diff --git a/nsync/src/sync-diff-state-container.h b/nsync/src/sync-diff-state-container.h
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+/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2012 University of California, Los Angeles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Author: Zhenkai Zhu <zhenkai@cs.ucla.edu>
+ *         Chaoyi Bian <bcy@pku.edu.cn>
+ *	   Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ */
+
+#ifndef SYNC_DIFF_STATE_CONTAINER_H
+#define SYNC_DIFF_STATE_CONTAINER_H
+
+#include "sync-diff-state.h"
+#include "sync-digest.h"
+
+#include <boost/multi_index_container.hpp>
+#include <boost/multi_index/tag.hpp>
+// #include <boost/multi_index/ordered_index.hpp>
+// #include <boost/multi_index/composite_key.hpp>
+#include <boost/multi_index/hashed_index.hpp>
+#include <boost/multi_index/sequenced_index.hpp>
+// #include <boost/multi_index/random_access_index.hpp>
+#include <boost/multi_index/member.hpp>
+#include <boost/multi_index/mem_fun.hpp>
+
+namespace mi = boost::multi_index;
+
+namespace Sync {
+
+/// @cond include_hidden 
+struct sequenced { };
+struct timed { };
+/// @endcond
+
+/**
+ * \ingroup sync
+ * @brief Container for differential states
+ */
+struct DiffStateContainer : public mi::multi_index_container<
+  DiffStatePtr,
+  mi::indexed_by<
+    // For fast access to elements using DiffState hashes
+    mi::hashed_unique<
+      mi::tag<hashed>,
+      mi::const_mem_fun<DiffState, DigestConstPtr, &DiffState::getDigest>,
+      DigestPtrHash,
+      DigestPtrEqual
+      >
+    ,        
+    // sequenced index to access older/newer element (like in list)
+    mi::sequenced<mi::tag<sequenced> >
+    >
+  >
+{
+};
+
+} // Sync
+
+#endif // SYNC_DIFF_STATE_CONTAINER_H