+bool
+FGInterpolateEnvironmentCtrl::bucket::lessThan(bucket *a, bucket *b)
+{
+ return (a->altitude_ft) < (b->altitude_ft);
+}
+
+\f
+////////////////////////////////////////////////////////////////////////
+// Implementation of FGMetarEnvironmentCtrl.
+////////////////////////////////////////////////////////////////////////
+
+FGMetarEnvironmentCtrl::FGMetarEnvironmentCtrl ()
+ : env( new FGInterpolateEnvironmentCtrl ),
+ metar_loaded( false ),
+ search_interval_sec( 60.0 ), // 1 minute
+ same_station_interval_sec( 900.0 ), // 15 minutes
+ search_elapsed( 9999.0 ),
+ fetch_elapsed( 9999.0 ),
+ last_apt( 0 ),
+ proxy_host( fgGetNode("/sim/presets/proxy/host", true) ),
+ proxy_port( fgGetNode("/sim/presets/proxy/port", true) ),
+ proxy_auth( fgGetNode("/sim/presets/proxy/authentication", true) ),
+ metar_max_age( fgGetNode("/environment/params/metar-max-age-min", true) ),
+
+ // Interpolation constant definitions.
+ EnvironmentUpdatePeriodSec( 0.2 ),
+ MaxWindChangeKtsSec( 0.2 ),
+ MaxVisChangePercentSec( 0.05 ),
+ MaxPressureChangeInHgSec( 0.0033 ),
+ MaxCloudAltitudeChangeFtSec( 20.0 ),
+ MaxCloudThicknessChangeFtSec( 50.0 ),
+ MaxCloudInterpolationHeightFt( 5000.0 ),
+ MaxCloudInterpolationDeltaFt( 4000.0 ),
+
+ _error_count( 0 ),
+ _stale_count( 0 ),
+ _dt( 0.0 ),
+ _error_dt( 0.0 )
+{
+#if defined(ENABLE_THREADS)
+ thread = new MetarThread(this);
+ thread->setProcessorAffinity(1);
+ thread->start();
+#endif // ENABLE_THREADS
+}
+
+FGMetarEnvironmentCtrl::~FGMetarEnvironmentCtrl ()
+{
+#if defined(ENABLE_THREADS)
+ thread_stop();
+#endif // ENABLE_THREADS
+
+ delete env;
+ env = NULL;
+}
+
+
+// use a "command" to set station temp at station elevation
+static void set_temp_at_altitude( float temp_degc, float altitude_ft ) {
+ SGPropertyNode args;
+ SGPropertyNode *node = args.getNode("temp-degc", 0, true);
+ node->setFloatValue( temp_degc );
+ node = args.getNode("altitude-ft", 0, true);
+ node->setFloatValue( altitude_ft );
+ globals->get_commands()->execute("set-outside-air-temp-degc", &args);
+}
+
+
+static void set_dewpoint_at_altitude( float dewpoint_degc, float altitude_ft ) {
+ SGPropertyNode args;
+ SGPropertyNode *node = args.getNode("dewpoint-degc", 0, true);
+ node->setFloatValue( dewpoint_degc );
+ node = args.getNode("altitude-ft", 0, true);
+ node->setFloatValue( altitude_ft );
+ globals->get_commands()->execute("set-dewpoint-temp-degc", &args);
+}
+
+
+void
+FGMetarEnvironmentCtrl::update_env_config ()
+{
+ double dir_from;
+ double dir_to;
+ double speed;
+ double gust;
+ double vis;
+ double pressure;
+ double temp;
+ double dewpoint;
+
+ // If we aren't in the METAR scenario, don't attempt to interpolate.
+ if (strcmp(fgGetString("/environment/weather-scenario", "METAR"), "METAR")) return;
+
+ if (metar_loaded) {
+ // Generate interpolated values between the METAR and the current
+ // configuration.
+
+ // Pick up the METAR wind values and convert them into a vector.
