diff --git a/core/src/main/scala/org/apache/spark/util/random/XORShiftRandom.scala b/core/src/main/scala/org/apache/spark/util/random/XORShiftRandom.scala index ca611b67ed91d2bb22f80521ea84465ed799d83c..8a4cdea2fa7b107143e1f408904e5f744bf3bf8a 100644 --- a/core/src/main/scala/org/apache/spark/util/random/XORShiftRandom.scala +++ b/core/src/main/scala/org/apache/spark/util/random/XORShiftRandom.scala @@ -17,8 +17,11 @@ package org.apache.spark.util.random +import java.nio.ByteBuffer import java.util.{Random => JavaRandom} +import scala.util.hashing.MurmurHash3 + import org.apache.spark.util.Utils.timeIt /** @@ -36,8 +39,8 @@ private[spark] class XORShiftRandom(init: Long) extends JavaRandom(init) { def this() = this(System.nanoTime) - private var seed = init - + private var seed = XORShiftRandom.hashSeed(init) + // we need to just override next - this will be called by nextInt, nextDouble, // nextGaussian, nextLong, etc. override protected def next(bits: Int): Int = { @@ -49,13 +52,19 @@ private[spark] class XORShiftRandom(init: Long) extends JavaRandom(init) { } override def setSeed(s: Long) { - seed = s + seed = XORShiftRandom.hashSeed(s) } } /** Contains benchmark method and main method to run benchmark of the RNG */ private[spark] object XORShiftRandom { + /** Hash seeds to have 0/1 bits throughout. */ + private def hashSeed(seed: Long): Long = { + val bytes = ByteBuffer.allocate(java.lang.Long.SIZE).putLong(seed).array() + MurmurHash3.bytesHash(bytes) + } + /** * Main method for running benchmark * @param args takes one argument - the number of random numbers to generate diff --git a/core/src/test/scala/org/apache/spark/util/random/XORShiftRandomSuite.scala b/core/src/test/scala/org/apache/spark/util/random/XORShiftRandomSuite.scala index c51d12bfe0bc6f6d7eb96b31710178e832cd5084..757476efdb789e51fd0b955b434a2a37ecfea9a0 100644 --- a/core/src/test/scala/org/apache/spark/util/random/XORShiftRandomSuite.scala +++ b/core/src/test/scala/org/apache/spark/util/random/XORShiftRandomSuite.scala @@ -72,4 +72,8 @@ class XORShiftRandomSuite extends FunSuite with ShouldMatchers { } + test ("XORShift with zero seed") { + val random = new XORShiftRandom(0L) + assert(random.nextInt() != 0) + } }