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
# 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
# Declare a block to be called before each dispatch.
# Run in the order declared.
def before_dispatch(*method_names, &block)
callbacks[:before].concat method_names
callbacks[:before] << block if block_given?
end
# Declare a block to be called after each dispatch.
# Run in reverse of the order declared.
def after_dispatch(*method_names, &block)
callbacks[:after].concat method_names
callbacks[:after] << block if block_given?
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)
# Already registered: update the existing callback
if identifier
if callback = callbacks[:prepare].assoc(identifier)
callback[1] = block
else
callbacks[:prepare] << [identifier, block]
end
else
callbacks[:prepare] << block
end
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_ROOT}/public" if defined? ::RAILS_ROOT
cattr_accessor :callbacks
self.callbacks = Hash.new { |h, k| h[k] = [] }
cattr_accessor :unprepared
self.unprepared = true
before_dispatch :reload_application
before_dispatch :prepare_application
after_dispatch :flush_logger
after_dispatch :cleanup_application
if defined? ActiveRecord
to_prepare :activerecord_instantiate_observers do
ActiveRecord::Base.instantiate_observers
end
end
def initialize(output, request = nil, response = nil)
@output, @request, @response = output, request, response
end
def dispatch
@@guard.synchronize do
begin
run_callbacks :before
handle_request
rescue Exception => exception
failsafe_rescue exception
ensure
run_callbacks :after, :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 reload_application
if Dependencies.load?
Routing::Routes.reload
self.unprepared = true
end
end
def prepare_application(force = false)
begin
require_dependency 'application' unless defined?(::ApplicationController)
rescue LoadError => error
raise unless error.message =~ /application\.rb/
end
ActiveRecord::Base.verify_active_connections! if defined?(ActiveRecord)
if unprepared || force
run_callbacks :prepare
self.unprepared = false
end
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(force = false)
if Dependencies.load? || force
ActiveRecord::Base.reset_subclasses if defined?(ActiveRecord)
Dependencies.clear
ActiveRecord::Base.clear_reloadable_connections! if defined?(ActiveRecord)
end
end
def flush_logger
RAILS_DEFAULT_LOGGER.flush if defined?(RAILS_DEFAULT_LOGGER) && RAILS_DEFAULT_LOGGER.respond_to?(:flush)
end
protected
def handle_request
@controller = Routing::Routes.recognize(@request)
@controller.process(@request, @response).out(@output)
end
def run_callbacks(kind, enumerator = :each)
callbacks[kind].send!(enumerator) do |callback|
case callback
when Proc; callback.call(self)
when String, Symbol; send!(callback)
when Array; callback[1].call(self)
else raise ArgumentError, "Unrecognized callback #{callback.inspect}"
end
end
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
