Spark 1095 : Adding explicit return types to all public methods

Excluded those that are self-evident and the cases that are discussed in the mailing list.

Author: NirmalReddy <nirmal_reddy2000@yahoo.com>
Author: NirmalReddy <nirmal.reddy@imaginea.com>

Closes #168 from NirmalReddy/Spark-1095 and squashes the following commits:

ac54b29 [NirmalReddy] import misplaced
8c5ff3e [NirmalReddy] Changed syntax of unit returning methods
02d0778 [NirmalReddy] fixed explicit types in all the other packages
1c17773 [NirmalReddy] fixed explicit types in core package

5 files changed, 33 insertions, 15 deletions

diff --git a/streaming/src/main/scala/org/apache/spark/streaming/StreamingContext.scala b/streaming/src/main/scala/org/apache/spark/streaming/StreamingContext.scala
index 062b888e80..e198c69470 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/StreamingContext.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/StreamingContext.scala
@@ -431,7 +431,7 @@ class StreamingContext private[streaming] (
    * Stop the execution of the streams.
    * @param stopSparkContext Stop the associated SparkContext or not
    */
-  def stop(stopSparkContext: Boolean = true) = synchronized {
+  def stop(stopSparkContext: Boolean = true): Unit = synchronized {
     scheduler.stop()
     logInfo("StreamingContext stopped successfully")
     waiter.notifyStop()
@@ -489,7 +489,7 @@ object StreamingContext extends Logging {
    * Find the JAR from which a given class was loaded, to make it easy for users to pass
    * their JARs to StreamingContext.
    */
-  def jarOfClass(cls: Class[_]) = SparkContext.jarOfClass(cls)
+  def jarOfClass(cls: Class[_]): Seq[String] = SparkContext.jarOfClass(cls)
 
   private[streaming] def createNewSparkContext(conf: SparkConf): SparkContext = {
     // Set the default cleaner delay to an hour if not already set.
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaDStreamLike.scala b/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaDStreamLike.scala
index a85cd04c93..bb2f492d06 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaDStreamLike.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaDStreamLike.scala
@@ -49,7 +49,9 @@ trait JavaDStreamLike[T, This <: JavaDStreamLike[T, This, R], R <: JavaRDDLike[T
    * Print the first ten elements of each RDD generated in this DStream. This is an output
    * operator, so this DStream will be registered as an output stream and there materialized.
    */
-  def print() = dstream.print()
+  def print(): Unit = {
+    dstream.print()
+  }
 
   /**
    * Return a new DStream in which each RDD has a single element generated by counting each RDD
@@ -401,7 +403,7 @@ trait JavaDStreamLike[T, This <: JavaDStreamLike[T, This, R], R <: JavaRDDLike[T
    * Enable periodic checkpointing of RDDs of this DStream.
    * @param interval Time interval after which generated RDD will be checkpointed
    */
-  def checkpoint(interval: Duration) = {
+  def checkpoint(interval: Duration): DStream[T] = {
     dstream.checkpoint(interval)
   }
 }
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaStreamingContext.scala b/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaStreamingContext.scala
index c48d754e43..b705d2ec9a 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaStreamingContext.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaStreamingContext.scala
@@ -477,31 +477,41 @@ class JavaStreamingContext(val ssc: StreamingContext) {
   /**
    * Start the execution of the streams.
    */
-  def start() = ssc.start()
+  def start(): Unit = {
+    ssc.start()
+  }
 
   /**
    * Wait for the execution to stop. Any exceptions that occurs during the execution
    * will be thrown in this thread.
    */
-  def awaitTermination() = ssc.awaitTermination()
+  def awaitTermination(): Unit = {
+    ssc.awaitTermination()
+  }
 
