Shekharrajak commented on code in PR #22572:
URL: https://github.com/apache/kafka/pull/22572#discussion_r3412538692
##########
share-coordinator/src/main/java/org/apache/kafka/coordinator/share/PersisterStateBatchCombiner.java:
##########
@@ -20,385 +20,170 @@
import org.apache.kafka.server.share.persister.PersisterStateBatch;
import java.util.ArrayList;
-import java.util.Iterator;
+import java.util.Comparator;
import java.util.List;
-import java.util.Objects;
-import java.util.TreeSet;
+import java.util.TreeMap;
+/**
+ * Combines an existing list of {@link PersisterStateBatch} entries with a
list of newly produced
+ * entries and returns the shortest non-overlapping, {@code (deliveryState,
deliveryCount)}-distinct
+ * cover of the union, clipped at {@code startOffset} (SPSO).
+ *
+ * <p>The merge is performed by an event-driven sweep-line over the union of
both inputs. Each
+ * input batch contributes one BEGIN event at {@code firstOffset} and one END
event at
+ * {@code lastOffset + 1}. Events are processed in offset order (END before
BEGIN at the same
+ * offset). A counted ordered map tracks the currently active priorities; the
first key defines the
+ * {@code (state, count)} that wins on the current sub-range. Successive
sub-ranges with identical
+ * {@code (state, count)} are coalesced on the fly.
+ *
+ * <p>Complexity: {@code O((n + k) log p)} where {@code n} is the total number
of input batches,
+ * {@code k} is the number of overlap transitions encountered, and {@code p}
is the number of
+ * distinct {@code (deliveryState, deliveryCount)} priorities.
+ */
public class PersisterStateBatchCombiner {
- private List<PersisterStateBatch> combinedBatchList; // link between
pruning and merging
+ private static final Comparator<BatchPriority> PRIORITY_DESC = (a, b) -> {
+ int cmpCount = Short.compare(b.deliveryCount(), a.deliveryCount());
Review Comment:
State
0 = AVAILABLE
1 = ACQUIRED
2 = ACKNOWLEDGED
3 = ARCHIVING
4 = ARCHIVED
---
existing: (100,110,state0,count1)
new:
(101,105,state1,count2)
(101,115,state2,count2)
(101,120,state3,count2)
result:
(100,100,state0,count1)
(101,120,state3,count2)
Meaning: all new ranges have higher count 2, and among them state 3 wins
over state 2 and 1.
---
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