Github user hvanhovell commented on a diff in the pull request:
https://github.com/apache/spark/pull/12490#discussion_r60264951
--- Diff:
core/src/main/java/org/apache/spark/util/collection/unsafe/sort/PrefixComparators.java
---
@@ -28,88 +28,84 @@
public class PrefixComparators {
private PrefixComparators() {}
- public static final StringPrefixComparator STRING = new
StringPrefixComparator();
- public static final StringPrefixComparatorDesc STRING_DESC = new
StringPrefixComparatorDesc();
- public static final BinaryPrefixComparator BINARY = new
BinaryPrefixComparator();
- public static final BinaryPrefixComparatorDesc BINARY_DESC = new
BinaryPrefixComparatorDesc();
- public static final LongPrefixComparator LONG = new
LongPrefixComparator();
- public static final LongPrefixComparatorDesc LONG_DESC = new
LongPrefixComparatorDesc();
- public static final DoublePrefixComparator DOUBLE = new
DoublePrefixComparator();
- public static final DoublePrefixComparatorDesc DOUBLE_DESC = new
DoublePrefixComparatorDesc();
-
- public static final class StringPrefixComparator extends
PrefixComparator {
- @Override
- public int compare(long aPrefix, long bPrefix) {
- return UnsignedLongs.compare(aPrefix, bPrefix);
- }
-
+ public static final PrefixComparator STRING = new
UnsignedPrefixComparator();
+ public static final PrefixComparator STRING_DESC = new
UnsignedPrefixComparatorDesc();
+ public static final PrefixComparator BINARY = new
UnsignedPrefixComparator();
+ public static final PrefixComparator BINARY_DESC = new
UnsignedPrefixComparatorDesc();
+ public static final PrefixComparator LONG = new SignedPrefixComparator();
+ public static final PrefixComparator LONG_DESC = new
SignedPrefixComparatorDesc();
+ public static final PrefixComparator DOUBLE = new
SignedPrefixComparator();
+ public static final PrefixComparator DOUBLE_DESC = new
SignedPrefixComparatorDesc();
+
+ public static final class StringPrefixComparator {
public static long computePrefix(UTF8String value) {
return value == null ? 0L : value.getPrefix();
}
}
- public static final class StringPrefixComparatorDesc extends
PrefixComparator {
- @Override
- public int compare(long bPrefix, long aPrefix) {
- return UnsignedLongs.compare(aPrefix, bPrefix);
+ public static final class BinaryPrefixComparator {
+ public static long computePrefix(byte[] bytes) {
+ return ByteArray.getPrefix(bytes);
}
}
- public static final class BinaryPrefixComparator extends
PrefixComparator {
- @Override
- public int compare(long aPrefix, long bPrefix) {
- return UnsignedLongs.compare(aPrefix, bPrefix);
+ public static final class DoublePrefixComparator {
+ public static long computePrefix(double value) {
+ // Java's doubleToLongBits already canonicalizes all NaN values to
the lowest possible NaN,
+ // so there's nothing special we need to do here.
+ return Double.doubleToLongBits(value);
}
+ }
- public static long computePrefix(byte[] bytes) {
- return ByteArray.getPrefix(bytes);
- }
+ /**
+ * Provides radix sort parameters. Comparators implementing this also
are indicating that the
+ * ordering they define is compatible with radix sort.
+ */
+ public static abstract class RadixSortSupport extends PrefixComparator {
+ /** @return Whether the sort should be descending in binary sort
order. */
+ public abstract boolean sortDescending();
+
+ /** @return Whether the sort should take into account the sign bit. */
+ public abstract boolean sortSigned();
}
- public static final class BinaryPrefixComparatorDesc extends
PrefixComparator {
+ //
+ // Standard prefix comparator implementations
+ //
+
+ public static final class UnsignedPrefixComparator extends
RadixSortSupport {
+ @Override public final boolean sortDescending() { return false; }
+ @Override public final boolean sortSigned() { return false; }
@Override
- public int compare(long bPrefix, long aPrefix) {
+ public final int compare(long aPrefix, long bPrefix) {
return UnsignedLongs.compare(aPrefix, bPrefix);
}
}
- public static final class LongPrefixComparator extends PrefixComparator {
+ public static final class UnsignedPrefixComparatorDesc extends
RadixSortSupport {
+ @Override public final boolean sortDescending() { return true; }
+ @Override public final boolean sortSigned() { return false; }
@Override
- public int compare(long a, long b) {
- return (a < b) ? -1 : (a > b) ? 1 : 0;
+ public final int compare(long bPrefix, long aPrefix) {
+ return UnsignedLongs.compare(aPrefix, bPrefix);
--- End diff --
A more generic question and probably beyond the scope of your PR. Is guava
something we still want a dependency on?
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