   /**
    * Wait for the execution to stop. Any exceptions that occurs during the execution
    * will be thrown in this thread.
    * @param timeout time to wait in milliseconds
    */
-  def awaitTermination(timeout: Long) = ssc.awaitTermination(timeout)
+  def awaitTermination(timeout: Long): Unit = {
+    ssc.awaitTermination(timeout)
+  }
 
   /**
    * Stop the execution of the streams. Will stop the associated JavaSparkContext as well.
    */
-  def stop() = ssc.stop()
+  def stop(): Unit = {
+    ssc.stop()
+  }
 
   /**
    * Stop the execution of the streams.
    * @param stopSparkContext Stop the associated SparkContext or not
    */
-  def stop(stopSparkContext: Boolean) = ssc.stop(stopSparkContext)
+  def stop(stopSparkContext: Boolean): Unit = {
+    ssc.stop(stopSparkContext)
+  }
 }
 
 /**
@@ -579,7 +589,7 @@ object JavaStreamingContext {
    * Find the JAR from which a given class was loaded, to make it easy for users to pass
    * their JARs to StreamingContext.
    */
-  def jarOfClass(cls: Class[_]) = SparkContext.jarOfClass(cls).toArray
+  def jarOfClass(cls: Class[_]): Array[String] = SparkContext.jarOfClass(cls).toArray
 }
 
 /**
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/dstream/DStream.scala b/streaming/src/main/scala/org/apache/spark/streaming/dstream/DStream.scala
index 6bff56a9d3..d48b51aa69 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/dstream/DStream.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/dstream/DStream.scala
@@ -503,14 +503,18 @@ abstract class DStream[T: ClassTag] (
    * 'this' DStream will be registered as an output stream and therefore materialized.
    */
   @deprecated("use foreachRDD", "0.9.0")
-  def foreach(foreachFunc: RDD[T] => Unit) = this.foreachRDD(foreachFunc)
+  def foreach(foreachFunc: RDD[T] => Unit): Unit = {
+    this.foreachRDD(foreachFunc)
+  }
 
   /**
    * Apply a function to each RDD in this DStream. This is an output operator, so
    * 'this' DStream will be registered as an output stream and therefore materialized.
    */
   @deprecated("use foreachRDD", "0.9.0")
-  def foreach(foreachFunc: (RDD[T], Time) => Unit) = this.foreachRDD(foreachFunc)
+  def foreach(foreachFunc: (RDD[T], Time) => Unit): Unit = {
+    this.foreachRDD(foreachFunc)
+  }
 
   /**
    * Apply a function to each RDD in this DStream. This is an output operator, so
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/scheduler/BatchInfo.scala b/streaming/src/main/scala/org/apache/spark/streaming/scheduler/BatchInfo.scala
index 4e8d07fe92..7f3cd2f8eb 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/scheduler/BatchInfo.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/scheduler/BatchInfo.scala
@@ -39,17 +39,19 @@ case class BatchInfo(
    * was submitted to the streaming scheduler. Essentially, it is
    * `processingStartTime` - `submissionTime`.
    */
-  def schedulingDelay = processingStartTime.map(_ - submissionTime)
+  def schedulingDelay: Option[Long] = processingStartTime.map(_ - submissionTime)
 
   /**
    * Time taken for the all jobs of this batch to finish processing from the time they started
    * processing. Essentially, it is `processingEndTime` - `processingStartTime`.
    */
-  def processingDelay = processingEndTime.zip(processingStartTime).map(x => x._1 - x._2).headOption
+  def processingDelay: Option[Long] = processingEndTime.zip(processingStartTime)
+    .map(x => x._1 - x._2).headOption
 
   /**
    * Time taken for all the jobs of this batch to finish processing from the time they
    * were submitted.  Essentially, it is `processingDelay` + `schedulingDelay`.
    */
-  def totalDelay = schedulingDelay.zip(processingDelay).map(x => x._1 + x._2).headOption
+  def totalDelay: Option[Long] = schedulingDelay.zip(processingDelay)
+    .map(x => x._1 + x._2).headOption
 }