/*
* Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*
*/
// The system dictionary stores all loaded classes and maps:
//
// [class name,class loader] -> class i.e. [symbolOop,oop] -> klassOop
//
// Classes are loaded lazily. The default VM class loader is
// represented as NULL.
// The underlying data structure is an open hash table with a fixed number
// of buckets. During loading the loader object is locked, (for the VM loader
// a private lock object is used). Class loading can thus be done concurrently,
// but only by different loaders.
//
// During loading a placeholder (name, loader) is temporarily placed in
// a side data structure, and is used to detect ClassCircularityErrors
// and to perform verification during GC. A GC can occur in the midst
// of class loading, as we call out to Java, have to take locks, etc.
//
// When class loading is finished, a new entry is added to the system
// dictionary and the place holder is removed. Note that the protection
// domain field of the system dictionary has not yet been filled in when
// the "real" system dictionary entry is created.
//
// Clients of this class who are interested in finding if a class has
// been completely loaded -- not classes in the process of being loaded --
// can read the SystemDictionary unlocked. This is safe because
// - entries are only deleted at safepoints
// - readers cannot come to a safepoint while actively examining
// an entry (an entry cannot be deleted from under a reader)
// - entries must be fully formed before they are available to concurrent
// readers (we must ensure write ordering)
//
// Note that placeholders are deleted at any time, as they are removed
// when a class is completely loaded. Therefore, readers as well as writers
// of placeholders must hold the SystemDictionary_lock.
//
class Dictionary;
class PlaceholderTable;
class LoaderConstraintTable;
class HashtableBucket;
class ResolutionErrorTable;
class SystemDictionary : AllStatic {
friend class VMStructs;
friend class CompactingPermGenGen;
NOT_PRODUCT(friend class instanceKlassKlass;)
public:
// Returns a class with a given class name and class loader. Loads the
// class if needed. If not found a NoClassDefFoundError or a
// ClassNotFoundException is thrown, depending on the value on the
// throw_error flag. For most uses the throw_error argument should be set
// to true.
static klassOop resolve_or_fail(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS);
// Convenient call for null loader and protection domain.
static klassOop resolve_or_fail(symbolHandle class_name, bool throw_error, TRAPS);
private:
// handle error translation for resolve_or_null results
static klassOop handle_resolution_exception(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS);
public:
// Returns a class with a given class name and class loader.
// Loads the class if needed. If not found NULL is returned.
static klassOop resolve_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
// Version with null loader and protection domain
static klassOop resolve_or_null(symbolHandle class_name, TRAPS);
// Resolve a superclass or superinterface. Called from ClassFileParser,
// parse_interfaces, resolve_instance_class_or_null, load_shared_class
// "child_name" is the class whose super class or interface is being resolved.
static klassOop resolve_super_or_fail(symbolHandle child_name,
symbolHandle class_name,
Handle class_loader,
Handle protection_domain,
bool is_superclass,
TRAPS);
// Parse new stream. This won't update the system dictionary or
// class hierarchy, simply parse the stream. Used by JVMTI RedefineClasses.
static klassOop parse_stream(symbolHandle class_name,
Handle class_loader,
Handle protection_domain,
ClassFileStream* st,
TRAPS);
// Resolve from stream (called by jni_DefineClass and JVM_DefineClass)
static klassOop resolve_from_stream(symbolHandle class_name, Handle class_loader, Handle protection_domain, ClassFileStream* st, TRAPS);
// Lookup an already loaded class. If not found NULL is returned.
static klassOop find(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
// Lookup an already loaded instance or array class.
// Do not make any queries to class loaders; consult only the cache.
// If not found NULL is returned.
static klassOop find_instance_or_array_klass(symbolHandle class_name,
Handle class_loader,
Handle protection_domain,
TRAPS);
// Lookup an instance or array class that has already been loaded
// either into the given class loader, or else into another class
// loader that is constrained (via loader constraints) to produce
// a consistent class. Do not take protection domains into account.
// Do not make any queries to class loaders; consult only the cache.
// Return NULL if the class is not found.
//
// This function is a strict superset of find_instance_or_array_klass.
// This function (the unchecked version) makes a conservative prediction
// of the result of the checked version, assuming successful lookup.
// If both functions return non-null, they must return the same value.
// Also, the unchecked version may sometimes be non-null where the
// checked version is null. This can occur in several ways:
// 1. No query has yet been made to the class loader.
// 2. The class loader was queried, but chose not to delegate.
