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3 Copyright (C) 2013, 2014 GNUnet e.V.
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6 under the terms of the GNU Affero General Public License as published
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18 SPDX-License-Identifier: AGPL3.0-or-later
22 * @author Florian Dold
23 * @author Christian Grothoff
26 * Two-peer set operations
28 * @defgroup set Set service
29 * Two-peer set operations
31 * @see [Documentation](https://gnunet.org/set-subsystem)
36 #ifndef GNUNET_SET_SERVICE_H
37 #define GNUNET_SET_SERVICE_H
42 #if 0 /* keep Emacsens' auto-indent happy */
47 #include "gnunet_common.h"
48 #include "gnunet_time_lib.h"
49 #include "gnunet_configuration_lib.h"
53 * Maximum size of a context message for set operation requests.
55 #define GNUNET_SET_CONTEXT_MESSAGE_MAX_SIZE ((1<<16) - 1024)
59 * Opaque handle to a set.
61 struct GNUNET_SET_Handle;
64 * Opaque handle to a set operation request from another peer.
66 struct GNUNET_SET_Request;
69 * Opaque handle to a listen operation.
71 struct GNUNET_SET_ListenHandle;
74 * Opaque handle to a set operation.
76 struct GNUNET_SET_OperationHandle;
80 * The operation that a set set supports.
82 enum GNUNET_SET_OperationType
85 * A purely local set that does not support any operation.
87 GNUNET_SET_OPERATION_NONE,
90 * Set intersection, only return elements that are in both sets.
92 GNUNET_SET_OPERATION_INTERSECTION,
95 * Set union, return all elements that are in at least one of the sets.
97 GNUNET_SET_OPERATION_UNION
102 * Status for the result callback
104 enum GNUNET_SET_Status
107 * Everything went ok, we are transmitting an element of the
108 * result (in set, or to be removed from set, depending on
109 * the `enum GNUNET_SET_ResultMode`).
112 * #GNUNET_SET_RESULT_FULL,
113 * #GNUNET_SET_RESULT_ADDED,
114 * #GNUNET_SET_RESULT_REMOVED,
116 GNUNET_SET_STATUS_OK,
119 * Element should be added to the result set
120 * of the local peer, i.e. the local peer is
121 * missing an element.
123 * Only applies to #GNUNET_SET_RESULT_SYMMETRIC
125 GNUNET_SET_STATUS_ADD_LOCAL,
128 * Element should be added to the result set
129 * of the remote peer, i.e. the remote peer is
130 * missing an element.
132 * Only applies to #GNUNET_SET_RESULT_SYMMETRIC
134 GNUNET_SET_STATUS_ADD_REMOTE,
137 * The other peer refused to to the operation with us,
138 * or something went wrong.
140 GNUNET_SET_STATUS_FAILURE,
143 * Success, all elements have been returned (but the other peer
144 * might still be receiving some from us, so we are not done). Only
145 * used during UNION operation.
147 GNUNET_SET_STATUS_HALF_DONE,
150 * Success, all elements have been sent (and received).
152 GNUNET_SET_STATUS_DONE
158 * The way results are given to the client.
160 enum GNUNET_SET_ResultMode
163 * Client gets every element in the resulting set.
165 * Only supported for set intersection.
167 GNUNET_SET_RESULT_FULL,
170 * Client gets notified of the required changes
171 * for both the local and the remote set.
173 * Only supported for set
175 GNUNET_SET_RESULT_SYMMETRIC,
178 * Client gets only elements that have been removed from the set.
180 * Only supported for set intersection.
182 GNUNET_SET_RESULT_REMOVED,
185 * Client gets only elements that have been added to the set.
187 * Only supported for set union.
189 GNUNET_SET_RESULT_ADDED
194 * Element stored in a set.
196 struct GNUNET_SET_Element
199 * Number of bytes in the buffer pointed to by data.
204 * Application-specific element type.
206 uint16_t element_type;
209 * Actual data of the element
216 * Possible options to pass to a set operation.
218 * Used as tag for struct #GNUNET_SET_Option.
220 enum GNUNET_SET_OptionType
225 GNUNET_SET_OPTION_END=0,
227 * Fail set operations when the other peer shows weird behavior
228 * that might by a Byzantine fault.
230 * For set union, 'v.num' is a lower bound on elements
231 * that the other peer must have in common with us.
233 GNUNET_SET_OPTION_BYZANTINE=1,
235 * Do not use the optimized set operation, but send full sets.
236 * Might trigger Byzantine fault detection.
238 GNUNET_SET_OPTION_FORCE_FULL=2,
240 * Only use optimized set operations, even though for this
241 * particular set operation they might be much slower.
242 * Might trigger Byzantine fault detection.
244 GNUNET_SET_OPTION_FORCE_DELTA=4,
249 * Option for set operations.
