g1RemSet.hpp 7.2 KB
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/*
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 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
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 * 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.
 *
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 * 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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 *
 */

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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_HPP
#define SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_HPP

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#include "gc_implementation/g1/g1RemSetSummary.hpp"

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

class G1CollectedHeap;
class CardTableModRefBarrierSet;
class ConcurrentG1Refine;

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// 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.

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class G1RemSet: public CHeapObj<mtGC> {
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private:
  G1RemSetSummary _prev_period_summary;
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protected:
  G1CollectedHeap* _g1;
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  size_t _conc_refine_cards;
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  uint n_workers();
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protected:
  enum SomePrivateConstants {
    UpdateRStoMergeSync  = 0,
    MergeRStoDoDirtySync = 1,
    DoDirtySync          = 2,
    LastSync             = 3,

    SeqTask              = 0,
    NumSeqTasks          = 1
  };

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  CardTableModRefBS*     _ct_bs;
  SubTasksDone*          _seq_task;
  G1CollectorPolicy*     _g1p;
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  ConcurrentG1Refine*    _cg1r;
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  size_t*                _cards_scanned;
  size_t                 _total_cards_scanned;
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  // Used for caching the closure that is responsible for scanning
  // references into the collection set.
  OopsInHeapRegionClosure** _cset_rs_update_cl;
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  // Print the given summary info
  virtual void print_summary_info(G1RemSetSummary * summary, const char * header = NULL);
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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();

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  G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs);
  ~G1RemSet();
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  // Invoke "blk->do_oop" on all pointers into the collection set
  // from objects in regions outside the collection set (having
  // invoked "blk->set_region" to set the "from" region correctly
  // beforehand.)
  //
  // Invoke code_root_cl->do_code_blob on the unmarked nmethods
  // on the strong code roots list for each region in the
  // collection set.
  //
  // The "worker_i" param is for the parallel case where the id
  // 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 ignored.
  void oops_into_collection_set_do(OopsInHeapRegionClosure* blk,
                                   CodeBlobToOopClosure* code_root_cl,
                                   int worker_i);
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  // 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.)
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  void prepare_for_oops_into_collection_set_do();
  void cleanup_after_oops_into_collection_set_do();
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  void scanRS(OopsInHeapRegionClosure* oc,
              CodeBlobToOopClosure* code_root_cl,
              int worker_i);

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  void updateRS(DirtyCardQueue* into_cset_dcq, int worker_i);
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  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.
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  template <class T> void write_ref(HeapRegion* from, T* p);
  template <class T> void par_write_ref(HeapRegion* from, T* p, int tid);
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  // 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.
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  void scrub(BitMap* region_bm, BitMap* card_bm);
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  // 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.
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  void scrub_par(BitMap* region_bm, BitMap* card_bm,
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                 uint worker_num, int claim_val);
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  // Refine the card corresponding to "card_ptr".
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  // 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.
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  virtual bool refine_card(jbyte* card_ptr,
                           int worker_i,
                           bool check_for_refs_into_cset);
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  // Print accumulated summary info from the start of the VM.
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  virtual void print_summary_info();
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  // Print accumulated summary info from the last time called.
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  virtual void print_periodic_summary_info(const char* header);
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  // Prepare remembered set for verification.
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  virtual void prepare_for_verify();
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  size_t conc_refine_cards() const {
    return _conc_refine_cards;
  }
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};

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; }
};
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class UpdateRSOopClosure: public ExtendedOopClosure {
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  HeapRegion* _from;
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  G1RemSet* _rs;
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  int _worker_i;
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  template <class T> void do_oop_work(T* p);

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public:
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  UpdateRSOopClosure(G1RemSet* rs, int worker_i = 0) :
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    _from(NULL), _rs(rs), _worker_i(worker_i)
  {}
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  void set_from(HeapRegion* from) {
    assert(from != NULL, "from region must be non-NULL");
    _from = from;
  }

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  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
  virtual void do_oop(oop* p)       { do_oop_work(p); }
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  // Override: this closure is idempotent.
  //  bool idempotent() { return true; }
  bool apply_to_weak_ref_discovered_field() { return true; }
};
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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); }
};
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#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_HPP