1 /*
   2  * Copyright (c) 2018, 2019, Red Hat, Inc. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHMARKINGCONTEXT_HPP
  26 #define SHARE_GC_SHENANDOAH_SHENANDOAHMARKINGCONTEXT_HPP
  27 
  28 #include "gc/shared/markBitMap.hpp"
  29 #include "memory/allocation.hpp"
  30 #include "memory/memRegion.hpp"
  31 #include "oops/oopsHierarchy.hpp"
  32 
  33 /**
  34  * Encapsulate a marking bitmap with the top-at-mark-start and top-bitmaps array.
  35  */
  36 class ShenandoahMarkingContext : public CHeapObj<mtGC> {
  37 private:
  38   MarkBitMap _mark_bit_map;
  39 
  40   HeapWord** const _top_bitmaps;
  41   HeapWord** const _top_at_mark_starts_base;
  42   HeapWord** const _top_at_mark_starts;
  43 
  44   ShenandoahSharedFlag _is_complete;
  45 
  46 public:
  47   ShenandoahMarkingContext(MemRegion heap_region, MemRegion bitmap_region, size_t num_regions);
  48 
  49   /*
  50    * Marks the object. Returns true if the object has not been marked before and has
  51    * been marked by this thread. Returns false if the object has already been marked,
  52    * or if a competing thread succeeded in marking this object.
  53    */
  54   inline bool mark(oop obj);
  55 
  56   inline bool is_marked(oop obj) const;
  57 
  58   inline bool allocated_after_mark_start(HeapWord* addr) const;
  59 
  60   inline MarkBitMap* mark_bit_map();
  61 
  62   HeapWord* top_at_mark_start(ShenandoahHeapRegion* r) const;
  63   void capture_top_at_mark_start(ShenandoahHeapRegion* r);
  64   void reset_top_at_mark_start(ShenandoahHeapRegion* r);
  65   void initialize_top_at_mark_start(ShenandoahHeapRegion* r);
  66 
  67   void reset_top_bitmap(ShenandoahHeapRegion *r);
  68   void clear_bitmap(ShenandoahHeapRegion *r);
  69 
  70   bool is_bitmap_clear() const;
  71   bool is_bitmap_clear_range(HeapWord* start, HeapWord* end) const;
  72 
  73   bool is_complete();
  74   void mark_complete();
  75   void mark_incomplete();
  76 
  77 };
  78 
  79 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHMARKINGCONTEXT_HPP