module Mongo::Id
This module abstracts the functionality for generating sequential unique integer IDs for instances of the class. It defines the method next_id on the class that includes it. The implementation ensures that the IDs will be unique even when called from multiple threads.
@example Include the Id
module.
class Foo include Mongo::Id end f = Foo.new foo.next_id # => 1 foo.next_id # => 2
Classes which include Id
should not access `@@id` or `@@id_lock` directly; instead, they should call `#next_id` in `#initialize` and save the result in the instance being created.
@example Save the ID in the instance of the including class.
class Bar include Mongo::Id attr_reader :id def initialize @id = self.class.next_id end end a = Bar.new a.id # => 1 b = Bar.new b.id # => 2
@since 2.7.0 @api private
Public Class Methods
included(klass)
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# File lib/mongo/id.rb, line 51 def self.included(klass) klass.class_variable_set(:@@id, 0) klass.class_variable_set(:@@id_lock, Mutex.new) klass.define_singleton_method(:next_id) do klass.class_variable_get(:@@id_lock).synchronize do id = class_variable_get(:@@id) klass.class_variable_set(:@@id, id + 1) klass.class_variable_get(:@@id) end end end