src/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 <urcu/assert.h>
  25 #include <rculfhash-internal.h>
  26
  27 static
  28 void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order)
  29 {
  30         if (order == 0) {
  31                 ht->tbl_order[0] = calloc(ht->min_nr_alloc_buckets,
  32                         sizeof(struct cds_lfht_node));
  33                 urcu_posix_assert(ht->tbl_order[0]);
  34         } else if (order > ht->min_alloc_buckets_order) {
  35                 ht->tbl_order[order] = calloc(1UL << (order -1),
  36                         sizeof(struct cds_lfht_node));
  37                 urcu_posix_assert(ht->tbl_order[order]);
  38         }
  39         /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
  40 }
  41
  42 /*
  43  * cds_lfht_free_bucket_table() should be called with decreasing order.
  44  * When cds_lfht_free_bucket_table(0) is called, it means the whole
  45  * lfht is destroyed.
  46  */
  47 static
  48 void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order)
  49 {
  50         if (order == 0)
  51                 poison_free(ht->tbl_order[0]);
  52         else if (order > ht->min_alloc_buckets_order)
  53                 poison_free(ht->tbl_order[order]);
  54         /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
  55 }
  56
  57 static
  58 struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index)
  59 {
  60         unsigned long order;
  61
  62         if (index < ht->min_nr_alloc_buckets) {
  63                 dbg_printf("bucket index %lu order 0 aridx 0\n", index);
  64                 return &ht->tbl_order[0][index];
  65         }
  66         /*
  67          * equivalent to cds_lfht_get_count_order_ulong(index + 1), but
  68          * optimizes away the non-existing 0 special-case for
  69          * cds_lfht_get_count_order_ulong.
  70          */
  71         order = cds_lfht_fls_ulong(index);
  72         dbg_printf("bucket index %lu order %lu aridx %lu\n",
  73                    index, order, index & ((1UL << (order - 1)) - 1));
  74         return &ht->tbl_order[order][index & ((1UL << (order - 1)) - 1)];
  75 }
  76
  77 static
  78 struct cds_lfht *alloc_cds_lfht(unsigned long min_nr_alloc_buckets,
  79                 unsigned long max_nr_buckets)
  80 {
  81         return __default_alloc_cds_lfht(
  82                         &cds_lfht_mm_order, sizeof(struct cds_lfht),
  83                         min_nr_alloc_buckets, max_nr_buckets);
  84 }
  85
  86 const struct cds_lfht_mm_type cds_lfht_mm_order = {
  87         .alloc_cds_lfht = alloc_cds_lfht,
  88         .alloc_bucket_table = cds_lfht_alloc_bucket_table,
  89         .free_bucket_table = cds_lfht_free_bucket_table,
  90         .bucket_at = bucket_at,
  91 };