1 /*
   2  * Copyright (c) 2001, 2014, 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.
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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).
  14  *
  15  * You should have received a copy of the GNU General Public License version
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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
  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_HPP
  27 
  28 #include "gc_implementation/g1/g1RemSetSummary.hpp"
  29 
  30 // A G1RemSet provides ways of iterating over pointers into a selected
  31 // collection set.
  32 
  33 class G1CollectedHeap;
  34 class ConcurrentG1Refine;
  35 class G1ParPushHeapRSClosure;
  36 
  37 // A G1RemSet in which each heap region has a rem set that records the
  38 // external heap references into it.  Uses a mod ref bs to track updates,
  39 // so that they can be used to update the individual region remsets.
  40 
  41 class G1RemSet: public CHeapObj<mtGC> {
  42 private:
  43   G1RemSetSummary _prev_period_summary;
  44 protected:
  45   G1CollectedHeap* _g1;
  46   size_t _conc_refine_cards;
  47   uint n_workers();
  48 
  49 protected:
  50   enum SomePrivateConstants {
  51     UpdateRStoMergeSync  = 0,
  52     MergeRStoDoDirtySync = 1,
  53     DoDirtySync          = 2,
  54     LastSync             = 3,
  55 
  56     SeqTask              = 0,
  57     NumSeqTasks          = 1
  58   };
  59 
  60   CardTableModRefBS*     _ct_bs;
  61   SubTasksDone*          _seq_task;
  62   G1CollectorPolicy*     _g1p;
  63 
  64   ConcurrentG1Refine*    _cg1r;
  65 
  66   size_t*                _cards_scanned;
  67   size_t                 _total_cards_scanned;
  68 
  69   // Used for caching the closure that is responsible for scanning
  70   // references into the collection set.
  71   G1ParPushHeapRSClosure** _cset_rs_update_cl;
  72 
  73   // Print the given summary info
  74   virtual void print_summary_info(G1RemSetSummary * summary, const char * header = NULL);
  75 public:
  76   // This is called to reset dual hash tables after the gc pause
  77   // is finished and the initial hash table is no longer being
  78   // scanned.
  79   void cleanupHRRS();
  80 
  81   G1RemSet(G1CollectedHeap* g1, CardTableModRefBS* ct_bs);
  82   ~G1RemSet();
  83 
  84   // Invoke "blk->do_oop" on all pointers into the collection set
  85   // from objects in regions outside the collection set (having
  86   // invoked "blk->set_region" to set the "from" region correctly
  87   // beforehand.)
  88   //
  89   // Invoke code_root_cl->do_code_blob on the unmarked nmethods
  90   // on the strong code roots list for each region in the
  91   // collection set.
  92   //
  93   // The "worker_i" param is for the parallel case where the id
  94   // of the worker thread calling this function can be helpful in
  95   // partitioning the work to be done. It should be the same as
  96   // the "i" passed to the calling thread's work(i) function.
  97   // In the sequential case this param will be ignored.
  98   void oops_into_collection_set_do(G1ParPushHeapRSClosure* blk,
  99                                    CodeBlobClosure* code_root_cl,
 100                                    uint worker_i);
 101 
 102   // Prepare for and cleanup after an oops_into_collection_set_do
 103   // call.  Must call each of these once before and after (in sequential
 104   // code) any threads call oops_into_collection_set_do.  (This offers an
 105   // opportunity to sequential setup and teardown of structures needed by a
 106   // parallel iteration over the CS's RS.)
 107   void prepare_for_oops_into_collection_set_do();
 108   void cleanup_after_oops_into_collection_set_do();
 109 
 110   void scanRS(G1ParPushHeapRSClosure* oc,
 111               CodeBlobClosure* code_root_cl,
 112               uint worker_i);
 113 
 114   void updateRS(DirtyCardQueue* into_cset_dcq, uint worker_i);
 115 
 116   CardTableModRefBS* ct_bs() { return _ct_bs; }
 117   size_t cardsScanned() { return _total_cards_scanned; }
 118 
 119   // Record, if necessary, the fact that *p (where "p" is in region "from",
 120   // which is required to be non-NULL) has changed to a new non-NULL value.
 121   template <class T> void write_ref(HeapRegion* from, T* p);
 122   template <class T> void par_write_ref(HeapRegion* from, T* p, uint tid);
 123 
 124   // Requires "region_bm" and "card_bm" to be bitmaps with 1 bit per region
 125   // or card, respectively, such that a region or card with a corresponding
 126   // 0 bit contains no part of any live object.  Eliminates any remembered
 127   // set entries that correspond to dead heap ranges. "worker_num" is the
 128   // parallel thread id of the current thread, and "hrclaimer" is the
 129   // HeapRegionClaimer that should be used.
 130   void scrub(BitMap* region_bm, BitMap* card_bm, uint worker_num, HeapRegionClaimer* hrclaimer);
 131 
 132   // Refine the card corresponding to "card_ptr".
 133   // If check_for_refs_into_cset is true, a true result is returned
 134   // if the given card contains oops that have references into the
 135   // current collection set.
 136   virtual bool refine_card(jbyte* card_ptr,
 137                            uint worker_i,
 138                            bool check_for_refs_into_cset);
 139 
 140   // Print accumulated summary info from the start of the VM.
 141   virtual void print_summary_info();
 142 
 143   // Print accumulated summary info from the last time called.
 144   virtual void print_periodic_summary_info(const char* header);
 145 
 146   // Prepare remembered set for verification.
 147   virtual void prepare_for_verify();
 148 
 149   size_t conc_refine_cards() const {
 150     return _conc_refine_cards;
 151   }
 152 };
 153 
 154 class UpdateRSOopClosure: public ExtendedOopClosure {
 155   HeapRegion* _from;
 156   G1RemSet* _rs;
 157   uint _worker_i;
 158 
 159   template <class T> void do_oop_work(T* p);
 160 
 161 public:
 162   UpdateRSOopClosure(G1RemSet* rs, uint worker_i = 0) :
 163     _from(NULL), _rs(rs), _worker_i(worker_i)
 164   {}
 165 
 166   void set_from(HeapRegion* from) {
 167     assert(from != NULL, "from region must be non-NULL");
 168     _from = from;
 169   }
 170 
 171   virtual void do_oop(narrowOop* p) { do_oop_work(p); }
 172   virtual void do_oop(oop* p)       { do_oop_work(p); }
 173 
 174   // Override: this closure is idempotent.
 175   //  bool idempotent() { return true; }
 176   bool apply_to_weak_ref_discovered_field() { return true; }
 177 };
 178 
 179 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_HPP