systemDictionary.hpp revision 1472:c18cbe5936b8
1/* 2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * 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 61class Dictionary; 62class PlaceholderTable; 63class LoaderConstraintTable; 64class HashtableBucket; 65class ResolutionErrorTable; 66class 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(RuntimeException_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(SoftReference_klass, java_lang_ref_SoftReference, Pre) \ 112 template(WeakReference_klass, java_lang_ref_WeakReference, Pre) \ 113 template(FinalReference_klass, java_lang_ref_FinalReference, Pre) \ 114 template(PhantomReference_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_AccessibleObject_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_MagicAccessorImpl_klass, sun_reflect_MagicAccessorImpl, Opt) \ 129 template(reflect_MethodAccessorImpl_klass, sun_reflect_MethodAccessorImpl, Opt_Only_JDK14NewRef) \ 130 template(reflect_ConstructorAccessorImpl_klass, sun_reflect_ConstructorAccessorImpl, Opt_Only_JDK14NewRef) \ 131 template(reflect_DelegatingClassLoader_klass, sun_reflect_DelegatingClassLoader, Opt) \ 132 template(reflect_ConstantPool_klass, sun_reflect_ConstantPool, Opt_Only_JDK15) \ 133 template(reflect_UnsafeStaticFieldAccessorImpl_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(MethodHandleNatives_klass, sun_dyn_MethodHandleNatives, Opt) \ 140 template(AdapterMethodHandle_klass, sun_dyn_AdapterMethodHandle, Opt) \ 141 template(BoundMethodHandle_klass, sun_dyn_BoundMethodHandle, Opt) \ 142 template(DirectMethodHandle_klass, sun_dyn_DirectMethodHandle, Opt) \ 143 template(MethodType_klass, java_dyn_MethodType, Opt) \ 144 template(MethodTypeForm_klass, java_dyn_MethodTypeForm, Opt) \ 145 template(WrongMethodTypeException_klass, java_dyn_WrongMethodTypeException, Opt) \ 146 template(Linkage_klass, java_dyn_Linkage, Opt) \ 147 template(CallSite_klass, java_dyn_CallSite, Opt) \ 148 template(InvokeDynamic_klass, java_dyn_InvokeDynamic, Opt) \ 149 /* Note: MethodHandle must be first, and InvokeDynamic last in group */ \ 150 \ 151 template(StringBuffer_klass, java_lang_StringBuffer, Pre) \ 152 template(StringBuilder_klass, java_lang_StringBuilder, Pre) \ 153 \ 154 /* It's NULL in non-1.4 JDKs. */ \ 155 template(StackTraceElement_klass, java_lang_StackTraceElement, Opt) \ 156 /* Universe::is_gte_jdk14x_version() is not set up by this point. */ \ 157 /* It's okay if this turns out to be NULL in non-1.4 JDKs. */ \ 158 template(java_nio_Buffer_klass, java_nio_Buffer, Opt) \ 159 \ 160 /* If this class isn't present, it won't be referenced. */ \ 161 template(sun_misc_AtomicLongCSImpl_klass, sun_misc_AtomicLongCSImpl, Opt) \ 162 \ 163 template(sun_jkernel_DownloadManager_klass, sun_jkernel_DownloadManager, Opt_Kernel) \ 164 \ 165 /* Preload boxing klasses */ \ 166 template(Boolean_klass, java_lang_Boolean, Pre) \ 167 template(Character_klass, java_lang_Character, Pre) \ 168 template(Float_klass, java_lang_Float, Pre) \ 169 template(Double_klass, java_lang_Double, Pre) \ 170 template(Byte_klass, java_lang_Byte, Pre) \ 171 template(Short_klass, java_lang_Short, Pre) \ 172 template(Integer_klass, java_lang_Integer, Pre) \ 173 template(Long_klass, java_lang_Long, Pre) \ 174 /*end*/ 175 176 177class SystemDictionary : AllStatic { 178 friend class VMStructs; 179 friend class CompactingPermGenGen; 180 friend class SystemDictionaryHandles; 181 NOT_PRODUCT(friend class instanceKlassKlass;) 182 183 public: 184 enum WKID { 185 NO_WKID = 0, 186 187 #define WK_KLASS_ENUM(name, ignore_s, ignore_o) WK_KLASS_ENUM_NAME(name), 188 WK_KLASSES_DO(WK_KLASS_ENUM) 189 #undef WK_KLASS_ENUM 190 191 WKID_LIMIT, 192 193 FIRST_WKID = NO_WKID + 1 194 }; 195 196 enum InitOption { 197 Pre, // preloaded; error if not present 198 199 // Order is significant. Options before this point require resolve_or_fail. 200 // Options after this point will use resolve_or_null instead. 