Thu, 11 Jun 2009 17:19:33 -0700
6843694: G1: assert(index < _vs.committed_size(),"bad index"), g1BlockOffsetTable.inline.hpp:55
Summary: For heaps larger than 32Gb, the number of heap regions overflows the data type used to hold the region index in the SparsePRT structure. Changed the region indexes, card indexes, and RSet hash table buckets to ints and added some size overflow guarantees.
Reviewed-by: ysr, tonyp
1 /*
2 * Copyright 2001-2009 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.
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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
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23 */
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.
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.
36 class SparsePRTEntry: public CHeapObj {
37 public:
39 enum SomePublicConstants {
40 CardsPerEntry = 4,
41 NullEntry = -1
42 };
44 private:
45 RegionIdx_t _region_ind;
46 int _next_index;
47 CardIdx_t _cards[CardsPerEntry];
49 public:
51 // Set the region_ind to the given value, and delete all cards.
52 inline void init(RegionIdx_t region_ind);
54 RegionIdx_t r_ind() const { return _region_ind; }
55 bool valid_entry() const { return r_ind() >= 0; }
56 void set_r_ind(RegionIdx_t rind) { _region_ind = rind; }
58 int next_index() const { return _next_index; }
59 int* next_index_addr() { return &_next_index; }
60 void set_next_index(int ni) { _next_index = ni; }
62 // Returns "true" iff the entry contains the given card index.
63 inline bool contains_card(CardIdx_t card_index) const;
65 // Returns the number of non-NULL card entries.
66 inline int num_valid_cards() const;
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(CardIdx_t card_index);
78 // Copy the current entry's cards into "cards".
79 inline void copy_cards(CardIdx_t* cards) const;
80 // Copy the current entry's cards into the "_card" array of "e."
81 inline void copy_cards(SparsePRTEntry* e) const;
83 inline CardIdx_t card(int i) const { return _cards[i]; }
84 };
87 class RSHashTable : public CHeapObj {
89 friend class RSHashTableIter;
91 enum SomePrivateConstants {
92 NullEntry = -1
93 };
95 size_t _capacity;
96 size_t _capacity_mask;
97 size_t _occupied_entries;
98 size_t _occupied_cards;
100 SparsePRTEntry* _entries;
101 int* _buckets;
102 int _free_region;
103 int _free_list;
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; }
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(RegionIdx_t region_ind) const;
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(RegionIdx_t region_ind);
125 // Returns the index of the next free entry in "_entries".
126 int 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(int fi);
131 public:
132 RSHashTable(size_t capacity);
133 ~RSHashTable();
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(RegionIdx_t region_id, CardIdx_t card_index);
143 bool get_cards(RegionIdx_t region_id, CardIdx_t* cards);
144 bool delete_entry(RegionIdx_t region_id);
146 bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const;
148 void add_entry(SparsePRTEntry* e);
150 void clear();
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; }
159 SparsePRTEntry* entry(int i) const { return &_entries[i]; }
161 void print();
163 static void add_to_deleted_list(RSHashTable* rsht);
164 static RSHashTable* get_from_deleted_list();
165 };
167 // ValueObj because will be embedded in HRRS iterator.
168 class RSHashTableIter VALUE_OBJ_CLASS_SPEC {
169 int _tbl_ind; // [-1, 0.._rsht->_capacity)
170 int _bl_ind; // [-1, 0.._rsht->_capacity)
171 short _card_ind; // [0..CardsPerEntry)
172 RSHashTable* _rsht;
173 size_t _heap_bot_card_ind;
175 enum SomePrivateConstants {
176 CardsPerRegion = HeapRegion::GrainBytes >> CardTableModRefBS::card_shift
177 };
179 // If the bucket list pointed to by _bl_ind contains a card, sets
180 // _bl_ind to the index of that entry, and returns the card.
181 // Otherwise, returns SparseEntry::NullEntry.
182 CardIdx_t find_first_card_in_list();
184 // Computes the proper card index for the card whose offset in the
185 // current region (as indicated by _bl_ind) is "ci".