+ double metar[2];
+ double metar_speed = fgGetDouble("/environment/metar/base-wind-speed-kt");
+ double metar_heading = fgGetDouble("/environment/metar/base-wind-range-from");
+
+ metar[0] = metar_speed * sin((metar_heading / 180.0) * M_PI);
+ metar[1] = metar_speed * cos((metar_heading / 180.0) * M_PI);
+
+ // Convert the current wind values and convert them into a vector
+ double current[2];
+ double current_speed =
+ fgGetDouble("/environment/config/boundary/entry/wind-speed-kt");
+ double current_heading = fgGetDouble(
+ "/environment/config/boundary/entry/wind-from-heading-deg");
+
+ current[0] = current_speed * sin((current_heading / 180.0) * M_PI);
+ current[1] = current_speed * cos((current_heading / 180.0) * M_PI);
+
+ // Determine the maximum component-wise value that the wind can change.
+ // First we determine the fraction in the X and Y component, then
+ // factor by the maximum wind change.
+ double x = fabs(current[0] - metar[0]);
+ double y = fabs(current[1] - metar[1]);
+
+ // only interpolate if we have a difference
+ if (x + y > 0) {
+ double dx = x / (x + y);
+ double dy = 1 - dx;
+
+ double maxdx = dx * MaxWindChangeKtsSec;
+ double maxdy = dy * MaxWindChangeKtsSec;
+
+ // Interpolate each component separately.
+ current[0] = interpolate_val(current[0], metar[0], maxdx);
+ current[1] = interpolate_val(current[1], metar[1], maxdy);
+ }
+
+ // Now convert back to polar coordinates.
+ if ((current[0] == 0.0) && (current[1] == 0.0)) {
+ // Special case where there is no wind (otherwise atan2 barfs)
+ speed = 0.0;
+ dir_from = current_heading;
+
+ } else {
+ // Some real wind to convert back from. Work out the speed
+ // and direction value in degrees.
+ speed = sqrt((current[0] * current[0]) + (current[1] * current[1]));
+ dir_from = (atan2(current[0], current[1]) * 180.0 / M_PI);
+
+ // Normalize the direction.
+ if (dir_from < 0.0)
+ dir_from += 360.0;
+
+ SG_LOG( SG_GENERAL, SG_DEBUG, "Wind : " << dir_from << "@" << speed);
+ }
+
+ // Now handle the visibility. We convert both visibility values
+ // to X-values, then interpolate from there, then back to real values.
+ // The length_scale is fixed to 1000m, so the visibility changes by
+ // by MaxVisChangePercentSec or 1000m X MaxVisChangePercentSec,
+ // whichever is more.
+ double currentvis =
+ fgGetDouble("/environment/config/boundary/entry/visibility-m");
+ double metarvis = fgGetDouble("/environment/metar/min-visibility-m");
+ double currentxval = log(1000.0 + currentvis);
+ double metarxval = log(1000.0 + metarvis);
+
+ currentxval = interpolate_val(currentxval, metarxval, MaxVisChangePercentSec);
+
+ // Now convert back from an X-value to a straightforward visibility.
+ vis = exp(currentxval) - 1000.0;
+
+ pressure = interpolate_prop(
+ "/environment/config/boundary/entry/pressure-sea-level-inhg",
+ "/environment/metar/pressure-inhg",
+ MaxPressureChangeInHgSec);
+
+ dir_to = fgGetDouble("/environment/metar/base-wind-range-to");
+ gust = fgGetDouble("/environment/metar/gust-wind-speed-kt");
+ temp = fgGetDouble("/environment/metar/temperature-degc");
+ dewpoint = fgGetDouble("/environment/metar/dewpoint-degc");
+
+ // Set the cloud layers by interpolating over the METAR versions.
+ SGPropertyNode * clouds = fgGetNode("/environment/metar/clouds");
+
+ vector<SGPropertyNode_ptr> layers = clouds->getChildren("layer");
+ vector<SGPropertyNode_ptr>::const_iterator layer;
+ vector<SGPropertyNode_ptr>::const_iterator layers_end = layers.end();
+
+ const char *cl = "/environment/clouds/layer[%i]";
+ double aircraft_alt = fgGetDouble("/position/altitude-ft");
+ char s[128];
+ int i;
+
+ for (i = 0, layer = layers.begin(); layer != layers_end; ++layer, i++) {
+ double currentval;
+ double requiredval;
+
+ // In the case of clouds, we want to avoid writing if nothing has
+ // changed, as these properties are tied to the renderer and will
+ // cause the clouds to be updated, reseting the texture locations.
