JDK14/Java14源码在线阅读
/*
* Copyright (c) 1997, 2019, 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 "jvm.h"
#include "aot/aotLoader.hpp"
#include "classfile/classFileParser.hpp"
#include "classfile/classFileStream.hpp"
#include "classfile/classLoader.hpp"
#include "classfile/classLoaderData.inline.hpp"
#include "classfile/classLoaderDataGraph.inline.hpp"
#include "classfile/classLoaderExt.hpp"
#include "classfile/dictionary.hpp"
#include "classfile/javaClasses.inline.hpp"
#include "classfile/klassFactory.hpp"
#include "classfile/loaderConstraints.hpp"
#include "classfile/packageEntry.hpp"
#include "classfile/placeholders.hpp"
#include "classfile/protectionDomainCache.hpp"
#include "classfile/resolutionErrors.hpp"
#include "classfile/stringTable.hpp"
#include "classfile/symbolTable.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "code/codeCache.hpp"
#include "compiler/compileBroker.hpp"
#include "gc/shared/gcTraceTime.inline.hpp"
#include "gc/shared/oopStorage.inline.hpp"
#include "gc/shared/oopStorageSet.hpp"
#include "interpreter/bytecodeStream.hpp"
#include "interpreter/interpreter.hpp"
#include "jfr/jfrEvents.hpp"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/filemap.hpp"
#include "memory/heapShared.hpp"
#include "memory/metaspaceClosure.hpp"
#include "memory/oopFactory.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "oops/access.inline.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/instanceRefKlass.hpp"
#include "oops/klass.inline.hpp"
#include "oops/method.inline.hpp"
#include "oops/methodData.hpp"
#include "oops/objArrayKlass.hpp"
#include "oops/objArrayOop.inline.hpp"
#include "oops/oop.inline.hpp"
#include "oops/symbol.hpp"
#include "oops/typeArrayKlass.hpp"
#include "prims/jvmtiExport.hpp"
#include "prims/methodHandles.hpp"
#include "runtime/arguments.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/sharedRuntime.hpp"
#include "runtime/signature.hpp"
#include "services/classLoadingService.hpp"
#include "services/diagnosticCommand.hpp"
#include "services/threadService.hpp"
#include "utilities/macros.hpp"
#if INCLUDE_CDS
#include "classfile/systemDictionaryShared.hpp"
#endif
#if INCLUDE_JFR
#include "jfr/jfr.hpp"
#endif
PlaceholderTable* SystemDictionary::_placeholders = NULL;
LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
ProtectionDomainCacheTable* SystemDictionary::_pd_cache_table = NULL;
oop SystemDictionary::_system_loader_lock_obj = NULL;
InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
= { NULL /*, NULL...*/ };
InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
oop SystemDictionary::_java_system_loader = NULL;
oop SystemDictionary::_java_platform_loader = NULL;
// Default ProtectionDomainCacheSize value
const int defaultProtectionDomainCacheSize = 1009;
// ----------------------------------------------------------------------------
// Java-level SystemLoader and PlatformLoader
oop SystemDictionary::java_system_loader() {
return _java_system_loader;
}
oop SystemDictionary::java_platform_loader() {
return _java_platform_loader;
}
void SystemDictionary::compute_java_loaders(TRAPS) {
JavaValue result(T_OBJECT);
InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
JavaCalls::call_static(&result,
class_loader_klass,
vmSymbols::getSystemClassLoader_name(),
vmSymbols::void_classloader_signature(),
CHECK);
_java_system_loader = (oop)result.get_jobject();
JavaCalls::call_static(&result,
class_loader_klass,
vmSymbols::getPlatformClassLoader_name(),
vmSymbols::void_classloader_signature(),
CHECK);
_java_platform_loader = (oop)result.get_jobject();
}
ClassLoaderData* SystemDictionary::register_loader(Handle class_loader) {
if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
return ClassLoaderDataGraph::find_or_create(class_loader);
}
// ----------------------------------------------------------------------------
// Parallel class loading check
bool SystemDictionary::is_parallelCapable(Handle class_loader) {
if (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 builtin application class loader
// or a custom system class loader. A customer system class loader can be
// specified via -Djava.system.class.loader.
bool SystemDictionary::is_system_class_loader(oop class_loader) {
if (class_loader == NULL) {
return false;
}
return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
class_loader == _java_system_loader);
}
// Returns true if the passed class loader is the platform class loader.
bool SystemDictionary::is_platform_class_loader(oop class_loader) {
if (class_loader == NULL) {
return false;
}
return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
}
// ----------------------------------------------------------------------------
// 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) {
// can return a null klass
klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
}
return klass;
}
Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
bool throw_error,
Klass* klass, 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 == 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 == 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* 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_array_class_or_null or resolve_instance_class_or_null
Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
if (FieldType::is_array(class_name)) {
return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
} else {
return resolve_instance_class_or_null_helper(class_name, class_loader, protection_domain, THREAD);
}
}
// name may be in the form of "java/lang/Object" or "Ljava/lang/Object;"
InstanceKlass* SystemDictionary::resolve_instance_class_or_null_helper(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
assert(class_name != NULL && !FieldType::is_array(class_name), "must be");
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);
return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
} else {
return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
}
}
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.
// Be careful when modifying this code: once you have run
// placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
// you need to find_and_remove it before returning.
// So be careful to not exit with a CHECK_ macro betweeen these calls.
InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
Symbol* super_name,
Handle class_loader,
Handle protection_domain,
bool is_superclass,
TRAPS) {
assert(!FieldType::is_array(super_name), "invalid super class name");
#if INCLUDE_CDS
if (DumpSharedSpaces) {
// Special processing for handling UNREGISTERED shared classes.
InstanceKlass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
super_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
if (k) {
return k;
}
}
#endif // INCLUDE_CDS
// 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 appropriate class loader
// 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 needs to be in its class loader 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
ClassLoaderData* loader_data = class_loader_data(class_loader);
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(child_name);
unsigned int p_hash = placeholders()->compute_hash(child_name);
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);
InstanceKlass* childk = find_class(d_hash, child_name, dictionary);
InstanceKlass* quicksuperk;
// to support // loading: if child done loading, just return superclass
// if super_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 = childk->java_super()) != NULL) &&
((quicksuperk->name() == super_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) {
// Be careful not to exit resolve_super
PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, super_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(super_name != NULL, "null super class for resolving");
// Resolve the super class or interface, check results on return
InstanceKlass* superk =
SystemDictionary::resolve_instance_class_or_null_helper(super_name,
class_loader,
protection_domain,
THREAD);
// 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 == NULL) {
// can null superk
Klass* k = handle_resolution_exception(super_name, true, superk, THREAD);
assert(k == NULL || k == superk, "must be");
if (k == NULL) {
superk = NULL;
}
}
return superk;
}
void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
Handle class_loader,
Handle protection_domain,
TRAPS) {
// Now we have to call back to java to check if the initating class has access
JavaValue result(T_VOID);
LogTarget(Debug, protectiondomain) lt;
if (lt.is_enabled()) {
ResourceMark rm(THREAD);
// Print out trace information
LogStream ls(lt);
ls.print_cr("Checking package access");
if (class_loader() != NULL) {
ls.print("class loader: ");
class_loader()->print_value_on(&ls);
} else {
ls.print_cr("class loader: NULL");
}
if (protection_domain() != NULL) {
ls.print(" protection domain: ");
protection_domain()->print_value_on(&ls);
} else {
ls.print_cr(" protection domain: NULL");
}
ls.print(" loading: "); klass->print_value_on(&ls);
ls.cr();
}
// This handle and the class_loader handle passed in keeps this class from
// being unloaded through several GC points.
// The class_loader handle passed in is the initiating loader.
Handle mirror(THREAD, klass->java_mirror());
InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
JavaCalls::call_special(&result,
class_loader,
system_loader,
vmSymbols::checkPackageAccess_name(),
vmSymbols::class_protectiondomain_signature(),
mirror,
protection_domain,
THREAD);
if (HAS_PENDING_EXCEPTION) {
log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
} else {
log_debug(protectiondomain)("granted");
}
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.
{
ClassLoaderData* loader_data = class_loader_data(class_loader);
Dictionary* dictionary = loader_data->dictionary();
Symbol* kn = klass->name();
unsigned int d_hash = dictionary->compute_hash(kn);
MutexLocker mu(SystemDictionary_lock, THREAD);
int d_index = dictionary->hash_to_index(d_hash);
dictionary->add_protection_domain(d_index, d_hash, klass,
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) 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);
intx 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
InstanceKlass* SystemDictionary::handle_parallel_super_load(
Symbol* name, Symbol* superclassname, Handle class_loader,
Handle protection_domain, Handle lockObject, TRAPS) {
ClassLoaderData* loader_data = class_loader_data(class_loader);
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(name);
unsigned int p_hash = placeholders()->compute_hash(name);
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_NULL);
// 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
return find_class(d_hash, name, dictionary);
}
// 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
InstanceKlass* check = find_class(d_hash, name, dictionary);
if (check != NULL) {
// Klass is already loaded, so just return it
return check;
} else {
placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
if (placeholder && placeholder->super_load_in_progress() ){
// 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 NULL;
}
static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
assert(event != NULL, "invariant");
assert(k != NULL, "invariant");
assert(event->should_commit(), "invariant");
event->set_loadedClass(k);
event->set_definingClassLoader(k->class_loader_data());
event->set_initiatingClassLoader(init_cld);
event->commit();
}
// Be careful when modifying this code: once you have run
// placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
// you need to find_and_remove it before returning.
// So be careful to not exit with a CHECK_ macro betweeen these calls.
//
// name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
InstanceKlass* 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");
EventClassLoad class_load_start_event;
HandleMark hm(THREAD);
// 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);
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(name);
// 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
{
InstanceKlass* probe = dictionary->find(d_hash, name, protection_domain);
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
// do not acquire lock here.
bool DoObjectLock = true;
if (is_parallelCapable(class_loader)) {
DoObjectLock = false;
}
unsigned int p_hash = placeholders()->compute_hash(name);
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;
InstanceKlass* k = NULL;
PlaceholderEntry* placeholder;
Symbol* superclassname = NULL;
assert(THREAD->can_call_java(),
"can not load classes with compiler thread: class=%s, classloader=%s",
name->as_C_string(),
class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
{
MutexLocker mu(SystemDictionary_lock, THREAD);
InstanceKlass* check = find_class(d_hash, name, dictionary);
if (check != NULL) {
// InstanceKlass is already loaded, so just return it
class_has_been_loaded = true;
k = 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 = handle_parallel_super_load(name,
superclassname,
class_loader,
protection_domain,
lockObject, THREAD);
if (HAS_PENDING_EXCEPTION) {
return NULL;
}
if (k != 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. 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 4. 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 3: 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
InstanceKlass* check = find_class(d_hash, name, dictionary);
if (check != NULL) {
// Klass is already loaded, so just return it
k = 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 4: 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
InstanceKlass* check = find_class(d_hash, name, dictionary);
if (check != NULL) {
// Klass is already loaded, so return it after checking/adding protection domain
k = 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);
// 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 != NULL &&
k->class_loader() != class_loader()) {
check_constraints(d_hash, k, class_loader, false, THREAD);
// Need to check for a PENDING_EXCEPTION again; check_constraints
// can throw but we may have to remove entry from the placeholder table below.
if (!HAS_PENDING_EXCEPTION) {
// Record dependency for non-parent delegation.
