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).
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  24 
  25 #ifndef SHARE_VM_GC_G1_G1REMSET_HPP
  26 #define SHARE_VM_GC_G1_G1REMSET_HPP
  27 
  28 #include "gc/g1/dirtyCardQueue.hpp"
  29 #include "gc/g1/g1CardLiveData.hpp"
  30 #include "gc/g1/g1RemSetSummary.hpp"
  31 #include "gc/g1/heapRegion.hpp"
  32 #include "memory/allocation.hpp"
  33 #include "memory/iterator.hpp"
  34 
  35 // A G1RemSet provides ways of iterating over pointers into a selected
  36 // collection set.
  37 
  38 class BitMap;
  39 class CardTableModRefBS;
  40 class G1BlockOffsetTable;
  41 class CodeBlobClosure;
  42 class G1CollectedHeap;
  43 class G1HotCardCache;
  44 class G1RemSetScanState;
  45 class G1ParScanThreadState;
  46 class G1Policy;
  47 class G1SATBCardTableModRefBS;
  48 class G1ScanObjsDuringScanRSClosure;
  49 class G1ScanObjsDuringUpdateRSClosure;
  50 class HeapRegionClaimer;
  51 
  52 // A G1RemSet in which each heap region has a rem set that records the
  53 // external heap references into it.  Uses a mod ref bs to track updates,
  54 // so that they can be used to update the individual region remsets.
  55 class G1RemSet: public CHeapObj<mtGC> {
  56 private:
  57   G1RemSetScanState* _scan_state;
  58   G1CardLiveData _card_live_data;
  59 
  60   G1RemSetSummary _prev_period_summary;
  61 
  62   // A DirtyCardQueueSet that is used to hold cards that contain
  63   // references into the current collection set. This is used to
  64   // update the remembered sets of the regions in the collection
  65   // set in the event of an evacuation failure.
  66   DirtyCardQueueSet _into_cset_dirty_card_queue_set;
  67 
  68   // Scan all remembered sets of the collection set for references into the collection
  69   // set.
  70   void scan_rem_set(G1ParScanThreadState* pss,
  71                     CodeBlobClosure* heap_region_codeblobs,
  72                     uint worker_i);
  73 
  74   // Flush remaining refinement buffers for cross-region references to either evacuate references
  75   // into the collection set or update the remembered set.
  76   void update_rem_set(DirtyCardQueue* into_cset_dcq, G1ParScanThreadState* pss, uint worker_i);
  77 
  78 protected:
  79   G1CollectedHeap* _g1;
  80   size_t _conc_refine_cards;
  81   uint n_workers();
  82 
  83 protected:
  84   CardTableModRefBS*     _ct_bs;
  85   G1Policy*              _g1p;
  86   G1HotCardCache*        _hot_card_cache;
  87 
  88 public:
  89   // Gives an approximation on how many threads can be expected to add records to
  90   // a remembered set in parallel. This can be used for sizing data structures to
  91   // decrease performance losses due to data structure sharing.
  92   // Examples for quantities that influence this value are the maximum number of
  93   // mutator threads, maximum number of concurrent refinement or GC threads.
  94   static uint num_par_rem_sets();
  95 
  96   // Initialize data that depends on the heap size being known.
  97   void initialize(size_t capacity, uint max_regions);
  98 
  99   // This is called to reset dual hash tables after the gc pause
 100   // is finished and the initial hash table is no longer being
 101   // scanned.
 102   void cleanupHRRS();
 103 
 104   G1RemSet(G1CollectedHeap* g1,
 105            CardTableModRefBS* ct_bs,
 106            G1HotCardCache* hot_card_cache);
 107   ~G1RemSet();
 108 
 109   // Process all oops in the collection set from the cards in the refinement buffers and
 110   // remembered sets using pss.
 111   //
 112   // Further applies heap_region_codeblobs on the oops of the unmarked nmethods on the strong code
 113   // roots list for each region in the collection set.
 114   void oops_into_collection_set_do(G1ParScanThreadState* pss,
 115                                    CodeBlobClosure* heap_region_codeblobs,
 116                                    uint worker_i);
 117 
 118   // Prepare for and cleanup after an oops_into_collection_set_do
 119   // call.  Must call each of these once before and after (in sequential
 120   // code) any thread calls oops_into_collection_set_do.
