Wed, 30 Sep 2009 14:50:51 -0400
6890137: G1: revamp reachable object dump
Summary: Revamp the reachable object dump debugging facility.
Reviewed-by: jmasa, apetrusenko
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.
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 */
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 // If the bucket list pointed to by _bl_ind contains a card, sets
176 // _bl_ind to the index of that entry, and returns the card.
177 // Otherwise, returns SparseEntry::NullEntry.
178 CardIdx_t find_first_card_in_list();
180 // Computes the proper card index for the card whose offset in the
181 // current region (as indicated by _bl_ind) is "ci".
182 // This is subject to errors when there is iteration concurrent with
183 // modification, but these errors should be benign.
184 size_t compute_card_ind(CardIdx_t ci);
186 public:
187 RSHashTableIter(size_t heap_bot_card_ind) :
188 _tbl_ind(RSHashTable::NullEntry),
189 _bl_ind(RSHashTable::NullEntry),
190 _card_ind((SparsePRTEntry::CardsPerEntry-1)),
191 _rsht(NULL),
192 _heap_bot_card_ind(heap_bot_card_ind)
193 {}
195 void init(RSHashTable* rsht) {
196 _rsht = rsht;
197 _tbl_ind = -1; // So that first increment gets to 0.
198 _bl_ind = RSHashTable::NullEntry;
199 _card_ind = (SparsePRTEntry::CardsPerEntry-1);
200 }
202 bool has_next(size_t& card_index);
203 };
205 // Concurrent accesss to a SparsePRT must be serialized by some external
206 // mutex.
208 class SparsePRTIter;
210 class SparsePRT VALUE_OBJ_CLASS_SPEC {
211 // Iterations are done on the _cur hash table, since they only need to
212 // see entries visible at the start of a collection pause.
213 // All other operations are done using the _next hash table.
214 RSHashTable* _cur;
215 RSHashTable* _next;
217 HeapRegion* _hr;
219 enum SomeAdditionalPrivateConstants {
220 InitialCapacity = 16
221 };
223 void expand();
225 bool _expanded;
227 bool expanded() { return _expanded; }
228 void set_expanded(bool b) { _expanded = b; }
230 SparsePRT* _next_expanded;
232 SparsePRT* next_expanded() { return _next_expanded; }
233 void set_next_expanded(SparsePRT* nxt) { _next_expanded = nxt; }
235 static SparsePRT* _head_expanded_list;
237 public:
238 SparsePRT(HeapRegion* hr);
240 ~SparsePRT();
242 size_t occupied() const { return _next->occupied_cards(); }
243 size_t mem_size() const;
245 // Attempts to ensure that the given card_index in the given region is in
246 // the sparse table. If successful (because the card was already
247 // present, or because it was successfullly added) returns "true".
248 // Otherwise, returns "false" to indicate that the addition would
249 // overflow the entry for the region. The caller must transfer these
250 // entries to a larger-capacity representation.
251 bool add_card(RegionIdx_t region_id, CardIdx_t card_index);
253 // If the table hold an entry for "region_ind", Copies its
254 // cards into "cards", which must be an array of length at least
255 // "CardsPerEntry", and returns "true"; otherwise, returns "false".
256 bool get_cards(RegionIdx_t region_ind, CardIdx_t* cards);
258 // If there is an entry for "region_ind", removes it and return "true";
259 // otherwise returns "false."
260 bool delete_entry(RegionIdx_t region_ind);
262 // Clear the table, and reinitialize to initial capacity.
263 void clear();
265 // Ensure that "_cur" and "_next" point to the same table.
266 void cleanup();
268 // Clean up all tables on the expanded list. Called single threaded.
269 static void cleanup_all();
270 RSHashTable* cur() const { return _cur; }
272 void init_iterator(SparsePRTIter* sprt_iter);
274 static void add_to_expanded_list(SparsePRT* sprt);
275 static SparsePRT* get_from_expanded_list();
277 bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const {
278 return _next->contains_card(region_id, card_index);
279 }
281 #if 0
282 void verify_is_cleared();
283 void print();
284 #endif
285 };
288 class SparsePRTIter: public /* RSHashTable:: */RSHashTableIter {
289 public:
290 SparsePRTIter(size_t heap_bot_card_ind) :
291 /* RSHashTable:: */RSHashTableIter(heap_bot_card_ind)
292 {}
294 void init(const SparsePRT* sprt) {
295 RSHashTableIter::init(sprt->cur());
296 }
297 bool has_next(size_t& card_index) {
298 return RSHashTableIter::has_next(card_index);
299 }
300 };