require 'fileutils'

module Cerberus
  class Latch
    #Emulate File.flock
    def self.lock(lock_file, options = {})
      if File.exist?(lock_file)
        modif_time = File::Stat.new(lock_file).mtime
        ttl = options[:lock_ttl]

        if ttl and modif_time + ttl < Time.now
          File.delete(lock_file)
        else
          return
        end
      end

      begin
        FileUtils.mkpath(File.dirname(lock_file))
        File.new(lock_file, 'w').close
        yield
      ensure
        File.delete(lock_file)
      end
    end
  end
end
