Explicitly set the implicit parameters

Author: zsxwing

core/src/main/scala/org/apache/spark/rdd/RDD.scala

@@ -1176,13 +1176,17 @@ abstract class RDD[T: ClassTag](
   def saveAsTextFile(path: String) {
     // https://issues.apache.org/jira/browse/SPARK-2075
     // NullWritable is a Comparable rather than Comparable[NullWritable] in Hadoop 1.+,
-    // so the compiler cannot find an implicit Ordering for it. It will generate different
-    // anonymous classes for `saveAsTextFile` in Hadoop 1.+ and Hadoop 2.+. Therefore, here we
-    // provide an Ordering for NullWritable so that the compiler will generate same codes.
-    implicit val nullWritableOrdering = new Ordering[NullWritable] {
+    // so the compiler cannot find an implicit Ordering for it and will use the default `null`.
+    // It will generate different anonymous classes for `saveAsTextFile` in Hadoop 1.+ and
+    // Hadoop 2.+. Therefore, here we provide an Ordering for NullWritable so that the compiler
+    // will generate same bytecode.
+    val nullWritableOrdering = new Ordering[NullWritable] {
       override def compare(x: NullWritable, y: NullWritable): Int = 0
     }
-    this.map(x => (NullWritable.get(), new Text(x.toString)))
+    val nullWritableClassTag = implicitly[ClassTag[NullWritable]]
+    val textClassTag = implicitly[ClassTag[Text]]
+    val r = this.map(x => (NullWritable.get(), new Text(x.toString)))
+    RDD.rddToPairRDDFunctions(r)(nullWritableClassTag, textClassTag, nullWritableOrdering)
       .saveAsHadoopFile[TextOutputFormat[NullWritable, Text]](path)
   }
 
@@ -1191,10 +1195,13 @@ abstract class RDD[T: ClassTag](
    */
   def saveAsTextFile(path: String, codec: Class[_ <: CompressionCodec]) {
     // https://issues.apache.org/jira/browse/SPARK-2075
-    implicit val nullWritableOrdering = new Ordering[NullWritable] {
+    val nullWritableOrdering = new Ordering[NullWritable] {
       override def compare(x: NullWritable, y: NullWritable): Int = 0
     }
-    this.map(x => (NullWritable.get(), new Text(x.toString)))
+    val nullWritableClassTag = implicitly[ClassTag[NullWritable]]
+    val textClassTag = implicitly[ClassTag[Text]]
+    val r = this.map(x => (NullWritable.get(), new Text(x.toString)))
+    RDD.rddToPairRDDFunctions(r)(nullWritableClassTag, textClassTag, nullWritableOrdering)
       .saveAsHadoopFile[TextOutputFormat[NullWritable, Text]](path, codec)
   }