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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_((((void)(mvar)->header), (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 struct GNUNET_MessageHeader *
109 GNUNET_MQ_extract_nested_mh_ (const struct GNUNET_MessageHeader *mh, uint16_t base_size);
113 * Implementation of the GNUNET_MQ_msg_nested_mh macro.
115 * @param mhp pointer to the message header pointer that will be changed to allocate at
116 * the newly allocated space for the message.
117 * @param base_size size of the data before the nested message
118 * @param type type of the message in the envelope
119 * @param nested_mh the message to append to the message after base_size
121 struct GNUNET_MQ_Envelope *
122 GNUNET_MQ_msg_nested_mh_ (struct GNUNET_MessageHeader **mhp, uint16_t base_size, uint16_t type,
123 const struct GNUNET_MessageHeader *nested_mh);
128 * End-marker for the handlers array
130 #define GNUNET_MQ_HANDLERS_END {NULL, 0, 0}
134 * Opaque handle to a message queue.
136 struct GNUNET_MQ_Handle;
139 * Opaque handle to an envelope.
141 struct GNUNET_MQ_Envelope;
145 * Error codes for the queue.
152 GNUNET_MQ_ERROR_READ = 1,
157 GNUNET_MQ_ERROR_WRITE = 2,
162 GNUNET_MQ_ERROR_TIMEOUT = 4
167 * Called when a message has been received.
170 * @param msg the received message
173 (*GNUNET_MQ_MessageCallback) (void *cls,
174 const struct GNUNET_MessageHeader *msg);
178 * Signature of functions implementing the
179 * sending functionality of a message queue.
181 * @param mq the message queue
182 * @param msg the message to send
183 * @param impl_state state of the implementation
186 (*GNUNET_MQ_SendImpl) (struct GNUNET_MQ_Handle *mq,
187 const struct GNUNET_MessageHeader *msg,
192 * Signature of functions implementing the
193 * destruction of a message queue.
194 * Implementations must not free @a mq, but should
195 * take care of @a impl_state.
197 * @param mq the message queue to destroy
198 * @param impl_state state of the implementation
201 (*GNUNET_MQ_DestroyImpl) (struct GNUNET_MQ_Handle *mq, void *impl_state);
205 * Implementation function that cancels the currently sent message.
207 * @param mq message queue
208 * @param impl_state state specific to the implementation
211 (*GNUNET_MQ_CancelImpl) (struct GNUNET_MQ_Handle *mq, void *impl_state);
215 * Callback used for notifications
220 (*GNUNET_MQ_NotifyCallback) (void *cls);
224 * Generic error handler, called with the appropriate
225 * error code and the same closure specified at the creation of
227 * Not every message queue implementation supports an error handler.
229 * @param cls closure, same closure as for the message handlers
230 * @param error error code
233 (*GNUNET_MQ_ErrorHandler) (void *cls, enum GNUNET_MQ_Error error);
237 * Message handler for a specific message type.
239 struct GNUNET_MQ_MessageHandler
242 * Callback, called every time a new message of
243 * the specified type has been receied.
245 GNUNET_MQ_MessageCallback cb;
248 * Type of the message this handler covers.
253 * Expected size of messages of this type. Use 0 for
254 * variable-size. If non-zero, messages of the given
255 * type will be discarded (and the connection closed)
256 * if they do not have the right size.
258 uint16_t expected_size;
264 * Create a new envelope.
266 * @param mhp message header to store the allocated message header in, can be NULL
267 * @param size size of the message to allocate
268 * @param type type of the message, will be set in the allocated message
269 * @return the allocated MQ message
271 struct GNUNET_MQ_Envelope *
272 GNUNET_MQ_msg_ (struct GNUNET_MessageHeader **mhp, uint16_t size, uint16_t type);
276 * Discard the message queue message, free all
277 * allocated resources. Must be called in the event
278 * that a message is created but should not actually be sent.
280 * @param mqm the message to discard
283 GNUNET_MQ_discard (struct GNUNET_MQ_Envelope *mqm);
287 * Send a message with the give message queue.
288 * May only be called once per message.
290 * @param mq message queue
291 * @param ev the envelope with the message to send.
294 GNUNET_MQ_send (struct GNUNET_MQ_Handle *mq,
295 struct GNUNET_MQ_Envelope *ev);
299 * Cancel sending the message. Message must have been sent with
300 * #GNUNET_MQ_send before. May not be called after the notify sent
301 * callback has been called
303 * @param ev queued envelope to cancel
306 GNUNET_MQ_send_cancel (struct GNUNET_MQ_Envelope *ev);
310 * Associate the assoc_data in mq with a unique request id.
312 * @param mq message queue, id will be unique for the queue
313 * @param assoc_data to associate
316 GNUNET_MQ_assoc_add (struct GNUNET_MQ_Handle *mq, void *assoc_data);
320 * Get the data associated with a request id in a queue
322 * @param mq the message queue with the association
323 * @param request_id the request id we are interested in
324 * @return the associated data
327 GNUNET_MQ_assoc_get (struct GNUNET_MQ_Handle *mq, uint32_t request_id);
331 * Remove the association for a request id
333 * @param mq the message queue with the association
334 * @param request_id the request id we want to remove
335 * @return the associated data
338 GNUNET_MQ_assoc_remove (struct GNUNET_MQ_Handle *mq, uint32_t request_id);
342 * Create a message queue for a GNUNET_CLIENT_Connection.
