`commitAsync()` in `onPartitionsRevoked()`

[demos/kafka/training] / src / main / java / de / juplo / kafka / ApplicationRebalanceListener.java

diff --git a/src/main/java/de/juplo/kafka/ApplicationRebalanceListener.java b/src/main/java/de/juplo/kafka/ApplicationRebalanceListener.java
index cd9da64..9e75112 100644 (file)
--- a/src/main/java/de/juplo/kafka/ApplicationRebalanceListener.java
+++ b/src/main/java/de/juplo/kafka/ApplicationRebalanceListener.java
@@ -3,51 +3,50 @@ package de.juplo.kafka;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.kafka.clients.consumer.Consumer;
+import org.apache.kafka.clients.consumer.ConsumerRebalanceListener;
 import org.apache.kafka.common.TopicPartition;
 
 import java.time.Clock;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.*;
+import java.util.concurrent.CountDownLatch;
 
 
 @RequiredArgsConstructor
 @Slf4j
-public class ApplicationRebalanceListener implements PollIntervalAwareConsumerRebalanceListener
+public class ApplicationRebalanceListener implements ConsumerRebalanceListener
 {
+  private final Consumer consumer;
   private final ApplicationRecordHandler recordHandler;
   private final AdderResults adderResults;
   private final StateRepository stateRepository;
   private final String id;
-  private final String topic;
-  private final Clock clock;
-  private final Duration commitInterval;
-  private final Consumer<String, String> consumer;
 
   private final Set<Integer> partitions = new HashSet<>();
 
-  private Instant lastCommit = Instant.EPOCH;
-  private boolean commitsEnabled = true;
-
   @Override
   public void onPartitionsAssigned(Collection<TopicPartition> partitions)
   {
     partitions.forEach(tp ->
     {
       Integer partition = tp.partition();
+      log.info("{} - adding partition: {}", id, partition);
       this.partitions.add(partition);
       StateDocument document =
           stateRepository
               .findById(Integer.toString(partition))
               .orElse(new StateDocument(partition));
-      log.info("{} - adding partition: {}, offset={}", id, partition, document.offset);
-      if (document.offset >= 0)
+      recordHandler.addPartition(partition, document.state);
+      for (String user : document.state.keySet())
       {
-        // Only seek, if a stored offset was found
-        // Otherwise: Use initial offset, generated by Kafka
-        consumer.seek(tp, document.offset);
+        log.info(
+            "{} - Restored state for partition={}|user={}: {}",
+            id,
+            partition,
+            user,
+            document.state.get(user));
       }
-      recordHandler.addPartition(partition, document.state);
       adderResults.addPartition(partition, document.results);
     });
   }
@@ -55,61 +54,55 @@ public class ApplicationRebalanceListener implements PollIntervalAwareConsumerRe
   @Override
   public void onPartitionsRevoked(Collection<TopicPartition> partitions)
   {
-    partitions.forEach(tp ->
+    log.info("{} - Commiting offsets for all previously assigned partitions", id);
+    CountDownLatch commitDone = new CountDownLatch(1);
+    consumer.commitAsync((offsets, e) ->
     {
-      Integer partition = tp.partition();
-      this.partitions.remove(partition);
-      Long offset = consumer.position(tp);
-      log.info(
-          "{} - removing partition: {}, offset of next message {})",
-          id,
-          partition,
-          offset);
-      if (commitsEnabled)
+      commitDone.countDown();
+      if (e == null)
       {
-        Map<String, AdderResult> state = recordHandler.removePartition(partition);
-        Map<String, List<AdderResult>> results = adderResults.removePartition(partition);
-        stateRepository.save(new StateDocument(partition, state, results, offset));
+        log.error("{} - Could not commit offsets to Kafka!", id, e);
       }
       else
       {
-        log.info("Offset commits are disabled! Last commit: {}", lastCommit);
+        offsets.entrySet().stream().forEach(entry ->
+        {
+          log.info("{} - Commited offset for {}: {}", id, entry.getKey(), entry.getValue());
+        });
       }
     });
-  }
 
+    partitions.forEach(tp ->
+    {
+      Integer partition = tp.partition();
+      log.info("{} - removing partition: {}", id, partition);
+      this.partitions.remove(partition);
+      Map<String, AdderResult> state = recordHandler.removePartition(partition);
+      for (String user : state.keySet())
+      {
+        log.info(
+            "{} - Saved state for partition={}|user={}: {}",
+            id,
+            partition,
+            user,
+            state.get(user));
+      }
+      Map<String, List<AdderResult>> results = adderResults.removePartition(partition);
+      stateRepository.save(new StateDocument(partition, state, results));
+    });
 
-  @Override
-  public void beforeNextPoll()
-  {
-    if (!commitsEnabled)
+    try
     {
-      log.info("Offset commits are disabled! Last commit: {}", lastCommit);
-      return;
+      log.debug("{} - Waiting for async commit to complete", id);
+      commitDone.await();
     }
-
-    if (lastCommit.plus(commitInterval).isBefore(clock.instant()))
+    catch (InterruptedException e)
     {
-      log.debug("Storing data and offsets, last commit: {}", lastCommit);
-      partitions.forEach(partition -> stateRepository.save(
-          new StateDocument(
-              partition,
-              recordHandler.getState(partition).getState(),
-              adderResults.getState(partition),
-              consumer.position(new TopicPartition(topic, partition)))));
-      lastCommit = clock.instant();
+      log.warn(
+        "{} - Interrupted while waiting for async commit in onPartitionsRevoked({})",
+        id,
+        partitions,
+        e);
     }
   }
-
-  @Override
-  public void enableCommits()
-  {
-    commitsEnabled = true;
-  }
-
-  @Override
-  public void disableCommits()
-  {
-    commitsEnabled = false;
-  }
 }