Matt's Ruby Log Splitter

Matt Secoske posted a Log Splitter on his blog. I thought it was a fun exercise, so I wrote my own as well. My version is different in that I made the work of splitting files into a class of its own that understands the same protocol of IO stream (or the parts that I need right now). All you do is simply create it like any another File object, except add a block that evaluates when the file should be split into a new one. The code at the bottom uses it. I tried to keep close to the input parameters of Matt's original code. Later on, I inspired him and he came up with a DSL version. Remember, I whipped this code up pretty quickly and I was having a bit of fun with Ruby. Enjoy!

class SplitFile
  def self.open(suffix, mode, &when_to_split)
    self.new(suffix, mode, when_to_split)
  end
  
  def write_all(enumerable)
    enumerable.each {|line| write(line) }
  end
  
  def write(line)
    open_next() if should_split?(line) || @file.nil?
    @file.write(line)
  end
  
  def close()
    @file.close() unless @file.nil?
    @file = nil
  end
  
  private
  def initialize(suffix, mode, when_to_split)
    @suffix = suffix
    @mode = mode
    @when_to_split = when_to_split
    @file_count = -1
  end
  
  def open_next()
    close()
    file_name = next_file_name()
    puts "Writing file #{file_name}"
    @file = File.open(file_name, @mode)
  end
  
  def next_file_name()
    @file_count += 1
    "#{@file_count}_#{@suffix}"
  end
  
  def should_split?(line)
    @when_to_split.call(line)
  end
end


FILE_SUFFIX = ARGV[0] ? ARGV[0] : "split.log"
MAX_LINES = ARGV[1] ? ARGV[1].to_i : 500000

lines = 0
split=SplitFile.open(FILE_SUFFIX, 'w') do |line|
  lines += 1
  result = lines >= MAX_LINES
  lines = 0 if result
  result
end

begin
  split.write_all($stdin)
ensure
  split.close
end