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android / platform / libcore / 8153779ad32 / . / hotspot / src / share / vm / classfile / systemDictionary.cpp
blob: d71f63a6c120ec05528f323accca39ace804babe [file] [log] [blame]
/*
* 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.
*
*/
# include "incls/_precompiled.incl"
# include "incls/_systemDictionary.cpp.incl"
Dictionary* SystemDictionary::_dictionary = NULL;
PlaceholderTable* SystemDictionary::_placeholders = NULL;
Dictionary* SystemDictionary::_shared_dictionary = NULL;
LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
int SystemDictionary::_number_of_modifications = 0;
oop SystemDictionary::_system_loader_lock_obj = NULL;
klassOop SystemDictionary::_object_klass = NULL;
klassOop SystemDictionary::_string_klass = NULL;
klassOop SystemDictionary::_class_klass = NULL;
klassOop SystemDictionary::_cloneable_klass = NULL;
klassOop SystemDictionary::_classloader_klass = NULL;
klassOop SystemDictionary::_serializable_klass = NULL;
klassOop SystemDictionary::_system_klass = NULL;
klassOop SystemDictionary::_throwable_klass = NULL;
klassOop SystemDictionary::_error_klass = NULL;
klassOop SystemDictionary::_threaddeath_klass = NULL;
klassOop SystemDictionary::_exception_klass = NULL;
klassOop SystemDictionary::_runtime_exception_klass = NULL;
klassOop SystemDictionary::_classNotFoundException_klass = NULL;
klassOop SystemDictionary::_noClassDefFoundError_klass = NULL;
klassOop SystemDictionary::_linkageError_klass = NULL;
klassOop SystemDictionary::_classCastException_klass = NULL;
klassOop SystemDictionary::_arrayStoreException_klass = NULL;
klassOop SystemDictionary::_virtualMachineError_klass = NULL;
klassOop SystemDictionary::_outOfMemoryError_klass = NULL;
klassOop SystemDictionary::_StackOverflowError_klass = NULL;
klassOop SystemDictionary::_illegalMonitorStateException_klass = NULL;
klassOop SystemDictionary::_protectionDomain_klass = NULL;
klassOop SystemDictionary::_AccessControlContext_klass = NULL;
klassOop SystemDictionary::_reference_klass = NULL;
klassOop SystemDictionary::_soft_reference_klass = NULL;
klassOop SystemDictionary::_weak_reference_klass = NULL;
klassOop SystemDictionary::_final_reference_klass = NULL;
klassOop SystemDictionary::_phantom_reference_klass = NULL;
klassOop SystemDictionary::_finalizer_klass = NULL;
klassOop SystemDictionary::_thread_klass = NULL;
klassOop SystemDictionary::_threadGroup_klass = NULL;
klassOop SystemDictionary::_properties_klass = NULL;
klassOop SystemDictionary::_reflect_accessible_object_klass = NULL;
klassOop SystemDictionary::_reflect_field_klass = NULL;
klassOop SystemDictionary::_reflect_method_klass = NULL;
klassOop SystemDictionary::_reflect_constructor_klass = NULL;
klassOop SystemDictionary::_reflect_magic_klass = NULL;
klassOop SystemDictionary::_reflect_method_accessor_klass = NULL;
klassOop SystemDictionary::_reflect_constructor_accessor_klass = NULL;
klassOop SystemDictionary::_reflect_delegating_classloader_klass = NULL;
klassOop SystemDictionary::_reflect_constant_pool_klass = NULL;
klassOop SystemDictionary::_reflect_unsafe_static_field_accessor_impl_klass = NULL;
klassOop SystemDictionary::_vector_klass = NULL;
klassOop SystemDictionary::_hashtable_klass = NULL;
klassOop SystemDictionary::_stringBuffer_klass = NULL;
klassOop SystemDictionary::_stackTraceElement_klass = NULL;
klassOop SystemDictionary::_java_nio_Buffer_klass = NULL;
klassOop SystemDictionary::_sun_misc_AtomicLongCSImpl_klass = NULL;
klassOop SystemDictionary::_sun_jkernel_DownloadManager_klass = NULL;
klassOop SystemDictionary::_boolean_klass = NULL;
klassOop SystemDictionary::_char_klass = NULL;
klassOop SystemDictionary::_float_klass = NULL;
klassOop SystemDictionary::_double_klass = NULL;
klassOop SystemDictionary::_byte_klass = NULL;
klassOop SystemDictionary::_short_klass = NULL;
klassOop SystemDictionary::_int_klass = NULL;
klassOop SystemDictionary::_long_klass = NULL;
klassOop SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
oop SystemDictionary::_java_system_loader = NULL;
bool SystemDictionary::_has_loadClassInternal = false;
bool SystemDictionary::_has_checkPackageAccess = false;
// lazily initialized klass variables
volatile klassOop SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
// ----------------------------------------------------------------------------
// Java-level SystemLoader
oop SystemDictionary::java_system_loader() {
return _java_system_loader;
}
void SystemDictionary::compute_java_system_loader(TRAPS) {
KlassHandle system_klass(THREAD, _classloader_klass);
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
KlassHandle(THREAD, _classloader_klass),
vmSymbolHandles::getSystemClassLoader_name(),
vmSymbolHandles::void_classloader_signature(),
CHECK);
_java_system_loader = (oop)result.get_jobject();
}
// ----------------------------------------------------------------------------
// debugging
#ifdef ASSERT
// return true if class_name contains no '.' (internal format is '/')
bool SystemDictionary::is_internal_format(symbolHandle class_name) {
if (class_name.not_null()) {
ResourceMark rm;
char* name = class_name->as_C_string();
return strchr(name, '.') == NULL;
} else {
return true;
}
}
#endif
// ----------------------------------------------------------------------------
// Resolving of classes
// Forwards to resolve_or_null
klassOop SystemDictionary::resolve_or_fail(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
klassOop klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
if (HAS_PENDING_EXCEPTION || klass == NULL) {
KlassHandle k_h(THREAD, klass);
// can return a null klass
klass = handle_resolution_exception(class_name, class_loader, protection_domain, throw_error, k_h, THREAD);
}
return klass;
}
klassOop SystemDictionary::handle_resolution_exception(symbolHandle class_name, Handle class_loader, Handle protection_domain, bool throw_error, KlassHandle klass_h, TRAPS) {
if (HAS_PENDING_EXCEPTION) {
// If we have a pending exception we forward it to the caller, unless throw_error is true,
// in which case we have to check whether the pending exception is a ClassNotFoundException,
// and if so convert it to a NoClassDefFoundError
// And chain the original ClassNotFoundException
if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::classNotFoundException_klass())) {
ResourceMark rm(THREAD);
assert(klass_h() == NULL, "Should not have result with exception pending");
Handle e(THREAD, PENDING_EXCEPTION);
CLEAR_PENDING_EXCEPTION;
THROW_MSG_CAUSE_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
} else {
return NULL;
}
}
// Class not found, throw appropriate error or exception depending on value of throw_error
if (klass_h() == NULL) {
ResourceMark rm(THREAD);
if (throw_error) {
THROW_MSG_0(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
} else {
THROW_MSG_0(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
}
}
return (klassOop)klass_h();
}
klassOop SystemDictionary::resolve_or_fail(symbolHandle class_name,
bool throw_error, TRAPS)
{
return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
}
// Forwards to resolve_instance_class_or_null
klassOop SystemDictionary::resolve_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS) {
assert(!THREAD->is_Compiler_thread(), "Can not load classes with the Compiler thread");
if (FieldType::is_array(class_name())) {
return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
} else {
return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
}
}
klassOop SystemDictionary::resolve_or_null(symbolHandle class_name, TRAPS) {
return resolve_or_null(class_name, Handle(), Handle(), THREAD);
}
// Forwards to resolve_instance_class_or_null
klassOop SystemDictionary::resolve_array_class_or_null(symbolHandle class_name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
assert(FieldType::is_array(class_name()), "must be array");
jint dimension;
symbolOop object_key;
klassOop k = NULL;
// dimension and object_key are assigned as a side-effect of this call
BasicType t = FieldType::get_array_info(class_name(),
&dimension,
&object_key,
CHECK_NULL);
if (t == T_OBJECT) {
symbolHandle h_key(THREAD, object_key);
// naked oop "k" is OK here -- we assign back into it
k = SystemDictionary::resolve_instance_class_or_null(h_key,
class_loader,
protection_domain,
CHECK_NULL);
if (k != NULL) {
k = Klass::cast(k)->array_klass(dimension, CHECK_NULL);
}
} else {
k = Universe::typeArrayKlassObj(t);
k = typeArrayKlass::cast(k)->array_klass(dimension, CHECK_NULL);
}
return k;
}
// Must be called for any super-class or super-interface resolution
// during class definition to allow class circularity checking
// super-interface callers:
// parse_interfaces - for defineClass & jvmtiRedefineClasses
// super-class callers:
// ClassFileParser - for defineClass & jvmtiRedefineClasses
// load_shared_class - while loading a class from shared archive
// resolve_instance_class_or_fail:
// when resolving a class that has an existing placeholder with
// a saved superclass [i.e. a defineClass is currently in progress]
// if another thread is trying to resolve the class, it must do
// super-class checks on its own thread to catch class circularity
// This last call is critical in class circularity checking for cases
// where classloading is delegated to different threads and the
// classloader lock is released.
// Take the case: Base->Super->Base
// 1. If thread T1 tries to do a defineClass of class Base
// resolve_super_or_fail creates placeholder: T1, Base (super Super)
// 2. resolve_instance_class_or_null does not find SD or placeholder for Super
// so it tries to load Super
// 3. If we load the class internally, or user classloader uses same thread
// loadClassFromxxx or defineClass via parseClassFile Super ...
// 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
// 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
// 3.4 calls resolve_super_or_fail Base
// 3.5 finds T1,Base -> throws class circularity
//OR 4. If T2 tries to resolve Super via defineClass Super ...
// 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
// 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
// 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
// 4.4 finds T2, Super -> throws class circularity
// Must be called, even if superclass is null, since this is
// where the placeholder entry is created which claims this
// thread is loading this class/classloader.
klassOop SystemDictionary::resolve_super_or_fail(symbolHandle child_name,
symbolHandle class_name,
Handle class_loader,
Handle protection_domain,
bool is_superclass,
TRAPS) {
// Double-check, if child class is already loaded, just return super-class,interface
// Don't add a placedholder if already loaded, i.e. already in system dictionary
// Make sure there's a placeholder for the *child* before resolving.
// Used as a claim that this thread is currently loading superclass/classloader
// Used here for ClassCircularity checks and also for heap verification
// (every instanceKlass in the heap needs to be in the system dictionary
// or have a placeholder).
// Must check ClassCircularity before checking if super class is already loaded
//
// We might not already have a placeholder if this child_name was
// first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
// the name of the class might not be known until the stream is actually
// parsed.
