[SPARK-22854][UI] Read Spark version from event logs.

The code was ignoring SparkListenerLogStart, which was added
somewhat recently to record the Spark version used to generate
an event log.

Author: Marcelo Vanzin <[email protected]>

Closes #20049 from vanzin/SPARK-22854.

Author: Marcelo Vanzin

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

@@ -48,7 +48,7 @@ private[spark] class AppStatusListener(
 
   import config._
 
-  private val sparkVersion = SPARK_VERSION
+  private var sparkVersion = SPARK_VERSION
   private var appInfo: v1.ApplicationInfo = null
   private var appSummary = new AppSummary(0, 0)
   private var coresPerTask: Int = 1
@@ -90,6 +90,11 @@ private[spark] class AppStatusListener(
     }
   }
 
+  override def onOtherEvent(event: SparkListenerEvent): Unit = event match {
+    case SparkListenerLogStart(version) => sparkVersion = version
+    case _ =>
+  }
+
   override def onApplicationStart(event: SparkListenerApplicationStart): Unit = {
     assert(event.appId.isDefined, "Application without IDs are not supported.")
 

core/src/test/scala/org/apache/spark/status/AppStatusListenerSuite.scala

@@ -103,6 +103,8 @@ class AppStatusListenerSuite extends SparkFunSuite with BeforeAndAfter {
   test("scheduler events") {
     val listener = new AppStatusListener(store, conf, true)
 
+    listener.onOtherEvent(SparkListenerLogStart("TestSparkVersion"))
+
     // Start the application.
     time += 1
     listener.onApplicationStart(SparkListenerApplicationStart(
@@ -125,6 +127,7 @@ class AppStatusListenerSuite extends SparkFunSuite with BeforeAndAfter {
       assert(attempt.endTime.getTime() === -1L)
       assert(attempt.sparkUser === "user")
       assert(!attempt.completed)
+      assert(attempt.appSparkVersion === "TestSparkVersion")
     }
 
     // Start a couple of executors.