class Seahorse::Client::H2::Handler

def call(context)
  stream = nil
  begin
    conn = context.client.connection
    stream = conn.new_stream
    stream_mutex = Mutex.new
    close_condition = ConditionVariable.new
    sync_queue = Queue.new
    conn.connect(context.http_request.endpoint)
    _register_callbacks(
      context.http_response,
      stream,
      stream_mutex,
      close_condition,
      sync_queue
    )
    conn.debug_output("sending initial request ...")
    if input_emitter = context[:input_event_emitter]
      _send_initial_headers(context.http_request, stream)
      # prepare for sending events later
      input_emitter.stream = stream
      # request sigv4 serves as the initial #prior_signature
      input_emitter.encoder.prior_signature =
        context.http_request.headers['authorization'].split('Signature=').last
      input_emitter.validate_event = context.config.validate_params
    else
      _send_initial_headers(context.http_request, stream)
      _send_initial_data(context.http_request, stream)
    end
    conn.start(stream)
  rescue *NETWORK_ERRORS => error
    error = NetworkingError.new(
      error, error_message(context.http_request, error))
    context.http_response.signal_error(error)
  rescue => error
    conn.debug_output(error.inspect)
    # not retryable
    context.http_response.signal_error(error)
  end
  AsyncResponse.new(
    context: context,
    stream: stream,
    stream_mutex: stream_mutex,
    close_condition: close_condition,
    sync_queue: sync_queue
  )
end