New version of Rak
I released a new version of Rak today with some bug fixes and enhancements.
New features:
- Colouring works on Windows if win32console gem is installed, fails gracefully if not.
- Added .rake, .erb and .haml to Ruby filetypes.
- Added match only at end-of/start-of line options
Thanks to Edvard Majakari, Kevin Ballard, Esad Hajdarevic, Bela Babik, Genki Takiuchi and Rob Knight for suggestions and fixes.
Using Meta-Programming for Performance in Ruby
Normally we use meta-programming in Ruby for our own convenience as developers, and we swallow the speed hit it gives us as a reasonable trade-off. The way Rak is implemented turns this on its head.
Rak compiles its line matching code on the fly, to speed up searching. Its not as horrendous as it sounds. Here’s a very simplified version of the line matching code without the optimization:
def line_match(filename, regex, line)
if options[:invert_match]
unless line =~ regex
if options[:print_filename]
puts filename
end
puts line
end
else
if line =~ regex
if options[:print_filename]
puts filename
end
puts line
end
end
end
We notice that the options hash never changes once the searching has begun. But we are doing an awful lot of work checking the values in the hash for every single line we are matching against. So we replace it with this:
def compile_line_match(filename, regex, line)
code = []
code << %{def line_match(filename, regex, line) }
if options[:invert_match]
code << %{ unless line =~ regex }
if options[:print_filename]
code << %{ puts filename }
end
code << %{ puts line }
code << %{ end }
else
code << %{ if line =~ regex }
if options[:print_filename]
code << %{ puts filename }
end
code << %{ puts line }
code << %{ end }
end
code << %{end }
module_eval code.join("\\n")
end
I’ve preserved the indenting so you can see the logic of the method. Here all the option tests have been factored out and will only be done once, at startup. Assuming we are not inverting the match and are printing filenames, the final compiled method looks like this:
def line_match(filename, regex, line)
if line =~ regex
puts filename
puts line
end
end
Much smaller. This method is 140 lines long in the full version, so its a much more impressive win there. All told this sped up Rak by about two times when I tested it searching on my Phd repository (3500 files).
There’s more work to do optimizing Rak. It’s still not as fast as Ack, so you might want to use that unless you are a Ruby fanboy like me :). But I have some more ideas….
Update 20/04/08: thankyou to redditer tomel for pointing out a WTF in the above code :).
Rak, a grep replacement in pure-Ruby
Rak is a tool for searching directories for files matching a regexp, like a more convenient grep. It gives you pretty highlighted output, and uses the Ruby regexp syntax. To install type gem install rak.
Rak is implemented in pure Ruby, so it should work on all platforms. Windows folk will probably find they need to use the –nocolour option (I will fix this next time I boot into Windows for any reason).
NB. Rak is an almost perfect clone of the Perl tool Ack by Andy Lester. He should get all the credit for the idea.
About
Daniel Lucraft, London, UK. Interested in Ruby, Prolog and software.