// 3. ClassLoader.checkPackageAccess rejected a proposed protection domain.
// 4. Loading was attempted, but there was a linkage error of some sort.
// In all of these cases, the loader constraints on this type are
// satisfied, and it is safe for classes in the given class loader
// to manipulate strongly-typed values of the found class, subject
// to local linkage and access checks.
static klassOop find_constrained_instance_or_array_klass(symbolHandle class_name,
Handle class_loader,
TRAPS);
// Iterate over all klasses in dictionary
// Just the classes from defining class loaders
static void classes_do(void f(klassOop));
// Added for initialize_itable_for_klass to handle exceptions
static void classes_do(void f(klassOop, TRAPS), TRAPS);
// All classes, and their class loaders
static void classes_do(void f(klassOop, oop));
// All classes, and their class loaders
// (added for helpers that use HandleMarks and ResourceMarks)
static void classes_do(void f(klassOop, oop, TRAPS), TRAPS);
// All entries in the placeholder table and their class loaders
static void placeholders_do(void f(symbolOop, oop));
// Iterate over all methods in all klasses in dictionary
static void methods_do(void f(methodOop));
// Garbage collection support
// This method applies "blk->do_oop" to all the pointers to "system"
// classes and loaders.
static void always_strong_oops_do(OopClosure* blk);
static void always_strong_classes_do(OopClosure* blk);
// This method applies "blk->do_oop" to all the placeholders.
static void placeholders_do(OopClosure* blk);
// Unload (that is, break root links to) all unmarked classes and
// loaders. Returns "true" iff something was unloaded.
static bool do_unloading(BoolObjectClosure* is_alive);
// Applies "f->do_oop" to all root oops in the system dictionary.
static void oops_do(OopClosure* f);
// System loader lock
static oop system_loader_lock() { return _system_loader_lock_obj; }
private:
// Traverses preloaded oops: various system classes. These are
// guaranteed to be in the perm gen.
static void preloaded_oops_do(OopClosure* f);
static void lazily_loaded_oops_do(OopClosure* f);
public:
// Sharing support.
static void reorder_dictionary();
static void copy_buckets(char** top, char* end);
static void copy_table(char** top, char* end);
static void reverse();
static void set_shared_dictionary(HashtableBucket* t, int length,
int number_of_entries);
// Printing
static void print() PRODUCT_RETURN;
static void print_class_statistics() PRODUCT_RETURN;
static void print_method_statistics() PRODUCT_RETURN;
// Number of contained klasses
// This is both fully loaded classes and classes in the process
// of being loaded
static int number_of_classes();
// Monotonically increasing counter which grows as classes are
// loaded or modifications such as hot-swapping or setting/removing
// of breakpoints are performed
static inline int number_of_modifications() { assert_locked_or_safepoint(Compile_lock); return _number_of_modifications; }
// Needed by evolution and breakpoint code
static inline void notice_modification() { assert_locked_or_safepoint(Compile_lock); ++_number_of_modifications; }
// Verification
static void verify();
#ifdef ASSERT
static bool is_internal_format(symbolHandle class_name);
#endif
// Verify class is in dictionary
static void verify_obj_klass_present(Handle obj,
symbolHandle class_name,
Handle class_loader);
// Initialization
static void initialize(TRAPS);
// Fast access to commonly used classes (preloaded)
static klassOop check_klass(klassOop k) {
assert(k != NULL, "preloaded klass not initialized");
return k;
}
public:
static klassOop object_klass() { return check_klass(_object_klass); }
static klassOop string_klass() { return check_klass(_string_klass); }
static klassOop class_klass() { return check_klass(_class_klass); }
static klassOop cloneable_klass() { return check_klass(_cloneable_klass); }
static klassOop classloader_klass() { return check_klass(_classloader_klass); }
static klassOop serializable_klass() { return check_klass(_serializable_klass); }
static klassOop system_klass() { return check_klass(_system_klass); }
static klassOop throwable_klass() { return check_klass(_throwable_klass); }
static klassOop error_klass() { return check_klass(_error_klass); }
static klassOop threaddeath_klass() { return check_klass(_threaddeath_klass); }
static klassOop exception_klass() { return check_klass(_exception_klass); }
static klassOop runtime_exception_klass() { return check_klass(_runtime_exception_klass); }
static klassOop classNotFoundException_klass() { return check_klass(_classNotFoundException_klass); }
