Use pass by reference for const auto in for loop. (#9811)

src/ray/common/task/scheduling_resources.cc

@@ -305,7 +305,7 @@ const std::string ResourceSet::ToString() const {
 
 const std::unordered_map<std::string, double> ResourceSet::GetResourceMap() const {
   std::unordered_map<std::string, double> result;
-  for (const auto resource_pair : resource_capacity_) {
+  for (const auto &resource_pair : resource_capacity_) {
     result[resource_pair.first] = resource_pair.second.ToDouble();
   }
   return result;

src/ray/gcs/test/redis_actor_info_accessor_test.cc

@@ -45,7 +45,7 @@ class ActorInfoAccessorTest : public AccessorTestBase<ActorID, ActorTableData> {
   }
 
   void GenCheckpointData() {
-    for (const auto item : id_to_data_) {
+    for (const auto &item : id_to_data_) {
       const ActorID &id = item.first;
       ActorCheckpointList checkpoints;
       for (size_t i = 0; i < checkpoint_number_; ++i) {

src/ray/raylet/node_manager.cc

@@ -3589,7 +3589,7 @@ void NodeManager::FlushObjectsToFree() {
 void NodeManager::HandleGetNodeStats(const rpc::GetNodeStatsRequest &node_stats_request,
                                      rpc::GetNodeStatsReply *reply,
                                      rpc::SendReplyCallback send_reply_callback) {
-  for (const auto task : local_queues_.GetTasks(TaskState::INFEASIBLE)) {
+  for (const auto &task : local_queues_.GetTasks(TaskState::INFEASIBLE)) {
     if (task.GetTaskSpecification().IsActorCreationTask()) {
       auto infeasible_task = reply->add_infeasible_tasks();
       infeasible_task->ParseFromString(task.GetTaskSpecification().Serialize());
@@ -3597,7 +3597,7 @@ void NodeManager::HandleGetNodeStats(const rpc::GetNodeStatsRequest &node_stats_
   }
   // Report tasks that are not scheduled because
   // resources are occupied by other actors/tasks.
-  for (const auto task : local_queues_.GetTasks(TaskState::READY)) {
+  for (const auto &task : local_queues_.GetTasks(TaskState::READY)) {
     if (task.GetTaskSpecification().IsActorCreationTask()) {
       auto ready_task = reply->add_ready_tasks();
       ready_task->ParseFromString(task.GetTaskSpecification().Serialize());

src/ray/raylet/scheduling/cluster_resource_scheduler.cc

@@ -329,7 +329,7 @@ TaskResourceInstances NodeResourceInstances::GetAvailableResourceInstances() {
     task_resources.predefined_resources[i] = this->predefined_resources[i].available;
   }
 
-  for (const auto it : this->custom_resources) {
+  for (const auto &it : this->custom_resources) {
     task_resources.custom_resources.emplace(it.first, it.second.available);
   }
 
@@ -365,8 +365,8 @@ bool TaskResourceInstances::IsEmpty() const {
     }
   }
 
-  for (const auto custom_resource : custom_resources) {
-    for (const auto custom_resource_instances : custom_resource.second) {
+  for (const auto &custom_resource : custom_resources) {
+    for (const auto &custom_resource_instances : custom_resource.second) {
       if (custom_resource_instances != 0) {
         return false;
       }
@@ -526,7 +526,7 @@ int64_t ClusterResourceScheduler::IsSchedulable(const TaskRequest &task_req,
   }
 
   // Now check custom resources.
-  for (const auto task_req_custom_resource : task_req.custom_resources) {
+  for (const auto &task_req_custom_resource : task_req.custom_resources) {
     auto it = resources.custom_resources.find(task_req_custom_resource.id);
 
     if (it == resources.custom_resources.end()) {
@@ -1038,7 +1038,7 @@ void ClusterResourceScheduler::UpdateLocalAvailableResourcesFromResourceInstance
     auto it = local_resources_.custom_resources.find(custom_resource.first);
     if (it != local_resources_.custom_resources.end()) {
       custom_resource.second.available = 0;
-      for (const auto available : it->second.available) {
+      for (const auto &available : it->second.available) {
         custom_resource.second.available += available;
       }
     }
@@ -1053,7 +1053,7 @@ void ClusterResourceScheduler::FreeTaskResourceInstances(
                                   &local_resources_.predefined_resources[i]);
   }
 
-  for (const auto task_allocation_custom_resource : task_allocation->custom_resources) {
+  for (const auto &task_allocation_custom_resource : task_allocation->custom_resources) {
     auto it =
         local_resources_.custom_resources.find(task_allocation_custom_resource.first);
     if (it != local_resources_.custom_resources.end()) {

src/ray/stats/stats_test.cc

@@ -43,7 +43,7 @@ class MockExporter : public opencensus::stats::StatsExporter::Handler {
 
       ASSERT_EQ("current_worker", descriptor.name());
       ASSERT_EQ(opencensus::stats::ViewData::Type::kDouble, view_data.type());
-      for (const auto row : view_data.double_data()) {
+      for (const auto &row : view_data.double_data()) {
         for (size_t i = 0; i < descriptor.columns().size(); ++i) {
           if (descriptor.columns()[i].name() == "WorkerPidKey") {
             ASSERT_EQ("1000", row.first[i]);