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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
31 #include "gnunet_common.h"
35 * Allocate an envelope, with extra space allocated after the space needed
36 * by the message struct.
37 * The allocated message will already have the type and size field set.
39 * @param mvar variable to store the allocated message in;
40 * must have a header field
41 * @param esize extra space to allocate after the message
42 * @param type type of the message
43 * @return the MQ message
45 #define GNUNET_MQ_msg_extra(mvar, esize, type) GNUNET_MQ_msg_((((void)(mvar)->header), (struct GNUNET_MessageHeader**) &(mvar)), (esize) + sizeof *(mvar), (type))
48 * Allocate a GNUNET_MQ_Envelope.
49 * The contained message will already have the type and size field set.
51 * @param mvar variable to store the allocated message in;
52 * must have a header field
53 * @param type type of the message
54 * @return the allocated envelope
56 #define GNUNET_MQ_msg(mvar, type) GNUNET_MQ_msg_extra(mvar, 0, type)
60 * Allocate a GNUNET_MQ_Envelope, where the message only consists of a header.
61 * The allocated message will already have the type and size field set.
63 * @param type type of the message
65 #define GNUNET_MQ_msg_header(type) GNUNET_MQ_msg_ (NULL, sizeof (struct GNUNET_MessageHeader), type)
69 * Allocate a GNUNET_MQ_Envelope, where the message only consists of a header and extra space.
70 * The allocated message will already have the type and size field set.
72 * @param mh pointer that will changed to point at to the allocated message header
73 * @param esize extra space to allocate after the message header
74 * @param type type of the message
76 #define GNUNET_MQ_msg_header_extra(mh, esize, type) GNUNET_MQ_msg_ (&mh, (esize) + sizeof (struct GNUNET_MessageHeader), type)
80 * Allocate a GNUNET_MQ_Envelope, and append a payload message after the given
83 * @param mvar pointer to a message struct, will be changed to point at the newly allocated message,
84 * whose size is 'sizeof(*mvar) + ntohs (mh->size)'
85 * @param type message type of the allocated message, has no effect on the nested message
86 * @param mh message to nest
87 * @return a newly allocated 'struct GNUNET_MQ_Envelope *'
89 #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)
93 * Return a pointer to the message at the end of the given message.
95 * @param var pointer to a message struct, the type of the expression determines the base size,
96 * the space after the base size is the nested message
97 * @return a 'struct GNUNET_MessageHeader *' that points at the nested message of the given message,
98 * or NULL if the given message in @a var does not have any space after the message struct
100 #define GNUNET_MQ_extract_nested_mh(var) GNUNET_MQ_extract_nested_mh_ ((struct GNUNET_MessageHeader *) (var), sizeof (*(var)))
104 * Implementation of the GNUNET_MQ_extract_nexted_mh macro.
106 * @param mh message header to extract nested message header from
107 * @param base_size size of the message before the nested message's header appears
108 * @return pointer to the nested message, does not copy the message
110 struct GNUNET_MessageHeader *
111 GNUNET_MQ_extract_nested_mh_ (const struct GNUNET_MessageHeader *mh, uint16_t base_size);
115 * Implementation of the GNUNET_MQ_msg_nested_mh macro.
117 * @param mhp pointer to the message header pointer that will be changed to allocate at
118 * the newly allocated space for the message.
119 * @param base_size size of the data before the nested message
120 * @param type type of the message in the envelope
121 * @param nested_mh the message to append to the message after base_size
123 struct GNUNET_MQ_Envelope *
124 GNUNET_MQ_msg_nested_mh_ (struct GNUNET_MessageHeader **mhp, uint16_t base_size, uint16_t type,
125 const struct GNUNET_MessageHeader *nested_mh);
130 * End-marker for the handlers array
132 #define GNUNET_MQ_HANDLERS_END {NULL, 0, 0}
136 * Opaque handle to a message queue.
138 struct GNUNET_MQ_Handle;
141 * Opaque handle to an envelope.
143 struct GNUNET_MQ_Envelope;
147 * Error codes for the queue.
