module ActionController
# Dispatches requests to the appropriate controller and takes care of
# reloading the app after each request when Dependencies.load? is true.
class Dispatcher
@@guard = Mutex.new
class << self
def define_dispatcher_callbacks(cache_classes)
unless cache_classes
# Development mode callbacks
before_dispatch :reload_application
after_dispatch :cleanup_application
end
# Common callbacks
to_prepare :load_application_controller do
begin
require_dependency 'application' unless defined?(::ApplicationController)
rescue LoadError => error
raise unless error.message =~ /application\.rb/
end
end
if defined?(ActiveRecord)
before_dispatch { ActiveRecord::Base.verify_active_connections! }
to_prepare(:activerecord_instantiate_observers) { ActiveRecord::Base.instantiate_observers }
end
after_dispatch :flush_logger if defined?(RAILS_DEFAULT_LOGGER) && RAILS_DEFAULT_LOGGER.respond_to?(:flush)
end
# Backward-compatible class method takes CGI-specific args. Deprecated
# in favor of Dispatcher.new(output, request, response).dispatch.
def dispatch(cgi = nil, session_options = CgiRequest::DEFAULT_SESSION_OPTIONS, output = $stdout)
new(output).dispatch_cgi(cgi, session_options)
end
# Add a preparation callback. Preparation callbacks are run before every
# request in development mode, and before the first request in production
# mode.
#
# An optional identifier may be supplied for the callback. If provided,
# to_prepare may be called again with the same identifier to replace the
# existing callback. Passing an identifier is a suggested practice if the
# code adding a preparation block may be reloaded.
def to_prepare(identifier = nil, &block)
@prepare_dispatch_callbacks ||= ActiveSupport::Callbacks::CallbackChain.new
callback = ActiveSupport::Callbacks::Callback.new(:prepare_dispatch, block, :identifier => identifier)
@prepare_dispatch_callbacks | callback
end
# If the block raises, send status code as a last-ditch response.
def failsafe_response(fallback_output, status, originating_exception = nil)
yield
rescue Exception => exception
begin
log_failsafe_exception(status, originating_exception || exception)
body = failsafe_response_body(status)
fallback_output.write "Status: #{status}\r\nContent-Type: text/html\r\n\r\n#{body}"
nil
rescue Exception => failsafe_error # Logger or IO errors
$stderr.puts "Error during failsafe response: #{failsafe_error}"
$stderr.puts "(originally #{originating_exception})" if originating_exception
end
end
private
def failsafe_response_body(status)
error_path = "#{error_file_path}/#{status.to_s[0..3]}.html"
if File.exist?(error_path)
File.read(error_path)
else
"<html><body><h1>#{status}</h1></body></html>"
end
end
def log_failsafe_exception(status, exception)
message = "/!\\ FAILSAFE /!\\ #{Time.now}\n Status: #{status}\n"
message << " #{exception}\n #{exception.backtrace.join("\n ")}" if exception
failsafe_logger.fatal message
end
def failsafe_logger
if defined?(::RAILS_DEFAULT_LOGGER) && !::RAILS_DEFAULT_LOGGER.nil?
::RAILS_DEFAULT_LOGGER
else
Logger.new($stderr)
end
end
end
cattr_accessor :error_file_path
self.error_file_path = Rails.public_path if defined?(Rails.public_path)
include ActiveSupport::Callbacks
define_callbacks :prepare_dispatch, :before_dispatch, :after_dispatch
def initialize(output = $stdout, request = nil, response = nil)
@output, @request, @response = output, request, response
end
def dispatch
@@guard.synchronize do
begin
run_callbacks :before_dispatch
handle_request
rescue Exception => exception
failsafe_rescue exception
ensure
run_callbacks :after_dispatch, :enumerator => :reverse_each
end
end
end
def dispatch_cgi(cgi, session_options)
if cgi ||= self.class.failsafe_response(@output, '400 Bad Request') { CGI.new }
@request = CgiRequest.new(cgi, session_options)
@response = CgiResponse.new(cgi)
dispatch
end
rescue Exception => exception
failsafe_rescue exception
end
def call(env)
@request = RackRequest.new(env)
@response = RackResponse.new(@request)
dispatch
end
def reload_application
# Run prepare callbacks before every request in development mode
run_callbacks :prepare_dispatch
Routing::Routes.reload
ActionView::TemplateFinder.reload! unless ActionView::Base.cache_template_loading
end
# Cleanup the application by clearing out loaded classes so they can
# be reloaded on the next request without restarting the server.
def cleanup_application
ActiveRecord::Base.reset_subclasses if defined?(ActiveRecord)
ActiveSupport::Dependencies.clear
ActiveRecord::Base.clear_reloadable_connections! if defined?(ActiveRecord)
end
def flush_logger
RAILS_DEFAULT_LOGGER.flush
end
protected
def handle_request
@controller = Routing::Routes.recognize(@request)
@controller.process(@request, @response).out(@output)
end
def failsafe_rescue(exception)
self.class.failsafe_response(@output, '500 Internal Server Error', exception) do
if @controller ||= defined?(::ApplicationController) ? ::ApplicationController : Base
@controller.process_with_exception(@request, @response, exception).out(@output)
else
raise exception
end
end
end
end
end
