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jdk/src/hotspot/share/classfile/systemDictionary.cpp
Yumin Qi 832272da71 8178349: Cache builtin class loader constraints to avoid re-initializing itable/vtable for shared classes 
Record loader constraints for built-in class which is loaded by app loader or platform loader in shared archive in dump time.  When the class loaded from shared archive at runtime, directly check loader constraints using the saved info so avoid lengthy relayout i/v-table at class link stage.

Reviewed-by: iklam, ccheung
2020-05-01 10:58:45 -07:00

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/*
* Copyright (c) 1997, 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "jvm.h"
#include "aot/aotLoader.hpp"
#include "classfile/classFileParser.hpp"
#include "classfile/classFileStream.hpp"
#include "classfile/classLoader.hpp"
#include "classfile/classLoaderData.inline.hpp"
#include "classfile/classLoaderDataGraph.inline.hpp"
#include "classfile/classLoaderExt.hpp"
#include "classfile/dictionary.hpp"
#include "classfile/javaClasses.inline.hpp"
#include "classfile/klassFactory.hpp"
#include "classfile/loaderConstraints.hpp"
#include "classfile/packageEntry.hpp"
#include "classfile/placeholders.hpp"
#include "classfile/protectionDomainCache.hpp"
#include "classfile/resolutionErrors.hpp"
#include "classfile/stringTable.hpp"
#include "classfile/symbolTable.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "code/codeCache.hpp"
#include "compiler/compileBroker.hpp"
#include "gc/shared/gcTraceTime.inline.hpp"
#include "gc/shared/oopStorage.inline.hpp"
#include "gc/shared/oopStorageSet.hpp"
#include "interpreter/bytecodeStream.hpp"
#include "interpreter/interpreter.hpp"
#include "jfr/jfrEvents.hpp"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/filemap.hpp"
#include "memory/heapShared.hpp"
#include "memory/metaspaceClosure.hpp"
#include "memory/oopFactory.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "oops/access.inline.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/instanceRefKlass.hpp"
#include "oops/klass.inline.hpp"
#include "oops/method.inline.hpp"
#include "oops/methodData.hpp"
#include "oops/objArrayKlass.hpp"
#include "oops/objArrayOop.inline.hpp"
#include "oops/oop.inline.hpp"
#include "oops/symbol.hpp"
#include "oops/typeArrayKlass.hpp"
#include "prims/jvmtiExport.hpp"
#include "prims/methodHandles.hpp"
#include "runtime/arguments.hpp"
#include "runtime/biasedLocking.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/java.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/signature.hpp"
#include "services/classLoadingService.hpp"
#include "services/diagnosticCommand.hpp"
#include "services/threadService.hpp"
#include "utilities/macros.hpp"
#if INCLUDE_CDS
#include "classfile/systemDictionaryShared.hpp"
#endif
#if INCLUDE_JFR
#include "jfr/jfr.hpp"
#endif
PlaceholderTable* SystemDictionary::_placeholders = NULL;
LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
ProtectionDomainCacheTable* SystemDictionary::_pd_cache_table = NULL;
oop SystemDictionary::_system_loader_lock_obj = NULL;
InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
= { NULL /*, NULL...*/ };
InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
oop SystemDictionary::_java_system_loader = NULL;
oop SystemDictionary::_java_platform_loader = NULL;
// Default ProtectionDomainCacheSize value
const int defaultProtectionDomainCacheSize = 1009;
ClassLoadInfo::ClassLoadInfo() {
_protection_domain = Handle();
_unsafe_anonymous_host = NULL;
_cp_patches = NULL;
_class_hidden_info._dynamic_nest_host = NULL;
_class_hidden_info._class_data = Handle();
_is_hidden = false;
_is_strong_hidden = false;
_can_access_vm_annotations = false;
}
ClassLoadInfo::ClassLoadInfo(Handle protection_domain) {
_protection_domain = protection_domain;
_unsafe_anonymous_host = NULL;
_cp_patches = NULL;
_class_hidden_info._dynamic_nest_host = NULL;
_class_hidden_info._class_data = Handle();
_is_hidden = false;
_is_strong_hidden = false;
_can_access_vm_annotations = false;
}
ClassLoadInfo::ClassLoadInfo(Handle protection_domain,
const InstanceKlass* unsafe_anonymous_host,
GrowableArray<Handle>* cp_patches,
InstanceKlass* dynamic_nest_host,
Handle class_data,
bool is_hidden,
bool is_strong_hidden,
bool can_access_vm_annotations) {
_protection_domain = protection_domain;
_unsafe_anonymous_host = unsafe_anonymous_host;
_cp_patches = cp_patches;
_class_hidden_info._dynamic_nest_host = dynamic_nest_host;
_class_hidden_info._class_data = class_data;
_is_hidden = is_hidden;
_is_strong_hidden = is_strong_hidden;
_can_access_vm_annotations = can_access_vm_annotations;
}
// ----------------------------------------------------------------------------
// Java-level SystemLoader and PlatformLoader
oop SystemDictionary::java_system_loader() {
return _java_system_loader;
}
oop SystemDictionary::java_platform_loader() {
return _java_platform_loader;
}
void SystemDictionary::compute_java_loaders(TRAPS) {
JavaValue result(T_OBJECT);
InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
JavaCalls::call_static(&result,
class_loader_klass,
vmSymbols::getSystemClassLoader_name(),
vmSymbols::void_classloader_signature(),
CHECK);
_java_system_loader = (oop)result.get_jobject();
JavaCalls::call_static(&result,
class_loader_klass,
vmSymbols::getPlatformClassLoader_name(),
vmSymbols::void_classloader_signature(),
CHECK);
_java_platform_loader = (oop)result.get_jobject();
}
ClassLoaderData* SystemDictionary::register_loader(Handle class_loader) {
if (class_loader.is_null()) return ClassLoaderData::the_null_class_loader_data();
return ClassLoaderDataGraph::find_or_create(class_loader);
}
// ----------------------------------------------------------------------------
// Parallel class loading check
bool SystemDictionary::is_parallelCapable(Handle class_loader) {
if (class_loader.is_null()) return true;
if (AlwaysLockClassLoader) return false;
return java_lang_ClassLoader::parallelCapable(class_loader());
}
// ----------------------------------------------------------------------------
// ParallelDefineClass flag does not apply to bootclass loader
bool SystemDictionary::is_parallelDefine(Handle class_loader) {
if (class_loader.is_null()) return false;
if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
return true;
}
return false;
}
// Returns true if the passed class loader is the builtin application class loader
// or a custom system class loader. A customer system class loader can be
// specified via -Djava.system.class.loader.
bool SystemDictionary::is_system_class_loader(oop class_loader) {
if (class_loader == NULL) {
return false;
}
return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
class_loader == _java_system_loader);
}
// Returns true if the passed class loader is the platform class loader.
bool SystemDictionary::is_platform_class_loader(oop class_loader) {
if (class_loader == NULL) {
return false;
}
return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
}
// ----------------------------------------------------------------------------
// Resolving of classes
// Forwards to resolve_or_null
Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
if (HAS_PENDING_EXCEPTION || klass == NULL) {
// can return a null klass
klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
}
return klass;
}
Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
bool throw_error,
Klass* klass, TRAPS) {
if (HAS_PENDING_EXCEPTION) {
// If we have a pending exception we forward it to the caller, unless throw_error is true,
// in which case we have to check whether the pending exception is a ClassNotFoundException,
// and if so convert it to a NoClassDefFoundError
// And chain the original ClassNotFoundException
if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
ResourceMark rm(THREAD);
assert(klass == NULL, "Should not have result with exception pending");
Handle e(THREAD, PENDING_EXCEPTION);
CLEAR_PENDING_EXCEPTION;
THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
} else {
return NULL;
}
}
// Class not found, throw appropriate error or exception depending on value of throw_error
if (klass == NULL) {
ResourceMark rm(THREAD);
if (throw_error) {
THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
} else {
THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
}
}
return klass;
}
Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
bool throw_error, TRAPS)
{
return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
}
// Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
if (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);
}
}
Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
return resolve_or_null(class_name, Handle(), Handle(), THREAD);
}
// Forwards to resolve_instance_class_or_null
Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
assert(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;
}
// Must be called for any super-class or super-interface resolution
// during class definition to allow class circularity checking
// super-interface callers:
// parse_interfaces - for defineClass & jvmtiRedefineClasses
// super-class callers:
// ClassFileParser - for defineClass & jvmtiRedefineClasses
// load_shared_class - while loading a class from shared archive
// resolve_instance_class_or_null:
// via: handle_parallel_super_load
// when resolving a class that has an existing placeholder with
// a saved superclass [i.e. a defineClass is currently in progress]
// if another thread is trying to resolve the class, it must do
// super-class checks on its own thread to catch class circularity
// This last call is critical in class circularity checking for cases
// where classloading is delegated to different threads and the
// classloader lock is released.
// Take the case: Base->Super->Base
// 1. If thread T1 tries to do a defineClass of class Base
// resolve_super_or_fail creates placeholder: T1, Base (super Super)
// 2. resolve_instance_class_or_null does not find SD or placeholder for Super
// so it tries to load Super
// 3. If we load the class internally, or user classloader uses same thread
// loadClassFromxxx or defineClass via parseClassFile Super ...
// 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
// 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
// 3.4 calls resolve_super_or_fail Base
// 3.5 finds T1,Base -> throws class circularity
//OR 4. If T2 tries to resolve Super via defineClass Super ...
// 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
// 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
// 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
// 4.4 finds T2, Super -> throws class circularity
// Must be called, even if superclass is null, since this is
// where the placeholder entry is created which claims this
// thread is loading this class/classloader.
// Be careful when modifying this code: once you have run
// placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
// you need to find_and_remove it before returning.
// So be careful to not exit with a CHECK_ macro betweeen these calls.
InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
Symbol* super_name,
Handle class_loader,
Handle protection_domain,
bool is_superclass,
TRAPS) {
assert(!Signature::is_array(super_name), "invalid super class name");
#if INCLUDE_CDS
if (DumpSharedSpaces) {
// Special processing for handling UNREGISTERED shared classes.
InstanceKlass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
super_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
if (k) {
return k;
}
}
#endif // INCLUDE_CDS
// Double-check, if child class is already loaded, just return super-class,interface
// Don't add a placedholder if already loaded, i.e. already in appropriate class loader
// dictionary.
// Make sure there's a placeholder for the *child* before resolving.
// Used as a claim that this thread is currently loading superclass/classloader
// Used here for ClassCircularity checks and also for heap verification
// (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
// Must check ClassCircularity before checking if super class is already loaded.
//
// We might not already have a placeholder if this child_name was
// first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
// the name of the class might not be known until the stream is actually
// parsed.
// Bugs 4643874, 4715493
ClassLoaderData* loader_data = class_loader_data(class_loader);
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(child_name);
unsigned int p_hash = placeholders()->compute_hash(child_name);
int p_index = placeholders()->hash_to_index(p_hash);
// can't throw error holding a lock
bool child_already_loaded = false;
bool throw_circularity_error = false;
{
MutexLocker mu(THREAD, SystemDictionary_lock);
InstanceKlass* childk = find_class(d_hash, child_name, dictionary);
InstanceKlass* quicksuperk;
// to support // loading: if child done loading, just return superclass
// if super_name, & class_loader don't match:
// if initial define, SD update will give LinkageError
// if redefine: compare_class_versions will give HIERARCHY_CHANGED
// so we don't throw an exception here.
// see: nsk redefclass014 & java.lang.instrument Instrument032
if ((childk != NULL ) && (is_superclass) &&
((quicksuperk = childk->java_super()) != NULL) &&
((quicksuperk->name() == super_name) &&
(quicksuperk->class_loader() == class_loader()))) {
return quicksuperk;
} else {
PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
throw_circularity_error = true;
}
}
if (!throw_circularity_error) {
// Be careful not to exit resolve_super
PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, super_name, THREAD);
}
}
if (throw_circularity_error) {
ResourceMark rm(THREAD);
THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
}
// java.lang.Object should have been found above
assert(super_name != NULL, "null super class for resolving");
// Resolve the super class or interface, check results on return
InstanceKlass* superk =
SystemDictionary::resolve_instance_class_or_null_helper(super_name,
class_loader,
protection_domain,
THREAD);
// Clean up of placeholders moved so that each classloadAction registrar self-cleans up
// It is no longer necessary to keep the placeholder table alive until update_dictionary
// or error. GC used to walk the placeholder table as strong roots.
// The instanceKlass is kept alive because the class loader is on the stack,
// which keeps the loader_data alive, as well as all instanceKlasses in
// the loader_data. parseClassFile adds the instanceKlass to loader_data.
{
MutexLocker mu(THREAD, SystemDictionary_lock);
placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
SystemDictionary_lock->notify_all();
}
if (HAS_PENDING_EXCEPTION || superk == NULL) {
// can null superk
Klass* k = handle_resolution_exception(super_name, true, superk, THREAD);
assert(k == NULL || k == superk, "must be");
if (k == NULL) {
superk = NULL;
}
}
return superk;
}
void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
Handle class_loader,
Handle protection_domain,
TRAPS) {
// Now we have to call back to java to check if the initating class has access
JavaValue result(T_VOID);
LogTarget(Debug, protectiondomain) lt;
if (lt.is_enabled()) {
ResourceMark rm(THREAD);
// Print out trace information
LogStream ls(lt);
ls.print_cr("Checking package access");
if (class_loader() != NULL) {
ls.print("class loader: ");
class_loader()->print_value_on(&ls);
} else {
ls.print_cr("class loader: NULL");
}
if (protection_domain() != NULL) {
ls.print(" protection domain: ");
protection_domain()->print_value_on(&ls);
} else {
ls.print_cr(" protection domain: NULL");
}
ls.print(" loading: "); klass->print_value_on(&ls);
ls.cr();
}
// This handle and the class_loader handle passed in keeps this class from
// being unloaded through several GC points.
// The class_loader handle passed in is the initiating loader.
Handle mirror(THREAD, klass->java_mirror());
InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
JavaCalls::call_special(&result,
class_loader,
system_loader,
vmSymbols::checkPackageAccess_name(),
vmSymbols::class_protectiondomain_signature(),
mirror,
protection_domain,
THREAD);
if (HAS_PENDING_EXCEPTION) {
log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
} else {
log_debug(protectiondomain)("granted");
}
if (HAS_PENDING_EXCEPTION) return;
// If no exception has been thrown, we have validated the protection domain
// Insert the protection domain of the initiating class into the set.
{
ClassLoaderData* loader_data = class_loader_data(class_loader);
Dictionary* dictionary = loader_data->dictionary();
Symbol* kn = klass->name();
unsigned int d_hash = dictionary->compute_hash(kn);
MutexLocker mu(THREAD, SystemDictionary_lock);
int d_index = dictionary->hash_to_index(d_hash);
dictionary->add_protection_domain(d_index, d_hash, klass,
protection_domain, THREAD);
}
}
// We only get here if this thread finds that another thread
// has already claimed the placeholder token for the current operation,
// but that other thread either never owned or gave up the
// object lock
// Waits on SystemDictionary_lock to indicate placeholder table updated
// On return, caller must recheck placeholder table state
//
// We only get here if
// 1) custom classLoader, i.e. not bootstrap classloader
// 2) custom classLoader has broken the class loader objectLock
// so another thread got here in parallel
//
// lockObject must be held.
// Complicated dance due to lock ordering:
// Must first release the classloader object lock to
// allow initial definer to complete the class definition
// and to avoid deadlock
// Reclaim classloader lock object with same original recursion count
// Must release SystemDictionary_lock after notify, since
// class loader lock must be claimed before SystemDictionary_lock
// to prevent deadlocks
//
// The notify allows applications that did an untimed wait() on
// the classloader object lock to not hang.
void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
assert_lock_strong(SystemDictionary_lock);
bool calledholdinglock
= ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
assert(calledholdinglock,"must hold lock for notify");
assert((lockObject() != _system_loader_lock_obj && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
ObjectSynchronizer::notifyall(lockObject, THREAD);
intx recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
SystemDictionary_lock->wait();
SystemDictionary_lock->unlock();
ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
SystemDictionary_lock->lock();
}
// If the class in is in the placeholder table, class loading is in progress
// For cases where the application changes threads to load classes, it
// is critical to ClassCircularity detection that we try loading
// the superclass on the same thread internally, so we do parallel
// super class loading here.
