jrochkind

A Capistrano Rails Guide

by Jonathan Rochkind, http://bibwild.wordpress.com

why cap?

Capistrano automates pushing out a new version of your application to a deployment location.

I've been writing and deploying Rails apps for a while, but I avoided using Capistrano until recently. I've got a pretty simple one-host deployment, and even though everyone said Capistrano was great, every time I tried to get started I just got snowed under not being able to figure out exactly what I wanted to do, and figured I wasn't having that much trouble doing it "manually".

jrochkind

Rails has a handy truncate helper (which is actually mostly a method added to String ), but it warns you it's not safe to use on html source, it'll cut off end tags and such.

What if you want an HTML safe one? There are a variety of suggested solutions you can google, none of which were quite robust/powerful enough for me.

So I started with my favorite, by Andrea Singh, using nokogiri.

But:

• I modified it to not monkey-patch Nokogiri, but be a static method instead (sadly making already confusing code yet more confusing, but I didn't want to monkey patch nokogiri)

jrochkind

######################
#
#  Monkey patch to ActiveRecord to prevent 'implicit' checkouts. Currently tested with Rails 4.0.8, prob
#  should work fine in Rails 4.1 too. 
#
#  If you create a thread yourself, if it uses ActiveRecord objects without
#  explicitly checking out a connection, one will still be checked out implicitly.
#  If it is never checked back in with `ActiveRecord::Base.clear_active_connections!`,
#  then it will be leaked. 
#

jrochkind

module Slug
  def self.customize(field: :name)
    Module.new do
      define_method :to_param do
        public_send(field).downcase.gsub /\W+/, '-'
      end       
    end
  end
end

jrochkind

require 'date'

# Actually doesn't matter WHAT you choose as the epoch, it
# won't change the algorithm. Just don't change it after you
# have cached computed scores. Choose something before your first
# post to avoid annoying negative numbers. Choose something close
# to your first post to keep the numbers smaller. This is, I think,
# reddit's own epoch. 
$our_epoch = Time.local(2005, 12, 8, 7, 46, 43).to_time

jrochkind

# test_for  == N / 5    -- approximate array average case?

{:benchmark_iterations=>10000, :class=>Array, :test_for=>5, :num_rewrites=>1, :col_size=>10, :num_reads=>10}
  0.140000   0.000000   0.140000 (  0.141915)

{:benchmark_iterations=>10000, :class=>Set, :test_for=>5, :num_rewrites=>1, :col_size=>10, :num_reads=>10}
  0.190000   0.010000   0.200000 (  0.198503)
----

{:benchmark_iterations=>10000, :class=>Array, :test_for=>50, :num_rewrites=>1, :col_size=>100, :num_reads=>10}

jrochkind

AWS_SIG4_SIGNER = Aws::Sigv4::Signer.new(
  service: 's3',
  region: AWS_CLIENT.config.region,
  credentials_provider: SOME_AWS_CLIENT.config.credentials,
  unsigned_headers: Aws::S3::Presigner::BLACKLISTED_HEADERS,
  uri_escape_path: false
)

def naive_with_uri_escape_escaping(shrine_file)
  # because URI.escape does NOT escape `/`, we don't need to split it, 

jrochkind

original AWS SDK public_url implementation   0.053043   0.000275   0.053318 (  0.053782)
naive implementation                         0.004730   0.000016   0.004746 (  0.004760)

jrochkind

def naive_public_url(shrine_file)
  "https://#{["#{shrine_file.storage.bucket.name}.s3.amazonaws.com", *shrine_file.storage.prefix, shrine_file.id].join('/')}"
end

naive_public_url(model.image)
#=> "https://somebucket.s3.amazonaws.com/path/to/image.jpg"

jrochkind

def naive_public_url(shrine_file)
  "https://#{["#{shrine_file.storage.bucket.name}.s3.amazonaws.com", *shrine_file.storage.prefix, shrine_file.id].join('/')}"
end

naive_public_url(model.image)
#=> "https://somebucket.s3.amazonaws.com/path/to/image.jpg"