Merge branch 'urcu/ht-shrink'
[urcu.git] / rculfhash-internal.h
1 #ifndef _URCU_RCULFHASH_INTERNAL_H
2 #define _URCU_RCULFHASH_INTERNAL_H
3
4 /*
5 * urcu/rculfhash-internal.h
6 *
7 * Internal header for Lock-Free RCU Hash Table
8 *
9 * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10 * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
11 *
12 * This library is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU Lesser General Public
14 * License as published by the Free Software Foundation; either
15 * version 2.1 of the License, or (at your option) any later version.
16 *
17 * This library is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * Lesser General Public License for more details.
21 *
22 * You should have received a copy of the GNU Lesser General Public
23 * License along with this library; if not, write to the Free Software
24 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25 */
26
27 #include <urcu/rculfhash.h>
28
29 #ifdef DEBUG
30 #define dbg_printf(fmt, args...) printf("[debug rculfhash] " fmt, ## args)
31 #else
32 #define dbg_printf(fmt, args...)
33 #endif
34
35 #if (CAA_BITS_PER_LONG == 32)
36 #define MAX_TABLE_ORDER 32
37 #else
38 #define MAX_TABLE_ORDER 64
39 #endif
40
41 #define MAX_CHUNK_TABLE (1UL << 10)
42
43 #ifndef min
44 #define min(a, b) ((a) < (b) ? (a) : (b))
45 #endif
46
47 #ifndef max
48 #define max(a, b) ((a) > (b) ? (a) : (b))
49 #endif
50
51 struct ht_items_count;
52
53 /*
54 * cds_lfht: Top-level data structure representing a lock-free hash
55 * table. Defined in the implementation file to make it be an opaque
56 * cookie to users.
57 *
58 * The fields used in fast-paths are placed near the end of the
59 * structure, because we need to have a variable-sized union to contain
60 * the mm plugin fields, which are used in the fast path.
61 */
62 struct cds_lfht {
63 /* Initial configuration items */
64 unsigned long max_nr_buckets;
65 const struct cds_lfht_mm_type *mm; /* memory management plugin */
66 const struct rcu_flavor_struct *flavor; /* RCU flavor */
67
68 long count; /* global approximate item count */
69
70 /*
71 * We need to put the work threads offline (QSBR) when taking this
72 * mutex, because we use synchronize_rcu within this mutex critical
73 * section, which waits on read-side critical sections, and could
74 * therefore cause grace-period deadlock if we hold off RCU G.P.
75 * completion.
76 */
77 pthread_mutex_t resize_mutex; /* resize mutex: add/del mutex */
78 pthread_attr_t *resize_attr; /* Resize threads attributes */
79 unsigned int in_progress_resize, in_progress_destroy;
80 unsigned long resize_target;
81 int resize_initiated;
82
83 /*
84 * Variables needed for add and remove fast-paths.
85 */
86 int flags;
87 unsigned long min_alloc_buckets_order;
88 unsigned long min_nr_alloc_buckets;
89 struct ht_items_count *split_count; /* split item count */
90
91 /*
92 * Variables needed for the lookup, add and remove fast-paths.
93 */
94 unsigned long size; /* always a power of 2, shared (RCU) */
95 /*
96 * bucket_at pointer is kept here to skip the extra level of
97 * dereference needed to get to "mm" (this is a fast-path).
98 */
99 struct cds_lfht_node *(*bucket_at)(struct cds_lfht *ht,
100 unsigned long index);
101 /*
102 * Dynamic length "tbl_chunk" needs to be at the end of
103 * cds_lfht.
104 */
105 union {
106 /*
107 * Contains the per order-index-level bucket node table.
108 * The size of each bucket node table is half the number
109 * of hashes contained in this order (except for order 0).
110 * The minimum allocation buckets size parameter allows
111 * combining the bucket node arrays of the lowermost
112 * levels to improve cache locality for small index orders.
113 */
114 struct cds_lfht_node *tbl_order[MAX_TABLE_ORDER];
115
116 /*
117 * Contains the bucket node chunks. The size of each
118 * bucket node chunk is ->min_alloc_size (we avoid to
119 * allocate chunks with different size). Chunks improve
120 * cache locality for small index orders, and are more
121 * friendly with environments where allocation of large
122 * contiguous memory areas is challenging due to memory
123 * fragmentation concerns or inability to use virtual
124 * memory addressing.
125 */
126 struct cds_lfht_node *tbl_chunk[0];
127
128 /*
129 * Memory mapping with room for all possible buckets.
130 * Their memory is allocated when needed.
131 */
132 struct cds_lfht_node *tbl_mmap;
133 };
134 /*
135 * End of variables needed for the lookup, add and remove
136 * fast-paths.
137 */
138 };
139
140 extern unsigned int cds_lfht_fls_ulong(unsigned long x);
141 extern int cds_lfht_get_count_order_ulong(unsigned long x);
142
143 #ifdef POISON_FREE
144 #define poison_free(ptr) \
145 do { \
146 if (ptr) { \
147 memset(ptr, 0x42, sizeof(*(ptr))); \
148 free(ptr); \
149 } \
150 } while (0)
151 #else
152 #define poison_free(ptr) free(ptr)
153 #endif
154
155 static inline
156 struct cds_lfht *__default_alloc_cds_lfht(
157 const struct cds_lfht_mm_type *mm,
158 unsigned long cds_lfht_size,
159 unsigned long min_nr_alloc_buckets,
160 unsigned long max_nr_buckets)
161 {
162 struct cds_lfht *ht;
163
164 ht = calloc(1, cds_lfht_size);
165 assert(ht);
166
167 ht->mm = mm;
168 ht->bucket_at = mm->bucket_at;
169 ht->min_nr_alloc_buckets = min_nr_alloc_buckets;
170 ht->min_alloc_buckets_order =
171 cds_lfht_get_count_order_ulong(min_nr_alloc_buckets);
172 ht->max_nr_buckets = max_nr_buckets;
173
174 return ht;
175 }
176
177 #endif /* _URCU_RCULFHASH_INTERNAL_H */
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