static klassOop noClassDefFoundError_klass() { return check_klass(_noClassDefFoundError_klass); }
static klassOop linkageError_klass() { return check_klass(_linkageError_klass); }
static klassOop ClassCastException_klass() { return check_klass(_classCastException_klass); }
static klassOop ArrayStoreException_klass() { return check_klass(_arrayStoreException_klass); }
static klassOop virtualMachineError_klass() { return check_klass(_virtualMachineError_klass); }
static klassOop OutOfMemoryError_klass() { return check_klass(_outOfMemoryError_klass); }
static klassOop StackOverflowError_klass() { return check_klass(_StackOverflowError_klass); }
static klassOop IllegalMonitorStateException_klass() { return check_klass(_illegalMonitorStateException_klass); }
static klassOop protectionDomain_klass() { return check_klass(_protectionDomain_klass); }
static klassOop AccessControlContext_klass() { return check_klass(_AccessControlContext_klass); }
static klassOop reference_klass() { return check_klass(_reference_klass); }
static klassOop soft_reference_klass() { return check_klass(_soft_reference_klass); }
static klassOop weak_reference_klass() { return check_klass(_weak_reference_klass); }
static klassOop final_reference_klass() { return check_klass(_final_reference_klass); }
static klassOop phantom_reference_klass() { return check_klass(_phantom_reference_klass); }
static klassOop finalizer_klass() { return check_klass(_finalizer_klass); }
static klassOop thread_klass() { return check_klass(_thread_klass); }
static klassOop threadGroup_klass() { return check_klass(_threadGroup_klass); }
static klassOop properties_klass() { return check_klass(_properties_klass); }
static klassOop reflect_accessible_object_klass() { return check_klass(_reflect_accessible_object_klass); }
static klassOop reflect_field_klass() { return check_klass(_reflect_field_klass); }
static klassOop reflect_method_klass() { return check_klass(_reflect_method_klass); }
static klassOop reflect_constructor_klass() { return check_klass(_reflect_constructor_klass); }
static klassOop reflect_method_accessor_klass() {
assert(JDK_Version::is_gte_jdk14x_version() && UseNewReflection, "JDK 1.4 only");
return check_klass(_reflect_method_accessor_klass);
}
static klassOop reflect_constructor_accessor_klass() {
assert(JDK_Version::is_gte_jdk14x_version() && UseNewReflection, "JDK 1.4 only");
return check_klass(_reflect_constructor_accessor_klass);
}
// NOTE: needed too early in bootstrapping process to have checks based on JDK version
static klassOop reflect_magic_klass() { return _reflect_magic_klass; }
static klassOop reflect_delegating_classloader_klass() { return _reflect_delegating_classloader_klass; }
static klassOop reflect_constant_pool_klass() {
assert(JDK_Version::is_gte_jdk15x_version(), "JDK 1.5 only");
return _reflect_constant_pool_klass;
}
static klassOop reflect_unsafe_static_field_accessor_impl_klass() {
assert(JDK_Version::is_gte_jdk15x_version(), "JDK 1.5 only");
return _reflect_unsafe_static_field_accessor_impl_klass;
}
static klassOop vector_klass() { return check_klass(_vector_klass); }
static klassOop hashtable_klass() { return check_klass(_hashtable_klass); }
static klassOop stringBuffer_klass() { return check_klass(_stringBuffer_klass); }
static klassOop stackTraceElement_klass() { return check_klass(_stackTraceElement_klass); }
static klassOop java_nio_Buffer_klass() { return check_klass(_java_nio_Buffer_klass); }
static klassOop sun_misc_AtomicLongCSImpl_klass() { return _sun_misc_AtomicLongCSImpl_klass; }
// To support incremental JRE downloads (KERNEL JRE). Null if not present.
static klassOop sun_jkernel_DownloadManager_klass() { return _sun_jkernel_DownloadManager_klass; }
static klassOop boolean_klass() { return check_klass(_boolean_klass); }
static klassOop char_klass() { return check_klass(_char_klass); }
static klassOop float_klass() { return check_klass(_float_klass); }
static klassOop double_klass() { return check_klass(_double_klass); }
static klassOop byte_klass() { return check_klass(_byte_klass); }
static klassOop short_klass() { return check_klass(_short_klass); }
static klassOop int_klass() { return check_klass(_int_klass); }
static klassOop long_klass() { return check_klass(_long_klass); }
static klassOop box_klass(BasicType t) {
assert((uint)t < T_VOID+1, "range check");
return check_klass(_box_klasses[t]);
}
static BasicType box_klass_type(klassOop k); // inverse of box_klass
// methods returning lazily loaded klasses
// The corresponding method to load the class must be called before calling them.
