Class: Firehose::Rack::Consumer::HttpLongPoll

Inherits:
Object
  • Object
show all
Includes:
Helpers
Defined in:
lib/firehose/rack/consumer.rb

Constant Summary collapse

TIMEOUT =

How long should we wait before closing out the consuming clients web connection for long polling? Most browsers timeout after a connection has been idle for 30s.

20

Instance Method Summary collapse

Methods included from Helpers

#response

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/firehose/rack/consumer.rb', line 34

def call(env)
  req     = env['parsed_request'] ||= ::Rack::Request.new(env)
  path    = req.path
  method  = req.request_method
  # Get the Last Message Sequence from the query string.
  # Ideally we'd use an HTTP header, but android devices don't let us
  # set any HTTP headers for CORS requests.
  last_sequence = req.params['last_message_sequence'].to_i

  case method
  # GET is how clients subscribe to the queue. When a messages comes in, we flush out a response,
  # close down the requeust, and the client then reconnects.
  when 'GET'
    Firehose.logger.debug "HTTP GET with last_sequence #{last_sequence} for path #{path} with query #{env["QUERY_STRING"].inspect} and params #{req.params.inspect}"
    EM.next_tick do

      if last_sequence < 0
        env['async.callback'].call response(400, "The last_message_sequence parameter may not be less than zero", response_headers(env))
      else
        Server::Channel.new(path).next_message(last_sequence, :timeout => TIMEOUT).callback do |message, sequence|
          env['async.callback'].call response(200, wrap_frame(message, sequence), response_headers(env))
        end.errback do |e|
          if e == :timeout
            env['async.callback'].call response(204, '', response_headers(env))
          else
            Firehose.logger.error "Unexpected error when trying to GET last_sequence #{last_sequence} for path #{path}: #{e.inspect}"
            env['async.callback'].call response(500, 'Unexpected error', response_headers(env))
          end
        end
      end

    end

    # Tell the web server that this will be an async response.
    ASYNC_RESPONSE

  else
    Firehose.logger.debug "HTTP #{method} not supported"
    response(501, "#{method} not supported.")
  end
end