// This also is critical in cases where the original thread gets stalled
// even in non-circularity situations.
// Note: must call resolve_super_or_fail even if null super -
// to force placeholder entry creation for this class for circularity detection
// Caller must check for pending exception
// Returns non-null Klass* if other thread has completed load
// and we are done,
// If return null Klass* and no pending exception, the caller must load the class
InstanceKlass* SystemDictionary::handle_parallel_super_load(
Symbol* name, Symbol* superclassname, Handle class_loader,
Handle protection_domain, Handle lockObject, TRAPS) {
ClassLoaderData* loader_data = class_loader_data(class_loader);
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(name);
unsigned int p_hash = placeholders()->compute_hash(name);
int p_index = placeholders()->hash_to_index(p_hash);
// superk is not used, resolve_super called for circularity check only
// This code is reached in two situations. One if this thread
// is loading the same class twice (e.g. ClassCircularity, or
// java.lang.instrument).
// The second is if another thread started the resolve_super first
// and has not yet finished.
// In both cases the original caller will clean up the placeholder
// entry on error.
Klass* superk = SystemDictionary::resolve_super_or_fail(name,
superclassname,
class_loader,
protection_domain,
true,
CHECK_NULL);
// parallelCapable class loaders do NOT wait for parallel superclass loads to complete
// Serial class loaders and bootstrap classloader do wait for superclass loads
if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
MutexLocker mu(THREAD, SystemDictionary_lock);
// Check if classloading completed while we were loading superclass or waiting
return find_class(d_hash, name, dictionary);
}
// must loop to both handle other placeholder updates
// and spurious notifications
bool super_load_in_progress = true;
PlaceholderEntry* placeholder;
while (super_load_in_progress) {
MutexLocker mu(THREAD, SystemDictionary_lock);
// Check if classloading completed while we were loading superclass or waiting
InstanceKlass* check = find_class(d_hash, name, dictionary);
if (check != NULL) {
// Klass is already loaded, so just return it
return check;
} else {
placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
if (placeholder && placeholder->super_load_in_progress() ){
// We only get here if the application has released the
// classloader lock when another thread was in the middle of loading a
// superclass/superinterface for this class, and now
// this thread is also trying to load this class.
// To minimize surprises, the first thread that started to
// load a class should be the one to complete the loading
// with the classfile it initially expected.
// This logic has the current thread wait once it has done
// all the superclass/superinterface loading it can, until
// the original thread completes the class loading or fails
// If it completes we will use the resulting InstanceKlass
// which we will find below in the systemDictionary.
// We also get here for parallel bootstrap classloader
if (class_loader.is_null()) {
SystemDictionary_lock->wait();
} else {
double_lock_wait(lockObject, THREAD);
}
} else {
// If not in SD and not in PH, other thread's load must have failed
super_load_in_progress = false;
}
}
}
return NULL;
}
static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
assert(event != NULL, "invariant");
assert(k != NULL, "invariant");
assert(event->should_commit(), "invariant");
event->set_loadedClass(k);
event->set_definingClassLoader(k->class_loader_data());
event->set_initiatingClassLoader(init_cld);
event->commit();
}
// Be careful when modifying this code: once you have run
// placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
// you need to find_and_remove it before returning.
// So be careful to not exit with a CHECK_ macro betweeen these calls.
//
// name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
assert(name != NULL && !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 d_hash = dictionary->compute_hash(name);
// Do lookup to see if class already exist and the protection domain
// has the right access
// This call uses find which checks protection domain already matches
// All subsequent calls use find_class, and set has_loaded_class so that
// before we return a result we call out to java to check for valid protection domain
// to allow returning the Klass* and add it to the pd_set if it is valid
{
InstanceKlass* probe = dictionary->find(d_hash, name, protection_domain);
if (probe != NULL) return probe;
}
// Non-bootstrap class loaders will call out to class loader and
// define via jvm/jni_DefineClass which will acquire the
// class loader object lock to protect against multiple threads
// defining the class in parallel by accident.
// This lock must be acquired here so the waiter will find
// any successful result in the SystemDictionary and not attempt
// the define.
// ParallelCapable Classloaders and the bootstrap classloader
// do not acquire lock here.
bool DoObjectLock = true;
if (is_parallelCapable(class_loader)) {
DoObjectLock = false;
}
unsigned int p_hash = placeholders()->compute_hash(name);
int p_index = placeholders()->hash_to_index(p_hash);
// Class is not in SystemDictionary so we have to do loading.
// Make sure we are synchronized on the class loader before we proceed
Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
check_loader_lock_contention(lockObject, THREAD);
ObjectLocker ol(lockObject, THREAD, DoObjectLock);
// Check again (after locking) if class already exist in SystemDictionary
bool class_has_been_loaded = false;
bool super_load_in_progress = false;
bool havesupername = false;
InstanceKlass* k = NULL;
PlaceholderEntry* placeholder;
Symbol* superclassname = NULL;
assert(THREAD->can_call_java(),
"can not load classes with compiler thread: class=%s, classloader=%s",
name->as_C_string(),
class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
{
MutexLocker mu(THREAD, SystemDictionary_lock);
InstanceKlass* check = find_class(d_hash, name, dictionary);
if (check != NULL) {
// InstanceKlass is already loaded, so just return it
class_has_been_loaded = true;
k = check;
} else {
placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
if (placeholder && placeholder->super_load_in_progress()) {
super_load_in_progress = true;
if (placeholder->havesupername() == true) {
superclassname = placeholder->supername();
havesupername = true;
}
}
}
}
// If the class is in the placeholder table, class loading is in progress
if (super_load_in_progress && havesupername==true) {
k = handle_parallel_super_load(name,
superclassname,
class_loader,
protection_domain,
lockObject, THREAD);
if (HAS_PENDING_EXCEPTION) {
return NULL;
}
if (k != NULL) {
class_has_been_loaded = true;
}
}
bool throw_circularity_error = false;
if (!class_has_been_loaded) {
bool load_instance_added = false;
// add placeholder entry to record loading instance class
// Five cases:
// All cases need to prevent modifying bootclasssearchpath
// in parallel with a classload of same classname
// Redefineclasses uses existence of the placeholder for the duration
// of the class load to prevent concurrent redefinition of not completely
// defined classes.
// case 1. traditional classloaders that rely on the classloader object lock
// - no other need for LOAD_INSTANCE
// case 2. traditional classloaders that break the classloader object lock
// as a deadlock workaround. Detection of this case requires that
// this check is done while holding the classloader object lock,
// and that lock is still held when calling classloader's loadClass.
// For these classloaders, we ensure that the first requestor
// completes the load and other requestors wait for completion.
// case 3. Bootstrap classloader - don't own objectLocker
// This classloader supports parallelism at the classloader level,
// but only allows a single load of a class/classloader pair.
// No performance benefit and no deadlock issues.
// case 4. parallelCapable user level classloaders - without objectLocker
// Allow parallel classloading of a class/classloader pair
{
MutexLocker mu(THREAD, SystemDictionary_lock);
if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
if (oldprobe) {
// only need check_seen_thread once, not on each loop
// 6341374 java/lang/Instrument with -Xcomp
if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
throw_circularity_error = true;
} else {
// case 1: traditional: should never see load_in_progress.
while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
// case 3: bootstrap classloader: prevent futile classloading,
// wait on first requestor
if (class_loader.is_null()) {
SystemDictionary_lock->wait();
} else {
// case 2: traditional with broken classloader lock. wait on first
// requestor.
double_lock_wait(lockObject, THREAD);
}
// Check if classloading completed while we were waiting
InstanceKlass* check = find_class(d_hash, name, dictionary);
if (check != NULL) {
// Klass is already loaded, so just return it
k = check;
class_has_been_loaded = true;
}
// check if other thread failed to load and cleaned up
oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
}
}
}
}
// All cases: add LOAD_INSTANCE holding SystemDictionary_lock
// case 4: parallelCapable: allow competing threads to try
// LOAD_INSTANCE in parallel
if (!throw_circularity_error && !class_has_been_loaded) {
PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
load_instance_added = true;
// For class loaders that do not acquire the classloader object lock,
// if they did not catch another thread holding LOAD_INSTANCE,
// need a check analogous to the acquire ObjectLocker/find_class
// i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
// one final check if the load has already completed
// class loaders holding the ObjectLock shouldn't find the class here
InstanceKlass* check = find_class(d_hash, name, dictionary);
if (check != NULL) {
// Klass is already loaded, so return it after checking/adding protection domain
k = check;
class_has_been_loaded = true;
}
}
}
// must throw error outside of owning lock
if (throw_circularity_error) {
assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
ResourceMark rm(THREAD);
THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
}
if (!class_has_been_loaded) {
// Do actual loading
k = load_instance_class(name, class_loader, THREAD);
// If everything was OK (no exceptions, no null return value), and
// class_loader is NOT the defining loader, do a little more bookkeeping.
if (!HAS_PENDING_EXCEPTION && k != NULL &&
k->class_loader() != class_loader()) {
check_constraints(d_hash, k, class_loader, false, THREAD);
// Need to check for a PENDING_EXCEPTION again; check_constraints
// can throw but we may have to remove entry from the placeholder table below.
if (!HAS_PENDING_EXCEPTION) {
// Record dependency for non-parent delegation.
