/* GLIB - Library of useful routines for C programming

 * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, see <http://www.gnu.org/licenses/>.

 */

/*

 * Modified by the GLib Team and others 1997-2000.  See the AUTHORS

 * file for a list of people on the GLib Team.  See the ChangeLog

 * files for a list of changes.  These files are distributed with

 * GLib at ftp://ftp.gtk.org/pub/gtk/.

 */

/*

 * MT safe

 */

#include "config.h"

#include "gcache.h"

#include "gslice.h"

#include "ghash.h"

#include "gtestutils.h"

/**

 * SECTION:caches

 * @title: Caches

 * @short_description: caches allow sharing of complex data structures

 *                     to save resources

 *

 * A #GCache allows sharing of complex data structures, in order to

 * save system resources.

 *

 * GCache uses keys and values. A GCache key describes the properties

 * of a particular resource. A GCache value is the actual resource.

 *

 * GCache has been marked as deprecated, since this API is rarely

 * used and not very actively maintained.

 */

typedef struct _GCacheNode  GCacheNode;

struct _GCacheNode

{

  /* A reference counted node */

  gpointer value;

  gint ref_count;

};

/**

 * GCache:

 *

 * The #GCache struct is an opaque data structure containing

 * information about a #GCache. It should only be accessed via the

 * following functions.

 *

 * Deprecated:2.32: Use a #GHashTable instead

 */

struct _GCache

{

  /* Called to create a value from a key */

  GCacheNewFunc value_new_func;

  /* Called to destroy a value */

  GCacheDestroyFunc value_destroy_func;

  /* Called to duplicate a key */

  GCacheDupFunc key_dup_func;

  /* Called to destroy a key */

  GCacheDestroyFunc key_destroy_func;

  /* Associates keys with nodes */

  GHashTable *key_table;

  /* Associates nodes with keys */

  GHashTable *value_table;

};

static inline GCacheNode*

g_cache_node_new (gpointer value)

{

  GCacheNode *node = g_slice_new (GCacheNode);

  node->value = value;

  node->ref_count = 1;

  return node;

}

static inline void

g_cache_node_destroy (GCacheNode *node)

{

  g_slice_free (GCacheNode, node);

}

/**

 * g_cache_new:

 * @value_new_func: a function to create a new object given a key.

 *                  This is called by g_cache_insert() if an object

 *                  with the given key does not already exist

 * @value_destroy_func: a function to destroy an object. It is called

 *                      by g_cache_remove() when the object is no

 *                      longer needed (i.e. its reference count drops

 *                      to 0)

 * @key_dup_func: a function to copy a key. It is called by

 *                g_cache_insert() if the key does not already exist in

 *                the #GCache

 * @key_destroy_func: a function to destroy a key. It is called by

 *                    g_cache_remove() when the object is no longer

 *                    needed (i.e. its reference count drops to 0)

 * @hash_key_func: a function to create a hash value from a key

 * @hash_value_func: a function to create a hash value from a value

 * @key_equal_func: a function to compare two keys. It should return

 *                  %TRUE if the two keys are equivalent

 *

 * Creates a new #GCache.

 *

 * Returns: a new #GCache

 *

 * Deprecated:2.32: Use a #GHashTable instead

 */

/**

 * GCacheNewFunc:

 * @key: a #GCache key

 *

 * Specifies the type of the @value_new_func function passed to

 * g_cache_new(). It is passed a #GCache key and should create the

 * value corresponding to the key.

 *

 * Returns: a new #GCache value corresponding to the key.

 */

/**

 * GCacheDestroyFunc:

 * @value: the #GCache value to destroy

 *

 * Specifies the type of the @value_destroy_func and @key_destroy_func

 * functions passed to g_cache_new(). The functions are passed a

 * pointer to the #GCache key or #GCache value and should free any

 * memory and other resources associated with it.

 */

/**

 * GCacheDupFunc:

 * @value: the #GCache key to destroy (__not__ a

 *         #GCache value as it seems)

 *

 * Specifies the type of the @key_dup_func function passed to

 * g_cache_new(). The function is passed a key

 * (__not__ a value as the prototype implies) and

 * should return a duplicate of the key.

