#380 Memcached & Dalli pro

Sep 12, 2012 | 12 minutes | Performance, Plugins, Caching, Production

Memcached is an excellent cache store, and Dalli is the best way to interact with it through Ruby. Here I show various ways to use Memcached in a Rails app including how to set it up in production.

Click to Play Video ▶

Download:
source codeProject Files in Zip (60.7 KB)
mp4Full Size H.264 Video (29.7 MB)
m4vSmaller H.264 Video (15.4 MB)
webmFull Size VP8 Video (16.3 MB)
ogvFull Size Theora Video (37.4 MB)

Browse Source Code

Resources

          terminal
        
memcached -h | head -1
brew install memcached
/usr/local/bin/memcached
ssh deployer@198.58.98.181
sudo apt-get install memcached
vim /etc/memcached.conf

          Gemfile
        
gem 'dalli'

          config/environments/development.rb
        
config.action_controller.perform_caching = true
config.cache_store = :dalli_store

          config/environments/production.rb
        
config.cache_store = :dalli_store

          rails console
        
Rails.cache
Rails.cache.write(:foo, 1)
Rails.cache.read(:foo)
Rails.cache.fetch(:bar) { sleep 1; 2 }
Rails.cache.multi_read(:foo, :bar)
Rails.cache.stats
y _
Rails.cache.write(:foo, 1, expires_in: 5.seconds)

          models/product.rb
        
def category_name
  Rails.cache.fetch([:category, category_id, :name], expires_in: 5.minutes) do
    category.name
  end
end

          models/category.rb
        
after_update :flush_name_cache

def flush_name_cache
  Rails.cache.delete([:category, id, :name]) if name_changed?
end

          config/recipes/memcached.rb
        
set_default :memcached_memory_limit, 64

namespace :memcached do
  desc "Install Memcached"
  task :install, roles: :app do
    run "#{sudo} apt-get install memcached"
  end
  after "deploy:install", "memcached:install"

  desc "Setup Memcached"
  task :setup, roles: :app do
    template "memcached.erb", "/tmp/memcached.conf"
    run "#{sudo} mv /tmp/memcached.conf /etc/memcached.conf"
    restart
  end
  after "deploy:setup", "memcached:setup"

  %w[start stop restart].each do |command|
    desc "#{command} Memcached"
    task command, roles: :app do
      run "service memcached #{command}"
    end
  end
end

          config/recipes/templates/memcached.erb
        
# run as a daemon
-d

logfile /var/log/memcached.log

# memory limit
-m <%= memcached_memory_limit %>

# port
-p 11211 

# user
-u memcache

# listen only on localhost (for security)
-l 127.0.0.1