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.
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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.
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18 Boston, MA 02110-1301, USA.
22 * @author Christian Grothoff
25 * API for the database backend plugins.
27 * @defgroup datastore-plugin Datastore service plugin API
28 * API for the database backend plugins.
31 #ifndef PLUGIN_DATASTORE_H
32 #define PLUGIN_DATASTORE_H
34 #include "gnunet_block_lib.h"
35 #include "gnunet_configuration_lib.h"
36 #include "gnunet_datastore_service.h"
37 #include "gnunet_statistics_service.h"
38 #include "gnunet_scheduler_lib.h"
42 * How many bytes of overhead will we assume per entry
43 * in any DB (for reservations)?
45 #define GNUNET_DATASTORE_ENTRY_OVERHEAD 256
49 * Function invoked to notify service of disk utilization
53 * @param delta change in disk utilization,
54 * 0 for "reset to empty"
57 (*GNUNET_DATASTORE_DiskUtilizationChange) (void *cls,
62 * The datastore service will pass a pointer to a struct
63 * of this type as the first and only argument to the
64 * entry point of each datastore plugin.
66 struct GNUNET_DATASTORE_PluginEnvironment
69 * Configuration to use.
71 const struct GNUNET_CONFIGURATION_Handle *cfg;
74 * Function to call on disk utilization change.
76 GNUNET_DATASTORE_DiskUtilizationChange duc;
87 * An processor over a set of items stored in the datastore.
90 * @param key key for the content
91 * @param size number of bytes in data
92 * @param data content stored
93 * @param type type of the content
94 * @param priority priority of the content
95 * @param anonymity anonymity-level for the content
96 * @param expiration expiration time for the content
97 * @param uid unique identifier for the datum
98 * @return #GNUNET_OK to keep the item
99 * #GNUNET_NO to delete the item
102 (*PluginDatumProcessor) (void *cls,
103 const struct GNUNET_HashCode *key,
106 enum GNUNET_BLOCK_Type type,
109 struct GNUNET_TIME_Absolute expiration,
114 * Get an estimate of how much space the database is
117 * NB: estimate is an output parameter because emscripten cannot handle
118 * returning 64-bit integers from dynamically loaded modules.
121 * @param estimate location to store estimate
122 * @return number of bytes used on disk
125 (*PluginEstimateSize) (void *cls,
126 unsigned long long *estimate);
133 * @param key key for the item stored
134 * @param size size of the item stored
135 * @param status #GNUNET_OK or #GNUNET_SYSERROR
136 * @param msg error message on error
139 (*PluginPutCont) (void *cls,
140 const struct GNUNET_HashCode *key,
147 * Store an item in the datastore. If the item is already present,
148 * the priorities and replication levels are summed up and the higher
149 * expiration time and lower anonymity level is used.
152 * @param key key for the item
153 * @param size number of bytes in @a data
154 * @param data content stored
155 * @param type type of the content
156 * @param priority priority of the content
157 * @param anonymity anonymity-level for the content
158 * @param replication replication-level for the content
159 * @param expiration expiration time for the content
160 * @param cont continuation called with success or failure status
161 * @param cont_cls continuation closure for @a cont
164 (*PluginPut) (void *cls, const struct GNUNET_HashCode *key,
167 enum GNUNET_BLOCK_Type type,
170 uint32_t replication,
171 struct GNUNET_TIME_Absolute expiration,
177 * An processor over a set of keys stored in the datastore.
180 * @param key key in the data store, if NULL iteration is finished
181 * @param count how many values are stored under this key in the datastore
184 (*PluginKeyProcessor) (void *cls,
185 const struct GNUNET_HashCode *key,
190 * Get all of the keys in the datastore.
193 * @param proc function to call on each key
194 * @param proc_cls closure for @a proc
197 (*PluginGetKeys) (void *cls,
198 PluginKeyProcessor proc, void *proc_cls);
202 * Get one of the results for a particular key in the datastore.
205 * @param offset offset of the result (modulo num-results);
206 * specific ordering does not matter for the offset
207 * @param key key to match, never NULL
208 * @param vhash hash of the value, maybe NULL (to
209 * match all values that have the right key).
