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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  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/g1RemSetSummary.hpp"
  30 #include "gc/g1/heapRegion.hpp"
  31 #include "memory/allocation.hpp"
  32 #include "memory/iterator.hpp"
  33 
  34 // A G1RemSet provides ways of iterating over pointers into a selected
  35 // collection set.
  36 
  37 class BitMap;
  38 class CardTableModRefBS;
  39 class G1BlockOffsetSharedArray;
  40 class ConcurrentG1Refine;
  41 class CodeBlobClosure;
  42 class G1CollectedHeap;
  43 class G1CollectorPolicy;
  44 class G1ParPushHeapRSClosure;
  45 class G1SATBCardTableModRefBS;
  46 class HeapRegionClaimer;
  47 
  48 // A G1RemSet in which each heap region has a rem set that records the
  49 // external heap references into it.  Uses a mod ref bs to track updates,
  50 // so that they can be used to update the individual region remsets.
  51 
  52 class G1RemSet: public CHeapObj<mtGC> {
  53 private:
  54   G1RemSetSummary _prev_period_summary;
  55 
  56   // A DirtyCardQueueSet that is used to hold cards that contain
  57   // references into the current collection set. This is used to
  58   // update the remembered sets of the regions in the collection
  59   // set in the event of an evacuation failure.
  60   DirtyCardQueueSet _into_cset_dirty_card_queue_set;
  61 
  62 protected:
  63   G1CollectedHeap* _g1;
  64   size_t _conc_refine_cards;
  65   uint n_workers();
  66 
  67 protected:
  68   CardTableModRefBS*     _ct_bs;
  69   G1CollectorPolicy*     _g1p;
  70 
  71   ConcurrentG1Refine*    _cg1r;
  72 
  73   // Used for caching the closure that is responsible for scanning
  74   // references into the collection set.
  75   G1ParPushHeapRSClosure** _cset_rs_update_cl;
  76 
  77 public:
  78   // Gives an approximation on how many threads can be expected to add records to
  79   // a remembered set in parallel. This can be used for sizing data structures to
  80   // decrease performance losses due to data structure sharing.
  81   // Examples for quantities that influence this value are the maximum number of
  82   // mutator threads, maximum number of concurrent refinement or GC threads.
  83   static uint num_par_rem_sets();
  84 
  85   // Initialize data that depends on the heap size being known.
  86   static void initialize(uint max_regions);
  87 
  88   // This is called to reset dual hash tables after the gc pause
  89   // is finished and the initial hash table is no longer being
  90   // scanned.
  91   void cleanupHRRS();
  92 
  93   G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs);
  94   ~G1RemSet();
  95 
  96   // Invoke "blk->do_oop" on all pointers into the collection set
  97   // from objects in regions outside the collection set (having
  98   // invoked "blk->set_region" to set the "from" region correctly
  99   // beforehand.)
 100   //
 101   // Apply non_heap_roots on the oops of the unmarked nmethods
 102   // on the strong code roots list for each region in the
 103   // collection set.
 104   //
 105   // The "worker_i" param is for the parallel case where the id
 106   // of the worker thread calling this function can be helpful in
 107   // partitioning the work to be done. It should be the same as
 108   // the "i" passed to the calling thread's work(i) function.
 109   // In the sequential case this param will be ignored.
 110   //
 111   // Returns the number of cards scanned while looking for pointers
 112   // into the collection set.
 113   size_t oops_into_collection_set_do(G1ParPushHeapRSClosure* blk,
 114                                      CodeBlobClosure* heap_region_codeblobs,
 115                                      uint worker_i);
 116 
 117   // Prepare for and cleanup after an oops_into_collection_set_do
 118   // call.  Must call each of these once before and after (in sequential
 119   // code) any threads call oops_into_collection_set_do.  (This offers an
 120   // opportunity to sequential setup and teardown of structures needed by a
 121   // parallel iteration over the CS's RS.)
