ActiveSupport::Cache::MemCacheStore

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.

Constants

ESCAPE_KEY_CHARS

Public Class Methods

build_mem_cache(*addresses) click to toggle source

    # File lib/active_support/cache/mem_cache_store.rb, line 34
34:       def self.build_mem_cache(*addresses)
35:         addresses = addresses.flatten
36:         options = addresses.extract_options!
37:         addresses = ["localhost:11211"] if addresses.empty?
38:         MemCache.new(addresses, options)
39:       end

new(*addresses) click to toggle source

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"))

    # File lib/active_support/cache/mem_cache_store.rb, line 54
54:       def initialize(*addresses)
55:         addresses = addresses.flatten
56:         options = addresses.extract_options!
57:         super(options)
58: 
59:         if addresses.first.respond_to?(:get)
60:           @data = addresses.first
61:         else
62:           mem_cache_options = options.dup
63:           UNIVERSAL_OPTIONS.each{|name| mem_cache_options.delete(name)}
64:           @data = self.class.build_mem_cache(*(addresses + [mem_cache_options]))
65:         end
66: 
67:         extend Strategy::LocalCache
68:         extend LocalCacheWithRaw
69:       end

Public Instance Methods

clear(options = nil) click to toggle source

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

     # File lib/active_support/cache/mem_cache_store.rb, line 116
116:       def clear(options = nil)
117:         @data.flush_all
118:       end

read_multi(*names) click to toggle source

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

    # File lib/active_support/cache/mem_cache_store.rb, line 73
73:       def read_multi(*names)
74:         options = names.extract_options!
75:         options = merged_options(options)
76:         keys_to_names = names.inject({}){|map, name| map[escape_key(namespaced_key(name, options))] = name; map}
77:         raw_values = @data.get_multi(keys_to_names.keys, :raw => true)
78:         values = {}
79:         raw_values.each do |key, value|
80:           entry = deserialize_entry(value)
81:           values[keys_to_names[key]] = entry.value unless entry.expired?
82:         end
83:         values
84:       end

stats() click to toggle source

Get the statistics from the memcached servers.

     # File lib/active_support/cache/mem_cache_store.rb, line 121
121:       def stats
122:         @data.stats
123:       end

Private Instance Methods

deserialize_entry(raw_value) click to toggle source

     # File lib/active_support/cache/mem_cache_store.rb, line 166
166:         def deserialize_entry(raw_value)
167:           if raw_value
168:             entry = Marshal.load(raw_value) rescue raw_value
169:             entry.is_a?(Entry) ? entry : Entry.new(entry)
170:           else
171:             nil
172:           end
173:         end

escape_key(key) click to toggle source

     # File lib/active_support/cache/mem_cache_store.rb, line 160
160:         def escape_key(key)
161:           key = key.to_s.gsub(ESCAPE_KEY_CHARS){|match| "%#{match.getbyte(0).to_s(16).upcase}"}
162:           key = "#{key[0, 213]}:md5:#{Digest::MD5.hexdigest(key)}" if key.size > 250
163:           key
164:         end

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ActiveSupport::Cache::MemCacheStore

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