diff --git a/graph_utils.cc b/graph_utils.cc
new file mode 100644
index 0000000..79d5733
--- /dev/null
+++ b/graph_utils.cc
@@ -0,0 +1,41 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "update_engine/graph_utils.h"
+#include "base/basictypes.h"
+
+using std::vector;
+
+namespace chromeos_update_engine {
+
+namespace graph_utils {
+
+uint64 EdgeWeight(const Graph& graph, const Edge& edge) {
+  uint64 weight = 0;
+  const vector<Extent>& extents =
+      graph[edge.first].out_edges.find(edge.second)->second.extents;
+  for (vector<Extent>::const_iterator it = extents.begin();
+       it != extents.end(); ++it) {
+    weight += it->num_blocks();
+  }
+  return weight;
+}
+
+void AppendBlockToExtents(vector<Extent>* extents, uint64 block) {
+  if (!extents->empty()) {
+    Extent& extent = extents->back();
+    if (extent.start_block() + extent.num_blocks() == block) {
+      extent.set_num_blocks(extent.num_blocks() + 1);
+      return;
+    }
+  }
+  Extent new_extent;
+  new_extent.set_start_block(block);
+  new_extent.set_num_blocks(1);
+  extents->push_back(new_extent);
+}
+
+}  // namespace graph_utils
+
+}  // namespace chromeos_update_engine