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android / platform / libcore / e4be9680cb5 / . / src / hotspot / share / classfile / systemDictionary.cpp
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/*
* Copyright (c) 1997, 2021, 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 "cds/heapShared.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/classLoadInfo.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/vmClasses.hpp"
#include "classfile/vmSymbols.hpp"
#include "code/codeCache.hpp"
#include "gc/shared/gcTraceTime.inline.hpp"
#include "interpreter/bootstrapInfo.hpp"
#include "jfr/jfrEvents.hpp"
#include "logging/log.hpp"
#include "logging/logStream.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/klass.inline.hpp"
#include "oops/method.inline.hpp"
#include "oops/objArrayKlass.hpp"
#include "oops/objArrayOop.inline.hpp"
#include "oops/oop.inline.hpp"
#include "oops/oopHandle.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/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"
#include "utilities/utf8.hpp"
#if INCLUDE_CDS
#include "classfile/systemDictionaryShared.hpp"
#endif
#if INCLUDE_JFR
#include "jfr/jfr.hpp"
#endif
ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
ProtectionDomainCacheTable* SystemDictionary::_pd_cache_table = NULL;
OopHandle SystemDictionary::_java_system_loader;
OopHandle SystemDictionary::_java_platform_loader;
// Default ProtectionDomainCacheSize value
const int defaultProtectionDomainCacheSize = 1009;
const int _resolution_error_size = 107; // number of entries in resolution error table
const int _invoke_method_size = 139; // number of entries in invoke method table
// Hashtable holding placeholders for classes being loaded.
const int _placeholder_table_size = 1009;
static PlaceholderTable* _placeholders = NULL;
static PlaceholderTable* placeholders() { return _placeholders; }
// Constraints on class loaders
const int _loader_constraint_size = 107; // number of entries in constraint table
static LoaderConstraintTable* _loader_constraints;
static LoaderConstraintTable* constraints() { return _loader_constraints; }
// ----------------------------------------------------------------------------
// Java-level SystemLoader and PlatformLoader
oop SystemDictionary::java_system_loader() {
return _java_system_loader.resolve();
}
oop SystemDictionary::java_platform_loader() {
return _java_platform_loader.resolve();
}
void SystemDictionary::compute_java_loaders(TRAPS) {
JavaValue result(T_OBJECT);
InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
JavaCalls::call_static(&result,
class_loader_klass,
vmSymbols::getSystemClassLoader_name(),
vmSymbols::void_classloader_signature(),
CHECK);
_java_system_loader = OopHandle(Universe::vm_global(), result.get_oop());
JavaCalls::call_static(&result,
class_loader_klass,
vmSymbols::getPlatformClassLoader_name(),
vmSymbols::void_classloader_signature(),
CHECK);
_java_platform_loader = OopHandle(Universe::vm_global(), result.get_oop());
}
ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
if (create_mirror_cld) {
// Add a new class loader data to the graph.
return ClassLoaderDataGraph::add(class_loader, true);
} else {
return (class_loader() == NULL) ? ClassLoaderData::the_null_class_loader_data() :
ClassLoaderDataGraph::find_or_create(class_loader);
}
}
// ----------------------------------------------------------------------------
// Parallel class loading check
bool 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 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() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
class_loader == _java_system_loader.peek());
}
// 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() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
}
Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
// If class_loader is NULL or parallelCapable, the JVM doesn't acquire a lock while loading.
if (is_parallelCapable(class_loader)) {
return Handle();
} else {
return class_loader;
}
}
// ----------------------------------------------------------------------------
// Resolving of classes
Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
if (name == NULL) {
THROW_MSG_0(exception, "No class name given");
}
if ((int)strlen(name) > Symbol::max_length()) {
// It's impossible to create this class; the name cannot fit
// into the constant pool.
Exceptions::fthrow(THREAD_AND_LOCATION, exception,
"Class name exceeds maximum length of %d: %s",
Symbol::max_length(),
name);
return NULL;
}
// Callers should ensure that the name is never an illegal UTF8 string.
assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false),
"Class name is not a valid utf8 string.");
// Make a new symbol for the class name.
return SymbolTable::new_symbol(name);
}
#ifdef ASSERT
// Used to verify that class loading succeeded in adding k to the dictionary.
void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
MutexLocker mu(SystemDictionary_lock);
ClassLoaderData* loader_data = k->class_loader_data();
Dictionary* dictionary = loader_data->dictionary();
assert(class_name == k->name(), "Must be the same");
unsigned int name_hash = dictionary->compute_hash(class_name);
InstanceKlass* kk = dictionary->find_class(name_hash, class_name);
assert(kk == k, "should be present in dictionary");
}
#endif
static void handle_resolution_exception(Symbol* class_name, bool throw_error, 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 convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
ResourceMark rm(THREAD);
Handle e(THREAD, PENDING_EXCEPTION);
CLEAR_PENDING_EXCEPTION;
THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
} else {
return; // the caller will throw the incoming exception
}
}
// If the class is not found, ie, caller has checked that klass is NULL, throw the appropriate
// error or exception depending on the value of throw_error.
ResourceMark rm(THREAD);
if (throw_error) {
THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
} else {
THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
}
}
// 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);
// Check for pending exception or null klass, and throw exception
if (HAS_PENDING_EXCEPTION || klass == NULL) {
handle_resolution_exception(class_name, throw_error, CHECK_NULL);
}
return klass;
}
// 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 (Signature::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 && !Signature::is_array(class_name), "must be");
if (Signature::has_envelope(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);
}
}
// 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(Signature::is_array(class_name), "must be array");
ResourceMark rm(THREAD);
SignatureStream ss(class_name, false);
int ndims = ss.skip_array_prefix(); // skip all '['s
Klass* k = NULL;
BasicType t = ss.type();
if (ss.has_envelope()) {
Symbol* obj_class = ss.as_symbol();
k = SystemDictionary::resolve_instance_class_or_null(obj_class,
class_loader,
protection_domain,
CHECK_NULL);
if (k != NULL) {
k = k->array_klass(ndims, CHECK_NULL);
}
} else {
k = Universe::typeArrayKlassObj(t);
k = TypeArrayKlass::cast(k)->array_klass(ndims, CHECK_NULL);
}
return k;
}
static inline void log_circularity_error(Thread* thread, PlaceholderEntry* probe) {
LogTarget(Debug, class, load, placeholders) lt;
if (lt.is_enabled()) {
ResourceMark rm(thread);
LogStream ls(lt);
ls.print("ClassCircularityError detected for placeholder ");
probe->print_entry(&ls);
ls.cr();
}
}
// Must be called for any superclass or superinterface resolution
// during class definition to allow class circularity checking
// superinterface callers:
// parse_interfaces - from defineClass
// superclass callers:
// ClassFileParser - from defineClass
// 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
// superclass checks on its own thread to catch class circularity and
// to avoid deadlock.
