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
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23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_SPARSEPRT_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_SPARSEPRT_HPP
27
28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 #include "gc_implementation/g1/heapRegion.hpp"
30 #include "memory/allocation.hpp"
31 #include "memory/cardTableModRefBS.hpp"
32 #include "runtime/mutex.hpp"
33 #include "utilities/globalDefinitions.hpp"
34
35 // Sparse remembered set for a heap region (the "owning" region). Maps
36 // indices of other regions to short sequences of cards in the other region
37 // that might contain pointers into the owner region.
38
39 // These tables only expand while they are accessed in parallel --
40 // deletions may be done in single-threaded code. This allows us to allow
41 // unsynchronized reads/iterations, as long as expansions caused by
42 // insertions only enqueue old versions for deletions, but do not delete
43 // old versions synchronously.
44
45 class SparsePRTEntry: public CHeapObj {
46 public:
47 enum SomePublicConstants {
48 NullEntry = -1,
49 UnrollFactor = 4
50 };
51 private:
52 RegionIdx_t _region_ind;
53 int _next_index;
54 CardIdx_t _cards[1];
55 // WARNING: Don't put any data members beyond this line. Card array has, in fact, variable length.
56 // It should always be the last data member.
57 public:
58 // Returns the size of the entry, used for entry allocation.
59 static size_t size() { return sizeof(SparsePRTEntry) + sizeof(CardIdx_t) * (cards_num() - 1); }
60 // Returns the size of the card array.
61 static int cards_num() {
62 // The number of cards should be a multiple of 4, because that's our current
63 // unrolling factor.
64 static const int s = MAX2<int>(G1RSetSparseRegionEntries & ~(UnrollFactor - 1), UnrollFactor);
65 return s;
66 }
67
68 // Set the region_ind to the given value, and delete all cards.
69 inline void init(RegionIdx_t region_ind);
70
71 RegionIdx_t r_ind() const { return _region_ind; }
72 bool valid_entry() const { return r_ind() >= 0; }
73 void set_r_ind(RegionIdx_t rind) { _region_ind = rind; }
74
75 int next_index() const { return _next_index; }
76 int* next_index_addr() { return &_next_index; }
77 void set_next_index(int ni) { _next_index = ni; }
78
79 // Returns "true" iff the entry contains the given card index.
80 inline bool contains_card(CardIdx_t card_index) const;
81
82 // Returns the number of non-NULL card entries.
83 inline int num_valid_cards() const;
84
85 // Requires that the entry not contain the given card index. If there is
86 // space available, add the given card index to the entry and return
87 // "true"; otherwise, return "false" to indicate that the entry is full.
88 enum AddCardResult {
89 overflow,
90 found,
91 added
92 };
93 inline AddCardResult add_card(CardIdx_t card_index);
94
95 // Copy the current entry's cards into "cards".
96 inline void copy_cards(CardIdx_t* cards) const;
97 // Copy the current entry's cards into the "_card" array of "e."
98 inline void copy_cards(SparsePRTEntry* e) const;
99
100 inline CardIdx_t card(int i) const { return _cards[i]; }
101 };
102
103
104 class RSHashTable : public CHeapObj {
105
106 friend class RSHashTableIter;
107
108 enum SomePrivateConstants {
109 NullEntry = -1
110 };
111
112 size_t _capacity;
113 size_t _capacity_mask;
114 size_t _occupied_entries;
115 size_t _occupied_cards;
116
117 SparsePRTEntry* _entries;
118 int* _buckets;
119 int _free_region;
120 int _free_list;
121
122 // Requires that the caller hold a lock preventing parallel modifying
123 // operations, and that the the table be less than completely full. If
124 // an entry for "region_ind" is already in the table, finds it and
125 // returns its address; otherwise returns "NULL."
126 SparsePRTEntry* entry_for_region_ind(RegionIdx_t region_ind) const;
127
128 // Requires that the caller hold a lock preventing parallel modifying
129 // operations, and that the the table be less than completely full. If
130 // an entry for "region_ind" is already in the table, finds it and
131 // returns its address; otherwise allocates, initializes, inserts and
132 // returns a new entry for "region_ind".
133 SparsePRTEntry* entry_for_region_ind_create(RegionIdx_t region_ind);
134
135 // Returns the index of the next free entry in "_entries".
136 int alloc_entry();
137 // Declares the entry "fi" to be free. (It must have already been
138 // deleted from any bucket lists.
139 void free_entry(int fi);
140
141 public:
142 RSHashTable(size_t capacity);
143 ~RSHashTable();
144
145 // Attempts to ensure that the given card_index in the given region is in
146 // the sparse table. If successful (because the card was already
147 // present, or because it was successfullly added) returns "true".
148 // Otherwise, returns "false" to indicate that the addition would
149 // overflow the entry for the region. The caller must transfer these
150 // entries to a larger-capacity representation.
151 bool add_card(RegionIdx_t region_id, CardIdx_t card_index);
152
153 bool get_cards(RegionIdx_t region_id, CardIdx_t* cards);
154
155 bool delete_entry(RegionIdx_t region_id);
156
157 bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const;
158
159 void add_entry(SparsePRTEntry* e);
160
161 SparsePRTEntry* get_entry(RegionIdx_t region_id);
162
163 void clear();
164
165 size_t capacity() const { return _capacity; }
166 size_t capacity_mask() const { return _capacity_mask; }
167 size_t occupied_entries() const { return _occupied_entries; }
168 size_t occupied_cards() const { return _occupied_cards; }
169 size_t mem_size() const;
170
171 SparsePRTEntry* entry(int i) const { return (SparsePRTEntry*)((char*)_entries + SparsePRTEntry::size() * i); }
172
173 void print();
174 };
175
176 // ValueObj because will be embedded in HRRS iterator.
