Kashyap kgrz

Make /robots.txt aware of the Rails environment

You probably don't want Google crawling your development staging app. Here's how to fix that.

$ mv public/robots.txt config/robots.production.txt
$ cp config/robots.production.txt config/robots.development.txt

Now edit config/routes.rb to add a route for /robots.txt, and add the controller code.

Mac OSX Spotlight Enhancement

Add this to Info.plist in /System/Library/Spotlight/RichText.mdimporter/Contents/ and Spotlight will search for source code files.

<string>public.c-header</string>
<string>public.c-plus-plus-header</string>
<string>public.c-source</string>
<string>public.objective-c-source</string>
public.c-plus-plus-source

This is a proof-of-concept of a couple of concurrent data structures written in Ruby.

The implementations are heavily commented for those interested. There are benchmarks (with results) included below. The results are interesting, but, as always, take with a grain of salt.

Data structures

AtomicLinkedQueue is a lock-free queue, built on atomic CAS operations.

Virtualenv's `bin/activate` is Doing It Wrong

I'm a Python programmer and frequently work with the excellent [virtualenv][] tool by Ian Bicking.

Virtualenv is a great tool on the whole but there is one glaring problem: the activate script that virtualenv provides as a convenience to enable its functionality requires you to source it with your shell to invoke it. The activate script sets some environment variables in your current environment and defines for you a deactivate shell function which will (attempt to) help you to undo those changes later.

This pattern is abhorrently wrong and un-unix-y. activate should instead do what ssh-agent does, and launch a sub-shell or sub-command with a modified environment.

Problems

Changes:

this version includes backport of Greg Price's patch for speedup startup http://bugs.ruby-lang.org/issues/7158 .

ruby-core prefers his way to do thing, so that I abandon cached-lp and sorted-lf patches of mine.
this version integrates 'array as queue' patch, which improves performance when push/shift pattern is heavily used on Array.

This patch is accepted into trunk for Ruby 2.0 and last possible bug is found by Yui Naruse. It is used in production* for a couple of months without issues even with this bug.

	$stack, $draws = [], {}

	def method_missing *args
	return if args[0][/^to_/]
	$stack << args.map { \|a\| a or $stack.pop }
	$draws[$stack.pop(2)[0][0]] = args[1] if args[0] == :<
	end

	class Array
	def +@

	# you can make a text file of request times (in ms, one number per line) and import it here, or you can use a probability distribution to simulate request times (see below where setting req_durations_in_ms)
	# rq = read.table("~/Downloads/request_times.txt", header=FALSE)$V1

	# argument notes:
	# parallel_router_count is only relevant if router_mode is set to "intelligent"
	# choice_of_two, power_of_two, and unicorn_workers_per_dyno are only relevant if router_mode is set to "naive"
	# you can only select one of choice_of_two, power_of_two, and unicorn_workers_per_dyno

	run_simulation = function(router_mode = "naive",
	reqs_per_minute = 9000,

	=Navigating=
	visit('/projects')
	visit(post_comments_path(post))

	=Clicking links and buttons=
	click_link('id-of-link')
	click_link('Link Text')
	click_button('Save')
	click('Link Text') # Click either a link or a button
	click('Button Value')

	#include <stdio.h>
	int main(){
	fprintf(stderr, "%s\n", "Study of int arrays");
	fprintf(stderr, "%s\n", "===================");
	int a[] = {1, 2, 3, 4, 5};
	// Arrays are contiguous memory locations.

	// The variable holding the array actually points to
	// the first item in the array :
	fprintf(stderr, "%p == %p\n", a, &a[0]);