[xDS] remove unnecessary string from XdsConfig struct (#35503)

I realized that this field wasn't actually necessary, since the string is already present in the map key.

Closes #35503

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/35503 from markdroth:xds_config_remove_cluster_name 94d5edc133
PiperOrigin-RevId: 597375018

src/core/ext/filters/client_channel/lb_policy/xds/cds.cc

@@ -404,7 +404,7 @@ absl::Status CdsLb::UpdateLocked(UpdateArgs args) {
             old_cluster_config, *new_cluster_config, endpoint_config);
         // Populate addresses and resolution_note for child policy.
         update_args.addresses = std::make_shared<PriorityEndpointIterator>(
-            new_cluster_config->cluster_name, endpoint_config.endpoints,
+            cluster_name_, endpoint_config.endpoints,
             child_name_state_.priority_child_numbers);
         update_args.resolution_note = endpoint_config.resolution_note;
         // Construct child policy config.
@@ -476,8 +476,7 @@ CdsLb::ChildNameState CdsLb::ComputeChildNames(
       locality_child_map;
   std::map<size_t, std::set<XdsLocalityName*, XdsLocalityName::Less>>
       child_locality_map;
-  if (old_cluster != nullptr &&
-      old_cluster->cluster_name == new_cluster.cluster_name) {
+  if (old_cluster != nullptr) {
     auto* old_endpoint_config =
         absl::get_if<XdsConfig::ClusterConfig::EndpointConfig>(
             &old_cluster->children);
@@ -579,9 +578,8 @@ Json CdsLb::CreateChildPolicyConfigForLeafCluster(
       GetUpdatePriorityList(endpoint_config.endpoints.get());
   for (size_t priority = 0; priority < priority_list.size(); ++priority) {
     // Add priority entry, with the appropriate child name.
-    std::string child_name =
-        MakeChildPolicyName(new_cluster.cluster_name,
-                            child_name_state_.priority_child_numbers[priority]);
+    std::string child_name = MakeChildPolicyName(
+        cluster_name_, child_name_state_.priority_child_numbers[priority]);
     priority_priorities.emplace_back(Json::FromString(child_name));
     Json::Object child_config = {{"config", xds_lb_policy}};
     if (!is_logical_dns) {
@@ -600,7 +598,7 @@ Json CdsLb::CreateChildPolicyConfigForLeafCluster(
   Json xds_override_host_policy = Json::FromArray({Json::FromObject({
       {"xds_override_host_experimental",
        Json::FromObject({
-           {"clusterName", Json::FromString(new_cluster.cluster_name)},
+           {"clusterName", Json::FromString(cluster_name_)},
            {"childPolicy", std::move(priority_policy)},
        })},
   })});
@@ -608,7 +606,7 @@ Json CdsLb::CreateChildPolicyConfigForLeafCluster(
   Json xds_cluster_impl_policy = Json::FromArray({Json::FromObject({
       {"xds_cluster_impl_experimental",
        Json::FromObject({
-           {"clusterName", Json::FromString(new_cluster.cluster_name)},
+           {"clusterName", Json::FromString(cluster_name_)},
            {"childPolicy", std::move(xds_override_host_policy)},
        })},
   })});

src/core/ext/filters/client_channel/resolver/xds/xds_dependency_manager.cc

@@ -41,19 +41,17 @@ constexpr int kMaxXdsAggregateClusterRecursionDepth = 16;
 //
 
 XdsDependencyManager::XdsConfig::ClusterConfig::ClusterConfig(
-    std::string cluster_name, std::shared_ptr<const XdsClusterResource> cluster,
+    std::shared_ptr<const XdsClusterResource> cluster,
     std::shared_ptr<const XdsEndpointResource> endpoints,
     std::string resolution_note)
-    : cluster_name(std::move(cluster_name)),
-      cluster(std::move(cluster)),
+    : cluster(std::move(cluster)),
       children(absl::in_place_type_t<EndpointConfig>(), std::move(endpoints),
                std::move(resolution_note)) {}
 
 XdsDependencyManager::XdsConfig::ClusterConfig::ClusterConfig(
-    std::string cluster_name, std::shared_ptr<const XdsClusterResource> cluster,
+    std::shared_ptr<const XdsClusterResource> cluster,
     std::vector<absl::string_view> leaf_clusters)
-    : cluster_name(std::move(cluster_name)),
-      cluster(std::move(cluster)),
+    : cluster(std::move(cluster)),
       children(absl::in_place_type_t<AggregateConfig>(),
                std::move(leaf_clusters)) {}
 
