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22 * @author Florian Dold
23 * @file include/gnunet_mq_lib.h
24 * @brief general purpose message queue
25 * @defgroup mq general purpose message queue
33 * Allocate an envelope, with extra space allocated after the space needed
34 * by the message struct.
35 * The allocated message will already have the type and size field set.
37 * @param mvar variable to store the allocated message in;
38 * must have a header field
39 * @param esize extra space to allocate after the message
40 * @param type type of the message
41 * @return the MQ message
43 #define GNUNET_MQ_msg_extra(mvar, esize, type) GNUNET_MQ_msg_(((struct GNUNET_MessageHeader**) &(mvar)), (esize) + sizeof *(mvar), (type))
46 * Allocate a GNUNET_MQ_Envelope.
47 * The contained message will already have the type and size field set.
49 * @param mvar variable to store the allocated message in;
50 * must have a header field
51 * @param type type of the message
52 * @return the allocated envelope
54 #define GNUNET_MQ_msg(mvar, type) GNUNET_MQ_msg_extra(mvar, 0, type)
58 * Allocate a GNUNET_MQ_Envelope, where the message only consists of a header.
59 * The allocated message will already have the type and size field set.
61 * @param type type of the message
63 #define GNUNET_MQ_msg_header(type) GNUNET_MQ_msg_ (NULL, sizeof (struct GNUNET_MessageHeader), type)
67 * Allocate a GNUNET_MQ_Envelope, where the message only consists of a header and extra space.
68 * The allocated message will already have the type and size field set.
70 * @param mh pointer that will changed to point at to the allocated message header
71 * @param esize extra space to allocate after the message header
72 * @param type type of the message
74 #define GNUNET_MQ_msg_header_extra(mh, esize, type) GNUNET_MQ_msg_ (&mh, (esize) + sizeof (struct GNUNET_MessageHeader), type)
78 * Allocate a GNUNET_MQ_Envelope, and append a payload message after the given
81 * @param mvar pointer to a message struct, will be changed to point at the newly allocated message,
82 * whose size is 'sizeof(*mvar) + ntohs (mh->size)'
83 * @param type message type of the allocated message, has no effect on the nested message
84 * @param mh message to nest
85 * @return a newly allocated 'struct GNUNET_MQ_Envelope *'
87 #define GNUNET_MQ_msg_nested_mh(mvar, type, mh) GNUNET_MQ_msg_nested_mh_((((void)(mvar)->header), (struct GNUNET_MessageHeader**) &(mvar)), sizeof (*(mvar)), (type), mh)
91 * Return a pointer to the message at the end of the given message.
93 * @param var pointer to a message struct, the type of the expression determines the base size,
94 * the space after the base size is the nested message
95 * @return a 'struct GNUNET_MessageHeader *' that points at the nested message of the given message,
96 * or NULL if the given message in @a var does not have any space after the message struct
98 #define GNUNET_MQ_extract_nested_mh(var) GNUNET_MQ_extract_nested_mh_ ((struct GNUNET_MessageHeader *) (var), sizeof (*(var)))
102 * Implementation of the GNUNET_MQ_extract_nexted_mh macro.
104 * @param mh message header to extract nested message header from
105 * @param base_size size of the message before the nested message's header appears
106 * @return pointer to the nested message, does not copy the message
108 const struct GNUNET_MessageHeader *
109 GNUNET_MQ_extract_nested_mh_ (const struct GNUNET_MessageHeader *mh,
114 * Implementation of the GNUNET_MQ_msg_nested_mh macro.
116 * @param mhp pointer to the message header pointer that will be changed to allocate at
117 * the newly allocated space for the message.
118 * @param base_size size of the data before the nested message
119 * @param type type of the message in the envelope
120 * @param nested_mh the message to append to the message after base_size
122 struct GNUNET_MQ_Envelope *
123 GNUNET_MQ_msg_nested_mh_ (struct GNUNET_MessageHeader **mhp,
126 const struct GNUNET_MessageHeader *nested_mh);
131 * End-marker for the handlers array
133 #define GNUNET_MQ_HANDLERS_END {NULL, 0, 0}
137 * Opaque handle to a message queue.
139 struct GNUNET_MQ_Handle;
142 * Opaque handle to an envelope.
144 struct GNUNET_MQ_Envelope;
148 * Error codes for the queue.
