Class: Protobuf::Nats::Client

Inherits:
Rpc::Connectors::Base
  • Object
show all
Defined in:
lib/protobuf/nats/client.rb

Defined Under Namespace

Classes: SubscriptionInbox

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options) ⇒ Client

Returns a new instance of Client.



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# File 'lib/protobuf/nats/client.rb', line 33

def initialize(options)
  # may need to override to setup connection at this stage ... may also do on load of class
  super

  # This will ensure the client is started.
  ::Protobuf::Nats.start_client_nats_connection
end

Class Method Details

.subscription_key_cache ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 71

def self.subscription_key_cache
  @subscription_key_cache ||= {}
end

.subscription_pool ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 17

def self.subscription_pool
  @subscription_pool ||= ::ConnectionPool.new(:size => subscription_pool_size, :timeout => 0.1) do
    inbox = ::Protobuf::Nats.client_nats_connection.new_inbox

    SubscriptionInbox.new(::Protobuf::Nats.client_nats_connection.subscribe(inbox), inbox)
  end
end

.subscription_pool_size ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 25

def self.subscription_pool_size
  @subscription_pool_size ||= if ::ENV.key?("PB_NATS_CLIENT_SUBSCRIPTION_POOL_SIZE")
    ::ENV["PB_NATS_CLIENT_SUBSCRIPTION_POOL_SIZE"].to_i
  else
    0
  end
end

Instance Method Details

#ack_timeout ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 75

def ack_timeout
  @ack_timeout ||= if ::ENV.key?("PB_NATS_CLIENT_ACK_TIMEOUT")
    ::ENV["PB_NATS_CLIENT_ACK_TIMEOUT"].to_i
  else
    5
  end
end

#cached_subscription_key ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 179

def cached_subscription_key
  klass = @options[:service]
  method_name = @options[:method]

  method_name_cache = self.class.subscription_key_cache[klass] ||= {}
  method_name_cache[method_name] ||= begin
    ::Protobuf::Nats.subscription_key(klass, method_name)
  end
end

#close_connection ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 67

def close_connection
  # no-op (I think for now), the connection to server is persistent
end

#formatted_service_and_method_name ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 189

def formatted_service_and_method_name
  klass = @options[:service]
  method_name = @options[:method]
  "#{klass}##{method_name}"
end

#nack_backoff_intervals ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 83

def nack_backoff_intervals
  @nack_backoff_intervals ||= if ::ENV.key?("PB_NATS_CLIENT_NACK_BACKOFF_INTERVALS")
    ::ENV["PB_NATS_CLIENT_NACK_BACKOFF_INTERVALS"].split(",").map(&:to_i)
  else
    [0, 1, 3, 5, 10]
  end
end

#nack_backoff_splay ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 91

def nack_backoff_splay
  @nack_backoff_splay ||= if nack_backoff_splay_limit > 0
    rand(nack_backoff_splay_limit)
  else
    0
  end
end

#nack_backoff_splay_limit ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 99

def nack_backoff_splay_limit
  @nack_backoff_splay_limit ||= if ::ENV.key?("PB_NATS_CLIENT_NACK_BACKOFF_SPLAY_LIMIT")
    ::ENV["PB_NATS_CLIENT_NACK_BACKOFF_SPLAY_LIMIT"].to_i
  else
    10
  end
end

#nats_request_with_two_responses(subject, data, opts) ⇒ Object

This is a request that expects two responses.

  1. An ACK from the server. We use a shorter timeout.

  2. A PB message from the server. We use a longer timoeut.



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# File 'lib/protobuf/nats/client.rb', line 203

def nats_request_with_two_responses(subject, data, opts)
  # Wait for the ACK from the server
  ack_timeout = opts[:ack_timeout] || 5
  # Wait for the protobuf response
  timeout = opts[:timeout] || 60

  nats = ::Protobuf::Nats.client_nats_connection

  # Publish to server
  with_subscription do |sub_inbox|
    begin
      completed_request = false

      if !sub_inbox.subscription.is_valid # replace the subscription if is has been pooled but is no longer valid (maybe a reconnect)
        nats.unsubscribe(sub_inbox.subscription)
        sub_inbox.swap(new_subscription_inbox) # this line replaces the sub_inbox in the connection pool if necessary
      end

      nats.publish(subject, data, sub_inbox.inbox)

