diff --git a/graph_utils.cc b/graph_utils.cc
index 5ad67cf..47d0c53 100644
--- a/graph_utils.cc
+++ b/graph_utils.cc
@@ -3,8 +3,17 @@
 // found in the LICENSE file.
 
 #include "update_engine/graph_utils.h"
-#include "base/basictypes.h"
 
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <base/basictypes.h>
+#include <base/logging.h>
+
+using std::make_pair;
+using std::pair;
+using std::string;
 using std::vector;
 
 namespace chromeos_update_engine {
@@ -45,6 +54,124 @@
   extents->push_back(new_extent);
 }
 
+void AddReadBeforeDep(Vertex* src,
+                      Vertex::Index dst,
+                      uint64_t block) {
+  Vertex::EdgeMap::iterator edge_it = src->out_edges.find(dst);
+  if (edge_it == src->out_edges.end()) {
+    // Must create new edge
+    pair<Vertex::EdgeMap::iterator, bool> result =
+        src->out_edges.insert(make_pair(dst, EdgeProperties()));
+    CHECK(result.second);
+    edge_it = result.first;
+  }
+  AppendBlockToExtents(&edge_it->second.extents, block);
+}
+
+void AddReadBeforeDepExtents(Vertex* src,
+                             Vertex::Index dst,
+                             const vector<Extent>& extents) {
+  // TODO(adlr): Be more efficient than adding each block individually.
+  for (vector<Extent>::const_iterator it = extents.begin(), e = extents.end();
+       it != e; ++it) {
+    const Extent& extent = *it;
+    for (uint64_t block = extent.start_block(),
+             block_end = extent.start_block() + extent.num_blocks();
+         block != block_end; ++block) {
+      AddReadBeforeDep(src, dst, block);
+    }
+  }
+}
+
+void DropWriteBeforeDeps(Vertex::EdgeMap* edge_map) {
+  // Specially crafted for-loop for the map-iterate-delete dance.
+  for (Vertex::EdgeMap::iterator it = edge_map->begin();
+       it != edge_map->end(); ) {
+    if (!it->second.write_extents.empty())
+      it->second.write_extents.clear();
+    if (it->second.extents.empty()) {
+      // Erase *it, as it contains no blocks
+      edge_map->erase(it++);
+    } else {
+      ++it;
+    }
+  }
+}
+
+// For each node N in graph, drop all edges N->|index|.
+void DropIncomingEdgesTo(Graph* graph, Vertex::Index index) {
+  // This would be much more efficient if we had doubly-linked
+  // edges in the graph.
+  for (Graph::iterator it = graph->begin(), e = graph->end(); it != e; ++it) {
+    it->out_edges.erase(index);
+  }
+}
+
+Extent GetElement(const std::vector<Extent>& collection, size_t index) {
+  return collection[index];
+}
+Extent GetElement(
+    const google::protobuf::RepeatedPtrField<Extent>& collection,
+    size_t index) {
+  return collection.Get(index);
+}
+
+namespace {
+template<typename T>
+void DumpExtents(const T& field, int prepend_space_count) {
+  string header(prepend_space_count, ' ');
+  for (int i = 0, e = field.size(); i != e; ++i) {
+    LOG(INFO) << header << "(" << GetElement(field, i).start_block() << ", "
+              << GetElement(field, i).num_blocks() << ")";
+  }
+}
+
+void DumpOutEdges(const Vertex::EdgeMap& out_edges) {
+  for (Vertex::EdgeMap::const_iterator it = out_edges.begin(),
+           e = out_edges.end(); it != e; ++it) {
+    LOG(INFO) << "    " << it->first << " read-before:";
+    DumpExtents(it->second.extents, 6);
+    LOG(INFO) << "      write-before:";
+    DumpExtents(it->second.write_extents, 6);
+  }
+}
+}  // namespace {}
+
+void DumpGraph(const Graph& graph) {
+  LOG(INFO) << "Graph length: " << graph.size();
+  for (Graph::size_type i = 0, e = graph.size(); i != e; ++i) {
+    string type_str = "UNK";
+    switch(graph[i].op.type()) {
+      case DeltaArchiveManifest_InstallOperation_Type_BSDIFF:
+        type_str = "BSDIFF";
+        break;
+      case DeltaArchiveManifest_InstallOperation_Type_MOVE:
+        type_str = "MOVE";
+        break;
+      case DeltaArchiveManifest_InstallOperation_Type_REPLACE:
+        type_str = "REPLACE";
+        break;
+      case DeltaArchiveManifest_InstallOperation_Type_REPLACE_BZ:
+        type_str = "REPLACE_BZ";
+        break;
+    }
+    LOG(INFO) << i 
+              << (graph[i].valid ? "" : "-INV")
+              << ": " << graph[i].file_name
+              << ": " << type_str;
+    LOG(INFO) << "  src_extents:";
+    DumpExtents(graph[i].op.src_extents(), 4);
+    LOG(INFO) << "  dst_extents:";
+    DumpExtents(graph[i].op.dst_extents(), 4);
+    LOG(INFO) << "  out edges:";
+    DumpOutEdges(graph[i].out_edges);
+  }
+}
+
 }  // namespace graph_utils
 
+bool operator==(const Extent& a, const Extent& b) {
+  return a.start_block() == b.start_block() && a.num_blocks() == b.num_blocks();
+}
+
 }  // namespace chromeos_update_engine