Module: Dalli::ServersArgNormalizer

Defined in:
lib/dalli/servers_arg_normalizer.rb

Overview

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.

Constant Summary collapse

ENV_VAR_NAME = 
'MEMCACHE_SERVERS'
DEFAULT_SERVERS = 
['127.0.0.1:11211'].freeze

Class Method Summary collapse

Class Method Details

.apply_defaults(arg) ⇒ Object 



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# File 'lib/dalli/servers_arg_normalizer.rb', line 40

def self.apply_defaults(arg)
  return arg unless arg.nil?

  ENV.fetch(ENV_VAR_NAME, nil) || DEFAULT_SERVERS
end

.normalize_servers(arg) ⇒ Object

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”



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# 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) ⇒ Object

Raises:

  • (ArgumentError) 


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# 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