1 /*

     2  * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.

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

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

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

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #ifndef SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_BINARYTREEDICTIONARY_HPP

    26 #define SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_BINARYTREEDICTIONARY_HPP

    27 

    28 #include "gc_implementation/concurrentMarkSweep/freeBlockDictionary.hpp"

    29 #include "gc_implementation/concurrentMarkSweep/freeList.hpp"

    30 

    31 /*

    32  * A binary tree based search structure for free blocks.

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

    34  */

    35 

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

    37 // binary tree of free lists.

    38 

    39 class TreeChunk;

    40 class BinaryTreeDictionary;

    41 class AscendTreeCensusClosure;

    42 class DescendTreeCensusClosure;

    43 class DescendTreeSearchClosure;

    44 

    45 class TreeList: public FreeList {

    46   friend class TreeChunk;

    47   friend class BinaryTreeDictionary;

    48   friend class AscendTreeCensusClosure;

    49   friend class DescendTreeCensusClosure;

    50   friend class DescendTreeSearchClosure;

    51 

    52  protected:

    53   TreeList* parent() const { return _parent; }

    54   TreeList* left()   const { return _left;   }

    55   TreeList* right()  const { return _right;  }

    56 

    57   // Accessors for links in tree.

    58 

    59   void setLeft(TreeList* tl) {

    60     _left   = tl;

    61     if (tl != NULL)

    62       tl->setParent(this);

    63   }

    64   void setRight(TreeList* tl) {

    65     _right  = tl;

    66     if (tl != NULL)

    67       tl->setParent(this);

    68   }

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

    70 

    71   void clearLeft()               { _left = NULL;   }

    72   void clearRight()              { _right = NULL;  }

    73   void clearParent()             { _parent = NULL; }

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

    75 

    76   // For constructing a TreeList from a Tree chunk or

    77   // address and size.

    78   static TreeList* as_TreeList(TreeChunk* tc);

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

    80 

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

    82   TreeChunk* head_as_TreeChunk();

    83 

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

    85   // to a TreeChunk.

    86   TreeChunk* first_available();

    87 

    88   // Returns the block with the largest heap address amongst

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

    90   // use with caution!

    91   TreeChunk* largest_address();

    92 

    93   // removeChunkReplaceIfNeeded() removes the given "tc" from the TreeList.

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

    95   // TreeList that is the node in the tree.  removeChunkReplaceIfNeeded()

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

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

    98   // node to point to the new node.

    99   TreeList* removeChunkReplaceIfNeeded(TreeChunk* tc);

   100   // See FreeList.

   101   void returnChunkAtHead(TreeChunk* tc);

   102   void returnChunkAtTail(TreeChunk* tc);

   103 };

   104 

   105 // A TreeChunk is a subclass of a FreeChunk that additionally

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

   107 // linked.

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

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

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

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

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

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

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

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

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

   117 

   118 class TreeChunk : public FreeChunk {

   119   friend class TreeList;

   120   TreeList* _list;

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

   122  protected:

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

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

   125  public:

   126   TreeList* list() { return _list; }

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

   128   static TreeChunk* as_TreeChunk(FreeChunk* fc);

   129   // Initialize fields in a TreeChunk that should be

   130   // initialized when the TreeChunk is being added to

   131   // a free list in the tree.

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

   133 

   134   // debugging

   135   void verifyTreeChunkList() const;

   136 };

   137 

   138 const size_t MIN_TREE_CHUNK_SIZE  = sizeof(TreeChunk)/HeapWordSize;

   139 

   140 class BinaryTreeDictionary: public FreeBlockDictionary {

   141   friend class VMStructs;

   142   bool       _splay;

   143   size_t     _totalSize;

   144   size_t     _totalFreeBlocks;

   145   TreeList* _root;

   146 

   147   // private accessors

   148   bool splay() const { return _splay; }

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

   150   size_t totalSize() const { return _totalSize; }

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

   152   virtual void inc_totalSize(size_t v);

   153   virtual void dec_totalSize(size_t v);

   154   size_t totalFreeBlocks() const { return _totalFreeBlocks; }

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

   156   TreeList* root() const { return _root; }

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

   158 

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

   160   // return it.  If the chunk

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

   162   // from the tree.

