloneable_klass) != NULL; }
 423 
 424   // Returns default system loader
 425   static oop java_system_loader();
 426 
 427   // Compute the default system loader
 428   static void compute_java_system_loader(TRAPS);
 429 
 430 private:
 431   // Mirrors for primitive classes (created eagerly)
 432   static oop check_mirror(oop m) {
 433     assert(m != NULL, "mirror not initialized");
 434     return m;
 435   }
 436 
 437 public:
 438   // Note:  java_lang_Class::primitive_type is the inverse of java_mirror
 439 
 440   // Check class loader constraints
 441   static bool add_loader_constraint(symbolHandle name, Handle loader1,
 442                                     Handle loader2, TRAPS);
 443   static char* check_signature_loaders(symbolHandle signature, Handle loader1,
 444                                        Handle loader2, bool is_method, TRAPS);
 445 
 446   // Utility for printing loader "name" as part of tracing constraints
 447   static const char* loader_name(oop loader) {
 448     return ((loader) == NULL ? "<bootloader>" :
 449             instanceKlass::cast((loader)->klass())->name()->as_C_string() );
 450   }
 451 
 452   // Record the error when the first attempt to resolve a reference from a constant
 453   // pool entry to a class fails.
 454   static void add_resolution_error(constantPoolHandle pool, int which, symbolHandle error);
 455   static symbolOop find_resolution_error(constantPoolHandle pool, int which);
 456 
 457  private:
 458 
 459   enum Constants {
 460     _loader_constraint_size = 107,                     // number of entries in constraint table
 461     _resolution_error_size  = 107,                     // number of entries in resolution error table
 462     _nof_buckets            = 1009                     // number of buckets in hash table
 463   };
 464 
 465 
 466   // Static variables
 467 
 468   // Hashtable holding loaded classes.
 469   static Dictionary*            _dictionary;
 470 
 471   // Hashtable holding placeholders for classes being loaded.
 472   static PlaceholderTable*       _placeholders;
 473 
 474   // Hashtable holding classes from the shared archive.
 475   static Dictionary*             _shared_dictionary;
 476 
 477   // Monotonically increasing counter which grows with
 478   // _number_of_classes as well as hot-swapping and breakpoint setting
 479   // and removal.
 480   static int                     _number_of_modifications;
 481 
 482   // Lock object for system class loader
 483   static oop                     _system_loader_lock_obj;
 484 
 485   // Constraints on class loaders
 486   static LoaderConstraintTable*  _loader_constraints;
 487 
 488   // Resolution errors
 489   static ResolutionErrorTable*   _resolution_errors;
 490 
 491 public:
 492   // for VM_CounterDecay iteration support
 493   friend class CounterDecay;
 494   static klassOop try_get_next_class();
 495 
 496 private:
 497   static void validate_protection_domain(instanceKlassHandle klass,
 498                                          Handle class_loader,
 499                                          Handle protection_domain, TRAPS);
 500 
 501   friend class VM_PopulateDumpSharedSpace;
 502   friend class TraversePlaceholdersClosure;
 503   static Dictionary*         dictionary() { return _dictionary; }
 504   static Dictionary*         shared_dictionary() { return _shared_dictionary; }
 505   static PlaceholderTable*   placeholders() { return _placeholders; }
 506   static LoaderConstraintTable* constraints() { return _loader_constraints; }
 507   static ResolutionErrorTable* resolution_errors() { return _resolution_errors; }
 508 
 509   // Basic loading operations
 510   static klassOop resolve_instance_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
 511   static klassOop resolve_array_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
 512   static instanceKlassHandle handle_parallel_super_load(symbolHandle class_name, symbolHandle supername, Handle class_loader, Handle protection_domain, Handle lockObject, TRAPS);
 513   // Wait on SystemDictionary_lock; unlocks lockObject before
 514   // waiting; relocks lockObject with correct recursion count
 515   // after waiting, but before reentering SystemDictionary_lock
 516   // to preserve lock order semantics.
 517   static void double_lock_wait(Handle lockObject, TRAPS);
 518   static void define_instance_class(instanceKlassHandle k, TRAPS);
 519   static instanceKlassHandle find_or_define_instance_class(symbolHandle class_name,
 520                                                 Handle class_loader,
 521                                                 instanceKlassHandle k, TRAPS);
 522   static instanceKlassHandle load_shared_class(symbolHandle class_name,
 523                                                Handle class_loader, TRAPS);
 524   static instanceKlassHandle load_shared_class(instanceKlassHandle ik,
 525                                                Handle class_loader, TRAPS);
 526   static instanceKlassHandle load_instance_class(symbolHandle class_name, Handle class_loader, TRAPS);
 527   static Handle compute_loader_lock_object(Handle class_loader, TRAPS);
 528   static void check_loader_lock_contention(Handle loader_lock, TRAPS);
 529 
 530   static klassOop find_shared_class(symbolHandle class_name);
 531 
 532   // Setup link to hierarchy
 533   static void add_to_hierarchy(instanceKlassHandle k, TRAPS);
 534 
 535 private:
 536   // We pass in the hashtable index so we can calculate it outside of
 537   // the SystemDictionary_lock.
 538 
 539   // Basic find on loaded classes
 540   static klassOop find_class(int index, unsigned int hash,
 541                              symbolHandle name, Handle loader);
 542 
 543   // Basic find on classes in the midst of being loaded
 544   static symbolOop find_placeholder(int index, unsigned int hash,
 545                                     symbolHandle name, Handle loader);
 546 
 547   // Basic find operation of loaded classes and classes in the midst
 548   // of loading;  used for assertions and verification only.
 549   static oop find_class_or_placeholder(symbolHandle class_name,
 550                                        Handle class_loader);
 551 
 552   // Updating entry in dictionary
 553   // Add a completely loaded class
 554   static void add_klass(int index, symbolHandle class_name,
 555                         Handle class_loader, KlassHandle obj);
 556 
 557   // Add a placeholder for a class being loaded
 558   static void add_placeholder(int index,
 559                               symbolHandle class_name,
 560                               Handle class_loader);
 561   static void remove_placeholder(int index,
 562                                  symbolHandle class_name,
 563                                  Handle class_loader);
 564 
 565   // Performs cleanups after resolve_super_or_fail. This typically needs
 566   // to be called on failure.
 567   // Won't throw, but can block.
 568   static void resolution_cleanups(symbolHandle class_name,
 569                                   Handle class_loader,
 570                                   TRAPS);
 571 
 572   // Initialization
 573   static void initialize_preloaded_classes(TRAPS);
 574 
 575   // Class loader constraints
 576   static void check_constraints(int index, unsigned int hash,
 577                                 instanceKlassHandle k, Handle loader,
 578                                 bool defining, TRAPS);
 579   static void update_dictionary(int d_index, unsigned int d_hash,
 580                                 int p_index, unsigned int p_hash,
 581                                 instanceKlassHandle k, Handle loader, TRAPS);
 582 
 583   // Variables holding commonly used klasses (preloaded)
 584   static klassOop _well_known_klasses[];
 585 
 586   // Lazily loaded klasses
 587   static volatile klassOop _abstract_ownable_synchronizer_klass;
 588 
 589   // table of box klasses (int_klass, etc.)
 590   static klassOop _box_klasses[T_VOID+1];
 591 
 592   static oop  _java_system_loader;
 593 
 594   static bool _has_loadClassInternal;
 595   static bool _has_checkPackageAccess;
 596 };