/*

 * Copyright (c) 2001, 2008, 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.

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 */

// 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;

class GenRemSet: public CHeapObj {

  friend class Generation;

  BarrierSet* _bs;

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; }

  // 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* gen, bool clear_perm) = 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. The parameter

  // younger indicates if the same should be done for younger generations

  // as well. The parameter perm indicates if the same should be done for

  // perm gen as well.

  virtual void invalidate_or_clear(Generation* gen, bool younger, bool perm) = 0;

};