@@ -75,9 +73,6 @@ std::string XdsDependencyManager::XdsConfig::ToString() const {
     } else {
       parts.push_back(
           absl::StrCat("      {\n"
-                       "        name: \"",
-                       p.second->cluster_name,
-                       "\"\n"
                        "        cluster: {",
                        p.second->cluster->ToString(), "}\n"));
       Match(
@@ -794,8 +789,7 @@ bool XdsDependencyManager::PopulateClusterConfigMap(
           return false;
         }
         // Populate cluster config.
-        cluster_config.emplace(std::string(name), *state.update,
-                               eds_state.update.endpoints,
+        cluster_config.emplace(*state.update, eds_state.update.endpoints,
                                eds_state.update.resolution_note);
         if (leaf_clusters != nullptr) (*leaf_clusters)->push_back(name);
         return true;
@@ -845,8 +839,7 @@ bool XdsDependencyManager::PopulateClusterConfigMap(
           return false;
         }
         // Populate cluster config.
-        cluster_config.emplace(std::string(name), *state.update,
-                               dns_state.update.endpoints,
+        cluster_config.emplace(*state.update, dns_state.update.endpoints,
                                dns_state.update.resolution_note);
         if (leaf_clusters != nullptr) (*leaf_clusters)->push_back(name);
         return true;
@@ -901,8 +894,7 @@ bool XdsDependencyManager::PopulateClusterConfigMap(
         // at the root of the tree, because we need to make sure the list
         // of underlying cluster names stays alive so that the leaf cluster
         // list of the root aggregate cluster can point to those strings.
-        aggregate_cluster_config.emplace(std::string(name),
-                                         std::move(cluster_resource),
+        aggregate_cluster_config.emplace(std::move(cluster_resource),
                                          std::move(*child_leaf_clusters));
         return have_all_resources;
       });

src/core/ext/filters/client_channel/resolver/xds/xds_dependency_manager.h

@@ -39,7 +39,7 @@ class XdsDependencyManager : public RefCounted<XdsDependencyManager>,
                              public Orphanable {
  public:
   struct XdsConfig : public RefCounted<XdsConfig> {
-    // Listener resource.
+    // Listener resource.  Always non-null.
     std::shared_ptr<const XdsListenerResource> listener;
     // RouteConfig resource.  Will be populated even if RouteConfig is
     // inlined into the Listener resource.
@@ -47,15 +47,11 @@ class XdsDependencyManager : public RefCounted<XdsDependencyManager>,
     // Virtual host.  Points into route_config.  Will always be non-null.
     const XdsRouteConfigResource::VirtualHost* virtual_host;
 
-    // Cluster map.  A cluster will have a non-OK status if either
-    // (a) there was an error and we did not already have a valid
-    // resource or (b) the resource does not exist.
     struct ClusterConfig {
-      // Cluster name and resource.
-      std::string cluster_name;
+      // Cluster resource.  Always non-null.
       std::shared_ptr<const XdsClusterResource> cluster;
-      // Endpoint info.  If there was an error, endpoints will be null
-      // and resolution_note will be set.  Not used for aggregate clusters.
+      // Endpoint info for EDS and LOGICAL_DNS clusters.  If there was an
+      // error, endpoints will be null and resolution_note will be set.
       struct EndpointConfig {
         std::shared_ptr<const XdsEndpointResource> endpoints;
         std::string resolution_note;
@@ -82,20 +78,20 @@ class XdsDependencyManager : public RefCounted<XdsDependencyManager>,
       absl::variant<EndpointConfig, AggregateConfig> children;
 
       // Ctor for leaf clusters.
-      ClusterConfig(std::string cluster_name,
-                    std::shared_ptr<const XdsClusterResource> cluster,
+      ClusterConfig(std::shared_ptr<const XdsClusterResource> cluster,
                     std::shared_ptr<const XdsEndpointResource> endpoints,
                     std::string resolution_note);
       // Ctor for aggregate clusters.
-      ClusterConfig(std::string cluster_name,
-                    std::shared_ptr<const XdsClusterResource> cluster,
+      ClusterConfig(std::shared_ptr<const XdsClusterResource> cluster,
                     std::vector<absl::string_view> leaf_clusters);
 
       bool operator==(const ClusterConfig& other) const {
-        return cluster_name == other.cluster_name && cluster == other.cluster &&
-               children == other.children;
+        return cluster == other.cluster && children == other.children;
       }
     };
+    // Cluster map.  A cluster will have a non-OK status if either
+    // (a) there was an error and we did not already have a valid
+    // resource or (b) the resource does not exist.
     absl::flat_hash_map<std::string, absl::StatusOr<ClusterConfig>> clusters;
 
     std::string ToString() const;

test/core/client_channel/lb_policy/xds_override_host_test.cc

@@ -72,8 +72,8 @@ class XdsOverrideHostTest : public LoadBalancingPolicyTest {
       cluster_resource->connection_idle_timeout = *connection_idle_timeout;
     }
     auto xds_config = MakeRefCounted<XdsDependencyManager::XdsConfig>();
-    xds_config->clusters[cluster_name].emplace(
-        cluster_name, std::move(cluster_resource), nullptr, "");
+    xds_config->clusters[std::move(cluster_name)].emplace(
+        std::move(cluster_resource), nullptr, "");
     return xds_config;
   }