consumer

Documentation

Index

• type Consumer
• type Message

Types

type Consumer

type Consumer interface {
	io.Closer

	// Name returns the name of this consumer group.
	Name() string
	// Topics returns the names of the topics being consumed.
	Topics() []string
	// Errors returns a channel of errors for the topic. To prevent deadlocks,
	// users must read from the error channel.
	//
	// All errors returned from this channel can be safely cast to the
	// consumer.Error interface, which allows structured access to the topic
	// name and partition number.
	Errors() <-chan error
	// Closed returns a channel that unblocks when the consumer successfully shuts
	// down.
	Closed() <-chan struct{}
	// Messages returns a channel of messages for the topic.
	//
	// If the consumer is not configured with nonzero buffer size, the Errors()
	// channel must be read in conjunction with Messages() to prevent deadlocks.
	Messages() <-chan Message
	// CommitUpTo marks this message and all previous messages in the same partition
	// as processed. The last processed offset for each partition is periodically
	// flushed to ZooKeeper; on startup, consumers begin processing after the last
	// stored offset.
	CommitUpTo(Message) error
}

A Consumer allows users to read and process messages from a Kafka topic. Consumer processes within the same group use ZooKeeper to negotiate partition ownership, so each process sees a stream of messages from one or more partitions. Within a partition, messages are linearizable.

type Message

type Message interface {
	// Key is a mutable reference to the message's key.
	Key() []byte
	// Value is a mutable reference to the message's value.
	Value() []byte
	// Topic is the topic from which the message was read.
	Topic() string
	// Partition is the ID of the partition from which the message was read.
	Partition() int32
	// Offset is the message's offset.
	Offset() int64
	// Ack the message
	Ack()
	// Nack the message
	Nack()
	// Cluster is the message's originated cluster.
	Cluster() string
}

Message is a single message pulled off a Kafka topic.