High-level KafkaConsumer (for brokers 0.9 and later) More...

#include <rdkafkacpp.h>

Inheritance diagram for RdKafka::KafkaConsumer:

Collaboration diagram for RdKafka::KafkaConsumer:

Public Member Functions
virtual ErrorCode	assignment (std::vector< RdKafka::TopicPartition *> &partitions)=0
	Returns the current partition assignment as set by RdKafka::KafkaConsumer::assign()

virtual ErrorCode	subscription (std::vector< std::string > &topics)=0
	Returns the current subscription as set by RdKafka::KafkaConsumer::subscribe()

virtual ErrorCode	subscribe (const std::vector< std::string > &topics)=0
	Update the subscription set to `topics`. More...

virtual ErrorCode	unsubscribe ()=0
	Unsubscribe from the current subscription set.

virtual ErrorCode	assign (const std::vector< TopicPartition *> &partitions)=0
	Update the assignment set to `partitions`. More...

virtual ErrorCode	unassign ()=0
	Stop consumption and remove the current assignment.

virtual Message *	consume (int timeout_ms)=0
	Consume message or get error event, triggers callbacks. More...

virtual ErrorCode	commitSync ()=0
	Commit offsets for the current assignment. More...

virtual ErrorCode	commitAsync ()=0
	Asynchronous version of RdKafka::KafkaConsumer::CommitSync() More...

virtual ErrorCode	commitSync (Message *message)=0
	Commit offset for a single topic+partition based on `message`. More...

virtual ErrorCode	commitAsync (Message *message)=0
	Commit offset for a single topic+partition based on `message`. More...

virtual ErrorCode	commitSync (std::vector< TopicPartition *> &offsets)=0
	Commit offsets for the provided list of partitions. More...

virtual ErrorCode	commitAsync (const std::vector< TopicPartition *> &offsets)=0
	Commit offset for the provided list of partitions. More...

virtual ErrorCode	committed (std::vector< TopicPartition *> &partitions, int timeout_ms)=0
	Retrieve committed offsets for topics+partitions. More...

virtual ErrorCode	position (std::vector< TopicPartition *> &partitions)=0
	Retrieve current positions (offsets) for topics+partitions. More...

virtual ErrorCode	close ()=0
	Close and shut down the proper. More...

Public Member Functions inherited from RdKafka::Handle
virtual const std::string	name () const =0

virtual const std::string	memberid () const =0
	Returns the client's broker-assigned group member id. More...

virtual int	poll (int timeout_ms)=0
	Polls the provided kafka handle for events. More...

virtual int	outq_len ()=0
	Returns the current out queue length. More...

virtual ErrorCode	metadata (bool all_topics, const Topic only_rkt, Metadata *metadatap, int timeout_ms)=0
	Request Metadata from broker. More...

virtual ErrorCode	pause (std::vector< TopicPartition *> &partitions)=0
	Pause producing or consumption for the provided list of partitions. More...

virtual ErrorCode	resume (std::vector< TopicPartition *> &partitions)=0
	Resume producing or consumption for the provided list of partitions. More...

virtual ErrorCode	query_watermark_offsets (const std::string &topic, int32_t partition, int64_t low, int64_t high, int timeout_ms)=0
	Query broker for low (oldest/beginning) and high (newest/end) offsets for partition. More...

virtual ErrorCode	get_watermark_offsets (const std::string &topic, int32_t partition, int64_t low, int64_t high)=0
	Get last known low (oldest/beginning) and high (newest/end) offsets for partition. More...

Static Public Member Functions
static KafkaConsumer *	create (Conf *conf, std::string &errstr)
	Creates a KafkaConsumer. More...

Detailed Description

High-level KafkaConsumer (for brokers 0.9 and later)

Remarks: Requires Apache Kafka >= 0.9.0 brokers

Currently supports the range and roundrobin partition assignment strategies (see partition.assignment.strategy)

Member Function Documentation

◆ create()

static KafkaConsumer* RdKafka::KafkaConsumer::create	(	Conf *	conf,
		std::string &	errstr
	)

static

Creates a KafkaConsumer.

The conf object must have group.id set to the consumer group to join.

Use RdKafka::KafkaConsumer::close() to shut down the consumer.

See also: RdKafka::RebalanceCb; CONFIGURATION.md for group.id, session.timeout.ms, partition.assignment.strategy, etc.

◆ subscribe()

virtual ErrorCode RdKafka::KafkaConsumer::subscribe ( const std::vector< std::string > & topics )

pure virtual

Update the subscription set to topics.

Any previous subscription will be unassigned and unsubscribed first.

The subscription set denotes the desired topics to consume and this set is provided to the partition assignor (one of the elected group members) for all clients which then uses the configured partition.assignment.strategy to assign the subscription sets's topics's partitions to the consumers, depending on their subscription.

The result of such an assignment is a rebalancing which is either handled automatically in librdkafka or can be overriden by the application by providing a RdKafka::RebalanceCb.

The rebalancing passes the assigned partition set to RdKafka::KafkaConsumer::assign() to update what partitions are actually being fetched by the KafkaConsumer.