 *

 * Returns: a copy of the #GCache key

 */

GCache*

g_cache_new (GCacheNewFunc      value_new_func,

             GCacheDestroyFunc  value_destroy_func,

             GCacheDupFunc      key_dup_func,

             GCacheDestroyFunc  key_destroy_func,

             GHashFunc          hash_key_func,

             GHashFunc          hash_value_func,

             GEqualFunc         key_equal_func)

{

  GCache *cache;

  g_return_val_if_fail (value_new_func != NULL, NULL);

  g_return_val_if_fail (value_destroy_func != NULL, NULL);

  g_return_val_if_fail (key_dup_func != NULL, NULL);

  g_return_val_if_fail (key_destroy_func != NULL, NULL);

  g_return_val_if_fail (hash_key_func != NULL, NULL);

  g_return_val_if_fail (hash_value_func != NULL, NULL);

  g_return_val_if_fail (key_equal_func != NULL, NULL);

  cache = g_slice_new (GCache);

  cache->value_new_func = value_new_func;

  cache->value_destroy_func = value_destroy_func;

  cache->key_dup_func = key_dup_func;

  cache->key_destroy_func = key_destroy_func;

  cache->key_table = g_hash_table_new (hash_key_func, key_equal_func);

  cache->value_table = g_hash_table_new (hash_value_func, NULL);

  return cache;

}

/**

 * g_cache_destroy:

 * @cache: a #GCache

 *

 * Frees the memory allocated for the #GCache.

 *

 * Note that it does not destroy the keys and values which were

 * contained in the #GCache.

 *

 * Deprecated:2.32: Use a #GHashTable instead

 */

void

g_cache_destroy (GCache *cache)

{

  g_return_if_fail (cache != NULL);

  g_hash_table_destroy (cache->key_table);

  g_hash_table_destroy (cache->value_table);

  g_slice_free (GCache, cache);

}

/**

 * g_cache_insert:

 * @cache: a #GCache

 * @key: a key describing a #GCache object

 *

 * Gets the value corresponding to the given key, creating it if

 * necessary. It first checks if the value already exists in the

 * #GCache, by using the @key_equal_func function passed to

 * g_cache_new(). If it does already exist it is returned, and its

 * reference count is increased by one. If the value does not currently

 * exist, if is created by calling the @value_new_func. The key is

 * duplicated by calling @key_dup_func and the duplicated key and value

 * are inserted into the #GCache.

 *

 * Returns: a pointer to a #GCache value

 *

 * Deprecated:2.32: Use a #GHashTable instead

 */

gpointer

g_cache_insert (GCache   *cache,

                gpointer  key)

{

  GCacheNode *node;

  gpointer value;

  g_return_val_if_fail (cache != NULL, NULL);

  node = g_hash_table_lookup (cache->key_table, key);

  if (node)

    {

      node->ref_count += 1;

      return node->value;

    }

  key = (* cache->key_dup_func) (key);

  value = (* cache->value_new_func) (key);

  node = g_cache_node_new (value);

  g_hash_table_insert (cache->key_table, key, node);

  g_hash_table_insert (cache->value_table, value, key);

  return node->value;

}

/**

 * g_cache_remove:

 * @cache: a #GCache

 * @value: the value to remove

 *

 * Decreases the reference count of the given value. If it drops to 0

 * then the value and its corresponding key are destroyed, using the

 * @value_destroy_func and @key_destroy_func passed to g_cache_new().

 *

 * Deprecated:2.32: Use a #GHashTable instead

 */

void

g_cache_remove (GCache        *cache,

                gconstpointer  value)

{

  GCacheNode *node;

  gpointer key;

  g_return_if_fail (cache != NULL);

  key = g_hash_table_lookup (cache->value_table, value);

  node = g_hash_table_lookup (cache->key_table, key);

  g_return_if_fail (node != NULL);

  node->ref_count -= 1;

  if (node->ref_count == 0)

    {

      g_hash_table_remove (cache->value_table, value);

      g_hash_table_remove (cache->key_table, key);

      (* cache->key_destroy_func) (key);

      (* cache->value_destroy_func) (node->value);

      g_cache_node_destroy (node);

    }

}

/**

 * g_cache_key_foreach:

 * @cache: a #GCache

 * @func: the function to call with each #GCache key

 * @user_data: user data to pass to the function

 *

 * Calls the given function for each of the keys in the #GCache.

 *

 * NOTE @func is passed three parameters, the value and key of a cache

 * entry and the @user_data. The order of value and key is different

 * from the order in which g_hash_table_foreach() passes key-value

 * pairs to its callback function !

 *

 * Deprecated:2.32: Use a #GHashTable instead

 */

void

g_cache_key_foreach (GCache   *cache,

                     GHFunc    func,

                     gpointer  user_data)

{

  g_return_if_fail (cache != NULL);

  g_return_if_fail (func != NULL);

  g_hash_table_foreach (cache->value_table, func, user_data);

}

/**

 * g_cache_value_foreach:

 * @cache: a #GCache

 * @func: the function to call with each #GCache value

 * @user_data: user data to pass to the function

 *

 * Calls the given function for each of the values in the #GCache.

 *

 * Deprecated:2.10: The reason is that it passes pointers to internal

 *    data structures to @func; use g_cache_key_foreach() instead

 */

void

g_cache_value_foreach (GCache   *cache,

                       GHFunc    func,

                       gpointer  user_data)

{

  g_return_if_fail (cache != NULL);

  g_return_if_fail (func != NULL);

  g_hash_table_foreach (cache->key_table, func, user_data);

}