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# frozen_string_literal: true
module Dalli
##
# This module contains methods for validating and normalizing the servers
# argument passed to the client. This argument can be nil, a string, or
# an array of strings. Each string value in the argument can represent
# a single server or a comma separated list of servers.
#
# If nil, it falls back to the values of ENV['MEMCACHE_SERVERS'] if the latter is
# defined. If that environment value is not defined, a default of '127.0.0.1:11211'
# is used.
#
# A server config string can take one of three forms:
# * A colon separated string of (host, port, weight) where both port and
# weight are optional (e.g. 'localhost', 'abc.com:12345', 'example.org:22222:3')
# * A colon separated string of (UNIX socket, weight) where the weight is optional
# (e.g. '/var/run/memcached/socket', '/tmp/xyz:3') (not supported on Windows)
# * A URI with a 'memcached' protocol (e.g. 'memcached://localhost:11211')
#
# The methods in this module do not validate the format of individual server strings, but
# rather normalize the argument into a compact array, wherein each array entry corresponds
# to a single server config string. If that normalization is not possible, then an
# ArgumentError is thrown.
##
module ServersArgNormalizer
ENV_VAR_NAME = 'MEMCACHE_SERVERS'
DEFAULT_SERVERS = ['127.0.0.1:11211'].freeze
##
# Normalizes the argument into an array of servers.
# If the argument is a string, or an array containing strings, it's expected that the URIs are comma separated e.g.
# "memcache1.example.com:11211,memcache2.example.com:11211,memcache3.example.com:11211"
def self.normalize_servers(arg)
arg = apply_defaults(arg)
validate_type(arg)
Array(arg).flat_map { |s| s.split(',') }.reject(&:empty?)
end
def self.apply_defaults(arg)
return arg unless arg.nil?
ENV.fetch(ENV_VAR_NAME, nil) || DEFAULT_SERVERS
end
def self.validate_type(arg)
return if arg.is_a?(String)
return if arg.is_a?(Array) && arg.all?(String)
raise ArgumentError,
'An explicit servers argument must be a comma separated string or an array containing strings.'
end
end
end
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