JDK14/Java14源码在线阅读
/*
* Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
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*/
#include "precompiled.hpp"
#include "classfile/javaClasses.inline.hpp"
#include "classfile/stringTable.hpp"
#include "classfile/symbolTable.hpp"
#include "classfile/systemDictionaryShared.hpp"
#include "classfile/vmSymbols.hpp"
#include "logging/log.hpp"
#include "logging/logMessage.hpp"
#include "logging/logStream.hpp"
#include "memory/archiveUtils.hpp"
#include "memory/filemap.hpp"
#include "memory/heapShared.inline.hpp"
#include "memory/iterator.inline.hpp"
#include "memory/metadataFactory.hpp"
#include "memory/metaspaceClosure.hpp"
#include "memory/metaspaceShared.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "oops/compressedOops.inline.hpp"
#include "oops/fieldStreams.inline.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/fieldDescriptor.inline.hpp"
#include "runtime/safepointVerifiers.hpp"
#include "utilities/bitMap.inline.hpp"
#if INCLUDE_G1GC
#include "gc/g1/g1CollectedHeap.hpp"
#endif
#if INCLUDE_CDS_JAVA_HEAP
bool HeapShared::_closed_archive_heap_region_mapped = false;
bool HeapShared::_open_archive_heap_region_mapped = false;
bool HeapShared::_archive_heap_region_fixed = false;
address HeapShared::_narrow_oop_base;
int HeapShared::_narrow_oop_shift;
//
// If you add new entries to the following tables, you should know what you're doing!
//
// Entry fields for shareable subgraphs archived in the closed archive heap
// region. Warning: Objects in the subgraphs should not have reference fields
// assigned at runtime.
static ArchivableStaticFieldInfo closed_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"},
};
// Entry fields for subgraphs archived in the open archive heap region.
static ArchivableStaticFieldInfo open_archive_subgraph_entry_fields[] = {
{"jdk/internal/module/ArchivedModuleGraph", "archivedModuleGraph"},
{"java/util/ImmutableCollections$ListN", "EMPTY_LIST"},
{"java/util/ImmutableCollections$MapN", "EMPTY_MAP"},
{"java/util/ImmutableCollections$SetN", "EMPTY_SET"},
{"java/lang/module/Configuration", "EMPTY_CONFIGURATION"},
{"jdk/internal/math/FDBigInteger", "archivedCaches"},
};
const static int num_closed_archive_subgraph_entry_fields =
sizeof(closed_archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
const static int num_open_archive_subgraph_entry_fields =
sizeof(open_archive_subgraph_entry_fields) / sizeof(ArchivableStaticFieldInfo);
////////////////////////////////////////////////////////////////
//
// Java heap object archiving support
//
////////////////////////////////////////////////////////////////
void HeapShared::fixup_mapped_heap_regions() {
FileMapInfo *mapinfo = FileMapInfo::current_info();
mapinfo->fixup_mapped_heap_regions();
set_archive_heap_region_fixed();
}
unsigned HeapShared::oop_hash(oop const& p) {
assert(!p->mark().has_bias_pattern(),
"this object should never have been locked"); // so identity_hash won't safepoin
unsigned hash = (unsigned)p->identity_hash();
return hash;
}
HeapShared::ArchivedObjectCache* HeapShared::_archived_object_cache = NULL;
oop HeapShared::find_archived_heap_object(oop obj) {
assert(DumpSharedSpaces, "dump-time only");
ArchivedObjectCache* cache = archived_object_cache();
oop* p = cache->get(obj);
if (p != NULL) {
return *p;
} else {
return NULL;
}
}
oop HeapShared::archive_heap_object(oop obj, Thread* THREAD) {
assert(DumpSharedSpaces, "dump-time only");
oop ao = find_archived_heap_object(obj);
if (ao != NULL) {
// already archived
return ao;
}
int len = obj->size();
if (G1CollectedHeap::heap()->is_archive_alloc_too_large(len)) {
log_debug(cds, heap)("Cannot archive, object (" PTR_FORMAT ") is too large: " SIZE_FORMAT,
p2i(obj), (size_t)obj->size());
return NULL;
}
// Pre-compute object identity hash at CDS dump time.
