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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.
37 struct SubscriberList {
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;
67 * The notification context is the key datastructure for a convenience
68 * API used for transmission of notifications to the subscriber until the
69 * subscriber disconnects (or the notification context is destroyed, in
70 * which case we disconnect these subscribers). Essentially, all
71 * (notification) messages are queued up until the subscriber is able to
74 struct GNUNET_NotificationContext {
76 * Head of list of subscribers receiving notifications.
78 struct SubscriberList *subscribers_head;
81 * Tail of list of subscribers receiving notifications.
83 struct SubscriberList *subscribers_tail;
86 * Maximum number of optional messages to queue per subscriber.
88 unsigned int queue_length;
93 * Subscriber has disconnected, clean up.
95 * @param cls our `struct SubscriberList *`
98 handle_mq_destroy(void *cls)
100 struct SubscriberList *pos = cls;
101 struct GNUNET_NotificationContext *nc = pos->nc;
103 GNUNET_CONTAINER_DLL_remove(nc->subscribers_head,
104 nc->subscribers_tail,
111 * Create a new notification context.
113 * @param queue_length maximum number of messages to keep in
114 * the notification queue; optional messages are dropped
115 * if the queue gets longer than this number of messages
116 * @return handle to the notification context
118 struct GNUNET_NotificationContext *
119 GNUNET_notification_context_create(unsigned int queue_length)
121 struct GNUNET_NotificationContext *nc;
123 nc = GNUNET_new(struct GNUNET_NotificationContext);
124 nc->queue_length = queue_length;
130 * Destroy the context, force disconnect for all subscribers.
132 * @param nc context to destroy.
135 GNUNET_notification_context_destroy(struct GNUNET_NotificationContext *nc)
137 struct SubscriberList *pos;
139 while (NULL != (pos = nc->subscribers_head))
141 GNUNET_CONTAINER_DLL_remove(nc->subscribers_head,
142 nc->subscribers_tail,
144 GNUNET_MQ_destroy_notify_cancel(pos->mq_nh);
152 * Add a subscriber to the notification context.
154 * @param nc context to modify
155 * @param mq message queue add
158 GNUNET_notification_context_add(struct GNUNET_NotificationContext *nc,
159 struct GNUNET_MQ_Handle *mq)
161 struct SubscriberList *cl;
163 for (cl = nc->subscribers_head; NULL != cl; cl = cl->next)
166 /* already present */
167 cl = GNUNET_new(struct SubscriberList);
168 GNUNET_CONTAINER_DLL_insert(nc->subscribers_head,
169 nc->subscribers_tail,
173 cl->mq_nh = GNUNET_MQ_destroy_notify(cl->mq,
180 * Send a message to all subscribers of this context.
182 * @param nc context to modify
183 * @param msg message to send
184 * @param can_drop can this message be dropped due to queue length limitations
187 GNUNET_notification_context_broadcast(struct GNUNET_NotificationContext *nc,
188 const struct GNUNET_MessageHeader *msg,
191 struct SubscriberList *pos;
192 struct GNUNET_MQ_Envelope *env;
194 for (pos = nc->subscribers_head; NULL != pos; pos = pos->next)
196 if ((GNUNET_YES == can_drop) &&
197 (GNUNET_MQ_get_length(pos->mq) > nc->queue_length))
199 env = GNUNET_MQ_msg_copy(msg);
200 GNUNET_MQ_send(pos->mq,
207 * Return active number of subscribers in this context.
209 * @param nc context to query
210 * @return number of current subscribers
213 GNUNET_notification_context_get_size(struct GNUNET_NotificationContext *nc)
216 struct SubscriberList *pos;
219 for (pos = nc->subscribers_head; NULL != pos; pos = pos->next)