Kafka_lwtSourceval consume_batch :
?timeout_ms:int ->
?msg_count:int ->
Kafka.topic ->
Kafka.partition ->
Kafka.message list Lwt.tval consume_batch_queue :
?timeout_ms:int ->
?msg_count:int ->
Kafka.queue ->
Kafka.message list Lwt.tWait that messages are delivered (waiting that less than max_outq_len messages are pending).