+
+ // We don't interpolate the coverage values as no-matter how we
+ // do it, it will be quite a sudden change of texture. Better to
+ // have a single change than four or five.
+ snprintf(s, 128, cl, i);
+ strncat(s, "/coverage", 128);
+ const char* coverage = (*layer)->getStringValue("coverage", "clear");
+ if (strncmp(fgGetString(s), coverage, 128) != 0)
+ fgSetString(s, coverage);
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/elevation-ft", 128);
+ double current_alt = fgGetDouble(s);
+ double required_alt = (*layer)->getDoubleValue("elevation-ft");
+
+ if (current_alt < -9000 || required_alt < -9000 ||
+ fabs(aircraft_alt - required_alt) > MaxCloudInterpolationHeightFt ||
+ fabs(current_alt - required_alt) > MaxCloudInterpolationDeltaFt) {
+ // We don't interpolate any layers that are
+ // - too far above us to be visible
+ // - too far below us to be visible
+ // - with too large a difference to make interpolation sensible
+ // - to or from -9999 (used as a placeholder)
+ // - any values that are too high above us,
+ snprintf(s, 128, cl, i);
+ strncat(s, "/elevation-ft", 128);
+ if (current_alt != required_alt)
+ fgSetDouble(s, required_alt);
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/thickness-ft", 128);
+ if (fgGetDouble(s) != (*layer)->getDoubleValue("thickness-ft"))
+ fgSetDouble(s, (*layer)->getDoubleValue("thickness-ft"));
+
+ } else {
+ // Interpolate the other values in the usual way
+ if (current_alt != required_alt) {
+ current_alt = interpolate_val(current_alt,
+ required_alt,
+ MaxCloudAltitudeChangeFtSec);
+ fgSetDouble(s, current_alt);
+ }
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/thickness-ft", 128);
+ currentval = fgGetDouble(s);
+ requiredval = (*layer)->getDoubleValue("thickness-ft");
+
+ if (currentval != requiredval) {
+ currentval = interpolate_val(currentval,
+ requiredval,
+ MaxCloudThicknessChangeFtSec);
+ fgSetDouble(s, currentval);
+ }
+ }
+ }
+
+ } else {
+ // We haven't already loaded a METAR, so apply it immediately.
+ dir_from = fgGetDouble("/environment/metar/base-wind-range-from");
+ dir_to = fgGetDouble("/environment/metar/base-wind-range-to");
+ speed = fgGetDouble("/environment/metar/base-wind-speed-kt");
+ gust = fgGetDouble("/environment/metar/gust-wind-speed-kt");
+ vis = fgGetDouble("/environment/metar/min-visibility-m");
+ pressure = fgGetDouble("/environment/metar/pressure-inhg");
+ temp = fgGetDouble("/environment/metar/temperature-degc");
+ dewpoint = fgGetDouble("/environment/metar/dewpoint-degc");
+
+ // Set the cloud layers by copying over the METAR versions.
