src/hotspot/share/classfile/classLoaderDataShared.cpp

 /*
 * Copyright (c) 2020, 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
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#include "precompiled.hpp"
#include "cds/metaspaceShared.hpp"
#include "classfile/classLoaderData.inline.hpp"
#include "classfile/classLoaderDataShared.hpp"
#include "classfile/moduleEntry.hpp"
#include "classfile/packageEntry.hpp"
#include "classfile/systemDictionary.hpp"
#include "logging/log.hpp"
#include "runtime/handles.inline.hpp"

#if INCLUDE_CDS_JAVA_HEAP

bool ClassLoaderDataShared::_full_module_graph_loaded = false;

class ArchivedClassLoaderData {
  Array<PackageEntry*>* _packages;
  Array<ModuleEntry*>* _modules;

  void assert_valid(ClassLoaderData* loader_data) {
    // loader_data may be null if the boot layer has loaded no modules for the platform or
    // system loaders (e.g., if you create a custom JDK image with only java.base).
    if (loader_data != nullptr) {
      assert(!loader_data->has_class_mirror_holder(),
             "loaders for non-strong hidden classes not supported");
    }
  }
public:
  ArchivedClassLoaderData() : _packages(nullptr), _modules(nullptr) {}

  void iterate_symbols(ClassLoaderData* loader_data, MetaspaceClosure* closure);
  void allocate(ClassLoaderData* loader_data);
  void init_archived_entries(ClassLoaderData* loader_data);

  void serialize(SerializeClosure* f) {
    f->do_ptr(&_packages);
    f->do_ptr(&_modules);
  }

  void restore(ClassLoaderData* loader_data, bool do_entries, bool do_oops);
  void clear_archived_oops();
};

static ArchivedClassLoaderData _archived_boot_loader_data;
static ArchivedClassLoaderData _archived_platform_loader_data;
static ArchivedClassLoaderData _archived_system_loader_data;
static ModuleEntry* _archived_javabase_moduleEntry = nullptr;

void ArchivedClassLoaderData::iterate_symbols(ClassLoaderData* loader_data, MetaspaceClosure* closure) {
  assert(DumpSharedSpaces, "must be");
  assert_valid(loader_data);
  if (loader_data != nullptr) {
    loader_data->packages()->iterate_symbols(closure);
    loader_data->modules() ->iterate_symbols(closure);
  }
}

void ArchivedClassLoaderData::allocate(ClassLoaderData* loader_data) {
  assert(DumpSharedSpaces, "must be");
  assert_valid(loader_data);
  if (loader_data != nullptr) {
    // We can't create hashtables at dump time because the hashcode depends on the
    // address of the Symbols, which may be relocated at runtime due to ASLR.
    // So we store the packages/modules in Arrays. At runtime, we create
    // the hashtables using these arrays.
    _packages = loader_data->packages()->allocate_archived_entries();
    _modules  = loader_data->modules() ->allocate_archived_entries();
  }
}

void ArchivedClassLoaderData::init_archived_entries(ClassLoaderData* loader_data) {
  assert(DumpSharedSpaces, "must be");
  assert_valid(loader_data);
  if (loader_data != nullptr) {
    loader_data->packages()->init_archived_entries(_packages);
    loader_data->modules() ->init_archived_entries(_modules);
  }
}

void ArchivedClassLoaderData::restore(ClassLoaderData* loader_data, bool do_entries, bool do_oops) {
  assert(UseSharedSpaces, "must be");
  assert_valid(loader_data);
  if (_modules != nullptr) { // Could be null if we have archived no modules for platform/system loaders
    ModuleEntryTable* modules = loader_data->modules();
    PackageEntryTable* packages = loader_data->packages();

    MutexLocker m1(Module_lock);
    if (do_entries) {
      modules->load_archived_entries(loader_data, _modules);
      packages->load_archived_entries(_packages);
    }
    if (do_oops) {
      modules->restore_archived_oops(loader_data, _modules);
    }
  }
}

void ArchivedClassLoaderData::clear_archived_oops() {
  assert(UseSharedSpaces, "must be");
  if (_modules != nullptr) {
    for (int i = 0; i < _modules->length(); i++) {
      _modules->at(i)->clear_archived_oops();
    }
  }
}

