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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

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  * published by the Free Software Foundation.

  *

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  * 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_MEMORY_BINARYTREEDICTIONARY_HPP

 #define SHARE_VM_MEMORY_BINARYTREEDICTIONARY_HPP

 #include "memory/freeBlockDictionary.hpp"

 #include "memory/freeList.hpp"

 /*

  * A binary tree based search structure for free blocks.

  * This is currently used in the Concurrent Mark&Sweep implementation, but

  * will be used for free block management for metadata.

  */

 // A TreeList is a FreeList which can be used to maintain a

 // binary tree of free lists.

 template <class Chunk> class TreeChunk;

 template <class Chunk> class BinaryTreeDictionary;

 template <class Chunk> class AscendTreeCensusClosure;

 template <class Chunk> class DescendTreeCensusClosure;

 template <class Chunk> class DescendTreeSearchClosure;

 template <class Chunk>

 class TreeList: public FreeList<Chunk> {

   friend class TreeChunk<Chunk>;

   friend class BinaryTreeDictionary<Chunk>;

   friend class AscendTreeCensusClosure<Chunk>;

   friend class DescendTreeCensusClosure<Chunk>;

   friend class DescendTreeSearchClosure<Chunk>;

   TreeList<Chunk>* _parent;

   TreeList<Chunk>* _left;

   TreeList<Chunk>* _right;

  protected:

   TreeList<Chunk>* parent() const { return _parent; }

   TreeList<Chunk>* left()   const { return _left;   }

   TreeList<Chunk>* right()  const { return _right;  }

   // Wrapper on call to base class, to get the template to compile.

   Chunk* head() const { return FreeList<Chunk>::head(); }

   Chunk* tail() const { return FreeList<Chunk>::tail(); }

   void set_head(Chunk* head) { FreeList<Chunk>::set_head(head); }

   void set_tail(Chunk* tail) { FreeList<Chunk>::set_tail(tail); }

   size_t size() const { return FreeList<Chunk>::size(); }

   // Accessors for links in tree.

   void set_left(TreeList<Chunk>* tl) {

     _left   = tl;

     if (tl != NULL)

       tl->set_parent(this);

   }

   void set_right(TreeList<Chunk>* tl) {

     _right  = tl;

     if (tl != NULL)

       tl->set_parent(this);

   }

   void set_parent(TreeList<Chunk>* tl)  { _parent = tl;   }

   void clearLeft()               { _left = NULL;   }

   void clear_right()              { _right = NULL;  }

   void clear_parent()             { _parent = NULL; }

   void initialize()              { clearLeft(); clear_right(), clear_parent(); }

   // For constructing a TreeList from a Tree chunk or

   // address and size.

   static TreeList<Chunk>* as_TreeList(TreeChunk<Chunk>* tc);

   static TreeList<Chunk>* as_TreeList(HeapWord* addr, size_t size);

   // Returns the head of the free list as a pointer to a TreeChunk.

   TreeChunk<Chunk>* head_as_TreeChunk();

   // Returns the first available chunk in the free list as a pointer

   // to a TreeChunk.

   TreeChunk<Chunk>* first_available();

   // Returns the block with the largest heap address amongst

   // those in the list for this size; potentially slow and expensive,

   // use with caution!

   TreeChunk<Chunk>* largest_address();

   // remove_chunk_replace_if_needed() removes the given "tc" from the TreeList.

   // If "tc" is the first chunk in the list, it is also the

   // TreeList that is the node in the tree.  remove_chunk_replace_if_needed()

   // returns the possibly replaced TreeList* for the node in

   // the tree.  It also updates the parent of the original

   // node to point to the new node.

   TreeList<Chunk>* remove_chunk_replace_if_needed(TreeChunk<Chunk>* tc);

   // See FreeList.

   void return_chunk_at_head(TreeChunk<Chunk>* tc);

   void return_chunk_at_tail(TreeChunk<Chunk>* tc);

 };

 // A TreeChunk is a subclass of a Chunk that additionally

 // maintains a pointer to the free list on which it is currently

 // linked.

