pulsar::ConsumerInterceptor Class Reference

#include <ConsumerInterceptor.h>

Public Member Functions
virtual void	close ()
virtual Message	beforeConsume (const Consumer &consumer, const Message &message)=0
virtual void	onAcknowledge (const Consumer &consumer, Result result, const MessageId &messageID)=0
virtual void	onAcknowledgeCumulative (const Consumer &consumer, Result result, const MessageId &messageID)=0
virtual void	onNegativeAcksSend (const Consumer &consumer, const std::set< MessageId > &messageIds)=0

Detailed Description

A plugin interface that allows you to intercept (and possibly mutate) messages received by the consumer.

A primary use case is to hook into consumer applications for custom monitoring, logging, etc.

Exceptions thrown by interceptor methods will be caught, logged, but not propagated further.

Member Function Documentation

beforeConsume()

virtual Message pulsar::ConsumerInterceptor::beforeConsume ( const Consumer &  consumer, const Message &  message  )

pure virtual

This is called just before the message is consumed.

This method is allowed to modify message, in which case the new message will be returned.

Any exception thrown by this method will be caught by the caller, logged, but not propagated to client.

Since the consumer may run multiple interceptors, a particular interceptor's beforeConsume callback will be called in the order. The first interceptor in the list gets the consumed message, the following interceptor will be passed the message returned by the previous interceptor, and so on. Since interceptors are allowed to modify message, interceptors may potentially get the messages already modified by other interceptors. However building a pipeline of mutable interceptors that depend on the output of the previous interceptor is discouraged, because of potential side-effects caused by interceptors potentially failing to modify the message and throwing an exception. if one of interceptors in the list throws an exception from beforeConsume, the exception is caught, logged, and the next interceptor is called with the message returned by the last successful interceptor in the list, or otherwise the original consumed message.

Parameters

consumer	the consumer which contains the interceptor
message	the message to be consumed by the client

Returns

message that is either modified by the interceptor or same message passed into the method.

close()

virtual void pulsar::ConsumerInterceptor::close ( )

inlinevirtual

Close the interceptor

onAcknowledge()

virtual void pulsar::ConsumerInterceptor::onAcknowledge ( const Consumer &  consumer, Result  result, const MessageId &  messageID  )

pure virtual

This is called before consumer sends the acknowledgment to the broker.

Any exception thrown by this method will be ignored by the caller.

Parameters

consumer	the consumer which contains the interceptor
result	the result of the acknowledgement
messageID	the message id to be acknowledged

onAcknowledgeCumulative()

virtual void pulsar::ConsumerInterceptor::onAcknowledgeCumulative ( const Consumer &  consumer, Result  result, const MessageId &  messageID  )

pure virtual

This is called before consumer sends the cumulative acknowledgment to the broker.

Any exception thrown by this method will be ignored by the caller.

Parameters

consumer	the consumer which contains the interceptor
result	the result of the cumulative acknowledgement
messageID	the message id to be acknowledged cumulatively

onNegativeAcksSend()

virtual void pulsar::ConsumerInterceptor::onNegativeAcksSend ( const Consumer &  consumer, const std::set< MessageId > &  messageIds  )

pure virtual

This method will be called when a redelivery from a negative acknowledge occurs.

Any exception thrown by this method will be ignored by the caller.

Parameters

consumer	the consumer which contains the interceptor
messageIds	the set of message ids to negative ack

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

• include/pulsar/ConsumerInterceptor.h