static klassOop abstract_ownable_synchronizer_klass() { return check_klass(_abstract_ownable_synchronizer_klass); }
static void load_abstract_ownable_synchronizer_klass(TRAPS);
private:
// Tells whether ClassLoader.loadClassInternal is present
static bool has_loadClassInternal() { return _has_loadClassInternal; }
public:
// Tells whether ClassLoader.checkPackageAccess is present
static bool has_checkPackageAccess() { return _has_checkPackageAccess; }
static bool class_klass_loaded() { return _class_klass != NULL; }
static bool cloneable_klass_loaded() { return _cloneable_klass != NULL; }
// Returns default system loader
static oop java_system_loader();
// Compute the default system loader
static void compute_java_system_loader(TRAPS);
private:
// Mirrors for primitive classes (created eagerly)
static oop check_mirror(oop m) {
assert(m != NULL, "mirror not initialized");
return m;
}
public:
// Note: java_lang_Class::primitive_type is the inverse of java_mirror
// Check class loader constraints
static bool add_loader_constraint(symbolHandle name, Handle loader1,
Handle loader2, TRAPS);
static char* check_signature_loaders(symbolHandle signature, Handle loader1,
Handle loader2, bool is_method, TRAPS);
// Utility for printing loader "name" as part of tracing constraints
static const char* loader_name(oop loader) {
return ((loader) == NULL ? "<bootloader>" :
instanceKlass::cast((loader)->klass())->name()->as_C_string() );
}
// Record the error when the first attempt to resolve a reference from a constant
// pool entry to a class fails.
static void add_resolution_error(constantPoolHandle pool, int which, symbolHandle error);
static symbolOop find_resolution_error(constantPoolHandle pool, int which);
private:
enum Constants {
_loader_constraint_size = 107, // number of entries in constraint table
_resolution_error_size = 107, // number of entries in resolution error table
_nof_buckets = 1009 // number of buckets in hash table
};
// Static variables
// Hashtable holding loaded classes.
static Dictionary* _dictionary;
// Hashtable holding placeholders for classes being loaded.
static PlaceholderTable* _placeholders;
// Hashtable holding classes from the shared archive.
static Dictionary* _shared_dictionary;
// Monotonically increasing counter which grows with
// _number_of_classes as well as hot-swapping and breakpoint setting
// and removal.
static int _number_of_modifications;
// Lock object for system class loader
static oop _system_loader_lock_obj;
// Constraints on class loaders
static LoaderConstraintTable* _loader_constraints;
// Resolution errors
static ResolutionErrorTable* _resolution_errors;
public:
// for VM_CounterDecay iteration support
friend class CounterDecay;
static klassOop try_get_next_class();
private:
static void validate_protection_domain(instanceKlassHandle klass,
Handle class_loader,
Handle protection_domain, TRAPS);
friend class VM_PopulateDumpSharedSpace;
friend class TraversePlaceholdersClosure;
static Dictionary* dictionary() { return _dictionary; }
static Dictionary* shared_dictionary() { return _shared_dictionary; }
static PlaceholderTable* placeholders() { return _placeholders; }
static LoaderConstraintTable* constraints() { return _loader_constraints; }
static ResolutionErrorTable* resolution_errors() { return _resolution_errors; }
// Basic loading operations
static klassOop resolve_instance_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
static klassOop resolve_array_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS);
static instanceKlassHandle handle_parallel_super_load(symbolHandle class_name, symbolHandle supername, Handle class_loader, Handle protection_domain, Handle lockObject, TRAPS);
// Wait on SystemDictionary_lock; unlocks lockObject before
// waiting; relocks lockObject with correct recursion count
// after waiting, but before reentering SystemDictionary_lock
// to preserve lock order semantics.
static void double_lock_wait(Handle lockObject, TRAPS);
static void define_instance_class(instanceKlassHandle k, TRAPS);
static instanceKlassHandle find_or_define_instance_class(symbolHandle class_name,
Handle class_loader,
instanceKlassHandle k, TRAPS);
static instanceKlassHandle load_shared_class(symbolHandle class_name,
Handle class_loader, TRAPS);
static instanceKlassHandle load_shared_class(instanceKlassHandle ik,
Handle class_loader, TRAPS);
static instanceKlassHandle load_instance_class(symbolHandle class_name, Handle class_loader, TRAPS);
static Handle compute_loader_lock_object(Handle class_loader, TRAPS);
static void check_loader_lock_contention(Handle loader_lock, TRAPS);
static klassOop find_shared_class(symbolHandle class_name);
// Setup link to hierarchy
static void add_to_hierarchy(instanceKlassHandle k, TRAPS);
private:
// We pass in the hashtable index so we can calculate it outside of
// the SystemDictionary_lock.
