AndrewJSchofield commented on code in PR #17149:
URL: https://github.com/apache/kafka/pull/17149#discussion_r1756707238
##########
share-coordinator/src/main/java/org/apache/kafka/coordinator/share/ShareCoordinatorShard.java:
##########
@@ -537,38 +539,195 @@ private static ShareGroupOffset merge(ShareGroupOffset
soFar, ShareUpdateValue n
.setStartOffset(newStartOffset)
.setLeaderEpoch(newLeaderEpoch)
.setStateBatches(combineStateBatches(currentBatches,
newData.stateBatches().stream()
- .map(PersisterOffsetsStateBatch::from)
- .collect(Collectors.toCollection(LinkedHashSet::new)),
newStartOffset))
- .build();
+ .map(ShareCoordinatorShard::toPersisterStateBatch)
+ .collect(Collectors.toList()), newStartOffset))
+ .build();
}
/**
- * Util method which takes in 2 collections containing {@link
PersisterOffsetsStateBatch}
+ * Util method which takes in 2 collections containing {@link
PersisterStateBatch}
* and the startOffset.
- * It removes all batches from the 1st collection which have the same
first and last offset
- * as the batches in 2nd collection. It then creates a final list of
batches which contains the
- * former result and all the batches in the 2nd collection. In set
notation (A - B) U B (we prefer batches in B
- * which have same first and last offset in A).
- * Finally, it removes any batches where the lastOffset < startOffset, if
the startOffset > -1.
- * @param currentBatch - collection containing current soft state of
batches
- * @param newBatch - collection containing batches in incoming request
+ * This method checks any overlap between current state batches and new
state batches.
+ * Based on various conditions it creates new non-overlapping records
preferring new batches.
+ * Finally, it removes any batches where the lastOffset < startOffset, if
the startOffset > -1 and
+ * merges any contiguous intervals with same state.
+ * @param batchesSoFar - collection containing current soft state of
batches
+ * @param newBatches - collection containing batches in incoming request
* @param startOffset - startOffset to consider when removing old batches.
* @return List containing combined batches
*/
- private static List<PersisterOffsetsStateBatch> combineStateBatches(
- Collection<PersisterOffsetsStateBatch> currentBatch,
- Collection<PersisterOffsetsStateBatch> newBatch,
+ // visibility for testing
+ static List<PersisterStateBatch> combineStateBatches(
+ List<PersisterStateBatch> batchesSoFar,
+ List<PersisterStateBatch> newBatches,
long startOffset
) {
- currentBatch.removeAll(newBatch);
- List<PersisterOffsetsStateBatch> batchesToAdd = new
LinkedList<>(currentBatch);
- batchesToAdd.addAll(newBatch);
- // Any batches where the last offset is < the current start offset
- // are now expired. We should remove them from the persister.
+ // will take care of overlapping batches
+ Queue<PersisterStateBatch> batchQueue = new LinkedList<>(
+ mergeBatches(
+ pruneBatches(
+ getSortedList(batchesSoFar),
+ startOffset
+ )
+ ));
+
+ // will take care of overlapping batches
+ List<PersisterStateBatch> modifiedNewBatches = new ArrayList<>(
+ mergeBatches(
+ pruneBatches(
+ getSortedList(newBatches),
+ startOffset
+ )
+ ));
+
+ for (PersisterStateBatch batch : modifiedNewBatches) {
+ for (int i = 0; i < batchQueue.size(); i++) {
Review Comment:
We will re-evaluate `batchQueue.size()` on each loop iteration, and it could
in theory mutate quite significantly. I don't believe this is a safe loop
condition.
##########
share-coordinator/src/main/java/org/apache/kafka/coordinator/share/ShareCoordinatorShard.java:
##########
@@ -537,38 +539,195 @@ private static ShareGroupOffset merge(ShareGroupOffset
soFar, ShareUpdateValue n
.setStartOffset(newStartOffset)
.setLeaderEpoch(newLeaderEpoch)
.setStateBatches(combineStateBatches(currentBatches,
newData.stateBatches().stream()
- .map(PersisterOffsetsStateBatch::from)
- .collect(Collectors.toCollection(LinkedHashSet::new)),
newStartOffset))
- .build();
+ .map(ShareCoordinatorShard::toPersisterStateBatch)
+ .collect(Collectors.toList()), newStartOffset))
+ .build();
}
/**
- * Util method which takes in 2 collections containing {@link
PersisterOffsetsStateBatch}
+ * Util method which takes in 2 collections containing {@link
PersisterStateBatch}
* and the startOffset.
- * It removes all batches from the 1st collection which have the same
first and last offset
- * as the batches in 2nd collection. It then creates a final list of
batches which contains the
- * former result and all the batches in the 2nd collection. In set
notation (A - B) U B (we prefer batches in B
- * which have same first and last offset in A).
- * Finally, it removes any batches where the lastOffset < startOffset, if
the startOffset > -1.
- * @param currentBatch - collection containing current soft state of
batches
- * @param newBatch - collection containing batches in incoming request
+ * This method checks any overlap between current state batches and new
state batches.
