Class: Franz::Output::Kafka

Inherits:
Object
  • Object
show all
Defined in:
lib/franz/output/kafka.rb

Overview

Kafka output for Franz.

Constant Summary collapse

@@host =

We’ll apply the hostname to all events

Socket.gethostname

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ Kafka

Start a new output in the background. We’ll consume from the input queue and ship events to STDOUT.

Parameters:

  • opts (Hash) (defaults to: {}) —

    options for the output

Options Hash (opts):

  • :input (Queue) — default: [] —

    “input” queue

  • :output (Queue) — default: [] —

    “output” configuration



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# File 'lib/franz/output/kafka.rb', line 22

def initialize opts={}
  opts = {
    logger: Logger.new(STDOUT),
    tags: [],
    input: [],
    output: {
      topic: 'franz',
      flush_interval: 10,
      flush_size: 500,
      client_id: @@host,
      type: 'sync',
      compression_codec: 'snappy',
      metadata_refresh_interval_ms: 600000,
      max_send_retries: 3,
      retry_backoff_ms: 100,
      required_acks: 0,
      ack_timeout_ms: 1500,
      socket_timeout_ms: 10000
    }
  }.deep_merge!(opts)

  @statz = opts[:statz] || Franz::Stats.new
  @statz.create :num_output, 0

  @logger = opts[:logger]

  @stop = false
  @foreground = opts[:foreground]

  @flush_size = opts[:output].delete :flush_size
  @flush_interval = opts[:output].delete :flush_interval
  @topic = opts[:output].delete :topic

  kafka_brokers = opts[:output].delete(:brokers) || %w[ localhost:9092 ]
  kafka_client_id = opts[:output].delete :client_id
  kafka_config = opts[:output].map { |k,v|
    [ k, v.is_a?(String) ? v.to_sym : v ]
  }

  @kafka = Poseidon::Producer.new \
    kafka_brokers,
    kafka_client_id,
    Hash[kafka_config]

  @lock = Mutex.new
  @messages = []


  @thread = Thread.new do
    loop do
      @lock.synchronize do
        ready_messages = @messages
        @messages = []
        @kafka.send_messages ready_messages unless ready_messages.empty?
        log.debug \
          event: 'periodic flush',
          num_messages: ready_messages.size
      end

      sleep @flush_interval
    end
  end


  @thread = Thread.new do
    until @stop
      event = opts[:input].shift

      log.trace \
        event: 'publish',
        raw: event

      payload = JSON::generate(event)

      @lock.synchronize do
        @messages << Poseidon::MessageToSend.new(@topic, payload)

        @statz.inc :num_output

        if @messages.size >= @flush_size
          @kafka.send_messages @messages
          log.debug \
            event: 'flush',
            num_messages: @messages.size
          @messages = []
        end
      end

    end
  end

  log.info event: 'output started'

  @thread.join if @foreground
end

Instance Method Details

#join ⇒ Object

Join the Output thread. Effectively only once.



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# File 'lib/franz/output/kafka.rb', line 120

def join
  return if @foreground
  @foreground = true
  @thread.join
end

#stop ⇒ Object

Stop the Output thread. Effectively only once.



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# File 'lib/franz/output/kafka.rb', line 128

def stop
  return if @foreground
  @foreground = true
  @thread.kill
  log.info event: 'output stopped'
end