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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 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,
203 * Get one of the results for a particular key in the datastore.
206 * @param offset offset of the result (modulo num-results);
207 * specific ordering does not matter for the offset
208 * @param key key to match, never NULL
209 * @param vhash hash of the value, maybe NULL (to
210 * match all values that have the right key).
211 * Note that for DBlocks there is no difference
212 * betwen key and vhash, but for other blocks
214 * @param type entries of which type are relevant?
215 * Use 0 for any type.
216 * @param proc function to call on the matching value;
217 * proc should be called with NULL if there is no result
218 * @param proc_cls closure for @a proc
221 (*PluginGetKey) (void *cls,
223 const struct GNUNET_HashCode *key,
224 const struct GNUNET_HashCode *vhash,
225 enum GNUNET_BLOCK_Type type,
226 PluginDatumProcessor proc,
231 * Get a random item (additional constraints may apply depending on
232 * the specific implementation). Calls @a proc with all values ZERO or
233 * NULL if no item applies, otherwise @a proc is called once and only
237 * @param proc function to call the value (once only).
238 * @param proc_cls closure for @a proc
241 (*PluginGetRandom) (void *cls,
242 PluginDatumProcessor proc,
247 * Update continuation.
250 * @param status #GNUNET_OK or #GNUNET_SYSERR
251 * @param msg error message on error
254 (*PluginUpdateCont) (void *cls,
260 * Update the priority for a particular key in the datastore. If
261 * the expiration time in value is different than the time found in
262 * the datastore, the higher value should be kept. For the
263 * anonymity level, the lower value is to be used. The specified
264 * priority should be added to the existing priority, ignoring the
268 * @param uid unique identifier of the datum
269 * @param delta by how much should the priority
270 * change? If priority + delta < 0 the
271 * priority should be set to 0 (never go
273 * @param expire new expiration time should be the
274 * MAX of any existing expiration time and
276 * @param cont continuation called with success or failure status
277 * @param cons_cls continuation closure
280 (*PluginUpdate) (void *cls,
283 struct GNUNET_TIME_Absolute expire,
284 PluginUpdateCont cont,
289 * Select a single item from the datastore at the specified offset
290 * (among those applicable).
293 * @param offset offset of the result (modulo num-results);
294 * specific ordering does not matter for the offset
295 * @param type entries of which type should be considered?
296 * Must not be zero (ANY).
297 * @param proc function to call on the matching value
298 * @param proc_cls closure for @a proc
301 (*PluginGetType) (void *cls,
303 enum GNUNET_BLOCK_Type type,
304 PluginDatumProcessor proc,
314 (*PluginDrop) (void *cls);
318 * Each plugin is required to return a pointer to a struct of this
319 * type as the return value from its entry point.
321 struct GNUNET_DATASTORE_PluginFunctions
325 * Closure to use for all of the following callbacks
326 * (except "next_request").
331 * Calculate the current on-disk size of the SQ store. Estimates
332 * are fine, if that's the only thing available.
334 PluginEstimateSize estimate_size;
337 * Function to store an item in the datastore.
342 * Update the priority for a particular key in the datastore. If
343 * the expiration time in value is different than the time found in
344 * the datastore, the higher value should be kept. For the
345 * anonymity level, the lower value is to be used. The specified
346 * priority should be added to the existing priority, ignoring the
352 * Get a particular datum matching a given hash from the datastore.
354 PluginGetKey get_key;
357 * Get datum (of the specified type) with anonymity level zero.
358 * This function is allowed to ignore the 'offset' argument
359 * and instead return a random result (with zero anonymity of
360 * the correct type) if implementing an offset is expensive.
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 */