Permalink
Cannot retrieve contributors at this time
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?
rails-kafka-consumers/rails/lib/kafka_consumer.rb
Go to fileThis commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
85 lines (71 sloc)
1.87 KB
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
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 |