uorb top: add 'uorb top -1' to run only once

src/modules/uORB/uORBDeviceMaster.cpp

@@ -249,13 +249,25 @@ void uORB::DeviceMaster::addNewDeviceNodes(DeviceNodeStatisticsData **first_node
 void uORB::DeviceMaster::showTop(char **topic_filter, int num_filters)
 {
 	bool print_active_only = true;
+	bool only_once = false; // if true, run only once, then exit
 
 	if (topic_filter && num_filters > 0) {
-		if (!strcmp("-a", topic_filter[0])) {
-			num_filters = 0;
+		bool show_all = false;
+
+		for (int i = 0; i < num_filters; ++i) {
+			if (!strcmp("-a", topic_filter[i])) {
+				show_all = true;
+
+			} else if (!strcmp("-1", topic_filter[i])) {
+				only_once = true;
+			}
 		}
 
-		print_active_only = false; // print non-active if -a or some filter given
+		print_active_only = only_once ? (num_filters == 1) : false; // print non-active if -a or some filter given
+
+		if (show_all || print_active_only) {
+			num_filters = 0;
+		}
 	}
 
 	PX4_INFO_RAW("\033[2J\n"); //clear screen
@@ -278,7 +290,7 @@ void uORB::DeviceMaster::showTop(char **topic_filter, int num_filters)
 	unlock();
 
 #ifdef __PX4_QURT //QuRT has no poll()
-	int num_runs = 0;
+	only_once = true;
 #else
 	const int stdin_fileno = 0;
 
@@ -292,13 +304,7 @@ void uORB::DeviceMaster::showTop(char **topic_filter, int num_filters)
 
 	while (!quit) {
 
-#ifdef __PX4_QURT
-
-		if (++num_runs > 1) {
-			quit = true; //just exit after one output
-		}
-
-#else
+#ifndef __PX4_QURT
 
 		/* Sleep 200 ms waiting for user input five times ~ 1s */
 		for (int k = 0; k < 5; k++) {
@@ -362,6 +368,10 @@ void uORB::DeviceMaster::showTop(char **topic_filter, int num_filters)
 			addNewDeviceNodes(&first_node, num_topics, max_topic_name_length, topic_filter, num_filters);
 			unlock();
 		}
+
+		if (only_once) {
+			quit = true;
+		}
 	}
 
 	//cleanup

src/modules/uORB/uORBMain.cpp

@@ -78,6 +78,7 @@ $ uorb top
 	PRINT_MODULE_USAGE_COMMAND_DESCR("status", "Print topic statistics");
 	PRINT_MODULE_USAGE_COMMAND_DESCR("top", "Monitor topic publication rates");
 	PRINT_MODULE_USAGE_PARAM_FLAG('a', "print all instead of only currently publishing topics", true);
+	PRINT_MODULE_USAGE_PARAM_FLAG('1', "run only once, then exit", true);
 	PRINT_MODULE_USAGE_ARG("<filter1> [<filter2>]", "topic(s) to match (implies -a)", true);
 }