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.
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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