obj->identity_hash();
oop archived_oop = (oop)G1CollectedHeap::heap()->archive_mem_allocate(len);
if (archived_oop != NULL) {
Copy::aligned_disjoint_words((HeapWord*)obj, (HeapWord*)archived_oop, len);
MetaspaceShared::relocate_klass_ptr(archived_oop);
ArchivedObjectCache* cache = archived_object_cache();
cache->put(obj, archived_oop);
log_debug(cds, heap)("Archived heap object " PTR_FORMAT " ==> " PTR_FORMAT,
p2i(obj), p2i(archived_oop));
} else {
log_error(cds, heap)(
"Cannot allocate space for object " PTR_FORMAT " in archived heap region",
p2i(obj));
vm_exit(1);
}
return archived_oop;
}
oop HeapShared::materialize_archived_object(narrowOop v) {
assert(archive_heap_region_fixed(),
"must be called after archive heap regions are fixed");
if (!CompressedOops::is_null(v)) {
oop obj = HeapShared::decode_from_archive(v);
return G1CollectedHeap::heap()->materialize_archived_object(obj);
}
return NULL;
}
void HeapShared::archive_klass_objects(Thread* THREAD) {
GrowableArray<Klass*>* klasses = MetaspaceShared::collected_klasses();
assert(klasses != NULL, "sanity");
for (int i = 0; i < klasses->length(); i++) {
Klass* k = klasses->at(i);
// archive mirror object
java_lang_Class::archive_mirror(k, CHECK);
// archive the resolved_referenes array
if (k->is_instance_klass()) {
InstanceKlass* ik = InstanceKlass::cast(k);
ik->constants()->archive_resolved_references(THREAD);
}
}
}
void HeapShared::archive_java_heap_objects(GrowableArray<MemRegion> *closed,
GrowableArray<MemRegion> *open) {
if (!is_heap_object_archiving_allowed()) {
if (log_is_enabled(Info, cds)) {
log_info(cds)(
"Archived java heap is not supported as UseG1GC, "
"UseCompressedOops and UseCompressedClassPointers are required."
"Current settings: UseG1GC=%s, UseCompressedOops=%s, UseCompressedClassPointers=%s.",
BOOL_TO_STR(UseG1GC), BOOL_TO_STR(UseCompressedOops),
BOOL_TO_STR(UseCompressedClassPointers));
}
return;
}
G1HeapVerifier::verify_ready_for_archiving();
{
NoSafepointVerifier nsv;
// Cache for recording where the archived objects are copied to
create_archived_object_cache();
tty->print_cr("Dumping objects to closed archive heap region ...");
NOT_PRODUCT(StringTable::verify());
copy_closed_archive_heap_objects(closed);
tty->print_cr("Dumping objects to open archive heap region ...");
copy_open_archive_heap_objects(open);
destroy_archived_object_cache();
}
G1HeapVerifier::verify_archive_regions();
}
void HeapShared::copy_closed_archive_heap_objects(
GrowableArray<MemRegion> * closed_archive) {
assert(is_heap_object_archiving_allowed(), "Cannot archive java heap objects");
Thread* THREAD = Thread::current();
G1CollectedHeap::heap()->begin_archive_alloc_range();
// Archive interned string objects
StringTable::write_to_archive();
archive_object_subgraphs(closed_archive_subgraph_entry_fields,
num_closed_archive_subgraph_entry_fields,
true /* is_closed_archive */, THREAD);
G1CollectedHeap::heap()->end_archive_alloc_range(closed_archive,
os::vm_allocation_granularity());
}
void HeapShared::copy_open_archive_heap_objects(
GrowableArray<MemRegion> * open_archive) {
assert(is_heap_object_archiving_allowed(), "Cannot archive java heap objects");
Thread* THREAD = Thread::current();
G1CollectedHeap::heap()->begin_archive_alloc_range(true /* open */);
java_lang_Class::archive_basic_type_mirrors(THREAD);
archive_klass_objects(THREAD);
archive_object_subgraphs(open_archive_subgraph_entry_fields,
num_open_archive_subgraph_entry_fields,
false /* is_closed_archive */,
THREAD);
G1CollectedHeap::heap()->end_archive_alloc_range(open_archive,
os::vm_allocation_granularity());
}
void HeapShared::init_narrow_oop_decoding(address base, int shift) {
_narrow_oop_base = base;
_narrow_oop_shift = shift;
}
//
// Subgraph archiving support
//
HeapShared::DumpTimeKlassSubGraphInfoTable* HeapShared::_dump_time_subgraph_info_table = NULL;
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 relocated
// Klass* of the original k.
