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class ActiveSupport::Cache::MemCacheStore

Parent:: ActiveSupport::Cache::Store

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.

Constants

ESCAPE_KEY_CHARS

Public Class Methods

new(*addresses) Show source

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 109
def initialize(*addresses)
  addresses = addresses.flatten
  options = addresses.extract_options!
  if options.key?(:cache_nils)
    options[:skip_nil] = !options.delete(:cache_nils)
  end
  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
    # The value "compress: false" prevents duplicate compression within Dalli.
    mem_cache_options[:compress] = false
    (UNIVERSAL_OPTIONS - %i(compress)).each { |name| mem_cache_options.delete(name) }
    @data = self.class.build_mem_cache(*(addresses + [mem_cache_options]))
  end
end

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 provided, but ENV is defined, it will be used instead. Otherwise, MemCacheStore will connect to localhost:11211 (the default memcached port).

Calls superclass method ActiveSupport::Cache::Store::new

supports_cache_versioning?() Show source

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 30
def self.supports_cache_versioning?
  true
end

Advertise cache versioning support.

Public Instance Methods

clear(options = nil) Show source

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 159
def clear(options = nil)
  rescue_error_with(nil) { @data.with { |c| c.flush_all } }
end

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

decrement(name, amount = 1, options = nil) Show source

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 148
def decrement(name, amount = 1, options = nil)
  options = merged_options(options)
  instrument(:decrement, name, amount: amount) do
    rescue_error_with nil do
      @data.with { |c| c.decr(normalize_key(name, options), amount, options[:expires_in]) }
    end
  end
end

Decrement a cached value. This method uses the memcached decr atomic operator and can only be used on values written with the :raw option. Calling it on a value not stored with :raw will initialize that value to zero.

increment(name, amount = 1, options = nil) Show source

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 135
def increment(name, amount = 1, options = nil)
  options = merged_options(options)
  instrument(:increment, name, amount: amount) do
    rescue_error_with nil do
      @data.with { |c| c.incr(normalize_key(name, options), amount, options[:expires_in]) }
    end
  end
end

Increment a cached value. This method uses the memcached incr atomic operator and can only be used on values written with the :raw option. Calling it on a value not stored with :raw will initialize that value to zero.

stats() Show source

# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 164
def stats
  @data.with { |c| c.stats }
end

Get the statistics from the memcached servers.