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android / toolchain / jdk / jdk21 / HEAD / . / src / hotspot / share / cds / heapShared.cpp
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/*
* Copyright (c) 2018, 2023, 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 "cds/archiveBuilder.hpp"
#include "cds/archiveHeapLoader.hpp"
#include "cds/archiveHeapWriter.hpp"
#include "cds/archiveUtils.hpp"
#include "cds/cdsHeapVerifier.hpp"
#include "cds/heapShared.hpp"
#include "cds/metaspaceShared.hpp"
#include "classfile/classLoaderData.hpp"
#include "classfile/javaClasses.inline.hpp"
#include "classfile/modules.hpp"
#include "classfile/stringTable.hpp"
#include "classfile/symbolTable.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/systemDictionaryShared.hpp"
#include "classfile/vmClasses.hpp"
#include "classfile/vmSymbols.hpp"
#include "gc/shared/collectedHeap.hpp"
#include "gc/shared/gcLocker.hpp"
#include "gc/shared/gcVMOperations.hpp"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/iterator.inline.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "oops/compressedOops.inline.hpp"
#include "oops/fieldStreams.inline.hpp"
#include "oops/objArrayOop.inline.hpp"
#include "oops/oop.inline.hpp"
#include "oops/typeArrayOop.inline.hpp"
#include "prims/jvmtiExport.hpp"
#include "runtime/fieldDescriptor.inline.hpp"
#include "runtime/init.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/safepointVerifiers.hpp"
#include "utilities/bitMap.inline.hpp"
#include "utilities/copy.hpp"
#if INCLUDE_G1GC
#include "gc/g1/g1CollectedHeap.hpp"
#endif
#if INCLUDE_CDS_JAVA_HEAP
struct ArchivableStaticFieldInfo {
const char* klass_name;
const char* field_name;
InstanceKlass* klass;
int offset;
BasicType type;
ArchivableStaticFieldInfo(const char* k, const char* f)
: klass_name(k), field_name(f), klass(nullptr), offset(0), type(T_ILLEGAL) {}
bool valid() {
return klass_name != nullptr;
}
};
bool HeapShared::_disable_writing = false;
DumpedInternedStrings *HeapShared::_dumped_interned_strings = nullptr;
size_t HeapShared::_alloc_count[HeapShared::ALLOC_STAT_SLOTS];
size_t HeapShared::_alloc_size[HeapShared::ALLOC_STAT_SLOTS];
size_t HeapShared::_total_obj_count;
size_t HeapShared::_total_obj_size;
#ifndef PRODUCT
#define ARCHIVE_TEST_FIELD_NAME "archivedObjects"
static Array<char>* _archived_ArchiveHeapTestClass = nullptr;
static const char* _test_class_name = nullptr;
static const Klass* _test_class = nullptr;
static const ArchivedKlassSubGraphInfoRecord* _test_class_record = nullptr;
#endif
//
// If you add new entries to the following tables, you should know what you're doing!
//
static ArchivableStaticFieldInfo archive_subgraph_entry_fields[] = {
{"java/lang/Integer$IntegerCache", "archivedCache"},
{"java/lang/Long$LongCache", "archivedCache"},
{"java/lang/Byte$ByteCache", "archivedCache"},
{"java/lang/Short$ShortCache", "archivedCache"},
{"java/lang/Character$CharacterCache", "archivedCache"},
{"java/util/jar/Attributes$Name", "KNOWN_NAMES"},
{"sun/util/locale/BaseLocale", "constantBaseLocales"},
{"jdk/internal/module/ArchivedModuleGraph", "archivedModuleGraph"},
{"java/util/ImmutableCollections", "archivedObjects"},
{"java/lang/ModuleLayer", "EMPTY_LAYER"},
{"java/lang/module/Configuration", "EMPTY_CONFIGURATION"},
{"jdk/internal/math/FDBigInteger", "archivedCaches"},
#ifndef PRODUCT
{nullptr, nullptr}, // Extra slot for -XX:ArchiveHeapTestClass
#endif
{nullptr, nullptr},
};
// full module graph
static ArchivableStaticFieldInfo fmg_archive_subgraph_entry_fields[] = {
{"jdk/internal/loader/ArchivedClassLoaders", "archivedClassLoaders"},
{"jdk/internal/module/ArchivedBootLayer", "archivedBootLayer"},
{"java/lang/Module$ArchivedData", "archivedData"},
{nullptr, nullptr},
};
KlassSubGraphInfo* HeapShared::_default_subgraph_info;
GrowableArrayCHeap<oop, mtClassShared>* HeapShared::_pending_roots = nullptr;
OopHandle HeapShared::_roots;
OopHandle HeapShared::_scratch_basic_type_mirrors[T_VOID+1];
KlassToOopHandleTable* HeapShared::_scratch_java_mirror_table = nullptr;
static bool is_subgraph_root_class_of(ArchivableStaticFieldInfo fields[], InstanceKlass* ik) {
for (int i = 0; fields[i].valid(); i++) {
if (fields[i].klass == ik) {
return true;
}
}
return false;
}
bool HeapShared::is_subgraph_root_class(InstanceKlass* ik) {
return is_subgraph_root_class_of(archive_subgraph_entry_fields, ik) ||
is_subgraph_root_class_of(fmg_archive_subgraph_entry_fields, ik);
}
unsigned HeapShared::oop_hash(oop const& p) {
// Do not call p->identity_hash() as that will update the
// object header.
return primitive_hash(cast_from_oop<intptr_t>(p));
}
static void reset_states(oop obj, TRAPS) {
Handle h_obj(THREAD, obj);
InstanceKlass* klass = InstanceKlass::cast(obj->klass());
TempNewSymbol method_name = SymbolTable::new_symbol("resetArchivedStates");
Symbol* method_sig = vmSymbols::void_method_signature();
while (klass != nullptr) {
Method* method = klass->find_method(method_name, method_sig);
if (method != nullptr) {
assert(method->is_private(), "must be");
if (log_is_enabled(Debug, cds)) {
ResourceMark rm(THREAD);
log_debug(cds)(" calling %s", method->name_and_sig_as_C_string());
}
JavaValue result(T_VOID);
JavaCalls::call_special(&result, h_obj, klass,
method_name, method_sig, CHECK);
}
klass = klass->java_super();
}
}
void HeapShared::reset_archived_object_states(TRAPS) {
assert(DumpSharedSpaces, "dump-time only");
log_debug(cds)("Resetting platform loader");
reset_states(SystemDictionary::java_platform_loader(), CHECK);
log_debug(cds)("Resetting system loader");
reset_states(SystemDictionary::java_system_loader(), CHECK);
// Clean up jdk.internal.loader.ClassLoaders::bootLoader(), which is not
// directly used for class loading, but rather is used by the core library
// to keep track of resources, etc, loaded by the null class loader.
//
// Note, this object is non-null, and is not the same as
// ClassLoaderData::the_null_class_loader_data()->class_loader(),
// which is null.
log_debug(cds)("Resetting boot loader");
JavaValue result(T_OBJECT);
JavaCalls::call_static(&result,
vmClasses::jdk_internal_loader_ClassLoaders_klass(),
vmSymbols::bootLoader_name(),
vmSymbols::void_BuiltinClassLoader_signature(),
CHECK);
Handle boot_loader(THREAD, result.get_oop());
reset_states(boot_loader(), CHECK);
}
HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = nullptr;
bool HeapShared::has_been_archived(oop obj) {
assert(DumpSharedSpaces, "dump-time only");
return archived_object_cache()->get(obj) != nullptr;
}
int HeapShared::append_root(oop obj) {
assert(DumpSharedSpaces, "dump-time only");
// No GC should happen since we aren't scanning _pending_roots.
assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
if (_pending_roots == nullptr) {
_pending_roots = new GrowableArrayCHeap<oop, mtClassShared>(500);
}
return _pending_roots->append(obj);
}
objArrayOop HeapShared::roots() {
if (DumpSharedSpaces) {
assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");
if (!HeapShared::can_write()) {
return nullptr;
}
} else {
assert(UseSharedSpaces, "must be");
}
objArrayOop roots = (objArrayOop)_roots.resolve();
assert(roots != nullptr, "should have been initialized");
return roots;
}
// Returns an objArray that contains all the roots of the archived objects
oop HeapShared::get_root(int index, bool clear) {
assert(index >= 0, "sanity");
assert(!DumpSharedSpaces && UseSharedSpaces, "runtime only");
assert(!_roots.is_empty(), "must have loaded shared heap");
oop result = roots()->obj_at(index);
if (clear) {
clear_root(index);
}
return result;
}
void HeapShared::clear_root(int index) {
assert(index >= 0, "sanity");
assert(UseSharedSpaces, "must be");
if (ArchiveHeapLoader::is_in_use()) {
if (log_is_enabled(Debug, cds, heap)) {
oop old = roots()->obj_at(index);
log_debug(cds, heap)("Clearing root %d: was " PTR_FORMAT, index, p2i(old));
}
roots()->obj_at_put(index, nullptr);
}
}
bool HeapShared::archive_object(oop obj) {
assert(DumpSharedSpaces, "dump-time only");
assert(!obj->is_stackChunk(), "do not archive stack chunks");
if (has_been_archived(obj)) {
return true;
}
if (ArchiveHeapWriter::is_too_large_to_archive(obj->size())) {
log_debug(cds, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: " SIZE_FORMAT,
p2i(obj), obj->size());
return false;
} else {
count_allocation(obj->size());
ArchiveHeapWriter::add_source_obj(obj);
// The archived objects are discovered in a predictable order. Compute
// their identity_hash() as soon as we see them. This ensures that the
// the identity_hash in the object header will have a predictable value,
// making the archive reproducible.
obj->identity_hash();
CachedOopInfo info = make_cached_oop_info();
archived_object_cache()->put(obj, info);
mark_native_pointers(obj);
if (log_is_enabled(Debug, cds, heap)) {
ResourceMark rm;
log_debug(cds, heap)("Archived heap object " PTR_FORMAT " : %s",
p2i(obj), obj->klass()->external_name());
}
if (java_lang_Module::is_instance(obj)) {
if (Modules::check_module_oop(obj)) {
Modules::update_oops_in_archived_module(obj, append_root(obj));
}
java_lang_Module::set_module_entry(obj, nullptr);
} else if (java_lang_ClassLoader::is_instance(obj)) {
// class_data will be restored explicitly at run time.
guarantee(obj == SystemDictionary::java_platform_loader() ||
obj == SystemDictionary::java_system_loader() ||
java_lang_ClassLoader::loader_data(obj) == nullptr, "must be");
java_lang_ClassLoader::release_set_loader_data(obj, nullptr);
}
return true;
}
}
class KlassToOopHandleTable: public ResourceHashtable<Klass*, OopHandle,
36137, // prime number
AnyObj::C_HEAP,
mtClassShared> {
public:
oop get_oop(Klass* k) {
MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
OopHandle* handle = get(k);
if (handle != nullptr) {
return handle->resolve();
} else {
return nullptr;
}
}
void set_oop(Klass* k, oop o) {
MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
OopHandle handle(Universe::vm_global(), o);
bool is_new = put(k, handle);
assert(is_new, "cannot set twice");
}
void remove_oop(Klass* k) {
MutexLocker ml(ScratchObjects_lock, Mutex::_no_safepoint_check_flag);
OopHandle* handle = get(k);
if (handle != nullptr) {
handle->release(Universe::vm_global());
remove(k);
}
}
};
void HeapShared::init_scratch_objects(TRAPS) {
for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
BasicType bt = (BasicType)i;
if (!is_reference_type(bt)) {
oop m = java_lang_Class::create_basic_type_mirror(type2name(bt), bt, CHECK);
_scratch_basic_type_mirrors[i] = OopHandle(Universe::vm_global(), m);
}
}
_scratch_java_mirror_table = new (mtClass)KlassToOopHandleTable();
}
oop HeapShared::scratch_java_mirror(BasicType t) {
assert((uint)t < T_VOID+1, "range check");
assert(!is_reference_type(t), "sanity");
return _scratch_basic_type_mirrors[t].resolve();
}
oop HeapShared::scratch_java_mirror(Klass* k) {
return _scratch_java_mirror_table->get_oop(k);
}
void HeapShared::set_scratch_java_mirror(Klass* k, oop mirror) {
_scratch_java_mirror_table->set_oop(k, mirror);
}
void HeapShared::remove_scratch_objects(Klass* k) {
_scratch_java_mirror_table->remove_oop(k);
}
void HeapShared::archive_java_mirrors() {
for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
BasicType bt = (BasicType)i;
if (!is_reference_type(bt)) {
oop m = _scratch_basic_type_mirrors[i].resolve();
assert(m != nullptr, "sanity");
bool success = archive_reachable_objects_from(1, _default_subgraph_info, m);
assert(success, "sanity");
log_trace(cds, heap, mirror)(
"Archived %s mirror object from " PTR_FORMAT,
type2name(bt), p2i(m));
Universe::set_archived_basic_type_mirror_index(bt, append_root(m));
}
}
GrowableArray<Klass*>* klasses = ArchiveBuilder::current()->klasses();
assert(klasses != nullptr, "sanity");
for (int i = 0; i < klasses->length(); i++) {
Klass* orig_k = klasses->at(i);
oop m = scratch_java_mirror(orig_k);
if (m != nullptr) {
Klass* buffered_k = ArchiveBuilder::get_buffered_klass(orig_k);
bool success = archive_reachable_objects_from(1, _default_subgraph_info, m);
guarantee(success, "scratch mirrors must point to only archivable objects");
buffered_k->set_archived_java_mirror(append_root(m));
ResourceMark rm;
log_trace(cds, heap, mirror)(
"Archived %s mirror object from " PTR_FORMAT,
buffered_k->external_name(), p2i(m));
// archive the resolved_referenes array
if (buffered_k->is_instance_klass()) {
InstanceKlass* ik = InstanceKlass::cast(buffered_k);
oop rr = ik->constants()->prepare_resolved_references_for_archiving();
if (rr != nullptr && !ArchiveHeapWriter::is_too_large_to_archive(rr)) {
bool success = HeapShared::archive_reachable_objects_from(1, _default_subgraph_info, rr);
assert(success, "must be");
int root_index = append_root(rr);
ik->constants()->cache()->set_archived_references(root_index);
}
}
}
}
}
void HeapShared::archive_strings() {
oop shared_strings_array = StringTable::init_shared_table(_dumped_interned_strings);
bool success = archive_reachable_objects_from(1, _default_subgraph_info, shared_strings_array);
// We must succeed because:
// - _dumped_interned_strings do not contain any large strings.
// - StringTable::init_shared_table() doesn't create any large arrays.
assert(success, "shared strings array must not point to arrays or strings that are too large to archive");
StringTable::set_shared_strings_array_index(append_root(shared_strings_array));
}
void HeapShared::mark_native_pointers(oop orig_obj) {
if (java_lang_Class::is_instance(orig_obj)) {
ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::klass_offset());
ArchiveHeapWriter::mark_native_pointer(orig_obj, java_lang_Class::array_klass_offset());
}
}
// -- Handling of Enum objects
// Java Enum classes have synthetic <clinit> methods that look like this
// enum MyEnum {FOO, BAR}
// MyEnum::<clinint> {
// /*static final MyEnum*/ MyEnum::FOO = new MyEnum("FOO");
// /*static final MyEnum*/ MyEnum::BAR = new MyEnum("BAR");
// }
//
// If MyEnum::FOO object is referenced by any of the archived subgraphs, we must
// ensure the archived value equals (in object address) to the runtime value of
// MyEnum::FOO.
//
// However, since MyEnum::<clinint> is synthetically generated by javac, there's
// no way of programmatically handling this inside the Java code (as you would handle
// ModuleLayer::EMPTY_LAYER, for example).