201 202 Opt, // preload tried; NULL if not present 203 Opt_Only_JDK14NewRef, // preload tried; use only with NewReflection 204 Opt_Only_JDK15, // preload tried; use only with JDK1.5+ 205 Opt_Kernel, // preload tried only #ifdef KERNEL 206 OPTION_LIMIT, 207 CEIL_LG_OPTION_LIMIT = 4 // OPTION_LIMIT <= (1<<CEIL_LG_OPTION_LIMIT) 208 }; 209 210 211 // Returns a class with a given class name and class loader. Loads the 212 // class if needed. If not found a NoClassDefFoundError or a 213 // ClassNotFoundException is thrown, depending on the value on the 214 // throw_error flag. For most uses the throw_error argument should be set 215 // to true. 216 217 static klassOop resolve_or_fail(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS); 218 // Convenient call for null loader and protection domain. 219 static klassOop resolve_or_fail(symbolHandle class_name, bool throw_error, TRAPS); 220private: 221 // handle error translation for resolve_or_null results 222 static klassOop handle_resolution_exception(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS); 223 224public: 225 226 // Returns a class with a given class name and class loader. 227 // Loads the class if needed. If not found NULL is returned. 228 static klassOop resolve_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS); 229 // Version with null loader and protection domain 230 static klassOop resolve_or_null(symbolHandle class_name, TRAPS); 231 232 // Resolve a superclass or superinterface. Called from ClassFileParser, 233 // parse_interfaces, resolve_instance_class_or_null, load_shared_class 234 // "child_name" is the class whose super class or interface is being resolved. 235 static klassOop resolve_super_or_fail(symbolHandle child_name, 236 symbolHandle class_name, 237 Handle class_loader, 238 Handle protection_domain, 239 bool is_superclass, 240 TRAPS); 241 242 // Parse new stream. This won't update the system dictionary or 243 // class hierarchy, simply parse the stream. Used by JVMTI RedefineClasses. 244 static klassOop parse_stream(symbolHandle class_name, 245 Handle class_loader, 246 Handle protection_domain, 247 ClassFileStream* st, 248 TRAPS) { 249 KlassHandle nullHandle; 250 return parse_stream(class_name, class_loader, protection_domain, st, nullHandle, NULL, THREAD); 251 } 252 static klassOop parse_stream(symbolHandle class_name, 253 Handle class_loader, 254 Handle protection_domain, 255 ClassFileStream* st, 256 KlassHandle host_klass, 257 GrowableArray<Handle>* cp_patches, 258 TRAPS); 259 260 // Resolve from stream (called by jni_DefineClass and JVM_DefineClass) 261 static klassOop resolve_from_stream(symbolHandle class_name, Handle class_loader, 262 Handle protection_domain, 263 ClassFileStream* st, bool verify, TRAPS); 264 265 // Lookup an already loaded class. If not found NULL is returned. 266 static klassOop find(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS); 267 268 // Lookup an already loaded instance or array class. 269 // Do not make any queries to class loaders; consult only the cache. 270 // If not found NULL is returned. 271 static klassOop find_instance_or_array_klass(symbolHandle class_name, 272 Handle class_loader, 273 Handle protection_domain, 274 TRAPS); 275 276 // If the given name is known to vmSymbols, return the well-know klass: 277 static klassOop find_well_known_klass(symbolOop class_name); 278 279 // Lookup an instance or array class that has already been loaded 280 // either into the given class loader, or else into another class 281 // loader that is constrained (via loader constraints) to produce 282 // a consistent class. Do not take protection domains into account. 283 // Do not make any queries to class loaders; consult only the cache. 284 // Return NULL if the class is not found. 