2 This file is part of GNUnet.
3 (C) 2010 Christian Grothoff (and other contributing authors)
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11 WITHOUT ANY WARRANTY; without even the implied warranty of
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-server-nc", __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 doubly linked list.
78 struct ClientList *next;
81 * This is a doubly linked list.
83 struct ClientList *prev;
86 * Overall context this client belongs to.
88 struct GNUNET_SERVER_NotificationContext *nc;
91 * Handle to the client.
93 struct GNUNET_SERVER_Client *client;
96 * Handle for pending transmission request to the client (or NULL).
98 struct GNUNET_SERVER_TransmitHandle *th;
101 * Head of linked list of requests queued for transmission.
103 struct PendingMessageList *pending_head;
106 * Tail of linked list of requests queued for transmission.
108 struct PendingMessageList *pending_tail;
111 * Number of messages currently in the list.
113 unsigned int num_pending;
119 * The notification context is the key datastructure for a convenience
120 * API used for transmission of notifications to the client until the
121 * client disconnects (or the notification context is destroyed, in
122 * which case we disconnect these clients). Essentially, all
123 * (notification) messages are queued up until the client is able to
126 struct GNUNET_SERVER_NotificationContext
130 * Server we do notifications for.
132 struct GNUNET_SERVER_Handle *server;
135 * Head of list of clients receiving notifications.
137 struct ClientList *clients_head;
140 * Tail of list of clients receiving notifications.
142 struct ClientList *clients_tail;
145 * Maximum number of optional messages to queue per client.
147 unsigned int queue_length;
153 * Client has disconnected, clean up.
155 * @param cls our 'struct GNUNET_SERVER_NotificationContext *'
156 * @param client handle of client that disconnected
159 handle_client_disconnect (void *cls, struct GNUNET_SERVER_Client *client)
161 struct GNUNET_SERVER_NotificationContext *nc = cls;
162 struct ClientList *pos;
163 struct PendingMessageList *pml;
170 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
171 if (pos->client == client)
175 LOG (GNUNET_ERROR_TYPE_DEBUG,
176 "Client disconnected, cleaning up %u messages in NC queue\n",
178 GNUNET_CONTAINER_DLL_remove (nc->clients_head,
181 while (NULL != (pml = pos->pending_head))
183 GNUNET_CONTAINER_DLL_remove (pos->pending_head, pos->pending_tail, pml);
189 GNUNET_SERVER_notify_transmit_ready_cancel (pos->th);
192 GNUNET_SERVER_client_drop (client);
193 GNUNET_assert (0 == pos->num_pending);
199 * Create a new notification context.
201 * @param server server for which this function creates the context
202 * @param queue_length maximum number of messages to keep in
203 * the notification queue; optional messages are dropped
204 * if the queue gets longer than this number of messages
205 * @return handle to the notification context
207 struct GNUNET_SERVER_NotificationContext *
208 GNUNET_SERVER_notification_context_create (struct GNUNET_SERVER_Handle *server,
209 unsigned int queue_length)
211 struct GNUNET_SERVER_NotificationContext *ret;
213 ret = GNUNET_malloc (sizeof (struct GNUNET_SERVER_NotificationContext));
214 ret->server = server;
215 ret->queue_length = queue_length;
216 GNUNET_SERVER_disconnect_notify (server, &handle_client_disconnect, ret);
222 * Destroy the context, force disconnect for all clients.
224 * @param nc context to destroy.
227 GNUNET_SERVER_notification_context_destroy (struct
228 GNUNET_SERVER_NotificationContext
231 struct ClientList *pos;
232 struct PendingMessageList *pml;
234 while (NULL != (pos = nc->clients_head))
236 GNUNET_CONTAINER_DLL_remove (nc->clients_head,
241 GNUNET_SERVER_notify_transmit_ready_cancel(pos->th);
244 GNUNET_SERVER_client_drop (pos->client);
245 while (NULL != (pml = pos->pending_head))
247 GNUNET_CONTAINER_DLL_remove (pos->pending_head, pos->pending_tail, pml);
251 GNUNET_assert (0 == pos->num_pending);
254 if (NULL != nc->server)
255 GNUNET_SERVER_disconnect_notify_cancel (nc->server,
256 &handle_client_disconnect, nc);
262 * Add a client to the notification context.