 // A TreeChunk is also used as a node in the binary tree.  This

 // allows the binary tree to be maintained without any additional

 // storage (the free chunks are used).  In a binary tree the first

 // chunk in the free list is also the tree node.  Note that the

 // TreeChunk has an embedded TreeList for this purpose.  Because

 // the first chunk in the list is distinguished in this fashion

 // (also is the node in the tree), it is the last chunk to be found

 // on the free list for a node in the tree and is only removed if

 // it is the last chunk on the free list.

 template <class Chunk>

 class TreeChunk : public Chunk {

   friend class TreeList<Chunk>;

   TreeList<Chunk>* _list;

   TreeList<Chunk> _embedded_list;  // if non-null, this chunk is on _list

  protected:

   TreeList<Chunk>* embedded_list() const { return (TreeList<Chunk>*) &_embedded_list; }

   void set_embedded_list(TreeList<Chunk>* v) { _embedded_list = *v; }

  public:

   TreeList<Chunk>* list() { return _list; }

   void set_list(TreeList<Chunk>* v) { _list = v; }

   static TreeChunk<Chunk>* as_TreeChunk(Chunk* fc);

   // Initialize fields in a TreeChunk that should be

   // initialized when the TreeChunk is being added to

   // a free list in the tree.

   void initialize() { embedded_list()->initialize(); }

   Chunk* next() const { return Chunk::next(); }

   Chunk* prev() const { return Chunk::prev(); }

   size_t size() const volatile { return Chunk::size(); }

   // debugging

   void verify_tree_chunk_list() const;

 };

 template <class Chunk>

 class BinaryTreeDictionary: public FreeBlockDictionary<Chunk> {

   friend class VMStructs;

   bool       _splay;

   size_t     _total_size;

   size_t     _total_free_blocks;

   TreeList<Chunk>* _root;

   bool       _adaptive_freelists;

   // private accessors

   bool splay() const { return _splay; }

   void set_splay(bool v) { _splay = v; }

   void set_total_size(size_t v) { _total_size = v; }

   virtual void inc_total_size(size_t v);

   virtual void dec_total_size(size_t v);

   size_t total_free_blocks() const { return _total_free_blocks; }

   void set_total_free_blocks(size_t v) { _total_free_blocks = v; }

   TreeList<Chunk>* root() const { return _root; }

   void set_root(TreeList<Chunk>* v) { _root = v; }

   bool adaptive_freelists() { return _adaptive_freelists; }

   // This field is added and can be set to point to the

   // the Mutex used to synchronize access to the

   // dictionary so that assertion checking can be done.

   // For example it is set to point to _parDictionaryAllocLock.

   NOT_PRODUCT(Mutex* _lock;)

   // Remove a chunk of size "size" or larger from the tree and

   // return it.  If the chunk

   // is the last chunk of that size, remove the node for that size

   // from the tree.

   TreeChunk<Chunk>* get_chunk_from_tree(size_t size, enum FreeBlockDictionary<Chunk>::Dither dither, bool splay);

   // Return a list of the specified size or NULL from the tree.

   // The list is not removed from the tree.

   TreeList<Chunk>* find_list (size_t size) const;

   // Remove this chunk from the tree.  If the removal results

   // in an empty list in the tree, remove the empty list.

   TreeChunk<Chunk>* remove_chunk_from_tree(TreeChunk<Chunk>* tc);

   // Remove the node in the trees starting at tl that has the

   // minimum value and return it.  Repair the tree as needed.

   TreeList<Chunk>* remove_tree_minimum(TreeList<Chunk>* tl);

   void       semi_splay_step(TreeList<Chunk>* tl);

   // Add this free chunk to the tree.

   void       insert_chunk_in_tree(Chunk* freeChunk);

  public:

   static const size_t min_tree_chunk_size  = sizeof(TreeChunk<Chunk>)/HeapWordSize;

   void       verify_tree() const;

   // verify that the given chunk is in the tree.

   bool       verify_chunk_in_free_list(Chunk* tc) const;

  private:

   void          verify_tree_helper(TreeList<Chunk>* tl) const;

   static size_t verify_prev_free_ptrs(TreeList<Chunk>* tl);

   // Returns the total number of chunks in the list.

   size_t     total_list_length(TreeList<Chunk>* tl) const;

   // Returns the total number of words in the chunks in the tree

   // starting at "tl".

   size_t     total_size_in_tree(TreeList<Chunk>* tl) const;

   // Returns the sum of the square of the size of each block

   // in the tree starting at "tl".

   double     sum_of_squared_block_sizes(TreeList<Chunk>* const tl) const;