//
// Instead, we archive all static field of such Enum classes. At runtime,
// HeapShared::initialize_enum_klass() will skip the <clinit> method and pull
// the static fields out of the archived heap.
void HeapShared::check_enum_obj(int level,
KlassSubGraphInfo* subgraph_info,
oop orig_obj) {
assert(level > 1, "must never be called at the first (outermost) level");
Klass* k = orig_obj->klass();
Klass* buffered_k = ArchiveBuilder::get_buffered_klass(k);
if (!k->is_instance_klass()) {
return;
}
InstanceKlass* ik = InstanceKlass::cast(k);
if (ik->java_super() == vmClasses::Enum_klass() && !ik->has_archived_enum_objs()) {
ResourceMark rm;
ik->set_has_archived_enum_objs();
buffered_k->set_has_archived_enum_objs();
oop mirror = ik->java_mirror();
for (JavaFieldStream fs(ik); !fs.done(); fs.next()) {
if (fs.access_flags().is_static()) {
fieldDescriptor& fd = fs.field_descriptor();
if (fd.field_type() != T_OBJECT && fd.field_type() != T_ARRAY) {
guarantee(false, "static field %s::%s must be T_OBJECT or T_ARRAY",
ik->external_name(), fd.name()->as_C_string());
}
oop oop_field = mirror->obj_field(fd.offset());
if (oop_field == nullptr) {
guarantee(false, "static field %s::%s must not be null",
ik->external_name(), fd.name()->as_C_string());
} else if (oop_field->klass() != ik && oop_field->klass() != ik->array_klass_or_null()) {
guarantee(false, "static field %s::%s is of the wrong type",
ik->external_name(), fd.name()->as_C_string());
}
bool success = archive_reachable_objects_from(level, subgraph_info, oop_field);
assert(success, "VM should have exited with unarchivable objects for _level > 1");
int root_index = append_root(oop_field);
log_info(cds, heap)("Archived enum obj @%d %s::%s (" INTPTR_FORMAT ")",
root_index, ik->external_name(), fd.name()->as_C_string(),
p2i((oopDesc*)oop_field));
SystemDictionaryShared::add_enum_klass_static_field(ik, root_index);
}
}
}
}
// See comments in HeapShared::check_enum_obj()
bool HeapShared::initialize_enum_klass(InstanceKlass* k, TRAPS) {
if (!ArchiveHeapLoader::is_in_use()) {
return false;
}
RunTimeClassInfo* info = RunTimeClassInfo::get_for(k);
assert(info != nullptr, "sanity");
if (log_is_enabled(Info, cds, heap)) {
ResourceMark rm;
log_info(cds, heap)("Initializing Enum class: %s", k->external_name());
}
oop mirror = k->java_mirror();
int i = 0;
for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
if (fs.access_flags().is_static()) {
int root_index = info->enum_klass_static_field_root_index_at(i++);
fieldDescriptor& fd = fs.field_descriptor();
assert(fd.field_type() == T_OBJECT || fd.field_type() == T_ARRAY, "must be");
mirror->obj_field_put(fd.offset(), get_root(root_index, /*clear=*/true));
}
}
return true;
}
void HeapShared::archive_objects(ArchiveHeapInfo *heap_info) {
{
NoSafepointVerifier nsv;
_default_subgraph_info = init_subgraph_info(vmClasses::Object_klass(), false);
// Cache for recording where the archived objects are copied to
create_archived_object_cache();
log_info(cds)("Heap range = [" PTR_FORMAT " - " PTR_FORMAT "]",
UseCompressedOops ? p2i(CompressedOops::begin()) :
p2i((address)G1CollectedHeap::heap()->reserved().start()),
UseCompressedOops ? p2i(CompressedOops::end()) :
p2i((address)G1CollectedHeap::heap()->reserved().end()));
copy_objects();
CDSHeapVerifier::verify();
check_default_subgraph_classes();
}
ArchiveHeapWriter::write(_pending_roots, heap_info);
}
void HeapShared::copy_interned_strings() {
init_seen_objects_table();
auto copier = [&] (oop s, bool value_ignored) {
assert(s != nullptr, "sanity");
assert(!ArchiveHeapWriter::is_string_too_large_to_archive(s), "large strings must have been filtered");
bool success = archive_reachable_objects_from(1, _default_subgraph_info, s);
assert(success, "must be");
// Prevent string deduplication from changing the value field to
// something not in the archive.
java_lang_String::set_deduplication_forbidden(s);
};
_dumped_interned_strings->iterate_all(copier);
delete_seen_objects_table();
}
void HeapShared::copy_special_objects() {
// Archive special objects that do not belong to any subgraphs
init_seen_objects_table();
archive_java_mirrors();
archive_strings();
delete_seen_objects_table();
}
void HeapShared::copy_objects() {
assert(HeapShared::can_write(), "must be");
copy_interned_strings();
copy_special_objects();
archive_object_subgraphs(archive_subgraph_entry_fields,
false /* is_full_module_graph */);
if (MetaspaceShared::use_full_module_graph()) {
archive_object_subgraphs(fmg_archive_subgraph_entry_fields,
true /* is_full_module_graph */);
Modules::verify_archived_modules();
}
}
//
// Subgraph archiving support
//
HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = nullptr;
HeapShared::RunTimeKlassSubGraphInfoTable HeapShared::_run_time_subgraph_info_table;
// Get the subgraph_info for Klass k. A new subgraph_info is created if
// there is no existing one for k. The subgraph_info records the "buffered"
// address of the class.
KlassSubGraphInfo* HeapShared::init_subgraph_info(Klass* k, bool is_full_module_graph) {
assert(DumpSharedSpaces, "dump time only");
bool created;
Klass* buffered_k = ArchiveBuilder::get_buffered_klass(k);
KlassSubGraphInfo* info =
_dump_time_subgraph_info_table->put_if_absent(k, KlassSubGraphInfo(buffered_k, is_full_module_graph),
&created);
assert(created, "must not initialize twice");
return info;
}
KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
assert(DumpSharedSpaces, "dump time only");
KlassSubGraphInfo* info = _dump_time_subgraph_info_table->get(k);
assert(info != nullptr, "must have been initialized");
return info;
}
// Add an entry field to the current KlassSubGraphInfo.
void KlassSubGraphInfo::add_subgraph_entry_field(int static_field_offset, oop v) {
assert(DumpSharedSpaces, "dump time only");
if (_subgraph_entry_fields == nullptr) {
_subgraph_entry_fields =
new (mtClass) GrowableArray<int>(10, mtClass);
}
_subgraph_entry_fields->append(static_field_offset);
_subgraph_entry_fields->append(HeapShared::append_root(v));
}
// Add the Klass* for an object in the current KlassSubGraphInfo's subgraphs.
// Only objects of boot classes can be included in sub-graph.
void KlassSubGraphInfo::add_subgraph_object_klass(Klass* orig_k) {
assert(DumpSharedSpaces, "dump time only");
Klass* buffered_k = ArchiveBuilder::get_buffered_klass(orig_k);
if (_subgraph_object_klasses == nullptr) {
_subgraph_object_klasses =
new (mtClass) GrowableArray<Klass*>(50, mtClass);
}
assert(ArchiveBuilder::current()->is_in_buffer_space(buffered_k), "must be a shared class");
if (_k == buffered_k) {
// Don't add the Klass containing the sub-graph to it's own klass
// initialization list.
return;
}
if (buffered_k->is_instance_klass()) {
assert(InstanceKlass::cast(buffered_k)->is_shared_boot_class(),
"must be boot class");
// vmClasses::xxx_klass() are not updated, need to check
// the original Klass*
if (orig_k == vmClasses::String_klass() ||
orig_k == vmClasses::Object_klass()) {
// Initialized early during VM initialization. No need to be added
// to the sub-graph object class list.
return;
}
check_allowed_klass(InstanceKlass::cast(orig_k));
} else if (buffered_k->is_objArray_klass()) {
Klass* abk = ObjArrayKlass::cast(buffered_k)->bottom_klass();
if (abk->is_instance_klass()) {
assert(InstanceKlass::cast(abk)->is_shared_boot_class(),
"must be boot class");
check_allowed_klass(InstanceKlass::cast(ObjArrayKlass::cast(orig_k)->bottom_klass()));
}
if (buffered_k == Universe::objectArrayKlassObj()) {
// Initialized early during Universe::genesis. No need to be added
// to the list.
return;
}
} else {
assert(buffered_k->is_typeArray_klass(), "must be");
// Primitive type arrays are created early during Universe::genesis.
