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3 Copyright (C) 2012-2016 GNUnet e.V.
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18 SPDX-License-Identifier: AGPL3.0-or-later
22 * @author Florian Dold
23 * @author Christian Grothoff
26 * General-purpose message queue
28 * @defgroup mq MQ library
29 * General-purpose message queue
31 * @see [Documentation](https://gnunet.org/message-queue-api)
35 #ifndef GNUNET_MQ_LIB_H
36 #define GNUNET_MQ_LIB_H
38 #include "gnunet_scheduler_lib.h"
41 * Allocate an envelope, with extra space allocated after the space needed
42 * by the message struct.
43 * The allocated message will already have the type and size field set.
45 * @param mvar variable to store the allocated message in;
46 * must have a header field;
48 * @param esize extra space to allocate after the message
49 * @param type type of the message
50 * @return the MQ message
52 #define GNUNET_MQ_msg_extra(mvar, esize, type) \
53 GNUNET_MQ_msg_(((struct GNUNET_MessageHeader **)&(mvar)), \
54 (esize) + sizeof *(mvar), \
58 * Allocate a GNUNET_MQ_Envelope.
59 * The contained message will already have the type and size field set.
61 * @param mvar variable to store the allocated message in;
62 * must have a header field;
64 * @param type type of the message
65 * @return the allocated envelope
67 #define GNUNET_MQ_msg(mvar, type) GNUNET_MQ_msg_extra(mvar, 0, type)
71 * Allocate a GNUNET_MQ_Envelope, where the message only consists of a header.
72 * The allocated message will already have the type and size field set.
74 * @param type type of the message
76 #define GNUNET_MQ_msg_header(type) \
77 GNUNET_MQ_msg_(NULL, sizeof(struct GNUNET_MessageHeader), type)
81 * Allocate a GNUNET_MQ_Envelope, where the message only consists of a header and extra space.
82 * The allocated message will already have the type and size field set.
84 * @param mh pointer that will changed to point at to the allocated message header
85 * @param esize extra space to allocate after the message header
86 * @param type type of the message
88 #define GNUNET_MQ_msg_header_extra(mh, esize, type) \
89 GNUNET_MQ_msg_(&mh, (esize) + sizeof(struct GNUNET_MessageHeader), type)
93 * Allocate a GNUNET_MQ_Envelope, and append a payload message after the given
96 * @param mvar pointer to a message struct, will be changed to point at the newly allocated message,
97 * whose size is 'sizeof(*mvar) + ntohs (mh->size)'
98 * @param type message type of the allocated message, has no effect on the nested message
99 * @param mh message to nest
100 * @return a newly allocated 'struct GNUNET_MQ_Envelope *'
102 #define GNUNET_MQ_msg_nested_mh(mvar, type, mh) \
104 struct GNUNET_MQ_Envelope *_ev; \
105 _ev = GNUNET_MQ_msg_nested_mh_((struct GNUNET_MessageHeader **)&(mvar), \
109 (void)(mvar)->header; /* type check */ \
115 * Return a pointer to the message at the end of the given message.
117 * @param var pointer to a message struct, the type of the expression determines the base size,
118 * the space after the base size is the nested message
119 * @return a 'struct GNUNET_MessageHeader *' that points at the nested message of the given message,
120 * or NULL if the given message in @a var does not have any space after the message struct
122 #define GNUNET_MQ_extract_nested_mh(var) \
123 GNUNET_MQ_extract_nested_mh_((struct GNUNET_MessageHeader *)(var), \
128 * Implementation of the #GNUNET_MQ_extract_nexted_mh macro.
130 * @param mh message header to extract nested message header from
131 * @param base_size size of the message before the nested message's header appears
132 * @return pointer to the nested message, does not copy the message
133 * OR NULL in case of a malformed message.
135 const struct GNUNET_MessageHeader *
136 GNUNET_MQ_extract_nested_mh_(const struct GNUNET_MessageHeader *mh,
141 * Opaque handle to an envelope.