// Bugs 4643874, 4715493
// compute_hash can have a safepoint
unsigned int d_hash = dictionary()->compute_hash(child_name, class_loader);
int d_index = dictionary()->hash_to_index(d_hash);
unsigned int p_hash = placeholders()->compute_hash(child_name, class_loader);
int p_index = placeholders()->hash_to_index(p_hash);
// can't throw error holding a lock
bool child_already_loaded = false;
bool throw_circularity_error = false;
{
MutexLocker mu(SystemDictionary_lock, THREAD);
klassOop childk = find_class(d_index, d_hash, child_name, class_loader);
klassOop quicksuperk;
// to support // loading: if child done loading, just return superclass
// if class_name, & class_loader don't match:
// if initial define, SD update will give LinkageError
// if redefine: compare_class_versions will give HIERARCHY_CHANGED
// so we don't throw an exception here.
// see: nsk redefclass014 & java.lang.instrument Instrument032
if ((childk != NULL ) && (is_superclass) &&
((quicksuperk = instanceKlass::cast(childk)->super()) != NULL) &&
((Klass::cast(quicksuperk)->name() == class_name()) &&
(Klass::cast(quicksuperk)->class_loader() == class_loader()))) {
return quicksuperk;
} else {
PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, class_loader);
if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
throw_circularity_error = true;
}
// add placeholder entry even if error - callers will remove on error
PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, class_loader, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
if (throw_circularity_error) {
newprobe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER);
}
}
}
if (throw_circularity_error) {
ResourceMark rm(THREAD);
THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
}
// java.lang.Object should have been found above
assert(class_name() != NULL, "null super class for resolving");
// Resolve the super class or interface, check results on return
klassOop superk = NULL;
superk = SystemDictionary::resolve_or_null(class_name,
class_loader,
protection_domain,
THREAD);
KlassHandle superk_h(THREAD, superk);
// Note: clean up of placeholders currently in callers of
// resolve_super_or_fail - either at update_dictionary time
// or on error
{
MutexLocker mu(SystemDictionary_lock, THREAD);
PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, class_loader);
if (probe != NULL) {
probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER);
}
}
if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
// can null superk
superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, class_loader, protection_domain, true, superk_h, THREAD));
}
return superk_h();
}
void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
Handle class_loader,
Handle protection_domain,
TRAPS) {
if(!has_checkPackageAccess()) return;
// Now we have to call back to java to check if the initating class has access
JavaValue result(T_VOID);
if (TraceProtectionDomainVerification) {
// Print out trace information
tty->print_cr("Checking package access");
tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
}
assert(class_loader() != NULL, "should not have non-null protection domain for null classloader");
KlassHandle system_loader(THREAD, SystemDictionary::classloader_klass());
JavaCalls::call_special(&result,
class_loader,
system_loader,
vmSymbolHandles::checkPackageAccess_name(),
vmSymbolHandles::class_protectiondomain_signature(),
Handle(THREAD, klass->java_mirror()),
protection_domain,
THREAD);
if (TraceProtectionDomainVerification) {
if (HAS_PENDING_EXCEPTION) {
tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
} else {
tty->print_cr(" -> granted");
}
tty->cr();
}
if (HAS_PENDING_EXCEPTION) return;
// If no exception has been thrown, we have validated the protection domain
// Insert the protection domain of the initiating class into the set.
{
// We recalculate the entry here -- we've called out to java since
// the last time it was calculated.
symbolHandle kn(THREAD, klass->name());
unsigned int d_hash = dictionary()->compute_hash(kn, class_loader);
int d_index = dictionary()->hash_to_index(d_hash);
MutexLocker mu(SystemDictionary_lock, THREAD);
{
// Note that we have an entry, and entries can be deleted only during GC,
// so we cannot allow GC to occur while we're holding this entry.
// We're using a No_Safepoint_Verifier to catch any place where we
// might potentially do a GC at all.
// SystemDictionary::do_unloading() asserts that classes are only
// unloaded at a safepoint.
No_Safepoint_Verifier nosafepoint;
dictionary()->add_protection_domain(d_index, d_hash, klass, class_loader,
protection_domain, THREAD);
}
}
}
// We only get here if this thread finds that another thread
// has already claimed the placeholder token for the current operation,
// but that other thread either never owned or gave up the
// object lock
// Waits on SystemDictionary_lock to indicate placeholder table updated
// On return, caller must recheck placeholder table state
//
// We only get here if
// 1) custom classLoader, i.e. not bootstrap classloader
// 2) UnsyncloadClass not set
// 3) custom classLoader has broken the class loader objectLock
// so another thread got here in parallel
//
// lockObject must be held.
// Complicated dance due to lock ordering:
// Must first release the classloader object lock to
// allow initial definer to complete the class definition
// and to avoid deadlock
// Reclaim classloader lock object with same original recursion count
// Must release SystemDictionary_lock after notify, since
// class loader lock must be claimed before SystemDictionary_lock
// to prevent deadlocks
//
// The notify allows applications that did an untimed wait() on
// the classloader object lock to not hang.
void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
assert_lock_strong(SystemDictionary_lock);
bool calledholdinglock
= ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
assert(calledholdinglock,"must hold lock for notify");
assert(!UnsyncloadClass, "unexpected double_lock_wait");
ObjectSynchronizer::notifyall(lockObject, THREAD);
intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
SystemDictionary_lock->wait();
SystemDictionary_lock->unlock();
ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
SystemDictionary_lock->lock();
}
// If the class in is in the placeholder table, class loading is in progress
// For cases where the application changes threads to load classes, it
// is critical to ClassCircularity detection that we try loading
// the superclass on the same thread internally, so we do parallel
// super class loading here.
// This also is critical in cases where the original thread gets stalled
// even in non-circularity situations.
// Note: only one thread can define the class, but multiple can resolve
// Note: must call resolve_super_or_fail even if null super -
// to force placeholder entry creation for this class
// Caller must check for pending exception
// Returns non-null klassOop if other thread has completed load
// and we are done,
// If return null klassOop and no pending exception, the caller must load the class
instanceKlassHandle SystemDictionary::handle_parallel_super_load(
symbolHandle name, symbolHandle superclassname, Handle class_loader,
Handle protection_domain, Handle lockObject, TRAPS) {
instanceKlassHandle nh = instanceKlassHandle(); // null Handle
unsigned int d_hash = dictionary()->compute_hash(name, class_loader);
int d_index = dictionary()->hash_to_index(d_hash);
unsigned int p_hash = placeholders()->compute_hash(name, class_loader);
int p_index = placeholders()->hash_to_index(p_hash);
// superk is not used, resolve_super called for circularity check only
// This code is reached in two situations. One if this thread
// is loading the same class twice (e.g. ClassCircularity, or
// java.lang.instrument).
// The second is if another thread started the resolve_super first
// and has not yet finished.
// In both cases the original caller will clean up the placeholder
// entry on error.
klassOop superk = SystemDictionary::resolve_super_or_fail(name,
superclassname,
class_loader,
protection_domain,
true,
CHECK_(nh));
// We don't redefine the class, so we just need to clean up if there
// was not an error (don't want to modify any system dictionary
// data structures).
{
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
SystemDictionary_lock->notify_all();
}
// UnsyncloadClass does NOT wait for parallel superclass loads to complete
// Bootstrap classloader does wait for parallel superclass loads
if (UnsyncloadClass) {
MutexLocker mu(SystemDictionary_lock, THREAD);
// Check if classloading completed while we were loading superclass or waiting
klassOop check = find_class(d_index, d_hash, name, class_loader);
if (check != NULL) {
// Klass is already loaded, so just return it
return(instanceKlassHandle(THREAD, check));
} else {
return nh;
}
}
// must loop to both handle other placeholder updates
// and spurious notifications
bool super_load_in_progress = true;
PlaceholderEntry* placeholder;
while (super_load_in_progress) {
MutexLocker mu(SystemDictionary_lock, THREAD);
// Check if classloading completed while we were loading superclass or waiting
klassOop check = find_class(d_index, d_hash, name, class_loader);
if (check != NULL) {
// Klass is already loaded, so just return it
return(instanceKlassHandle(THREAD, check));
} else {
placeholder = placeholders()->get_entry(p_index, p_hash, name, class_loader);
if (placeholder && placeholder->super_load_in_progress() ){
// Before UnsyncloadClass:
// We only get here if the application has released the
// classloader lock when another thread was in the middle of loading a
// superclass/superinterface for this class, and now
// this thread is also trying to load this class.
// To minimize surprises, the first thread that started to
// load a class should be the one to complete the loading
// with the classfile it initially expected.
// This logic has the current thread wait once it has done
// all the superclass/superinterface loading it can, until
// the original thread completes the class loading or fails
// If it completes we will use the resulting instanceKlass
// which we will find below in the systemDictionary.
// We also get here for parallel bootstrap classloader
if (class_loader.is_null()) {
SystemDictionary_lock->wait();
} else {
double_lock_wait(lockObject, THREAD);
}
} else {
// If not in SD and not in PH, other thread's load must have failed
super_load_in_progress = false;
}
}
}
return (nh);
}
klassOop SystemDictionary::resolve_instance_class_or_null(symbolHandle class_name, Handle class_loader, Handle protection_domain, TRAPS) {
assert(class_name.not_null() && !FieldType::is_array(class_name()), "invalid class name");
// First check to see if we should remove wrapping L and ;
symbolHandle name;
if (FieldType::is_obj(class_name())) {
ResourceMark rm(THREAD);
// Ignore wrapping L and ;.
name = oopFactory::new_symbol_handle(class_name()->as_C_string() + 1, class_name()->utf8_length() - 2, CHECK_NULL);
} else {
name = class_name;
}
// UseNewReflection
// Fix for 4474172; see evaluation for more details
class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
// Do lookup to see if class already exist and the protection domain
// has the right access
unsigned int d_hash = dictionary()->compute_hash(name, class_loader);
int d_index = dictionary()->hash_to_index(d_hash);
klassOop probe = dictionary()->find(d_index, d_hash, name, class_loader,
protection_domain, THREAD);
if (probe != NULL) return probe;
// Non-bootstrap class loaders will call out to class loader and
// define via jvm/jni_DefineClass which will acquire the
// class loader object lock to protect against multiple threads
// defining the class in parallel by accident.
// This lock must be acquired here so the waiter will find
// any successful result in the SystemDictionary and not attempt
// the define
// Classloaders that support parallelism, e.g. bootstrap classloader,
// or all classloaders with UnsyncloadClass do not acquire lock here
bool DoObjectLock = true;
if (UnsyncloadClass || (class_loader.is_null())) {
DoObjectLock = false;
}
unsigned int p_hash = placeholders()->compute_hash(name, class_loader);
int p_index = placeholders()->hash_to_index(p_hash);
// Class is not in SystemDictionary so we have to do loading.
