/*

 * Copyright 2003-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

#include "incls/_precompiled.incl"

#include "incls/_compactingPermGenGen.cpp.incl"

// An ObjectClosure helper: Recursively adjust all pointers in an object

// and all objects by referenced it. Clear marks on objects in order to

// prevent visiting any object twice. This helper is used when the

// RedefineClasses() API has been called.

class AdjustSharedObjectClosure : public ObjectClosure {

public:

  void do_object(oop obj) {

    if (obj->is_shared_readwrite()) {

      if (obj->mark()->is_marked()) {

        obj->init_mark();         // Don't revisit this object.

        obj->adjust_pointers();   // Adjust this object's references.

      }

    }

  }

};

// An OopClosure helper: Recursively adjust all pointers in an object

// and all objects by referenced it. Clear marks on objects in order

// to prevent visiting any object twice.

class RecursiveAdjustSharedObjectClosure : public OopClosure {

 protected:

  template <class T> inline void do_oop_work(T* p) {

    oop obj = oopDesc::load_decode_heap_oop_not_null(p);

    if (obj->is_shared_readwrite()) {

      if (obj->mark()->is_marked()) {

        obj->init_mark();         // Don't revisit this object.

        obj->oop_iterate(this);   // Recurse - adjust objects referenced.

        obj->adjust_pointers();   // Adjust this object's references.

        // Special case: if a class has a read-only constant pool,

        // then the read-write objects referenced by the pool must

        // have their marks reset.

        if (obj->klass() == Universe::instanceKlassKlassObj()) {

          instanceKlass* ik = instanceKlass::cast((klassOop)obj);

          constantPoolOop cp = ik->constants();

          if (cp->is_shared_readonly()) {

            cp->oop_iterate(this);

          }

        }

      }

    }

  }

 public:

  virtual void do_oop(oop* p)       { RecursiveAdjustSharedObjectClosure::do_oop_work(p); }

  virtual void do_oop(narrowOop* p) { RecursiveAdjustSharedObjectClosure::do_oop_work(p); }

};

// We need to go through all placeholders in the system dictionary and

// try to resolve them into shared classes. Other threads might be in

// the process of loading a shared class and have strong roots on

// their stack to the class without having added the class to the

// dictionary yet. This means the class will be marked during phase 1

// but will not be unmarked during the application of the

// RecursiveAdjustSharedObjectClosure to the SystemDictionary. Note

// that we must not call find_shared_class with non-read-only symbols

// as doing so can cause hash codes to be computed, destroying

// forwarding pointers.

class TraversePlaceholdersClosure : public OopClosure {

 protected:

  template <class T> inline void do_oop_work(T* p) {

    oop obj = oopDesc::load_decode_heap_oop_not_null(p);

    if (obj->klass() == Universe::symbolKlassObj() &&

        obj->is_shared_readonly()) {

      symbolHandle sym((symbolOop) obj);

      oop k = SystemDictionary::find_shared_class(sym);

      if (k != NULL) {

        RecursiveAdjustSharedObjectClosure clo;

        clo.do_oop(&k);

      }

    }

  }

 public:

  virtual void do_oop(oop* p)       { TraversePlaceholdersClosure::do_oop_work(p); }

  virtual void do_oop(narrowOop* p) { TraversePlaceholdersClosure::do_oop_work(p); }

};

void CompactingPermGenGen::initialize_performance_counters() {

  const char* gen_name = "perm";

  // Generation Counters - generation 2, 1 subspace

  _gen_counters = new GenerationCounters(gen_name, 2, 1, &_virtual_space);

  _space_counters = new CSpaceCounters(gen_name, 0,

                                       _virtual_space.reserved_size(),

                                      _the_space, _gen_counters);

}

void CompactingPermGenGen::update_counters() {

  if (UsePerfData) {

    _space_counters->update_all();

    _gen_counters->update_all();

  }

}

CompactingPermGenGen::CompactingPermGenGen(ReservedSpace rs,

                                           ReservedSpace shared_rs,

                                           size_t initial_byte_size,

                                           int level, GenRemSet* remset,

                                           ContiguousSpace* space,

                                           PermanentGenerationSpec* spec_) :

  OneContigSpaceCardGeneration(rs, initial_byte_size, MinPermHeapExpansion,

                               level, remset, space) {

  set_spec(spec_);

  if (!UseSharedSpaces && !DumpSharedSpaces) {

    spec()->disable_sharing();

