Implement proper check on whether a GW has a location and add a gateway cache.

workspace/ttnhabbridge/src/main/java/nl/sikken/bertrik/TtnHabBridge.java

@@ -13,12 +13,12 @@ import org.slf4j.LoggerFactory;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 
+import nl.sikken.bertrik.hab.ExpiringCache;
 import nl.sikken.bertrik.hab.PayloadDecoder;
 import nl.sikken.bertrik.hab.Sentence;
 import nl.sikken.bertrik.hab.habitat.HabReceiver;
 import nl.sikken.bertrik.hab.habitat.HabitatUploader;
 import nl.sikken.bertrik.hab.habitat.IHabitatRestApi;
-import nl.sikken.bertrik.hab.habitat.Location;
 import nl.sikken.bertrik.hab.ttn.TtnListener;
 import nl.sikken.bertrik.hab.ttn.TtnMessage;
 import nl.sikken.bertrik.hab.ttn.TtnMessageGateway;
@@ -38,6 +38,7 @@ public final class TtnHabBridge {
     private final HabitatUploader habUploader;
     private final PayloadDecoder decoder;
     private final ObjectMapper mapper;
+    private final ExpiringCache gwCache;
 
     /**
      * Main application entry point.
@@ -67,6 +68,7 @@ public final class TtnHabBridge {
         this.habUploader = new HabitatUploader(restApi);
         this.mapper = new ObjectMapper();
         this.decoder = new PayloadDecoder();
+        this.gwCache = new ExpiringCache(600);
     }
 
     /**
@@ -98,20 +100,16 @@ public final class TtnHabBridge {
             final String line = sentence.format();
             
             // create listeners
+            final Date now = new Date();
             final List<HabReceiver> receivers = new ArrayList<>();
             for (TtnMessageGateway gw : message.getMetaData().getMqttGateways()) {
-            	final Double latitude = gw.getLatitude();
-            	final Double longitude = gw.getLongitude();
-            	final Double altitude = gw.getAltitude();
-            	if ((latitude != null) && (longitude != null) && (altitude != null)) {
-	                final HabReceiver receiver = new HabReceiver(gw.getId(),
-	                        new Location(gw.getLatitude(), gw.getLongitude(), gw.getAltitude()));
-	                receivers.add(receiver);
-            	}
+                if (gw.hasLocation() && gwCache.add(gw.getId(), now)) {
+                    final HabReceiver receiver = new HabReceiver(gw.getId(), gw.getLocation());
+                    receivers.add(receiver);
+                }
             }
 
             // send listener data
-            final Date now = new Date();
             for (HabReceiver receiver : receivers) {
                 habUploader.scheduleListenerDataUpload(receiver, now);
             }
@@ -134,6 +132,7 @@ public final class TtnHabBridge {
         LOG.info("Stopping TTN HAB bridge application");
         ttnListener.stop();
         habUploader.stop();
+        LOG.info("Stopped TTN HAB bridge application");
     }
 
     private static ITtnHabBridgeConfig readConfig(File file) throws IOException {

workspace/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/ExpiringCache.java

@@ -0,0 +1,51 @@
+package nl.sikken.bertrik.hab;
+
+import java.util.Date;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Simple expiring cache.
+ */
+public final class ExpiringCache {
+
+    private final Map<String, Date> map = new ConcurrentHashMap<String, Date>();
+    private final long expiryTimeMs;
+
+    /**
+     * Constructor.
+     * 
+     * @param expiryTimeSec the expiry time (seconds)
+     */
+    public ExpiringCache(int expiryTimeSec) {
+        this.expiryTimeMs = expiryTimeSec * 1000L;
+    }
+    
+    /**
+     * Adds the item to the cache. 
+     * 
+     * @param id the id of the item
+     * @param date the date
+     * @return true if the item was newly added
+     */
+    public boolean add(String id, Date date) {
+        cleanUp(date);
+        final Date previous = map.putIfAbsent(id, date);
+        return previous == null;
+    }
+
+    /**
+     * Cleans up the cache, removing all items from before the current date minus the expiration timeout.
+     * 
+     * @param now the current date
+     */
+    private void cleanUp(Date now) {
+        final Date limit = new Date(now.getTime() - expiryTimeMs);
+        map.forEach((k,v) -> {
+            if (v.before(limit)) {
+                map.remove(k, v);
+            }
+        });
+    }
+    
+}

workspace/ttnhabbridge/src/main/java/nl/sikken/bertrik/hab/ttn/TtnMessageGateway.java

@@ -1,8 +1,11 @@
 package nl.sikken.bertrik.hab.ttn;
 
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
+import nl.sikken.bertrik.hab.habitat.Location;
+
 /**
  * Representation of a gateway in the metadata of the TTN MQTT JSON format.
  */
@@ -27,6 +30,30 @@ public final class TtnMessageGateway {
     @JsonProperty("altitude")
     private Double altitude;
 
+    private TtnMessageGateway() {
+        // jackson constructor
+    }
+    
+    /**
+     * Constructor.
+     * 
+     * @param id the id (name)
+     * @param trusted whether it is trusted
+     * @param time the time
+     * @param lat the latitude (degrees)
+     * @param lon the longitude (degrees)
+     * @param alt the altitude (meters)
+     */
+    public TtnMessageGateway(String id, boolean trusted, String time, Double lat, Double lon, Double alt) {
+        this();
+        this.id = id;
+        this.trusted = trusted;
+        this.time = time;
+        this.latitude = lat;
+        this.longitude = lon;
+        this.altitude = alt;
+    }
+    
     public String getId() {
         return id;
     }
@@ -51,4 +78,14 @@ public final class TtnMessageGateway {
         return altitude;
     }
     
+    @JsonIgnore
+    public boolean hasLocation() {
+        return latitude != null && longitude != null && altitude != null;
+    }
+    
+    @JsonIgnore
+    public Location getLocation() {
+        return new Location(latitude, longitude, altitude);
+    }
+    
 }