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 /*

  * Copyright (c) 2001, 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_MEMORY_GENREMSET_HPP

 #define SHARE_VM_MEMORY_GENREMSET_HPP

 #include "oops/oop.hpp"

 // A GenRemSet provides ways of iterating over pointers accross generations.

 // (This is especially useful for older-to-younger.)

 class Generation;

 class BarrierSet;

 class OopsInGenClosure;

 class CardTableRS;

 // Helper to remember modified oops in all klasses.

 class KlassRemSet {

   bool _accumulate_modified_oops;

  public:

   KlassRemSet() : _accumulate_modified_oops(false) {}

   void set_accumulate_modified_oops(bool value) { _accumulate_modified_oops = value; }

   bool accumulate_modified_oops() { return _accumulate_modified_oops; }

   bool mod_union_is_clear();

   void clear_mod_union();

 };

 class GenRemSet: public CHeapObj<mtGC> {

   friend class Generation;

   BarrierSet* _bs;

   KlassRemSet _klass_rem_set;

 public:

   enum Name {

     CardTable,

     Other

   };

   GenRemSet(BarrierSet * bs) : _bs(bs) {}

   GenRemSet() : _bs(NULL) {}

   virtual Name rs_kind() = 0;

   // These are for dynamic downcasts.  Unfortunately that it names the

   // possible subtypes (but not that they are subtypes!)  Return NULL if

   // the cast is invalide.

   virtual CardTableRS* as_CardTableRS() { return NULL; }

   // Return the barrier set associated with "this."

   BarrierSet* bs() { return _bs; }

   // Set the barrier set.

   void set_bs(BarrierSet* bs) { _bs = bs; }

   KlassRemSet* klass_rem_set() { return &_klass_rem_set; }

   // Do any (sequential) processing necessary to prepare for (possibly

   // "parallel", if that arg is true) calls to younger_refs_iterate.

   virtual void prepare_for_younger_refs_iterate(bool parallel) = 0;

   // Apply the "do_oop" method of "blk" to (exactly) all oop locations

   //  1) that are in objects allocated in "g" at the time of the last call

   //     to "save_Marks", and

   //  2) that point to objects in younger generations.

   virtual void younger_refs_iterate(Generation* g, OopsInGenClosure* blk) = 0;

   virtual void younger_refs_in_space_iterate(Space* sp,

                                              OopsInGenClosure* cl) = 0;

   // This method is used to notify the remembered set that "new_val" has

   // been written into "field" by the garbage collector.

   void write_ref_field_gc(void* field, oop new_val);

 protected:

   virtual void write_ref_field_gc_work(void* field, oop new_val) = 0;

 public:

   // A version of the above suitable for use by parallel collectors.

   virtual void write_ref_field_gc_par(void* field, oop new_val) = 0;

   // Resize one of the regions covered by the remembered set.

   virtual void resize_covered_region(MemRegion new_region) = 0;

   // If the rem set imposes any alignment restrictions on boundaries

   // within the heap, this function tells whether they are met.

   virtual bool is_aligned(HeapWord* addr) = 0;

   // If the RS (or BS) imposes an aligment constraint on maximum heap size.

   // (This must be static, and dispatch on "nm", because it is called

   // before an RS is created.)

   static uintx max_alignment_constraint(Name nm);

   virtual void verify() = 0;

   // Verify that the remembered set has no entries for

   // the heap interval denoted by mr.  If there are any

   // alignment constraints on the remembered set, only the

   // part of the region that is aligned is checked.

   //

   //   alignment boundaries

   //   +--------+-------+--------+-------+

   //         [ region mr              )

   //            [ part checked   )

   virtual void verify_aligned_region_empty(MemRegion mr) = 0;

   // If appropriate, print some information about the remset on "tty".

   virtual void print() {}

   // Informs the RS that the given memregion contains no references to

   // younger generations.

   virtual void clear(MemRegion mr) = 0;

   // Informs the RS that there are no references to generations

   // younger than gen from generations gen and older.

   // The parameter clear_perm indicates if the perm_gen's

   // remembered set should also be processed/cleared.

   virtual void clear_into_younger(Generation* old_gen) = 0;

   // Informs the RS that refs in the given "mr" may have changed

   // arbitrarily, and therefore may contain old-to-young pointers.

   // If "whole heap" is true, then this invalidation is part of an

   // invalidation of the whole heap, which an implementation might

   // handle differently than that of a sub-part of the heap.

   virtual void invalidate(MemRegion mr, bool whole_heap = false) = 0;

   // Informs the RS that refs in this generation

   // may have changed arbitrarily, and therefore may contain

   // old-to-young pointers in arbitrary locations.

   virtual void invalidate_or_clear(Generation* old_gen) = 0;

 };

 #endif // SHARE_VM_MEMORY_GENREMSET_HPP