liblttng-ust/rculfhash-internal.h

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-or-later
   3  *
   4  * Copyright 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  * Copyright 2011 Lai Jiangshan <laijs@cn.fujitsu.com>
   6  *
   7  * Internal header for Lock-Free RCU Hash Table
   8  */
   9
  10 #ifndef _LTTNG_UST_RCULFHASH_INTERNAL_H
  11 #define _LTTNG_UST_RCULFHASH_INTERNAL_H
  12
  13 #include "rculfhash.h"
  14 #include <stdio.h>
  15 #include <stdlib.h>
  16 #include <assert.h>
  17 #include "helper.h"
  18
  19 #ifdef DEBUG
  20 #define dbg_printf(fmt, args...)     printf("[debug lttng-ust rculfhash] " fmt, ## args)
  21 #else
  22 #define dbg_printf(fmt, args...)                                \
  23 do {                                                            \
  24         /* do nothing but check printf format */                \
  25         if (0)                                                  \
  26                 printf("[debug lttng-ust rculfhash] " fmt, ## args);    \
  27 } while (0)
  28 #endif
  29
  30 #if (CAA_BITS_PER_LONG == 32)
  31 #define MAX_TABLE_ORDER                 32
  32 #else
  33 #define MAX_TABLE_ORDER                 64
  34 #endif
  35
  36 #define MAX_CHUNK_TABLE                 (1UL << 10)
  37
  38 #ifndef min
  39 #define min(a, b)       ((a) < (b) ? (a) : (b))
  40 #endif
  41
  42 #ifndef max
  43 #define max(a, b)       ((a) > (b) ? (a) : (b))
  44 #endif
  45
  46 /*
  47  * lttng_ust_lfht: Top-level data structure representing a lock-free hash
  48  * table. Defined in the implementation file to make it be an opaque
  49  * cookie to users.
  50  *
  51  * The fields used in fast-paths are placed near the end of the
  52  * structure, because we need to have a variable-sized union to contain
  53  * the mm plugin fields, which are used in the fast path.
  54  */
  55 struct lttng_ust_lfht {
  56         /* Initial configuration items */
  57         unsigned long max_nr_buckets;
  58         const struct lttng_ust_lfht_mm_type *mm;        /* memory management plugin */
  59         const struct rcu_flavor_struct *flavor; /* RCU flavor */
  60
  61         /*
  62          * We need to put the work threads offline (QSBR) when taking this
  63          * mutex, because we use synchronize_rcu within this mutex critical
  64          * section, which waits on read-side critical sections, and could
  65          * therefore cause grace-period deadlock if we hold off RCU G.P.
  66          * completion.
  67          */
  68         pthread_mutex_t resize_mutex;   /* resize mutex: add/del mutex */
  69         unsigned int in_progress_destroy;
  70         unsigned long resize_target;
  71         int resize_initiated;
  72
  73         /*
  74          * Variables needed for add and remove fast-paths.
  75          */
  76         int flags;
  77         unsigned long min_alloc_buckets_order;
  78         unsigned long min_nr_alloc_buckets;
  79
  80         /*
  81          * Variables needed for the lookup, add and remove fast-paths.
  82          */
  83         unsigned long size;     /* always a power of 2, shared (RCU) */
  84         /*
  85          * bucket_at pointer is kept here to skip the extra level of
  86          * dereference needed to get to "mm" (this is a fast-path).
  87          */
  88         struct lttng_ust_lfht_node *(*bucket_at)(struct lttng_ust_lfht *ht,
  89                         unsigned long index);
  90         /*
  91          * Dynamic length "tbl_chunk" needs to be at the end of
  92          * lttng_ust_lfht.
  93          */
  94         union {
  95                 /*
  96                  * Contains the per order-index-level bucket node table.
  97                  * The size of each bucket node table is half the number
  98                  * of hashes contained in this order (except for order 0).
  99                  * The minimum allocation buckets size parameter allows
 100                  * combining the bucket node arrays of the lowermost
 101                  * levels to improve cache locality for small index orders.
 102                  */
 103                 struct lttng_ust_lfht_node *tbl_order[MAX_TABLE_ORDER];
 104
 105                 /*
 106                  * Contains the bucket node chunks. The size of each
 107                  * bucket node chunk is ->min_alloc_size (we avoid to
 108                  * allocate chunks with different size). Chunks improve
 109                  * cache locality for small index orders, and are more
 110                  * friendly with environments where allocation of large
 111                  * contiguous memory areas is challenging due to memory
 112                  * fragmentation concerns or inability to use virtual
 113                  * memory addressing.
 114                  */
 115                 struct lttng_ust_lfht_node *tbl_chunk[0];
 116
 117                 /*
 118                  * Memory mapping with room for all possible buckets.
 119                  * Their memory is allocated when needed.
 120                  */
 121                 struct lttng_ust_lfht_node *tbl_mmap;
 122         };
 123         /*
 124          * End of variables needed for the lookup, add and remove
 125          * fast-paths.
 126          */
 127 };
 128
 129 LTTNG_HIDDEN
 130 extern unsigned int lttng_ust_lfht_fls_ulong(unsigned long x);
 131 LTTNG_HIDDEN
 132 extern int lttng_ust_lfht_get_count_order_u32(uint32_t x);
 133 LTTNG_HIDDEN
 134 extern int lttng_ust_lfht_get_count_order_ulong(unsigned long x);
 135
 136 #ifdef POISON_FREE
 137 #define poison_free(ptr)                                        \
 138         do {                                                    \
 139                 if (ptr) {                                      \
 140                         memset(ptr, 0x42, sizeof(*(ptr)));      \
 141                         free(ptr);                              \
 142                 }                                               \
 143         } while (0)
 144 #else
 145 #define poison_free(ptr)        free(ptr)
 146 #endif
 147
 148 static inline
 149 struct lttng_ust_lfht *__default_alloc_lttng_ust_lfht(
 150                 const struct lttng_ust_lfht_mm_type *mm,
 151                 unsigned long lttng_ust_lfht_size,
 152                 unsigned long min_nr_alloc_buckets,
 153                 unsigned long max_nr_buckets)
 154 {
 155         struct lttng_ust_lfht *ht;
 156
 157         ht = calloc(1, lttng_ust_lfht_size);
 158         assert(ht);
 159
 160         ht->mm = mm;
 161         ht->bucket_at = mm->bucket_at;
 162         ht->min_nr_alloc_buckets = min_nr_alloc_buckets;
 163         ht->min_alloc_buckets_order =
 164                 lttng_ust_lfht_get_count_order_ulong(min_nr_alloc_buckets);
 165         ht->max_nr_buckets = max_nr_buckets;
 166
 167         return ht;
 168 }
 169
 170 #endif /* _LTTNG_UST_RCULFHASH_INTERNAL_H */