// This recording keeps the defining class loader of the klass (k) found
// from being unloaded while the initiating class loader is loaded
// even if the reference to the defining class loader is dropped
// before references to the initiating class loader.
loader_data->record_dependency(k);
{ // Grabbing the Compile_lock prevents systemDictionary updates
// during compilations.
MutexLocker mu(THREAD, Compile_lock);
update_dictionary(d_hash, p_index, p_hash,
k, class_loader, THREAD);
}
if (JvmtiExport::should_post_class_load()) {
Thread *thread = THREAD;
assert(thread->is_Java_thread(), "thread->is_Java_thread()");
JvmtiExport::post_class_load((JavaThread *) thread, k);
}
}
}
} // load_instance_class
if (load_instance_added == true) {
// clean up placeholder entries for LOAD_INSTANCE success or error
// This brackets the SystemDictionary updates for both defining
// and initiating loaders
MutexLocker mu(THREAD, SystemDictionary_lock);
placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
SystemDictionary_lock->notify_all();
}
}
if (HAS_PENDING_EXCEPTION || k == NULL) {
return NULL;
}
if (class_load_start_event.should_commit()) {
post_class_load_event(&class_load_start_event, k, loader_data);
}
#ifdef ASSERT
{
ClassLoaderData* loader_data = k->class_loader_data();
MutexLocker mu(THREAD, SystemDictionary_lock);
InstanceKlass* kk = find_class(name, loader_data);
assert(kk == k, "should be present in dictionary");
}
#endif
// return if the protection domain in NULL
if (protection_domain() == NULL) return k;
// Check the protection domain has the right access
if (dictionary->is_valid_protection_domain(d_hash, name,
protection_domain)) {
return k;
}
// Verify protection domain. If it fails an exception is thrown
validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
return k;
}
// This routine does not lock the system dictionary.
//
// Since readers don't hold a lock, we must make sure that system
// dictionary entries are only removed at a safepoint (when only one
// thread is running), and are added to in a safe way (all links must
// be updated in an MT-safe manner).
//
// Callers should be aware that an entry could be added just after
// _dictionary->bucket(index) is read here, so the caller will not see
// the new entry.
Klass* SystemDictionary::find(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
// The result of this call should be consistent with the result
// of the call to resolve_instance_class_or_null().
// See evaluation 6790209 and 4474172 for more details.
class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
if (loader_data == NULL) {
// If the ClassLoaderData has not been setup,
// then the class loader has no entries in the dictionary.
return NULL;
}
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(class_name);
return dictionary->find(d_hash, class_name,
protection_domain);
}
// Look for a loaded instance or array klass by name. Do not do any loading.
// return NULL in case of error.
Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
TRAPS) {
Klass* k = NULL;
assert(class_name != NULL, "class name must be non NULL");
if (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(ss.as_symbol(), class_loader, protection_domain, THREAD);
}
if (k != NULL) {
k = k->array_klass_or_null(ndims);
}
} else {
k = find(class_name, class_loader, protection_domain, THREAD);
}
return k;
}
// Note: this method is much like resolve_from_stream, but
// does not publish the classes via the SystemDictionary.
// Handles Lookup.defineClass hidden, unsafe_DefineAnonymousClass
// and redefineclasses. RedefinedClasses do not add to the class hierarchy.
InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
Handle class_loader,
ClassFileStream* st,
const ClassLoadInfo& cl_info,
TRAPS) {
EventClassLoad class_load_start_event;
ClassLoaderData* loader_data;
bool is_unsafe_anon_class = cl_info.unsafe_anonymous_host() != NULL;
if (is_unsafe_anon_class) {
// - for unsafe anonymous class: create a new CLD whith a class holder that uses
// the same class loader as the unsafe_anonymous_host.
guarantee(cl_info.unsafe_anonymous_host()->class_loader() == class_loader(),
"should be the same");
loader_data = ClassLoaderData::has_class_mirror_holder_cld(class_loader);
} else if (cl_info.is_hidden()) {
// - for hidden classes that are not strong: create a new CLD that has a class holder and
// whose loader is the Lookup class' loader.
// - for hidden class: add the class to the Lookup class' loader's CLD.
if (!cl_info.is_strong_hidden()) {
loader_data = ClassLoaderData::has_class_mirror_holder_cld(class_loader);
} else {
// This hidden class goes into the regular CLD pool for this loader.
loader_data = register_loader(class_loader);
}
} else {
loader_data = ClassLoaderData::class_loader_data(class_loader());
}
assert(st != NULL, "invariant");
assert(st->need_verify(), "invariant");
// Parse stream and create a klass.
// Note that we do this even though this klass might
// already be present in the SystemDictionary, otherwise we would not
// throw potential ClassFormatErrors.
InstanceKlass* k = KlassFactory::create_from_stream(st,
class_name,
loader_data,
cl_info,
CHECK_NULL);
if ((cl_info.is_hidden() || is_unsafe_anon_class) && k != NULL) {
// 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, initialize vtables, and do possible
// deoptimizations.
add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
// But, do not add to dictionary.
}
// Rewrite and patch constant pool here.
k->link_class(CHECK_NULL);
if (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()) {
assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
JvmtiExport::post_class_load((JavaThread *) THREAD, k);
}
if (class_load_start_event.should_commit()) {
post_class_load_event(&class_load_start_event, k, loader_data);
}
}
assert(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.
InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
Handle class_loader,
Handle protection_domain,
ClassFileStream* st,
TRAPS) {
HandleMark hm(THREAD);
// Classloaders that support parallelism, e.g. bootstrap classloader,
// do not acquire lock here
bool DoObjectLock = true;
if (is_parallelCapable(class_loader)) {
DoObjectLock = false;
}
ClassLoaderData* loader_data = register_loader(class_loader);
// Make sure we are synchronized on the class loader before we proceed
Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
check_loader_lock_contention(lockObject, THREAD);
ObjectLocker ol(lockObject, THREAD, DoObjectLock);
assert(st != NULL, "invariant");
// Parse the stream and create a klass.
// Note that we do this even though this klass might
// already be present in the SystemDictionary, otherwise we would not
// throw potential ClassFormatErrors.
InstanceKlass* k = NULL;
#if INCLUDE_CDS
if (!DumpSharedSpaces) {
k = SystemDictionaryShared::lookup_from_stream(class_name,
class_loader,
protection_domain,
st,
CHECK_NULL);
}
#endif
if (k == NULL) {
if (st->buffer() == NULL) {
return NULL;
}
ClassLoadInfo cl_info(protection_domain);
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
if (is_parallelCapable(class_loader)) {
InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
if (!HAS_PENDING_EXCEPTION && defined_k != k) {
// If a parallel capable class loader already defined this class, register 'k' for cleanup.
assert(defined_k != NULL, "Should have a klass if there's no exception");
loader_data->add_to_deallocate_list(k);
k = defined_k;
}
} else {
define_instance_class(k, THREAD);
}
// If defining the class throws an exception register 'k' for cleanup.
if (HAS_PENDING_EXCEPTION) {
assert(k != NULL, "Must have an instance klass here!");
loader_data->add_to_deallocate_list(k);
return NULL;
}
// Make sure we have an entry in the SystemDictionary on success
debug_only( {
MutexLocker mu(THREAD, SystemDictionary_lock);
Klass* check = find_class(h_name, k->class_loader_data());
assert(check == k, "should be present in the dictionary");
} );
return k;
}
#if INCLUDE_CDS
// Load a class for boot loader from the shared spaces. This also
// forces the super class and all interfaces to be loaded.
