Java example source code file (systemDictionary.cpp)
The systemDictionary.cpp Java example source code
/*
* Copyright (c) 1997, 2013, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "classfile/classLoaderData.inline.hpp"
#include "classfile/dictionary.hpp"
#include "classfile/javaClasses.hpp"
#include "classfile/loaderConstraints.hpp"
#include "classfile/placeholders.hpp"
#include "classfile/resolutionErrors.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "compiler/compileBroker.hpp"
#include "interpreter/bytecodeStream.hpp"
#include "interpreter/interpreter.hpp"
#include "memory/gcLocker.hpp"
#include "memory/oopFactory.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/instanceRefKlass.hpp"
#include "oops/klass.inline.hpp"
#include "oops/methodData.hpp"
#include "oops/objArrayKlass.hpp"
#include "oops/oop.inline.hpp"
#include "oops/oop.inline2.hpp"
#include "oops/typeArrayKlass.hpp"
#include "prims/jvmtiEnvBase.hpp"
#include "prims/methodHandles.hpp"
#include "runtime/biasedLocking.hpp"
#include "runtime/fieldType.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/java.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/signature.hpp"
#include "services/classLoadingService.hpp"
#include "services/threadService.hpp"
#include "utilities/macros.hpp"
#include "utilities/ticks.hpp"
#if INCLUDE_TRACE
#include "trace/tracing.hpp"
#endif
Dictionary* SystemDictionary::_dictionary = NULL;
PlaceholderTable* SystemDictionary::_placeholders = NULL;
Dictionary* SystemDictionary::_shared_dictionary = NULL;
LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
int SystemDictionary::_number_of_modifications = 0;
int SystemDictionary::_sdgeneration = 0;
const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
20201,40423,99991};
oop SystemDictionary::_system_loader_lock_obj = NULL;
Klass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
= { NULL /*, NULL...*/ };
Klass* 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
Klass* volatile 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, WK_KLASS(ClassLoader_klass));
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
vmSymbols::getSystemClassLoader_name(),
vmSymbols::void_classloader_signature(),
CHECK);
_java_system_loader = (oop)result.get_jobject();
}
ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
return ClassLoaderDataGraph::find_or_create(class_loader, CHECK_NULL);
}
// ----------------------------------------------------------------------------
// debugging
#ifdef ASSERT
// return true if class_name contains no '.' (internal format is '/')
bool SystemDictionary::is_internal_format(Symbol* class_name) {
if (class_name != NULL) {
ResourceMark rm;
char* name = class_name->as_C_string();
return strchr(name, '.') == NULL;
} else {
return true;
}
}
#endif
// ----------------------------------------------------------------------------
// Parallel class loading check
bool SystemDictionary::is_parallelCapable(Handle class_loader) {
if (UnsyncloadClass || class_loader.is_null()) return true;
if (AlwaysLockClassLoader) return false;
return java_lang_ClassLoader::parallelCapable(class_loader());
}
// ----------------------------------------------------------------------------
// ParallelDefineClass flag does not apply to bootclass loader
bool SystemDictionary::is_parallelDefine(Handle class_loader) {
if (class_loader.is_null()) return false;
if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
return true;
}
return false;
}
/**
* Returns true if the passed class loader is the extension class loader.
*/
bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
if (class_loader.is_null()) {
return false;
}
return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
}
// ----------------------------------------------------------------------------
// Resolving of classes
// Forwards to resolve_or_null
Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
Klass* 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;
}
Klass* SystemDictionary::handle_resolution_exception(Symbol* 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_NULL(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_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
} else {
THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
}
}
return (Klass*)klass_h();
}
Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
bool throw_error, TRAPS)
{
return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
}
// Forwards to resolve_instance_class_or_null
Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
assert(!THREAD->is_Compiler_thread(),
err_msg("can not load classes with compiler thread: class=%s, classloader=%s",
class_name->as_C_string(),
class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()));
if (FieldType::is_array(class_name)) {
return resolve_array_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
} else if (FieldType::is_obj(class_name)) {
ResourceMark rm(THREAD);
// Ignore wrapping L and ;.
TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
class_name->utf8_length() - 2, CHECK_NULL);
return resolve_instance_class_or_null(name, class_loader, protection_domain, CHECK_NULL);
} else {
return resolve_instance_class_or_null(class_name, class_loader, protection_domain, CHECK_NULL);
}
}
Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
return resolve_or_null(class_name, Handle(), Handle(), THREAD);
}
// Forwards to resolve_instance_class_or_null
Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
assert(FieldType::is_array(class_name), "must be array");
Klass* k = NULL;
FieldArrayInfo fd;
// dimension and object_key in FieldArrayInfo are assigned as a side-effect
// of this call
BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
if (t == T_OBJECT) {
// naked oop "k" is OK here -- we assign back into it
k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
class_loader,
protection_domain,
CHECK_NULL);
if (k != NULL) {
k = k->array_klass(fd.dimension(), CHECK_NULL);
}
} else {
k = Universe::typeArrayKlassObj(t);
k = TypeArrayKlass::cast(k)->array_klass(fd.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_null:
// via: handle_parallel_super_load
// 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.
Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
Symbol* 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
ClassLoaderData* loader_data = class_loader_data(class_loader);
unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
int d_index = dictionary()->hash_to_index(d_hash);
unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
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);
Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
Klass* 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) &&
((quicksuperk->name() == class_name) &&
(quicksuperk->class_loader() == class_loader()))) {
return quicksuperk;
} else {
PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
throw_circularity_error = true;
}
}
if (!throw_circularity_error) {
PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
}
}
if (throw_circularity_error) {
ResourceMark rm(THREAD);
THROW_MSG_NULL(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
Klass* superk = SystemDictionary::resolve_or_null(class_name,
class_loader,
protection_domain,
THREAD);
KlassHandle superk_h(THREAD, superk);
// Clean up of placeholders moved so that each classloadAction registrar self-cleans up
// It is no longer necessary to keep the placeholder table alive until update_dictionary
// or error. GC used to walk the placeholder table as strong roots.
