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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,
155 struct GNUNET_SERVER_Client *client)
157 struct GNUNET_SERVER_NotificationContext *nc = cls;
158 struct ClientList *pos;
159 struct PendingMessageList *pml;
166 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
167 if (pos->client == client)
171 LOG (GNUNET_ERROR_TYPE_DEBUG,
172 "Client disconnected, cleaning up %u messages in NC queue\n",
174 GNUNET_CONTAINER_DLL_remove (nc->clients_head,
177 while (NULL != (pml = pos->pending_head))
179 GNUNET_CONTAINER_DLL_remove (pos->pending_head, pos->pending_tail, pml);
185 GNUNET_SERVER_notify_transmit_ready_cancel (pos->th);
188 GNUNET_SERVER_client_drop (client);
189 GNUNET_assert (0 == pos->num_pending);
195 * Create a new notification context.
197 * @param server server for which this function creates the context
198 * @param queue_length maximum number of messages to keep in
199 * the notification queue; optional messages are dropped
200 * if the queue gets longer than this number of messages
201 * @return handle to the notification context
203 struct GNUNET_SERVER_NotificationContext *
204 GNUNET_SERVER_notification_context_create (struct GNUNET_SERVER_Handle *server,
205 unsigned int queue_length)
207 struct GNUNET_SERVER_NotificationContext *ret;
209 ret = GNUNET_new (struct GNUNET_SERVER_NotificationContext);
210 ret->server = server;
211 ret->queue_length = queue_length;
212 GNUNET_SERVER_disconnect_notify (server, &handle_client_disconnect, ret);
218 * Destroy the context, force disconnect for all clients.
220 * @param nc context to destroy.
223 GNUNET_SERVER_notification_context_destroy (struct GNUNET_SERVER_NotificationContext *nc)
225 struct ClientList *pos;
226 struct PendingMessageList *pml;
228 while (NULL != (pos = nc->clients_head))
230 GNUNET_CONTAINER_DLL_remove (nc->clients_head,
235 GNUNET_SERVER_notify_transmit_ready_cancel(pos->th);
238 GNUNET_SERVER_client_drop (pos->client);
239 while (NULL != (pml = pos->pending_head))
241 GNUNET_CONTAINER_DLL_remove (pos->pending_head, pos->pending_tail, pml);
245 GNUNET_assert (0 == pos->num_pending);
248 if (NULL != nc->server)
249 GNUNET_SERVER_disconnect_notify_cancel (nc->server,
250 &handle_client_disconnect, nc);
256 * Add a client to the notification context.
258 * @param nc context to modify
259 * @param client client to add
262 GNUNET_SERVER_notification_context_add (struct GNUNET_SERVER_NotificationContext *nc,
263 struct GNUNET_SERVER_Client *client)
265 struct ClientList *cl;
267 for (cl = nc->clients_head; NULL != cl; cl = cl->next)
268 if (cl->client == client)
269 return; /* already present */
270 cl = GNUNET_new (struct ClientList);
271 GNUNET_CONTAINER_DLL_insert (nc->clients_head,
276 GNUNET_SERVER_client_keep (client);
281 * Function called to notify a client about the socket begin ready to
282 * queue more data. @a buf will be NULL and @a size zero if the socket
283 * was closed for writing in the meantime.
285 * @param cls the `struct ClientList *`
286 * @param size number of bytes available in @a buf
287 * @param buf where the callee should write the message
288 * @return number of bytes written to buf
291 transmit_message (void *cls, size_t size, void *buf)
293 struct ClientList *cl = cls;
295 struct PendingMessageList *pml;
302 /* 'cl' should be freed via disconnect notification shortly */
303 LOG (GNUNET_ERROR_TYPE_DEBUG,
304 "Failed to transmit message from NC queue to client\n");
308 while (NULL != (pml = cl->pending_head))
310 msize = ntohs (pml->msg->size);
313 GNUNET_CONTAINER_DLL_remove (cl->pending_head, cl->pending_tail, pml);
314 LOG (GNUNET_ERROR_TYPE_DEBUG,
315 "Copying message of type %u and size %u from pending queue to transmission buffer\n",
316 ntohs (pml->msg->type), msize);
317 memcpy (&cbuf[ret], pml->msg, msize);
325 LOG (GNUNET_ERROR_TYPE_DEBUG,
326 "Have %u messages left in NC queue, will try transmission again\n",
329 GNUNET_SERVER_notify_transmit_ready (cl->client, ntohs (pml->msg->size),
330 GNUNET_TIME_UNIT_FOREVER_REL,
331 &transmit_message, cl);
335 GNUNET_assert (0 == cl->num_pending);
342 * Send a message to a particular client.
344 * @param nc context to modify
345 * @param client client to transmit to
346 * @param msg message to send
347 * @param can_drop can this message be dropped due to queue length limitations
350 do_unicast (struct GNUNET_SERVER_NotificationContext *nc,
351 struct ClientList *client,
352 const struct GNUNET_MessageHeader *msg,
355 struct PendingMessageList *pml;
358 if ((client->num_pending > nc->queue_length) && (GNUNET_YES == can_drop))
360 LOG (GNUNET_ERROR_TYPE_INFO,
361 "Dropping message of type %u and size %u due to full queue (%u entries)\n",
362 ntohs (msg->type), ntohs (msg->size), (unsigned int) nc->queue_length);
365 if (client->num_pending > nc->queue_length)
367 /* FIXME: consider checking for other messages in the
368 * queue that are 'droppable' */
370 client->num_pending++;
371 size = ntohs (msg->size);
372 pml = GNUNET_malloc (sizeof (struct PendingMessageList) + size);
373 pml->msg = (const struct GNUNET_MessageHeader *) &pml[1];
374 pml->can_drop = can_drop;
375 LOG (GNUNET_ERROR_TYPE_DEBUG,
376 "Adding message of type %u and size %u to pending queue (which has %u entries)\n",
377 ntohs (msg->type), ntohs (msg->size), (unsigned int) nc->queue_length);
378 memcpy (&pml[1], msg, size);
380 GNUNET_CONTAINER_DLL_insert_tail (client->pending_head, client->pending_tail,
382 if (NULL == client->th)
384 GNUNET_SERVER_notify_transmit_ready (client->client,
385 ntohs (client->pending_head->
387 GNUNET_TIME_UNIT_FOREVER_REL,
388 &transmit_message, client);
393 * Send a message to a particular client; must have
394 * already been added to the notification context.
396 * @param nc context to modify
397 * @param client client to transmit to
398 * @param msg message to send
399 * @param can_drop can this message be dropped due to queue length limitations
402 GNUNET_SERVER_notification_context_unicast (struct
403 GNUNET_SERVER_NotificationContext *nc,
404 struct GNUNET_SERVER_Client *client,
405 const struct GNUNET_MessageHeader *msg,
408 struct ClientList *pos;
410 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
411 if (pos->client == client)
413 GNUNET_assert (NULL != pos);
414 do_unicast (nc, pos, msg, can_drop);
419 * Send a message to all clients of this context.
421 * @param nc context to modify
422 * @param msg message to send
423 * @param can_drop can this message be dropped due to queue length limitations
426 GNUNET_SERVER_notification_context_broadcast (struct
427 GNUNET_SERVER_NotificationContext *nc,
428 const struct GNUNET_MessageHeader *msg,
431 struct ClientList *pos;
433 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
434 do_unicast (nc, pos, msg, can_drop);
438 /* end of server_nc.c */