// Make sure we are synchronized on the class loader before we proceed
Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
check_loader_lock_contention(lockObject, THREAD);
ObjectLocker ol(lockObject, THREAD, DoObjectLock);
// Check again (after locking) if class already exist in SystemDictionary
bool class_has_been_loaded = false;
bool super_load_in_progress = false;
bool havesupername = false;
instanceKlassHandle k;
PlaceholderEntry* placeholder;
symbolHandle superclassname;
{
MutexLocker mu(SystemDictionary_lock, THREAD);
klassOop check = find_class(d_index, d_hash, name, class_loader);
if (check != NULL) {
// Klass is already loaded, so just return it
class_has_been_loaded = true;
k = instanceKlassHandle(THREAD, check);
} else {
placeholder = placeholders()->get_entry(p_index, p_hash, name, class_loader);
if (placeholder && placeholder->super_load_in_progress()) {
super_load_in_progress = true;
if (placeholder->havesupername() == true) {
superclassname = symbolHandle(THREAD, placeholder->supername());
havesupername = true;
}
}
}
}
// If the class in is in the placeholder table, class loading is in progress
if (super_load_in_progress && havesupername==true) {
k = SystemDictionary::handle_parallel_super_load(name, superclassname,
class_loader, protection_domain, lockObject, THREAD);
if (HAS_PENDING_EXCEPTION) {
return NULL;
}
if (!k.is_null()) {
class_has_been_loaded = true;
}
}
if (!class_has_been_loaded) {
// add placeholder entry to record loading instance class
// Five cases:
// All cases need to prevent modifying bootclasssearchpath
// in parallel with a classload of same classname
// case 1. traditional classloaders that rely on the classloader object lock
// - no other need for LOAD_INSTANCE
// case 2. traditional classloaders that break the classloader object lock
// as a deadlock workaround. Detection of this case requires that
// this check is done while holding the classloader object lock,
// and that lock is still held when calling classloader's loadClass.
// For these classloaders, we ensure that the first requestor
// completes the load and other requestors wait for completion.
// case 3. UnsyncloadClass - don't use objectLocker
// With this flag, we allow parallel classloading of a
// class/classloader pair
// case4. Bootstrap classloader - don't own objectLocker
// This classloader supports parallelism at the classloader level,
// but only allows a single load of a class/classloader pair.
// No performance benefit and no deadlock issues.
// case 5. Future: parallel user level classloaders - without objectLocker
symbolHandle nullsymbolHandle;
bool throw_circularity_error = false;
{
MutexLocker mu(SystemDictionary_lock, THREAD);
if (!UnsyncloadClass) {
PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
if (oldprobe) {
// only need check_seen_thread once, not on each loop
// 6341374 java/lang/Instrument with -Xcomp
if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
throw_circularity_error = true;
} else {
// case 1: traditional: should never see load_in_progress.
while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
// case 4: bootstrap classloader: prevent futile classloading,
// wait on first requestor
if (class_loader.is_null()) {
SystemDictionary_lock->wait();
} else {
// case 2: traditional with broken classloader lock. wait on first
// requestor.
double_lock_wait(lockObject, THREAD);
}
// Check if classloading completed while we were waiting
klassOop check = find_class(d_index, d_hash, name, class_loader);
if (check != NULL) {
// Klass is already loaded, so just return it
k = instanceKlassHandle(THREAD, check);
class_has_been_loaded = true;
}
// check if other thread failed to load and cleaned up
oldprobe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
}
}
}
}
// All cases: add LOAD_INSTANCE
// case 3: UnsyncloadClass: allow competing threads to try
// LOAD_INSTANCE in parallel
// add placeholder entry even if error - callers will remove on error
if (!class_has_been_loaded) {
PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, class_loader, PlaceholderTable::LOAD_INSTANCE, nullsymbolHandle, THREAD);
if (throw_circularity_error) {
newprobe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);
}
// For class loaders that do not acquire the classloader object lock,
// if they did not catch another thread holding LOAD_INSTANCE,
// need a check analogous to the acquire ObjectLocker/find_class
// i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
// one final check if the load has already completed
klassOop check = find_class(d_index, d_hash, name, class_loader);
if (check != NULL) {
// Klass is already loaded, so just return it
k = instanceKlassHandle(THREAD, check);
class_has_been_loaded = true;
newprobe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);
}
}
}
// must throw error outside of owning lock
if (throw_circularity_error) {
ResourceMark rm(THREAD);
THROW_MSG_0(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
}
if (!class_has_been_loaded) {
// Do actual loading
k = load_instance_class(name, class_loader, THREAD);
// In custom class loaders, the usual findClass calls
// findLoadedClass, which directly searches the SystemDictionary, then
// defineClass. If these are not atomic with respect to other threads,
// the findLoadedClass can fail, but the defineClass can get a
// LinkageError:: duplicate class definition.
// If they got a linkageError, check if a parallel class load succeeded.
// If it did, then for bytecode resolution the specification requires
// that we return the same result we did for the other thread, i.e. the
// successfully loaded instanceKlass
// Note: Class can not be unloaded as long as any classloader refs exist
// Should not get here for classloaders that support parallelism
// with the new cleaner mechanism, e.g. bootstrap classloader
if (UnsyncloadClass || (class_loader.is_null())) {
if (k.is_null() && HAS_PENDING_EXCEPTION
&& PENDING_EXCEPTION->is_a(SystemDictionary::linkageError_klass())) {
MutexLocker mu(SystemDictionary_lock, THREAD);
klassOop check = find_class(d_index, d_hash, name, class_loader);
if (check != NULL) {
// Klass is already loaded, so just use it
k = instanceKlassHandle(THREAD, check);
CLEAR_PENDING_EXCEPTION;
guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
}
}
}
// clean up placeholder entries for success or error
// This cleans up LOAD_INSTANCE entries
// It also cleans up LOAD_SUPER entries on errors from
// calling load_instance_class
{
MutexLocker mu(SystemDictionary_lock, THREAD);
PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name, class_loader);
if (probe != NULL) {
probe->remove_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE);
placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
SystemDictionary_lock->notify_all();
}
}
// If everything was OK (no exceptions, no null return value), and
// class_loader is NOT the defining loader, do a little more bookkeeping.
if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
k->class_loader() != class_loader()) {
check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
// Need to check for a PENDING_EXCEPTION again; check_constraints
// can throw and doesn't use the CHECK macro.
if (!HAS_PENDING_EXCEPTION) {
{ // Grabbing the Compile_lock prevents systemDictionary updates
// during compilations.
MutexLocker mu(Compile_lock, THREAD);
update_dictionary(d_index, d_hash, p_index, p_hash,
k, class_loader, THREAD);
}
if (JvmtiExport::should_post_class_load()) {
Thread *thread = THREAD;
assert(thread->is_Java_thread(), "thread->is_Java_thread()");
JvmtiExport::post_class_load((JavaThread *) thread, k());
}
}
}
if (HAS_PENDING_EXCEPTION || k.is_null()) {
// On error, clean up placeholders
{
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
SystemDictionary_lock->notify_all();
}
return NULL;
}
}
}
#ifdef ASSERT
{
Handle loader (THREAD, k->class_loader());
MutexLocker mu(SystemDictionary_lock, THREAD);
oop kk = find_class_or_placeholder(name, loader);
assert(kk == k(), "should be present in dictionary");
}
#endif
// return if the protection domain in NULL
if (protection_domain() == NULL) return k();
// Check the protection domain has the right access
{
MutexLocker mu(SystemDictionary_lock, THREAD);
// Note that we have an entry, and entries can be deleted only during GC,
// so we cannot allow GC to occur while we're holding this entry.
// We're using a No_Safepoint_Verifier to catch any place where we
// might potentially do a GC at all.
// SystemDictionary::do_unloading() asserts that classes are only
// unloaded at a safepoint.
No_Safepoint_Verifier nosafepoint;
if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
class_loader,
protection_domain)) {
return k();
}
}
// Verify protection domain. If it fails an exception is thrown
validate_protection_domain(k, class_loader, protection_domain, CHECK_(klassOop(NULL)));
return k();
}
// This routine does not lock the system dictionary.
//
// Since readers don't hold a lock, we must make sure that system
// dictionary entries are only removed at a safepoint (when only one
// thread is running), and are added to in a safe way (all links must
// be updated in an MT-safe manner).
//
// Callers should be aware that an entry could be added just after
// _dictionary->bucket(index) is read here, so the caller will not see
// the new entry.
klassOop SystemDictionary::find(symbolHandle class_name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);
int d_index = dictionary()->hash_to_index(d_hash);
{
// Note that we have an entry, and entries can be deleted only during GC,
// so we cannot allow GC to occur while we're holding this entry.
// We're using a No_Safepoint_Verifier to catch any place where we
// might potentially do a GC at all.
// SystemDictionary::do_unloading() asserts that classes are only
// unloaded at a safepoint.
No_Safepoint_Verifier nosafepoint;
return dictionary()->find(d_index, d_hash, class_name, class_loader,
protection_domain, THREAD);
}
}
// Look for a loaded instance or array klass by name. Do not do any loading.
// return NULL in case of error.
klassOop SystemDictionary::find_instance_or_array_klass(symbolHandle class_name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
klassOop k = NULL;
assert(class_name() != NULL, "class name must be non NULL");
if (FieldType::is_array(class_name())) {
// The name refers to an array. Parse the name.
jint dimension;
symbolOop object_key;
// dimension and object_key are assigned as a side-effect of this call
BasicType t = FieldType::get_array_info(class_name(), &dimension,
&object_key, CHECK_(NULL));
if (t != T_OBJECT) {
k = Universe::typeArrayKlassObj(t);
} else {
symbolHandle h_key(THREAD, object_key);
k = SystemDictionary::find(h_key, class_loader, protection_domain, THREAD);
}
if (k != NULL) {
k = Klass::cast(k)->array_klass_or_null(dimension);
}
} else {
k = find(class_name, class_loader, protection_domain, THREAD);
}
return k;
}
// Note: this method is much like resolve_from_stream, but
// updates no supplemental data structures.
// TODO consolidate the two methods with a helper routine?
klassOop SystemDictionary::parse_stream(symbolHandle class_name,
Handle class_loader,
Handle protection_domain,
ClassFileStream* st,
TRAPS) {
symbolHandle parsed_name;
// Parse the stream. Note that we do this even though this klass might
// already be present in the SystemDictionary, otherwise we would not
// throw potential ClassFormatErrors.
//
// Note: "name" is updated.
// Further note: a placeholder will be added for this class when
// super classes are loaded (resolve_super_or_fail). We expect this
// to be called for all classes but java.lang.Object; and we preload
// java.lang.Object through resolve_or_fail, not this path.
instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
class_loader,
protection_domain,
parsed_name,
THREAD);
// We don't redefine the class, so we just need to clean up whether there
// was an error or not (don't want to modify any system dictionary
// data structures).
// Parsed name could be null if we threw an error before we got far
// enough along to parse it -- in that case, there is nothing to clean up.
if (!parsed_name.is_null()) {
unsigned int p_hash = placeholders()->compute_hash(parsed_name,
class_loader);
int p_index = placeholders()->hash_to_index(p_hash);
{
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, parsed_name, class_loader, THREAD);
SystemDictionary_lock->notify_all();
}
}
return k();
}
// Add a klass to the system from a stream (called by jni_DefineClass and
// JVM_DefineClass).