143 struct GNUNET_MQ_Envelope;
147 * Obtain message contained in envelope.
149 * @param env the envelope
150 * @return message contained in the envelope
152 const struct GNUNET_MessageHeader *
153 GNUNET_MQ_env_get_msg(const struct GNUNET_MQ_Envelope *env);
157 * Return next envelope in queue.
159 * @param env a queued envelope
160 * @return next one, or NULL
162 const struct GNUNET_MQ_Envelope *
163 GNUNET_MQ_env_next(const struct GNUNET_MQ_Envelope *env);
167 * Implementation of the #GNUNET_MQ_msg_nested_mh macro.
169 * @param mhp pointer to the message header pointer that will be changed to allocate at
170 * the newly allocated space for the message.
171 * @param base_size size of the data before the nested message
172 * @param type type of the message in the envelope
173 * @param nested_mh the message to append to the message after base_size
175 struct GNUNET_MQ_Envelope *
176 GNUNET_MQ_msg_nested_mh_(struct GNUNET_MessageHeader **mhp,
179 const struct GNUNET_MessageHeader *nested_mh);
183 * Opaque handle to a message queue.
185 struct GNUNET_MQ_Handle;
189 * Error codes for the queue.
191 enum GNUNET_MQ_Error {
193 * Failed to read message from the network.
194 * FIXME: Likely not properly distinguished
195 * from TIMEOUT case in the code!
197 GNUNET_MQ_ERROR_READ = 1,
202 GNUNET_MQ_ERROR_WRITE = 2,
207 GNUNET_MQ_ERROR_TIMEOUT = 4,
210 * We received a message that was malformed and thus
211 * could not be passed to its handler.
213 GNUNET_MQ_ERROR_MALFORMED = 8,
216 * We received a message for which we have no matching
219 GNUNET_MQ_ERROR_NO_MATCH = 16
224 * Per envelope preferences and priorities.
226 enum GNUNET_MQ_PriorityPreferences {
228 * Lowest priority, i.e. background traffic (i.e. NSE, FS).
229 * This is the default!
231 GNUNET_MQ_PRIO_BACKGROUND = 0,
234 * Best-effort traffic (i.e. CADET relay, DHT)
236 GNUNET_MQ_PRIO_BEST_EFFORT = 1,
239 * Urgent traffic (local peer, i.e. Conversation).
241 GNUNET_MQ_PRIO_URGENT = 2,
244 * Highest priority, control traffic (i.e. CORE/CADET KX).
246 GNUNET_MQ_PRIO_CRITICAL_CONTROL = 3,
249 * Bit mask to apply to extract the priority bits.
251 GNUNET_MQ_PRIORITY_MASK = 3,
254 * Flag to indicate that unreliable delivery is acceptable. This
255 * means TRANSPORT will not attempt to receive an
256 * acknowledgment. CORE will just pass this flag through. CADET
257 * will use unreliable delivery if this flag is set.
259 * Note that even without this flag, messages may be lost by
260 * TRANSPORT and CORE.
262 * Thus, how "strong" the semantics of reliable delivery are depends
265 GNUNET_MQ_PREF_UNRELIABLE = 16,
268 * Flag to indicate that low latency is important. This flag must
269 * generally not be used in combination with
270 * #GNUNET_MQ_PREF_CORKING_ALLOWED as it would be a contradiction.
271 * When this flags is set, the envelope may skip forward in the
272 * queue (depending on priority) and also TRANSPORT should attempt
273 * to pick a communicator with particularly low latency.
275 GNUNET_MQ_PREF_LOW_LATENCY = 32,
278 * Flag to indicate that CORKing is acceptable. This allows the
279 * receiver to delay transmission in hope of combining this message
280 * with other messages into a larger transmission with less
281 * per-message overhead.
