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# frozen_string_literal: true
begin
require "dalli"
rescue LoadError => e
$stderr.puts "You don't have dalli installed in your application. Please add it to your Gemfile and run bundle install"
raise e
end
require "active_support/core_ext/marshal"
require "active_support/core_ext/array/extract_options"
module ActiveSupport
module Cache
# A cache store implementation which stores data in Memcached:
# https://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.
class MemCacheStore < Store
# Provide support for raw values in the local cache strategy.
module LocalCacheWithRaw # :nodoc:
private
def read_entry(key, options)
entry = super
if options[:raw] && local_cache && entry
entry = deserialize_entry(entry.value)
end
entry
end
def write_entry(key, entry, options)
if options[:raw] && local_cache
raw_entry = Entry.new(entry.value.to_s)
raw_entry.expires_at = entry.expires_at
super(key, raw_entry, options)
else
super
end
end
end
prepend Strategy::LocalCache
prepend LocalCacheWithRaw
ESCAPE_KEY_CHARS = /[\x00-\x20%\x7F-\xFF]/n
# Creates a new Dalli::Client instance with specified addresses and options.
# By default address is equal localhost:11211.
#
# ActiveSupport::Cache::MemCacheStore.build_mem_cache
# # => #<Dalli::Client:0x007f98a47d2028 @servers=["localhost:11211"], @options={}, @ring=nil>
# ActiveSupport::Cache::MemCacheStore.build_mem_cache('localhost:10290')
# # => #<Dalli::Client:0x007f98a47b3a60 @servers=["localhost:10290"], @options={}, @ring=nil>
def self.build_mem_cache(*addresses) # :nodoc:
addresses = addresses.flatten
options = addresses.extract_options!
addresses = ["localhost:11211"] if addresses.empty?
pool_options = retrieve_pool_options(options)
if pool_options.empty?
Dalli::Client.new(addresses, options)
else
ensure_connection_pool_added!
ConnectionPool.new(pool_options) { Dalli::Client.new(addresses, options.merge(threadsafe: false)) }
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 specified, then MemCacheStore will connect to
# localhost port 11211 (the default memcached port).
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
# 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.
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
# 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.
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
# Clear the entire cache on all memcached servers. This method should
# be used with care when shared cache is being used.
def clear(options = nil)
rescue_error_with(nil) { @data.with { |c| c.flush_all } }
end
# Get the statistics from the memcached servers.
def stats
@data.with { |c| c.stats }
end
private
# Read an entry from the cache.
def read_entry(key, options)
rescue_error_with(nil) { deserialize_entry(@data.with { |c| c.get(key, options) }) }
end
# Write an entry to the cache.
def write_entry(key, entry, options)
method = options && options[:unless_exist] ? :add : :set
value = options[:raw] ? entry.value.to_s : entry
expires_in = options[:expires_in].to_i
if expires_in > 0 && !options[:raw]
# Set the memcache expire a few minutes in the future to support race condition ttls on read
expires_in += 5.minutes
end
rescue_error_with false do
@data.with { |c| c.send(method, key, value, expires_in, options) }
end
end
# Reads multiple entries from the cache implementation.
def read_multi_entries(names, options)
keys_to_names = Hash[names.map { |name| [normalize_key(name, options), name] }]
raw_values = @data.with { |c| c.get_multi(keys_to_names.keys) }
values = {}
raw_values.each do |key, value|
entry = deserialize_entry(value)
unless entry.expired? || entry.mismatched?(normalize_version(keys_to_names[key], options))
values[keys_to_names[key]] = entry.value
end
end
values
end
# Delete an entry from the cache.
def delete_entry(key, options)
rescue_error_with(false) { @data.with { |c| c.delete(key) } }
end
# Memcache keys are binaries. So we need to force their encoding to binary
# before applying the regular expression to ensure we are escaping all
# characters properly.
def normalize_key(key, options)
key = super.dup
key = key.force_encoding(Encoding::ASCII_8BIT)
key = key.gsub(ESCAPE_KEY_CHARS) { |match| "%#{match.getbyte(0).to_s(16).upcase}" }
key = "#{key[0, 213]}:md5:#{ActiveSupport::Digest.hexdigest(key)}" if key.size > 250
key
end
def deserialize_entry(raw_value)
if raw_value
entry = Marshal.load(raw_value) rescue raw_value
entry.is_a?(Entry) ? entry : Entry.new(entry)
end
end
def rescue_error_with(fallback)
yield
rescue Dalli::DalliError => e
logger.error("DalliError (#{e}): #{e.message}") if logger
fallback
end
end
end
end