From: Eric Hodel <drbrain@...7.net>
Date: 2005-09-10T02:41:02+09:00
Subject: Re: Optimizing a single slow method

On 08 Sep 2005, at 20:46, Glenn M. Lewis wrote:

> Hi!
>     I have a Ruby script (a small part of it is included below)
> that has many methods, but one method is so incredibly slow that
> I would like to write it in C++ (or any other faster language).
>
>     The method is "Contract.parseFile(file)".  I've tried the
> latest SWIG, but am having a heck of a time trying to call the
> two methods: "Contract.open()" and "Contract.addTick()" from within
> the SWIG'd extension.  (By the way, I also tried "rio(file).csv {| 
> fields|"
> but that had the same speed as the code below.)
>
>     Any ideas on how I can rewrite 'Contract.parseFile()' for
> speed?
>
>     Thanks!
> -- Glenn Lewis
>
>   def Contract.parseFile(file)
>     return unless File.exists?(file)
>     return if @@files.has_key?(file)
>     @@files[file] = 1
>     print "Parsing file #{file}..."
>     File.open(file, "rb").each_line {|line|
>       line.chomp!
>       # puts line
>       fields = line.split(/,/)
>       next if fields.size < 8
>       datestring = fields[1]
>       year  = datestring[0..1].to_i
>       month = datestring[2..3].to_i
>       day   = datestring[4..5].to_i
>       # puts "year=#{year}, month=#{month}, day=#{day}"
>       # RUBY BUG?!?  Can't use 'date' here... as that messes up  
> findTick's 'date'...
>       mydate  = Date.new((year < 50 ? year+2000 : year+1900),  
> month, day)

Since Dates are created using Rational, so they can use up a  
significant amount of processing time.  Time is much better provided  
your dates fit within its bounds.

>       contract = Contract.open(fields[0])
>       tick = Tick.new(mydate, fields[2].to_f, fields[3].to_f,
>               fields[4].to_f, fields[5].to_f,
>               fields[6].to_i, fields[7].to_i)
>       contract.addTick(tick)
>     }
>     puts "done"
>   end

-- 
Eric Hodel - drbrain@segment7.net - http://segment7.net
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