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https://issues.apache.org/jira/browse/TWILL-199?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15799721#comment-15799721
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ASF GitHub Bot commented on TWILL-199:
--------------------------------------
Github user chtyim commented on a diff in the pull request:
https://github.com/apache/twill/pull/16#discussion_r94688950
--- Diff:
twill-core/src/test/java/org/apache/twill/kafka/client/KafkaTest.java ---
@@ -170,11 +172,57 @@ public void testKafkaClient() throws Exception {
Cancellable cancel = kafkaClient.getConsumer().prepare().add(topic, 0,
0).consume(new KafkaConsumer
.MessageCallback() {
@Override
- public void onReceived(Iterator<FetchedMessage> messages) {
+ public long onReceived(Iterator<FetchedMessage> messages, long
startOffset) {
+ long nextOffset = startOffset;
while (messages.hasNext()) {
-
LOG.info(Charsets.UTF_8.decode(messages.next().getPayload()).toString());
+ FetchedMessage message = messages.next();
+ LOG.info(Charsets.UTF_8.decode(message.getPayload()).toString());
latch.countDown();
}
+ return nextOffset;
+ }
+
+ @Override
+ public void finished() {
+ stopLatch.countDown();
+ }
+ });
+
+ Assert.assertTrue(latch.await(5, TimeUnit.SECONDS));
+ cancel.cancel();
+ Assert.assertTrue(stopLatch.await(1, TimeUnit.SECONDS));
+ }
+
+ @Test
+ public void testKafkaClientSkipNext() throws Exception {
+ String topic = "testClient";
+ // Publish 30 messages with indecies the same as offsets within the
range 0 - 29
+ Thread t1 = createPublishThread(kafkaClient, topic, Compression.GZIP,
"GZIP Testing message", 10);
+ t1.start();
+ t1.join();
+ Thread t2 = createPublishThread(kafkaClient, topic, Compression.NONE,
"Testing message", 10, 10);
+ t2.start();
+ t2.join();
+ Thread t3 = createPublishThread(kafkaClient, topic,
Compression.SNAPPY, "Snappy Testing message", 10, 20);
+ t3.start();
+ t3.join();
+
+ // 15 messages will be counted since onReceived returns
`message.getNextOffset() + 1` as next offset to read
--- End diff --
I don't think the test is correct. You published 30 messages in three
message set, hence the `onReceived` method will be called three times. The
first time with messages 0-9 and you return 11. The second call with 11-19, and
you return 20. The last call with 21-29. So in total there will be more than 15
messages.
> Get next offset and handle offset error in KafkaConsumer.MessageCallback
> ------------------------------------------------------------------------
>
> Key: TWILL-199
> URL: https://issues.apache.org/jira/browse/TWILL-199
> Project: Apache Twill
> Issue Type: Improvement
> Reporter: Chengfeng Mao
>
> The method {{void onReceived(Iterator<FetchedMessage> messages)}} in
> {{KafkaConsumer.MessageCallback}} can be more flexible with the change to
> {{Long onReceived(Iterator<FetchedMessage> messages)}} so that it can provide
> additional functionalities:
> 1. To return the next offset to be fetched
> 2. To handle offset non-existence or offset mismatch error and take action on
> the error
> This method will return null for backward compatibility when it doesn't need
> to provide the next offset.
> In concrete implementation, a class of a new interface
> {{KafkaOffsetProvider}} can be added as a member in
> {{KafkaConsumer.MessageCallback}} to perform the offset error handling and
> provide the next offset. Besides, {{KafkaOffsetProvider}} also has methods to
> provide the following functionalities:
> 1. To fetch earliest/latest offset in Kafka
> 2. To find the offset of a message with timestamp equal to the given
> timestamp in Kafka
> For backward compatibility, if {{KafkaOffsetProvider}} instance is not
> provided, its default value will be null and none of its methods will be
> called.
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