// Note: class_name can be NULL. In that case we do not know the name of
// the class until we have parsed the stream.
klassOop SystemDictionary::resolve_from_stream(symbolHandle class_name,
Handle class_loader,
Handle protection_domain,
ClassFileStream* st,
TRAPS) {
// Make sure we are synchronized on the class loader before we initiate
// loading.
Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
check_loader_lock_contention(lockObject, THREAD);
ObjectLocker ol(lockObject, THREAD);
symbolHandle parsed_name;
// Parse the stream. Note that we do this even though this klass might
// already be present in the SystemDictionary, otherwise we would not
// throw potential ClassFormatErrors.
//
// Note: "name" is updated.
// Further note: a placeholder will be added for this class when
// super classes are loaded (resolve_super_or_fail). We expect this
// to be called for all classes but java.lang.Object; and we preload
// java.lang.Object through resolve_or_fail, not this path.
instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
class_loader,
protection_domain,
parsed_name,
THREAD);
const char* pkg = "java/";
if (!HAS_PENDING_EXCEPTION &&
!class_loader.is_null() &&
!parsed_name.is_null() &&
!strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
// It is illegal to define classes in the "java." package from
// JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
ResourceMark rm(THREAD);
char* name = parsed_name->as_C_string();
char* index = strrchr(name, '/');
*index = '\0'; // chop to just the package name
while ((index = strchr(name, '/')) != NULL) {
*index = '.'; // replace '/' with '.' in package name
}
const char* fmt = "Prohibited package name: %s";
size_t len = strlen(fmt) + strlen(name);
char* message = NEW_RESOURCE_ARRAY(char, len);
jio_snprintf(message, len, fmt, name);
Exceptions::_throw_msg(THREAD_AND_LOCATION,
vmSymbols::java_lang_SecurityException(), message);
}
if (!HAS_PENDING_EXCEPTION) {
assert(!parsed_name.is_null(), "Sanity");
assert(class_name.is_null() || class_name() == parsed_name(),
"name mismatch");
// Verification prevents us from creating names with dots in them, this
// asserts that that's the case.
assert(is_internal_format(parsed_name),
"external class name format used internally");
// Add class just loaded
define_instance_class(k, THREAD);
}
// If parsing the class file or define_instance_class failed, we
// need to remove the placeholder added on our behalf. But we
// must make sure parsed_name is valid first (it won't be if we had
// a format error before the class was parsed far enough to
// find the name).
if (HAS_PENDING_EXCEPTION && !parsed_name.is_null()) {
unsigned int p_hash = placeholders()->compute_hash(parsed_name,
class_loader);
int p_index = placeholders()->hash_to_index(p_hash);
{
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, parsed_name, class_loader, THREAD);
SystemDictionary_lock->notify_all();
}
return NULL;
}
// Make sure that we didn't leave a place holder in the
// SystemDictionary; this is only done on success
debug_only( {
if (!HAS_PENDING_EXCEPTION) {
assert(!parsed_name.is_null(), "parsed_name is still null?");
symbolHandle h_name (THREAD, k->name());
Handle h_loader (THREAD, k->class_loader());
MutexLocker mu(SystemDictionary_lock, THREAD);
oop check = find_class_or_placeholder(parsed_name, class_loader);
assert(check == k(), "should be present in the dictionary");
oop check2 = find_class_or_placeholder(h_name, h_loader);
assert(check == check2, "name inconsistancy in SystemDictionary");
}
} );
return k();
}
void SystemDictionary::set_shared_dictionary(HashtableBucket* t, int length,
int number_of_entries) {
assert(length == _nof_buckets * sizeof(HashtableBucket),
"bad shared dictionary size.");
_shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
}
// If there is a shared dictionary, then find the entry for the
// given shared system class, if any.
klassOop SystemDictionary::find_shared_class(symbolHandle class_name) {
if (shared_dictionary() != NULL) {
unsigned int d_hash = dictionary()->compute_hash(class_name, Handle());
int d_index = dictionary()->hash_to_index(d_hash);
return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
} else {
return NULL;
}
}
// Load a class from the shared spaces (found through the shared system
// dictionary). Force the superclass and all interfaces to be loaded.
// Update the class definition to include sibling classes and no
// subclasses (yet). [Classes in the shared space are not part of the
// object hierarchy until loaded.]
instanceKlassHandle SystemDictionary::load_shared_class(
symbolHandle class_name, Handle class_loader, TRAPS) {
instanceKlassHandle ik (THREAD, find_shared_class(class_name));
return load_shared_class(ik, class_loader, THREAD);
}
// Note well! Changes to this method may affect oop access order
// in the shared archive. Please take care to not make changes that
// adversely affect cold start time by changing the oop access order
// that is specified in dump.cpp MarkAndMoveOrderedReadOnly and
// MarkAndMoveOrderedReadWrite closures.
instanceKlassHandle SystemDictionary::load_shared_class(
instanceKlassHandle ik, Handle class_loader, TRAPS) {
assert(class_loader.is_null(), "non-null classloader for shared class?");
if (ik.not_null()) {
instanceKlassHandle nh = instanceKlassHandle(); // null Handle
symbolHandle class_name(THREAD, ik->name());
// Found the class, now load the superclass and interfaces. If they
// are shared, add them to the main system dictionary and reset
// their hierarchy references (supers, subs, and interfaces).
if (ik->super() != NULL) {
symbolHandle cn(THREAD, ik->super()->klass_part()->name());
resolve_super_or_fail(class_name, cn,
class_loader, Handle(), true, CHECK_(nh));
}
objArrayHandle interfaces (THREAD, ik->local_interfaces());
int num_interfaces = interfaces->length();
for (int index = 0; index < num_interfaces; index++) {
klassOop k = klassOop(interfaces->obj_at(index));
// Note: can not use instanceKlass::cast here because
// interfaces' instanceKlass's C++ vtbls haven't been
// reinitialized yet (they will be once the interface classes
// are loaded)
symbolHandle name (THREAD, k->klass_part()->name());
resolve_super_or_fail(class_name, name, class_loader, Handle(), false, CHECK_(nh));
}
// Adjust methods to recover missing data. They need addresses for
// interpreter entry points and their default native method address
// must be reset.
// Updating methods must be done under a lock so multiple
// threads don't update these in parallel
// Shared classes are all currently loaded by the bootstrap
// classloader, so this will never cause a deadlock on
// a custom class loader lock.
{
Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
check_loader_lock_contention(lockObject, THREAD);
ObjectLocker ol(lockObject, THREAD, true);
objArrayHandle methods (THREAD, ik->methods());
int num_methods = methods->length();
for (int index2 = 0; index2 < num_methods; ++index2) {
methodHandle m(THREAD, methodOop(methods->obj_at(index2)));
m()->link_method(m, CHECK_(nh));
}
}
if (TraceClassLoading) {
ResourceMark rm;
tty->print("[Loaded %s", ik->external_name());
tty->print(" from shared objects file");
tty->print_cr("]");
}
// notify a class loaded from shared object
ClassLoadingService::notify_class_loaded(instanceKlass::cast(ik()),
true /* shared class */);
}
return ik;
}
#ifdef KERNEL
// Some classes on the bootstrap class path haven't been installed on the
// system yet. Call the DownloadManager method to make them appear in the
// bootstrap class path and try again to load the named class.
// Note that with delegation class loaders all classes in another loader will
// first try to call this so it'd better be fast!!
static instanceKlassHandle download_and_retry_class_load(
symbolHandle class_name,
TRAPS) {
klassOop dlm = SystemDictionary::sun_jkernel_DownloadManager_klass();
instanceKlassHandle nk;
// If download manager class isn't loaded just return.
if (dlm == NULL) return nk;
{ HandleMark hm(THREAD);
ResourceMark rm(THREAD);
Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nk));
Handle class_string = java_lang_String::externalize_classname(s, CHECK_(nk));
// return value
JavaValue result(T_OBJECT);
// Call the DownloadManager. We assume that it has a lock because
// multiple classes could be not found and downloaded at the same time.
// class sun.misc.DownloadManager;
// public static String getBootClassPathEntryForClass(String className);
JavaCalls::call_static(&result,
KlassHandle(THREAD, dlm),
vmSymbolHandles::getBootClassPathEntryForClass_name(),
vmSymbolHandles::string_string_signature(),
class_string,
CHECK_(nk));
// Get result.string and add to bootclasspath
assert(result.get_type() == T_OBJECT, "just checking");
oop obj = (oop) result.get_jobject();
if (obj == NULL) { return nk; }
char* new_class_name = java_lang_String::as_utf8_string(obj);
// lock the loader
// we use this lock because JVMTI does.
Handle loader_lock(THREAD, SystemDictionary::system_loader_lock());
ObjectLocker ol(loader_lock, THREAD);
// add the file to the bootclasspath
ClassLoader::update_class_path_entry_list(new_class_name, true);
} // end HandleMark
if (TraceClassLoading) {
ClassLoader::print_bootclasspath();
}
return ClassLoader::load_classfile(class_name, CHECK_(nk));
}
#endif // KERNEL
instanceKlassHandle SystemDictionary::load_instance_class(symbolHandle class_name, Handle class_loader, TRAPS) {
instanceKlassHandle nh = instanceKlassHandle(); // null Handle
if (class_loader.is_null()) {
// Search the shared system dictionary for classes preloaded into the
// shared spaces.
instanceKlassHandle k;
k = load_shared_class(class_name, class_loader, THREAD);
if (k.is_null()) {
// Use VM class loader
k = ClassLoader::load_classfile(class_name, CHECK_(nh));
}
#ifdef KERNEL
// If the VM class loader has failed to load the class, call the
// DownloadManager class to make it magically appear on the classpath
// and try again. This is only configured with the Kernel VM.
if (k.is_null()) {
k = download_and_retry_class_load(class_name, CHECK_(nh));
}
#endif // KERNEL
// find_or_define_instance_class may return a different k
if (!k.is_null()) {
k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
}
return k;
} else {
// Use user specified class loader to load class. Call loadClass operation on class_loader.
ResourceMark rm(THREAD);
Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
// Translate to external class name format, i.e., convert '/' chars to '.'
Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
JavaValue result(T_OBJECT);
KlassHandle spec_klass (THREAD, SystemDictionary::classloader_klass());
// UnsyncloadClass option means don't synchronize loadClass() calls.
// loadClassInternal() is synchronized and public loadClass(String) is not.
// This flag is for diagnostic purposes only. It is risky to call
// custom class loaders without synchronization.
// WARNING If a custom class loader does NOT synchronizer findClass, or callers of
// findClass, this flag risks unexpected timing bugs in the field.
