Dude, what function am I in?

The ctags plugin for vim shows the function name containing the current line. This is helpful when you're refactoring down functions that are longer than a screenful.

I've been using this (exuberant) ctags based approach for years. It's quite handy and works across more languages than I use: 41 languages from ant to YACC. I've tested with perl, python, C, java and ruby.

The plugin has options to display the function name in the status bar or in the xterm menu bar. It takes care of generating the ctags files on the fly.

I've blogged before on using vim with tags file, recommending using ctags to create a tags file for your codebase. Using the tags browser to jump to subroutines defined in other files is just ... super fun.

ctags plugin for vim:

http://www.vim.org/scripts/script.php?script_id=610

exuberant ctags:

http://ctags.sf.net/

My blogpost on effective VIM with perl and tags. http://www.lowlevelmanager.com/2010/12/perl-tags-and-vim-effective-code.html

These are the options I use with the plugin:

  let g:ctags_statusline=1
  let g:ctags_title=0
  let g:generate_tags=1 
  let g:ctags_regenerate=1

PS. OSX comes with a different version of ctags, you'll need to install exuberant ctags for the ctag plugin to work, it's available in both fink and MacPorts.

More LWP SSL 500 issues! Now with HTTP::DAV crossover

LWP::UserAgent is returning a 500 level error in the case of a self-signed site key. This is similar to my previous post on this topic, ( Fixed 500 can't verify SSL peers ):

For https://... default to verified connections with require IO::Socket::SSL and Mozilla::CA modules to be installed. Old behaviour can be requested by setting the PERL_LWP_SSL_VERIFY_HOSTNAME environment variable to 0. The LWP::UserAgent got new ssl_opts method to control this as well.

I use HTTP::DAV to push changes to the Los Angeles Perl Mongers website. When I tried to push updates for tonight's meeting, HTTP::DAV threw an error " The URL "https://groups.pm.org/groups/losangeles/" is not DAV enabled or not accessible.".

This seemed familiar -- in fact I filed a bug against HTTP::DAV ( Bug 59674 ) to pass through SSL errors from LWP when SSL libraries were not installed. ( Cosimo, I am sorry that I didn't respond in a timely manner when the fixes were proposed. Thanks for fixing it!). The fix for 59674 included having a specific message for various classes of errors out of LWP::UserAgent.

## Error conditions
my %err = (
    'ERR_WRONG_ARGS'    => 'Wrong number of arguments supplied.',
    'ERR_UNAUTHORIZED'  => 'Unauthorized. ',
    'ERR_NULL_RESOURCE' => 'Not connected. Do an open first. ',
    'ERR_RESP_FAIL'     => 'Server response: ',
    'ERR_501'           => 'Server response: ',
    'ERR_405'           => 'Server response: ',
    'ERR_GENERIC'       => '',
);

LWP::UserAgent is returning a 500 level error in the case of a self-signed site key. Not 501 as in the prior case.

Example:

#!/usr/bin/perl
use strict;
use warnings;
use LWP::UserAgent;
use Data::Dumper;
my $url = "https://groups.pm.org/groups/losangeles";
my $ua=LWP::UserAgent->new();
my $resp = $ua->get( $url );
print Dumper $resp;

Output Snippet:
LWP::Protocol::https::Socket: SSL connect attempt failed with unknown errorerror:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed at /Library/Perl/5.10.0/LWP/Protocol/http.pm line 51.

One can get around this by setting an environment variable export PERL_LWP_SSL_VERIFY_HOSTNAME=0, or by using the ssl_opts option to UserAgent. A third, preferred solution would be import the key and mark it as "OK" on the client side.

I pushed my website changes by using the PERL_LWP_SSL_VERIFY_HOSTNAME=0 workaround. Now let's see if I can figure out workarounds 3 and 2.

FIXED: 500 Can't verify SSL peers without knowning which Certificate Authorities to trust

Having problems using LWP::UserAgent with SSL hosts? Try installing Mozilla::CA.

500 Can't verify SSL peers without knowning which Certificate Authorities to trust

Props to Corion for posting this tip to perlmonks.

