2 This file is part of GNUnet
3 Copyright (C) 2009, 2011 Christian Grothoff (and other contributing authors)
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3, or (at your
8 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 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA.
22 * @file include/gnunet_datastore_plugin.h
23 * @brief API for the database backend plugins.
24 * @author Christian Grothoff
26 #ifndef PLUGIN_DATASTORE_H
27 #define PLUGIN_DATASTORE_H
29 #include "gnunet_block_lib.h"
30 #include "gnunet_configuration_lib.h"
31 #include "gnunet_datastore_service.h"
32 #include "gnunet_statistics_service.h"
33 #include "gnunet_scheduler_lib.h"
37 * How many bytes of overhead will we assume per entry
38 * in any DB (for reservations)?
40 #define GNUNET_DATASTORE_ENTRY_OVERHEAD 256
44 * Function invoked to notify service of disk utilization
48 * @param delta change in disk utilization,
49 * 0 for "reset to empty"
51 typedef void (*DiskUtilizationChange) (void *cls, int delta);
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_DATASTORE_PluginEnvironment
62 * Configuration to use.
64 const struct GNUNET_CONFIGURATION_Handle *cfg;
67 * Function to call on disk utilization change.
69 DiskUtilizationChange duc;
80 * An processor over a set of items stored in the datastore.
83 * @param key key for the content
84 * @param size number of bytes in data
85 * @param data content stored
86 * @param type type of the content
87 * @param priority priority of the content
88 * @param anonymity anonymity-level for the content
89 * @param expiration expiration time for the content
90 * @param uid unique identifier for the datum
91 * @return #GNUNET_OK to keep the item
92 * #GNUNET_NO to delete the item
94 typedef int (*PluginDatumProcessor) (void *cls, const struct GNUNET_HashCode * key,
95 uint32_t size, const void *data,
96 enum GNUNET_BLOCK_Type type,
97 uint32_t priority, uint32_t anonymity,
98 struct GNUNET_TIME_Absolute expiration,
102 * Get an estimate of how much space the database is
105 * NB: estimate is an output parameter because emscripten cannot handle
106 * returning 64-bit integers from dynamically loaded modules.
109 * @param estimate location to store estimate
110 * @return number of bytes used on disk
112 typedef void (*PluginEstimateSize) (void *cls, unsigned long long *estimate);
119 * @param key key for the item stored
120 * @param size size of the item stored
121 * @param status GNUNET_OK or GNUNET_SYSERROR
122 * @param msg error message on error
124 typedef void (*PluginPutCont) (void *cls, const struct GNUNET_HashCode *key,
125 uint32_t size, int status, char *msg);
129 * Store an item in the datastore. If the item is already present,
130 * the priorities and replication levels are summed up and the higher
131 * expiration time and lower anonymity level is used.
134 * @param key key for the item
135 * @param size number of bytes in @a data
136 * @param data content stored
137 * @param type type of the content
138 * @param priority priority of the content
139 * @param anonymity anonymity-level for the content
140 * @param replication replication-level for the content
141 * @param expiration expiration time for the content
142 * @param cont continuation called with success or failure status
143 * @param cont_cls continuation closure
145 typedef void (*PluginPut) (void *cls, const struct GNUNET_HashCode * key,
147 const void *data, enum GNUNET_BLOCK_Type type,
148 uint32_t priority, uint32_t anonymity,
149 uint32_t replication,
150 struct GNUNET_TIME_Absolute expiration,
151 PluginPutCont cont, void *cont_cls);
155 * An processor over a set of keys stored in the datastore.
158 * @param key key in the data store, if NULL iteration is finished
159 * @param count how many values are stored under this key in the datastore
161 typedef void (*PluginKeyProcessor) (void *cls,
162 const struct GNUNET_HashCode *key,
167 * Get all of the keys in the datastore.
170 * @param proc function to call on each key
171 * @param proc_cls closure for @a proc
173 typedef void (*PluginGetKeys) (void *cls,
174 PluginKeyProcessor proc, void *proc_cls);
178 * Get one of the results for a particular key in the datastore.
181 * @param offset offset of the result (modulo num-results);
182 * specific ordering does not matter for the offset
183 * @param key key to match, never NULL
184 * @param vhash hash of the value, maybe NULL (to
185 * match all values that have the right key).
