[SPARK-24851] : Addressing Reviews August 9

Author: pgandhi

core/src/main/scala/org/apache/spark/status/AppStatusStore.scala

@@ -113,9 +113,9 @@ private[spark] class AppStatusStore(
   }
 
   def stageAttempt(stageId: Int, stageAttemptId: Int,
-    details: Boolean = false): (v1.StageData, Seq[Int]) = {
+      details: Boolean = false): (v1.StageData, Seq[Int]) = {
     val stageKey = Array(stageId, stageAttemptId)
-    val stageDataWrapper: StageDataWrapper = store.read(classOf[StageDataWrapper], stageKey)
+    val stageDataWrapper = store.read(classOf[StageDataWrapper], stageKey)
     val stage = if (details) stageWithDetails(stageDataWrapper.info) else stageDataWrapper.info
     val jobIds = stageDataWrapper.jobIds
     (stage, jobIds.toSeq)

core/src/main/scala/org/apache/spark/ui/jobs/StagePage.scala

@@ -105,28 +105,29 @@ private[ui] class StagePage(parent: StagesTab, store: AppStatusStore) extends We
     val stageAttemptId = parameterAttempt.toInt
 
     val stageHeader = s"Details for Stage $stageId (Attempt $stageAttemptId)"
-    var stageDataTuple: Tuple2[StageData, Seq[Int]] = null
-    try {
-      stageDataTuple = parent.store.stageAttempt(stageId, stageAttemptId, details = false)
+    var stageDataTuple: Option[Tuple2[StageData, Seq[Int]]] = try {
+      Some(parent.store.stageAttempt(stageId, stageAttemptId, details = false))
     } catch {
       case e: NoSuchElementException => e.getMessage
+      None
     }
     var stageData: StageData = null
     var stageJobIds: Seq[Int] = null
-    if (stageDataTuple == null) {
-      stageData = {
-        val content =
-          <div id="no-info">
-            <p>No information to display for Stage
-              {stageId}
-              (Attempt
-              {stageAttemptId})</p>
-          </div>
-        return UIUtils.headerSparkPage(request, stageHeader, content, parent)
-      }
-    } else {
-      stageData = stageDataTuple._1
-      stageJobIds = stageDataTuple._2
+    stageDataTuple match {
+      case Some(stageTuple) =>
+        stageData = stageTuple._1
+        stageJobIds = stageTuple._2
+      case None =>
+        stageData = {
+          val content =
+            <div id="no-info">
+              <p>No information to display for Stage
+                {stageId}
+                (Attempt
+                {stageAttemptId})</p>
+            </div>
+          return UIUtils.headerSparkPage(request, stageHeader, content, parent)
+        }
     }
 
     val localitySummary = store.localitySummary(stageData.stageId, stageData.attemptId)