Class: Deimos::Utils::DbPoller::Base

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

Overview

Base poller class for retrieving and publishing messages.

Direct Known Subclasses

StateBased, TimeBased

Constant Summary collapse

BATCH_SIZE =

Returns:

  • (Integer) 
1000

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(config) ⇒ Base

Returns a new instance of Base.

Parameters:



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# File 'lib/deimos/utils/db_poller/base.rb', line 32

def initialize(config)
  @config = config
  @id = SecureRandom.hex
  begin
    if @config.poller_class.nil? && @config.producer_class.nil?
      raise 'No producers have been set for this DB poller!'
    end

    @resource_class = self.class.producers.any? ? self.class : @config.producer_class.constantize

    producer_classes.each do |producer_class|
      validate_producer_class(producer_class)
    end
  rescue NameError
    raise "Class #{@config.producer_class} not found!"
  end
end

Instance Attribute Details

#config ⇒ Hash (readonly)

Returns:

  • (Hash) 


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# File 'lib/deimos/utils/db_poller/base.rb', line 22

def config
  @config
end

#id ⇒ Integer (readonly)

Needed for Executor so it can identify the worker

Returns:

  • (Integer) 


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# File 'lib/deimos/utils/db_poller/base.rb', line 19

def id
  @id
end

Class Method Details

.producers ⇒ Array<Producer>

Method to define producers if a single poller needs to publish to multiple topics. Producer classes should be constantized

Returns:



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# File 'lib/deimos/utils/db_poller/base.rb', line 27

def self.producers
  []
end

Instance Method Details

#create_poll_info ⇒ Deimos::PollInfo

Returns:



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# File 'lib/deimos/utils/db_poller/base.rb', line 84

def create_poll_info
  Deimos::PollInfo.create!(producer: @resource_class.to_s, last_sent: Time.new(0))
end

#handle_message_too_large(exception, batch, status, span) ⇒ Boolean

Parameters:

  • exception (Exception)
  • batch (Array<ActiveRecord::Base>)
  • status (PollStatus)
  • span (Object)

Returns:

  • (Boolean) 


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# File 'lib/deimos/utils/db_poller/base.rb', line 113

def handle_message_too_large(exception, batch, status, span)
  Deimos.config.logger.error("Error publishing through DB Poller: #{exception.message}")
  if @config.skip_too_large_messages
    Deimos.config.logger.error("Skipping messages #{batch.map(&:id).join(', ')} since they are too large")
    Deimos.config.tracer&.set_error(span, exception)
    status.batches_errored += 1
    true
  else # do the same thing as regular Kafka::Error
    sleep(0.5)
    false
  end
end

#log_identifier ⇒ String

Configure log identifier and messages to be used in subclasses

Returns:

  • (String) 


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# File 'lib/deimos/utils/db_poller/base.rb', line 177

def log_identifier
  "#{@resource_class.name}: #{producer_classes.map(&:topic)}"
end

#process_batch(batch) ⇒ void

This method returns an undefined value.

Publish batch using the configured producers

Parameters:

  • batch (Array<ActiveRecord::Base>) 


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# File 'lib/deimos/utils/db_poller/base.rb', line 169

def process_batch(batch)
  producer_classes.each do |producer|
    producer.send_events(batch)
  end
end

#process_batch_with_span(batch, status) ⇒ Boolean

rubocop:disable Metrics/AbcSize

Parameters:

  • batch (Array<ActiveRecord::Base>)
  • status (PollStatus)

Returns:

  • (Boolean) 


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# File 'lib/deimos/utils/db_poller/base.rb', line 130

def process_batch_with_span(batch, status)
  retries = 0
  begin
    span = Deimos.config.tracer&.start(
      'deimos-db-poller',
      resource: @resource_class.name.gsub('::', '-')
    )
    process_batch(batch)
    Deimos.config.tracer&.finish(span)
    status.batches_processed += 1
  rescue Kafka::BufferOverflow, Kafka::MessageSizeTooLarge,
         Kafka::RecordListTooLarge => e
    retry unless handle_message_too_large(e, batch, status, span)
  rescue Kafka::Error => e # keep trying till it fixes itself
    Deimos.config.logger.error("Error publishing through DB Poller: #{e.message}")
    sleep(0.5)
    retry
  rescue StandardError => e
    Deimos.config.logger.error("Error publishing through DB poller: #{e.message}}")
    if @config.retries.nil? || retries < @config.retries
      retries += 1
      sleep(0.5)
      retry
    else
      Deimos.config.logger.error('Retries exceeded, moving on to next batch')
      Deimos.config.tracer&.set_error(span, e)
      status.batches_errored += 1
      return false
    end
  ensure
    status.messages_processed += batch.size
  end
  true
end

#process_updates ⇒ void

This method returns an undefined value.

Send messages for updated data.

Raises:



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# File 'lib/deimos/utils/db_poller/base.rb', line 104

def process_updates
  raise Deimos::MissingImplementationError
end

#producer_classes ⇒ Array<ActiveRecordProducer>

Return array of configured producers depending on poller class

Returns:



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# File 'lib/deimos/utils/db_poller/base.rb', line 183

def producer_classes
  return self.class.producers if self.class.producers.any?

  [@config.producer_class.constantize]
end

#retrieve_poll_info ⇒ void

Grab the PollInfo or create if it doesn’t exist.

Returns:

  • (void)
  • (void) 


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# File 'lib/deimos/utils/db_poller/base.rb', line 79

def retrieve_poll_info
  @info = Deimos::PollInfo.find_by_producer(@resource_class.to_s) || create_poll_info
end

#should_run? ⇒ Boolean

Indicate whether this current loop should process updates. Most loops will busy-wait (sleeping 0.1 seconds) until it’s ready.

Returns:

  • (Boolean) 


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# File 'lib/deimos/utils/db_poller/base.rb', line 91

def should_run?
  Time.zone.now - @info.last_sent - @config.delay_time >= @config.run_every
end

#start ⇒ void

This method returns an undefined value.

Start the poll: 1) Grab the current PollInfo from the database indicating the last time we ran 2) On a loop, process all the recent updates between the last time we ran and now.



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# File 'lib/deimos/utils/db_poller/base.rb', line 56

def start
  # Don't send asynchronously
  if Deimos.config.producers.backend == :kafka_async
    Deimos.config.producers.backend = :kafka
  end
  Deimos.config.logger.info('Starting...')
  @signal_to_stop = false
  ActiveRecord::Base.connection.reconnect! unless ActiveRecord::Base.connection.open_transactions.positive?

  retrieve_poll_info
  loop do
    if @signal_to_stop
      Deimos.config.logger.info('Shutting down')
      break
    end
    process_updates if should_run?
    sleep(0.1)
  end
end

#stop ⇒ void

This method returns an undefined value.

Stop the poll.



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# File 'lib/deimos/utils/db_poller/base.rb', line 97

def stop
  Deimos.config.logger.info('Received signal to stop')
  @signal_to_stop = true
end

#validate_producer_class(producer_class) ⇒ void

This method returns an undefined value.

Validate if a producer class is an ActiveRecordProducer or not



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# File 'lib/deimos/utils/db_poller/base.rb', line 191

def validate_producer_class(producer_class)
  unless producer_class < Deimos::ActiveRecordProducer
    raise "Class #{producer_class.class.name} is not an ActiveRecordProducer!"
  end
end