lib/gl_anyhash2.h

   1 /* Hash table for sequential list, set, and map data type.
   2    Copyright (C) 2006, 2009-2018 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2006.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Common code of
  19    gl_linkedhash_list.c, gl_avltreehash_list.c, gl_rbtreehash_list.c,
  20    gl_linkedhash_set.c, gl_hash_set.c.  */
  21
  22 #include "gl_anyhash_primes.h"
  23
  24 /* Resize the hash table with a new estimated size.  */
  25 static void
  26 hash_resize (CONTAINER_T container, size_t estimate)
  27 {
  28   size_t new_size = next_prime (estimate);
  29
  30   if (new_size > container->table_size)
  31     {
  32       gl_hash_entry_t *old_table = container->table;
  33       /* Allocate the new table.  */
  34       gl_hash_entry_t *new_table;
  35       size_t i;
  36
  37       if (size_overflow_p (xtimes (new_size, sizeof (gl_hash_entry_t))))
  38         goto fail;
  39       new_table =
  40         (gl_hash_entry_t *) calloc (new_size, sizeof (gl_hash_entry_t));
  41       if (new_table == NULL)
  42         goto fail;
  43
  44       /* Iterate through the entries of the old table.  */
  45       for (i = container->table_size; i > 0; )
  46         {
  47           gl_hash_entry_t node = old_table[--i];
  48
  49           while (node != NULL)
  50             {
  51               gl_hash_entry_t next = node->hash_next;
  52               /* Add the entry to the new table.  */
  53               size_t bucket = node->hashcode % new_size;
  54               node->hash_next = new_table[bucket];
  55               new_table[bucket] = node;
  56
  57               node = next;
  58             }
  59         }
  60
  61       container->table = new_table;
  62       container->table_size = new_size;
  63       free (old_table);
  64     }
  65   return;
  66
  67  fail:
  68   /* Just continue without resizing the table.  */
  69   return;
  70 }
  71
  72 /* Resize the hash table if needed, after CONTAINER_COUNT (container) was
  73    incremented.  */
  74 static void
  75 hash_resize_after_add (CONTAINER_T container)
  76 {
  77   size_t count = CONTAINER_COUNT (container);
  78   size_t estimate = xsum (count, count / 2); /* 1.5 * count */
  79   if (estimate > container->table_size)
  80     hash_resize (container, estimate);
  81 }