1 /*
   2  * Copyright 1997-2009 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 class SymbolPropertyTable;
  67 
  68 // Certain classes are preloaded, such as java.lang.Object and java.lang.String.
  69 // They are all "well-known", in the sense that no class loader is allowed
  70 // to provide a different definition.
  71 //
  72 // These klasses must all have names defined in vmSymbols.
  73 
  74 #define WK_KLASS_ENUM_NAME(kname)    kname##_knum
  75 
  76 // Each well-known class has a short klass name (like object_klass),
  77 // a vmSymbol name (like java_lang_Object), and a flag word
  78 // that makes some minor distinctions, like whether the klass
  79 // is preloaded, optional, release-specific, etc.
  80 // The order of these definitions is significant; it is the order in which
  81 // preloading is actually performed by initialize_preloaded_classes.
  82 
  83 #define WK_KLASSES_DO(template)                                               \
  84   /* well-known classes */                                                    \
  85   template(object_klass,                 java_lang_Object,               Pre) \
  86   template(string_klass,                 java_lang_String,               Pre) \
  87   template(class_klass,                  java_lang_Class,                Pre) \
  88   template(cloneable_klass,              java_lang_Cloneable,            Pre) \
  89   template(classloader_klass,            java_lang_ClassLoader,          Pre) \
  90   template(serializable_klass,           java_io_Serializable,           Pre) \
  91   template(system_klass,                 java_lang_System,               Pre) \
  92   template(throwable_klass,              java_lang_Throwable,            Pre) \
  93   template(error_klass,                  java_lang_Error,                Pre) \
  94   template(threaddeath_klass,            java_lang_ThreadDeath,          Pre) \
  95   template(exception_klass,              java_lang_Exception,            Pre) \
  96   template(runtime_exception_klass,      java_lang_RuntimeException,     Pre) \
  97   template(protectionDomain_klass,       java_security_ProtectionDomain, Pre) \
  98   template(AccessControlContext_klass,   java_security_AccessControlContext, Pre) \
  99   template(classNotFoundException_klass, java_lang_ClassNotFoundException, Pre) \
 100   template(noClassDefFoundError_klass,   java_lang_NoClassDefFoundError, Pre) \
 101   template(linkageError_klass,           java_lang_LinkageError,         Pre) \
 102   template(ClassCastException_klass,     java_lang_ClassCastException,   Pre) \
 103   template(ArrayStoreException_klass,    java_lang_ArrayStoreException,  Pre) \
 104   template(virtualMachineError_klass,    java_lang_VirtualMachineError,  Pre) \
 105   template(OutOfMemoryError_klass,       java_lang_OutOfMemoryError,     Pre) \
 106   template(StackOverflowError_klass,     java_lang_StackOverflowError,   Pre) \
 107   template(IllegalMonitorStateException_klass, java_lang_IllegalMonitorStateException, Pre) \
 108   template(reference_klass,              java_lang_ref_Reference,        Pre) \
 109                                                                               \
 110   /* Preload ref klasses and set reference types */                           \
 111   template(soft_reference_klass,         java_lang_ref_SoftReference,    Pre) \
 112   template(weak_reference_klass,         java_lang_ref_WeakReference,    Pre) \
 113   template(final_reference_klass,        java_lang_ref_FinalReference,   Pre) \
 114   template(phantom_reference_klass,      java_lang_ref_PhantomReference, Pre) \
 115   template(finalizer_klass,              java_lang_ref_Finalizer,        Pre) \
 116                                                                               \
 117   template(thread_klass,                 java_lang_Thread,               Pre) \
 118   template(threadGroup_klass,            java_lang_ThreadGroup,          Pre) \
 119   template(properties_klass,             java_util_Properties,           Pre) \
 120   template(reflect_accessible_object_klass, java_lang_reflect_AccessibleObject, Pre) \
 121   template(reflect_field_klass,          java_lang_reflect_Field,        Pre) \
 122   template(reflect_method_klass,         java_lang_reflect_Method,       Pre) \
 123   template(reflect_constructor_klass,    java_lang_reflect_Constructor,  Pre) \
 124                                                                               \
 125   /* NOTE: needed too early in bootstrapping process to have checks based on JDK version */ \
 126   /* Universe::is_gte_jdk14x_version() is not set up by this point. */        \
 127   /* It's okay if this turns out to be NULL in non-1.4 JDKs. */               \
 128   template(reflect_magic_klass,          sun_reflect_MagicAccessorImpl,  Opt) \
