[misc] add `final` on a bunch of classes that should not have subclasses (#36212)

Closes #36212

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/36212 from markdroth:subclass_final 7626ccd691
PiperOrigin-RevId: 620990528

src/core/client_channel/client_channel_channelz.h

@@ -41,7 +41,7 @@
 namespace grpc_core {
 namespace channelz {
 
-class SubchannelNode : public BaseNode {
+class SubchannelNode final : public BaseNode {
  public:
   SubchannelNode(std::string target_address, size_t channel_tracer_max_nodes);
   ~SubchannelNode() override;

src/core/client_channel/client_channel_filter.cc

@@ -191,7 +191,7 @@ class ClientChannelFilter::CallData {
   RefCountedPtr<DynamicFilters> dynamic_filters_;
 };
 
-class ClientChannelFilter::FilterBasedCallData
+class ClientChannelFilter::FilterBasedCallData final
     : public ClientChannelFilter::CallData {
  public:
   static grpc_error_handle Init(grpc_call_element* elem,
@@ -311,7 +311,7 @@ class ClientChannelFilter::FilterBasedCallData
   grpc_error_handle cancel_error_;
 };
 
-class ClientChannelFilter::PromiseBasedCallData
+class ClientChannelFilter::PromiseBasedCallData final
     : public ClientChannelFilter::CallData {
  public:
   explicit PromiseBasedCallData(ClientChannelFilter* chand) : chand_(chand) {}
@@ -451,7 +451,7 @@ ClientChannelServiceConfigCallData* GetServiceConfigCallData(
       context[GRPC_CONTEXT_SERVICE_CONFIG_CALL_DATA].value);
 }
 
-class DynamicTerminationFilter {
+class DynamicTerminationFilter final {
  public:
   class CallData;
 
@@ -496,7 +496,7 @@ class DynamicTerminationFilter {
   ClientChannelFilter* chand_;
 };
 
-class DynamicTerminationFilter::CallData {
+class DynamicTerminationFilter::CallData final {
  public:
   static grpc_error_handle Init(grpc_call_element* elem,
                                 const grpc_call_element_args* args) {
@@ -593,7 +593,7 @@ const grpc_channel_filter DynamicTerminationFilter::kFilterVtable = {
 // ClientChannelFilter::ResolverResultHandler
 //
 
-class ClientChannelFilter::ResolverResultHandler
+class ClientChannelFilter::ResolverResultHandler final
     : public Resolver::ResultHandler {
  public:
   explicit ResolverResultHandler(ClientChannelFilter* chand) : chand_(chand) {
@@ -628,7 +628,8 @@ class ClientChannelFilter::ResolverResultHandler
 // underlying subchannel is shared between channels, this wrapper will only
 // be used within one channel, so it will always be synchronized by the
 // control plane work_serializer.
-class ClientChannelFilter::SubchannelWrapper : public SubchannelInterface {
+class ClientChannelFilter::SubchannelWrapper final
+    : public SubchannelInterface {
  public:
   SubchannelWrapper(ClientChannelFilter* chand,
                     RefCountedPtr<Subchannel> subchannel)
@@ -771,7 +772,8 @@ class ClientChannelFilter::SubchannelWrapper : public SubchannelInterface {
   // This class handles things like hopping into the WorkSerializer
   // before passing notifications to the LB policy and propagating
   // keepalive information betwen subchannels.
-  class WatcherWrapper : public Subchannel::ConnectivityStateWatcherInterface {
+  class WatcherWrapper final
+      : public Subchannel::ConnectivityStateWatcherInterface {
    public:
     WatcherWrapper(
         std::unique_ptr<SubchannelInterface::ConnectivityStateWatcherInterface>
@@ -1024,7 +1026,7 @@ void ClientChannelFilter::ExternalConnectivityWatcher::RemoveWatcherLocked() {
 // ClientChannelFilter::ConnectivityWatcherAdder
 //
 
-class ClientChannelFilter::ConnectivityWatcherAdder {
+class ClientChannelFilter::ConnectivityWatcherAdder final {
  public:
   ConnectivityWatcherAdder(
       ClientChannelFilter* chand, grpc_connectivity_state initial_state,
@@ -1057,7 +1059,7 @@ class ClientChannelFilter::ConnectivityWatcherAdder {
 // ClientChannelFilter::ConnectivityWatcherRemover
 //
 
-class ClientChannelFilter::ConnectivityWatcherRemover {
+class ClientChannelFilter::ConnectivityWatcherRemover final {
  public:
   ConnectivityWatcherRemover(ClientChannelFilter* chand,
                              AsyncConnectivityStateWatcherInterface* watcher)
@@ -1087,7 +1089,7 @@ class ClientChannelFilter::ConnectivityWatcherRemover {
 // ClientChannelFilter::ClientChannelControlHelper
 //
 
-class ClientChannelFilter::ClientChannelControlHelper
+class ClientChannelFilter::ClientChannelControlHelper final
     : public LoadBalancingPolicy::ChannelControlHelper {
  public:
   explicit ClientChannelControlHelper(ClientChannelFilter* chand)
@@ -2478,7 +2480,8 @@ void ClientChannelFilter::FilterBasedCallData::PendingBatchesResume() {
 
 // A class to handle the call combiner cancellation callback for a
 // queued pick.
-class ClientChannelFilter::FilterBasedCallData::ResolverQueuedCallCanceller {
+class ClientChannelFilter::FilterBasedCallData::ResolverQueuedCallCanceller
+    final {
  public:
   explicit ResolverQueuedCallCanceller(FilterBasedCallData* calld)
       : calld_(calld) {
@@ -2599,7 +2602,7 @@ void ClientChannelFilter::FilterBasedCallData::
 // ClientChannelFilter::LoadBalancedCall::LbCallState
 //
 
-class ClientChannelFilter::LoadBalancedCall::LbCallState
+class ClientChannelFilter::LoadBalancedCall::LbCallState final
     : public ClientChannelLbCallState {
  public:
   explicit LbCallState(LoadBalancedCall* lb_call) : lb_call_(lb_call) {}
@@ -2621,7 +2624,7 @@ class ClientChannelFilter::LoadBalancedCall::LbCallState
 // ClientChannelFilter::LoadBalancedCall::Metadata
 //
 
-class ClientChannelFilter::LoadBalancedCall::Metadata
+class ClientChannelFilter::LoadBalancedCall::Metadata final
     : public LoadBalancingPolicy::MetadataInterface {
  public:
   explicit Metadata(grpc_metadata_batch* batch) : batch_(batch) {}
@@ -2661,7 +2664,7 @@ class ClientChannelFilter::LoadBalancedCall::Metadata
   }
 
  private:
-  class Encoder {
+  class Encoder final {
    public:
     void Encode(const Slice& key, const Slice& value) {
       out_.emplace_back(std::string(key.as_string_view()),
@@ -2714,7 +2717,7 @@ ClientChannelFilter::LoadBalancedCall::LbCallState::GetCallAttemptTracer()
 // ClientChannelFilter::LoadBalancedCall::BackendMetricAccessor
 //
 
-class ClientChannelFilter::LoadBalancedCall::BackendMetricAccessor
+class ClientChannelFilter::LoadBalancedCall::BackendMetricAccessor final
     : public LoadBalancingPolicy::BackendMetricAccessor {
  public:
   BackendMetricAccessor(LoadBalancedCall* lb_call,
@@ -2735,7 +2738,7 @@ class ClientChannelFilter::LoadBalancedCall::BackendMetricAccessor
   }
 
  private:
-  class BackendMetricAllocator : public BackendMetricAllocatorInterface {
+  class BackendMetricAllocator final : public BackendMetricAllocatorInterface {
    public:
     explicit BackendMetricAllocator(Arena* arena) : arena_(arena) {}
 
@@ -3390,7 +3393,8 @@ void ClientChannelFilter::FilterBasedLoadBalancedCall::
 // because there may be multiple LB picks happening in parallel.
 // Instead, we will probably need to maintain a list in the CallData
 // object of pending LB picks to be cancelled when the closure runs.
-class ClientChannelFilter::FilterBasedLoadBalancedCall::LbQueuedCallCanceller {
+class ClientChannelFilter::FilterBasedLoadBalancedCall::LbQueuedCallCanceller
+    final {
  public:
   explicit LbQueuedCallCanceller(
       RefCountedPtr<FilterBasedLoadBalancedCall> lb_call)

src/core/client_channel/client_channel_filter.h

@@ -101,7 +101,7 @@
 
 namespace grpc_core {
 
-class ClientChannelFilter {
+class ClientChannelFilter final {
  public:
   static const grpc_channel_filter kFilterVtableWithPromises;
   static const grpc_channel_filter kFilterVtableWithoutPromises;
@@ -184,7 +184,8 @@ class ClientChannelFilter {
 
   // Represents a pending connectivity callback from an external caller
   // via grpc_client_channel_watch_connectivity_state().
-  class ExternalConnectivityWatcher : public ConnectivityStateWatcherInterface {
+  class ExternalConnectivityWatcher final
+      : public ConnectivityStateWatcherInterface {
    public:
     ExternalConnectivityWatcher(ClientChannelFilter* chand,
                                 grpc_polling_entity pollent,
@@ -469,7 +470,7 @@ class ClientChannelFilter::LoadBalancedCall
   grpc_call_context_element* const call_context_;
 };
 
-class ClientChannelFilter::FilterBasedLoadBalancedCall
+class ClientChannelFilter::FilterBasedLoadBalancedCall final
     : public ClientChannelFilter::LoadBalancedCall {
  public:
   // If on_call_destruction_complete is non-null, then it will be
@@ -595,7 +596,7 @@ class ClientChannelFilter::FilterBasedLoadBalancedCall
   grpc_transport_stream_op_batch* pending_batches_[MAX_PENDING_BATCHES] = {};
 };
 
-class ClientChannelFilter::PromiseBasedLoadBalancedCall
+class ClientChannelFilter::PromiseBasedLoadBalancedCall final
     : public ClientChannelFilter::LoadBalancedCall {
  public:
   PromiseBasedLoadBalancedCall(ClientChannelFilter* chand,

src/core/client_channel/client_channel_internal.h

@@ -54,7 +54,7 @@ class ClientChannelLbCallState : public LoadBalancingPolicy::CallState {
 };
 
