aromanenko-dev commented on a change in pull request #13710:
URL: https://github.com/apache/beam/pull/13710#discussion_r560272725
##########
File path:
sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/KafkaIO.java
##########
@@ -1402,6 +1407,15 @@ public void populateDisplayData(DisplayData.Builder
builder) {
return toBuilder().setConsumerFactoryFn(consumerFactoryFn).build();
}
+ /**
+ * A custom {@link SerializableFunction} that determines whether the
{@link ReadFromKafkaDoFn}
+ * should stop reading from the given {@link TopicPartition}.
+ */
+ public ReadSourceDescriptors<K, V> withCheckStopReadingFn(
Review comment:
Could you add an example to the main `KafkaIO` Javadoc how to use this
functionality to make it more clear for users?
##########
File path:
sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/ReadFromKafkaDoFn.java
##########
@@ -288,6 +316,19 @@ public ProcessContinuation processElement(
Optional.ofNullable(watermarkEstimator.currentWatermark()));
}
try (Consumer<byte[], byte[]> consumer =
consumerFactoryFn.apply(updatedConsumerConfig)) {
+ // Check whether current TopicPartition is still available to read.
+ Set<TopicPartition> existingTopicPartitions = new HashSet<>();
+ for (List<PartitionInfo> topicPartitionList :
consumer.listTopics().values()) {
Review comment:
How often `consumer.listTopics()` will be called? Won't it affect a
performance? Will it make sense to cache the result?
##########
File path:
sdks/java/io/kafka/src/main/java/org/apache/beam/sdk/io/kafka/ReadFromKafkaDoFn.java
##########
@@ -288,6 +316,19 @@ public ProcessContinuation processElement(
Optional.ofNullable(watermarkEstimator.currentWatermark()));
}
try (Consumer<byte[], byte[]> consumer =
consumerFactoryFn.apply(updatedConsumerConfig)) {
+ // Check whether current TopicPartition is still available to read.
+ Set<TopicPartition> existingTopicPartitions = new HashSet<>();
+ for (List<PartitionInfo> topicPartitionList :
consumer.listTopics().values()) {
+ topicPartitionList.forEach(
+ partitionInfo -> {
+ existingTopicPartitions.add(
+ new TopicPartition(partitionInfo.topic(),
partitionInfo.partition()));
+ });
+ }
+ if
(!existingTopicPartitions.contains(kafkaSourceDescriptor.getTopicPartition())) {
+ return ProcessContinuation.stop();
Review comment:
What's about checkpointing for already read records in this case? Are
they going to be processed?
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