//
// resolve_super_or_fail adds a LOAD_SUPER placeholder to the placeholder table before calling
// resolve_instance_class_or_null. ClassCircularityError is detected when a LOAD_SUPER or LOAD_INSTANCE
// placeholder for the same thread, class, classloader is found.
// This can be seen with logging option: -Xlog:class+load+placeholders=debug.
//
InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* class_name,
Symbol* super_name,
Handle class_loader,
Handle protection_domain,
bool is_superclass,
TRAPS) {
assert(super_name != NULL, "null superclass for resolving");
assert(!Signature::is_array(super_name), "invalid superclass name");
#if INCLUDE_CDS
if (DumpSharedSpaces) {
// Special processing for handling UNREGISTERED shared classes.
InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
super_name, is_superclass);
if (k) {
return k;
}
}
#endif // INCLUDE_CDS
// If klass is already loaded, just return the superclass or superinterface.
// Make sure there's a placeholder for the class_name before resolving.
// This is used as a claim that this thread is currently loading superclass/classloader
// and for ClassCircularity checks.
ClassLoaderData* loader_data = class_loader_data(class_loader);
Dictionary* dictionary = loader_data->dictionary();
unsigned int name_hash = dictionary->compute_hash(class_name);
assert(placeholders()->compute_hash(class_name) == name_hash, "they're the same hashcode");
// can't throw error holding a lock
bool throw_circularity_error = false;
{
MutexLocker mu(THREAD, SystemDictionary_lock);
InstanceKlass* klassk = dictionary->find_class(name_hash, class_name);
InstanceKlass* quicksuperk;
// To support parallel loading: if class is done loading, just return the superclass
// if the super_name matches class->super()->name() and if the class loaders match.
// Otherwise, a LinkageError will be thrown later.
if (klassk != NULL && is_superclass &&
((quicksuperk = klassk->java_super()) != NULL) &&
((quicksuperk->name() == super_name) &&
(quicksuperk->class_loader() == class_loader()))) {
return quicksuperk;
} else {
// Must check ClassCircularity before checking if superclass is already loaded.
PlaceholderEntry* probe = placeholders()->get_entry(name_hash, class_name, loader_data);
if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
log_circularity_error(THREAD, probe);
throw_circularity_error = true;
}
}
if (!throw_circularity_error) {
// Be careful not to exit resolve_super without removing this placeholder.
PlaceholderEntry* newprobe = placeholders()->find_and_add(name_hash,
class_name,
loader_data,
PlaceholderTable::LOAD_SUPER,
super_name, THREAD);
}
}
if (throw_circularity_error) {
ResourceMark rm(THREAD);
THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
}
// Resolve the superclass or superinterface, check results on return
InstanceKlass* superk =
SystemDictionary::resolve_instance_class_or_null_helper(super_name,
class_loader,
protection_domain,
THREAD);
// Clean up placeholder entry.
{
MutexLocker mu(THREAD, SystemDictionary_lock);
placeholders()->find_and_remove(name_hash, class_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
SystemDictionary_lock->notify_all();
}
// Check for pending exception or null superk, and throw exception
if (HAS_PENDING_EXCEPTION || superk == NULL) {
handle_resolution_exception(super_name, true, CHECK_NULL);
}
return superk;
}
// 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.
static void double_lock_wait(JavaThread* thread, Handle lockObject) {
assert_lock_strong(SystemDictionary_lock);
assert(lockObject() != NULL, "lockObject must be non-NULL");
bool calledholdinglock
= ObjectSynchronizer::current_thread_holds_lock(thread, lockObject);
assert(calledholdinglock, "must hold lock for notify");
assert(!is_parallelCapable(lockObject), "lockObject must not be parallelCapable");
// These don't throw exceptions.
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 new thread internally, so we do parallel
// superclass loading here. This avoids deadlock for ClassCircularity
// detection for parallelCapable class loaders that lock on a per-class lock.
static void handle_parallel_super_load(Symbol* name,
Symbol* superclassname,
Handle class_loader,
Handle protection_domain, TRAPS) {
// superk is not used; resolve_super_or_fail is called for circularity check only.
Klass* superk = SystemDictionary::resolve_super_or_fail(name,
superclassname,
class_loader,
protection_domain,
true,
CHECK);
}
// parallelCapable class loaders do NOT wait for parallel superclass loads to complete
// Serial class loaders and bootstrap classloader do wait for superclass loads
static bool should_wait_for_loading(Handle class_loader) {
return class_loader.is_null() || !is_parallelCapable(class_loader);
}
// For bootstrap and non-parallelCapable class loaders, check and wait for
// another thread to complete loading this class.