  }

  // Break virtual space into address ranges for all spaces.

  if (spec()->enable_shared_spaces()) {

    shared_end = (HeapWord*)(shared_rs.base() + shared_rs.size());

      misccode_end = shared_end;

      misccode_bottom = misccode_end - heap_word_size(spec()->misc_code_size());

      miscdata_end = misccode_bottom;

      miscdata_bottom = miscdata_end - heap_word_size(spec()->misc_data_size());

      readwrite_end = miscdata_bottom;

      readwrite_bottom =

        readwrite_end - heap_word_size(spec()->read_write_size());

      readonly_end = readwrite_bottom;

      readonly_bottom =

        readonly_end - heap_word_size(spec()->read_only_size());

    shared_bottom = readonly_bottom;

    unshared_end = shared_bottom;

    assert((char*)shared_bottom == shared_rs.base(), "shared space mismatch");

  } else {

    shared_end = (HeapWord*)(rs.base() + rs.size());

      misccode_end = shared_end;

      misccode_bottom = shared_end;

      miscdata_end = shared_end;

      miscdata_bottom = shared_end;

      readwrite_end = shared_end;

      readwrite_bottom = shared_end;

      readonly_end = shared_end;

      readonly_bottom = shared_end;

    shared_bottom = shared_end;

    unshared_end = shared_bottom;

  }

  unshared_bottom = (HeapWord*) rs.base();

  // Verify shared and unshared spaces adjacent.

  assert((char*)shared_bottom == rs.base()+rs.size(), "shared space mismatch");

  assert(unshared_end > unshared_bottom, "shared space mismatch");

  // Split reserved memory into pieces.

  ReservedSpace ro_rs   = shared_rs.first_part(spec()->read_only_size(),

                                              UseSharedSpaces);

  ReservedSpace tmp_rs1 = shared_rs.last_part(spec()->read_only_size());

  ReservedSpace rw_rs   = tmp_rs1.first_part(spec()->read_write_size(),

                                             UseSharedSpaces);

  ReservedSpace tmp_rs2 = tmp_rs1.last_part(spec()->read_write_size());

  ReservedSpace md_rs   = tmp_rs2.first_part(spec()->misc_data_size(),

                                             UseSharedSpaces);

  ReservedSpace mc_rs   = tmp_rs2.last_part(spec()->misc_data_size());

  _shared_space_size = spec()->read_only_size()

                     + spec()->read_write_size()

                     + spec()->misc_data_size()

                     + spec()->misc_code_size();

  // Allocate the unshared (default) space.

  _the_space = new ContigPermSpace(_bts,

               MemRegion(unshared_bottom, heap_word_size(initial_byte_size)));

  if (_the_space == NULL)

    vm_exit_during_initialization("Could not allocate an unshared"

                                  " CompactingPermGen Space");

  // Allocate shared spaces

  if (spec()->enable_shared_spaces()) {

    // If mapping a shared file, the space is not committed, don't

    // mangle.

    NOT_PRODUCT(bool old_ZapUnusedHeapArea = ZapUnusedHeapArea;)

    NOT_PRODUCT(if (UseSharedSpaces) ZapUnusedHeapArea = false;)

    // Commit the memory behind the shared spaces if dumping (not

    // mapping).

    if (DumpSharedSpaces) {

      _ro_vs.initialize(ro_rs, spec()->read_only_size());

      _rw_vs.initialize(rw_rs, spec()->read_write_size());

      _md_vs.initialize(md_rs, spec()->misc_data_size());

      _mc_vs.initialize(mc_rs, spec()->misc_code_size());

    }

    // Allocate the shared spaces.

    _ro_bts = new BlockOffsetSharedArray(

                  MemRegion(readonly_bottom,

                            heap_word_size(spec()->read_only_size())),

                  heap_word_size(spec()->read_only_size()));

    _ro_space = new OffsetTableContigSpace(_ro_bts,

                  MemRegion(readonly_bottom, readonly_end));

    _rw_bts = new BlockOffsetSharedArray(

                  MemRegion(readwrite_bottom,

                            heap_word_size(spec()->read_write_size())),

                  heap_word_size(spec()->read_write_size()));

    _rw_space = new OffsetTableContigSpace(_rw_bts,

                  MemRegion(readwrite_bottom, readwrite_end));

    // Restore mangling flag.

    NOT_PRODUCT(ZapUnusedHeapArea = old_ZapUnusedHeapArea;)

    if (_ro_space == NULL || _rw_space == NULL)

      vm_exit_during_initialization("Could not allocate a shared space");

    // Cover both shared spaces entirely with cards.

