liblttng-ust/rculfhash-internal.h

   1 #ifndef _LTTNG_UST_RCULFHASH_INTERNAL_H
   2 #define _LTTNG_UST_RCULFHASH_INTERNAL_H
   3
   4 /*
   5  * liblttng-ust/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 "rculfhash.h"
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <assert.h>
  31
  32 #ifdef DEBUG
  33 #define dbg_printf(fmt, args...)     printf("[debug lttng-ust rculfhash] " fmt, ## args)
  34 #else
  35 #define dbg_printf(fmt, args...)                                \
  36 do {                                                            \
  37         /* do nothing but check printf format */                \
  38         if (0)                                                  \
  39                 printf("[debug lttng-ust rculfhash] " fmt, ## args);    \
  40 } while (0)
  41 #endif
  42
  43 #if (CAA_BITS_PER_LONG == 32)
  44 #define MAX_TABLE_ORDER                 32
  45 #else
  46 #define MAX_TABLE_ORDER                 64
  47 #endif
  48
  49 #define MAX_CHUNK_TABLE                 (1UL << 10)
  50
  51 #ifndef min
  52 #define min(a, b)       ((a) < (b) ? (a) : (b))
  53 #endif
  54
  55 #ifndef max
  56 #define max(a, b)       ((a) > (b) ? (a) : (b))
  57 #endif
  58
  59 /*
  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
  62  * cookie to users.
  63  *
  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.
  67  */
  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 */
  73
  74         /*
  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.
  79          * completion.
  80          */
  81         pthread_mutex_t resize_mutex;   /* resize mutex: add/del mutex */
  82         unsigned int in_progress_destroy;
  83         unsigned long resize_target;
  84         int resize_initiated;
  85
  86         /*
  87          * Variables needed for add and remove fast-paths.
  88          */
  89         int flags;
  90         unsigned long min_alloc_buckets_order;
  91         unsigned long min_nr_alloc_buckets;
  92
  93         /*
  94          * Variables needed for the lookup, add and remove fast-paths.
  95          */
  96         unsigned long size;     /* always a power of 2, shared (RCU) */
  97         /*
  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).
 100          */
 101         struct lttng_ust_lfht_node *(*bucket_at)(struct lttng_ust_lfht *ht,
 102                         unsigned long index);
 103         /*
 104          * Dynamic length "tbl_chunk" needs to be at the end of
 105          * lttng_ust_lfht.
 106          */
 107         union {
 108                 /*
 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.
 115                  */
 116                 struct lttng_ust_lfht_node *tbl_order[MAX_TABLE_ORDER];
 117
 118                 /*
 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
 126                  * memory addressing.
 127                  */
 128                 struct lttng_ust_lfht_node *tbl_chunk[0];
 129
 130                 /*
 131                  * Memory mapping with room for all possible buckets.
 132                  * Their memory is allocated when needed.
 133                  */
 134                 struct lttng_ust_lfht_node *tbl_mmap;
 135         };
 136         /*
 137          * End of variables needed for the lookup, add and remove
 138          * fast-paths.
 139          */
 140 };
 141
 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);
 144
 145 #ifdef POISON_FREE
 146 #define poison_free(ptr)                                        \
 147         do {                                                    \
 148                 if (ptr) {                                      \
 149                         memset(ptr, 0x42, sizeof(*(ptr)));      \
 150                         free(ptr);                              \
 151                 }                                               \
 152         } while (0)
 153 #else
 154 #define poison_free(ptr)        free(ptr)
 155 #endif
 156
 157 static inline
 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)
 163 {
 164         struct lttng_ust_lfht *ht;
 165
 166         ht = calloc(1, lttng_ust_lfht_size);
 167         assert(ht);
 168
 169         ht->mm = mm;
 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;
 175
 176         return ht;
 177 }
 178
 179 #endif /* _LTTNG_UST_RCULFHASH_INTERNAL_H */