InstanceKlass* SystemDictionary::handle_parallel_loading(JavaThread* current,
unsigned int name_hash,
Symbol* name,
ClassLoaderData* loader_data,
Handle lockObject,
bool* throw_circularity_error) {
PlaceholderEntry* oldprobe = placeholders()->get_entry(name_hash, name, loader_data);
if (oldprobe != NULL) {
// only need check_seen_thread once, not on each loop
// 6341374 java/lang/Instrument with -Xcomp
if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
log_circularity_error(current, oldprobe);
*throw_circularity_error = true;
return NULL;
} else {
// Wait until the first thread has finished loading this class. Also wait until all the
// threads trying to load its superclass have removed their placeholders.
while (oldprobe != NULL &&
(oldprobe->instance_load_in_progress() || oldprobe->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.
oldprobe = NULL; // Other thread could delete this placeholder entry
if (lockObject.is_null()) {
SystemDictionary_lock->wait();
} else {
double_lock_wait(current, lockObject);
}
// Check if classloading completed while we were waiting
InstanceKlass* check = loader_data->dictionary()->find_class(name_hash, name);
if (check != NULL) {
// Klass is already loaded, so just return it
return check;
}
// check if other thread failed to load and cleaned up
oldprobe = placeholders()->get_entry(name_hash, name, loader_data);
}
}
}
return NULL;
}
void SystemDictionary::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();
}
// SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
// After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
// whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
// which will load the class via the bootstrap loader or call ClassLoader.loadClass().
// This can return NULL, an exception or an InstanceKlass.
InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
// name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
assert(name != NULL && !Signature::is_array(name) &&
!Signature::has_envelope(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 name_hash = dictionary->compute_hash(name);
// Do lookup to see if class already exists 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 loaded_class so that
// before we return a result, we call out to java to check for valid protection domain.
InstanceKlass* probe = dictionary->find(name_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 class loaders and the bootstrap classloader
// do not acquire lock here.
Handle lockObject = get_loader_lock_or_null(class_loader);
ObjectLocker ol(lockObject, THREAD->as_Java_thread());
bool super_load_in_progress = false;
InstanceKlass* loaded_class = NULL;
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());
assert(placeholders()->compute_hash(name) == name_hash, "they're the same hashcode");
// Check again (after locking) if the class already exists in SystemDictionary
{
MutexLocker mu(THREAD, SystemDictionary_lock);
InstanceKlass* check = dictionary->find_class(name_hash, name);
if (check != NULL) {
// InstanceKlass is already loaded, but we still need to check protection domain below.
loaded_class = check;
} else {
PlaceholderEntry* placeholder = placeholders()->get_entry(name_hash, name, loader_data);
if (placeholder != NULL && placeholder->super_load_in_progress()) {
super_load_in_progress = true;
superclassname = placeholder->supername();
assert(superclassname != NULL, "superclass has to have a name");
}
}
}
// If the class is in the placeholder table with super_class set,
// handle superclass loading in progress.
if (super_load_in_progress) {
handle_parallel_super_load(name, superclassname,
class_loader,
protection_domain,
CHECK_NULL);
}
bool throw_circularity_error = false;
if (loaded_class == NULL) {
bool load_placeholder_added = false;
// Add placeholder entry to record loading instance class
// Four cases:
// case 1. Bootstrap classloader
// This classloader supports parallelism at the classloader level
// but only allows a single thread to load a class/classloader pair.
// The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
// case 2. parallelCapable user level classloaders
// These class loaders lock a per-class object lock when ClassLoader.loadClass()
// is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
// case 3. traditional classloaders that rely on the classloader object lock
// There should be no need for need for LOAD_INSTANCE, except:
// case 4. traditional class loaders that break the classloader object lock
// as a legacy 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.
{
MutexLocker mu(THREAD, SystemDictionary_lock);
if (should_wait_for_loading(class_loader)) {
loaded_class = handle_parallel_loading(THREAD->as_Java_thread(),
name_hash,
name,
loader_data,
lockObject,
&throw_circularity_error);
}
// Recheck if the class has been loaded for all class loader cases and
// add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
if (!throw_circularity_error && loaded_class == NULL) {
InstanceKlass* check = dictionary->find_class(name_hash, name);
if (check != NULL) {
loaded_class = check;
} else if (should_wait_for_loading(class_loader)) {
// Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
PlaceholderEntry* newprobe = placeholders()->find_and_add(name_hash, name, loader_data,
PlaceholderTable::LOAD_INSTANCE,
NULL,
THREAD);
load_placeholder_added = true;
}
}
}
// Must throw error outside of owning lock
if (throw_circularity_error) {
assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
ResourceMark rm(THREAD);
THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
}
// 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 between these calls.
if (loaded_class == NULL) {
// Do actual loading
loaded_class = load_instance_class(name_hash, name, class_loader, THREAD);
}
if (load_placeholder_added) {
// clean up placeholder entries for LOAD_INSTANCE success or error
// This brackets the SystemDictionary updates for both defining
// and initiating loaders
MutexLocker mu(THREAD, SystemDictionary_lock);
placeholders()->find_and_remove(name_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
SystemDictionary_lock->notify_all();
}
}
if (HAS_PENDING_EXCEPTION || loaded_class == NULL) {
return NULL;
}
if (class_load_start_event.should_commit()) {
post_class_load_event(&class_load_start_event, loaded_class, loader_data);
}
// Make sure we have the right class in the dictionary
DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
// Check if the protection domain is present it has the right access
if (protection_domain() != NULL) {
// Verify protection domain. If it fails an exception is thrown
dictionary->validate_protection_domain(name_hash, loaded_class, class_loader, protection_domain, CHECK_NULL);
}
return loaded_class;
}
// This routine does not lock the system dictionary.
//
// Since readers don't hold a lock, we must make sure that system
// dictionary entries are added to in a safe way (all links must
// be updated in an MT-safe manner). All entries are removed during class
// unloading, when this class loader is no longer referenced.
//
// 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.
InstanceKlass* SystemDictionary::find_instance_klass(Symbol* class_name,
Handle class_loader,
Handle protection_domain) {
// 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.
oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
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 name_hash = dictionary->compute_hash(class_name);
return dictionary->find(name_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) {
Klass* k = NULL;
assert(class_name != NULL, "class name must be non NULL");
if (Signature::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
SignatureStream ss(class_name, false);
int ndims = ss.skip_array_prefix(); // skip all '['s
BasicType t = ss.type();
if (t != T_OBJECT) {
k = Universe::typeArrayKlassObj(t);
} else {
k = SystemDictionary::find_instance_klass(ss.as_symbol(), class_loader, protection_domain);
}
if (k != NULL) {
k = k->array_klass_or_null(ndims);
}
} else {
k = find_instance_klass(class_name, class_loader, protection_domain);
}
return k;
}
// Note: this method is much like resolve_class_from_stream, but
// does not publish the classes in the SystemDictionary.