 // Internal type for ServiceConfigCallData.  Handles call commits.
-class ClientChannelServiceConfigCallData : public ServiceConfigCallData {
+class ClientChannelServiceConfigCallData final : public ServiceConfigCallData {
  public:
   ClientChannelServiceConfigCallData(Arena* arena,
                                      grpc_call_context_element* call_context)

src/core/client_channel/client_channel_service_config.h

@@ -41,7 +41,7 @@
 namespace grpc_core {
 namespace internal {
 
-class ClientChannelGlobalParsedConfig
+class ClientChannelGlobalParsedConfig final
     : public ServiceConfigParser::ParsedConfig {
  public:
   RefCountedPtr<LoadBalancingPolicy::Config> parsed_lb_config() const {
@@ -72,7 +72,7 @@ class ClientChannelGlobalParsedConfig
   HealthCheckConfig health_check_config_;
 };
 
-class ClientChannelMethodParsedConfig
+class ClientChannelMethodParsedConfig final
     : public ServiceConfigParser::ParsedConfig {
  public:
   Duration timeout() const { return timeout_; }
@@ -86,7 +86,8 @@ class ClientChannelMethodParsedConfig
   absl::optional<bool> wait_for_ready_;
 };
 
-class ClientChannelServiceConfigParser : public ServiceConfigParser::Parser {
+class ClientChannelServiceConfigParser final
+    : public ServiceConfigParser::Parser {
  public:
   absl::string_view name() const override { return parser_name(); }
 

src/core/client_channel/config_selector.h

@@ -90,7 +90,7 @@ class ConfigSelector : public RefCounted<ConfigSelector> {
 };
 
 // Default ConfigSelector that gets the MethodConfig from the service config.
-class DefaultConfigSelector : public ConfigSelector {
+class DefaultConfigSelector final : public ConfigSelector {
  public:
   explicit DefaultConfigSelector(RefCountedPtr<ServiceConfig> service_config)
       : service_config_(std::move(service_config)) {

src/core/client_channel/dynamic_filters.h

@@ -42,7 +42,7 @@
 
 namespace grpc_core {
 
-class DynamicFilters : public RefCounted<DynamicFilters> {
+class DynamicFilters final : public RefCounted<DynamicFilters> {
  public:
   // Implements the interface of RefCounted<>.
   class Call {

src/core/client_channel/http_proxy_mapper.h

@@ -33,7 +33,7 @@
 
 namespace grpc_core {
 
-class HttpProxyMapper : public ProxyMapperInterface {
+class HttpProxyMapper final : public ProxyMapperInterface {
  public:
   static constexpr char const* kAddressProxyEnvVar = "GRPC_ADDRESS_HTTP_PROXY";
   static constexpr char const* kAddressProxyEnabledAddressesEnvVar =

src/core/client_channel/retry_filter.h

@@ -48,7 +48,7 @@ extern grpc_core::TraceFlag grpc_retry_trace;
 
 namespace grpc_core {
 
-class RetryFilter {
+class RetryFilter final {
  public:
   static const grpc_channel_filter kVtable;
 

src/core/client_channel/retry_filter_legacy_call_data.cc

@@ -72,7 +72,7 @@ namespace grpc_core {
 // those refs are not released until the LB call stack is destroyed.
 // When this object is destroyed, it will invoke the
 // on_call_stack_destruction closure from the surface.
-class RetryFilter::LegacyCallData::CallStackDestructionBarrier
+class RetryFilter::LegacyCallData::CallStackDestructionBarrier final
     : public RefCounted<CallStackDestructionBarrier, PolymorphicRefCount,
                         UnrefCallDtor> {
  public:

src/core/client_channel/retry_filter_legacy_call_data.h

@@ -54,7 +54,7 @@
 
 namespace grpc_core {
 
-class RetryFilter::LegacyCallData {
+class RetryFilter::LegacyCallData final {
  public:
   static grpc_error_handle Init(grpc_call_element* elem,
                                 const grpc_call_element_args* args);
@@ -78,7 +78,7 @@ class RetryFilter::LegacyCallData {
   };
 
   // State associated with each call attempt.
-  class CallAttempt : public RefCounted<CallAttempt> {
+  class CallAttempt final : public RefCounted<CallAttempt> {
    public:
     CallAttempt(LegacyCallData* calld, bool is_transparent_retry);
     ~CallAttempt() override;
@@ -102,7 +102,7 @@ class RetryFilter::LegacyCallData {
     // structures needed to populate the ops in the batch.
     // We allocate one struct on the arena for each attempt at starting a
     // batch on a given LB call.
-    class BatchData
+    class BatchData final
         : public RefCounted<BatchData, PolymorphicRefCount, UnrefCallDtor> {
      public:
       BatchData(RefCountedPtr<CallAttempt> call_attempt, int refcount,

src/core/client_channel/retry_service_config.h

@@ -40,7 +40,7 @@
 namespace grpc_core {
 namespace internal {
 
-class RetryGlobalConfig : public ServiceConfigParser::ParsedConfig {
+class RetryGlobalConfig final : public ServiceConfigParser::ParsedConfig {
  public:
   uintptr_t max_milli_tokens() const { return max_milli_tokens_; }
   uintptr_t milli_token_ratio() const { return milli_token_ratio_; }
@@ -54,7 +54,7 @@ class RetryGlobalConfig : public ServiceConfigParser::ParsedConfig {
   uintptr_t milli_token_ratio_ = 0;
 };
 
-class RetryMethodConfig : public ServiceConfigParser::ParsedConfig {
+class RetryMethodConfig final : public ServiceConfigParser::ParsedConfig {
  public:
   int max_attempts() const { return max_attempts_; }
   Duration initial_backoff() const { return initial_backoff_; }
@@ -80,7 +80,7 @@ class RetryMethodConfig : public ServiceConfigParser::ParsedConfig {
   absl::optional<Duration> per_attempt_recv_timeout_;
 };
 
-class RetryServiceConfigParser : public ServiceConfigParser::Parser {
+class RetryServiceConfigParser final : public ServiceConfigParser::Parser {
  public:
   absl::string_view name() const override { return parser_name(); }
 

src/core/client_channel/retry_throttle.h

@@ -38,7 +38,8 @@ namespace grpc_core {
 namespace internal {
 
 /// Tracks retry throttling data for an individual server name.
-class ServerRetryThrottleData : public RefCounted<ServerRetryThrottleData> {
+class ServerRetryThrottleData final
+    : public RefCounted<ServerRetryThrottleData> {
  public:
   ServerRetryThrottleData(uintptr_t max_milli_tokens,
                           uintptr_t milli_token_ratio,
@@ -68,7 +69,7 @@ class ServerRetryThrottleData : public RefCounted<ServerRetryThrottleData> {
 };
 
 /// Global map of server name to retry throttle data.
-class ServerRetryThrottleMap {
+class ServerRetryThrottleMap final {
  public:
   static ServerRetryThrottleMap* Get();
 

src/core/client_channel/subchannel.cc

@@ -328,7 +328,7 @@ void SubchannelCall::IncrementRefCount(const DebugLocation& /*location*/,
 // Subchannel::ConnectedSubchannelStateWatcher
 //
 
-class Subchannel::ConnectedSubchannelStateWatcher
+class Subchannel::ConnectedSubchannelStateWatcher final
     : public AsyncConnectivityStateWatcherInterface {
  public:
   // Must be instantiated while holding c->mu.

src/core/client_channel/subchannel.h

@@ -65,7 +65,7 @@ namespace grpc_core {
 
 class SubchannelCall;
 
-class ConnectedSubchannel : public RefCounted<ConnectedSubchannel> {
+class ConnectedSubchannel final : public RefCounted<ConnectedSubchannel> {
  public:
   ConnectedSubchannel(
       grpc_channel_stack* channel_stack, const ChannelArgs& args,
@@ -96,7 +96,7 @@ class ConnectedSubchannel : public RefCounted<ConnectedSubchannel> {
 };
 
 // Implements the interface of RefCounted<>.
-class SubchannelCall {
+class SubchannelCall final {
  public:
   struct Args {
     RefCountedPtr<ConnectedSubchannel> connected_subchannel;
@@ -166,7 +166,7 @@ class SubchannelCall {
 // different from the SubchannelInterface that is exposed to LB policy
 // implementations.  The client channel provides an adaptor class
 // (SubchannelWrapper) that "converts" between the two.
-class Subchannel : public DualRefCounted<Subchannel> {
+class Subchannel final : public DualRefCounted<Subchannel> {
  public:
   // TODO(roth): Once we remove pollset_set, consider whether this can
   // just use the normal AsyncConnectivityStateWatcherInterface API.
@@ -279,7 +279,7 @@ class Subchannel : public DualRefCounted<Subchannel> {
 
   // A linked list of ConnectivityStateWatcherInterfaces that are monitoring
   // the subchannel's state.
-  class ConnectivityStateWatcherList {
+  class ConnectivityStateWatcherList final {
    public:
     explicit ConnectivityStateWatcherList(Subchannel* subchannel)
         : subchannel_(subchannel) {}

src/core/client_channel/subchannel_pool_interface.h

@@ -39,7 +39,7 @@ class Subchannel;
 extern TraceFlag grpc_subchannel_pool_trace;
 