154 GNUNET_MQ_ERROR_READ = 1,
159 GNUNET_MQ_ERROR_WRITE = 2,
164 GNUNET_MQ_ERROR_TIMEOUT = 4
169 * Called when a message has been received.
172 * @param msg the received message
175 (*GNUNET_MQ_MessageCallback) (void *cls,
176 const struct GNUNET_MessageHeader *msg);
180 * Signature of functions implementing the
181 * sending functionality of a message queue.
183 * @param mq the message queue
184 * @param msg the message to send
185 * @param impl_state state of the implementation
188 (*GNUNET_MQ_SendImpl) (struct GNUNET_MQ_Handle *mq,
189 const struct GNUNET_MessageHeader *msg,
194 * Signature of functions implementing the
195 * destruction of a message queue.
196 * Implementations must not free @a mq, but should
197 * take care of @a impl_state.
199 * @param mq the message queue to destroy
200 * @param impl_state state of the implementation
203 (*GNUNET_MQ_DestroyImpl) (struct GNUNET_MQ_Handle *mq, void *impl_state);
207 * Implementation function that cancels the currently sent message.
209 * @param mq message queue
210 * @param impl_state state specific to the implementation
213 (*GNUNET_MQ_CancelImpl) (struct GNUNET_MQ_Handle *mq, void *impl_state);
217 * Callback used for notifications
222 (*GNUNET_MQ_NotifyCallback) (void *cls);
226 * Generic error handler, called with the appropriate
227 * error code and the same closure specified at the creation of
229 * Not every message queue implementation supports an error handler.
231 * @param cls closure, same closure as for the message handlers
232 * @param error error code
235 (*GNUNET_MQ_ErrorHandler) (void *cls, enum GNUNET_MQ_Error error);
239 * Message handler for a specific message type.
241 struct GNUNET_MQ_MessageHandler
244 * Callback, called every time a new message of
245 * the specified type has been receied.
247 GNUNET_MQ_MessageCallback cb;
251 * Type of the message this handler covers.
256 * Expected size of messages of this type. Use 0 for
257 * variable-size. If non-zero, messages of the given
258 * type will be discarded (and the connection closed)
259 * if they do not have the right size.
261 uint16_t expected_size;
267 * Create a new envelope.
269 * @param mhp message header to store the allocated message header in, can be NULL
270 * @param size size of the message to allocate
271 * @param type type of the message, will be set in the allocated message
272 * @return the allocated MQ message
274 struct GNUNET_MQ_Envelope *
275 GNUNET_MQ_msg_ (struct GNUNET_MessageHeader **mhp, uint16_t size, uint16_t type);
279 * Discard the message queue message, free all
280 * allocated resources. Must be called in the event
281 * that a message is created but should not actually be sent.
283 * @param mqm the message to discard
286 GNUNET_MQ_discard (struct GNUNET_MQ_Envelope *mqm);
290 * Send a message with the give message queue.
291 * May only be called once per message.
293 * @param mq message queue
294 * @param ev the envelope with the message to send.
297 GNUNET_MQ_send (struct GNUNET_MQ_Handle *mq,
298 struct GNUNET_MQ_Envelope *ev);
302 * Cancel sending the message. Message must have been sent with
303 * #GNUNET_MQ_send before. May not be called after the notify sent
304 * callback has been called
306 * @param ev queued envelope to cancel
309 GNUNET_MQ_send_cancel (struct GNUNET_MQ_Envelope *ev);
313 * Associate the assoc_data in mq with a unique request id.
315 * @param mq message queue, id will be unique for the queue
316 * @param assoc_data to associate
319 GNUNET_MQ_assoc_add (struct GNUNET_MQ_Handle *mq, void *assoc_data);
323 * Get the data associated with a request id in a queue
325 * @param mq the message queue with the association
326 * @param request_id the request id we are interested in
327 * @return the associated data
330 GNUNET_MQ_assoc_get (struct GNUNET_MQ_Handle *mq, uint32_t request_id);
334 * Remove the association for a request id
336 * @param mq the message queue with the association
337 * @param request_id the request id we want to remove
338 * @return the associated data
341 GNUNET_MQ_assoc_remove (struct GNUNET_MQ_Handle *mq, uint32_t request_id);
345 * Create a message queue for a GNUNET_CLIENT_Connection.
