glib/gcache.c

   1 /* GLIB - Library of useful routines for C programming
   2  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  */
  19
  20 /*
  21  * Modified by the GLib Team and others 1997-2000.  See the AUTHORS
  22  * file for a list of people on the GLib Team.  See the ChangeLog
  23  * files for a list of changes.  These files are distributed with
  24  * GLib at ftp://ftp.gtk.org/pub/gtk/.
  25  */
  26
  27 /*
  28  * MT safe
  29  */
  30
  31 #include "config.h"
  32
  33 #include "galias.h"
  34 #include "glib.h"
  35
  36
  37 typedef struct _GCacheNode  GCacheNode;
  38
  39 struct _GCacheNode
  40 {
  41   /* A reference counted node */
  42   gpointer value;
  43   gint ref_count;
  44 };
  45
  46 struct _GCache
  47 {
  48   /* Called to create a value from a key */
  49   GCacheNewFunc value_new_func;
  50
  51   /* Called to destroy a value */
  52   GCacheDestroyFunc value_destroy_func;
  53
  54   /* Called to duplicate a key */
  55   GCacheDupFunc key_dup_func;
  56
  57   /* Called to destroy a key */
  58   GCacheDestroyFunc key_destroy_func;
  59
  60   /* Associates keys with nodes */
  61   GHashTable *key_table;
  62
  63   /* Associates nodes with keys */
  64   GHashTable *value_table;
  65 };
  66
  67
  68 static GCacheNode* g_cache_node_new     (gpointer value);
  69 static void        g_cache_node_destroy (GCacheNode *node);
  70
  71
  72 static GMemChunk *node_mem_chunk = NULL;
  73 G_LOCK_DEFINE_STATIC (node_mem_chunk);
  74
  75 GCache*
  76 g_cache_new (GCacheNewFunc      value_new_func,
  77              GCacheDestroyFunc  value_destroy_func,
  78              GCacheDupFunc      key_dup_func,
  79              GCacheDestroyFunc  key_destroy_func,
  80              GHashFunc          hash_key_func,
  81              GHashFunc          hash_value_func,
  82              GEqualFunc         key_equal_func)
  83 {
  84   GCache *cache;
  85
  86   g_return_val_if_fail (value_new_func != NULL, NULL);
  87   g_return_val_if_fail (value_destroy_func != NULL, NULL);
  88   g_return_val_if_fail (key_dup_func != NULL, NULL);
  89   g_return_val_if_fail (key_destroy_func != NULL, NULL);
  90   g_return_val_if_fail (hash_key_func != NULL, NULL);
  91   g_return_val_if_fail (hash_value_func != NULL, NULL);
  92   g_return_val_if_fail (key_equal_func != NULL, NULL);
  93
  94   cache = g_new (GCache, 1);
  95   cache->value_new_func = value_new_func;
  96   cache->value_destroy_func = value_destroy_func;
  97   cache->key_dup_func = key_dup_func;
  98   cache->key_destroy_func = key_destroy_func;
  99   cache->key_table = g_hash_table_new (hash_key_func, key_equal_func);
 100   cache->value_table = g_hash_table_new (hash_value_func, NULL);
 101
 102   return cache;
 103 }
 104
 105 void
 106 g_cache_destroy (GCache *cache)
 107 {
 108   g_return_if_fail (cache != NULL);
 109
 110   g_hash_table_destroy (cache->key_table);
 111   g_hash_table_destroy (cache->value_table);
 112   g_free (cache);
 113 }
 114
 115 gpointer
 116 g_cache_insert (GCache   *cache,
 117                 gpointer  key)
 118 {
 119   GCacheNode *node;
 120   gpointer value;
 121
 122   g_return_val_if_fail (cache != NULL, NULL);
 123
 124   node = g_hash_table_lookup (cache->key_table, key);
 125   if (node)
 126     {
 127       node->ref_count += 1;
 128       return node->value;
 129     }
 130
 131   key = (* cache->key_dup_func) (key);
 132   value = (* cache->value_new_func) (key);
 133   node = g_cache_node_new (value);
 134
 135   g_hash_table_insert (cache->key_table, key, node);
 136   g_hash_table_insert (cache->value_table, value, key);
 137
 138   return node->value;
 139 }
 140
 141 void
 142 g_cache_remove (GCache        *cache,
 143                 gconstpointer  value)
 144 {
 145   GCacheNode *node;
 146   gpointer key;
 147
 148   g_return_if_fail (cache != NULL);
 149
 150   key = g_hash_table_lookup (cache->value_table, value);
 151   node = g_hash_table_lookup (cache->key_table, key);
 152
 153   g_return_if_fail (node != NULL);
 154
 155   node->ref_count -= 1;
 156   if (node->ref_count == 0)
 157     {
 158       g_hash_table_remove (cache->value_table, value);
 159       g_hash_table_remove (cache->key_table, key);
 160
 161       (* cache->key_destroy_func) (key);
 162       (* cache->value_destroy_func) (node->value);
 163       g_cache_node_destroy (node);
 164     }
 165 }
 166
 167 void
 168 g_cache_key_foreach (GCache   *cache,
 169                      GHFunc    func,
 170                      gpointer  user_data)
 171 {
 172   g_return_if_fail (cache != NULL);
 173   g_return_if_fail (func != NULL);
 174
 175   g_hash_table_foreach (cache->value_table, func, user_data);
 176 }
 177
 178 void
 179 g_cache_value_foreach (GCache   *cache,
 180                        GHFunc    func,
 181                        gpointer  user_data)
 182 {
 183   g_return_if_fail (cache != NULL);
 184   g_return_if_fail (func != NULL);
 185
 186   g_hash_table_foreach (cache->key_table, func, user_data);
 187 }
 188
 189
 190 static GCacheNode*
 191 g_cache_node_new (gpointer value)
 192 {
 193   GCacheNode *node;
 194
 195   G_LOCK (node_mem_chunk);
 196   if (!node_mem_chunk)
 197     node_mem_chunk = g_mem_chunk_new ("cache node mem chunk", sizeof (GCacheNode),
 198                                       1024, G_ALLOC_AND_FREE);
 199
 200   node = g_chunk_new (GCacheNode, node_mem_chunk);
 201   G_UNLOCK (node_mem_chunk);
 202
 203   node->value = value;
 204   node->ref_count = 1;
 205
 206   return node;
 207 }
 208
 209 static void
 210 g_cache_node_destroy (GCacheNode *node)
 211 {
 212   G_LOCK (node_mem_chunk);
 213   g_mem_chunk_free (node_mem_chunk, node);
 214   G_UNLOCK (node_mem_chunk);
 215 }