Cleanup: cleaning up .first/.second [source/common/config] (#12468)

This is the second PR to this #12354. This time is in the common/config submodule.

Signed-off-by: Yifan Yang <needyyang@google.com>

source/common/config/delta_subscription_state.cc

@@ -124,16 +124,16 @@ DeltaSubscriptionState::getNextRequestAckless() {
     // initial_resource_versions "must be populated for first request in a stream".
     // Also, since this might be a new server, we must explicitly state *all* of our subscription
     // interest.
-    for (auto const& resource : resource_versions_) {
+    for (auto const& [resource_name, resource_version] : resource_versions_) {
       // Populate initial_resource_versions with the resource versions we currently have.
       // Resources we are interested in, but are still waiting to get any version of from the
       // server, do not belong in initial_resource_versions. (But do belong in new subscriptions!)
-      if (!resource.second.waitingForServer()) {
-        (*request.mutable_initial_resource_versions())[resource.first] = resource.second.version();
+      if (!resource_version.waitingForServer()) {
+        (*request.mutable_initial_resource_versions())[resource_name] = resource_version.version();
       }
       // As mentioned above, fill resource_names_subscribe with everything, including names we
       // have yet to receive any resource for.
-      names_added_.insert(resource.first);
+      names_added_.insert(resource_name);
     }
     names_removed_.clear();
   }

source/common/config/metadata.h

@@ -116,10 +116,11 @@ template <typename factoryClass> class TypedMetadataImpl : public TypedMetadata
    */
   void populateFrom(const envoy::config::core::v3::Metadata& metadata) {
     auto& data_by_key = metadata.filter_metadata();
-    for (const auto& it : Registry::FactoryRegistry<factoryClass>::factories()) {
-      const auto& meta_iter = data_by_key.find(it.first);
+    for (const auto& [factory_name, factory] :
+         Registry::FactoryRegistry<factoryClass>::factories()) {
+      const auto& meta_iter = data_by_key.find(factory_name);
       if (meta_iter != data_by_key.end()) {
-        data_[it.second->name()] = it.second->parse(meta_iter->second);
+        data_[factory->name()] = factory->parse(meta_iter->second);
       }
     }
   }

source/common/config/new_grpc_mux_impl.cc

@@ -73,8 +73,8 @@ void NewGrpcMuxImpl::onDiscoveryResponse(
 }
 
 void NewGrpcMuxImpl::onStreamEstablished() {
-  for (auto& sub : subscriptions_) {
-    sub.second->sub_state_.markStreamFresh();
+  for (auto& [type_url, subscription] : subscriptions_) {
+    subscription->sub_state_.markStreamFresh();
   }
   trySendDiscoveryRequests();
 }
@@ -88,8 +88,8 @@ void NewGrpcMuxImpl::onEstablishmentFailure() {
   absl::flat_hash_map<std::string, DeltaSubscriptionState*> all_subscribed;
   absl::flat_hash_map<std::string, DeltaSubscriptionState*> already_called;
   do {
-    for (auto& sub : subscriptions_) {
-      all_subscribed[sub.first] = &sub.second->sub_state_;
+    for (auto& [type_url, subscription] : subscriptions_) {
+      all_subscribed[type_url] = &subscription->sub_state_;
     }
     for (auto& sub : all_subscribed) {
       if (already_called.insert(sub).second) { // insert succeeded ==> not already called

source/common/config/type_to_endpoint.cc

@@ -185,12 +185,11 @@ TypeUrlToVersionedServiceMap* buildTypeUrlToServiceMap() {
                }},
            }},
        }) {
-    for (const auto& registered_service : registered) {
-      const TypeUrl resource_type_url = getResourceTypeUrl(registered_service.first);
+    for (const auto& [registered_service_name, registered_service_info] : registered) {
+      const TypeUrl resource_type_url = getResourceTypeUrl(registered_service_name);
       VersionedService& service = (*type_url_to_versioned_service_map)[resource_type_url];
 
-      for (const auto& versioned_service_name : registered_service.second.names_) {
-        const ServiceName& service_name = versioned_service_name.second;
+      for (const auto& [transport_api_version, service_name] : registered_service_info.names_) {
         const auto* service_desc =
             Protobuf::DescriptorPool::generated_pool()->FindServiceByName(service_name);
         ASSERT(service_desc != nullptr, fmt::format("{} missing", service_name));
@@ -200,7 +199,6 @@ TypeUrlToVersionedServiceMap* buildTypeUrlToServiceMap() {
         // services don't implement all, e.g. VHDS doesn't support SotW or REST.
         for (int method_index = 0; method_index < service_desc->method_count(); ++method_index) {
           const auto& method_desc = *service_desc->method(method_index);
-          const auto transport_api_version = versioned_service_name.first;
           if (absl::StartsWith(method_desc.name(), "Stream")) {
             service.sotw_grpc_.methods_[transport_api_version] = method_desc.full_name();
           } else if (absl::StartsWith(method_desc.name(), "Delta")) {

source/common/config/watch_map.cc

@@ -181,28 +181,27 @@ void WatchMap::onConfigUpdate(
   }
 
   // We just bundled up the updates into nice per-watch packages. Now, deliver them.
-  for (const auto& added : per_watch_added) {
-    const Watch* cur_watch = added.first;
+  for (const auto& [cur_watch, resource_to_add] : per_watch_added) {
     if (deferred_removed_during_update_->count(cur_watch) > 0) {
       continue;
     }
     const auto removed = per_watch_removed.find(cur_watch);
     if (removed == per_watch_removed.end()) {
       // additions only, no removals
-      cur_watch->callbacks_.onConfigUpdate(added.second, {}, system_version_info);
+      cur_watch->callbacks_.onConfigUpdate(resource_to_add, {}, system_version_info);
     } else {
       // both additions and removals
-      cur_watch->callbacks_.onConfigUpdate(added.second, removed->second, system_version_info);
+      cur_watch->callbacks_.onConfigUpdate(resource_to_add, removed->second, system_version_info);
       // Drop the removals now, so the final removals-only pass won't use them.
       per_watch_removed.erase(removed);
     }
   }
   // Any removals-only updates will not have been picked up in the per_watch_added loop.
-  for (auto& removed : per_watch_removed) {
-    if (deferred_removed_during_update_->count(removed.first) > 0) {
+  for (auto& [cur_watch, resource_to_remove] : per_watch_removed) {
+    if (deferred_removed_during_update_->count(cur_watch) > 0) {
       continue;
     }
-    removed.first->callbacks_.onConfigUpdate({}, removed.second, system_version_info);
+    cur_watch->callbacks_.onConfigUpdate({}, resource_to_remove, system_version_info);
   }
 }