InstanceKlass* SystemDictionary::load_shared_boot_class(Symbol* class_name,
PackageEntry* pkg_entry,
TRAPS) {
InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
if (ik != NULL && ik->is_shared_boot_class()) {
return load_shared_class(ik, Handle(), Handle(), NULL, pkg_entry, THREAD);
}
return NULL;
}
// Check if a shared class can be loaded by the specific classloader:
//
// NULL classloader:
// - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
// - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
// be defined in an unnamed module.
bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
InstanceKlass* ik,
PackageEntry* pkg_entry,
Handle class_loader, TRAPS) {
assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
"Cannot use sharing if java.base is patched");
ResourceMark rm(THREAD);
int path_index = ik->shared_classpath_index();
ClassLoaderData* loader_data = class_loader_data(class_loader);
if (path_index < 0) {
// path_index < 0 indicates that the class is intended for a custom loader
// and should not be loaded by boot/platform/app loaders
if (loader_data->is_builtin_class_loader_data()) {
return false;
} else {
return true;
}
}
SharedClassPathEntry* ent =
(SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
if (!Universe::is_module_initialized()) {
assert(ent != NULL && ent->is_modules_image(),
"Loading non-bootstrap classes before the module system is initialized");
assert(class_loader.is_null(), "sanity");
return true;
}
// Get the pkg_entry from the classloader
ModuleEntry* mod_entry = NULL;
TempNewSymbol pkg_name = pkg_entry != NULL ? pkg_entry->name() :
ClassLoader::package_from_class_name(class_name);
if (pkg_name != NULL) {
if (loader_data != NULL) {
if (pkg_entry != NULL) {
mod_entry = pkg_entry->module();
// If the archived class is from a module that has been patched at runtime,
// the class cannot be loaded from the archive.
if (mod_entry != NULL && mod_entry->is_patched()) {
return false;
}
}
}
}
if (class_loader.is_null()) {
assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
// The NULL classloader can load archived class originated from the
// "modules" jimage and the -Xbootclasspath/a. For class from the
// "modules" jimage, the PackageEntry/ModuleEntry must be defined
// by the NULL classloader.
if (mod_entry != NULL) {
// PackageEntry/ModuleEntry is found in the classloader. Check if the
// ModuleEntry's location agrees with the archived class' origination.
if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
return true; // Module class from the "module" jimage
}
}
// If the archived class is not from the "module" jimage, the class can be
// loaded by the NULL classloader if
//
// 1. the class is from the unamed package
// 2. or, the class is not from a module defined in the NULL classloader
// 3. or, the class is from an unamed module
if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
// the class is from the -Xbootclasspath/a
if (pkg_name == NULL ||
pkg_entry == NULL ||
pkg_entry->in_unnamed_module()) {
assert(mod_entry == NULL ||
mod_entry == loader_data->unnamed_module(),
"the unnamed module is not defined in the classloader");
return true;
}
}
return false;
} else {
bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
ik, class_loader, pkg_name, pkg_entry, mod_entry, CHECK_(false));
return res;
}
}
bool SystemDictionary::check_shared_class_super_type(InstanceKlass* child, InstanceKlass* super_type,
Handle class_loader, Handle protection_domain,
bool is_superclass, TRAPS) {
assert(super_type->is_shared(), "must be");
Klass *found = resolve_super_or_fail(child->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 child 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_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();
bool visible = is_shared_class_visible(
class_name, ik, pkg_entry, class_loader, CHECK_NULL);
if (!visible) {
return NULL;
}
if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {
return NULL;
}
InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
if (new_ik != NULL) {
// The class is changed by CFLH. Return the new class. The shared class is
// not used.
return new_ik;
}
// Adjust methods to recover missing data. They need addresses for
// interpreter entry points and their default native method address
// must be reset.
// Updating methods must be done under a lock so multiple
// threads don't update these in parallel
//
// Shared classes are all currently loaded by either the bootstrap or
// internal parallel class loaders, so this will never cause a deadlock
// on a custom class loader lock.
ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
{
HandleMark hm(THREAD);
Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
check_loader_lock_contention(lockObject, THREAD);
ObjectLocker ol(lockObject, THREAD, true);
// prohibited package check assumes all classes loaded from archive call
// restore_unshareable_info which calls ik->set_package()
ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
}
load_shared_class_misc(ik, loader_data, CHECK_NULL);
return ik;
}
void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data, TRAPS) {
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, THREAD);
}
if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
// Only dump the classes that can be stored into CDS archive
if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
ResourceMark rm(THREAD);
classlist_file->print_cr("%s", ik->name()->as_C_string());
classlist_file->flush();
}
}
// notify a class loaded from shared object
ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
ik->set_has_passed_fingerprint_check(false);
if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
uint64_t cds_fp = ik->get_stored_fingerprint();
if (aot_fp != 0 && aot_fp == cds_fp) {
// This class matches with a class saved in an AOT library
ik->set_has_passed_fingerprint_check(true);
} else {
if (log_is_enabled(Info, class, fingerprint)) {
ResourceMark rm(THREAD);
log_info(class, fingerprint)("%s : expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
}
}
}
}
void SystemDictionary::quick_resolve(InstanceKlass* klass, ClassLoaderData* loader_data, Handle domain, TRAPS) {
assert(!Universe::is_fully_initialized(), "We can make short cuts only during VM initialization");
assert(klass->is_shared(), "Must be shared class");
if (klass->class_loader_data() != NULL) {
return;
}
// add super and interfaces first
Klass* super = klass->super();
if (super != NULL && super->class_loader_data() == NULL) {
assert(super->is_instance_klass(), "Super should be instance klass");
quick_resolve(InstanceKlass::cast(super), loader_data, domain, CHECK);
}
Array<InstanceKlass*>* ifs = klass->local_interfaces();
for (int i = 0; i < ifs->length(); i++) {
InstanceKlass* ik = ifs->at(i);
if (ik->class_loader_data() == NULL) {
quick_resolve(ik, loader_data, domain, CHECK);
}
}
klass->restore_unshareable_info(loader_data, domain, NULL, THREAD);
load_shared_class_misc(klass, loader_data, CHECK);
Dictionary* dictionary = loader_data->dictionary();
unsigned int hash = dictionary->compute_hash(klass->name());
dictionary->add_klass(hash, klass->name(), klass);
add_to_hierarchy(klass, CHECK);
assert(klass->is_loaded(), "Must be in at least loaded state");
}
#endif // INCLUDE_CDS
InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
if (class_loader.is_null()) {
ResourceMark rm(THREAD);
PackageEntry* pkg_entry = NULL;
bool search_only_bootloader_append = false;
ClassLoaderData *loader_data = class_loader_data(class_loader);
// Find the package in the boot loader's package entry table.
TempNewSymbol pkg_name = 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
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) {
InstanceKlass* defined_k =
find_or_define_instance_class(class_name, class_loader, k, THREAD);
if (!HAS_PENDING_EXCEPTION && defined_k != k) {
// If a parallel capable class loader already defined this class, register 'k' for cleanup.
assert(defined_k != NULL, "Should have a klass if there's no exception");
loader_data->add_to_deallocate_list(k);
k = defined_k;
} else if (HAS_PENDING_EXCEPTION) {
loader_data->add_to_deallocate_list(k);
return NULL;
}
}
return k;
} else {
// Use user specified class loader to load class. Call loadClass operation on class_loader.
ResourceMark rm(THREAD);
assert(THREAD->is_Java_thread(), "must be a JavaThread");
JavaThread* jt = (JavaThread*) THREAD;
PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
ClassLoader::perf_app_classload_selftime(),
ClassLoader::perf_app_classload_count(),
jt->get_thread_stat()->perf_recursion_counts_addr(),
jt->get_thread_stat()->perf_timers_addr(),
PerfClassTraceTime::CLASS_LOAD);
Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
// Translate to external class name format, i.e., convert '/' chars to '.'
Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
JavaValue result(T_OBJECT);
InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
// Call public unsynchronized loadClass(String) directly for all class loaders.
// For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
// acquire a class-name based lock rather than the class loader object lock.
// JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
JavaCalls::call_virtual(&result,
class_loader,
spec_klass,
vmSymbols::loadClass_name(),
vmSymbols::string_class_signature(),
string,
CHECK_NULL);
assert(result.get_type() == T_OBJECT, "just checking");
oop obj = (oop) result.get_jobject();
// Primitive classes return null since forName() can not be
// used to obtain any of the Class objects representing primitives or void
if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
// For user defined Java class loaders, check that the name returned is
// the same as that requested. This check is done for the bootstrap
// loader when parsing the class file.
if (class_name == k->name()) {
return k;
}
}
// Class is not found or has the wrong name, return NULL
return NULL;
}
}
static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
EventClassDefine event;
if (event.should_commit()) {
event.set_definedClass(k);
event.set_definingClassLoader(def_cld);
event.commit();
}
}
void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
HandleMark hm(THREAD);
ClassLoaderData* loader_data = k->class_loader_data();
Handle class_loader_h(THREAD, loader_data->class_loader());
// for bootstrap and other parallel classloaders don't acquire lock,
// use placeholder token
// If a parallelCapable class loader calls define_instance_class instead of
// find_or_define_instance_class to get here, we have a timing
// hole with systemDictionary updates and check_constraints
if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
compute_loader_lock_object(class_loader_h, THREAD)),
"define called without lock");
}
// Check class-loading constraints. Throw exception if violation is detected.
// Grabs and releases SystemDictionary_lock
// The check_constraints/find_class call and update_dictionary sequence
// must be "atomic" for a specific class/classloader pair so we never
// define two different instanceKlasses for that class/classloader pair.
// Existing classloaders will call define_instance_class with the
// classloader lock held
// Parallel classloaders will call find_or_define_instance_class
// which will require a token to perform the define class
Symbol* name_h = k->name();
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(name_h);
check_constraints(d_hash, k, class_loader_h, true, CHECK);
// Register class just loaded with class loader (placed in 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_h);
args.push_oop(Handle(THREAD, k->java_mirror()));
JavaCalls::call(&result, m, &args, CHECK);
}
// Add the new class. We need recompile lock during update of CHA.
{
unsigned int p_hash = placeholders()->compute_hash(name_h);
int p_index = placeholders()->hash_to_index(p_hash);
MutexLocker mu_r(THREAD, Compile_lock);
// Add to class hierarchy, initialize vtables, and do possible
// deoptimizations.
add_to_hierarchy(k, CHECK); // No exception, but can block
// Add to systemDictionary - so other classes can see it.
// Grabs and releases SystemDictionary_lock
update_dictionary(d_hash, p_index, p_hash,
k, class_loader_h, THREAD);
}
k->eager_initialize(THREAD);
// notify jvmti
if (JvmtiExport::should_post_class_load()) {
assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
JvmtiExport::post_class_load((JavaThread *) THREAD, k);
}
post_class_define_event(k, loader_data);
}
// Support parallel classloading
// All parallel class loaders, including bootstrap classloader
// lock a placeholder entry for this class/class_loader pair
// to allow parallel defines of different classes for this class loader
// With AllowParallelDefine flag==true, in case they do not synchronize around
// FindLoadedClass/DefineClass, calls, we check for parallel
// loading for them, wait if a defineClass is in progress
// and return the initial requestor's results
// This flag does not apply to the bootstrap classloader.
// With AllowParallelDefine flag==false, call through to define_instance_class
// which will throw LinkageError: duplicate class definition.
// False is the requested default.
// For better performance, the class loaders should synchronize
// findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
// potentially waste time reading and parsing the bytestream.
// Note: VM callers should ensure consistency of k/class_name,class_loader
// Be careful when modifying this code: once you have run
// placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
// you need to find_and_remove it before returning.
// So be careful to not exit with a CHECK_ macro betweeen these calls.
InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
InstanceKlass* k, TRAPS) {
Symbol* name_h = k->name(); // passed in class_name may be null
ClassLoaderData* loader_data = class_loader_data(class_loader);
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(name_h);
// Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
unsigned int p_hash = placeholders()->compute_hash(name_h);
int p_index = placeholders()->hash_to_index(p_hash);
PlaceholderEntry* probe;
{
MutexLocker mu(THREAD, SystemDictionary_lock);
// First check if class already defined
if (is_parallelDefine(class_loader)) {
InstanceKlass* check = find_class(d_hash, name_h, dictionary);
if (check != NULL) {
return check;
}
}
// Acquire define token for this class/classloader
probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
// Wait if another thread defining in parallel
// All threads wait - even those that will throw duplicate class: otherwise
// caller is surprised by LinkageError: duplicate, but findLoadedClass fails
// if other thread has not finished updating dictionary
while (probe->definer() != NULL) {
SystemDictionary_lock->wait();
}
// Only special cases allow parallel defines and can use other thread's results
// Other cases fall through, and may run into duplicate defines
// caught by finding an entry in the SystemDictionary
if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
SystemDictionary_lock->notify_all();
#ifdef ASSERT
InstanceKlass* check = find_class(d_hash, name_h, dictionary);
assert(check != NULL, "definer missed recording success");
#endif
return probe->instance_klass();
} else {
// This thread will define the class (even if earlier thread tried and had an error)
probe->set_definer(THREAD);
}
}
define_instance_class(k, THREAD);
Handle linkage_exception = Handle(); // null handle
// definer must notify any waiting threads
{
MutexLocker mu(THREAD, SystemDictionary_lock);
PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
if (probe != NULL) {
if (HAS_PENDING_EXCEPTION) {
linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
CLEAR_PENDING_EXCEPTION;
} else {
probe->set_instance_klass(k);
}
probe->set_definer(NULL);
placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
SystemDictionary_lock->notify_all();
}
}
// Can't throw exception while holding lock due to rank ordering
if (linkage_exception() != NULL) {
THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
}
return k;
}
Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
// If class_loader is NULL we synchronize on _system_loader_lock_obj
if (class_loader.is_null()) {
return Handle(THREAD, _system_loader_lock_obj);
} else {
return class_loader;
}
}
// This method is added to check how often we have to wait to grab loader
// lock. The results are being recorded in the performance counters defined in
// ClassLoader::_sync_systemLoaderLockContentionRate and
// ClassLoader::_sync_nonSystemLoaderLockConteionRate.
void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
if (!UsePerfData) {
return;
}
assert(!loader_lock.is_null(), "NULL lock object");
if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
== ObjectSynchronizer::owner_other) {
// contention will likely happen, so increment the corresponding
// contention counter.
if (loader_lock() == _system_loader_lock_obj) {
ClassLoader::sync_systemLoaderLockContentionRate()->inc();
} else {
ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
}
}
}
// ----------------------------------------------------------------------------
// Lookup
InstanceKlass* SystemDictionary::find_class(unsigned int hash,
Symbol* class_name,
Dictionary* dictionary) {
assert_locked_or_safepoint(SystemDictionary_lock);
int index = dictionary->hash_to_index(hash);
return dictionary->find_class(index, hash, class_name);
}
// Basic find on classes in the midst of being loaded
Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
ClassLoaderData* loader_data) {
assert_locked_or_safepoint(SystemDictionary_lock);
unsigned int p_hash = placeholders()->compute_hash(class_name);
int p_index = placeholders()->hash_to_index(p_hash);
return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
}
// Used for assertions and verification only
// Precalculating the hash and index is an optimization because there are many lookups
// before adding the class.
InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
assert_locked_or_safepoint(SystemDictionary_lock);
#ifndef ASSERT
guarantee(VerifyBeforeGC ||
VerifyDuringGC ||
VerifyBeforeExit ||
VerifyDuringStartup ||
VerifyAfterGC, "too expensive");
#endif
Dictionary* dictionary = loader_data->dictionary();
unsigned int d_hash = dictionary->compute_hash(class_name);
return find_class(d_hash, class_name, dictionary);
}
// ----------------------------------------------------------------------------
// Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
// is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
// before a new class is used.
void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
assert(k != NULL, "just checking");
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(THREAD); // handle all "implements" declarations
// Now flush all code that depended on old class hierarchy.
// Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
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();
// Oops referenced by the protection domain cache table may get unreachable independently
// of the class loader (eg. cached protection domain oops). So we need to
// explicitly unlink them here.
// All protection domain oops are linked to the caller class, so if nothing
// unloads, this is not needed.
