Class: Deimos::Utils::DbPoller::StateBased

Inherits:
Base
  • Object
show all
Defined in:
lib/deimos/utils/db_poller/state_based.rb

Overview

Poller that uses state columns to determine the records to publish.

Constant Summary

Constants inherited from Base

Base::BATCH_SIZE

Instance Attribute Summary

Attributes inherited from Base

#config, #id

Instance Method Summary collapse

Methods inherited from Base

#create_poll_info, #handle_message_too_large, #initialize, #log_identifier, #process_batch, #process_batch_with_span, #producer_classes, producers, #retrieve_poll_info, #should_run?, #start, #stop, #validate_producer_class

Constructor Details

This class inherits a constructor from Deimos::Utils::DbPoller::Base

Instance Method Details

#fetch_results ⇒ ActiveRecord::Relation

Returns:

  • (ActiveRecord::Relation) 


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# File 'lib/deimos/utils/db_poller/state_based.rb', line 36

def fetch_results
  @resource_class.poll_query.limit(BATCH_SIZE).order(@config.timestamp_column)
end

#finalize_batch(batch, success) ⇒ void

This method returns an undefined value.

Parameters:

  • batch (Array<ActiveRecord::Base>)
  • success (Boolean) 


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# File 'lib/deimos/utils/db_poller/state_based.rb', line 43

def finalize_batch(batch, success)
  @info.touch(:last_sent)

  state = success ? @config.published_state : @config.failed_state
  klass = batch.first.class
  id_col = klass.primary_key.to_sym
  timestamp_col = @config.timestamp_column

  attrs = { timestamp_col => Time.zone.now }
  attrs[@config.state_column] = state if state
  if @config.publish_timestamp_column
    attrs[@config.publish_timestamp_column] = Time.zone.now
  end

  klass.where(id_col => batch.map(&id_col)).update_all(attrs)
end

#process_updates ⇒ void

This method returns an undefined value.

Send messages for updated data.



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# File 'lib/deimos/utils/db_poller/state_based.rb', line 12

def process_updates
  Deimos.config.logger.info("Polling #{log_identifier}")
  status = PollStatus.new(0, 0, 0)
  first_batch = true

  # poll_query gets all the relevant data from the database, as defined
  # by the producer itself.
  loop do
    Deimos.config.logger.debug("Polling #{log_identifier}, batch #{status.current_batch}")
    batch = fetch_results.to_a
    break if batch.empty?

    first_batch = false
    success = process_batch_with_span(batch, status)
    finalize_batch(batch, success)
  end

  # If there were no results at all, we update last_sent so that we still get a wait
  # before the next poll.
  @info.touch(:last_sent) if first_batch
  Deimos.config.logger.info("Poll #{log_identifier} complete (#{status.report}")
end