lazy_initialize

# File lib/resolv.rb, line 185
    def lazy_initialize # :nodoc:
      @mutex.synchronize {
        unless @initialized
          @name2addr = {}
          @addr2name = {}
          open(@filename, 'rb') {|f|
            f.each {|line|
              line.sub!(/#.*/, '')
              addr, hostname, *aliases = line.split(/\s+/)
              next unless addr
              addr.untaint
              hostname.untaint
              @addr2name[addr] = [] unless @addr2name.include? addr
              @addr2name[addr] << hostname
              @addr2name[addr] += aliases
              @name2addr[hostname] = [] unless @name2addr.include? hostname
              @name2addr[hostname] << addr
              aliases.each {|n|
                n.untaint
                @name2addr[n] = [] unless @name2addr.include? n
                @name2addr[n] << addr
              }
            }
          }
          @name2addr.each {|name, arr| arr.reverse!}
          @initialized = true
        end
      }
      self
    end