+ SGPropertyNode * clouds = fgGetNode("/environment/metar/clouds", true);
+
+ vector<SGPropertyNode_ptr> layers = clouds->getChildren("layer");
+ vector<SGPropertyNode_ptr>::const_iterator layer;
+ vector<SGPropertyNode_ptr>::const_iterator layers_end = layers.end();
+
+ const char *cl = "/environment/clouds/layer[%i]";
+ char s[128];
+ int i;
+
+ for (i = 0, layer = layers.begin(); layer != layers_end; ++layer, i++) {
+ snprintf(s, 128, cl, i);
+ strncat(s, "/coverage", 128);
+ fgSetString(s, (*layer)->getStringValue("coverage", "clear"));
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/elevation-ft", 128);
+ fgSetDouble(s, (*layer)->getDoubleValue("elevation-ft"));
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/thickness-ft", 128);
+ fgSetDouble(s, (*layer)->getDoubleValue("thickness-ft"));
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/span-m", 128);
+ fgSetDouble(s, 40000.0);
+ }
+
+ // Force an update of the 3D clouds
+ fgSetDouble("/environment/rebuild-layers", 1.0);
+ }
+
+ fgSetupWind(dir_from, dir_to, speed, gust);
+ fgDefaultWeatherValue("visibility-m", vis);
+ set_temp_at_altitude(temp, station_elevation_ft);
+ set_dewpoint_at_altitude(dewpoint, station_elevation_ft);
+ fgDefaultWeatherValue("pressure-sea-level-inhg", pressure);
+
+ // We've now successfully loaded a METAR into the configuration
+ metar_loaded = true;
+}
+
+double FGMetarEnvironmentCtrl::interpolate_prop(const char * currentname,
+ const char * requiredname,
+ double dt)
+{
+ double currentval = fgGetDouble(currentname);
+ double requiredval = fgGetDouble(requiredname);
+ return interpolate_val(currentval, requiredval, dt);
+}
+
+double FGMetarEnvironmentCtrl::interpolate_val(double currentval,
+ double requiredval,
+ double dt)
+{
+ double dval = EnvironmentUpdatePeriodSec * dt;
+
+ if (fabs(currentval - requiredval) < dval) return requiredval;
+ if (currentval < requiredval) return (currentval + dval);
+ if (currentval > requiredval) return (currentval - dval);
+ return requiredval;
+}
+
+void
+FGMetarEnvironmentCtrl::init ()
+{
+ SGGeod pos = SGGeod::fromDeg(
+ fgGetDouble("/position/longitude-deg", true),
+ fgGetDouble( "/position/latitude-deg", true));
+
+ metar_loaded = false;
+ bool found_metar = false;
+ long max_age = metar_max_age->getLongValue();
+ // Don't check max age during init so that we don't loop over a lot
+ // of airports metar if there is a problem.
+ // The update() calls will find a correct metar if things went wrong here
+ metar_max_age->setLongValue(0);
+
+ while ( !found_metar && (_error_count < 3) ) {
+ AirportWithMetar filter;
+ FGAirport* a = FGAirport::findClosest(pos, 10000.0, &filter);
+ if (!a) {
+ break;
+ }
+
+ FGMetarResult result = fetch_data(a);
+ if ( result.m != NULL ) {
+ SG_LOG( SG_GENERAL, SG_INFO, "closest station w/ metar = "
+ << a->ident());
+ last_apt = a;
+ search_elapsed = 0.0;
+ fetch_elapsed = 0.0;
+ update_metar_properties( result.m );
+ update_env_config();
+ env->init();
+ found_metar = true;
+ } else {
+ // mark as no metar so it doesn't show up in subsequent
+ // searches.
+ SG_LOG( SG_GENERAL, SG_INFO, "no metar at metar = " << a->ident() );
+ a->setMetar(false);
+ }
+ } // of airprot-with-metar search iteration
+
+ metar_max_age->setLongValue(max_age);
+}
+
+void
+FGMetarEnvironmentCtrl::reinit ()
+{
+ _error_count = 0;
+ _error_dt = 0.0;
+ metar_loaded = false;
+
+ env->reinit();
+}
+
+void
+FGMetarEnvironmentCtrl::update(double delta_time_sec)
+{
+ _dt += delta_time_sec;
+ if (_error_count >= 3)
+ return;
+
+ FGMetarResult result;
+
+ static const SGPropertyNode *longitude
+ = fgGetNode( "/position/longitude-deg", true );
+ static const SGPropertyNode *latitude
+ = fgGetNode( "/position/latitude-deg", true );
+ SGGeod pos = SGGeod::fromDeg(longitude->getDoubleValue(),
+ latitude->getDoubleValue());
+
+ search_elapsed += delta_time_sec;
+ fetch_elapsed += delta_time_sec;
+ interpolate_elapsed += delta_time_sec;
+
+ // if time for a new search request, push it onto the request
+ // queue
+ if ( search_elapsed > search_interval_sec ) {
+ AirportWithMetar filter;
+ FGAirport* a = FGAirport::findClosest(pos, 10000.0, &filter);
+ if (a) {
+ if ( !last_apt || last_apt->ident() != a->ident()
+ || fetch_elapsed > same_station_interval_sec )
+ {
+ SG_LOG( SG_GENERAL, SG_INFO, "closest station w/ metar = "
+ << a->ident());
+ request_queue.push(a);
+ last_apt = a;
+ search_elapsed = 0.0;
+ fetch_elapsed = 0.0;
+ } else {
+ search_elapsed = 0.0;
+ SG_LOG( SG_GENERAL, SG_INFO, "same station, waiting = "
+ << same_station_interval_sec - fetch_elapsed );
+ }
+
+ } else {
+ SG_LOG( SG_GENERAL, SG_WARN,
+ "Unable to find any airports with metar" );
+ }
+ } else if ( interpolate_elapsed > EnvironmentUpdatePeriodSec ) {
+ // Interpolate the current configuration closer to the actual METAR
+ update_env_config();
+ env->reinit();
+ interpolate_elapsed = 0.0;
+ }
+
+#if !defined(ENABLE_THREADS)
+ // No loader thread running so manually fetch the data
+ FGAirport* apt = NULL;
+ while ( !request_queue.empty() ) {
+ apt = request_queue.front();
+ request_queue.pop();
+ }
+
+ if (apt) {
+ SG_LOG( SG_GENERAL, SG_INFO, "inline fetching = " << apt->ident() );
+ result = fetch_data( apt );
+ result_queue.push( result );
+ }
+#endif // ENABLE_THREADS
+
+ // process any results from the loader.
