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 "glib.h"
  32
  33
  34 typedef struct _GCacheNode  GCacheNode;
  35
  36 struct _GCacheNode
  37 {
  38   /* A reference counted node */
  39   gpointer value;
  40   gint ref_count;
  41 };
  42
  43 struct _GCache
  44 {
  45   /* Called to create a value from a key */
  46   GCacheNewFunc value_new_func;
  47
  48   /* Called to destroy a value */
  49   GCacheDestroyFunc value_destroy_func;
  50
  51   /* Called to duplicate a key */
  52   GCacheDupFunc key_dup_func;
  53
  54   /* Called to destroy a key */
  55   GCacheDestroyFunc key_destroy_func;
  56
  57   /* Associates keys with nodes */
  58   GHashTable *key_table;
  59
  60   /* Associates nodes with keys */
  61   GHashTable *value_table;
  62 };
  63
  64
  65 static GCacheNode* g_cache_node_new     (gpointer value);
  66 static void        g_cache_node_destroy (GCacheNode *node);
  67
  68
  69 static GMemChunk *node_mem_chunk = NULL;
  70 G_LOCK_DEFINE_STATIC (node_mem_chunk);
  71
  72 GCache*
  73 g_cache_new (GCacheNewFunc      value_new_func,
  74              GCacheDestroyFunc  value_destroy_func,
  75              GCacheDupFunc      key_dup_func,
  76              GCacheDestroyFunc  key_destroy_func,
  77              GHashFunc          hash_key_func,
  78              GHashFunc          hash_value_func,
  79              GEqualFunc         key_equal_func)
  80 {
  81   GCache *cache;
  82
  83   g_return_val_if_fail (value_new_func != NULL, NULL);
  84   g_return_val_if_fail (value_destroy_func != NULL, NULL);
  85   g_return_val_if_fail (key_dup_func != NULL, NULL);
  86   g_return_val_if_fail (key_destroy_func != NULL, NULL);
  87   g_return_val_if_fail (hash_key_func != NULL, NULL);
  88   g_return_val_if_fail (hash_value_func != NULL, NULL);
  89   g_return_val_if_fail (key_equal_func != NULL, NULL);
  90
  91   cache = g_new (GCache, 1);
  92   cache->value_new_func = value_new_func;
  93   cache->value_destroy_func = value_destroy_func;
  94   cache->key_dup_func = key_dup_func;
  95   cache->key_destroy_func = key_destroy_func;
  96   cache->key_table = g_hash_table_new (hash_key_func, key_equal_func);
  97   cache->value_table = g_hash_table_new (hash_value_func, NULL);
  98
  99   return cache;
 100 }
 101
 102 void
 103 g_cache_destroy (GCache *cache)
 104 {
 105   g_return_if_fail (cache != NULL);
 106
 107   g_hash_table_destroy (cache->key_table);
 108   g_hash_table_destroy (cache->value_table);
 109   g_free (cache);
 110 }
 111
 112 gpointer
 113 g_cache_insert (GCache   *cache,
 114                 gpointer  key)
 115 {
 116   GCacheNode *node;
 117   gpointer value;
 118
 119   g_return_val_if_fail (cache != NULL, NULL);
 120
 121   node = g_hash_table_lookup (cache->key_table, key);
 122   if (node)
 123     {
 124       node->ref_count += 1;
 125       return node->value;
 126     }
 127
 128   key = (* cache->key_dup_func) (key);
 129   value = (* cache->value_new_func) (key);
 130   node = g_cache_node_new (value);
 131
 132   g_hash_table_insert (cache->key_table, key, node);
 133   g_hash_table_insert (cache->value_table, value, key);
 134
 135   return node->value;
 136 }
 137
 138 void
 139 g_cache_remove (GCache        *cache,
 140                 gconstpointer  value)
 141 {
 142   GCacheNode *node;
 143   gpointer key;
 144
 145   g_return_if_fail (cache != NULL);
 146
 147   key = g_hash_table_lookup (cache->value_table, value);
 148   node = g_hash_table_lookup (cache->key_table, key);
 149
 150   g_return_if_fail (node != NULL);
 151
 152   node->ref_count -= 1;
 153   if (node->ref_count == 0)
 154     {
 155       g_hash_table_remove (cache->value_table, value);
 156       g_hash_table_remove (cache->key_table, key);
 157
 158       (* cache->key_destroy_func) (key);
 159       (* cache->value_destroy_func) (node->value);
 160       g_cache_node_destroy (node);
 161     }
 162 }
 163
 164 void
 165 g_cache_key_foreach (GCache   *cache,
 166                      GHFunc    func,
 167                      gpointer  user_data)
 168 {
 169   g_return_if_fail (cache != NULL);
 170   g_return_if_fail (func != NULL);
 171
 172   g_hash_table_foreach (cache->value_table, func, user_data);
 173 }
 174
 175 void
 176 g_cache_value_foreach (GCache   *cache,
 177                        GHFunc    func,
 178                        gpointer  user_data)
 179 {
 180   g_return_if_fail (cache != NULL);
 181   g_return_if_fail (func != NULL);
 182
 183   g_hash_table_foreach (cache->key_table, func, user_data);
 184 }
 185
 186
 187 static GCacheNode*
 188 g_cache_node_new (gpointer value)
 189 {
 190   GCacheNode *node;
 191
 192   G_LOCK (node_mem_chunk);
 193   if (!node_mem_chunk)
 194     node_mem_chunk = g_mem_chunk_new ("cache node mem chunk", sizeof (GCacheNode),
 195                                       1024, G_ALLOC_AND_FREE);
 196
 197   node = g_chunk_new (GCacheNode, node_mem_chunk);
 198   G_UNLOCK (node_mem_chunk);
 199
 200   node->value = value;
 201   node->ref_count = 1;
 202
 203   return node;
 204 }
 205
 206 static void
 207 g_cache_node_destroy (GCacheNode *node)
 208 {
 209   G_LOCK (node_mem_chunk);
 210   g_mem_chunk_free (node_mem_chunk, node);
 211   G_UNLOCK (node_mem_chunk);
 212 }