186 // This is subject to errors when there is iteration concurrent with
187 // modification, but these errors should be benign.
188 size_t compute_card_ind(CardIdx_t ci);
190 public:
191 RSHashTableIter(size_t heap_bot_card_ind) :
192 _tbl_ind(RSHashTable::NullEntry),
193 _bl_ind(RSHashTable::NullEntry),
194 _card_ind((SparsePRTEntry::CardsPerEntry-1)),
195 _rsht(NULL),
196 _heap_bot_card_ind(heap_bot_card_ind)
197 {}
199 void init(RSHashTable* rsht) {
200 _rsht = rsht;
201 _tbl_ind = -1; // So that first increment gets to 0.
202 _bl_ind = RSHashTable::NullEntry;
203 _card_ind = (SparsePRTEntry::CardsPerEntry-1);
204 }
206 bool has_next(size_t& card_index);
207 };
209 // Concurrent accesss to a SparsePRT must be serialized by some external
210 // mutex.
212 class SparsePRTIter;
214 class SparsePRT VALUE_OBJ_CLASS_SPEC {
215 // Iterations are done on the _cur hash table, since they only need to
216 // see entries visible at the start of a collection pause.
217 // All other operations are done using the _next hash table.
218 RSHashTable* _cur;
219 RSHashTable* _next;
221 HeapRegion* _hr;
223 enum SomeAdditionalPrivateConstants {
224 InitialCapacity = 16
225 };
227 void expand();
229 bool _expanded;
231 bool expanded() { return _expanded; }
232 void set_expanded(bool b) { _expanded = b; }
234 SparsePRT* _next_expanded;
236 SparsePRT* next_expanded() { return _next_expanded; }
237 void set_next_expanded(SparsePRT* nxt) { _next_expanded = nxt; }
239 static SparsePRT* _head_expanded_list;
241 public:
242 SparsePRT(HeapRegion* hr);
244 ~SparsePRT();
246 size_t occupied() const { return _next->occupied_cards(); }
247 size_t mem_size() const;
249 // Attempts to ensure that the given card_index in the given region is in
250 // the sparse table. If successful (because the card was already
251 // present, or because it was successfullly added) returns "true".
252 // Otherwise, returns "false" to indicate that the addition would
253 // overflow the entry for the region. The caller must transfer these
254 // entries to a larger-capacity representation.
255 bool add_card(RegionIdx_t region_id, CardIdx_t card_index);
257 // If the table hold an entry for "region_ind", Copies its
258 // cards into "cards", which must be an array of length at least
259 // "CardsPerEntry", and returns "true"; otherwise, returns "false".
260 bool get_cards(RegionIdx_t region_ind, CardIdx_t* cards);
262 // If there is an entry for "region_ind", removes it and return "true";
263 // otherwise returns "false."
264 bool delete_entry(RegionIdx_t region_ind);
266 // Clear the table, and reinitialize to initial capacity.
267 void clear();
269 // Ensure that "_cur" and "_next" point to the same table.
270 void cleanup();
272 // Clean up all tables on the expanded list. Called single threaded.
273 static void cleanup_all();
274 RSHashTable* cur() const { return _cur; }
276 void init_iterator(SparsePRTIter* sprt_iter);
278 static void add_to_expanded_list(SparsePRT* sprt);
279 static SparsePRT* get_from_expanded_list();
281 bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const {
282 return _next->contains_card(region_id, card_index);
283 }
285 #if 0
286 void verify_is_cleared();
287 void print();
288 #endif
289 };
292 class SparsePRTIter: public /* RSHashTable:: */RSHashTableIter {
293 public:
294 SparsePRTIter(size_t heap_bot_card_ind) :
295 /* RSHashTable:: */RSHashTableIter(heap_bot_card_ind)
296 {}
298 void init(const SparsePRT* sprt) {
299 RSHashTableIter::init(sprt->cur());
300 }
301 bool has_next(size_t& card_index) {
302 return RSHashTableIter::has_next(card_index);
303 }
304 };