From: Robert Klemme <shortcutter@...>
Date: 2007-11-26T21:35:41+09:00
Subject: Re: Moving files matching Regex

2007/11/26, Mark Woodward <markonlinux@internode.on.net>:
> On Sun, 25 Nov 2007 20:59:46 +1100
> Mark Woodward <markonlinux@internode.on.net> wrote:
>
> thanks to all replies. Very informative.
> I've benchmarked this and 'get_file_names2' is considerably quicker!
> (if I'm benchmarking correctly?)
>
> Could someone explain why? ie what is it about get_file_names2 that
> makes it so much quicker? What is it about get_file_names that slows it
> down?

In _2 you do a dir glob in *one* directory only while find recursively
descends a *directory tree*.  Even though you prune in some cases it
comes as no surprise that this is slower.

> def get_file_names
>   fn=[]
>   Find.find('./') do |path|
>     Find.prune if File.basename(path) == 'sent'
>     curr_file = File.basename(path)
>     if curr_file =~ FILE_REGEX
>       fn << curr_file
>     end
>   end
>   fn
> end
>
>
> def get_file_names2
>   fglob= %r{^(CAL|NCPH|GOH)\d{6}\.xls$}x
>   all_files = Dir.glob("*")
>   my_files  = all_files.grep(fglob)
> end
>
>
>
> Benchmark.bm(5) do |timer|
>   timer.report('get_file_names') {10000.times {get_file_names}}
>   timer.report('get_file_names2') {10000.times {get_file_names2}}
> end
>
>
> Results:
>
>                  user       system     total     real
> get_file_names   3.040000   0.700000   3.740000  (5.440394)
> get_file_names2  0.570000   0.160000   0.730000  (0.997355)
>

Kind regards

robert

-- 
use.inject do |as, often| as.you_can - without end