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3 Copyright (C) 2010, 2016 GNUnet e.V.
5 GNUnet is free software: you can redistribute it and/or modify it
6 under the terms of the GNU Affero General Public License as published
7 by the Free Software Foundation, either version 3 of the License,
8 or (at your option) any later version.
10 GNUnet is distributed in the hope that it will be useful, but
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.
15 You should have received a copy of the GNU Affero General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
18 SPDX-License-Identifier: AGPL3.0-or-later
23 * @brief convenience functions for transmission of
24 * messages to multiple clients
25 * @author Christian Grothoff
29 #include "gnunet_util_lib.h"
31 #define LOG(kind, ...) GNUNET_log_from (kind, "util-nc", __VA_ARGS__)
35 * Lists of subscribers we manage for notifications.
40 * This is a doubly linked list.
42 struct SubscriberList *next;
45 * This is a doubly linked list.
47 struct SubscriberList *prev;
50 * Overall context this subscriber belongs to.
52 struct GNUNET_NotificationContext *nc;
55 * Handle where we registered with @e mq to be told about
56 * the MQ's destruction.
58 struct GNUNET_MQ_DestroyNotificationHandle *mq_nh;
61 * Message queue for the subscriber.
63 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
78 * Head of list of subscribers receiving notifications.
80 struct SubscriberList *subscribers_head;
83 * Tail of list of subscribers receiving notifications.
85 struct SubscriberList *subscribers_tail;
88 * Maximum number of optional messages to queue per subscriber.
90 unsigned int queue_length;
95 * Subscriber has disconnected, clean up.
97 * @param cls our `struct SubscriberList *`
100 handle_mq_destroy (void *cls)
102 struct SubscriberList *pos = cls;
103 struct GNUNET_NotificationContext *nc = pos->nc;
105 GNUNET_CONTAINER_DLL_remove (nc->subscribers_head,
106 nc->subscribers_tail,
113 * Create a new notification context.
115 * @param queue_length maximum number of messages to keep in
116 * the notification queue; optional messages are dropped
117 * if the queue gets longer than this number of messages
118 * @return handle to the notification context
120 struct GNUNET_NotificationContext *
121 GNUNET_notification_context_create (unsigned int queue_length)
123 struct GNUNET_NotificationContext *nc;
125 nc = GNUNET_new (struct GNUNET_NotificationContext);
126 nc->queue_length = queue_length;
132 * Destroy the context, force disconnect for all subscribers.
134 * @param nc context to destroy.
137 GNUNET_notification_context_destroy (struct GNUNET_NotificationContext *nc)
139 struct SubscriberList *pos;
141 while (NULL != (pos = nc->subscribers_head))
143 GNUNET_CONTAINER_DLL_remove (nc->subscribers_head,
144 nc->subscribers_tail,
146 GNUNET_MQ_destroy_notify_cancel (pos->mq_nh);
154 * Add a subscriber to the notification context.
156 * @param nc context to modify
157 * @param mq message queue add
160 GNUNET_notification_context_add (struct GNUNET_NotificationContext *nc,
161 struct GNUNET_MQ_Handle *mq)
163 struct SubscriberList *cl;
165 for (cl = nc->subscribers_head; NULL != cl; cl = cl->next)
168 /* already present */
169 cl = GNUNET_new (struct SubscriberList);
170 GNUNET_CONTAINER_DLL_insert (nc->subscribers_head,
171 nc->subscribers_tail,
175 cl->mq_nh = GNUNET_MQ_destroy_notify (cl->mq,
182 * Send a message to all subscribers of this context.
184 * @param nc context to modify
185 * @param msg message to send
186 * @param can_drop can this message be dropped due to queue length limitations
189 GNUNET_notification_context_broadcast (struct GNUNET_NotificationContext *nc,
190 const struct GNUNET_MessageHeader *msg,
193 struct SubscriberList *pos;
194 struct GNUNET_MQ_Envelope *env;
196 for (pos = nc->subscribers_head; NULL != pos; pos = pos->next)
198 if ((GNUNET_YES == can_drop) &&
199 (GNUNET_MQ_get_length (pos->mq) > nc->queue_length))
201 env = GNUNET_MQ_msg_copy (msg);
202 GNUNET_MQ_send (pos->mq,
209 * Return active number of subscribers in this context.
211 * @param nc context to query
212 * @return number of current subscribers
215 GNUNET_notification_context_get_size (struct GNUNET_NotificationContext *nc)
218 struct SubscriberList *pos;
221 for (pos = nc->subscribers_head; NULL != pos; pos = pos->next)