285 // 286 // This function is a strict superset of find_instance_or_array_klass. 287 // This function (the unchecked version) makes a conservative prediction 288 // of the result of the checked version, assuming successful lookup. 289 // If both functions return non-null, they must return the same value. 290 // Also, the unchecked version may sometimes be non-null where the 291 // checked version is null. This can occur in several ways: 292 // 1. No query has yet been made to the class loader. 293 // 2. The class loader was queried, but chose not to delegate. 294 // 3. ClassLoader.checkPackageAccess rejected a proposed protection domain. 295 // 4. Loading was attempted, but there was a linkage error of some sort. 296 // In all of these cases, the loader constraints on this type are 297 // satisfied, and it is safe for classes in the given class loader 298 // to manipulate strongly-typed values of the found class, subject 299 // to local linkage and access checks. 300 static klassOop find_constrained_instance_or_array_klass(symbolHandle class_name, 301 Handle class_loader, 302 TRAPS); 303 304 // Iterate over all klasses in dictionary 305 // Just the classes from defining class loaders 306 static void classes_do(void f(klassOop)); 307 // Added for initialize_itable_for_klass to handle exceptions 308 static void classes_do(void f(klassOop, TRAPS), TRAPS); 309 // All classes, and their class loaders 310 static void classes_do(void f(klassOop, oop)); 311 // All classes, and their class loaders 312 // (added for helpers that use HandleMarks and ResourceMarks) 313 static void classes_do(void f(klassOop, oop, TRAPS), TRAPS); 314 // All entries in the placeholder table and their class loaders 315 static void placeholders_do(void f(symbolOop, oop)); 316 317 // Iterate over all methods in all klasses in dictionary 318 static void methods_do(void f(methodOop)); 319 320 // Garbage collection support 321 322 // This method applies "blk->do_oop" to all the pointers to "system" 323 // classes and loaders. 324 static void always_strong_oops_do(OopClosure* blk); 325 static void always_strong_classes_do(OopClosure* blk); 326 // This method applies "blk->do_oop" to all the placeholders. 327 static void placeholders_do(OopClosure* blk); 328 329 // Unload (that is, break root links to) all unmarked classes and 330 // loaders. Returns "true" iff something was unloaded. 331 static bool do_unloading(BoolObjectClosure* is_alive); 332 333 // Applies "f->do_oop" to all root oops in the system dictionary. 334 static void oops_do(OopClosure* f); 335 336 // System loader lock 337 static oop system_loader_lock() { return _system_loader_lock_obj; } 338 339private: 340 // Traverses preloaded oops: various system classes. These are 341 // guaranteed to be in the perm gen. 342 static void preloaded_oops_do(OopClosure* f); 343 static void lazily_loaded_oops_do(OopClosure* f); 344 345public: 346 // Sharing support. 347 static void reorder_dictionary(); 348 static void copy_buckets(char** top, char* end); 349 static void copy_table(char** top, char* end); 350 static void reverse(); 351 static void set_shared_dictionary(HashtableBucket* t, int length, 352 int number_of_entries); 353 // Printing 354 static void print() PRODUCT_RETURN; 355 static void print_class_statistics() PRODUCT_RETURN; 356 static void print_method_statistics() PRODUCT_RETURN; 357 358 // Number of contained klasses 359 // This is both fully loaded classes and classes in the process 360 // of being loaded 361 static int number_of_classes(); 362 363 // Monotonically increasing counter which grows as classes are 364 // loaded or modifications such as hot-swapping or setting/removing 365 // of breakpoints are performed 366 static inline int number_of_modifications() { assert_locked_or_safepoint(Compile_lock); return _number_of_modifications; } 367 // Needed by evolution and breakpoint code 368 static