fixes #389: Slow Leader Election (#390)

* fixes #389: Slow Leader Election

* added comment

* Update StreamsTransactionEventHandler.kt

Author: conker84

producer/src/main/kotlin/streams/StreamsTransactionEventHandler.kt

@@ -23,8 +23,12 @@ class StreamsTransactionEventHandler(private val router: StreamsEventRouter,
 
     private val nodeAll = configuration.nodeRouting.any { it.labels.isEmpty() }
     private val relAll = configuration.relRouting.any { it.name.isNullOrBlank() }
-
-    private val hostName = InetAddress.getLocalHost().hostName
+  
+    // As getting host name in some network configuration can be expensive
+    // this can lead to slowness in the start-up process (i.e. slowing the leader 
+    // election in case of a Causal Cluster). We define it a `lazy` value
+    // computing it at the first invocation
+    private val hostName by lazy { InetAddress.getLocalHost().hostName }
 
     /**
      * Wrap the payload into a StreamsTransactionEvent for the eventId
@@ -334,4 +338,4 @@ class StreamsTransactionEventHandler(private val router: StreamsEventRouter,
 
         return builder.build()
     }
-}
+}