283 GNUNET_MQ_PREF_CORK_ALLOWED = 64,
286 * Flag to indicate that high bandwidth is desired. This flag
287 * indicates that the method chosen for transmission should focus on
288 * overall goodput. It rarely makes sense to combine this flag with
289 * #GNUNET_MQ_PREF_LOW_LATENCY.
291 GNUNET_MQ_PREF_GOODPUT = 128,
294 * Flag to indicate that out-of-order delivery is OK.
296 GNUNET_MQ_PREF_OUT_OF_ORDER = 256,
301 * Called when a message has been received.
304 * @param msg the received message
306 typedef void (*GNUNET_MQ_MessageCallback) (
308 const struct GNUNET_MessageHeader *msg);
312 * Called when a message needs to be validated.
315 * @param msg the received message
316 * @return #GNUNET_OK if the message is well-formed,
317 * #GNUNET_SYSERR if not
319 typedef int (*GNUNET_MQ_MessageValidationCallback) (
321 const struct GNUNET_MessageHeader *msg);
325 * Signature of functions implementing the
326 * sending functionality of a message queue.
328 * @param mq the message queue
329 * @param msg the message to send
330 * @param impl_state state of the implementation
332 typedef void (*GNUNET_MQ_SendImpl) (struct GNUNET_MQ_Handle *mq,
333 const struct GNUNET_MessageHeader *msg,
338 * Signature of functions implementing the
339 * destruction of a message queue.
340 * Implementations must not free @a mq, but should
341 * take care of @a impl_state.
343 * @param mq the message queue to destroy
344 * @param impl_state state of the implementation
346 typedef void (*GNUNET_MQ_DestroyImpl) (struct GNUNET_MQ_Handle *mq,
351 * Implementation function that cancels the currently sent message.
353 * @param mq message queue
354 * @param impl_state state specific to the implementation
356 typedef void (*GNUNET_MQ_CancelImpl) (struct GNUNET_MQ_Handle *mq,
361 * Generic error handler, called with the appropriate
362 * error code and the same closure specified at the creation of
364 * Not every message queue implementation supports an error handler.
367 * @param error error code
369 typedef void (*GNUNET_MQ_ErrorHandler) (void *cls, enum GNUNET_MQ_Error error);
373 * Insert @a env into the envelope DLL starting at @a env_head
374 * Note that @a env must not be in any MQ while this function
375 * is used with DLLs defined outside of the MQ module. This
376 * is just in case some application needs to also manage a
377 * FIFO of envelopes independent of MQ itself and wants to
378 * re-use the pointers internal to @a env. Use with caution.
380 * @param[in|out] env_head of envelope DLL
381 * @param[in|out] env_tail tail of envelope DLL
382 * @param[in|out] env element to insert at the tail
385 GNUNET_MQ_dll_insert_head(struct GNUNET_MQ_Envelope **env_head,
386 struct GNUNET_MQ_Envelope **env_tail,
387 struct GNUNET_MQ_Envelope *env);
391 * Insert @a env into the envelope DLL starting at @a env_head
392 * Note that @a env must not be in any MQ while this function
393 * is used with DLLs defined outside of the MQ module. This
394 * is just in case some application needs to also manage a
395 * FIFO of envelopes independent of MQ itself and wants to
396 * re-use the pointers internal to @a env. Use with caution.
398 * @param[in|out] env_head of envelope DLL
399 * @param[in|out] env_tail tail of envelope DLL
400 * @param[in|out] env element to insert at the tail
403 GNUNET_MQ_dll_insert_tail(struct GNUNET_MQ_Envelope **env_head,
404 struct GNUNET_MQ_Envelope **env_tail,
405 struct GNUNET_MQ_Envelope *env);
409 * Remove @a env from the envelope DLL starting at @a env_head.
410 * Note that @a env must not be in any MQ while this function
411 * is used with DLLs defined outside of the MQ module. This
412 * is just in case some application needs to also manage a
413 * FIFO of envelopes independent of MQ itself and wants to
414 * re-use the pointers internal to @a env. Use with caution.
