module Dalli::ServersArgNormalizer

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 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, which will typically include a username/password

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.

Constants

DEFAULT_SERVERS
ENV_VAR_NAME

Public Class Methods

apply_defaults(arg) click to toggle source
# File lib/dalli/servers_arg_normalizer.rb, line 40
def self.apply_defaults(arg)
  return arg unless arg.nil?

  ENV[ENV_VAR_NAME] || DEFAULT_SERVERS
end
normalize_servers(arg) click to toggle source

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”

# File lib/dalli/servers_arg_normalizer.rb, line 34
def self.normalize_servers(arg)
  arg = apply_defaults(arg)
  validate_type(arg)
  Array(arg).flat_map { |s| s.split(',') }.reject(&:empty?)
end
validate_type(arg) click to toggle source
# File lib/dalli/servers_arg_normalizer.rb, line 46
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