1 /*
   2  * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   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  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  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
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  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 G1ParPushHeapRSClosure;
  45 class G1RemSetScanState;
  46 class G1Policy;
  47 class G1SATBCardTableModRefBS;
  48 class HeapRegionClaimer;
  49 
  50 // A G1RemSet in which each heap region has a rem set that records the
  51 // external heap references into it.  Uses a mod ref bs to track updates,
  52 // so that they can be used to update the individual region remsets.
  53 class G1RemSet: public CHeapObj<mtGC> {
  54 private:
  55   G1RemSetScanState* _scan_state;
  56   G1CardLiveData _card_live_data;
  57 
  58   G1RemSetSummary _prev_period_summary;
  59 
  60   // A DirtyCardQueueSet that is used to hold cards that contain
  61   // references into the current collection set. This is used to
  62   // update the remembered sets of the regions in the collection
  63   // set in the event of an evacuation failure.
  64   DirtyCardQueueSet _into_cset_dirty_card_queue_set;
  65 
  66 protected:
  67   G1CollectedHeap* _g1;
  68   size_t _conc_refine_cards;
  69   uint n_workers();
  70 
  71 protected:
  72   CardTableModRefBS*     _ct_bs;
  73   G1Policy*              _g1p;
  74   G1HotCardCache*        _hot_card_cache;
  75 
  76 public:
  77   // Gives an approximation on how many threads can be expected to add records to
  78   // a remembered set in parallel. This can be used for sizing data structures to
  79   // decrease performance losses due to data structure sharing.
  80   // Examples for quantities that influence this value are the maximum number of
  81   // mutator threads, maximum number of concurrent refinement or GC threads.
  82   static uint num_par_rem_sets();
  83 
  84   // Initialize data that depends on the heap size being known.
  85   void initialize(size_t capacity, uint max_regions);
  86 
  87   // This is called to reset dual hash tables after the gc pause
  88   // is finished and the initial hash table is no longer being
  89   // scanned.
  90   void cleanupHRRS();
  91 
  92   G1RemSet(G1CollectedHeap* g1,
  93            CardTableModRefBS* ct_bs,
  94            G1HotCardCache* hot_card_cache);
  95   ~G1RemSet();
  96 
  97   // Invoke "cl->do_oop" on all pointers into the collection set
  98   // from objects in regions outside the collection set (having
  99   // invoked "cl->set_region" to set the "from" region correctly
 100   // beforehand.)
 101   //
 102   // Apply non_heap_roots on the oops of the unmarked nmethods
 103   // on the strong code roots list for each region in the
 104   // collection set.
 105   //
 106   // The "worker_i" param is for the parallel case where the id
 107   // of the worker thread calling this function can be helpful in
 108   // partitioning the work to be done. It should be the same as
 109   // the "i" passed to the calling thread's work(i) function.
 110   // In the sequential case this param will be ignored.
 111   //
 112   // Returns the number of cards scanned while looking for pointers
 113   // into the collection set.
 114   size_t oops_into_collection_set_do(G1ParPushHeapRSClosure* cl,
 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 threads call oops_into_collection_set_do.  (This offers an
 121   // opportunity to sequential setup and teardown of structures needed by a
 122   // parallel iteration over the CS's RS.)
 123   void prepare_for_oops_into_collection_set_do();
 124   void cleanup_after_oops_into_collection_set_do();
 125 
 126   size_t scan_rem_set(G1ParPushHeapRSClosure* oops_in_heap_closure,
 127                       CodeBlobClosure* heap_region_codeblobs,
 128                       uint worker_i);
 129 
 130   G1RemSetScanState* scan_state() const { return _scan_state; }
 131 
 132   // Flush remaining refinement buffers into the remembered set,
 133   // applying oops_in_heap_closure on the references found.
 134   void update_rem_set(DirtyCardQueue* into_cset_dcq, G1ParPushHeapRSClosure* oops_in_heap_closure, uint worker_i);
 135 
 136   // Record, if necessary, the fact that *p (where "p" is in region "from",
 137   // which is required to be non-NULL) has changed to a new non-NULL value.