// This recording keeps the defining class loader of the klass (k) found
// from being unloaded while the initiating class loader is loaded
// even if the reference to the defining class loader is dropped
// before references to the initiating class loader.
loader_data->record_dependency(k);
{ // Grabbing the Compile_lock prevents systemDictionary updates
// during compilations.
MutexLocker mu(Compile_lock, THREAD);
update_dictionary(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
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 == NULL) {
return NULL;
}
if (class_load_start_event.should_commit()) {
post_class_load_event(&class_load_start_event, k, loader_data);
}
#ifdef ASSERT
{
ClassLoaderData* loader_data = k->class_loader_data();
MutexLocker mu(SystemDictionary_lock, THREAD);
InstanceKlass* 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
if (dictionary->is_valid_protection_domain(d_hash, name,
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) {
// 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;
}
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(class_name);
return dictionary->find(d_hash, class_name,
protection_domain);
}
// 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
// does not publish the classes via the SystemDictionary.
// Handles unsafe_DefineAnonymousClass and redefineclasses
// RedefinedClasses do not add to the class hierarchy
InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
ClassFileStream* st,
const InstanceKlass* unsafe_anonymous_host,
GrowableArray<Handle>* cp_patches,
TRAPS) {
EventClassLoad class_load_start_event;
ClassLoaderData* loader_data;
if (unsafe_anonymous_host != NULL) {
// Create a new CLD for an unsafe anonymous class, that uses the same class loader
// as the unsafe_anonymous_host
guarantee(unsafe_anonymous_host->class_loader() == class_loader(), "should be the same");
loader_data = ClassLoaderData::unsafe_anonymous_class_loader_data(class_loader);
} else {
loader_data = ClassLoaderData::class_loader_data(class_loader());
}
assert(st != NULL, "invariant");
assert(st->need_verify(), "invariant");
// Parse stream and create a klass.
// Note that we do this even though this klass might
// already be present in the SystemDictionary, otherwise we would not
// throw potential ClassFormatErrors.
InstanceKlass* k = KlassFactory::create_from_stream(st,
class_name,
loader_data,
protection_domain,
unsafe_anonymous_host,
cp_patches,
CHECK_NULL);
if (unsafe_anonymous_host != NULL && k != NULL) {
// Unsafe anonymous classes must update ClassLoaderData holder (was unsafe_anonymous_host loader)
// so that they can be unloaded when the mirror is no longer referenced.
k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
{
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 dictionary.
}
// Rewrite and patch constant pool here.
k->link_class(CHECK_NULL);
if (cp_patches != NULL) {
k->constants()->patch_resolved_references(cp_patches);
}
// If it's anonymous, initialize it now, since nobody else will.
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);
}
if (class_load_start_event.should_commit()) {
post_class_load_event(&class_load_start_event, k, loader_data);
}
}
assert(unsafe_anonymous_host != NULL || NULL == cp_patches,
"cp_patches only found with unsafe_anonymous_host");
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.
InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
ClassFileStream* st,
TRAPS) {
HandleMark hm(THREAD);
// Classloaders that support parallelism, e.g. bootstrap classloader,
// do not acquire lock here
bool DoObjectLock = true;
if (is_parallelCapable(class_loader)) {
DoObjectLock = false;
}
ClassLoaderData* loader_data = register_loader(class_loader);
// 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);
assert(st != NULL, "invariant");
// Parse the stream and create a klass.
// Note that we do this even though this klass might
// already be present in the SystemDictionary, otherwise we would not
// throw potential ClassFormatErrors.
InstanceKlass* k = NULL;
#if INCLUDE_CDS
if (!DumpSharedSpaces) {
k = SystemDictionaryShared::lookup_from_stream(class_name,
class_loader,
protection_domain,
st,
CHECK_NULL);
}
#endif
if (k == NULL) {
if (st->buffer() == NULL) {
return NULL;
}
k = KlassFactory::create_from_stream(st,
class_name,
loader_data,
protection_domain,
NULL, // unsafe_anonymous_host
NULL, // cp_patches
CHECK_NULL);
}
assert(k != NULL, "no klass created");
Symbol* h_name = k->name();
assert(class_name == NULL || class_name == h_name, "name mismatch");
// 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)) {
InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
if (!HAS_PENDING_EXCEPTION && defined_k != k) {
// If a parallel capable class loader already defined this class, register 'k' for cleanup.
assert(defined_k != NULL, "Should have a klass if there's no exception");
loader_data->add_to_deallocate_list(k);
k = defined_k;
}
} else {
define_instance_class(k, THREAD);
}
// If defining the class throws an exception register 'k' for cleanup.
if (HAS_PENDING_EXCEPTION) {
assert(k != NULL, "Must have an instance klass here!");
loader_data->add_to_deallocate_list(k);
return NULL;
}
// Make sure we have an entry in the SystemDictionary on success
debug_only( {
MutexLocker mu(SystemDictionary_lock, THREAD);
Klass* check = find_class(h_name, k->class_loader_data());
assert(check == k, "should be present in the dictionary");
} );
return k;
}
#if INCLUDE_CDS
// Load a class for boot loader from the shared spaces. This also
// forces the super class and all interfaces to be loaded.