// Do NOT assume this will be supported in future releases.
if (!UnsyncloadClass && has_loadClassInternal()) {
JavaCalls::call_special(&result,
class_loader,
spec_klass,
vmSymbolHandles::loadClassInternal_name(),
vmSymbolHandles::string_class_signature(),
string,
CHECK_(nh));
} else {
JavaCalls::call_virtual(&result,
class_loader,
spec_klass,
vmSymbolHandles::loadClass_name(),
vmSymbolHandles::string_class_signature(),
string,
CHECK_(nh));
}
assert(result.get_type() == T_OBJECT, "just checking");
oop obj = (oop) result.get_jobject();
// Primitive classes return null since forName() can not be
// used to obtain any of the Class objects representing primitives or void
if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
instanceKlassHandle k =
instanceKlassHandle(THREAD, java_lang_Class::as_klassOop(obj));
// For user defined Java class loaders, check that the name returned is
// the same as that requested. This check is done for the bootstrap
// loader when parsing the class file.
if (class_name() == k->name()) {
return k;
}
}
// Class is not found or has the wrong name, return NULL
return nh;
}
}
void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
Handle class_loader_h(THREAD, k->class_loader());
// for bootstrap classloader don't acquire lock
if (!class_loader_h.is_null()) {
assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
compute_loader_lock_object(class_loader_h, THREAD)),
"define called without lock");
}
// Check class-loading constraints. Throw exception if violation is detected.
// Grabs and releases SystemDictionary_lock
// The check_constraints/find_class call and update_dictionary sequence
// must be "atomic" for a specific class/classloader pair so we never
// define two different instanceKlasses for that class/classloader pair.
// Existing classloaders will call define_instance_class with the
// classloader lock held
// Parallel classloaders will call find_or_define_instance_class
// which will require a token to perform the define class
symbolHandle name_h(THREAD, k->name());
unsigned int d_hash = dictionary()->compute_hash(name_h, class_loader_h);
int d_index = dictionary()->hash_to_index(d_hash);
check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
// Register class just loaded with class loader (placed in Vector)
// Note we do this before updating the dictionary, as this can
// fail with an OutOfMemoryError (if it does, we will *not* put this
// class in the dictionary and will not update the class hierarchy).
if (k->class_loader() != NULL) {
methodHandle m(THREAD, Universe::loader_addClass_method());
JavaValue result(T_VOID);
JavaCallArguments args(class_loader_h);
args.push_oop(Handle(THREAD, k->java_mirror()));
JavaCalls::call(&result, m, &args, CHECK);
}
// Add the new class. We need recompile lock during update of CHA.
{
unsigned int p_hash = placeholders()->compute_hash(name_h, class_loader_h);
int p_index = placeholders()->hash_to_index(p_hash);
MutexLocker mu_r(Compile_lock, THREAD);
// Add to class hierarchy, initialize vtables, and do possible
// deoptimizations.
add_to_hierarchy(k, CHECK); // No exception, but can block
// Add to systemDictionary - so other classes can see it.
// Grabs and releases SystemDictionary_lock
update_dictionary(d_index, d_hash, p_index, p_hash,
k, class_loader_h, THREAD);
}
k->eager_initialize(THREAD);
// notify jvmti
if (JvmtiExport::should_post_class_load()) {
assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
JvmtiExport::post_class_load((JavaThread *) THREAD, k());
}
}
// Support parallel classloading
// Initial implementation for bootstrap classloader
// For future:
// For custom class loaders that support parallel classloading,
// in case they do not synchronize around
// FindLoadedClass/DefineClass calls, we check for parallel
// loading for them, wait if a defineClass is in progress
// and return the initial requestor's results
// For better performance, the class loaders should synchronize
// findClass(), i.e. FindLoadedClass/DefineClass or they
// potentially waste time reading and parsing the bytestream.
// Note: VM callers should ensure consistency of k/class_name,class_loader
instanceKlassHandle SystemDictionary::find_or_define_instance_class(symbolHandle class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
instanceKlassHandle nh = instanceKlassHandle(); // null Handle
unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);
int d_index = dictionary()->hash_to_index(d_hash);
// Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
unsigned int p_hash = placeholders()->compute_hash(class_name, class_loader);
int p_index = placeholders()->hash_to_index(p_hash);
PlaceholderEntry* probe;
{
MutexLocker mu(SystemDictionary_lock, THREAD);
// First check if class already defined
klassOop check = find_class(d_index, d_hash, class_name, class_loader);
if (check != NULL) {
return(instanceKlassHandle(THREAD, check));
}
// Acquire define token for this class/classloader
symbolHandle nullsymbolHandle;
probe = placeholders()->find_and_add(p_index, p_hash, class_name, class_loader, PlaceholderTable::DEFINE_CLASS, nullsymbolHandle, THREAD);
// Check if another thread defining in parallel
if (probe->definer() == NULL) {
// Thread will define the class
probe->set_definer(THREAD);
} else {
// Wait for defining thread to finish and return results
while (probe->definer() != NULL) {
SystemDictionary_lock->wait();
}
if (probe->instanceKlass() != NULL) {
probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);
return(instanceKlassHandle(THREAD, probe->instanceKlass()));
} else {
// If definer had an error, try again as any new thread would
probe->set_definer(THREAD);
#ifdef ASSERT
klassOop check = find_class(d_index, d_hash, class_name, class_loader);
assert(check == NULL, "definer missed recording success");
#endif
}
}
}
define_instance_class(k, THREAD);
Handle linkage_exception = Handle(); // null handle
// definer must notify any waiting threads
{
MutexLocker mu(SystemDictionary_lock, THREAD);
PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, class_name, class_loader);
assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
if (probe != NULL) {
if (HAS_PENDING_EXCEPTION) {
linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
CLEAR_PENDING_EXCEPTION;
} else {
probe->set_instanceKlass(k());
}
probe->set_definer(NULL);
probe->remove_seen_thread(THREAD, PlaceholderTable::DEFINE_CLASS);
SystemDictionary_lock->notify_all();
}
}
// Can't throw exception while holding lock due to rank ordering
if (linkage_exception() != NULL) {
THROW_OOP_(linkage_exception(), nh); // throws exception and returns
}
return k;
}
Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
// If class_loader is NULL we synchronize on _system_loader_lock_obj
if (class_loader.is_null()) {
return Handle(THREAD, _system_loader_lock_obj);
} else {
return class_loader;
}
}
// This method is added to check how often we have to wait to grab loader
// lock. The results are being recorded in the performance counters defined in
// ClassLoader::_sync_systemLoaderLockContentionRate and
// ClassLoader::_sync_nonSystemLoaderLockConteionRate.
void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
if (!UsePerfData) {
return;
}
assert(!loader_lock.is_null(), "NULL lock object");
if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
== ObjectSynchronizer::owner_other) {
// contention will likely happen, so increment the corresponding
// contention counter.
if (loader_lock() == _system_loader_lock_obj) {
ClassLoader::sync_systemLoaderLockContentionRate()->inc();
} else {
ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
}
}
}
// ----------------------------------------------------------------------------
// Lookup
klassOop SystemDictionary::find_class(int index, unsigned int hash,
symbolHandle class_name,
Handle class_loader) {
assert_locked_or_safepoint(SystemDictionary_lock);
assert (index == dictionary()->index_for(class_name, class_loader),
"incorrect index?");
klassOop k = dictionary()->find_class(index, hash, class_name, class_loader);
return k;
}
// Basic find on classes in the midst of being loaded
symbolOop SystemDictionary::find_placeholder(int index, unsigned int hash,
symbolHandle class_name,
Handle class_loader) {
assert_locked_or_safepoint(SystemDictionary_lock);
return placeholders()->find_entry(index, hash, class_name, class_loader);
}
// Used for assertions and verification only
oop SystemDictionary::find_class_or_placeholder(symbolHandle class_name,
Handle class_loader) {
#ifndef ASSERT
guarantee(VerifyBeforeGC ||
VerifyDuringGC ||
VerifyBeforeExit ||
VerifyAfterGC, "too expensive");
#endif
assert_locked_or_safepoint(SystemDictionary_lock);
symbolOop class_name_ = class_name();
oop class_loader_ = class_loader();
// First look in the loaded class array
unsigned int d_hash = dictionary()->compute_hash(class_name, class_loader);
int d_index = dictionary()->hash_to_index(d_hash);
oop lookup = find_class(d_index, d_hash, class_name, class_loader);
if (lookup == NULL) {
// Next try the placeholders
unsigned int p_hash = placeholders()->compute_hash(class_name,class_loader);
int p_index = placeholders()->hash_to_index(p_hash);
lookup = find_placeholder(p_index, p_hash, class_name, class_loader);
}
return lookup;
}
// Get the next class in the diictionary.
klassOop SystemDictionary::try_get_next_class() {
return dictionary()->try_get_next_class();
}
// ----------------------------------------------------------------------------
// Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
// is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
// before a new class is used.
void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
assert(k.not_null(), "just checking");
// Link into hierachy. Make sure the vtables are initialized before linking into
k->append_to_sibling_list(); // add to superklass/sibling list
k->process_interfaces(THREAD); // handle all "implements" declarations
k->set_init_state(instanceKlass::loaded);
// Now flush all code that depended on old class hierarchy.
// Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
// Also, first reinitialize vtable because it may have gotten out of synch
// while the new class wasn't connected to the class hierarchy.
Universe::flush_dependents_on(k);
}
// ----------------------------------------------------------------------------
// GC support
// Following roots during mark-sweep is separated in two phases.
//
// The first phase follows preloaded classes and all other system
// classes, since these will never get unloaded anyway.
//
// The second phase removes (unloads) unreachable classes from the
// system dictionary and follows the remaining classes' contents.
void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
// Follow preloaded classes/mirrors and system loader object
blk->do_oop(&_java_system_loader);
preloaded_oops_do(blk);
always_strong_classes_do(blk);
}
void SystemDictionary::always_strong_classes_do(OopClosure* blk) {
// Follow all system classes and temporary placeholders in dictionary
dictionary()->always_strong_classes_do(blk);
// Placeholders. These are *always* strong roots, as they
// represent classes we're actively loading.
placeholders_do(blk);
// Loader constraints. We must keep the symbolOop used in the name alive.
constraints()->always_strong_classes_do(blk);
// Resolution errors keep the symbolOop for the error alive
resolution_errors()->always_strong_classes_do(blk);
}
void SystemDictionary::placeholders_do(OopClosure* blk) {
placeholders()->oops_do(blk);
}
bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
bool result = dictionary()->do_unloading(is_alive);
constraints()->purge_loader_constraints(is_alive);
resolution_errors()->purge_resolution_errors(is_alive);
return result;
}
// The mirrors are scanned by shared_oops_do() which is
// not called by oops_do(). In order to process oops in
// a necessary order, shared_oops_do() is call by
// Universe::oops_do().
