kgrz

require 'benchmark'
result = []
Benchmark.bm(7) do |reports|
  reports.report do
    (2..500).each do |x|
      (2..500).each do |y|
        next unless x > y
        a = [x*x-y*y, 2*x*y, x*x+y*y]
        next unless (a[0] + a[1] + a[2] === 1000)
        next unless (a[0]*a[0]+a[1]*a[1] === a[2]*a[2])

kgrz

# This is a modification of the blogpost on how to use Mongoid and Sinatra.
# Here is the original blogpost http://www.garrensmith.com/2010/09/11/Mongoid-sinatra.html
# The modification lets you use Mongoid 3.0 with the new Moped driver

# The new Moped driver uses the Sessions component to define the MongoDB connection rather
# than the Mongo::Connection.new that is used in the case of the default Ruby driver.
# Moped::Session.new vs Mongo::Connection.new

# Mongoid.load!(yaml_config.yml) is used to build the config hash. Alternatively, the hash can
# be built manually by using Mongoid.config {|config| ...} syntax. The config.sessions hash 

kgrz

class Email
  include Mongoid::Document
  field :emailid, type: String
  embeds_many :account
end

class Account
  include Mongoid::Document
  field :number, type: Integer
  field :openedon, type: DateTime

kgrz

TL;DR 
Putting it all together: Make sure you are using the Ruby version that you need to export from

$ gem list > ~/gemlist && rbenv local rbx-1.2.4 && \
gem install `awk -F' ' '{print $1}' ~/gemlist` && rm ~/gemlist


How I got there:
By exporting to a file:

kgrz

# Enumerable module provides most of the list traversal classes, some of which are mixed-in to File class.
# #each_line, #each_slice etc are such methods. 

# What if you need to split against a custom symbol. This is particularly useful while processing reports or logs.
# For instance, one of the reports I get is see is of this format:

# \e!C\r
# <some header data>
# -----------------------------------------------------------------------
# Name           Account        Address               DoB

kgrz

require 'faraday'
require 'net/http'
require 'pp'

# Repos: 
# https://github.com/technoweenie/faraday
# https://github.com/pengwynn/faraday_middleware

# Blog posts: 
# http://adventuresincoding.com/2010/09/writing-modular-http-client-code-with-faraday

kgrz

# this simple plumbing makes sure that the return data is in the form of a hash.

require 'faraday'

class Main
  attr_reader :conn
  def initialize
    @conn = Faraday.new "http://127.0.0.1:5984/somedb" do |faraday|
      faraday.adapter :em_http
      faraday.builder.insert(0, JSONMiddleware)

kgrz

If the error has "emfile" in the reason, it most probably has to do with the ulimit.

If the error is a TCP driver error saying that max file descriptors can be only a certain value, it has to do with the compilation of Erlang. This link: http://boorad.github.com/2009/07/09/mac-kpoll.html has info.
Setting the FD_SETSIZE to 8192 worked and limited the TCP driver connections to 8192.
Setting it to 81920 makes CouchDB fail to start.

^
| That worked. The reason why couch didnt start up was the setting of mochiweb acceptor pool to an atrocious 81000! 

things to look out for:

kgrz

# Soundcloud, after authorization, redirects to a pre-registered URL
# with the user's  code, access_token embedded in the URL which may 
# be an issue! 

# Alternatively, modify the #authorize_url() method such that the url
# that gets generated has a parameter "response_type" of "code" instead
# of "code_and_token" which is the default. 

require 'sinatra'
require 'soundcloud'

kgrz

# ~/.rake is your global rake directory. Rake knows the tasks you write there.
# Create a rake file, say, sinatra.rake

desc "Create a directory structure for Sinatra classic app"
task :create_sinatra do
  sh "mkdir public"
  sh "touch app.rb"
  sh "mkdir public/js"
  sh "mkdir public/css"
  sh "mkdir public/images"