1 #ifndef _LTTNG_UST_RCULFHASH_INTERNAL_H
2 #define _LTTNG_UST_RCULFHASH_INTERNAL_H
5 * liblttng-ust/rculfhash-internal.h
7 * Internal header for Lock-Free RCU Hash Table
9 * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10 * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
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.
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.
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
27 #include "rculfhash.h"
33 #define dbg_printf(fmt, args...) printf("[debug lttng-ust rculfhash] " fmt, ## args)
35 #define dbg_printf(fmt, args...) \
37 /* do nothing but check printf format */ \
39 printf("[debug lttng-ust rculfhash] " fmt, ## args); \
43 #if (CAA_BITS_PER_LONG == 32)
44 #define MAX_TABLE_ORDER 32
46 #define MAX_TABLE_ORDER 64
49 #define MAX_CHUNK_TABLE (1UL << 10)
52 #define min(a, b) ((a) < (b) ? (a) : (b))
56 #define max(a, b) ((a) > (b) ? (a) : (b))
60 * lttng_ust_lfht: Top-level data structure representing a lock-free hash
61 * table. Defined in the implementation file to make it be an opaque
64 * The fields used in fast-paths are placed near the end of the
65 * structure, because we need to have a variable-sized union to contain
66 * the mm plugin fields, which are used in the fast path.
68 struct lttng_ust_lfht
{
69 /* Initial configuration items */
70 unsigned long max_nr_buckets
;
71 const struct lttng_ust_lfht_mm_type
*mm
; /* memory management plugin */
72 const struct rcu_flavor_struct
*flavor
; /* RCU flavor */
75 * We need to put the work threads offline (QSBR) when taking this
76 * mutex, because we use synchronize_rcu within this mutex critical
77 * section, which waits on read-side critical sections, and could
78 * therefore cause grace-period deadlock if we hold off RCU G.P.
81 pthread_mutex_t resize_mutex
; /* resize mutex: add/del mutex */
82 unsigned int in_progress_destroy
;
83 unsigned long resize_target
;
87 * Variables needed for add and remove fast-paths.
90 unsigned long min_alloc_buckets_order
;
91 unsigned long min_nr_alloc_buckets
;
94 * Variables needed for the lookup, add and remove fast-paths.
96 unsigned long size
; /* always a power of 2, shared (RCU) */
98 * bucket_at pointer is kept here to skip the extra level of
99 * dereference needed to get to "mm" (this is a fast-path).
101 struct lttng_ust_lfht_node
*(*bucket_at
)(struct lttng_ust_lfht
*ht
,
102 unsigned long index
);
104 * Dynamic length "tbl_chunk" needs to be at the end of
109 * Contains the per order-index-level bucket node table.
110 * The size of each bucket node table is half the number
111 * of hashes contained in this order (except for order 0).
112 * The minimum allocation buckets size parameter allows
113 * combining the bucket node arrays of the lowermost
114 * levels to improve cache locality for small index orders.
116 struct lttng_ust_lfht_node
*tbl_order
[MAX_TABLE_ORDER
];
119 * Contains the bucket node chunks. The size of each
120 * bucket node chunk is ->min_alloc_size (we avoid to
121 * allocate chunks with different size). Chunks improve
122 * cache locality for small index orders, and are more
123 * friendly with environments where allocation of large
124 * contiguous memory areas is challenging due to memory
125 * fragmentation concerns or inability to use virtual
128 struct lttng_ust_lfht_node
*tbl_chunk
[0];
131 * Memory mapping with room for all possible buckets.
132 * Their memory is allocated when needed.
134 struct lttng_ust_lfht_node
*tbl_mmap
;
137 * End of variables needed for the lookup, add and remove
142 extern unsigned int lttng_ust_lfht_fls_ulong(unsigned long x
);
143 extern int lttng_ust_lfht_get_count_order_ulong(unsigned long x
);
146 #define poison_free(ptr) \
149 memset(ptr, 0x42, sizeof(*(ptr))); \
154 #define poison_free(ptr) free(ptr)
158 struct lttng_ust_lfht
*__default_alloc_lttng_ust_lfht(
159 const struct lttng_ust_lfht_mm_type
*mm
,
160 unsigned long lttng_ust_lfht_size
,
161 unsigned long min_nr_alloc_buckets
,
162 unsigned long max_nr_buckets
)
164 struct lttng_ust_lfht
*ht
;
166 ht
= calloc(1, lttng_ust_lfht_size
);
170 ht
->bucket_at
= mm
->bucket_at
;
171 ht
->min_nr_alloc_buckets
= min_nr_alloc_buckets
;
172 ht
->min_alloc_buckets_order
=
173 lttng_ust_lfht_get_count_order_ulong(min_nr_alloc_buckets
);
174 ht
->max_nr_buckets
= max_nr_buckets
;
179 #endif /* _LTTNG_UST_RCULFHASH_INTERNAL_H */