duke@435: /*
trims@1907:  * Copyright (c) 2001, 2008, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
duke@435: /*
duke@435:  * A binary tree based search structure for free blocks.
duke@435:  * This is currently used in the Concurrent Mark&Sweep implementation.
duke@435:  */
duke@435: 
duke@435: // A TreeList is a FreeList which can be used to maintain a
duke@435: // binary tree of free lists.
duke@435: 
duke@435: class TreeChunk;
duke@435: class BinaryTreeDictionary;
duke@435: class AscendTreeCensusClosure;
duke@435: class DescendTreeCensusClosure;
duke@435: class DescendTreeSearchClosure;
duke@435: 
duke@435: class TreeList: public FreeList {
duke@435:   friend class TreeChunk;
duke@435:   friend class BinaryTreeDictionary;
duke@435:   friend class AscendTreeCensusClosure;
duke@435:   friend class DescendTreeCensusClosure;
duke@435:   friend class DescendTreeSearchClosure;
duke@435: 
duke@435:  protected:
duke@435:   TreeList* parent() const { return _parent; }
duke@435:   TreeList* left()   const { return _left;   }
duke@435:   TreeList* right()  const { return _right;  }
duke@435: 
duke@435:   // Accessors for links in tree.
duke@435: 
duke@435:   void setLeft(TreeList* tl) {
duke@435:     _left   = tl;
duke@435:     if (tl != NULL)
duke@435:       tl->setParent(this);
duke@435:   }
duke@435:   void setRight(TreeList* tl) {
duke@435:     _right  = tl;
duke@435:     if (tl != NULL)
duke@435:       tl->setParent(this);
duke@435:   }
duke@435:   void setParent(TreeList* tl)  { _parent = tl;   }
duke@435: 
duke@435:   void clearLeft()               { _left = NULL;   }
duke@435:   void clearRight()              { _right = NULL;  }
duke@435:   void clearParent()             { _parent = NULL; }
duke@435:   void initialize()              { clearLeft(); clearRight(), clearParent(); }
duke@435: 
duke@435:   // For constructing a TreeList from a Tree chunk or
duke@435:   // address and size.
duke@435:   static TreeList* as_TreeList(TreeChunk* tc);
duke@435:   static TreeList* as_TreeList(HeapWord* addr, size_t size);
duke@435: 
duke@435:   // Returns the head of the free list as a pointer to a TreeChunk.
duke@435:   TreeChunk* head_as_TreeChunk();
duke@435: 
duke@435:   // Returns the first available chunk in the free list as a pointer
duke@435:   // to a TreeChunk.
duke@435:   TreeChunk* first_available();
duke@435: 
ysr@1580:   // Returns the block with the largest heap address amongst
ysr@1580:   // those in the list for this size; potentially slow and expensive,
ysr@1580:   // use with caution!
ysr@1580:   TreeChunk* largest_address();
ysr@1580: 
duke@435:   // removeChunkReplaceIfNeeded() removes the given "tc" from the TreeList.
duke@435:   // If "tc" is the first chunk in the list, it is also the
duke@435:   // TreeList that is the node in the tree.  removeChunkReplaceIfNeeded()
duke@435:   // returns the possibly replaced TreeList* for the node in
duke@435:   // the tree.  It also updates the parent of the original
duke@435:   // node to point to the new node.
duke@435:   TreeList* removeChunkReplaceIfNeeded(TreeChunk* tc);
duke@435:   // See FreeList.
duke@435:   void returnChunkAtHead(TreeChunk* tc);
duke@435:   void returnChunkAtTail(TreeChunk* tc);
duke@435: };
duke@435: 
duke@435: // A TreeChunk is a subclass of a FreeChunk that additionally
duke@435: // maintains a pointer to the free list on which it is currently
duke@435: // linked.
duke@435: // A TreeChunk is also used as a node in the binary tree.  This
duke@435: // allows the binary tree to be maintained without any additional
duke@435: // storage (the free chunks are used).  In a binary tree the first
duke@435: // chunk in the free list is also the tree node.  Note that the
duke@435: // TreeChunk has an embedded TreeList for this purpose.  Because
duke@435: // the first chunk in the list is distinguished in this fashion
duke@435: // (also is the node in the tree), it is the last chunk to be found
duke@435: // on the free list for a node in the tree and is only removed if
duke@435: // it is the last chunk on the free list.
