Class: Hutch::Broker

Inherits:
Object
  • Object
show all
Includes:
Logging
Defined in:
lib/hutch/broker.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Logging

#logger, logger, logger=, setup_logger

Constructor Details

#initialize(config = nil) ⇒ Broker

Returns a new instance of Broker.



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# File 'lib/hutch/broker.rb', line 13

def initialize(config = nil)
  @config = config || Hutch::Config
end

Instance Attribute Details

#api_client ⇒ Object

Returns the value of attribute api_client.



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# File 'lib/hutch/broker.rb', line 11

def api_client
  @api_client
end

#channel ⇒ Object

Returns the value of attribute channel.



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# File 'lib/hutch/broker.rb', line 11

def channel
  @channel
end

#connection ⇒ Object

Returns the value of attribute connection.



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# File 'lib/hutch/broker.rb', line 11

def connection
  @connection
end

#exchange ⇒ Object

Returns the value of attribute exchange.



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# File 'lib/hutch/broker.rb', line 11

def exchange
  @exchange
end

Instance Method Details

#ack(delivery_tag) ⇒ Object 



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# File 'lib/hutch/broker.rb', line 151

def ack(delivery_tag)
  @channel.ack(delivery_tag, false)
end

#bind_queue(queue, routing_keys) ⇒ Object

Bind a queue to the broker’s exchange on the routing keys provided. Any existing bindings on the queue that aren’t present in the array of routing keys will be unbound.



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# File 'lib/hutch/broker.rb', line 121

def bind_queue(queue, routing_keys)
  # Find the existing bindings, and unbind any redundant bindings
  queue_bindings = bindings.select { |dest, keys| dest == queue.name }
  queue_bindings.each do |dest, keys|
    keys.reject { |key| routing_keys.include?(key) }.each do |key|
      logger.debug "removing redundant binding #{queue.name} <--> #{key}"
      queue.unbind(@exchange, routing_key: key)
    end
  end

  # Ensure all the desired bindings are present
  routing_keys.each do |routing_key|
    logger.debug "creating binding #{queue.name} <--> #{routing_key}"
    queue.bind(@exchange, routing_key: routing_key)
  end
end

#bindings ⇒ Object

Return a mapping of queue names to the routing keys they’re bound to.



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# File 'lib/hutch/broker.rb', line 107

def bindings
  results = Hash.new { |hash, key| hash[key] = [] }
  @api_client.bindings.each do |binding|
    next if binding['destination'] == binding['routing_key']
    next unless binding['source'] == @config[:mq_exchange]
    next unless binding['vhost'] == @config[:mq_vhost]
    results[binding['destination']] << binding['routing_key']
  end
  results
end

#connect(options = {}) ⇒ Object 



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# File 'lib/hutch/broker.rb', line 17

def connect(options = {})
  set_up_amqp_connection
  set_up_api_connection if options.fetch(:enable_http_api_use, true)

  if block_given?
    yield
    disconnect
  end
end

#disconnect ⇒ Object 



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# File 'lib/hutch/broker.rb', line 27

def disconnect
  @channel.close    if @channel
  @connection.close if @connection
  @channel, @connection, @exchange, @api_client = nil, nil, nil, nil
end

#nack(delivery_tag) ⇒ Object 



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# File 'lib/hutch/broker.rb', line 155

def nack(delivery_tag)
  @channel.nack(delivery_tag, false, false)
end

#open_channel! ⇒ Object 



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# File 'lib/hutch/broker.rb', line 74

def open_channel!
  logger.info 'opening rabbitmq channel'
  @channel = connection.create_channel.tap do |ch|
    ch.prefetch(@config[:channel_prefetch]) if @config[:channel_prefetch]
  end
end

#open_connection! ⇒ Object 



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# File 'lib/hutch/broker.rb', line 48

def open_connection!
  host     = @config[:mq_host]
  port     = @config[:mq_port]
  vhost    = @config[:mq_vhost]
  username = @config[:mq_username]
  password = @config[:mq_password]
  tls      = @config[:mq_tls]
  tls_key  = @config[:mq_tls_key]
  tls_cert = @config[:mq_tls_cert]
  protocol = tls ? "amqps://" : "amqp://"
  sanitized_uri = "#{protocol}#{username}@#{host}:#{port}/#{vhost.sub(/^\//, '')}"
  logger.info "connecting to rabbitmq (#{sanitized_uri})"

  @connection = Bunny.new(host: host, port: port, vhost: vhost,
                          tls: tls, tls_key: tls_key, tls_cert: tls_cert,
                          username: username, password: password,
                          heartbeat: 30, automatically_recover: true,
                          network_recovery_interval: 1)

  with_bunny_connection_handler(sanitized_uri) do
    @connection.start
  end

  @connection
end

#publish(routing_key, message, properties = {}) ⇒ Object 



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# File 'lib/hutch/broker.rb', line 159

def publish(routing_key, message, properties = {})
  ensure_connection!(routing_key, message)

  non_overridable_properties = {
    routing_key: routing_key,
    timestamp: Time.now.to_i,
    content_type: 'application/json'
  }
  properties[:message_id] ||= generate_id

  logger.info("publishing message '#{message.inspect}' to #{routing_key}")
  @exchange.publish(JSON.dump(message), {persistent: true}.
    merge(properties).
    merge(global_properties).
    merge(non_overridable_properties))
end

#queue(name) ⇒ Object

Create / get a durable queue and apply namespace if it exists.



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# File 'lib/hutch/broker.rb', line 98

def queue(name)
  with_bunny_precondition_handler('queue') do
    namespace = @config[:namespace].to_s.downcase.gsub(/[^-_:\.\w]/, "")
    name = name.prepend(namespace + ":") unless namespace.empty?
    channel.queue(name, durable: true)
  end
end

#set_up_amqp_connection ⇒ Object

Connect to RabbitMQ via AMQP. This sets up the main connection and channel we use for talking to RabbitMQ. It also ensures the existance of the exchange we’ll be using.



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# File 'lib/hutch/broker.rb', line 36

def set_up_amqp_connection
  open_connection!
  open_channel!

  exchange_name = @config[:mq_exchange]
  logger.info "using topic exchange '#{exchange_name}'"

  with_bunny_precondition_handler('exchange') do
    @exchange = @channel.topic(exchange_name, durable: true)
  end
end

#set_up_api_connection ⇒ Object

Set up the connection to the RabbitMQ management API. Unfortunately, this is necessary to do a few things that are impossible over AMQP. E.g. listing queues and bindings.



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# File 'lib/hutch/broker.rb', line 84

def set_up_api_connection
  logger.info "connecting to rabbitmq HTTP API (#{api_config.sanitized_uri})"

  with_authentication_error_handler do
    with_connection_error_handler do
      @api_client = CarrotTop.new(host: api_config.host, port: api_config.port,
                                  user: api_config.username, password: api_config.password,
                                  ssl: api_config.ssl)
      @api_client.exchanges
    end
  end
end

#stop ⇒ Object 



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# File 'lib/hutch/broker.rb', line 147

def stop
  @channel.work_pool.kill
end

#wait_on_threads(timeout) ⇒ Object

Each subscriber is run in a thread. This calls Thread#join on each of the subscriber threads.



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# File 'lib/hutch/broker.rb', line 140

def wait_on_threads(timeout)
  # Thread#join returns nil when the timeout is hit. If any return nil,
  # the threads didn't all join so we return false.
  per_thread_timeout = timeout.to_f / work_pool_threads.length
  work_pool_threads.none? { |thread| thread.join(per_thread_timeout).nil? }
end