Use single thread for usrsctp stack

conf/janus.jcfg.sample.in

@@ -105,6 +105,9 @@ general: {
 									# As such, if you want to use this you should
 									# provision the correct value according to the
 									# available resources (e.g., CPUs available).
+	#usrsctp_singlethread = true	# You can also choose whether to use a single thread
+									# for the usrsctp stack, or use their internal
+									# threads instead (default=multiple threads).
 	#opaqueid_in_api = true			# Opaque IDs set by applications are typically
 									# only passed to event handlers for correlation
 									# purposes, but not sent back to the user or
@@ -205,6 +208,7 @@ media: {
 	#slowlink_threshold = 4
 	#twcc_period = 100
 	#dtls_timeout = 500
+	#usrsctp_single_thread = true
 
 	# If you need DSCP packet marking and prioritization, you can configure
 	# the 'dscp' property to a specific values, and Janus will try to

janus.c

@@ -4846,7 +4846,9 @@ gint main(int argc, char *argv[])
 
 #ifdef HAVE_SCTP
 	/* Initialize SCTP for DataChannels */
-	if(janus_sctp_init() < 0) {
+	item = janus_config_get(config, config_general, janus_config_type_item, "usrsctp_singlethread");
+	gboolean st = (item && item->value && janus_is_true(item->value));
+	if(janus_sctp_init(st) < 0) {
 		exit(1);
 	}
 #else

sctp.c

@@ -126,10 +126,58 @@ static GHashTable *sctp_ids = NULL;
 static void janus_sctp_association_unref(janus_sctp_association *sctp);
 
 /* SCTP management code */
-static gboolean sctp_running;
-int janus_sctp_init(void) {
-	/* Initialize the SCTP stack */
-	usrsctp_init(0, janus_sctp_data_to_dtls, NULL);
+static gboolean sctp_running = FALSE;
+static gint64 sctp_last_called = 0;
+static GMainContext *sctp_mainctx;
+static GMainLoop *sctp_mainloop = NULL;
+static GThread *sctp_thread = NULL;
+static GSource *sctp_timer = NULL;
+static gpointer janus_sctp_thread(gpointer user_data) {
+	JANUS_LOG(LOG_VERB, "SCTP timer thread started\n");
+	g_main_loop_run(sctp_mainloop);
+	/* When the loop quits, we can unref it */
+	g_main_loop_unref(sctp_mainloop);
+	g_main_context_unref(sctp_mainctx);
+	JANUS_LOG(LOG_VERB, "Leaving SCTP timer thread\n");
+	return NULL;
+}
+static gboolean janus_sctp_timer(gpointer user_data) {
+	gint64 now = janus_get_monotonic_time();
+	guint32 elapsed = sctp_last_called ? (now-sctp_last_called) : 0;
+	sctp_last_called = now;
+	usrsctp_handle_timers(elapsed);
+	return TRUE;
+}
+int janus_sctp_init(gboolean single_thread) {
+	JANUS_LOG(LOG_INFO, "Using %s for the usrsctp stack\n",
+		single_thread ? "a single thread" : "multiple treads");
+	if(!single_thread) {
+		/* Initialize the SCTP stack */
+		usrsctp_init(0, janus_sctp_data_to_dtls, NULL);
+	} else {
+		/* Create a loop that we'll use for SCTP timers */
+		sctp_mainctx = g_main_context_new();
+		sctp_mainloop = g_main_loop_new(sctp_mainctx, FALSE);
+		GError *error = NULL;
+		char tname[16];
+		g_snprintf(tname, sizeof(tname), "sctp timers");
+		sctp_thread = g_thread_try_new(tname, &janus_sctp_thread, NULL, &error);
+		if(error != NULL) {
+			g_main_loop_unref(sctp_mainloop);
+			g_main_context_unref(sctp_mainctx);
+			JANUS_LOG(LOG_FATAL, "Got error %d (%s) trying to launch the SCTP timer thread...\n",
+				error->code, error->message ? error->message : "??");
+			g_error_free(error);
+			return -1;
+		}
+		/* Initialize the SCTP stack */
+		usrsctp_init_nothreads(0, janus_sctp_data_to_dtls, NULL);
+		/* Add a timer source (every 10ms) */
+		sctp_timer = g_timeout_source_new(10);
+		g_source_set_callback(sctp_timer, janus_sctp_timer, sctp_mainctx, NULL);
+		g_source_attach(sctp_timer, sctp_mainctx);
+		g_source_unref(sctp_timer);
+	}
 	sctp_running = TRUE;
 
 #ifdef DEBUG_SCTP
@@ -152,6 +200,10 @@ void janus_sctp_deinit(void) {
 	janus_mutex_lock(&sctp_mutex);
 	g_hash_table_unref(sctp_ids);
 	janus_mutex_unlock(&sctp_mutex);
+	if(sctp_mainloop != NULL && g_main_loop_is_running(sctp_mainloop))
+		g_main_loop_quit(sctp_mainloop);
+	if(sctp_thread != NULL)
+		g_thread_join(sctp_thread);
 }
 
 static void janus_sctp_association_unref(janus_sctp_association *sctp) {

sctp.h

@@ -49,7 +49,7 @@
 
 /*! \brief SCTP stuff initialization
  * \returns 0 on success, a negative integer otherwise */
-int janus_sctp_init(void);
+int janus_sctp_init(gboolean single_thread);
 
 /*! \brief SCTP stuff de-initialization */
 void janus_sctp_deinit(void);