/*

 * Copyright (c) 2012, 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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 */

#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP

#define SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP

#include "gc_implementation/g1/concurrentMark.inline.hpp"

#include "gc_implementation/g1/dirtyCardQueue.hpp"

#include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

#include "gc_implementation/g1/g1_globals.hpp"

#include "gc_implementation/g1/g1OopClosures.inline.hpp"

#include "gc_implementation/g1/heapRegion.hpp"

#include "gc_implementation/g1/heapRegionRemSet.hpp"

#include "utilities/workgroup.hpp"

// Closures and tasks associated with any self-forwarding pointers

// installed as a result of an evacuation failure.

class UpdateRSetDeferred : public OopsInHeapRegionClosure {

private:

  G1CollectedHeap* _g1;

  DirtyCardQueue *_dcq;

  CardTableModRefBS* _ct_bs;

public:

  UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :

    _g1(g1), _ct_bs((CardTableModRefBS*)_g1->barrier_set()), _dcq(dcq) {}

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

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

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

    assert(_from->is_in_reserved(p), "paranoia");

    if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&

        !_from->is_survivor()) {

      size_t card_index = _ct_bs->index_for(p);

      if (_ct_bs->mark_card_deferred(card_index)) {

        _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));

      }

    }

  }

};

class RemoveSelfForwardPtrObjClosure: public ObjectClosure {

private:

  G1CollectedHeap* _g1;

  ConcurrentMark* _cm;

  HeapRegion* _hr;

  size_t _prev_marked_bytes;

  size_t _next_marked_bytes;

  OopsInHeapRegionClosure *_update_rset_cl;

public:

  RemoveSelfForwardPtrObjClosure(G1CollectedHeap* g1, ConcurrentMark* cm,

                                 HeapRegion* hr,

                                 OopsInHeapRegionClosure* update_rset_cl) :

    _g1(g1), _cm(cm), _hr(hr),

    _update_rset_cl(update_rset_cl),

    _prev_marked_bytes(0), _next_marked_bytes(0) {}

  size_t prev_marked_bytes() { return _prev_marked_bytes; }

  size_t next_marked_bytes() { return _next_marked_bytes; }

  // <original comment>

  // The original idea here was to coalesce evacuated and dead objects.

  // However that caused complications with the block offset table (BOT).

  // In particular if there were two TLABs, one of them partially refined.

  // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|

  // The BOT entries of the unrefined part of TLAB_2 point to the start

  // of TLAB_2. If the last object of the TLAB_1 and the first object

  // of TLAB_2 are coalesced, then the cards of the unrefined part

  // would point into middle of the filler object.

  // The current approach is to not coalesce and leave the BOT contents intact.

  // </original comment>

  //

  // We now reset the BOT when we start the object iteration over the

  // region and refine its entries for every object we come across. So

  // the above comment is not really relevant and we should be able

  // to coalesce dead objects if we want to.

  void do_object(oop obj) {

    HeapWord* obj_addr = (HeapWord*) obj;

    assert(_hr->is_in(obj_addr), "sanity");

    size_t obj_size = obj->size();

    _hr->update_bot_for_object(obj_addr, obj_size);

    if (obj->is_forwarded() && obj->forwardee() == obj) {

      // The object failed to move.

      assert(!_g1->is_obj_dead(obj), "We should not be preserving dead objs.");

      _cm->markPrev(obj);

      assert(_cm->isPrevMarked(obj), "Should be marked!");

      _prev_marked_bytes += (obj_size * HeapWordSize);

      if (_g1->mark_in_progress() && !_g1->is_obj_ill(obj)) {

        _cm->markAndGrayObjectIfNecessary(obj);

      }

      obj->set_mark(markOopDesc::prototype());

      // While we were processing RSet buffers during the collection,

      // we actually didn't scan any cards on the collection set,

      // since we didn't want to update remembered sets with entries

      // that point into the collection set, given that live objects

      // from the collection set are about to move and such entries

      // will be stale very soon.

