[SPARK-3325][Streaming] Add a parameter to the method print in class DStream

This PR is a fixed version of the original PR #3237 by watermen and scwf.
This adds the ability to specify how many elements to print in `DStream.print`.

Author: Yadong Qi <qiyadong2010@gmail.com>
Author: q00251598 <qiyadong@huawei.com>
Author: Tathagata Das <tathagata.das1565@gmail.com>
Author: wangfei <wangfei1@huawei.com>

Closes #3865 from tdas/print-num and squashes the following commits:

cd34e9e [Tathagata Das] Fix bug
7c09f16 [Tathagata Das] Merge remote-tracking branch 'apache-github/master' into HEAD
bb35d1a [Yadong Qi] Update MimaExcludes.scala
f8098ca [Yadong Qi] Update MimaExcludes.scala
f6ac3cb [Yadong Qi] Update MimaExcludes.scala
e4ed897 [Yadong Qi] Update MimaExcludes.scala
3b9d5cf [wangfei] fix conflicts
ec8a3af [q00251598] move to  Spark 1.3
26a70c0 [q00251598] extend the Python DStream's print
b589a4b [q00251598] add another print function

2 files changed, 20 insertions, 4 deletions

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 2a7004e56e..e0542eda13 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
@@ -51,7 +51,15 @@ trait JavaDStreamLike[T, This <: JavaDStreamLike[T, This, R], R <: JavaRDDLike[T
    * operator, so this DStream will be registered as an output stream and there materialized.
    */
   def print(): Unit = {
-    dstream.print()
+    print(10)
+  }
+
+  /**
+   * Print the first num 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(num: Int): Unit = {
+    dstream.print(num)
   }
 
   /**
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 7f8651e719..28fc00cf39 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
@@ -605,13 +605,21 @@ abstract class DStream[T: ClassTag] (
    * operator, so this DStream will be registered as an output stream and there materialized.
    */
   def print() {
+    print(10)
+  }
+
+  /**
+   * Print the first num 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(num: Int) {
     def foreachFunc = (rdd: RDD[T], time: Time) => {
-      val first11 = rdd.take(11)
+      val firstNum = rdd.take(num + 1)
       println ("-------------------------------------------")
       println ("Time: " + time)
       println ("-------------------------------------------")
-      first11.take(10).foreach(println)
-      if (first11.size > 10) println("...")
+      firstNum.take(num).foreach(println)
+      if (firstNum.size > num) println("...")
       println()
     }
     new ForEachDStream(this, context.sparkContext.clean(foreachFunc)).register()