KlassSubGraphInfo* HeapShared::get_subgraph_info(Klass* k) {
assert(DumpSharedSpaces, "dump time only");
Klass* relocated_k = MetaspaceShared::get_relocated_klass(k);
KlassSubGraphInfo* info = _dump_time_subgraph_info_table->get(relocated_k);
if (info == NULL) {
_dump_time_subgraph_info_table->put(relocated_k, KlassSubGraphInfo(relocated_k));
info = _dump_time_subgraph_info_table->get(relocated_k);
++ _dump_time_subgraph_info_table->_count;
}
return info;
}
// Add an entry field to the current KlassSubGraphInfo.
void KlassSubGraphInfo::add_subgraph_entry_field(
int static_field_offset, oop v, bool is_closed_archive) {
assert(DumpSharedSpaces, "dump time only");
if (_subgraph_entry_fields == NULL) {
_subgraph_entry_fields =
new(ResourceObj::C_HEAP, mtClass) GrowableArray<juint>(10, true);
}
_subgraph_entry_fields->append((juint)static_field_offset);
_subgraph_entry_fields->append(CompressedOops::encode(v));
_subgraph_entry_fields->append(is_closed_archive ? 1 : 0);
}
// 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, Klass *relocated_k) {
assert(DumpSharedSpaces, "dump time only");
assert(relocated_k == MetaspaceShared::get_relocated_klass(orig_k),
"must be the relocated Klass in the shared space");
if (_subgraph_object_klasses == NULL) {
_subgraph_object_klasses =
new(ResourceObj::C_HEAP, mtClass) GrowableArray<Klass*>(50, true);
}
assert(relocated_k->is_shared(), "must be a shared class");
if (_k == relocated_k) {
// Don't add the Klass containing the sub-graph to it's own klass
// initialization list.
return;
}
if (relocated_k->is_instance_klass()) {
assert(InstanceKlass::cast(relocated_k)->is_shared_boot_class(),
"must be boot class");
// SystemDictionary::xxx_klass() are not updated, need to check
// the original Klass*
if (orig_k == SystemDictionary::String_klass() ||
orig_k == SystemDictionary::Object_klass()) {
// Initialized early during VM initialization. No need to be added
// to the sub-graph object class list.
return;
}
} else if (relocated_k->is_objArray_klass()) {
Klass* abk = ObjArrayKlass::cast(relocated_k)->bottom_klass();
if (abk->is_instance_klass()) {
assert(InstanceKlass::cast(abk)->is_shared_boot_class(),
"must be boot class");
}
if (relocated_k == Universe::objectArrayKlassObj()) {
// Initialized early during Universe::genesis. No need to be added
// to the list.
return;
}
} else {
assert(relocated_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(relocated_k)) {
ResourceMark rm;
log_debug(cds, heap)("Adding klass %s", orig_k->external_name());
}
}
_subgraph_object_klasses->append_if_missing(relocated_k);
}
// Initialize an archived subgraph_info_record from the given KlassSubGraphInfo.
