1 /* GLIB - Library of useful routines for C programming
2 * Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
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.
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.
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.
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/.
37 #include "gtestutils.h"
42 * @short_description: caches allow sharing of complex data structures
45 * A #GCache allows sharing of complex data structures, in order to
46 * save system resources.
48 * GTK+ uses caches for #GtkStyles and #GdkGCs. These consume a lot of
49 * resources, so a #GCache is used to see if a #GtkStyle or #GdkGC with
50 * the required properties already exists. If it does, then the
51 * existing object is used instead of creating a new one.
53 * #GCache uses keys and values. A #GCache key describes the properties
54 * of a particular resource. A #GCache value is the actual resource.
57 typedef struct _GCacheNode GCacheNode;
61 /* A reference counted node */
69 * The #GCache struct is an opaque data structure containing
70 * information about a #GCache. It should only be accessed via the
71 * following functions.
75 /* Called to create a value from a key */
76 GCacheNewFunc value_new_func;
78 /* Called to destroy a value */
79 GCacheDestroyFunc value_destroy_func;
81 /* Called to duplicate a key */
82 GCacheDupFunc key_dup_func;
84 /* Called to destroy a key */
85 GCacheDestroyFunc key_destroy_func;
87 /* Associates keys with nodes */
88 GHashTable *key_table;
90 /* Associates nodes with keys */
91 GHashTable *value_table;
94 static inline GCacheNode*
95 g_cache_node_new (gpointer value)
97 GCacheNode *node = g_slice_new (GCacheNode);
104 g_cache_node_destroy (GCacheNode *node)
106 g_slice_free (GCacheNode, node);
111 * @value_new_func: a function to create a new object given a key.
112 * This is called by g_cache_insert() if an object
113 * with the given key does not already exist.
114 * @value_destroy_func: a function to destroy an object. It is called
115 * by g_cache_remove() when the object is no
116 * longer needed (i.e. its reference count drops
118 * @key_dup_func: a function to copy a key. It is called by
119 * g_cache_insert() if the key does not already exist in
121 * @key_destroy_func: a function to destroy a key. It is called by
122 * g_cache_remove() when the object is no longer
123 * needed (i.e. its reference count drops to 0).
124 * @hash_key_func: a function to create a hash value from a key.
125 * @hash_value_func: a function to create a hash value from a value.
126 * @key_equal_func: a function to compare two keys. It should return
127 * %TRUE if the two keys are equivalent.
128 * @Returns: a new #GCache.
130 * Creates a new #GCache.
134 * @key: a #GCache key.
135 * @Returns: a new #GCache value corresponding to the key.
137 * Specifies the type of the @value_new_func function passed to
138 * g_cache_new(). It is passed a #GCache key and should create the
139 * value corresponding to the key.
143 * @value: the #GCache value to destroy.
145 * Specifies the type of the @value_destroy_func and @key_destroy_func
146 * functions passed to g_cache_new(). The functions are passed a
147 * pointer to the #GCache key or #GCache value and should free any
148 * memory and other resources associated with it.
152 * @value: the #GCache key to destroy (<emphasis>not</emphasis> a
153 * #GCache value as it seems).
154 * @Returns: a copy of the #GCache key.
156 * Specifies the type of the @key_dup_func function passed to
157 * g_cache_new(). The function is passed a key
158 * (<emphasis>not</emphasis> a value as the prototype implies) and
159 * should return a duplicate of the key.