duke@435: 
duke@435: class TreeChunk : public FreeChunk {
duke@435:   friend class TreeList;
duke@435:   TreeList* _list;
duke@435:   TreeList _embedded_list;  // if non-null, this chunk is on _list
duke@435:  protected:
duke@435:   TreeList* embedded_list() const { return (TreeList*) &_embedded_list; }
duke@435:   void set_embedded_list(TreeList* v) { _embedded_list = *v; }
duke@435:  public:
duke@435:   TreeList* list() { return _list; }
duke@435:   void set_list(TreeList* v) { _list = v; }
duke@435:   static TreeChunk* as_TreeChunk(FreeChunk* fc);
duke@435:   // Initialize fields in a TreeChunk that should be
duke@435:   // initialized when the TreeChunk is being added to
duke@435:   // a free list in the tree.
duke@435:   void initialize() { embedded_list()->initialize(); }
duke@435: 
duke@435:   // debugging
duke@435:   void verifyTreeChunkList() const;
duke@435: };
duke@435: 
duke@435: const size_t MIN_TREE_CHUNK_SIZE  = sizeof(TreeChunk)/HeapWordSize;
duke@435: 
duke@435: class BinaryTreeDictionary: public FreeBlockDictionary {
dcubed@587:   friend class VMStructs;
duke@435:   bool       _splay;
duke@435:   size_t     _totalSize;
duke@435:   size_t     _totalFreeBlocks;
duke@435:   TreeList* _root;
duke@435: 
duke@435:   // private accessors
duke@435:   bool splay() const { return _splay; }
duke@435:   void set_splay(bool v) { _splay = v; }
duke@435:   size_t totalSize() const { return _totalSize; }
duke@435:   void set_totalSize(size_t v) { _totalSize = v; }
duke@435:   virtual void inc_totalSize(size_t v);
duke@435:   virtual void dec_totalSize(size_t v);
duke@435:   size_t totalFreeBlocks() const { return _totalFreeBlocks; }
duke@435:   void set_totalFreeBlocks(size_t v) { _totalFreeBlocks = v; }
duke@435:   TreeList* root() const { return _root; }
duke@435:   void set_root(TreeList* v) { _root = v; }
duke@435: 
duke@435:   // Remove a chunk of size "size" or larger from the tree and
duke@435:   // return it.  If the chunk
duke@435:   // is the last chunk of that size, remove the node for that size
duke@435:   // from the tree.
duke@435:   TreeChunk* getChunkFromTree(size_t size, Dither dither, bool splay);
duke@435:   // Return a list of the specified size or NULL from the tree.
duke@435:   // The list is not removed from the tree.
duke@435:   TreeList* findList (size_t size) const;
duke@435:   // Remove this chunk from the tree.  If the removal results
duke@435:   // in an empty list in the tree, remove the empty list.
duke@435:   TreeChunk* removeChunkFromTree(TreeChunk* tc);
duke@435:   // Remove the node in the trees starting at tl that has the
duke@435:   // minimum value and return it.  Repair the tree as needed.
duke@435:   TreeList* removeTreeMinimum(TreeList* tl);
duke@435:   void       semiSplayStep(TreeList* tl);
duke@435:   // Add this free chunk to the tree.
duke@435:   void       insertChunkInTree(FreeChunk* freeChunk);
duke@435:  public:
duke@435:   void       verifyTree() const;
duke@435:   // verify that the given chunk is in the tree.
duke@435:   bool       verifyChunkInFreeLists(FreeChunk* tc) const;
duke@435:  private:
duke@435:   void          verifyTreeHelper(TreeList* tl) const;
duke@435:   static size_t verifyPrevFreePtrs(TreeList* tl);
duke@435: 
duke@435:   // Returns the total number of chunks in the list.
duke@435:   size_t     totalListLength(TreeList* tl) const;
duke@435:   // Returns the total number of words in the chunks in the tree
duke@435:   // starting at "tl".
duke@435:   size_t     totalSizeInTree(TreeList* tl) const;
duke@435:   // Returns the sum of the square of the size of each block
duke@435:   // in the tree starting at "tl".
duke@435:   double     sum_of_squared_block_sizes(TreeList* const tl) const;
duke@435:   // Returns the total number of free blocks in the tree starting
duke@435:   // at "tl".
duke@435:   size_t     totalFreeBlocksInTree(TreeList* tl) const;
duke@435:   size_t     numFreeBlocks() const;
duke@435:   size_t     treeHeight() const;
duke@435:   size_t     treeHeightHelper(TreeList* tl) const;
duke@435:   size_t     totalNodesInTree(TreeList* tl) const;
duke@435:   size_t     totalNodesHelper(TreeList* tl) const;
duke@435: 
duke@435:  public:
duke@435:   // Constructor
duke@435:   BinaryTreeDictionary(MemRegion mr, bool splay = false);
duke@435: 
duke@435:   // Reset the dictionary to the initial conditions with
duke@435:   // a single free chunk.