      # Wait for reply
      first_message = nats.next_message(sub_inbox.subscription, ack_timeout)
      return :ack_timeout if first_message.nil?

      first_message_data = first_message.data
      return :nack if first_message_data == ::Protobuf::Nats::Messages::NACK

      second_message = nats.next_message(sub_inbox.subscription, timeout)
      second_message_data = second_message.nil? ? nil : second_message.data

      # Check messages
      response = case ::Protobuf::Nats::Messages::ACK
                 when first_message_data then second_message_data
                 when second_message_data then first_message_data
                 else return :ack_timeout
                 end

      fail(::Protobuf::Nats::Errors::ResponseTimeout, formatted_service_and_method_name) unless response

      completed_request = true
      response
    ensure
      if !completed_request
        nats.unsubscribe(sub_inbox.subscription)
        sub_inbox.swap(new_subscription_inbox) # this line replaces the sub_inbox in the connection pool if necessary
      end
    end
  end
end

#new_subscription_inbox ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 41

def new_subscription_inbox
  nats = ::Protobuf::Nats.client_nats_connection
  inbox = nats.new_inbox
  sub = if use_subscription_pooling?
          nats.subscribe(inbox)
        else
          nats.subscribe(inbox, :max => 2)
        end

  SubscriptionInbox.new(sub, inbox)
end

#reconnect_delay ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 107

def reconnect_delay
  @reconnect_delay ||= if ::ENV.key?("PB_NATS_CLIENT_RECONNECT_DELAY")
    ::ENV["PB_NATS_CLIENT_RECONNECT_DELAY"].to_i
  else
    ack_timeout
  end
end

#response_timeout ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 115

def response_timeout
  @response_timeout ||= if ::ENV.key?("PB_NATS_CLIENT_RESPONSE_TIMEOUT")
    ::ENV["PB_NATS_CLIENT_RESPONSE_TIMEOUT"].to_i
  else
    60
  end
end

#send_request ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 128

def send_request
  # This will ensure the client is started.
  ::Protobuf::Nats.start_client_nats_connection

  if use_subscription_pooling?
    available = self.class.subscription_pool.instance_variable_get("@available")
    ::ActiveSupport::Notifications.instrument "client.subscription_pool_available_size.protobuf-nats", available.length
  end

  ::ActiveSupport::Notifications.instrument "client.request_duration.protobuf-nats" do
    send_request_through_nats
  end
end

#send_request_through_nats ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 142

def send_request_through_nats
  retries ||= 3
  nack_retry ||= 0

  loop do
    setup_connection
    request_options = {:timeout => response_timeout, :ack_timeout => ack_timeout}
    @response_data = nats_request_with_two_responses(cached_subscription_key, @request_data, request_options)
    case @response_data
    when :ack_timeout
      ::ActiveSupport::Notifications.instrument "client.request_timeout.protobuf-nats"
      next if (retries -= 1) > 0
      raise ::Protobuf::Nats::Errors::RequestTimeout, formatted_service_and_method_name
    when :nack
      ::ActiveSupport::Notifications.instrument "client.request_nack.protobuf-nats"
      interval = nack_backoff_intervals[nack_retry]
      nack_retry += 1
      raise ::Protobuf::Nats::Errors::RequestTimeout, formatted_service_and_method_name if interval.nil?
      sleep((interval + nack_backoff_splay)/1000.0)
      next
    end

    break
  end

  parse_response
rescue ::Protobuf::Nats::Errors::IOException => error
  ::Protobuf::Nats.log_error(error)

  delay = reconnect_delay
  logger.warn "An IOException was raised. We are going to sleep for #{delay} seconds."
  sleep delay

  retry if (retries -= 1) > 0
  raise
end

#use_subscription_pooling? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protobuf/nats/client.rb', line 123

def use_subscription_pooling?
  return @use_subscription_pooling unless @use_subscription_pooling.nil?
  @use_subscription_pooling = self.class.subscription_pool_size > 0
end

#with_subscription ⇒ Object 



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# File 'lib/protobuf/nats/client.rb', line 53

def with_subscription
  return_value = nil

  if use_subscription_pooling?
    self.class.subscription_pool.with do |sub_inbox|
      return_value = yield sub_inbox
    end
  else
    return_value = yield new_subscription_inbox
  end

  return_value
end