Clean code again

Author: li-zhihui

core/src/main/scala/org/apache/spark/executor/Executor.scala

@@ -323,13 +323,13 @@ private[spark] class Executor(
       for ((name, timestamp) <- newFiles if currentFiles.getOrElse(name, -1L) < timestamp) {
         logInfo("Fetching " + name + " with timestamp " + timestamp)
         Utils.fetchFile(name, new File(SparkFiles.getRootDirectory), conf,
-          env.securityManager, hadoopConf, timestamp, true)
+          env.securityManager, hadoopConf, timestamp, useCache = true)
         currentFiles(name) = timestamp
       }
       for ((name, timestamp) <- newJars if currentJars.getOrElse(name, -1L) < timestamp) {
         logInfo("Fetching " + name + " with timestamp " + timestamp)
         Utils.fetchFile(name, new File(SparkFiles.getRootDirectory), conf,
-          env.securityManager, hadoopConf, timestamp, true)
+          env.securityManager, hadoopConf, timestamp, useCache = true)
         currentJars(name) = timestamp
         // Add it to our class loader
         val localName = name.split("/").last

core/src/main/scala/org/apache/spark/util/Utils.scala

@@ -313,11 +313,12 @@ private[spark] object Utils extends Logging {
   }
 
   /**
-   * Download a file requested by the executor . Supports fetching the file in a variety of ways,
+   * Download a file to target directory. Supports fetching the file in a variety of ways,
    * including HTTP, HDFS and files on a standard filesystem, based on the URL parameter.
    *
-   * If `useCache` is true, first attempts to fetch the file from a local cache that's shared across
-   * executors running the same application.
+   * If `useCache` is true, first attempts to fetch the file to a local cache that's shared 
+   * across executors running the same application. `useCache` is used mainly for 
+   * the the executors, not in local mode.
    *
    * Throws SparkException if the target file already exists and has different contents than
    * the requested file.
@@ -377,7 +378,7 @@ private[spark] object Utils extends Logging {
   }
 
   /**
-   * Download a file requested by the executor. Supports fetching the file in a variety of ways,
+   * Download a file to target directory. Supports fetching the file in a variety of ways,
    * including HTTP, HDFS and files on a standard filesystem, based on the URL parameter.
    *
    * Throws SparkException if the target file already exists and has different contents than