 122   void prepare_for_oops_into_collection_set_do();
 123   void cleanup_after_oops_into_collection_set_do();
 124 
 125   size_t scanRS(G1ParPushHeapRSClosure* oc,
 126                 CodeBlobClosure* heap_region_codeblobs,
 127                 uint worker_i);
 128 
 129   void updateRS(DirtyCardQueue* into_cset_dcq, uint worker_i);
 130 
 131   CardTableModRefBS* ct_bs() { return _ct_bs; }
 132 
 133   // Record, if necessary, the fact that *p (where "p" is in region "from",
 134   // which is required to be non-NULL) has changed to a new non-NULL value.
 135   template <class T> void par_write_ref(HeapRegion* from, T* p, uint tid);
 136 
 137   // Requires "region_bm" and "card_bm" to be bitmaps with 1 bit per region
 138   // or card, respectively, such that a region or card with a corresponding
 139   // 0 bit contains no part of any live object.  Eliminates any remembered
 140   // set entries that correspond to dead heap ranges. "worker_num" is the
 141   // parallel thread id of the current thread, and "hrclaimer" is the
 142   // HeapRegionClaimer that should be used.
 143   void scrub(BitMap* region_bm, BitMap* card_bm, uint worker_num, HeapRegionClaimer* hrclaimer);
 144 
 145   // Refine the card corresponding to "card_ptr".
 146   // If check_for_refs_into_cset is true, a true result is returned
 147   // if the given card contains oops that have references into the
 148   // current collection set.
 149   virtual bool refine_card(jbyte* card_ptr,
 150                            uint worker_i,
 151                            bool check_for_refs_into_cset);
 152 
 153   // Print accumulated summary info from the start of the VM.
 154   virtual void print_summary_info();
 155 
 156   // Print accumulated summary info from the last time called.
 157   virtual void print_periodic_summary_info(const char* header, uint period_count);
 158 
 159   // Prepare remembered set for verification.
 160   virtual void prepare_for_verify();
 161 
 162   size_t conc_refine_cards() const {
 163     return _conc_refine_cards;
 164   }
 165 };
 166 
 167 class ScanRSClosure : public HeapRegionClosure {
 168   size_t _cards_done, _cards;
 169   G1CollectedHeap* _g1h;
 170 
 171   G1ParPushHeapRSClosure* _oc;
 172   CodeBlobClosure* _code_root_cl;
 173 
 174   G1BlockOffsetSharedArray* _bot_shared;
 175   G1SATBCardTableModRefBS *_ct_bs;
 176 
 177   double _strong_code_root_scan_time_sec;
 178   uint   _worker_i;
 179   size_t _block_size;
 180   bool   _try_claimed;
 181 
 182 public:
 183   ScanRSClosure(G1ParPushHeapRSClosure* oc,
 184                 CodeBlobClosure* code_root_cl,
 185                 uint worker_i);
 186 
 187   bool doHeapRegion(HeapRegion* r);
 188 
 189   double strong_code_root_scan_time_sec() {
 190     return _strong_code_root_scan_time_sec;
 191   }
 192   size_t cards_done() { return _cards_done;}
 193   size_t cards_looked_up() { return _cards;}
 194   void set_try_claimed() { _try_claimed = true; }
 195 private:
 196   void scanCard(size_t index, HeapRegion *r);
 197   void printCard(HeapRegion* card_region, size_t card_index,
 198                  HeapWord* card_start);
 199   void scan_strong_code_roots(HeapRegion* r);
 200 };
 201 
 202 class UpdateRSOopClosure: public ExtendedOopClosure {
 203   HeapRegion* _from;
 204   G1RemSet* _rs;
 205   uint _worker_i;
 206 
 207   template <class T> void do_oop_work(T* p);
 208 
 209 public:
 210   UpdateRSOopClosure(G1RemSet* rs, uint worker_i = 0) :
 211     _from(NULL), _rs(rs), _worker_i(worker_i)
 212   {}
 213 
 214   void set_from(HeapRegion* from) {
 215     assert(from != NULL, "from region must be non-NULL");
 216     _from = from;
 217   }
 218 
 219   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 220   virtual void do_oop(oop* p)       { do_oop_work(p); }
 221 };
 222 
 223 #endif // SHARE_VM_GC_G1_G1REMSET_HPP