416 * @param[in|out] env_head of envelope DLL
417 * @param[in|out] env_tail tail of envelope DLL
418 * @param[in|out] env element to remove from the DLL
421 GNUNET_MQ_dll_remove(struct GNUNET_MQ_Envelope **env_head,
422 struct GNUNET_MQ_Envelope **env_tail,
423 struct GNUNET_MQ_Envelope *env);
427 * Copy an array of handlers.
429 * Useful if the array has been delared in local memory and needs to be
430 * persisted for future use.
432 * @param handlers Array of handlers to be copied.
433 * @return A newly allocated array of handlers.
434 * Needs to be freed with #GNUNET_free.
436 struct GNUNET_MQ_MessageHandler *
437 GNUNET_MQ_copy_handlers(const struct GNUNET_MQ_MessageHandler *handlers);
441 * Copy an array of handlers, appending AGPL handler.
443 * Useful if the array has been delared in local memory and needs to be
444 * persisted for future use.
446 * @param handlers Array of handlers to be copied. Can be NULL (nothing done).
447 * @param agpl_handler function to call for AGPL handling
448 * @param agpl_cls closure for @a agpl_handler
449 * @return A newly allocated array of handlers.
450 * Needs to be freed with #GNUNET_free.
452 struct GNUNET_MQ_MessageHandler *
453 GNUNET_MQ_copy_handlers2(const struct GNUNET_MQ_MessageHandler *handlers,
454 GNUNET_MQ_MessageCallback agpl_handler,
459 * Count the handlers in a handler array.
461 * @param handlers Array of handlers to be counted.
462 * @return The number of handlers in the array.
465 GNUNET_MQ_count_handlers(const struct GNUNET_MQ_MessageHandler *handlers);
469 * Message handler for a specific message type.
471 struct GNUNET_MQ_MessageHandler {
473 * Callback to validate a message of the specified @e type.
474 * The closure given to @e mv will be this struct (not @e ctx).
475 * Using NULL means only size-validation using
476 * @e expected_size. In this case, @e expected_size must
479 GNUNET_MQ_MessageValidationCallback mv;
482 * Callback, called every time a new message of
483 * the specified @e type has been receied.
484 * The closure given to @e mv will be this struct (not @e ctx).
486 GNUNET_MQ_MessageCallback cb;
489 * Closure for @e mv and @e cb.
494 * Type of the message this handler covers, in host byte order.
499 * Expected size of messages of this type. Minimum size of the
500 * message if @e mv is non-NULL. Messages of the given type will be
501 * discarded (and the connection closed with an error reported to
502 * the application) if they do not have the right size.
504 uint16_t expected_size;
509 * End-marker for the handlers array
511 #define GNUNET_MQ_handler_end() \
513 NULL, NULL, NULL, 0, 0 \
518 * Defines a static function @a name which takes as a single argument
519 * a message handler for fixed-sized messages of type @a code and with
520 * a message type argument of @a str. Given such an argument, the
521 * function @name will return a `struct GNUNET_MQ_MessageHandler`
522 * for the given message type.
524 * The macro is to be used as follows:
526 * struct GNUNET_MessageTest { ... }; // must be fixed size
528 * handle_test_message (void *cls,
529 * const struct GNUNET_MessageTest *msg)
532 * struct GNUNET_MQ_MessageHandler handlers[] = {
533 * GNUNET_MQ_hd_fixed_size(test_message,
534 * GNUNET_MESSAGE_TYPE_TEST,
535 * struct GNUNET_MessageTest,
537 * GNUNET_MQ_handler_end()
540 * @param name unique basename for the functions
541 * @param code message type constant
542 * @param str type of the message (a struct)
543 * @param ctx context for the callbacks
545 #define GNUNET_MQ_hd_fixed_size(name, code, str, ctx) \
547 void (*_cb)(void *cls, const str *msg) = &handle_ ## name; \
548 ((struct GNUNET_MQ_MessageHandler){ NULL, \
549 (GNUNET_MQ_MessageCallback)_cb, \
557 * Defines a static function @a name which takes two arguments and a
558 * context-pointer for validating and handling variable-sized messages
559 * of type @a code and with a message type argument of @a str. Given
560 * such arguments, the function @name will return a `struct
561 * GNUNET_MQ_MessageHandler` for the given message type.
