91 class YoungList : public CHeapObj<mtGC> {

    92 private:

    93   G1CollectedHeap* _g1h;

    94 

    95   HeapRegion* _head;

    96 

    97   HeapRegion* _survivor_head;

    98   HeapRegion* _survivor_tail;

    99 

   100   HeapRegion* _curr;

   101 

   102   uint        _length;

   103   uint        _survivor_length;

   104 

   105   size_t      _last_sampled_rs_lengths;

   106   size_t      _sampled_rs_lengths;

   107 

   108   void         empty_list(HeapRegion* list);

   109 

   110 public:

   111   YoungList(G1CollectedHeap* g1h);

   112 

   113   void         push_region(HeapRegion* hr);

   114   void         add_survivor_region(HeapRegion* hr);

   115 

   116   void         empty_list();

   117   bool         is_empty() { return _length == 0; }

   118   uint         length() { return _length; }

   119   uint         eden_length() { return length() - survivor_length(); }

   120   uint         survivor_length() { return _survivor_length; }

   121 

   122   // Currently we do not keep track of the used byte sum for the

   123   // young list and the survivors and it'd be quite a lot of work to

   124   // do so. When we'll eventually replace the young list with

   125   // instances of HeapRegionLinkedList we'll get that for free. So,

   126   // we'll report the more accurate information then.

   127   size_t       eden_used_bytes() {

   128     assert(length() >= survivor_length(), "invariant");

   129     return (size_t) eden_length() * HeapRegion::GrainBytes;

   130   }

   131   size_t       survivor_used_bytes() {

   132     return (size_t) survivor_length() * HeapRegion::GrainBytes;

   133   }

   134 

   135   void rs_length_sampling_init();

   136   bool rs_length_sampling_more();

   137   void rs_length_sampling_next();

   138 

   139   void reset_sampled_info() {

   140     _last_sampled_rs_lengths =   0;

   141   }

   142   size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; }

   143 

   144   // for development purposes

   145   void reset_auxilary_lists();

   146   void clear() { _head = NULL; _length = 0; }

   147 

   148   void clear_survivors() {

   149     _survivor_head    = NULL;

   150     _survivor_tail    = NULL;

   151     _survivor_length  = 0;

   152   }

   153 

   154   HeapRegion* first_region() { return _head; }

   155   HeapRegion* first_survivor_region() { return _survivor_head; }

   156   HeapRegion* last_survivor_region() { return _survivor_tail; }

   157 

   158   // debugging

   159   bool          check_list_well_formed();

   160   bool          check_list_empty(bool check_sample = true);

   161   void          print();

   162 };

   163