A cache store implementation which stores data in Memcached: www.danga.com/memcached/

This is currently the most popular cache store for production websites.

Special features:

  • Clustering and load balancing. One can specify multiple memcached servers, and MemCacheStore will load balance between all available servers. If a server goes down, then MemCacheStore will ignore it until it comes back up.

MemCacheStore implements the Strategy::LocalCache strategy which implements an in memory cache inside of a block.

Methods
B
C
N
R
S
Constants
ESCAPE_KEY_CHARS = /[\x00-\x20%\x7F-\xFF]/n
 
Class Public methods
build_mem_cache(*addresses)

Source: show 

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 36
def self.build_mem_cache(*addresses)
  addresses = addresses.flatten
  options = addresses.extract_options!
  addresses = ["localhost:11211"] if addresses.empty?
  MemCache.new(addresses, options)
end
new(*addresses)

Creates a new MemCacheStore object, with the given memcached server addresses. Each address is either a host name, or a host-with-port string in the form of “host_name:port”. For example:

ActiveSupport::Cache::MemCacheStore.new("localhost", "server-downstairs.localnetwork:8229")

If no addresses are specified, then MemCacheStore will connect to localhost port 11211 (the default memcached port).

Instead of addresses one can pass in a MemCache-like object. For example:

require 'memcached' # gem install memcached; uses C bindings to libmemcached
ActiveSupport::Cache::MemCacheStore.new(Memcached::Rails.new("localhost:11211"))

Source: show 

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 56
def initialize(*addresses)
  addresses = addresses.flatten
  options = addresses.extract_options!
  super(options)

  if addresses.first.respond_to?(:get)
    @data = addresses.first
  else
    mem_cache_options = options.dup
    UNIVERSAL_OPTIONS.each{|name| mem_cache_options.delete(name)}
    @data = self.class.build_mem_cache(*(addresses + [mem_cache_options]))
  end

  extend Strategy::LocalCache
  extend LocalCacheWithRaw
end
Instance Public methods
clear(options = nil)

Clear the entire cache on all memcached servers. This method should be used with care when shared cache is being used.

Source: show 

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 118
def clear(options = nil)
  @data.flush_all
end
read_multi(*names)

Reads multiple values from the cache using a single call to the servers for all keys. Options can be passed in the last argument.

Source: show 

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 75
def read_multi(*names)
  options = names.extract_options!
  options = merged_options(options)
  keys_to_names = Hash[names.map{|name| [escape_key(namespaced_key(name, options)), name]}]
  raw_values = @data.get_multi(keys_to_names.keys, :raw => true)
  values = {}
  raw_values.each do |key, value|
    entry = deserialize_entry(value)
    values[keys_to_names[key]] = entry.value unless entry.expired?
  end
  values
end
stats()

Get the statistics from the memcached servers.

Source: show 

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 123
def stats
  @data.stats
end