inline void notice_modification() { assert_locked_or_safepoint(Compile_lock); ++_number_of_modifications; } 369 370 // Verification 371 static void verify(); 372 373#ifdef ASSERT 374 static bool is_internal_format(symbolHandle class_name); 375#endif 376 377 // Verify class is in dictionary 378 static void verify_obj_klass_present(Handle obj, 379 symbolHandle class_name, 380 Handle class_loader); 381 382 // Initialization 383 static void initialize(TRAPS); 384 385 // Fast access to commonly used classes (preloaded) 386 static klassOop check_klass(klassOop k) { 387 assert(k != NULL, "preloaded klass not initialized"); 388 return k; 389 } 390 391 static klassOop check_klass_Pre(klassOop k) { return check_klass(k); } 392 static klassOop check_klass_Opt(klassOop k) { return k; } 393 static klassOop check_klass_Opt_Kernel(klassOop k) { return k; } //== Opt 394 static klassOop check_klass_Opt_Only_JDK15(klassOop k) { 395 assert(JDK_Version::is_gte_jdk15x_version(), "JDK 1.5 only"); 396 return k; 397 } 398 static klassOop check_klass_Opt_Only_JDK14NewRef(klassOop k) { 399 assert(JDK_Version::is_gte_jdk14x_version() && UseNewReflection, "JDK 1.4 only"); 400 // despite the optional loading, if you use this it must be present: 401 return check_klass(k); 402 } 403 404 static bool initialize_wk_klass(WKID id, int init_opt, TRAPS); 405 static void initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS); 406 static void initialize_wk_klasses_through(WKID end_id, WKID &start_id, TRAPS) { 407 int limit = (int)end_id + 1; 408 initialize_wk_klasses_until((WKID) limit, start_id, THREAD); 409 } 410 411public: 412 #define WK_KLASS_DECLARE(name, ignore_symbol, option) \ 413 static klassOop name() { return check_klass_##option(_well_known_klasses[WK_KLASS_ENUM_NAME(name)]); } 414 WK_KLASSES_DO(WK_KLASS_DECLARE); 415 #undef WK_KLASS_DECLARE 416 417 // Local definition for direct access to the private array: 418 #define WK_KLASS(name) _well_known_klasses[SystemDictionary::WK_KLASS_ENUM_NAME(name)] 419 420 static klassOop box_klass(BasicType t) { 421 assert((uint)t < T_VOID+1, "range check"); 422 return check_klass(_box_klasses[t]); 423 } 424 static BasicType box_klass_type(klassOop k); // inverse of box_klass 425 426 // methods returning lazily loaded klasses 427 // The corresponding method to load the class must be called before calling them. 428 static klassOop abstract_ownable_synchronizer_klass() { return check_klass(_abstract_ownable_synchronizer_klass); } 429 430 static void load_abstract_ownable_synchronizer_klass(TRAPS); 431 432private: 433 // Tells whether ClassLoader.loadClassInternal is present 434 static bool has_loadClassInternal() { return _has_loadClassInternal; } 435 436public: 437 // Tells whether ClassLoader.checkPackageAccess is present 438 static bool has_checkPackageAccess() { return _has_checkPackageAccess; } 439 440 static bool Class_klass_loaded() { return WK_KLASS(Class_klass) != NULL; } 441 static bool Cloneable_klass_loaded() { return WK_KLASS(Cloneable_klass) != NULL; } 442 443 // Returns default system loader 444 static oop java_system_loader(); 445 446 // Compute the default system loader 447 static void compute_java_system_loader(TRAPS); 448 449private: 450 // Mirrors for primitive classes (created eagerly) 451 static oop check_mirror(oop m) { 452 assert(m != NULL, "mirror not initialized"); 453 return m; 454 } 455 456public: 457 // Note: java_lang_Class::primitive_type is the inverse of java_mirror 458 459 // Check class loader constraints 460 static bool add_loader_constraint(symbolHandle name, Handle loader1, 461 Handle loader2, TRAPS); 462 static char* check_signature_loaders(symbolHandle signature, Handle loader1, 463 Handle loader2, bool is_method, TRAPS); 464 465 // JSR 292 466 // find the java.dyn.MethodHandles::invoke method for a given signature 467 static methodOop