2011-03-08 Release 6.00

Unbundled all modules not in the LWP:: namespace from the libwww-perl distribution. The new broken out CPAN distribtions are File-Listing, HTML-Form, HTTP-Cookies, HTTP-Daemon, HTTP-Date, HTTP-Message, HTTP-Negotiate, Net-HTTP, and WWW-RobotRules. libwww-perl-6 require these to be installed.

This release also drops the unmaintained lwp-rget script from the distribution.

Perl v5.8.8 or better is now required. For older versions of perl please stay with libwww-perl-5.837.

For https://... default to verified connections with require IO::Socket::SSL and Mozilla::CA modules to be installed. Old behaviour can be requested by setting the PERL_LWP_SSL_VERIFY_HOSTNAME environment variable to 0. The LWP::UserAgent got new ssl_opts method to control this as well.

Support internationalized URLs from command line scripts and in the proxy environment variables.

The lwp-dump script got new --request option.

The lwp-request script got new -E option, contributed by Tony Finch.

Protocol handlers and callbacks can raise HTTP::Response objects as exceptions. This will abort the current request and make LWP return the raised response.

-- LWP 6.00 release notes 2011/03/08(emphasis mine).

CPANTS: down?

I tried to pull up a report on CPANTS (cpants.perl.org) today (The CPAN Testing Service) and was greeted by the sad message quoted below.

Is this because CPANTS.perl.org wasn't getting used in favor of www.cpantesters.org? I was afraid we'd lost the awesome CPAN testing infrastructure. According to the CPAN::Testers documentation, CPANTS was a project to track "Kwalitee" & metadata of modules on the CPAN. So what does that mean?

CPANTS - The CPAN Testing Service
CPANTS is currently down due to terminal bitrot.
If you're interested in having it back, please contact domm AT cpan.org

CPANTS and Site maintained by Thomas Klausner - domm AT cpan.org

Hosting and bandwidth provided by Vienna.pm.
-- cpants.perl.org

Moving at Scale : Etsy

I know the etsy engineers like to graph, graph, graph, but I hadn't heard too much about the rest of their release cycle. They have taken specific steps to attempt to "Stay a Startup as we grow larger." Watch as they expound on the benefits of "one button deployment", empowering releases, branching-in-code, A-B testing and configurable features.

Warning, the video is a couple of hours long.

Watch live streaming video from etsy at livestream.com

Source

1. Make deployments easier
2. No-fault post-mortems
3. everyone works on head, no branches in source control, lots of if(0){ ... } blocks
4. configuration file that determines which features are live, to which percentage of the population.
5. public logging and metrics
6. ...
7. Change are quick, easy and encouraged.
8. maintains the "can do" "default is yes" attitude of the early startup.
9. mean time to notice problems: <5 minutes, mean time to fix problems: 4.5 minutes.
10. ...
11. profit

They have released two projects as openSource, available on github:

logster

https://github.com/etsy/logster

Forked from ganglia-logtailer, they removed the daemon mode to simplify the code.

Logster is a utility for reading log files and generating metrics in Graphite or Ganglia. It is ideal for visualizing trends of events that are occurring in your application/system/error logs. For example, you might use logster to graph the number of occurrences of HTTP response code that appears in your web server logs.

statsd

Github: https://github.com/etsy/statsd

Blogpost: measure anything measure everything/

A network daemon for aggregating statistics (counters and timers), rolling them up, then sending them to graphite.

They make heavy use of Graphite for displaying graphs. http://graphite.wikidot.com/

Better programming reading list

How to become a better programmer in 90 days -- a lightning talk.
http://www.foraker.com/how-to-become-a-better-programmer-in-90-days/

I stumbled upon this lighting talk by Neal Enssle. In it he recommends three books to improve our craft. I admit to not having read any of them, but I have heard of some of the authors.

The Passionate Programmer, Chad Fowler

Love what you do, your attitude comes through. Highlight a daily win.

Clean Code, Robert C. Martin

A language for describing our code.

Refactoring, Martin Fowler

60 refactoring patterns.