 129   template(reflect_method_accessor_klass, sun_reflect_MethodAccessorImpl, Opt_Only_JDK14NewRef) \
 130   template(reflect_constructor_accessor_klass, sun_reflect_ConstructorAccessorImpl, Opt_Only_JDK14NewRef) \
 131   template(reflect_delegating_classloader_klass, sun_reflect_DelegatingClassLoader, Opt) \
 132   template(reflect_constant_pool_klass,  sun_reflect_ConstantPool,       Opt_Only_JDK15) \
 133   template(reflect_unsafe_static_field_accessor_impl_klass, sun_reflect_UnsafeStaticFieldAccessorImpl, Opt_Only_JDK15) \
 134                                                                               \
 135   /* support for dynamic typing; it's OK if these are NULL in earlier JDKs */ \
 136   template(MethodHandle_klass,           java_dyn_MethodHandle,          Opt) \
 137   template(MemberName_klass,             sun_dyn_MemberName,             Opt) \
 138   template(MethodHandleImpl_klass,       sun_dyn_MethodHandleImpl,       Opt) \
 139   template(AdapterMethodHandle_klass,    sun_dyn_AdapterMethodHandle,    Opt) \
 140   template(BoundMethodHandle_klass,      sun_dyn_BoundMethodHandle,      Opt) \
 141   template(DirectMethodHandle_klass,     sun_dyn_DirectMethodHandle,     Opt) \
 142   template(MethodType_klass,             java_dyn_MethodType,            Opt) \
 143   template(MethodTypeForm_klass,         java_dyn_MethodTypeForm,        Opt) \
 144   template(WrongMethodTypeException_klass, java_dyn_WrongMethodTypeException, Opt) \
 145   template(Linkage_klass,                java_dyn_Linkage,               Opt) \
 146   template(CallSite_klass,               java_dyn_CallSite,              Opt) \
 147   template(InvokeDynamic_klass,          java_dyn_InvokeDynamic,         Opt) \
 148   /* Note: MethodHandle must be first, and Dynamic last in group */           \
 149                                                                               \
 150   template(vector_klass,                 java_util_Vector,               Pre) \
 151   template(hashtable_klass,              java_util_Hashtable,            Pre) \
 152   template(stringBuffer_klass,           java_lang_StringBuffer,         Pre) \
 153   template(StringBuilder_klass,          java_lang_StringBuilder,        Pre) \
 154                                                                               \
 155   /* It's NULL in non-1.4 JDKs. */                                            \
 156   template(stackTraceElement_klass,      java_lang_StackTraceElement,    Opt) \
 157   /* Universe::is_gte_jdk14x_version() is not set up by this point. */        \
 158   /* It's okay if this turns out to be NULL in non-1.4 JDKs. */               \
 159   template(java_nio_Buffer_klass,        java_nio_Buffer,                Opt) \
 160                                                                               \
 161   /* If this class isn't present, it won't be referenced. */                  \
 162   template(sun_misc_AtomicLongCSImpl_klass, sun_misc_AtomicLongCSImpl,   Opt) \
 163                                                                               \
 164   template(sun_jkernel_DownloadManager_klass, sun_jkernel_DownloadManager, Opt_Kernel) \
 165                                                                               \
 166   /* Preload boxing klasses */                                                \
 167   template(boolean_klass,                java_lang_Boolean,              Pre) \
 168   template(char_klass,                   java_lang_Character,            Pre) \
 169   template(float_klass,                  java_lang_Float,                Pre) \
 170   template(double_klass,                 java_lang_Double,               Pre) \
 171   template(byte_klass,                   java_lang_Byte,                 Pre) \
 172   template(short_klass,                  java_lang_Short,                Pre) \
 173   template(int_klass,                    java_lang_Integer,              Pre) \
 174   template(long_klass,                   java_lang_Long,                 Pre) \
 175   /*end*/
 176 
 177 
 178 class SystemDictionary : AllStatic {
 179   friend class VMStructs;
 180   friend class CompactingPermGenGen;
 181   friend class SystemDictionaryHandles;
 182   NOT_PRODUCT(friend class instanceKlassKlass;)
 183 
 184  public:
 185   enum WKID {
 186     NO_WKID = 0,
 187 
 188     #define WK_KLASS_ENUM(name, ignore_s, ignore_o) WK_KLASS_ENUM_NAME(name),
 189     WK_KLASSES_DO(WK_KLASS_ENUM)
 190     #undef WK_KLASS_ENUM
 191 
 192     WKID_LIMIT,
 193 
 194     FIRST_WKID = NO_WKID + 1
 195   };
 196 
 197   enum InitOption {
 198     Pre,                        // preloaded; error if not present
 199 
 200     // Order is significant.  Options before this point require resolve_or_fail.
