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1 /*
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2 * Copyright 2001-2006 Sun Microsystems, Inc. All Rights Reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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20 * CA 95054 USA or visit www.sun.com if you need additional information or
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21 * have any questions.
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22 *
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23 */
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24
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25 /*
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26 * A binary tree based search structure for free blocks.
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27 * This is currently used in the Concurrent Mark&Sweep implementation.
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28 */
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29
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30 // A TreeList is a FreeList which can be used to maintain a
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31 // binary tree of free lists.
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32
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33 class TreeChunk;
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34 class BinaryTreeDictionary;
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35 class AscendTreeCensusClosure;
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36 class DescendTreeCensusClosure;
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37 class DescendTreeSearchClosure;
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38
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39 class TreeList: public FreeList {
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40 friend class TreeChunk;
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41 friend class BinaryTreeDictionary;
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42 friend class AscendTreeCensusClosure;
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43 friend class DescendTreeCensusClosure;
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44 friend class DescendTreeSearchClosure;
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45 TreeList* _parent;
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46 TreeList* _left;
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47 TreeList* _right;
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48
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49 protected:
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50 TreeList* parent() const { return _parent; }
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51 TreeList* left() const { return _left; }
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52 TreeList* right() const { return _right; }
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53
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54 // Accessors for links in tree.
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55
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56 void setLeft(TreeList* tl) {
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57 _left = tl;
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58 if (tl != NULL)
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59 tl->setParent(this);
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60 }
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61 void setRight(TreeList* tl) {
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62 _right = tl;
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63 if (tl != NULL)
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64 tl->setParent(this);
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65 }
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66 void setParent(TreeList* tl) { _parent = tl; }
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67
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68 void clearLeft() { _left = NULL; }
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69 void clearRight() { _right = NULL; }
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70 void clearParent() { _parent = NULL; }
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71 void initialize() { clearLeft(); clearRight(), clearParent(); }
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72
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73 // For constructing a TreeList from a Tree chunk or
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74 // address and size.
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75 static TreeList* as_TreeList(TreeChunk* tc);
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76 static TreeList* as_TreeList(HeapWord* addr, size_t size);
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77
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78 // Returns the head of the free list as a pointer to a TreeChunk.
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79 TreeChunk* head_as_TreeChunk();
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80
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81 // Returns the first available chunk in the free list as a pointer
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82 // to a TreeChunk.
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83 TreeChunk* first_available();
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84
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85 // removeChunkReplaceIfNeeded() removes the given "tc" from the TreeList.
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86 // If "tc" is the first chunk in the list, it is also the
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87 // TreeList that is the node in the tree. removeChunkReplaceIfNeeded()
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88 // returns the possibly replaced TreeList* for the node in
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89 // the tree. It also updates the parent of the original
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90 // node to point to the new node.
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91 TreeList* removeChunkReplaceIfNeeded(TreeChunk* tc);
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92 // See FreeList.
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93 void returnChunkAtHead(TreeChunk* tc);
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94 void returnChunkAtTail(TreeChunk* tc);
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95 };
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96
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97 // A TreeChunk is a subclass of a FreeChunk that additionally
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98 // maintains a pointer to the free list on which it is currently
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99 // linked.
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100 // A TreeChunk is also used as a node in the binary tree. This
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101 // allows the binary tree to be maintained without any additional
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102 // storage (the free chunks are used). In a binary tree the first
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103 // chunk in the free list is also the tree node. Note that the
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104 // TreeChunk has an embedded TreeList for this purpose. Because
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105 // the first chunk in the list is distinguished in this fashion
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106 // (also is the node in the tree), it is the last chunk to be found
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107 // on the free list for a node in the tree and is only removed if
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108 // it is the last chunk on the free list.
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109
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110 class TreeChunk : public FreeChunk {
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111 friend class TreeList;
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112 TreeList* _list;
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113 TreeList _embedded_list; // if non-null, this chunk is on _list
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114 protected:
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115 TreeList* embedded_list() const { return (TreeList*) &_embedded_list; }
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116 void set_embedded_list(TreeList* v) { _embedded_list = *v; }
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117 public:
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118 TreeList* list() { return _list; }
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119 void set_list(TreeList* v) { _list = v; }
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120 static TreeChunk* as_TreeChunk(FreeChunk* fc);
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121 // Initialize fields in a TreeChunk that should be
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122 // initialized when the TreeChunk is being added to
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123 // a free list in the tree.
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124 void initialize() { embedded_list()->initialize(); }
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125
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126 // debugging
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127 void verifyTreeChunkList() const;
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128 };
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129
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130 const size_t MIN_TREE_CHUNK_SIZE = sizeof(TreeChunk)/HeapWordSize;
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131
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132 class BinaryTreeDictionary: public FreeBlockDictionary {
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133 bool _splay;
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134 size_t _totalSize;
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135 size_t _totalFreeBlocks;
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136 TreeList* _root;
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137
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138 // private accessors
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139 bool splay() const { return _splay; }
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140 void set_splay(bool v) { _splay = v; }
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141 size_t totalSize() const { return _totalSize; }
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142 void set_totalSize(size_t v) { _totalSize = v; }
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143 virtual void inc_totalSize(size_t v);
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144 virtual void dec_totalSize(size_t v);
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145 size_t totalFreeBlocks() const { return _totalFreeBlocks; }
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146 void set_totalFreeBlocks(size_t v) { _totalFreeBlocks = v; }
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147 TreeList* root() const { return _root; }
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148 void set_root(TreeList* v) { _root = v; }
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149
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150 // Remove a chunk of size "size" or larger from the tree and
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151 // return it. If the chunk
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152 // is the last chunk of that size, remove the node for that size
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153 // from the tree.
