Partitioner callback
Return the partition to use for \p key in \p topic.
The \p msg_opaque is the same \p msg_opaque provided in the Producer::produce() call.
Note: \p key may be null or the empty.
Must return a value between 0 and \p partition_cnt (non-inclusive). May return RD_KAFKA_PARTITION_UA (-1) if partitioning failed.
The callback may use Topic::partition_available() to check if a partition has an active leader broker.
See Implementation
Partitioner callback
Return the partition to use for \p key in \p topic.
The \p msg_opaque is the same \p msg_opaque provided in the Producer::produce() call.
Note: \p key may be null or the empty.
Must return a value between 0 and \p partition_cnt (non-inclusive). May return RD_KAFKA_PARTITION_UA (-1) if partitioning failed.