move XORShiftRandom to util.random and use it in BernoulliSampler

Author: mengxr

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

@@ -18,6 +18,7 @@
 package org.apache.spark.util
 
 import scala.util.Random
+import org.apache.spark.util.random.XORShiftRandom
 
 class Vector(val elements: Array[Double]) extends Serializable {
   def length = elements.length

core/src/main/scala/org/apache/spark/util/random/RandomSampler.scala

@@ -47,10 +47,11 @@ trait RandomSampler[T, U] extends Pseudorandom with Cloneable with Serializable
  * @tparam T item type
  */
 class BernoulliSampler[T](lb: Double, ub: Double, complement: Boolean = false)
-    (implicit random: Random = new Random)
+    (implicit random: Random = new XORShiftRandom)
   extends RandomSampler[T, T] {
 
-  def this(ratio: Double)(implicit random: Random = new Random) = this(0.0d, ratio)(random)
+  def this(ratio: Double)(implicit random: Random = new XORShiftRandom)
+    = this(0.0d, ratio)(random)
 
   override def setSeed(seed: Long) = random.setSeed(seed)
 

core/src/main/scala/org/apache/spark/util/XORShiftRandom.scala renamed to core/src/main/scala/org/apache/spark/util/random/XORShiftRandom.scala

@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-package org.apache.spark.util
+package org.apache.spark.util.random
 
 import java.util.{Random => JavaRandom}
 import org.apache.spark.util.Utils.timeIt
@@ -46,6 +46,10 @@ private[spark] class XORShiftRandom(init: Long) extends JavaRandom(init) {
     seed = nextSeed
     (nextSeed & ((1L << bits) -1)).asInstanceOf[Int]
   }
+
+  override def setSeed(s: Long) {
+    seed = s
+  }
 }
 
 /** Contains benchmark method and main method to run benchmark of the RNG */

core/src/test/scala/org/apache/spark/util/XORShiftRandomSuite.scala renamed to core/src/test/scala/org/apache/spark/util/random/XORShiftRandomSuite.scala

@@ -15,10 +15,8 @@
  * limitations under the License.
  */
 
-package org.apache.spark.util
+package org.apache.spark.util.random
 
-import java.util.Random
-import org.scalatest.FlatSpec
 import org.scalatest.FunSuite
 import org.scalatest.matchers.ShouldMatchers
 import org.apache.spark.util.Utils.times

mllib/src/main/scala/org/apache/spark/mllib/clustering/KMeans.scala

@@ -26,8 +26,7 @@ import org.apache.spark.SparkContext._
 import org.apache.spark.rdd.RDD
 import org.apache.spark.Logging
 import org.apache.spark.mllib.util.MLUtils
-import org.apache.spark.util.XORShiftRandom
-
+import org.apache.spark.util.random.XORShiftRandom
 
 
 /**