module Signal
	def signame s
		case s      
		when String then s
		when Symbol then s.to_s
		when Fixnum then list.invert[s]
		end                            
	end                                    

	def sig s
		case s  
		when Fixnum then s
		when String then list[s]
		when Symbol then list[s.to_s]
		end                          
	end                                  

	list do |n, s|
		Signal.const_set n, s
		Signal.const_set "SIG#{n}", s
	end                                  

	def [] s
		case s 
		when String then list[s]
		when Symbol then list[s.to_s]
		when Fixnum then list.invert[s]
		else raise ArgumentError       
		end                            
	end                                    
end

class Retries
	attr_accessor :max, :range
	attr_reader :count, :last

	def initialize max = 10, range = 10
		@max, @range, @count, @last = max, range, 0, Time.now
	end

	def retry?
		@count = @last + @range > Time.now ? @count + 1 : 1
		@last = Time.now
		@count < @max
	end

	def run ex, &e
		begin e.call *args
		rescue ex
			retries.retry? and retry
		end
	end
end

class RobustServer
	def self.main *argv
		self.new( *argv).main
	end

	def initialize *p
		super *p
		sh = method :signal_handler
		@sigs = {
			Signal[:INT] => sh, Signal[:HUP] => nil, Signal[:TERM] => sh,
			Signal[:KILL] => sh, Signal[:USR1] => nil, Signal[:USR2] => nil
		}
	end

	def trapping
		@sigs.each { |s, p|  @sigs[s] = trap s, p  }  if @sigs
	end

	def signal_handler s
		@signal = s
	end

	def main max = nil, range = nil
		retries = Retries.new max, range
		trapping
		$stderr.puts "Arbeit wird nun aufgenommen..."
		begin
			self.run
		rescue SystemExit, Interrupt, SignalException
			$stderr.puts "Das Beenden des Programms wurde angefordert. #{$!}"
		rescue Object
			$stderr.puts [:rescue, $!, $!.class, $!.backtrace].inspect
			retry  if retries.retry?
			$stderr.print "Zuviele Fehler in zu kurzer Zeit.  Ich gebe auf und "
		end
		trapping
		$stderr.puts "Beende mich selbst."
	end
end