// Handles Lookup.defineClass hidden and unsafe_DefineAnonymousClass.
InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
ClassFileStream* st,
Symbol* class_name,
Handle class_loader,
const ClassLoadInfo& cl_info,
TRAPS) {
EventClassLoad class_load_start_event;
ClassLoaderData* loader_data;
bool is_unsafe_anon_class = cl_info.unsafe_anonymous_host() != NULL;
// - for unsafe anonymous class: create a new CLD whith a class holder that uses
// the same class loader as the unsafe_anonymous_host.
// - for hidden classes that are not strong: create a new CLD that has a class holder and
// whose loader is the Lookup class's loader.
// - for hidden class: add the class to the Lookup class's loader's CLD.
assert (is_unsafe_anon_class || cl_info.is_hidden(), "only used for hidden classes");
guarantee(!is_unsafe_anon_class || cl_info.unsafe_anonymous_host()->class_loader() == class_loader(),
"should be NULL or the same");
bool create_mirror_cld = is_unsafe_anon_class || !cl_info.is_strong_hidden();
loader_data = register_loader(class_loader, create_mirror_cld);
assert(st != NULL, "invariant");
assert(st->need_verify(), "invariant");
// Parse stream and create a klass.
InstanceKlass* k = KlassFactory::create_from_stream(st,
class_name,
loader_data,
cl_info,
CHECK_NULL);
assert(k != NULL, "no klass created");
// Hidden classes that are not strong and unsafe anonymous classes must update
// ClassLoaderData holder so that they can be unloaded when the mirror is no
// longer referenced.
if (!cl_info.is_strong_hidden() || is_unsafe_anon_class) {
k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
}
{
MutexLocker mu_r(THREAD, Compile_lock);
// Add to class hierarchy, and do possible deoptimizations.
add_to_hierarchy(k);
// But, do not add to dictionary.
}
// Rewrite and patch constant pool here.
k->link_class(CHECK_NULL);
if (cl_info.cp_patches() != NULL) {
k->constants()->patch_resolved_references(cl_info.cp_patches());
}
// If it's anonymous, initialize it now, since nobody else will.
if (is_unsafe_anon_class) {
k->eager_initialize(CHECK_NULL);
}
// notify jvmti
if (JvmtiExport::should_post_class_load()) {
JvmtiExport::post_class_load(THREAD->as_Java_thread(), k);
}
if (class_load_start_event.should_commit()) {
post_class_load_event(&class_load_start_event, k, loader_data);
}
assert(is_unsafe_anon_class || NULL == cl_info.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.
// This function either returns an InstanceKlass or throws an exception. It does
// not return NULL without a pending exception.
InstanceKlass* SystemDictionary::resolve_class_from_stream(
ClassFileStream* st,
Symbol* class_name,
Handle class_loader,
const ClassLoadInfo& cl_info,
TRAPS) {
HandleMark hm(THREAD);
ClassLoaderData* loader_data = register_loader(class_loader);
// Classloaders that support parallelism, e.g. bootstrap classloader,
// do not acquire lock here
Handle lockObject = get_loader_lock_or_null(class_loader);
ObjectLocker ol(lockObject, THREAD->as_Java_thread());
// 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,
cl_info.protection_domain(),
st,
CHECK_NULL);
}
#endif
if (k == NULL) {
k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, 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,
// in which case the old k would be deallocated
if (is_parallelCapable(class_loader)) {
k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
} else {
define_instance_class(k, class_loader, 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(verify_dictionary_entry(h_name, k));
return k;
}
InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
Symbol* class_name,
Handle class_loader,
const ClassLoadInfo& cl_info,
TRAPS) {
bool is_unsafe_anon_class = cl_info.unsafe_anonymous_host() != NULL;
if (cl_info.is_hidden() || is_unsafe_anon_class) {
return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
} else {
return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
}
}
#if INCLUDE_CDS
// Load a class for boot loader from the shared spaces. This also
// forces the superclass and all interfaces to be loaded.
InstanceKlass* SystemDictionary::load_shared_boot_class(Symbol* class_name,
PackageEntry* pkg_entry,
TRAPS) {
assert(UseSharedSpaces, "Sanity check");
InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
if (ik != NULL && ik->is_shared_boot_class()) {
return load_shared_class(ik, Handle(), Handle(), NULL, pkg_entry, THREAD);
}
return NULL;
}
// Check if a shared class can be loaded by the specific classloader.
bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
InstanceKlass* ik,
PackageEntry* pkg_entry,
Handle class_loader) {
assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
"Cannot use sharing if java.base is patched");
// (1) Check if we are loading into the same loader as in dump time.
if (ik->is_shared_boot_class()) {
if (class_loader() != NULL) {
return false;
}
} else if (ik->is_shared_platform_class()) {
if (class_loader() != java_platform_loader()) {
return false;
}
} else if (ik->is_shared_app_class()) {
if (class_loader() != java_system_loader()) {
return false;
}
} else {
// ik was loaded by a custom loader during dump time
if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
return false;
} else {
return true;
}
}
// (2) Check if we are loading into the same module from the same location as in dump time.
if (MetaspaceShared::use_optimized_module_handling()) {
// Class visibility has not changed between dump time and run time, so a class
// that was visible (and thus archived) during dump time is always visible during runtime.
assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
"visibility cannot change between dump time and runtime");
return true;
}
return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
}
bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
InstanceKlass* ik,
PackageEntry* pkg_entry,
Handle class_loader) {
int scp_index = ik->shared_classpath_index();
assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
assert(scp_index >= 0, "must be");
SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
if (!Universe::is_module_initialized()) {
assert(scp_entry != NULL && scp_entry->is_modules_image(),
"Loading non-bootstrap classes before the module system is initialized");
assert(class_loader.is_null(), "sanity");
return true;
}
ModuleEntry* mod_entry = (pkg_entry == NULL) ? NULL : pkg_entry->module();
bool should_be_in_named_module = (mod_entry != NULL && mod_entry->is_named());
bool was_archived_from_named_module = scp_entry->in_named_module();
bool visible;
if (was_archived_from_named_module) {
if (should_be_in_named_module) {
// Is the module loaded from the same location as during dump time?
visible = mod_entry->shared_path_index() == scp_index;
if (visible) {
assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
}
} else {
// During dump time, this class was in a named module, but at run time, this class should be
// in an unnamed module.
visible = false;
}
} else {
if (should_be_in_named_module) {
// During dump time, this class was in an unnamed, but at run time, this class should be
// in a named module.
visible = false;
} else {
visible = true;
}
}
return visible;
}
bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
Handle class_loader, Handle protection_domain,
bool is_superclass, TRAPS) {
assert(super_type->is_shared(), "must be");
// Quick check if the super type has been already loaded.