251 struct GNUNET_SET_Option
254 * Type of the option.
256 enum GNUNET_SET_OptionType type;
259 * Value for the option, only used with some options.
268 * Continuation used for some of the set operations
273 (*GNUNET_SET_Continuation) (void *cls);
277 * Callback for set operation results. Called for each element
281 * @param element a result element, only valid if status is #GNUNET_SET_STATUS_OK
282 * @param current_size current set size
283 * @param status see `enum GNUNET_SET_Status`
286 (*GNUNET_SET_ResultIterator) (void *cls,
287 const struct GNUNET_SET_Element *element,
288 uint64_t current_size,
289 enum GNUNET_SET_Status status);
292 * Iterator for set elements.
295 * @param element the current element, NULL if all elements have been
297 * @return #GNUNET_YES to continue iterating, #GNUNET_NO to stop.
300 (*GNUNET_SET_ElementIterator) (void *cls,
301 const struct GNUNET_SET_Element *element);
305 * Called when another peer wants to do a set operation with the
306 * local peer. If a listen error occurs, the @a request is NULL.
309 * @param other_peer the other peer
310 * @param context_msg message with application specific information from
312 * @param request request from the other peer (never NULL), use GNUNET_SET_accept()
313 * to accept it, otherwise the request will be refused
314 * Note that we can't just return value from the listen callback,
315 * as it is also necessary to specify the set we want to do the
316 * operation with, whith sometimes can be derived from the context
317 * message. It's necessary to specify the timeout.
320 (*GNUNET_SET_ListenCallback) (void *cls,
321 const struct GNUNET_PeerIdentity *other_peer,
322 const struct GNUNET_MessageHeader *context_msg,
323 struct GNUNET_SET_Request *request);
328 (*GNUNET_SET_CopyReadyCallback) (void *cls,
329 struct GNUNET_SET_Handle *copy);
333 * Create an empty set, supporting the specified operation.
335 * @param cfg configuration to use for connecting to the
337 * @param op operation supported by the set
338 * Note that the operation has to be specified
339 * beforehand, as certain set operations need to maintain
340 * data structures spefific to the operation
341 * @return a handle to the set
343 struct GNUNET_SET_Handle *
344 GNUNET_SET_create (const struct GNUNET_CONFIGURATION_Handle *cfg,
345 enum GNUNET_SET_OperationType op);
349 * Add an element to the given set.
350 * After the element has been added (in the sense of being
351 * transmitted to the set service), @a cont will be called.
352 * Calls to #GNUNET_SET_add_element can be queued
354 * @param set set to add element to
355 * @param element element to add to the set
356 * @param cont continuation called after the element has been added
357 * @param cont_cls closure for @a cont
358 * @return #GNUNET_OK on success, #GNUNET_SYSERR if the
359 * set is invalid (e.g. the set service crashed)
362 GNUNET_SET_add_element (struct GNUNET_SET_Handle *set,
363 const struct GNUNET_SET_Element *element,
364 GNUNET_SET_Continuation cont,
369 * Remove an element to the given set.
370 * After the element has been removed (in the sense of the
371 * request being transmitted to the set service), cont will be called.
372 * Calls to remove_element can be queued
374 * @param set set to remove element from
375 * @param element element to remove from the set
376 * @param cont continuation called after the element has been removed
377 * @param cont_cls closure for @a cont
378 * @return #GNUNET_OK on success, #GNUNET_SYSERR if the
379 * set is invalid (e.g. the set service crashed)
382 GNUNET_SET_remove_element (struct GNUNET_SET_Handle *set,
383 const struct GNUNET_SET_Element *element,
384 GNUNET_SET_Continuation cont,
389 GNUNET_SET_copy_lazy (struct GNUNET_SET_Handle *set,
390 GNUNET_SET_CopyReadyCallback cb,
395 * Destroy the set handle, and free all associated resources.
396 * Iterations must have completed (or be explicitly canceled)
397 * before destroying the corresponding set. Operations may
398 * still be pending when a set is destroyed.
400 * @param set set to destroy
403 GNUNET_SET_destroy (struct GNUNET_SET_Handle *set);
407 * Prepare a set operation to be evaluated with another peer.
408 * The evaluation will not start until the client provides
409 * a local set with GNUNET_SET_commit().
411 * @param other_peer peer with the other set
412 * @param app_id hash for the application using the set
413 * @param context_msg additional information for the request
414 * @param result_mode specified how results will be returned,
415 * see `enum GNUNET_SET_ResultMode`.
