[SPARK-16694][CORE] Use for/foreach rather than map for Unit expressions whose side effects are required

## What changes were proposed in this pull request?

Use foreach/for instead of map where operation requires execution of body, not actually defining a transformation

## How was this patch tested?

Jenkins

Author: Sean Owen <sowen@cloudera.com>

Closes #14332 from srowen/SPARK-16694.

5 files changed, 20 insertions, 20 deletions

diff --git a/core/src/main/scala/org/apache/spark/api/r/RBackendHandler.scala b/core/src/main/scala/org/apache/spark/api/r/RBackendHandler.scala
index c416e835a9..7d5348266b 100644
--- a/core/src/main/scala/org/apache/spark/api/r/RBackendHandler.scala
+++ b/core/src/main/scala/org/apache/spark/api/r/RBackendHandler.scala
@@ -198,7 +198,7 @@ private[r] class RBackendHandler(server: RBackend)
       args: Array[Object]): Option[Int] = {
     val numArgs = args.length
 
-    for (index <- 0 until parameterTypesOfMethods.length) {
+    for (index <- parameterTypesOfMethods.indices) {
       val parameterTypes = parameterTypesOfMethods(index)
 
       if (parameterTypes.length == numArgs) {
@@ -240,7 +240,7 @@ private[r] class RBackendHandler(server: RBackend)
           // Convert args if needed
           val parameterTypes = parameterTypesOfMethods(index)
 
-          (0 until numArgs).map { i =>
+          for (i <- 0 until numArgs) {
             if (parameterTypes(i) == classOf[Seq[Any]] && args(i).getClass.isArray) {
               // Convert a Java array to scala Seq
               args(i) = args(i).asInstanceOf[Array[_]].toSeq
diff --git a/core/src/main/scala/org/apache/spark/deploy/Client.scala b/core/src/main/scala/org/apache/spark/deploy/Client.scala
index 640f25f504..bf2dab6e71 100644
--- a/core/src/main/scala/org/apache/spark/deploy/Client.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/Client.scala
@@ -116,7 +116,7 @@ private class ClientEndpoint(
   }
 
   /* Find out driver status then exit the JVM */
-  def pollAndReportStatus(driverId: String) {
+  def pollAndReportStatus(driverId: String): Unit = {
     // Since ClientEndpoint is the only RpcEndpoint in the process, blocking the event loop thread
     // is fine.
     logInfo("... waiting before polling master for driver state")
@@ -137,12 +137,14 @@ private class ClientEndpoint(
           case _ =>
         }
         // Exception, if present
-        statusResponse.exception.map { e =>
-          logError(s"Exception from cluster was: $e")
-          e.printStackTrace()
-          System.exit(-1)
+        statusResponse.exception match {
+          case Some(e) =>
+            logError(s"Exception from cluster was: $e")
+            e.printStackTrace()
+            System.exit(-1)
+          case _ =>
+            System.exit(0)
         }
-        System.exit(0)
     }
   }
 
diff --git a/core/src/main/scala/org/apache/spark/rdd/CoalescedRDD.scala b/core/src/main/scala/org/apache/spark/rdd/CoalescedRDD.scala
index 2ec9846e33..9c198a61f3 100644
--- a/core/src/main/scala/org/apache/spark/rdd/CoalescedRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/CoalescedRDD.scala
@@ -183,14 +183,14 @@ private class DefaultPartitionCoalescer(val balanceSlack: Double = 0.10)
 
     getAllPrefLocs(prev)
 
-    // gets all the preffered locations of the previous RDD and splits them into partitions
+    // gets all the preferred locations of the previous RDD and splits them into partitions
     // with preferred locations and ones without
-    def getAllPrefLocs(prev: RDD[_]) {
+    def getAllPrefLocs(prev: RDD[_]): Unit = {
       val tmpPartsWithLocs = mutable.LinkedHashMap[Partition, Seq[String]]()
       // first get the locations for each partition, only do this once since it can be expensive
       prev.partitions.foreach(p => {
           val locs = currPrefLocs(p, prev)
-          if (locs.size > 0) {
+          if (locs.nonEmpty) {
             tmpPartsWithLocs.put(p, locs)
           } else {
             partsWithoutLocs += p
@@ -198,13 +198,13 @@ private class DefaultPartitionCoalescer(val balanceSlack: Double = 0.10)
         }
       )
       // convert it into an array of host to partition
-      (0 to 2).map(x =>
-        tmpPartsWithLocs.foreach(parts => {
+      for (x <- 0 to 2) {
+        tmpPartsWithLocs.foreach { parts =>
           val p = parts._1
           val locs = parts._2
           if (locs.size > x) partsWithLocs += ((locs(x), p))
-        } )
-      )
+        }
+      }
     }
   }
 
diff --git a/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala b/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala
index 515fd6f4e2..99afe0250c 100644
--- a/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala
@@ -155,7 +155,7 @@ class HadoopRDD[K, V](
         logDebug("Cloning Hadoop Configuration")
         val newJobConf = new JobConf(conf)
         if (!conf.isInstanceOf[JobConf]) {
-          initLocalJobConfFuncOpt.map(f => f(newJobConf))
+          initLocalJobConfFuncOpt.foreach(f => f(newJobConf))
         }
         newJobConf
       }
@@ -174,7 +174,7 @@ class HadoopRDD[K, V](
         HadoopRDD.CONFIGURATION_INSTANTIATION_LOCK.synchronized {
           logDebug("Creating new JobConf and caching it for later re-use")
           val newJobConf = new JobConf(conf)
-          initLocalJobConfFuncOpt.map(f => f(newJobConf))
+          initLocalJobConfFuncOpt.foreach(f => f(newJobConf))
           HadoopRDD.putCachedMetadata(jobConfCacheKey, newJobConf)
           newJobConf
         }
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosCoarseGrainedSchedulerBackend.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosCoarseGrainedSchedulerBackend.scala
index 959d6fd46d..263e6197a6 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosCoarseGrainedSchedulerBackend.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosCoarseGrainedSchedulerBackend.scala
@@ -220,9 +220,7 @@ private[spark] class MesosCoarseGrainedSchedulerBackend(
       command.addUris(CommandInfo.URI.newBuilder().setValue(uri.get))
     }
 
-    conf.getOption("spark.mesos.uris").map { uris =>
-      setupUris(uris, command)
-    }
+    conf.getOption("spark.mesos.uris").foreach(setupUris(_, command))
 
     command.build()
   }