// The instanceKlass is kept alive because the class loader is on the stack,
// which keeps the loader_data alive, as well as all instanceKlasses in
// the loader_data. parseClassFile adds the instanceKlass to loader_data.
{
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
SystemDictionary_lock->notify_all();
}
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();
}
KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
JavaCalls::call_special(&result,
class_loader,
system_loader,
vmSymbols::checkPackageAccess_name(),
vmSymbols::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.
ClassLoaderData* loader_data = class_loader_data(class_loader);
Symbol* kn = klass->name();
unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
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.
// Dictionary::do_unloading() asserts that classes in SD are only
// unloaded at a safepoint. Anonymous classes are not in SD.
No_Safepoint_Verifier nosafepoint;
dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
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((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "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: must call resolve_super_or_fail even if null super -
// to force placeholder entry creation for this class for circularity detection
// Caller must check for pending exception
// Returns non-null Klass* if other thread has completed load
// and we are done,
// If return null Klass* and no pending exception, the caller must load the class
instanceKlassHandle SystemDictionary::handle_parallel_super_load(
Symbol* name, Symbol* superclassname, Handle class_loader,
Handle protection_domain, Handle lockObject, TRAPS) {
instanceKlassHandle nh = instanceKlassHandle(); // null Handle
ClassLoaderData* loader_data = class_loader_data(class_loader);
unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
int d_index = dictionary()->hash_to_index(d_hash);
unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
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.
Klass* superk = SystemDictionary::resolve_super_or_fail(name,
superclassname,
class_loader,
protection_domain,
true,
CHECK_(nh));
// parallelCapable class loaders do NOT wait for parallel superclass loads to complete
// Serial class loaders and bootstrap classloader do wait for superclass loads
if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
MutexLocker mu(SystemDictionary_lock, THREAD);
// Check if classloading completed while we were loading superclass or waiting
Klass* check = find_class(d_index, d_hash, name, loader_data);
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
Klass* check = find_class(d_index, d_hash, name, loader_data);
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, loader_data);
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);
}
Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
assert(name != NULL && !FieldType::is_array(name) &&
!FieldType::is_obj(name), "invalid class name");
Ticks class_load_start_time = Ticks::now();
// UseNewReflection
// Fix for 4474172; see evaluation for more details
class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
// Do lookup to see if class already exist and the protection domain
// has the right access
// This call uses find which checks protection domain already matches
// All subsequent calls use find_class, and set has_loaded_class so that
// before we return a result we call out to java to check for valid protection domain
// to allow returning the Klass* and add it to the pd_set if it is valid
unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
int d_index = dictionary()->hash_to_index(d_hash);
Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
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
// ParallelCapable Classloaders and the bootstrap classloader,
// or all classloaders with UnsyncloadClass do not acquire lock here
bool DoObjectLock = true;
if (is_parallelCapable(class_loader)) {
DoObjectLock = false;
}
unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
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;
Symbol* superclassname = NULL;
{
MutexLocker mu(SystemDictionary_lock, THREAD);
Klass* check = find_class(d_index, d_hash, name, loader_data);
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, loader_data);
if (placeholder && placeholder->super_load_in_progress()) {
super_load_in_progress = true;
if (placeholder->havesupername() == true) {
superclassname = placeholder->supername();
havesupername = true;
}
}
}
}
// If the class 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;
}
}
bool throw_circularity_error = false;
if (!class_has_been_loaded) {
bool load_instance_added = false;
// 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
// Redefineclasses uses existence of the placeholder for the duration
// of the class load to prevent concurrent redefinition of not completely
// defined classes.
// 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. parallelCapable user level classloaders - without objectLocker
// Allow parallel classloading of a class/classloader pair
{
MutexLocker mu(SystemDictionary_lock, THREAD);
if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
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
Klass* check = find_class(d_index, d_hash, name, loader_data);
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, loader_data);
}
}
}
}
// All cases: add LOAD_INSTANCE holding SystemDictionary_lock
// case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
// LOAD_INSTANCE in parallel
if (!throw_circularity_error && !class_has_been_loaded) {
PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
load_instance_added = true;
// 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
// class loaders holding the ObjectLock shouldn't find the class here
Klass* check = find_class(d_index, d_hash, name, loader_data);
if (check != NULL) {
// Klass is already loaded, so return it after checking/adding protection domain
k = instanceKlassHandle(THREAD, check);
class_has_been_loaded = true;
}
}
}
// must throw error outside of owning lock
if (throw_circularity_error) {
assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
ResourceMark rm(THREAD);
THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
}
if (!class_has_been_loaded) {
// Do actual loading
k = load_instance_class(name, class_loader, THREAD);
// For UnsyncloadClass only
// 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
// Should not get here for classloaders that support parallelism
// with the new cleaner mechanism, even with AllowParallelDefineClass
// Bootstrap goes through here to allow for an extra guarantee check
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);
Klass* check = find_class(d_index, d_hash, name, loader_data);
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?");
}
}
}
// 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());
}
}
}
} // load_instance_class loop
if (HAS_PENDING_EXCEPTION) {
// An exception, such as OOM could have happened at various places inside
// load_instance_class. We might have partially initialized a shared class
// and need to clean it up.
if (class_loader.is_null()) {
// In some cases k may be null. Let's find the shared class again.
instanceKlassHandle ik(THREAD, find_shared_class(name));
if (ik.not_null()) {
if (ik->class_loader_data() == NULL) {
// We didn't go as far as Klass::restore_unshareable_info(),
// so nothing to clean up.
