[mqtt] avoid duplicates in listenerList; only (un)register topicd if …

…listener in listenerList Signed-off-by: Andrew Fiddian-Green <software@whitebear.ch>
andrewfg · Apr 25, 2021 · c0d00c9 · c0d00c9
1 parent 6d4b890
commit c0d00c9
Showing 1 changed file with 10 additions and 9 deletions.
diff --git a/...inding.mqtt/src/main/java/org/openhab/binding/mqtt/internal/MqttBrokerHandlerFactory.java b/...inding.mqtt/src/main/java/org/openhab/binding/mqtt/internal/MqttBrokerHandlerFactory.java
@@ -12,10 +12,9 @@
  */
 package org.openhab.binding.mqtt.internal;
 
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
-import java.util.List;
+import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.WeakHashMap;
@@ -58,7 +57,7 @@ public class MqttBrokerHandlerFactory extends BaseThingHandlerFactory implements
             .of(MqttBindingConstants.BRIDGE_TYPE_SYSTEMBROKER, MqttBindingConstants.BRIDGE_TYPE_BROKER)
             .collect(Collectors.toSet());
     private final Logger logger = LoggerFactory.getLogger(MqttBrokerHandlerFactory.class);
-    protected final Map<String, List<MQTTTopicDiscoveryParticipant>> discoveryTopics = new HashMap<>();
+    protected final Map<String, Set<MQTTTopicDiscoveryParticipant>> discoveryTopics = new HashMap<>();
     protected final Set<AbstractBrokerHandler> handlers = Collections
             .synchronizedSet(Collections.newSetFromMap(new WeakHashMap<>()));
 
@@ -113,11 +112,12 @@ protected void createdHandler(AbstractBrokerHandler handler) {
      * a MQTT topic that is registered on all available broker connections.
      */
     @Override
+    @SuppressWarnings("null")
     public void subscribe(MQTTTopicDiscoveryParticipant listener, String topic) {
-        List<MQTTTopicDiscoveryParticipant> listenerList = discoveryTopics.computeIfAbsent(topic,
-                t -> new ArrayList<>());
-        listenerList.add(listener);
-        handlers.forEach(broker -> broker.registerDiscoveryListener(listener, topic));
+        Set<MQTTTopicDiscoveryParticipant> listenerList = discoveryTopics.computeIfAbsent(topic, t -> new HashSet<>());
+        if (listenerList.add(listener)) {
+            handlers.forEach(broker -> broker.registerDiscoveryListener(listener, topic));
+        }
     }
 
     /**
@@ -127,8 +127,9 @@ public void subscribe(MQTTTopicDiscoveryParticipant listener, String topic) {
     @SuppressWarnings("null")
     public void unsubscribe(MQTTTopicDiscoveryParticipant listener) {
         discoveryTopics.forEach((topic, listenerList) -> {
-            listenerList.remove(listener);
-            handlers.forEach(broker -> broker.unregisterDiscoveryListener(listener, topic));
+            if (listenerList.remove(listener)) {
+                handlers.forEach(broker -> broker.unregisterDiscoveryListener(listener, topic));
+            }
         });
     }