563 * The macro is to be used as follows:
565 * struct GNUNET_MessageTest { ... }; // can be variable size
567 * check_test (void *cls,
568 * const struct GNUNET_MessageTest *msg)
570 * const char *ctx = cls;
571 * GNUNET_assert (0 == strcmp ("context", ctx));
575 * handle_test (void *cls,
576 * const struct GNUNET_MessageTest *msg)
578 * const char *ctx = cls;
579 * GNUNET_assert (0 == strcmp ("context", ctx));
583 * struct GNUNET_MQ_MessageHandler handlers[] = {
584 * GNUNET_MQ_hd_var_size(test_message,
585 * GNUNET_MESSAGE_TYPE_TEST,
586 * struct GNUNET_MessageTest,
588 * GNUNET_MQ_handler_end()
591 * @param name unique basename for the functions
592 * @param code message type constant
593 * @param str type of the message (a struct)
594 * @param ctx context for the callbacks
596 #define GNUNET_MQ_hd_var_size(name, code, str, ctx) \
598 int (*_mv)(void *cls, const str *msg) = &check_ ## name; \
599 void (*_cb)(void *cls, const str *msg) = &handle_ ## name; \
600 ((struct GNUNET_MQ_MessageHandler){ (GNUNET_MQ_MessageValidationCallback) \
602 (GNUNET_MQ_MessageCallback)_cb, \
610 * Insert code for a "check_" function that verifies that
611 * a given variable-length message received over the network
612 * is followed by a 0-terminated string. If the message @a m
613 * is not followed by a 0-terminated string, an error is logged
614 * and the function is returned with #GNUNET_NO.
616 * @param an IPC message with proper type to determine
617 * the size, starting with a `struct GNUNET_MessageHeader`
619 #define GNUNET_MQ_check_zero_termination(m) \
621 const char *str = (const char *)&m[1]; \
622 const struct GNUNET_MessageHeader *hdr = \
623 (const struct GNUNET_MessageHeader *)m; \
624 uint16_t slen = ntohs(hdr->size) - sizeof(*m); \
625 if ((0 == slen) || (memchr(str, 0, slen) != &str[slen - 1])) \
634 * Insert code for a "check_" function that verifies that
635 * a given variable-length message received over the network
636 * is followed by another variable-length message that fits
637 * exactly with the given size. If the message @a m
638 * is not followed by another `struct GNUNET_MessageHeader`
639 * with a size that adds up to the total size, an error is logged
640 * and the function is returned with #GNUNET_NO.
642 * @param an IPC message with proper type to determine
643 * the size, starting with a `struct GNUNET_MessageHeader`
645 #define GNUNET_MQ_check_boxed_message(m) \
647 const struct GNUNET_MessageHeader *inbox = \
648 (const struct GNUNET_MessageHeader *)&m[1]; \
649 const struct GNUNET_MessageHeader *hdr = \
650 (const struct GNUNET_MessageHeader *)m; \
651 uint16_t slen = ntohs(hdr->size) - sizeof(*m); \
652 if ((slen < sizeof(struct GNUNET_MessageHeader)) || \
653 (slen != ntohs(inbox->size))) \
662 * Call the message message handler that was registered
663 * for the type of the given message in the given @a handlers list.
665 * This function is indended to be used for the implementation
668 * @param handlers a set of handlers
669 * @param mh message to dispatch
670 * @return #GNUNET_OK on success, #GNUNET_NO if no handler matched,
671 * #GNUNET_SYSERR if message was rejected by check function
674 GNUNET_MQ_handle_message(const struct GNUNET_MQ_MessageHandler *handlers,
675 const struct GNUNET_MessageHeader *mh);
679 * Create a new envelope.
