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Objects: simplify merging iterator even more^2

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initialMaxValue streams can be simplified too
This commit is contained in:
Stepan Usatiuk
2025-04-03 22:31:59 +02:00
parent 4c5cbfb5bf
commit cb8c50000a
1 changed files with 26 additions and 11 deletions
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37
dhfs-parent/objects/src/main/java/com/usatiuk/objects/iterators/MergingKvIterator.java
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@@ -4,7 +4,6 @@ import io.quarkus.logging.Log;
import org.apache.commons.lang3.tuple.Pair;
import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
public class MergingKvIterator<K extends Comparable<K>, V> extends ReversibleKvIterator<K, V> {
@@ -27,18 +26,34 @@ public class MergingKvIterator<K extends Comparable<K>, V> extends ReversibleKvI
// We have a bunch of iterators that have given us theirs "greatest LT/LE key"
// now we need to pick the greatest of those to start with
// But if some of them don't have a lesser key, we need to pick the smallest of those
var found = _iterators.keySet().stream()
.filter(CloseableKvIterator::hasNext)
.map((i) -> {
var peeked = i.peekNextKey();
// Log.warnv("peeked: {0}, from {1}", peeked, i.getClass());
return peeked;
}).distinct().collect(Collectors.partitioningBy(e -> startType == IteratorStart.LE ? e.compareTo(startKey) <= 0 : e.compareTo(startKey) < 0));
K greatestLess = null;
K smallestMore = null;
for (var it : _iterators.keySet()) {
if (it.hasNext()) {
var peeked = it.peekNextKey();
if (startType == IteratorStart.LE ? peeked.compareTo(startKey) <= 0 : peeked.compareTo(startKey) < 0) {
if (greatestLess == null || peeked.compareTo(greatestLess) > 0) {
greatestLess = peeked;
}
} else {
if (smallestMore == null || peeked.compareTo(smallestMore) < 0) {
smallestMore = peeked;
}
}
}
}
K initialMaxValue;
if (!found.get(true).isEmpty())
initialMaxValue = found.get(true).stream().max(Comparator.naturalOrder()).orElse(null);
if (greatestLess != null)
initialMaxValue = greatestLess;
else
initialMaxValue = found.get(false).stream().min(Comparator.naturalOrder()).orElse(null);
initialMaxValue = smallestMore;
if (initialMaxValue == null) {
// Empty iterators
}
for (var iterator : _iterators.keySet()) {
while (iterator.hasNext() && iterator.peekNextKey().compareTo(initialMaxValue) < 0) {