} else {
Klass *kk;
{
MutexLocker mu(SystemDictionary_lock, THREAD);
kk = find_class(d_index, d_hash, name, ik->class_loader_data());
}
if (kk != NULL) {
// No clean up is needed if the shared class has been entered
// into system dictionary, as load_shared_class() won't be called
// again.
} else {
// This must be done outside of the SystemDictionary_lock to
// avoid deadlock.
//
// Note that Klass::restore_unshareable_info (called via
// load_instance_class above) is also called outside
// of SystemDictionary_lock. Other threads are blocked from
// loading this class because they are waiting on the
// SystemDictionary_lock until this thread removes
// the placeholder below.
//
// This need to be re-thought when parallel-capable non-boot
// classloaders are supported by CDS (today they're not).
clean_up_shared_class(ik, class_loader, THREAD);
}
}
}
}
}
if (load_instance_added == true) {
// clean up placeholder entries for LOAD_INSTANCE success or error
// This brackets the SystemDictionary updates for both defining
// and initiating loaders
MutexLocker mu(SystemDictionary_lock, THREAD);
placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
SystemDictionary_lock->notify_all();
}
}
if (HAS_PENDING_EXCEPTION || k.is_null()) {
return NULL;
}
post_class_load_event(class_load_start_time, k, class_loader);
#ifdef ASSERT
{
ClassLoaderData* loader_data = k->class_loader_data();
MutexLocker mu(SystemDictionary_lock, THREAD);
Klass* kk = find_class(name, loader_data);
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.
// Dictionary::do_unloading() asserts that classes in SD are only
// unloaded at a safepoint. Anonymous classes are not in SD.
No_Safepoint_Verifier nosafepoint;
if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
loader_data,
protection_domain)) {
return k();
}
}
// Verify protection domain. If it fails an exception is thrown
validate_protection_domain(k, class_loader, protection_domain, CHECK_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.
Klass* SystemDictionary::find(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
// UseNewReflection
// The result of this call should be consistent with the result
// of the call to resolve_instance_class_or_null().
// See evaluation 6790209 and 4474172 for more details.
class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
if (loader_data == NULL) {
// If the ClassLoaderData has not been setup,
// then the class loader has no entries in the dictionary.
return NULL;
}
unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
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.
// Dictionary::do_unloading() asserts that classes in SD are only
// unloaded at a safepoint. Anonymous classes are not in SD.
No_Safepoint_Verifier nosafepoint;
return dictionary()->find(d_index, d_hash, class_name, loader_data,
protection_domain, THREAD);
}
}
// Look for a loaded instance or array klass by name. Do not do any loading.
// return NULL in case of error.
Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
Klass* 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.
// dimension and object_key in FieldArrayInfo are assigned as a
// side-effect of this call
FieldArrayInfo fd;
BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
if (t != T_OBJECT) {
k = Universe::typeArrayKlassObj(t);
} else {
k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
}
if (k != NULL) {
k = k->array_klass_or_null(fd.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?
Klass* SystemDictionary::parse_stream(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
ClassFileStream* st,
KlassHandle host_klass,
GrowableArray<Handle>* cp_patches,
TRAPS) {
TempNewSymbol parsed_name = NULL;
Ticks class_load_start_time = Ticks::now();
ClassLoaderData* loader_data;
if (host_klass.not_null()) {
// Create a new CLD for anonymous class, that uses the same class loader
// as the host_klass
assert(EnableInvokeDynamic, "");
guarantee(host_klass->class_loader() == class_loader(), "should be the same");
loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
loader_data->record_dependency(host_klass(), CHECK_NULL);
} else {
loader_data = ClassLoaderData::class_loader_data(class_loader());
}
// 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.
instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
loader_data,
protection_domain,
host_klass,
cp_patches,
parsed_name,
true,
THREAD);
if (host_klass.not_null() && k.not_null()) {
assert(EnableInvokeDynamic, "");
k->set_host_klass(host_klass());
// If it's anonymous, initialize it now, since nobody else will.
{
MutexLocker mu_r(Compile_lock, THREAD);
// Add to class hierarchy, initialize vtables, and do possible
// deoptimizations.
add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
// But, do not add to system dictionary.
// compiled code dependencies need to be validated anyway
notice_modification();
}
// Rewrite and patch constant pool here.
k->link_class(CHECK_NULL);
if (cp_patches != NULL) {
k->constants()->patch_resolved_references(cp_patches);
}
k->eager_initialize(CHECK_NULL);
// notify jvmti
if (JvmtiExport::should_post_class_load()) {
assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
JvmtiExport::post_class_load((JavaThread *) THREAD, k());
}
post_class_load_event(class_load_start_time, k, class_loader);
}
assert(host_klass.not_null() || cp_patches == NULL,
"cp_patches only found with host_klass");
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.
Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
ClassFileStream* st,
bool verify,
TRAPS) {
// Classloaders that support parallelism, e.g. bootstrap classloader,
// or all classloaders with UnsyncloadClass do not acquire lock here
bool DoObjectLock = true;
if (is_parallelCapable(class_loader)) {
DoObjectLock = false;
}
ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
// 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);
TempNewSymbol parsed_name = NULL;
// 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.
instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
loader_data,
protection_domain,
parsed_name,
verify,
THREAD);
const char* pkg = "java/";
if (!HAS_PENDING_EXCEPTION &&
!class_loader.is_null() &&
parsed_name != 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 != NULL, "Sanity");
assert(class_name == 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
// If a class loader supports parallel classloading handle parallel define requests
// find_or_define_instance_class may return a different InstanceKlass
if (is_parallelCapable(class_loader)) {
k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
} else {
define_instance_class(k, THREAD);
}
}
// Make sure we have an entry in the SystemDictionary on success
debug_only( {
if (!HAS_PENDING_EXCEPTION) {
assert(parsed_name != NULL, "parsed_name is still null?");
Symbol* h_name = k->name();
ClassLoaderData *defining_loader_data = k->class_loader_data();
MutexLocker mu(SystemDictionary_lock, THREAD);
Klass* check = find_class(parsed_name, loader_data);
assert(check == k(), "should be present in the dictionary");
Klass* check2 = find_class(h_name, defining_loader_data);
assert(check == check2, "name inconsistancy in SystemDictionary");
}
} );
return k();
}
void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
int number_of_entries) {
assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
"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.
Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
if (shared_dictionary() != NULL) {
unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
int d_index = shared_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(
Symbol* class_name, Handle class_loader, TRAPS) {
instanceKlassHandle ik (THREAD, find_shared_class(class_name));
return load_shared_class(ik, class_loader, THREAD);
}
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
Symbol* class_name = 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) {
Symbol* cn = ik->super()->name();
resolve_super_or_fail(class_name, cn,
class_loader, Handle(), true, CHECK_(nh));
}
Array<Klass*>* interfaces = ik->local_interfaces();
int num_interfaces = interfaces->length();
for (int index = 0; index < num_interfaces; index++) {
Klass* k = interfaces->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)
Symbol* name = k->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);
ik->restore_unshareable_info(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;
}
void SystemDictionary::clean_up_shared_class(instanceKlassHandle ik, Handle class_loader, TRAPS) {
// 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);
ik->remove_unshareable_info();
}
}
instanceKlassHandle SystemDictionary::load_instance_class(Symbol* 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;
{
PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
k = load_shared_class(class_name, class_loader, THREAD);
}
if (k.is_null()) {
// Use VM class loader
PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
k = ClassLoader::load_classfile(class_name, CHECK_(nh));
}
// find_or_define_instance_class may return a different InstanceKlass
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);
assert(THREAD->is_Java_thread(), "must be a JavaThread");
JavaThread* jt = (JavaThread*) THREAD;
PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
ClassLoader::perf_app_classload_selftime(),
ClassLoader::perf_app_classload_count(),
jt->get_thread_stat()->perf_recursion_counts_addr(),
jt->get_thread_stat()->perf_timers_addr(),
PerfClassTraceTime::CLASS_LOAD);
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());
// Call public unsynchronized loadClass(String) directly for all class loaders
// for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
// acquire a class-name based lock rather than the class loader object lock.
// JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
// so the call to loadClassInternal() was not required.
//
// UnsyncloadClass flag means both call loadClass(String) and do
// not acquire the class loader lock even for class loaders that are
// not parallelCapable. This was a risky transitional
// flag 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, the UnsyncloadClass flag risks unexpected timing bugs in the field.
// Do NOT assume this will be supported in future releases.
//
// Added MustCallLoadClassInternal in case we discover in the field
// a customer that counts on this call
if (MustCallLoadClassInternal && has_loadClassInternal()) {
JavaCalls::call_special(&result,
class_loader,
spec_klass,
vmSymbols::loadClassInternal_name(),
vmSymbols::string_class_signature(),
string,
CHECK_(nh));
} else {
JavaCalls::call_virtual(&result,
class_loader,
spec_klass,
vmSymbols::loadClass_name(),
vmSymbols::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_Klass(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) {
ClassLoaderData* loader_data = k->class_loader_data();
Handle class_loader_h(THREAD, loader_data->class_loader());
for (uintx it = 0; it < GCExpandToAllocateDelayMillis; it++){}
// for bootstrap and other parallel classloaders don't acquire lock,
// use placeholder token
// If a parallelCapable class loader calls define_instance_class instead of
// find_or_define_instance_class to get here, we have a timing
// hole with systemDictionary updates and check_constraints
if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
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
Symbol* name_h = k->name();
unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
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).
// JVMTI FollowReferences needs to find the classes this way.
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, loader_data);
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
// All parallel class loaders, including bootstrap classloader
// lock a placeholder entry for this class/class_loader pair
// to allow parallel defines of different classes for this class loader
// With AllowParallelDefine flag==true, 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
// This flag does not apply to the bootstrap classloader.
// With AllowParallelDefine flag==false, call through to define_instance_class
// which will throw LinkageError: duplicate class definition.
// False is the requested default.
// For better performance, the class loaders should synchronize
// findClass(), i.e. FindLoadedClass/DefineClassIfAbsent 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(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
instanceKlassHandle nh = instanceKlassHandle(); // null Handle
Symbol* name_h = k->name(); // passed in class_name may be null
ClassLoaderData* loader_data = class_loader_data(class_loader);
unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
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(name_h, loader_data);
int p_index = placeholders()->hash_to_index(p_hash);
PlaceholderEntry* probe;
{
MutexLocker mu(SystemDictionary_lock, THREAD);
// First check if class already defined
if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
Klass* check = find_class(d_index, d_hash, name_h, loader_data);
if (check != NULL) {
return(instanceKlassHandle(THREAD, check));
}
}
// Acquire define token for this class/classloader
probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
// Wait if another thread defining in parallel
// All threads wait - even those that will throw duplicate class: otherwise
// caller is surprised by LinkageError: duplicate, but findLoadedClass fails
// if other thread has not finished updating dictionary
while (probe->definer() != NULL) {
SystemDictionary_lock->wait();
}
// Only special cases allow parallel defines and can use other thread's results
// Other cases fall through, and may run into duplicate defines
// caught by finding an entry in the SystemDictionary
if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
SystemDictionary_lock->notify_all();
#ifdef ASSERT
Klass* check = find_class(d_index, d_hash, name_h, loader_data);
assert(check != NULL, "definer missed recording success");
#endif
return(instanceKlassHandle(THREAD, probe->instance_klass()));
} else {
// This thread will define the class (even if earlier thread tried and had an error)
probe->set_definer(THREAD);
}
}
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, name_h, loader_data);
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_instance_klass(k());
}
probe->set_definer(NULL);
placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
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
Klass* SystemDictionary::find_class(int index, unsigned int hash,
Symbol* class_name,
ClassLoaderData* loader_data) {
assert_locked_or_safepoint(SystemDictionary_lock);
assert (index == dictionary()->index_for(class_name, loader_data),
"incorrect index?");
Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
return k;
}
// Basic find on classes in the midst of being loaded
Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
ClassLoaderData* loader_data) {
assert_locked_or_safepoint(SystemDictionary_lock);
unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
int p_index = placeholders()->hash_to_index(p_hash);
return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
}
// Used for assertions and verification only
Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
#ifndef ASSERT
guarantee(VerifyBeforeGC ||
VerifyDuringGC ||
VerifyBeforeExit ||
VerifyDuringStartup ||
VerifyAfterGC, "too expensive");
#endif
assert_locked_or_safepoint(SystemDictionary_lock);
// First look in the loaded class array
unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
int d_index = dictionary()->hash_to_index(d_hash);
return find_class(d_index, d_hash, class_name, loader_data);
}
// Get the next class in the diictionary.
