node: fix high cpu usage

etc/websocket-demo.conf

@@ -0,0 +1,65 @@
+/** Example configuration file for VILLASnode.
+ *
+ * The syntax of this file is similar to JSON.
+ * A detailed description of the format can be found here:
+ *   http://www.hyperrealm.com/libconfig/libconfig_manual.html#Configuration-Files
+ *
+ * @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
+ * @copyright 2017, Institute for Automation of Complex Power Systems, EONERC
+ * @license GNU General Public License (version 3)
+ *
+ * VILLASnode
+ *
+ * This program 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 of the License, or
+ * any later version.
+ *
+ * This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ *********************************************************************************/
+
+stats = 1;
+
+nodes = {
+	sig_1 = {
+		type = "signal",
+
+		signal = "mixed",
+		values = 4,
+		rate = 50
+	},
+	ws_1 = {
+		type = "websocket",
+		description = "Demo Channel",
+		vectorize = 50,
+		source = {
+			simulator = "OP5600",
+			location = "ACS lab"
+		},
+		series = (
+			{ label = "Random walk", unit = "V" },
+			{ label = "Sine",        unit = "A" },
+			{ label = "Rect",        unit = "Var"},
+			{ label = "Ramp",        unit = "°C" }
+		)
+	}
+};
+
+############       List of paths       ############
+
+paths = (
+	{
+		in = "sig_1",
+		out = "ws_1",
+		reverse = false
+		hooks = (
+			{ type = "stats" }
+		)
+	}
+);

src/node.c

@@ -132,12 +132,13 @@ int main(int argc, char *argv[])
 	if (sn.stats > 0)
 		stats_print_header(STATS_FORMAT_HUMAN);
 
-	struct timespec now, last = time_now();
 
-	/* Run! Until signal handler is invoked */
-	while (1) {
-		now = time_now();
-		if (sn.stats > 0 && time_delta(&last, &now) > sn.stats) {
+	if (sn.stats > 0) {
+		int tfd = timerfd_create_rate(1.0 / sn.stats);
+
+		for (;;) {
+			timerfd_wait(tfd);
+
 			for (size_t i = 0; i < list_length(&sn.paths); i++) {
 				struct path *p = list_at(&sn.paths, i);
 
@@ -150,10 +151,12 @@ int main(int argc, char *argv[])
 					hook_periodic(h);
 				}
 			}
-
-			last = time_now();
 		}
 	}
+	else {
+		for (;;)
+			pause();
+	}
 
 	return 0;
 }