// + Don't do it for unregistered classes -- they can be unloaded so
// super_type->class_loader_data() could be stale.
// + Don't check if loader data is NULL, ie. the super_type isn't fully loaded.
if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != NULL) {
// Check if the superclass is loaded by the current class_loader
Symbol* name = super_type->name();
InstanceKlass* check = find_instance_klass(name, class_loader, protection_domain);
if (check == super_type) {
return true;
}
}
Klass *found = resolve_super_or_fail(klass->name(), super_type->name(),
class_loader, protection_domain, is_superclass, CHECK_0);
if (found == super_type) {
return true;
} else {
// The dynamically resolved super type is not the same as the one we used during dump time,
// so we cannot use the class.
return false;
}
}
bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
Handle protection_domain, TRAPS) {
// Check 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 &&
!check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
class_loader, protection_domain, true, THREAD)) {
return false;
}
Array<InstanceKlass*>* interfaces = ik->local_interfaces();
int num_interfaces = interfaces->length();
for (int index = 0; index < num_interfaces; index++) {
if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) {
return false;
}
}
return true;
}
InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
Handle class_loader,
Handle protection_domain,
PackageEntry* pkg_entry,
TRAPS) {
InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
Symbol* cn = shared_nest_host->name();
Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
if (s != shared_nest_host) {
// The dynamically resolved nest_host 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");
}
// The lambda proxy class and its nest host have the same class loader and class loader data,
// as verified in SystemDictionaryShared::add_lambda_proxy_class()
assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
assert(shared_nest_host->class_loader_data() == ClassLoaderData::class_loader_data(class_loader()), "mismatched class loader data");
ik->set_nest_host(shared_nest_host);
InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, NULL, pkg_entry, CHECK_NULL);
if (loaded_ik != NULL) {
assert(shared_nest_host->is_same_class_package(ik),
"lambda proxy class and its nest host must be in the same package");
}
return loaded_ik;
}
InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
Handle class_loader,
Handle protection_domain,
const ClassFileStream *cfs,
PackageEntry* pkg_entry,
TRAPS) {
assert(ik != NULL, "sanity");
assert(!ik->is_unshareable_info_restored(), "shared class can be loaded only once");
Symbol* class_name = ik->name();
if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
return NULL;
}
if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {
return NULL;
}
InstanceKlass* new_ik = NULL;
// CFLH check is skipped for VM hidden or anonymous classes (see KlassFactory::create_from_stream).
// It will be skipped for shared VM hidden lambda proxy classes.
if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
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.
// 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.
// Since this class is already locked with parallel capable class
// loaders, including the bootstrap loader via the placeholder table,
// this lock is currently a nop.
ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
{
HandleMark hm(THREAD);
Handle lockObject = get_loader_lock_or_null(class_loader);
ObjectLocker ol(lockObject, THREAD->as_Java_thread());
// 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, pkg_entry, CHECK_NULL);
}
load_shared_class_misc(ik, loader_data);
return ik;
}
void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
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 (loader_data->is_the_null_class_loader_data()) {
int path_index = ik->shared_classpath_index();
ik->set_classpath_index(path_index);
}
// notify a class loaded from shared object
ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
}
#endif // INCLUDE_CDS
InstanceKlass* SystemDictionary::load_instance_class_impl(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 = ClassLoader::package_from_class_name(class_name);
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
if (UseSharedSpaces)
{
PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
k = load_shared_boot_class(class_name, pkg_entry, 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) {
k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
}
return k;
} else {
// Use user specified class loader to load class. Call loadClass operation on class_loader.
ResourceMark rm(THREAD);
JavaThread* jt = THREAD->as_Java_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 = vmClasses::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 = result.get_oop();
// 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;
}
}
InstanceKlass* SystemDictionary::load_instance_class(unsigned int name_hash,
Symbol* name,
Handle class_loader,
TRAPS) {
InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
// If everything was OK (no exceptions, no null return value), and
// class_loader is NOT the defining loader, do a little more bookkeeping.
if (loaded_class != NULL &&
loaded_class->class_loader() != class_loader()) {
check_constraints(name_hash, loaded_class, class_loader, false, CHECK_NULL);
// Record dependency for non-parent delegation.
// This recording keeps the defining class loader of the klass (loaded_class) 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.
ClassLoaderData* loader_data = class_loader_data(class_loader);
loader_data->record_dependency(loaded_class);
{ // Grabbing the Compile_lock prevents systemDictionary updates
// during compilations.
MutexLocker mu(THREAD, Compile_lock);
update_dictionary(name_hash, loaded_class, class_loader);
}
if (JvmtiExport::should_post_class_load()) {
JvmtiExport::post_class_load(THREAD->as_Java_thread(), loaded_class);
}
}
return loaded_class;
}
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, Handle class_loader, TRAPS) {
ClassLoaderData* loader_data = k->class_loader_data();
assert(loader_data->class_loader() == class_loader(), "they must be the same");
// Bootstrap and other parallel classloaders don't acquire a lock,
// they 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 (!is_parallelCapable(class_loader)) {
assert(ObjectSynchronizer::current_thread_holds_lock(THREAD->as_Java_thread(),
get_loader_lock_or_null(class_loader)),
"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 name_hash = dictionary->compute_hash(name_h);
check_constraints(name_hash, k, class_loader, true, CHECK);
// Register class just loaded with class loader (placed in ArrayList)
// 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);
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.
