improve how deletes are read by avoiding temporary object creation (#305

)

improve how deletes are read by avoiding temporary object creation

keyvi/include/keyvi/index/internal/read_only_segment.h

@@ -260,11 +260,13 @@ class ReadOnlySegment {
  deleted_t deleted_keys;
  std::ifstream deleted_keys_stream(filename, std::ios::binary);
  if (deleted_keys_stream.good()) {
- std::stringstream buffer;
- buffer << deleted_keys_stream.rdbuf();
-
+ std::string buffer;
+ deleted_keys_stream.seekg(0, std::ios::end);
+ buffer.resize(deleted_keys_stream.tellg());
+ deleted_keys_stream.seekg(0, std::ios::beg);
+ deleted_keys_stream.read(&buffer[0], buffer.size());
  msgpack::unpacked unpacked_object;
- msgpack::unpack(unpacked_object, buffer.str().data(), buffer.str().size());
+ msgpack::unpack(unpacked_object, buffer.data(), buffer.size());
  unpacked_object.get().convert(deleted_keys);
  }
  return deleted_keys;