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 #include <rculfhash-internal.h>
  25
  26 static
  27 void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order)
  28 {
  29         if (order == 0) {
  30                 ht->tbl_order[0] = calloc(ht->min_nr_alloc_buckets,
  31                         sizeof(struct cds_lfht_node));
  32                 assert(ht->tbl_order[0]);
  33         } else if (order > ht->min_alloc_buckets_order) {
  34                 ht->tbl_order[order] = calloc(1UL << (order -1),
  35                         sizeof(struct cds_lfht_node));
  36                 assert(ht->tbl_order[order]);
  37         }
  38         /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
  39 }
  40
  41 /*
  42  * cds_lfht_free_bucket_table() should be called with decreasing order.
  43  * When cds_lfht_free_bucket_table(0) is called, it means the whole
  44  * lfht is destroyed.
  45  */
  46 static
  47 void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order)
  48 {
  49         if (order == 0)
  50                 poison_free(ht->tbl_order[0]);
  51         else if (order > ht->min_alloc_buckets_order)
  52                 poison_free(ht->tbl_order[order]);
  53         /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
  54 }
  55
  56 static
  57 struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index)
  58 {
  59         unsigned long order;
  60
  61         if (index < ht->min_nr_alloc_buckets) {
  62                 dbg_printf("bucket index %lu order 0 aridx 0\n", index);
  63                 return &ht->tbl_order[0][index];
  64         }
  65         /*
  66          * equivalent to cds_lfht_get_count_order_ulong(index + 1), but
  67          * optimizes away the non-existing 0 special-case for
  68          * cds_lfht_get_count_order_ulong.
  69          */
  70         order = cds_lfht_fls_ulong(index);
  71         dbg_printf("bucket index %lu order %lu aridx %lu\n",
  72                    index, order, index & ((1UL << (order - 1)) - 1));
  73         return &ht->tbl_order[order][index & ((1UL << (order - 1)) - 1)];
  74 }
  75
  76 static
  77 struct cds_lfht *alloc_cds_lfht(unsigned long min_nr_alloc_buckets,
  78                 unsigned long max_nr_buckets)
  79 {
  80         return __default_alloc_cds_lfht(
  81                         &cds_lfht_mm_order, sizeof(struct cds_lfht),
  82                         min_nr_alloc_buckets, max_nr_buckets);
  83 }
  84
  85 const struct cds_lfht_mm_type cds_lfht_mm_order = {
  86         .alloc_cds_lfht = alloc_cds_lfht,
  87         .alloc_bucket_table = cds_lfht_alloc_bucket_table,
  88         .free_bucket_table = cds_lfht_free_bucket_table,
  89         .bucket_at = bucket_at,
  90 };