1 /*
   2  * Copyright (c) 2001, 2013, 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_MEMORY_BINARYTREEDICTIONARY_HPP
  26 #define SHARE_VM_MEMORY_BINARYTREEDICTIONARY_HPP
  27 
  28 #include "memory/freeBlockDictionary.hpp"
  29 #include "memory/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, but
  34  * will be used for free block management for metadata.
  35  */
  36 
  37 // A TreeList is a FreeList which can be used to maintain a
  38 // binary tree of free lists.
  39 
  40 template <class Chunk_t, class FreeList_t> class TreeChunk;
  41 template <class Chunk_t, class FreeList_t> class BinaryTreeDictionary;
  42 template <class Chunk_t, class FreeList_t> class AscendTreeCensusClosure;
  43 template <class Chunk_t, class FreeList_t> class DescendTreeCensusClosure;
  44 template <class Chunk_t, class FreeList_t> class DescendTreeSearchClosure;
  45 
  46 class FreeChunk;
  47 template <class> class AdaptiveFreeList;
  48 typedef BinaryTreeDictionary<FreeChunk, AdaptiveFreeList<FreeChunk> > AFLBinaryTreeDictionary;
  49 
  50 template <class Chunk_t, class FreeList_t>
  51 class TreeList : public FreeList_t {
  52   friend class TreeChunk<Chunk_t, FreeList_t>;
  53   friend class BinaryTreeDictionary<Chunk_t, FreeList_t>;
  54   friend class AscendTreeCensusClosure<Chunk_t, FreeList_t>;
  55   friend class DescendTreeCensusClosure<Chunk_t, FreeList_t>;
  56   friend class DescendTreeSearchClosure<Chunk_t, FreeList_t>;
  57 
  58   TreeList<Chunk_t, FreeList_t>* _parent;
  59   TreeList<Chunk_t, FreeList_t>* _left;
  60   TreeList<Chunk_t, FreeList_t>* _right;
  61 
  62  protected:
  63 
  64   TreeList<Chunk_t, FreeList_t>* parent() const { return _parent; }
  65   TreeList<Chunk_t, FreeList_t>* left()   const { return _left;   }
  66   TreeList<Chunk_t, FreeList_t>* right()  const { return _right;  }
  67 
  68   // Wrapper on call to base class, to get the template to compile.
  69   Chunk_t* head() const { return FreeList_t::head(); }
  70   Chunk_t* tail() const { return FreeList_t::tail(); }
  71   void set_head(Chunk_t* head) { FreeList_t::set_head(head); }
  72   void set_tail(Chunk_t* tail) { FreeList_t::set_tail(tail); }
  73 
  74   size_t size() const { return FreeList_t::size(); }
  75 
  76   // Accessors for links in tree.
  77 
  78   void set_left(TreeList<Chunk_t, FreeList_t>* tl) {
  79     _left   = tl;
  80     if (tl != NULL)
  81       tl->set_parent(this);
  82   }
  83   void set_right(TreeList<Chunk_t, FreeList_t>* tl) {
  84     _right  = tl;
  85     if (tl != NULL)
  86       tl->set_parent(this);
  87   }
  88   void set_parent(TreeList<Chunk_t, FreeList_t>* tl)  { _parent = tl;   }
  89 
  90   void clear_left()               { _left = NULL;   }
  91   void clear_right()              { _right = NULL;  }
  92   void clear_parent()             { _parent = NULL; }
  93   void initialize()               { clear_left(); clear_right(), clear_parent(); FreeList_t::initialize(); }
  94 
  95   // For constructing a TreeList from a Tree chunk or
  96   // address and size.
  97   TreeList();
  98   static TreeList<Chunk_t, FreeList_t>*
  99           as_TreeList(TreeChunk<Chunk_t, FreeList_t>* tc);
 100   static TreeList<Chunk_t, FreeList_t>* as_TreeList(HeapWord* addr, size_t size);
 101 
 102   // Returns the head of the free list as a pointer to a TreeChunk.
 103   TreeChunk<Chunk_t, FreeList_t>* head_as_TreeChunk();
 104 
 105   // Returns the first available chunk in the free list as a pointer
 106   // to a TreeChunk.
