/*

 * Copyright (c) 2018, 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 "classfile/javaClasses.inline.hpp"

#include "classfile/vmSymbols.hpp"

#include "logging/log.hpp"

#include "logging/logMessage.hpp"

#include "logging/logStream.hpp"

#include "memory/heapShared.hpp"

#include "memory/iterator.inline.hpp"

#include "memory/metadataFactory.hpp"

#include "memory/metaspaceClosure.hpp"

#include "memory/metaspaceShared.hpp"

#include "memory/resourceArea.hpp"

#include "oops/compressedOops.inline.hpp"

#include "oops/oop.inline.hpp"

#if INCLUDE_CDS_JAVA_HEAP

KlassSubGraphInfo* HeapShared::_subgraph_info_list = NULL;

int HeapShared::_num_archived_subgraph_info_records = 0;

Array<ArchivedKlassSubGraphInfoRecord>* HeapShared::_archived_subgraph_info_records = NULL;

// Currently there is only one class mirror (ArchivedModuleGraph) with archived

// sub-graphs.

KlassSubGraphInfo* HeapShared::find_subgraph_info(Klass* k) {

  KlassSubGraphInfo* info = _subgraph_info_list;

  while (info != NULL) {

    if (info->klass() == k) {

      return info;

    }

    info = info->next();

  }

  return NULL;

}

// 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) {

  Klass* relocated_k = MetaspaceShared::get_relocated_klass(k);

  KlassSubGraphInfo* info = find_subgraph_info(relocated_k);

  if (info != NULL) {

    return info;

  }

  info = new KlassSubGraphInfo(relocated_k, _subgraph_info_list);

  _subgraph_info_list = info;

  return info;

}

int HeapShared::num_of_subgraph_infos() {

  int num = 0;

  KlassSubGraphInfo* info = _subgraph_info_list;

  while (info != NULL) {

    num ++;

    info = info->next();

  }

  return num;

}

// 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 == 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));

}

// 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 (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;

  }

  _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();

  _next = NULL;

  _entry_field_records = NULL;

  _subgraph_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 % 2 == 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_klasses = info->subgraph_object_klasses();

  if (subgraph_klasses != NULL) {

    int num_subgraphs_klasses = subgraph_klasses->length();

    _subgraph_klasses =

      MetaspaceShared::new_ro_array<Klass*>(num_subgraphs_klasses);

    for (int i = 0; i < num_subgraphs_klasses; i++) {

      Klass* subgraph_k = subgraph_klasses->at(i);

      if (log_is_enabled(Info, cds, heap)) {

        ResourceMark rm;

        log_info(cds, heap)(

          "Archived object klass (%d): %s in %s sub-graphs",

          i, subgraph_k->external_name(), _k->external_name());

      }

      _subgraph_klasses->at_put(i, subgraph_k);

    }

  }

}

// 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 are 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.

//

// The records are saved in the archive file and reloaded at runtime. Currently

// there is only one class mirror (ArchivedModuleGraph) with archived sub-graphs.

//

// Layout of the archived subgraph info records:

//

// records_size | num_records | records*

// ArchivedKlassSubGraphInfoRecord | entry_fields | subgraph_object_klasses

size_t HeapShared::build_archived_subgraph_info_records(int num_records) {

  // remember the start address

  char* start_p = MetaspaceShared::read_only_space_top();

  // now populate the archived subgraph infos, which will be saved in the

  // archive file

  _archived_subgraph_info_records =

    MetaspaceShared::new_ro_array<ArchivedKlassSubGraphInfoRecord>(num_records);

  KlassSubGraphInfo* info = _subgraph_info_list;

  int i = 0;

  while (info != NULL) {

    assert(i < _archived_subgraph_info_records->length(), "sanity");

    ArchivedKlassSubGraphInfoRecord* record =

      _archived_subgraph_info_records->adr_at(i);

    record->init(info);

    info = info->next();

    i ++;

  }

  // _subgraph_info_list is no longer needed

  delete _subgraph_info_list;

  _subgraph_info_list = NULL;

  char* end_p = MetaspaceShared::read_only_space_top();

  size_t records_size = end_p - start_p;

  return records_size;