_pd_cache_table->trigger_cleanup();
}
return unloading_occurred;
}
void SystemDictionary::oops_do(OopClosure* f, bool include_handles) {
f->do_oop(&_java_system_loader);
f->do_oop(&_java_platform_loader);
f->do_oop(&_system_loader_lock_obj);
CDS_ONLY(SystemDictionaryShared::oops_do(f);)
// Visit extra methods
invoke_method_table()->oops_do(f);
if (include_handles) {
OopStorageSet::vm_global()->oops_do(f);
}
}
// CDS: scan and relocate all classes referenced by _well_known_klasses[].
void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
it->push(well_known_klass_addr((WKID)id));
}
}
void SystemDictionary::methods_do(void f(Method*)) {
// Walk methods in loaded classes
MutexLocker ml(ClassLoaderDataGraph_lock);
ClassLoaderDataGraph::methods_do(f);
// Walk method handle intrinsics
invoke_method_table()->methods_do(f);
}
// ----------------------------------------------------------------------------
// Initialization
void SystemDictionary::initialize(TRAPS) {
// Allocate arrays
_placeholders = new PlaceholderTable(_placeholder_table_size);
_loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
_resolution_errors = new ResolutionErrorTable(_resolution_error_size);
_invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
_pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
// Allocate private object used as system class loader lock
_system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
// Initialize basic classes
resolve_well_known_classes(CHECK);
}
// Compact table of directions on the initialization of klasses:
static const short wk_init_info[] = {
#define WK_KLASS_INIT_INFO(name, symbol) \
((short)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol)),
WK_KLASSES_DO(WK_KLASS_INIT_INFO)
#undef WK_KLASS_INIT_INFO
0
};
#ifdef ASSERT
bool SystemDictionary::is_well_known_klass(Symbol* class_name) {
int sid;
for (int i = 0; (sid = wk_init_info[i]) != 0; i++) {
Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
if (class_name == symbol) {
return true;
}
}
return false;
}
#endif
bool SystemDictionary::resolve_wk_klass(WKID id, TRAPS) {
assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
int sid = wk_init_info[id - FIRST_WKID];
Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
InstanceKlass** klassp = &_well_known_klasses[id];
#if INCLUDE_CDS
if (UseSharedSpaces && !JvmtiExport::should_post_class_prepare()) {
InstanceKlass* k = *klassp;
assert(k->is_shared_boot_class(), "must be");
ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data();
quick_resolve(k, loader_data, Handle(), CHECK_false);
return true;
}
#endif // INCLUDE_CDS
if (!is_wk_klass_loaded(*klassp)) {
Klass* k = resolve_or_fail(symbol, true, CHECK_false);
(*klassp) = InstanceKlass::cast(k);
}
return ((*klassp) != NULL);
}
void SystemDictionary::resolve_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
assert((int)start_id <= (int)limit_id, "IDs are out of order!");
for (int id = (int)start_id; id < (int)limit_id; id++) {
assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
resolve_wk_klass((WKID)id, CHECK);
}
// move the starting value forward to the limit:
start_id = limit_id;
}
void SystemDictionary::resolve_well_known_classes(TRAPS) {
assert(!Object_klass_loaded(), "well-known classes should only be initialized once");
// Create the ModuleEntry for java.base. This call needs to be done here,
// after vmSymbols::initialize() is called but before any classes are pre-loaded.
ClassLoader::classLoader_init2(CHECK);
// Preload commonly used klasses
WKID scan = FIRST_WKID;
// first do Object, then String, Class
#if INCLUDE_CDS
if (UseSharedSpaces) {
resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
// It's unsafe to access the archived heap regions before they
// are fixed up, so we must do the fixup as early as possible
// before the archived java objects are accessed by functions
// such as java_lang_Class::restore_archived_mirror and
// ConstantPool::restore_unshareable_info (restores the archived
// resolved_references array object).
//
// HeapShared::fixup_mapped_heap_regions() fills the empty
// spaces in the archived heap regions and may use
// SystemDictionary::Object_klass(), so we can do this only after
// Object_klass is resolved. See the above resolve_wk_klasses_through()
// call. No mirror objects are accessed/restored in the above call.
// Mirrors are restored after java.lang.Class is loaded.
HeapShared::fixup_mapped_heap_regions();
// Initialize the constant pool for the Object_class
assert(Object_klass()->is_shared(), "must be");
Object_klass()->constants()->restore_unshareable_info(CHECK);
resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
} else
#endif
{
resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
}
assert(WK_KLASS(Object_klass) != NULL, "well-known classes should now be initialized");
java_lang_Object::register_natives(CHECK);
// Calculate offsets for String and Class classes since they are loaded and
// can be used after this point.
java_lang_String::compute_offsets();
java_lang_Class::compute_offsets();
// Fixup mirrors for classes loaded before java.lang.Class.
Universe::initialize_basic_type_mirrors(CHECK);
Universe::fixup_mirrors(CHECK);
// do a bunch more:
resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
// Preload ref klasses and set reference types
WK_KLASS(Reference_klass)->set_reference_type(REF_OTHER);
InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
WK_KLASS(SoftReference_klass)->set_reference_type(REF_SOFT);
WK_KLASS(WeakReference_klass)->set_reference_type(REF_WEAK);
WK_KLASS(FinalReference_klass)->set_reference_type(REF_FINAL);
WK_KLASS(PhantomReference_klass)->set_reference_type(REF_PHANTOM);
// JSR 292 classes
WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
resolve_wk_klasses_until(jsr292_group_start, scan, CHECK);
resolve_wk_klasses_through(jsr292_group_end, scan, CHECK);
WKID last = WKID_LIMIT;
resolve_wk_klasses_until(last, scan, CHECK);
_box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
_box_klasses[T_CHAR] = WK_KLASS(Character_klass);
_box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
_box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
_box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
_box_klasses[T_SHORT] = WK_KLASS(Short_klass);
_box_klasses[T_INT] = WK_KLASS(Integer_klass);
_box_klasses[T_LONG] = WK_KLASS(Long_klass);
//_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
//_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
#ifdef ASSERT
if (UseSharedSpaces) {
JVMTI_ONLY(assert(JvmtiExport::is_early_phase(),
"All well known classes must be resolved in JVMTI early phase"));
for (int i = FIRST_WKID; i < last; i++) {
InstanceKlass* k = _well_known_klasses[i];
assert(k->is_shared(), "must not be replaced by JVMTI class file load hook");
}
}
#endif
}
// Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
// If so, returns the basic type it holds. If not, returns T_OBJECT.
BasicType SystemDictionary::box_klass_type(Klass* k) {
assert(k != NULL, "");
for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
if (_box_klasses[i] == k)
return (BasicType)i;
}
return T_OBJECT;
}
// Constraints on class loaders. The details of the algorithm can be
// found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
// Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
// that the dictionary needs to maintain a set of contraints that
// must be satisfied by all classes in the dictionary.
// if defining is true, then LinkageError if already in dictionary
// if initiating loader, then ok if InstanceKlass matches existing entry
void SystemDictionary::check_constraints(unsigned int d_hash,
InstanceKlass* k,
Handle class_loader,
bool defining,
TRAPS) {
ResourceMark rm(THREAD);
stringStream ss;
bool throwException = false;
{
Symbol *name = k->name();
ClassLoaderData *loader_data = class_loader_data(class_loader);
MutexLocker mu(THREAD, SystemDictionary_lock);
InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
if (check != NULL) {
// If different InstanceKlass - duplicate class definition,
// else - ok, class loaded by a different thread in parallel.
// We should only have found it if it was done loading and ok to use.
