RdKafka::Queue Class Reference

Queue interface. More...

#include <rdkafkacpp.h>

Public Member Functions
virtual ErrorCode	forward (Queue *dst)=0
	Forward/re-route queue to dst. If dst is NULL, the forwarding is removed. More...
virtual Message *	consume (int timeout_ms)=0
	Consume message or get error event from the queue. More...
virtual int	poll (int timeout_ms)=0
	Poll queue, serving any enqueued callbacks. More...
virtual void	io_event_enable (int fd, const void *payload, size_t size)=0
	Enable IO event triggering for queue. More...

Static Public Member Functions
static Queue *	create (Handle *handle)
	Create Queue object.

Detailed Description

Queue interface.

Create a new message queue. Message queues allows the application to re-route consumed messages from multiple topic+partitions into one single queue point. This queue point, containing messages from a number of topic+partitions, may then be served by a single consume() method, rather than one per topic+partition combination.

See the RdKafka::Consumer::start(), RdKafka::Consumer::consume(), and RdKafka::Consumer::consume_callback() methods that take a queue as the first parameter for more information.

Member Function Documentation

forward()

virtual ErrorCode RdKafka::Queue::forward ( Queue *  dst )

pure virtual

Forward/re-route queue to dst. If dst is NULL, the forwarding is removed.

The internal refcounts for both queues are increased.

Remarks

Regardless of whether dst is NULL or not, after calling this function, src will not forward it's fetch queue to the consumer queue.

consume()

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

pure virtual

Consume message or get error event from the queue.

Remarks

Use delete to free the message.

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)

poll()

virtual int RdKafka::Queue::poll ( int  timeout_ms )

pure virtual

Poll queue, serving any enqueued callbacks.

Remarks

Must NOT be used for queues containing messages.

Returns

the number of events served or 0 on timeout.

io_event_enable()

virtual void RdKafka::Queue::io_event_enable ( int  fd, const void *  payload, size_t  size  )

pure virtual

Enable IO event triggering for queue.

To ease integration with IO based polling loops this API allows an application to create a separate file-descriptor that librdkafka will write payload (of size size) to whenever a new element is enqueued on a previously empty queue.

To remove event triggering call with fd = -1.

librdkafka will maintain a copy of the payload.

Remarks

When using forwarded queues the IO event must only be enabled on the final forwarded-to (destination) queue.

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

• src-cpp/rdkafkacpp.h