find_method_handle_invoke(symbolHandle name, 468 symbolHandle signature, 469 KlassHandle accessing_klass, 470 TRAPS); 471 // ask Java to compute a java.dyn.MethodType object for a given signature 472 static Handle find_method_handle_type(symbolHandle signature, 473 KlassHandle accessing_klass, 474 bool& return_bcp_flag, 475 TRAPS); 476 // ask Java to create a dynamic call site, while linking an invokedynamic op 477 static Handle make_dynamic_call_site(Handle bootstrap_method, 478 // Callee information: 479 symbolHandle name, 480 methodHandle signature_invoker, 481 Handle info, 482 // Caller information: 483 methodHandle caller_method, 484 int caller_bci, 485 TRAPS); 486 487 // coordinate with Java about bootstrap methods 488 static Handle find_bootstrap_method(KlassHandle caller, TRAPS); 489 490 // Utility for printing loader "name" as part of tracing constraints 491 static const char* loader_name(oop loader) { 492 return ((loader) == NULL ? "<bootloader>" : 493 instanceKlass::cast((loader)->klass())->name()->as_C_string() ); 494 } 495 496 // Record the error when the first attempt to resolve a reference from a constant 497 // pool entry to a class fails. 498 static void add_resolution_error(constantPoolHandle pool, int which, symbolHandle error); 499 static symbolOop find_resolution_error(constantPoolHandle pool, int which); 500 501 private: 502 503 enum Constants { 504 _loader_constraint_size = 107, // number of entries in constraint table 505 _resolution_error_size = 107, // number of entries in resolution error table 506 _invoke_method_size = 139, // number of entries in invoke method table 507 _nof_buckets = 1009 // number of buckets in hash table 508 }; 509 510 511 // Static variables 512 513 // Hashtable holding loaded classes. 514 static Dictionary* _dictionary; 515 516 // Hashtable holding placeholders for classes being loaded. 517 static PlaceholderTable* _placeholders; 518 519 // Hashtable holding classes from the shared archive. 520 static Dictionary* _shared_dictionary; 521 522 // Monotonically increasing counter which grows with 523 // _number_of_classes as well as hot-swapping and breakpoint setting 524 // and removal. 525 static int _number_of_modifications; 526 527 // Lock object for system class loader 528 static oop _system_loader_lock_obj; 529 530 // Constraints on class loaders 531 static LoaderConstraintTable* _loader_constraints; 532 533 // Resolution errors 534 static ResolutionErrorTable* _resolution_errors; 535 536 // Invoke methods (JSR 292) 537 static SymbolPropertyTable* _invoke_method_table; 538 539public: 540 // for VM_CounterDecay iteration support 541 friend class CounterDecay; 542 static klassOop try_get_next_class(); 543 544private: 545 static void validate_protection_domain(instanceKlassHandle klass, 546 Handle class_loader, 547 Handle protection_domain, TRAPS); 548 549 friend class VM_PopulateDumpSharedSpace; 550 friend class TraversePlaceholdersClosure; 551 static Dictionary* dictionary() { return _dictionary; } 552 static Dictionary* shared_dictionary() { return _shared_dictionary; } 553 static PlaceholderTable* placeholders() { return _placeholders; } 554 static LoaderConstraintTable* constraints() { return _loader_constraints; } 555 static ResolutionErrorTable* resolution_errors() { return _resolution_errors; } 556 static SymbolPropertyTable* invoke_method_table() { return _invoke_method_table; } 557 558 // Basic loading operations 559 static klassOop resolve_instance_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS); 560 static klassOop resolve_array_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS); 561 static instanceKlassHandle handle_parallel_super_load(symbolHandle class_name, symbolHandle supername, Handle class_loader, Handle protection_domain, Handle lockObject, TRAPS); 562 // Wait on SystemDictionary_lock; unlocks lockObject before 563 // waiting; relocks lockObject with correct recursion count 564 // after waiting, but before reentering SystemDictionary_lock 565 // to preserve lock order semantics. 