/*

 * Copyright (c) 2001, 2010, 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.

 *

 */

// A G1RemSet provides ways of iterating over pointers into a selected

// collection set.

class G1CollectedHeap;

class CardTableModRefBarrierSet;

class ConcurrentG1Refine;

// A G1RemSet in which each heap region has a rem set that records the

// external heap references into it.  Uses a mod ref bs to track updates,

// so that they can be used to update the individual region remsets.

class G1RemSet: public CHeapObj {

protected:

  G1CollectedHeap* _g1;

  unsigned _conc_refine_cards;

  size_t n_workers();

protected:

  enum SomePrivateConstants {

    UpdateRStoMergeSync  = 0,

    MergeRStoDoDirtySync = 1,

    DoDirtySync          = 2,

    LastSync             = 3,

    SeqTask              = 0,

    NumSeqTasks          = 1

  };

  CardTableModRefBS*             _ct_bs;

  SubTasksDone*                  _seq_task;

  G1CollectorPolicy* _g1p;

  ConcurrentG1Refine* _cg1r;

  size_t*             _cards_scanned;

  size_t              _total_cards_scanned;

  // Used for caching the closure that is responsible for scanning

  // references into the collection set.

  OopsInHeapRegionClosure** _cset_rs_update_cl;

  // The routine that performs the actual work of refining a dirty

  // card.

  // If check_for_refs_into_refs is true then a true result is returned

  // if the card contains oops that have references into the current

  // collection set.

  bool concurrentRefineOneCard_impl(jbyte* card_ptr, int worker_i,

                                    bool check_for_refs_into_cset);

public:

  // This is called to reset dual hash tables after the gc pause

  // is finished and the initial hash table is no longer being

  // scanned.

  void cleanupHRRS();

  G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs);

  ~G1RemSet();

  // Invoke "blk->do_oop" on all pointers into the CS in objects in regions

  // outside the CS (having invoked "blk->set_region" to set the "from"

  // region correctly beforehand.) The "worker_i" param is for the

  // parallel case where the number of the worker thread calling this

  // function can be helpful in partitioning the work to be done. It

  // should be the same as the "i" passed to the calling thread's

  // work(i) function. In the sequential case this param will be ingored.

  void oops_into_collection_set_do(OopsInHeapRegionClosure* blk,

                                   int worker_i);

  // Prepare for and cleanup after an oops_into_collection_set_do

  // call.  Must call each of these once before and after (in sequential

  // code) any threads call oops_into_collection_set_do.  (This offers an

  // opportunity to sequential setup and teardown of structures needed by a

  // parallel iteration over the CS's RS.)

  void prepare_for_oops_into_collection_set_do();

  void cleanup_after_oops_into_collection_set_do();

  void scanRS(OopsInHeapRegionClosure* oc, int worker_i);

  void updateRS(DirtyCardQueue* into_cset_dcq, int worker_i);

  HeapRegion* calculateStartRegion(int i);

  CardTableModRefBS* ct_bs() { return _ct_bs; }

  size_t cardsScanned() { return _total_cards_scanned; }

  // Record, if necessary, the fact that *p (where "p" is in region "from",

  // which is required to be non-NULL) has changed to a new non-NULL value.

  // Requires "region_bm" and "card_bm" to be bitmaps with 1 bit per region

  // or card, respectively, such that a region or card with a corresponding

  // 0 bit contains no part of any live object.  Eliminates any remembered

  // set entries that correspond to dead heap ranges.

  void scrub(BitMap* region_bm, BitMap* card_bm);

  // Like the above, but assumes is called in parallel: "worker_num" is the

  // parallel thread id of the current thread, and "claim_val" is the

  // value that should be used to claim heap regions.

  void scrub_par(BitMap* region_bm, BitMap* card_bm,

                 int worker_num, int claim_val);

  // Refine the card corresponding to "card_ptr".  If "sts" is non-NULL,

  // join and leave around parts that must be atomic wrt GC.  (NULL means

  // being done at a safepoint.)

  // If check_for_refs_into_cset is true, a true result is returned

  // if the given card contains oops that have references into the

  // current collection set.

  virtual bool concurrentRefineOneCard(jbyte* card_ptr, int worker_i,

                                       bool check_for_refs_into_cset);

  // Print any relevant summary info.

  virtual void print_summary_info();

  // Prepare remembered set for verification.

  virtual void prepare_for_verify();

};

#define G1_REM_SET_LOGGING 0

class CountNonCleanMemRegionClosure: public MemRegionClosure {

  G1CollectedHeap* _g1;

  int _n;

  HeapWord* _start_first;

public:

  CountNonCleanMemRegionClosure(G1CollectedHeap* g1) :

    _g1(g1), _n(0), _start_first(NULL)

  {}

  void do_MemRegion(MemRegion mr);

  int n() { return _n; };

  HeapWord* start_first() { return _start_first; }

};

class UpdateRSOopClosure: public OopClosure {

  HeapRegion* _from;

  G1RemSet* _rs;

  int _worker_i;

  template <class T> void do_oop_work(T* p);

public:

  UpdateRSOopClosure(G1RemSet* rs, int worker_i = 0) :

  void set_from(HeapRegion* from) {

    assert(from != NULL, "from region must be non-NULL");

    _from = from;

  }

  virtual void do_oop(narrowOop* p) { do_oop_work(p); }

  virtual void do_oop(oop* p)       { do_oop_work(p); }

  // Override: this closure is idempotent.

  //  bool idempotent() { return true; }

  bool apply_to_weak_ref_discovered_field() { return true; }

};

class UpdateRSetImmediate: public OopsInHeapRegionClosure {

private:

  G1RemSet* _g1_rem_set;

  template <class T> void do_oop_work(T* p);

public:

  UpdateRSetImmediate(G1RemSet* rs) :

    _g1_rem_set(rs) {}

  virtual void do_oop(narrowOop* p) { do_oop_work(p); }

  virtual void do_oop(      oop* p) { do_oop_work(p); }

};