void SystemDictionary::oops_do(OopClosure* f) {
// Adjust preloaded classes and system loader object
f->do_oop(&_java_system_loader);
preloaded_oops_do(f);
lazily_loaded_oops_do(f);
// Adjust dictionary
dictionary()->oops_do(f);
// Partially loaded classes
placeholders()->oops_do(f);
// Adjust constraint table
constraints()->oops_do(f);
// Adjust resolution error table
resolution_errors()->oops_do(f);
}
void SystemDictionary::preloaded_oops_do(OopClosure* f) {
f->do_oop((oop*) &_string_klass);
f->do_oop((oop*) &_object_klass);
f->do_oop((oop*) &_class_klass);
f->do_oop((oop*) &_cloneable_klass);
f->do_oop((oop*) &_classloader_klass);
f->do_oop((oop*) &_serializable_klass);
f->do_oop((oop*) &_system_klass);
f->do_oop((oop*) &_throwable_klass);
f->do_oop((oop*) &_error_klass);
f->do_oop((oop*) &_threaddeath_klass);
f->do_oop((oop*) &_exception_klass);
f->do_oop((oop*) &_runtime_exception_klass);
f->do_oop((oop*) &_classNotFoundException_klass);
f->do_oop((oop*) &_noClassDefFoundError_klass);
f->do_oop((oop*) &_linkageError_klass);
f->do_oop((oop*) &_classCastException_klass);
f->do_oop((oop*) &_arrayStoreException_klass);
f->do_oop((oop*) &_virtualMachineError_klass);
f->do_oop((oop*) &_outOfMemoryError_klass);
f->do_oop((oop*) &_StackOverflowError_klass);
f->do_oop((oop*) &_illegalMonitorStateException_klass);
f->do_oop((oop*) &_protectionDomain_klass);
f->do_oop((oop*) &_AccessControlContext_klass);
f->do_oop((oop*) &_reference_klass);
f->do_oop((oop*) &_soft_reference_klass);
f->do_oop((oop*) &_weak_reference_klass);
f->do_oop((oop*) &_final_reference_klass);
f->do_oop((oop*) &_phantom_reference_klass);
f->do_oop((oop*) &_finalizer_klass);
f->do_oop((oop*) &_thread_klass);
f->do_oop((oop*) &_threadGroup_klass);
f->do_oop((oop*) &_properties_klass);
f->do_oop((oop*) &_reflect_accessible_object_klass);
f->do_oop((oop*) &_reflect_field_klass);
f->do_oop((oop*) &_reflect_method_klass);
f->do_oop((oop*) &_reflect_constructor_klass);
f->do_oop((oop*) &_reflect_magic_klass);
f->do_oop((oop*) &_reflect_method_accessor_klass);
f->do_oop((oop*) &_reflect_constructor_accessor_klass);
f->do_oop((oop*) &_reflect_delegating_classloader_klass);
f->do_oop((oop*) &_reflect_constant_pool_klass);
f->do_oop((oop*) &_reflect_unsafe_static_field_accessor_impl_klass);
f->do_oop((oop*) &_stringBuffer_klass);
f->do_oop((oop*) &_vector_klass);
f->do_oop((oop*) &_hashtable_klass);
f->do_oop((oop*) &_stackTraceElement_klass);
f->do_oop((oop*) &_java_nio_Buffer_klass);
f->do_oop((oop*) &_sun_misc_AtomicLongCSImpl_klass);
f->do_oop((oop*) &_sun_jkernel_DownloadManager_klass);
f->do_oop((oop*) &_boolean_klass);
f->do_oop((oop*) &_char_klass);
f->do_oop((oop*) &_float_klass);
f->do_oop((oop*) &_double_klass);
f->do_oop((oop*) &_byte_klass);
f->do_oop((oop*) &_short_klass);
f->do_oop((oop*) &_int_klass);
f->do_oop((oop*) &_long_klass);
{
for (int i = 0; i < T_VOID+1; i++) {
if (_box_klasses[i] != NULL) {
assert(i >= T_BOOLEAN, "checking");
f->do_oop((oop*) &_box_klasses[i]);
}
}
}
// The basic type mirrors would have already been processed in
// Universe::oops_do(), via a call to shared_oops_do(), so should
// not be processed again.
f->do_oop((oop*) &_system_loader_lock_obj);
FilteredFieldsMap::klasses_oops_do(f);
}
void SystemDictionary::lazily_loaded_oops_do(OopClosure* f) {
f->do_oop((oop*) &_abstract_ownable_synchronizer_klass);
}
// Just the classes from defining class loaders
// Don't iterate over placeholders
void SystemDictionary::classes_do(void f(klassOop)) {
dictionary()->classes_do(f);
}
// Added for initialize_itable_for_klass
// Just the classes from defining class loaders
// Don't iterate over placeholders
void SystemDictionary::classes_do(void f(klassOop, TRAPS), TRAPS) {
dictionary()->classes_do(f, CHECK);
}
// All classes, and their class loaders
// Don't iterate over placeholders
void SystemDictionary::classes_do(void f(klassOop, oop)) {
dictionary()->classes_do(f);
}
// All classes, and their class loaders
// (added for helpers that use HandleMarks and ResourceMarks)
// Don't iterate over placeholders
void SystemDictionary::classes_do(void f(klassOop, oop, TRAPS), TRAPS) {
dictionary()->classes_do(f, CHECK);
}
void SystemDictionary::placeholders_do(void f(symbolOop, oop)) {
placeholders()->entries_do(f);
}
void SystemDictionary::methods_do(void f(methodOop)) {
dictionary()->methods_do(f);
}
// ----------------------------------------------------------------------------
// Lazily load klasses
void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
assert(JDK_Version::is_gte_jdk16x_version(), "Must be JDK 1.6 or later");
// if multiple threads calling this function, only one thread will load
// the class. The other threads will find the loaded version once the
// class is loaded.
klassOop aos = _abstract_ownable_synchronizer_klass;
if (aos == NULL) {
klassOop k = resolve_or_fail(vmSymbolHandles::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
// Force a fence to prevent any read before the write completes
OrderAccess::fence();
_abstract_ownable_synchronizer_klass = k;
}
}
// ----------------------------------------------------------------------------
// Initialization
void SystemDictionary::initialize(TRAPS) {
// Allocate arrays
assert(dictionary() == NULL,
"SystemDictionary should only be initialized once");
_dictionary = new Dictionary(_nof_buckets);
_placeholders = new PlaceholderTable(_nof_buckets);
_number_of_modifications = 0;
_loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
_resolution_errors = new ResolutionErrorTable(_resolution_error_size);
// Allocate private object used as system class loader lock
_system_loader_lock_obj = oopFactory::new_system_objArray(0, CHECK);
// Initialize basic classes
initialize_preloaded_classes(CHECK);
}
void SystemDictionary::initialize_preloaded_classes(TRAPS) {
assert(_object_klass == NULL, "preloaded classes should only be initialized once");
// Preload commonly used klasses
_object_klass = resolve_or_fail(vmSymbolHandles::java_lang_Object(), true, CHECK);
_string_klass = resolve_or_fail(vmSymbolHandles::java_lang_String(), true, CHECK);
_class_klass = resolve_or_fail(vmSymbolHandles::java_lang_Class(), true, CHECK);
debug_only(instanceKlass::verify_class_klass_nonstatic_oop_maps(_class_klass));
// Fixup mirrors for classes loaded before java.lang.Class.
// These calls iterate over the objects currently in the perm gen
// so calling them at this point is matters (not before when there
// are fewer objects and not later after there are more objects
// in the perm gen.
Universe::initialize_basic_type_mirrors(CHECK);
Universe::fixup_mirrors(CHECK);
_cloneable_klass = resolve_or_fail(vmSymbolHandles::java_lang_Cloneable(), true, CHECK);
_classloader_klass = resolve_or_fail(vmSymbolHandles::java_lang_ClassLoader(), true, CHECK);
_serializable_klass = resolve_or_fail(vmSymbolHandles::java_io_Serializable(), true, CHECK);
_system_klass = resolve_or_fail(vmSymbolHandles::java_lang_System(), true, CHECK);
_throwable_klass = resolve_or_fail(vmSymbolHandles::java_lang_Throwable(), true, CHECK);
_error_klass = resolve_or_fail(vmSymbolHandles::java_lang_Error(), true, CHECK);
_threaddeath_klass = resolve_or_fail(vmSymbolHandles::java_lang_ThreadDeath(), true, CHECK);
_exception_klass = resolve_or_fail(vmSymbolHandles::java_lang_Exception(), true, CHECK);
_runtime_exception_klass = resolve_or_fail(vmSymbolHandles::java_lang_RuntimeException(), true, CHECK);
_protectionDomain_klass = resolve_or_fail(vmSymbolHandles::java_security_ProtectionDomain(), true, CHECK);
_AccessControlContext_klass = resolve_or_fail(vmSymbolHandles::java_security_AccessControlContext(), true, CHECK);
_classNotFoundException_klass = resolve_or_fail(vmSymbolHandles::java_lang_ClassNotFoundException(), true, CHECK);
_noClassDefFoundError_klass = resolve_or_fail(vmSymbolHandles::java_lang_NoClassDefFoundError(), true, CHECK);
_linkageError_klass = resolve_or_fail(vmSymbolHandles::java_lang_LinkageError(), true, CHECK);
_classCastException_klass = resolve_or_fail(vmSymbolHandles::java_lang_ClassCastException(), true, CHECK);
_arrayStoreException_klass = resolve_or_fail(vmSymbolHandles::java_lang_ArrayStoreException(), true, CHECK);
_virtualMachineError_klass = resolve_or_fail(vmSymbolHandles::java_lang_VirtualMachineError(), true, CHECK);
_outOfMemoryError_klass = resolve_or_fail(vmSymbolHandles::java_lang_OutOfMemoryError(), true, CHECK);
_StackOverflowError_klass = resolve_or_fail(vmSymbolHandles::java_lang_StackOverflowError(), true, CHECK);
_illegalMonitorStateException_klass = resolve_or_fail(vmSymbolHandles::java_lang_IllegalMonitorStateException(), true, CHECK);
// Preload ref klasses and set reference types
_reference_klass = resolve_or_fail(vmSymbolHandles::java_lang_ref_Reference(), true, CHECK);
instanceKlass::cast(_reference_klass)->set_reference_type(REF_OTHER);
instanceRefKlass::update_nonstatic_oop_maps(_reference_klass);
_soft_reference_klass = resolve_or_fail(vmSymbolHandles::java_lang_ref_SoftReference(), true, CHECK);
instanceKlass::cast(_soft_reference_klass)->set_reference_type(REF_SOFT);
_weak_reference_klass = resolve_or_fail(vmSymbolHandles::java_lang_ref_WeakReference(), true, CHECK);
instanceKlass::cast(_weak_reference_klass)->set_reference_type(REF_WEAK);
_final_reference_klass = resolve_or_fail(vmSymbolHandles::java_lang_ref_FinalReference(), true, CHECK);
instanceKlass::cast(_final_reference_klass)->set_reference_type(REF_FINAL);
_phantom_reference_klass = resolve_or_fail(vmSymbolHandles::java_lang_ref_PhantomReference(), true, CHECK);
instanceKlass::cast(_phantom_reference_klass)->set_reference_type(REF_PHANTOM);
_finalizer_klass = resolve_or_fail(vmSymbolHandles::java_lang_ref_Finalizer(), true, CHECK);
_thread_klass = resolve_or_fail(vmSymbolHandles::java_lang_Thread(), true, CHECK);
_threadGroup_klass = resolve_or_fail(vmSymbolHandles::java_lang_ThreadGroup(), true, CHECK);
_properties_klass = resolve_or_fail(vmSymbolHandles::java_util_Properties(), true, CHECK);
_reflect_accessible_object_klass = resolve_or_fail(vmSymbolHandles::java_lang_reflect_AccessibleObject(), true, CHECK);
_reflect_field_klass = resolve_or_fail(vmSymbolHandles::java_lang_reflect_Field(), true, CHECK);
_reflect_method_klass = resolve_or_fail(vmSymbolHandles::java_lang_reflect_Method(), true, CHECK);
_reflect_constructor_klass = resolve_or_fail(vmSymbolHandles::java_lang_reflect_Constructor(), true, CHECK);
// Universe::is_gte_jdk14x_version() is not set up by this point.
