Class: Skein::Client::RPC

Inherits:
Skein::Connected show all
Defined in:
lib/skein/client/rpc.rb

Defined Under Namespace

Classes: RPCException

Constant Summary collapse

EXCHANGE_NAME_DEFAULT =

Constants ============================================================

''.freeze

Instance Attribute Summary

Attributes inherited from Skein::Connected

#connection, #context, #ident

Instance Method Summary collapse

Methods inherited from Skein::Connected

#channel, #connect, #connection_shared?, #create_channel, #lock, #reconnect, #repeat_until_not_nil

Constructor Details

#initialize(exchange_name = nil, routing_key: nil, connection: nil, context: nil, ident: nil, expiration: nil, persistent: true, durable: true, timeout: nil) ⇒ RPC

Instance Methods =====================================================



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# File 'lib/skein/client/rpc.rb', line 18

def initialize(exchange_name = nil, routing_key: nil, connection: nil, context: nil, ident: nil, expiration: nil, persistent: true, durable: true, timeout: nil)
  super(connection: connection, context: context, ident: ident)

  @routing_key = routing_key
  @timeout = timeout

  @rpc_exchange = self.channel.direct(
    exchange_name || EXCHANGE_NAME_DEFAULT,
    durable: durable
  )

  @response_queue = self.channel.queue(
    @ident,
    durable: false,
    header: true,
    auto_delete: true
  )
  @expiration = expiration
  @persistent = !!persistent

  @callback = { }

  @consumer = Skein::Adapter.subscribe(@response_queue, block: false) do |payload, delivery_tag, reply_to|
    self.context.trap do
      if (ENV['SKEIN_DEBUG_JSON'])
        $stdout.puts(payload)
      end

      response = JSON.load(payload)

      if (callback = @callback.delete(response['id']))
        if (response['error'])
          exception =
            case (response['error'] and response['error']['code'])
            when -32601
              NoMethodError.new(
                "%s from `%s' RPC call" % [
                  response.dig('error', 'message'),
                  response.dig('error', 'data', 'method')
                ]
              )
            when -32602
              ArgumentError.new(
                response.dig('error', 'data', 'message') || 'wrong number of arguments'
              )
            else
              RPCException.new(
                response.dig('error', 'data', 'message') || response.dig('error', 'message')
              )
            end

          case (callback)
          when Skein::TimeoutQueue
            callback << exception
          when Proc
            callback.call(exception)
          end
        else
          case (callback)
          when Skein::TimeoutQueue
            callback << response['result']
          when Proc
            callback.call(response['result'])
          end
        end
      end

      self.channel.acknowledge(delivery_tag)
    end
  end
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(name, *args, &block) ⇒ Object 



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# File 'lib/skein/client/rpc.rb', line 107

def method_missing(name, *args, &block)
  name = name.to_s

  blocking = !name.sub!(/!\z/, '')

  message_id = SecureRandom.uuid
  request = JSON.dump(
    jsonrpc: '2.0',
    method: name,
    params: args,
    id: message_id
  )

  @rpc_exchange.publish(
    request,
    routing_key: @routing_key,
    reply_to: blocking ? @ident : nil,
    content_type: 'application/json',
    message_id: message_id,
    persistent: @persistent,
    expiration: @expiration
  )

  if (block_given?)
    @callback[message_id] =
      if (defined?(EventMachine))
        EventMachine.next_tick(&block)
      else
        block
      end
  elsif (blocking)
    queue = Skein::TimeoutQueue.new(blocking: true, timeout: @timeout)

    @callback[message_id] = queue

    case (result = queue.pop)
    when Exception
      raise result
    else
      result
    end
  end
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/skein/client/rpc.rb', line 100

def close
  @consumer&.cancel
  @consumer = nil

  super
end

#reroute!(routing_key) ⇒ Object

Temporarily deliver RPC calls to a different routing key. The supplied block is executed with this temporary routing in effect.



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# File 'lib/skein/client/rpc.rb', line 92

def reroute!(routing_key)
  routing_key, @routing_key = @routing_key, routing_key

  yield if (block_given?)

  @routing_key = routing_key
end