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.

Methods

Constants

ESCAPE_KEY_CHARS = /[\x00-\x20%\x7F-\xFF]/n

Class Public 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 code 
# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 76
      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
      end
🔎 See on GitHub

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 code 
# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 121
      def clear(options = nil)
        rescue_error_with(nil) { @data.with { |c| c.flush_all } }
      end
🔎 See on GitHub

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

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.

📝 Source code 
# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 110
      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
🔎 See on GitHub

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

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.

📝 Source code 
# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 97
      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
🔎 See on GitHub

stats()

Get the statistics from the memcached servers.

📝 Source code 
# File activesupport/lib/active_support/cache/mem_cache_store.rb, line 126
      def stats
        @data.with { |c| c.stats }
      end
🔎 See on GitHub