Module: Concurrent::Dereferenceable

Included in:
Agent, MVar, Obligation, TimerTask
Defined in:
lib/concurrent/dereferenceable.rb

Overview

Object references in Ruby are mutable. This can lead to serious problems when the ‘#value` of a concurrent object is a mutable reference. Which is always the case unless the value is a `Fixnum`, `Symbol`, or similar “primitive” data type. Most classes in this library that expose a `#value` getter method do so using this mixin module.

Instance Method Summary collapse

Instance Method Details

#value ⇒ Object Also known as: deref

Return the value this object represents after applying the options specified by the ‘#set_deref_options` method.

When multiple deref options are set the order of operations is strictly defined. The order of deref operations is:

  • ‘:copy_on_deref`

  • ‘:dup_on_deref`

  • ‘:freeze_on_deref`

Because of this ordering there is no need to ‘#freeze` an object created by a provided `:copy_on_deref` block. Simply set `:freeze_on_deref` to `true`. Setting both `:dup_on_deref` to `true` and `:freeze_on_deref` to `true` is as close to the behavior of a “pure” functional language (like Erlang, Clojure, or Haskell) as we are likely to get in Ruby.

This method is thread-safe and synchronized with the internal ‘#mutex`.

Returns:

  • (Object) —

    the current value of the object



28
29
30
31
32
33
 
# File 'lib/concurrent/dereferenceable.rb', line 28

def value
  mutex.lock
  apply_deref_options(@value)
ensure
  mutex.unlock
end