InstanceKlass* SystemDictionary::load_shared_boot_class(Symbol* class_name,
TRAPS) {
InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
if (ik != NULL && ik->is_shared_boot_class()) {
return load_shared_class(ik, Handle(), Handle(), NULL, THREAD);
}
return NULL;
}
// Check if a shared class can be loaded by the specific classloader:
//
// NULL classloader:
// - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
// - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
// be defined in an unnamed module.
bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
InstanceKlass* ik,
Handle class_loader, TRAPS) {
assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
"Cannot use sharing if java.base is patched");
ResourceMark rm(THREAD);
int path_index = ik->shared_classpath_index();
ClassLoaderData* loader_data = class_loader_data(class_loader);
if (path_index < 0) {
// path_index < 0 indicates that the class is intended for a custom loader
// and should not be loaded by boot/platform/app loaders
if (loader_data->is_builtin_class_loader_data()) {
return false;
} else {
return true;
}
}
SharedClassPathEntry* ent =
(SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
if (!Universe::is_module_initialized()) {
assert(ent != NULL && ent->is_modules_image(),
"Loading non-bootstrap classes before the module system is initialized");
assert(class_loader.is_null(), "sanity");
return true;
}
// Get the pkg_entry from the classloader
TempNewSymbol pkg_name = NULL;
PackageEntry* pkg_entry = NULL;
ModuleEntry* mod_entry = NULL;
pkg_name = InstanceKlass::package_from_name(class_name, CHECK_false);
if (pkg_name != NULL) {
if (loader_data != NULL) {
pkg_entry = loader_data->packages()->lookup_only(pkg_name);
}
if (pkg_entry != NULL) {
mod_entry = pkg_entry->module();
}
}
// If the archived class is from a module that has been patched at runtime,
// the class cannot be loaded from the archive.
if (mod_entry != NULL && mod_entry->is_patched()) {
return false;
}
if (class_loader.is_null()) {
assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
// The NULL classloader can load archived class originated from the
// "modules" jimage and the -Xbootclasspath/a. For class from the
// "modules" jimage, the PackageEntry/ModuleEntry must be defined
// by the NULL classloader.
if (mod_entry != NULL) {
// PackageEntry/ModuleEntry is found in the classloader. Check if the
// ModuleEntry's location agrees with the archived class' origination.
if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
return true; // Module class from the "module" jimage
}
}
// If the archived class is not from the "module" jimage, the class can be
// loaded by the NULL classloader if
//
// 1. the class is from the unamed package
// 2. or, the class is not from a module defined in the NULL classloader
// 3. or, the class is from an unamed module
if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
// the class is from the -Xbootclasspath/a
if (pkg_name == NULL ||
pkg_entry == NULL ||
pkg_entry->in_unnamed_module()) {
assert(mod_entry == NULL ||
mod_entry == loader_data->unnamed_module(),
"the unnamed module is not defined in the classloader");
return true;
}
}
return false;
} else {
bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
ik, class_loader, pkg_name, pkg_entry, mod_entry, CHECK_(false));
return res;
}
}
InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
Handle class_loader,
Handle protection_domain,
const ClassFileStream *cfs,
TRAPS) {
assert(ik != NULL, "sanity");
assert(!ik->is_unshareable_info_restored(), "shared class can be loaded only once");
Symbol* class_name = ik->name();
bool visible = is_shared_class_visible(
class_name, ik, class_loader, CHECK_NULL);
if (!visible) {
return NULL;
}
// Resolve the superclass and interfaces. They must be the same
// as in dump time, because the layout of <ik> depends on
// the specific layout of ik->super() and ik->local_interfaces().
//
// If unexpected superclass or interfaces are found, we cannot
// load <ik> from the shared archive.
if (ik->super() != NULL) {
Symbol* cn = ik->super()->name();
Klass *s = resolve_super_or_fail(class_name, cn,
class_loader, protection_domain, true, CHECK_NULL);
if (s != ik->super()) {
// The dynamically resolved super class is not the same as the one we used during dump time,
// so we cannot use ik.
return NULL;
} else {
assert(s->is_shared(), "must be");
}
}
Array<InstanceKlass*>* interfaces = ik->local_interfaces();
int num_interfaces = interfaces->length();
for (int index = 0; index < num_interfaces; index++) {
InstanceKlass* k = interfaces->at(index);
Symbol* name = k->name();
Klass* i = resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_NULL);
if (k != i) {
// The dynamically resolved interface class is not the same as the one we used during dump time,
// so we cannot use ik.
return NULL;
} else {
assert(i->is_shared(), "must be");
}
}
InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
if (new_ik != NULL) {
// The class is changed by CFLH. Return the new class. The shared class is
// not used.
return new_ik;
}
// 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 either the bootstrap or
// internal parallel class loaders, so this will never cause a deadlock
// on a custom class loader lock.
ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
{
HandleMark hm(THREAD);
Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
check_loader_lock_contention(lockObject, THREAD);
ObjectLocker ol(lockObject, THREAD, true);
// prohibited package check assumes all classes loaded from archive call
// restore_unshareable_info which calls ik->set_package()
ik->restore_unshareable_info(loader_data, protection_domain, CHECK_NULL);
}
ik->print_class_load_logging(loader_data, NULL, NULL);
// For boot loader, ensure that GetSystemPackage knows that a class in this
// package was loaded.
if (class_loader.is_null()) {
int path_index = ik->shared_classpath_index();
ResourceMark rm(THREAD);
ClassLoader::add_package(ik->name()->as_C_string(), path_index, THREAD);
}
if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
// Only dump the classes that can be stored into CDS archive
if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
ResourceMark rm(THREAD);
classlist_file->print_cr("%s", ik->name()->as_C_string());
classlist_file->flush();
}
}
// notify a class loaded from shared object
ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
ik->set_has_passed_fingerprint_check(false);
if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
uint64_t cds_fp = ik->get_stored_fingerprint();
if (aot_fp != 0 && aot_fp == cds_fp) {
// This class matches with a class saved in an AOT library
ik->set_has_passed_fingerprint_check(true);
} else {
if (log_is_enabled(Info, class, fingerprint)) {
ResourceMark rm(THREAD);
log_info(class, fingerprint)("%s : expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
}
}
}
return ik;
}
#endif // INCLUDE_CDS
InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
if (class_loader.is_null()) {
ResourceMark rm(THREAD);
PackageEntry* pkg_entry = NULL;
bool search_only_bootloader_append = false;
ClassLoaderData *loader_data = class_loader_data(class_loader);
// Find the package in the boot loader's package entry table.
TempNewSymbol pkg_name = InstanceKlass::package_from_name(class_name, CHECK_NULL);
if (pkg_name != NULL) {
pkg_entry = loader_data->packages()->lookup_only(pkg_name);
}
// Prior to attempting to load the class, enforce the boot loader's
// visibility boundaries.
if (!Universe::is_module_initialized()) {
// During bootstrapping, prior to module initialization, any
// class attempting to be loaded must be checked against the
// java.base packages in the boot loader's PackageEntryTable.
// No class outside of java.base is allowed to be loaded during
// this bootstrapping window.
if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
// Class is either in the unnamed package or in
// a named package within the unnamed module. Either
// case is outside of java.base, do not attempt to
// load the class post java.base definition. If
// java.base has not been defined, let the class load
// and its package will be checked later by
// ModuleEntryTable::verify_javabase_packages.
if (ModuleEntryTable::javabase_defined()) {
return NULL;
}
} else {
// Check that the class' package is defined within java.base.
ModuleEntry* mod_entry = pkg_entry->module();
Symbol* mod_entry_name = mod_entry->name();
if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
return NULL;
}
}
} else {
// After the module system has been initialized, check if the class'
// package is in a module defined to the boot loader.
if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
// Class is either in the unnamed package, in a named package
// within a module not defined to the boot loader or in a
// a named package within the unnamed module. In all cases,
// limit visibility to search for the class only in the boot
// loader's append path.
if (!ClassLoader::has_bootclasspath_append()) {
// If there is no bootclasspath append entry, no need to continue
// searching.
return NULL;
}
search_only_bootloader_append = true;
}
}
// Prior to bootstrapping's module initialization, never load a class outside
// of the boot loader's module path
assert(Universe::is_module_initialized() ||
!search_only_bootloader_append,
"Attempt to load a class outside of boot loader's module path");
// Search for classes in the CDS archive.
InstanceKlass* k = NULL;
{
#if INCLUDE_CDS
PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
k = load_shared_boot_class(class_name, THREAD);
#endif
}
if (k == NULL) {
// Use VM class loader
PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
}
// find_or_define_instance_class may return a different InstanceKlass
if (k != NULL) {
InstanceKlass* defined_k =
find_or_define_instance_class(class_name, class_loader, k, THREAD);
if (!HAS_PENDING_EXCEPTION && defined_k != k) {
// If a parallel capable class loader already defined this class, register 'k' for cleanup.
assert(defined_k != NULL, "Should have a klass if there's no exception");
loader_data->add_to_deallocate_list(k);
k = defined_k;
} else if (HAS_PENDING_EXCEPTION) {
loader_data->add_to_deallocate_list(k);
return NULL;
}
}
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_NULL);
// Translate to external class name format, i.e., convert '/' chars to '.'
Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
JavaValue result(T_OBJECT);
InstanceKlass* spec_klass = 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).
JavaCalls::call_virtual(&result,
class_loader,
spec_klass,
vmSymbols::loadClass_name(),
vmSymbols::string_class_signature(),
string,
CHECK_NULL);
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))) {
InstanceKlass* k = InstanceKlass::cast(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 NULL;
}
}
static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
EventClassDefine event;
if (event.should_commit()) {
event.set_definedClass(k);
event.set_definingClassLoader(def_cld);
event.commit();
}
}
void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
HandleMark hm(THREAD);
ClassLoaderData* loader_data = k->class_loader_data();
Handle class_loader_h(THREAD, loader_data->class_loader());
// 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();
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(name_h);
check_constraints(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);
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_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);
}
post_class_define_event(k, loader_data);
}
// 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
// Be careful when modifying this code: once you have run
// placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
// you need to find_and_remove it before returning.
// So be careful to not exit with a CHECK_ macro betweeen these calls.
InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
InstanceKlass* k, TRAPS) {
Symbol* name_h = k->name(); // passed in class_name may be null
ClassLoaderData* loader_data = class_loader_data(class_loader);
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(name_h);
// Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
unsigned int p_hash = placeholders()->compute_hash(name_h);
int p_index = placeholders()->hash_to_index(p_hash);
PlaceholderEntry* probe;
{
MutexLocker mu(SystemDictionary_lock, THREAD);
// First check if class already defined
if (is_parallelDefine(class_loader)) {
InstanceKlass* check = find_class(d_hash, name_h, dictionary);
if (check != NULL) {
return 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 (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
InstanceKlass* check = find_class(d_hash, name_h, dictionary);
assert(check != NULL, "definer missed recording success");
#endif
return 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(), NULL); // 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
InstanceKlass* SystemDictionary::find_class(unsigned int hash,
Symbol* class_name,
Dictionary* dictionary) {
assert_locked_or_safepoint(SystemDictionary_lock);
int index = dictionary->hash_to_index(hash);
return dictionary->find_class(index, hash, class_name);
}
// 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);
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
// Precalculating the hash and index is an optimization because there are many lookups
// before adding the class.
InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
assert_locked_or_safepoint(SystemDictionary_lock);
#ifndef ASSERT
guarantee(VerifyBeforeGC ||
VerifyDuringGC ||
VerifyBeforeExit ||
VerifyDuringStartup ||
VerifyAfterGC, "too expensive");
#endif
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(class_name);
return find_class(d_hash, class_name, dictionary);
}
// ----------------------------------------------------------------------------
// 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(InstanceKlass* k, TRAPS) {
assert(k != NULL, "just checking");
assert_locked_or_safepoint(Compile_lock);
k->set_init_state(InstanceKlass::loaded);
// make sure init_state store is already done.
// The compiler reads the hierarchy outside of the Compile_lock.
// Access ordering is used to add to hierarchy.
// Link into hierachy.
k->append_to_sibling_list(); // add to superklass/sibling list
k->process_interfaces(THREAD); // handle all "implements" declarations
// 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)
CodeCache::flush_dependents_on(k);
}
// ----------------------------------------------------------------------------
// GC support
// Assumes classes in the SystemDictionary are only unloaded at a safepoint
// Note: anonymous classes are not in the SD.
bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
bool unloading_occurred;
bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
{
GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
// First, mark for unload all ClassLoaderData referencing a dead class loader.
unloading_occurred = ClassLoaderDataGraph::do_unloading();
if (unloading_occurred) {
MutexLocker ml2(is_concurrent ? Module_lock : NULL);
JFR_ONLY(Jfr::on_unloading_classes();)
MutexLocker ml1(is_concurrent ? SystemDictionary_lock : NULL);
ClassLoaderDataGraph::clean_module_and_package_info();
constraints()->purge_loader_constraints();
resolution_errors()->purge_resolution_errors();
}
}
GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
if (unloading_occurred) {
SymbolTable::trigger_cleanup();
// Oops referenced by the protection domain cache table may get unreachable independently
// of the class loader (eg. cached protection domain oops). So we need to
// explicitly unlink them here.
// All protection domain oops are linked to the caller class, so if nothing
// unloads, this is not needed.
_pd_cache_table->trigger_cleanup();
}
return unloading_occurred;
}
void SystemDictionary::oops_do(OopClosure* f, bool include_handles) {
f->do_oop(&_java_system_loader);
f->do_oop(&_java_platform_loader);
f->do_oop(&_system_loader_lock_obj);
CDS_ONLY(SystemDictionaryShared::oops_do(f);)
// Visit extra methods
invoke_method_table()->oops_do(f);
if (include_handles) {
OopStorageSet::vm_global()->oops_do(f);
}
}
// CDS: scan and relocate all classes referenced by _well_known_klasses[].
void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
it->push(well_known_klass_addr((WKID)id));
}
}
void SystemDictionary::methods_do(void f(Method*)) {
// Walk methods in loaded classes
MutexLocker ml(ClassLoaderDataGraph_lock);
ClassLoaderDataGraph::methods_do(f);
// Walk method handle intrinsics
invoke_method_table()->methods_do(f);
}
// ----------------------------------------------------------------------------
// Initialization
void SystemDictionary::initialize(TRAPS) {
// Allocate arrays
_placeholders = new PlaceholderTable(_placeholder_table_size);
_loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
_resolution_errors = new ResolutionErrorTable(_resolution_error_size);
_invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
_pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
// Allocate private object used as system class loader lock
_system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
// Initialize basic classes
resolve_well_known_classes(CHECK);
}
// Compact table of directions on the initialization of klasses:
static const short wk_init_info[] = {
#define WK_KLASS_INIT_INFO(name, symbol) \
((short)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol)),
WK_KLASSES_DO(WK_KLASS_INIT_INFO)
#undef WK_KLASS_INIT_INFO
0
};
#ifdef ASSERT
bool SystemDictionary::is_well_known_klass(Symbol* class_name) {
int sid;
for (int i = 0; (sid = wk_init_info[i]) != 0; i++) {
Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
if (class_name == symbol) {
return true;
}
}
return false;
}
#endif
bool SystemDictionary::resolve_wk_klass(WKID id, TRAPS) {
assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
int sid = wk_init_info[id - FIRST_WKID];
Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
InstanceKlass** klassp = &_well_known_klasses[id];
if ((*klassp) == NULL) {
Klass* k = resolve_or_fail(symbol, true, CHECK_0);
(*klassp) = InstanceKlass::cast(k);
}
return ((*klassp) != NULL);
}
void SystemDictionary::resolve_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");
resolve_wk_klass((WKID)id, CHECK);
}
// move the starting value forward to the limit:
start_id = limit_id;
}
void SystemDictionary::resolve_well_known_classes(TRAPS) {
assert(WK_KLASS(Object_klass) == NULL, "well-known classes should only be initialized once");
// Create the ModuleEntry for java.base. This call needs to be done here,
// after vmSymbols::initialize() is called but before any classes are pre-loaded.