 201     // Options after this point will use resolve_or_null instead.
 202 
 203     Opt,                        // preload tried; NULL if not present
 204     Opt_Only_JDK14NewRef,       // preload tried; use only with NewReflection
 205     Opt_Only_JDK15,             // preload tried; use only with JDK1.5+
 206     Opt_Kernel,                 // preload tried only #ifdef KERNEL
 207     OPTION_LIMIT,
 208     CEIL_LG_OPTION_LIMIT = 4    // OPTION_LIMIT <= (1<<CEIL_LG_OPTION_LIMIT)
 209   };
 210 
 211 
 212   // Returns a class with a given class name and class loader.  Loads the
 213   // class if needed. If not found a NoClassDefFoundError or a
 214   // ClassNotFoundException is thrown, depending on the value on the
 215   // throw_error flag.  For most uses the throw_error argument should be set
 216   // to true.
 217 
 218   static klassOop resolve_or_fail(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS);
 219   // Convenient call for null loader and protection domain.
 220   static klassOop resolve_or_fail(symbolHandle class_name, bool throw_error, TRAPS);
 221 private:
 222   // handle error translation for resolve_or_null results
 223   static klassOop handle_resolution_exception(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS);
 224 
 225 public:
 226 
 227   // Returns a class with a given class name and class loader.
 228   // Loads the class if needed. If not found NULL is returned.
 229   static klassOop resolve_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
 230   // Version with null loader and protection domain
 231   static klassOop resolve_or_null(symbolHandle class_name, TRAPS);
 232 
 233   // Resolve a superclass or superinterface. Called from ClassFileParser,
 234   // parse_interfaces, resolve_instance_class_or_null, load_shared_class
 235   // "child_name" is the class whose super class or interface is being resolved.
 236   static klassOop resolve_super_or_fail(symbolHandle child_name,
 237                                         symbolHandle class_name,
 238                                         Handle class_loader,
 239                                         Handle protection_domain,
 240                                         bool is_superclass,
 241                                         TRAPS);
 242 
 243   // Parse new stream. This won't update the system dictionary or
 244   // class hierarchy, simply parse the stream. Used by JVMTI RedefineClasses.
 245   static klassOop parse_stream(symbolHandle class_name,
 246                                Handle class_loader,
 247                                Handle protection_domain,
 248                                ClassFileStream* st,
 249                                TRAPS) {
 250     KlassHandle nullHandle;
 251     return parse_stream(class_name, class_loader, protection_domain, st, nullHandle, NULL, THREAD);
 252   }
 253   static klassOop parse_stream(symbolHandle class_name,
 254                                Handle class_loader,
 255                                Handle protection_domain,
 256                                ClassFileStream* st,
 257                                KlassHandle host_klass,
 258                                GrowableArray<Handle>* cp_patches,
 259                                TRAPS);
 260 
 261   // Resolve from stream (called by jni_DefineClass and JVM_DefineClass)
 262   static klassOop resolve_from_stream(symbolHandle class_name, Handle class_loader,
 263                                       Handle protection_domain,
 264                                       ClassFileStream* st, bool verify, TRAPS);
 265 
 266   // Lookup an already loaded class. If not found NULL is returned.
 267   static klassOop find(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
 268 
 269   // Lookup an already loaded instance or array class.
 270   // Do not make any queries to class loaders; consult only the cache.
 271   // If not found NULL is returned.
 272   static klassOop find_instance_or_array_klass(symbolHandle class_name,
 273                                                Handle class_loader,
 274                                                Handle protection_domain,
 275                                                TRAPS);
 276 
 277   // If the given name is known to vmSymbols, return the well-know klass:
 278   static klassOop find_well_known_klass(symbolOop class_name);
 279 
 280   // Lookup an instance or array class that has already been loaded
 281   // either into the given class loader, or else into another class
 282   // loader that is constrained (via loader constraints) to produce
 283   // a consistent class.  Do not take protection domains into account.
