Revert "[SPARK-9458] Avoid object allocation in prefix generation."

This reverts commit 9514d874f0cf61f1eb4ec4f5f66e053119f769c9.

2 files changed, 28 insertions, 0 deletions

diff --git a/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/PrefixComparators.java b/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/PrefixComparators.java
index a9ee6042fe..600aff7d15 100644
--- a/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/PrefixComparators.java
+++ b/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/PrefixComparators.java
@@ -29,6 +29,7 @@ public class PrefixComparators {
 
   public static final StringPrefixComparator STRING = new StringPrefixComparator();
   public static final IntegralPrefixComparator INTEGRAL = new IntegralPrefixComparator();
+  public static final FloatPrefixComparator FLOAT = new FloatPrefixComparator();
   public static final DoublePrefixComparator DOUBLE = new DoublePrefixComparator();
 
   public static final class StringPrefixComparator extends PrefixComparator {
@@ -54,6 +55,21 @@ public class PrefixComparators {
     public final long NULL_PREFIX = Long.MIN_VALUE;
   }
 
+  public static final class FloatPrefixComparator extends PrefixComparator {
+    @Override
+    public int compare(long aPrefix, long bPrefix) {
+      float a = Float.intBitsToFloat((int) aPrefix);
+      float b = Float.intBitsToFloat((int) bPrefix);
+      return Utils.nanSafeCompareFloats(a, b);
+    }
+
+    public long computePrefix(float value) {
+      return Float.floatToIntBits(value) & 0xffffffffL;
+    }
+
+    public final long NULL_PREFIX = computePrefix(Float.NEGATIVE_INFINITY);
+  }
+
   public static final class DoublePrefixComparator extends PrefixComparator {
     @Override
     public int compare(long aPrefix, long bPrefix) {
diff --git a/core/src/test/scala/org/apache/spark/util/collection/unsafe/sort/PrefixComparatorsSuite.scala b/core/src/test/scala/org/apache/spark/util/collection/unsafe/sort/PrefixComparatorsSuite.scala
index 26b7a9e816..cf53a8ad21 100644
--- a/core/src/test/scala/org/apache/spark/util/collection/unsafe/sort/PrefixComparatorsSuite.scala
+++ b/core/src/test/scala/org/apache/spark/util/collection/unsafe/sort/PrefixComparatorsSuite.scala
@@ -55,6 +55,18 @@ class PrefixComparatorsSuite extends SparkFunSuite with PropertyChecks {
     forAll { (s1: String, s2: String) => testPrefixComparison(s1, s2) }
   }
 
+  test("float prefix comparator handles NaN properly") {
+    val nan1: Float = java.lang.Float.intBitsToFloat(0x7f800001)
+    val nan2: Float = java.lang.Float.intBitsToFloat(0x7fffffff)
+    assert(nan1.isNaN)
+    assert(nan2.isNaN)
+    val nan1Prefix = PrefixComparators.FLOAT.computePrefix(nan1)
+    val nan2Prefix = PrefixComparators.FLOAT.computePrefix(nan2)
+    assert(nan1Prefix === nan2Prefix)
+    val floatMaxPrefix = PrefixComparators.FLOAT.computePrefix(Float.MaxValue)
+    assert(PrefixComparators.FLOAT.compare(nan1Prefix, floatMaxPrefix) === 1)
+  }
+
   test("double prefix comparator handles NaNs properly") {
     val nan1: Double = java.lang.Double.longBitsToDouble(0x7ff0000000000001L)
     val nan2: Double = java.lang.Double.longBitsToDouble(0x7fffffffffffffffL)