address comments

Author: mgaido91

core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala

@@ -152,7 +152,6 @@ class HistoryServer(
     assert(serverInfo.isDefined, "HistoryServer must be bound before attaching SparkUIs")
     handlers.synchronized {
       ui.getHandlers.foreach(attachHandler)
-      addFilters(ui.getHandlers, conf)
     }
   }
 

core/src/main/scala/org/apache/spark/ui/JettyUtils.scala

@@ -263,7 +263,7 @@ private[spark] object JettyUtils extends Logging {
     filters.foreach {
       case filter : String =>
         if (!filter.isEmpty) {
-          logInfo("Adding filter: " + filter)
+          logInfo(s"Adding filter $filter to ${handlers.map(_.getContextPath).mkString(", ")}.")
           val holder : FilterHolder = new FilterHolder()
           holder.setClassName(filter)
           // Get any parameters for each filter

core/src/main/scala/org/apache/spark/ui/WebUI.scala

@@ -93,7 +93,12 @@ private[spark] abstract class WebUI(
   /** Attach a handler to this UI. */
   def attachHandler(handler: ServletContextHandler) {
     handlers += handler
-    serverInfo.foreach(_.addHandler(handler))
+    serverInfo.foreach { sInfo =>
+      sInfo.addHandler(handler)
+      // If the UI has already been bound, we need to add the filters to the newly attached
+      // handlers. Otherwise, they will be attached when binding.
+      addFilters(Seq(handler), conf)
+    }
   }
 
   /** Detach a handler from this UI. */

sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/ui/ThriftServerTab.scala

@@ -39,10 +39,6 @@ private[thriftserver] class ThriftServerTab(sparkContext: SparkContext)
   attachPage(new ThriftServerSessionPage(this))
   parent.attachTab(this)
 
-  // We need to add the filters to the handlers generated here since the SparkUI has been already
-  // started.
-  JettyUtils.addFilters(this.pages.flatMap(parent.handlersForPage), parent.conf)
-
   def detach() {
     getSparkUI(sparkContext).detachTab(this)
   }