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3 Copyright (C) 2010, 2016 GNUnet e.V.
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7 by the Free Software Foundation, either version 3 of the License,
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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 Affero General Public License for more details.
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16 along with this program. If not, see <http://www.gnu.org/licenses/>.
21 * @brief convenience functions for transmission of
22 * messages to multiple clients
23 * @author Christian Grothoff
27 #include "gnunet_util_lib.h"
29 #define LOG(kind,...) GNUNET_log_from (kind, "util-nc", __VA_ARGS__)
33 * Lists of subscribers we manage for notifications.
39 * This is a doubly linked list.
41 struct SubscriberList *next;
44 * This is a doubly linked list.
46 struct SubscriberList *prev;
49 * Overall context this subscriber belongs to.
51 struct GNUNET_NotificationContext *nc;
54 * Handle where we registered with @e mq to be told about
55 * the MQ's destruction.
57 struct GNUNET_MQ_DestroyNotificationHandle *mq_nh;
60 * Message queue for the subscriber.
62 struct GNUNET_MQ_Handle *mq;
68 * The notification context is the key datastructure for a convenience
69 * API used for transmission of notifications to the subscriber until the
70 * subscriber disconnects (or the notification context is destroyed, in
71 * which case we disconnect these subscribers). Essentially, all
72 * (notification) messages are queued up until the subscriber is able to
75 struct GNUNET_NotificationContext
79 * Head of list of subscribers receiving notifications.
81 struct SubscriberList *subscribers_head;
84 * Tail of list of subscribers receiving notifications.
86 struct SubscriberList *subscribers_tail;
89 * Maximum number of optional messages to queue per subscriber.
91 unsigned int queue_length;
97 * Subscriber has disconnected, clean up.
99 * @param cls our `struct SubscriberList *`
102 handle_mq_destroy (void *cls)
104 struct SubscriberList *pos = cls;
105 struct GNUNET_NotificationContext *nc = pos->nc;
107 GNUNET_CONTAINER_DLL_remove (nc->subscribers_head,
108 nc->subscribers_tail,
115 * Create a new notification context.
117 * @param queue_length maximum number of messages to keep in
118 * the notification queue; optional messages are dropped
119 * if the queue gets longer than this number of messages
120 * @return handle to the notification context
122 struct GNUNET_NotificationContext *
123 GNUNET_notification_context_create (unsigned int queue_length)
125 struct GNUNET_NotificationContext *nc;
127 nc = GNUNET_new (struct GNUNET_NotificationContext);
128 nc->queue_length = queue_length;
134 * Destroy the context, force disconnect for all subscribers.
136 * @param nc context to destroy.
139 GNUNET_notification_context_destroy (struct GNUNET_NotificationContext *nc)
141 struct SubscriberList *pos;
143 while (NULL != (pos = nc->subscribers_head))
145 GNUNET_CONTAINER_DLL_remove (nc->subscribers_head,
146 nc->subscribers_tail,
148 GNUNET_MQ_destroy_notify_cancel (pos->mq_nh);
156 * Add a subscriber to the notification context.
158 * @param nc context to modify
159 * @param mq message queue add
162 GNUNET_notification_context_add (struct GNUNET_NotificationContext *nc,
163 struct GNUNET_MQ_Handle *mq)
165 struct SubscriberList *cl;
167 for (cl = nc->subscribers_head; NULL != cl; cl = cl->next)
169 return; /* already present */
170 cl = GNUNET_new (struct SubscriberList);
171 GNUNET_CONTAINER_DLL_insert (nc->subscribers_head,
172 nc->subscribers_tail,
176 cl->mq_nh = GNUNET_MQ_destroy_notify (cl->mq,
183 * Send a message to all subscribers of this context.
185 * @param nc context to modify
186 * @param msg message to send
187 * @param can_drop can this message be dropped due to queue length limitations
190 GNUNET_notification_context_broadcast (struct GNUNET_NotificationContext *nc,
191 const struct GNUNET_MessageHeader *msg,
194 struct SubscriberList *pos;
195 struct GNUNET_MQ_Envelope *env;
197 for (pos = nc->subscribers_head; NULL != pos; pos = pos->next)
199 if ( (GNUNET_YES == can_drop) &&
200 (GNUNET_MQ_get_length (pos->mq) > nc->queue_length) )
202 env = GNUNET_MQ_msg_copy (msg);
203 GNUNET_MQ_send (pos->mq,
210 * Return active number of subscribers in this context.
212 * @param nc context to query
213 * @return number of current subscribers
216 GNUNET_notification_context_get_size (struct GNUNET_NotificationContext *nc)
219 struct SubscriberList *pos;
222 for (pos = nc->subscribers_head; NULL != pos; pos = pos->next)