dispatcher.rb

   1 module ActionController
   2   # Dispatches requests to the appropriate controller and takes care of
   3   # reloading the app after each request when Dependencies.load? is true.
   4   class Dispatcher
   5     @@guard = Mutex.new
   6
   7     class << self
   8       def define_dispatcher_callbacks(cache_classes)
   9         unless cache_classes
  10           # Development mode callbacks
  11           before_dispatch :reload_application
  12           after_dispatch :cleanup_application
  13         end
  14
  15         # Common callbacks
  16         to_prepare :load_application_controller do
  17           begin
  18             require_dependency 'application' unless defined?(::ApplicationController)
  19           rescue LoadError => error
  20             raise unless error.message =~ /application\.rb/
  21           end
  22         end
  23
  24         if defined?(ActiveRecord)
  25           after_dispatch :checkin_connections
  26           to_prepare(:activerecord_instantiate_observers) { ActiveRecord::Base.instantiate_observers }
  27         end
  28
  29         after_dispatch :flush_logger if Base.logger && Base.logger.respond_to?(:flush)
  30
  31         to_prepare do
  32           I18n.reload!
  33         end
  34       end
  35
  36       # Backward-compatible class method takes CGI-specific args. Deprecated
  37       # in favor of Dispatcher.new(output, request, response).dispatch.
  38       def dispatch(cgi = nil, session_options = CgiRequest::DEFAULT_SESSION_OPTIONS, output = $stdout)
  39         new(output).dispatch_cgi(cgi, session_options)
  40       end
  41
  42       # Add a preparation callback. Preparation callbacks are run before every
  43       # request in development mode, and before the first request in production
  44       # mode.
  45       #
  46       # An optional identifier may be supplied for the callback. If provided,
  47       # to_prepare may be called again with the same identifier to replace the
  48       # existing callback. Passing an identifier is a suggested practice if the
  49       # code adding a preparation block may be reloaded.
  50       def to_prepare(identifier = nil, &block)
  51         @prepare_dispatch_callbacks ||= ActiveSupport::Callbacks::CallbackChain.new
  52         callback = ActiveSupport::Callbacks::Callback.new(:prepare_dispatch, block, :identifier => identifier)
  53         @prepare_dispatch_callbacks.replace_or_append!(callback)
  54       end
  55
  56       # If the block raises, send status code as a last-ditch response.
  57       def failsafe_response(fallback_output, status, originating_exception = nil)
  58         yield
  59       rescue Exception => exception
  60         begin
  61           log_failsafe_exception(status, originating_exception || exception)
  62           body = failsafe_response_body(status)
  63           fallback_output.write "Status: #{status}\r\nContent-Type: text/html\r\n\r\n#{body}"
  64           nil
  65         rescue Exception => failsafe_error # Logger or IO errors
  66           $stderr.puts "Error during failsafe response: #{failsafe_error}"
  67           $stderr.puts "(originally #{originating_exception})" if originating_exception
  68         end
  69       end
  70
  71       private
  72         def failsafe_response_body(status)
  73           error_path = "#{error_file_path}/#{status.to_s[0..3]}.html"
  74
  75           if File.exist?(error_path)
  76             File.read(error_path)
  77           else
  78             "<html><body><h1>#{status}</h1></body></html>"
  79           end
  80         end
  81
  82         def log_failsafe_exception(status, exception)
  83           message = "/!\\ FAILSAFE /!\\  #{Time.now}\n  Status: #{status}\n"
  84           message << "  #{exception}\n    #{exception.backtrace.join("\n    ")}" if exception
  85           failsafe_logger.fatal message
  86         end
  87
  88         def failsafe_logger
  89           if defined?(::RAILS_DEFAULT_LOGGER) && !::RAILS_DEFAULT_LOGGER.nil?
  90             ::RAILS_DEFAULT_LOGGER
  91           else
  92             Logger.new($stderr)
  93           end
  94         end
  95     end
  96
  97     cattr_accessor :error_file_path
  98     self.error_file_path = Rails.public_path if defined?(Rails.public_path)
  99
 100     include ActiveSupport::Callbacks
 101     define_callbacks :prepare_dispatch, :before_dispatch, :after_dispatch
 102
 103     def initialize(output = $stdout, request = nil, response = nil)
 104       @output, @request, @response = output, request, response
 105     end
 106
 107     def dispatch_unlocked
 108       begin
 109         run_callbacks :before_dispatch
 110         handle_request
 111       rescue Exception => exception
 112         failsafe_rescue exception
 113       ensure
 114         run_callbacks :after_dispatch, :enumerator => :reverse_each
 115       end
 116     end
 117
 118     def dispatch
 119       if ActionController::Base.allow_concurrency
 120         dispatch_unlocked
 121       else
 122         @@guard.synchronize do
 123           dispatch_unlocked
 124         end
 125       end
 126     end
 127
 128     def dispatch_cgi(cgi, session_options)
 129       if cgi ||= self.class.failsafe_response(@output, '400 Bad Request') { CGI.new }
 130         @request = CgiRequest.new(cgi, session_options)
 131         @response = CgiResponse.new(cgi)
 132         dispatch
 133       end
 134     rescue Exception => exception
 135       failsafe_rescue exception
 136     end
 137
 138     def call(env)
 139       @request = RackRequest.new(env)
 140       @response = RackResponse.new(@request)
 141       dispatch
 142     end
 143
 144     def reload_application
 145       # Run prepare callbacks before every request in development mode
 146       run_callbacks :prepare_dispatch
 147
 148       Routing::Routes.reload
 149       ActionController::Base.view_paths.reload!
 150       ActionView::Helpers::AssetTagHelper::AssetTag::Cache.clear
 151     end
 152
 153     # Cleanup the application by clearing out loaded classes so they can
 154     # be reloaded on the next request without restarting the server.
 155     def cleanup_application
 156       ActiveRecord::Base.reset_subclasses if defined?(ActiveRecord)
 157       ActiveSupport::Dependencies.clear
 158       ActiveRecord::Base.clear_reloadable_connections! if defined?(ActiveRecord)
 159     end
 160
 161     def flush_logger
 162       Base.logger.flush
 163     end
 164
 165     def mark_as_test_request!
 166       @test_request = true
 167       self
 168     end
 169
 170     def test_request?
 171       @test_request
 172     end
 173
 174     def checkin_connections
 175       # Don't return connection (and peform implicit rollback) if this request is a part of integration test
 176       return if test_request?
 177       ActiveRecord::Base.clear_active_connections!
 178     end
 179
 180     protected
 181       def handle_request
 182         @controller = Routing::Routes.recognize(@request)
 183         @controller.process(@request, @response).out(@output)
 184       end
 185
 186       def failsafe_rescue(exception)
 187         self.class.failsafe_response(@output, '500 Internal Server Error', exception) do
 188           if @controller ||= defined?(::ApplicationController) ? ::ApplicationController : Base
 189             @controller.process_with_exception(@request, @response, exception).out(@output)
 190           else
 191             raise exception
 192           end
 193         end
 194       end
 195   end
 196 end