return;
}
if (log_is_enabled(Debug, cds, heap)) {
if (!_subgraph_object_klasses->contains(buffered_k)) {
ResourceMark rm;
log_debug(cds, heap)("Adding klass %s", orig_k->external_name());
}
}
_subgraph_object_klasses->append_if_missing(buffered_k);
_has_non_early_klasses |= is_non_early_klass(orig_k);
}
void KlassSubGraphInfo::check_allowed_klass(InstanceKlass* ik) {
if (ik->module()->name() == vmSymbols::java_base()) {
assert(ik->package() != nullptr, "classes in java.base cannot be in unnamed package");
return;
}
#ifndef PRODUCT
if (!ik->module()->is_named() && ik->package() == nullptr) {
// This class is loaded by ArchiveHeapTestClass
return;
}
const char* extra_msg = ", or in an unnamed package of an unnamed module";
#else
const char* extra_msg = "";
#endif
ResourceMark rm;
log_error(cds, heap)("Class %s not allowed in archive heap. Must be in java.base%s",
ik->external_name(), extra_msg);
MetaspaceShared::unrecoverable_writing_error();
}
bool KlassSubGraphInfo::is_non_early_klass(Klass* k) {
if (k->is_objArray_klass()) {
k = ObjArrayKlass::cast(k)->bottom_klass();
}
if (k->is_instance_klass()) {
if (!SystemDictionaryShared::is_early_klass(InstanceKlass::cast(k))) {
ResourceMark rm;
log_info(cds, heap)("non-early: %s", k->external_name());
return true;
} else {
return false;
}
} else {
return false;
}
}
// Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
_k = info->klass();
_entry_field_records = nullptr;
_subgraph_object_klasses = nullptr;
_is_full_module_graph = info->is_full_module_graph();
if (_is_full_module_graph) {
// Consider all classes referenced by the full module graph as early -- we will be
// allocating objects of these classes during JVMTI early phase, so they cannot
// be processed by (non-early) JVMTI ClassFileLoadHook
_has_non_early_klasses = false;
} else {
_has_non_early_klasses = info->has_non_early_klasses();
}
if (_has_non_early_klasses) {
ResourceMark rm;
log_info(cds, heap)(
"Subgraph of klass %s has non-early klasses and cannot be used when JVMTI ClassFileLoadHook is enabled",
_k->external_name());
}
// populate the entry fields
GrowableArray<int>* entry_fields = info->subgraph_entry_fields();
if (entry_fields != nullptr) {
int num_entry_fields = entry_fields->length();
assert(num_entry_fields % 2 == 0, "sanity");
_entry_field_records =
ArchiveBuilder::new_ro_array<int>(num_entry_fields);
for (int i = 0 ; i < num_entry_fields; i++) {
_entry_field_records->at_put(i, entry_fields->at(i));
}
}
// the Klasses of the objects in the sub-graphs
GrowableArray<Klass*>* subgraph_object_klasses = info->subgraph_object_klasses();
if (subgraph_object_klasses != nullptr) {
int num_subgraphs_klasses = subgraph_object_klasses->length();
_subgraph_object_klasses =
ArchiveBuilder::new_ro_array<Klass*>(num_subgraphs_klasses);
for (int i = 0; i < num_subgraphs_klasses; i++) {
Klass* subgraph_k = subgraph_object_klasses->at(i);
if (log_is_enabled(Info, cds, heap)) {
ResourceMark rm;
log_info(cds, heap)(
"Archived object klass %s (%2d) => %s",
_k->external_name(), i, subgraph_k->external_name());
}
_subgraph_object_klasses->at_put(i, subgraph_k);
ArchivePtrMarker::mark_pointer(_subgraph_object_klasses->adr_at(i));
}
}
ArchivePtrMarker::mark_pointer(&_k);
ArchivePtrMarker::mark_pointer(&_entry_field_records);
ArchivePtrMarker::mark_pointer(&_subgraph_object_klasses);
}
struct CopyKlassSubGraphInfoToArchive : StackObj {
CompactHashtableWriter* _writer;
CopyKlassSubGraphInfoToArchive(CompactHashtableWriter* writer) : _writer(writer) {}
bool do_entry(Klass* klass, KlassSubGraphInfo& info) {
if (info.subgraph_object_klasses() != nullptr || info.subgraph_entry_fields() != nullptr) {
ArchivedKlassSubGraphInfoRecord* record =
(ArchivedKlassSubGraphInfoRecord*)ArchiveBuilder::ro_region_alloc(sizeof(ArchivedKlassSubGraphInfoRecord));
record->init(&info);
Klass* buffered_k = ArchiveBuilder::get_buffered_klass(klass);
unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary((address)buffered_k);
u4 delta = ArchiveBuilder::current()->any_to_offset_u4(record);
_writer->add(hash, delta);
}
return true; // keep on iterating
}
};
// Build the records of archived subgraph infos, which include:
// - Entry points to all subgraphs from the containing class mirror. The entry
// points are static fields in the mirror. For each entry point, the field
// offset, and value are recorded in the sub-graph
// info. The value is stored back to the corresponding field at runtime.
// - A list of klasses that need to be loaded/initialized before archived
// java object sub-graph can be accessed at runtime.
void HeapShared::write_subgraph_info_table() {
// Allocate the contents of the hashtable(s) inside the RO region of the CDS archive.
DumpTimeKlassSubGraphInfoTable* d_table = _dump_time_subgraph_info_table;
CompactHashtableStats stats;
_run_time_subgraph_info_table.reset();
CompactHashtableWriter writer(d_table->_count, &stats);
CopyKlassSubGraphInfoToArchive copy(&writer);
d_table->iterate(&copy);
writer.dump(&_run_time_subgraph_info_table, "subgraphs");
#ifndef PRODUCT
if (ArchiveHeapTestClass != nullptr) {
size_t len = strlen(ArchiveHeapTestClass) + 1;
Array<char>* array = ArchiveBuilder::new_ro_array<char>((int)len);
strncpy(array->adr_at(0), ArchiveHeapTestClass, len);
_archived_ArchiveHeapTestClass = array;
}
#endif
if (log_is_enabled(Info, cds, heap)) {
print_stats();
}
}
void HeapShared::serialize_root(SerializeClosure* soc) {
oop roots_oop = nullptr;
if (soc->reading()) {
soc->do_oop(&roots_oop); // read from archive
assert(oopDesc::is_oop_or_null(roots_oop), "is oop");
// Create an OopHandle only if we have actually mapped or loaded the roots
if (roots_oop != nullptr) {
assert(ArchiveHeapLoader::is_in_use(), "must be");
_roots = OopHandle(Universe::vm_global(), roots_oop);
}
} else {
// writing
if (HeapShared::can_write()) {
roots_oop = ArchiveHeapWriter::heap_roots_requested_address();
}
soc->do_oop(&roots_oop); // write to archive
}
}
void HeapShared::serialize_tables(SerializeClosure* soc) {
#ifndef PRODUCT
soc->do_ptr(&_archived_ArchiveHeapTestClass);
if (soc->reading() && _archived_ArchiveHeapTestClass != nullptr) {
_test_class_name = _archived_ArchiveHeapTestClass->adr_at(0);
setup_test_class(_test_class_name);
}
#endif
_run_time_subgraph_info_table.serialize_header(soc);
}
static void verify_the_heap(Klass* k, const char* which) {
if (VerifyArchivedFields > 0) {
ResourceMark rm;
log_info(cds, heap)("Verify heap %s initializing static field(s) in %s",
which, k->external_name());
VM_Verify verify_op;
VMThread::execute(&verify_op);
if (VerifyArchivedFields > 1 && is_init_completed()) {
// At this time, the oop->klass() of some archived objects in the heap may not
// have been loaded into the system dictionary yet. Nevertheless, oop->klass() should
// have enough information (object size, oop maps, etc) so that a GC can be safely
// performed.
//
// -XX:VerifyArchivedFields=2 force a GC to happen in such an early stage
// to check for GC safety.
log_info(cds, heap)("Trigger GC %s initializing static field(s) in %s",
which, k->external_name());
FlagSetting fs1(VerifyBeforeGC, true);
FlagSetting fs2(VerifyDuringGC, true);
FlagSetting fs3(VerifyAfterGC, true);
Universe::heap()->collect(GCCause::_java_lang_system_gc);
}
}
}
// Before GC can execute, we must ensure that all oops reachable from HeapShared::roots()
// have a valid klass. I.e., oopDesc::klass() must have already been resolved.
