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 "glib.h"
  34
  35
  36 typedef struct _GCacheNode  GCacheNode;
  37
  38 struct _GCacheNode
  39 {
  40   /* A reference counted node */
  41   gpointer value;
  42   gint ref_count;
  43 };
  44
  45 struct _GCache
  46 {
  47   /* Called to create a value from a key */
  48   GCacheNewFunc value_new_func;
  49
  50   /* Called to destroy a value */
  51   GCacheDestroyFunc value_destroy_func;
  52
  53   /* Called to duplicate a key */
  54   GCacheDupFunc key_dup_func;
  55
  56   /* Called to destroy a key */
  57   GCacheDestroyFunc key_destroy_func;
  58
  59   /* Associates keys with nodes */
  60   GHashTable *key_table;
  61
  62   /* Associates nodes with keys */
  63   GHashTable *value_table;
  64 };
  65
  66
  67 static GCacheNode* g_cache_node_new     (gpointer value);
  68 static void        g_cache_node_destroy (GCacheNode *node);
  69
  70
  71 static GMemChunk *node_mem_chunk = NULL;
  72 G_LOCK_DEFINE_STATIC (node_mem_chunk);
  73
  74 GCache*
  75 g_cache_new (GCacheNewFunc      value_new_func,
  76              GCacheDestroyFunc  value_destroy_func,
  77              GCacheDupFunc      key_dup_func,
  78              GCacheDestroyFunc  key_destroy_func,
  79              GHashFunc          hash_key_func,
  80              GHashFunc          hash_value_func,
  81              GEqualFunc         key_equal_func)
  82 {
  83   GCache *cache;
  84
  85   g_return_val_if_fail (value_new_func != NULL, NULL);
  86   g_return_val_if_fail (value_destroy_func != NULL, NULL);
  87   g_return_val_if_fail (key_dup_func != NULL, NULL);
  88   g_return_val_if_fail (key_destroy_func != NULL, NULL);
  89   g_return_val_if_fail (hash_key_func != NULL, NULL);
  90   g_return_val_if_fail (hash_value_func != NULL, NULL);
  91   g_return_val_if_fail (key_equal_func != NULL, NULL);
  92
  93   cache = g_new (GCache, 1);
  94   cache->value_new_func = value_new_func;
  95   cache->value_destroy_func = value_destroy_func;
  96   cache->key_dup_func = key_dup_func;
  97   cache->key_destroy_func = key_destroy_func;
  98   cache->key_table = g_hash_table_new (hash_key_func, key_equal_func);
  99   cache->value_table = g_hash_table_new (hash_value_func, NULL);
 100
 101   return cache;
 102 }
 103
 104 void
 105 g_cache_destroy (GCache *cache)
 106 {
 107   g_return_if_fail (cache != NULL);
 108
 109   g_hash_table_destroy (cache->key_table);
 110   g_hash_table_destroy (cache->value_table);
 111   g_free (cache);
 112 }
 113
 114 gpointer
 115 g_cache_insert (GCache   *cache,
 116                 gpointer  key)
 117 {
 118   GCacheNode *node;
 119   gpointer value;
 120
 121   g_return_val_if_fail (cache != NULL, NULL);
 122
 123   node = g_hash_table_lookup (cache->key_table, key);
 124   if (node)
 125     {
 126       node->ref_count += 1;
 127       return node->value;
 128     }
 129
 130   key = (* cache->key_dup_func) (key);
 131   value = (* cache->value_new_func) (key);
 132   node = g_cache_node_new (value);
 133
 134   g_hash_table_insert (cache->key_table, key, node);
 135   g_hash_table_insert (cache->value_table, value, key);
 136
 137   return node->value;
 138 }
 139
 140 void
 141 g_cache_remove (GCache        *cache,
 142                 gconstpointer  value)
 143 {
 144   GCacheNode *node;
 145   gpointer key;
 146
 147   g_return_if_fail (cache != NULL);
 148
 149   key = g_hash_table_lookup (cache->value_table, value);
 150   node = g_hash_table_lookup (cache->key_table, key);
 151
 152   g_return_if_fail (node != NULL);
 153
 154   node->ref_count -= 1;
 155   if (node->ref_count == 0)
 156     {
 157       g_hash_table_remove (cache->value_table, value);
 158       g_hash_table_remove (cache->key_table, key);
 159
 160       (* cache->key_destroy_func) (key);
 161       (* cache->value_destroy_func) (node->value);
 162       g_cache_node_destroy (node);
 163     }
 164 }
 165
 166 void
 167 g_cache_key_foreach (GCache   *cache,
 168                      GHFunc    func,
 169                      gpointer  user_data)
 170 {
 171   g_return_if_fail (cache != NULL);
 172   g_return_if_fail (func != NULL);
 173
 174   g_hash_table_foreach (cache->value_table, func, user_data);
 175 }
 176
 177 void
 178 g_cache_value_foreach (GCache   *cache,
 179                        GHFunc    func,
 180                        gpointer  user_data)
 181 {
 182   g_return_if_fail (cache != NULL);
 183   g_return_if_fail (func != NULL);
 184
 185   g_hash_table_foreach (cache->key_table, func, user_data);
 186 }
 187
 188
 189 static GCacheNode*
 190 g_cache_node_new (gpointer value)
 191 {
 192   GCacheNode *node;
 193
 194   G_LOCK (node_mem_chunk);
 195   if (!node_mem_chunk)
 196     node_mem_chunk = g_mem_chunk_new ("cache node mem chunk", sizeof (GCacheNode),
 197                                       1024, G_ALLOC_AND_FREE);
 198
 199   node = g_chunk_new (GCacheNode, node_mem_chunk);
 200   G_UNLOCK (node_mem_chunk);
 201
 202   node->value = value;
 203   node->ref_count = 1;
 204
 205   return node;
 206 }
 207
 208 static void
 209 g_cache_node_destroy (GCacheNode *node)
 210 {
 211   G_LOCK (node_mem_chunk);
 212   g_mem_chunk_free (node_mem_chunk, node);
 213   G_UNLOCK (node_mem_chunk);
 214 }