void ArchivedKlassSubGraphInfoRecord::init(KlassSubGraphInfo* info) {
_k = info->klass();
_entry_field_records = NULL;
_subgraph_object_klasses = NULL;
// populate the entry fields
GrowableArray<juint>* entry_fields = info->subgraph_entry_fields();
if (entry_fields != NULL) {
int num_entry_fields = entry_fields->length();
assert(num_entry_fields % 3 == 0, "sanity");
_entry_field_records =
MetaspaceShared::new_ro_array<juint>(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 != NULL) {
int num_subgraphs_klasses = subgraph_object_klasses->length();
_subgraph_object_klasses =
MetaspaceShared::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() != NULL || info.subgraph_entry_fields() != NULL) {
ArchivedKlassSubGraphInfoRecord* record =
(ArchivedKlassSubGraphInfoRecord*)MetaspaceShared::read_only_space_alloc(sizeof(ArchivedKlassSubGraphInfoRecord));
record->init(&info);
unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary(klass);
u4 delta = MetaspaceShared::object_delta_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, value and is_closed_archive flag 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(©);
writer.dump(&_run_time_subgraph_info_table, "subgraphs");
}
void HeapShared::serialize_subgraph_info_table_header(SerializeClosure* soc) {
_run_time_subgraph_info_table.serialize_header(soc);
}
void HeapShared::initialize_from_archived_subgraph(Klass* k) {
if (!open_archive_heap_region_mapped()) {
return; // nothing to do
}
assert(!DumpSharedSpaces, "Should not be called with DumpSharedSpaces");
unsigned int hash = SystemDictionaryShared::hash_for_shared_dictionary(k);
const ArchivedKlassSubGraphInfoRecord* record = _run_time_subgraph_info_table.lookup(k, hash, 0);
// Initialize from archived data. Currently this is done only
// during VM initialization time. No lock is needed.
if (record != NULL) {
Thread* THREAD = Thread::current();
int i;
// Load/link/initialize the klasses of the objects in the subgraph.
// NULL class loader is used.
Array<Klass*>* klasses = record->subgraph_object_klasses();
if (klasses != NULL) {
for (i = 0; i < klasses->length(); i++) {
Klass* obj_k = klasses->at(i);
Klass* resolved_k = SystemDictionary::resolve_or_null(
(obj_k)->name(), THREAD);
if (resolved_k != obj_k) {
assert(!SystemDictionary::is_well_known_klass(resolved_k),
"shared well-known classes must not be replaced by JVMTI ClassFileLoadHook");
ResourceMark rm(THREAD);
log_info(cds, heap)("Failed to load subgraph because %s was not loaded from archive",
resolved_k->external_name());
return;
}
if ((obj_k)->is_instance_klass()) {
InstanceKlass* ik = InstanceKlass::cast(obj_k);
ik->initialize(THREAD);
} else if ((obj_k)->is_objArray_klass()) {
ObjArrayKlass* oak = ObjArrayKlass::cast(obj_k);
oak->initialize(THREAD);
}
}
}
if (HAS_PENDING_EXCEPTION) {
CLEAR_PENDING_EXCEPTION;
// None of the field value will be set if there was an exception.
// The java code will not see any of the archived objects in the
// subgraphs referenced from k in this case.
return;
}
// 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<juint>* entry_field_records = record->entry_field_records();
if (entry_field_records != NULL) {
int efr_len = entry_field_records->length();
assert(efr_len % 3 == 0, "sanity");
for (i = 0; i < efr_len;) {
int field_offset = entry_field_records->at(i);
narrowOop nv = entry_field_records->at(i+1);
int is_closed_archive = entry_field_records->at(i+2);
oop v;
if (is_closed_archive == 0) {
// It's an archived object in the open archive heap regions, not shared.
// The object refereced by the field becomes 'known' by GC from this
// point. All objects in the subgraph reachable from the object are
// also 'known' by GC.
v = materialize_archived_object(nv);
} else {
// Shared object in the closed archive heap regions. Decode directly.