// It's okay if these turn out to be NULL in non-1.4 JDKs.
_reflect_magic_klass = resolve_or_null(vmSymbolHandles::sun_reflect_MagicAccessorImpl(), CHECK);
_reflect_method_accessor_klass = resolve_or_null(vmSymbolHandles::sun_reflect_MethodAccessorImpl(), CHECK);
_reflect_constructor_accessor_klass = resolve_or_null(vmSymbolHandles::sun_reflect_ConstructorAccessorImpl(), CHECK);
_reflect_delegating_classloader_klass = resolve_or_null(vmSymbolHandles::sun_reflect_DelegatingClassLoader(), CHECK);
_reflect_constant_pool_klass = resolve_or_null(vmSymbolHandles::sun_reflect_ConstantPool(), CHECK);
_reflect_unsafe_static_field_accessor_impl_klass = resolve_or_null(vmSymbolHandles::sun_reflect_UnsafeStaticFieldAccessorImpl(), CHECK);
_vector_klass = resolve_or_fail(vmSymbolHandles::java_util_Vector(), true, CHECK);
_hashtable_klass = resolve_or_fail(vmSymbolHandles::java_util_Hashtable(), true, CHECK);
_stringBuffer_klass = resolve_or_fail(vmSymbolHandles::java_lang_StringBuffer(), true, CHECK);
// It's NULL in non-1.4 JDKs.
_stackTraceElement_klass = resolve_or_null(vmSymbolHandles::java_lang_StackTraceElement(), CHECK);
// Universe::is_gte_jdk14x_version() is not set up by this point.
// It's okay if this turns out to be NULL in non-1.4 JDKs.
_java_nio_Buffer_klass = resolve_or_null(vmSymbolHandles::java_nio_Buffer(), CHECK);
// If this class isn't present, it won't be referenced.
_sun_misc_AtomicLongCSImpl_klass = resolve_or_null(vmSymbolHandles::sun_misc_AtomicLongCSImpl(), CHECK);
#ifdef KERNEL
_sun_jkernel_DownloadManager_klass = resolve_or_null(vmSymbolHandles::sun_jkernel_DownloadManager(), CHECK);
if (_sun_jkernel_DownloadManager_klass == NULL) {
warning("Cannot find sun/jkernel/DownloadManager");
}
#endif // KERNEL
// Preload boxing klasses
_boolean_klass = resolve_or_fail(vmSymbolHandles::java_lang_Boolean(), true, CHECK);
_char_klass = resolve_or_fail(vmSymbolHandles::java_lang_Character(), true, CHECK);
_float_klass = resolve_or_fail(vmSymbolHandles::java_lang_Float(), true, CHECK);
_double_klass = resolve_or_fail(vmSymbolHandles::java_lang_Double(), true, CHECK);
_byte_klass = resolve_or_fail(vmSymbolHandles::java_lang_Byte(), true, CHECK);
_short_klass = resolve_or_fail(vmSymbolHandles::java_lang_Short(), true, CHECK);
_int_klass = resolve_or_fail(vmSymbolHandles::java_lang_Integer(), true, CHECK);
_long_klass = resolve_or_fail(vmSymbolHandles::java_lang_Long(), true, CHECK);
_box_klasses[T_BOOLEAN] = _boolean_klass;
_box_klasses[T_CHAR] = _char_klass;
_box_klasses[T_FLOAT] = _float_klass;
_box_klasses[T_DOUBLE] = _double_klass;
_box_klasses[T_BYTE] = _byte_klass;
_box_klasses[T_SHORT] = _short_klass;
_box_klasses[T_INT] = _int_klass;
_box_klasses[T_LONG] = _long_klass;
//_box_klasses[T_OBJECT] = _object_klass;
//_box_klasses[T_ARRAY] = _object_klass;
{ // Compute whether we should use loadClass or loadClassInternal when loading classes.
methodOop method = instanceKlass::cast(classloader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
_has_loadClassInternal = (method != NULL);
}
{ // Compute whether we should use checkPackageAccess or NOT
methodOop method = instanceKlass::cast(classloader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
_has_checkPackageAccess = (method != NULL);
}
}
// Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
// If so, returns the basic type it holds. If not, returns T_OBJECT.
BasicType SystemDictionary::box_klass_type(klassOop k) {
assert(k != NULL, "");
for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
if (_box_klasses[i] == k)
return (BasicType)i;
}
return T_OBJECT;
}
// Constraints on class loaders. The details of the algorithm can be
// found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
// Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
// that the system dictionary needs to maintain a set of contraints that
// must be satisfied by all classes in the dictionary.
// if defining is true, then LinkageError if already in systemDictionary
// if initiating loader, then ok if instanceKlass matches existing entry
void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
instanceKlassHandle k,
Handle class_loader, bool defining,
TRAPS) {
const char *linkage_error = NULL;
{
symbolHandle name (THREAD, k->name());
MutexLocker mu(SystemDictionary_lock, THREAD);
klassOop check = find_class(d_index, d_hash, name, class_loader);
if (check != (klassOop)NULL) {
// if different instanceKlass - duplicate class definition,
// else - ok, class loaded by a different thread in parallel,
// we should only have found it if it was done loading and ok to use
// system dictionary only holds instance classes, placeholders
// also holds array classes
assert(check->klass_part()->oop_is_instance(), "noninstance in systemdictionary");
if ((defining == true) || (k() != check)) {
linkage_error = "loader (instance of %s): attempted duplicate class "
"definition for name: \"%s\"";
} else {
return;
}
}
#ifdef ASSERT
unsigned int p_hash = placeholders()->compute_hash(name, class_loader);
int p_index = placeholders()->hash_to_index(p_hash);
symbolOop ph_check = find_placeholder(p_index, p_hash, name, class_loader);
assert(ph_check == NULL || ph_check == name(), "invalid symbol");
#endif
if (linkage_error == NULL) {
if (constraints()->check_or_update(k, class_loader, name) == false) {
linkage_error = "loader constraint violation: loader (instance of %s)"
" previously initiated loading for a different type with name \"%s\"";
}
}
}
// Throw error now if needed (cannot throw while holding
// SystemDictionary_lock because of rank ordering)
if (linkage_error) {
ResourceMark rm(THREAD);
const char* class_loader_name = loader_name(class_loader());
char* type_name = k->name()->as_C_string();
size_t buflen = strlen(linkage_error) + strlen(class_loader_name) +
strlen(type_name);
char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name);
THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
}
}
// Update system dictionary - done after check_constraint and add_to_hierachy
// have been called.
void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
int p_index, unsigned int p_hash,
instanceKlassHandle k,
Handle class_loader,
TRAPS) {
// Compile_lock prevents systemDictionary updates during compilations
assert_locked_or_safepoint(Compile_lock);
symbolHandle name (THREAD, k->name());
{
MutexLocker mu1(SystemDictionary_lock, THREAD);
// See whether biased locking is enabled and if so set it for this
// klass.
// Note that this must be done past the last potential blocking
// point / safepoint. We enable biased locking lazily using a
// VM_Operation to iterate the SystemDictionary and installing the
// biasable mark word into each instanceKlass's prototype header.
// To avoid race conditions where we accidentally miss enabling the
// optimization for one class in the process of being added to the
// dictionary, we must not safepoint after the test of
// BiasedLocking::enabled().
if (UseBiasedLocking && BiasedLocking::enabled()) {
// Set biased locking bit for all loaded classes; it will be
// cleared if revocation occurs too often for this type
// NOTE that we must only do this when the class is initally
// defined, not each time it is referenced from a new class loader
if (k->class_loader() == class_loader()) {
k->set_prototype_header(markOopDesc::biased_locking_prototype());
}
}
// Check for a placeholder. If there, remove it and make a
// new system dictionary entry.
placeholders()->find_and_remove(p_index, p_hash, name, class_loader, THREAD);
klassOop sd_check = find_class(d_index, d_hash, name, class_loader);
if (sd_check == NULL) {
dictionary()->add_klass(name, class_loader, k);
notice_modification();
}
#ifdef ASSERT
sd_check = find_class(d_index, d_hash, name, class_loader);
assert (sd_check != NULL, "should have entry in system dictionary");
// Changed to allow PH to remain to complete class circularity checking
// while only one thread can define a class at one time, multiple
// classes can resolve the superclass for a class at one time,
// and the placeholder is used to track that
// symbolOop ph_check = find_placeholder(p_index, p_hash, name, class_loader);
// assert (ph_check == NULL, "should not have a placeholder entry");
#endif
SystemDictionary_lock->notify_all();
}
}
klassOop SystemDictionary::find_constrained_instance_or_array_klass(
symbolHandle class_name, Handle class_loader, TRAPS) {
// First see if it has been loaded directly.
// Force the protection domain to be null. (This removes protection checks.)