566 static void double_lock_wait(Handle lockObject, TRAPS); 567 static void define_instance_class(instanceKlassHandle k, TRAPS); 568 static instanceKlassHandle find_or_define_instance_class(symbolHandle class_name, 569 Handle class_loader, 570 instanceKlassHandle k, TRAPS); 571 static instanceKlassHandle load_shared_class(symbolHandle class_name, 572 Handle class_loader, TRAPS); 573 static instanceKlassHandle load_shared_class(instanceKlassHandle ik, 574 Handle class_loader, TRAPS); 575 static instanceKlassHandle load_instance_class(symbolHandle class_name, Handle class_loader, TRAPS); 576 static Handle compute_loader_lock_object(Handle class_loader, TRAPS); 577 static void check_loader_lock_contention(Handle loader_lock, TRAPS); 578 static bool is_parallelCapable(Handle class_loader); 579 static bool is_parallelDefine(Handle class_loader); 580 581 static klassOop find_shared_class(symbolHandle class_name); 582 583 // Setup link to hierarchy 584 static void add_to_hierarchy(instanceKlassHandle k, TRAPS); 585 586private: 587 // We pass in the hashtable index so we can calculate it outside of 588 // the SystemDictionary_lock. 589 590 // Basic find on loaded classes 591 static klassOop find_class(int index, unsigned int hash, 592 symbolHandle name, Handle loader); 593 594 // Basic find on classes in the midst of being loaded 595 static symbolOop find_placeholder(int index, unsigned int hash, 596 symbolHandle name, Handle loader); 597 598 // Basic find operation of loaded classes and classes in the midst 599 // of loading; used for assertions and verification only. 600 static oop find_class_or_placeholder(symbolHandle class_name, 601 Handle class_loader); 602 603 // Updating entry in dictionary 604 // Add a completely loaded class 605 static void add_klass(int index, symbolHandle class_name, 606 Handle class_loader, KlassHandle obj); 607 608 // Add a placeholder for a class being loaded 609 static void add_placeholder(int index, 610 symbolHandle class_name, 611 Handle class_loader); 612 static void remove_placeholder(int index, 613 symbolHandle class_name, 614 Handle class_loader); 615 616 // Performs cleanups after resolve_super_or_fail. This typically needs 617 // to be called on failure. 618 // Won't throw, but can block. 619 static void resolution_cleanups(symbolHandle class_name, 620 Handle class_loader, 621 TRAPS); 622 623 // Initialization 624 static void initialize_preloaded_classes(TRAPS); 625 626 // Class loader constraints 627 static void check_constraints(int index, unsigned int hash, 628 instanceKlassHandle k, Handle loader, 629 bool defining, TRAPS); 630 static void update_dictionary(int d_index, unsigned int d_hash, 631 int p_index, unsigned int p_hash, 632 instanceKlassHandle k, Handle loader, TRAPS); 633 634 // Variables holding commonly used klasses (preloaded) 635 static klassOop _well_known_klasses[]; 636 637 // Lazily loaded klasses 638 static volatile klassOop _abstract_ownable_synchronizer_klass; 639 640 // table of box klasses (int_klass, etc.) 641 static klassOop _box_klasses[T_VOID+1]; 642 643 static oop _java_system_loader; 644 645 static bool _has_loadClassInternal; 646 static bool _has_checkPackageAccess; 647}; 648 649// Cf. vmSymbols vs. vmSymbolHandles 650class SystemDictionaryHandles : AllStatic { 651public: 652 #define WK_KLASS_HANDLE_DECLARE(name, ignore_symbol, option) \ 653 static KlassHandle name() { \ 654 SystemDictionary::name(); \ 655 klassOop* loc = &SystemDictionary::_well_known_klasses[SystemDictionary::WK_KLASS_ENUM_NAME(name)]; \ 656 return KlassHandle(loc, true); \ 657 } 658 WK_KLASSES_DO(WK_KLASS_HANDLE_DECLARE); 659 #undef WK_KLASS_HANDLE_DECLARE 660 661 static KlassHandle box_klass(BasicType t); 662}; 663