Skip to content
Permalink
master
Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
Go to file
 
 
Cannot retrieve contributors at this time
require "statsd"
STATSD = Statsd.new("localhost", 9125)
# Abstract class meant to be subclassed by concrete Kafka consumer
# implementations. It provides every consumer integration with statsd and
# can also provide many other integrations in the future (Sentry, honeycomb etc.)
#
# @abstract
#
# @see {SampleConsumer}
class KafkaConsumer
attr_reader :group, :id, :client
@topic = nil
class << self
attr :topic
# @raise [RuntimeError] if topic is blank
def set_topic(t)
raise "Topic #{t.inspect} is invalid" if t.blank?
@topic = t
end
end
# @param group [String] kafka consumer group
# @param id [String] consumer id
# @param rafka_opts [Hash]
#
# @raise [RuntimeError] if {.set_topic} has not been called
def initialize(group, id, rafka_opts)
if self.class.topic.blank?
raise "Topic for #{self.class} should be set using `set_topic`"
end
@group = group
@id = id
rafka_opts = rafka_opts.merge(topic: self.class.topic, group: @group, id: @id)
@client = Rafka::Consumer.new(rafka_opts)
end
# @abstract
#
# @param msg [Rafka::Message]
def process(msg)
raise "Implement me!"
end
# @return [String]
def topic
self.class.topic
end
def to_s
"#{group}:#{id}"
end
# Consumes a message and processes it.
#
# @param timeout [Fixnum] number of seconds to wait for a message before
# retrying
#
# @return [Rafka::Message, nil]
def process_next(timeout)
client.consume(timeout) do |msg|
begin
# record timing statistics to some backend (eg. statsd)
STATSD.time("kafka.consumer.process.#{self.class}") do
process(msg)
end
rescue => e
# ...report the exception to a backend (eg. Sentry)
raise e
end
end
end
# Terminates the consumer and the connection to Rafka.
def shutdown
client.close
end
end