Add ProtoStreamWriterInterface and implement forwarding writer. (#849)

cartographer/io/in_memory_proto_stream.cc

@@ -16,9 +16,18 @@
 
 #include "cartographer/io/in_memory_proto_stream.h"
 
+#include "glog/logging.h"
+
 namespace cartographer {
 namespace io {
 
+void ForwardingProtoStreamWriter::WriteProto(
+    const google::protobuf::Message& proto) {
+  CHECK(writer_callback_(&proto));
+}
+
+bool ForwardingProtoStreamWriter::Close() { return writer_callback_(nullptr); }
+
 bool InMemoryProtoStreamReader::ReadProto(google::protobuf::Message* proto) {
   if (eof()) return false;
   proto->CopyFrom(*map_chunks_.front());

cartographer/io/in_memory_proto_stream.h

@@ -27,6 +27,26 @@
 namespace cartographer {
 namespace io {
 
+class ForwardingProtoStreamWriter
+    : public cartographer::io::ProtoStreamWriterInterface {
+ public:
+  // A callback that is invoked anytime 'WriteProto()' is called on the
+  // 'ForwardingProtoStreamWriter'. When 'Close()' is called on the
+  // 'ForwardingProtoStreamWriter' the callback is invoked with a 'nullptr'.
+  using WriterCallback =
+      std::function<bool(const google::protobuf::Message* proto)>;
+
+  explicit ForwardingProtoStreamWriter(WriterCallback writer_callback)
+      : writer_callback_(writer_callback) {}
+  ~ForwardingProtoStreamWriter() = default;
+
+  void WriteProto(const google::protobuf::Message& proto) override;
+  bool Close() override;
+
+ private:
+  WriterCallback writer_callback_;
+};
+
 class InMemoryProtoStreamReader
     : public cartographer::io::ProtoStreamReaderInterface {
  public:

cartographer/io/proto_stream.h

@@ -32,7 +32,7 @@ namespace io {
 //
 // TODO(whess): Compress the file instead of individual messages for better
 // compression performance? Should we use LZ4?
-class ProtoStreamWriter {
+class ProtoStreamWriter : public ProtoStreamWriterInterface {
  public:
   ProtoStreamWriter(const std::string& filename);
   ~ProtoStreamWriter() = default;
@@ -40,11 +40,8 @@ class ProtoStreamWriter {
   ProtoStreamWriter(const ProtoStreamWriter&) = delete;
   ProtoStreamWriter& operator=(const ProtoStreamWriter&) = delete;
 
-  // Serializes, compressed and writes the 'proto' to the file.
-  void WriteProto(const google::protobuf::Message& proto);
-
-  // This should be called to check whether writing was successful.
-  bool Close();
+  void WriteProto(const google::protobuf::Message& proto) override;
+  bool Close() override;
 
  private:
   void Write(const std::string& uncompressed_data);

cartographer/io/proto_stream_interface.h

@@ -23,6 +23,18 @@
 namespace cartographer {
 namespace io {
 
+// A writer for writing proto messages to a pbstream.
+class ProtoStreamWriterInterface {
+ public:
+  virtual ~ProtoStreamWriterInterface(){};
+
+  // Serializes, compressed and writes the 'proto' to the file.
+  virtual void WriteProto(const google::protobuf::Message& proto) = 0;
+
+  // This should be called to check whether writing was successful.
+  virtual bool Close() = 0;
+};
+
 // A reader of the format produced by ProtoStreamWriter.
 class ProtoStreamReaderInterface {
  public:

cartographer/mapping/map_builder.cc

@@ -168,7 +168,7 @@ std::string MapBuilder::SubmapToProto(
   return "";
 }
 
-void MapBuilder::SerializeState(io::ProtoStreamWriter* const writer) {
+void MapBuilder::SerializeState(io::ProtoStreamWriterInterface* const writer) {
   // We serialize the pose graph followed by all the data referenced in it.
   writer->WriteProto(pose_graph_->ToProto());
   // Next we serialize all submap data.

cartographer/mapping/map_builder.h

@@ -60,7 +60,7 @@ class MapBuilder : public MapBuilderInterface {
   std::string SubmapToProto(const SubmapId& submap_id,
                             proto::SubmapQuery::Response* response) override;
 
-  void SerializeState(io::ProtoStreamWriter* writer) override;
+  void SerializeState(io::ProtoStreamWriterInterface* writer) override;
 
   void LoadMap(io::ProtoStreamReaderInterface* reader) override;
 

cartographer/mapping/map_builder_interface.h

@@ -74,7 +74,7 @@ class MapBuilderInterface {
                                     proto::SubmapQuery::Response* response) = 0;
 
   // Serializes the current state to a proto stream.
-  virtual void SerializeState(io::ProtoStreamWriter* writer) = 0;
+  virtual void SerializeState(io::ProtoStreamWriterInterface* writer) = 0;
 
   // Loads submaps from a proto stream into a new frozen trajectory.
   virtual void LoadMap(io::ProtoStreamReaderInterface* reader) = 0;

cartographer_grpc/client_server_test.cc

@@ -56,7 +56,8 @@ class MockMapBuilder : public cartographer::mapping::MapBuilderInterface {
       SubmapToProto,
       std::string(const cartographer::mapping::SubmapId&,
                   cartographer::mapping::proto::SubmapQuery::Response*));
-  MOCK_METHOD1(SerializeState, void(cartographer::io::ProtoStreamWriter*));
+  MOCK_METHOD1(SerializeState,
+               void(cartographer::io::ProtoStreamWriterInterface*));
   MOCK_METHOD1(LoadMap, void(cartographer::io::ProtoStreamReaderInterface*));
   MOCK_CONST_METHOD0(num_trajectory_builders, int());
   MOCK_METHOD0(pose_graph, PoseGraphInterface*());

cartographer_grpc/mapping/map_builder_stub.cc

@@ -88,7 +88,7 @@ std::string MapBuilderStub::SubmapToProto(
 }
 
 void MapBuilderStub::SerializeState(
-    cartographer::io::ProtoStreamWriter* writer) {
+    cartographer::io::ProtoStreamWriterInterface* writer) {
   LOG(FATAL) << "Not implemented";
 }
 

cartographer_grpc/mapping/map_builder_stub.h

@@ -47,7 +47,8 @@ class MapBuilderStub : public cartographer::mapping::MapBuilderInterface {
   std::string SubmapToProto(
       const cartographer::mapping::SubmapId& submap_id,
       cartographer::mapping::proto::SubmapQuery::Response* response) override;
-  void SerializeState(cartographer::io::ProtoStreamWriter* writer) override;
+  void SerializeState(
+      cartographer::io::ProtoStreamWriterInterface* writer) override;
   void LoadMap(cartographer::io::ProtoStreamReaderInterface* reader) override;
   int num_trajectory_builders() const override;
   cartographer::mapping::PoseGraphInterface* pose_graph() override;