From: bwv549 <jtprince@...>
Date: 2008-11-07T02:18:11+09:00
Subject: Re: how to quickly find a string towards the end of a large io object

Here's roughly what I'm using right now (sort of an amalgamation of
everyone's thoughts):

File.open(filename) do |handle|
      halfway = handle.stat.size / 2
      handle.seek halfway
      last_half = handle.read
      params_start_index = last_half.rindex(my_substring) + halfway
end

using rindex this takes .17 sec on an 85MB file
using index it takes  .45 sec on the same file

Those numbers argue that rindex indeed seeks from the end.

Thanks for everyone's help and I will check back to see if there are
any more thoughts.