177 class RSHashTableIter VALUE_OBJ_CLASS_SPEC {
178 int _tbl_ind; // [-1, 0.._rsht->_capacity)
179 int _bl_ind; // [-1, 0.._rsht->_capacity)
180 short _card_ind; // [0..SparsePRTEntry::cards_num())
181 RSHashTable* _rsht;
182 size_t _heap_bot_card_ind;
183
184 // If the bucket list pointed to by _bl_ind contains a card, sets
185 // _bl_ind to the index of that entry, and returns the card.
186 // Otherwise, returns SparseEntry::NullEntry.
187 CardIdx_t find_first_card_in_list();
188
189 // Computes the proper card index for the card whose offset in the
190 // current region (as indicated by _bl_ind) is "ci".
191 // This is subject to errors when there is iteration concurrent with
192 // modification, but these errors should be benign.
193 size_t compute_card_ind(CardIdx_t ci);
194
195 public:
196 RSHashTableIter(size_t heap_bot_card_ind) :
197 _tbl_ind(RSHashTable::NullEntry),
198 _bl_ind(RSHashTable::NullEntry),
199 _card_ind((SparsePRTEntry::cards_num() - 1)),
200 _rsht(NULL),
201 _heap_bot_card_ind(heap_bot_card_ind)
202 {}
203
204 void init(RSHashTable* rsht) {
205 _rsht = rsht;
206 _tbl_ind = -1; // So that first increment gets to 0.
207 _bl_ind = RSHashTable::NullEntry;
208 _card_ind = (SparsePRTEntry::cards_num() - 1);
209 }
210
211 bool has_next(size_t& card_index);
212 };
213
214 // Concurrent accesss to a SparsePRT must be serialized by some external
215 // mutex.
216
217 class SparsePRTIter;
218
219 class SparsePRT VALUE_OBJ_CLASS_SPEC {
220 // Iterations are done on the _cur hash table, since they only need to
221 // see entries visible at the start of a collection pause.
222 // All other operations are done using the _next hash table.
223 RSHashTable* _cur;
224 RSHashTable* _next;
225
226 HeapRegion* _hr;
227
228 enum SomeAdditionalPrivateConstants {
229 InitialCapacity = 16
230 };
231
232 void expand();
233
234 bool _expanded;
235
236 bool expanded() { return _expanded; }
237 void set_expanded(bool b) { _expanded = b; }
238
239 SparsePRT* _next_expanded;
240
241 SparsePRT* next_expanded() { return _next_expanded; }
242 void set_next_expanded(SparsePRT* nxt) { _next_expanded = nxt; }
243
244 static SparsePRT* _head_expanded_list;
245
246 public:
247 SparsePRT(HeapRegion* hr);
248
249 ~SparsePRT();
250
251 size_t occupied() const { return _next->occupied_cards(); }
252 size_t mem_size() const;
253
254 // Attempts to ensure that the given card_index in the given region is in
255 // the sparse table. If successful (because the card was already
256 // present, or because it was successfullly added) returns "true".
257 // Otherwise, returns "false" to indicate that the addition would
258 // overflow the entry for the region. The caller must transfer these
259 // entries to a larger-capacity representation.
260 bool add_card(RegionIdx_t region_id, CardIdx_t card_index);
261
262 // If the table hold an entry for "region_ind", Copies its
263 // cards into "cards", which must be an array of length at least
264 // "SparePRTEntry::cards_num()", and returns "true"; otherwise,
265 // returns "false".
266 bool get_cards(RegionIdx_t region_ind, CardIdx_t* cards);
267
268 // Return the pointer to the entry associated with the given region.
269 SparsePRTEntry* get_entry(RegionIdx_t region_ind);
270
271 // If there is an entry for "region_ind", removes it and return "true";
272 // otherwise returns "false."
273 bool delete_entry(RegionIdx_t region_ind);
274
275 // Clear the table, and reinitialize to initial capacity.
276 void clear();
277
278 // Ensure that "_cur" and "_next" point to the same table.
279 void cleanup();
280
281 // Clean up all tables on the expanded list. Called single threaded.
282 static void cleanup_all();
283 RSHashTable* cur() const { return _cur; }
284
285 void init_iterator(SparsePRTIter* sprt_iter);
286
287 static void add_to_expanded_list(SparsePRT* sprt);
288 static SparsePRT* get_from_expanded_list();
289
290 bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const {
291 return _next->contains_card(region_id, card_index);
292 }
293
294 #if 0
295 void verify_is_cleared();
296 void print();
297 #endif
298 };
299
300
301 class SparsePRTIter: public /* RSHashTable:: */RSHashTableIter {
302 public:
303 SparsePRTIter(size_t heap_bot_card_ind) :
304 /* RSHashTable:: */RSHashTableIter(heap_bot_card_ind)
305 {}
306
307 void init(const SparsePRT* sprt) {
308 RSHashTableIter::init(sprt->cur());
309 }
310 bool has_next(size_t& card_index) {
311 return RSHashTableIter::has_next(card_index);
312 }
313 };
314
315 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_SPARSEPRT_HPP