assert(!CompressedOops::is_null(nv), "shared object is null");
v = HeapShared::decode_from_archive(nv);
}
m->obj_field_put(field_offset, v);
i += 3;
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,
k->external_name(), p2i(k));
}
}
}
}
class WalkOopAndArchiveClosure: public BasicOopIterateClosure {
int _level;
bool _is_closed_archive;
bool _record_klasses_only;
KlassSubGraphInfo* _subgraph_info;
oop _orig_referencing_obj;
oop _archived_referencing_obj;
Thread* _thread;
public:
WalkOopAndArchiveClosure(int level,
bool is_closed_archive,
bool record_klasses_only,
KlassSubGraphInfo* subgraph_info,
oop orig, oop archived, TRAPS) :
_level(level), _is_closed_archive(is_closed_archive),
_record_klasses_only(record_klasses_only),
_subgraph_info(subgraph_info),
_orig_referencing_obj(orig), _archived_referencing_obj(archived),
_thread(THREAD) {}
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)) {
assert(!HeapShared::is_archived_object(obj),
"original objects must not point to archived objects");
size_t field_delta = pointer_delta(p, _orig_referencing_obj, sizeof(char));
T* new_p = (T*)(address(_archived_referencing_obj) + field_delta);
Thread* THREAD = _thread;
if (!_record_klasses_only && log_is_enabled(Debug, cds, heap)) {
ResourceMark rm;
log_debug(cds, heap)("(%d) %s[" SIZE_FORMAT "] ==> " PTR_FORMAT " size %d %s", _level,
_orig_referencing_obj->klass()->external_name(), field_delta,
p2i(obj), obj->size() * HeapWordSize, obj->klass()->external_name());
LogTarget(Trace, cds, heap) log;
LogStream out(log);
obj->print_on(&out);
}
oop archived = HeapShared::archive_reachable_objects_from(
_level + 1, _subgraph_info, obj, _is_closed_archive, THREAD);
assert(archived != NULL, "VM should have exited with unarchivable objects for _level > 1");
assert(HeapShared::is_archived_object(archived), "must be");
if (!_record_klasses_only) {
// Update the reference in the archived copy of the referencing object.
log_debug(cds, heap)("(%d) updating oop @[" PTR_FORMAT "] " PTR_FORMAT " ==> " PTR_FORMAT,
_level, p2i(new_p), p2i(obj), p2i(archived));
RawAccess<IS_NOT_NULL>::oop_store(new_p, archived);
}
}
}
};
void HeapShared::check_closed_archive_heap_region_object(InstanceKlass* k,
Thread* THREAD) {
// Check fields in the object
for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
if (!fs.access_flags().is_static()) {
BasicType ft = fs.field_descriptor().field_type();
if (!fs.access_flags().is_final() && is_reference_type(ft)) {
ResourceMark rm(THREAD);
log_warning(cds, heap)(
"Please check reference field in %s instance in closed archive heap region: %s %s",
k->external_name(), (fs.name())->as_C_string(),
(fs.signature())->as_C_string());
}
}
}
}
// (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.
oop HeapShared::archive_reachable_objects_from(int level,
KlassSubGraphInfo* subgraph_info,
oop orig_obj,
bool is_closed_archive,
TRAPS) {
assert(orig_obj != NULL, "must be");
assert(!is_archived_object(orig_obj), "sanity");
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());
vm_exit(1);
}
// 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)) {
log_error(cds, heap)("(%d) Unknown java.lang.Class object is in the archived sub-graph", level);
vm_exit(1);
}
oop archived_obj = find_archived_heap_object(orig_obj);
if (java_lang_String::is_instance(orig_obj) && archived_obj != NULL) {
// To save time, don't walk strings that are already archived. They just contain
// pointers to a type array, whose klass doesn't need to be recorded.
return archived_obj;
}
if (has_been_seen_during_subgraph_recording(orig_obj)) {
// orig_obj has already been archived and traced. Nothing more to do.
return archived_obj;
} else {
set_has_been_seen_during_subgraph_recording(orig_obj);
}
bool record_klasses_only = (archived_obj != NULL);
if (archived_obj == NULL) {
++_num_new_archived_objs;
archived_obj = archive_heap_object(orig_obj, THREAD);
if (archived_obj == NULL) {
// 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 %d, 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 NULL;
} 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.