{
MutexLocker mu_r(THREAD, Compile_lock);
// Add to class hierarchy, and do possible deoptimizations.
add_to_hierarchy(k);
// Add to systemDictionary - so other classes can see it.
// Grabs and releases SystemDictionary_lock
update_dictionary(name_hash, k, class_loader);
}
k->eager_initialize(THREAD);
// notify jvmti
if (JvmtiExport::should_post_class_load()) {
JvmtiExport::post_class_load(THREAD->as_Java_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 between these calls.
InstanceKlass* SystemDictionary::find_or_define_helper(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 name_hash = dictionary->compute_hash(name_h);
// Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
{
MutexLocker mu(THREAD, SystemDictionary_lock);
// First check if class already defined
if (is_parallelDefine(class_loader)) {
InstanceKlass* check = dictionary->find_class(name_hash, name_h);
if (check != NULL) {
return check;
}
}
// Acquire define token for this class/classloader
assert(placeholders()->compute_hash(name_h) == name_hash, "they're the same hashcode");
PlaceholderEntry* probe = placeholders()->find_and_add(name_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)) {
InstanceKlass* ik = probe->instance_klass();
placeholders()->find_and_remove(name_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
SystemDictionary_lock->notify_all();
#ifdef ASSERT
InstanceKlass* check = dictionary->find_class(name_hash, name_h);
assert(check != NULL, "definer missed recording success");
#endif
return ik;
} else {
// This thread will define the class (even if earlier thread tried and had an error)
probe->set_definer(THREAD);
}
}
define_instance_class(k, class_loader, THREAD);
// definer must notify any waiting threads
{
MutexLocker mu(THREAD, SystemDictionary_lock);
PlaceholderEntry* probe = placeholders()->get_entry(name_hash, name_h, loader_data);
assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
if (!HAS_PENDING_EXCEPTION) {
probe->set_instance_klass(k);
}
probe->set_definer(NULL);
placeholders()->find_and_remove(name_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
SystemDictionary_lock->notify_all();
}
return HAS_PENDING_EXCEPTION ? NULL : k;
}
// If a class loader supports parallel classloading handle parallel define requests.
// find_or_define_instance_class may return a different InstanceKlass
InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
InstanceKlass* k, TRAPS) {
InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
// Clean up original InstanceKlass if duplicate or error
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");
k->class_loader_data()->add_to_deallocate_list(k);
} else if (HAS_PENDING_EXCEPTION) {
assert(defined_k == NULL, "Should not have a klass if there's an exception");
k->class_loader_data()->add_to_deallocate_list(k);
}
return defined_k;
}
// ----------------------------------------------------------------------------
// Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Compile_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) {
assert(k != NULL, "just checking");
if (Universe::is_fully_initialized()) {
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(); // 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)
if (Universe::is_fully_initialized()) {
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();
if (java_lang_System::allow_security_manager()) {
// 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();
} else {
assert(_pd_cache_table->number_of_entries() == 0, "should be empty");
}
}
return unloading_occurred;
}
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);
// Resolve basic classes
vmClasses::resolve_all(CHECK);
// Resolve classes used by archived heap objects
if (UseSharedSpaces) {
HeapShared::resolve_classes(THREAD);
}
}
// 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 name_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(THREAD, SystemDictionary_lock);
InstanceKlass* check = loader_data->dictionary()->find_class(name_hash, name);
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.
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;
}
}
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 hash,
InstanceKlass* k,
Handle class_loader) {
// 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);
// Make a new dictionary entry.
Dictionary* dictionary = loader_data->dictionary();
InstanceKlass* sd_check = dictionary->find_class(hash, name);
if (sd_check == NULL) {
dictionary->add_klass(hash, name, k);
}
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(
Thread* current, Symbol* class_name, Handle class_loader) {
// 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);
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 (Signature::is_array(class_name)) {
// For array classes, their Klass*s are not kept in the
// constraint table. The element Klass*s are.
SignatureStream ss(class_name, false);
int ndims = ss.skip_array_prefix(); // skip all '['s
BasicType t = ss.type();
if (t != T_OBJECT) {
klass = Universe::typeArrayKlassObj(t);
} else {
MutexLocker mu(current, SystemDictionary_lock);
klass = constraints()->find_constrained_klass(ss.as_symbol(), class_loader);
}
// If element class already loaded, allocate array klass
if (klass != NULL) {
klass = klass->array_klass_or_null(ndims);
}
} else {
MutexLocker mu(current, SystemDictionary_lock);
// 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,
Klass* klass_being_linked,
Handle class_loader1,
Handle class_loader2) {
ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
Symbol* constraint_name = NULL;
if (!Signature::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.
SignatureStream ss(class_name, false);
ss.skip_array_prefix(); // skip all '['s
if (!ss.has_envelope()) {
return true; // primitive types always pass
}
constraint_name = ss.as_symbol();
// Increment refcount to keep constraint_name alive after
// SignatureStream is destructed. It will be decremented below
// before returning.
