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.
# 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
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
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
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
# 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
# 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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