vm_exit(1);
}
}
}
assert(archived_obj != NULL, "must be");
Klass *orig_k = orig_obj->klass();
Klass *relocated_k = archived_obj->klass();
subgraph_info->add_subgraph_object_klass(orig_k, relocated_k);
WalkOopAndArchiveClosure walker(level, is_closed_archive, record_klasses_only,
subgraph_info, orig_obj, archived_obj, THREAD);
orig_obj->oop_iterate(&walker);
if (is_closed_archive && orig_k->is_instance_klass()) {
check_closed_archive_heap_region_object(InstanceKlass::cast(orig_k), THREAD);
}
return archived_obj;
}
//
// 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
// refererence 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 initialzing 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,
bool is_closed_archive,
TRAPS) {
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);
}
oop af = archive_reachable_objects_from(1, subgraph_info, f,
is_closed_archive, CHECK);
if (af == NULL) {
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, af, is_closed_archive);
log_info(cds, heap)("Archived field %s::%s => " PTR_FORMAT, klass_name, field_name, p2i(af));
}
} 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, NULL, false);
}
}
#ifndef PRODUCT
class VerifySharedOopClosure: public BasicOopIterateClosure {
private:
bool _is_archived;
public:
VerifySharedOopClosure(bool is_archived) : _is_archived(is_archived) {}
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, _is_archived);
}
}
};
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) {
oop archived_obj = find_archived_heap_object(orig_obj);
if (archived_obj == NULL) {
// 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, false);
delete_seen_objects_table();
// Note: we could also verify that all objects reachable from the archived
// copy of orig_obj can only point to archived objects, with:
// init_seen_objects_table();
// verify_reachable_objects_from(archived_obj, true);
// init_seen_objects_table();
// but that's already done in G1HeapVerifier::verify_archive_regions so we
// won't do it here.
}
void HeapShared::verify_reachable_objects_from(oop obj, bool is_archived) {
_num_total_verifications ++;
if (!has_been_seen_during_subgraph_recording(obj)) {
set_has_been_seen_during_subgraph_recording(obj);
if (is_archived) {
assert(is_archived_object(obj), "must be");
assert(find_archived_heap_object(obj) == NULL, "must be");
} else {
assert(!is_archived_object(obj), "must be");
assert(find_archived_heap_object(obj) != NULL, "must be");
}
VerifySharedOopClosure walker(is_archived);
obj->oop_iterate(&walker);
}
}
#endif
HeapShared::SeenObjectsTable* HeapShared::_seen_objects_table = NULL;
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) != NULL;
}
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) {
log_info(cds, heap)("Start recording subgraph(s) for archived fields in %s", class_name);
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 cannot be overloaded");
assert(is_reference_type(fd->field_type()), "can archive only fields that are references");
_found = true;
_offset = fd->offset();
}
}
bool found() { return _found; }
int offset() { return _offset; }
};
void HeapShared::init_subgraph_entry_fields(ArchivableStaticFieldInfo fields[],
int num, Thread* THREAD) {
for (int i = 0; i < num; i++) {
ArchivableStaticFieldInfo* info = &fields[i];
TempNewSymbol klass_name = SymbolTable::new_symbol(info->klass_name);
TempNewSymbol field_name = SymbolTable::new_symbol(info->field_name);
Klass* k = SystemDictionary::resolve_or_null(klass_name, THREAD);
assert(k != NULL && !HAS_PENDING_EXCEPTION, "class must exist");
InstanceKlass* ik = InstanceKlass::cast(k);
assert(InstanceKlass::cast(ik)->is_shared_boot_class(),
"Only support boot classes");
ik->initialize(THREAD);
guarantee(!HAS_PENDING_EXCEPTION, "exception in initialize");
ArchivableStaticFieldFinder finder(ik, field_name);
ik->do_local_static_fields(&finder);
assert(finder.found(), "field must exist");
info->klass = ik;
info->offset = finder.offset();
}
}
void HeapShared::init_subgraph_entry_fields(Thread* THREAD) {
_dump_time_subgraph_info_table = new (ResourceObj::C_HEAP, mtClass)DumpTimeKlassSubGraphInfoTable();
init_subgraph_entry_fields(closed_archive_subgraph_entry_fields,
num_closed_archive_subgraph_entry_fields,
THREAD);
init_subgraph_entry_fields(open_archive_subgraph_entry_fields,
num_open_archive_subgraph_entry_fields,
THREAD);
}
void HeapShared::archive_object_subgraphs(ArchivableStaticFieldInfo fields[],
int num, bool is_closed_archive,
Thread* THREAD) {
_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
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