From a7721afdaead1977c78c8afb60ebd21e076a1e01 Mon Sep 17 00:00:00 2001
From: Carson Wang <carson.wang@intel.com>
Date: Thu, 17 Dec 2015 15:37:23 +0800
Subject: [PATCH] Display correct error message when accessing REST API with an
 unknown app Id

---
 .../apache/spark/deploy/history/HistoryServer.scala  | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala b/core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala
index f31fef0eccc3b..0544fe232ccc6 100644
--- a/core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/history/HistoryServer.scala
@@ -115,7 +115,17 @@ class HistoryServer(
   }
 
   def getSparkUI(appKey: String): Option[SparkUI] = {
-    Option(appCache.get(appKey))
+    try {
+      val ui = appCache.get(appKey)
+      Some(ui)
+    } catch {
+      case e: Exception => e.getCause() match {
+        case nsee: NoSuchElementException =>
+          None
+
+        case cause: Exception => throw cause
+      }
+    }
   }
 
   initialize()