DU

#!/usr/bin/ruby

def human(size)
  units = 'kMGTPEZY'
  unit_index = -1
  size *= 10
  while size >= 10000 && unit_index < units.size - 1
    unit_index += 1
    size /= 1000
  end
  unit = unit_index >= 0 ? units[unit_index] : ''
  if unit_index >= 0 && size < 100
    return '%d.%d%s' % [size / 10, size % 10, unit]
  else
    return '%d%s' % [size / 10, unit]
  end
end

def parse_line(line)
  size, name = line.split(' ', 2)
  size = size.to_i
  [size, name.chomp]
end

def is_already_counted(name, seen_prefixes)
  while name.b =~ /\/[^\/]+$/n
    name = $`
    if seen_prefixes[name]
      return true
    end
  end
  return false
end

mu = Mutex.new
started = false
tmpfile = '/tmp/du.tmp'
TOP_N = 3

if true
  thread = Thread.new do
    while true
      sleep 0.1
      next if !File.exist?(tmpfile)
      mu.synchronize do
        Thread.exit if started
        dirs = 0
        total = 0
        tops = []
        seen_prefixes = {}
        IO.popen("sort -nr #{tmpfile}") do |pipe|
          pipe.each do |line|
            size, name = parse_line(line)
            dirs += 1
            if !is_already_counted(name, seen_prefixes)
              total += size
            end
            seen_prefixes[name] = true

            if tops.size < TOP_N
              tops << "#{name}:#{human(size)}"
            end
          end
        end
        Thread.exit if started
        msg = "\r#{human(total)}/#{human(dirs)} [#{tops * ' '}]"
        if msg.size > 79
          msg = msg[0,79]
        else
          msg = msg.ljust(79)
        end
        STDERR.print msg
      end
    end
  end
end

open('/tmp/du.out', 'w') do |of|
  IO.popen("du -b #{ARGV[0]} | tee #{tmpfile} | sort -n") do |pipe|
    pipe.each do |line|
      mu.synchronize do
        started = true
      end
      size, name = parse_line(line)
      line = "#{human(size)} #{name}"
      of.puts line
      puts line
    end
  end
end

if thread
  thread.join
end