 107   TreeChunk<Chunk_t, FreeList_t>* first_available();
 108 
 109   // Returns the block with the largest heap address amongst
 110   // those in the list for this size; potentially slow and expensive,
 111   // use with caution!
 112   TreeChunk<Chunk_t, FreeList_t>* largest_address();
 113 
 114   TreeList<Chunk_t, FreeList_t>* get_better_list(
 115     BinaryTreeDictionary<Chunk_t, FreeList_t>* dictionary);
 116 
 117   // remove_chunk_replace_if_needed() removes the given "tc" from the TreeList.
 118   // If "tc" is the first chunk in the list, it is also the
 119   // TreeList that is the node in the tree.  remove_chunk_replace_if_needed()
 120   // returns the possibly replaced TreeList* for the node in
 121   // the tree.  It also updates the parent of the original
 122   // node to point to the new node.
 123   TreeList<Chunk_t, FreeList_t>* remove_chunk_replace_if_needed(TreeChunk<Chunk_t, FreeList_t>* tc);
 124   // See FreeList.
 125   void return_chunk_at_head(TreeChunk<Chunk_t, FreeList_t>* tc);
 126   void return_chunk_at_tail(TreeChunk<Chunk_t, FreeList_t>* tc);
 127 };
 128 
 129 // A TreeChunk is a subclass of a Chunk that additionally
 130 // maintains a pointer to the free list on which it is currently
 131 // linked.
 132 // A TreeChunk is also used as a node in the binary tree.  This
 133 // allows the binary tree to be maintained without any additional
 134 // storage (the free chunks are used).  In a binary tree the first
 135 // chunk in the free list is also the tree node.  Note that the
 136 // TreeChunk has an embedded TreeList for this purpose.  Because
 137 // the first chunk in the list is distinguished in this fashion
 138 // (also is the node in the tree), it is the last chunk to be found
 139 // on the free list for a node in the tree and is only removed if
 140 // it is the last chunk on the free list.
 141 
 142 template <class Chunk_t, class FreeList_t>
 143 class TreeChunk : public Chunk_t {
 144   friend class TreeList<Chunk_t, FreeList_t>;
 145   TreeList<Chunk_t, FreeList_t>* _list;
 146   TreeList<Chunk_t, FreeList_t> _embedded_list;  // if non-null, this chunk is on _list
 147 
 148   static size_t _min_tree_chunk_size;
 149 
 150  protected:
 151   TreeList<Chunk_t, FreeList_t>* embedded_list() const { return (TreeList<Chunk_t, FreeList_t>*) &_embedded_list; }
 152   void set_embedded_list(TreeList<Chunk_t, FreeList_t>* v) { _embedded_list = *v; }
 153  public:
 154   TreeList<Chunk_t, FreeList_t>* list() { return _list; }
 155   void set_list(TreeList<Chunk_t, FreeList_t>* v) { _list = v; }
 156   static TreeChunk<Chunk_t, FreeList_t>* as_TreeChunk(Chunk_t* fc);
 157   // Initialize fields in a TreeChunk that should be
 158   // initialized when the TreeChunk is being added to
 159   // a free list in the tree.
 160   void initialize() { embedded_list()->initialize(); }
 161 
 162   Chunk_t* next() const { return Chunk_t::next(); }
 163   Chunk_t* prev() const { return Chunk_t::prev(); }
 164   size_t size() const volatile { return Chunk_t::size(); }
 165 
 166   static size_t min_size() {
 167     return _min_tree_chunk_size;
 168   }
 169 
 170   // debugging
 171   void verify_tree_chunk_list() const;
 172   void assert_is_mangled() const;
 173 };
 174 
 175 
 176 template <class Chunk_t, class FreeList_t>
 177 class BinaryTreeDictionary: public FreeBlockDictionary<Chunk_t> {
 178   friend class VMStructs;
 179   size_t     _total_size;
 180   size_t     _total_free_blocks;
 181   TreeList<Chunk_t, FreeList_t>* _root;
 182 
 183   // private accessors
 184   void set_total_size(size_t v) { _total_size = v; }
 185   virtual void inc_total_size(size_t v);
 186   virtual void dec_total_size(size_t v);
 187   void set_total_free_blocks(size_t v) { _total_free_blocks = v; }
 188   TreeList<Chunk_t, FreeList_t>* root() const { return _root; }
 189   void set_root(TreeList<Chunk_t, FreeList_t>* v) { _root = v; }
 190 
 191   // This field is added and can be set to point to the
 192   // the Mutex used to synchronize access to the
 193   // dictionary so that assertion checking can be done.