 138   template <class T> void par_write_ref(HeapRegion* from, T* p, uint tid);
 139 
 140   // Requires "region_bm" and "card_bm" to be bitmaps with 1 bit per region
 141   // or card, respectively, such that a region or card with a corresponding
 142   // 0 bit contains no part of any live object.  Eliminates any remembered
 143   // set entries that correspond to dead heap ranges. "worker_num" is the
 144   // parallel thread id of the current thread, and "hrclaimer" is the
 145   // HeapRegionClaimer that should be used.
 146   void scrub(uint worker_num, HeapRegionClaimer* hrclaimer);
 147 
 148   // Refine the card corresponding to "card_ptr".
 149   // If oops_in_heap_closure is not NULL, a true result is returned
 150   // if the given card contains oops that have references into the
 151   // current collection set.
 152   bool refine_card(jbyte* card_ptr,
 153                    uint worker_i,
 154                    G1ParPushHeapRSClosure* oops_in_heap_closure);
 155 
 156   // Print accumulated summary info from the start of the VM.
 157   void print_summary_info();
 158 
 159   // Print accumulated summary info from the last time called.
 160   void print_periodic_summary_info(const char* header, uint period_count);
 161 
 162   // Prepare remembered set for verification.
 163   void prepare_for_verify();
 164 
 165   size_t conc_refine_cards() const {
 166     return _conc_refine_cards;
 167   }
 168 
 169   void create_card_live_data(WorkGang* workers, G1CMBitMap* mark_bitmap);
 170   void finalize_card_live_data(WorkGang* workers, G1CMBitMap* mark_bitmap);
 171 
 172   // Verify that the liveness count data created concurrently matches one created
 173   // during this safepoint.
 174   void verify_card_live_data(WorkGang* workers, G1CMBitMap* actual_bitmap);
 175 
 176   void clear_card_live_data(WorkGang* workers);
 177 
 178 #ifdef ASSERT
 179   void verify_card_live_data_is_clear();
 180 #endif
 181 };
 182 
 183 class G1ScanRSClosure : public HeapRegionClosure {
 184   G1RemSetScanState* _scan_state;
 185 
 186   size_t _cards_done;
 187   size_t _cards;
 188   G1CollectedHeap* _g1h;
 189 
 190   G1ParPushHeapRSClosure* _push_heap_cl;
 191   CodeBlobClosure* _code_root_cl;
 192 
 193   G1BlockOffsetTable* _bot;
 194   G1SATBCardTableModRefBS *_ct_bs;
 195 
 196   double _strong_code_root_scan_time_sec;
 197   uint   _worker_i;
 198   size_t _block_size;
 199 
 200   void scan_card(size_t index, HeapRegion *r);
 201   void scan_strong_code_roots(HeapRegion* r);
 202 public:
 203   G1ScanRSClosure(G1RemSetScanState* scan_state,
 204                   G1ParPushHeapRSClosure* push_heap_cl,
 205                   CodeBlobClosure* code_root_cl,
 206                   uint worker_i);
 207 
 208   bool doHeapRegion(HeapRegion* r);
 209 
 210   double strong_code_root_scan_time_sec() {
 211     return _strong_code_root_scan_time_sec;
 212   }
 213 
 214   size_t cards_done() { return _cards_done;}
 215   size_t cards_looked_up() { return _cards;}
 216 };
 217 
 218 class UpdateRSOopClosure: public ExtendedOopClosure {
 219   HeapRegion* _from;
 220   G1RemSet* _rs;
 221   uint _worker_i;
 222 
 223   template <class T> void do_oop_work(T* p);
 224 
 225 public:
 226   UpdateRSOopClosure(G1RemSet* rs, uint worker_i = 0) :
 227     _from(NULL), _rs(rs), _worker_i(worker_i)
 228   {}
 229 
 230   void set_from(HeapRegion* from) {
 231     assert(from != NULL, "from region must be non-NULL");
 232     _from = from;
 233   }
 234 
 235   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 236   virtual void do_oop(oop* p)       { do_oop_work(p); }
 237 };
 238 
 239 #endif // SHARE_VM_GC_G1_G1REMSET_HPP