constraint_name->increment_refcount();
}
Dictionary* dictionary1 = loader_data1->dictionary();
unsigned int name_hash1 = dictionary1->compute_hash(constraint_name);
Dictionary* dictionary2 = loader_data2->dictionary();
unsigned int name_hash2 = dictionary2->compute_hash(constraint_name);
{
MutexLocker mu_s(SystemDictionary_lock);
InstanceKlass* klass1 = dictionary1->find_class(name_hash1, constraint_name);
InstanceKlass* klass2 = dictionary2->find_class(name_hash2, constraint_name);
bool result = constraints()->add_entry(constraint_name, klass1, class_loader1,
klass2, class_loader2);
#if INCLUDE_CDS
if (Arguments::is_dumping_archive() && klass_being_linked != NULL &&
!klass_being_linked->is_shared()) {
SystemDictionaryShared::record_linking_constraint(constraint_name,
InstanceKlass::cast(klass_being_linked),
class_loader1, class_loader2);
}
#endif // INCLUDE_CDS
if (Signature::is_array(class_name)) {
constraint_name->decrement_refcount();
}
return result;
}
}
// 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,
Symbol* cause, Symbol* cause_msg) {
unsigned int hash = resolution_errors()->compute_hash(pool, which);
int index = resolution_errors()->hash_to_index(hash);
{
MutexLocker ml(Thread::current(), SystemDictionary_lock);
ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
if (entry == NULL) {
resolution_errors()->add_entry(index, hash, pool, which, error, message, cause, cause_msg);
}
}
}
// 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, Symbol** cause, Symbol** cause_msg) {
unsigned int hash = resolution_errors()->compute_hash(pool, which);
int index = resolution_errors()->hash_to_index(hash);
{
MutexLocker ml(Thread::current(), SystemDictionary_lock);
ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
if (entry != NULL) {
*message = entry->message();
*cause = entry->cause();
*cause_msg = entry->cause_msg();
return entry->error();
} else {
return NULL;
}
}
}
// Add an entry to resolution error table to record an error in resolving or
// validating a nest host. This is used to construct informative error
// messages when IllegalAccessError's occur. If an entry already exists it will
// be updated with the nest host error message.
void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
int which,
const char* message) {
unsigned int hash = resolution_errors()->compute_hash(pool, which);
int index = resolution_errors()->hash_to_index(hash);
{
MutexLocker ml(Thread::current(), SystemDictionary_lock);
ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
if (entry != NULL) {
assert(entry->nest_host_error() == NULL, "Nest host error message already set!");
entry->set_nest_host_error(message);
} else {
resolution_errors()->add_entry(index, hash, pool, which, message);
}
}
}
// Lookup any nest host error
const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
unsigned int hash = resolution_errors()->compute_hash(pool, which);
int index = resolution_errors()->hash_to_index(hash);
{
MutexLocker ml(Thread::current(), SystemDictionary_lock);
ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
if (entry != NULL) {
return entry->nest_host_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, klass_being_linked, 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,
Klass* klass_being_linked,
Handle loader1, Handle loader2,
bool is_method) {
// Nothing to do if loaders are the same.
if (loader1() == loader2()) {
return NULL;
}
for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
if (ss.is_reference()) {
Symbol* sig = ss.as_symbol();
// Note: In the future, if template-like types can take
// arguments, we will want to recognize them and dig out class
// names hiding inside the argument lists.
if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
return sig;
}
}
}
return NULL;
}
Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
Symbol* signature,
TRAPS) {
methodHandle empty;
const int iid_as_int = vmIntrinsics::as_int(iid);
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_as_int, vmIntrinsics::name_at(iid));
unsigned int hash = invoke_method_table()->compute_hash(signature, iid_as_int);
int index = invoke_method_table()->hash_to_index(hash);
SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid_as_int);
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(THREAD, SystemDictionary_lock);
spe = invoke_method_table()->find_entry(index, hash, signature, iid_as_int);
if (spe == NULL)
spe = invoke_method_table()->add_entry(index, hash, signature, iid_as_int);
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);
LogTarget(Info, methodhandles) lt;
if (lt.develop_is_enabled()) {
ResourceMark rm(THREAD);
LogStream ls(lt);
ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
m->print_on(&ls);
if (appendix != NULL) { ls.print("appendix = "); appendix->print_on(&ls); }
ls.cr();
}
(*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(vmClasses::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,
vmClasses::MethodHandleNatives_klass(),
vmSymbols::linkMethod_name(),
vmSymbols::linkMethod_signature(),
&args, CHECK_NULL);
Handle mname(THREAD, result.get_oop());
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(vmClasses::Object_klass()) || // java.lang
InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
}
// Find or construct the Java mirror (java.lang.Class instance) 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) {
assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
"one or the other, or perhaps neither");
// 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 (accessing_klass != NULL) {
class_loader = Handle(THREAD, accessing_klass->class_loader());
protection_domain = Handle(THREAD, accessing_klass->protection_domain());
}
ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
if (mirror_oop == NULL) {
return Handle(); // report failure this way
}
Handle mirror(THREAD, mirror_oop);
if (accessing_klass != NULL) {
// Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
Klass* sel_klass = java_lang_Class::as_Klass(mirror());
if (sel_klass != NULL) {
LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
}
}
return mirror;
}
// 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;
int null_iid = vmIntrinsics::as_int(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;
int npts = ArgumentCount(signature).size();
objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
int arg = 0;
Handle rt; // the return type from the signature
ResourceMark rm(THREAD);
for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
oop mirror = NULL;
if (can_be_cached) {
// Use neutral class loader to lookup candidate classes to be placed in the cache.
mirror = ss.as_java_mirror(Handle(), Handle(),
SignatureStream::ReturnNull, CHECK_(empty));
if (mirror == NULL || (ss.is_reference() && !is_always_visible_class(mirror))) {
// Fall back to accessing_klass context.
can_be_cached = false;
}
}
if (!can_be_cached) {
// Resolve, throwing a real error if it doesn't work.
mirror = ss.as_java_mirror(class_loader, protection_domain,
SignatureStream::NCDFError, CHECK_(empty));
}
assert(mirror != NULL, "%s", ss.as_symbol()->as_C_string());
if (ss.at_return_type())
rt = Handle(THREAD, mirror);
else
pts->obj_at_put(arg++, mirror);
// Check accessibility.
if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
Klass* sel_klass = java_lang_Class::as_Klass(mirror);
mirror = NULL; // safety
// Emulate ConstantPool::verify_constant_pool_resolve.
LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
}
}
assert(arg == npts, "");
// call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
JavaCallArguments args(Handle(THREAD, rt()));
args.push_oop(pts);
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
vmClasses::MethodHandleNatives_klass(),
vmSymbols::findMethodHandleType_name(),
vmSymbols::findMethodHandleType_signature(),
&args, CHECK_(empty));
Handle method_type(THREAD, result.get_oop());
if (can_be_cached) {
// We can cache this MethodType inside the JVM.