    _rs->resize_covered_region(MemRegion(readonly_bottom, readwrite_end));

    if (UseSharedSpaces) {

      // Map in the regions in the shared file.

      FileMapInfo* mapinfo = FileMapInfo::current_info();

      size_t image_alignment = mapinfo->alignment();

      CollectedHeap* ch = Universe::heap();

      if ((!mapinfo->map_space(ro, ro_rs, _ro_space)) ||

          (!mapinfo->map_space(rw, rw_rs, _rw_space)) ||

          (!mapinfo->map_space(md, md_rs, NULL))      ||

          (!mapinfo->map_space(mc, mc_rs, NULL))      ||

          // check the alignment constraints

          (ch == NULL || ch->kind() != CollectedHeap::GenCollectedHeap ||

           image_alignment !=

           ((GenCollectedHeap*)ch)->gen_policy()->max_alignment())) {

        // Base addresses didn't match; skip sharing, but continue

        shared_rs.release();

        spec()->disable_sharing();

        // If -Xshare:on is specified, print out the error message and exit VM,

        // otherwise, set UseSharedSpaces to false and continue.

        if (RequireSharedSpaces) {

          vm_exit_during_initialization("Unable to use shared archive.", NULL);

        } else {

          FLAG_SET_DEFAULT(UseSharedSpaces, false);

        }

        // Note: freeing the block offset array objects does not

        // currently free up the underlying storage.

        delete _ro_bts;

        _ro_bts = NULL;

        delete _ro_space;

        _ro_space = NULL;

        delete _rw_bts;

        _rw_bts = NULL;

        delete _rw_space;

        _rw_space = NULL;

        shared_end = (HeapWord*)(rs.base() + rs.size());

        _rs->resize_covered_region(MemRegion(shared_bottom, shared_bottom));

      }

    }

    // Reserved region includes shared spaces for oop.is_in_reserved().

    _reserved.set_end(shared_end);

  } else {

    _ro_space = NULL;

    _rw_space = NULL;

  }

}

// Do a complete scan of the shared read write space to catch all

// objects which contain references to any younger generation.  Forward

// the pointers.  Avoid space_iterate, as actually visiting all the

// objects in the space will page in more objects than we need.

// Instead, use the system dictionary as strong roots into the read

// write space.

//

// If a RedefineClasses() call has been made, then we have to iterate

// over the entire shared read-write space in order to find all the

// objects that need to be forwarded. For example, it is possible for

// an nmethod to be found and marked in GC phase-1 only for the nmethod

// to be freed by the time we reach GC phase-3. The underlying method

// is still marked, but we can't (easily) find it in GC phase-3 so we

// blow up in GC phase-4. With RedefineClasses() we want replaced code

// (EMCP or obsolete) to go away (i.e., be collectible) once it is no

// longer being executed by any thread so we keep minimal attachments

// to the replaced code. However, we can't guarantee when those EMCP

// or obsolete methods will be collected so they may still be out there

// even after we've severed our minimal attachments.

void CompactingPermGenGen::pre_adjust_pointers() {

  if (spec()->enable_shared_spaces()) {

    if (JvmtiExport::has_redefined_a_class()) {

      // RedefineClasses() requires a brute force approach

      AdjustSharedObjectClosure blk;

      rw_space()->object_iterate(&blk);

    } else {

      RecursiveAdjustSharedObjectClosure blk;

      Universe::oops_do(&blk);

      StringTable::oops_do(&blk);

      SystemDictionary::always_strong_classes_do(&blk);

      TraversePlaceholdersClosure tpc;

      SystemDictionary::placeholders_do(&tpc);

    }

  }

}

#ifdef ASSERT

class VerifyMarksClearedClosure : public ObjectClosure {

public:

  void do_object(oop obj) {

    assert(SharedSkipVerify || !obj->mark()->is_marked(),

           "Shared oop still marked?");

  }

};

#endif

void CompactingPermGenGen::post_compact() {

#ifdef ASSERT

  if (!SharedSkipVerify && spec()->enable_shared_spaces()) {

    VerifyMarksClearedClosure blk;

    rw_space()->object_iterate(&blk);

  }

#endif

}

// Do not use in time-critical operations due to the possibility of paging

// in otherwise untouched or previously unread portions of the perm gen,

// for instance, the shared spaces. NOTE: Because CompactingPermGenGen

// derives from OneContigSpaceCardGeneration which is supposed to have a

// single space, and does not override its object_iterate() method,

// object iteration via that interface does not look at the objects in

// the shared spaces when using CDS. This should be fixed; see CR 6897798.

void CompactingPermGenGen::space_iterate(SpaceClosure* blk, bool usedOnly) {

  OneContigSpaceCardGeneration::space_iterate(blk, usedOnly);

  if (spec()->enable_shared_spaces()) {

    // Making the rw_space walkable will page in the entire space, and

    // is to be avoided in the case of time-critical operations.

