monitoring: make GNSS thread fill GNSS monitoring info

The GNSS info is collected in separate thread and it's better to prepare
GNSS monitoring data filled in within the same thread. Introduce another
mutex to reduce the scope of the lock section and avoid any double locks.

Signed-off-by: Vadim Fedorenko <[email protected]>

src/gnss.c

@@ -943,6 +943,22 @@ static void * gnss_thread(void * p_data)
 			pthread_mutex_unlock(&gnss->mutex_data);
 			usleep(5 * 1000);
 		}
+
+		/* this thread is the only writer to gnss->session, it's safe read the same values without mutex_data locked */
+		if (gnss->gnss_info) {
+			struct gnss_state *gnss_info = gnss->gnss_info;
+			pthread_mutex_lock(&gnss_info->lock);
+			gnss_info->antenna_power = gnss->session->antenna_power;
+			gnss_info->antenna_status = gnss->session->antenna_status;
+			gnss_info->fix = gnss->session->fix;
+			gnss_info->fixOk = gnss->session->fixOk;
+			gnss_info->leap_seconds = gnss->session->context->leap_seconds;
+			gnss_info->lsChange = gnss->session->context->lsChange;
+			gnss_info->satellites_count = gnss->session->satellites_count;
+			gnss_info->survey_in_position_error = gnss->session->survey_in_position_error;
+			pthread_mutex_unlock(&gnss_info->lock);
+		}
+
 		pthread_mutex_lock(&gnss->mutex_data);
 		stop = gnss->stop;
 		action = gnss->action;

src/gnss.h

@@ -125,6 +125,23 @@ struct gps_context_t {
 		const char *buf, const size_t len);
 };
 
+
+/**
+ * @struct gnss_state
+ * @brief Structure containing data with the latest gnss values
+ */
+struct gnss_state {
+	float survey_in_position_error;
+	int fix;
+	int satellites_count;
+	int leap_seconds;
+	int lsChange;
+	int8_t antenna_power;
+	int8_t antenna_status;
+	bool fixOk;
+	pthread_mutex_t lock;
+};
+
 /**
  * @struct gps_device_t
  * @brief Structure containing data about the gnss device
@@ -180,6 +197,7 @@ struct gnss {
 	bool stop;
 	int receiver_version_major;
 	int receiver_version_minor;
+	struct gnss_state *gnss_info;
 };
 
 struct gnss* gnss_init(const struct config *config, char *gnss_device_tty, struct gps_device_t *session, int fd_clock);

src/monitoring.c

@@ -565,7 +565,7 @@ static void json_add_oscillator_data(struct json_object *resp, struct monitoring
 }
 
 /**
- * @brief Add GNSS data to json response
+ * @brief Add GNSS data to json response. Must be called under gnss_info.lock locked
  *
  * @param resp
  * @param monitoring
@@ -627,10 +627,13 @@ static fd_status_t on_peer_ready_send(int sockfd, struct monitoring * monitoring
 
 	json_add_clock_data(json_resp, monitoring);
 	json_add_oscillator_data(json_resp, monitoring);
-	json_add_gnss_data(json_resp, monitoring);
 
 	pthread_mutex_unlock(&monitoring->mutex);
 
+	pthread_mutex_lock(&monitoring->gnss_info.lock);
+	json_add_gnss_data(json_resp, monitoring);
+	pthread_mutex_unlock(&monitoring->gnss_info.lock);
+
 	const char *resp = json_object_to_json_string(json_resp);
 	json_object_object_del(json_resp, "disciplining");
 	json_object_object_del(json_resp, "gnss");
@@ -728,6 +731,8 @@ struct monitoring* monitoring_init(const struct config *config, struct devices_p
 	monitoring->gnss_info.lsChange = -10;
 	monitoring->gnss_info.satellites_count = -1;
 	monitoring->gnss_info.survey_in_position_error = -1.0;
+	pthread_mutex_init(&monitoring->gnss_info.lock, NULL);
+
 	pthread_mutex_init(&monitoring->mutex, NULL);
 	pthread_cond_init(&monitoring->cond, NULL);
 

src/monitoring.h

@@ -33,17 +33,6 @@ enum monitoring_request {
 	REQUEST_RESET_UBLOX_SERIAL
 };
 
-struct gnss_state {
-	float survey_in_position_error;
-	int fix;
-	int satellites_count;
-	int leap_seconds;
-	int lsChange;
-	int8_t antenna_power;
-	int8_t antenna_status;
-	bool fixOk;
-};
-
 /**
  * @brief General structure for monitoring thread
  */

src/oscillatord.c

@@ -333,6 +333,9 @@ int main(int argc, char *argv[])
 		error(EXIT_FAILURE, errno, "Failed to listen to the receiver");
 		return -EINVAL;
 	}
+	if (monitoring) {
+		gnss->gnss_info = &monitoring->gnss_info;
+	}
 
 	if (disciplining_mode) {
 		/* Get disciplining parameters files exposed by driver */
@@ -612,7 +615,6 @@ int main(int argc, char *argv[])
 		if (monitoring_mode) {
 			/* Check for monitoring requests */
 			enum monitoring_request request;
-			struct gnss_state gnss_info = {};
 			struct od_monitoring disciplining = {
 				.clock_class = CLOCK_CLASS_UNCALIBRATED,
 				.status = WARMUP,
@@ -621,18 +623,6 @@ int main(int argc, char *argv[])
 				.convergence_progress = 0.00,
 				.ready_for_holdover = false,
 			};
-			if (gnss) {
-				pthread_mutex_lock(&gnss->mutex_data);
-				gnss_info.antenna_power = gnss->session->antenna_power;
-				gnss_info.antenna_status = gnss->session->antenna_status;
-				gnss_info.fix = gnss->session->fix;
-				gnss_info.fixOk = gnss->session->fixOk;
-				gnss_info.leap_seconds = gnss->session->context->leap_seconds;
-				gnss_info.lsChange = gnss->session->context->lsChange;
-				gnss_info.satellites_count = gnss->session->satellites_count;
-				gnss_info.survey_in_position_error = gnss->session->survey_in_position_error;
-				pthread_mutex_unlock(&gnss->mutex_data);
-			}
 			if (disciplining_mode) {
 				if(od_get_monitoring_data(od, &disciplining) != 0) {
 					log_warn("Could not get disciplining data");
@@ -650,15 +640,13 @@ int main(int argc, char *argv[])
 				oscillator_get_phase_error(oscillator, &osc_attr.phase_error);
 				oscillator_get_disciplining_status(oscillator, &disciplining);
 			}
+
 			pthread_mutex_lock(&monitoring->mutex);
 			monitoring->osc_attributes = osc_attr;
 			monitoring->ctrl_values = ctrl_values;
 			monitoring->disciplining = disciplining;
 			request = monitoring->request;
 			monitoring->request = REQUEST_NONE;
-			if (gnss)
-				monitoring->gnss_info = gnss_info;
-
 			pthread_mutex_unlock(&monitoring->mutex);
 
 			switch(request) {