--- a/src/alice/codesegment/InputDataSegment.java	Wed Jan 11 00:53:30 2012 +0900
+++ b/src/alice/codesegment/InputDataSegment.java	Wed Jan 11 23:28:02 2012 +0900
@@ -4,7 +4,6 @@
 import java.util.concurrent.atomic.AtomicInteger;
 
 import alice.datasegment.DataSegment;
-import alice.datasegment.DataSegmentManager;
 import alice.datasegment.DataSegmentValue;
 
 public class InputDataSegment {

--- a/src/alice/datasegment/CommandType.java	Wed Jan 11 00:53:30 2012 +0900
+++ b/src/alice/datasegment/CommandType.java	Wed Jan 11 23:28:02 2012 +0900
@@ -2,6 +2,7 @@
 
 public enum CommandType {
 	PUT,
+	UPDATE,
 	PEEK,
 	TAKE,
 	REMOVE,

--- a/src/alice/datasegment/DataSegmentKey.java	Wed Jan 11 00:53:30 2012 +0900
+++ b/src/alice/datasegment/DataSegmentKey.java	Wed Jan 11 23:28:02 2012 +0900
@@ -30,6 +30,10 @@
 					try {
 						Command cmd = cmdQueue.take();
 						switch (cmd.cmdType) {
+						case UPDATE:
+							if (dataList.size() != 0) {
+								dataList.remove(0);
+							}
 						case PUT:
 							int index = tailIndex.getAndIncrement();
 							dataList.add(new DataSegmentValue(index, cmd.val));
@@ -59,14 +63,19 @@
 								waitList.add(cmd);
 								break;
 							}
+							boolean waitFlag = true;
 							for (DataSegmentValue data : dataList) {
 								if (data.index > cmd.index) {
 									// TODO: make and send reply msg
-
+									
+									
 									dataList.remove(data);
+									waitFlag = false;
 									break;
 								}
 							}
+							if (waitFlag)
+								waitList.add(cmd);
 							break;
 						case REMOVE:
 							// TODO: implements later
@@ -74,7 +83,6 @@
 						default:
 						}
 					} catch (InterruptedException e) {
-						// TODO Auto-generated catch block
 						e.printStackTrace();
 					}
 				}

--- a/src/alice/datasegment/DataSegmentManager.java	Wed Jan 11 00:53:30 2012 +0900
+++ b/src/alice/datasegment/DataSegmentManager.java	Wed Jan 11 23:28:02 2012 +0900
@@ -9,6 +9,7 @@
 	ConcurrentHashMap<String, DataSegmentKey> dataSegments = new ConcurrentHashMap<String, DataSegmentKey>();
 	
 	public abstract void put(String key, Value val);
+	public abstract void update(String key, Value val);
 	public void take(String key, CodeSegment cs) {
 		take(key, 0, cs);
 	}

--- a/src/alice/datasegment/LocalDataSegmentManager.java	Wed Jan 11 00:53:30 2012 +0900
+++ b/src/alice/datasegment/LocalDataSegmentManager.java	Wed Jan 11 23:28:02 2012 +0900
@@ -27,6 +27,12 @@
 	}
 
 	@Override
+	public void update(String key, Value val) {
+		DataSegmentKey dataSegmentKey = getDataSegmentKey(key);
+		dataSegmentKey.addCommand(new Command(CommandType.UPDATE, val, 0, null, 0));
+	}
+
+	@Override
 	public void take(String key, int index, CodeSegment cs) {
 		DataSegmentKey dataSegmentKey = getDataSegmentKey(key);
 		int seq = this.seq.getAndIncrement();