--- /dev/null
+/*
+ This file is part of GNUnet.
+ Copyright (C) 2010, 2016 GNUnet e.V.
+
+ GNUnet is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published
+ by the Free Software Foundation; either version 3, or (at your
+ option) any later version.
+
+ GNUnet is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with GNUnet; see the file COPYING. If not, write to the
+ Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ Boston, MA 02110-1301, USA.
+*/
+
+/**
+ * @file util/nc.c
+ * @brief convenience functions for transmission of
+ * messages to multiple clients
+ * @author Christian Grothoff
+ */
+
+#include "platform.h"
+#include "gnunet_util_lib.h"
+
+#define LOG(kind,...) GNUNET_log_from (kind, "util-nc", __VA_ARGS__)
+
+
+/**
+ * Lists of subscribers we manage for notifications.
+ */
+struct SubscriberList
+{
+
+ /**
+ * This is a doubly linked list.
+ */
+ struct SubscriberList *next;
+
+ /**
+ * This is a doubly linked list.
+ */
+ struct SubscriberList *prev;
+
+ /**
+ * Overall context this subscriber belongs to.
+ */
+ struct GNUNET_NotificationContext *nc;
+
+ /**
+ * Handle where we registered with @e mq to be told about
+ * the MQ's destruction.
+ */
+ struct GNUNET_MQ_DestroyNotificationHandle *mq_nh;
+
+ /**
+ * Message queue for the subscriber.
+ */
+ struct GNUNET_MQ_Handle *mq;
+
+};
+
+
+/**
+ * The notification context is the key datastructure for a convenience
+ * API used for transmission of notifications to the subscriber until the
+ * subscriber disconnects (or the notification context is destroyed, in
+ * which case we disconnect these subscribers). Essentially, all
+ * (notification) messages are queued up until the subscriber is able to
+ * read them.
+ */
+struct GNUNET_NotificationContext
+{
+
+ /**
+ * Head of list of subscribers receiving notifications.
+ */
+ struct SubscriberList *subscribers_head;
+
+ /**
+ * Tail of list of subscribers receiving notifications.
+ */
+ struct SubscriberList *subscribers_tail;
+
+ /**
+ * Maximum number of optional messages to queue per subscriber.
+ */
+ unsigned int queue_length;
+
+};
+
+
+/**
+ * Subscriber has disconnected, clean up.
+ *
+ * @param cls our `struct SubscriberList *`
+ */
+static void
+handle_mq_destroy (void *cls)
+{
+ struct SubscriberList *pos = cls;
+ struct GNUNET_NotificationContext *nc = pos->nc;
+
+ GNUNET_CONTAINER_DLL_remove (nc->subscribers_head,
+ nc->subscribers_tail,
+ pos);
+ GNUNET_free (pos);
+}
+
+
+/**
+ * Create a new notification context.
+ *
+ * @param queue_length maximum number of messages to keep in
+ * the notification queue; optional messages are dropped
+ * if the queue gets longer than this number of messages
+ * @return handle to the notification context
+ */
+struct GNUNET_NotificationContext *
+GNUNET_notification_context_create (unsigned int queue_length)
+{
+ struct GNUNET_NotificationContext *nc;
+
+ nc = GNUNET_new (struct GNUNET_NotificationContext);
+ nc->queue_length = queue_length;
+ return nc;
+}
+
+
+/**
+ * Destroy the context, force disconnect for all subscribers.
+ *
+ * @param nc context to destroy.
+ */
+void
+GNUNET_notification_context_destroy (struct GNUNET_NotificationContext *nc)
+{
+ struct SubscriberList *pos;
+
+ while (NULL != (pos = nc->subscribers_head))
+ {
+ GNUNET_CONTAINER_DLL_remove (nc->subscribers_head,
+ nc->subscribers_tail,
+ pos);
+ GNUNET_MQ_destroy_notify_cancel (pos->mq_nh);
+ GNUNET_free (pos);
+ }
+ GNUNET_free (nc);
+}
+
+
+/**
+ * Add a subscriber to the notification context.
+ *
+ * @param nc context to modify
+ * @param mq message queue add
+ */
+void
+GNUNET_notification_context_add (struct GNUNET_NotificationContext *nc,
+ struct GNUNET_MQ_Handle *mq)
+{
+ struct SubscriberList *cl;
+
+ for (cl = nc->subscribers_head; NULL != cl; cl = cl->next)
+ if (cl->mq == mq)
+ return; /* already present */
+ cl = GNUNET_new (struct SubscriberList);
+ GNUNET_CONTAINER_DLL_insert (nc->subscribers_head,
+ nc->subscribers_tail,
+ cl);
+ cl->nc = nc;
+ cl->mq = mq;
+ cl->mq_nh = GNUNET_MQ_destroy_notify (cl->mq,
+ &handle_mq_destroy,
+ cl);
+}
+
+
+/**
+ * Send a message to all subscribers of this context.
+ *
+ * @param nc context to modify
+ * @param msg message to send
+ * @param can_drop can this message be dropped due to queue length limitations
+ */
+void
+GNUNET_notification_context_broadcast (struct GNUNET_NotificationContext *nc,
+ const struct GNUNET_MessageHeader *msg,
+ int can_drop)
+{
+ struct SubscriberList *pos;
+ struct GNUNET_MQ_Envelope *env;
+
+ for (pos = nc->subscribers_head; NULL != pos; pos = pos->next)
+ {
+ if ( (GNUNET_YES == can_drop) &&
+ (GNUNET_MQ_get_length (pos->mq) > nc->queue_length) )
+ continue;
+ env = GNUNET_MQ_msg_copy (msg);
+ GNUNET_MQ_send (pos->mq,
+ env);
+ }
+}
+
+
+/**
+ * Return active number of subscribers in this context.
+ *
+ * @param nc context to query
+ * @return number of current subscribers
+ */
+unsigned int
+GNUNET_notification_context_get_size (struct GNUNET_NotificationContext *nc)
+{
+ unsigned int num;
+ struct SubscriberList *pos;
+
+ num = 0;
+ for (pos = nc->subscribers_head; NULL != pos; pos = pos->next)
+ num++;
+ return num;
+}
+
+/* end of nc.c */
projects / oweals / gnunet.git / commitdiff