johnc@3412: /*
mikael@6198:  * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
johnc@3412:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
johnc@3412:  *
johnc@3412:  * This code is free software; you can redistribute it and/or modify it
johnc@3412:  * under the terms of the GNU General Public License version 2 only, as
johnc@3412:  * published by the Free Software Foundation.
johnc@3412:  *
johnc@3412:  * This code is distributed in the hope that it will be useful, but WITHOUT
johnc@3412:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
johnc@3412:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
johnc@3412:  * version 2 for more details (a copy is included in the LICENSE file that
johnc@3412:  * accompanied this code).
johnc@3412:  *
johnc@3412:  * You should have received a copy of the GNU General Public License version
johnc@3412:  * 2 along with this work; if not, write to the Free Software Foundation,
johnc@3412:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
johnc@3412:  *
johnc@3412:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
johnc@3412:  * or visit www.oracle.com if you need additional information or have any
johnc@3412:  * questions.
johnc@3412:  *
johnc@3412:  */
johnc@3412: 
johnc@3412: #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP
johnc@3412: #define SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP
johnc@3412: 
johnc@3412: #include "gc_implementation/g1/concurrentMark.inline.hpp"
johnc@3412: #include "gc_implementation/g1/dirtyCardQueue.hpp"
johnc@3412: #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
johnc@3412: #include "gc_implementation/g1/g1_globals.hpp"
johnc@3412: #include "gc_implementation/g1/g1OopClosures.inline.hpp"
johnc@3412: #include "gc_implementation/g1/heapRegion.hpp"
johnc@3412: #include "gc_implementation/g1/heapRegionRemSet.hpp"
johnc@3412: #include "utilities/workgroup.hpp"
johnc@3412: 
johnc@3412: // Closures and tasks associated with any self-forwarding pointers
johnc@3412: // installed as a result of an evacuation failure.
johnc@3412: 
johnc@3412: class UpdateRSetDeferred : public OopsInHeapRegionClosure {
johnc@3412: private:
johnc@3412:   G1CollectedHeap* _g1;
johnc@3412:   DirtyCardQueue *_dcq;
mgerdin@5811:   G1SATBCardTableModRefBS* _ct_bs;
johnc@3412: 
johnc@3412: public:
johnc@3412:   UpdateRSetDeferred(G1CollectedHeap* g1, DirtyCardQueue* dcq) :
mgerdin@5811:     _g1(g1), _ct_bs(_g1->g1_barrier_set()), _dcq(dcq) {}
johnc@3412: 
johnc@3412:   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
johnc@3412:   virtual void do_oop(      oop* p) { do_oop_work(p); }
johnc@3412:   template <class T> void do_oop_work(T* p) {
johnc@3412:     assert(_from->is_in_reserved(p), "paranoia");
johnc@3412:     if (!_from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) &&
johnc@3412:         !_from->is_survivor()) {
johnc@3412:       size_t card_index = _ct_bs->index_for(p);
johnc@3412:       if (_ct_bs->mark_card_deferred(card_index)) {
johnc@3412:         _dcq->enqueue((jbyte*)_ct_bs->byte_for_index(card_index));
johnc@3412:       }
johnc@3412:     }
johnc@3412:   }
johnc@3412: };
johnc@3412: 
johnc@3412: class RemoveSelfForwardPtrObjClosure: public ObjectClosure {
johnc@3412: private:
johnc@3412:   G1CollectedHeap* _g1;
johnc@3412:   ConcurrentMark* _cm;
johnc@3412:   HeapRegion* _hr;
tonyp@3416:   size_t _marked_bytes;
johnc@3412:   OopsInHeapRegionClosure *_update_rset_cl;
tonyp@3416:   bool _during_initial_mark;
tonyp@3416:   bool _during_conc_mark;
johnc@3463:   uint _worker_id;
stefank@6992:   HeapWord* _end_of_last_gap;
stefank@6992:   HeapWord* _last_gap_threshold;
stefank@6992:   HeapWord* _last_obj_threshold;
johnc@3463: 
johnc@3412: public:
johnc@3412:   RemoveSelfForwardPtrObjClosure(G1CollectedHeap* g1, ConcurrentMark* cm,
johnc@3412:                                  HeapRegion* hr,
tonyp@3416:                                  OopsInHeapRegionClosure* update_rset_cl,
tonyp@3416:                                  bool during_initial_mark,
johnc@3463:                                  bool during_conc_mark,
johnc@3463:                                  uint worker_id) :
tonyp@3416:     _g1(g1), _cm(cm), _hr(hr), _marked_bytes(0),
johnc@3412:     _update_rset_cl(update_rset_cl),
tonyp@3416:     _during_initial_mark(during_initial_mark),
johnc@3463:     _during_conc_mark(during_conc_mark),
stefank@6992:     _worker_id(worker_id),
stefank@6992:     _end_of_last_gap(hr->bottom()),
stefank@6992:     _last_gap_threshold(hr->bottom()),
stefank@6992:     _last_obj_threshold(hr->bottom()) { }
johnc@3412: 
tonyp@3416:   size_t marked_bytes() { return _marked_bytes; }
johnc@3412: 
johnc@3412:   // <original comment>
johnc@3412:   // The original idea here was to coalesce evacuated and dead objects.