// ------------------------------

static ClassLoaderData* null_class_loader_data() {
  ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data();
  assert(loader_data != nullptr, "must be");
  return loader_data;
}

static ClassLoaderData* java_platform_loader_data_or_null() {
  return ClassLoaderData::class_loader_data_or_null(SystemDictionary::java_platform_loader());
}

static ClassLoaderData* java_system_loader_data_or_null() {
  return ClassLoaderData::class_loader_data_or_null(SystemDictionary::java_system_loader());
}

void ClassLoaderDataShared::iterate_symbols(MetaspaceClosure* closure) {
  assert(DumpSharedSpaces && MetaspaceShared::use_full_module_graph(), "must be");
  _archived_boot_loader_data.iterate_symbols    (null_class_loader_data(), closure);
  _archived_platform_loader_data.iterate_symbols(java_platform_loader_data_or_null(), closure);
  _archived_system_loader_data.iterate_symbols  (java_system_loader_data_or_null(), closure);
}

void ClassLoaderDataShared::allocate_archived_tables() {
  assert(DumpSharedSpaces && MetaspaceShared::use_full_module_graph(), "must be");
  _archived_boot_loader_data.allocate    (null_class_loader_data());
  _archived_platform_loader_data.allocate(java_platform_loader_data_or_null());
  _archived_system_loader_data.allocate  (java_system_loader_data_or_null());
}

void ClassLoaderDataShared::init_archived_tables() {
  assert(DumpSharedSpaces && MetaspaceShared::use_full_module_graph(), "must be");
  _archived_boot_loader_data.init_archived_entries    (null_class_loader_data());
  _archived_platform_loader_data.init_archived_entries(java_platform_loader_data_or_null());
  _archived_system_loader_data.init_archived_entries  (java_system_loader_data_or_null());
  _archived_javabase_moduleEntry = ModuleEntry::get_archived_entry(ModuleEntryTable::javabase_moduleEntry());
}

void ClassLoaderDataShared::serialize(SerializeClosure* f) {
  _archived_boot_loader_data.serialize(f);
  _archived_platform_loader_data.serialize(f);
  _archived_system_loader_data.serialize(f);
  f->do_ptr(&_archived_javabase_moduleEntry);

  if (f->reading() && MetaspaceShared::use_full_module_graph()) {
    // Must be done before ClassLoader::create_javabase()
    _archived_boot_loader_data.restore(null_class_loader_data(), true, false);
    ModuleEntryTable::set_javabase_moduleEntry(_archived_javabase_moduleEntry);
    log_info(cds)("use_full_module_graph = true; java.base = " INTPTR_FORMAT,
                  p2i(_archived_javabase_moduleEntry));
  }
}

void ClassLoaderDataShared::clear_archived_oops() {
  assert(UseSharedSpaces && !MetaspaceShared::use_full_module_graph(), "must be");
  _archived_boot_loader_data.clear_archived_oops();
  _archived_platform_loader_data.clear_archived_oops();
  _archived_system_loader_data.clear_archived_oops();
}

oop ClassLoaderDataShared::restore_archived_oops_for_null_class_loader_data() {
  assert(UseSharedSpaces && MetaspaceShared::use_full_module_graph(), "must be");
  _archived_boot_loader_data.restore(null_class_loader_data(), false, true);
  return _archived_javabase_moduleEntry->module();
}

void ClassLoaderDataShared::restore_java_platform_loader_from_archive(ClassLoaderData* loader_data) {
  assert(UseSharedSpaces && MetaspaceShared::use_full_module_graph(), "must be");
  _archived_platform_loader_data.restore(loader_data, true, true);
}

void ClassLoaderDataShared::restore_java_system_loader_from_archive(ClassLoaderData* loader_data) {
  assert(UseSharedSpaces && MetaspaceShared::use_full_module_graph(), "must be");
  _archived_system_loader_data.restore(loader_data, true, true);
  _full_module_graph_loaded = true;
}

#endif // INCLUDE_CDS_JAVA_HEAP