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 /*

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

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  * accompanied this code).

  *

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

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 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONMANAGER_HPP

 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONMANAGER_HPP

 #include "gc_implementation/g1/g1BiasedArray.hpp"

 #include "gc_implementation/g1/g1RegionToSpaceMapper.hpp"

 #include "gc_implementation/g1/heapRegionSet.hpp"

 class HeapRegion;

 class HeapRegionClosure;

 class FreeRegionList;

 class G1HeapRegionTable : public G1BiasedMappedArray<HeapRegion*> {

  protected:

   virtual HeapRegion* default_value() const { return NULL; }

 };

 // This class keeps track of the actual heap memory, auxiliary data

 // and its metadata (i.e., HeapRegion instances) and the list of free regions.

 //

 // This allows maximum flexibility for deciding what to commit or uncommit given

 // a request from outside.

 //

 // HeapRegions are kept in the _regions array in address order. A region's

 // index in the array corresponds to its index in the heap (i.e., 0 is the

 // region at the bottom of the heap, 1 is the one after it, etc.). Two

 // regions that are consecutive in the array should also be adjacent in the

 // address space (i.e., region(i).end() == region(i+1).bottom().

 //

 // We create a HeapRegion when we commit the region's address space

 // for the first time. When we uncommit the address space of a

 // region we retain the HeapRegion to be able to re-use it in the

 // future (in case we recommit it).

 //

 // We keep track of three lengths:

 //

 // * _num_committed (returned by length()) is the number of currently

 //   committed regions. These may not be contiguous.

 // * _allocated_heapregions_length (not exposed outside this class) is the

 //   number of regions+1 for which we have HeapRegions.

 // * max_length() returns the maximum number of regions the heap can have.

 //

 class HeapRegionManager: public CHeapObj<mtGC> {

   friend class VMStructs;

   G1HeapRegionTable _regions;

   G1RegionToSpaceMapper* _heap_mapper;

   G1RegionToSpaceMapper* _prev_bitmap_mapper;

   G1RegionToSpaceMapper* _next_bitmap_mapper;

   G1RegionToSpaceMapper* _bot_mapper;

   G1RegionToSpaceMapper* _cardtable_mapper;

   G1RegionToSpaceMapper* _card_counts_mapper;

   FreeRegionList _free_list;

   // Each bit in this bitmap indicates that the corresponding region is available

   // for allocation.

   BitMap _available_map;

    // The number of regions committed in the heap.

   uint _num_committed;

   // Internal only. The highest heap region +1 we allocated a HeapRegion instance for.

   uint _allocated_heapregions_length;

    HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); }

    HeapWord* heap_end() const {return _regions.end_address_mapped(); }

   void make_regions_available(uint index, uint num_regions = 1);

   // Pass down commit calls to the VirtualSpace.

   void commit_regions(uint index, size_t num_regions = 1);

   void uncommit_regions(uint index, size_t num_regions = 1);

   // Notify other data structures about change in the heap layout.

   void update_committed_space(HeapWord* old_end, HeapWord* new_end);

   // Calculate the starting region for each worker during parallel iteration so

   // that they do not all start from the same region.

   uint start_region_for_worker(uint worker_i, uint num_workers, uint num_regions) const;

   // Find a contiguous set of empty or uncommitted regions of length num and return

   // the index of the first region or G1_NO_HRM_INDEX if the search was unsuccessful.

   // If only_empty is true, only empty regions are considered.

   // Searches from bottom to top of the heap, doing a first-fit.

   uint find_contiguous(size_t num, bool only_empty);

   // Finds the next sequence of unavailable regions starting from start_idx. Returns the

   // length of the sequence found. If this result is zero, no such sequence could be found,

   // otherwise res_idx indicates the start index of these regions.

   uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const;

   // Finds the next sequence of empty regions starting from start_idx, going backwards in

   // the heap. Returns the length of the sequence found. If this value is zero, no

   // sequence could be found, otherwise res_idx contains the start index of this range.

   uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const;

   // Allocate a new HeapRegion for the given index.

   HeapRegion* new_heap_region(uint hrm_index);

 #ifdef ASSERT

 public:

   bool is_free(HeapRegion* hr) const;

 #endif

   // Returns whether the given region is available for allocation.

   bool is_available(uint region) const;

  public:

   // Empty constructor, we'll initialize it with the initialize() method.