Klass* 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");
assert_locked_or_safepoint(Compile_lock);
// 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) {
blk->do_oop(&_java_system_loader);
blk->do_oop(&_system_loader_lock_obj);
dictionary()->always_strong_oops_do(blk);
// Visit extra methods
invoke_method_table()->oops_do(blk);
}
void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
// Follow all system classes and temporary placeholders in dictionary
dictionary()->always_strong_classes_do(closure);
// Placeholders. These represent classes we're actively loading.
placeholders()->classes_do(closure);
}
// Calculate a "good" systemdictionary size based
// on predicted or current loaded classes count
int SystemDictionary::calculate_systemdictionary_size(int classcount) {
int newsize = _old_default_sdsize;
if ((classcount > 0) && !DumpSharedSpaces) {
int desiredsize = classcount/_average_depth_goal;
for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
newsize = _primelist[++_sdgeneration]) {
if (desiredsize <= newsize) {
break;
}
}
}
return newsize;
}
#ifdef ASSERT
class VerifySDReachableAndLiveClosure : public OopClosure {
private:
BoolObjectClosure* _is_alive;
template <class T> void do_oop_work(T* p) {
oop obj = oopDesc::load_decode_heap_oop(p);
guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
}
public:
VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
virtual void do_oop(oop* p) { do_oop_work(p); }
virtual void do_oop(narrowOop* p) { do_oop_work(p); }
};
#endif
// Assumes classes in the SystemDictionary are only unloaded at a safepoint
// Note: anonymous classes are not in the SD.
bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive) {
// First, mark for unload all ClassLoaderData referencing a dead class loader.
bool has_dead_loaders = ClassLoaderDataGraph::do_unloading(is_alive);
bool unloading_occurred = false;
if (has_dead_loaders) {
unloading_occurred = dictionary()->do_unloading();
constraints()->purge_loader_constraints();
resolution_errors()->purge_resolution_errors();
}
// Oops referenced by the system dictionary may get unreachable independently
// of the class loader (eg. cached protection domain oops). So we need to
// explicitly unlink them here instead of in Dictionary::do_unloading.
dictionary()->unlink(is_alive);
#ifdef ASSERT
VerifySDReachableAndLiveClosure cl(is_alive);
dictionary()->oops_do(&cl);
#endif
return unloading_occurred;
}
void SystemDictionary::oops_do(OopClosure* f) {
f->do_oop(&_java_system_loader);
f->do_oop(&_system_loader_lock_obj);
// Adjust dictionary
dictionary()->oops_do(f);
// Visit extra methods
invoke_method_table()->oops_do(f);
}
// Extended Class redefinition support.
// If one of these classes is replaced, we need to replace it in these places.
// KlassClosure::do_klass should take the address of a class but we can
// change that later.
void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
f->do_klass(_well_known_klasses[k]);
}
{
for (int i = 0; i < T_VOID+1; i++) {
if (_box_klasses[i] != NULL) {
assert(i >= T_BOOLEAN, "checking");
f->do_klass(_box_klasses[i]);
}
}
}
FilteredFieldsMap::classes_do(f);
}
void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
f->do_klass(_abstract_ownable_synchronizer_klass);
}
// Just the classes from defining class loaders
// Don't iterate over placeholders
void SystemDictionary::classes_do(void f(Klass*)) {
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(Klass*, TRAPS), TRAPS) {
dictionary()->classes_do(f, CHECK);
}
// All classes, and their class loaders
// Don't iterate over placeholders
void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
dictionary()->classes_do(f);
}
void SystemDictionary::placeholders_do(void f(Symbol*)) {
placeholders()->entries_do(f);
}
void SystemDictionary::methods_do(void f(Method*)) {
dictionary()->methods_do(f);
invoke_method_table()->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.