162 g_cache_new (GCacheNewFunc value_new_func,
163 GCacheDestroyFunc value_destroy_func,
164 GCacheDupFunc key_dup_func,
165 GCacheDestroyFunc key_destroy_func,
166 GHashFunc hash_key_func,
167 GHashFunc hash_value_func,
168 GEqualFunc key_equal_func)
172 g_return_val_if_fail (value_new_func != NULL, NULL);
173 g_return_val_if_fail (value_destroy_func != NULL, NULL);
174 g_return_val_if_fail (key_dup_func != NULL, NULL);
175 g_return_val_if_fail (key_destroy_func != NULL, NULL);
176 g_return_val_if_fail (hash_key_func != NULL, NULL);
177 g_return_val_if_fail (hash_value_func != NULL, NULL);
178 g_return_val_if_fail (key_equal_func != NULL, NULL);
180 cache = g_slice_new (GCache);
181 cache->value_new_func = value_new_func;
182 cache->value_destroy_func = value_destroy_func;
183 cache->key_dup_func = key_dup_func;
184 cache->key_destroy_func = key_destroy_func;
185 cache->key_table = g_hash_table_new (hash_key_func, key_equal_func);
186 cache->value_table = g_hash_table_new (hash_value_func, NULL);
195 * Frees the memory allocated for the #GCache.
197 * Note that it does not destroy the keys and values which were
198 * contained in the #GCache.
201 g_cache_destroy (GCache *cache)
203 g_return_if_fail (cache != NULL);
205 g_hash_table_destroy (cache->key_table);
206 g_hash_table_destroy (cache->value_table);
207 g_slice_free (GCache, cache);
213 * @key: a key describing a #GCache object.
214 * @Returns: a pointer to a #GCache value.
216 * Gets the value corresponding to the given key, creating it if
217 * necessary. It first checks if the value already exists in the
218 * #GCache, by using the @key_equal_func function passed to
219 * g_cache_new(). If it does already exist it is returned, and its
220 * reference count is increased by one. If the value does not currently
221 * exist, if is created by calling the @value_new_func. The key is
222 * duplicated by calling @key_dup_func and the duplicated key and value
223 * are inserted into the #GCache.
226 g_cache_insert (GCache *cache,
232 g_return_val_if_fail (cache != NULL, NULL);
234 node = g_hash_table_lookup (cache->key_table, key);
237 node->ref_count += 1;
241 key = (* cache->key_dup_func) (key);
242 value = (* cache->value_new_func) (key);
243 node = g_cache_node_new (value);
245 g_hash_table_insert (cache->key_table, key, node);
246 g_hash_table_insert (cache->value_table, value, key);
254 * @value: the value to remove.
256 * Decreases the reference count of the given value. If it drops to 0
257 * then the value and its corresponding key are destroyed, using the
258 * @value_destroy_func and @key_destroy_func passed to g_cache_new().
261 g_cache_remove (GCache *cache,
267 g_return_if_fail (cache != NULL);
269 key = g_hash_table_lookup (cache->value_table, value);
270 node = g_hash_table_lookup (cache->key_table, key);
272 g_return_if_fail (node != NULL);
274 node->ref_count -= 1;
275 if (node->ref_count == 0)
277 g_hash_table_remove (cache->value_table, value);
278 g_hash_table_remove (cache->key_table, key);
280 (* cache->key_destroy_func) (key);
281 (* cache->value_destroy_func) (node->value);
282 g_cache_node_destroy (node);
287 * g_cache_key_foreach:
289 * @func: the function to call with each #GCache key.
290 * @user_data: user data to pass to the function.
292 * Calls the given function for each of the keys in the #GCache.
294 * NOTE @func is passed three parameters, the value and key of a cache
295 * entry and the @user_data. The order of value and key is different
296 * from the order in which g_hash_table_foreach() passes key-value
297 * pairs to its callback function !
300 g_cache_key_foreach (GCache *cache,
304 g_return_if_fail (cache != NULL);
305 g_return_if_fail (func != NULL);
307 g_hash_table_foreach (cache->value_table, func, user_data);
311 * g_cache_value_foreach:
313 * @func: the function to call with each #GCache value.
314 * @user_data: user data to pass to the function.
316 * Calls the given function for each of the values in the #GCache.
318 * Deprecated:2.10: The reason is that it passes pointers to internal
319 * data structures to @func; use g_cache_key_foreach()
323 g_cache_value_foreach (GCache *cache,
327 g_return_if_fail (cache != NULL);
328 g_return_if_fail (func != NULL);
330 g_hash_table_foreach (cache->key_table, func, user_data);