johnc@3412:   // However that caused complications with the block offset table (BOT).
johnc@3412:   // In particular if there were two TLABs, one of them partially refined.
johnc@3412:   // |----- TLAB_1--------|----TLAB_2-~~~(partially refined part)~~~|
johnc@3412:   // The BOT entries of the unrefined part of TLAB_2 point to the start
johnc@3412:   // of TLAB_2. If the last object of the TLAB_1 and the first object
johnc@3412:   // of TLAB_2 are coalesced, then the cards of the unrefined part
johnc@3412:   // would point into middle of the filler object.
johnc@3412:   // The current approach is to not coalesce and leave the BOT contents intact.
johnc@3412:   // </original comment>
johnc@3412:   //
johnc@3412:   // We now reset the BOT when we start the object iteration over the
johnc@3412:   // region and refine its entries for every object we come across. So
johnc@3412:   // the above comment is not really relevant and we should be able
johnc@3412:   // to coalesce dead objects if we want to.
johnc@3412:   void do_object(oop obj) {
johnc@3412:     HeapWord* obj_addr = (HeapWord*) obj;
johnc@3412:     assert(_hr->is_in(obj_addr), "sanity");
johnc@3412:     size_t obj_size = obj->size();
stefank@6992:     HeapWord* obj_end = obj_addr + obj_size;
stefank@6992: 
stefank@6992:     if (_end_of_last_gap != obj_addr) {
stefank@6992:       // there was a gap before obj_addr
stefank@6992:       _last_gap_threshold = _hr->cross_threshold(_end_of_last_gap, obj_addr);
stefank@6992:     }
johnc@3412: 
johnc@3412:     if (obj->is_forwarded() && obj->forwardee() == obj) {
johnc@3412:       // The object failed to move.
tonyp@3416: 
tonyp@3416:       // We consider all objects that we find self-forwarded to be
tonyp@3416:       // live. What we'll do is that we'll update the prev marking
tonyp@3416:       // info so that they are all under PTAMS and explicitly marked.
stefank@6992:       if (!_cm->isPrevMarked(obj)) {
stefank@6992:         _cm->markPrev(obj);
stefank@6992:       }
tonyp@3416:       if (_during_initial_mark) {
tonyp@3416:         // For the next marking info we'll only mark the
tonyp@3416:         // self-forwarded objects explicitly if we are during
tonyp@3416:         // initial-mark (since, normally, we only mark objects pointed
tonyp@3416:         // to by roots if we succeed in copying them). By marking all
tonyp@3416:         // self-forwarded objects we ensure that we mark any that are
tonyp@3416:         // still pointed to be roots. During concurrent marking, and
tonyp@3416:         // after initial-mark, we don't need to mark any objects
tonyp@3416:         // explicitly and all objects in the CSet are considered
tonyp@3416:         // (implicitly) live. So, we won't mark them explicitly and
tonyp@3416:         // we'll leave them over NTAMS.
tonyp@3464:         _cm->grayRoot(obj, obj_size, _worker_id, _hr);
johnc@3412:       }
tonyp@3416:       _marked_bytes += (obj_size * HeapWordSize);
johnc@3412:       obj->set_mark(markOopDesc::prototype());
johnc@3412: 
johnc@3412:       // While we were processing RSet buffers during the collection,
johnc@3412:       // we actually didn't scan any cards on the collection set,
johnc@3412:       // since we didn't want to update remembered sets with entries
johnc@3412:       // that point into the collection set, given that live objects
johnc@3412:       // from the collection set are about to move and such entries
johnc@3412:       // will be stale very soon.
johnc@3412:       // This change also dealt with a reliability issue which
johnc@3412:       // involved scanning a card in the collection set and coming
johnc@3412:       // across an array that was being chunked and looking malformed.
johnc@3412:       // The problem is that, if evacuation fails, we might have
johnc@3412:       // remembered set entries missing given that we skipped cards on
johnc@3412:       // the collection set. So, we'll recreate such entries now.
johnc@3412:       obj->oop_iterate(_update_rset_cl);
johnc@3412:     } else {
stefank@6992: 
johnc@3412:       // The object has been either evacuated or is dead. Fill it with a
johnc@3412:       // dummy object.
