Module: Karafka::Processing::Strategies::DlqMom

Includes:
Dlq
Included in:
AjDlqMom
Defined in:
lib/karafka/processing/strategies/dlq_mom.rb

Overview

Same as pure dead letter queue but we do not marked failed message as consumed

Constant Summary collapse

FEATURES =

Apply strategy when dlq is on with manual offset management

%i[
  dead_letter_queue
  manual_offset_management
].freeze

Instance Method Summary collapse

Methods included from Dlq

#dispatch_to_dlq, #find_skippable_message, #mark_as_consumed, #mark_as_consumed!, #mark_dispatched_to_dlq

Methods included from Default

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

Methods included from 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/processing/strategies/dlq_mom.rb', line 18

def handle_after_consume
  return if revoked?

  if coordinator.success?
    coordinator.pause_tracker.reset
  elsif coordinator.pause_tracker.attempt <= topic.dead_letter_queue.max_retries
    retry_after_pause
  # If we've reached number of retries that we could, we need to skip the first message
  # that was not marked as consumed, pause and continue, while also moving this message
  # to the dead topic
  else
    # We reset the pause to indicate we will now consider it as "ok".
    coordinator.pause_tracker.reset

    skippable_message, = find_skippable_message

    dispatch_to_dlq(skippable_message)

    # We mark the broken message as consumed and move on
    if mark_after_dispatch?
      mark_dispatched_to_dlq(skippable_message)

      return if revoked?
    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

    pause(coordinator.seek_offset, nil, false)
  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/processing/strategies/dlq_mom.rb', line 60

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

  topic.dead_letter_queue.mark_after_dispatch
end