2 This file is part of GNUnet.
3 (C) 2010 Christian Grothoff (and other contributing authors)
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
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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_common.h"
30 #include "gnunet_connection_lib.h"
31 #include "gnunet_container_lib.h"
32 #include "gnunet_scheduler_lib.h"
33 #include "gnunet_server_lib.h"
34 #include "gnunet_time_lib.h"
36 #define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
40 * Entry in list of messages pending to be transmitted.
42 struct PendingMessageList
46 * This is a doubly-linked list.
48 struct PendingMessageList *next;
51 * This is a doubly-linked list.
53 struct PendingMessageList *prev;
56 * Message to transmit (allocated at the end of this
57 * struct, do not free)
59 const struct GNUNET_MessageHeader *msg;
62 * Can this message be dropped?
70 * Lists of clients we manage for notifications.
76 * This is a linked list.
78 struct ClientList *next;
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 * List of clients receiving notifications.
132 struct ClientList *clients;
135 * Maximum number of optional messages to queue per client.
137 unsigned int queue_length;
143 * Client has disconnected, clean up.
145 * @param cls our 'struct GNUNET_SERVER_NotificationContext *'
146 * @param client handle of client that disconnected
149 handle_client_disconnect (void *cls, struct GNUNET_SERVER_Client *client)
151 struct GNUNET_SERVER_NotificationContext *nc = cls;
152 struct ClientList *pos;
153 struct ClientList *prev;
154 struct PendingMessageList *pml;
165 if (pos->client == client)
172 LOG (GNUNET_ERROR_TYPE_DEBUG,
173 "Client disconnected, cleaning up %u messages in NC queue\n",
176 nc->clients = pos->next;
178 prev->next = pos->next;
179 while (NULL != (pml = pos->pending_head))
181 GNUNET_CONTAINER_DLL_remove (pos->pending_head, pos->pending_tail, pml);
186 GNUNET_SERVER_notify_transmit_ready_cancel (pos->th);
189 GNUNET_SERVER_client_drop (client);
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 * it 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_malloc (sizeof (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
224 GNUNET_SERVER_NotificationContext
227 struct ClientList *pos;
228 struct PendingMessageList *pml;
230 while (NULL != (pos = nc->clients))
232 nc->clients = pos->next;
233 GNUNET_SERVER_client_drop (pos->client);
234 while (NULL != (pml = pos->pending_head))
236 GNUNET_CONTAINER_DLL_remove (pos->pending_head, pos->pending_tail, pml);
241 if (nc->server != NULL)
242 GNUNET_SERVER_disconnect_notify_cancel (nc->server,
243 &handle_client_disconnect, nc);
249 * Add a client to the notification context.
251 * @param nc context to modify
252 * @param client client to add
255 GNUNET_SERVER_notification_context_add (struct GNUNET_SERVER_NotificationContext
257 struct GNUNET_SERVER_Client *client)
259 struct ClientList *cl;
261 for (cl = nc->clients; NULL != cl; cl = cl->next)
262 if (cl->client == client)
263 return; /* already present */
264 cl = GNUNET_malloc (sizeof (struct ClientList));
265 cl->next = nc->clients;
268 GNUNET_SERVER_client_keep (client);
274 * Function called to notify a client about the socket begin ready to
275 * queue more data. "buf" will be NULL and "size" zero if the socket
276 * was closed for writing in the meantime.
278 * @param cls the 'struct ClientList *'
279 * @param size number of bytes available in buf
280 * @param buf where the callee should write the message
281 * @return number of bytes written to buf
284 transmit_message (void *cls, size_t size, void *buf)
286 struct ClientList *cl = cls;
288 struct PendingMessageList *pml;
295 /* 'cl' should be freed via disconnect notification shortly */
296 LOG (GNUNET_ERROR_TYPE_DEBUG,
297 "Failed to transmit message from NC queue to client\n");
301 while (NULL != (pml = cl->pending_head))
303 msize = ntohs (pml->msg->size);
306 GNUNET_CONTAINER_DLL_remove (cl->pending_head, cl->pending_tail, pml);
307 LOG (GNUNET_ERROR_TYPE_DEBUG,
308 "Copying message of type %u and size %u from pending queue to transmission buffer\n",
309 ntohs (pml->msg->type), msize);
310 memcpy (&cbuf[ret], pml->msg, msize);
318 LOG (GNUNET_ERROR_TYPE_DEBUG,
319 "Have %u messages left in NC queue, will try transmission again\n",
322 GNUNET_SERVER_notify_transmit_ready (cl->client, ntohs (pml->msg->size),
323 GNUNET_TIME_UNIT_FOREVER_REL,
324 &transmit_message, cl);
327 GNUNET_assert (cl->num_pending == 0);
333 * Send a message to a particular client.
335 * @param nc context to modify
336 * @param client client to transmit to
337 * @param msg message to send
338 * @param can_drop can this message be dropped due to queue length limitations
341 do_unicast (struct GNUNET_SERVER_NotificationContext *nc,
342 struct ClientList *client, const struct GNUNET_MessageHeader *msg,
345 struct PendingMessageList *pml;
348 if ((client->num_pending > nc->queue_length) && (GNUNET_YES == can_drop))
350 LOG (GNUNET_ERROR_TYPE_INFO,
351 "Dropping message of type %u and size %u due to full queue (%u entries)\n",
352 ntohs (msg->type), ntohs (msg->size), (unsigned int) nc->queue_length);
355 if (client->num_pending > nc->queue_length)
357 /* FIXME: consider checking for other messages in the
358 * queue that are 'droppable' */
360 client->num_pending++;
361 size = ntohs (msg->size);
362 pml = GNUNET_malloc (sizeof (struct PendingMessageList) + size);
363 pml->msg = (const struct GNUNET_MessageHeader *) &pml[1];
364 pml->can_drop = can_drop;
365 LOG (GNUNET_ERROR_TYPE_DEBUG,
366 "Adding message of type %u and size %u to pending queue (which has %u entries)\n",
367 ntohs (msg->type), ntohs (msg->size), (unsigned int) nc->queue_length);
368 memcpy (&pml[1], msg, size);
370 GNUNET_CONTAINER_DLL_insert_tail (client->pending_head, client->pending_tail,
372 if (client->th == NULL)
374 GNUNET_SERVER_notify_transmit_ready (client->client,
375 ntohs (client->pending_head->
377 GNUNET_TIME_UNIT_FOREVER_REL,
378 &transmit_message, client);
383 * Send a message to a particular client; must have
384 * already been added to the notification context.
386 * @param nc context to modify
387 * @param client client to transmit to
388 * @param msg message to send
389 * @param can_drop can this message be dropped due to queue length limitations
392 GNUNET_SERVER_notification_context_unicast (struct
393 GNUNET_SERVER_NotificationContext
395 struct GNUNET_SERVER_Client *client,
396 const struct GNUNET_MessageHeader
399 struct ClientList *pos;
404 if (pos->client == client)
408 GNUNET_assert (pos != NULL);
409 do_unicast (nc, pos, msg, can_drop);
414 * Send a message to all clients of this context.
416 * @param nc context to modify
417 * @param msg message to send
418 * @param can_drop can this message be dropped due to queue length limitations
421 GNUNET_SERVER_notification_context_broadcast (struct
422 GNUNET_SERVER_NotificationContext
424 const struct GNUNET_MessageHeader
427 struct ClientList *pos;
432 do_unicast (nc, pos, msg, can_drop);
438 /* end of server_nc.c */