1 /*
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  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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  5  * This code is free software; you can redistribute it and/or modify it
  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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 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 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 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   // Scan all remembered sets of the collection set for references into the collection
 63   // set.
 64   void scan_rem_set(G1ParScanThreadState* pss,
 65                     CodeBlobClosure* heap_region_codeblobs,
 66                     uint worker_i);
 67 
 68   // Flush remaining refinement buffers for cross-region references to either evacuate references
 69   // into the collection set or update the remembered set.
 70   void update_rem_set(G1ParScanThreadState* pss, uint worker_i);
 71 
 72   G1CollectedHeap* _g1;
 73   size_t _num_conc_refined_cards; // Number of cards refined concurrently to the mutator.
 74 
 75   G1CardTable*           _ct;
 76   G1Policy*              _g1p;
 77   G1HotCardCache*        _hot_card_cache;
 78 
 79 public:
 80   // Gives an approximation on how many threads can be expected to add records to
 81   // a remembered set in parallel. This can be used for sizing data structures to
 82   // decrease performance losses due to data structure sharing.
 83   // Examples for quantities that influence this value are the maximum number of
 84   // mutator threads, maximum number of concurrent refinement or GC threads.
 85   static uint num_par_rem_sets();
 86 
 87   // Initialize data that depends on the heap size being known.
 88   void initialize(size_t capacity, uint max_regions);
 89 
 90   // This is called to reset dual hash tables after the gc pause
 91   // is finished and the initial hash table is no longer being
 92   // scanned.
 93   void cleanupHRRS();
 94 
 95   G1RemSet(G1CollectedHeap* g1,
 96            G1CardTable* ct,
 97            G1HotCardCache* hot_card_cache);
 98   ~G1RemSet();
 99 
100   // Process all oops in the collection set from the cards in the refinement buffers and
101   // remembered sets using pss.
102   //
103   // Further applies heap_region_codeblobs on the oops of the unmarked nmethods on the strong code
104   // roots list for each region in the collection set.
105   void oops_into_collection_set_do(G1ParScanThreadState* pss,
106                                    CodeBlobClosure* heap_region_codeblobs,
107                                    uint worker_i);
108 
109   // Prepare for and cleanup after an oops_into_collection_set_do
110   // call.  Must call each of these once before and after (in sequential
111   // code) any thread calls oops_into_collection_set_do.
112   void prepare_for_oops_into_collection_set_do();
113   void cleanup_after_oops_into_collection_set_do();
114 
115   G1RemSetScanState* scan_state() const { return _scan_state; }
116 
117   // Eliminates any remembered set entries that correspond to dead heap ranges.
118   void scrub(uint worker_num, HeapRegionClaimer* hrclaimer);
119 
120   // Refine the card corresponding to "card_ptr". Safe to be called concurrently
121   // to the mutator.
122   void refine_card_concurrently(jbyte* card_ptr,
123                                 uint worker_i);
124 
125   // Refine the card corresponding to "card_ptr", applying the given closure to
126   // all references found. Must only be called during gc.
127   // Returns whether the card has been scanned.
128   bool refine_card_during_gc(jbyte* card_ptr, G1ScanObjsDuringUpdateRSClosure* update_rs_cl);
129 
130   // Print accumulated summary info from the start of the VM.
131   void print_summary_info();
132 
133   // Print accumulated summary info from the last time called.
134   void print_periodic_summary_info(const char* header, uint period_count);
135 
136   size_t num_conc_refined_cards() const { return _num_conc_refined_cards; }
137 
138   void create_card_live_data(WorkGang* workers, G1CMBitMap* mark_bitmap);
139   void finalize_card_live_data(WorkGang* workers, G1CMBitMap* mark_bitmap);
140 
141   // Verify that the liveness count data created concurrently matches one created
142   // during this safepoint.
143   void verify_card_live_data(WorkGang* workers, G1CMBitMap* actual_bitmap);
144 
145   void clear_card_live_data(WorkGang* workers);
146 
147 #ifdef ASSERT
148   void verify_card_live_data_is_clear();
149 #endif
150 };
151 
152 class G1ScanRSForRegionClosure : public HeapRegionClosure {
153   G1RemSetScanState* _scan_state;
154 
155   size_t _cards_scanned;
156   size_t _cards_claimed;
157   size_t _cards_skipped;
158 
159   G1CollectedHeap* _g1h;
160 
161   G1ScanObjsDuringScanRSClosure* _scan_objs_on_card_cl;
162   CodeBlobClosure* _code_root_cl;
163 
164   G1BlockOffsetTable* _bot;
165   G1CardTable *_ct;
166 
167   double _strong_code_root_scan_time_sec;
168   uint   _worker_i;
169 
170   void claim_card(size_t card_index, const uint region_idx_for_card);
171   void scan_card(MemRegion mr, uint region_idx_for_card);
172   void scan_strong_code_roots(HeapRegion* r);
173 public:
174   G1ScanRSForRegionClosure(G1RemSetScanState* scan_state,
175                            G1ScanObjsDuringScanRSClosure* scan_obj_on_card,
176                            CodeBlobClosure* code_root_cl,
177                            uint worker_i);
178 
179   bool do_heap_region(HeapRegion* r);
180 
181   double strong_code_root_scan_time_sec() {
182     return _strong_code_root_scan_time_sec;
183   }
184 
185   size_t cards_scanned() const { return _cards_scanned; }
186   size_t cards_claimed() const { return _cards_claimed; }
187   size_t cards_skipped() const { return _cards_skipped; }
188 };
189 
190 #endif // SHARE_VM_GC_G1_G1REMSET_HPP