ClassLoader::classLoader_init2(CHECK);
// Preload commonly used klasses
WKID scan = FIRST_WKID;
// first do Object, then String, Class
#if INCLUDE_CDS
if (UseSharedSpaces) {
resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
// It's unsafe to access the archived heap regions before they
// are fixed up, so we must do the fixup as early as possible
// before the archived java objects are accessed by functions
// such as java_lang_Class::restore_archived_mirror and
// ConstantPool::restore_unshareable_info (restores the archived
// resolved_references array object).
//
// HeapShared::fixup_mapped_heap_regions() fills the empty
// spaces in the archived heap regions and may use
// SystemDictionary::Object_klass(), so we can do this only after
// Object_klass is resolved. See the above resolve_wk_klasses_through()
// call. No mirror objects are accessed/restored in the above call.
// Mirrors are restored after java.lang.Class is loaded.
HeapShared::fixup_mapped_heap_regions();
// Initialize the constant pool for the Object_class
assert(Object_klass()->is_shared(), "must be");
Object_klass()->constants()->restore_unshareable_info(CHECK);
resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
} else
#endif
{
resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
}
assert(WK_KLASS(Object_klass) != NULL, "well-known classes should now be initialized");
java_lang_Object::register_natives(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:
resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
// Preload ref klasses and set reference types
WK_KLASS(Reference_klass)->set_reference_type(REF_OTHER);
InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
WK_KLASS(SoftReference_klass)->set_reference_type(REF_SOFT);
WK_KLASS(WeakReference_klass)->set_reference_type(REF_WEAK);
WK_KLASS(FinalReference_klass)->set_reference_type(REF_FINAL);
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);
resolve_wk_klasses_until(jsr292_group_start, scan, CHECK);
resolve_wk_klasses_through(jsr292_group_end, scan, CHECK);
WKID last = WKID_LIMIT;
resolve_wk_klasses_until(last, 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);
#ifdef ASSERT
if (UseSharedSpaces) {
assert(JvmtiExport::is_early_phase(),
"All well known classes must be resolved in JVMTI early phase");
for (int i = FIRST_WKID; i < last; i++) {
InstanceKlass* k = _well_known_klasses[i];
assert(k->is_shared(), "must not be replaced by JVMTI class file load hook");
}
}
#endif
}
// 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 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 dictionary
// if initiating loader, then ok if InstanceKlass matches existing entry
void SystemDictionary::check_constraints(unsigned int d_hash,
InstanceKlass* k,
Handle class_loader,
bool defining,
TRAPS) {
ResourceMark rm(THREAD);
stringStream ss;
bool throwException = false;
{
Symbol *name = k->name();
ClassLoaderData *loader_data = class_loader_data(class_loader);
MutexLocker mu(SystemDictionary_lock, THREAD);
InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
if (check != 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.
// The dictionary only holds instance classes, placeholders
// also hold array classes.
assert(check->is_instance_klass(), "noninstance in systemdictionary");
if ((defining == true) || (k != check)) {
throwException = true;
ss.print("loader %s", loader_data->loader_name_and_id());
ss.print(" attempted duplicate %s definition for %s. (%s)",
k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
} else {
return;
}
}
#ifdef ASSERT
Symbol* ph_check = find_placeholder(name, loader_data);
assert(ph_check == NULL || ph_check == name, "invalid symbol");
#endif
if (throwException == false) {
if (constraints()->check_or_update(k, class_loader, name) == false) {
throwException = true;
ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
ss.print(" wants to load %s %s.",
k->external_kind(), k->external_name());
Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
if (existing_klass != NULL && existing_klass->class_loader() != class_loader()) {
ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
existing_klass->external_kind(),
existing_klass->class_loader_data()->loader_name_and_id(),
existing_klass->class_in_module_of_loader(false, true));
} else {
ss.print(" (%s)", k->class_in_module_of_loader(false, true));
}
}
}
}
// Throw error now if needed (cannot throw while holding
// SystemDictionary_lock because of rank ordering)
if (throwException == true) {
THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
}
}
// Update class loader data dictionary - done after check_constraint and add_to_hierachy
// have been called.
void SystemDictionary::update_dictionary(unsigned int d_hash,
int p_index, unsigned int p_hash,
InstanceKlass* 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);
// Make a new dictionary entry.
Dictionary* dictionary = loader_data->dictionary();
InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
if (sd_check == NULL) {
dictionary->add_klass(d_hash, name, k);
}
#ifdef ASSERT
sd_check = find_class(d_hash, name, dictionary);
assert (sd_check != NULL, "should have entry in 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;
// Needs to be in same scope as constraint_name in case a Symbol is created and
// assigned to constraint_name.
FieldArrayInfo fd;
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.
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();
}
}
Dictionary* dictionary1 = loader_data1->dictionary();
unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
Dictionary* dictionary2 = loader_data2->dictionary();
unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
{
MutexLocker mu_s(SystemDictionary_lock, THREAD);
InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
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(const constantPoolHandle& pool, int which,
Symbol* error, Symbol* message) {
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, message);
}
}
// 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(const constantPoolHandle& pool, int which,
Symbol** message) {
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);
if (entry != NULL) {
*message = entry->message();
return entry->error();
} else {
return 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();
if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
return sig;
}
}
sig_strm.next();
}
return NULL;
}
Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
Symbol* signature,
TRAPS) {
methodHandle empty;
assert(MethodHandles::is_signature_polymorphic(iid) &&
MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
iid != vmIntrinsics::_invokeGeneric,
"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_NULL);
if (!Arguments::is_interpreter_only()) {
// Generate a compiled form of the MH intrinsic.
