--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/gc_implementation/g1/g1EvacFailure.hpp	Fri Dec 23 11:14:18 2011 -0800
@@ -0,0 +1,228 @@
+/*
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#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