 194   // For example it is set to point to _parDictionaryAllocLock.
 195   NOT_PRODUCT(Mutex* _lock;)
 196 
 197   // Remove a chunk of size "size" or larger from the tree and
 198   // return it.  If the chunk
 199   // is the last chunk of that size, remove the node for that size
 200   // from the tree.
 201   TreeChunk<Chunk_t, FreeList_t>* get_chunk_from_tree(size_t size, enum FreeBlockDictionary<Chunk_t>::Dither dither);
 202   // Remove this chunk from the tree.  If the removal results
 203   // in an empty list in the tree, remove the empty list.
 204   TreeChunk<Chunk_t, FreeList_t>* remove_chunk_from_tree(TreeChunk<Chunk_t, FreeList_t>* tc);
 205   // Remove the node in the trees starting at tl that has the
 206   // minimum value and return it.  Repair the tree as needed.
 207   TreeList<Chunk_t, FreeList_t>* remove_tree_minimum(TreeList<Chunk_t, FreeList_t>* tl);
 208   // Add this free chunk to the tree.
 209   void       insert_chunk_in_tree(Chunk_t* freeChunk);
 210  public:
 211 
 212   // Return a list of the specified size or NULL from the tree.
 213   // The list is not removed from the tree.
 214   TreeList<Chunk_t, FreeList_t>* find_list (size_t size) const;
 215 
 216   void       verify_tree() const;
 217   // verify that the given chunk is in the tree.
 218   bool       verify_chunk_in_free_list(Chunk_t* tc) const;
 219  private:
 220   void          verify_tree_helper(TreeList<Chunk_t, FreeList_t>* tl) const;
 221   static size_t verify_prev_free_ptrs(TreeList<Chunk_t, FreeList_t>* tl);
 222 
 223   // Returns the total number of chunks in the list.
 224   size_t     total_list_length(TreeList<Chunk_t, FreeList_t>* tl) const;
 225   // Returns the total number of words in the chunks in the tree
 226   // starting at "tl".
 227   size_t     total_size_in_tree(TreeList<Chunk_t, FreeList_t>* tl) const;
 228   // Returns the sum of the square of the size of each block
 229   // in the tree starting at "tl".
 230   double     sum_of_squared_block_sizes(TreeList<Chunk_t, FreeList_t>* const tl) const;
 231   // Returns the total number of free blocks in the tree starting
 232   // at "tl".
 233   size_t     total_free_blocks_in_tree(TreeList<Chunk_t, FreeList_t>* tl) const;
 234   size_t     num_free_blocks()  const;
 235   size_t     tree_height() const;
 236   size_t     tree_height_helper(TreeList<Chunk_t, FreeList_t>* tl) const;
 237   size_t     total_nodes_in_tree(TreeList<Chunk_t, FreeList_t>* tl) const;
 238   size_t     total_nodes_helper(TreeList<Chunk_t, FreeList_t>* tl) const;
 239 
 240  public:
 241   // Constructor
 242   BinaryTreeDictionary() :
 243     _total_size(0), _total_free_blocks(0), _root(0) {}
 244 
 245   BinaryTreeDictionary(MemRegion mr);
 246 
 247   // Public accessors
 248   size_t total_size() const { return _total_size; }
 249   size_t total_free_blocks() const { return _total_free_blocks; }
 250 
 251   // Reset the dictionary to the initial conditions with
 252   // a single free chunk.
 253   void       reset(MemRegion mr);
 254   void       reset(HeapWord* addr, size_t size);
 255   // Reset the dictionary to be empty.