+ * Based on various conditions it creates new non-overlapping records
preferring new batches.
+ * Finally, it removes any batches where the lastOffset < startOffset, if
the startOffset > -1 and
+ * merges any contiguous intervals with same state.
+ * @param batchesSoFar - collection containing current soft state of
batches
+ * @param newBatches - collection containing batches in incoming request
* @param startOffset - startOffset to consider when removing old batches.
* @return List containing combined batches
*/
- private static List<PersisterOffsetsStateBatch> combineStateBatches(
- Collection<PersisterOffsetsStateBatch> currentBatch,
- Collection<PersisterOffsetsStateBatch> newBatch,
+ // visibility for testing
+ static List<PersisterStateBatch> combineStateBatches(
+ List<PersisterStateBatch> batchesSoFar,
+ List<PersisterStateBatch> newBatches,
long startOffset
) {
- currentBatch.removeAll(newBatch);
- List<PersisterOffsetsStateBatch> batchesToAdd = new
LinkedList<>(currentBatch);
- batchesToAdd.addAll(newBatch);
- // Any batches where the last offset is < the current start offset
- // are now expired. We should remove them from the persister.
+ // will take care of overlapping batches
+ Queue<PersisterStateBatch> batchQueue = new LinkedList<>(
+ mergeBatches(
+ pruneBatches(
+ getSortedList(batchesSoFar),
+ startOffset
+ )
+ ));
+
+ // will take care of overlapping batches
+ List<PersisterStateBatch> modifiedNewBatches = new ArrayList<>(
+ mergeBatches(
+ pruneBatches(
+ getSortedList(newBatches),
+ startOffset
+ )
+ ));
+
+ for (PersisterStateBatch batch : modifiedNewBatches) {
+ for (int i = 0; i < batchQueue.size(); i++) {
+ PersisterStateBatch cur = batchQueue.poll();
+ // cur batch under inspection has no overlap with the new one
+ // we will need to add to our result
+ if (batch.lastOffset() < cur.firstOffset() ||
batch.firstOffset() > cur.lastOffset()) {
+ batchQueue.add(cur);
+ continue;
+ }
+
+ // Covers cases where we need to create a new interval
+ // from the current one such that they do not
+ // overlap with the new one.
+ // Following cases will not produce any new records so need
not be handled.
+ // cur: ____ ______ ______ _____
+ // new: ________ ______ _________ _________
+
+
+ // covers
+ // cur: ______ _____ _____ ______
+ // batch: ___ _____ ___ ___
+ if (batch.firstOffset() >= cur.firstOffset() &&
batch.lastOffset() <= cur.lastOffset()) {
+ // extra batch needs to be created
+ if (batch.firstOffset() > cur.firstOffset()) {
+ batchQueue.add(
+ new PersisterStateBatch(
+ cur.firstOffset(),
+ batch.firstOffset() - 1,
+ cur.deliveryState(),
+ cur.deliveryCount()
+ )
+ );
+ }
+
+ // extra batch needs to be created
+ if (batch.lastOffset() < cur.lastOffset()) {
+ batchQueue.add(
+ new PersisterStateBatch(
+ batch.lastOffset() + 1,
+ cur.lastOffset(),
+ cur.deliveryState(),
+ cur.deliveryCount()
+ )
+ );
+ }
+ } else if (batch.firstOffset() < cur.firstOffset() &&
batch.lastOffset() < cur.lastOffset()) {
+ // covers
+ // ______
+ //____
+ batchQueue.add(new PersisterStateBatch(
+ batch.lastOffset() + 1,
+ cur.lastOffset(),
+ cur.deliveryState(),
+ cur.deliveryCount()
+ ));
+ } else if (batch.firstOffset() > cur.firstOffset() &&
batch.lastOffset() > cur.lastOffset()) {
+ // covers
+ // ______
+ // _______
+ batchQueue.add(new PersisterStateBatch(
+ cur.firstOffset(),
+ batch.firstOffset() - 1,
+ cur.deliveryState(),
+ cur.deliveryCount()
+ ));
+ }
+ }
+ batchQueue.add(batch);
+ }
+
+ // sort, prune and merge intervals
+ return mergeBatches(
+ pruneBatches(
+ getSortedList(batchQueue),
+ startOffset
+ )
+ );
+ }
+
+ private static List<PersisterStateBatch>
getSortedList(Collection<PersisterStateBatch> collection) {
+ List<PersisterStateBatch> finalList = new ArrayList<>(collection);
+ finalList.sort(PersisterStateBatch::compareTo);
+ return finalList;
+ }
+
+ // assumes sorted input
+ private static List<PersisterStateBatch>
mergeBatches(List<PersisterStateBatch> batches) {
+ if (batches.size() < 2) {
+ return batches;
+ }
+ Stack<PersisterStateBatch> stack = new Stack<>();
+ stack.add(batches.get(0));
Review Comment:
Can't this be `batches.remove(0)`? Otherwise, the first element will be
added to the stack and also the initial candidate in the loop.
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