Class: MessageBus::Rack::Middleware

Inherits:
Object
  • Object
show all
Defined in:
lib/message_bus/rack/middleware.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(app, config = {}) ⇒ Middleware

Returns a new instance of Middleware.



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# File 'lib/message_bus/rack/middleware.rb', line 35

def initialize(app, config = {})
  @app = app
  @bus = config[:message_bus] || MessageBus
  @connection_manager = MessageBus::ConnectionManager.new(@bus)
  self.start_listener
end

Class Method Details

.backlog_to_json(backlog) ⇒ Object 



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# File 'lib/message_bus/rack/middleware.rb', line 49

def self.backlog_to_json(backlog)
  m = backlog.map do |msg|
    {
      global_id: msg.global_id,
      message_id: msg.message_id,
      channel: msg.channel,
      data: msg.data
    }
  end.to_a
  JSON.dump(m)
end

Instance Method Details

#add_client_with_timeout(client) ⇒ Object 



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# File 'lib/message_bus/rack/middleware.rb', line 204

def add_client_with_timeout(client)
  @connection_manager.add_client(client)

  client.cleanup_timer = MessageBus.timer.queue(@bus.long_polling_interval.to_f / 1000) {
    begin
      client.cleanup_timer = nil
      client.ensure_closed!
      @connection_manager.remove_client(client)
    rescue
      @bus.logger.warn "Failed to clean up client properly: #{$!} #{$!.backtrace}"
    end
  }
end

#call(env) ⇒ Object 



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# File 'lib/message_bus/rack/middleware.rb', line 61

def call(env)

  return @app.call(env) unless env['PATH_INFO'] =~ /^\/message-bus\//

  # special debug/test route
  if @bus.allow_broadcast? && env['PATH_INFO'] == '/message-bus/broadcast'
    parsed = Rack::Request.new(env)
    @bus.publish parsed["channel"], parsed["data"]
    return [200, { "Content-Type" => "text/html" }, ["sent"]]
  end

  if env['PATH_INFO'].start_with? '/message-bus/_diagnostics'
    diags = MessageBus::Rack::Diagnostics.new(@app, message_bus: @bus)
    return diags.call(env)
  end

  client_id = env['PATH_INFO'].split("/")[2]
  return [404, {}, ["not found"]] unless client_id

  user_id = @bus.user_id_lookup.call(env) if @bus.user_id_lookup
  group_ids = @bus.group_ids_lookup.call(env) if @bus.group_ids_lookup
  site_id = @bus.site_id_lookup.call(env) if @bus.site_id_lookup

  # close db connection as early as possible
  close_db_connection!

  client = MessageBus::Client.new(message_bus: @bus, client_id: client_id,
                                  user_id: user_id, site_id: site_id, group_ids: group_ids)

  if channels = env['message_bus.channels']
    if seq = env['message_bus.seq']
      client.seq = seq.to_i
    end
    channels.each do |k, v|
      client.subscribe(k, v)
    end
  else
    request = Rack::Request.new(env)
    is_json = request.content_type && request.content_type.include?('application/json')
    data = is_json ? JSON.parse(request.body.read) : request.POST
    data.each do |k, v|
      if k == "__seq"
        client.seq = v.to_i
      else
        client.subscribe(k, v)
      end
    end
  end

  headers = {}
  headers["Cache-Control"] = "must-revalidate, private, max-age=0"
  headers["Content-Type"] = "application/json; charset=utf-8"
  headers["Pragma"] = "no-cache"
  headers["Expires"] = "0"

  if @bus.extra_response_headers_lookup
    @bus.extra_response_headers_lookup.call(env).each do |k, v|
      headers[k] = v
    end
  end

  if env["REQUEST_METHOD"] == "OPTIONS"
    return [200, headers, ["OK"]]
  end

  long_polling = @bus.long_polling_enabled? &&
                 env['QUERY_STRING'] !~ /dlp=t/ &&
                 @connection_manager.client_count < @bus.max_active_clients

  allow_chunked = env['HTTP_VERSION'] == 'HTTP/1.1'
  allow_chunked &&= !env['HTTP_DONT_CHUNK']
  allow_chunked &&= @bus.chunked_encoding_enabled?

  client.use_chunked = allow_chunked

  backlog = client.backlog

  if backlog.length > 0 && !allow_chunked
    client.cancel
    @bus.logger.debug "Delivering backlog #{backlog} to client #{client_id} for user #{user_id}"
    [200, headers, [self.class.backlog_to_json(backlog)] ]
  elsif long_polling && env['rack.hijack'] && @bus.rack_hijack_enabled?
    io = env['rack.hijack'].call
    # TODO disable client till deliver backlog is called
    client.io = io
    client.headers = headers
    client.synchronize do
      client.deliver_backlog(backlog)
      add_client_with_timeout(client)
      client.ensure_first_chunk_sent
    end
    [418, {}, ["I'm a teapot, undefined in spec"]]
  elsif long_polling && env['async.callback']
    response = nil
    # load extension if needed
    begin
      response = Thin::AsyncResponse.new(env)
    rescue NameError
      require 'message_bus/rack/thin_ext'
      response = Thin::AsyncResponse.new(env)
    end

    headers.each do |k, v|
      response.headers[k] = v
    end

    if allow_chunked
      response.headers["X-Content-Type-Options"] = "nosniff"
      response.headers["Transfer-Encoding"] = "chunked"
      response.headers["Content-Type"] = "text/plain; charset=utf-8"
    end

    response.status = 200
    client.async_response = response
    client.synchronize do
      add_client_with_timeout(client)
      client.deliver_backlog(backlog)
      client.ensure_first_chunk_sent
    end

    throw :async
  else
    [200, headers, [self.class.backlog_to_json(backlog)]]
  end

rescue => e
  if @bus.on_middleware_error && result = @bus.on_middleware_error.call(env, e)
    result
  else
    raise
  end
end

#close_db_connection! ⇒ Object 



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# File 'lib/message_bus/rack/middleware.rb', line 194

def close_db_connection!
  # IMPORTANT
  # ConnectionManagement in Rails puts a BodyProxy around stuff
  #  this means connections are not returned until rack.async is
  #  closed
  if defined? ActiveRecord::Base.clear_active_connections!
    ActiveRecord::Base.clear_active_connections!
  end
end

#start_listener ⇒ Object 



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# File 'lib/message_bus/rack/middleware.rb', line 9

def start_listener
  unless @started_listener

    thin = defined?(Thin::Server) && ObjectSpace.each_object(Thin::Server).to_a.first
    thin_running = thin && thin.running?

    @subscription = @bus.subscribe do |msg|
      run = proc do
        begin
          @connection_manager.notify_clients(msg) if @connection_manager
        rescue
          @bus.logger.warn "Failed to notify clients: #{$!} #{$!.backtrace}"
        end
      end

      if thin_running
        EM.next_tick(&run)
      else
        MessageBus.timer.queue(&run)
      end

      @started_listener = true
    end
  end
end

#stop_listener ⇒ Object 



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# File 'lib/message_bus/rack/middleware.rb', line 42

def stop_listener
  if @subscription
    @bus.unsubscribe(&@subscription)
    @started_listener = false
  end
end