2 This file is part of GNUnet.
3 (C) 2010 Christian Grothoff (and other contributing authors)
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6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 2, or (at your
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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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18 Boston, MA 02111-1307, USA.
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"
37 #define DEBUG_SERVER_NC GNUNET_EXTRA_LOGGING
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_CONNECTION_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)
173 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
174 "Client disconnected, cleaning up %u messages in NC queue\n",
178 nc->clients = pos->next;
180 prev->next = pos->next;
181 while (NULL != (pml = pos->pending_head))
183 GNUNET_CONTAINER_DLL_remove (pos->pending_head, pos->pending_tail, pml);
188 GNUNET_CONNECTION_notify_transmit_ready_cancel (pos->th);
191 GNUNET_SERVER_client_drop (client);
197 * Create a new notification context.
199 * @param server server for which this function creates the context
200 * @param queue_length maximum number of messages to keep in
201 * the notification queue; optional messages are dropped
202 * it the queue gets longer than this number of messages
203 * @return handle to the notification context
205 struct GNUNET_SERVER_NotificationContext *
206 GNUNET_SERVER_notification_context_create (struct GNUNET_SERVER_Handle *server,
207 unsigned int queue_length)
209 struct GNUNET_SERVER_NotificationContext *ret;
211 ret = GNUNET_malloc (sizeof (struct GNUNET_SERVER_NotificationContext));
212 ret->server = server;
213 ret->queue_length = queue_length;
214 GNUNET_SERVER_disconnect_notify (server, &handle_client_disconnect, ret);
220 * Destroy the context, force disconnect for all clients.
222 * @param nc context to destroy.
225 GNUNET_SERVER_notification_context_destroy (struct
226 GNUNET_SERVER_NotificationContext
229 struct ClientList *pos;
230 struct PendingMessageList *pml;
232 while (NULL != (pos = nc->clients))
234 nc->clients = pos->next;
235 GNUNET_SERVER_client_drop (pos->client);
236 while (NULL != (pml = pos->pending_head))
238 GNUNET_CONTAINER_DLL_remove (pos->pending_head, pos->pending_tail, pml);
243 if (nc->server != NULL)
244 GNUNET_SERVER_disconnect_notify_cancel (nc->server,
245 &handle_client_disconnect, nc);
251 * Add a client to the notification context.
253 * @param nc context to modify
254 * @param client client to add
257 GNUNET_SERVER_notification_context_add (struct GNUNET_SERVER_NotificationContext
259 struct GNUNET_SERVER_Client *client)
261 struct ClientList *cl;
263 cl = GNUNET_malloc (sizeof (struct ClientList));
264 cl->next = nc->clients;
267 GNUNET_SERVER_client_keep (client);
273 * Function called to notify a client about the socket begin ready to
274 * queue more data. "buf" will be NULL and "size" zero if the socket
275 * was closed for writing in the meantime.
277 * @param cls the 'struct ClientList *'
278 * @param size number of bytes available in buf
279 * @param buf where the callee should write the message
280 * @return number of bytes written to buf
283 transmit_message (void *cls, size_t size, void *buf)
285 struct ClientList *cl = cls;
287 struct PendingMessageList *pml;
294 /* 'cl' should be freed via disconnect notification shortly */
296 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
297 "Failed to transmit message from NC queue to client\n");
302 while (NULL != (pml = cl->pending_head))
304 msize = ntohs (pml->msg->size);
307 GNUNET_CONTAINER_DLL_remove (cl->pending_head, cl->pending_tail, pml);
309 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
310 "Copying message of type %u and size %u from pending queue to transmission buffer\n",
311 ntohs (pml->msg->type), msize);
313 memcpy (&cbuf[ret], pml->msg, msize);
322 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
323 "Have %u messages left in NC queue, will try transmission again\n",
327 GNUNET_SERVER_notify_transmit_ready (cl->client, ntohs (pml->msg->size),
328 GNUNET_TIME_UNIT_FOREVER_REL,
329 &transmit_message, cl);
332 GNUNET_assert (cl->num_pending == 0);
338 * Send a message to a particular client.
340 * @param nc context to modify
341 * @param client client to transmit to
342 * @param msg message to send
343 * @param can_drop can this message be dropped due to queue length limitations
346 do_unicast (struct GNUNET_SERVER_NotificationContext *nc,
347 struct ClientList *client, const struct GNUNET_MessageHeader *msg,
350 struct PendingMessageList *pml;
353 if ((client->num_pending > nc->queue_length) && (GNUNET_YES == can_drop))
355 GNUNET_log (GNUNET_ERROR_TYPE_INFO,
356 "Dropping message of type %u and size %u due to full queue (%u entries)\n",
357 ntohs (msg->type), ntohs (msg->size),
358 (unsigned int) nc->queue_length);
361 if (client->num_pending > nc->queue_length)
363 /* FIXME: consider checking for other messages in the
364 * queue that are 'droppable' */
366 client->num_pending++;
367 size = ntohs (msg->size);
368 pml = GNUNET_malloc (sizeof (struct PendingMessageList) + size);
369 pml->msg = (const struct GNUNET_MessageHeader *) &pml[1];
370 pml->can_drop = can_drop;
372 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
373 "Adding message of type %u and size %u to pending queue (which has %u entries)\n",
374 ntohs (msg->type), ntohs (msg->size),
375 (unsigned int) nc->queue_length);
377 memcpy (&pml[1], msg, size);
379 GNUNET_CONTAINER_DLL_insert_tail (client->pending_head, client->pending_tail,
381 if (client->th == NULL)
383 GNUNET_SERVER_notify_transmit_ready (client->client,
384 ntohs (client->pending_head->
386 GNUNET_TIME_UNIT_FOREVER_REL,
387 &transmit_message, client);
392 * Send a message to a particular client; must have
393 * already been added to the notification context.
395 * @param nc context to modify
396 * @param client client to transmit to
397 * @param msg message to send
398 * @param can_drop can this message be dropped due to queue length limitations
401 GNUNET_SERVER_notification_context_unicast (struct
402 GNUNET_SERVER_NotificationContext
404 struct GNUNET_SERVER_Client *client,
405 const struct GNUNET_MessageHeader
408 struct ClientList *pos;
413 if (pos->client == client)
417 GNUNET_assert (pos != NULL);
418 do_unicast (nc, pos, msg, can_drop);
423 * Send a message to all clients of this context.
425 * @param nc context to modify
426 * @param msg message to send
427 * @param can_drop can this message be dropped due to queue length limitations
430 GNUNET_SERVER_notification_context_broadcast (struct
431 GNUNET_SERVER_NotificationContext
433 const struct GNUNET_MessageHeader
436 struct ClientList *pos;
441 do_unicast (nc, pos, msg, can_drop);
447 /* end of server_nc.c */