]> git.mxchange.org Git - flightgear.git/blobdiff - src/Environment/environment_ctrl.cxx
Development for two new features:
[flightgear.git] / src / Environment / environment_ctrl.cxx
index ebfc97e6dfec678f379ce149215059f7bb436dda..cf9c6505faefd68dff5f2cdfabb23f86666f19d2 100644 (file)
 #  include "config.h"
 #endif
 
-#include <simgear/debug/logstream.hxx>
-
-#include <stdlib.h>
 #include <algorithm>
 
+#include <simgear/debug/logstream.hxx>
 #include <simgear/structure/commands.hxx>
 #include <simgear/structure/exception.hxx>
 
 #include <Main/fg_props.hxx>
 #include <Main/util.hxx>
 
+#include "Environment/fgmetar.hxx"
 #include "environment_mgr.hxx"
 #include "environment_ctrl.hxx"
 
-SG_USING_STD(sort);
-
+using std::sort;
 
+class AirportWithMetar : public FGAirport::AirportFilter
+{
+public:
+  virtual bool passAirport(FGAirport* aApt) const
+  {
+    return aApt->getMetar();
+  }
+};
 \f
 ////////////////////////////////////////////////////////////////////////
 // Implementation of FGEnvironmentCtrl abstract base class.
@@ -231,7 +237,7 @@ FGInterpolateEnvironmentCtrl::read_table (const SGPropertyNode * node,
             table.push_back(b);
         }
     }
-    sort(table.begin(), table.end());
+    sort(table.begin(), table.end(), bucket::lessThan);
 }
 
 void
@@ -312,6 +318,11 @@ FGInterpolateEnvironmentCtrl::bucket::operator< (const bucket &b) const
     return (altitude_ft < b.altitude_ft);
 }
 
+bool
+FGInterpolateEnvironmentCtrl::bucket::lessThan(bucket *a, bucket *b)
+{
+    return (a->altitude_ft) < (b->altitude_ft);
+}
 
 \f
 ////////////////////////////////////////////////////////////////////////
@@ -320,32 +331,43 @@ FGInterpolateEnvironmentCtrl::bucket::operator< (const bucket &b) const
 
 FGMetarEnvironmentCtrl::FGMetarEnvironmentCtrl ()
     : env( new FGInterpolateEnvironmentCtrl ),
-      _icao( "" ),
+      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 ),
-      last_apt(0)
+      _error_dt( 0.0 )
 {
 #if defined(ENABLE_THREADS)
     thread = new MetarThread(this);
-    thread->start( 1 );
+    thread->setProcessorAffinity(1);
+    thread->start();
 #endif // ENABLE_THREADS
 }
 
 FGMetarEnvironmentCtrl::~FGMetarEnvironmentCtrl ()
 {
 #if defined(ENABLE_THREADS)
-   thread->cancel();
-   thread->join();
+   thread_stop();
 #endif // ENABLE_THREADS
 
    delete env;
@@ -377,29 +399,263 @@ static void set_dewpoint_at_altitude( float dewpoint_degc, float altitude_ft ) {
 void
 FGMetarEnvironmentCtrl::update_env_config ()
 {
-    fgSetupWind( fgGetDouble("/environment/metar/base-wind-range-from"),
-                 fgGetDouble("/environment/metar/base-wind-range-to"),
-                 fgGetDouble("/environment/metar/base-wind-speed-kt"),
-                 fgGetDouble("/environment/metar/gust-wind-speed-kt") );
+    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;
 
-    fgDefaultWeatherValue( "visibility-m",
-                           fgGetDouble("/environment/metar/min-visibility-m") );
-    set_temp_at_altitude( fgGetDouble("/environment/metar/temperature-degc"),
-                          station_elevation_ft );
-    set_dewpoint_at_altitude( fgGetDouble("/environment/metar/dewpoint-degc"),
-                              station_elevation_ft );
-    fgDefaultWeatherValue( "pressure-sea-level-inhg",
-                           fgGetDouble("/environment/metar/pressure-inhg") );
+            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 ()
 {
-    const SGPropertyNode *longitude
-        = fgGetNode( "/position/longitude-deg", true );
-    const SGPropertyNode *latitude
-        = fgGetNode( "/position/latitude-deg", true );
+    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
@@ -408,32 +664,31 @@ FGMetarEnvironmentCtrl::init ()
     metar_max_age->setLongValue(0);
 
     while ( !found_metar && (_error_count < 3) ) {
-        const FGAirport* a = globals->get_airports()
-                   ->search( longitude->getDoubleValue(),
-                             latitude->getDoubleValue(),
-                             true );
-        if ( a ) {  
-            FGMetarResult result = fetch_data( a->getId() );
-            if ( result.m != NULL ) {
-                SG_LOG( SG_GENERAL, SG_INFO, "closest station w/ metar = "
-                        << a->getId());
-                last_apt = a;
-                _icao = a->getId();
-                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->getId() );
-                globals->get_airports()->no_metar( a->getId() );
-            }
+        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);
 }
 
