Grant Henke created KAFKA-3563:
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Summary: Maintain MessageAndMetadata constructor compatibility
Key: KAFKA-3563
URL: https://issues.apache.org/jira/browse/KAFKA-3563
Project: Kafka
Issue Type: Improvement
Affects Versions: 0.10.0.0
Reporter: Grant Henke
Assignee: Grant Henke
Fix For: 0.10.0.0
The MessageAndMetadata constructor was changed to include timestamp information
as a part of KIP-32. Though the constructor may not be used in general client
usage, it may be used in unit tests or some advanced usage. We should maintain
compatibility if possible.
One example where the constructor is used is Apache Spark:
https://github.com/apache/spark/blob/master/external/kafka/src/main/scala/org/apache/spark/streaming/kafka/KafkaRDD.scala#L223-L225
The old constructor was:
{code}
MessageAndMetadata[K, V](topic: String,
partition: Int,
private val rawMessage: Message,
offset: Long,
keyDecoder: Decoder[K], valueDecoder: Decoder[V])
{code}
And after KIP-32 it is now:
{code}
MessageAndMetadata[K, V](topic: String,
partition: Int,
private val rawMessage: Message,
offset: Long,
timestamp: Long = Message.NoTimestamp,
timestampType: TimestampType = TimestampType.CREATE_TIME,
keyDecoder: Decoder[K], valueDecoder: Decoder[V])
{code}
Even though _timestamp_ and _timestampType_ have defaults, if _keyDecoder_ and
_valueDecoder_ were not accessed by name, then the new constructor is not
backwards compatible.
We can fix compatibility by moving the _timestamp_ and _timestampType_
parameters to the end of the constructor, or by providing a new constructor
without _timestamp_ and _timestampType_ that matches the old constructor.
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