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Class: ActiveSupport::Cache::MemCacheStore

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, Store
Instance Chain:
self, Store
Inherits: ActiveSupport::Cache::Store
Defined in: activesupport/lib/active_support/cache/mem_cache_store.rb

Overview

A cache store implementation which stores data in Memcached: memcached.org/

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.

Constant Summary

Class Attribute Summary

Store - Inherited

.instrument

:deprecated:
.instrument=

:deprecated:
.logger

Class Method Summary

Store - Inherited

.new

Create a new cache.

Instance Attribute Summary

Store - Inherited

#logger, #options,
#silence?

Alias for Store#silence.

Instance Method Summary

Store - Inherited

#cleanup

Cleanup the cache by removing expired entries.
#clear

Clear the entire cache.
#decrement

Decrement an integer value in the cache.
#delete

Deletes an entry in the cache.
#delete_matched

Delete all entries with keys matching the pattern.
#exist?

Returns true if the cache contains an entry for the given key.
#fetch

Fetches data from the cache, using the given key.
#fetch_multi

Fetches data from the cache, using the given keys.
#increment

Increment an integer value in the cache.
#mute

Silence the logger within a block.
#read

Fetches data from the cache, using the given key.
#read_multi

Read multiple values at once from the cache.
#silence,
#silence!

Silence the logger.
#write

Writes the value to the cache, with the key.

Constructor Details

.new(*addresses) ⇒ MemCacheStore

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).

[ GitHub ] 

  


# File 'activesupport/lib/active_support/cache/mem_cache_store.rb', line 44



def initialize(*addresses)
  addresses = addresses.flatten
  options = addresses.extract_options!
  super(options)

  unless [String, Dalli::Client, NilClass].include?(addresses.first.class)
    raise ArgumentError, "First argument must be an empty array, an array of hosts or a Dalli::Client instance."
  end
  if addresses.first.is_a?(Dalli::Client)
    @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


  







Class Method Details



  

    .build_mem_cache(*addresses)  
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/mem_cache_store.rb', line 29



def self.build_mem_cache(*addresses)
  addresses = addresses.flatten
  options = addresses.extract_options!
  addresses = ["localhost:11211"] if addresses.empty?
  Dalli::Client.new(addresses, options)
end


  







Instance Method Details



  

    #clear(options = nil)  
  



  

    

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


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/mem_cache_store.rb', line 109



def clear(options = nil)
  @data.flush_all
rescue Dalli::DalliError => e
  logger.error("DalliError (#{e}): #{e.message}") if logger
  nil
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.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/mem_cache_store.rb', line 66



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)
  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.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/mem_cache_store.rb', line 117



def stats
  @data.stats
end