210 * Note that for DBlocks there is no difference
211 * betwen key and vhash, but for other blocks
213 * @param type entries of which type are relevant?
214 * Use 0 for any type.
215 * @param proc function to call on the matching value;
216 * proc should be called with NULL if there is no result
217 * @param proc_cls closure for @a proc
220 (*PluginGetKey) (void *cls,
222 const struct GNUNET_HashCode *key,
223 const struct GNUNET_HashCode *vhash,
224 enum GNUNET_BLOCK_Type type,
225 PluginDatumProcessor proc,
230 * Get a random item (additional constraints may apply depending on
231 * the specific implementation). Calls @a proc with all values ZERO or
232 * NULL if no item applies, otherwise @a proc is called once and only
236 * @param proc function to call the value (once only).
237 * @param proc_cls closure for @a proc
240 (*PluginGetRandom) (void *cls,
241 PluginDatumProcessor proc,
246 * Update continuation.
249 * @param status #GNUNET_OK or #GNUNET_SYSERROR
250 * @param msg error message on error
253 (*PluginUpdateCont) (void *cls,
259 * Update the priority for a particular key in the datastore. If
260 * the expiration time in value is different than the time found in
261 * the datastore, the higher value should be kept. For the
262 * anonymity level, the lower value is to be used. The specified
263 * priority should be added to the existing priority, ignoring the
267 * @param uid unique identifier of the datum
268 * @param delta by how much should the priority
269 * change? If priority + delta < 0 the
270 * priority should be set to 0 (never go
272 * @param expire new expiration time should be the
273 * MAX of any existing expiration time and
275 * @param cont continuation called with success or failure status
276 * @param cons_cls continuation closure
279 (*PluginUpdate) (void *cls,
282 struct GNUNET_TIME_Absolute expire,
283 PluginUpdateCont cont,
288 * Select a single item from the datastore at the specified offset
289 * (among those applicable).
292 * @param offset offset of the result (modulo num-results);
293 * specific ordering does not matter for the offset
294 * @param type entries of which type should be considered?
295 * Must not be zero (ANY).
296 * @param proc function to call on the matching value
297 * @param proc_cls closure for @a proc
300 (*PluginGetType) (void *cls,
302 enum GNUNET_BLOCK_Type type,
303 PluginDatumProcessor proc,
313 (*PluginDrop) (void *cls);
317 * Each plugin is required to return a pointer to a struct of this
318 * type as the return value from its entry point.
320 struct GNUNET_DATASTORE_PluginFunctions
324 * Closure to use for all of the following callbacks
325 * (except "next_request").
330 * Calculate the current on-disk size of the SQ store. Estimates
331 * are fine, if that's the only thing available.
333 PluginEstimateSize estimate_size;
336 * Function to store an item in the datastore.
341 * Update the priority for a particular key in the datastore. If
342 * the expiration time in value is different than the time found in
343 * the datastore, the higher value should be kept. For the
344 * anonymity level, the lower value is to be used. The specified
345 * priority should be added to the existing priority, ignoring the
351 * Get a particular datum matching a given hash from the datastore.
353 PluginGetKey get_key;
356 * Get datum (of the specified type) with anonymity level zero.
357 * This function is allowed to ignore the 'offset' argument
358 * and instead return a random result (with zero anonymity of
359 * the correct type) if implementing an offset is expensive.
361 PluginGetType get_zero_anonymity;
364 * Function to get a random item with high replication score from
365 * the database, lowering the item's replication score. Returns a
366 * single random item from those with the highest replication
367 * counters. The item's replication counter is decremented by one
368 * IF it was positive before.
370 PluginGetRandom get_replication;
373 * Function to get a random expired item or, if none are expired,
374 * either the oldest entry or one with a low priority (depending
375 * on what was efficiently implementable).
377 PluginGetRandom get_expiration;
380 * Delete the database. The next operation is
381 * guaranteed to be unloading of the module.
386 * Iterate over all keys in the database.
388 PluginGetKeys get_keys;
392 /** @} */ /* end of group */