 284   // Do not make any queries to class loaders; consult only the cache.
 285   // Return NULL if the class is not found.
 286   //
 287   // This function is a strict superset of find_instance_or_array_klass.
 288   // This function (the unchecked version) makes a conservative prediction
 289   // of the result of the checked version, assuming successful lookup.
 290   // If both functions return non-null, they must return the same value.
 291   // Also, the unchecked version may sometimes be non-null where the
 292   // checked version is null.  This can occur in several ways:
 293   //   1. No query has yet been made to the class loader.
 294   //   2. The class loader was queried, but chose not to delegate.
 295   //   3. ClassLoader.checkPackageAccess rejected a proposed protection domain.
 296   //   4. Loading was attempted, but there was a linkage error of some sort.
 297   // In all of these cases, the loader constraints on this type are
 298   // satisfied, and it is safe for classes in the given class loader
 299   // to manipulate strongly-typed values of the found class, subject
 300   // to local linkage and access checks.
 301   static klassOop find_constrained_instance_or_array_klass(symbolHandle class_name,
 302                                                            Handle class_loader,
 303                                                            TRAPS);
 304 
 305   // Iterate over all klasses in dictionary
 306   //   Just the classes from defining class loaders
 307   static void classes_do(void f(klassOop));
 308   // Added for initialize_itable_for_klass to handle exceptions
 309   static void classes_do(void f(klassOop, TRAPS), TRAPS);
 310   //   All classes, and their class loaders
 311   static void classes_do(void f(klassOop, oop));
 312   //   All classes, and their class loaders
 313   //   (added for helpers that use HandleMarks and ResourceMarks)
 314   static void classes_do(void f(klassOop, oop, TRAPS), TRAPS);
 315   // All entries in the placeholder table and their class loaders
 316   static void placeholders_do(void f(symbolOop, oop));
 317 
 318   // Iterate over all methods in all klasses in dictionary
 319   static void methods_do(void f(methodOop));
 320 
 321   // Garbage collection support
 322 
 323   // This method applies "blk->do_oop" to all the pointers to "system"
 324   // classes and loaders.
 325   static void always_strong_oops_do(OopClosure* blk);
 326   static void always_strong_classes_do(OopClosure* blk);
 327   // This method applies "blk->do_oop" to all the placeholders.
 328   static void placeholders_do(OopClosure* blk);
 329 
 330   // Unload (that is, break root links to) all unmarked classes and
 331   // loaders.  Returns "true" iff something was unloaded.
 332   static bool do_unloading(BoolObjectClosure* is_alive);
 333 
 334   // Applies "f->do_oop" to all root oops in the system dictionary.
 335   static void oops_do(OopClosure* f);
 336 
 337   // System loader lock
 338   static oop system_loader_lock()           { return _system_loader_lock_obj; }
 339 
 340 private:
 341   //    Traverses preloaded oops: various system classes.  These are
 342   //    guaranteed to be in the perm gen.
 343   static void preloaded_oops_do(OopClosure* f);
 344   static void lazily_loaded_oops_do(OopClosure* f);
 345 
 346 public:
 347   // Sharing support.
