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3 (C) 2010 Christian Grothoff (and other contributing authors)
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22 * @file util/server_nc.c
23 * @brief convenience functions for transmission of
24 * a notification stream
25 * @author Christian Grothoff
29 #include "gnunet_util_lib.h"
31 #define LOG(kind,...) GNUNET_log_from (kind, "util-server-nc", __VA_ARGS__)
35 * Entry in list of messages pending to be transmitted.
37 struct PendingMessageList
41 * This is a doubly-linked list.
43 struct PendingMessageList *next;
46 * This is a doubly-linked list.
48 struct PendingMessageList *prev;
51 * Message to transmit (allocated at the end of this
52 * struct, do not free)
54 const struct GNUNET_MessageHeader *msg;
57 * Can this message be dropped?
65 * Lists of clients we manage for notifications.
71 * This is a doubly linked list.
73 struct ClientList *next;
76 * This is a doubly linked list.
78 struct ClientList *prev;
81 * Overall context this client belongs to.
83 struct GNUNET_SERVER_NotificationContext *nc;
86 * Handle to the client.
88 struct GNUNET_SERVER_Client *client;
91 * Handle for pending transmission request to the client (or NULL).
93 struct GNUNET_SERVER_TransmitHandle *th;
96 * Head of linked list of requests queued for transmission.
98 struct PendingMessageList *pending_head;
101 * Tail of linked list of requests queued for transmission.
103 struct PendingMessageList *pending_tail;
106 * Number of messages currently in the list.
108 unsigned int num_pending;
114 * The notification context is the key datastructure for a convenience
115 * API used for transmission of notifications to the client until the
116 * client disconnects (or the notification context is destroyed, in
117 * which case we disconnect these clients). Essentially, all
118 * (notification) messages are queued up until the client is able to
121 struct GNUNET_SERVER_NotificationContext
125 * Server we do notifications for.
127 struct GNUNET_SERVER_Handle *server;
130 * Head of list of clients receiving notifications.
132 struct ClientList *clients_head;
135 * Tail of list of clients receiving notifications.
137 struct ClientList *clients_tail;
140 * Maximum number of optional messages to queue per client.
142 unsigned int queue_length;
148 * Client has disconnected, clean up.
150 * @param cls our 'struct GNUNET_SERVER_NotificationContext *'
151 * @param client handle of client that disconnected
154 handle_client_disconnect (void *cls, struct GNUNET_SERVER_Client *client)
156 struct GNUNET_SERVER_NotificationContext *nc = cls;
157 struct ClientList *pos;
158 struct PendingMessageList *pml;
165 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
166 if (pos->client == client)
170 LOG (GNUNET_ERROR_TYPE_DEBUG,
171 "Client disconnected, cleaning up %u messages in NC queue\n",
173 GNUNET_CONTAINER_DLL_remove (nc->clients_head,
176 while (NULL != (pml = pos->pending_head))
178 GNUNET_CONTAINER_DLL_remove (pos->pending_head, pos->pending_tail, pml);
184 GNUNET_SERVER_notify_transmit_ready_cancel (pos->th);
187 GNUNET_SERVER_client_drop (client);
188 GNUNET_assert (0 == pos->num_pending);
194 * Create a new notification context.
196 * @param server server for which this function creates the context
197 * @param queue_length maximum number of messages to keep in
198 * the notification queue; optional messages are dropped
199 * if the queue gets longer than this number of messages
200 * @return handle to the notification context
202 struct GNUNET_SERVER_NotificationContext *
203 GNUNET_SERVER_notification_context_create (struct GNUNET_SERVER_Handle *server,
204 unsigned int queue_length)
206 struct GNUNET_SERVER_NotificationContext *ret;
208 ret = GNUNET_malloc (sizeof (struct GNUNET_SERVER_NotificationContext));
209 ret->server = server;
210 ret->queue_length = queue_length;
211 GNUNET_SERVER_disconnect_notify (server, &handle_client_disconnect, ret);
217 * Destroy the context, force disconnect for all clients.
219 * @param nc context to destroy.
222 GNUNET_SERVER_notification_context_destroy (struct
223 GNUNET_SERVER_NotificationContext
226 struct ClientList *pos;
227 struct PendingMessageList *pml;
229 while (NULL != (pos = nc->clients_head))
231 GNUNET_CONTAINER_DLL_remove (nc->clients_head,
236 GNUNET_SERVER_notify_transmit_ready_cancel(pos->th);
239 GNUNET_SERVER_client_drop (pos->client);
240 while (NULL != (pml = pos->pending_head))
242 GNUNET_CONTAINER_DLL_remove (pos->pending_head, pos->pending_tail, pml);
246 GNUNET_assert (0 == pos->num_pending);
249 if (NULL != nc->server)
250 GNUNET_SERVER_disconnect_notify_cancel (nc->server,
251 &handle_client_disconnect, nc);
257 * Add a client to the notification context.
