Expose method and class - so that we can use it from user code (particularly...

Expose method and class - so that we can use it from user code (particularly since checkpoint directory is autogenerated now

core/src/main/scala/org/apache/spark/SparkContext.scala

@@ -956,6 +956,8 @@ class SparkContext(
     }
   }
 
+  def getCheckpointDir = checkpointDir.getOrElse(null)
+
   /** Default level of parallelism to use when not given by user (e.g. parallelize and makeRDD). */
   def defaultParallelism: Int = taskScheduler.defaultParallelism
 
@@ -1125,7 +1127,7 @@ object SparkContext {
     if (sparkHome != null) {
       res.setSparkHome(sparkHome)
     }
-    if (!jars.isEmpty) {
+    if (null != jars && !jars.isEmpty) {
       res.setJars(jars)
     }
     res.setExecutorEnv(environment.toSeq)

core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala

@@ -28,7 +28,6 @@ import org.apache.spark.{SparkContext, SparkException}
 /**
  * Contains util methods to interact with Hadoop from Spark.
  */
-private[spark]
 class SparkHadoopUtil {
   val conf = newConfiguration()
   UserGroupInformation.setConfiguration(conf)