 348   static void reorder_dictionary();
 349   static void copy_buckets(char** top, char* end);
 350   static void copy_table(char** top, char* end);
 351   static void reverse();
 352   static void set_shared_dictionary(HashtableBucket* t, int length,
 353                                     int number_of_entries);
 354   // Printing
 355   static void print()                   PRODUCT_RETURN;
 356   static void print_class_statistics()  PRODUCT_RETURN;
 357   static void print_method_statistics() PRODUCT_RETURN;
 358 
 359   // Number of contained klasses
 360   // This is both fully loaded classes and classes in the process
 361   // of being loaded
 362   static int number_of_classes();
 363 
 364   // Monotonically increasing counter which grows as classes are
 365   // loaded or modifications such as hot-swapping or setting/removing
 366   // of breakpoints are performed
 367   static inline int number_of_modifications()     { assert_locked_or_safepoint(Compile_lock); return _number_of_modifications; }
 368   // Needed by evolution and breakpoint code
 369   static inline void notice_modification()        { assert_locked_or_safepoint(Compile_lock); ++_number_of_modifications;      }
 370 
 371   // Verification
 372   static void verify();
 373 
 374 #ifdef ASSERT
 375   static bool is_internal_format(symbolHandle class_name);
 376 #endif
 377 
 378   // Verify class is in dictionary
 379   static void verify_obj_klass_present(Handle obj,
 380                                        symbolHandle class_name,
 381                                        Handle class_loader);
 382 
 383   // Initialization
 384   static void initialize(TRAPS);
 385 
 386   // Fast access to commonly used classes (preloaded)
 387   static klassOop check_klass(klassOop k) {
 388     assert(k != NULL, "preloaded klass not initialized");
 389     return k;
 390   }
 391 
 392   static klassOop check_klass_Pre(klassOop k) { return check_klass(k); }
 393   static klassOop check_klass_Opt(klassOop k) { return k; }
 394   static klassOop check_klass_Opt_Kernel(klassOop k) { return k; } //== Opt
 395   static klassOop check_klass_Opt_Only_JDK15(klassOop k) {
 396     assert(JDK_Version::is_gte_jdk15x_version(), "JDK 1.5 only");
 397     return k;
 398   }
 399   static klassOop check_klass_Opt_Only_JDK14NewRef(klassOop k) {
 400     assert(JDK_Version::is_gte_jdk14x_version() && UseNewReflection, "JDK 1.4 only");
 401     // despite the optional loading, if you use this it must be present:
 402     return check_klass(k);
 403   }
 404 
 405   static bool initialize_wk_klass(WKID id, int init_opt, TRAPS);
 406   static void initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS);
 407   static void initialize_wk_klasses_through(WKID end_id, WKID &start_id, TRAPS) {
 408     int limit = (int)end_id + 1;
 409     initialize_wk_klasses_until((WKID) limit, start_id, THREAD);
 410   }
 411 
 412 public:
 413   #define WK_KLASS_DECLARE(name, ignore_symbol, option) \
 414     static klassOop name() { return check_klass_##option(_well_known_klasses[WK_KLASS_ENUM_NAME(name)]); }
 415   WK_KLASSES_DO(WK_KLASS_DECLARE);
 416   #undef WK_KLASS_DECLARE
 417 
 418   // Local definition for direct access to the private array:
 419   #define WK_KLASS(name) _well_known_klasses[SystemDictionary::WK_KLASS_ENUM_NAME(name)]
 420 
 421   static klassOop box_klass(BasicType t) {
 422     assert((uint)t < T_VOID+1, "range check");
 423     return check_klass(_box_klasses[t]);
 424   }
 425   static BasicType box_klass_type(klassOop k);  // inverse of box_klass
 426 
 427   // methods returning lazily loaded klasses
 428   // The corresponding method to load the class must be called before calling them.
 429   static klassOop abstract_ownable_synchronizer_klass() { return check_klass(_abstract_ownable_synchronizer_klass); }
 430 
 431   static void load_abstract_ownable_synchronizer_klass(TRAPS);
 432 
 433 private:
 434   // Tells whether ClassLoader.loadClassInternal is present
 435   static bool has_loadClassInternal()       { return _has_loadClassInternal; }
 436 
 437 public:
 438   // Tells whether ClassLoader.checkPackageAccess is present
 439   static bool has_checkPackageAccess()      { return _has_checkPackageAccess; }
 440 
 441   static bool class_klass_loaded()          { return WK_KLASS(class_klass) != NULL; }
 442   static bool cloneable_klass_loaded()      { return WK_KLASS(cloneable_klass) != NULL; }
 443 
 444   // Returns default system loader
 445   static oop java_system_loader();
 446 
 447   // Compute the default system loader
 448   static void compute_java_system_loader(TRAPS);
 449 
 450 private:
 451   // Mirrors for primitive classes (created eagerly)
 452   static oop check_mirror(oop m) {
 453     assert(m != NULL, "mirror not initialized");
 454     return m;
 455   }
 456 
 457 public:
 458   // Note:  java_lang_Class::primitive_type is the inverse of java_mirror
 459 
 460   // Check class loader constraints
 461   static bool add_loader_constraint(symbolHandle name, Handle loader1,
 462                                     Handle loader2, TRAPS);
 463   static char* check_signature_loaders(symbolHandle signature, Handle loader1,
 464                                        Handle loader2, bool is_method, TRAPS);
 465 
 466   // JSR 292
 467   // find the java.dyn.MethodHandles::invoke method for a given signature
 468   static methodOop find_method_handle_invoke(symbolHandle signature,
 469                                              Handle class_loader,
 470                                              Handle protection_domain,
 471                                              TRAPS);
 472   // ask Java to compute the java.dyn.MethodType object for a given signature
 473   static Handle    compute_method_handle_type(symbolHandle signature,
 474                                               Handle class_loader,
 475                                               Handle protection_domain,
 476                                               TRAPS);
 477   // ask Java to create a dynamic call site, while linking an invokedynamic op
 478   static Handle    make_dynamic_call_site(KlassHandle caller,
 479                                           int caller_method_idnum,
 480                                           int caller_bci,
 481                                           symbolHandle name,
 482                                           methodHandle mh_invoke,
 483                                           TRAPS);
 484 
 485   // coordinate with Java about bootstrap methods
 486   static Handle    find_bootstrap_method(KlassHandle caller,
 487                                          // This argument is non-null only when a
 488                                          // classfile attribute has been found:
 489                                          KlassHandle search_bootstrap_klass,
 490                                          TRAPS);
 491 
 492   // Utility for printing loader "name" as part of tracing constraints
 493   static const char* loader_name(oop loader) {
 494     return ((loader) == NULL ? "<bootloader>" :
 495             instanceKlass::cast((loader)->klass())->name()->as_C_string() );
 496   }
 497 
 498   // Record the error when the first attempt to resolve a reference from a constant
 499   // pool entry to a class fails.