}

// Write the subgraph info records in the shared _ro region

void HeapShared::write_archived_subgraph_infos() {

  assert(DumpSharedSpaces, "dump time only");

  Array<intptr_t>* records_header = MetaspaceShared::new_ro_array<intptr_t>(3);

  _num_archived_subgraph_info_records = num_of_subgraph_infos();

  size_t records_size = build_archived_subgraph_info_records(

                             _num_archived_subgraph_info_records);

  // Now write the header information:

  // records_size, num_records, _archived_subgraph_info_records

  assert(records_header != NULL, "sanity");

  intptr_t* p = (intptr_t*)(records_header->data());

  *p = (intptr_t)records_size;

  p ++;

  *p = (intptr_t)_num_archived_subgraph_info_records;

  p ++;

  *p = (intptr_t)_archived_subgraph_info_records;

}

char* HeapShared::read_archived_subgraph_infos(char* buffer) {

  Array<intptr_t>* records_header = (Array<intptr_t>*)buffer;

  intptr_t* p = (intptr_t*)(records_header->data());

  size_t records_size = (size_t)(*p);

  p ++;

  _num_archived_subgraph_info_records = *p;

  p ++;

  _archived_subgraph_info_records =

    (Array<ArchivedKlassSubGraphInfoRecord>*)(*p);

  buffer = (char*)_archived_subgraph_info_records + records_size;

  return buffer;

}

void HeapShared::initialize_from_archived_subgraph(Klass* k) {

  if (!MetaspaceShared::open_archive_heap_region_mapped()) {

    return; // nothing to do

  }

  if (_num_archived_subgraph_info_records == 0) {

    return; // no subgraph info records

  }

  // Initialize from archived data. Currently only ArchivedModuleGraph

  // has archived object subgraphs, which is used during VM initialization

  // time when bootstraping the system modules. No lock is needed.

  Thread* THREAD = Thread::current();

  for (int i = 0; i < _archived_subgraph_info_records->length(); i++) {

    ArchivedKlassSubGraphInfoRecord* record = _archived_subgraph_info_records->adr_at(i);

    if (record->klass() == k) {

      int i;

      // Found the archived subgraph info record for the requesting klass.

      // Load/link/initialize the klasses of the objects in the subgraph.

      // NULL class loader is used.

      Array<Klass*>* klasses = record->subgraph_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) {

            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 % 2 == 0, "sanity");

        for (i = 0; i < efr_len;) {

          int field_offset = entry_field_records->at(i);

          // 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.

          oop v = MetaspaceShared::materialize_archived_object(

            CompressedOops::decode(entry_field_records->at(i+1)));

          m->obj_field_put(field_offset, v);

          i += 2;

        }

      }

      // Done. Java code can see the archived sub-graphs referenced from k's

      // mirror after this point.

      return;

    }

  }

}

class WalkOopAndArchiveClosure: public BasicOopIterateClosure {

  int _level;

  KlassSubGraphInfo* _subgraph_info;

  oop _orig_referencing_obj;

  oop _archived_referencing_obj;

 public:

  WalkOopAndArchiveClosure(int level, KlassSubGraphInfo* subgraph_info,

           oop orig, oop archived) : _level(level),

                                     _subgraph_info(subgraph_info),

                                     _orig_referencing_obj(orig),

                                     _archived_referencing_obj(archived) {}

  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)) {

      // A java.lang.Class instance can not be included in an archived

      // object sub-graph.

      if (java_lang_Class::is_instance(obj)) {

        tty->print("Unknown java.lang.Class object is in the archived sub-graph\n");

        vm_exit(1);

      }

      LogTarget(Debug, cds, heap) log;

      LogStream ls(log);

      outputStream* out = &ls;

      {

        ResourceMark rm;

        log.print("(%d) %s <--- referenced from:  %s",

                  _level, obj->klass()->external_name(),

                  CompressedOops::is_null(_orig_referencing_obj) ?