681 * @param mhp message header to store the allocated message header in, can be NULL
682 * @param size size of the message to allocate
683 * @param type type of the message, will be set in the allocated message
684 * @return the allocated MQ message
686 struct GNUNET_MQ_Envelope *
687 GNUNET_MQ_msg_(struct GNUNET_MessageHeader **mhp,
693 * Create a new envelope by copying an existing message.
695 * @param hdr header of the message to copy
696 * @return envelope containing @a hdr
698 struct GNUNET_MQ_Envelope *
699 GNUNET_MQ_msg_copy(const struct GNUNET_MessageHeader *hdr);
703 * Discard the message queue message, free all
704 * allocated resources. Must be called in the event
705 * that a message is created but should not actually be sent.
707 * @param mqm the message to discard
710 GNUNET_MQ_discard(struct GNUNET_MQ_Envelope *mqm);
714 * Function to obtain the current envelope
715 * from within #GNUNET_MQ_SendImpl implementations.
717 * @param mq message queue to interrogate
718 * @return the current envelope
720 struct GNUNET_MQ_Envelope *
721 GNUNET_MQ_get_current_envelope(struct GNUNET_MQ_Handle *mq);
725 * Function to copy an envelope. The envelope must not yet
726 * be in any queue or have any options or callbacks set.
728 * @param env envelope to copy
729 * @return copy of @a env
731 struct GNUNET_MQ_Envelope *
732 GNUNET_MQ_env_copy(struct GNUNET_MQ_Envelope *env);
736 * Function to obtain the last envelope in the queue.
738 * @param mq message queue to interrogate
739 * @return the last envelope in the queue
741 struct GNUNET_MQ_Envelope *
742 GNUNET_MQ_get_last_envelope(struct GNUNET_MQ_Handle *mq);
746 * Set application-specific options for this envelope.
747 * Overrides the options set for the queue with
748 * #GNUNET_MQ_set_options() for this message only.
750 * @param env message to set options for
751 * @param pp priority and preferences to set for @a env
754 GNUNET_MQ_env_set_options(struct GNUNET_MQ_Envelope *env,
755 enum GNUNET_MQ_PriorityPreferences pp);
759 * Get performance preferences set for this envelope.
761 * @param env message to set options for
762 * @return priority and preferences to use
764 enum GNUNET_MQ_PriorityPreferences
765 GNUNET_MQ_env_get_options(struct GNUNET_MQ_Envelope *env);
769 * Combine performance preferences set for different
770 * envelopes that are being combined into one larger envelope.
772 * @param p1 one set of preferences
773 * @param p2 second set of preferences
774 * @return combined priority and preferences to use
776 enum GNUNET_MQ_PriorityPreferences
777 GNUNET_MQ_env_combine_options(enum GNUNET_MQ_PriorityPreferences p1,
778 enum GNUNET_MQ_PriorityPreferences p2);
782 * Remove the first envelope that has not yet been sent from the message
783 * queue and return it.
785 * @param mq queue to remove envelope from
786 * @return NULL if queue is empty (or has no envelope that is not under transmission)
788 struct GNUNET_MQ_Envelope *
789 GNUNET_MQ_unsent_head(struct GNUNET_MQ_Handle *mq);
793 * Set application-specific options for this queue.
795 * @param mq message queue to set options for
796 * @param pp priority and preferences to use by default
799 GNUNET_MQ_set_options(struct GNUNET_MQ_Handle *mq,
800 enum GNUNET_MQ_PriorityPreferences pp);
804 * Obtain the current length of the message queue.
806 * @param mq queue to inspect
807 * @return number of queued, non-transmitted messages
810 GNUNET_MQ_get_length(struct GNUNET_MQ_Handle *mq);
814 * Send a message with the given message queue.
815 * May only be called once per message.
