maedhroz commented on code in PR #3194:
URL: https://github.com/apache/cassandra/pull/3194#discussion_r1542043293
##########
src/java/org/apache/cassandra/index/sai/iterators/KeyRangeConcatIterator.java:
##########
@@ -18,84 +18,78 @@
package org.apache.cassandra.index.sai.iterators;
import java.util.ArrayList;
-import java.util.Comparator;
+import java.util.Iterator;
import java.util.List;
-import java.util.PriorityQueue;
import com.google.common.annotations.VisibleForTesting;
import org.apache.cassandra.index.sai.utils.PrimaryKey;
import org.apache.cassandra.io.util.FileUtils;
/**
- * {@link KeyRangeConcatIterator} takes a list of sorted range iterator and
concatenates them, leaving duplicates in
+ * {@link KeyRangeConcatIterator} takes a list of sorted range iterators and
concatenates them, leaving duplicates in
* place, to produce a new stably sorted iterator. Duplicates are eliminated
later in
* {@link org.apache.cassandra.index.sai.plan.StorageAttachedIndexSearcher}
* as results from multiple SSTable indexes and their respective segments are
consumed.
- *
+ * <p>
* ex. (1, 2, 3) + (3, 3, 4, 5) -> (1, 2, 3, 3, 3, 4, 5)
* ex. (1, 2, 2, 3) + (3, 4, 4, 6, 6, 7) -> (1, 2, 2, 3, 3, 4, 4, 6, 6, 7)
- *
- * TODO Investigate removing the use of PriorityQueue from this class <a
href="https://issues.apache.org/jira/browse/CASSANDRA-18165";>CASSANDRA-18165</a>
*/
public class KeyRangeConcatIterator extends KeyRangeIterator
{
public static final String MUST_BE_SORTED_ERROR = "RangeIterator must be
sorted, previous max: %s, next min: %s";
- private final PriorityQueue<KeyRangeIterator> ranges;
+ private final Iterator<KeyRangeIterator> ranges;
+ private KeyRangeIterator currentRange;
private final List<KeyRangeIterator> toRelease;
- protected KeyRangeConcatIterator(KeyRangeIterator.Builder.Statistics
statistics, PriorityQueue<KeyRangeIterator> ranges)
+ protected KeyRangeConcatIterator(KeyRangeIterator.Builder.Statistics
statistics, List<KeyRangeIterator> ranges)
{
super(statistics);
- this.ranges = ranges;
+ if (ranges.isEmpty())
+ throw new IllegalArgumentException("Cannot concatenate empty list
of ranges");
+
+ this.ranges = ranges.iterator();
+ this.currentRange = this.ranges.next();
this.toRelease = new ArrayList<>(ranges);
Review Comment:
After looking at this, I think it might be worth trying to use the original
approach I proposed in
[CASSANDRA-18165](https://issues.apache.org/jira/browse/CASSANDRA-18165). We
should be able to avoid creating a new iterator, and while we're here, I'm not
really sure why we defensive copy `ranges` for `toRelease` when we've already
created a new list in the builder. (If we used my implementation, we could
rename `toRelease` to just `ranges` I guess?)
I know `getCurrent()` is gone, so it can't be a direct port, but I think we
can still do this without all the extra object creation...
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