msgfetcher

type Factory interface {
	// Spawn creates and starts a fetcher instance that reads messages from the
	// given topic-partition starting from the specified offset. It will return
	// an error if there is an fetcher instance reading from the topic-partition
	// already.
	//
	// If the given offset does not exists in the topic-partition, then a real
	// offset that the fetcher will start reading from is determined as follows:
	//  * if the given offset equals to sarama.OffsetOldest or it is smaller
	//    then the oldest partition offset, then the oldest partition offset is
	//    selected;
	//  * if the given offset equals to sarama.OffsetNewest, or it is larger
	//    then the newest partition offset, then the newest partition offset is
	//    selected.
	// The real offset value is returned by the function.
	Spawn(parentActDesc *actor.Descriptor, topic string, partition int32, offset int64) (T, int64, error)

	// Stop shuts down the consumer. It must be called after all child partition
	// consumers have already been closed.
	Stop()
}

type T interface {
	// Messages returns the read channel for the messages that are fetched from
	// the topic partition.
	Messages() <-chan consumer.Message

	// Stop synchronously stops the partition consumer. It must be called
	// before the factory that created the instance can be stopped.
	Stop()
}