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22 * @author Christian Grothoff
25 * API for the database backend plugins.
27 * @defgroup datastore-plugin Data Store 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 replication replication-level for the content
97 * @param expiration expiration time for the content
98 * @param uid unique identifier for the datum
99 * @return #GNUNET_OK to keep the item
100 * #GNUNET_NO to delete the item
103 (*PluginDatumProcessor) (void *cls,
104 const struct GNUNET_HashCode *key,
107 enum GNUNET_BLOCK_Type type,
110 uint32_t replication,
111 struct GNUNET_TIME_Absolute expiration,
116 * Get an estimate of how much space the database is
119 * NB: estimate is an output parameter because emscripten cannot handle
120 * returning 64-bit integers from dynamically loaded modules.
123 * @param estimate location to store estimate
124 * @return number of bytes used on disk
127 (*PluginEstimateSize) (void *cls,
128 unsigned long long *estimate);
135 * @param key key for the item stored
136 * @param size size of the item stored
137 * @param status #GNUNET_OK or #GNUNET_SYSERROR
138 * @param msg error message on error
141 (*PluginPutCont) (void *cls,
142 const struct GNUNET_HashCode *key,
149 * Store an item in the datastore. If the item is already present,
150 * the priorities and replication levels are summed up and the higher
151 * expiration time and lower anonymity level is used.
154 * @param key key for the item
155 * @param size number of bytes in @a data
156 * @param data content stored
157 * @param type type of the content
158 * @param priority priority of the content
159 * @param anonymity anonymity-level for the content
160 * @param replication replication-level for the content
161 * @param expiration expiration time for the content
162 * @param cont continuation called with success or failure status
163 * @param cont_cls continuation closure for @a cont
166 (*PluginPut) (void *cls,
167 const struct GNUNET_HashCode *key,
170 enum GNUNET_BLOCK_Type type,
173 uint32_t replication,
174 struct GNUNET_TIME_Absolute expiration,
180 * An processor over a set of keys stored in the datastore.
183 * @param key key in the data store, if NULL iteration is finished
184 * @param count how many values are stored under this key in the datastore
187 (*PluginKeyProcessor) (void *cls,
188 const struct GNUNET_HashCode *key,
193 * Get all of the keys in the datastore.
196 * @param proc function to call on each key
197 * @param proc_cls closure for @a proc
200 (*PluginGetKeys) (void *cls,
201 PluginKeyProcessor proc,
206 * Get one of the results for a particular key in the datastore.
209 * @param next_uid return the result with lowest uid >= next_uid
210 * @param random if true, return a random result instead of using next_uid
211 * @param key maybe NULL (to match all entries)
212 * @param vhash hash of the value, maybe NULL (to
213 * match all values that have the right key).
214 * Note that for DBlocks there is no difference
215 * betwen key and vhash, but for other blocks
217 * @param type entries of which type are relevant?
218 * Use 0 for any type.
219 * @param proc function to call on the matching value;
220 * will be called with NULL if nothing matches
221 * @param proc_cls closure for @a proc
224 (*PluginGetKey) (void *cls,
227 const struct GNUNET_HashCode *key,
228 const struct GNUNET_HashCode *vhash,
229 enum GNUNET_BLOCK_Type type,
230 PluginDatumProcessor proc,
235 * Get a random item (additional constraints may apply depending on
236 * the specific implementation). Calls @a proc with all values ZERO or
237 * NULL if no item applies, otherwise @a proc is called once and only
241 * @param proc function to call the value (once only).
242 * @param proc_cls closure for @a proc
245 (*PluginGetRandom) (void *cls,
246 PluginDatumProcessor proc,
251 * Update continuation.
254 * @param status #GNUNET_OK or #GNUNET_SYSERR
255 * @param msg error message on error
258 (*PluginUpdateCont) (void *cls,
264 * Update the priority, replication and expiration for a particular
265 * unique ID in the datastore. If the expiration time in value is
266 * different than the time found in the datastore, the higher value
267 * should be kept. The specified priority and replication is added
268 * to the existing value.
271 * @param uid unique identifier of the datum
272 * @param priority by how much should the priority
274 * @param replication by how much should the replication
276 * @param expire new expiration time should be the
277 * MAX of any existing expiration time and
279 * @param cont continuation called with success or failure status
280 * @param cons_cls continuation closure
283 (*PluginUpdate) (void *cls,
286 uint32_t replication,
287 struct GNUNET_TIME_Absolute expire,
288 PluginUpdateCont cont,
293 * Select a single item from the datastore (among those applicable).
296 * @param next_uid return the result with lowest uid >= next_uid
297 * @param type entries of which type should be considered?
298 * Must not be zero (ANY).
299 * @param proc function to call on the matching value;
300 * will be called with NULL if no value matches
301 * @param proc_cls closure for @a proc
304 (*PluginGetType) (void *cls,
306 enum GNUNET_BLOCK_Type type,
307 PluginDatumProcessor proc,
317 (*PluginDrop) (void *cls);
321 * Each plugin is required to return a pointer to a struct of this
322 * type as the return value from its entry point.
324 struct GNUNET_DATASTORE_PluginFunctions
328 * Closure to use for all of the following callbacks
329 * (except "next_request").
334 * Calculate the current on-disk size of the SQ store. Estimates
335 * are fine, if that's the only thing available.
337 PluginEstimateSize estimate_size;
340 * Function to store an item in the datastore.
345 * Update the priority for a particular key in the datastore. If
346 * the expiration time in value is different than the time found in
347 * the datastore, the higher value should be kept. For the
348 * anonymity level, the lower value is to be used. The specified
349 * priority should be added to the existing priority, ignoring the
355 * Get a particular datum matching a given hash from the datastore.
357 PluginGetKey get_key;
360 * Get datum (of the specified type) with anonymity level zero.
362 PluginGetType get_zero_anonymity;
365 * Function to get a random item with high replication score from
366 * the database, lowering the item's replication score. Returns a
367 * single random item from those with the highest replication
368 * counters. The item's replication counter is decremented by one
369 * IF it was positive before.
371 PluginGetRandom get_replication;
374 * Function to get a random expired item or, if none are expired,
375 * either the oldest entry or one with a low priority (depending
376 * on what was efficiently implementable).
378 PluginGetRandom get_expiration;
381 * Delete the database. The next operation is
382 * guaranteed to be unloading of the module.
387 * Iterate over all keys in the database.
389 PluginGetKeys get_keys;
395 /** @} */ /* end of group */