Handle no_protection_domain;
klassOop klass = find_instance_or_array_klass(class_name, class_loader,
no_protection_domain, CHECK_NULL);
if (klass != NULL)
return klass;
// Now look to see if it has been loaded elsewhere, and is subject to
// a loader constraint that would require this loader to return the
// klass that is already loaded.
if (FieldType::is_array(class_name())) {
// Array classes are hard because their klassOops are not kept in the
// constraint table. The array klass may be constrained, but the elem class
// may not be.
jint dimension;
symbolOop object_key;
BasicType t = FieldType::get_array_info(class_name(), &dimension,
&object_key, CHECK_(NULL));
if (t != T_OBJECT) {
klass = Universe::typeArrayKlassObj(t);
} else {
symbolHandle elem_name(THREAD, object_key);
MutexLocker mu(SystemDictionary_lock, THREAD);
klass = constraints()->find_constrained_elem_klass(class_name, elem_name, class_loader, THREAD);
}
if (klass != NULL) {
klass = Klass::cast(klass)->array_klass_or_null(dimension);
}
} else {
MutexLocker mu(SystemDictionary_lock, THREAD);
// Non-array classes are easy: simply check the constraint table.
klass = constraints()->find_constrained_klass(class_name, class_loader);
}
return klass;
}
bool SystemDictionary::add_loader_constraint(symbolHandle class_name,
Handle class_loader1,
Handle class_loader2,
Thread* THREAD) {
unsigned int d_hash1 = dictionary()->compute_hash(class_name, class_loader1);
int d_index1 = dictionary()->hash_to_index(d_hash1);
unsigned int d_hash2 = dictionary()->compute_hash(class_name, class_loader2);
int d_index2 = dictionary()->hash_to_index(d_hash2);
{
MutexLocker mu_s(SystemDictionary_lock, THREAD);
// Better never do a GC while we're holding these oops
No_Safepoint_Verifier nosafepoint;
klassOop klass1 = find_class(d_index1, d_hash1, class_name, class_loader1);
klassOop klass2 = find_class(d_index2, d_hash2, class_name, class_loader2);
return constraints()->add_entry(class_name, klass1, class_loader1,
klass2, class_loader2);
}
}
// Add entry to resolution error table to record the error when the first
// attempt to resolve a reference to a class has failed.
void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, symbolHandle error) {
unsigned int hash = resolution_errors()->compute_hash(pool, which);
int index = resolution_errors()->hash_to_index(hash);
{
MutexLocker ml(SystemDictionary_lock, Thread::current());
resolution_errors()->add_entry(index, hash, pool, which, error);
}
}
// Lookup resolution error table. Returns error if found, otherwise NULL.
symbolOop SystemDictionary::find_resolution_error(constantPoolHandle pool, int which) {
unsigned int hash = resolution_errors()->compute_hash(pool, which);
int index = resolution_errors()->hash_to_index(hash);
{
MutexLocker ml(SystemDictionary_lock, Thread::current());
ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
return (entry != NULL) ? entry->error() : (symbolOop)NULL;
}
}
// Make sure all class components (including arrays) in the given
// signature will be resolved to the same class in both loaders.
// Returns the name of the type that failed a loader constraint check, or
// NULL if no constraint failed. The returned C string needs cleaning up
// with a ResourceMark in the caller
char* SystemDictionary::check_signature_loaders(symbolHandle signature,
Handle loader1, Handle loader2,
bool is_method, TRAPS) {
// Nothing to do if loaders are the same.
if (loader1() == loader2()) {
return NULL;
}
SignatureStream sig_strm(signature, is_method);
while (!sig_strm.is_done()) {
if (sig_strm.is_object()) {
symbolOop s = sig_strm.as_symbol(CHECK_NULL);
symbolHandle sig (THREAD, s);
if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
return sig()->as_C_string();
}
}
sig_strm.next();
}
return NULL;
}
// Since the identity hash code for symbols changes when the symbols are
// moved from the regular perm gen (hash in the mark word) to the shared
// spaces (hash is the address), the classes loaded into the dictionary
// may be in the wrong buckets.
void SystemDictionary::reorder_dictionary() {
dictionary()->reorder_dictionary();
}
void SystemDictionary::copy_buckets(char** top, char* end) {
dictionary()->copy_buckets(top, end);
}
void SystemDictionary::copy_table(char** top, char* end) {
dictionary()->copy_table(top, end);
}
void SystemDictionary::reverse() {
dictionary()->reverse();
}
int SystemDictionary::number_of_classes() {
return dictionary()->number_of_entries();
}
// ----------------------------------------------------------------------------
#ifndef PRODUCT
void SystemDictionary::print() {
dictionary()->print();
// Placeholders
GCMutexLocker mu(SystemDictionary_lock);
placeholders()->print();
// loader constraints - print under SD_lock
constraints()->print();
}
#endif
void SystemDictionary::verify() {
guarantee(dictionary() != NULL, "Verify of system dictionary failed");
guarantee(constraints() != NULL,
"Verify of loader constraints failed");
guarantee(dictionary()->number_of_entries() >= 0 &&
placeholders()->number_of_entries() >= 0,
"Verify of system dictionary failed");
// Verify dictionary
dictionary()->verify();
GCMutexLocker mu(SystemDictionary_lock);
placeholders()->verify();
// Verify constraint table
guarantee(constraints() != NULL, "Verify of loader constraints failed");
constraints()->verify(dictionary());
}
void SystemDictionary::verify_obj_klass_present(Handle obj,
symbolHandle class_name,
Handle class_loader) {
GCMutexLocker mu(SystemDictionary_lock);
oop probe = find_class_or_placeholder(class_name, class_loader);
if (probe == NULL) {
probe = SystemDictionary::find_shared_class(class_name);
}
guarantee(probe != NULL &&
(!probe->is_klass() || probe == obj()),
"Loaded klasses should be in SystemDictionary");
}
#ifndef PRODUCT
// statistics code
class ClassStatistics: AllStatic {
private:
static int nclasses; // number of classes
static int nmethods; // number of methods
static int nmethoddata; // number of methodData
static int class_size; // size of class objects in words
static int method_size; // size of method objects in words
static int debug_size; // size of debug info in methods
static int methoddata_size; // size of methodData objects in words
static void do_class(klassOop k) {
nclasses++;
class_size += k->size();
if (k->klass_part()->oop_is_instance()) {
instanceKlass* ik = (instanceKlass*)k->klass_part();
class_size += ik->methods()->size();
class_size += ik->constants()->size();
class_size += ik->local_interfaces()->size();
class_size += ik->transitive_interfaces()->size();
// We do not have to count implementors, since we only store one!
class_size += ik->fields()->size();
}
}
static void do_method(methodOop m) {
nmethods++;
method_size += m->size();
// class loader uses same objArray for empty vectors, so don't count these
if (m->exception_table()->length() != 0) method_size += m->exception_table()->size();
if (m->has_stackmap_table()) {
method_size += m->stackmap_data()->size();
}
methodDataOop mdo = m->method_data();
if (mdo != NULL) {
nmethoddata++;
methoddata_size += mdo->size();
}
}
public:
static void print() {
SystemDictionary::classes_do(do_class);
SystemDictionary::methods_do(do_method);
tty->print_cr("Class statistics:");
tty->print_cr("%d classes (%d bytes)", nclasses, class_size * oopSize);
tty->print_cr("%d methods (%d bytes = %d base + %d debug info)", nmethods,
(method_size + debug_size) * oopSize, method_size * oopSize, debug_size * oopSize);
tty->print_cr("%d methoddata (%d bytes)", nmethoddata, methoddata_size * oopSize);
}
};
int ClassStatistics::nclasses = 0;
int ClassStatistics::nmethods = 0;
int ClassStatistics::nmethoddata = 0;
int ClassStatistics::class_size = 0;
int ClassStatistics::method_size = 0;
int ClassStatistics::debug_size = 0;
int ClassStatistics::methoddata_size = 0;
void SystemDictionary::print_class_statistics() {
ResourceMark rm;
ClassStatistics::print();
}
class MethodStatistics: AllStatic {
public:
enum {
max_parameter_size = 10
};
private:
static int _number_of_methods;
static int _number_of_final_methods;
static int _number_of_static_methods;
static int _number_of_native_methods;
static int _number_of_synchronized_methods;
static int _number_of_profiled_methods;
static int _number_of_bytecodes;
static int _parameter_size_profile[max_parameter_size];
static int _bytecodes_profile[Bytecodes::number_of_java_codes];
static void initialize() {
_number_of_methods = 0;
_number_of_final_methods = 0;
_number_of_static_methods = 0;
_number_of_native_methods = 0;
_number_of_synchronized_methods = 0;
_number_of_profiled_methods = 0;
_number_of_bytecodes = 0;
for (int i = 0; i < max_parameter_size ; i++) _parameter_size_profile[i] = 0;
for (int j = 0; j < Bytecodes::number_of_java_codes; j++) _bytecodes_profile [j] = 0;
};
static void do_method(methodOop m) {
_number_of_methods++;
// collect flag info
if (m->is_final() ) _number_of_final_methods++;
if (m->is_static() ) _number_of_static_methods++;
if (m->is_native() ) _number_of_native_methods++;
if (m->is_synchronized()) _number_of_synchronized_methods++;
if (m->method_data() != NULL) _number_of_profiled_methods++;
// collect parameter size info (add one for receiver, if any)
_parameter_size_profile[MIN2(m->size_of_parameters() + (m->is_static() ? 0 : 1), max_parameter_size - 1)]++;
// collect bytecodes info
{
Thread *thread = Thread::current();
HandleMark hm(thread);
BytecodeStream s(methodHandle(thread, m));
Bytecodes::Code c;
while ((c = s.next()) >= 0) {
_number_of_bytecodes++;
_bytecodes_profile[c]++;
}
}
}
public:
static void print() {
initialize();
SystemDictionary::methods_do(do_method);
// generate output
tty->cr();
tty->print_cr("Method statistics (static):");
// flag distribution
tty->cr();
tty->print_cr("%6d final methods %6.1f%%", _number_of_final_methods , _number_of_final_methods * 100.0F / _number_of_methods);
tty->print_cr("%6d static methods %6.1f%%", _number_of_static_methods , _number_of_static_methods * 100.0F / _number_of_methods);
tty->print_cr("%6d native methods %6.1f%%", _number_of_native_methods , _number_of_native_methods * 100.0F / _number_of_methods);
tty->print_cr("%6d synchronized methods %6.1f%%", _number_of_synchronized_methods, _number_of_synchronized_methods * 100.0F / _number_of_methods);
tty->print_cr("%6d profiled methods %6.1f%%", _number_of_profiled_methods, _number_of_profiled_methods * 100.0F / _number_of_methods);
// parameter size profile
tty->cr();
{ int tot = 0;
int avg = 0;
for (int i = 0; i < max_parameter_size; i++) {
int n = _parameter_size_profile[i];
tot += n;
avg += n*i;
tty->print_cr("parameter size = %1d: %6d methods %5.1f%%", i, n, n * 100.0F / _number_of_methods);
}
assert(tot == _number_of_methods, "should be the same");
tty->print_cr(" %6d methods 100.0%%", _number_of_methods);
tty->print_cr("(average parameter size = %3.1f including receiver, if any)", (float)avg / _number_of_methods);
}
// bytecodes profile
tty->cr();
{ int tot = 0;
for (int i = 0; i < Bytecodes::number_of_java_codes; i++) {
if (Bytecodes::is_defined(i)) {
Bytecodes::Code c = Bytecodes::cast(i);
int n = _bytecodes_profile[c];
tot += n;
tty->print_cr("%9d %7.3f%% %s", n, n * 100.0F / _number_of_bytecodes, Bytecodes::name(c));
}
}
assert(tot == _number_of_bytecodes, "should be the same");
tty->print_cr("%9d 100.000%%", _number_of_bytecodes);
}
tty->cr();
}
};
int MethodStatistics::_number_of_methods;
int MethodStatistics::_number_of_final_methods;
int MethodStatistics::_number_of_static_methods;
int MethodStatistics::_number_of_native_methods;
int MethodStatistics::_number_of_synchronized_methods;
int MethodStatistics::_number_of_profiled_methods;
int MethodStatistics::_number_of_bytecodes;
int MethodStatistics::_parameter_size_profile[MethodStatistics::max_parameter_size];
int MethodStatistics::_bytecodes_profile[Bytecodes::number_of_java_codes];
void SystemDictionary::print_method_statistics() {
MethodStatistics::print();
}
#endif // PRODUCT