                         "" : _orig_referencing_obj->klass()->external_name());

        obj->print_on(out);

      }

      if (MetaspaceShared::is_archive_object(obj)) {

        // The current oop is an archived oop, nothing needs to be done

        log.print("--- object is already archived ---");

        return;

      }

      size_t field_delta = pointer_delta(

        p, _orig_referencing_obj, sizeof(char));

      T* new_p = (T*)(address(_archived_referencing_obj) + field_delta);

      oop archived = MetaspaceShared::find_archived_heap_object(obj);

      if (archived != NULL) {

        // There is an archived copy existing, update reference to point

        // to the archived copy

        RawAccess<IS_NOT_NULL>::oop_store(new_p, archived);

        log.print(

          "--- found existing archived copy, store archived " PTR_FORMAT " in " PTR_FORMAT,

          p2i(archived), p2i(new_p));

        return;

      }

      int l = _level + 1;

      Thread* THREAD = Thread::current();

      // Archive the current oop before iterating through its references

      archived = MetaspaceShared::archive_heap_object(obj, THREAD);

      assert(MetaspaceShared::is_archive_object(archived), "must be archived");

      log.print("=== archiving oop " PTR_FORMAT " ==> " PTR_FORMAT,

                 p2i(obj), p2i(archived));

      // Following the references in the current oop and archive any

      // encountered objects during the process

      WalkOopAndArchiveClosure walker(l, _subgraph_info, obj, archived);

      obj->oop_iterate(&walker);

      // Update the reference in the archived copy of the referencing object

      RawAccess<IS_NOT_NULL>::oop_store(new_p, archived);

      log.print("=== store archived " PTR_FORMAT " in " PTR_FORMAT,

                p2i(archived), p2i(new_p));

      // Add the klass to the list of classes that need to be loaded before

      // module system initialization

      Klass *orig_k = obj->klass();

      Klass *relocated_k = archived->klass();

      _subgraph_info->add_subgraph_object_klass(orig_k, relocated_k);

    }

  }

};

//

// 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.

// Currently, only ArchivedModuleGraph class instance (mirror) has archived

// object subgraphs. 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(Klass *k,

                                                             int field_offset,

                                                             BasicType field_type,

                                                             TRAPS) {

  assert(DumpSharedSpaces, "dump time only");

  assert(k->is_instance_klass(), "sanity");

  assert(InstanceKlass::cast(k)->is_shared_boot_class(),

         "must be boot class");

  oop m = k->java_mirror();

  oop archived_m = MetaspaceShared::find_archived_heap_object(m);

  if (CompressedOops::is_null(archived_m)) {

    return;

  }

  if (field_type == T_OBJECT) {

    // obtain k's subGraph Info

    KlassSubGraphInfo* subgraph_info = get_subgraph_info(k);

    // get the object referenced by the field

    oop f = m->obj_field(field_offset);

    if (!CompressedOops::is_null(f)) {

      LogTarget(Debug, cds, heap) log;

      LogStream ls(log);

      outputStream* out = &ls;

      log.print("Start from: ");

      f->print_on(out);

      // get the archived copy of the field referenced object

      oop af = MetaspaceShared::archive_heap_object(f, THREAD);

      if (!MetaspaceShared::is_archive_object(f)) {

        WalkOopAndArchiveClosure walker(1, subgraph_info, f, af);

        f->oop_iterate(&walker);

      }

      // 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);

      Klass *relocated_k = af->klass();

      Klass *orig_k = f->klass();

      subgraph_info->add_subgraph_object_klass(orig_k, relocated_k);

    } 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);

    }

  } else {

    ShouldNotReachHere();

  }

}

#define do_module_object_graph(archive_object_graph_do) \

  archive_object_graph_do(SystemDictionary::ArchivedModuleGraph_klass(), jdk_internal_module_ArchivedModuleGraph::archivedSystemModules_offset(), T_OBJECT, CHECK); \

  archive_object_graph_do(SystemDictionary::ArchivedModuleGraph_klass(), jdk_internal_module_ArchivedModuleGraph::archivedModuleFinder_offset(), T_OBJECT, CHECK); \

void HeapShared::archive_module_graph_objects(Thread* THREAD) {

  do_module_object_graph(archive_reachable_objects_from_static_field);

}

#endif // INCLUDE_CDS_JAVA_HEAP