Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 2001-2008 Sun Microsystems, Inc.  All Rights Reserved.

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

  *

  * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

  * have any questions.

  *

  */

 /*

  * A binary tree based search structure for free blocks.

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

  */

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

 // binary tree of free lists.

 class TreeChunk;

 class BinaryTreeDictionary;

 class AscendTreeCensusClosure;

 class DescendTreeCensusClosure;

 class DescendTreeSearchClosure;

 class TreeList: public FreeList {

   friend class TreeChunk;

   friend class BinaryTreeDictionary;

   friend class AscendTreeCensusClosure;

   friend class DescendTreeCensusClosure;

   friend class DescendTreeSearchClosure;

  protected:

   TreeList* parent() const { return _parent; }

   TreeList* left()   const { return _left;   }

   TreeList* right()  const { return _right;  }

   // Accessors for links in tree.

   void setLeft(TreeList* tl) {

     _left   = tl;

     if (tl != NULL)

       tl->setParent(this);

   }

   void setRight(TreeList* tl) {

     _right  = tl;

     if (tl != NULL)

       tl->setParent(this);

   }

   void setParent(TreeList* tl)  { _parent = tl;   }

   void clearLeft()               { _left = NULL;   }

   void clearRight()              { _right = NULL;  }

   void clearParent()             { _parent = NULL; }

   void initialize()              { clearLeft(); clearRight(), clearParent(); }

   // For constructing a TreeList from a Tree chunk or

   // address and size.

   static TreeList* as_TreeList(TreeChunk* tc);

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

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

   TreeChunk* head_as_TreeChunk();

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

   // to a TreeChunk.

   TreeChunk* 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* largest_address();

   // removeChunkReplaceIfNeeded() 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.  removeChunkReplaceIfNeeded()

   // 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* removeChunkReplaceIfNeeded(TreeChunk* tc);

   // See FreeList.

   void returnChunkAtHead(TreeChunk* tc);

   void returnChunkAtTail(TreeChunk* tc);

 };

 // A TreeChunk is a subclass of a FreeChunk 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.

 class TreeChunk : public FreeChunk {

   friend class TreeList;

   TreeList* _list;

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

  protected:

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

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

  public:

   TreeList* list() { return _list; }

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

   static TreeChunk* as_TreeChunk(FreeChunk* 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(); }

   // debugging

   void verifyTreeChunkList() const;

 };

 const size_t MIN_TREE_CHUNK_SIZE  = sizeof(TreeChunk)/HeapWordSize;

 class BinaryTreeDictionary: public FreeBlockDictionary {

   friend class VMStructs;

   bool       _splay;

   size_t     _totalSize;

   size_t     _totalFreeBlocks;

   TreeList* _root;

   // private accessors

   bool splay() const { return _splay; }

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

   size_t totalSize() const { return _totalSize; }

   void set_totalSize(size_t v) { _totalSize = v; }

   virtual void inc_totalSize(size_t v);

   virtual void dec_totalSize(size_t v);

   size_t totalFreeBlocks() const { return _totalFreeBlocks; }

   void set_totalFreeBlocks(size_t v) { _totalFreeBlocks = v; }

   TreeList* root() const { return _root; }

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

   // 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* getChunkFromTree(size_t size, 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* findList (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* removeChunkFromTree(TreeChunk* tc);

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

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

   TreeList* removeTreeMinimum(TreeList* tl);

   void       semiSplayStep(TreeList* tl);

   // Add this free chunk to the tree.

   void       insertChunkInTree(FreeChunk* freeChunk);

  public:

   void       verifyTree() const;

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

   bool       verifyChunkInFreeLists(FreeChunk* tc) const;

  private:

   void          verifyTreeHelper(TreeList* tl) const;

   static size_t verifyPrevFreePtrs(TreeList* tl);

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

   size_t     totalListLength(TreeList* tl) const;

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

   // starting at "tl".

   size_t     totalSizeInTree(TreeList* 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* const tl) const;

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

   // at "tl".

   size_t     totalFreeBlocksInTree(TreeList* tl) const;

   size_t     numFreeBlocks() const;

   size_t     treeHeight() const;

   size_t     treeHeightHelper(TreeList* tl) const;

   size_t     totalNodesInTree(TreeList* tl) const;

   size_t     totalNodesHelper(TreeList* tl) const;

  public:

   // Constructor

   BinaryTreeDictionary(MemRegion mr, bool splay = false);

   // 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.

   FreeChunk* getChunk(size_t size, Dither dither) {

     verify_par_locked();

     FreeChunk* res = getChunkFromTree(size, dither, splay());

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

            "Should be returning a free chunk");

     return res;

   }

   void returnChunk(FreeChunk* chunk) {

     verify_par_locked();

     insertChunkInTree(chunk);

   }

   void removeChunk(FreeChunk* chunk) {

     verify_par_locked();

     removeChunkFromTree((TreeChunk*)chunk);

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

   }

   size_t     maxChunkSize() const;

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

     debug_only(

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

         assert(totalSizeInTree(root()) == totalSize(),

                "_totalSize inconsistency");

       }

     )

     return totalSize();

   }

   size_t     minSize() const {

     return MIN_TREE_CHUNK_SIZE;

   }

   double     sum_of_squared_block_sizes() const {

     return sum_of_squared_block_sizes(root());

   }

   FreeChunk* 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       dictCensusUpdate(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       coalDictOverPopulated(size_t size);

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

   // statistics for the sweep.

   void       beginSweepDictCensus(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       endSweepDictCensus(double splitSurplusPercent);

   // Return the largest free chunk in the tree.

   FreeChunk* findLargestDict() const;

   // Accessors for statistics

   void       setTreeSurplus(double splitSurplusPercent);

   void       setTreeHints(void);

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

   void       clearTreeCensus(void);

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

   // print out summaries.

   void       printDictCensus(void) const;

   void       print_free_lists(outputStream* st) const;

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

   // all lists in the tree.

   size_t     sumDictReturnedBytes()     PRODUCT_RETURN0;

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

   void       initializeDictReturnedBytes()      PRODUCT_RETURN;

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

   size_t     totalCount()       PRODUCT_RETURN0;

   void       reportStatistics() const;

   void       verify() const;

 };