1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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   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  *
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_HPP
  27 
  28 #include "gc_implementation/g1/g1RemSetSummary.hpp"
  29 
  30 // A G1RemSet provides ways of iterating over pointers into a selected
  31 // collection set.
  32 
  33 class G1CollectedHeap;
  34 class CardTableModRefBarrierSet;
  35 class ConcurrentG1Refine;
  36 
  37 // A G1RemSet in which each heap region has a rem set that records the
  38 // external heap references into it.  Uses a mod ref bs to track updates,
  39 // so that they can be used to update the individual region remsets.
  40 
  41 class G1RemSet: public CHeapObj<mtGC> {
  42 private:
  43   G1RemSetSummary _prev_period_summary;
  44 protected:
  45   G1CollectedHeap* _g1;
  46   size_t _conc_refine_cards;
  47   uint n_workers();
  48 
  49 protected:
  50   enum SomePrivateConstants {
  51     UpdateRStoMergeSync  = 0,
  52     MergeRStoDoDirtySync = 1,
  53     DoDirtySync          = 2,
  54     LastSync             = 3,
  55 
  56     SeqTask              = 0,
  57     NumSeqTasks          = 1
  58   };
  59 
  60   CardTableModRefBS*     _ct_bs;
  61   G1CollectorPolicy*     _g1p;
  62 
  63   ConcurrentG1Refine*    _cg1r;
  64 
  65   size_t*                _cards_scanned;
  66   size_t                 _total_cards_scanned;
  67 
  68   // Used for caching the closure that is responsible for scanning
  69   // references into the collection set.
  70   OopsInHeapRegionClosure** _cset_rs_update_cl;
  71 
  72   // Print the given summary info
  73   virtual void print_summary_info(G1RemSetSummary * summary, const char * header = NULL);
  74 public:
  75   // This is called to reset dual hash tables after the gc pause
  76   // is finished and the initial hash table is no longer being
  77   // scanned.
  78   void cleanupHRRS();
  79 
  80   G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs);
  81   ~G1RemSet();
  82 
  83   // Invoke "blk->do_oop" on all pointers into the collection set
  84   // from objects in regions outside the collection set (having
  85   // invoked "blk->set_region" to set the "from" region correctly
  86   // beforehand.)
  87   //
  88   // Invoke code_root_cl->do_code_blob on the unmarked nmethods
  89   // on the strong code roots list for each region in the
  90   // collection set.
  91   //
  92   // The "worker_i" param is for the parallel case where the id
  93   // of the worker thread calling this function can be helpful in
  94   // partitioning the work to be done. It should be the same as
  95   // the "i" passed to the calling thread's work(i) function.
  96   // In the sequential case this param will be ignored.
  97   void oops_into_collection_set_do(OopsInHeapRegionClosure* blk,
  98                                    CodeBlobClosure* code_root_cl,
  99                                    uint worker_i);
 100 
 101   // Prepare for and cleanup after an oops_into_collection_set_do
 102   // call.  Must call each of these once before and after (in sequential
 103   // code) any threads call oops_into_collection_set_do.  (This offers an
 104   // opportunity to sequential setup and teardown of structures needed by a
 105   // parallel iteration over the CS's RS.)
 106   void prepare_for_oops_into_collection_set_do();
 107   void cleanup_after_oops_into_collection_set_do();
 108 
 109   void scanRS(OopsInHeapRegionClosure* oc,
 110               CodeBlobClosure* code_root_cl,
 111               uint worker_i);
 112 
 113   void updateRS(DirtyCardQueue* into_cset_dcq, uint worker_i);
 114 
 115   CardTableModRefBS* ct_bs() { return _ct_bs; }
 116   size_t cardsScanned() { return _total_cards_scanned; }
 117 
 118   // Record, if necessary, the fact that *p (where "p" is in region "from",
 119   // which is required to be non-NULL) has changed to a new non-NULL value.
 120   template <class T> void write_ref(HeapRegion* from, T* p);
 121   template <class T> void par_write_ref(HeapRegion* from, T* p, int tid);
 122 
 123   // Requires "region_bm" and "card_bm" to be bitmaps with 1 bit per region
 124   // or card, respectively, such that a region or card with a corresponding
 125   // 0 bit contains no part of any live object.  Eliminates any remembered
 126   // set entries that correspond to dead heap ranges.
 127   void scrub(BitMap* region_bm, BitMap* card_bm);
 128 
 129   // Like the above, but assumes is called in parallel: "worker_num" is the
 130   // parallel thread id of the current thread, and "claim_val" is the
 131   // value that should be used to claim heap regions.
 132   void scrub_par(BitMap* region_bm, BitMap* card_bm,
 133                  uint worker_num, int claim_val);
 134 
 135   // Refine the card corresponding to "card_ptr".
 136   // If check_for_refs_into_cset is true, a true result is returned
 137   // if the given card contains oops that have references into the
 138   // current collection set.
 139   virtual bool refine_card(jbyte* card_ptr,
 140                            uint worker_i,
 141                            bool check_for_refs_into_cset);
 142 
 143   // Print accumulated summary info from the start of the VM.
 144   virtual void print_summary_info();
 145 
 146   // Print accumulated summary info from the last time called.
 147   virtual void print_periodic_summary_info(const char* header);
 148 
 149   // Prepare remembered set for verification.
 150   virtual void prepare_for_verify();
 151 
 152   size_t conc_refine_cards() const {
 153     return _conc_refine_cards;
 154   }
 155 };
 156 
 157 class CountNonCleanMemRegionClosure: public MemRegionClosure {
 158   G1CollectedHeap* _g1;
 159   int _n;
 160   HeapWord* _start_first;
 161 public:
 162   CountNonCleanMemRegionClosure(G1CollectedHeap* g1) :
 163     _g1(g1), _n(0), _start_first(NULL)
 164   {}
 165   void do_MemRegion(MemRegion mr);
 166   int n() { return _n; };
 167   HeapWord* start_first() { return _start_first; }
 168 };
 169 
 170 class UpdateRSOopClosure: public ExtendedOopClosure {
 171   HeapRegion* _from;
 172   G1RemSet* _rs;
 173   uint _worker_i;
 174 
 175   template <class T> void do_oop_work(T* p);
 176 
 177 public:
 178   UpdateRSOopClosure(G1RemSet* rs, uint worker_i = 0) :
 179     _from(NULL), _rs(rs), _worker_i(worker_i)
 180   {}
 181 
 182   void set_from(HeapRegion* from) {
 183     assert(from != NULL, "from region must be non-NULL");
 184     _from = from;
 185   }
 186 
 187   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 188   virtual void do_oop(oop* p)       { do_oop_work(p); }
 189 
 190   // Override: this closure is idempotent.
 191   //  bool idempotent() { return true; }
 192   bool apply_to_weak_ref_discovered_field() { return true; }
 193 };
 194 
 195 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_HPP