track how quickly file size grows until Ctrl+C. follows symlinks

filesize_change_stats.rb

start_time = Time.now
files = {}
SAMPLE_INTERVAL = 2

def record_filesize(fds, sizes)
  loop do
    fds.each do |file|
      unless sizes[file]
        sizes[file] = []
      end

      sizes[file] << file.stat.size
    end

    sleep(SAMPLE_INTERVAL)
  end
end

def open_fds(filenames)
  fds = []

  filenames.map do |f|
    next if File.directory?(f)

    fds << File.open(f)
  rescue
    puts("File doesn't exist: #{f}, ignoring.")
  end

  fds
end

def calc_change(files, start_time)
  total_bytes = 0

  files.each do |fd, sizes|
    difference = []
    rotated = false

    sizes.each_with_index do |s, i|
      next if i==0

      difference << s - sizes[i-1]
      if difference.last < 0
        rotated = true
        break
      end

      total_bytes += difference.last
    end

    rate_of_change = difference.sum / difference.size
    next if rate_of_change == 0

    puts fd.path
    puts "Avg rate of change: #{rate_of_change/SAMPLE_INTERVAL} bytes/s #{"(rotated}" if rotated}\n\n"
  end

  avg_increase = total_bytes / (Time.now-start_time)
  puts "Total file size increase: #{total_bytes} bytes (in #{Time.now-start_time} seconds), or #{avg_increase} bytes/s"
end

Signal.trap("SIGINT") do
  puts("\nWatching: #{files.size} files")
  puts("Sampling interval: #{SAMPLE_INTERVAL} seconds\n")
  calc_change(files, start_time)

  exit
end

record_filesize(open_fds(ARGV), files)