186 * Note that for DBlocks there is no difference
187 * betwen key and vhash, but for other blocks
189 * @param type entries of which type are relevant?
190 * Use 0 for any type.
191 * @param proc function to call on the matching value;
192 * proc should be called with NULL if there is no result
193 * @param proc_cls closure for @a proc
195 typedef void (*PluginGetKey) (void *cls, uint64_t offset,
196 const struct GNUNET_HashCode * key,
197 const struct GNUNET_HashCode * vhash,
198 enum GNUNET_BLOCK_Type type,
199 PluginDatumProcessor proc, void *proc_cls);
203 * Get a random item (additional constraints may apply depending on
204 * the specific implementation). Calls @a proc with all values ZERO or
205 * NULL if no item applies, otherwise @a proc is called once and only
209 * @param proc function to call the value (once only).
210 * @param proc_cls closure for @a proc
212 typedef void (*PluginGetRandom) (void *cls, PluginDatumProcessor proc,
217 * Update continuation.
220 * @param status GNUNET_OK or GNUNET_SYSERROR
221 * @param msg error message on error
223 typedef void (*PluginUpdateCont) (void *cls, int status, char *msg);
227 * Update the priority for a particular key in the datastore. If
228 * the expiration time in value is different than the time found in
229 * the datastore, the higher value should be kept. For the
230 * anonymity level, the lower value is to be used. The specified
231 * priority should be added to the existing priority, ignoring the
235 * @param uid unique identifier of the datum
236 * @param delta by how much should the priority
237 * change? If priority + delta < 0 the
238 * priority should be set to 0 (never go
240 * @param expire new expiration time should be the
241 * MAX of any existing expiration time and
243 * @param cont continuation called with success or failure status
244 * @param cons_cls continuation closure
246 typedef void (*PluginUpdate) (void *cls, uint64_t uid, int delta,
247 struct GNUNET_TIME_Absolute expire,
248 PluginUpdateCont cont, void *cont_cls);
252 * Select a single item from the datastore at the specified offset
253 * (among those applicable).
256 * @param offset offset of the result (modulo num-results);
257 * specific ordering does not matter for the offset
258 * @param type entries of which type should be considered?
259 * Must not be zero (ANY).
260 * @param proc function to call on the matching value
261 * @param proc_cls closure for @a proc
263 typedef void (*PluginGetType) (void *cls, uint64_t offset,
264 enum GNUNET_BLOCK_Type type,
265 PluginDatumProcessor proc, void *proc_cls);
273 typedef void (*PluginDrop) (void *cls);
278 * Each plugin is required to return a pointer to a struct of this
279 * type as the return value from its entry point.
281 struct GNUNET_DATASTORE_PluginFunctions
285 * Closure to use for all of the following callbacks
286 * (except "next_request").
291 * Calculate the current on-disk size of the SQ store. Estimates
292 * are fine, if that's the only thing available.
294 PluginEstimateSize estimate_size;
297 * Function to store an item in the datastore.
302 * Update the priority for a particular key in the datastore. If
303 * the expiration time in value is different than the time found in
304 * the datastore, the higher value should be kept. For the
305 * anonymity level, the lower value is to be used. The specified
306 * priority should be added to the existing priority, ignoring the
312 * Get a particular datum matching a given hash from the datastore.
314 PluginGetKey get_key;
317 * Get datum (of the specified type) with anonymity level zero.
318 * This function is allowed to ignore the 'offset' argument
319 * and instead return a random result (with zero anonymity of
320 * the correct type) if implementing an offset is expensive.
322 PluginGetType get_zero_anonymity;
325 * Function to get a random item with high replication score from
326 * the database, lowering the item's replication score. Returns a
327 * single random item from those with the highest replication
328 * counters. The item's replication counter is decremented by one
329 * IF it was positive before.
331 PluginGetRandom get_replication;
334 * Function to get a random expired item or, if none are expired,
335 * either the oldest entry or one with a low priority (depending
336 * on what was efficiently implementable).
338 PluginGetRandom get_expiration;
341 * Delete the database. The next operation is
342 * guaranteed to be unloading of the module.
347 * Iterate over all keys in the database.
349 PluginGetKeys get_keys;