+ while ( !result_queue.empty() ) {
+ result = result_queue.front();
+ result_queue.pop();
+ if ( result.m != NULL ) {
+ update_metar_properties( result.m );
+ delete result.m;
+ update_env_config();
+ env->reinit();
+ } else {
+ // mark as no metar so it doesn't show up in subsequent
+ // searches, and signal an immediate re-search.
+ SG_LOG( SG_GENERAL, SG_WARN,
+ "no metar at station = " << result.airport->ident() );
+ result.airport->setMetar(false);
+ search_elapsed = 9999.0;
+ }
+ }
+
+ env->update(delta_time_sec);
+}
+
+
+void
+FGMetarEnvironmentCtrl::setEnvironment (FGEnvironment * environment)
+{
+ env->setEnvironment(environment);
+}
+
+FGMetarResult
+FGMetarEnvironmentCtrl::fetch_data(FGAirport* apt)
+{
+ FGMetarResult result;
+ result.airport = apt;
+
+ // if the last error was more than three seconds ago,
+ // then pretent nothing happened.
+ if (_error_dt < 3) {
+ _error_dt += _dt;
+
+ } else {
+ _error_dt = 0.0;
+ _error_count = 0;
+ }
+
+ station_elevation_ft = apt->getElevation();
+
+ // fetch current metar data
+ try {
+ string host = proxy_host->getStringValue();
+ string auth = proxy_auth->getStringValue();
+ string port = proxy_port->getStringValue();
+ result.m = new FGMetar( apt->ident(), host, port, auth);
+
+ long max_age = metar_max_age->getLongValue();
+ long age = result.m->getAge_min();
+ if (max_age && age > max_age) {
+ SG_LOG( SG_GENERAL, SG_WARN, "METAR data too old (" << age << " min).");
+ delete result.m;
+ result.m = NULL;
+
+ if (++_stale_count > 10) {
+ _error_count = 1000;
+ throw sg_io_exception("More than 10 stale METAR messages in a row."
