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 /*

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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_COLLECTIONSETCHOOSER_HPP

 #define SHARE_VM_GC_IMPLEMENTATION_G1_COLLECTIONSETCHOOSER_HPP

 #include "gc_implementation/g1/heapRegion.hpp"

 #include "utilities/growableArray.hpp"

 class CSetChooserCache VALUE_OBJ_CLASS_SPEC {

 private:

   enum {

     CacheLength = 16

   } PrivateConstants;

   HeapRegion*  _cache[CacheLength];

   int          _occupancy; // number of regions in cache

   int          _first;     // (index of) "first" region in the cache

   // adding CacheLength to deal with negative values

   inline int trim_index(int index) {

     return (index + CacheLength) % CacheLength;

   }

   inline int get_sort_index(int index) {

     return -index-2;

   }

   inline int get_index(int sort_index) {

     return -sort_index-2;

   }

 public:

   CSetChooserCache(void);

   inline int occupancy(void) { return _occupancy; }

   inline bool is_full()      { return _occupancy == CacheLength; }

   inline bool is_empty()     { return _occupancy == 0; }

   void clear(void);

   void insert(HeapRegion *hr);

   HeapRegion *remove_first(void);

   inline HeapRegion *get_first(void) {

     return _cache[_first];

   }

 #ifndef PRODUCT

   bool verify (void);

   bool region_in_cache(HeapRegion *hr) {

     int sort_index = hr->sort_index();

     if (sort_index < -1) {

       int index = get_index(sort_index);

       guarantee(index < CacheLength, "should be within bounds");

       return _cache[index] == hr;

     } else

       return 0;

   }

 #endif // PRODUCT

 };

 class CollectionSetChooser: public CHeapObj {

   GrowableArray<HeapRegion*> _markedRegions;

   // The index of the next candidate old region to be considered for

   // addition to the CSet.

   int _curr_index;

   // The number of candidate old regions added to the CSet chooser.

   int _length;

   CSetChooserCache _cache;

   jint _first_par_unreserved_idx;

   // If a region has more live bytes than this threshold, it will not

   // be added to the CSet chooser and will not be a candidate for

   // collection.

   size_t _regionLiveThresholdBytes;

   // The sum of reclaimable bytes over all the regions in the CSet chooser.

   size_t _remainingReclaimableBytes;

 public:

   // Return the current candidate region to be considered for

   // collection without removing it from the CSet chooser.

   HeapRegion* peek() {

     HeapRegion* res = NULL;

     if (_curr_index < _length) {

       res = _markedRegions.at(_curr_index);

       assert(res != NULL,

              err_msg("Unexpected NULL hr in _markedRegions at index %d",

                      _curr_index));

     }

     return res;

   }

   // Remove the given region from the CSet chooser and move to the

   // next one. The given region should be the current candidate region

   // in the CSet chooser.

   void remove_and_move_to_next(HeapRegion* hr) {

     assert(hr != NULL, "pre-condition");

     assert(_curr_index < _length, "pre-condition");

     assert(_markedRegions.at(_curr_index) == hr, "pre-condition");

     hr->set_sort_index(-1);

     _markedRegions.at_put(_curr_index, NULL);

     assert(hr->reclaimable_bytes() <= _remainingReclaimableBytes,

            err_msg("remaining reclaimable bytes inconsistent "

                    "from region: "SIZE_FORMAT" remaining: "SIZE_FORMAT,

                    hr->reclaimable_bytes(), _remainingReclaimableBytes));

     _remainingReclaimableBytes -= hr->reclaimable_bytes();

     _curr_index += 1;

   }

   CollectionSetChooser();

   void sortMarkedHeapRegions();

   void fillCache();

   // Determine whether to add the given region to the CSet chooser or

   // not. Currently, we skip humongous regions (we never add them to

   // the CSet, we only reclaim them during cleanup) and regions whose

   // live bytes are over the threshold.

   bool shouldAdd(HeapRegion* hr) {

     assert(hr->is_marked(), "pre-condition");

     assert(!hr->is_young(), "should never consider young regions");

     return !hr->isHumongous() &&

             hr->live_bytes() < _regionLiveThresholdBytes;

   }

   // Calculate the minimum number of old regions we'll add to the CSet

   // during a mixed GC.

   size_t calcMinOldCSetLength();

   // Calculate the maximum number of old regions we'll add to the CSet

   // during a mixed GC.

   size_t calcMaxOldCSetLength();

   // Serial version.

   void addMarkedHeapRegion(HeapRegion *hr);

   // Must be called before calls to getParMarkedHeapRegionChunk.

   // "n_regions" is the number of regions, "chunkSize" the chunk size.

   void prepareForAddMarkedHeapRegionsPar(size_t n_regions, size_t chunkSize);

   // Returns the first index in a contiguous chunk of "n_regions" indexes

   // that the calling thread has reserved.  These must be set by the

   // calling thread using "setMarkedHeapRegion" (to NULL if necessary).

   jint getParMarkedHeapRegionChunk(jint n_regions);

   // Set the marked array entry at index to hr.  Careful to claim the index

   // first if in parallel.

   void setMarkedHeapRegion(jint index, HeapRegion* hr);

   // Atomically increment the number of added regions by region_num

   // and the amount of reclaimable bytes by reclaimable_bytes.

   void updateTotals(jint region_num, size_t reclaimable_bytes);

   void clearMarkedHeapRegions();

   // Return the number of candidate regions that remain to be collected.

   size_t remainingRegions() { return _length - _curr_index; }

   // Determine whether the CSet chooser has more candidate regions or not.

   bool isEmpty() { return remainingRegions() == 0; }

   // Return the reclaimable bytes that remain to be collected on

   // all the candidate regions in the CSet chooser.

   size_t remainingReclaimableBytes () { return _remainingReclaimableBytes; }

   // Returns true if the used portion of "_markedRegions" is properly

   // sorted, otherwise asserts false.

 #ifndef PRODUCT

   bool verify(void);

   bool regionProperlyOrdered(HeapRegion* r) {

     int si = r->sort_index();

     if (si > -1) {

       guarantee(_curr_index <= si && si < _length,

                 err_msg("curr: %d sort index: %d: length: %d",

                         _curr_index, si, _length));

       guarantee(_markedRegions.at(si) == r,

                 err_msg("sort index: %d at: "PTR_FORMAT" r: "PTR_FORMAT,

                         si, _markedRegions.at(si), r));

     } else {

       guarantee(si == -1, err_msg("sort index: %d", si));

     }

     return true;

   }

 #endif

 };

 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_COLLECTIONSETCHOOSER_HPP