 // A key that can uniquely identify a subchannel.
-class SubchannelKey {
+class SubchannelKey final {
  public:
   SubchannelKey(const grpc_resolved_address& address, const ChannelArgs& args);
 

src/core/client_channel/subchannel_stream_client.h

@@ -61,7 +61,7 @@ namespace grpc_core {
 //
 // Currently, this assumes server-side streaming, but it could be extended
 // to support full bidi streaming if there is a need in the future.
-class SubchannelStreamClient
+class SubchannelStreamClient final
     : public InternallyRefCounted<SubchannelStreamClient> {
  public:
   // Interface implemented by caller.  Thread safety is provided for the
@@ -112,7 +112,7 @@ class SubchannelStreamClient
 
  private:
   // Contains a call to the backend and all the data related to the call.
-  class CallState : public Orphanable {
+  class CallState final : public Orphanable {
    public:
     CallState(RefCountedPtr<SubchannelStreamClient> client,
               grpc_pollset_set* interested_parties);

src/core/ext/xds/certificate_provider_store.h

@@ -46,7 +46,7 @@
 namespace grpc_core {
 
 // Map for xDS based grpc_tls_certificate_provider instances.
-class CertificateProviderStore
+class CertificateProviderStore final
     : public InternallyRefCounted<CertificateProviderStore> {
  public:
   struct PluginDefinition {
@@ -77,7 +77,8 @@ class CertificateProviderStore
  private:
   // A thin wrapper around `grpc_tls_certificate_provider` which allows removing
   // the entry from the CertificateProviderStore when the refcount reaches zero.
-  class CertificateProviderWrapper : public grpc_tls_certificate_provider {
+  class CertificateProviderWrapper final
+      : public grpc_tls_certificate_provider {
    public:
     CertificateProviderWrapper(
         RefCountedPtr<grpc_tls_certificate_provider> certificate_provider,

src/core/ext/xds/file_watcher_certificate_provider_factory.h

@@ -37,10 +37,10 @@
 
 namespace grpc_core {
 
-class FileWatcherCertificateProviderFactory
+class FileWatcherCertificateProviderFactory final
     : public CertificateProviderFactory {
  public:
-  class Config : public CertificateProviderFactory::Config {
+  class Config final : public CertificateProviderFactory::Config {
    public:
     absl::string_view name() const override;
 

src/core/ext/xds/xds_api.h

@@ -48,7 +48,7 @@ class XdsClient;
 // - ADS request/response handling
 // - LRS request/response handling
 // - CSDS response generation
-class XdsApi {
+class XdsApi final {
  public:
   // Interface defined by caller and passed to ParseAdsResponse().
   class AdsResponseParserInterface {

src/core/ext/xds/xds_audit_logger_registry.cc

@@ -39,7 +39,8 @@ namespace {
 
 using experimental::AuditLoggerRegistry;
 
-class StdoutLoggerConfigFactory : public XdsAuditLoggerRegistry::ConfigFactory {
+class StdoutLoggerConfigFactory final
+    : public XdsAuditLoggerRegistry::ConfigFactory {
  public:
   Json::Object ConvertXdsAuditLoggerConfig(
       const XdsResourceType::DecodeContext& /*context*/,

src/core/ext/xds/xds_audit_logger_registry.h

@@ -33,7 +33,7 @@ namespace grpc_core {
 
 // A registry that maintains a set of converters that are able to map xDS
 // RBAC audit logger configuration to gRPC's JSON format.
-class XdsAuditLoggerRegistry {
+class XdsAuditLoggerRegistry final {
  public:
   class ConfigFactory {
    public:

src/core/ext/xds/xds_bootstrap_grpc.cc

@@ -254,7 +254,7 @@ absl::StatusOr<std::unique_ptr<GrpcXdsBootstrap>> GrpcXdsBootstrap::Create(
         "Failed to parse bootstrap JSON string: ", json.status().ToString()));
   }
   // Validate JSON.
-  class XdsJsonArgs : public JsonArgs {
+  class XdsJsonArgs final : public JsonArgs {
    public:
     bool IsEnabled(absl::string_view key) const override {
       if (key == "federation") return XdsFederationEnabled();

src/core/ext/xds/xds_bootstrap_grpc.h

@@ -44,9 +44,9 @@
 
 namespace grpc_core {
 
-class GrpcXdsBootstrap : public XdsBootstrap {
+class GrpcXdsBootstrap final : public XdsBootstrap {
  public:
-  class GrpcNode : public Node {
+  class GrpcNode final : public Node {
    public:
     const std::string& id() const override { return id_; }
     const std::string& cluster() const override { return cluster_; }
@@ -76,7 +76,7 @@ class GrpcXdsBootstrap : public XdsBootstrap {
     Json::Object metadata_;
   };
 
-  class GrpcXdsServer : public XdsServer {
+  class GrpcXdsServer final : public XdsServer {
    public:
     const std::string& server_uri() const override { return server_uri_; }
 
@@ -102,7 +102,7 @@ class GrpcXdsBootstrap : public XdsBootstrap {
     std::set<std::string> server_features_;
   };
 
-  class GrpcAuthority : public Authority {
+  class GrpcAuthority final : public Authority {
    public:
     std::vector<const XdsServer*> servers() const override {
       std::vector<const XdsServer*> servers;

src/core/ext/xds/xds_certificate_provider.cc

@@ -35,7 +35,7 @@ namespace grpc_core {
 
 namespace {
 
-class RootCertificatesWatcher
+class RootCertificatesWatcher final
     : public grpc_tls_certificate_distributor::TlsCertificatesWatcherInterface {
  public:
   // Takes a ref to \a parent instead of a raw pointer since the watcher is
@@ -68,7 +68,7 @@ class RootCertificatesWatcher
   RefCountedPtr<grpc_tls_certificate_distributor> parent_;
 };
 
-class IdentityCertificatesWatcher
+class IdentityCertificatesWatcher final
     : public grpc_tls_certificate_distributor::TlsCertificatesWatcherInterface {
  public:
   // Takes a ref to \a parent instead of a raw pointer since the watcher is

src/core/ext/xds/xds_certificate_provider.h

@@ -42,7 +42,7 @@
 
 namespace grpc_core {
 
-class XdsCertificateProvider : public grpc_tls_certificate_provider {
+class XdsCertificateProvider final : public grpc_tls_certificate_provider {
  public:
   // ctor for client side
   XdsCertificateProvider(

src/core/ext/xds/xds_channel_stack_modifier.h

@@ -39,7 +39,8 @@ namespace grpc_core {
 // XdsChannelStackModifier allows for inserting xDS HTTP filters into the
 // channel stack. It is registered to mutate the `ChannelStackBuilder` object
 // via ChannelInit::Builder::RegisterPostProcessor.
-class XdsChannelStackModifier : public RefCounted<XdsChannelStackModifier> {
+class XdsChannelStackModifier final
+    : public RefCounted<XdsChannelStackModifier> {
  public:
   explicit XdsChannelStackModifier(
       std::vector<const grpc_channel_filter*> filters)

src/core/ext/xds/xds_client.cc

@@ -76,7 +76,7 @@ TraceFlag grpc_xds_client_refcount_trace(false, "xds_client_refcount");
 // An xds call wrapper that can restart a call upon failure. Holds a ref to
 // the xds channel. The template parameter is the kind of wrapped xds call.
 template <typename T>
-class XdsClient::XdsChannel::RetryableCall
+class XdsClient::XdsChannel::RetryableCall final
     : public InternallyRefCounted<RetryableCall<T>> {
  public:
   explicit RetryableCall(WeakRefCountedPtr<XdsChannel> xds_channel);
@@ -114,7 +114,8 @@ class XdsClient::XdsChannel::RetryableCall
 };
 
 // Contains an ADS call to the xds server.
-class XdsClient::XdsChannel::AdsCall : public InternallyRefCounted<AdsCall> {
+class XdsClient::XdsChannel::AdsCall final
+    : public InternallyRefCounted<AdsCall> {
  public:
   // The ctor and dtor should not be used directly.
   explicit AdsCall(RefCountedPtr<RetryableCall<AdsCall>> retryable_call);
@@ -140,7 +141,7 @@ class XdsClient::XdsChannel::AdsCall : public InternallyRefCounted<AdsCall> {
  private:
   class AdsReadDelayHandle;
 
-  class AdsResponseParser : public XdsApi::AdsResponseParserInterface {
+  class AdsResponseParser final : public XdsApi::AdsResponseParserInterface {
    public:
     struct Result {
       const XdsResourceType* type;
@@ -178,7 +179,7 @@ class XdsClient::XdsChannel::AdsCall : public InternallyRefCounted<AdsCall> {
     Result result_;
   };
 
-  class ResourceTimer : public InternallyRefCounted<ResourceTimer> {
+  class ResourceTimer final : public InternallyRefCounted<ResourceTimer> {
    public:
     ResourceTimer(const XdsResourceType* type, const XdsResourceName& name)
         : type_(type), name_(name) {}
@@ -291,7 +292,7 @@ class XdsClient::XdsChannel::AdsCall : public InternallyRefCounted<AdsCall> {
         ABSL_GUARDED_BY(&XdsClient::mu_);
   };
 
-  class StreamEventHandler
+  class StreamEventHandler final
       : public XdsTransportFactory::XdsTransport::StreamingCall::EventHandler {
    public:
     explicit StreamEventHandler(RefCountedPtr<AdsCall> ads_call)
@@ -354,7 +355,8 @@ class XdsClient::XdsChannel::AdsCall : public InternallyRefCounted<AdsCall> {
 };
 
 // Contains an LRS call to the xds server.
-class XdsClient::XdsChannel::LrsCall : public InternallyRefCounted<LrsCall> {
+class XdsClient::XdsChannel::LrsCall final
+    : public InternallyRefCounted<LrsCall> {
  public:
   // The ctor and dtor should not be used directly.
   explicit LrsCall(RefCountedPtr<RetryableCall<LrsCall>> retryable_call);
@@ -367,7 +369,7 @@ class XdsClient::XdsChannel::LrsCall : public InternallyRefCounted<LrsCall> {
   bool seen_response() const { return seen_response_; }
 
  private:
-  class StreamEventHandler
+  class StreamEventHandler final
       : public XdsTransportFactory::XdsTransport::StreamingCall::EventHandler {
    public:
     explicit StreamEventHandler(RefCountedPtr<LrsCall> lrs_call)
@@ -386,7 +388,7 @@ class XdsClient::XdsChannel::LrsCall : public InternallyRefCounted<LrsCall> {
   };
 