 256   void       reset();
 257 
 258   // Return a chunk of size "size" or greater from
 259   // the tree.
 260   Chunk_t* get_chunk(size_t size, enum FreeBlockDictionary<Chunk_t>::Dither dither) {
 261     FreeBlockDictionary<Chunk_t>::verify_par_locked();
 262     Chunk_t* res = get_chunk_from_tree(size, dither);
 263     assert(res == NULL || res->is_free(),
 264            "Should be returning a free chunk");
 265     assert(dither != FreeBlockDictionary<Chunk_t>::exactly ||
 266            res == NULL || res->size() == size, "Not correct size");
 267     return res;
 268   }
 269 
 270   void return_chunk(Chunk_t* chunk) {
 271     FreeBlockDictionary<Chunk_t>::verify_par_locked();
 272     insert_chunk_in_tree(chunk);
 273   }
 274 
 275   void remove_chunk(Chunk_t* chunk) {
 276     FreeBlockDictionary<Chunk_t>::verify_par_locked();
 277     remove_chunk_from_tree((TreeChunk<Chunk_t, FreeList_t>*)chunk);
 278     assert(chunk->is_free(), "Should still be a free chunk");
 279   }
 280 
 281   size_t     max_chunk_size() const;
 282   size_t     total_chunk_size(debug_only(const Mutex* lock)) const {
 283     debug_only(
 284       if (lock != NULL && lock->owned_by_self()) {
 285         assert(total_size_in_tree(root()) == total_size(),
 286                "_total_size inconsistency");
 287       }
 288     )
 289     return total_size();
 290   }
 291 
 292   size_t     min_size() const {
 293     return TreeChunk<Chunk_t, FreeList_t>::min_size();
 294   }
 295 
 296   double     sum_of_squared_block_sizes() const {
 297     return sum_of_squared_block_sizes(root());
 298   }
 299 
 300   Chunk_t* find_chunk_ends_at(HeapWord* target) const;
 301 
 302   // Find the list with size "size" in the binary tree and update
 303   // the statistics in the list according to "split" (chunk was
 304   // split or coalesce) and "birth" (chunk was added or removed).
 305   void       dict_census_update(size_t size, bool split, bool birth);
 306   // Return true if the dictionary is overpopulated (more chunks of
 307   // this size than desired) for size "size".
 308   bool       coal_dict_over_populated(size_t size);
 309   // Methods called at the beginning of a sweep to prepare the
 310   // statistics for the sweep.
 311   void       begin_sweep_dict_census(double coalSurplusPercent,
 312                                   float inter_sweep_current,
 313                                   float inter_sweep_estimate,
 314                                   float intra_sweep_estimate);
 315   // Methods called after the end of a sweep to modify the
 316   // statistics for the sweep.
 317   void       end_sweep_dict_census(double splitSurplusPercent);
 318   // Return the largest free chunk in the tree.
 319   Chunk_t* find_largest_dict() const;
 320   // Accessors for statistics
 321   void       set_tree_surplus(double splitSurplusPercent);
 322   void       set_tree_hints(void);
 323   // Reset statistics for all the lists in the tree.
 324   void       clear_tree_census(void);
 325   // Print the statistcis for all the lists in the tree.  Also may
 326   // print out summaries.
 327   void       print_dict_census(void) const;
 328   void       print_free_lists(outputStream* st) const;
 329 
 330   // For debugging.  Returns the sum of the _returned_bytes for
 331   // all lists in the tree.
 332   size_t     sum_dict_returned_bytes()     PRODUCT_RETURN0;
 333   // Sets the _returned_bytes for all the lists in the tree to zero.
 334   void       initialize_dict_returned_bytes()      PRODUCT_RETURN;
 335   // For debugging.  Return the total number of chunks in the dictionary.
 336   size_t     total_count()       PRODUCT_RETURN0;
 337 
 338   void       report_statistics() const;
 339 
 340   void       verify() const;
 341 };
 342 
 343 #endif // SHARE_VM_MEMORY_BINARYTREEDICTIONARY_HPP