Small performance optimization.

PiperOrigin-RevId: 304322695

Author: tensorflower-gardener

tensorflow_serving/core/aspired_versions_manager.cc

@@ -262,7 +262,7 @@ void AspiredVersionsManager::ProcessAspiredVersionsRequest(
   const std::vector<ServableStateSnapshot<Aspired>> state_snapshots =
       basic_manager_->GetManagedServableStateSnapshots<Aspired>(
           string(servable_name));
-  for (const ServableStateSnapshot<Aspired> state_snapshot : state_snapshots) {
+  for (const ServableStateSnapshot<Aspired>& state_snapshot : state_snapshots) {
     if (state_snapshot.additional_state->is_aspired) {
       current_aspired_versions.insert(state_snapshot.id.version);
     }

tensorflow_serving/model_servers/server.cc

@@ -337,7 +337,7 @@ Status Server::BuildAndStart(const Options& server_options) {
   builder.SetMaxMessageSize(tensorflow::kint32max);
   const std::vector<GrpcChannelArgument> channel_arguments =
       parseGrpcChannelArgs(server_options.grpc_channel_arguments);
-  for (GrpcChannelArgument channel_argument : channel_arguments) {
+  for (const GrpcChannelArgument& channel_argument : channel_arguments) {
     // gRPC accept arguments of two types, int and string. We will attempt to
     // parse each arg as int and pass it on as such if successful. Otherwise we
     // will pass it as a string. gRPC will log arguments that were not accepted.

tensorflow_serving/servables/tensorflow/predict_util.cc

@@ -48,7 +48,7 @@ Status VerifySignature(const SignatureDef& signature) {
 template <typename T>
 std::set<string> GetMapKeys(const T& proto_map) {
   std::set<string> keys;
-  for (auto it : proto_map) {
+  for (const auto& it : proto_map) {
     keys.insert(it.first);
   }
   return keys;

tensorflow_serving/util/net_http/client/testing/evhttp_echo_client.cc

@@ -43,7 +43,7 @@ bool SendRequest(const char* url) {
   std::cout << "Response received: " << std::endl
             << "Status: " << response.status << std::endl;
 
-  for (auto keyval : response.headers) {
+  for (const auto& keyval : response.headers) {
     std::cout << keyval.first << " : " << keyval.second << std::endl;
   }