// Basic find on loaded classes
static klassOop find_class(int index, unsigned int hash,
symbolHandle name, Handle loader);
// Basic find on classes in the midst of being loaded
static symbolOop find_placeholder(int index, unsigned int hash,
symbolHandle name, Handle loader);
// Basic find operation of loaded classes and classes in the midst
// of loading; used for assertions and verification only.
static oop find_class_or_placeholder(symbolHandle class_name,
Handle class_loader);
// Updating entry in dictionary
// Add a completely loaded class
static void add_klass(int index, symbolHandle class_name,
Handle class_loader, KlassHandle obj);
// Add a placeholder for a class being loaded
static void add_placeholder(int index,
symbolHandle class_name,
Handle class_loader);
static void remove_placeholder(int index,
symbolHandle class_name,
Handle class_loader);
// Performs cleanups after resolve_super_or_fail. This typically needs
// to be called on failure.
// Won't throw, but can block.
static void resolution_cleanups(symbolHandle class_name,
Handle class_loader,
TRAPS);
// Initialization
static void initialize_preloaded_classes(TRAPS);
// Class loader constraints
static void check_constraints(int index, unsigned int hash,
instanceKlassHandle k, Handle loader,
bool defining, TRAPS);
static void update_dictionary(int d_index, unsigned int d_hash,
int p_index, unsigned int p_hash,
instanceKlassHandle k, Handle loader, TRAPS);
// Variables holding commonly used klasses (preloaded)
static klassOop _object_klass;
static klassOop _string_klass;
static klassOop _class_klass;
static klassOop _cloneable_klass;
static klassOop _classloader_klass;
static klassOop _serializable_klass;
static klassOop _system_klass;
static klassOop _throwable_klass;
static klassOop _error_klass;
static klassOop _threaddeath_klass;
static klassOop _exception_klass;
static klassOop _runtime_exception_klass;
static klassOop _classNotFoundException_klass;
static klassOop _noClassDefFoundError_klass;
static klassOop _linkageError_klass;
static klassOop _classCastException_klass;
static klassOop _arrayStoreException_klass;
static klassOop _virtualMachineError_klass;
static klassOop _outOfMemoryError_klass;
static klassOop _StackOverflowError_klass;
static klassOop _illegalMonitorStateException_klass;
static klassOop _protectionDomain_klass;
static klassOop _AccessControlContext_klass;
static klassOop _reference_klass;
static klassOop _soft_reference_klass;
static klassOop _weak_reference_klass;
static klassOop _final_reference_klass;
static klassOop _phantom_reference_klass;
static klassOop _finalizer_klass;
static klassOop _thread_klass;
static klassOop _threadGroup_klass;
static klassOop _properties_klass;
static klassOop _reflect_accessible_object_klass;
static klassOop _reflect_field_klass;
static klassOop _reflect_method_klass;
static klassOop _reflect_constructor_klass;
// 1.4 reflection implementation
static klassOop _reflect_magic_klass;
static klassOop _reflect_method_accessor_klass;
static klassOop _reflect_constructor_accessor_klass;
static klassOop _reflect_delegating_classloader_klass;
// 1.5 annotations implementation
static klassOop _reflect_constant_pool_klass;
static klassOop _reflect_unsafe_static_field_accessor_impl_klass;
static klassOop _stringBuffer_klass;
static klassOop _vector_klass;
static klassOop _hashtable_klass;
static klassOop _stackTraceElement_klass;
static klassOop _java_nio_Buffer_klass;
static klassOop _sun_misc_AtomicLongCSImpl_klass;
// KERNEL JRE support.
static klassOop _sun_jkernel_DownloadManager_klass;
// Lazily loaded klasses
static volatile klassOop _abstract_ownable_synchronizer_klass;
// Box klasses
static klassOop _boolean_klass;
static klassOop _char_klass;
static klassOop _float_klass;
static klassOop _double_klass;
static klassOop _byte_klass;
static klassOop _short_klass;
static klassOop _int_klass;
static klassOop _long_klass;
// table of same
static klassOop _box_klasses[T_VOID+1];
static oop _java_system_loader;
static bool _has_loadClassInternal;
static bool _has_checkPackageAccess;
};