+ " Check your system time!");
+ }
+ } else
+ _stale_count = 0;
+
+ } catch (const sg_io_exception& e) {
+ SG_LOG( SG_GENERAL, SG_WARN, "Error fetching live weather data: "
+ << e.getFormattedMessage().c_str() );
+#if defined(ENABLE_THREADS)
+ if (_error_count++ >= 3) {
+ SG_LOG( SG_GENERAL, SG_WARN, "Stop fetching data permanently.");
+ thread_stop();
+ }
+#endif
+
+ result.m = NULL;
+ }
+
+ _dt = 0;
+
+ return result;
+}
+
+
+void
+FGMetarEnvironmentCtrl::update_metar_properties( const FGMetar *m )
+{
+ int i;
+ double d;
+ char s[128];
+
+ fgSetString("/environment/metar/real-metar", m->getData());
+ // don't update with real weather when we use a custom weather scenario
+ const char *current_scenario = fgGetString("/environment/weather-scenario", "METAR");
+ if( strcmp(current_scenario, "METAR") && strcmp(current_scenario, "none"))
+ return;
+ fgSetString("/environment/metar/last-metar", m->getData());
+ fgSetString("/environment/metar/station-id", m->getId());
+ fgSetDouble("/environment/metar/min-visibility-m",
+ m->getMinVisibility().getVisibility_m() );
+ fgSetDouble("/environment/metar/max-visibility-m",
+ m->getMaxVisibility().getVisibility_m() );
+
+ const SGMetarVisibility *dirvis = m->getDirVisibility();
+ for (i = 0; i < 8; i++, dirvis++) {
+ const char *min = "/environment/metar/visibility[%d]/min-m";
+ const char *max = "/environment/metar/visibility[%d]/max-m";
+
+ d = dirvis->getVisibility_m();
+
+ snprintf(s, 128, min, i);
+ fgSetDouble(s, d);
+ snprintf(s, 128, max, i);
+ fgSetDouble(s, d);
+ }
+
+ fgSetInt("/environment/metar/base-wind-range-from",
+ m->getWindRangeFrom() );
+ fgSetInt("/environment/metar/base-wind-range-to",
+ m->getWindRangeTo() );
+ fgSetDouble("/environment/metar/base-wind-speed-kt",
+ m->getWindSpeed_kt() );
+ fgSetDouble("/environment/metar/gust-wind-speed-kt",
+ m->getGustSpeed_kt() );
+ fgSetDouble("/environment/metar/temperature-degc",
+ m->getTemperature_C() );
+ fgSetDouble("/environment/metar/dewpoint-degc",
+ m->getDewpoint_C() );
+ fgSetDouble("/environment/metar/rel-humidity-norm",
+ m->getRelHumidity() );
+ fgSetDouble("/environment/metar/pressure-inhg",
+ m->getPressure_inHg() );
+
+ vector<SGMetarCloud> cv = m->getClouds();
+ vector<SGMetarCloud>::const_iterator cloud;
+
+ const char *cl = "/environment/metar/clouds/layer[%i]";
+ for (i = 0, cloud = cv.begin(); cloud != cv.end(); cloud++, i++) {
+ const char *coverage_string[5] =
+ { "clear", "few", "scattered", "broken", "overcast" };
+ const double thickness[5] = { 0, 65, 600,750, 1000};
+ int q;
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/coverage", 128);
+ q = cloud->getCoverage();
+ fgSetString(s, coverage_string[q] );
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/elevation-ft", 128);
+ fgSetDouble(s, cloud->getAltitude_ft() + station_elevation_ft);
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/thickness-ft", 128);
+ fgSetDouble(s, thickness[q]);
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/span-m", 128);
+ fgSetDouble(s, 40000.0);
+ }
+
+ for (; i < FGEnvironmentMgr::MAX_CLOUD_LAYERS; i++) {
+ snprintf(s, 128, cl, i);
+ strncat(s, "/coverage", 128);
+ fgSetString(s, "clear");
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/elevation-ft", 128);
+ fgSetDouble(s, -9999);
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/thickness-ft", 128);
+ fgSetDouble(s, 0);
+
+ snprintf(s, 128, cl, i);
+ strncat(s, "/span-m", 128);
+ fgSetDouble(s, 40000.0);
+ }
+
+ fgSetDouble("/environment/metar/rain-norm", m->getRain());
+ fgSetDouble("/environment/metar/hail-norm", m->getHail());
+ fgSetDouble("/environment/metar/snow-norm", m->getSnow());
+ fgSetBool("/environment/metar/snow-cover", m->getSnowCover());
+}
+
+
+#if defined(ENABLE_THREADS)
+void
+FGMetarEnvironmentCtrl::thread_stop()
+{
+ request_queue.push(NULL); // ask thread to terminate
+ thread->join();
+}
+
+void
+FGMetarEnvironmentCtrl::MetarThread::run()
+{
+ while ( true )
+ {
+ FGAirport* apt = fetcher->request_queue.pop();
+ if (!apt)
+ return;
+ SG_LOG( SG_GENERAL, SG_INFO, "Thread: fetch metar data = " << apt->ident() );
+ FGMetarResult result = fetcher->fetch_data( apt );
+ fetcher->result_queue.push( result );
+ }
+}
+#endif // ENABLE_THREADS
+