   // A repeating timer for a particular duration.
-  class Timer : public InternallyRefCounted<Timer> {
+  class Timer final : public InternallyRefCounted<Timer> {
    public:
     explicit Timer(RefCountedPtr<LrsCall> lrs_call)
         : lrs_call_(std::move(lrs_call)) {}
@@ -700,7 +702,7 @@ void XdsClient::XdsChannel::RetryableCall<T>::OnRetryTimer() {
 // XdsClient::XdsChannel::AdsCall::AdsReadDelayHandle
 //
 
-class XdsClient::XdsChannel::AdsCall::AdsReadDelayHandle
+class XdsClient::XdsChannel::AdsCall::AdsReadDelayHandle final
     : public XdsClient::ReadDelayHandle {
  public:
   explicit AdsReadDelayHandle(RefCountedPtr<AdsCall> ads_call)

src/core/ext/xds/xds_client.h

@@ -208,7 +208,7 @@ class XdsClient : public DualRefCounted<XdsClient> {
 
   // Contains a channel to the xds server and all the data related to the
   // channel.  Holds a ref to the xds client object.
-  class XdsChannel : public DualRefCounted<XdsChannel> {
+  class XdsChannel final : public DualRefCounted<XdsChannel> {
    public:
     template <typename T>
     class RetryableCall;

src/core/ext/xds/xds_client_grpc.cc

@@ -140,7 +140,7 @@ const auto kMetricResources =
 // GrpcXdsClient::MetricsReporter
 //
 
-class GrpcXdsClient::MetricsReporter : public XdsMetricsReporter {
+class GrpcXdsClient::MetricsReporter final : public XdsMetricsReporter {
  public:
   explicit MetricsReporter(GrpcXdsClient& xds_client)
       : xds_client_(xds_client) {}

src/core/ext/xds/xds_client_grpc.h

@@ -40,7 +40,7 @@
 
 namespace grpc_core {
 
-class GrpcXdsClient : public XdsClient {
+class GrpcXdsClient final : public XdsClient {
  public:
   // The key to pass to GetOrCreate() for gRPC servers.
   static constexpr absl::string_view kServerKey = "#server";

src/core/ext/xds/xds_client_stats.h

@@ -45,7 +45,7 @@ namespace grpc_core {
 class XdsClient;
 
 // Locality name.
-class XdsLocalityName : public RefCounted<XdsLocalityName> {
+class XdsLocalityName final : public RefCounted<XdsLocalityName> {
  public:
   struct Less {
     bool operator()(const XdsLocalityName* lhs,
@@ -115,7 +115,7 @@ class XdsLocalityName : public RefCounted<XdsLocalityName> {
 };
 
 // Drop stats for an xds cluster.
-class XdsClusterDropStats : public RefCounted<XdsClusterDropStats> {
+class XdsClusterDropStats final : public RefCounted<XdsClusterDropStats> {
  public:
   // The total number of requests dropped for any reason is the sum of
   // uncategorized_drops, and dropped_requests map.
@@ -169,7 +169,8 @@ class XdsClusterDropStats : public RefCounted<XdsClusterDropStats> {
 };
 
 // Locality stats for an xds cluster.
-class XdsClusterLocalityStats : public RefCounted<XdsClusterLocalityStats> {
+class XdsClusterLocalityStats final
+    : public RefCounted<XdsClusterLocalityStats> {
  public:
   struct BackendMetric {
     uint64_t num_requests_finished_with_metric = 0;

src/core/ext/xds/xds_cluster_specifier_plugin.h

@@ -49,7 +49,7 @@ class XdsClusterSpecifierPluginImpl {
       ValidationErrors* errors) const = 0;
 };
 
-class XdsRouteLookupClusterSpecifierPlugin
+class XdsRouteLookupClusterSpecifierPlugin final
     : public XdsClusterSpecifierPluginImpl {
   absl::string_view ConfigProtoName() const override;
 
@@ -60,7 +60,7 @@ class XdsRouteLookupClusterSpecifierPlugin
       ValidationErrors* errors) const override;
 };
 
-class XdsClusterSpecifierPluginRegistry {
+class XdsClusterSpecifierPluginRegistry final {
  public:
   XdsClusterSpecifierPluginRegistry();
 

src/core/ext/xds/xds_endpoint.h

@@ -71,7 +71,7 @@ struct XdsEndpointResource : public XdsResourceType::ResourceData {
   // 1. to initialize in the control plane combiner;
   // 2. to use in the data plane combiner.
   // So no additional synchronization is needed.
-  class DropConfig : public RefCounted<DropConfig> {
+  class DropConfig final : public RefCounted<DropConfig> {
    public:
     struct DropCategory {
       bool operator==(const DropCategory& other) const {
@@ -130,7 +130,7 @@ struct XdsEndpointResource : public XdsResourceType::ResourceData {
   std::string ToString() const;
 };
 
-class XdsEndpointResourceType
+class XdsEndpointResourceType final
     : public XdsResourceTypeImpl<XdsEndpointResourceType, XdsEndpointResource> {
  public:
   absl::string_view type_url() const override {

src/core/ext/xds/xds_health_status.h

@@ -34,7 +34,7 @@
 
 namespace grpc_core {
 
-class XdsHealthStatus {
+class XdsHealthStatus final {
  public:
   enum HealthStatus { kUnknown, kHealthy, kDraining };
 
@@ -56,7 +56,7 @@ class XdsHealthStatus {
   HealthStatus status_;
 };
 
-class XdsHealthStatusSet {
+class XdsHealthStatusSet final {
  public:
   XdsHealthStatusSet() = default;
 

src/core/ext/xds/xds_http_fault_filter.h

@@ -33,7 +33,7 @@
 
 namespace grpc_core {
 
-class XdsHttpFaultFilter : public XdsHttpFilterImpl {
+class XdsHttpFaultFilter final : public XdsHttpFilterImpl {
  public:
   absl::string_view ConfigProtoName() const override;
   absl::string_view OverrideConfigProtoName() const override;

src/core/ext/xds/xds_http_filters.h

@@ -124,7 +124,7 @@ class XdsHttpFilterImpl {
   virtual bool IsTerminalFilter() const { return false; }
 };
 
-class XdsHttpRouterFilter : public XdsHttpFilterImpl {
+class XdsHttpRouterFilter final : public XdsHttpFilterImpl {
  public:
   absl::string_view ConfigProtoName() const override;
   absl::string_view OverrideConfigProtoName() const override;
@@ -147,7 +147,7 @@ class XdsHttpRouterFilter : public XdsHttpFilterImpl {
   bool IsTerminalFilter() const override { return true; }
 };
 
-class XdsHttpFilterRegistry {
+class XdsHttpFilterRegistry final {
  public:
   explicit XdsHttpFilterRegistry(bool register_builtins = true);
 

src/core/ext/xds/xds_http_rbac_filter.h

@@ -33,7 +33,7 @@
 
 namespace grpc_core {
 
-class XdsHttpRbacFilter : public XdsHttpFilterImpl {
+class XdsHttpRbacFilter final : public XdsHttpFilterImpl {
  public:
   absl::string_view ConfigProtoName() const override;
   absl::string_view OverrideConfigProtoName() const override;

src/core/ext/xds/xds_http_stateful_session_filter.h

@@ -33,7 +33,7 @@
 
 namespace grpc_core {
 
-class XdsHttpStatefulSessionFilter : public XdsHttpFilterImpl {
+class XdsHttpStatefulSessionFilter final : public XdsHttpFilterImpl {
  public:
   absl::string_view ConfigProtoName() const override;
   absl::string_view OverrideConfigProtoName() const override;

src/core/ext/xds/xds_lb_policy_registry.cc

@@ -46,7 +46,7 @@ namespace grpc_core {
 
 namespace {
 
-class RoundRobinLbPolicyConfigFactory
+class RoundRobinLbPolicyConfigFactory final
     : public XdsLbPolicyRegistry::ConfigFactory {
  public:
   Json::Object ConvertXdsLbPolicyConfig(
@@ -64,7 +64,7 @@ class RoundRobinLbPolicyConfigFactory
   }
 };
 
-class ClientSideWeightedRoundRobinLbPolicyConfigFactory
+class ClientSideWeightedRoundRobinLbPolicyConfigFactory final
     : public XdsLbPolicyRegistry::ConfigFactory {
  public:
   Json::Object ConvertXdsLbPolicyConfig(
@@ -151,7 +151,7 @@ class ClientSideWeightedRoundRobinLbPolicyConfigFactory
   }
 };
 
-class RingHashLbPolicyConfigFactory
+class RingHashLbPolicyConfigFactory final
     : public XdsLbPolicyRegistry::ConfigFactory {
  public:
   Json::Object ConvertXdsLbPolicyConfig(
@@ -216,7 +216,7 @@ class RingHashLbPolicyConfigFactory
   }
 };
 
-class WrrLocalityLbPolicyConfigFactory
+class WrrLocalityLbPolicyConfigFactory final
     : public XdsLbPolicyRegistry::ConfigFactory {
  public:
   Json::Object ConvertXdsLbPolicyConfig(
@@ -255,7 +255,7 @@ class WrrLocalityLbPolicyConfigFactory
   }
 };
 
-class PickFirstLbPolicyConfigFactory
+class PickFirstLbPolicyConfigFactory final
     : public XdsLbPolicyRegistry::ConfigFactory {
  public:
   Json::Object ConvertXdsLbPolicyConfig(

src/core/ext/xds/xds_lb_policy_registry.h

@@ -33,7 +33,7 @@ namespace grpc_core {
 
 // A registry that maintans a set of converters that are able to map xDS
 // loadbalancing policy configurations to gRPC's JSON format.
-class XdsLbPolicyRegistry {
+class XdsLbPolicyRegistry final {
  public:
   class ConfigFactory {
    public:

src/core/ext/xds/xds_listener.h

@@ -207,7 +207,7 @@ struct XdsListenerResource : public XdsResourceType::ResourceData {
   std::string ToString() const;
 };
 
-class XdsListenerResourceType
+class XdsListenerResourceType final
     : public XdsResourceTypeImpl<XdsListenerResourceType, XdsListenerResource> {
  public:
   absl::string_view type_url() const override {

src/core/ext/xds/xds_route_config.h

@@ -227,7 +227,7 @@ struct XdsRouteConfigResource : public XdsResourceType::ResourceData {
       ValidationErrors* errors);
 };
 