      // This change also dealt with a reliability issue which

      // involved scanning a card in the collection set and coming

      // across an array that was being chunked and looking malformed.

      // The problem is that, if evacuation fails, we might have

      // remembered set entries missing given that we skipped cards on

      // the collection set. So, we'll recreate such entries now.

      obj->oop_iterate(_update_rset_cl);

      assert(_cm->isPrevMarked(obj), "Should be marked!");

    } else {

      // The object has been either evacuated or is dead. Fill it with a

      // dummy object.

      MemRegion mr((HeapWord*)obj, obj_size);

      CollectedHeap::fill_with_object(mr);

      _cm->clearRangeBothMaps(mr);

    }

  }

};

class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure {

  G1CollectedHeap* _g1h;

  ConcurrentMark* _cm;

  OopsInHeapRegionClosure *_update_rset_cl;

public:

  RemoveSelfForwardPtrHRClosure(G1CollectedHeap* g1h,

                                OopsInHeapRegionClosure* update_rset_cl) :

    _g1h(g1h), _update_rset_cl(update_rset_cl),

    _cm(_g1h->concurrent_mark()) { }

  bool doHeapRegion(HeapRegion *hr) {

    assert(!hr->isHumongous(), "sanity");

    assert(hr->in_collection_set(), "bad CS");

    if (hr->claimHeapRegion(HeapRegion::ParEvacFailureClaimValue)) {

      if (hr->evacuation_failed()) {

        RemoveSelfForwardPtrObjClosure rspc(_g1h, _cm, hr, _update_rset_cl);

        // In the common case (i.e. when there is no evacuation

        // failure) we make sure that the following is done when

        // the region is freed so that it is "ready-to-go" when it's

        // re-allocated. However, when evacuation failure happens, a

        // region will remain in the heap and might ultimately be added

        // to a CSet in the future. So we have to be careful here and

        // make sure the region's RSet is ready for parallel iteration

        // whenever this might be required in the future.

        hr->rem_set()->reset_for_par_iteration();

        hr->reset_bot();

        _update_rset_cl->set_region(hr);

        hr->object_iterate(&rspc);

        // A number of manipulations to make the TAMS for this region

        // be the current top, and the marked bytes be the ones observed

        // in the iteration.

        if (_cm->at_least_one_mark_complete()) {

          // The comments below are the postconditions achieved by the

          // calls.  Note especially the last such condition, which says that

          // the count of marked bytes has been properly restored.

          hr->note_start_of_marking(false);

          // _next_top_at_mark_start == top, _next_marked_bytes == 0

          hr->add_to_marked_bytes(rspc.prev_marked_bytes());

          // _next_marked_bytes == prev_marked_bytes.

          hr->note_end_of_marking();

          // _prev_top_at_mark_start == top(),

          // _prev_marked_bytes == prev_marked_bytes

        }

        // If there is no mark in progress, we modified the _next variables

        // above needlessly, but harmlessly.

        if (_g1h->mark_in_progress()) {

          hr->note_start_of_marking(false);

          // _next_top_at_mark_start == top, _next_marked_bytes == 0

          // _next_marked_bytes == next_marked_bytes.

        }

      }

    }

    return false;

  }

};

class G1ParRemoveSelfForwardPtrsTask: public AbstractGangTask {

protected:

  G1CollectedHeap* _g1h;

public:

  G1ParRemoveSelfForwardPtrsTask(G1CollectedHeap* g1h) :

    AbstractGangTask("G1 Remove Self-forwarding Pointers"),

    _g1h(g1h) { }

  void work(uint worker_id) {

    UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());

    DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());

    UpdateRSetDeferred deferred_update(_g1h, &dcq);

    OopsInHeapRegionClosure *update_rset_cl = &deferred_update;

    if (!G1DeferredRSUpdate) {

      update_rset_cl = &immediate_update;

    }

    RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, update_rset_cl);

    HeapRegion* hr = _g1h->start_cset_region_for_worker(worker_id);

    _g1h->collection_set_iterate_from(hr, &rsfp_cl);

  }

};

#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP