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

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 *

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 * 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).

 *

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#ifndef SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP

#define SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP

#include "gc/g1/g1BiasedArray.hpp"

#include "gc/g1/g1RegionToSpaceMapper.hpp"

#include "gc/g1/heapRegionSet.hpp"

#include "services/memoryUsage.hpp"

class HeapRegion;

class HeapRegionClosure;

class HeapRegionClaimer;

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;

  friend class HeapRegionClaimer;

  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);

  // 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;

  // Return the next region (by index) that is part of the same

  // humongous object that hr is part of.

  inline HeapRegion* next_region_in_humongous(HeapRegion* hr) 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(); }

  MemoryUsage get_auxiliary_data_memory_usage() const;

  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;

  // Find the highest free or uncommitted region in the reserved heap,

  // and if uncommitted, commit it. If none are available, return G1_NO_HRM_INDEX.

  // Set the 'expanded' boolean true if a new region was committed.

  uint find_highest_free(bool* expanded);

  // Allocate the regions that contain the address range specified, committing the

  // regions if necessary. Return false if any of the regions is already committed

  // and not free, and return the number of regions newly committed in commit_count.

  bool allocate_containing_regions(MemRegion range, size_t* commit_count);

  // 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, HeapRegionClaimer* hrclaimer, bool concurrent) 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);

  // Uncommit a number of regions starting at the specified index, which must be available,

  // empty, and free.

  void shrink_at(uint index, size_t num_regions);

  void verify();

  // Do some sanity checking.

  void verify_optional() PRODUCT_RETURN;

};

// The HeapRegionClaimer is used during parallel iteration over heap regions,

// allowing workers to claim heap regions, gaining exclusive rights to these regions.

class HeapRegionClaimer : public StackObj {

  uint  _n_workers;

  uint  _n_regions;

  uint* _claims;

  static const uint Unclaimed = 0;

  static const uint Claimed   = 1;

 public:

  HeapRegionClaimer(uint n_workers);

  ~HeapRegionClaimer();

  inline uint n_regions() const {

    return _n_regions;

  }

  // Calculate the starting region for given worker so

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

  uint start_region_for_worker(uint worker_id) const;

  // Check if region has been claimed with this HRClaimer.

  bool is_region_claimed(uint region_index) const;

  // Claim the given region, returns true if successfully claimed.

  bool claim_region(uint region_index);

};

#endif // SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP