digitaldisorder

Just a quick review of my old post.

As some of my commenters pointed out it's now possible to manage OpenSSL and Readline libraries from inside RVM. This will solve some of the problems when Ruby and operating system need different versions of the libraries.

The fast way to get everything going is just use:

bash < <(curl -s https://raw.github.com/wayneeseguin/rvm/master/binscripts/rvm-installer )

echo '[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm" # Load RVM function' >> ~/.bashrc

rvm pkg install readline
rvm pkg install iconv
rvm pkg install zlib
rvm pkg install openssl

rvm install 1.9.2 --with-readline-dir=$rvm_path/usr,--with-iconv-dir=$rvm_path/usr,--with-zlib-dir=$rvm_path/usr,--with-openssl-dir=$rvm_path/usr

Et voila! You've got everything installed, without jumping between RVM documentation pages.

Every time i start a new project I'm searching for a good guide on how to setup rspec, guard and spork to play nice together.

Setup gemfile by adding:

gem "spork"
  gem "guard"
  gem "guard-rspec"
  gem "guard-spork"
  gem "rb-inotify" if linux?
  gem "libnotify" if linux?

Method linux? is a little helper that i created so I don't annoy my mac loving friends it's just:

def linux?
  RUBY_PLATFORM.downcase.include?("linux")
end

that I use everytime I'm including gem that was made specificaly for Linux. At the end we have to run:

bundle install

Setup sport

spork --bootstrap

Setup guard

guard init spork
guard init rspec

Customize spec_helper.rb

Last thing is to customize spec_helper for spork:

require 'rubygems'
require 'spork'

Spork.prefork do
  ENV["RAILS_ENV"] ||= 'test'
  require File.expand_path("../../config/environment", __FILE__)
  require 'rspec/rails'
  require 'rspec/autorun'

  require 'factories'

  if RUBY_PLATFORM !~ /java/
    require 'simplecov'
    require 'simplecov-rcov'
    SimpleCov.formatter = SimpleCov::Formatter::RcovFormatter
    SimpleCov.start 'rails'
  end

  Dir[Rails.root.join("spec/support/**/*.rb")].each {|f| require f}

  RSpec.configure do |config|
    config.mock_with :rspec
    config.infer_base_class_for_anonymous_controllers = false
  end
end

Spork.each_run do
  # This code will be run each time you run your specs.
end

One of those aaaaaaahhhhhh moments

Extjs has a wonderful scope parameter that will let you specify the scope in which the function must be executed.

I just stumbled at the following piece of code, in my news showing component that is supposed to open in new window a link to PDF file.

{xtype: 'button', text: 'PDF', icon: '/images/pdf.png',
      handler: function() {
        var cmp = Ext.getCmp('newslist');
        var selModel = cmp.getSelectionModel();
        var record = selModel.getLastSelected();
        if (record) {
          open_new_window(record.getPDFUrl());
        }
      }
    }

As you can see, to get the selected item I have to find the grid component, selection model and retrieve the record. In my component I'm already storing the record in the 'record' attribute. Using scopes I can easily retrieve it. Which can be refactored to simple:

{xtype: 'button', text: 'PDF', icon: '/images/pdf.png', scope: this,
      handler: function() { 
        open_new_window(this.record.getPDFUrl()); 
      }
    },

When scope is not defined this is referring to the handler function object.

Posterous UI is great. I like the themes. I like the UI for writing new posts. The only thing I don't like is the little widget that is appearing in the top right corner of the screen. The idea is great - to let you access basic administration functionalities but there is one little thing that is really annoying: 

I decided to port all my Rails projects to use the rvm and rvmrc to have separate environment and avoid conflicts between gems. 

My frustration only grew when I was trying to update Ruby on my debian squeeze.

First shot:

rvm install ruby-head

Failed!

compiling ossl_ssl.c
ossl_ssl.c:110:1: error: ‘SSLv2_method’ undeclared here (not in a function)
ossl_ssl.c:111:1: error: ‘SSLv2_server_method’ undeclared here (not in a function)
ossl_ssl.c:112:1: error: ‘SSLv2_client_method’ undeclared here (not in a function)
make[2]: *** [ossl_ssl.o] Error 1

It's because debian removed support for SSLv2 which is deprecated because of security problems

rvm install ruby-1.9.2

Failed!

PIC -I. -I.ext/include/i686-linux -I./include -I. -DRUBY_EXPORT   -o dmyversion.o -c dmyversion.c
In file included from vm.c:26:0:
vm_eval.c: In function ‘loop_i’:
vm_eval.c:801:1: internal compiler error: in dfs_enumerate_from, at cfganal.c:1207
Please submit a full bug report,
with preprocessed source if appropriate.
See <file:///usr/share/doc/gcc-4.5/README.Bugs> for instructions.
make: *** [vm.o] Error 1

Which means it's a bug in compiler itself! There is regression bug in gcc 4.5, there are some patches backported from 4.6 but I would have to patch gcc by hand.

rvm install ruby-1.9.1

ossl_ssl.c:1201:2: warning: passing argument 1 of ‘sk_value’ from incompatible pointer type
/usr/include/openssl/stack.h:80:7: note: expected ‘const struct _STACK *’ but argument is of type ‘struct stack_st_X509 *’
ossl_ssl.c: In function ‘ossl_ssl_get_cipher’:
ossl_ssl.c:1223:12: warning: assignment discards qualifiers from pointer target type
ossl_pkcs7.c:575:14: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
ossl_pkcs7.c: In function ‘ossl_pkcs7_set_certificates’:
ossl_pkcs7.c:613:5: warning: implicit declaration of function ‘pkcs7_get_certs_or_crls’
ossl_pkcs7.c:613:11: warning: assignment makes pointer from integer without a cast
ossl_pkcs7.c: In function ‘ossl_pkcs7_get_certificates’:
ossl_pkcs7.c:623:5: warning: passing argument 1 of ‘ossl_x509_sk2ary’ makes pointer from integer without a cast
ossl.h:117:7: note: expected ‘struct stack_st_X509 *’ but argument is of type ‘int’
ossl_pkcs7.c: In function ‘ossl_pkcs7_set_crls’:
ossl_pkcs7.c:653:10: warning: assignment makes pointer from integer without a cast
ossl_pkcs7.c: In function ‘ossl_pkcs7_get_crls’:
ossl_pkcs7.c:663:5: warning: passing argument 1 of ‘ossl_x509crl_sk2ary’ makes pointer from integer without a cast
ossl.h:118:7: note: expected ‘struct stack_st_X509_CRL *’ but argument is of type ‘int’
make[1]: *** [ossl_pkcs7.o] Error 1

So finally I decided that the easiest way will be to remove the checks for SSLv2 in Ruby and created this patch:

cat  /tmp/disable_ssl2.patch 
diff --git a/ext/openssl/ossl_ssl.c b/ext/openssl/ossl_ssl.c
index d8951fb..4254b76 100644
--- a/ext/openssl/ossl_ssl.c
+++ b/ext/openssl/ossl_ssl.c
@@ -107,9 +107,11 @@ struct {
     OSSL_SSL_METHOD_ENTRY(TLSv1),
     OSSL_SSL_METHOD_ENTRY(TLSv1_server),
     OSSL_SSL_METHOD_ENTRY(TLSv1_client),
-    OSSL_SSL_METHOD_ENTRY(SSLv2),
+/*
+OSSL_SSL_METHOD_ENTRY(SSLv2),
     OSSL_SSL_METHOD_ENTRY(SSLv2_server),
     OSSL_SSL_METHOD_ENTRY(SSLv2_client),
+*/
     OSSL_SSL_METHOD_ENTRY(SSLv3),
     OSSL_SSL_METHOD_ENTRY(SSLv3_server),
     OSSL_SSL_METHOD_ENTRY(SSLv3_client),

So now you can successfully compile ruby using:

   rvm install ruby-head --patch /tmp/disable_ssl2.patch   

And finally success!!!!