stefank@6992:       MemRegion mr(obj_addr, obj_size);
johnc@3412:       CollectedHeap::fill_with_object(mr);
stefank@6992: 
stefank@6992:       // must nuke all dead objects which we skipped when iterating over the region
stefank@6992:       _cm->clearRangePrevBitmap(MemRegion(_end_of_last_gap, obj_end));
johnc@3412:     }
stefank@6992:     _end_of_last_gap = obj_end;
stefank@6992:     _last_obj_threshold = _hr->cross_threshold(obj_addr, obj_end);
johnc@3412:   }
johnc@3412: };
johnc@3412: 
johnc@3412: class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure {
johnc@3412:   G1CollectedHeap* _g1h;
johnc@3412:   ConcurrentMark* _cm;
johnc@3412:   OopsInHeapRegionClosure *_update_rset_cl;
johnc@3463:   uint _worker_id;
johnc@3412: 
johnc@3412: public:
johnc@3412:   RemoveSelfForwardPtrHRClosure(G1CollectedHeap* g1h,
johnc@3463:                                 OopsInHeapRegionClosure* update_rset_cl,
johnc@3463:                                 uint worker_id) :
johnc@3412:     _g1h(g1h), _update_rset_cl(update_rset_cl),
johnc@3463:     _worker_id(worker_id), _cm(_g1h->concurrent_mark()) { }
johnc@3412: 
johnc@3412:   bool doHeapRegion(HeapRegion *hr) {
tonyp@3416:     bool during_initial_mark = _g1h->g1_policy()->during_initial_mark_pause();
tonyp@3416:     bool during_conc_mark = _g1h->mark_in_progress();
tonyp@3416: 
johnc@3412:     assert(!hr->isHumongous(), "sanity");
johnc@3412:     assert(hr->in_collection_set(), "bad CS");
johnc@3412: 
johnc@3412:     if (hr->claimHeapRegion(HeapRegion::ParEvacFailureClaimValue)) {
johnc@3412:       if (hr->evacuation_failed()) {
tonyp@3416:         RemoveSelfForwardPtrObjClosure rspc(_g1h, _cm, hr, _update_rset_cl,
tonyp@3416:                                             during_initial_mark,
johnc@3463:                                             during_conc_mark,
johnc@3463:                                             _worker_id);
tonyp@3416: 
tonyp@3416:         hr->note_self_forwarding_removal_start(during_initial_mark,
tonyp@3416:                                                during_conc_mark);
johnc@3412: 
johnc@3412:         // In the common case (i.e. when there is no evacuation
johnc@3412:         // failure) we make sure that the following is done when
johnc@3412:         // the region is freed so that it is "ready-to-go" when it's
johnc@3412:         // re-allocated. However, when evacuation failure happens, a
johnc@3412:         // region will remain in the heap and might ultimately be added
johnc@3412:         // to a CSet in the future. So we have to be careful here and
johnc@3412:         // make sure the region's RSet is ready for parallel iteration
johnc@3412:         // whenever this might be required in the future.
johnc@3412:         hr->rem_set()->reset_for_par_iteration();
johnc@3412:         hr->reset_bot();
johnc@3412:         _update_rset_cl->set_region(hr);
johnc@3412:         hr->object_iterate(&rspc);
johnc@3412: 
tonyp@3416:         hr->note_self_forwarding_removal_end(during_initial_mark,
tonyp@3416:                                              during_conc_mark,
tonyp@3416:                                              rspc.marked_bytes());
johnc@3412:       }
johnc@3412:     }
johnc@3412:     return false;
johnc@3412:   }
johnc@3412: };
johnc@3412: 
johnc@3412: class G1ParRemoveSelfForwardPtrsTask: public AbstractGangTask {
johnc@3412: protected:
johnc@3412:   G1CollectedHeap* _g1h;
johnc@3412: 
johnc@3412: public:
johnc@3412:   G1ParRemoveSelfForwardPtrsTask(G1CollectedHeap* g1h) :
johnc@3412:     AbstractGangTask("G1 Remove Self-forwarding Pointers"),
johnc@3412:     _g1h(g1h) { }
johnc@3412: 
johnc@3412:   void work(uint worker_id) {
johnc@3412:     UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
johnc@3412:     DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
johnc@3412:     UpdateRSetDeferred deferred_update(_g1h, &dcq);
johnc@3412: 
johnc@3412:     OopsInHeapRegionClosure *update_rset_cl = &deferred_update;
johnc@3412:     if (!G1DeferredRSUpdate) {
johnc@3412:       update_rset_cl = &immediate_update;
johnc@3412:     }
johnc@3412: 
johnc@3463:     RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, update_rset_cl, worker_id);
johnc@3412: 
johnc@3412:     HeapRegion* hr = _g1h->start_cset_region_for_worker(worker_id);
johnc@3412:     _g1h->collection_set_iterate_from(hr, &rsfp_cl);
johnc@3412:   }
johnc@3412: };
johnc@3412: 
johnc@3412: #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1EVACFAILURE_HPP