--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/main/java/jp/ac/u_ryukyu/ie/cr/shoshi/jungle/store/impl/util/Commitment.java	Tue Jan 15 02:24:42 2013 +0900
@@ -0,0 +1,94 @@
+package jp.ac.u_ryukyu.ie.cr.shoshi.jungle.store.impl.util;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+
+import jp.ac.u_ryukyu.ie.cr.shoshi.jungle.util.Pair;
+
+public final class Commitment
+{
+	private Commitment()
+	{
+		// 
+	}
+	
+	public static <T> Pair<Publisher<T>,Value<T>> newInstance(T _draft,T _sub)
+	{
+		ValueWrapper<T> fail = new ValueWrapper<T>(_sub);
+		ValueWrapper<T> init = new ValueWrapper<T>(_sub);
+		ValueWrapper<T> draft = new ValueWrapper<T>(_draft);
+		AtomicReference<ValueWrapper<T>> value = new AtomicReference<ValueWrapper<T>>(init);
+		
+		Publisher<T> p = new Publisher<T>(value,draft,fail);
+		Value<T> v = new Value<T>(value,fail);
+		
+		return new Pair<Publisher<T>,Value<T>>(p,v);
+	}
+	
+	public static class Publisher<T>
+	{
+		private final AtomicReference<ValueWrapper<T>> value;
+		private final ValueWrapper<T> draft;
+		private final AtomicBoolean flag;
+		private final ValueWrapper<T> fail;
+		
+		Publisher(AtomicReference<ValueWrapper<T>> _value,ValueWrapper<T> _draft,ValueWrapper<T> _fail)
+		{
+			value = _value;
+			draft = _draft;
+			flag = new AtomicBoolean(false);
+			fail = _fail;
+		}
+		
+		public void commit()
+		{
+			if(flag.compareAndSet(true,false)){
+				value.set(draft);
+			}
+		}
+		
+		public void fail()
+		{
+			if(flag.compareAndSet(true,false)){
+				value.set(fail);
+			}
+		}
+	}
+	
+	public static class Value<T>
+	{
+		private final AtomicReference<ValueWrapper<T>> value;
+		private final ValueWrapper<T> fail;
+		
+		Value(AtomicReference<ValueWrapper<T>> _value,ValueWrapper<T> _fail)
+		{
+			value = _value;
+			fail = _fail;
+		}
+		
+		public T get()
+		{
+			return value.get().get();
+		}
+		
+		public boolean isFail()
+		{
+			return (value.get() == fail);
+		}
+	}
+	
+	private static class ValueWrapper<T>
+	{
+		private final T object;
+		
+		public ValueWrapper(T _object)
+		{
+			object = _object;
+		}
+		
+		public T get()
+		{
+			return object;
+		}
+	}
+}