   HeapRegionManager() : _regions(), _heap_mapper(NULL), _num_committed(0),

                     _next_bitmap_mapper(NULL), _prev_bitmap_mapper(NULL), _bot_mapper(NULL),

                     _allocated_heapregions_length(0), _available_map(),

                     _free_list("Free list", new MasterFreeRegionListMtSafeChecker())

   { }

   void initialize(G1RegionToSpaceMapper* heap_storage,

                   G1RegionToSpaceMapper* prev_bitmap,

                   G1RegionToSpaceMapper* next_bitmap,

                   G1RegionToSpaceMapper* bot,

                   G1RegionToSpaceMapper* cardtable,

                   G1RegionToSpaceMapper* card_counts);

   // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired

   // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit

   // the heap from the lowest address, this region (and its associated data

   // structures) are available and we do not need to check further.

   HeapRegion* get_dummy_region() { return new_heap_region(0); }

   // Return the HeapRegion at the given index. Assume that the index

   // is valid.

   inline HeapRegion* at(uint index) const;

   // If addr is within the committed space return its corresponding

   // HeapRegion, otherwise return NULL.

   inline HeapRegion* addr_to_region(HeapWord* addr) const;

   // Insert the given region into the free region list.

   inline void insert_into_free_list(HeapRegion* hr);

   // Insert the given region list into the global free region list.

   void insert_list_into_free_list(FreeRegionList* list) {

     _free_list.add_ordered(list);

   }

   HeapRegion* allocate_free_region(bool is_old) {

     HeapRegion* hr = _free_list.remove_region(is_old);

     if (hr != NULL) {

       assert(hr->next() == NULL, "Single region should not have next");

       assert(is_available(hr->hrm_index()), "Must be committed");

     }

     return hr;

   }

   inline void allocate_free_regions_starting_at(uint first, uint num_regions);

   // Remove all regions from the free list.

   void remove_all_free_regions() {

     _free_list.remove_all();

   }

   // Return the number of committed free regions in the heap.

   uint num_free_regions() const {

     return _free_list.length();

   }

   size_t total_capacity_bytes() const {

     return num_free_regions() * HeapRegion::GrainBytes;

   }

   // Return the number of available (uncommitted) regions.

   uint available() const { return max_length() - length(); }

   // Return the number of regions that have been committed in the heap.

   uint length() const { return _num_committed; }

   // Return the maximum number of regions in the heap.

   uint max_length() const { return (uint)_regions.length(); }

   MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); }

   // Expand the sequence to reflect that the heap has grown. Either create new

   // HeapRegions, or re-use existing ones. Returns the number of regions the

   // sequence was expanded by. If a HeapRegion allocation fails, the resulting

   // number of regions might be smaller than what's desired.

   uint expand_by(uint num_regions);

   // Makes sure that the regions from start to start+num_regions-1 are available

   // for allocation. Returns the number of regions that were committed to achieve

   // this.

   uint expand_at(uint start, uint num_regions);

   // Find a contiguous set of empty regions of length num. Returns the start index of

   // that set, or G1_NO_HRM_INDEX.

   uint find_contiguous_only_empty(size_t num) { return find_contiguous(num, true); }

   // Find a contiguous set of empty or unavailable regions of length num. Returns the

   // start index of that set, or G1_NO_HRM_INDEX.

   uint find_contiguous_empty_or_unavailable(size_t num) { return find_contiguous(num, false); }

   HeapRegion* next_region_in_heap(const HeapRegion* r) const;

   // Apply blk->doHeapRegion() on all committed regions in address order,

   // terminating the iteration early if doHeapRegion() returns true.

   void iterate(HeapRegionClosure* blk) const;

   void par_iterate(HeapRegionClosure* blk, uint worker_id, uint no_of_par_workers, jint claim_value) const;

   // Uncommit up to num_regions_to_remove regions that are completely free.

   // Return the actual number of uncommitted regions.

   uint shrink_by(uint num_regions_to_remove);

   void verify();

   // Do some sanity checking.

   void verify_optional() PRODUCT_RETURN;

 };

 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONMANAGER_HPP