   163   TreeChunk* getChunkFromTree(size_t size, Dither dither, bool splay);

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

   165   // The list is not removed from the tree.

   166   TreeList* findList (size_t size) const;

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

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

   169   TreeChunk* removeChunkFromTree(TreeChunk* tc);

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

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

   172   TreeList* removeTreeMinimum(TreeList* tl);

   173   void       semiSplayStep(TreeList* tl);

   174   // Add this free chunk to the tree.

   175   void       insertChunkInTree(FreeChunk* freeChunk);

   176  public:

   177   void       verifyTree() const;

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

   179   bool       verifyChunkInFreeLists(FreeChunk* tc) const;

   180  private:

   181   void          verifyTreeHelper(TreeList* tl) const;

   182   static size_t verifyPrevFreePtrs(TreeList* tl);

   183 

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

   185   size_t     totalListLength(TreeList* tl) const;

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

   187   // starting at "tl".

   188   size_t     totalSizeInTree(TreeList* tl) const;

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

   190   // in the tree starting at "tl".

   191   double     sum_of_squared_block_sizes(TreeList* const tl) const;

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

   193   // at "tl".

   194   size_t     totalFreeBlocksInTree(TreeList* tl) const;

   195   size_t     numFreeBlocks() const;

   196   size_t     treeHeight() const;

   197   size_t     treeHeightHelper(TreeList* tl) const;

   198   size_t     totalNodesInTree(TreeList* tl) const;

   199   size_t     totalNodesHelper(TreeList* tl) const;

   200 

   201  public:

   202   // Constructor

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

   204 

   205   // Reset the dictionary to the initial conditions with

   206   // a single free chunk.

   207   void       reset(MemRegion mr);

   208   void       reset(HeapWord* addr, size_t size);

   209   // Reset the dictionary to be empty.

   210   void       reset();

   211 

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

   213   // the tree.

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

   215   FreeChunk* getChunk(size_t size, Dither dither) {

   216     verify_par_locked();

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

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

   219            "Should be returning a free chunk");

   220     return res;

   221   }

   222 

   223   void returnChunk(FreeChunk* chunk) {

   224     verify_par_locked();

   225     insertChunkInTree(chunk);

   226   }

   227 

   228   void removeChunk(FreeChunk* chunk) {

   229     verify_par_locked();

   230     removeChunkFromTree((TreeChunk*)chunk);

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

   232   }

   233 

   234   size_t     maxChunkSize() const;

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

   236     debug_only(

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

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

   239                "_totalSize inconsistency");

   240       }

   241     )

   242     return totalSize();

   243   }

   244 

   245   size_t     minSize() const {

   246     return MIN_TREE_CHUNK_SIZE;

   247   }

   248 

   249   double     sum_of_squared_block_sizes() const {

   250     return sum_of_squared_block_sizes(root());

   251   }

   252 

   253   FreeChunk* find_chunk_ends_at(HeapWord* target) const;

   254 

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

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

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

   258   void       dictCensusUpdate(size_t size, bool split, bool birth);

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

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

   261   bool       coalDictOverPopulated(size_t size);

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

   263   // statistics for the sweep.

   264   void       beginSweepDictCensus(double coalSurplusPercent,

   265                                   float inter_sweep_current,

   266                                   float inter_sweep_estimate,

   267                                   float intra_sweep_estimate);

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

   269   // statistics for the sweep.

   270   void       endSweepDictCensus(double splitSurplusPercent);

   271   // Return the largest free chunk in the tree.

   272   FreeChunk* findLargestDict() const;

   273   // Accessors for statistics

   274   void       setTreeSurplus(double splitSurplusPercent);

   275   void       setTreeHints(void);

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

   277   void       clearTreeCensus(void);

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

   279   // print out summaries.

   280   void       printDictCensus(void) const;

   281   void       print_free_lists(outputStream* st) const;

   282 

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

   284   // all lists in the tree.

   285   size_t     sumDictReturnedBytes()     PRODUCT_RETURN0;

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

   287   void       initializeDictReturnedBytes()      PRODUCT_RETURN;

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

   289   size_t     totalCount()       PRODUCT_RETURN0;

   290 

   291   void       reportStatistics() const;

   292 

   293   void       verify() const;

   294 };

   295 

   296 #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_BINARYTREEDICTIONARY_HPP