Class: Kafka::Cluster

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

Overview

A cluster represents the state of a Kafka cluster. It needs to be initialized with a non-empty list of seed brokers. The first seed broker that the cluster can connect to will be asked for the cluster metadata, which allows the cluster to map topic partitions to the current leader for those partitions.

Instance Method Summary collapse

Constructor Details

#initialize(seed_brokers:, broker_pool:, logger:) ⇒ Cluster

Initializes a Cluster with a set of seed brokers.

The cluster will try to fetch cluster metadata from one of the brokers.

Parameters:



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# File 'lib/kafka/cluster.rb', line 21

def initialize(seed_brokers:, broker_pool:, logger:)
  if seed_brokers.empty?
    raise ArgumentError, "At least one seed broker must be configured"
  end

  @logger = logger
  @seed_brokers = seed_brokers
  @broker_pool = broker_pool
  @cluster_info = nil
  @stale = true

  # This is the set of topics we need metadata for. If empty, metadata for
  # all topics will be fetched.
  @target_topics = Set.new
end

Instance Method Details

#add_target_topics(topics) ⇒ nil

Adds a list of topics to the target list. Only the topics on this list will be queried for metadata.

Parameters:

  • topics (Array<String>)

Returns:

  • (nil) 


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# File 'lib/kafka/cluster.rb', line 42

def add_target_topics(topics)
  topics = Set.new(topics)
  unless topics.subset?(@target_topics)
    new_topics = topics - @target_topics

    unless new_topics.empty?
      @logger.info "New topics added to target list: #{new_topics.to_a.join(', ')}"

      @target_topics.merge(new_topics)

      refresh_metadata!
    end
  end
end

#alter_topic(name, configs = {}) ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 230

def alter_topic(name, configs = {})
  options = {
    resources: [[Kafka::Protocol::RESOURCE_TYPE_TOPIC, name, configs]]
  }

  broker = controller_broker

  @logger.info "Altering the config for topic `#{name}` using controller broker #{broker}"

  response = broker.alter_configs(**options)

  response.resources.each do |resource|
    Protocol.handle_error(resource.error_code, resource.error_message)
  end

  nil
end

#api_info(api_key) ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 57

def api_info(api_key)
  apis.find {|api| api.api_key == api_key }
end

#apis ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 72

def apis
  @apis ||=
    begin
      response = random_broker.api_versions

      Protocol.handle_error(response.error_code)

      response.apis
    end
end

#clear_target_topics ⇒ nil

Clears the list of target topics.

Returns:

  • (nil)

See Also:



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# File 'lib/kafka/cluster.rb', line 87

def clear_target_topics
  @target_topics.clear
  refresh_metadata!
end

#cluster_info ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 349

def cluster_info
  @cluster_info ||= fetch_cluster_info
end

#create_partitions_for(name, num_partitions:, timeout:) ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 255

def create_partitions_for(name, num_partitions:, timeout:)
  options = {
    topics: [[name, num_partitions, nil]],
    timeout: timeout
  }

  broker = controller_broker

  @logger.info "Creating #{num_partitions} partition(s) for topic `#{name}` using controller broker #{broker}"

  response = broker.create_partitions(**options)

  response.errors.each do |topic, error_code, error_message|
    Protocol.handle_error(error_code, error_message)
  end
  mark_as_stale!

  @logger.info "Topic `#{name}` was updated"
end

#create_topic(name, num_partitions:, replication_factor:, timeout:, config:) ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 151

def create_topic(name, num_partitions:, replication_factor:, timeout:, config:)
  options = {
    topics: {
      name => {
        num_partitions: num_partitions,
        replication_factor: replication_factor,
        config: config,
      }
    },
    timeout: timeout,
  }

  broker = controller_broker

  @logger.info "Creating topic `#{name}` using controller broker #{broker}"

  response = broker.create_topics(**options)

  response.errors.each do |topic, error_code|
    Protocol.handle_error(error_code)
  end

  begin
    partitions_for(name).each do |info|
      Protocol.handle_error(info.partition_error_code)
    end
  rescue Kafka::LeaderNotAvailable
    @logger.warn "Leader not yet available for `#{name}`, waiting 1s..."
    sleep 1

    retry
  rescue Kafka::UnknownTopicOrPartition
    @logger.warn "Topic `#{name}` not yet created, waiting 1s..."
    sleep 1

    retry
  end

  @logger.info "Topic `#{name}` was created"
end

#delete_topic(name, timeout:) ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 192

def delete_topic(name, timeout:)
  options = {
    topics: [name],
    timeout: timeout,
  }

  broker = controller_broker

  @logger.info "Deleting topic `#{name}` using controller broker #{broker}"

  response = broker.delete_topics(**options)

  response.errors.each do |topic, error_code|
    Protocol.handle_error(error_code)
  end

  @logger.info "Topic `#{name}` was deleted"
end

#describe_group(group_id) ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 248

def describe_group(group_id)
  response = get_group_coordinator(group_id: group_id).describe_groups(group_ids: [group_id])
  group = response.groups.first
  Protocol.handle_error(group.error_code)
  group
end

