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comparison src/share/vm/gc_implementation/g1/sparsePRT.hpp @ 342:37f87013dfd8

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6711316: Open source the Garbage-First garbage collector Summary: First mercurial integration of the code for the Garbage-First garbage collector. Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr
author ysr
date Thu, 05 Jun 2008 15:57:56 -0700
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children fe3d7c11b4b7
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189:0b27f3512f9e 342:37f87013dfd8
1 /*
2 * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // Sparse remembered set for a heap region (the "owning" region). Maps
26 // indices of other regions to short sequences of cards in the other region
27 // that might contain pointers into the owner region.
28
29 // These tables only expand while they are accessed in parallel --
30 // deletions may be done in single-threaded code. This allows us to allow
31 // unsynchronized reads/iterations, as long as expansions caused by
32 // insertions only enqueue old versions for deletions, but do not delete
33 // old versions synchronously.
34
35
36 class SparsePRTEntry {
37 public:
38 enum SomePublicConstants {
39 CardsPerEntry = (short)4,
40 NullEntry = (short)-1,
41 DeletedEntry = (short)-2
42 };
43
44 private:
45 short _region_ind;
46 short _next_index;
47 short _cards[CardsPerEntry];
48
49 public:
50
51 // Set the region_ind to the given value, and delete all cards.
52 inline void init(short region_ind);
53
54 short r_ind() const { return _region_ind; }
55 bool valid_entry() const { return r_ind() >= 0; }
56 void set_r_ind(short rind) { _region_ind = rind; }
57
58 short next_index() const { return _next_index; }
59 short* next_index_addr() { return &_next_index; }
60 void set_next_index(short ni) { _next_index = ni; }
61
62 // Returns "true" iff the entry contains the given card index.
63 inline bool contains_card(short card_index) const;
64
65 // Returns the number of non-NULL card entries.
66 inline int num_valid_cards() const;
67
68 // Requires that the entry not contain the given card index. If there is
69 // space available, add the given card index to the entry and return
70 // "true"; otherwise, return "false" to indicate that the entry is full.
71 enum AddCardResult {
72 overflow,
73 found,
74 added
75 };
76 inline AddCardResult add_card(short card_index);
77
78 // Copy the current entry's cards into "cards".
79 inline void copy_cards(short* cards) const;
80 // Copy the current entry's cards into the "_card" array of "e."
81 inline void copy_cards(SparsePRTEntry* e) const;
82
83 inline short card(int i) const { return _cards[i]; }
84 };
85
86
87 class RSHashTable : public CHeapObj {
88
89 friend class RSHashTableIter;
90
91 enum SomePrivateConstants {
92 NullEntry = -1
93 };
94
95 size_t _capacity;
96 size_t _capacity_mask;
97 size_t _occupied_entries;
98 size_t _occupied_cards;
99
100 SparsePRTEntry* _entries;
101 short* _buckets;
102 short _free_region;
103 short _free_list;
104
105 static RSHashTable* _head_deleted_list;
106 RSHashTable* _next_deleted;
107 RSHashTable* next_deleted() { return _next_deleted; }
108 void set_next_deleted(RSHashTable* rsht) { _next_deleted = rsht; }
109 bool _deleted;
110 void set_deleted(bool b) { _deleted = b; }
111
112 // Requires that the caller hold a lock preventing parallel modifying
113 // operations, and that the the table be less than completely full. If
114 // an entry for "region_ind" is already in the table, finds it and
115 // returns its address; otherwise returns "NULL."
116 SparsePRTEntry* entry_for_region_ind(short region_ind) const;
117
118 // Requires that the caller hold a lock preventing parallel modifying
119 // operations, and that the the table be less than completely full. If
120 // an entry for "region_ind" is already in the table, finds it and
121 // returns its address; otherwise allocates, initializes, inserts and
122 // returns a new entry for "region_ind".
123 SparsePRTEntry* entry_for_region_ind_create(short region_ind);
124
125 // Returns the index of the next free entry in "_entries".
126 short alloc_entry();
127 // Declares the entry "fi" to be free. (It must have already been
128 // deleted from any bucket lists.
129 void free_entry(short fi);
130
131 public:
132 RSHashTable(size_t capacity);
133 ~RSHashTable();
134
135 // Attempts to ensure that the given card_index in the given region is in
136 // the sparse table. If successful (because the card was already
137 // present, or because it was successfullly added) returns "true".
138 // Otherwise, returns "false" to indicate that the addition would
139 // overflow the entry for the region. The caller must transfer these
140 // entries to a larger-capacity representation.
141 bool add_card(short region_id, short card_index);
142
143 bool get_cards(short region_id, short* cards);
144 bool delete_entry(short region_id);
145
146 bool contains_card(short region_id, short card_index) const;
147
148 void add_entry(SparsePRTEntry* e);
149
150 void clear();
151
152 size_t capacity() const { return _capacity; }
153 size_t capacity_mask() const { return _capacity_mask; }
154 size_t occupied_entries() const { return _occupied_entries; }
155 size_t occupied_cards() const { return _occupied_cards; }
156 size_t mem_size() const;
157 bool deleted() { return _deleted; }
158
159 SparsePRTEntry* entry(int i) const { return &_entries[i]; }
160
161 void print();
162
163 static void add_to_deleted_list(RSHashTable* rsht);
164 static RSHashTable* get_from_deleted_list();
165
166
167 };
168
169 // ValueObj because will be embedded in HRRS iterator.