 121   void prepare_for_oops_into_collection_set_do();
 122   void cleanup_after_oops_into_collection_set_do();
 123 
 124   G1RemSetScanState* scan_state() const { return _scan_state; }
 125 
 126   // Record, if necessary, the fact that *p (where "p" is in region "from",
 127   // which is required to be non-NULL) has changed to a new non-NULL value.
 128   template <class T> void par_write_ref(HeapRegion* from, T* p, uint tid);
 129 
 130   // Eliminates any remembered set entries that correspond to dead heap ranges.
 131   void scrub(uint worker_num, HeapRegionClaimer* hrclaimer);
 132 
 133   // Refine the card corresponding to "card_ptr". Safe to be called concurrently
 134   // to the mutator.
 135   void refine_card_concurrently(jbyte* card_ptr,
 136                                 uint worker_i);
 137 
 138   // Refine the card corresponding to "card_ptr", applying the given closure to
 139   // all references found. Returns "true" if the given card contains
 140   // oops that have references into the current collection set. Must only be
 141   // called during gc.
 142   bool refine_card_during_gc(jbyte* card_ptr,
 143                              G1ScanObjsDuringUpdateRSClosure* update_rs_cl);
 144 
 145   // Print accumulated summary info from the start of the VM.
 146   void print_summary_info();
 147 
 148   // Print accumulated summary info from the last time called.
 149   void print_periodic_summary_info(const char* header, uint period_count);
 150 
 151   // Prepare remembered set for verification.
 152   void prepare_for_verify();
 153 
 154   size_t conc_refine_cards() const { return _conc_refine_cards; }
 155 
 156   void create_card_live_data(WorkGang* workers, G1CMBitMap* mark_bitmap);
 157   void finalize_card_live_data(WorkGang* workers, G1CMBitMap* mark_bitmap);
 158 
 159   // Verify that the liveness count data created concurrently matches one created
 160   // during this safepoint.
 161   void verify_card_live_data(WorkGang* workers, G1CMBitMap* actual_bitmap);
 162 
 163   void clear_card_live_data(WorkGang* workers);
 164 
 165 #ifdef ASSERT
 166   void verify_card_live_data_is_clear();
 167 #endif
 168 };
 169 
 170 class G1ScanRSForRegionClosure : public HeapRegionClosure {
 171   G1RemSetScanState* _scan_state;
 172 
 173   size_t _cards_scanned;
 174   size_t _cards_claimed;
 175   size_t _cards_skipped;
 176 
 177   G1CollectedHeap* _g1h;
 178 
 179   G1ScanObjsDuringScanRSClosure* _scan_objs_on_card_cl;
 180   CodeBlobClosure* _code_root_cl;
 181 
 182   G1BlockOffsetTable* _bot;
 183   G1SATBCardTableModRefBS *_ct_bs;
 184 
 185   double _strong_code_root_scan_time_sec;
 186   uint   _worker_i;
 187 
 188   void scan_card(size_t index, HeapWord* card_start, HeapRegion *r);
 189   void scan_strong_code_roots(HeapRegion* r);
 190 public:
 191   G1ScanRSForRegionClosure(G1RemSetScanState* scan_state,
 192                            G1ScanObjsDuringScanRSClosure* scan_obj_on_card,
 193                            CodeBlobClosure* code_root_cl,
 194                            uint worker_i);
 195 
 196   bool doHeapRegion(HeapRegion* r);
 197 
 198   double strong_code_root_scan_time_sec() {
 199     return _strong_code_root_scan_time_sec;
 200   }
 201 
 202   size_t cards_scanned() const { return _cards_scanned; }
 203   size_t cards_claimed() const { return _cards_claimed; }
 204   size_t cards_skipped() const { return _cards_skipped; }
 205 };
 206 
 207 class RebuildRSOopClosure: public ExtendedOopClosure {
 208   HeapRegion* _from;
 209   G1RemSet* _rs;
 210   uint _worker_i;
 211 
 212   template <class T> void do_oop_work(T* p);
 213 
 214 public:
 215   RebuildRSOopClosure(G1RemSet* rs, uint worker_i = 0) :
 216     _from(NULL), _rs(rs), _worker_i(worker_i)
 217   {}
 218 
 219   void set_from(HeapRegion* from) {
 220     assert(from != NULL, "from region must be non-NULL");
 221     _from = from;
 222   }
 223 
 224   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 225   virtual void do_oop(oop* p)       { do_oop_work(p); }
 226 };
 227 
 228 #endif // SHARE_VM_GC_G1_G1REMSET_HPP