duke@435:   void       reset(MemRegion mr);
duke@435:   void       reset(HeapWord* addr, size_t size);
duke@435:   // Reset the dictionary to be empty.
duke@435:   void       reset();
duke@435: 
duke@435:   // Return a chunk of size "size" or greater from
duke@435:   // the tree.
duke@435:   // want a better dynamic splay strategy for the future.
duke@435:   FreeChunk* getChunk(size_t size, Dither dither) {
duke@435:     verify_par_locked();
duke@435:     FreeChunk* res = getChunkFromTree(size, dither, splay());
duke@435:     assert(res == NULL || res->isFree(),
duke@435:            "Should be returning a free chunk");
duke@435:     return res;
duke@435:   }
duke@435: 
duke@435:   void returnChunk(FreeChunk* chunk) {
duke@435:     verify_par_locked();
duke@435:     insertChunkInTree(chunk);
duke@435:   }
duke@435: 
duke@435:   void removeChunk(FreeChunk* chunk) {
duke@435:     verify_par_locked();
duke@435:     removeChunkFromTree((TreeChunk*)chunk);
duke@435:     assert(chunk->isFree(), "Should still be a free chunk");
duke@435:   }
duke@435: 
duke@435:   size_t     maxChunkSize() const;
duke@435:   size_t     totalChunkSize(debug_only(const Mutex* lock)) const {
duke@435:     debug_only(
duke@435:       if (lock != NULL && lock->owned_by_self()) {
duke@435:         assert(totalSizeInTree(root()) == totalSize(),
duke@435:                "_totalSize inconsistency");
duke@435:       }
duke@435:     )
duke@435:     return totalSize();
duke@435:   }
duke@435: 
duke@435:   size_t     minSize() const {
duke@435:     return MIN_TREE_CHUNK_SIZE;
duke@435:   }
duke@435: 
duke@435:   double     sum_of_squared_block_sizes() const {
duke@435:     return sum_of_squared_block_sizes(root());
duke@435:   }
duke@435: 
duke@435:   FreeChunk* find_chunk_ends_at(HeapWord* target) const;
duke@435: 
duke@435:   // Find the list with size "size" in the binary tree and update
duke@435:   // the statistics in the list according to "split" (chunk was
duke@435:   // split or coalesce) and "birth" (chunk was added or removed).
duke@435:   void       dictCensusUpdate(size_t size, bool split, bool birth);
duke@435:   // Return true if the dictionary is overpopulated (more chunks of
duke@435:   // this size than desired) for size "size".
duke@435:   bool       coalDictOverPopulated(size_t size);
duke@435:   // Methods called at the beginning of a sweep to prepare the
duke@435:   // statistics for the sweep.
duke@435:   void       beginSweepDictCensus(double coalSurplusPercent,
ysr@1580:                                   float inter_sweep_current,
ysr@1580:                                   float inter_sweep_estimate,
ysr@1580:                                   float intra_sweep_estimate);
duke@435:   // Methods called after the end of a sweep to modify the
duke@435:   // statistics for the sweep.
duke@435:   void       endSweepDictCensus(double splitSurplusPercent);
duke@435:   // Return the largest free chunk in the tree.
duke@435:   FreeChunk* findLargestDict() const;
duke@435:   // Accessors for statistics
duke@435:   void       setTreeSurplus(double splitSurplusPercent);
duke@435:   void       setTreeHints(void);
duke@435:   // Reset statistics for all the lists in the tree.
duke@435:   void       clearTreeCensus(void);
duke@435:   // Print the statistcis for all the lists in the tree.  Also may
duke@435:   // print out summaries.
duke@435:   void       printDictCensus(void) const;
ysr@1580:   void       print_free_lists(outputStream* st) const;
duke@435: 
duke@435:   // For debugging.  Returns the sum of the _returnedBytes for
duke@435:   // all lists in the tree.
duke@435:   size_t     sumDictReturnedBytes()     PRODUCT_RETURN0;
duke@435:   // Sets the _returnedBytes for all the lists in the tree to zero.
duke@435:   void       initializeDictReturnedBytes()      PRODUCT_RETURN;
duke@435:   // For debugging.  Return the total number of chunks in the dictionary.
duke@435:   size_t     totalCount()       PRODUCT_RETURN0;
duke@435: 
duke@435:   void       reportStatistics() const;
duke@435: 
duke@435:   void       verify() const;
duke@435: };