src/common/hashtable/rculfhash-mm-order.c

   1 /*
   2  * rculfhash-mm-order.c
   3  *
   4  * Order based memory management for Lock-Free RCU Hash Table
   5  *
   6  * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #define _GNU_SOURCE
  25 #define _LGPL_SOURCE
  26 #include "rculfhash-internal.h"
  27
  28 static
  29 void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order)
  30 {
  31         if (order == 0) {
  32                 ht->tbl_order[0] = calloc(ht->min_nr_alloc_buckets,
  33                         sizeof(struct cds_lfht_node));
  34                 assert(ht->tbl_order[0]);
  35         } else if (order > ht->min_alloc_buckets_order) {
  36                 ht->tbl_order[order] = calloc(1UL << (order -1),
  37                         sizeof(struct cds_lfht_node));
  38                 assert(ht->tbl_order[order]);
  39         }
  40         /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
  41 }
  42
  43 /*
  44  * cds_lfht_free_bucket_table() should be called with decreasing order.
  45  * When cds_lfht_free_bucket_table(0) is called, it means the whole
  46  * lfht is destroyed.
  47  */
  48 static
  49 void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order)
  50 {
  51         if (order == 0)
  52                 poison_free(ht->tbl_order[0]);
  53         else if (order > ht->min_alloc_buckets_order)
  54                 poison_free(ht->tbl_order[order]);
  55         /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
  56 }
  57
  58 static
  59 struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index)
  60 {
  61         unsigned long order;
  62
  63         if (index < ht->min_nr_alloc_buckets) {
  64                 dbg_printf("bucket index %lu order 0 aridx 0\n", index);
  65                 return &ht->tbl_order[0][index];
  66         }
  67         /*
  68          * equivalent to cds_lfht_get_count_order_ulong(index + 1), but
  69          * optimizes away the non-existing 0 special-case for
  70          * cds_lfht_get_count_order_ulong.
  71          */
  72         order = cds_lfht_fls_ulong(index);
  73         dbg_printf("bucket index %lu order %lu aridx %lu\n",
  74                    index, order, index & ((1UL << (order - 1)) - 1));
  75         return &ht->tbl_order[order][index & ((1UL << (order - 1)) - 1)];
  76 }
  77
  78 static
  79 struct cds_lfht *alloc_cds_lfht(unsigned long min_nr_alloc_buckets,
  80                 unsigned long max_nr_buckets)
  81 {
  82         return __default_alloc_cds_lfht(
  83                         &cds_lfht_mm_order, sizeof(struct cds_lfht),
  84                         min_nr_alloc_buckets, max_nr_buckets);
  85 }
  86
  87 const struct cds_lfht_mm_type cds_lfht_mm_order = {
  88         .alloc_cds_lfht = alloc_cds_lfht,
  89         .alloc_bucket_table = cds_lfht_alloc_bucket_table,
  90         .free_bucket_table = cds_lfht_free_bucket_table,
  91         .bucket_at = bucket_at,
  92 };