class Ramaze::Cache::MemCache

Cache driver for the Memcache storage engine. Memcache is a key/value store that's extremely useful for caching data such as views or API responses. More inforamtion about Memcache can be found on it's website: <memcached.org/>.

Note that this cache driver requires the Dalli gem rather than Memcache Client. The reason for this is that the Memcache client hasn't been updated in over a year and Memcache has changed quite a bit. Dalli is also supposed to be faster and better coded. This cache driver will also try to load the kgio Gem if it's installed, if it's not it will just continue to operate but you won't get the nice speed boost.

This driver works similar to Ramaze::Cache::Sequel in that it allows you to specify instance specific options uisng the using() method:

Ramaze::Cache.options.session = Ramaze::Cache::MemCache.using(
  :compression => false
)

All options sent to the using() method will be sent to Dalli.

@example Using the default options

Ramaze::Cache.options.view = Ramaze::Cache::MemCache
Ramaze.setup_dependencies

Ramaze::Cache.view.store(:my_view, 'Hello Ramaze')

@example Using custom options

Ramaze::Cache.options.view = Ramaze::Cache::MemCache.using(
  :compression => false,
  :servers     => ['localhost:11211', 'localhost:112112']
)

Ramaze.setup_dependencies
Ramaze::Cache.view.store(:my_view, 'Hello Ramaze')

@author Yorick Peterse @since 04-05-2011

Constants

MAX_TTL

The maximum Time To Live that can be used in Memcache

Attributes

options[RW]
options[RW]

Hash containing all the default options merged with the user specified ones

Public Class Methods

new(options = {}) click to toggle source

Creates a new instance of the cache class.

@author Michael Fellinger @since 04-05-2011 @param [Hash] options A hash with custom options, see

Ramaze::Cache::MemCache.using for all available options.
# File lib/ramaze/cache/memcache.rb, line 116
def initialize(options = {})
  self.class.options ||= Ramaze::Cache::MemCache.trait[:default].merge(
    options
  )

  @options = options.merge(self.class.options)
end
using(options = {}) click to toggle source

This method will create a subclass of Ramaze::Cache::MemCache with all the custom options set. All options set in this method will be sent to Dalli as well.

Using this method allows you to use different memcache settings for various parts of Ramaze. For example, you might want to use servers A and B for storing the sessions but server C for only views. Most of the way this method works was inspired by Ramaze::Cache::Sequel which was contributed by Lars Olsson.

@example

Ramaze::Cache.options.session = Ramaze::Cache::MemCache.using(
  :compression => false,
  :username    => 'ramaze',
  :password    => 'ramaze123',
  :servers     => ['othermachine.com:12345']
)

@author Yorick Peterse @since 04-05-2011 @param [Hash] options A hash containing all configuration options to

use for Dalli. For more information on all the available options you
can read the README in their repository. This repository can be found
here: https://github.com/mperham/dalli
# File lib/ramaze/cache/memcache.rb, line 102
def using(options = {})
  merged = Ramaze::Cache::MemCache.trait[:default].merge(options)
  Class.new(self) { @options = merged }
end

Public Instance Methods

cache_clear() click to toggle source

Removes all items from the cache.

@author Yorick Peterse @since 04-05-2011

# File lib/ramaze/cache/memcache.rb, line 155
def cache_clear
  @client.flush
end
cache_delete(*keys) click to toggle source

Removes the specified keys from the cache.

@author Yorick Peterse @since 04-05-2011 @param [Array] keys The keys to remove from the cache.

# File lib/ramaze/cache/memcache.rb, line 166
def cache_delete(*keys)
  keys.each do |key|
    @client.delete(key)
  end
end
cache_fetch(key, default = nil) click to toggle source

Fetches the specified key from the cache. It the value was nil the default value will be returned instead.

@author Yorick Peterse @since 04-05-2011 @param [String] key The name of the key to retrieve. @param [Mixed] default The default value. @return [Mixed]

# File lib/ramaze/cache/memcache.rb, line 182
def cache_fetch(key, default = nil)
  value = @client.get(key)

  if value.nil?
    return default
  else
    return value
  end
end
cache_setup(hostname, username, appname, cachename) click to toggle source

Prepares the cache by creating the namespace and an instance of a Dalli client.

@author Yorick Peterse @since 04-05-2011 @param [String] hostname The hostname of the machine running the

application.

@param [String] username The name of the user executing the process @param [String] appname Unique identifier for the application. @param [String] cachename The namespace to use for this cache instance.

# File lib/ramaze/cache/memcache.rb, line 136
def cache_setup(hostname, username, appname, cachename)
  # Validate the maximum TTL
  if options[:expires_in] > MAX_TTL
    raise(ArgumentError, "The maximum TTL of Memcache is 30 days")
  end

  options[:namespace] = [
    hostname, username, appname, cachename
  ].compact.join('-')

  @client = ::Dalli::Client.new(options[:servers], options)
end
cache_store(key, value, ttl = nil, options = {}) click to toggle source

Sets the given key to the specified value. Optionally you can specify a hash with options specific to the key. Once a key has been stored it's value will be returned.

@author Yorick Peterse @since 04-05-2011 @param [String] key The name of the key to store. @param [Mixed] value The value to store in Memcache. @param [Fixnum] ttl The Time To Live to use for the current key. @param [Hash] options A hash containing options specific for the

specified key.

@return [Mixed]

# File lib/ramaze/cache/memcache.rb, line 206
def cache_store(key, value, ttl = nil, options = {})
  ttl = options.delete(:ttl) || @options[:expires_in]

  if ttl > MAX_TTL
    raise(ArgumentError, "The maximum TTL of Memcache is 30 days")
  end

  @client.set(key, value, ttl, options)

  return value
end