Merge pull request #464 from ruby-concurrency/synchronization

Remove #ensure_ivar_visibility! in favor of .save_initialization!

Author: jdantonio

ext/com/concurrent_ruby/ext/SynchronizationLibrary.java

@@ -93,7 +93,7 @@ public static class JRubyAttrVolatile {
         // attempt to avoid code elimination.
         private static volatile ThreadContext threadContext = null;
 
-        @JRubyMethod(name = "full_memory_barrier", visibility = Visibility.PRIVATE)
+        @JRubyMethod(name = "full_memory_barrier", visibility = Visibility.PUBLIC)
         public static IRubyObject fullMemoryBarrier(ThreadContext context, IRubyObject self) {
             // Prevent reordering of ivar writes with publication of this instance
             if (UnsafeHolder.U == null || !UnsafeHolder.SUPPORTS_FENCES) {
@@ -107,7 +107,7 @@ public static IRubyObject fullMemoryBarrier(ThreadContext context, IRubyObject s
             return context.nil;
         }
 
-        @JRubyMethod(name = "instance_variable_get_volatile", visibility = Visibility.PROTECTED)
+        @JRubyMethod(name = "instance_variable_get_volatile", visibility = Visibility.PUBLIC)
         public static IRubyObject instanceVariableGetVolatile(ThreadContext context, IRubyObject self, IRubyObject name) {
             // Ensure we ses latest value with loadFence
             if (UnsafeHolder.U == null || !UnsafeHolder.SUPPORTS_FENCES) {
@@ -120,7 +120,7 @@ public static IRubyObject instanceVariableGetVolatile(ThreadContext context, IRu
             }
         }
 
-        @JRubyMethod(name = "instance_variable_set_volatile", visibility = Visibility.PROTECTED)
+        @JRubyMethod(name = "instance_variable_set_volatile", visibility = Visibility.PUBLIC)
         public static IRubyObject InstanceVariableSetVolatile(ThreadContext context, IRubyObject self, IRubyObject name, IRubyObject value) {
             // Ensure we make last update visible
             if (UnsafeHolder.U == null || !UnsafeHolder.SUPPORTS_FENCES) {

lib/concurrent/synchronization/abstract_object.rb

@@ -10,28 +10,6 @@ def initialize
         raise NotImplementedError
       end
 
-      # @!macro [attach] synchronization_object_method_ensure_ivar_visibility
-      #
-      #   Allows to construct immutable objects where all fields are visible after initialization, not requiring
-      #   further synchronization on access.
-      #   @example
-      #     class AClass
-      #       attr_reader :val
-      #       def initialize(val)
-      #         @val = val # final value, after assignment it's not changed (just convention, not enforced)
-      #         ensure_ivar_visibility!
-      #         # now it can be shared as Java's final field
-      #       end
-      #     end
-      # @!visibility private
-      def ensure_ivar_visibility!
-        # We have to prevent ivar writes to reordered with storing of the final instance reference
-        # Therefore wee need a fullFence to prevent reordering in both directions.
-        full_memory_barrier
-      end
-
-      protected
-
       # @!visibility private
       # @abstract
       def full_memory_barrier

lib/concurrent/synchronization/object.rb

@@ -52,7 +52,7 @@ def self.safe_initialization!
         def self.new(*)
           object = super
         ensure
-          object.ensure_ivar_visibility! if object
+          object.full_memory_barrier if object
         end
 
         @safe_initialization = true

spec/concurrent/synchronization_spec.rb

@@ -49,22 +49,22 @@ class ADClass < ACClass
       end
 
       it 'does not ensure visibility when not needed' do
-        expect_any_instance_of(AAClass).not_to receive(:ensure_ivar_visibility!)
+        expect_any_instance_of(AAClass).not_to receive(:full_memory_barrier)
         AAClass.new
       end
 
       it "does ensure visibility when specified" do
-        expect_any_instance_of(ABClass).to receive(:ensure_ivar_visibility!)
+        expect_any_instance_of(ABClass).to receive(:full_memory_barrier)
         ABClass.new
       end
 
       it "does ensure visibility when specified in a parent" do
-        expect_any_instance_of(ACClass).to receive(:ensure_ivar_visibility!)
+        expect_any_instance_of(ACClass).to receive(:full_memory_barrier)
         ACClass.new
       end
 
       it "does ensure visibility once when specified in child again" do
-        expect_any_instance_of(ADClass).to receive(:ensure_ivar_visibility!)
+        expect_any_instance_of(ADClass).to receive(:full_memory_barrier)
         ADClass.new
       end