Class ActiveSupport::Cache::MemCacheStore
In: vendor/rails/activesupport/lib/active_support/cache/mem_cache_store.rb
Parent: Store

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 goes back online.
  • Time-based expiry support. See write and the +:expires_in+ option.

Methods

clear   new   stats   write  

Attributes

addresses  [R] 

Public Class methods

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).

[Source]

    # File vendor/rails/activesupport/lib/active_support/cache/mem_cache_store.rb, line 35
35:       def initialize(*addresses)
36:         addresses = addresses.flatten
37:         options = addresses.extract_options!
38:         addresses = ["localhost"] if addresses.empty?
39:         @addresses = addresses
40:         @data = MemCache.new(addresses, options)
41:       end

Public Instance methods

clear()

[Source]

     # File vendor/rails/activesupport/lib/active_support/cache/mem_cache_store.rb, line 109
109:       def clear
110:         @data.flush_all
111:       end
stats()

[Source]

     # File vendor/rails/activesupport/lib/active_support/cache/mem_cache_store.rb, line 113
113:       def stats
114:         @data.stats
115:       end
write(key, value, options = nil)

Writes a value to the cache.

Possible options:

  • +:unless_exist+ - set to true if you don‘t want to update the cache if the key is already set.
  • +:expires_in+ - the number of seconds that this value may stay in the cache. See ActiveSupport::Cache::Store#write for an example.

[Source]

    # File vendor/rails/activesupport/lib/active_support/cache/mem_cache_store.rb, line 58
58:       def write(key, value, options = nil)
59:         super
60:         method = options && options[:unless_exist] ? :add : :set
61:         # memcache-client will break the connection if you send it an integer
62:         # in raw mode, so we convert it to a string to be sure it continues working.
63:         value = value.to_s if raw?(options)
64:         response = @data.send(method, key, value, expires_in(options), raw?(options))
65:         response == Response::STORED
66:       rescue MemCache::MemCacheError => e
67:         logger.error("MemCacheError (#{e}): #{e.message}")
68:         false
69:       end

[Validate]