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KAFKA-14035: Fix NPE caused by missing null check in SnapshottableHashTable::mergeFrom() #12371

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Merged
hachikuji merged 1 commit into from
Jul 1, 2022
Merged

KAFKA-14035: Fix NPE caused by missing null check in SnapshottableHashTable::mergeFrom() #12371

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22 changes: 13 additions & 9 deletions metadata/src/main/java/org/apache/kafka/timeline/SnapshottableHashTable.java
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Original file line number Diff line number Diff line change
Expand Up @@ -111,15 +111,19 @@ static class HashTier<T extends SnapshottableHashTable.ElementWithStartEpoch> im
@Override
public void mergeFrom(long epoch, Delta source) {
HashTier<T> other = (HashTier<T>) source;
List<T> list = new ArrayList<>();
Object[] otherElements = other.deltaTable.baseElements();
for (int slot = 0; slot < otherElements.length; slot++) {
BaseHashTable.unpackSlot(list, otherElements, slot);
for (T element : list) {
// When merging in a later hash tier, we want to keep only the elements
// that were present at our epoch.
if (element.startEpoch() <= epoch) {
deltaTable.baseAddOrReplace(element);
// As an optimization, the deltaTable might not exist for a new key
// as there is no previous value
if (other.deltaTable != null) {
List<T> list = new ArrayList<>();
Object[] otherElements = other.deltaTable.baseElements();
for (int slot = 0; slot < otherElements.length; slot++) {
BaseHashTable.unpackSlot(list, otherElements, slot);
for (T element : list) {
// When merging in a later hash tier, we want to keep only the elements
// that were present at our epoch.
if (element.startEpoch() <= epoch) {
deltaTable.baseAddOrReplace(element);
}
}
}
}
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19 changes: 19 additions & 0 deletions metadata/src/test/java/org/apache/kafka/timeline/SnapshottableHashTableTest.java
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Expand Up @@ -97,6 +97,25 @@ public void testEmptyTable() {
new SnapshottableHashTable<>(registry, 1);
assertEquals(0, table.snapshottableSize(Long.MAX_VALUE));
}
@Test
public void testDeleteOnEmptyDeltaTable() {
// A simple test case to validate the behavior of the TimelineHashSet
// when the deltaTable for a snapshot is null
SnapshotRegistry registry = new SnapshotRegistry(new LogContext());
TimelineHashSet<String> set = new TimelineHashSet<>(registry, 5);

registry.getOrCreateSnapshot(100);
set.add("bar");
registry.getOrCreateSnapshot(200);
set.add("baz");
registry.revertToSnapshot(100);
assertTrue(set.isEmpty());
set.add("foo");
registry.getOrCreateSnapshot(300);
set.remove("bar");
registry.revertToSnapshot(100);
assertTrue(set.isEmpty());
}

@Test
public void testAddAndRemove() {
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