[kafka] branch trunk updated: KAFKA-15271: Historicalterator can exposes elements that are too new (#14125)

[cmccabe]

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cmccabe pushed a commit to branch trunk
in repository https://gitbox.apache.org/repos/asf/kafka.git


The following commit(s) were added to refs/heads/trunk by this push:
     new 9bc4a2d4d1e KAFKA-15271: Historicalterator can exposes elements that 
are too new (#14125)
9bc4a2d4d1e is described below

commit 9bc4a2d4d1e9b4ce0f322ec6c604c7b7ac7c7d26
Author: Colin Patrick McCabe <cmcc...@apache.org>
AuthorDate: Tue Aug 8 16:36:59 2023 -0700

    KAFKA-15271: Historicalterator can exposes elements that are too new 
(#14125)
    
    A HistoricalIterator at epoch N is supposed to only reveal elements at 
epoch N or earlier. However,
    due to a bug, we sometimes will reveal elements which are at a newer epoch 
than N. The bug does
    not affect elements that are in the latest epoch (aka topTier). It only 
affects elements that are
    newer than N, but which do not persist until the latest epoch.  This PR 
fixes the bug and adds a
    unit test for this case.
    
    Reviewers: David Arthur <mum...@gmail.com>
---
 .../org/apache/kafka/timeline/SnapshottableHashTable.java |  6 ++++--
 .../apache/kafka/timeline/SnapshottableHashTableTest.java | 15 +++++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git 
a/server-common/src/main/java/org/apache/kafka/timeline/SnapshottableHashTable.java
 
b/server-common/src/main/java/org/apache/kafka/timeline/SnapshottableHashTable.java
index 9284d5964c5..2977e061643 100644
--- 
a/server-common/src/main/java/org/apache/kafka/timeline/SnapshottableHashTable.java
+++ 
b/server-common/src/main/java/org/apache/kafka/timeline/SnapshottableHashTable.java
@@ -261,8 +261,10 @@ class SnapshottableHashTable<T extends 
SnapshottableHashTable.ElementWithStartEp
                         int tierSlot = slot >>> shift;
                         BaseHashTable.unpackSlot(temp, 
deltaTable.baseElements(), tierSlot);
                         for (T object : temp) {
-                            if (BaseHashTable.findSlot(object, topTier.length) 
== slot) {
-                                ready.add(object);
+                            if (object.startEpoch() <= snapshot.epoch()) {
+                                if (BaseHashTable.findSlot(object, 
topTier.length) == slot) {
+                                    ready.add(object);
+                                }
                             }
                         }
                         temp.clear();
diff --git 
a/server-common/src/test/java/org/apache/kafka/timeline/SnapshottableHashTableTest.java
 
b/server-common/src/test/java/org/apache/kafka/timeline/SnapshottableHashTableTest.java
index 5f85463c15c..2d4a4cf9f04 100644
--- 
a/server-common/src/test/java/org/apache/kafka/timeline/SnapshottableHashTableTest.java
+++ 
b/server-common/src/test/java/org/apache/kafka/timeline/SnapshottableHashTableTest.java
@@ -275,6 +275,21 @@ public class SnapshottableHashTableTest {
         assertIteratorYields(table.snapshottableIterator(Long.MAX_VALUE));
     }
 
+    @Test
+    public void testIteratorAtOlderEpoch() {
+        SnapshotRegistry registry = new SnapshotRegistry(new LogContext());
+        SnapshottableHashTable<TestElement> table =
+                new SnapshottableHashTable<>(registry, 4);
+        assertNull(table.snapshottableAddOrReplace(E_3B));
+        registry.getOrCreateSnapshot(0);
+        assertNull(table.snapshottableAddOrReplace(E_1A));
+        registry.getOrCreateSnapshot(1);
+        assertEquals(E_1A, table.snapshottableAddOrReplace(E_1B));
+        registry.getOrCreateSnapshot(2);
+        assertEquals(E_1B, table.snapshottableRemove(E_1B));
+        assertIteratorYields(table.snapshottableIterator(1), E_3B, E_1A);
+    }
+
     /**
      * Assert that the given iterator contains the given elements, in any 
order.
      * We compare using reference equality here, rather than object equality.