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.
  8  *
  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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 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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/g1CardTable.hpp"
 31 #include "gc/g1/g1RemSetSummary.hpp"
 32 #include "gc/g1/heapRegion.hpp"
 33 #include "memory/allocation.hpp"
 34 #include "memory/iterator.hpp"
 35 
 36 // A G1RemSet provides ways of iterating over pointers into a selected
 37 // collection set.
 38 
 39 class BitMap;
 40 class CardTableModRefBS;
 41 class G1BlockOffsetTable;
 42 class CodeBlobClosure;
 43 class G1CollectedHeap;
 44 class G1HotCardCache;
 45 class G1RemSetScanState;
 46 class G1ParScanThreadState;
 47 class G1Policy;
 48 class G1SATBCardTableModRefBS;
 49 class G1ScanObjsDuringScanRSClosure;
 50 class G1ScanObjsDuringUpdateRSClosure;
 51 class HeapRegionClaimer;
 52 
 53 // A G1RemSet in which each heap region has a rem set that records the
 54 // external heap references into it.  Uses a mod ref bs to track updates,
 55 // so that they can be used to update the individual region remsets.
 56 class G1RemSet: public CHeapObj<mtGC> {
 57 private:
 58   G1RemSetScanState* _scan_state;
 59   G1CardLiveData _card_live_data;
 60 
 61   G1RemSetSummary _prev_period_summary;
 62 
 63   // Scan all remembered sets of the collection set for references into the collection
 64   // set.
 65   void scan_rem_set(G1ParScanThreadState* pss,
 66                     CodeBlobClosure* heap_region_codeblobs,
 67                     uint worker_i);
 68 
 69   // Flush remaining refinement buffers for cross-region references to either evacuate references
 70   // into the collection set or update the remembered set.
 71   void update_rem_set(G1ParScanThreadState* pss, uint worker_i);
 72 
 73   G1CollectedHeap* _g1;
 74   size_t _num_conc_refined_cards; // Number of cards refined concurrently to the mutator.
 75 
 76   G1CardTable*           _ct;
 77   G1Policy*              _g1p;
 78   G1HotCardCache*        _hot_card_cache;
 79 
 80 public:
 81   // Gives an approximation on how many threads can be expected to add records to
 82   // a remembered set in parallel. This can be used for sizing data structures to
 83   // decrease performance losses due to data structure sharing.
 84   // Examples for quantities that influence this value are the maximum number of
 85   // mutator threads, maximum number of concurrent refinement or GC threads.
 86   static uint num_par_rem_sets();
 87 
 88   // Initialize data that depends on the heap size being known.
 89   void initialize(size_t capacity, uint max_regions);
 90 
 91   // This is called to reset dual hash tables after the gc pause
 92   // is finished and the initial hash table is no longer being
 93   // scanned.
 94   void cleanupHRRS();
 95 
 96   G1RemSet(G1CollectedHeap* g1,
 97            G1CardTable* ct,
 98            G1HotCardCache* hot_card_cache);
 99   ~G1RemSet();
100 
101   // Process all oops in the collection set from the cards in the refinement buffers and
102   // remembered sets using pss.
103   //
104   // Further applies heap_region_codeblobs on the oops of the unmarked nmethods on the strong code
105   // roots list for each region in the collection set.
106   void oops_into_collection_set_do(G1ParScanThreadState* pss,
107                                    CodeBlobClosure* heap_region_codeblobs,
108                                    uint worker_i);
109 
110   // Prepare for and cleanup after an oops_into_collection_set_do
111   // call.  Must call each of these once before and after (in sequential
112   // code) any thread calls oops_into_collection_set_do.
113   void prepare_for_oops_into_collection_set_do();
114   void cleanup_after_oops_into_collection_set_do();
115 
116   G1RemSetScanState* scan_state() const { return _scan_state; }
117 
118   // Eliminates any remembered set entries that correspond to dead heap ranges.
119   void scrub(uint worker_num, HeapRegionClaimer* hrclaimer);
120 
121   // Refine the card corresponding to "card_ptr". Safe to be called concurrently
122   // to the mutator.
123   void refine_card_concurrently(jbyte* card_ptr,
124                                 uint worker_i);
125 
126   // Refine the card corresponding to "card_ptr", applying the given closure to
127   // all references found. Must only be called during gc.
128   // Returns whether the card has been scanned.
129   bool refine_card_during_gc(jbyte* card_ptr, G1ScanObjsDuringUpdateRSClosure* update_rs_cl);
130 
131   // Print accumulated summary info from the start of the VM.
132   void print_summary_info();
133 
134   // Print accumulated summary info from the last time called.
135   void print_periodic_summary_info(const char* header, uint period_count);
136 
137   size_t num_conc_refined_cards() const { return _num_conc_refined_cards; }
138 
139   void create_card_live_data(WorkGang* workers, G1CMBitMap* mark_bitmap);
140   void finalize_card_live_data(WorkGang* workers, G1CMBitMap* mark_bitmap);
141 
142   // Verify that the liveness count data created concurrently matches one created
143   // during this safepoint.
144   void verify_card_live_data(WorkGang* workers, G1CMBitMap* actual_bitmap);
145 
146   void clear_card_live_data(WorkGang* workers);
147 
148 #ifdef ASSERT
149   void verify_card_live_data_is_clear();
150 #endif
151 };
152 
153 class G1ScanRSForRegionClosure : public HeapRegionClosure {
154   G1RemSetScanState* _scan_state;
155 
156   size_t _cards_scanned;
157   size_t _cards_claimed;
158   size_t _cards_skipped;
159 
160   G1CollectedHeap* _g1h;
161 
162   G1ScanObjsDuringScanRSClosure* _scan_objs_on_card_cl;
163   CodeBlobClosure* _code_root_cl;
164 
165   G1BlockOffsetTable* _bot;
166   G1CardTable *_ct;
167 
168   double _strong_code_root_scan_time_sec;
169   uint   _worker_i;
170 
171   void claim_card(size_t card_index, const uint region_idx_for_card);
172   void scan_card(MemRegion mr, uint region_idx_for_card);
173   void scan_strong_code_roots(HeapRegion* r);
174 public:
175   G1ScanRSForRegionClosure(G1RemSetScanState* scan_state,
176                            G1ScanObjsDuringScanRSClosure* scan_obj_on_card,
177                            CodeBlobClosure* code_root_cl,
178                            uint worker_i);
179 
180   bool do_heap_region(HeapRegion* r);
181 
182   double strong_code_root_scan_time_sec() {
183     return _strong_code_root_scan_time_sec;
184   }
185 
186   size_t cards_scanned() const { return _cards_scanned; }
187   size_t cards_claimed() const { return _cards_claimed; }
188   size_t cards_skipped() const { return _cards_skipped; }
189 };
190 
191 #endif // SHARE_VM_GC_G1_G1REMSET_HPP