   // Returns the total number of free blocks in the tree starting

   // at "tl".

   size_t     total_free_blocks_in_tree(TreeList<Chunk>* tl) const;

   size_t     num_free_blocks() const;

   size_t     treeHeight() const;

   size_t     tree_height_helper(TreeList<Chunk>* tl) const;

   size_t     total_nodes_in_tree(TreeList<Chunk>* tl) const;

   size_t     total_nodes_helper(TreeList<Chunk>* tl) const;

  public:

   // Constructor

   BinaryTreeDictionary(bool adaptive_freelists, bool splay = false);

   BinaryTreeDictionary(MemRegion mr, bool adaptive_freelists, bool splay = false);

   // Public accessors

   size_t total_size() const { return _total_size; }

   // Reset the dictionary to the initial conditions with

   // a single free chunk.

   void       reset(MemRegion mr);

   void       reset(HeapWord* addr, size_t size);

   // Reset the dictionary to be empty.

   void       reset();

   // Return a chunk of size "size" or greater from

   // the tree.

   // want a better dynamic splay strategy for the future.

   Chunk* get_chunk(size_t size, enum FreeBlockDictionary<Chunk>::Dither dither) {

     FreeBlockDictionary<Chunk>::verify_par_locked();

     Chunk* res = get_chunk_from_tree(size, dither, splay());

     assert(res == NULL || res->is_free(),

            "Should be returning a free chunk");

     return res;

   }

   void return_chunk(Chunk* chunk) {

     FreeBlockDictionary<Chunk>::verify_par_locked();

     insert_chunk_in_tree(chunk);

   }

   void remove_chunk(Chunk* chunk) {

     FreeBlockDictionary<Chunk>::verify_par_locked();

     remove_chunk_from_tree((TreeChunk<Chunk>*)chunk);

     assert(chunk->is_free(), "Should still be a free chunk");

   }

   size_t     max_chunk_size() const;

   size_t     total_chunk_size(debug_only(const Mutex* lock)) const {

     debug_only(

       if (lock != NULL && lock->owned_by_self()) {

         assert(total_size_in_tree(root()) == total_size(),

                "_total_size inconsistency");

       }

     )

     return total_size();

   }

   size_t     min_size() const {

     return min_tree_chunk_size;

   }

   double     sum_of_squared_block_sizes() const {

     return sum_of_squared_block_sizes(root());

   }

   Chunk* find_chunk_ends_at(HeapWord* target) const;

   // Find the list with size "size" in the binary tree and update

   // the statistics in the list according to "split" (chunk was

   // split or coalesce) and "birth" (chunk was added or removed).

   void       dict_census_udpate(size_t size, bool split, bool birth);

   // Return true if the dictionary is overpopulated (more chunks of

   // this size than desired) for size "size".

   bool       coal_dict_over_populated(size_t size);

   // Methods called at the beginning of a sweep to prepare the

   // statistics for the sweep.

   void       begin_sweep_dict_census(double coalSurplusPercent,

                                   float inter_sweep_current,

                                   float inter_sweep_estimate,

                                   float intra_sweep_estimate);

   // Methods called after the end of a sweep to modify the

   // statistics for the sweep.

   void       end_sweep_dict_census(double splitSurplusPercent);

   // Return the largest free chunk in the tree.

   Chunk* find_largest_dict() const;

   // Accessors for statistics

   void       set_tree_surplus(double splitSurplusPercent);

   void       set_tree_hints(void);

   // Reset statistics for all the lists in the tree.

   void       clear_tree_census(void);

   // Print the statistcis for all the lists in the tree.  Also may

   // print out summaries.

   void       print_dict_census(void) const;

   void       print_free_lists(outputStream* st) const;

   // For debugging.  Returns the sum of the _returned_bytes for

   // all lists in the tree.

   size_t     sum_dict_returned_bytes()     PRODUCT_RETURN0;

   // Sets the _returned_bytes for all the lists in the tree to zero.

   void       initialize_dict_returned_bytes()      PRODUCT_RETURN;

   // For debugging.  Return the total number of chunks in the dictionary.

   size_t     total_count()       PRODUCT_RETURN0;

   void       report_statistics() const;

   void       verify() const;

 };

 #endif // SHARE_VM_MEMORY_BINARYTREEDICTIONARY_HPP