817 * @param mq message queue
818 * @param ev the envelope with the message to send.
821 GNUNET_MQ_send(struct GNUNET_MQ_Handle *mq, struct GNUNET_MQ_Envelope *ev);
825 * Send a copy of a message with the given message queue.
826 * Can be called repeatedly on the same envelope.
828 * @param mq message queue
829 * @param ev the envelope with the message to send.
832 GNUNET_MQ_send_copy(struct GNUNET_MQ_Handle *mq,
833 const struct GNUNET_MQ_Envelope *ev);
837 * Cancel sending the message. Message must have been sent with
838 * #GNUNET_MQ_send before. May not be called after the notify sent
839 * callback has been called
841 * @param ev queued envelope to cancel
844 GNUNET_MQ_send_cancel(struct GNUNET_MQ_Envelope *ev);
848 * Associate the assoc_data in @a mq with a unique request id.
850 * @param mq message queue, id will be unique for the queue
851 * @param assoc_data to associate
854 GNUNET_MQ_assoc_add(struct GNUNET_MQ_Handle *mq, void *assoc_data);
858 * Get the data associated with a @a request_id in a queue
860 * @param mq the message queue with the association
861 * @param request_id the request id we are interested in
862 * @return the associated data
865 GNUNET_MQ_assoc_get(struct GNUNET_MQ_Handle *mq, uint32_t request_id);
869 * Remove the association for a @a request_id
871 * @param mq the message queue with the association
872 * @param request_id the request id we want to remove
873 * @return the associated data
876 GNUNET_MQ_assoc_remove(struct GNUNET_MQ_Handle *mq, uint32_t request_id);
880 * Create a message queue for the specified handlers.
882 * @param send function the implements sending messages
883 * @param destroy function that implements destroying the queue
884 * @param cancel function that implements canceling a message
885 * @param impl_state for the queue, passed to @a send, @a destroy and @a cancel
886 * @param handlers array of message handlers
887 * @param error_handler handler for read and write errors
888 * @param cls closure for message handlers and error handler
889 * @return a new message queue
891 struct GNUNET_MQ_Handle *
892 GNUNET_MQ_queue_for_callbacks(GNUNET_MQ_SendImpl send,
893 GNUNET_MQ_DestroyImpl destroy,
894 GNUNET_MQ_CancelImpl cancel,
896 const struct GNUNET_MQ_MessageHandler *handlers,
897 GNUNET_MQ_ErrorHandler error_handler,
902 * Change the closure argument in all of the `handlers` of the
905 * @param mq to modify
906 * @param handlers_cls new closure to use
909 GNUNET_MQ_set_handlers_closure(struct GNUNET_MQ_Handle *mq,
914 * Call a callback once the envelope has been sent, that is,
915 * sending it can not be canceled anymore.
916 * There can be only one notify sent callback per envelope.
918 * @param ev message to call the notify callback for
919 * @param cb the notify callback
920 * @param cb_cls closure for the callback
923 GNUNET_MQ_notify_sent(struct GNUNET_MQ_Envelope *ev,
924 GNUNET_SCHEDULER_TaskCallback cb,
929 * Destroy the message queue.
931 * @param mq message queue to destroy
934 GNUNET_MQ_destroy(struct GNUNET_MQ_Handle *mq);
938 * Handle we return for callbacks registered to be
939 * notified when #GNUNET_MQ_destroy() is called on a queue.
941 struct GNUNET_MQ_DestroyNotificationHandle;
945 * Register function to be called whenever @a mq is being
948 * @param mq message queue to watch
949 * @param cb function to call on @a mq destruction
950 * @param cb_cls closure for @a cb
951 * @return handle for #GNUNET_MQ_destroy_notify_cancel().
953 struct GNUNET_MQ_DestroyNotificationHandle *
954 GNUNET_MQ_destroy_notify(struct GNUNET_MQ_Handle *mq,
955 GNUNET_SCHEDULER_TaskCallback cb,
959 * Cancel registration from #GNUNET_MQ_destroy_notify().
