2 This file is part of GNUnet
3 Copyright (C) 2006, 2009, 2015 GNUnet e.V.
5 GNUnet is free software: you can redistribute it and/or modify it
6 under the terms of the GNU General Public License as published
7 by the Free Software Foundation, either version 3 of the License,
8 or (at your option) any later version.
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Affero General Public License for more details.
17 * @author Christian Grothoff
20 * API for database backends for the datacache
22 * @defgroup datacache-plugin Data Cache plugin API
23 * API for database backends for the datacache
26 #ifndef PLUGIN_DATACACHE_H
27 #define PLUGIN_DATACACHE_H
29 #include "gnunet_datacache_lib.h"
34 #if 0 /* keep Emacsens' auto-indent happy */
41 * Function called by plugins to notify the datacache
42 * about content deletions.
45 * @param key key of the content that was deleted
46 * @param size number of bytes that were made available
49 (*GNUNET_DATACACHE_DeleteNotifyCallback) (void *cls,
50 const struct GNUNET_HashCode *key,
55 * The datastore service will pass a pointer to a struct
56 * of this type as the first and only argument to the
57 * entry point of each datastore plugin.
59 struct GNUNET_DATACACHE_PluginEnvironment
63 * Configuration to use.
65 const struct GNUNET_CONFIGURATION_Handle *cfg;
68 * Configuration section to use.
73 * Closure to use for callbacks.
78 * Function to call whenever the plugin needs to
79 * discard content that it was asked to store.
81 GNUNET_DATACACHE_DeleteNotifyCallback delete_notify;
84 * How much space are we allowed to use?
86 unsigned long long quota;
92 * @brief struct returned by the initialization function of the plugin
94 struct GNUNET_DATACACHE_PluginFunctions
98 * Closure to pass to all plugin functions.
103 * Store an item in the datastore.
105 * @param cls closure (internal context for the plugin)
106 * @param key key to store the value under
107 * @param xor_distance how close is @a key to our PID?
108 * @param size number of bytes in @a data
109 * @param data data to store
110 * @param type type of the value
111 * @param discard_time when to discard the value in any case
112 * @param path_info_len number of entries in @a path_info
113 * @param path_info a path through the network
114 * @return 0 if duplicate, -1 on error, number of bytes used otherwise
116 ssize_t (*put) (void *cls,
117 const struct GNUNET_HashCode *key,
118 uint32_t xor_distance,
121 enum GNUNET_BLOCK_Type type,
122 struct GNUNET_TIME_Absolute discard_time,
123 unsigned int path_info_len,
124 const struct GNUNET_PeerIdentity *path_info);
127 * Iterate over the results for a particular key
130 * @param cls closure (internal context for the plugin)
131 * @param key key to look for
132 * @param type entries of which type are relevant?
133 * @param iter maybe NULL (to just count)
134 * @param iter_cls closure for @a iter
135 * @return the number of results found
137 unsigned int (*get) (void *cls,
138 const struct GNUNET_HashCode *key,
139 enum GNUNET_BLOCK_Type type,
140 GNUNET_DATACACHE_Iterator iter,
144 * Delete the entry with the lowest expiration value
145 * from the datacache right now.
147 * @param cls closure (internal context for the plugin)
148 * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
150 int (*del) (void *cls);
153 * Return a random value from the datastore.
155 * @param cls closure (internal context for the plugin)
156 * @param iter maybe NULL (to just count)
157 * @param iter_cls closure for @a iter
158 * @return the number of results found (zero or one)
160 unsigned int (*get_random) (void *cls,
161 GNUNET_DATACACHE_Iterator iter,
166 * Iterate over the results that are "close" to a particular key in
167 * the datacache. "close" is defined as numerically larger than @a
168 * key (when interpreted as a circular address space), with small
171 * @param cls closure (internal context for the plugin)
172 * @param key area of the keyspace to look into
173 * @param num_results number of results that should be returned to @a iter
174 * @param iter maybe NULL (to just count)
175 * @param iter_cls closure for @a iter
176 * @return the number of results found
178 unsigned int (*get_closest) (void *cls,
179 const struct GNUNET_HashCode *key,
180 unsigned int num_results,
181 GNUNET_DATACACHE_Iterator iter,
187 #if 0 /* keep Emacsens' auto-indent happy */
196 /** @} */ /* end of group */