-class XdsRouteConfigResourceType
+class XdsRouteConfigResourceType final
     : public XdsResourceTypeImpl<XdsRouteConfigResourceType,
                                  XdsRouteConfigResource> {
  public:

src/core/ext/xds/xds_routing.h

@@ -39,7 +39,7 @@
 
 namespace grpc_core {
 
-class XdsRouting {
+class XdsRouting final {
  public:
   class VirtualHostListIterator {
    public:

src/core/ext/xds/xds_server_config_fetcher.cc

@@ -99,7 +99,7 @@ TraceFlag grpc_xds_server_config_fetcher_trace(false,
 
 // A server config fetcher that fetches the information for configuring server
 // listeners from the xDS control plane.
-class XdsServerConfigFetcher : public grpc_server_config_fetcher {
+class XdsServerConfigFetcher final : public grpc_server_config_fetcher {
  public:
   XdsServerConfigFetcher(RefCountedPtr<GrpcXdsClient> xds_client,
                          grpc_server_xds_status_notifier notifier);
@@ -140,7 +140,7 @@ class XdsServerConfigFetcher : public grpc_server_config_fetcher {
 // continues to be used. If there isn't any previous good update or if the
 // update received was a fatal error (resource does not exist), the server
 // listener is made to stop listening.
-class XdsServerConfigFetcher::ListenerWatcher
+class XdsServerConfigFetcher::ListenerWatcher final
     : public XdsListenerResourceType::WatcherInterface {
  public:
   ListenerWatcher(RefCountedPtr<GrpcXdsClient> xds_client,
@@ -200,7 +200,7 @@ class XdsServerConfigFetcher::ListenerWatcher
 // appropriate filter chain from the xDS Listener resource and injects channel
 // args that configure the right mTLS certs and cause the right set of HTTP
 // filters to be injected.
-class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager
+class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager final
     : public grpc_server_config_fetcher::ConnectionManager {
  public:
   FilterChainMatchManager(RefCountedPtr<GrpcXdsClient> xds_client,
@@ -280,7 +280,8 @@ class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager
 // with the latest updates and new connections do not need to wait for the RDS
 // resources to be fetched.
 class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager::
-    RouteConfigWatcher : public XdsRouteConfigResourceType::WatcherInterface {
+    RouteConfigWatcher final
+    : public XdsRouteConfigResourceType::WatcherInterface {
  public:
   RouteConfigWatcher(
       std::string resource_name,
@@ -316,7 +317,7 @@ class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager::
 // DynamicXdsServerConfigSelectorProvider to parse the RDS update and get
 // per-call configuration based on incoming metadata.
 class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager::
-    XdsServerConfigSelector : public ServerConfigSelector {
+    XdsServerConfigSelector final : public ServerConfigSelector {
  public:
   static absl::StatusOr<RefCountedPtr<XdsServerConfigSelector>> Create(
       const XdsHttpFilterRegistry& http_filter_registry,
@@ -340,7 +341,7 @@ class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager::
       RefCountedPtr<ServiceConfig> method_config;
     };
 
-    class RouteListIterator : public XdsRouting::RouteListIterator {
+    class RouteListIterator final : public XdsRouting::RouteListIterator {
      public:
       explicit RouteListIterator(const std::vector<Route>* routes)
           : routes_(routes) {}
@@ -360,7 +361,8 @@ class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager::
     std::vector<Route> routes;
   };
 
-  class VirtualHostListIterator : public XdsRouting::VirtualHostListIterator {
+  class VirtualHostListIterator final
+      : public XdsRouting::VirtualHostListIterator {
    public:
     explicit VirtualHostListIterator(
         const std::vector<VirtualHost>* virtual_hosts)
@@ -383,7 +385,7 @@ class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager::
 // An XdsServerConfigSelectorProvider implementation for when the
 // RouteConfiguration is available inline.
 class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager::
-    StaticXdsServerConfigSelectorProvider
+    StaticXdsServerConfigSelectorProvider final
     : public ServerConfigSelectorProvider {
  public:
   StaticXdsServerConfigSelectorProvider(
@@ -434,7 +436,7 @@ class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager::
 // An XdsServerConfigSelectorProvider implementation for when the
 // RouteConfiguration is to be fetched separately via RDS.
 class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager::
-    DynamicXdsServerConfigSelectorProvider
+    DynamicXdsServerConfigSelectorProvider final
     : public ServerConfigSelectorProvider {
  public:
   DynamicXdsServerConfigSelectorProvider(
@@ -480,7 +482,7 @@ class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager::
 // A watcher implementation for updating the RDS resource used by
 // DynamicXdsServerConfigSelectorProvider
 class XdsServerConfigFetcher::ListenerWatcher::FilterChainMatchManager::
-    DynamicXdsServerConfigSelectorProvider::RouteConfigWatcher
+    DynamicXdsServerConfigSelectorProvider::RouteConfigWatcher final
     : public XdsRouteConfigResourceType::WatcherInterface {
  public:
   explicit RouteConfigWatcher(

src/core/ext/xds/xds_transport_grpc.cc

@@ -227,7 +227,7 @@ void GrpcXdsTransportFactory::GrpcXdsTransport::GrpcStreamingCall::
 // GrpcXdsTransportFactory::GrpcXdsTransport::StateWatcher
 //
 
-class GrpcXdsTransportFactory::GrpcXdsTransport::StateWatcher
+class GrpcXdsTransportFactory::GrpcXdsTransport::StateWatcher final
     : public AsyncConnectivityStateWatcherInterface {
  public:
   explicit StateWatcher(

src/core/ext/xds/xds_transport_grpc.h

@@ -41,7 +41,7 @@
 
 namespace grpc_core {
 
-class GrpcXdsTransportFactory : public XdsTransportFactory {
+class GrpcXdsTransportFactory final : public XdsTransportFactory {
  public:
   class GrpcXdsTransport;
 
@@ -62,7 +62,7 @@ class GrpcXdsTransportFactory : public XdsTransportFactory {
   grpc_pollset_set* interested_parties_;
 };
 
-class GrpcXdsTransportFactory::GrpcXdsTransport
+class GrpcXdsTransportFactory::GrpcXdsTransport final
     : public XdsTransportFactory::XdsTransport {
  public:
   class GrpcStreamingCall;
@@ -88,7 +88,7 @@ class GrpcXdsTransportFactory::GrpcXdsTransport
   StateWatcher* watcher_;
 };
 
-class GrpcXdsTransportFactory::GrpcXdsTransport::GrpcStreamingCall
+class GrpcXdsTransportFactory::GrpcXdsTransport::GrpcStreamingCall final
     : public XdsTransportFactory::XdsTransport::StreamingCall {
  public:
   GrpcStreamingCall(RefCountedPtr<GrpcXdsTransportFactory> factory,

src/core/lib/channel/channelz.h

@@ -120,7 +120,7 @@ class BaseNode : public RefCounted<BaseNode> {
 //   - track calls_{started,succeeded,failed}
 //   - track last_call_started_timestamp
 //   - perform rendering of the above items
-class CallCountingHelper {
+class CallCountingHelper final {
  public:
   void RecordCallStarted();
   void RecordCallFailed();
@@ -139,7 +139,7 @@ class CallCountingHelper {
   std::atomic<gpr_cycle_counter> last_call_started_cycle_{0};
 };
 
-class PerCpuCallCountingHelper {
+class PerCpuCallCountingHelper final {
  public:
   void RecordCallStarted();
   void RecordCallFailed();
@@ -183,7 +183,7 @@ class PerCpuCallCountingHelper {
 };
 
 // Handles channelz bookkeeping for channels
-class ChannelNode : public BaseNode {
+class ChannelNode final : public BaseNode {
  public:
   ChannelNode(std::string target, size_t channel_tracer_max_nodes,
               bool is_internal_channel);
@@ -247,7 +247,7 @@ class ChannelNode : public BaseNode {
 };
 
 // Handles channelz bookkeeping for servers
-class ServerNode : public BaseNode {
+class ServerNode final : public BaseNode {
  public:
   explicit ServerNode(size_t channel_tracer_max_nodes);
 
@@ -291,7 +291,7 @@ class ServerNode : public BaseNode {
 #define GRPC_ARG_CHANNELZ_SECURITY "grpc.internal.channelz_security"
 
 // Handles channelz bookkeeping for sockets
-class SocketNode : public BaseNode {
+class SocketNode final : public BaseNode {
  public:
   struct Security : public RefCounted<Security> {
     struct Tls {
@@ -367,7 +367,7 @@ class SocketNode : public BaseNode {
 };
 