ruby --version
ruby 1.8.7 (2010-12-23 patchlevel 330) [i686-linux]

It works also for ruby 1.9.2

rvm install ruby-1.9.2 --patch /tmp/disable_ssl2.patch

ruby --version 
ruby 1.9.2p180 (2011-02-18 revision 30909) [i686-linux]

For a long time I was planning to encrypt my hard disk on my laptop (I'm running Linux Debian unstable). I was afraid of complicated bootup process, risk of loosing my data and of course performance penalty related to encryption of all IO operations. Finally when I lost my phone (it was later returned by some good Samaritan) I said to myself that I don't want anyone looking trough my files when something similar happens to my laptop.

While I found some good step by step guides and performance tests of different encryption algorithms I didn't know what to expect from normal user point of view. I didn't like the idea of encrypting only one directory or maybe just my home directory so I went with full hdd encryption offered by dm-crypt (default options for algorithm). It could be also important to tell that my hard disk is Western Digital - WD5000BEKT - 500GB 7200RPM 2.5" with 16MB of cache, if you are using SSD your results can be different.

Below you can find the CPU load of krcyptd (which is responsible for fs encryption) - it's no scientific study it's just my observation:

• find -name *.jpg - cpu load: 4%
• copy of 1GB file - cpu load: 17%
• digikam scanning all my 70GB of photos - cpu load: 10-14% (digikam doing all the work takes 50-70%)
• apt-get dist-upgrade - cpu load: 8-13% (dpkg uncompressing and running installation scripts 11%)
• tar zxvf linux-2.6.38.tar.gz - 50-60% 
• compiling linux kernel - 5% (and the rest is taken by cc) (*)

What does it mean? It means that on not-so-modern system like mine (dual core T8300 @ 2.40Ghz) it takes virtually no processing power to secure your data, even for IO intensive tasks like copying files CPU will not be a problem. 

* in some guides you can read that performance is acceptable if you are not compiling code. I think it's acceptable in every case and as you can see even when you are compiling big source trees. 

If you are tired of switching perspectives from Java to Debug in Eclipse everytime you want to see the output from your emulator or real divce just use the old good.

adb logcat

you can chain it with grep and other commands to facilitate debugging of just one class...

Probably obvious but it took me some time and frustration to discover, even if I was using it when installing Cyanogen.

Using Rails 3 I couldn't figure out how stop autotest to run in infinite loop making my laptop fans turn constantly.

I found several posts on the web telling to add hooks to .autotest but all were missing some files or directories, finally I arrived to the magical combination that solved the problem:

Autotest.add_hook :initialize do |at|
    %w{.svn .hg .git vendor rerun.txt tmp log}.each {|exception| at.add_exception(exception)}
end

No monitoring of tmp/log/vendor and source control directories.

Are you tired of adding --no-ri and --no-rdoc everytime you install a new gem?

You can configure the default options used by gem in your .gemrc, just add those two lines:

install: --no-rdoc --no-ri
update: --no-rdoc --no-ri

and don't worry anymore...

If you have seen the error 'file name must be set' when running the standard Cucumber tests of models extended with Paperclip, it means that probably you have (as it happened in my case) similar class structure:

class Document < ActiveRecord::Base
  has_many :attachments, :dependent => :destroy, :class_name => '::Attachment'
  accepts_nested_attributes_for :attachments, :allow_destroy => true
end

In my case Document has_many attachments and it's attachment that has paperclip file.

It means also that we can but not have to embed file uploads in the Document form. In my case I could submit the document from web browser without any troubles but Cucumber tests were failing.

It's because in the post request we had this parameters:

"attachments_attributes"=>{"0"=>{"file"=>""}}}

Which makes our webserver think that we are sending a file attachment, but because the value of 'file' is empty the validation fails.

The solution is easy: we have to reject the nested attributes when the file is empty. This can be done by modifying our class in the following way:

accepts_nested_attributes_for :attachments, :allow_destroy => true, :reject_if => lambda { |t| t['attachment_file'].nil?

In this case we just create the document object without trying to create the attachment.