//
// Note: if a ArchivedKlassSubGraphInfoRecord contains non-early classes, and JVMTI
// ClassFileLoadHook is enabled, it's possible for this class to be dynamically replaced. In
// this case, we will not load the ArchivedKlassSubGraphInfoRecord and will clear its roots.
void HeapShared::resolve_classes(JavaThread* current) {
assert(UseSharedSpaces, "runtime only!");
if (!ArchiveHeapLoader::is_in_use()) {
return; // nothing to do
}
resolve_classes_for_subgraphs(current, archive_subgraph_entry_fields);
resolve_classes_for_subgraphs(current, fmg_archive_subgraph_entry_fields);
}
void HeapShared::resolve_classes_for_subgraphs(JavaThread* current, ArchivableStaticFieldInfo fields[]) {
for (int i = 0; fields[i].valid(); i++) {
ArchivableStaticFieldInfo* info = &fields[i];
TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
InstanceKlass* k = SystemDictionaryShared::find_builtin_class(klass_name);
assert(k != nullptr && k->is_shared_boot_class(), "sanity");
resolve_classes_for_subgraph_of(current, k);
}
}
void HeapShared::resolve_classes_for_subgraph_of(JavaThread* current, Klass* k) {
JavaThread* THREAD = current;
ExceptionMark em(THREAD);
const ArchivedKlassSubGraphInfoRecord* record =
resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/false, THREAD);
if (HAS_PENDING_EXCEPTION) {
CLEAR_PENDING_EXCEPTION;
}
if (record == nullptr) {
clear_archived_roots_of(k);
}
}
void HeapShared::initialize_from_archived_subgraph(JavaThread* current, Klass* k) {
JavaThread* THREAD = current;
if (!ArchiveHeapLoader::is_in_use()) {
return; // nothing to do
}
ExceptionMark em(THREAD);
const ArchivedKlassSubGraphInfoRecord* record =
resolve_or_init_classes_for_subgraph_of(k, /*do_init=*/true, THREAD);
if (HAS_PENDING_EXCEPTION) {
CLEAR_PENDING_EXCEPTION;
// None of the field value will be set if there was an exception when initializing the classes.
// The java code will not see any of the archived objects in the
// subgraphs referenced from k in this case.
return;
}
if (record != nullptr) {
init_archived_fields_for(k, record);
}
}
const ArchivedKlassSubGraphInfoRecord*
HeapShared::resolve_or_init_classes_for_subgraph_of(Klass* k, bool do_init, TRAPS) {
assert(!DumpSharedSpaces, "Should not be called with DumpSharedSpaces");
if (!k->is_shared()) {
return nullptr;
}
unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
#ifndef PRODUCT
if (_test_class_name != nullptr && k->name()->equals(_test_class_name) && record != nullptr) {
_test_class = k;
_test_class_record = record;
}
#endif
// Initialize from archived data. Currently this is done only
// during VM initialization time. No lock is needed.
if (record != nullptr) {
if (record->is_full_module_graph() && !MetaspaceShared::use_full_module_graph()) {
if (log_is_enabled(Info, cds, heap)) {
ResourceMark rm(THREAD);
log_info(cds, heap)("subgraph %s cannot be used because full module graph is disabled",
k->external_name());
}
return nullptr;
}
if (record->has_non_early_klasses() && JvmtiExport::should_post_class_file_load_hook()) {
if (log_is_enabled(Info, cds, heap)) {
ResourceMark rm(THREAD);
log_info(cds, heap)("subgraph %s cannot be used because JVMTI ClassFileLoadHook is enabled",
k->external_name());
}
return nullptr;
}
if (log_is_enabled(Info, cds, heap)) {
ResourceMark rm;
log_info(cds, heap)("%s subgraph %s ", do_init ? "init" : "resolve", k->external_name());
}
resolve_or_init(k, do_init, CHECK_NULL);
// Load/link/initialize the klasses of the objects in the subgraph.
// nullptr class loader is used.
Array<Klass*>* klasses = record->subgraph_object_klasses();
if (klasses != nullptr) {
for (int i = 0; i < klasses->length(); i++) {
Klass* klass = klasses->at(i);
if (!klass->is_shared()) {
return nullptr;
}
resolve_or_init(klass, do_init, CHECK_NULL);
}
}
}
return record;
}
void HeapShared::resolve_or_init(Klass* k, bool do_init, TRAPS) {
if (!do_init) {
if (k->class_loader_data() == nullptr) {
Klass* resolved_k = SystemDictionary::resolve_or_null(k->name(), CHECK);
assert(resolved_k == k, "classes used by archived heap must not be replaced by JVMTI ClassFileLoadHook");
}
} else {
assert(k->class_loader_data() != nullptr, "must have been resolved by HeapShared::resolve_classes");
if (k->is_instance_klass()) {
InstanceKlass* ik = InstanceKlass::cast(k);
ik->initialize(CHECK);
} else if (k->is_objArray_klass()) {
ObjArrayKlass* oak = ObjArrayKlass::cast(k);
oak->initialize(CHECK);
}
}
}
void HeapShared::init_archived_fields_for(Klass* k, const ArchivedKlassSubGraphInfoRecord* record) {
verify_the_heap(k, "before");
// Load the subgraph entry fields from the record and store them back to
// the corresponding fields within the mirror.
oop m = k->java_mirror();
Array<int>* entry_field_records = record->entry_field_records();
if (entry_field_records != nullptr) {
int efr_len = entry_field_records->length();
assert(efr_len % 2 == 0, "sanity");
for (int i = 0; i < efr_len; i += 2) {
int field_offset = entry_field_records->at(i);
int root_index = entry_field_records->at(i+1);
oop v = get_root(root_index, /*clear=*/true);
m->obj_field_put(field_offset, v);
log_debug(cds, heap)(" " PTR_FORMAT " init field @ %2d = " PTR_FORMAT, p2i(k), field_offset, p2i(v));
}
// Done. Java code can see the archived sub-graphs referenced from k's
// mirror after this point.
if (log_is_enabled(Info, cds, heap)) {
ResourceMark rm;
log_info(cds, heap)("initialize_from_archived_subgraph %s " PTR_FORMAT "%s",
k->external_name(), p2i(k), JvmtiExport::is_early_phase() ? " (early)" : "");
}
}
verify_the_heap(k, "after ");
}
void HeapShared::clear_archived_roots_of(Klass* k) {
unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary_quick(k);
const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
if (record != nullptr) {
Array<int>* entry_field_records = record->entry_field_records();
if (entry_field_records != nullptr) {
int efr_len = entry_field_records->length();
assert(efr_len % 2 == 0, "sanity");
for (int i = 0; i < efr_len; i += 2) {
int root_index = entry_field_records->at(i+1);
clear_root(root_index);
}
}
}
}
class WalkOopAndArchiveClosure: public BasicOopIterateClosure {
int _level;
bool _record_klasses_only;
KlassSubGraphInfo* _subgraph_info;
oop _referencing_obj;
// The following are for maintaining a stack for determining
// CachedOopInfo::_referrer
static WalkOopAndArchiveClosure* _current;
WalkOopAndArchiveClosure* _last;
public:
WalkOopAndArchiveClosure(int level,
bool record_klasses_only,
KlassSubGraphInfo* subgraph_info,
oop orig) :
_level(level),
_record_klasses_only(record_klasses_only),
_subgraph_info(subgraph_info),
_referencing_obj(orig) {
_last = _current;
_current = this;
}
~WalkOopAndArchiveClosure() {
_current = _last;
}
void do_oop(narrowOop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
void do_oop( oop *p) { WalkOopAndArchiveClosure::do_oop_work(p); }
protected:
template <class T> void do_oop_work(T *p) {
oop obj = RawAccess<>::oop_load(p);
if (!CompressedOops::is_null(obj)) {
size_t field_delta = pointer_delta(p, _referencing_obj, sizeof(char));
if (!_record_klasses_only && log_is_enabled(Debug, cds, heap)) {
ResourceMark rm;
log_debug(cds, heap)("(%d) %s[" SIZE_FORMAT "] ==> " PTR_FORMAT " size " SIZE_FORMAT " %s", _level,
_referencing_obj->klass()->external_name(), field_delta,
p2i(obj), obj->size() * HeapWordSize, obj->klass()->external_name());
if (log_is_enabled(Trace, cds, heap)) {
LogTarget(Trace, cds, heap) log;
LogStream out(log);
obj->print_on(&out);
}
}
bool success = HeapShared::archive_reachable_objects_from(
_level + 1, _subgraph_info, obj);
assert(success, "VM should have exited with unarchivable objects for _level > 1");
}
}
public:
static WalkOopAndArchiveClosure* current() { return _current; }
oop referencing_obj() { return _referencing_obj; }
KlassSubGraphInfo* subgraph_info() { return _subgraph_info; }
};
WalkOopAndArchiveClosure* WalkOopAndArchiveClosure::_current = nullptr;
HeapShared::CachedOopInfo HeapShared::make_cached_oop_info() {
WalkOopAndArchiveClosure* walker = WalkOopAndArchiveClosure::current();
oop referrer = (walker == nullptr) ? nullptr : walker->referencing_obj();
return CachedOopInfo(referrer);
}
// (1) If orig_obj has not been archived yet, archive it.