MutexLocker ml(THREAD, SystemDictionary_lock);
spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
if (spe == NULL)
spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
if (spe->method_type() == NULL) {
spe->set_method_type(method_type());
}
}
// report back to the caller with the MethodType
return method_type;
}
Handle SystemDictionary::find_field_handle_type(Symbol* signature,
Klass* accessing_klass,
TRAPS) {
Handle empty;
ResourceMark rm(THREAD);
SignatureStream ss(signature, /*is_method=*/ false);
if (!ss.is_done()) {
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());
}
oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
ss.next();
if (ss.is_done()) {
return Handle(THREAD, mirror);
}
}
return empty;
}
// Ask Java code to find or construct a method handle constant.
Handle SystemDictionary::link_method_handle_constant(Klass* caller,
int ref_kind, //e.g., JVM_REF_invokeVirtual
Klass* callee,
Symbol* name,
Symbol* signature,
TRAPS) {
Handle empty;
if (caller == NULL) {
THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
}
Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
// Put symbolic info from the MH constant into freshly created MemberName and resolve it.
Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
java_lang_invoke_MemberName::set_name (mname(), name_str());
java_lang_invoke_MemberName::set_type (mname(), signature_str());
java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
if (ref_kind == JVM_REF_invokeVirtual &&
MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
// Skip resolution for public signature polymorphic methods such as
// j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
// They require appendix argument which MemberName resolution doesn't handle.
// There's special logic on JDK side to handle them
// (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
} else {
MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
}
// After method/field resolution succeeded, it's safe to resolve MH signature as well.
Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
// call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
JavaCallArguments args;
args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
args.push_int(ref_kind);
args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
args.push_oop(name_str);
args.push_oop(type);
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
vmClasses::MethodHandleNatives_klass(),
vmSymbols::linkMethodHandleConstant_name(),
vmSymbols::linkMethodHandleConstant_signature(),
&args, CHECK_(empty));
return Handle(THREAD, result.get_oop());
}
// Ask Java to run a bootstrap method, in order to create a dynamic call site
// while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
// with linkage results being stored back into the bootstrap specifier.
void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
// Resolve the bootstrap specifier, its name, type, and static arguments
bootstrap_specifier.resolve_bsm(CHECK);
// This should not happen. JDK code should take care of that.
if (bootstrap_specifier.caller() == NULL || bootstrap_specifier.type_arg().is_null()) {
THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
}
bool is_indy = bootstrap_specifier.is_method_call();
objArrayHandle appendix_box;
if (is_indy) {
// Some method calls may require an appendix argument. Arrange to receive it.
appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
assert(appendix_box->obj_at(0) == NULL, "");
}
// call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, condy_index, bsm, type, info)
// indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
JavaCallArguments args;
args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
args.push_int(bootstrap_specifier.bss_index());
args.push_oop(bootstrap_specifier.bsm());
args.push_oop(bootstrap_specifier.name_arg());
args.push_oop(bootstrap_specifier.type_arg());
args.push_oop(bootstrap_specifier.arg_values());
if (is_indy) {
args.push_oop(appendix_box);
}
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
vmClasses::MethodHandleNatives_klass(),
is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
&args, CHECK);
Handle value(THREAD, result.get_oop());
if (is_indy) {
Handle appendix;
Method* method = unpack_method_and_appendix(value,
bootstrap_specifier.caller(),
appendix_box,
&appendix, CHECK);
methodHandle mh(THREAD, method);
bootstrap_specifier.set_resolved_method(mh, appendix);
} else {
bootstrap_specifier.set_resolved_value(value);
}
// sanity check
assert(bootstrap_specifier.is_resolved() ||
(bootstrap_specifier.is_method_call() &&
bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
}
ClassLoaderData* SystemDictionary::class_loader_data(Handle class_loader) {
return ClassLoaderData::class_loader_data(class_loader());
}
bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
assert(m != NULL, "Unexpected NULL Method*");
return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
}
// ----------------------------------------------------------------------------
void SystemDictionary::print_on(outputStream *st) {
CDS_ONLY(SystemDictionaryShared::print_on(st));
GCMutexLocker mu(SystemDictionary_lock);
ClassLoaderDataGraph::print_dictionary(st);
// Placeholders
placeholders()->print_on(st);
st->cr();
// loader constraints - print under SD_lock
constraints()->print_on(st);
st->cr();
_pd_cache_table->print_on(st);
st->cr();
}
void SystemDictionary::print() { print_on(tty); }
void SystemDictionary::verify() {
guarantee(constraints() != NULL,
"Verify of loader constraints failed");
guarantee(placeholders()->number_of_entries() >= 0,
"Verify of placeholders failed");
GCMutexLocker mu(SystemDictionary_lock);
// Verify dictionary
ClassLoaderDataGraph::verify_dictionary();
placeholders()->verify();
// Verify constraint table
guarantee(constraints() != NULL, "Verify of loader constraints failed");
constraints()->verify(placeholders());
_pd_cache_table->verify();
}
void SystemDictionary::dump(outputStream *st, bool verbose) {
assert_locked_or_safepoint(SystemDictionary_lock);
if (verbose) {
print_on(st);
} else {
CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
ClassLoaderDataGraph::print_table_statistics(st);
placeholders()->print_table_statistics(st, "Placeholder Table");
constraints()->print_table_statistics(st, "LoaderConstraints Table");
pd_cache_table()->print_table_statistics(st, "ProtectionDomainCache Table");
}
}
TableStatistics SystemDictionary::placeholders_statistics() {
MutexLocker ml(SystemDictionary_lock);
return placeholders()->statistics_calculate();
}
TableStatistics SystemDictionary::loader_constraints_statistics() {
MutexLocker ml(SystemDictionary_lock);
return constraints()->statistics_calculate();
}
TableStatistics SystemDictionary::protection_domain_cache_statistics() {
MutexLocker ml(SystemDictionary_lock);
return pd_cache_table()->statistics_calculate();
}
// Utility for dumping dictionaries.
SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
DCmdWithParser(output, heap),
_verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
"BOOLEAN", false, "false") {
_dcmdparser.add_dcmd_option(&_verbose);
}
void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
_verbose.value());
VMThread::execute(&dumper);
}