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_G1CARDLIVEDATA_HPP
  26 #define SHARE_VM_GC_G1_G1CARDLIVEDATA_HPP
  27 
  28 #include "gc/g1/g1CollectedHeap.hpp"
  29 #include "utilities/bitMap.hpp"
  30 #include "utilities/globalDefinitions.hpp"
  31 
  32 class G1CollectedHeap;
  33 class G1CMBitMap;
  34 class WorkGang;
  35 
  36 // Information about object liveness on the Java heap on a "card" basis.
  37 // Can be used for various purposes, like as remembered set for completely
  38 // coarsened remembered sets, scrubbing remembered sets or estimating liveness.
  39 // This information is created as part of the concurrent marking cycle.
  40 class G1CardLiveData VALUE_OBJ_CLASS_SPEC {
  41   friend class G1CardLiveDataHelper;
  42   friend class G1VerifyCardLiveDataTask;
  43 private:
  44   typedef BitMap::bm_word_t bm_word_t;
  45   // Store some additional information about the covered area to be able to test.
  46   size_t _max_capacity;
  47   size_t _cards_per_region;
  48 
  49   // Regions may be reclaimed while concurrently creating live data (e.g. due to humongous
  50   // eager reclaim). This results in wrong live data for these regions at the end.
  51   // So we need to somehow detect these regions, and during live data finalization completely
  52   // recreate their information.
  53   // This _gc_timestamp_at_create tracks the global timestamp when live data creation
  54   // has started. Any regions with a higher time stamp have been cleared after that
  55   // point in time, and need re-finalization.
  56   // Unsynchronized access to this variable is okay, since this value is only set during a
  57   // concurrent phase, and read only at the Cleanup safepoint. I.e. there is always
  58   // full memory synchronization inbetween.
  59   uint _gc_timestamp_at_create;
  60   // The per-card liveness bitmap.

  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_G1CARDLIVEDATA_HPP
  26 #define SHARE_VM_GC_G1_G1CARDLIVEDATA_HPP
  27 
  28 #include "gc/g1/g1CollectedHeap.hpp"
  29 #include "utilities/bitMap.hpp"
  30 #include "utilities/globalDefinitions.hpp"
  31 
  32 class G1CollectedHeap;
  33 class G1CMBitMap;
  34 class WorkGang;
  35 
  36 // Information about object liveness on the Java heap on a "card" basis.
  37 // Can be used for various purposes, like as remembered set for completely
  38 // coarsened remembered sets, scrubbing remembered sets or estimating liveness.
  39 // This information is created as part of the concurrent marking cycle.
  40 class G1CardLiveData {
  41   friend class G1CardLiveDataHelper;
  42   friend class G1VerifyCardLiveDataTask;
  43 private:
  44   typedef BitMap::bm_word_t bm_word_t;
  45   // Store some additional information about the covered area to be able to test.
  46   size_t _max_capacity;
  47   size_t _cards_per_region;
  48 
  49   // Regions may be reclaimed while concurrently creating live data (e.g. due to humongous
  50   // eager reclaim). This results in wrong live data for these regions at the end.
  51   // So we need to somehow detect these regions, and during live data finalization completely
  52   // recreate their information.
  53   // This _gc_timestamp_at_create tracks the global timestamp when live data creation
  54   // has started. Any regions with a higher time stamp have been cleared after that
  55   // point in time, and need re-finalization.
  56   // Unsynchronized access to this variable is okay, since this value is only set during a
  57   // concurrent phase, and read only at the Cleanup safepoint. I.e. there is always
  58   // full memory synchronization inbetween.
  59   uint _gc_timestamp_at_create;
  60   // The per-card liveness bitmap.