Klass* aos = _abstract_ownable_synchronizer_klass;
if (aos == NULL) {
Klass* k = resolve_or_fail(vmSymbols::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");
_sdgeneration = 0;
_dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
_placeholders = new PlaceholderTable(_nof_buckets);
_number_of_modifications = 0;
_loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
_resolution_errors = new ResolutionErrorTable(_resolution_error_size);
_invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
// Allocate private object used as system class loader lock
_system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
// Initialize basic classes
initialize_preloaded_classes(CHECK);
}
// Compact table of directions on the initialization of klasses:
static const short wk_init_info[] = {
#define WK_KLASS_INIT_INFO(name, symbol, option) \
( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
<< SystemDictionary::CEIL_LG_OPTION_LIMIT) \
| (int)SystemDictionary::option ),
WK_KLASSES_DO(WK_KLASS_INIT_INFO)
#undef WK_KLASS_INIT_INFO
0
};
bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
int info = wk_init_info[id - FIRST_WKID];
int sid = (info >> CEIL_LG_OPTION_LIMIT);
Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
Klass** klassp = &_well_known_klasses[id];
bool must_load = (init_opt < SystemDictionary::Opt);
if ((*klassp) == NULL) {
if (must_load) {
(*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class
} else {
(*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass
}
}
return ((*klassp) != NULL);
}
void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
assert((int)start_id <= (int)limit_id, "IDs are out of order!");
for (int id = (int)start_id; id < (int)limit_id; id++) {
assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
int info = wk_init_info[id - FIRST_WKID];
int sid = (info >> CEIL_LG_OPTION_LIMIT);
int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
initialize_wk_klass((WKID)id, opt, CHECK);
}
// move the starting value forward to the limit:
start_id = limit_id;
}
void SystemDictionary::initialize_preloaded_classes(TRAPS) {
assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
// Preload commonly used klasses
WKID scan = FIRST_WKID;
// first do Object, then String, Class
if (UseSharedSpaces) {
initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
// Initialize the constant pool for the Object_class
InstanceKlass* ik = InstanceKlass::cast(Object_klass());
ik->constants()->restore_unshareable_info(CHECK);
initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
} else {
initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
}
// Calculate offsets for String and Class classes since they are loaded and
// can be used after this point.
java_lang_String::compute_offsets();
java_lang_Class::compute_offsets();
// 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);
// do a bunch more:
initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
// Preload ref klasses and set reference types
InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
// JSR 292 classes
WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
if (EnableInvokeDynamic) {
initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
} else {
// Skip the JSR 292 classes, if not enabled.
scan = WKID(jsr292_group_end + 1);
}
initialize_wk_klasses_until(WKID_LIMIT, scan, CHECK);
_box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
_box_klasses[T_CHAR] = WK_KLASS(Character_klass);
_box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
_box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
_box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
_box_klasses[T_SHORT] = WK_KLASS(Short_klass);
_box_klasses[T_INT] = WK_KLASS(Integer_klass);
_box_klasses[T_LONG] = WK_KLASS(Long_klass);
//_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
//_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
{ // Compute whether we should use loadClass or loadClassInternal when loading classes.
Method* 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
Method* 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(Klass* 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;
{
Symbol* name = k->name();
ClassLoaderData *loader_data = class_loader_data(class_loader);
MutexLocker mu(SystemDictionary_lock, THREAD);
Klass* check = find_class(d_index, d_hash, name, loader_data);
if (check != (Klass*)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->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
Symbol* ph_check = find_placeholder(name, loader_data);
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);
Symbol* name = k->name();
ClassLoaderData *loader_data = class_loader_data(class_loader);
{
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());
}
}
// Make a new system dictionary entry.
Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
if (sd_check == NULL) {
dictionary()->add_klass(name, loader_data, k);
notice_modification();
}
#ifdef ASSERT
sd_check = find_class(d_index, d_hash, name, loader_data);
assert (sd_check != NULL, "should have entry in system dictionary");
// Note: there may be a placeholder entry: for circularity testing
// or for parallel defines
#endif
SystemDictionary_lock->notify_all();
}
}
// Try to find a class name using the loader constraints. The
// loader constraints might know about a class that isn't fully loaded
// yet and these will be ignored.
Klass* SystemDictionary::find_constrained_instance_or_array_klass(
Symbol* 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;
Klass* 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)) {
// For array classes, their Klass*s are not kept in the
// constraint table. The element Klass*s are.
FieldArrayInfo fd;
BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
if (t != T_OBJECT) {
klass = Universe::typeArrayKlassObj(t);
} else {
MutexLocker mu(SystemDictionary_lock, THREAD);
klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
}
// If element class already loaded, allocate array klass
if (klass != NULL) {
klass = klass->array_klass_or_null(fd.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(Symbol* class_name,
Handle class_loader1,
Handle class_loader2,
Thread* THREAD) {
ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
Symbol* constraint_name = NULL;
if (!FieldType::is_array(class_name)) {
constraint_name = class_name;
} else {
// For array classes, their Klass*s are not kept in the
// constraint table. The element classes are.
FieldArrayInfo fd;
BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
// primitive types always pass
if (t != T_OBJECT) {
return true;
} else {
constraint_name = fd.object_key();
}
}
unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
int d_index1 = dictionary()->hash_to_index(d_hash1);
unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
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;
Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
return constraints()->add_entry(constraint_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, Symbol* 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);
}
}
// Delete a resolution error for RedefineClasses for a constant pool is going away
void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
resolution_errors()->delete_entry(pool);
}
// Lookup resolution error table. Returns error if found, otherwise NULL.
Symbol* 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() : (Symbol*)NULL;
}
}
// Signature constraints ensure that callers and callees agree about
// the meaning of type names in their signatures. This routine is the
// intake for constraints. It collects them from several places:
//
// * LinkResolver::resolve_method (if check_access is true) requires
// that the resolving class (the caller) and the defining class of
// the resolved method (the callee) agree on each type in the
// method's signature.
//
// * LinkResolver::resolve_interface_method performs exactly the same
// checks.
//
// * LinkResolver::resolve_field requires that the constant pool
// attempting to link to a field agree with the field's defining
// class about the type of the field signature.
//
// * klassVtable::initialize_vtable requires that, when a class
// overrides a vtable entry allocated by a superclass, that the
// overriding method (i.e., the callee) agree with the superclass
// on each type in the method's signature.
//
// * klassItable::initialize_itable requires that, when a class fills
// in its itables, for each non-abstract method installed in an
// itable, the method (i.e., the callee) agree with the interface
// on each type in the method's signature.
//
// All those methods have a boolean (check_access, checkconstraints)
// which turns off the checks. This is used from specialized contexts
// such as bootstrapping, dumping, and debugging.