259 * @param nc context to modify
260 * @param client client to add
263 GNUNET_SERVER_notification_context_add (struct GNUNET_SERVER_NotificationContext
265 struct GNUNET_SERVER_Client *client)
267 struct ClientList *cl;
269 for (cl = nc->clients_head; NULL != cl; cl = cl->next)
270 if (cl->client == client)
271 return; /* already present */
272 cl = GNUNET_malloc (sizeof (struct ClientList));
273 GNUNET_CONTAINER_DLL_insert (nc->clients_head,
278 GNUNET_SERVER_client_keep (client);
283 * Function called to notify a client about the socket begin ready to
284 * queue more data. "buf" will be NULL and "size" zero if the socket
285 * was closed for writing in the meantime.
287 * @param cls the 'struct ClientList *'
288 * @param size number of bytes available in buf
289 * @param buf where the callee should write the message
290 * @return number of bytes written to buf
293 transmit_message (void *cls, size_t size, void *buf)
295 struct ClientList *cl = cls;
297 struct PendingMessageList *pml;
304 /* 'cl' should be freed via disconnect notification shortly */
305 LOG (GNUNET_ERROR_TYPE_DEBUG,
306 "Failed to transmit message from NC queue to client\n");
310 while (NULL != (pml = cl->pending_head))
312 msize = ntohs (pml->msg->size);
315 GNUNET_CONTAINER_DLL_remove (cl->pending_head, cl->pending_tail, pml);
316 LOG (GNUNET_ERROR_TYPE_DEBUG,
317 "Copying message of type %u and size %u from pending queue to transmission buffer\n",
318 ntohs (pml->msg->type), msize);
319 memcpy (&cbuf[ret], pml->msg, msize);
327 LOG (GNUNET_ERROR_TYPE_DEBUG,
328 "Have %u messages left in NC queue, will try transmission again\n",
331 GNUNET_SERVER_notify_transmit_ready (cl->client, ntohs (pml->msg->size),
332 GNUNET_TIME_UNIT_FOREVER_REL,
333 &transmit_message, cl);
337 GNUNET_assert (0 == cl->num_pending);
344 * Send a message to a particular client.
346 * @param nc context to modify
347 * @param client client to transmit to
348 * @param msg message to send
349 * @param can_drop can this message be dropped due to queue length limitations
352 do_unicast (struct GNUNET_SERVER_NotificationContext *nc,
353 struct ClientList *client, const struct GNUNET_MessageHeader *msg,
356 struct PendingMessageList *pml;
359 if ((client->num_pending > nc->queue_length) && (GNUNET_YES == can_drop))
361 LOG (GNUNET_ERROR_TYPE_INFO,
362 "Dropping message of type %u and size %u due to full queue (%u entries)\n",
363 ntohs (msg->type), ntohs (msg->size), (unsigned int) nc->queue_length);
366 if (client->num_pending > nc->queue_length)
368 /* FIXME: consider checking for other messages in the
369 * queue that are 'droppable' */
371 client->num_pending++;
372 size = ntohs (msg->size);
373 pml = GNUNET_malloc (sizeof (struct PendingMessageList) + size);
374 pml->msg = (const struct GNUNET_MessageHeader *) &pml[1];
375 pml->can_drop = can_drop;
376 LOG (GNUNET_ERROR_TYPE_DEBUG,
377 "Adding message of type %u and size %u to pending queue (which has %u entries)\n",
378 ntohs (msg->type), ntohs (msg->size), (unsigned int) nc->queue_length);
379 memcpy (&pml[1], msg, size);
381 GNUNET_CONTAINER_DLL_insert_tail (client->pending_head, client->pending_tail,
383 if (NULL == client->th)
385 GNUNET_SERVER_notify_transmit_ready (client->client,
386 ntohs (client->pending_head->
388 GNUNET_TIME_UNIT_FOREVER_REL,
389 &transmit_message, client);
394 * Send a message to a particular client; must have
395 * already been added to the notification context.
397 * @param nc context to modify
398 * @param client client to transmit to
399 * @param msg message to send
400 * @param can_drop can this message be dropped due to queue length limitations
403 GNUNET_SERVER_notification_context_unicast (struct
404 GNUNET_SERVER_NotificationContext
406 struct GNUNET_SERVER_Client *client,
407 const struct GNUNET_MessageHeader
410 struct ClientList *pos;
412 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
413 if (pos->client == client)
415 GNUNET_assert (NULL != pos);
416 do_unicast (nc, pos, msg, can_drop);
421 * Send a message to all clients of this context.
423 * @param nc context to modify
424 * @param msg message to send
425 * @param can_drop can this message be dropped due to queue length limitations
428 GNUNET_SERVER_notification_context_broadcast (struct
429 GNUNET_SERVER_NotificationContext
431 const struct GNUNET_MessageHeader
434 struct ClientList *pos;
436 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
437 do_unicast (nc, pos, msg, can_drop);
441 /* end of server_nc.c */