#describe_topic(name, configs = []) ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 211

def describe_topic(name, configs = [])
  options = {
    resources: [[Kafka::Protocol::RESOURCE_TYPE_TOPIC, name, configs]]
  }
  broker = controller_broker

  @logger.info "Fetching topic `#{name}`'s configs using controller broker #{broker}"

  response = broker.describe_configs(**options)

  response.resources.each do |resource|
    Protocol.handle_error(resource.error_code, resource.error_message)
  end
  topic_description = response.resources.first
  topic_description.configs.each_with_object({}) do |config, hash|
    hash[config.name] = config.value
  end
end

#disconnect ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 345

def disconnect
  @broker_pool.close
end

#get_group_coordinator(group_id:) ⇒ Broker

Finds the broker acting as the coordinator of the given group.

Parameters:

  • group_id: (String)

Returns:

  • (Broker) —

    the broker that's currently coordinator.



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# File 'lib/kafka/cluster.rb', line 118

def get_group_coordinator(group_id:)
  @logger.debug "Getting group coordinator for `#{group_id}`"
  refresh_metadata_if_necessary!
  get_coordinator(Kafka::Protocol::COORDINATOR_TYPE_GROUP, group_id)
end

#get_leader(topic, partition) ⇒ Broker

Finds the broker acting as the leader of the given topic and partition.

Parameters:

  • topic (String)
  • partition (Integer)

Returns:

  • (Broker) —

    the broker that's currently leader.



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# File 'lib/kafka/cluster.rb', line 110

def get_leader(topic, partition)
  connect_to_broker(get_leader_id(topic, partition))
end

#get_transaction_coordinator(transactional_id:) ⇒ Broker

Finds the broker acting as the coordinator of the given transaction.

Parameters:

  • transactional_id: (String)

Returns:

  • (Broker) —

    the broker that's currently coordinator.



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# File 'lib/kafka/cluster.rb', line 128

def get_transaction_coordinator(transactional_id:)
  @logger.debug "Getting transaction coordinator for `#{transactional_id}`"

  refresh_metadata_if_necessary!

  if transactional_id.nil?
    # Get a random_broker
    @logger.debug "Transaction ID is not available. Choose a random broker."
    return random_broker
  else
    get_coordinator(Kafka::Protocol::COORDINATOR_TYPE_TRANSACTION, transactional_id)
  end
end

#list_groups ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 336

def list_groups
  refresh_metadata_if_necessary!
  cluster_info.brokers.map do |broker|
    response = connect_to_broker(broker.node_id).list_groups
    Protocol.handle_error(response.error_code)
    response.groups.map(&:group_id)
  end.flatten.uniq
end

#list_topics ⇒ Object

Lists all topics in the cluster.



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# File 'lib/kafka/cluster.rb', line 329

def list_topics
  response = random_broker.fetch_metadata(topics: nil)
  response.topics.select do |topic|
    topic.topic_error_code == 0
  end.map(&:topic_name)
end

#mark_as_stale! ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 92

def mark_as_stale!
  @stale = true
end

#partitions_for(topic) ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 142

def partitions_for(topic)
  add_target_topics([topic])
  refresh_metadata_if_necessary!
  cluster_info.partitions_for(topic)
rescue Kafka::ProtocolError
  mark_as_stale!
  raise
end

#refresh_metadata! ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 96

def refresh_metadata!
  @cluster_info = nil
  cluster_info
end

#refresh_metadata_if_necessary! ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 101

def refresh_metadata_if_necessary!
  refresh_metadata! if @stale
end

#resolve_offset(topic, partition, offset) ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 317

def resolve_offset(topic, partition, offset)
  resolve_offsets(topic, [partition], offset).fetch(partition)
end

#resolve_offsets(topic, partitions, offset) ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 275

def resolve_offsets(topic, partitions, offset)
  add_target_topics([topic])
  refresh_metadata_if_necessary!

  partitions_by_broker = partitions.each_with_object({}) {|partition, hsh|
    broker = get_leader(topic, partition)

    hsh[broker] ||= []
    hsh[broker] << partition
  }

  if offset == :earliest
    offset = -2
  elsif offset == :latest
    offset = -1
  end

  offsets = {}

  partitions_by_broker.each do |broker, broker_partitions|
    response = broker.list_offsets(
      topics: {
        topic => broker_partitions.map {|partition|
          {
            partition: partition,
            time: offset
          }
        }
      }
    )

    broker_partitions.each do |partition|
      offsets[partition] = response.offset_for(topic, partition)
    end
  end

  offsets
rescue Kafka::ProtocolError
  mark_as_stale!
  raise
end

#supports_api?(api_key, version = nil) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/kafka/cluster.rb', line 61

def supports_api?(api_key, version = nil)
  info = api_info(api_key)
  if info.nil?
    return false
  elsif version.nil?
    return true
  else
    return info.version_supported?(version)
  end
end

#topics ⇒ Object 



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# File 'lib/kafka/cluster.rb', line 321

def topics
  refresh_metadata_if_necessary!
  cluster_info.topics.select do |topic|
    topic.topic_error_code == 0
  end.map(&:topic_name)
end