155 GNUNET_MQ_ERROR_READ = 1,
160 GNUNET_MQ_ERROR_WRITE = 2,
165 GNUNET_MQ_ERROR_TIMEOUT = 4
170 * Called when a message has been received.
173 * @param msg the received message
176 (*GNUNET_MQ_MessageCallback) (void *cls,
177 const struct GNUNET_MessageHeader *msg);
181 * Signature of functions implementing the
182 * sending functionality of a message queue.
184 * @param mq the message queue
185 * @param msg the message to send
186 * @param impl_state state of the implementation
189 (*GNUNET_MQ_SendImpl) (struct GNUNET_MQ_Handle *mq,
190 const struct GNUNET_MessageHeader *msg,
195 * Signature of functions implementing the
196 * destruction of a message queue.
197 * Implementations must not free @a mq, but should
198 * take care of @a impl_state.
200 * @param mq the message queue to destroy
201 * @param impl_state state of the implementation
204 (*GNUNET_MQ_DestroyImpl) (struct GNUNET_MQ_Handle *mq,
209 * Implementation function that cancels the currently sent message.
211 * @param mq message queue
212 * @param impl_state state specific to the implementation
215 (*GNUNET_MQ_CancelImpl) (struct GNUNET_MQ_Handle *mq,
220 * Callback used for notifications
225 (*GNUNET_MQ_NotifyCallback) (void *cls);
229 * Generic error handler, called with the appropriate
230 * error code and the same closure specified at the creation of
232 * Not every message queue implementation supports an error handler.
234 * @param cls closure, same closure as for the message handlers
235 * @param error error code
238 (*GNUNET_MQ_ErrorHandler) (void *cls,
239 enum GNUNET_MQ_Error error);
243 * Message handler for a specific message type.
245 struct GNUNET_MQ_MessageHandler
248 * Callback, called every time a new message of
249 * the specified type has been receied.
251 GNUNET_MQ_MessageCallback cb;
254 * Type of the message this handler covers.
259 * Expected size of messages of this type. Use 0 for
260 * variable-size. If non-zero, messages of the given
261 * type will be discarded (and the connection closed)
262 * if they do not have the right size.
264 uint16_t expected_size;
270 * Create a new envelope.
272 * @param mhp message header to store the allocated message header in, can be NULL
273 * @param size size of the message to allocate
274 * @param type type of the message, will be set in the allocated message
275 * @return the allocated MQ message
277 struct GNUNET_MQ_Envelope *
278 GNUNET_MQ_msg_ (struct GNUNET_MessageHeader **mhp,
284 * Discard the message queue message, free all
285 * allocated resources. Must be called in the event
286 * that a message is created but should not actually be sent.
288 * @param mqm the message to discard
291 GNUNET_MQ_discard (struct GNUNET_MQ_Envelope *mqm);
295 * Send a message with the give message queue.
296 * May only be called once per message.
298 * @param mq message queue
299 * @param ev the envelope with the message to send.
302 GNUNET_MQ_send (struct GNUNET_MQ_Handle *mq,
303 struct GNUNET_MQ_Envelope *ev);
307 * Cancel sending the message. Message must have been sent with
308 * #GNUNET_MQ_send before. May not be called after the notify sent
309 * callback has been called
311 * @param ev queued envelope to cancel
314 GNUNET_MQ_send_cancel (struct GNUNET_MQ_Envelope *ev);
318 * Associate the assoc_data in mq with a unique request id.
320 * @param mq message queue, id will be unique for the queue
321 * @param assoc_data to associate
324 GNUNET_MQ_assoc_add (struct GNUNET_MQ_Handle *mq, void *assoc_data);
328 * Get the data associated with a request id in a queue
330 * @param mq the message queue with the association
331 * @param request_id the request id we are interested in
332 * @return the associated data
335 GNUNET_MQ_assoc_get (struct GNUNET_MQ_Handle *mq,
336 uint32_t request_id);
340 * Remove the association for a request id
342 * @param mq the message queue with the association
343 * @param request_id the request id we want to remove
344 * @return the associated data
347 GNUNET_MQ_assoc_remove (struct GNUNET_MQ_Handle *mq,
348 uint32_t request_id);
352 * Create a message queue for a GNUNET_CLIENT_Connection.
353 * If handlers are specfied, receive messages from the connection.