 // Handles channelz bookkeeping for listen sockets
-class ListenSocketNode : public BaseNode {
+class ListenSocketNode final : public BaseNode {
  public:
   ListenSocketNode(std::string local_addr, std::string name);
   ~ListenSocketNode() override {}

src/core/lib/channel/channelz_registry.h

@@ -36,7 +36,7 @@ namespace channelz {
 
 // singleton registry object to track all objects that are needed to support
 // channelz bookkeeping. All objects share globally distributed uuids.
-class ChannelzRegistry {
+class ChannelzRegistry final {
  public:
   static void Register(BaseNode* node) {
     return Default()->InternalRegister(node);

src/core/lib/surface/legacy_channel.cc

@@ -214,7 +214,7 @@ bool LegacyChannel::SupportsConnectivityWatcher() const {
 }
 
 // A fire-and-forget object to handle external connectivity state watches.
-class LegacyChannel::StateWatcher : public DualRefCounted<StateWatcher> {
+class LegacyChannel::StateWatcher final : public DualRefCounted<StateWatcher> {
  public:
   StateWatcher(RefCountedPtr<LegacyChannel> channel, grpc_completion_queue* cq,
                void* tag, grpc_connectivity_state last_observed_state,
@@ -254,7 +254,7 @@ class LegacyChannel::StateWatcher : public DualRefCounted<StateWatcher> {
  private:
   // A fire-and-forget object used to delay starting the timer until the
   // ClientChannelFilter actually starts the watch.
-  class WatcherTimerInitState {
+  class WatcherTimerInitState final {
    public:
     WatcherTimerInitState(StateWatcher* state_watcher, Timestamp deadline)
         : state_watcher_(state_watcher), deadline_(deadline) {

src/core/lib/surface/legacy_channel.h

@@ -44,7 +44,7 @@
 
 namespace grpc_core {
 
-class LegacyChannel : public Channel {
+class LegacyChannel final : public Channel {
  public:
   static absl::StatusOr<OrphanablePtr<Channel>> Create(
       std::string target, ChannelArgs args,

src/core/load_balancing/address_filtering.cc

@@ -47,7 +47,7 @@ int HierarchicalPathArg::ChannelArgsCompare(const HierarchicalPathArg* a,
 
 namespace {
 
-class HierarchicalAddressIterator : public EndpointAddressesIterator {
+class HierarchicalAddressIterator final : public EndpointAddressesIterator {
  public:
   HierarchicalAddressIterator(
       std::shared_ptr<EndpointAddressesIterator> parent_it,

src/core/load_balancing/address_filtering.h

@@ -87,7 +87,7 @@ namespace grpc_core {
 
 // An address channel arg containing the hierarchical path
 // to be associated with the address.
-class HierarchicalPathArg : public RefCounted<HierarchicalPathArg> {
+class HierarchicalPathArg final : public RefCounted<HierarchicalPathArg> {
  public:
   explicit HierarchicalPathArg(std::vector<RefCountedStringValue> path)
       : path_(std::move(path)) {}

src/core/load_balancing/child_policy_handler.cc

@@ -44,7 +44,7 @@ namespace grpc_core {
 // ChildPolicyHandler::Helper
 //
 
-class ChildPolicyHandler::Helper
+class ChildPolicyHandler::Helper final
     : public LoadBalancingPolicy::ParentOwningDelegatingChannelControlHelper<
           ChildPolicyHandler> {
  public:

src/core/load_balancing/endpoint_list.cc

@@ -51,7 +51,7 @@ namespace grpc_core {
 // EndpointList::Endpoint::Helper
 //
 
-class EndpointList::Endpoint::Helper
+class EndpointList::Endpoint::Helper final
     : public LoadBalancingPolicy::DelegatingChannelControlHelper {
  public:
   explicit Helper(RefCountedPtr<Endpoint> endpoint)

src/core/load_balancing/grpclb/client_load_reporting_filter.h

@@ -30,7 +30,8 @@
 #include "src/core/lib/transport/transport.h"
 
 namespace grpc_core {
-class ClientLoadReportingFilter : public ChannelFilter {
+
+class ClientLoadReportingFilter final : public ChannelFilter {
  public:
   static const grpc_channel_filter kFilter;
 
@@ -41,6 +42,7 @@ class ClientLoadReportingFilter : public ChannelFilter {
   ArenaPromise<ServerMetadataHandle> MakeCallPromise(
       CallArgs call_args, NextPromiseFactory next_promise_factory) override;
 };
+
 }  // namespace grpc_core
 
 #endif  // GRPC_SRC_CORE_LOAD_BALANCING_GRPCLB_CLIENT_LOAD_REPORTING_FILTER_H

src/core/load_balancing/grpclb/grpclb.cc

@@ -165,7 +165,7 @@ using ::grpc_event_engine::experimental::EventEngine;
 
 constexpr absl::string_view kGrpclb = "grpclb";
 
-class GrpcLbConfig : public LoadBalancingPolicy::Config {
+class GrpcLbConfig final : public LoadBalancingPolicy::Config {
  public:
   GrpcLbConfig() = default;
 
@@ -222,7 +222,7 @@ class GrpcLbConfig : public LoadBalancingPolicy::Config {
   std::string service_name_;
 };
 
-class GrpcLb : public LoadBalancingPolicy {
+class GrpcLb final : public LoadBalancingPolicy {
  public:
   explicit GrpcLb(Args args);
 
@@ -233,7 +233,8 @@ class GrpcLb : public LoadBalancingPolicy {
 
  private:
   /// Contains a call to the LB server and all the data related to the call.
-  class BalancerCallState : public InternallyRefCounted<BalancerCallState> {
+  class BalancerCallState final
+      : public InternallyRefCounted<BalancerCallState> {
    public:
     explicit BalancerCallState(
         RefCountedPtr<LoadBalancingPolicy> parent_grpclb_policy);
@@ -307,7 +308,7 @@ class GrpcLb : public LoadBalancingPolicy {
     grpc_closure client_load_report_done_closure_;
   };
 
-  class SubchannelWrapper : public DelegatingSubchannel {
+  class SubchannelWrapper final : public DelegatingSubchannel {
    public:
     SubchannelWrapper(RefCountedPtr<SubchannelInterface> subchannel,
                       RefCountedPtr<GrpcLb> lb_policy, std::string lb_token,
@@ -343,7 +344,8 @@ class GrpcLb : public LoadBalancingPolicy {
     RefCountedPtr<GrpcLbClientStats> client_stats_;
   };
 
-  class TokenAndClientStatsArg : public RefCounted<TokenAndClientStatsArg> {
+  class TokenAndClientStatsArg final
+      : public RefCounted<TokenAndClientStatsArg> {
    public:
     TokenAndClientStatsArg(std::string lb_token,
                            RefCountedPtr<GrpcLbClientStats> client_stats)
@@ -371,7 +373,7 @@ class GrpcLb : public LoadBalancingPolicy {
     RefCountedPtr<GrpcLbClientStats> client_stats_;
   };
 
-  class Serverlist : public RefCounted<Serverlist> {
+  class Serverlist final : public RefCounted<Serverlist> {
    public:
     // Takes ownership of serverlist.
     explicit Serverlist(std::vector<GrpcLbServer> serverlist)
@@ -408,7 +410,7 @@ class GrpcLb : public LoadBalancingPolicy {
     std::atomic<size_t> drop_index_{0};
   };
 
-  class Picker : public SubchannelPicker {
+  class Picker final : public SubchannelPicker {
    public:
     Picker(RefCountedPtr<Serverlist> serverlist,
            RefCountedPtr<SubchannelPicker> child_picker,
@@ -424,7 +426,7 @@ class GrpcLb : public LoadBalancingPolicy {
     // in the case where the subchannel call is never actually started,
     // since the client load reporting filter will not be able to do it
     // in that case.
-    class SubchannelCallTracker : public SubchannelCallTrackerInterface {
+    class SubchannelCallTracker final : public SubchannelCallTrackerInterface {
      public:
       SubchannelCallTracker(
           RefCountedPtr<GrpcLbClientStats> client_stats,
@@ -460,7 +462,8 @@ class GrpcLb : public LoadBalancingPolicy {
     RefCountedPtr<GrpcLbClientStats> client_stats_;
   };
 
-  class Helper : public ParentOwningDelegatingChannelControlHelper<GrpcLb> {
+  class Helper final
+      : public ParentOwningDelegatingChannelControlHelper<GrpcLb> {
    public:
     explicit Helper(RefCountedPtr<GrpcLb> parent)
         : ParentOwningDelegatingChannelControlHelper(std::move(parent)) {}
@@ -473,7 +476,7 @@ class GrpcLb : public LoadBalancingPolicy {
     void RequestReresolution() override;
   };
 
-  class StateWatcher : public AsyncConnectivityStateWatcherInterface {
+  class StateWatcher final : public AsyncConnectivityStateWatcherInterface {
    public:
     explicit StateWatcher(RefCountedPtr<GrpcLb> parent)
         : AsyncConnectivityStateWatcherInterface(parent->work_serializer()),
@@ -647,7 +650,8 @@ void ParseServer(const GrpcLbServer& server, grpc_resolved_address* addr) {
   }
 }
 
-class GrpcLb::Serverlist::AddressIterator : public EndpointAddressesIterator {
+class GrpcLb::Serverlist::AddressIterator final
+    : public EndpointAddressesIterator {
  public:
   AddressIterator(RefCountedPtr<Serverlist> serverlist,
                   RefCountedPtr<GrpcLbClientStats> client_stats)
@@ -1526,7 +1530,8 @@ void GrpcLb::ResetBackoffLocked() {
 }
 
 // Endpoint iterator wrapper to add null LB token attribute.
-class GrpcLb::NullLbTokenEndpointIterator : public EndpointAddressesIterator {
+class GrpcLb::NullLbTokenEndpointIterator final
+    : public EndpointAddressesIterator {
  public:
   explicit NullLbTokenEndpointIterator(
       std::shared_ptr<EndpointAddressesIterator> parent_it)
@@ -1892,7 +1897,7 @@ void GrpcLb::OnSubchannelCacheTimerLocked() {
 // factory
 //
 
-class GrpcLbFactory : public LoadBalancingPolicyFactory {
+class GrpcLbFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/grpclb/grpclb_client_stats.h

@@ -37,7 +37,7 @@
 
 namespace grpc_core {
 
-class GrpcLbClientStats : public RefCounted<GrpcLbClientStats> {
+class GrpcLbClientStats final : public RefCounted<GrpcLbClientStats> {
  public:
   struct DropTokenCount {
     UniquePtr<char> token;

src/core/load_balancing/health_check_client.cc

@@ -71,7 +71,7 @@ TraceFlag grpc_health_check_client_trace(false, "health_check_client");
 namespace {
 
 // A fire-and-forget class to asynchronously drain a WorkSerializer queue.
-class AsyncWorkSerializerDrainer {
+class AsyncWorkSerializerDrainer final {
  public:
   explicit AsyncWorkSerializerDrainer(
       std::shared_ptr<WorkSerializer> work_serializer)
@@ -212,7 +212,7 @@ void HealthProducer::HealthChecker::OnHealthWatchStatusChange(
 // HealthProducer::HealthChecker::HealthStreamEventHandler
 //
 
