Class: Avro::IPC::Requestor

Inherits:
Object
  • Object
show all
Defined in:
lib/avro/ipc.rb

Overview

Base class for the client side of a protocol interaction.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(local_protocol, transport) ⇒ Requestor

Returns a new instance of Requestor.



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# File 'lib/avro/ipc.rb', line 86

def initialize(local_protocol, transport)
  @local_protocol = local_protocol
  @transport = transport
  @remote_protocol = nil
  @remote_hash = nil
  @send_protocol = nil
end

Instance Attribute Details

#local_protocol ⇒ Object (readonly)

Returns the value of attribute local_protocol.



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# File 'lib/avro/ipc.rb', line 83

def local_protocol
  @local_protocol
end

#remote_hash ⇒ Object

Returns the value of attribute remote_hash.



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# File 'lib/avro/ipc.rb', line 83

def remote_hash
  @remote_hash
end

#remote_protocol ⇒ Object

Returns the value of attribute remote_protocol.



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# File 'lib/avro/ipc.rb', line 83

def remote_protocol
  @remote_protocol
end

#send_protocol ⇒ Object

Returns the value of attribute send_protocol.



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# File 'lib/avro/ipc.rb', line 84

def send_protocol
  @send_protocol
end

#transport ⇒ Object (readonly)

Returns the value of attribute transport.



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# File 'lib/avro/ipc.rb', line 83

def transport
  @transport
end

Instance Method Details

#read_call_response(message_name, decoder) ⇒ Object

Raises:



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# File 'lib/avro/ipc.rb', line 194

def read_call_response(message_name, decoder)
  # The format of a call response is:
  #   * response metadata, a map with values of type bytes
  #   * a one-byte error flag boolean, followed by either:
  #     * if the error flag is false,
  #       the message response, serialized per the message's response schema.
  #     * if the error flag is true,
  #       the error, serialized per the message's error union schema.
  _response_metadata = META_READER.read(decoder)

  # remote response schema
  remote_message_schema = remote_protocol.messages[message_name]
  raise AvroError.new("Unknown remote message: #{message_name}") unless remote_message_schema

  # local response schema
  local_message_schema = local_protocol.messages[message_name]
  unless local_message_schema
    raise AvroError.new("Unknown local message: #{message_name}")
  end

  # error flag
  if !decoder.read_boolean
    writers_schema = remote_message_schema.response
    readers_schema = local_message_schema.response
    read_response(writers_schema, readers_schema, decoder)
  else
    writers_schema = remote_message_schema.errors || SYSTEM_ERROR_SCHEMA
    readers_schema = local_message_schema.errors || SYSTEM_ERROR_SCHEMA
    raise read_error(writers_schema, readers_schema, decoder)
  end
end

#read_error(writers_schema, readers_schema, decoder) ⇒ Object 



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# File 'lib/avro/ipc.rb', line 231

def read_error(writers_schema, readers_schema, decoder)
  datum_reader = Avro::IO::DatumReader.new(writers_schema, readers_schema)
  AvroRemoteError.new(datum_reader.read(decoder))
end

#read_handshake_response(decoder) ⇒ Object 



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# File 'lib/avro/ipc.rb', line 168

def read_handshake_response(decoder)
  handshake_response = HANDSHAKE_REQUESTOR_READER.read(decoder)
  we_have_matching_schema = false

  case handshake_response['match']
  when 'BOTH'
    self.send_protocol = false
    we_have_matching_schema = true
  when 'CLIENT'
    raise AvroError.new('Handshake failure. match == CLIENT') if send_protocol
    self.remote_protocol = Avro::Protocol.parse(handshake_response['serverProtocol'])
    self.remote_hash = handshake_response['serverHash']
    self.send_protocol = false
    we_have_matching_schema = true
  when 'NONE'
    raise AvroError.new('Handshake failure. match == NONE') if send_protocol
    self.remote_protocol = Avro::Protocol.parse(handshake_response['serverProtocol'])
    self.remote_hash = handshake_response['serverHash']
    self.send_protocol = true
  else
    raise AvroError.new("Unexpected match: #{match}")
  end

  return we_have_matching_schema
end

#read_response(writers_schema, readers_schema, decoder) ⇒ Object 



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# File 'lib/avro/ipc.rb', line 226

def read_response(writers_schema, readers_schema, decoder)
  datum_reader = Avro::IO::DatumReader.new(writers_schema, readers_schema)
  datum_reader.read(decoder)
end

#request(message_name, request_datum) ⇒ Object 



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# File 'lib/avro/ipc.rb', line 104

def request(message_name, request_datum)
  # Writes a request message and reads a response or error message.
  # build handshake and call request
  buffer_writer = StringIO.new(String.new('', encoding: 'BINARY'))
  buffer_encoder = Avro::IO::BinaryEncoder.new(buffer_writer)
  write_handshake_request(buffer_encoder)
  write_call_request(message_name, request_datum, buffer_encoder)

  # send the handshake and call request;  block until call response
  call_request = buffer_writer.string
  call_response = transport.transceive(call_request)

  # process the handshake and call response
  buffer_decoder = Avro::IO::BinaryDecoder.new(StringIO.new(call_response))
  if read_handshake_response(buffer_decoder)
    read_call_response(message_name, buffer_decoder)
  else
    request(message_name, request_datum)
  end
end

#write_call_request(message_name, request_datum, encoder) ⇒ Object 



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# File 'lib/avro/ipc.rb', line 143

def write_call_request(message_name, request_datum, encoder)
  # The format of a call request is:
  #   * request metadata, a map with values of type bytes
  #   * the message name, an Avro string, followed by
  #   * the message parameters. Parameters are serialized according to
  #     the message's request declaration.

  # TODO request metadata (not yet implemented)
  request_metadata = {}
  META_WRITER.write(request_metadata, encoder)

  message = local_protocol.messages[message_name]
  unless message
    raise AvroError, "Unknown message: #{message_name}"
  end
  encoder.write_string(message.name)

  write_request(message.request, request_datum, encoder)
end

#write_handshake_request(encoder) ⇒ Object 



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# File 'lib/avro/ipc.rb', line 125

def write_handshake_request(encoder)
  local_hash = local_protocol.md5
  remote_name = transport.remote_name
  remote_hash = REMOTE_HASHES[remote_name]
  unless remote_hash
    remote_hash = local_hash
    self.remote_protocol = local_protocol
  end
  request_datum = {
    'clientHash' => local_hash,
    'serverHash' => remote_hash
  }
  if send_protocol
    request_datum['clientProtocol'] = local_protocol.to_s
  end
  HANDSHAKE_REQUESTOR_WRITER.write(request_datum, encoder)
end

#write_request(request_schema, request_datum, encoder) ⇒ Object 



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# File 'lib/avro/ipc.rb', line 163

def write_request(request_schema, request_datum, encoder)
  datum_writer = Avro::IO::DatumWriter.new(request_schema)
  datum_writer.write(request_datum, encoder)
end