rculfhash-mm-chunk.c

   1 /*
   2  * rculfhash-mm-chunk.c
   3  *
   4  * Chunk based memory management for Lock-Free RCU Hash Table
   5  *
   6  * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <stddef.h>
  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_chunk[0] = calloc(ht->min_nr_alloc_buckets,
  31                         sizeof(struct cds_lfht_node));
  32                 assert(ht->tbl_chunk[0]);
  33         } else if (order > ht->min_alloc_buckets_order) {
  34                 unsigned long i, len = 1UL << (order - 1 - ht->min_alloc_buckets_order);
  35
  36                 for (i = len; i < 2 * len; i++) {
  37                         ht->tbl_chunk[i] = calloc(ht->min_nr_alloc_buckets,
  38                                 sizeof(struct cds_lfht_node));
  39                         assert(ht->tbl_chunk[i]);
  40                 }
  41         }
  42         /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
  43 }
  44
  45 /*
  46  * cds_lfht_free_bucket_table() should be called with decreasing order.
  47  * When cds_lfht_free_bucket_table(0) is called, it means the whole
  48  * lfht is destroyed.
  49  */
  50 static
  51 void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order)
  52 {
  53         if (order == 0)
  54                 poison_free(ht->tbl_chunk[0]);
  55         else if (order > ht->min_alloc_buckets_order) {
  56                 unsigned long i, len = 1UL << (order - 1 - ht->min_alloc_buckets_order);
  57
  58                 for (i = len; i < 2 * len; i++)
  59                         poison_free(ht->tbl_chunk[i]);
  60         }
  61         /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
  62 }
  63
  64 static
  65 struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index)
  66 {
  67         unsigned long chunk, offset;
  68
  69         chunk = index >> ht->min_alloc_buckets_order;
  70         offset = index & (ht->min_nr_alloc_buckets - 1);
  71         return &ht->tbl_chunk[chunk][offset];
  72 }
  73
  74 static
  75 struct cds_lfht *alloc_cds_lfht(unsigned long min_nr_alloc_buckets,
  76                 unsigned long max_nr_buckets)
  77 {
  78         unsigned long nr_chunks, cds_lfht_size;
  79
  80         min_nr_alloc_buckets = max(min_nr_alloc_buckets,
  81                                 max_nr_buckets / MAX_CHUNK_TABLE);
  82         nr_chunks = max_nr_buckets / min_nr_alloc_buckets;
  83         cds_lfht_size = offsetof(struct cds_lfht, tbl_chunk) +
  84                         sizeof(struct cds_lfht_node *) * nr_chunks;
  85         cds_lfht_size = max(cds_lfht_size, sizeof(struct cds_lfht));
  86
  87         return __default_alloc_cds_lfht(
  88                         &cds_lfht_mm_chunk, cds_lfht_size,
  89                         min_nr_alloc_buckets, max_nr_buckets);
  90 }
  91
  92 const struct cds_lfht_mm_type cds_lfht_mm_chunk = {
  93         .alloc_cds_lfht = alloc_cds_lfht,
  94         .alloc_bucket_table = cds_lfht_alloc_bucket_table,
  95         .free_bucket_table = cds_lfht_free_bucket_table,
  96         .bucket_at = bucket_at,
  97 };