961 * @param dnh handle for registration to cancel
964 GNUNET_MQ_destroy_notify_cancel(
965 struct GNUNET_MQ_DestroyNotificationHandle *dnh);
969 * Call the message message handler that was registered
970 * for the type of the given message in the given message queue.
972 * This function is indended to be used for the implementation
975 * @param mq message queue with the handlers
976 * @param mh message to dispatch
979 GNUNET_MQ_inject_message(struct GNUNET_MQ_Handle *mq,
980 const struct GNUNET_MessageHeader *mh);
984 * Call the error handler of a message queue with the given
985 * error code. If there is no error handler, log a warning.
987 * This function is intended to be used for the implementation
990 * @param mq message queue
991 * @param error the error type
994 GNUNET_MQ_inject_error(struct GNUNET_MQ_Handle *mq,
995 enum GNUNET_MQ_Error error);
999 * Call the send implementation for the next queued message, if any.
1000 * Calls the send notification for the current message unless
1001 * #GNUNET_MQ_impl_send_in_flight was called for this envelope.
1003 * Only useful for implementing message queues, results in undefined
1004 * behavior if not used carefully.
1006 * @param mq message queue to send the next message with
1009 GNUNET_MQ_impl_send_continue(struct GNUNET_MQ_Handle *mq);
1013 * Call the send notification for the current message, but do not
1014 * try to send the next message until #gnunet_mq_impl_send_continue
1017 * Only useful for implementing message queues, results in undefined
1018 * behavior if not used carefully.
1020 * @param mq message queue to send the next message with
1023 GNUNET_MQ_impl_send_in_flight(struct GNUNET_MQ_Handle *mq);
1027 * Get the implementation state associated with the
1030 * While the GNUNET_MQ_Impl* callbacks receive the
1031 * implementation state, continuations that are scheduled
1032 * by the implementation function often only have one closure
1033 * argument, with this function it is possible to get at the
1034 * implementation state when only passing the `struct GNUNET_MQ_Handle`
1037 * @param mq message queue with the current message
1038 * @return message to send, never NULL
1041 GNUNET_MQ_impl_state(struct GNUNET_MQ_Handle *mq);
1045 * Get the message that should currently be sent.
1046 * Fails if there is no current message.
1047 * Only useful for implementing message queues,
1048 * results in undefined behavior if not used carefully.
1050 * @param mq message queue with the current message
1051 * @return message to send, never NULL
1053 const struct GNUNET_MessageHeader *
1054 GNUNET_MQ_impl_current(struct GNUNET_MQ_Handle *mq);
1058 * Enum defining all known preference categories.
1060 * @deprecated will be replaced by `enum GNUNET_MQ_PriorityPreference`
1062 enum GNUNET_MQ_PreferenceKind {
1064 * No preference was expressed.
1066 GNUNET_MQ_PREFERENCE_NONE = 0,
1069 * The preferred transmission for this envelope focuses on
1070 * maximizing bandwidth.
1072 GNUNET_MQ_PREFERENCE_BANDWIDTH = 1,
1075 * The preferred transmission for this envelope foces on
1076 * minimizing latency.
1078 GNUNET_MQ_PREFERENCE_LATENCY = 2,
1081 * The preferred transmission for this envelope foces on
1084 GNUNET_MQ_PREFERENCE_RELIABILITY = 3
1087 * Number of preference values allowed.
1089 #define GNUNET_MQ_PREFERENCE_COUNT 4
1094 * Convert an `enum GNUNET_MQ_PreferenceType` to a string
1096 * @param type the preference type
1097 * @return a string or NULL if invalid
1099 * @deprecated will be replaced by `enum GNUNET_MQ_PriorityPreference`
1102 GNUNET_MQ_preference_to_string(enum GNUNET_MQ_PreferenceKind type);
1107 /** @} */ /* end of group mq */