AU: More graph utilities

graph_utils.h

 // 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.
 
 #ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_GRAPH_UTILS_H__
 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_GRAPH_UTILS_H__
 
 #include <vector>
 #include "base/basictypes.h"
 #include "update_engine/graph_types.h"
 #include "update_engine/update_metadata.pb.h"
 
 // A few utility functions for graphs
 
 namespace chromeos_update_engine {
 
 namespace graph_utils {
 
 // Returns the number of blocks represented by all extents in the edge.
 uint64_t EdgeWeight(const Graph& graph, const Edge& edge);
 
+// These add a read-before dependency from graph[src] -> graph[dst]. If the dep
+// already exists, the block/s is/are added to the existing edge.
+void AddReadBeforeDep(Vertex* src,
+                      Vertex::Index dst,
+                      uint64_t block);
+void AddReadBeforeDepExtents(Vertex* src,
+                             Vertex::Index dst,
+                             const std::vector<Extent>& extents);
+
+void DropWriteBeforeDeps(Vertex::EdgeMap* edge_map);
+
+// For each node N in graph, drop all edges N->|index|.
+void DropIncomingEdgesTo(Graph* graph, Vertex::Index index);
+
 // block must either be the next block in the last extent or a block
 // in the next extent. This function will not handle inserting block
 // into an arbitrary place in the extents.
 void AppendBlockToExtents(std::vector<Extent>* extents, uint64_t block);
 
+// Get/SetElement are intentionally overloaded so that templated functions
+// can accept either type of collection of Extents.
+Extent GetElement(const std::vector<Extent>& collection, size_t index);
+Extent GetElement(
+    const google::protobuf::RepeatedPtrField<Extent>& collection,
+    size_t index);
+
+template<typename T>
+uint64_t BlocksInExtents(const T& collection) {
+  uint64_t ret = 0;
+  for (size_t i = 0; i < static_cast<size_t>(collection.size()); ++i) {
+    ret += GetElement(collection, i).num_blocks();
+  }
+  return ret;
+}
+
+void DumpGraph(const Graph& graph);
+
 }  // namespace graph_utils
 
 }  // namespace chromeos_update_engine
 
 #endif  // CHROMEOS_PLATFORM_UPDATE_ENGINE_GRAPH_UTILS_H__