-class HealthProducer::HealthChecker::HealthStreamEventHandler
+class HealthProducer::HealthChecker::HealthStreamEventHandler final
     : public SubchannelStreamClient::CallEventHandler {
  public:
   explicit HealthStreamEventHandler(RefCountedPtr<HealthChecker> health_checker)
@@ -321,7 +321,7 @@ class HealthProducer::HealthChecker::HealthStreamEventHandler
 // HealthProducer::ConnectivityWatcher
 //
 
-class HealthProducer::ConnectivityWatcher
+class HealthProducer::ConnectivityWatcher final
     : public Subchannel::ConnectivityStateWatcherInterface {
  public:
   explicit ConnectivityWatcher(WeakRefCountedPtr<HealthProducer> producer)

src/core/load_balancing/health_check_client_internal.h

@@ -52,7 +52,7 @@ class HealthWatcher;
 // health watch call for each health check service name that is being
 // watched and reports the resulting connectivity state to all
 // registered watchers.
-class HealthProducer : public Subchannel::DataProducerInterface {
+class HealthProducer final : public Subchannel::DataProducerInterface {
  public:
   HealthProducer() : interested_parties_(grpc_pollset_set_create()) {}
   ~HealthProducer() override { grpc_pollset_set_destroy(interested_parties_); }
@@ -77,7 +77,7 @@ class HealthProducer : public Subchannel::DataProducerInterface {
 
   // Health checker for a given health check service name.  Contains the
   // health check client and the list of watchers.
-  class HealthChecker : public InternallyRefCounted<HealthChecker> {
+  class HealthChecker final : public InternallyRefCounted<HealthChecker> {
    public:
     HealthChecker(WeakRefCountedPtr<HealthProducer> producer,
                   absl::string_view health_check_service_name);
@@ -155,7 +155,7 @@ class HealthProducer : public Subchannel::DataProducerInterface {
 };
 
 // A data watcher that handles health checking.
-class HealthWatcher : public InternalSubchannelDataWatcherInterface {
+class HealthWatcher final : public InternalSubchannelDataWatcherInterface {
  public:
   HealthWatcher(
       std::shared_ptr<WorkSerializer> work_serializer,

src/core/load_balancing/lb_policy.h

@@ -430,7 +430,7 @@ class LoadBalancingPolicy : public InternallyRefCounted<LoadBalancingPolicy> {
   // A picker that returns PickResult::Queue for all picks.
   // Also calls the parent LB policy's ExitIdleLocked() method when the
   // first pick is seen.
-  class QueuePicker : public SubchannelPicker {
+  class QueuePicker final : public SubchannelPicker {
    public:
     explicit QueuePicker(RefCountedPtr<LoadBalancingPolicy> parent)
         : parent_(std::move(parent)) {}
@@ -445,7 +445,7 @@ class LoadBalancingPolicy : public InternallyRefCounted<LoadBalancingPolicy> {
   };
 
   // A picker that returns PickResult::Fail for all picks.
-  class TransientFailurePicker : public SubchannelPicker {
+  class TransientFailurePicker final : public SubchannelPicker {
    public:
     explicit TransientFailurePicker(absl::Status status) : status_(status) {}
 

src/core/load_balancing/lb_policy_registry.h

@@ -33,12 +33,12 @@
 
 namespace grpc_core {
 
-class LoadBalancingPolicyRegistry {
+class LoadBalancingPolicyRegistry final {
  public:
   /// Methods used to create and populate the LoadBalancingPolicyRegistry.
   /// NOT THREAD SAFE -- to be used only during global gRPC
   /// initialization and shutdown.
-  class Builder {
+  class Builder final {
    public:
     /// Registers an LB policy factory.  The factory will be used to create an
     /// LB policy whose name matches that of the factory.

src/core/load_balancing/oob_backend_metric.cc

@@ -66,7 +66,7 @@ TraceFlag grpc_orca_client_trace(false, "orca_client");
 // OrcaProducer::ConnectivityWatcher
 //
 
-class OrcaProducer::ConnectivityWatcher
+class OrcaProducer::ConnectivityWatcher final
     : public Subchannel::ConnectivityStateWatcherInterface {
  public:
   explicit ConnectivityWatcher(WeakRefCountedPtr<OrcaProducer> producer)
@@ -97,7 +97,7 @@ class OrcaProducer::ConnectivityWatcher
 // OrcaProducer::OrcaStreamEventHandler
 //
 
-class OrcaProducer::OrcaStreamEventHandler
+class OrcaProducer::OrcaStreamEventHandler final
     : public SubchannelStreamClient::CallEventHandler {
  public:
   OrcaStreamEventHandler(WeakRefCountedPtr<OrcaProducer> producer,
@@ -168,7 +168,7 @@ class OrcaProducer::OrcaStreamEventHandler
   // notifications, which avoids lock inversion problems due to
   // acquiring producer_->mu_ while holding the lock from inside of
   // SubchannelStreamClient.
-  class BackendMetricAllocator : public BackendMetricAllocatorInterface {
+  class BackendMetricAllocator final : public BackendMetricAllocatorInterface {
    public:
     explicit BackendMetricAllocator(WeakRefCountedPtr<OrcaProducer> producer)
         : producer_(std::move(producer)) {}

src/core/load_balancing/oob_backend_metric_internal.h

@@ -46,7 +46,7 @@ class OrcaWatcher;
 // This producer is registered with a subchannel.  It creates a
 // streaming ORCA call and reports the resulting backend metrics to all
 // registered watchers.
-class OrcaProducer : public Subchannel::DataProducerInterface {
+class OrcaProducer final : public Subchannel::DataProducerInterface {
  public:
   void Start(RefCountedPtr<Subchannel> subchannel);
 
@@ -92,7 +92,7 @@ class OrcaProducer : public Subchannel::DataProducerInterface {
 
 // This watcher is returned to the LB policy and added to the
 // client channel SubchannelWrapper.
-class OrcaWatcher : public InternalSubchannelDataWatcherInterface {
+class OrcaWatcher final : public InternalSubchannelDataWatcherInterface {
  public:
   OrcaWatcher(Duration report_interval,
               std::unique_ptr<OobBackendMetricWatcher> watcher)

src/core/load_balancing/outlier_detection/outlier_detection.cc

@@ -85,7 +85,7 @@ constexpr absl::string_view kOutlierDetection =
     "outlier_detection_experimental";
 
 // Config for xDS Cluster Impl LB policy.
-class OutlierDetectionLbConfig : public LoadBalancingPolicy::Config {
+class OutlierDetectionLbConfig final : public LoadBalancingPolicy::Config {
  public:
   OutlierDetectionLbConfig(
       OutlierDetectionConfig outlier_detection_config,
@@ -114,7 +114,7 @@ class OutlierDetectionLbConfig : public LoadBalancingPolicy::Config {
 };
 
 // xDS Cluster Impl LB policy.
-class OutlierDetectionLb : public LoadBalancingPolicy {
+class OutlierDetectionLb final : public LoadBalancingPolicy {
  public:
   explicit OutlierDetectionLb(Args args);
 
@@ -128,7 +128,7 @@ class OutlierDetectionLb : public LoadBalancingPolicy {
   class SubchannelState;
   class EndpointState;
 
-  class SubchannelWrapper : public DelegatingSubchannel {
+  class SubchannelWrapper final : public DelegatingSubchannel {
    public:
     SubchannelWrapper(std::shared_ptr<WorkSerializer> work_serializer,
                       RefCountedPtr<SubchannelState> subchannel_state,
@@ -158,7 +158,7 @@ class OutlierDetectionLb : public LoadBalancingPolicy {
     }
 
    private:
-    class WatcherWrapper
+    class WatcherWrapper final
         : public SubchannelInterface::ConnectivityStateWatcherInterface {
      public:
       WatcherWrapper(std::shared_ptr<
@@ -234,7 +234,7 @@ class OutlierDetectionLb : public LoadBalancingPolicy {
     WatcherWrapper* watcher_wrapper_ = nullptr;
   };
 
-  class SubchannelState : public RefCounted<SubchannelState> {
+  class SubchannelState final : public RefCounted<SubchannelState> {
    public:
     void AddSubchannel(SubchannelWrapper* wrapper) {
       subchannels_.insert(wrapper);
@@ -277,7 +277,7 @@ class OutlierDetectionLb : public LoadBalancingPolicy {
     RefCountedPtr<EndpointState> endpoint_state_ ABSL_GUARDED_BY(mu_);
   };
 
-  class EndpointState : public RefCounted<EndpointState> {
+  class EndpointState final : public RefCounted<EndpointState> {
    public:
     explicit EndpointState(std::set<SubchannelState*> subchannels)
         : subchannels_(std::move(subchannels)) {
@@ -371,7 +371,7 @@ class OutlierDetectionLb : public LoadBalancingPolicy {
   };
 
   // A picker that wraps the picker from the child to perform outlier detection.
-  class Picker : public SubchannelPicker {
+  class Picker final : public SubchannelPicker {
    public:
     Picker(OutlierDetectionLb* outlier_detection_lb,
            RefCountedPtr<SubchannelPicker> picker, bool counting_enabled);
@@ -384,7 +384,7 @@ class OutlierDetectionLb : public LoadBalancingPolicy {
     bool counting_enabled_;
   };
 
-  class Helper
+  class Helper final
       : public ParentOwningDelegatingChannelControlHelper<OutlierDetectionLb> {
    public:
     explicit Helper(RefCountedPtr<OutlierDetectionLb> outlier_detection_policy)
@@ -398,7 +398,7 @@ class OutlierDetectionLb : public LoadBalancingPolicy {
                      RefCountedPtr<SubchannelPicker> picker) override;
   };
 
-  class EjectionTimer : public InternallyRefCounted<EjectionTimer> {
+  class EjectionTimer final : public InternallyRefCounted<EjectionTimer> {
    public:
     EjectionTimer(RefCountedPtr<OutlierDetectionLb> parent,
                   Timestamp start_time);
@@ -483,7 +483,7 @@ void OutlierDetectionLb::SubchannelWrapper::CancelDataWatcher(
 // OutlierDetectionLb::Picker::SubchannelCallTracker
 //
 
