cacheable

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= cacheable

Like ActiveSupport::Memoizable, but for caching. Uses Evan Weaver's memcached gem (i.e. libmemcached) for speed.

== Requirements

The memcached gem.

== Real-world use

In production use at http://brighterplanet.com since November 2009.

== Quickstart

In config/environment.rb...

config.gem 'memcached', :source => 'http://gemcutter.org' config.gem 'cacheable', :source => 'http://gemcutter.org'

And then in config/initializers/cacheable.rb...

servers = [ 'localhost:11211' ] options = { :support_cas => true, :binary_protocol => true, # Use the binary protocol to reduce query processing overhead. Defaults to false. :connect_timeout => 5, # How long to wait for a connection to a server. Defaults to 2 seconds. Set to 0 if you want to wait forever. :timeout => 0.25, # How long to wait for a response from the server. Defaults to 0.25 seconds. Set to 0 if you want to wait forever. :server_failure_limit => 25 # How many consecutive failures to allow before marking a host as dead. Has no effect unless :retry_timeout is also set. Defaults to 2 } Cacheable.repository = Memcached.new servers, options

Then in a model:

class ProjectFundDeposit < ActiveRecord::Base # do this just once and it will work for both instance and class methods extend Cacheable

# an instance method
def foo
  # etc.
end
cacheify :foo

# a instance method that takes arguments (works just the same)
def bar(args)
  # etc.
end
cacheify :bar

class << self
  # a class method
  def baz
    # etc.
  end
  cacheify :baz
end

after_save :clear_cache
after_destroy :clear_cache
def clear_cache
  uncacheify :foo
  uncacheify :bar, "a really good argument"
  self.class.uncacheify_all
  true
end

end

== Expiry

You can also specify an expiry in seconds (default is 60):

cacheify :foo, :ttl => 3600

== Combining cacheing and memoization (careful!)

class ProjectFundDeposit < ActiveRecord::Base # just once extend Cacheable # once for instance methods extend ActiveSupport::Memoizable

def foo
  # etc.
end
cacheify :foo
memoize :foo

class << self
  # once for class methods
  extend ActiveSupport::Memoizable

  def baz
    # etc.
  end
  cacheify :baz
  memoize :baz
end

end

Note that since there can be many ActiveRecord objects instantiated to represent the same row in the database, memoization doesn't always work like you want.

== Acknowledgements

• ActiveSupport::Memoizable
• {Yehuda Katz's post about "Better Ruby Idioms"}[http://yehudakatz.com/2009/11/12/better-ruby-idioms/]
• {brighterplanet.com}[http://brighterplanet.com]

== Wishlist

• split up the repository and the registry into their own modules

== Copyright

Copyright (c) 2009 Seamus Abshere. See LICENSE for details.