Move AtomicMarkableReference out of Edge

Author: ianks

README.md

@@ -108,6 +108,7 @@ Thread-safe variables:
 * [ReadWriteLock](http://ruby-concurrency.github.io/concurrent-ruby/Concurrent/ReadWriteLock.html) A lock that supports multiple readers but only one writer.
 * [ReentrantReadWriteLock](http://ruby-concurrency.github.io/concurrent-ruby/Concurrent/ReentrantReadWriteLock.html) A read/write lock with reentrant and upgrade features.
 * [Semaphore](http://ruby-concurrency.github.io/concurrent-ruby/Concurrent/Semaphore.html) A counting-based locking mechanism that uses permits.
+* [AtomicMarkableReference](http://ruby-concurrency.github.io/concurrent-ruby/Concurrent/Atomic/AtomicMarkableReference.html)
 
 ### Edge Features
 
@@ -129,7 +130,6 @@ be obeyed though. Features developed in `concurrent-ruby-edge` are expected to m
   Functionally equivalent to Go [channels](https://tour.golang.org/concurrency/2) with additional
   inspiration from Clojure [core.async](https://clojure.github.io/core.async/).
 * [LazyRegister](http://ruby-concurrency.github.io/concurrent-ruby/Concurrent/LazyRegister.html)
-* [AtomicMarkableReference](http://ruby-concurrency.github.io/concurrent-ruby/Concurrent/Edge/AtomicMarkableReference.html)
 * [LockFreeLinkedSet](http://ruby-concurrency.github.io/concurrent-ruby/Concurrent/Edge/LockFreeLinkedSet.html)
 * [LockFreeStack](http://ruby-concurrency.github.io/concurrent-ruby/Concurrent/LockFreeStack.html)
 

lib/concurrent-edge.rb

@@ -6,7 +6,6 @@
 require 'concurrent/exchanger'
 require 'concurrent/lazy_register'
 
-require 'concurrent/edge/atomic_markable_reference'
 require 'concurrent/edge/lock_free_linked_set'
 require 'concurrent/edge/lock_free_queue'
 require 'concurrent/edge/lock_free_stack'

lib/concurrent.rb

@@ -7,6 +7,7 @@
 require 'concurrent/executors'
 require 'concurrent/synchronization'
 
+require 'concurrent/atomic/atomic_markable_reference'
 require 'concurrent/atomic/atomic_reference'
 require 'concurrent/agent'
 require 'concurrent/atom'

lib/concurrent/edge/atomic_markable_reference.rb renamed to lib/concurrent/atomic/atomic_markable_reference.rb

@@ -1,6 +1,5 @@
 module Concurrent
-  module Edge
-
+  module Atomic
     # @!macro [attach] atomic_markable_reference
     #
     #   An atomic reference which maintains an object reference along with a mark bit
@@ -144,9 +143,9 @@ def try_update!
 
         unless compare_and_set old_val, new_val, old_mark, new_mark
           fail ::Concurrent::ConcurrentUpdateError,
-               'AtomicMarkableReference: Update failed due to race condition.',
-               'Note: If you would like to guarantee an update, please use ' \
-               'the `AtomicMarkableReference#update` method.'
+            'AtomicMarkableReference: Update failed due to race condition.',
+            'Note: If you would like to guarantee an update, please use ' \
+            'the `AtomicMarkableReference#update` method.'
         end
 
         ImmutableArray[new_val, new_mark]

lib/concurrent/edge/lock_free_linked_set/node.rb

@@ -1,16 +1,17 @@
-require 'concurrent/edge/atomic_markable_reference'
+require 'concurrent/atomic/atomic_markable_reference'
 
 module Concurrent
   module Edge
     class LockFreeLinkedSet
       class Node < Synchronization::Object
         include Comparable
+        include Concurrent::Atomic
 
         safe_initialization!
 
         def initialize(data = nil, successor = nil)
           super()
-          @SuccessorReference = AtomicMarkableReference.new(successor || Tail.new)
+          @SuccessorReference  = AtomicMarkableReference.new(successor || Tail.new)
           @Data                = data
           @Key                 = key_for data
         end

spec/concurrent/atomic/atomic_markable_reference_spec.rb

@@ -1,4 +1,4 @@
-RSpec.describe Concurrent::Edge::AtomicMarkableReference do
+RSpec.describe Concurrent::Atomic::AtomicMarkableReference do
   subject { described_class.new 1000, true }
 
   describe '.initialize' do