343 * If handlers are specfied, receive messages from the connection.
345 * @param connection the client connection
346 * @param handlers handlers for receiving messages
347 * @param error_handler error handler
348 * @param cls closure for the handlers
349 * @return the message queue
351 struct GNUNET_MQ_Handle *
352 GNUNET_MQ_queue_for_connection_client (struct GNUNET_CLIENT_Connection *connection,
353 const struct GNUNET_MQ_MessageHandler *handlers,
354 GNUNET_MQ_ErrorHandler error_handler,
359 * Create a message queue for a GNUNET_SERVER_Client.
361 * @param client the client
362 * @return the message queue
364 struct GNUNET_MQ_Handle *
365 GNUNET_MQ_queue_for_server_client (struct GNUNET_SERVER_Client *client);
369 * Create a message queue for the specified handlers.
371 * @param send function the implements sending messages
372 * @param destroy function that implements destroying the queue
373 * @param cancel function that implements canceling a message
374 * @param impl_state for the queue, passed to @a send, @a destroy and @a cancel
375 * @param handlers array of message handlers
376 * @param error_handler handler for read and write errors
377 * @param cls closure for message handlers and error handler
378 * @return a new message queue
380 struct GNUNET_MQ_Handle *
381 GNUNET_MQ_queue_for_callbacks (GNUNET_MQ_SendImpl send,
382 GNUNET_MQ_DestroyImpl destroy,
383 GNUNET_MQ_CancelImpl cancel,
385 const struct GNUNET_MQ_MessageHandler *handlers,
386 GNUNET_MQ_ErrorHandler error_handler,
392 * Replace the handlers of a message queue with new handlers.
393 * Takes effect immediately, even for messages that already have been received, but for
394 * with the handler has not been called.
396 * If the message queue does not support receiving messages,
397 * this function has no effect.
399 * @param mq message queue
400 * @param new_handlers new handlers
401 * @param cls new closure for the handlers
404 GNUNET_MQ_replace_handlers (struct GNUNET_MQ_Handle *mq,
405 const struct GNUNET_MQ_MessageHandler *new_handlers,
410 * Call a callback once the envelope has been sent, that is,
411 * sending it can not be canceled anymore.
412 * There can be only one notify sent callback per envelope.
414 * @param ev message to call the notify callback for
415 * @param cb the notify callback
416 * @param cls closure for the callback
419 GNUNET_MQ_notify_sent (struct GNUNET_MQ_Envelope *ev,
420 GNUNET_MQ_NotifyCallback cb,
425 * Destroy the message queue.
427 * @param mq message queue to destroy
430 GNUNET_MQ_destroy (struct GNUNET_MQ_Handle *mq);
434 * Call the message message handler that was registered
435 * for the type of the given message in the given message queue.
437 * This function is indended to be used for the implementation
440 * @param mq message queue with the handlers
441 * @param mh message to dispatch
444 GNUNET_MQ_inject_message (struct GNUNET_MQ_Handle *mq,
445 const struct GNUNET_MessageHeader *mh);
449 * Call the error handler of a message queue with the given
450 * error code. If there is no error handler, log a warning.
452 * This function is intended to be used for the implementation
455 * @param mq message queue
456 * @param error the error type
459 GNUNET_MQ_inject_error (struct GNUNET_MQ_Handle *mq,
460 enum GNUNET_MQ_Error error);
464 * Call the send implementation for the next queued message,
466 * Only useful for implementing message queues,
467 * results in undefined behavior if not used carefully.
469 * @param mq message queue to send the next message with
472 GNUNET_MQ_impl_send_continue (struct GNUNET_MQ_Handle *mq);
476 * Get the message that should currently be sent.
477 * The returned message is only valid until #GNUNET_MQ_impl_send_continue
479 * Fails if there is no current message.
480 * Only useful for implementing message queues,
481 * results in undefined behavior if not used carefully.
483 * @param mq message queue with the current message, only valid
484 * until #GNUNET_MQ_impl_send_continue is called
485 * @return message to send, never NULL
487 const struct GNUNET_MessageHeader *
488 GNUNET_MQ_impl_current (struct GNUNET_MQ_Handle *mq);
492 * Get the implementation state associated with the
495 * While the GNUNET_MQ_Impl* callbacks receive the
496 * implementation state, continuations that are scheduled
497 * by the implementation function often only have one closure
498 * argument, with this function it is possible to get at the
499 * implementation state when only passing the GNUNET_MQ_Handle
502 * @param mq message queue with the current message
503 * @return message to send, never NULL
506 GNUNET_MQ_impl_state (struct GNUNET_MQ_Handle *mq);
510 * Mark the current message as irrevocably sent, but do not
511 * proceed with sending the next message.
512 * Will call the appropriate GNUNET_MQ_NotifyCallback, if any.
514 * @param mq message queue
517 GNUNET_MQ_impl_send_commit (struct GNUNET_MQ_Handle *mq);
519 /** @} */ /* end of group mq */