Regex pattern matching automatically performed for topics prefixed with "^" (e.g. "^myPfx[0-9]_.*"

◆ assign()

virtual ErrorCode RdKafka::KafkaConsumer::assign ( const std::vector< TopicPartition *> & partitions )

pure virtual

Update the assignment set to partitions.

The assignment set is the set of partitions actually being consumed by the KafkaConsumer.

◆ consume()

virtual Message* RdKafka::KafkaConsumer::consume ( int timeout_ms )

pure virtual

Consume message or get error event, triggers callbacks.

Will automatically call registered callbacks for any such queued events, including RdKafka::RebalanceCb, RdKafka::EventCb, RdKafka::OffsetCommitCb, etc.

Remarks: Use delete to free the message.; An application should make sure to call consume() at regular intervals, even if no messages are expected, to serve any queued callbacks waiting to be called. This is especially important when a RebalanceCb has been registered as it needs to be called and handled properly to synchronize internal consumer state.; Application MUST NOT call poll() on KafkaConsumer objects.

Returns

One of:

proper message (RdKafka::Message::err() is ERR_NO_ERROR)
error event (RdKafka::Message::err() is != ERR_NO_ERROR)
timeout due to no message or event in timeout_ms (RdKafka::Message::err() is ERR__TIMED_OUT)

◆ commitSync() [1/3]

virtual ErrorCode RdKafka::KafkaConsumer::commitSync ( )

pure virtual

Commit offsets for the current assignment.

Remarks: This is the synchronous variant that blocks until offsets are committed or the commit fails (see return value).; If a RdKafka::OffsetCommitCb callback is registered it will be called with commit details on a future call to RdKafka::KafkaConsumer::consume()

Returns: ERR_NO_ERROR or error code.

◆ commitAsync() [1/3]

virtual ErrorCode RdKafka::KafkaConsumer::commitAsync ( )

pure virtual

Asynchronous version of RdKafka::KafkaConsumer::CommitSync()

See also: RdKafka::KafkaConsummer::commitSync()

◆ commitSync() [2/3]

virtual ErrorCode RdKafka::KafkaConsumer::commitSync ( Message * message )

pure virtual

Commit offset for a single topic+partition based on message.

Remarks: This is the synchronous variant.

See also: RdKafka::KafkaConsummer::commitSync()

◆ commitAsync() [2/3]

virtual ErrorCode RdKafka::KafkaConsumer::commitAsync ( Message * message )

pure virtual

Commit offset for a single topic+partition based on message.

Remarks: This is the asynchronous variant.

See also: RdKafka::KafkaConsummer::commitSync()

◆ commitSync() [3/3]

virtual ErrorCode RdKafka::KafkaConsumer::commitSync ( std::vector< TopicPartition *> & offsets )

pure virtual

Commit offsets for the provided list of partitions.

Remarks: This is the synchronous variant.

◆ commitAsync() [3/3]

virtual ErrorCode RdKafka::KafkaConsumer::commitAsync ( const std::vector< TopicPartition *> & offsets )

pure virtual

Commit offset for the provided list of partitions.

Remarks: This is the asynchronous variant.

◆ committed()

virtual ErrorCode RdKafka::KafkaConsumer::committed	(	std::vector< TopicPartition *> &	partitions,
		int	timeout_ms
	)

pure virtual

Retrieve committed offsets for topics+partitions.

Returns: RD_KAFKA_RESP_ERR_NO_ERROR on success in which case the offset or err field of each partitions' element is filled in with the stored offset, or a partition specific error. Else returns an error code.

◆ position()

virtual ErrorCode RdKafka::KafkaConsumer::position ( std::vector< TopicPartition *> & partitions )

pure virtual

Retrieve current positions (offsets) for topics+partitions.

Returns: RD_KAFKA_RESP_ERR_NO_ERROR on success in which case the offset or err field of each partitions' element is filled in with the stored offset, or a partition specific error. Else returns an error code.

◆ close()

virtual ErrorCode RdKafka::KafkaConsumer::close ( )

pure virtual

Close and shut down the proper.

For pausing and resuming consumption, see

See also

RdKafka::Handle::pause() and RdKafka::Handle::resume() This call will block until the following operations are finished:

Trigger a local rebalance to void the current assignment
Stop consumption for current assignment
Commit offsets
Leave group

The maximum blocking time is roughly limited to session.timeout.ms.

Remarks: Callbacks, such as RdKafka::RebalanceCb and RdKafka::OffsetCommitCb, etc, may be called.; The consumer object must later be freed with delete

The documentation for this class was generated from the following file:

src-cpp/rdkafkacpp.h

Public Member Functions

Static Public Member Functions

Detailed Description

Member Function Documentation

◆ create()

◆ subscribe()

◆ assign()

◆ consume()

◆ commitSync() [1/3]

◆ commitAsync() [1/3]

◆ commitSync() [2/3]

◆ commitAsync() [2/3]

◆ commitSync() [3/3]

◆ commitAsync() [3/3]

◆ committed()

◆ position()

◆ close()