RdKafka::Message Class Reference

Message object. More...

#include <rdkafkacpp.h>

Public Types
enum	Status {   MSG_STATUS_NOT_PERSISTED = 0 ,   MSG_STATUS_POSSIBLY_PERSISTED = 1 ,   MSG_STATUS_PERSISTED = 2 }
	Message persistence status can be used by the application to find out if a produced message was persisted in the topic log. More...

Public Member Functions
virtual std::string	errstr () const =0
	Accessor functions*. More...
virtual ErrorCode	err () const =0
virtual Topic *	topic () const =0
virtual std::string	topic_name () const =0
virtual int32_t	partition () const =0
virtual void *	payload () const =0
virtual size_t	len () const =0
virtual const std::string *	key () const =0
virtual const void *	key_pointer () const =0
virtual size_t	key_len () const =0
virtual int64_t	offset () const =0
virtual MessageTimestamp	timestamp () const =0
virtual void *	msg_opaque () const =0
virtual int64_t	latency () const =0
virtual struct rd_kafka_message_s *	c_ptr ()=0
	Returns the underlying librdkafka C rd_kafka_message_t handle. More...
virtual Status	status () const =0
	Returns the message's persistence status in the topic log.
virtual RdKafka::Headers *	headers ()=0
virtual RdKafka::Headers *	headers (RdKafka::ErrorCode *err)=0
virtual int32_t	broker_id () const =0

Detailed Description

Message object.

This object represents either a single consumed or produced message, or an event (err() is set).

An application must check RdKafka::Message::err() to see if the object is a proper message (error is RdKafka::ERR_NO_ERROR) or a an error event.

Member Enumeration Documentation

Status

enum RdKafka::Message::Status

Message persistence status can be used by the application to find out if a produced message was persisted in the topic log.

Enumerator
MSG_STATUS_NOT_PERSISTED	Message was never transmitted to the broker, or failed with an error indicating it was not written to the log. Application retry risks ordering, but not duplication.
MSG_STATUS_POSSIBLY_PERSISTED	Message was transmitted to broker, but no acknowledgement was received. Application retry risks ordering and duplication.
MSG_STATUS_PERSISTED	Message was written to the log and fully acknowledged. No reason for application to retry. Note: this value should only be trusted with acks=all.

Member Function Documentation

errstr()

virtual std::string RdKafka::Message::errstr ( ) const

pure virtual

Accessor functions*.

Remarks

Not all fields are present in all types of callbacks.

Returns

The error string if object represent an error event, else an empty string.

err()

virtual ErrorCode RdKafka::Message::err ( ) const

pure virtual

Returns

The error code if object represents an error event, else 0.

topic()

virtual Topic* RdKafka::Message::topic ( ) const

pure virtual

Returns

the RdKafka::Topic object for a message (if applicable), or NULL if a corresponding RdKafka::Topic object has not been explicitly created with RdKafka::Topic::create(). In this case use topic_name() instead.

topic_name()

virtual std::string RdKafka::Message::topic_name ( ) const

pure virtual

Returns

Topic name (if applicable, else empty string)

partition()

virtual int32_t RdKafka::Message::partition ( ) const

pure virtual

Returns

Partition (if applicable)

payload()

virtual void* RdKafka::Message::payload ( ) const

pure virtual

Returns

Message payload (if applicable)

len()

virtual size_t RdKafka::Message::len ( ) const

pure virtual

Returns

Message payload length (if applicable)

key()

virtual const std::string* RdKafka::Message::key ( ) const

pure virtual

Returns

Message key as string (if applicable)

key_pointer()

virtual const void* RdKafka::Message::key_pointer ( ) const

pure virtual

Returns

Message key as void pointer (if applicable)

key_len()

virtual size_t RdKafka::Message::key_len ( ) const

pure virtual

Returns

Message key's binary length (if applicable)

offset()

virtual int64_t RdKafka::Message::offset ( ) const

pure virtual

Returns

Message or error offset (if applicable)

timestamp()

virtual MessageTimestamp RdKafka::Message::timestamp ( ) const

pure virtual

Returns

Message timestamp (if applicable)

msg_opaque()

virtual void* RdKafka::Message::msg_opaque ( ) const

pure virtual

Returns

The msg_opaque as provided to RdKafka::Producer::produce()

latency()

virtual int64_t RdKafka::Message::latency ( ) const

pure virtual

Returns

the latency in microseconds for a produced message measured from the produce() call, or -1 if latency is not available.

c_ptr()

virtual struct rd_kafka_message_s* RdKafka::Message::c_ptr ( )

pure virtual

Returns the underlying librdkafka C rd_kafka_message_t handle.

Warning

Calling the C API on this handle is not recommended and there is no official support for it, but for cases where the C++ API does not provide the underlying functionality this C handle can be used to interact directly with the core librdkafka API.

Remarks

The lifetime of the returned pointer is the same as the Message object this method is called on.

Include <rdkafka/rdkafka.h> prior to including <rdkafka/rdkafkacpp.h>

Returns

rd_kafka_message_t*

headers() [1/2]

virtual RdKafka::Headers* RdKafka::Message::headers ( )

pure virtual

Returns

the Headers instance for this Message, or NULL if there are no headers.

Remarks

The lifetime of the Headers are the same as the Message.

headers() [2/2]

virtual RdKafka::Headers* RdKafka::Message::headers ( RdKafka::ErrorCode *  err )

pure virtual

Returns

the Headers instance for this Message (if applicable). If NULL is returned the reason is given in err, which is either ERR__NOENT if there were no headers, or another error code if header parsing failed.

Remarks

The lifetime of the Headers are the same as the Message.

broker_id()

virtual int32_t RdKafka::Message::broker_id ( ) const

pure virtual

Returns

the broker id of the broker the message was produced to or fetched from, or -1 if not known/applicable.

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

• src-cpp/rdkafkacpp.h