// (2) If orig_obj has not been seen yet (since start_recording_subgraph() was called),
// trace all objects that are reachable from it, and make sure these objects are archived.
// (3) Record the klasses of all orig_obj and all reachable objects.
bool HeapShared::archive_reachable_objects_from(int level,
KlassSubGraphInfo* subgraph_info,
oop orig_obj) {
assert(orig_obj != nullptr, "must be");
if (!JavaClasses::is_supported_for_archiving(orig_obj)) {
// This object has injected fields that cannot be supported easily, so we disallow them for now.
// If you get an error here, you probably made a change in the JDK library that has added
// these objects that are referenced (directly or indirectly) by static fields.
ResourceMark rm;
log_error(cds, heap)("Cannot archive object of class %s", orig_obj->klass()->external_name());
MetaspaceShared::unrecoverable_writing_error();
}
// java.lang.Class instances cannot be included in an archived object sub-graph. We only support
// them as Klass::_archived_mirror because they need to be specially restored at run time.
//
// If you get an error here, you probably made a change in the JDK library that has added a Class
// object that is referenced (directly or indirectly) by static fields.
if (java_lang_Class::is_instance(orig_obj) && subgraph_info != _default_subgraph_info) {
log_error(cds, heap)("(%d) Unknown java.lang.Class object is in the archived sub-graph", level);
MetaspaceShared::unrecoverable_writing_error();
}
if (has_been_seen_during_subgraph_recording(orig_obj)) {
// orig_obj has already been archived and traced. Nothing more to do.
return true;
} else {
set_has_been_seen_during_subgraph_recording(orig_obj);
}
bool already_archived = has_been_archived(orig_obj);
bool record_klasses_only = already_archived;
if (!already_archived) {
++_num_new_archived_objs;
if (!archive_object(orig_obj)) {
// Skip archiving the sub-graph referenced from the current entry field.
ResourceMark rm;
log_error(cds, heap)(
"Cannot archive the sub-graph referenced from %s object ("
PTR_FORMAT ") size " SIZE_FORMAT ", skipped.",
orig_obj->klass()->external_name(), p2i(orig_obj), orig_obj->size() * HeapWordSize);
if (level == 1) {
// Don't archive a subgraph root that's too big. For archives static fields, that's OK
// as the Java code will take care of initializing this field dynamically.
return false;
} else {
// We don't know how to handle an object that has been archived, but some of its reachable
// objects cannot be archived. Bail out for now. We might need to fix this in the future if
// we have a real use case.
MetaspaceShared::unrecoverable_writing_error();
}
}
}
Klass *orig_k = orig_obj->klass();
subgraph_info->add_subgraph_object_klass(orig_k);
WalkOopAndArchiveClosure walker(level, record_klasses_only, subgraph_info, orig_obj);
orig_obj->oop_iterate(&walker);
check_enum_obj(level + 1, subgraph_info, orig_obj);
return true;
}
//
// Start from the given static field in a java mirror and archive the
// complete sub-graph of java heap objects that are reached directly
// or indirectly from the starting object by following references.
// Sub-graph archiving restrictions (current):
//
// - All classes of objects in the archived sub-graph (including the
// entry class) must be boot class only.
// - No java.lang.Class instance (java mirror) can be included inside
// an archived sub-graph. Mirror can only be the sub-graph entry object.
//
// The Java heap object sub-graph archiving process (see
// WalkOopAndArchiveClosure):
//
// 1) Java object sub-graph archiving starts from a given static field
// within a Class instance (java mirror). If the static field is a
// reference field and points to a non-null java object, proceed to
// the next step.
//
// 2) Archives the referenced java object. If an archived copy of the
// current object already exists, updates the pointer in the archived
// copy of the referencing object to point to the current archived object.
// Otherwise, proceed to the next step.
//
// 3) Follows all references within the current java object and recursively
// archive the sub-graph of objects starting from each reference.
//
// 4) Updates the pointer in the archived copy of referencing object to
// point to the current archived object.
//
// 5) The Klass of the current java object is added to the list of Klasses
// for loading and initializing before any object in the archived graph can
// be accessed at runtime.
//
void HeapShared::archive_reachable_objects_from_static_field(InstanceKlass *k,
const char* klass_name,
int field_offset,
const char* field_name) {
assert(DumpSharedSpaces, "dump time only");
assert(k->is_shared_boot_class(), "must be boot class");
oop m = k->java_mirror();
KlassSubGraphInfo* subgraph_info = get_subgraph_info(k);
oop f = m->obj_field(field_offset);
log_debug(cds, heap)("Start archiving from: %s::%s (" PTR_FORMAT ")", klass_name, field_name, p2i(f));
if (!CompressedOops::is_null(f)) {
if (log_is_enabled(Trace, cds, heap)) {
LogTarget(Trace, cds, heap) log;
LogStream out(log);
f->print_on(&out);
}
bool success = archive_reachable_objects_from(1, subgraph_info, f);
if (!success) {
log_error(cds, heap)("Archiving failed %s::%s (some reachable objects cannot be archived)",
klass_name, field_name);
} else {
// Note: the field value is not preserved in the archived mirror.
// Record the field as a new subGraph entry point. The recorded
// information is restored from the archive at runtime.
subgraph_info->add_subgraph_entry_field(field_offset, f);
log_info(cds, heap)("Archived field %s::%s => " PTR_FORMAT, klass_name, field_name, p2i(f));
}
} else {
// The field contains null, we still need to record the entry point,
// so it can be restored at runtime.
subgraph_info->add_subgraph_entry_field(field_offset, nullptr);
}
}
#ifndef PRODUCT
class VerifySharedOopClosure: public BasicOopIterateClosure {
public:
void do_oop(narrowOop *p) { VerifySharedOopClosure::do_oop_work(p); }
void do_oop( oop *p) { VerifySharedOopClosure::do_oop_work(p); }
protected:
template <class T> void do_oop_work(T *p) {
oop obj = RawAccess<>::oop_load(p);
if (!CompressedOops::is_null(obj)) {
HeapShared::verify_reachable_objects_from(obj);
}
}
};
void HeapShared::verify_subgraph_from_static_field(InstanceKlass* k, int field_offset) {
assert(DumpSharedSpaces, "dump time only");
assert(k->is_shared_boot_class(), "must be boot class");
oop m = k->java_mirror();
oop f = m->obj_field(field_offset);
if (!CompressedOops::is_null(f)) {
verify_subgraph_from(f);
}
}
void HeapShared::verify_subgraph_from(oop orig_obj) {
if (!has_been_archived(orig_obj)) {
// It's OK for the root of a subgraph to be not archived. See comments in
// archive_reachable_objects_from().
return;
}
// Verify that all objects reachable from orig_obj are archived.
init_seen_objects_table();
verify_reachable_objects_from(orig_obj);
delete_seen_objects_table();
}
void HeapShared::verify_reachable_objects_from(oop obj) {
_num_total_verifications ++;
if (!has_been_seen_during_subgraph_recording(obj)) {
set_has_been_seen_during_subgraph_recording(obj);
assert(has_been_archived(obj), "must be");
VerifySharedOopClosure walker;
obj->oop_iterate(&walker);
}
}
#endif
// The "default subgraph" contains special objects (see heapShared.hpp) that
// can be accessed before we load any Java classes (including java/lang/Class).