346 * If handlers are specfied, receive messages from the connection.
348 * @param connection the client connection
349 * @param handlers handlers for receiving messages
350 * @param error_handler error handler
351 * @param cls closure for the handlers
352 * @return the message queue
354 struct GNUNET_MQ_Handle *
355 GNUNET_MQ_queue_for_connection_client (struct GNUNET_CLIENT_Connection *connection,
356 const struct GNUNET_MQ_MessageHandler *handlers,
357 GNUNET_MQ_ErrorHandler error_handler,
362 * Create a message queue for a GNUNET_SERVER_Client.
364 * @param client the client
365 * @return the message queue
367 struct GNUNET_MQ_Handle *
368 GNUNET_MQ_queue_for_server_client (struct GNUNET_SERVER_Client *client);
372 * Create a message queue for the specified handlers.
374 * @param send function the implements sending messages
375 * @param destroy function that implements destroying the queue
376 * @param cancel function that implements canceling a message
377 * @param impl_state for the queue, passed to @a send, @a destroy and @a cancel
378 * @param handlers array of message handlers
379 * @param error_handler handler for read and write errors
380 * @param cls closure for message handlers and error handler
381 * @return a new message queue
383 struct GNUNET_MQ_Handle *
384 GNUNET_MQ_queue_for_callbacks (GNUNET_MQ_SendImpl send,
385 GNUNET_MQ_DestroyImpl destroy,
386 GNUNET_MQ_CancelImpl cancel,
388 const struct GNUNET_MQ_MessageHandler *handlers,
389 GNUNET_MQ_ErrorHandler error_handler,
395 * Replace the handlers of a message queue with new handlers.
396 * Takes effect immediately, even for messages that already have been received, but for
397 * with the handler has not been called.
399 * If the message queue does not support receiving messages,
400 * this function has no effect.
402 * @param mq message queue
403 * @param new_handlers new handlers
404 * @param cls new closure for the handlers
407 GNUNET_MQ_replace_handlers (struct GNUNET_MQ_Handle *mq,
408 const struct GNUNET_MQ_MessageHandler *new_handlers,
413 * Call a callback once the envelope has been sent, that is,
414 * sending it can not be canceled anymore.
415 * There can be only one notify sent callback per envelope.
417 * @param ev message to call the notify callback for
418 * @param cb the notify callback
419 * @param cls closure for the callback
422 GNUNET_MQ_notify_sent (struct GNUNET_MQ_Envelope *ev,
423 GNUNET_MQ_NotifyCallback cb,
428 * Destroy the message queue.
430 * @param mq message queue to destroy
433 GNUNET_MQ_destroy (struct GNUNET_MQ_Handle *mq);
437 * Call the message message handler that was registered
438 * for the type of the given message in the given message queue.
440 * This function is indended to be used for the implementation
443 * @param mq message queue with the handlers
444 * @param mh message to dispatch
447 GNUNET_MQ_inject_message (struct GNUNET_MQ_Handle *mq,
448 const struct GNUNET_MessageHeader *mh);
452 * Call the error handler of a message queue with the given
453 * error code. If there is no error handler, log a warning.
455 * This function is intended to be used for the implementation
458 * @param mq message queue
459 * @param error the error type
462 GNUNET_MQ_inject_error (struct GNUNET_MQ_Handle *mq,
463 enum GNUNET_MQ_Error error);
467 * Call the send implementation for the next queued message,
469 * Only useful for implementing message queues,
470 * results in undefined behavior if not used carefully.
472 * @param mq message queue to send the next message with
475 GNUNET_MQ_impl_send_continue (struct GNUNET_MQ_Handle *mq);
479 * Get the message that should currently be sent.
480 * Fails if there is no current message.
481 * Only useful for implementing message queues,
482 * results in undefined behavior if not used carefully.
484 * @param mq message queue with the current message
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 */