Merge pull request #22 from lyft/spark-bug

SPARK-33790 Reduce rpc call to SingleFileEventLogFileReader

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

@@ -106,7 +106,7 @@ object EventLogFileReader {
       lastIndex: Option[Long]): EventLogFileReader = {
     lastIndex match {
       case Some(_) => new RollingEventLogFilesFileReader(fs, path)
-      case None => new SingleFileEventLogFileReader(fs, path, None)
+      case None => new SingleFileEventLogFileReader(fs, path)
     }
   }
 
@@ -116,7 +116,7 @@ object EventLogFileReader {
 
   def apply(fs: FileSystem, status: FileStatus): Option[EventLogFileReader] = {
     if (isSingleEventLog(status)) {
-      Some(new SingleFileEventLogFileReader(fs, status.getPath, Some(status)))
+      Some(new SingleFileEventLogFileReader(fs, status.getPath, Option(status)))
     } else if (isRollingEventLogs(status)) {
       Some(new RollingEventLogFilesFileReader(fs, status.getPath))
     } else {
@@ -164,13 +164,11 @@ object EventLogFileReader {
  * FileNotFoundException could occur if the log file is renamed before getting the
  * status of log file.
  */
-class SingleFileEventLogFileReader(
+private[history] class SingleFileEventLogFileReader(
     fs: FileSystem,
-    path: Path, fileStatus: Option[FileStatus]) extends EventLogFileReader(fs, path) {
-  private lazy val status = fileStatus match {
-    case Some(s) => s
-    case None => fileSystem.getFileStatus(rootPath)
-  }
+    path: Path,
+    maybeStatus: Option[FileStatus] = None) extends EventLogFileReader(fs, path) {
+  private lazy val status = maybeStatus.getOrElse(fileSystem.getFileStatus(rootPath))
 
   override def lastIndex: Option[Long] = None
 
@@ -206,7 +204,7 @@ class SingleFileEventLogFileReader(
  * This reader lists the files only once; if caller would like to play with updated list,
  * it needs to create another reader instance.
  */
-class RollingEventLogFilesFileReader(
+private[history] class RollingEventLogFilesFileReader(
     fs: FileSystem,
     path: Path) extends EventLogFileReader(fs, path) {
   import RollingEventLogFilesWriter._