From: Dominik Bathon <dbatml@...>
Date: 2006-07-17T03:39:28+09:00
Subject: Re: How to speed up ruby and make it as fast as possible

On Sun, 16 Jul 2006 09:40:47 +0200, Austin Ziegler <halostatue@gmail.com>  
wrote:

> On 7/14/06, Dominik Bathon <dbatml@gmx.de> wrote:
>> Ruby2CExtension doesn't support 100% of Ruby's features, but it supports
>> enough to handle real world libraries. It can compile Austin Ziegler's
>> PDF::Writer for example (with some small changes). The resulting C
>> extension is about 33% faster (i.e. 3s instead of 4s) than the Ruby  
>> code.
>
> I'd love to hear what those changes are.

Here they are:

diff -ruw lib_orig/pdf/writer/fontmetrics.rb lib/pdf/writer/fontmetrics.rb
--- lib_orig/pdf/writer/fontmetrics.rb  2005-06-16 06:28:25.000000000 +0200
+++ lib/pdf/writer/fontmetrics.rb       2006-07-08 01:33:40.000000000 +0200
@@ -57,6 +57,7 @@
      font = nil
      afm = nil

+    resss = nil
      metrics_path.each do |path|
        afm_file  = File.join(path, "#{name}.afm").gsub(/\.afm\.afm$/o,  
".afm")
        rfm_file  = "#{afm_file}.rfm"
@@ -67,7 +68,8 @@
          if File.exists?(rfm_file)
            data = File.open(rfm_file, "rb") { |file| file.read }
            font = Marshal.load(data)
-          return font
+          resss = font
+          break
          end
        rescue
          nil
@@ -188,6 +190,7 @@
        end rescue nil # Ignore file errors
        break unless font.nil?
      end
+    return resss if resss

      raise ArgumentError, "Font #{font_name} not found." if font.nil?
      font

This is because return from inside a block is not supported.

diff -ruw lib_orig/pdf/writer.rb lib/pdf/writer.rb
--- lib_orig/pdf/writer.rb      2005-09-07 19:01:14.000000000 +0200
+++ lib/pdf/writer.rb   2006-07-08 01:34:32.000000000 +0200
@@ -1687,7 +1687,7 @@
      tw = width / size.to_f * 1000

      pos = -1
-    loop do
+    while true
        pos += 1
        break if pos == text.size
        font_change = true

Again because return from inside a block is not supported (so I just  
changed the block to a while loop).

diff -ruw lib_orig/transaction/simple.rb lib/transaction/simple.rb
--- lib_orig/transaction/simple.rb      2005-05-05 18:16:49.000000000 +0200
+++ lib/transaction/simple.rb   2006-07-08 01:33:00.000000000 +0200
@@ -650,7 +650,8 @@
          if respond_to?(:instance_variable_get)
            instance_variable_set(vv, rr.instance_variable_get(vv))
          else
-          instance_eval(%q|#{vv} = rr.instance_eval("#{vv}")|)
+          $__________xxxxxxxx___rr = rr
+          instance_eval(%q|#{vv} =  
$__________xxxxxxxx___rr.instance_eval("#{vv}")|)
          end
        end

This is because the instance_eval wouldn't see the local variable rr.

That's all that I changed to get it to compile and the resulting C  
extension seems to work correctly with the demos.


Dominik