// The dictionary only holds instance classes, placeholders
// also hold array classes.
assert(check->is_instance_klass(), "noninstance in systemdictionary");
if ((defining == true) || (k != check)) {
throwException = true;
ss.print("loader %s", loader_data->loader_name_and_id());
ss.print(" attempted duplicate %s definition for %s. (%s)",
k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
} else {
return;
}
}
#ifdef ASSERT
Symbol* ph_check = find_placeholder(name, loader_data);
assert(ph_check == NULL || ph_check == name, "invalid symbol");
#endif
if (throwException == false) {
if (constraints()->check_or_update(k, class_loader, name) == false) {
throwException = true;
ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
ss.print(" wants to load %s %s.",
k->external_kind(), k->external_name());
Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
if (existing_klass != NULL && existing_klass->class_loader() != class_loader()) {
ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
existing_klass->external_kind(),
existing_klass->class_loader_data()->loader_name_and_id(),
existing_klass->class_in_module_of_loader(false, true));
} else {
ss.print(" (%s)", k->class_in_module_of_loader(false, true));
}
}
}
}
// Throw error now if needed (cannot throw while holding
// SystemDictionary_lock because of rank ordering)
if (throwException == true) {
THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
}
}
// Update class loader data dictionary - done after check_constraint and add_to_hierachy
// have been called.
void SystemDictionary::update_dictionary(unsigned int d_hash,
int p_index, unsigned int p_hash,
InstanceKlass* k,
Handle class_loader,
TRAPS) {
// Compile_lock prevents systemDictionary updates during compilations
assert_locked_or_safepoint(Compile_lock);
Symbol* name = k->name();
ClassLoaderData *loader_data = class_loader_data(class_loader);
{
MutexLocker mu1(THREAD, SystemDictionary_lock);
// Make a new dictionary entry.
Dictionary* dictionary = loader_data->dictionary();
InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
if (sd_check == NULL) {
dictionary->add_klass(d_hash, name, k);
}
#ifdef ASSERT
sd_check = find_class(d_hash, name, dictionary);
assert (sd_check != NULL, "should have entry in dictionary");
// Note: there may be a placeholder entry: for circularity testing
// or for parallel defines
#endif
SystemDictionary_lock->notify_all();
}
}
// Try to find a class name using the loader constraints. The
// loader constraints might know about a class that isn't fully loaded
// yet and these will be ignored.
Klass* SystemDictionary::find_constrained_instance_or_array_klass(
Symbol* class_name, Handle class_loader, TRAPS) {
// First see if it has been loaded directly.
// Force the protection domain to be null. (This removes protection checks.)
Handle no_protection_domain;
Klass* klass = find_instance_or_array_klass(class_name, class_loader,
no_protection_domain, CHECK_NULL);
if (klass != NULL)
return klass;
// Now look to see if it has been loaded elsewhere, and is subject to
// a loader constraint that would require this loader to return the
// klass that is already loaded.
if (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(THREAD, 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(THREAD, 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,
Thread* THREAD) {
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 d_hash1 = dictionary1->compute_hash(constraint_name);
Dictionary* dictionary2 = loader_data2->dictionary();
unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
{
MutexLocker mu_s(THREAD, SystemDictionary_lock);
InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
bool result = constraints()->add_entry(constraint_name, klass1, class_loader1,
klass2, class_loader2);
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, THREAD);
}
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) {
unsigned int hash = resolution_errors()->compute_hash(pool, which);
int index = resolution_errors()->hash_to_index(hash);
{
MutexLocker ml(Thread::current(), SystemDictionary_lock);
resolution_errors()->add_entry(index, hash, pool, which, error, message);
}
}
// Delete a resolution error for RedefineClasses for a constant pool is going away
void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
resolution_errors()->delete_entry(pool);
}
// Lookup resolution error table. Returns error if found, otherwise NULL.
Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
Symbol** message) {
unsigned int hash = resolution_errors()->compute_hash(pool, which);
int index = resolution_errors()->hash_to_index(hash);
{
MutexLocker ml(Thread::current(), SystemDictionary_lock);
ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
if (entry != NULL) {
*message = entry->message();
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, TRAPS) {
// 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, THREAD)) {
return sig;
}
}
}
return NULL;
}
Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
Symbol* signature,
TRAPS) {
methodHandle empty;
assert(MethodHandles::is_signature_polymorphic(iid) &&
MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
iid != vmIntrinsics::_invokeGeneric,
"must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
int index = invoke_method_table()->hash_to_index(hash);
SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
methodHandle m;
if (spe == NULL || spe->method() == NULL) {
spe = NULL;
// Must create lots of stuff here, but outside of the SystemDictionary lock.
m = Method::make_method_handle_intrinsic(iid, signature, CHECK_NULL);
if (!Arguments::is_interpreter_only()) {
// Generate a compiled form of the MH intrinsic.
AdapterHandlerLibrary::create_native_wrapper(m);
// Check if have the compiled code.
if (!m->has_compiled_code()) {
THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
"Out of space in CodeCache for method handle intrinsic");
}
}
// Now grab the lock. We might have to throw away the new method,
// if a racing thread has managed to install one at the same time.
{
MutexLocker ml(THREAD, SystemDictionary_lock);
spe = invoke_method_table()->find_entry(index, hash, signature, iid);
if (spe == NULL)
spe = invoke_method_table()->add_entry(index, hash, signature, iid);
if (spe->method() == NULL)
spe->set_method(m());
}
}
assert(spe != NULL && spe->method() != NULL, "");
assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
"MH intrinsic invariant");
return spe->method();
}
// Helper for unpacking the return value from linkMethod and linkCallSite.
static Method* unpack_method_and_appendix(Handle mname,
Klass* accessing_klass,
objArrayHandle appendix_box,
Handle* appendix_result,
TRAPS) {
if (mname.not_null()) {
Method* m = java_lang_invoke_MemberName::vmtarget(mname());
if (m != NULL) {
oop appendix = appendix_box->obj_at(0);
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(SystemDictionary::Object_klass(), 1, CHECK_NULL);
assert(appendix_box->obj_at(0) == NULL, "");
// This should not happen. JDK code should take care of that.
if (accessing_klass == NULL || method_type.is_null()) {
THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
}
// call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
JavaCallArguments args;
args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
args.push_int(ref_kind);
args.push_oop(Handle(THREAD, klass->java_mirror()));
args.push_oop(name_str);
args.push_oop(method_type);
args.push_oop(appendix_box);
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
SystemDictionary::MethodHandleNatives_klass(),
vmSymbols::linkMethod_name(),
vmSymbols::linkMethod_signature(),
&args, CHECK_NULL);
Handle mname(THREAD, (oop) result.get_jobject());
return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
}
// Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
// We must ensure that all class loaders everywhere will reach this class, for any client.
// This is a safe bet for public classes in java.lang, such as Object and String.
// We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
// Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
static bool is_always_visible_class(oop mirror) {
Klass* klass = java_lang_Class::as_Klass(mirror);
if (klass->is_objArray_klass()) {
klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
}
if (klass->is_typeArray_klass()) {
return true; // primitive array
}
assert(klass->is_instance_klass(), "%s", klass->external_name());
return klass->is_public() &&
(InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang
InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke
}
// 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;
vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
int index = invoke_method_table()->hash_to_index(hash);
SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
if (spe != NULL && spe->method_type() != NULL) {
assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
return Handle(THREAD, spe->method_type());
} else if (!THREAD->can_call_java()) {
warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
return Handle(); // do not attempt from within compiler, unless it was cached
}
Handle class_loader, protection_domain;
if (accessing_klass != NULL) {
class_loader = Handle(THREAD, accessing_klass->class_loader());
protection_domain = Handle(THREAD, accessing_klass->protection_domain());
}
bool can_be_cached = true;
int npts = ArgumentCount(signature).size();
objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
int arg = 0;
Handle rt; // the return type from the signature
ResourceMark rm(THREAD);
for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
oop mirror = NULL;
if (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,
SystemDictionary::MethodHandleNatives_klass(),
vmSymbols::findMethodHandleType_name(),
vmSymbols::findMethodHandleType_signature(),
&args, CHECK_(empty));
Handle method_type(THREAD, (oop) result.get_jobject());
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 = 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, /*speculative_resolve*/false, 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,
SystemDictionary::MethodHandleNatives_klass(),
vmSymbols::linkMethodHandleConstant_name(),
vmSymbols::linkMethodHandleConstant_signature(),
&args, CHECK_(empty));
return Handle(THREAD, (oop) result.get_jobject());
}
// 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(SystemDictionary::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,
SystemDictionary::MethodHandleNatives_klass(),
is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
&args, CHECK);
Handle value(THREAD, (oop) result.get_jobject());
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");
}
// Protection domain cache table handling
ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
return _pd_cache_table->get(protection_domain);
}
// ----------------------------------------------------------------------------
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);
}
int SystemDictionaryDCmd::num_arguments() {
ResourceMark rm;
SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
if (dcmd != NULL) {
DCmdMark mark(dcmd);
return dcmd->_dcmdparser.num_arguments();
} else {
return 0;
}
}
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