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154 TreeChunk* getChunkFromTree(size_t size, Dither dither, bool splay);
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155 // Return a list of the specified size or NULL from the tree.
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156 // The list is not removed from the tree.
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157 TreeList* findList (size_t size) const;
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158 // Remove this chunk from the tree. If the removal results
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159 // in an empty list in the tree, remove the empty list.
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160 TreeChunk* removeChunkFromTree(TreeChunk* tc);
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161 // Remove the node in the trees starting at tl that has the
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162 // minimum value and return it. Repair the tree as needed.
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163 TreeList* removeTreeMinimum(TreeList* tl);
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164 void semiSplayStep(TreeList* tl);
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165 // Add this free chunk to the tree.
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166 void insertChunkInTree(FreeChunk* freeChunk);
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167 public:
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168 void verifyTree() const;
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169 // verify that the given chunk is in the tree.
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170 bool verifyChunkInFreeLists(FreeChunk* tc) const;
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171 private:
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172 void verifyTreeHelper(TreeList* tl) const;
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173 static size_t verifyPrevFreePtrs(TreeList* tl);
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174
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175 // Returns the total number of chunks in the list.
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176 size_t totalListLength(TreeList* tl) const;
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177 // Returns the total number of words in the chunks in the tree
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178 // starting at "tl".
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179 size_t totalSizeInTree(TreeList* tl) const;
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180 // Returns the sum of the square of the size of each block
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181 // in the tree starting at "tl".
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182 double sum_of_squared_block_sizes(TreeList* const tl) const;
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183 // Returns the total number of free blocks in the tree starting
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184 // at "tl".
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185 size_t totalFreeBlocksInTree(TreeList* tl) const;
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186 size_t numFreeBlocks() const;
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187 size_t treeHeight() const;
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188 size_t treeHeightHelper(TreeList* tl) const;
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189 size_t totalNodesInTree(TreeList* tl) const;
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190 size_t totalNodesHelper(TreeList* tl) const;
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191
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192 public:
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193 // Constructor
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194 BinaryTreeDictionary(MemRegion mr, bool splay = false);
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195
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196 // Reset the dictionary to the initial conditions with
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197 // a single free chunk.
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198 void reset(MemRegion mr);
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199 void reset(HeapWord* addr, size_t size);
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200 // Reset the dictionary to be empty.
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201 void reset();
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202
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203 // Return a chunk of size "size" or greater from
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204 // the tree.
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205 // want a better dynamic splay strategy for the future.
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206 FreeChunk* getChunk(size_t size, Dither dither) {
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207 verify_par_locked();
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208 FreeChunk* res = getChunkFromTree(size, dither, splay());
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209 assert(res == NULL || res->isFree(),
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210 "Should be returning a free chunk");
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211 return res;
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212 }
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213
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214 void returnChunk(FreeChunk* chunk) {
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215 verify_par_locked();
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216 insertChunkInTree(chunk);
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217 }
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218
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219 void removeChunk(FreeChunk* chunk) {
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220 verify_par_locked();
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221 removeChunkFromTree((TreeChunk*)chunk);
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222 assert(chunk->isFree(), "Should still be a free chunk");
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223 }
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224
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225 size_t maxChunkSize() const;
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226 size_t totalChunkSize(debug_only(const Mutex* lock)) const {
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227 debug_only(
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228 if (lock != NULL && lock->owned_by_self()) {
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229 assert(totalSizeInTree(root()) == totalSize(),
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230 "_totalSize inconsistency");
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231 }
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232 )
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233 return totalSize();
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234 }
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235
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236 size_t minSize() const {
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237 return MIN_TREE_CHUNK_SIZE;
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238 }
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239
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240 double sum_of_squared_block_sizes() const {
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241 return sum_of_squared_block_sizes(root());
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242 }
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243
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244 FreeChunk* find_chunk_ends_at(HeapWord* target) const;
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245
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246 // Find the list with size "size" in the binary tree and update
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247 // the statistics in the list according to "split" (chunk was
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248 // split or coalesce) and "birth" (chunk was added or removed).
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249 void dictCensusUpdate(size_t size, bool split, bool birth);
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250 // Return true if the dictionary is overpopulated (more chunks of
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251 // this size than desired) for size "size".
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252 bool coalDictOverPopulated(size_t size);
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253 // Methods called at the beginning of a sweep to prepare the
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254 // statistics for the sweep.
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255 void beginSweepDictCensus(double coalSurplusPercent,
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256 float sweep_current,
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257 float sweep_estimate);
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258 // Methods called after the end of a sweep to modify the
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259 // statistics for the sweep.
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260 void endSweepDictCensus(double splitSurplusPercent);
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261 // Return the largest free chunk in the tree.
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262 FreeChunk* findLargestDict() const;
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263 // Accessors for statistics
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264 void setTreeSurplus(double splitSurplusPercent);
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265 void setTreeHints(void);
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266 // Reset statistics for all the lists in the tree.
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267 void clearTreeCensus(void);
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268 // Print the statistcis for all the lists in the tree. Also may
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269 // print out summaries.
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270 void printDictCensus(void) const;
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271
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272 // For debugging. Returns the sum of the _returnedBytes for
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273 // all lists in the tree.
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274 size_t sumDictReturnedBytes() PRODUCT_RETURN0;
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275 // Sets the _returnedBytes for all the lists in the tree to zero.
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276 void initializeDictReturnedBytes() PRODUCT_RETURN;
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277 // For debugging. Return the total number of chunks in the dictionary.
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278 size_t totalCount() PRODUCT_RETURN0;
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279
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280 void reportStatistics() const;
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281
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282 void verify() const;
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283 };
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