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SPARK-1632. Remove unnecessary boxing in compares in ExternalAppendOnlyM... #559

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SPARK-1632. Remove unnecessary boxing in compares in ExternalAppendOnlyM... #559

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SPARK-1632. Remove unnecessary boxing in compares in ExternalAppendOn…
sryza Apr 25, 2014
a6cd352
Only compute hashes once
sryza Apr 25, 2014
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8 changes: 5 additions & 3 deletions core/src/main/scala/org/apache/spark/util/collection/ExternalAppendOnlyMap.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -337,8 +337,8 @@ class ExternalAppendOnlyMap[K, V, C](
}

override def compareTo(other: StreamBuffer): Int = {
// minus sign because mutable.PriorityQueue dequeues the max, not the min
-minKeyHash.compareTo(other.minKeyHash)
// descending order because mutable.PriorityQueue dequeues the max, not the min
if (other.minKeyHash < minKeyHash) -1 else if (other.minKeyHash == minKeyHash) 0 else 1
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@mridulm mridulm Apr 27, 2014

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It is better to use Integer.compare instead of writing these manually.

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@srowen srowen Apr 27, 2014

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Java 7 only :(
http://docs.oracle.com/javase/7/docs/api/java/lang/Integer.html#compare(int, int)

Guava has Ints.compare() though:
http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/primitives/Ints.html#compare(int, int)

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@andrewor14 andrewor14 Apr 27, 2014

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We could also write our own Utils.compare, though this is only used in 2 places so I think it's fine to just write it out directly. Also this is a super hot code path so maybe it's better to just avoid function calls altogether (maybe, maybe not).

}
}
}
Expand Down Expand Up @@ -422,7 +422,9 @@ class ExternalAppendOnlyMap[K, V, C](
private[spark] object ExternalAppendOnlyMap {
private class KCComparator[K, C] extends Comparator[(K, C)] {
def compare(kc1: (K, C), kc2: (K, C)): Int = {
kc1._1.hashCode().compareTo(kc2._1.hashCode())
val hash1 = kc1._1.hashCode()
val hash2 = kc2._1.hashCode()
if (hash1 < hash2) -1 else if (hash1 == hash2) 0 else 1
}
}
}