// Make sure that these are only instances of the very few specific types
// that we can handle.
void HeapShared::check_default_subgraph_classes() {
GrowableArray<Klass*>* klasses = _default_subgraph_info->subgraph_object_klasses();
int num = klasses->length();
for (int i = 0; i < num; i++) {
Klass* subgraph_k = klasses->at(i);
if (log_is_enabled(Info, cds, heap)) {
ResourceMark rm;
log_info(cds, heap)(
"Archived object klass (default subgraph %d) => %s",
i, subgraph_k->external_name());
}
guarantee(subgraph_k->name()->equals("java/lang/Class") ||
subgraph_k->name()->equals("java/lang/String") ||
subgraph_k->name()->equals("[Ljava/lang/Object;") ||
subgraph_k->name()->equals("[C") ||
subgraph_k->name()->equals("[B"),
"default subgraph can have only these objects");
}
}
HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = nullptr;
int HeapShared::_num_new_walked_objs;
int HeapShared::_num_new_archived_objs;
int HeapShared::_num_old_recorded_klasses;
int HeapShared::_num_total_subgraph_recordings = 0;
int HeapShared::_num_total_walked_objs = 0;
int HeapShared::_num_total_archived_objs = 0;
int HeapShared::_num_total_recorded_klasses = 0;
int HeapShared::_num_total_verifications = 0;
bool HeapShared::has_been_seen_during_subgraph_recording(oop obj) {
return _seen_objects_table->get(obj) != nullptr;
}
void HeapShared::set_has_been_seen_during_subgraph_recording(oop obj) {
assert(!has_been_seen_during_subgraph_recording(obj), "sanity");
_seen_objects_table->put(obj, true);
++ _num_new_walked_objs;
}
void HeapShared::start_recording_subgraph(InstanceKlass *k, const char* class_name, bool is_full_module_graph) {
log_info(cds, heap)("Start recording subgraph(s) for archived fields in %s", class_name);
init_subgraph_info(k, is_full_module_graph);
init_seen_objects_table();
_num_new_walked_objs = 0;
_num_new_archived_objs = 0;
_num_old_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses();
}
void HeapShared::done_recording_subgraph(InstanceKlass *k, const char* class_name) {
int num_new_recorded_klasses = get_subgraph_info(k)->num_subgraph_object_klasses() -
_num_old_recorded_klasses;
log_info(cds, heap)("Done recording subgraph(s) for archived fields in %s: "
"walked %d objs, archived %d new objs, recorded %d classes",
class_name, _num_new_walked_objs, _num_new_archived_objs,
num_new_recorded_klasses);
delete_seen_objects_table();
_num_total_subgraph_recordings ++;
_num_total_walked_objs += _num_new_walked_objs;
_num_total_archived_objs += _num_new_archived_objs;
_num_total_recorded_klasses += num_new_recorded_klasses;
}
class ArchivableStaticFieldFinder: public FieldClosure {
InstanceKlass* _ik;
Symbol* _field_name;
bool _found;
int _offset;
public:
ArchivableStaticFieldFinder(InstanceKlass* ik, Symbol* field_name) :
_ik(ik), _field_name(field_name), _found(false), _offset(-1) {}
virtual void do_field(fieldDescriptor* fd) {
if (fd->name() == _field_name) {
assert(!_found, "fields can never be overloaded");
if (is_reference_type(fd->field_type())) {
_found = true;
_offset = fd->offset();
}
}
}
bool found() { return _found; }
int offset() { return _offset; }
};
void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
TRAPS) {
for (int i = 0; fields[i].valid(); i++) {
ArchivableStaticFieldInfo* info = &fields[i];
TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
TempNewSymbol field_name = SymbolTable::new_symbol(info->field_name);
ResourceMark rm; // for stringStream::as_string() etc.
#ifndef PRODUCT
bool is_test_class = (ArchiveHeapTestClass != nullptr) && (strcmp(info->klass_name, ArchiveHeapTestClass) == 0);
#else
bool is_test_class = false;
#endif
if (is_test_class) {
log_warning(cds)("Loading ArchiveHeapTestClass %s ...", ArchiveHeapTestClass);
}
Klass* k = SystemDictionary::resolve_or_fail(klass_name, true, THREAD);
if (HAS_PENDING_EXCEPTION) {
CLEAR_PENDING_EXCEPTION;
stringStream st;
st.print("Fail to initialize archive heap: %s cannot be loaded by the boot loader", info->klass_name);
THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
}
if (!k->is_instance_klass()) {
stringStream st;
st.print("Fail to initialize archive heap: %s is not an instance class", info->klass_name);
THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
}
InstanceKlass* ik = InstanceKlass::cast(k);
assert(InstanceKlass::cast(ik)->is_shared_boot_class(),
"Only support boot classes");
if (is_test_class) {
if (ik->module()->is_named()) {
// We don't want ArchiveHeapTestClass to be abused to easily load/initialize arbitrary
// core-lib classes. You need to at least append to the bootclasspath.
stringStream st;
st.print("ArchiveHeapTestClass %s is not in unnamed module", ArchiveHeapTestClass);
THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
}
if (ik->package() != nullptr) {
// This restriction makes HeapShared::is_a_test_class_in_unnamed_module() easy.
stringStream st;
st.print("ArchiveHeapTestClass %s is not in unnamed package", ArchiveHeapTestClass);
THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
}
} else {
if (ik->module()->name() != vmSymbols::java_base()) {
// We don't want to deal with cases when a module is unavailable at runtime.
// FUTURE -- load from archived heap only when module graph has not changed
// between dump and runtime.
stringStream st;
st.print("%s is not in java.base module", info->klass_name);
THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
}
}
if (is_test_class) {
log_warning(cds)("Initializing ArchiveHeapTestClass %s ...", ArchiveHeapTestClass);
}
ik->initialize(CHECK);
ArchivableStaticFieldFinder finder(ik, field_name);
ik->do_local_static_fields(&finder);
if (!finder.found()) {
stringStream st;
st.print("Unable to find the static T_OBJECT field %s::%s", info->klass_name, info->field_name);
THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), st.as_string());
}
info->klass = ik;
info->offset = finder.offset();
}
}
void HeapShared::init_subgraph_entry_fields(TRAPS) {
assert(HeapShared::can_write(), "must be");
_dump_time_subgraph_info_table = new (mtClass)DumpTimeKlassSubGraphInfoTable();
init_subgraph_entry_fields(archive_subgraph_entry_fields, CHECK);
if (MetaspaceShared::use_full_module_graph()) {
init_subgraph_entry_fields(fmg_archive_subgraph_entry_fields, CHECK);
}
}
#ifndef PRODUCT
void HeapShared::setup_test_class(const char* test_class_name) {
ArchivableStaticFieldInfo* p = archive_subgraph_entry_fields;
int num_slots = sizeof(archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
assert(p[num_slots - 2].klass_name == nullptr, "must have empty slot that's patched below");
assert(p[num_slots - 1].klass_name == nullptr, "must have empty slot that marks the end of the list");
if (test_class_name != nullptr) {
p[num_slots - 2].klass_name = test_class_name;
p[num_slots - 2].field_name = ARCHIVE_TEST_FIELD_NAME;
}
}
// See if ik is one of the test classes that are pulled in by -XX:ArchiveHeapTestClass
// during runtime. This may be called before the module system is initialized so
// we cannot rely on InstanceKlass::module(), etc.
bool HeapShared::is_a_test_class_in_unnamed_module(Klass* ik) {
if (_test_class != nullptr) {
if (ik == _test_class) {
return true;
}
Array<Klass*>* klasses = _test_class_record->subgraph_object_klasses();
if (klasses == nullptr) {
return false;
}
for (int i = 0; i < klasses->length(); i++) {
Klass* k = klasses->at(i);
if (k == ik) {
Symbol* name;
if (k->is_instance_klass()) {
name = InstanceKlass::cast(k)->name();
} else if (k->is_objArray_klass()) {
Klass* bk = ObjArrayKlass::cast(k)->bottom_klass();
if (!bk->is_instance_klass()) {
return false;
}
name = bk->name();
} else {
return false;
}
// See KlassSubGraphInfo::check_allowed_klass() - only two types of
// classes are allowed:
// (A) java.base classes (which must not be in the unnamed module)
// (B) test classes which must be in the unnamed package of the unnamed module.
