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