170 class RSHashTableIter: public CHeapObj {
171 short _tbl_ind;
172 short _bl_ind;
173 short _card_ind;
174 RSHashTable* _rsht;
175 size_t _heap_bot_card_ind;
176
177 enum SomePrivateConstants {
178 CardsPerRegion = HeapRegion::GrainBytes >> CardTableModRefBS::card_shift
179 };
180
181 // If the bucket list pointed to by _bl_ind contains a card, sets
182 // _bl_ind to the index of that entry, and returns the card.
183 // Otherwise, returns SparseEntry::NullEnty.
184 short find_first_card_in_list();
185 // Computes the proper card index for the card whose offset in the
186 // current region (as indicated by _bl_ind) is "ci".
187 // This is subject to errors when there is iteration concurrent with
188 // modification, but these errors should be benign.
189 size_t compute_card_ind(short ci);
190
191 public:
192 RSHashTableIter(size_t heap_bot_card_ind) :
193 _tbl_ind(RSHashTable::NullEntry),
194 _bl_ind(RSHashTable::NullEntry),
195 _card_ind((SparsePRTEntry::CardsPerEntry-1)),
196 _rsht(NULL),
197 _heap_bot_card_ind(heap_bot_card_ind)
198 {}
199
200 void init(RSHashTable* rsht) {
201 _rsht = rsht;
202 _tbl_ind = -1; // So that first increment gets to 0.
203 _bl_ind = RSHashTable::NullEntry;
204 _card_ind = (SparsePRTEntry::CardsPerEntry-1);
205 }
206
207 bool has_next(size_t& card_index);
208
209 };
210
211 // Concurrent accesss to a SparsePRT must be serialized by some external
212 // mutex.
213
214 class SparsePRTIter;
215
216 class SparsePRT : public CHeapObj {
217 // Iterations are done on the _cur hash table, since they only need to
218 // see entries visible at the start of a collection pause.
219 // All other operations are done using the _next hash table.
220 RSHashTable* _cur;
221 RSHashTable* _next;
222
223 HeapRegion* _hr;
224
225 enum SomeAdditionalPrivateConstants {
226 InitialCapacity = 16
227 };
228
229 void expand();
230
231 bool _expanded;
232
233 bool expanded() { return _expanded; }
234 void set_expanded(bool b) { _expanded = b; }
235
236 SparsePRT* _next_expanded;
237
238 SparsePRT* next_expanded() { return _next_expanded; }
239 void set_next_expanded(SparsePRT* nxt) { _next_expanded = nxt; }
240
241
242 static SparsePRT* _head_expanded_list;
243
244 public:
245 SparsePRT(HeapRegion* hr);
246
247 ~SparsePRT();
248
249 size_t occupied() const { return _next->occupied_cards(); }
250 size_t mem_size() const;
251
252 // Attempts to ensure that the given card_index in the given region is in
253 // the sparse table. If successful (because the card was already
254 // present, or because it was successfullly added) returns "true".
255 // Otherwise, returns "false" to indicate that the addition would
256 // overflow the entry for the region. The caller must transfer these
257 // entries to a larger-capacity representation.
258 bool add_card(short region_id, short card_index);
259
260 // If the table hold an entry for "region_ind", Copies its
261 // cards into "cards", which must be an array of length at least
262 // "CardsPerEntry", and returns "true"; otherwise, returns "false".
263 bool get_cards(short region_ind, short* cards);
264
265 // If there is an entry for "region_ind", removes it and return "true";
266 // otherwise returns "false."
267 bool delete_entry(short region_ind);
268
269 // Clear the table, and reinitialize to initial capacity.
270 void clear();
271
272 // Ensure that "_cur" and "_next" point to the same table.
273 void cleanup();
274
275 // Clean up all tables on the expanded list. Called single threaded.
276 static void cleanup_all();
277 RSHashTable* next() const { return _next; }
278
279
280 void init_iterator(SparsePRTIter* sprt_iter);
281
282 static void add_to_expanded_list(SparsePRT* sprt);
283 static SparsePRT* get_from_expanded_list();
284
285 bool contains_card(short region_id, short card_index) const {
286 return _next->contains_card(region_id, card_index);
287 }
288
289 #if 0
290 void verify_is_cleared();
291 void print();
292 #endif
293 };
294
295
296 class SparsePRTIter: public /* RSHashTable:: */RSHashTableIter {
297 public:
298 SparsePRTIter(size_t heap_bot_card_ind) :
299 /* RSHashTable:: */RSHashTableIter(heap_bot_card_ind)
300 {}
301
302 void init(const SparsePRT* sprt) {
303 RSHashTableIter::init(sprt->next());
304 }
305 bool has_next(size_t& card_index) {
306 return RSHashTableIter::has_next(card_index);
307 }
308 };