 500   static void add_resolution_error(constantPoolHandle pool, int which, symbolHandle error);
 501   static symbolOop find_resolution_error(constantPoolHandle pool, int which);
 502 
 503  private:
 504 
 505   enum Constants {
 506     _loader_constraint_size = 107,                     // number of entries in constraint table
 507     _resolution_error_size  = 107,                     // number of entries in resolution error table
 508     _invoke_method_size     = 139,                     // number of entries in invoke method table
 509     _nof_buckets            = 1009                     // number of buckets in hash table
 510   };
 511 
 512 
 513   // Static variables
 514 
 515   // Hashtable holding loaded classes.
 516   static Dictionary*            _dictionary;
 517 
 518   // Hashtable holding placeholders for classes being loaded.
 519   static PlaceholderTable*       _placeholders;
 520 
 521   // Hashtable holding classes from the shared archive.
 522   static Dictionary*             _shared_dictionary;
 523 
 524   // Monotonically increasing counter which grows with
 525   // _number_of_classes as well as hot-swapping and breakpoint setting
 526   // and removal.
 527   static int                     _number_of_modifications;
 528 
 529   // Lock object for system class loader
 530   static oop                     _system_loader_lock_obj;
 531 
 532   // Constraints on class loaders
 533   static LoaderConstraintTable*  _loader_constraints;
 534 
 535   // Resolution errors
 536   static ResolutionErrorTable*   _resolution_errors;
 537 
 538   // Invoke methods (JSR 292)
 539   static SymbolPropertyTable*    _invoke_method_table;
 540 
 541 public:
 542   // for VM_CounterDecay iteration support
 543   friend class CounterDecay;
 544   static klassOop try_get_next_class();
 545 
 546 private:
 547   static void validate_protection_domain(instanceKlassHandle klass,
 548                                          Handle class_loader,
 549                                          Handle protection_domain, TRAPS);
 550 
 551   friend class VM_PopulateDumpSharedSpace;
 552   friend class TraversePlaceholdersClosure;
 553   static Dictionary*         dictionary() { return _dictionary; }
 554   static Dictionary*         shared_dictionary() { return _shared_dictionary; }
 555   static PlaceholderTable*   placeholders() { return _placeholders; }
 556   static LoaderConstraintTable* constraints() { return _loader_constraints; }
 557   static ResolutionErrorTable* resolution_errors() { return _resolution_errors; }
 558   static SymbolPropertyTable* invoke_method_table() { return _invoke_method_table; }
 559 
 560   // Basic loading operations
 561   static klassOop resolve_instance_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
 562   static klassOop resolve_array_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
 563   static instanceKlassHandle handle_parallel_super_load(symbolHandle class_name, symbolHandle supername, Handle class_loader, Handle protection_domain, Handle lockObject, TRAPS);
 564   // Wait on SystemDictionary_lock; unlocks lockObject before
 565   // waiting; relocks lockObject with correct recursion count
 566   // after waiting, but before reentering SystemDictionary_lock
 567   // to preserve lock order semantics.