@@ -442,10 +697,7 @@ FGMetarEnvironmentCtrl::reinit ()
 {
     _error_count = 0;
     _error_dt = 0.0;
-
-#if 0
-    update_env_config();
-#endif
+    metar_loaded = false;
 
     env->reinit();
 }
@@ -453,7 +705,6 @@ FGMetarEnvironmentCtrl::reinit ()
 void
 FGMetarEnvironmentCtrl::update(double delta_time_sec)
 {
-
     _dt += delta_time_sec;
     if (_error_count >= 3)
        return;
@@ -464,25 +715,26 @@ FGMetarEnvironmentCtrl::update(double delta_time_sec)
         = 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 ) {
-        const FGAirport* a = globals->get_airports()
-                   ->search( longitude->getDoubleValue(),
-                             latitude->getDoubleValue(),
-                             true );
-        if ( a ) {
-            if ( !last_apt || last_apt->getId() != a->getId()
+        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->getId());
-                request_queue.push( a->getId() );
+                        << a->ident());
+                request_queue.push(a);
                 last_apt = a;
-                _icao = a->getId();
                 search_elapsed = 0.0;
                 fetch_elapsed = 0.0;
             } else {
@@ -490,23 +742,29 @@ FGMetarEnvironmentCtrl::update(double delta_time_sec)
                 SG_LOG( SG_GENERAL, SG_INFO, "same station, waiting = "
                         << same_station_interval_sec - fetch_elapsed );
             }
+
         } else {
-            SG_LOG( SG_GENERAL, SG_WARN,
+          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
-    string id = "";
+    FGAirport* apt = NULL;
     while ( !request_queue.empty() ) {
-        id = request_queue.front();
+        apt = request_queue.front();
         request_queue.pop();
     }
 
-    if ( !id.empty() ) {
-        SG_LOG( SG_GENERAL, SG_INFO, "inline fetching = " << id );
-        result = fetch_data( id );
+    if (apt) {
+        SG_LOG( SG_GENERAL, SG_INFO, "inline fetching = " << apt->ident() );
+        result = fetch_data( apt );
         result_queue.push( result );
     }
 #endif // ENABLE_THREADS
@@ -524,8 +782,8 @@ FGMetarEnvironmentCtrl::update(double delta_time_sec)
             // 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.icao );
-            globals->get_airports()->no_metar( result.icao );
+                    "no metar at station = " << result.airport->ident() );
+            result.airport->setMetar(false);
             search_elapsed = 9999.0;
         }
     }
@@ -541,10 +799,10 @@ FGMetarEnvironmentCtrl::setEnvironment (FGEnvironment * environment)
 }
 
 FGMetarResult
-FGMetarEnvironmentCtrl::fetch_data( const string &icao )
+FGMetarEnvironmentCtrl::fetch_data(FGAirport* apt)
 {
     FGMetarResult result;
-    result.icao = icao;
+    result.airport = apt;
 
     // if the last error was more than three seconds ago,
     // then pretent nothing happened.
@@ -556,18 +814,14 @@ FGMetarEnvironmentCtrl::fetch_data( const string &icao )
         _error_count = 0;
     }
 
-    // fetch station elevation if exists
-    const FGAirport* a = globals->get_airports()->search( icao );
-    if ( a ) {
-        station_elevation_ft = a->getElevation();
-    }
+    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( icao, host, port, auth);
+        result.m = new FGMetar( apt->ident(), host, port, auth);
 
         long max_age = metar_max_age->getLongValue();
         long age = result.m->getAge_min();
@@ -590,8 +844,7 @@ FGMetarEnvironmentCtrl::fetch_data( const string &icao )
 #if defined(ENABLE_THREADS)
         if (_error_count++ >= 3) {
            SG_LOG( SG_GENERAL, SG_WARN, "Stop fetching data permanently.");
-           thread->cancel();
-           thread->join();
+           thread_stop();
         }
 #endif
 
@@ -656,7 +909,7 @@ FGMetarEnvironmentCtrl::update_metar_properties( const FGMetar *m )
     vector<SGMetarCloud> cv = m->getClouds();
     vector<SGMetarCloud>::const_iterator cloud;
 
-    const char *cl = "/environment/clouds/layer[%i]";
+    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" };
@@ -707,36 +960,25 @@ FGMetarEnvironmentCtrl::update_metar_properties( const FGMetar *m )
 
 
 #if defined(ENABLE_THREADS)
-/**
- * Ensure mutex is unlocked.
- */
 void
-metar_cleanup_handler( void* arg )
+FGMetarEnvironmentCtrl::thread_stop()
 {
-    FGMetarEnvironmentCtrl* fetcher = (FGMetarEnvironmentCtrl*) arg;
-    fetcher->mutex.unlock();
+    request_queue.push(NULL);  // ask thread to terminate
+    thread->join();
 }
 
-/**
- *
- */
 void
 FGMetarEnvironmentCtrl::MetarThread::run()
 {
-    pthread_cleanup_push( metar_cleanup_handler, fetcher );
     while ( true )
     {
-        set_cancel( SGThread::CANCEL_DISABLE );
-
-        string icao = fetcher->request_queue.pop();
-        SG_LOG( SG_GENERAL, SG_INFO, "Thread: fetch metar data = " << icao );
-        FGMetarResult result = fetcher->fetch_data( icao );
-
-        set_cancel( SGThread::CANCEL_DEFERRED );
-
+        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 );
     }
-    pthread_cleanup_pop(1);
 }
 #endif // ENABLE_THREADS