AdapterHandlerLibrary::create_native_wrapper(m);
// Check if have the compiled code.
if (!m->has_compiled_code()) {
THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
"Out of space in CodeCache for method handle intrinsic");
}
}
// 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, "");
assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
"MH intrinsic invariant");
return spe->method();
}
// Helper for unpacking the return value from linkMethod and linkCallSite.
static Method* unpack_method_and_appendix(Handle mname,
Klass* accessing_klass,
objArrayHandle appendix_box,
Handle* appendix_result,
TRAPS) {
if (mname.not_null()) {
Method* m = java_lang_invoke_MemberName::vmtarget(mname());
if (m != NULL) {
oop appendix = appendix_box->obj_at(0);
if (TraceMethodHandles) {
#ifndef PRODUCT
ttyLocker ttyl;
tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(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
// MemberName is dropped we need a way to make sure the
// class_loader containing this method is kept alive.
methodHandle mh(THREAD, m); // record_dependency can safepoint.
ClassLoaderData* this_key = accessing_klass->class_loader_data();
this_key->record_dependency(m->method_holder());
return mh();
}
}
THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
}
Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
Symbol* name,
Symbol* signature,
Klass* accessing_klass,
Handle *appendix_result,
TRAPS) {
assert(THREAD->can_call_java() ,"");
Handle method_type =
SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
int ref_kind = JVM_REF_invokeVirtual;
oop name_oop = StringTable::intern(name, CHECK_NULL);
Handle name_str (THREAD, name_oop);
objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_NULL);
assert(appendix_box->obj_at(0) == NULL, "");
// This should not happen. JDK code should take care of that.
if (accessing_klass == NULL || method_type.is_null()) {
THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
}
// call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
JavaCallArguments args;
args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
args.push_int(ref_kind);
args.push_oop(Handle(THREAD, 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_NULL);
Handle mname(THREAD, (oop) result.get_jobject());
return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
}
// Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
// We must ensure that all class loaders everywhere will reach this class, for any client.
// This is a safe bet for public classes in java.lang, such as Object and String.
// We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
// Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
static bool is_always_visible_class(oop mirror) {
Klass* klass = java_lang_Class::as_Klass(mirror);
if (klass->is_objArray_klass()) {
klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
}
if (klass->is_typeArray_klass()) {
return true; // primitive array
}
assert(klass->is_instance_klass(), "%s", klass->external_name());
return klass->is_public() &&
(InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang
InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke
}
// Return the Java mirror (java.lang.Class instance) for a single-character
// descriptor. This result, when available, is the same as produced by the
// heavier API point of the same name that takes a Symbol.
oop SystemDictionary::find_java_mirror_for_type(char signature_char) {
return java_lang_Class::primitive_mirror(char2type(signature_char));
}
// Find or construct the Java mirror (java.lang.Class instance) for a
// for the given field type signature, as interpreted relative to the
// given class loader. Handles primitives, void, references, arrays,
// and all other reflectable types, except method types.
// N.B. Code in reflection should use this entry point.
Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
Klass* accessing_klass,
Handle class_loader,
Handle protection_domain,
SignatureStream::FailureMode failure_mode,
TRAPS) {
Handle empty;
assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
"one or the other, or perhaps neither");
Symbol* type = signature;
// What we have here must be a valid field descriptor,
// and all valid field descriptors are supported.
// Produce the same java.lang.Class that reflection reports.
if (type->utf8_length() == 1) {
// It's a primitive. (Void has a primitive mirror too.)
char ch = type->char_at(0);
assert(is_java_primitive(char2type(ch)) || ch == JVM_SIGNATURE_VOID, "");
return Handle(THREAD, find_java_mirror_for_type(ch));
} else if (FieldType::is_obj(type) || FieldType::is_array(type)) {
// It's a reference type.
if (accessing_klass != NULL) {
class_loader = Handle(THREAD, accessing_klass->class_loader());
protection_domain = Handle(THREAD, accessing_klass->protection_domain());
}
Klass* constant_type_klass;
if (failure_mode == SignatureStream::ReturnNull) {
constant_type_klass = resolve_or_null(type, class_loader, protection_domain,
CHECK_(empty));
} else {
bool throw_error = (failure_mode == SignatureStream::NCDFError);
constant_type_klass = resolve_or_fail(type, class_loader, protection_domain,
throw_error, CHECK_(empty));
}
if (constant_type_klass == NULL) {
return Handle(); // report failure this way
}
Handle mirror(THREAD, constant_type_klass->java_mirror());
// Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
if (accessing_klass != NULL) {
Klass* sel_klass = constant_type_klass;
bool fold_type_to_class = true;
LinkResolver::check_klass_accessability(accessing_klass, sel_klass,
fold_type_to_class, CHECK_(empty));
}
return mirror;
}
// Fall through to an error.
assert(false, "unsupported mirror syntax");
THROW_MSG_(vmSymbols::java_lang_InternalError(), "unsupported mirror syntax", empty);
}
// 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,
Klass* 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->can_call_java()) {
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;
if (accessing_klass != NULL) {
class_loader = Handle(THREAD, accessing_klass->class_loader());
protection_domain = Handle(THREAD, accessing_klass->protection_domain());
}
bool can_be_cached = true;
/**代码未完, 请加载全部代码(NowJava.com).**/
关注时代Java
关注时代Java