    // However, this is required for Verify and heap dump operations.

    blk->do_space(ro_space());

    blk->do_space(rw_space());

  }

}

void CompactingPermGenGen::print_on(outputStream* st) const {

  OneContigSpaceCardGeneration::print_on(st);

  if (spec()->enable_shared_spaces()) {

    st->print("    ro");

    ro_space()->print_on(st);

    st->print("    rw");

    rw_space()->print_on(st);

  } else {

    st->print_cr("No shared spaces configured.");

  }

}

// References from the perm gen to the younger generation objects may

// occur in static fields in Java classes or in constant pool references

// to String objects.

void CompactingPermGenGen::younger_refs_iterate(OopsInGenClosure* blk) {

  OneContigSpaceCardGeneration::younger_refs_iterate(blk);

  if (spec()->enable_shared_spaces()) {

    blk->set_generation(this);

    // ro_space has no younger gen refs.

    _rs->younger_refs_in_space_iterate(rw_space(), blk);

    blk->reset_generation();

  }

}

// Shared spaces are addressed in pre_adjust_pointers.

void CompactingPermGenGen::adjust_pointers() {

  the_space()->adjust_pointers();

}

void CompactingPermGenGen::compact() {

  the_space()->compact();

}

size_t CompactingPermGenGen::contiguous_available() const {

  // Don't include shared spaces.

  return OneContigSpaceCardGeneration::contiguous_available()

         - _shared_space_size;

}

size_t CompactingPermGenGen::max_capacity() const {

  // Don't include shared spaces.

  assert(UseSharedSpaces || (_shared_space_size == 0),

    "If not used, the size of shared spaces should be 0");

  return OneContigSpaceCardGeneration::max_capacity()

          - _shared_space_size;

}

// No young generation references, clear this generation's main space's

// card table entries.  Do NOT clear the card table entries for the

// read-only space (always clear) or the read-write space (valuable

// information).

void CompactingPermGenGen::clear_remembered_set() {

  _rs->clear(MemRegion(the_space()->bottom(), the_space()->end()));

}

// Objects in this generation's main space may have moved, invalidate

// that space's cards.  Do NOT invalidate the card table entries for the

// read-only or read-write spaces, as those objects never move.

void CompactingPermGenGen::invalidate_remembered_set() {

  _rs->invalidate(used_region());

}

void CompactingPermGenGen::verify(bool allow_dirty) {

  the_space()->verify(allow_dirty);

  if (!SharedSkipVerify && spec()->enable_shared_spaces()) {

    ro_space()->verify(allow_dirty);

    rw_space()->verify(allow_dirty);

  }

}

HeapWord* CompactingPermGenGen::unshared_bottom;

HeapWord* CompactingPermGenGen::unshared_end;

HeapWord* CompactingPermGenGen::shared_bottom;

HeapWord* CompactingPermGenGen::shared_end;

HeapWord* CompactingPermGenGen::readonly_bottom;

HeapWord* CompactingPermGenGen::readonly_end;

HeapWord* CompactingPermGenGen::readwrite_bottom;

HeapWord* CompactingPermGenGen::readwrite_end;

HeapWord* CompactingPermGenGen::miscdata_bottom;

HeapWord* CompactingPermGenGen::miscdata_end;

HeapWord* CompactingPermGenGen::misccode_bottom;

HeapWord* CompactingPermGenGen::misccode_end;

// JVM/TI RedefineClasses() support:

bool CompactingPermGenGen::remap_shared_readonly_as_readwrite() {

  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");

  if (UseSharedSpaces) {

    // remap the shared readonly space to shared readwrite, private

    FileMapInfo* mapinfo = FileMapInfo::current_info();

    if (!mapinfo->remap_shared_readonly_as_readwrite()) {

      return false;

    }

  }

  return true;

}

void** CompactingPermGenGen::_vtbl_list;