355 * @param connection the client connection
356 * @param handlers handlers for receiving messages
357 * @param error_handler error handler
358 * @param cls closure for the handlers
359 * @return the message queue
361 struct GNUNET_MQ_Handle *
362 GNUNET_MQ_queue_for_connection_client (struct GNUNET_CLIENT_Connection *connection,
363 const struct GNUNET_MQ_MessageHandler *handlers,
364 GNUNET_MQ_ErrorHandler error_handler,
369 * Create a message queue for a GNUNET_SERVER_Client.
371 * @param client the client
372 * @return the message queue
374 struct GNUNET_MQ_Handle *
375 GNUNET_MQ_queue_for_server_client (struct GNUNET_SERVER_Client *client);
379 * Create a message queue for the specified handlers.
381 * @param send function the implements sending messages
382 * @param destroy function that implements destroying the queue
383 * @param cancel function that implements canceling a message
384 * @param impl_state for the queue, passed to @a send, @a destroy and @a cancel
385 * @param handlers array of message handlers
386 * @param error_handler handler for read and write errors
387 * @param cls closure for message handlers and error handler
388 * @return a new message queue
390 struct GNUNET_MQ_Handle *
391 GNUNET_MQ_queue_for_callbacks (GNUNET_MQ_SendImpl send,
392 GNUNET_MQ_DestroyImpl destroy,
393 GNUNET_MQ_CancelImpl cancel,
395 const struct GNUNET_MQ_MessageHandler *handlers,
396 GNUNET_MQ_ErrorHandler error_handler,
401 * Replace the handlers of a message queue with new handlers. Takes
402 * effect immediately, even for messages that already have been
403 * received, but for with the handler has not been called.
405 * If the message queue does not support receiving messages,
406 * this function has no effect.
408 * @param mq message queue
409 * @param new_handlers new handlers
410 * @param cls new closure for the handlers
413 GNUNET_MQ_replace_handlers (struct GNUNET_MQ_Handle *mq,
414 const struct GNUNET_MQ_MessageHandler *new_handlers,
419 * Call a callback once the envelope has been sent, that is,
420 * sending it can not be canceled anymore.
421 * There can be only one notify sent callback per envelope.
423 * @param ev message to call the notify callback for
424 * @param cb the notify callback
425 * @param cls closure for the callback
428 GNUNET_MQ_notify_sent (struct GNUNET_MQ_Envelope *ev,
429 GNUNET_MQ_NotifyCallback cb,
434 * Destroy the message queue.
436 * @param mq message queue to destroy
439 GNUNET_MQ_destroy (struct GNUNET_MQ_Handle *mq);
443 * Call the message message handler that was registered
444 * for the type of the given message in the given message queue.
446 * This function is indended to be used for the implementation
449 * @param mq message queue with the handlers
450 * @param mh message to dispatch
453 GNUNET_MQ_inject_message (struct GNUNET_MQ_Handle *mq,
454 const struct GNUNET_MessageHeader *mh);
458 * Call the error handler of a message queue with the given
459 * error code. If there is no error handler, log a warning.
461 * This function is intended to be used for the implementation
464 * @param mq message queue
465 * @param error the error type
468 GNUNET_MQ_inject_error (struct GNUNET_MQ_Handle *mq,
469 enum GNUNET_MQ_Error error);
473 * Call the send implementation for the next queued message,
475 * Only useful for implementing message queues,
476 * results in undefined behavior if not used carefully.
478 * @param mq message queue to send the next message with
481 GNUNET_MQ_impl_send_continue (struct GNUNET_MQ_Handle *mq);
485 * Get the message that should currently be sent.
486 * The returned message is only valid until #GNUNET_MQ_impl_send_continue
488 * Fails if there is no current message.
489 * Only useful for implementing message queues,
490 * results in undefined behavior if not used carefully.
492 * @param mq message queue with the current message, only valid
493 * until #GNUNET_MQ_impl_send_continue is called
494 * @return message to send, never NULL
496 const struct GNUNET_MessageHeader *
497 GNUNET_MQ_impl_current (struct GNUNET_MQ_Handle *mq);
501 * Get the implementation state associated with the
504 * While the GNUNET_MQ_Impl* callbacks receive the
505 * implementation state, continuations that are scheduled
506 * by the implementation function often only have one closure
507 * argument, with this function it is possible to get at the
508 * implementation state when only passing the GNUNET_MQ_Handle
511 * @param mq message queue with the current message
512 * @return message to send, never NULL
515 GNUNET_MQ_impl_state (struct GNUNET_MQ_Handle *mq);
518 /** @} */ /* end of group mq */