Moved NULL to constants file.

Author: jdantonio

CHANGELOG.md

@@ -1,3 +1,7 @@
+### Upcoming Release v1.0.0 (TBD)
+
+* Shared constants now in `lib/concurrent/constants.rb`
+
 ## Current Release v1.0.0.pre2 (19 September 2015)
 
 * Simplification of `RubySingleThreadExecutor`

lib/concurrent.rb

@@ -1,8 +1,9 @@
 require 'concurrent/version'
+require 'concurrent/constants'
+require 'concurrent/errors'
 require 'concurrent/configuration'
 
 require 'concurrent/atomics'
-require 'concurrent/errors'
 require 'concurrent/executors'
 require 'concurrent/synchronization'
 
@@ -126,9 +127,4 @@
 # * Be small, lean, and loosely coupled
 module Concurrent
 
-  # Various classes within allows for +nil+ values to be stored,
-  # so a special +NULL+ token is required to indicate the "nil-ness".
-  # @!visibility private
-  NULL = Object.new
-
 end

lib/concurrent/atomic/abstract_thread_local_var.rb

@@ -1,14 +1,12 @@
+require 'concurrent/constants'
+
 module Concurrent
 
   # @!macro thread_local_var
   # @!macro internal_implementation_note
   # @!visibility private
   class AbstractThreadLocalVar
 
-    # @!visibility private
-    NIL_SENTINEL = Object.new
-    private_constant :NIL_SENTINEL
-
     # @!macro thread_local_var_method_initialize
     def initialize(default = nil)
       @default = default

lib/concurrent/atomic/java_thread_local_var.rb

@@ -14,7 +14,7 @@ def value
 
         if value.nil?
           @default
-        elsif value == NIL_SENTINEL
+        elsif value == NULL
           nil
         else
           value

lib/concurrent/atomic/ruby_thread_local_var.rb

@@ -51,7 +51,7 @@ def value
         value = array[@index]
         if value.nil?
           @default
-        elsif value.equal?(NIL_SENTINEL)
+        elsif value.equal?(NULL)
           nil
         else
           value
@@ -72,7 +72,7 @@ def value=(value)
         LOCK.synchronize { ARRAYS[array.object_id] = array }
         ObjectSpace.define_finalizer(me, self.class.thread_finalizer(array))
       end
-      array[@index] = (value.nil? ? NIL_SENTINEL : value)
+      array[@index] = (value.nil? ? NULL : value)
       value
     end
 
@@ -159,7 +159,7 @@ def value_for(thread)
         value = array[@index]
         if value.nil?
           @default
-        elsif value.equal?(NIL_SENTINEL)
+        elsif value.equal?(NULL)
           nil
         else
           value

lib/concurrent/collection/map/atomic_reference_map_backend.rb

@@ -1,3 +1,4 @@
+require 'concurrent/constants'
 require 'concurrent/thread_safe/util'
 require 'concurrent/thread_safe/util/adder'
 require 'concurrent/thread_safe/util/cheap_lockable'

lib/concurrent/collection/map/non_concurrent_map_backend.rb

@@ -1,3 +1,5 @@
+require 'concurrent/constants'
+
 module Concurrent
 
   # @!visibility private

lib/concurrent/constants.rb

@@ -0,0 +1,8 @@
+module Concurrent
+
+  # Various classes within allows for +nil+ values to be stored,
+  # so a special +NULL+ token is required to indicate the "nil-ness".
+  # @!visibility private
+  NULL = Object.new
+
+end

lib/concurrent/exchanger.rb

@@ -1,3 +1,4 @@
+require 'concurrent/constants'
 require 'concurrent/errors'
 require 'concurrent/maybe'
 require 'concurrent/atomic/atomic_reference'
@@ -139,10 +140,6 @@ class RubyExchanger < AbstractExchanger
     # not include the arena or the multi-processor spin loops.
     # http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/java/util/concurrent/Exchanger.java
 
-    # @!visibility private
-    NIL_SENTINEL = Object.new
-    private_constant :NIL_SENTINEL
-
     # @!visibility private
     class Node < Concurrent::AtomicReference
       attr_reader :item, :latch
@@ -249,7 +246,7 @@ def do_exchange(value, timeout)
       #     - Wake the sleeping occupier
       #     - Return the occupier's item
 
-      value = NIL_SENTINEL if value.nil?                # The sentinel allows nil to be a valid value
+      value = NULL if value.nil?                        # The sentinel allows nil to be a valid value
       slot = @slot                                      # Convenience to minimize typing @
       me = Node.new(value)                              # create my node in case I need to occupy
       end_at = Concurrent.monotonic_time + timeout.to_f # The time to give up
@@ -282,7 +279,7 @@ def do_exchange(value, timeout)
         break CANCEL if timeout && Concurrent.monotonic_time >= end_at
       end
 
-      result == NIL_SENTINEL ? nil : result
+      result == NULL ? nil : result
     end
   end
 

lib/concurrent/future.rb

@@ -1,4 +1,5 @@
 require 'thread'
+require 'concurrent/constants'
 require 'concurrent/errors'
 require 'concurrent/ivar'
 require 'concurrent/executor/safe_task_executor'