Re: [PR] Kafka Connect: Fix coordinator potentially committing files from prior commit in certain rebalance scenarios [iceberg]

["amogh-jahagirdar (via GitHub)" <gi...@apache.org>]

amogh-jahagirdar commented on code in PR #17713:
URL: https://github.com/apache/iceberg/pull/17713#discussion_r4032523362


##########
kafka-connect/kafka-connect/src/main/java/org/apache/iceberg/connect/channel/Channel.java:
##########
@@ -119,21 +120,32 @@ protected void send(List<Event> events, Map<TopicPartition, Offset> sourceOffset
   protected void consumeAvailable(Duration pollDuration) {
     ConsumerRecords<String, byte[]> records = consumer.poll(pollDuration);
     while (!records.isEmpty()) {
-      records.forEach(
-          record -> {
-            // the consumer stores the offsets that corresponds to the next record to consume,
-            // so increment the record offset by one
-            controlTopicOffsets.put(record.partition(), record.offset() + 1);
-
-            Event event = AvroUtil.decode(record.value());
-
-            if (event.groupId().equals(connectGroupId)) {
-              LOG.debug("Received event of type: {}", event.type().name());
-              if (receive(new Envelope(event, record.partition(), record.offset()))) {
-                LOG.info("Handled event of type: {}", event.type().name());
-              }
-            }
-          });
+      for (ConsumerRecord<String, byte[]> record : records) {
+        Long nextOffset = controlTopicOffsets.get(record.partition());
+        // A rebalance may revoke and later reassign this control partition to the same

Review Comment:
   Nit:
   ```
   // A rebalance can rewind the consumer to the committed offset, which can lag the in-memory
   //position. Skip already-processed records.
   ```



##########
kafka-connect/kafka-connect/src/test/java/org/apache/iceberg/connect/channel/TestControlTopicReplay.java:
##########
@@ -0,0 +1,211 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.iceberg.connect.channel;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+import java.io.IOException;
+import java.time.Duration;
+import java.util.List;
+import java.util.Optional;
+import java.util.UUID;
+import org.apache.iceberg.DataFile;
+import org.apache.iceberg.DataFiles;
+import org.apache.iceberg.FileFormat;
+import org.apache.iceberg.FileScanTask;
+import org.apache.iceberg.PartitionSpec;
+import org.apache.iceberg.Snapshot;
+import org.apache.iceberg.connect.IcebergSinkConfig;
+import org.apache.iceberg.connect.events.AvroUtil;
+import org.apache.iceberg.connect.events.DataComplete;
+import org.apache.iceberg.connect.events.DataWritten;
+import org.apache.iceberg.connect.events.Event;
+import org.apache.iceberg.connect.events.StartCommit;
+import org.apache.iceberg.connect.events.TableReference;
+import org.apache.iceberg.connect.events.TopicPartitionOffset;
+import org.apache.iceberg.io.CloseableIterable;
+import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
+import org.apache.iceberg.relocated.com.google.common.collect.ImmutableSet;
+import org.apache.iceberg.relocated.com.google.common.collect.Lists;
+import org.apache.iceberg.types.Types.StructType;
+import org.apache.kafka.clients.admin.MemberAssignment;
+import org.apache.kafka.clients.admin.MemberDescription;
+import org.apache.kafka.clients.consumer.ConsumerRecord;
+import org.apache.kafka.common.TopicPartition;
+import org.apache.kafka.connect.sink.SinkTaskContext;
+import org.junit.jupiter.api.Test;
+
+class TestControlTopicReplay extends ChannelTestBase {
+
+  @Test
+  void handlesReplayedControlRecordsOnce() {
+    TrackingChannel channel =
+        new TrackingChannel(config, clientFactory, mock(SinkTaskContext.class));
+    channel.start();
+    initConsumer();
+
+    addStartCommit(0L);
+    addStartCommit(1L);
+    channel.process();
+
+    assertThat(channel.receivedCount()).isEqualTo(2);
+    assertThat(channel.nextOffset(0)).isEqualTo(2L);
+
+    consumer.seek(new TopicPartition(CTL_TOPIC_NAME, 0), 0L);
+    addStartCommit(0L);
+    addStartCommit(1L);
+    channel.process();
+
+    assertThat(channel.receivedCount()).isEqualTo(2);
+    assertThat(channel.nextOffset(0)).isEqualTo(2L);
+  }
+
+  @Test
+  void doesNotCommitReplayedDataFilesTwice() throws IOException {
+    when(config.commitIntervalMs()).thenReturn(0);
+    when(config.commitTimeoutMs()).thenReturn(Integer.MAX_VALUE);
+
+    MemberAssignment assignment =
+        new MemberAssignment(
+            ImmutableSet.of(
+                new TopicPartition(SRC_TOPIC_NAME, 0),
+                new TopicPartition(SRC_TOPIC_NAME, 1),
+                new TopicPartition(SRC_TOPIC_NAME, 2)));
+    MemberDescription member =
+        new MemberDescription(null, Optional.empty(), null, null, assignment);
+    Coordinator coordinator =
+        new Coordinator(
+            catalog, config, ImmutableList.of(member), clientFactory, mock(SinkTaskContext.class));
+    coordinator.start();
+    initConsumer();
+    coordinator.process();
+
+    UUID commitId =
+        ((StartCommit) AvroUtil.decode(producer.history().get(0).value()).payload()).commitId();
+    DataFile file1 = dataFile("path/to/file-1.parquet");
+    DataFile file2 = dataFile("path/to/file-2.parquet");
+
+    addDataWritten(0L, commitId, file1);
+    addDataComplete(1L, commitId, 0);
+    addDataWritten(2L, commitId, file2);
+    addDataComplete(3L, commitId, 1);
+    coordinator.process();
+

Review Comment:
   minor: maybe a comment like
   
   ```
   // Simulate a rebalance by rewinding the consumer and replaying records before the commit
   // is ready, since a snapshot would record these offsets and filter them.
   ```



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