Module: Karafka::Pro::Processing::Strategies::Dlq::Mom

Includes:
Default
Included in:
Aj::DlqMom, MomVp
Defined in:
lib/karafka/pro/processing/strategies/dlq/mom.rb

Overview

Strategy for supporting DLQ with Mom enabled

Constant Summary collapse

FEATURES =

Features for this strategy

%i[
  dead_letter_queue
  manual_offset_management
].freeze

Instance Method Summary collapse

Methods included from Default

#apply_dlq_flow, #build_dlq_message, #dispatch_if_needed_and_mark_as_consumed, #dispatch_in_a_transaction?, #dispatch_to_dlq, #dispatch_to_dlq?, #find_skippable_message, #mark_as_consumed, #mark_as_consumed!, #mark_dispatched_to_dlq

Methods included from Karafka::Pro::Processing::Strategies::Default

#handle_before_consume, #handle_before_schedule_consume, #handle_before_schedule_tick, #handle_consume, #handle_revoked, #handle_tick, #mark_as_consumed, #mark_as_consumed!, #mark_in_transaction, #store_offset_metadata, #transaction

Methods included from Karafka::Processing::Strategies::Default

#commit_offsets, #commit_offsets!, #handle_before_consume, #handle_consume, #handle_eofed, #handle_idle, #handle_revoked, #handle_shutdown, #mark_as_consumed, #mark_as_consumed!

Methods included from Karafka::Processing::Strategies::Base

#handle_before_consume, #handle_consume, #handle_idle, #handle_revoked, #handle_shutdown

Instance Method Details

#handle_after_consume ⇒ Object

When manual offset management is on, we do not mark anything as consumed automatically and we rely on the user to figure things out



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# File 'lib/karafka/pro/processing/strategies/dlq/mom.rb', line 32

def handle_after_consume
  coordinator.on_finished do
    return if revoked?

    if coordinator.success?
      coordinator.pause_tracker.reset
    else
      apply_dlq_flow do
        skippable_message, = find_skippable_message
        dispatch_to_dlq(skippable_message) if dispatch_to_dlq?

        if mark_after_dispatch?
          mark_dispatched_to_dlq(skippable_message)
        else
          # Save the next offset we want to go with after moving given message to DLQ
          # Without this, we would not be able to move forward and we would end up
          # in an infinite loop trying to un-pause from the message we've already
          # processed. Of course, since it's a MoM a rebalance or kill, will move it
          # back as no offsets are being committed
          coordinator.seek_offset = skippable_message.offset + 1
        end
      end
    end
  end
end

#mark_after_dispatch? ⇒ Boolean

Note:

Please note, this is the opposite behavior than in case of AOM strategies.

Returns should we mark given message as consumed after dispatch. For MOM strategies if user did not explicitly tell us to mark, we do not mark. Default is nil, which means false in this case. If user provided alternative value, we go with it.

Returns:

  • (Boolean) —

    should we mark given message as consumed after dispatch. For MOM strategies if user did not explicitly tell us to mark, we do not mark. Default is nil, which means false in this case. If user provided alternative value, we go with it.



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# File 'lib/karafka/pro/processing/strategies/dlq/mom.rb', line 64

def mark_after_dispatch?
  return false if topic.dead_letter_queue.mark_after_dispatch.nil?

  topic.dead_letter_queue.mark_after_dispatch
end