416 * @param result_cb called on error or success
417 * @param result_cls closure for @a result_cb
418 * @return a handle to cancel the operation
420 struct GNUNET_SET_OperationHandle *
421 GNUNET_SET_prepare (const struct GNUNET_PeerIdentity *other_peer,
422 const struct GNUNET_HashCode *app_id,
423 const struct GNUNET_MessageHeader *context_msg,
424 enum GNUNET_SET_ResultMode result_mode,
425 struct GNUNET_SET_Option options[],
426 GNUNET_SET_ResultIterator result_cb,
431 * Wait for set operation requests for the given application ID.
432 * If the connection to the set service is lost, the listener is
433 * re-created transparently with exponential backoff.
435 * @param cfg configuration to use for connecting to
437 * @param operation operation we want to listen for
438 * @param app_id id of the application that handles set operation requests
439 * @param listen_cb called for each incoming request matching the operation
441 * @param listen_cls handle for @a listen_cb
442 * @return a handle that can be used to cancel the listen operation
444 struct GNUNET_SET_ListenHandle *
445 GNUNET_SET_listen (const struct GNUNET_CONFIGURATION_Handle *cfg,
446 enum GNUNET_SET_OperationType op_type,
447 const struct GNUNET_HashCode *app_id,
448 GNUNET_SET_ListenCallback listen_cb,
453 * Cancel the given listen operation. After calling cancel, the
454 * listen callback for this listen handle will not be called again.
455 * Note that cancelling a listen operation will automatically reject
456 * all operations that have not yet been accepted.
458 * @param lh handle for the listen operation
461 GNUNET_SET_listen_cancel (struct GNUNET_SET_ListenHandle *lh);
465 * Accept a request we got via GNUNET_SET_listen(). Must be called during
466 * GNUNET_SET_listen(), as the `struct GNUNET_SET_Request` becomes invalid
468 * Call GNUNET_SET_commit() to provide the local set to use for the operation,
469 * and to begin the exchange with the remote peer.
471 * @param request request to accept
472 * @param result_mode specified how results will be returned,
473 * see `enum GNUNET_SET_ResultMode`.
474 * @param result_cb callback for the results
475 * @param result_cls closure for @a result_cb
476 * @return a handle to cancel the operation
478 struct GNUNET_SET_OperationHandle *
479 GNUNET_SET_accept (struct GNUNET_SET_Request *request,
480 enum GNUNET_SET_ResultMode result_mode,
481 struct GNUNET_SET_Option options[],
482 GNUNET_SET_ResultIterator result_cb,
487 * Commit a set to be used with a set operation.
488 * This function is called once we have fully constructed
489 * the set that we want to use for the operation. At this
490 * time, the P2P protocol can then begin to exchange the
491 * set information and call the result callback with the
492 * result information.
494 * @param oh handle to the set operation
495 * @param set the set to use for the operation
496 * @return #GNUNET_OK on success, #GNUNET_SYSERR if the
497 * set is invalid (e.g. the set service crashed)
500 GNUNET_SET_commit (struct GNUNET_SET_OperationHandle *oh,
501 struct GNUNET_SET_Handle *set);
505 * Cancel the given set operation. May not be called after the
506 * operation's `GNUNET_SET_ResultIterator` has been called with a
507 * status that indicates error, timeout or done.
509 * @param oh set operation to cancel
512 GNUNET_SET_operation_cancel (struct GNUNET_SET_OperationHandle *oh);
516 * Iterate over all elements in the given set.
517 * Note that this operation involves transferring every element of the set
518 * from the service to the client, and is thus costly.
519 * Only one iteration per set may be active at the same time.
521 * @param set the set to iterate over
522 * @param iter the iterator to call for each element
523 * @param iter_cls closure for @a iter
524 * @return #GNUNET_YES if the iteration started successfuly,
525 * #GNUNET_NO if another iteration was still active,
526 * #GNUNET_SYSERR if the set is invalid (e.g. the server crashed, disconnected)
529 GNUNET_SET_iterate (struct GNUNET_SET_Handle *set,
530 GNUNET_SET_ElementIterator iter,
535 * Stop iteration over all elements in the given set. Can only
536 * be called before the iteration has "naturally" completed its
539 * @param set the set to stop iterating over
542 GNUNET_SET_iterate_cancel (struct GNUNET_SET_Handle *set);
546 * Create a copy of an element. The copy
547 * must be GNUNET_free-d by the caller.
549 * @param element the element to copy
550 * @return the copied element
552 struct GNUNET_SET_Element *
553 GNUNET_SET_element_dup (const struct GNUNET_SET_Element *element);
557 * Hash a set element.
559 * @param element the element that should be hashed
560 * @param ret_hash a pointer to where the hash of @a element
564 GNUNET_SET_element_hash (const struct GNUNET_SET_Element *element,
565 struct GNUNET_HashCode *ret_hash);
568 #if 0 /* keep Emacsens' auto-indent happy */
577 /** @} */ /* end of group */