[hue] Implementing "[discovery.upnp] Devices may apply a grace period"

bundles/org.openhab.binding.hue/README.md

@@ -373,3 +373,11 @@ if (receivedEvent.getEvent() == "1000.0")) {
     //do stuff
 }       
 ```
+
+### UPnP Discovery: Inbox 'Grace Period'
+
+The Hue Bridge can sometimes be late in sending its UPnP 'ssdp:alive' notifications even though it has not really gone offline.
+This means that the Hue Bridge could be repeatedly removed from, and (re)added to, the InBox.
+Which would lead to confusion in the UI, and repeated logger messages.
+To prevent this, the binding tells the OpenHAB core to wait for a further period of time ('grace period') before actually removing the Bridge from the Inbox.
+The 'grace period' has a default value of 50 seconds, but it can be fine tuned in the main UI via Settings | Bindings | Hue | Configure.

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/HueBindingConstants.java

@@ -83,6 +83,9 @@ public class HueBindingConstants {
     public static final String EVENT_DIMMER_SWITCH = "dimmer_switch_event";
     public static final String EVENT_TAP_SWITCH = "tap_switch_event";
 
+    // Binding configuration properties
+    public static final String REMOVAL_GRACE_PERIOD = "removalGracePeriod";
+
     // Bridge config properties
     public static final String HOST = "ipAddress";
     public static final String PORT = "port";

bundles/org.openhab.binding.hue/src/main/java/org/openhab/binding/hue/internal/discovery/HueBridgeDiscoveryParticipant.java

@@ -15,7 +15,9 @@
 import static org.openhab.binding.hue.internal.HueBindingConstants.*;
 import static org.openhab.core.thing.Thing.PROPERTY_SERIAL_NUMBER;
 
+import java.io.IOException;
 import java.util.Collections;
+import java.util.Dictionary;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
@@ -25,13 +27,20 @@
 import org.jupnp.model.meta.DeviceDetails;
 import org.jupnp.model.meta.ModelDetails;
 import org.jupnp.model.meta.RemoteDevice;
+import org.openhab.binding.hue.internal.HueBindingConstants;
 import org.openhab.core.config.discovery.DiscoveryResult;
 import org.openhab.core.config.discovery.DiscoveryResultBuilder;
 import org.openhab.core.config.discovery.upnp.UpnpDiscoveryParticipant;
 import org.openhab.core.config.discovery.upnp.internal.UpnpDiscoveryService;
 import org.openhab.core.thing.ThingTypeUID;
 import org.openhab.core.thing.ThingUID;
+import org.osgi.service.cm.Configuration;
+import org.osgi.service.cm.ConfigurationAdmin;
+import org.osgi.service.component.annotations.Activate;
 import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Reference;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * The {@link HueBridgeDiscoveryParticipant} is responsible for discovering new and
@@ -44,6 +53,18 @@
 @Component(service = UpnpDiscoveryParticipant.class)
 public class HueBridgeDiscoveryParticipant implements UpnpDiscoveryParticipant {
 
+    private final Logger logger = LoggerFactory.getLogger(HueBridgeDiscoveryParticipant.class);
+
+    // Hue bridges have maxAge 100 seconds, so set the default grace period to half of that
+    private long removalGracePeriodSeconds = 50;
+
+    private final ConfigurationAdmin configAdmin;
+
+    @Activate
+    public HueBridgeDiscoveryParticipant(final @Reference ConfigurationAdmin configAdmin) {
+        this.configAdmin = configAdmin;
+    }
+
     @Override
     public Set<ThingTypeUID> getSupportedThingTypeUIDs() {
         return Collections.singleton(THING_TYPE_BRIDGE);
@@ -92,4 +113,20 @@ public Set<ThingTypeUID> getSupportedThingTypeUIDs() {
         }
         return null;
     }
+
+    @Override
+    public long getRemovalGracePeriodSeconds(RemoteDevice device) {
+        try {
+            Configuration conf = configAdmin.getConfiguration("binding.hue");
+            Dictionary<String, @Nullable Object> properties = conf.getProperties();
+            Object property = properties.get(HueBindingConstants.REMOVAL_GRACE_PERIOD);
+            if (property != null) {
+                removalGracePeriodSeconds = Integer.valueOf(property.toString()).longValue();
+            }
+        } catch (IOException | IllegalStateException | NullPointerException | NumberFormatException e) {
+            // fall through to pre-initialised (default) value
+        }
+        logger.trace("getRemovalGracePeriodSeconds={}", removalGracePeriodSeconds);
+        return removalGracePeriodSeconds;
+    }
 }

bundles/org.openhab.binding.hue/src/main/resources/OH-INF/binding/binding.xml

@@ -3,8 +3,16 @@
 	xmlns:binding="https://openhab.org/schemas/binding/v1.0.0"
 	xsi:schemaLocation="https://openhab.org/schemas/binding/v1.0.0 https://openhab.org/schemas/binding-1.0.0.xsd">
 
-	<name>hue Binding</name>
-	<description>The hue Binding integrates the Philips hue system. It
-		allows to control hue bulbs.</description>
+	<name>Hue Binding</name>
+	<description>The Hue Binding integrates the Philips Hue system. It allows to control Hue bulbs.</description>
+
+	<config-description>
+		<parameter name="removalGracePeriod" type="integer" min="0" step="1" unit="s">
+			<label>Removal Grace Period</label>
+			<description>Extra grace period (seconds) that UPnP discovery shall wait before removing a lost Bridge from the
+				Inbox. Default is 50 seconds.</description>
+			<default>50</default>
+		</parameter>
+	</config-description>
 
 </binding:binding>