 568   static void double_lock_wait(Handle lockObject, TRAPS);
 569   static void define_instance_class(instanceKlassHandle k, TRAPS);
 570   static instanceKlassHandle find_or_define_instance_class(symbolHandle class_name,
 571                                                 Handle class_loader,
 572                                                 instanceKlassHandle k, TRAPS);
 573   static instanceKlassHandle load_shared_class(symbolHandle class_name,
 574                                                Handle class_loader, TRAPS);
 575   static instanceKlassHandle load_shared_class(instanceKlassHandle ik,
 576                                                Handle class_loader, TRAPS);
 577   static instanceKlassHandle load_instance_class(symbolHandle class_name, Handle class_loader, TRAPS);
 578   static Handle compute_loader_lock_object(Handle class_loader, TRAPS);
 579   static void check_loader_lock_contention(Handle loader_lock, TRAPS);
 580   static bool is_parallelCapable(Handle class_loader);
 581   static bool is_parallelDefine(Handle class_loader);
 582 
 583   static klassOop find_shared_class(symbolHandle class_name);
 584 
 585   // Setup link to hierarchy
 586   static void add_to_hierarchy(instanceKlassHandle k, TRAPS);
 587 
 588 private:
 589   // We pass in the hashtable index so we can calculate it outside of
 590   // the SystemDictionary_lock.
 591 
 592   // Basic find on loaded classes
 593   static klassOop find_class(int index, unsigned int hash,
 594                              symbolHandle name, Handle loader);
 595 
 596   // Basic find on classes in the midst of being loaded
 597   static symbolOop find_placeholder(int index, unsigned int hash,
 598                                     symbolHandle name, Handle loader);
 599 
 600   // Basic find operation of loaded classes and classes in the midst
 601   // of loading;  used for assertions and verification only.
 602   static oop find_class_or_placeholder(symbolHandle class_name,
 603                                        Handle class_loader);
 604 
 605   // Updating entry in dictionary
 606   // Add a completely loaded class
 607   static void add_klass(int index, symbolHandle class_name,
 608                         Handle class_loader, KlassHandle obj);
 609 
 610   // Add a placeholder for a class being loaded
 611   static void add_placeholder(int index,
 612                               symbolHandle class_name,
 613                               Handle class_loader);
 614   static void remove_placeholder(int index,
 615                                  symbolHandle class_name,
 616                                  Handle class_loader);
 617 
 618   // Performs cleanups after resolve_super_or_fail. This typically needs
 619   // to be called on failure.
 620   // Won't throw, but can block.
 621   static void resolution_cleanups(symbolHandle class_name,
 622                                   Handle class_loader,
 623                                   TRAPS);
 624 
 625   // Initialization
 626   static void initialize_preloaded_classes(TRAPS);
 627 
 628   // Class loader constraints
 629   static void check_constraints(int index, unsigned int hash,
 630                                 instanceKlassHandle k, Handle loader,
 631                                 bool defining, TRAPS);
 632   static void update_dictionary(int d_index, unsigned int d_hash,
 633                                 int p_index, unsigned int p_hash,
 634                                 instanceKlassHandle k, Handle loader, TRAPS);
 635 
 636   // Variables holding commonly used klasses (preloaded)
 637   static klassOop _well_known_klasses[];
 638 
 639   // Lazily loaded klasses
 640   static volatile klassOop _abstract_ownable_synchronizer_klass;
 641 
 642   // table of box klasses (int_klass, etc.)
 643   static klassOop _box_klasses[T_VOID+1];
 644 
 645   static oop  _java_system_loader;
 646 
 647   static bool _has_loadClassInternal;
 648   static bool _has_checkPackageAccess;
 649 };
 650 
 651 // Cf. vmSymbols vs. vmSymbolHandles
 652 class SystemDictionaryHandles : AllStatic {
 653 public:
 654   #define WK_KLASS_HANDLE_DECLARE(name, ignore_symbol, option) \
 655     static KlassHandle name() { \
 656       SystemDictionary::name(); \
 657       klassOop* loc = &SystemDictionary::_well_known_klasses[SystemDictionary::WK_KLASS_ENUM_NAME(name)]; \
 658       return KlassHandle(loc, true); \
 659     }
 660   WK_KLASSES_DO(WK_KLASS_HANDLE_DECLARE);
 661   #undef WK_KLASS_HANDLE_DECLARE
 662 
 663   static KlassHandle box_klass(BasicType t);
 664 };