thread_variable? behaves strangely. Restore legacy NULL handling.

Author: ioquatix

lib/concurrent-ruby/concurrent/atomic/fiber_local_var.rb

@@ -20,9 +20,7 @@ def initialize(default = nil, &default_block)
 
     # @!macro thread_local_var_method_get
     def value
-      Thread.current.fetch(@name) do
-        Thread.current[@name] = default
-      end
+      Thread.current.fetch(@name) {default}
     end
 
     # @!macro thread_local_var_method_set

lib/concurrent-ruby/concurrent/atomic/thread_local_var.rb

@@ -23,15 +23,23 @@ def initialize(default = nil, &default_block)
 
     # @!macro thread_local_var_method_get
     def value
-      if Thread.current.thread_variable?(@name)
-        Thread.current.thread_variable_get(@name)
+      value = Thread.current.thread_variable_get(@name)
+
+      if value.nil?
+        default
+      elsif value.equal?(NULL)
+        nil
       else
-        Thread.current.thread_variable_set(@name, default)
+        value
       end
     end
 
     # @!macro thread_local_var_method_set
     def value=(value)
+      if value.nil?
+        value = NULL
+      end
+
       Thread.current.thread_variable_set(@name, value)
     end
 

spec/concurrent/atomic/thread_local_var_spec.rb

@@ -100,7 +100,7 @@ module Concurrent
       end
 
       it 'does not modify the value for other threads' do
-        v.value = 2
+        v.value = 3
 
         b1 = CountDownLatch.new(2)
         b2 = CountDownLatch.new(2)