CHRIS WANSTRATH
ERR FREE
[ http://errfree.com ]

50,000,000 pages
no downtime

memcached.

Memcaching Rails
CHRIS WANSTRATH
ERR FREE
[ http://errfree.com ]

Memcaching Rails
CHRIS WANSTRATH
ERR FREE
[ http://errfree.com ]

chris wanstrath
railsconf 2007
kickin’ ass
with cache-fu

{}

class Memcache < Hash
undef :each, :keys
end

class Memcache < DRbHash
undef :each, :keys
end

$ memcached -vv
<3 server listening
<7 new client connection
<7 get app-test:Story:1
>7 END
<7 set app-test:Story:2 0
>7 STORED
<7 delete app-test:Story:1
>7 DELETED

$ memcached -vv
<3 server listening
<7 new client connection
<7 get app-test:Story:1
>7 END
<7 set app-test:Story:2 0
>7 STORED
<7 delete app-test:Story:1
>7 DELETED

YAGNI

UYRDNI

UYRDNI
(unless you really do need it)

class Presentation < ActiveRecord::Base
def self.get_cache(id)
if data = @cache.get(id)
data
else
data = find(id)
@cache.set(id, data)
data
end
end
end

class Presentation < ActiveRecord::Base
def self.get_cache(id)
@cache.get(id) ||
@cache.set(id, find(id))
end
end

Fragments
Actions
Sessions
&
Objects

memcache-client

memcache-client
$ gem install memcache-client

topfunky memcached

CachedModel

Fragment Cache Store

Session Store

cache_fu

cache_fu
( acts_as_cached 2.0 )

Fragments
Actions
Sessions
&
Objects

acts_as_cached

config/memcached.yml
defaults:
ttl: 1800
namespace: railsconf
sessions: false
fragments: false
servers: localhost:11211

config/memcached.yml
defaults:
ttl: 1800
namespace: railsconf
sessions: true
fragments: true
servers: localhost:11211

config/memcached.yml
production:
benchmarking: false
sessions: true
fragments: true
servers:
- 192.185.254.121:11211
- 192.185.254.138:11211
- 192.185.254.160:11211

config/memcached.yml
production:
benchmarking: false
sessions: true
fragments: true
servers:
- 192.185.254.121:11211
- 192.185.254.138:11211
- 192.185.254.160:11211

class Presentation < ActiveRecord::Base
acts_as_cached
end

get_cache
expire_cache

class Presentation < ActiveRecord::Base
acts_as_cached
after_save :expire_cache
end

class Presentation < ActiveRecord::Base
def self.get_cache(id)
if data = @cache.get(id)
data
else
data = find(id)
@cache.set(id, data)
data
end
end
end

class Presentation < ActiveRecord::Base
def self.get_cache(id)
if not (data = @cache.get(id)).nil?
data
else
data = find(id)
@cache.set(id, data)
data
end
end
end

class Presentation < ActiveRecord::Base
def self.get_cache(id)
if not (data = @cache.get(id)).nil?
data
else
data = find(id) || false
@cache.set(id, data)
data
end
end
end

Presentation.get_cache(1337)

class Presentation < ActiveRecord::Base
acts_as_cached :conditions => 'published = 1'
end

class Presentation < ActiveRecord::Base
acts_as_cached :finder => :find_live
end

Topic.find :all,
:conditions =>
[\"created_at > ?\", 1.week.ago],
:order => 'post_count desc',
:limit => 5

class Topic < ActiveRecord::Base
def self.weekly_popular(limit = 5)
find :all,
:conditions =>
[\"created_at > ?\", 1.week.ago],
:order => 'post_count desc',
:limit => limit
end
end

Topic.weekly_popular

DB: 0.00 (0%)

class Topic < ActiveRecord::Base
def self.cached_weekly_popular
get_cache(:weekly_popular) do
weekly_popular
end
end
end

Topic.cached_weekly_popular

ruby mocha

bdd test spec

A Ruby object acting as cached
- should be able to retrieve a cached version of itself
- should be able to set itself to the cache
- should pass its cached self into a block when supplied
- should be able to expire its cache
- should be able to reset its cache
- should be able to tell if it is cached
- should be able to set itself to the cache with an arbitrary ttl
Finished in 0.028509 seconds.
28 specifications (53 requirements), 0 failures

context \"Calling #cached_weekly_popular\" do
specify \"should call #weekly_popular if not cached\" do
Topic.expects(:fetch_cache).returns(nil)
Topic.cached_weekly_popular.should.equal Topic.weekly_popular
end
specify \"should return if cached\" do
Topic.expects(:get_cache).returns(true)
Topic.expects(:weekly_popular).never
Topic.cached_weekly_popular
end
end

Topic.cached(:weekly_popular)

def self.cache_key_with_date(id)
date = Date.today.to_s.tr(' ', '_')
cache_key_without_date(id) + ':' + date
end
class << self
alias_method_chain :cache_key, :date
end

class Topic < ActiveRecord::Base
def self.date_for_key
Date.today.to_s.tr(' ', '_')
end
def self.cached_weekly_popular
key = 'weekly_popular' + date_for_key
get_cache(key) { weekly_popular }
end
end

Topic.find(1, 2, 3)

Topic.get_cache(1, 2, 3)

user_ids = @topic.posts.map(&:user_id).uniq
@users = User.get_cache(user_ids)

class ApplicationController
before_filter :local_cache_for_request
end

# pulls from memcache
@user = User.get_cache(1)
# pulls from local cache
@user = User.get_cache(1)

class ApplicationController
before_filter :set_cache_override
def set_cache_override
returning true do
ActsAsCached.skip_cache_gets =
!!params[:skip_cache]
end
end
end

www.mysite.com/home?skip_cache=1

reset_cache

@topic.set_cache

class Presentation < ActiveRecord::Base
acts_as_cached
after_save :reset_cache
end

class Presentation < ActiveRecord::Base
acts_as_cached :version => 1
end

monit

libketama

1
600 200
400

1
600 cache_get :railsconf 200
400

1
:railsconf == 100
600 200
400

1
:railsconf == 200
600 200
400

1
:railsconf == 200
600 200

1
700
:railsconf == 200
600 200
500 300
400

l33t h4x0rs
• Geoffrey Grosenbach
• Rob Sanheim
• Ryan King
• Lourens Naudé
• Michael Moen
• Corey Donohoe
• PJ Hyett
• Eric Hodel

{}
( thanks. any questions? )

http://flickr.com/photos/seibuone/144588686/
http://flickr.com/photos/j00zt1n/255430115/
http://flickr.com/photos/jameswong/145397570/
http://flickr.com/photos/xalpha/58368229/
http://flickr.com/photos/63503896@N00/35723413/
http://flickr.com/photos/mrcrash/145451993/
thanks
http://flickr.com/photos/psybernoid/398301743/
http://flickr.com/photos/45royale/422227291/
flickr
http://flickr.com/photos/andrson/420810541/
http://flickr.com/photos/joshuaweiland/370931770/
http://flickr.com/photos/zesmerelda/27258314/
http://flickr.com/photos/slice/390271923/
http://flickr.com/photos/cocoen/411960476/
http://flickr.com/photos/pinguino/198885132/
http://flickr.com/photos/davidfmiller/468476118/
http://laughingsquid.com - Scott Beale
http://flickr.com/photos/bail56/313536999/
http://flickr.com/photos/65995199@N00/272672183/