//
// No direct constraint is placed between the class and its
// supertypes. Constraints are only placed along linked relations
// between callers and callees. When a method overrides or implements
// an abstract method in a supertype (superclass or interface), the
// constraints are placed as if the supertype were the caller to the
// overriding method. (This works well, since callers to the
// supertype have already established agreement between themselves and
// the supertype.) As a result of all this, a class can disagree with
// its supertype about the meaning of a type name, as long as that
// class neither calls a relevant method of the supertype, nor is
// called (perhaps via an override) from the supertype.
//
//
// SystemDictionary::check_signature_loaders(sig, l1, l2)
//
// 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. No exception except OOME is thrown.
// Arrays are not added to the loader constraint table, their elements are.
Symbol* SystemDictionary::check_signature_loaders(Symbol* 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()) {
Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
return sig;
}
}
sig_strm.next();
}
return NULL;
}
methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
Symbol* signature,
TRAPS) {
methodHandle empty;
assert(EnableInvokeDynamic, "");
assert(MethodHandles::is_signature_polymorphic(iid) &&
MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
iid != vmIntrinsics::_invokeGeneric,
err_msg("must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)));
unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
int index = invoke_method_table()->hash_to_index(hash);
SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
methodHandle m;
if (spe == NULL || spe->method() == NULL) {
spe = NULL;
// Must create lots of stuff here, but outside of the SystemDictionary lock.
m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
CompileBroker::compile_method(m, InvocationEntryBci, CompLevel_highest_tier,
methodHandle(), CompileThreshold, "MH", CHECK_(empty));
// Now grab the lock. We might have to throw away the new method,
// if a racing thread has managed to install one at the same time.
{
MutexLocker ml(SystemDictionary_lock, THREAD);
spe = invoke_method_table()->find_entry(index, hash, signature, iid);
if (spe == NULL)
spe = invoke_method_table()->add_entry(index, hash, signature, iid);
if (spe->method() == NULL)
spe->set_method(m());
}
}
assert(spe != NULL && spe->method() != NULL, "");
return spe->method();
}
// Helper for unpacking the return value from linkMethod and linkCallSite.
static methodHandle unpack_method_and_appendix(Handle mname,
KlassHandle accessing_klass,
objArrayHandle appendix_box,
Handle* appendix_result,
TRAPS) {
methodHandle empty;
if (mname.not_null()) {
Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
if (vmtarget != NULL && vmtarget->is_method()) {
Method* m = (Method*)vmtarget;
oop appendix = appendix_box->obj_at(0);
if (TraceMethodHandles) {
#ifndef PRODUCT
tty->print("Linked method="INTPTR_FORMAT": ", m);
m->print();
if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
tty->cr();
#endif //PRODUCT
}
(*appendix_result) = Handle(THREAD, appendix);
// the target is stored in the cpCache and if a reference to this
// MethodName is dropped we need a way to make sure the
// class_loader containing this method is kept alive.
// FIXME: the appendix might also preserve this dependency.
ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
return methodHandle(THREAD, m);
}
}
THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
return empty;
}
methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
Symbol* signature,
KlassHandle accessing_klass,
Handle *appendix_result,
Handle *method_type_result,
TRAPS) {
methodHandle empty;
assert(EnableInvokeDynamic, "");
assert(!THREAD->is_Compiler_thread(), "");
Handle method_type =
SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
if (false) { // FIXME: Decide if the Java upcall should resolve signatures.
method_type = java_lang_String::create_from_symbol(signature, CHECK_(empty));
}
KlassHandle mh_klass = SystemDictionary::MethodHandle_klass();
int ref_kind = JVM_REF_invokeVirtual;
Handle name_str = StringTable::intern(name, CHECK_(empty));
objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
assert(appendix_box->obj_at(0) == NULL, "");
// This should not happen. JDK code should take care of that.
if (accessing_klass.is_null() || method_type.is_null()) {
THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
}
// call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
JavaCallArguments args;
args.push_oop(accessing_klass()->java_mirror());
args.push_int(ref_kind);
args.push_oop(mh_klass()->java_mirror());
args.push_oop(name_str());
args.push_oop(method_type());
args.push_oop(appendix_box());
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
SystemDictionary::MethodHandleNatives_klass(),
vmSymbols::linkMethod_name(),
vmSymbols::linkMethod_signature(),
&args, CHECK_(empty));
Handle mname(THREAD, (oop) result.get_jobject());
(*method_type_result) = method_type;
return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
}
// Ask Java code to find or construct a java.lang.invoke.MethodType for the given
// signature, as interpreted relative to the given class loader.
// Because of class loader constraints, all method handle usage must be
// consistent with this loader.
Handle SystemDictionary::find_method_handle_type(Symbol* signature,
KlassHandle accessing_klass,
TRAPS) {
Handle empty;
vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
int index = invoke_method_table()->hash_to_index(hash);
SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
if (spe != NULL && spe->method_type() != NULL) {
assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
return Handle(THREAD, spe->method_type());
} else if (THREAD->is_Compiler_thread()) {
warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
return Handle(); // do not attempt from within compiler, unless it was cached
}
Handle class_loader, protection_domain;
bool is_on_bcp = true; // keep this true as long as we can materialize from the boot classloader
int npts = ArgumentCount(signature).size();
objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
int arg = 0;
Handle rt; // the return type from the signature
ResourceMark rm(THREAD);
for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
oop mirror = NULL;
if (is_on_bcp) {
// Note: class_loader & protection_domain are both null at this point.
mirror = ss.as_java_mirror(class_loader, protection_domain,
SignatureStream::ReturnNull, CHECK_(empty));
if (mirror == NULL) {
// fall back from BCP to accessing_klass
if (accessing_klass.not_null()) {
class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
}
is_on_bcp = false;
}
}
if (!is_on_bcp) {
// Resolve, throwing a real error if it doesn't work.