264 * @param nc context to modify
265 * @param client client to add
268 GNUNET_SERVER_notification_context_add (struct GNUNET_SERVER_NotificationContext
270 struct GNUNET_SERVER_Client *client)
272 struct ClientList *cl;
274 for (cl = nc->clients_head; NULL != cl; cl = cl->next)
275 if (cl->client == client)
276 return; /* already present */
277 cl = GNUNET_malloc (sizeof (struct ClientList));
278 GNUNET_CONTAINER_DLL_insert (nc->clients_head,
283 GNUNET_SERVER_client_keep (client);
288 * Function called to notify a client about the socket begin ready to
289 * queue more data. "buf" will be NULL and "size" zero if the socket
290 * was closed for writing in the meantime.
292 * @param cls the 'struct ClientList *'
293 * @param size number of bytes available in buf
294 * @param buf where the callee should write the message
295 * @return number of bytes written to buf
298 transmit_message (void *cls, size_t size, void *buf)
300 struct ClientList *cl = cls;
302 struct PendingMessageList *pml;
309 /* 'cl' should be freed via disconnect notification shortly */
310 LOG (GNUNET_ERROR_TYPE_DEBUG,
311 "Failed to transmit message from NC queue to client\n");
315 while (NULL != (pml = cl->pending_head))
317 msize = ntohs (pml->msg->size);
320 GNUNET_CONTAINER_DLL_remove (cl->pending_head, cl->pending_tail, pml);
321 LOG (GNUNET_ERROR_TYPE_DEBUG,
322 "Copying message of type %u and size %u from pending queue to transmission buffer\n",
323 ntohs (pml->msg->type), msize);
324 memcpy (&cbuf[ret], pml->msg, msize);
332 LOG (GNUNET_ERROR_TYPE_DEBUG,
333 "Have %u messages left in NC queue, will try transmission again\n",
336 GNUNET_SERVER_notify_transmit_ready (cl->client, ntohs (pml->msg->size),
337 GNUNET_TIME_UNIT_FOREVER_REL,
338 &transmit_message, cl);
342 GNUNET_assert (0 == cl->num_pending);
349 * Send a message to a particular client.
351 * @param nc context to modify
352 * @param client client to transmit to
353 * @param msg message to send
354 * @param can_drop can this message be dropped due to queue length limitations
357 do_unicast (struct GNUNET_SERVER_NotificationContext *nc,
358 struct ClientList *client, const struct GNUNET_MessageHeader *msg,
361 struct PendingMessageList *pml;
364 if ((client->num_pending > nc->queue_length) && (GNUNET_YES == can_drop))
366 LOG (GNUNET_ERROR_TYPE_INFO,
367 "Dropping message of type %u and size %u due to full queue (%u entries)\n",
368 ntohs (msg->type), ntohs (msg->size), (unsigned int) nc->queue_length);
371 if (client->num_pending > nc->queue_length)
373 /* FIXME: consider checking for other messages in the
374 * queue that are 'droppable' */
376 client->num_pending++;
377 size = ntohs (msg->size);
378 pml = GNUNET_malloc (sizeof (struct PendingMessageList) + size);
379 pml->msg = (const struct GNUNET_MessageHeader *) &pml[1];
380 pml->can_drop = can_drop;
381 LOG (GNUNET_ERROR_TYPE_DEBUG,
382 "Adding message of type %u and size %u to pending queue (which has %u entries)\n",
383 ntohs (msg->type), ntohs (msg->size), (unsigned int) nc->queue_length);
384 memcpy (&pml[1], msg, size);
386 GNUNET_CONTAINER_DLL_insert_tail (client->pending_head, client->pending_tail,
388 if (NULL == client->th)
390 GNUNET_SERVER_notify_transmit_ready (client->client,
391 ntohs (client->pending_head->
393 GNUNET_TIME_UNIT_FOREVER_REL,
394 &transmit_message, client);
399 * Send a message to a particular client; must have
400 * already been added to the notification context.
402 * @param nc context to modify
403 * @param client client to transmit to
404 * @param msg message to send
405 * @param can_drop can this message be dropped due to queue length limitations
408 GNUNET_SERVER_notification_context_unicast (struct
409 GNUNET_SERVER_NotificationContext
411 struct GNUNET_SERVER_Client *client,
412 const struct GNUNET_MessageHeader
415 struct ClientList *pos;
417 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
418 if (pos->client == client)
420 GNUNET_assert (NULL != pos);
421 do_unicast (nc, pos, msg, can_drop);
426 * Send a message to all clients of this context.
428 * @param nc context to modify
429 * @param msg message to send
430 * @param can_drop can this message be dropped due to queue length limitations
433 GNUNET_SERVER_notification_context_broadcast (struct
434 GNUNET_SERVER_NotificationContext
436 const struct GNUNET_MessageHeader
439 struct ClientList *pos;
441 for (pos = nc->clients_head; NULL != pos; pos = pos->next)
442 do_unicast (nc, pos, msg, can_drop);
446 /* end of server_nc.c */