Get rid of the ruby-atomic dependency.

Author: thedarkone

lib/thread_safe/util/atomic_reference.rb

@@ -1,12 +1,45 @@
 module ThreadSafe
   module Util
-    # An overhead-less atomic reference.
     AtomicReference =
       if defined?(Rubinius::AtomicReference)
+        # An overhead-less atomic reference.
         Rubinius::AtomicReference
       else
-        require 'atomic'
-        defined?(Atomic::InternalReference) ? Atomic::InternalReference : Atomic
+        begin
+          require 'atomic'
+          defined?(Atomic::InternalReference) ? Atomic::InternalReference : Atomic
+        rescue NameError
+          require 'thread' # get Mutex on 1.8
+          class FullLockingAtomicReference
+            def initialize(value = nil)
+              @___mutex = Mutex.new
+              @___value = value
+            end
+
+            def get
+              @___mutex.synchronize { @___value }
+            end
+            alias_method :value, :get
+
+            def set(new_value)
+              @___mutex.synchronize { @___value = new_value }
+            end
+            alias_method :value=, :set
+
+            def compare_and_set(old_value, new_value)
+              return false unless @___mutex.try_lock
+              begin
+                return false unless @___value.equal? old_value
+                @___value = new_value
+              ensure
+                @___mutex.unlock
+              end
+              true
+            end
+          end
+
+          FullLockingAtomicReference
+        end
       end
   end
 end

thread_safe.gemspec

@@ -19,6 +19,6 @@ Gem::Specification.new do |gem|
   gem.version       = ThreadSafe::VERSION
   gem.license       = "Apache-2.0"
 
-  gem.add_dependency 'atomic', ['>= 1.1.7', '< 2']
+  gem.add_development_dependency 'atomic', ['>= 1.1.7', '< 2']
   gem.add_development_dependency 'rake'
 end