[Issue 53][PulsarSpout] Adds DLQ support in PulsarSpout of the Storm adapter #60
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AnuragReddy2000
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| public void negativeAck(Object msgId) { |
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I was just following the same approach used in the ack and fail methods in the same class, where the method argument is called msgId and has the type Object. But inside the method, there is a check on whether msgId is an instance of the Message class and then is type cast into the Message type and assigned to a variable called msg.
Do you still want me to rename the argument to some other name?
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yes, let's rename it to msg as it's not msgId
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| values = pulsarSpoutConf.getMessageToValuesMapper().toValues(msg); | ||
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this change doesn't seem related to this PR? did we see any issue with the mapper failure? can we create a separate PR with the details if you have come across with such issue?
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Yes, this change is not related to this PR. Let me remove it here and create a separate one for it.
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This change is removed.
rdhabalia
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rdhabalia
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LGTM. let's fix the minor comment.
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| public void negativeAck(Object msgId) { |
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yes, let's rename it to msg as it's not msgId
Addressed review comments
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Fixes #53
Motivation
The current implementation of the Storm adapter does not utilise the dead letter queue functionality of Pulsar. Often it may be desired that when there is some error while processing a message in the Storm topology, the message be moved into the dead letter queue so that it can be handled separately. But the PulsarSpout currently keeps retrying for a while & finally just drops the message by acking it, which leads to data loss. This PR seeks to allow users of PulsarSpout to opt in to using DLQ queues for message processing failures.
Modifications
negativeAcknowledgeto thePulsarSpoutConsumerinterface & added the implementation for the same in theSpoutConsumerclass.negativeAckFailedMessagesin thePulsarSpoutConfigurationclass along with getter & setters for the same.negativeAckin thePulsarSpoutclass to negatively ack messages and send them to the DLQ.failmethod in thePulsarSpoutclass to negatively acknowledge messages whennegativeAckFailedMessagesis set totruemapToValueAndEmitmethod to throw an exception when mapping to the value fails.4.0.2. This is required for this fix as mentioned in the following PR [fix][client] Make DeadLetterPolicy & KeySharedPolicy serializable pulsar#23718Verifying this change
This change added tests and can be verified as follows:
Tested the cases where
negativeAckFailedMessagesis set totrueandfalsein thePulsarSpoutTesttest class.Does this pull request potentially affect one of the following parts:
If
yeswas chosen, please highlight the changesDocumentation
The corresponding PR in my fork: AnuragReddy2000#2