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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,
165 const struct GNUNET_HashCode *key,
168 enum GNUNET_BLOCK_Type type,
171 uint32_t replication,
172 struct GNUNET_TIME_Absolute expiration,
178 * An processor over a set of keys stored in the datastore.
181 * @param key key in the data store, if NULL iteration is finished
182 * @param count how many values are stored under this key in the datastore
185 (*PluginKeyProcessor) (void *cls,
186 const struct GNUNET_HashCode *key,
191 * Get all of the keys in the datastore.
194 * @param proc function to call on each key
195 * @param proc_cls closure for @a proc
198 (*PluginGetKeys) (void *cls,
199 PluginKeyProcessor proc,
204 * Get one of the results for a particular key in the datastore.
207 * @param offset offset of the result (modulo num-results);
208 * specific ordering does not matter for the offset
209 * @param key key to match, never NULL
210 * @param vhash hash of the value, maybe NULL (to
211 * match all values that have the right key).
212 * Note that for DBlocks there is no difference
213 * betwen key and vhash, but for other blocks
215 * @param type entries of which type are relevant?
216 * Use 0 for any type.
217 * @param proc function to call on the matching value;
218 * proc should be called with NULL if there is no result
219 * @param proc_cls closure for @a proc
222 (*PluginGetKey) (void *cls,
224 const struct GNUNET_HashCode *key,
225 const struct GNUNET_HashCode *vhash,
226 enum GNUNET_BLOCK_Type type,
227 PluginDatumProcessor proc,
232 * Get a random item (additional constraints may apply depending on
233 * the specific implementation). Calls @a proc with all values ZERO or
234 * NULL if no item applies, otherwise @a proc is called once and only
238 * @param proc function to call the value (once only).
239 * @param proc_cls closure for @a proc
242 (*PluginGetRandom) (void *cls,
243 PluginDatumProcessor proc,
248 * Update continuation.
251 * @param status #GNUNET_OK or #GNUNET_SYSERR
252 * @param msg error message on error
255 (*PluginUpdateCont) (void *cls,
261 * Update the priority for a particular key in the datastore. If
262 * the expiration time in value is different than the time found in
263 * the datastore, the higher value should be kept. For the
264 * anonymity level, the lower value is to be used. The specified
265 * priority should be added to the existing priority, ignoring the
269 * @param uid unique identifier of the datum
270 * @param delta by how much should the priority
271 * change? If priority + delta < 0 the
272 * priority should be set to 0 (never go
274 * @param expire new expiration time should be the
275 * MAX of any existing expiration time and
277 * @param cont continuation called with success or failure status
278 * @param cons_cls continuation closure
281 (*PluginUpdate) (void *cls,
284 struct GNUNET_TIME_Absolute expire,
285 PluginUpdateCont cont,
290 * Select a single item from the datastore at the specified offset
291 * (among those applicable).
294 * @param offset offset of the result (modulo num-results);
295 * specific ordering does not matter for the offset
296 * @param type entries of which type should be considered?
297 * Must not be zero (ANY).
298 * @param proc function to call on the matching value
299 * @param proc_cls closure for @a proc
302 (*PluginGetType) (void *cls,
304 enum GNUNET_BLOCK_Type type,
305 PluginDatumProcessor proc,
315 (*PluginDrop) (void *cls);
319 * Each plugin is required to return a pointer to a struct of this
320 * type as the return value from its entry point.
322 struct GNUNET_DATASTORE_PluginFunctions
326 * Closure to use for all of the following callbacks
327 * (except "next_request").
332 * Calculate the current on-disk size of the SQ store. Estimates
333 * are fine, if that's the only thing available.
335 PluginEstimateSize estimate_size;
338 * Function to store an item in the datastore.
343 * Update the priority for a particular key in the datastore. If
344 * the expiration time in value is different than the time found in
345 * the datastore, the higher value should be kept. For the
346 * anonymity level, the lower value is to be used. The specified
347 * priority should be added to the existing priority, ignoring the
353 * Get a particular datum matching a given hash from the datastore.
355 PluginGetKey get_key;
358 * Get datum (of the specified type) with anonymity level zero.
359 * This function is allowed to ignore the 'offset' argument
360 * and instead return a random result (with zero anonymity of
361 * the correct type) if implementing an offset is expensive.
363 PluginGetType get_zero_anonymity;
366 * Function to get a random item with high replication score from
367 * the database, lowering the item's replication score. Returns a
368 * single random item from those with the highest replication
369 * counters. The item's replication counter is decremented by one
370 * IF it was positive before.
372 PluginGetRandom get_replication;
375 * Function to get a random expired item or, if none are expired,
376 * either the oldest entry or one with a low priority (depending
377 * on what was efficiently implementable).
379 PluginGetRandom get_expiration;
382 * Delete the database. The next operation is
383 * guaranteed to be unloading of the module.
388 * Iterate over all keys in the database.
390 PluginGetKeys get_keys;
396 /** @} */ /* end of group */