// So if we see a '/' character in the class name, it must be in (A);
// otherwise it must be in (B).
if (name->index_of_at(0, "/", 1) >= 0) {
return false; // (A)
}
return true; // (B)
}
}
}
return false;
}
#endif
void HeapShared::init_for_dumping(TRAPS) {
if (HeapShared::can_write()) {
setup_test_class(ArchiveHeapTestClass);
_dumped_interned_strings = new (mtClass)DumpedInternedStrings();
init_subgraph_entry_fields(CHECK);
}
}
void HeapShared::archive_object_subgraphs(ArchivableStaticFieldInfo fields[],
bool is_full_module_graph) {
_num_total_subgraph_recordings = 0;
_num_total_walked_objs = 0;
_num_total_archived_objs = 0;
_num_total_recorded_klasses = 0;
_num_total_verifications = 0;
// For each class X that has one or more archived fields:
// [1] Dump the subgraph of each archived field
// [2] Create a list of all the class of the objects that can be reached
// by any of these static fields.
// At runtime, these classes are initialized before X's archived fields
// are restored by HeapShared::initialize_from_archived_subgraph().
int i;
for (int i = 0; fields[i].valid(); ) {
ArchivableStaticFieldInfo* info = &fields[i];
const char* klass_name = info->klass_name;
start_recording_subgraph(info->klass, klass_name, is_full_module_graph);
// If you have specified consecutive fields of the same klass in
// fields[], these will be archived in the same
// {start_recording_subgraph ... done_recording_subgraph} pass to
// save time.
for (; fields[i].valid(); i++) {
ArchivableStaticFieldInfo* f = &fields[i];
if (f->klass_name != klass_name) {
break;
}
archive_reachable_objects_from_static_field(f->klass, f->klass_name,
f->offset, f->field_name);
}
done_recording_subgraph(info->klass, klass_name);
}
log_info(cds, heap)("Archived subgraph records = %d",
_num_total_subgraph_recordings);
log_info(cds, heap)(" Walked %d objects", _num_total_walked_objs);
log_info(cds, heap)(" Archived %d objects", _num_total_archived_objs);
log_info(cds, heap)(" Recorded %d klasses", _num_total_recorded_klasses);
#ifndef PRODUCT
for (int i = 0; fields[i].valid(); i++) {
ArchivableStaticFieldInfo* f = &fields[i];
verify_subgraph_from_static_field(f->klass, f->offset);
}
log_info(cds, heap)(" Verified %d references", _num_total_verifications);
#endif
}
// Not all the strings in the global StringTable are dumped into the archive, because
// some of those strings may be only referenced by classes that are excluded from
// the archive. We need to explicitly mark the strings that are:
// [1] used by classes that WILL be archived;
// [2] included in the SharedArchiveConfigFile.
void HeapShared::add_to_dumped_interned_strings(oop string) {
assert_at_safepoint(); // DumpedInternedStrings uses raw oops
assert(!ArchiveHeapWriter::is_string_too_large_to_archive(string), "must be");
bool created;
_dumped_interned_strings->put_if_absent(string, true, &created);
}
#ifndef PRODUCT
// At dump-time, find the location of all the non-null oop pointers in an archived heap
// region. This way we can quickly relocate all the pointers without using
// BasicOopIterateClosure at runtime.
class FindEmbeddedNonNullPointers: public BasicOopIterateClosure {
void* _start;
BitMap *_oopmap;
int _num_total_oops;
int _num_null_oops;
public:
FindEmbeddedNonNullPointers(void* start, BitMap* oopmap)
: _start(start), _oopmap(oopmap), _num_total_oops(0), _num_null_oops(0) {}
virtual void do_oop(narrowOop* p) {
assert(UseCompressedOops, "sanity");
_num_total_oops ++;
narrowOop v = *p;
if (!CompressedOops::is_null(v)) {
// Note: HeapShared::to_requested_address() is not necessary because
// the heap always starts at a deterministic address with UseCompressedOops==true.
size_t idx = p - (narrowOop*)_start;
_oopmap->set_bit(idx);
} else {
_num_null_oops ++;
}
}
virtual void do_oop(oop* p) {
assert(!UseCompressedOops, "sanity");
_num_total_oops ++;
if ((*p) != nullptr) {
size_t idx = p - (oop*)_start;
_oopmap->set_bit(idx);
} else {
_num_null_oops ++;
}
}
int num_total_oops() const { return _num_total_oops; }
int num_null_oops() const { return _num_null_oops; }
};
#endif
address HeapShared::to_requested_address(address dumptime_addr) {
assert(DumpSharedSpaces, "static dump time only");
if (dumptime_addr == nullptr || UseCompressedOops) {
return dumptime_addr;
}
// With UseCompressedOops==false, actual_base is selected by the OS so
// it's different across -Xshare:dump runs.
address actual_base = (address)G1CollectedHeap::heap()->reserved().start();
address actual_end = (address)G1CollectedHeap::heap()->reserved().end();
assert(actual_base <= dumptime_addr && dumptime_addr <= actual_end, "must be an address in the heap");
// We always write the objects as if the heap started at this address. This
// makes the heap content deterministic.
//
// Note that at runtime, the heap address is also selected by the OS, so
// the archive heap will not be mapped at 0x10000000. Instead, we will call
// HeapShared::patch_embedded_pointers() to relocate the heap contents
// accordingly.
const address REQUESTED_BASE = (address)0x10000000;
intx delta = REQUESTED_BASE - actual_base;
address requested_addr = dumptime_addr + delta;
assert(REQUESTED_BASE != 0 && requested_addr != nullptr, "sanity");
return requested_addr;
}
#ifndef PRODUCT
ResourceBitMap HeapShared::calculate_oopmap(MemRegion region) {
size_t num_bits = region.byte_size() / (UseCompressedOops ? sizeof(narrowOop) : sizeof(oop));
ResourceBitMap oopmap(num_bits);
HeapWord* p = region.start();
HeapWord* end = region.end();
FindEmbeddedNonNullPointers finder((void*)p, &oopmap);
int num_objs = 0;
while (p < end) {
oop o = cast_to_oop(p);
o->oop_iterate(&finder);
p += o->size();
++ num_objs;
}
log_info(cds, heap)("calculate_oopmap: objects = %6d, oop fields = %7d (nulls = %7d)",
num_objs, finder.num_total_oops(), finder.num_null_oops());
return oopmap;
}
#endif // !PRODUCT
void HeapShared::count_allocation(size_t size) {
_total_obj_count ++;
_total_obj_size += size;
for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
if (size <= (size_t(1) << i)) {
_alloc_count[i] ++;
_alloc_size[i] += size;
return;
}
}
}
static double avg_size(size_t size, size_t count) {
double avg = 0;
if (count > 0) {
avg = double(size * HeapWordSize) / double(count);
}
return avg;
}
void HeapShared::print_stats() {
size_t huge_count = _total_obj_count;
size_t huge_size = _total_obj_size;
for (int i = 0; i < ALLOC_STAT_SLOTS; i++) {
size_t byte_size_limit = (size_t(1) << i) * HeapWordSize;
size_t count = _alloc_count[i];
size_t size = _alloc_size[i];
log_info(cds, heap)(SIZE_FORMAT_W(8) " objects are <= " SIZE_FORMAT_W(-6)
" bytes (total " SIZE_FORMAT_W(8) " bytes, avg %8.1f bytes)",
count, byte_size_limit, size * HeapWordSize, avg_size(size, count));
huge_count -= count;
huge_size -= size;
}
log_info(cds, heap)(SIZE_FORMAT_W(8) " huge objects (total " SIZE_FORMAT_W(8) " bytes"
", avg %8.1f bytes)",
huge_count, huge_size * HeapWordSize,
avg_size(huge_size, huge_count));
log_info(cds, heap)(SIZE_FORMAT_W(8) " total objects (total " SIZE_FORMAT_W(8) " bytes"
", avg %8.1f bytes)",
_total_obj_count, _total_obj_size * HeapWordSize,
avg_size(_total_obj_size, _total_obj_count));
}
#endif // INCLUDE_CDS_JAVA_HEAP