mirror = ss.as_java_mirror(class_loader, protection_domain,
SignatureStream::NCDFError, CHECK_(empty));
}
if (ss.at_return_type())
rt = Handle(THREAD, mirror);
else
pts->obj_at_put(arg++, mirror);
// Check accessibility.
if (ss.is_object() && accessing_klass.not_null()) {
Klass* sel_klass = java_lang_Class::as_Klass(mirror);
mirror = NULL; // safety
// Emulate ConstantPool::verify_constant_pool_resolve.
if (sel_klass->oop_is_objArray())
sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
if (sel_klass->oop_is_instance()) {
KlassHandle sel_kh(THREAD, sel_klass);
LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
}
}
}
assert(arg == npts, "");
// call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
JavaCallArguments args(Handle(THREAD, rt()));
args.push_oop(pts());
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
SystemDictionary::MethodHandleNatives_klass(),
vmSymbols::findMethodHandleType_name(),
vmSymbols::findMethodHandleType_signature(),
&args, CHECK_(empty));
Handle method_type(THREAD, (oop) result.get_jobject());
if (is_on_bcp) {
// We can cache this MethodType inside the JVM.
MutexLocker ml(SystemDictionary_lock, THREAD);
spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
if (spe == NULL)
spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
if (spe->method_type() == NULL) {
spe->set_method_type(method_type());
}
}
// report back to the caller with the MethodType
return method_type;
}
// Ask Java code to find or construct a method handle constant.
Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
int ref_kind, //e.g., JVM_REF_invokeVirtual
KlassHandle callee,
Symbol* name_sym,
Symbol* signature,
TRAPS) {
Handle empty;
Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
Handle type;
if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
type = find_method_handle_type(signature, caller, CHECK_(empty));
} else if (caller.is_null()) {
// This should not happen. JDK code should take care of that.
THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
} else {
ResourceMark rm(THREAD);
SignatureStream ss(signature, false);
if (!ss.is_done()) {
oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
SignatureStream::NCDFError, CHECK_(empty));
type = Handle(THREAD, mirror);
ss.next();
if (!ss.is_done()) type = Handle(); // error!
}
}
if (type.is_null()) {
THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
}
// call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
JavaCallArguments args;
args.push_oop(caller->java_mirror()); // the referring class
args.push_int(ref_kind);
args.push_oop(callee->java_mirror()); // the target class
args.push_oop(name());
args.push_oop(type());
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
SystemDictionary::MethodHandleNatives_klass(),
vmSymbols::linkMethodHandleConstant_name(),
vmSymbols::linkMethodHandleConstant_signature(),
&args, CHECK_(empty));
return Handle(THREAD, (oop) result.get_jobject());
}
// Ask Java code to find or construct a java.lang.invoke.CallSite for the given
// name and signature, as interpreted relative to the given class loader.
methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
Handle bootstrap_specifier,
Symbol* name,
Symbol* type,
Handle *appendix_result,
Handle *method_type_result,
TRAPS) {
methodHandle empty;
Handle bsm, info;
if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
bsm = bootstrap_specifier;
} else {
assert(bootstrap_specifier->is_objArray(), "");
objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
int len = args->length();
assert(len >= 1, "");
bsm = Handle(THREAD, args->obj_at(0));
if (len > 1) {
objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
for (int i = 1; i < len; i++)
args1->obj_at_put(i-1, args->obj_at(i));
info = Handle(THREAD, args1);
}
}
guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
"caller must supply a valid BSM");
Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
// This should not happen. JDK code should take care of that.
if (caller.is_null() || method_type.is_null()) {
THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
}
objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
assert(appendix_box->obj_at(0) == NULL, "");
// call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
JavaCallArguments args;
args.push_oop(caller->java_mirror());
args.push_oop(bsm());
args.push_oop(method_name());
args.push_oop(method_type());
args.push_oop(info());
args.push_oop(appendix_box);
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
SystemDictionary::MethodHandleNatives_klass(),
vmSymbols::linkCallSite_name(),
vmSymbols::linkCallSite_signature(),
&args, CHECK_(empty));
Handle mname(THREAD, (oop) result.get_jobject());
(*method_type_result) = method_type;
return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
}
// 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(), placeholders());
}
void SystemDictionary::verify_obj_klass_present(Symbol* class_name,
ClassLoaderData* loader_data) {
GCMutexLocker mu(SystemDictionary_lock);
Symbol* name;
Klass* probe = find_class(class_name, loader_data);
if (probe == NULL) {
probe = SystemDictionary::find_shared_class(class_name);
if (probe == NULL) {
name = find_placeholder(class_name, loader_data);
}
}
guarantee(probe != NULL || name != NULL,
"Loaded klasses should be in SystemDictionary");
}
// utility function for class load event
void SystemDictionary::post_class_load_event(const Ticks& start_time,
instanceKlassHandle k,
Handle initiating_loader) {
#if INCLUDE_TRACE
EventClassLoad event(UNTIMED);
if (event.should_commit()) {
event.set_starttime(start_time);
event.set_loadedClass(k());
oop defining_class_loader = k->class_loader();
event.set_definingClassLoader(defining_class_loader != NULL ?
defining_class_loader->klass() : (Klass*)NULL);
oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
event.set_initiatingClassLoader(class_loader != NULL ?
class_loader->klass() : (Klass*)NULL);
event.commit();
}
#endif /* INCLUDE_TRACE */
}
#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(Klass* k) {
nclasses++;
class_size += k->size();
if (k->oop_is_instance()) {
InstanceKlass* ik = (InstanceKlass*)k;
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!
// SSS: How should these be accounted now that they have moved?
// class_size += ik->fields()->length();
}
}
static void do_method(Method* m) {
nmethods++;
method_size += m->size();
// class loader uses same objArray for empty vectors, so don't count these
if (m->has_stackmap_table()) {
method_size += m->stackmap_data()->size();
}
MethodData* 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(Method* 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
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