-class OutlierDetectionLb::Picker::SubchannelCallTracker
+class OutlierDetectionLb::Picker::SubchannelCallTracker final
     : public LoadBalancingPolicy::SubchannelCallTrackerInterface {
  public:
   SubchannelCallTracker(
@@ -1068,7 +1068,7 @@ void OutlierDetectionLb::EjectionTimer::OnTimerLocked() {
 // factory
 //
 
-class OutlierDetectionLbFactory : public LoadBalancingPolicyFactory {
+class OutlierDetectionLbFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/pick_first/pick_first.cc

@@ -97,7 +97,7 @@ const auto kMetricConnectionAttemptsFailed =
         "EXPERIMENTAL.  Number of failed connection attempts.",
         "{attempt}", {kMetricLabelTarget}, {}, false);
 
-class PickFirstConfig : public LoadBalancingPolicy::Config {
+class PickFirstConfig final : public LoadBalancingPolicy::Config {
  public:
   absl::string_view name() const override { return kPickFirst; }
   bool shuffle_addresses() const { return shuffle_addresses_; }
@@ -115,7 +115,7 @@ class PickFirstConfig : public LoadBalancingPolicy::Config {
   bool shuffle_addresses_ = false;
 };
 
-class PickFirst : public LoadBalancingPolicy {
+class PickFirst final : public LoadBalancingPolicy {
  public:
   explicit PickFirst(Args args);
 
@@ -128,9 +128,9 @@ class PickFirst : public LoadBalancingPolicy {
  private:
   ~PickFirst() override;
 
-  class SubchannelList : public InternallyRefCounted<SubchannelList> {
+  class SubchannelList final : public InternallyRefCounted<SubchannelList> {
    public:
-    class SubchannelData {
+    class SubchannelData final {
      public:
       SubchannelData(SubchannelList* subchannel_list, size_t index,
                      RefCountedPtr<SubchannelInterface> subchannel);
@@ -162,7 +162,7 @@ class PickFirst : public LoadBalancingPolicy {
 
      private:
       // Watcher for subchannel connectivity state.
-      class Watcher
+      class Watcher final
           : public SubchannelInterface::ConnectivityStateWatcherInterface {
        public:
         Watcher(RefCountedPtr<SubchannelList> subchannel_list, size_t index)
@@ -287,7 +287,7 @@ class PickFirst : public LoadBalancingPolicy {
     absl::Status last_failure_;
   };
 
-  class HealthWatcher
+  class HealthWatcher final
       : public SubchannelInterface::ConnectivityStateWatcherInterface {
    public:
     explicit HealthWatcher(RefCountedPtr<PickFirst> policy)
@@ -308,7 +308,7 @@ class PickFirst : public LoadBalancingPolicy {
     RefCountedPtr<PickFirst> policy_;
   };
 
-  class Picker : public SubchannelPicker {
+  class Picker final : public SubchannelPicker {
    public:
     explicit Picker(RefCountedPtr<SubchannelInterface> subchannel)
         : subchannel_(std::move(subchannel)) {}
@@ -467,7 +467,7 @@ absl::string_view GetAddressFamily(const grpc_resolved_address& address) {
 
 // An endpoint list iterator that returns only entries for a specific
 // address family, as indicated by the URI scheme.
-class AddressFamilyIterator {
+class AddressFamilyIterator final {
  public:
   AddressFamilyIterator(absl::string_view scheme, size_t index)
       : scheme_(scheme), index_(index) {}
@@ -1128,7 +1128,7 @@ void PickFirst::SubchannelList::MaybeFinishHappyEyeballsPass() {
 // factory
 //
 
-class PickFirstFactory : public LoadBalancingPolicyFactory {
+class PickFirstFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/priority/priority.cc

@@ -83,7 +83,7 @@ constexpr Duration kChildRetentionInterval = Duration::Minutes(15);
 constexpr Duration kDefaultChildFailoverTimeout = Duration::Seconds(10);
 
 // Config for priority LB policy.
-class PriorityLbConfig : public LoadBalancingPolicy::Config {
+class PriorityLbConfig final : public LoadBalancingPolicy::Config {
  public:
   struct PriorityLbChild {
     RefCountedPtr<LoadBalancingPolicy::Config> config;
@@ -119,7 +119,7 @@ class PriorityLbConfig : public LoadBalancingPolicy::Config {
 };
 
 // priority LB policy.
-class PriorityLb : public LoadBalancingPolicy {
+class PriorityLb final : public LoadBalancingPolicy {
  public:
   explicit PriorityLb(Args args);
 
@@ -131,7 +131,7 @@ class PriorityLb : public LoadBalancingPolicy {
 
  private:
   // Each ChildPriority holds a ref to the PriorityLb.
-  class ChildPriority : public InternallyRefCounted<ChildPriority> {
+  class ChildPriority final : public InternallyRefCounted<ChildPriority> {
    public:
     ChildPriority(RefCountedPtr<PriorityLb> priority_policy, std::string name);
 
@@ -163,7 +163,7 @@ class PriorityLb : public LoadBalancingPolicy {
     bool FailoverTimerPending() const { return failover_timer_ != nullptr; }
 
    private:
-    class Helper : public DelegatingChannelControlHelper {
+    class Helper final : public DelegatingChannelControlHelper {
      public:
       explicit Helper(RefCountedPtr<ChildPriority> priority)
           : priority_(std::move(priority)) {}
@@ -183,7 +183,8 @@ class PriorityLb : public LoadBalancingPolicy {
       RefCountedPtr<ChildPriority> priority_;
     };
 
-    class DeactivationTimer : public InternallyRefCounted<DeactivationTimer> {
+    class DeactivationTimer final
+        : public InternallyRefCounted<DeactivationTimer> {
      public:
       explicit DeactivationTimer(RefCountedPtr<ChildPriority> child_priority);
 
@@ -196,7 +197,7 @@ class PriorityLb : public LoadBalancingPolicy {
       absl::optional<EventEngine::TaskHandle> timer_handle_;
     };
 
-    class FailoverTimer : public InternallyRefCounted<FailoverTimer> {
+    class FailoverTimer final : public InternallyRefCounted<FailoverTimer> {
      public:
       explicit FailoverTimer(RefCountedPtr<ChildPriority> child_priority);
 
@@ -874,7 +875,7 @@ void PriorityLbConfig::JsonPostLoad(const Json& /*json*/, const JsonArgs&,
   }
 }
 
-class PriorityLbFactory : public LoadBalancingPolicyFactory {
+class PriorityLbFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/ring_hash/ring_hash.cc

@@ -114,7 +114,7 @@ namespace {
 
 constexpr absl::string_view kRingHash = "ring_hash_experimental";
 
-class RingHashLbConfig : public LoadBalancingPolicy::Config {
+class RingHashLbConfig final : public LoadBalancingPolicy::Config {
  public:
   RingHashLbConfig(size_t min_ring_size, size_t max_ring_size)
       : min_ring_size_(min_ring_size), max_ring_size_(max_ring_size) {}
@@ -133,7 +133,7 @@ class RingHashLbConfig : public LoadBalancingPolicy::Config {
 
 constexpr size_t kRingSizeCapDefault = 4096;
 
-class RingHash : public LoadBalancingPolicy {
+class RingHash final : public LoadBalancingPolicy {
  public:
   explicit RingHash(Args args);
 
@@ -144,7 +144,7 @@ class RingHash : public LoadBalancingPolicy {
 
  private:
   // A ring computed based on a config and address list.
-  class Ring : public RefCounted<Ring> {
+  class Ring final : public RefCounted<Ring> {
    public:
     struct RingEntry {
       uint64_t hash;
@@ -160,7 +160,7 @@ class RingHash : public LoadBalancingPolicy {
   };
 
   // State for a particular endpoint.  Delegates to a pick_first child policy.
-  class RingHashEndpoint : public InternallyRefCounted<RingHashEndpoint> {
+  class RingHashEndpoint final : public InternallyRefCounted<RingHashEndpoint> {
    public:
     // index is the index into RingHash::endpoints_ of this endpoint.
     RingHashEndpoint(RefCountedPtr<RingHash> ring_hash, size_t index)
@@ -216,7 +216,7 @@ class RingHash : public LoadBalancingPolicy {
     RefCountedPtr<SubchannelPicker> picker_;
   };
 
-  class Picker : public SubchannelPicker {
+  class Picker final : public SubchannelPicker {
    public:
     explicit Picker(RefCountedPtr<RingHash> ring_hash)
         : ring_hash_(std::move(ring_hash)),
@@ -232,7 +232,7 @@ class RingHash : public LoadBalancingPolicy {
    private:
     // A fire-and-forget class that schedules endpoint connection attempts
     // on the control plane WorkSerializer.
-    class EndpointConnectionAttempter {
+    class EndpointConnectionAttempter final {
      public:
       EndpointConnectionAttempter(RefCountedPtr<RingHash> ring_hash,
                                   RefCountedPtr<RingHashEndpoint> endpoint)
@@ -462,7 +462,7 @@ RingHash::Ring::Ring(RingHash* ring_hash, RingHashLbConfig* config) {
 // RingHash::RingHashEndpoint::Helper
 //
 
-class RingHash::RingHashEndpoint::Helper
+class RingHash::RingHashEndpoint::Helper final
     : public LoadBalancingPolicy::DelegatingChannelControlHelper {
  public:
   explicit Helper(RefCountedPtr<RingHashEndpoint> endpoint)
@@ -849,7 +849,7 @@ void RingHash::UpdateAggregatedConnectivityStateLocked(
 // factory
 //
 
-class RingHashFactory : public LoadBalancingPolicyFactory {
+class RingHashFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/ring_hash/ring_hash.h

@@ -30,7 +30,7 @@
 
 namespace grpc_core {
 
-class RequestHashAttribute
+class RequestHashAttribute final
     : public ServiceConfigCallData::CallAttributeInterface {
  public:
   static UniqueTypeName TypeName();

src/core/load_balancing/rls/rls.cc

@@ -188,7 +188,7 @@ const Duration kCacheCleanupTimerInterval = Duration::Minutes(1);
 const int64_t kMaxCacheSizeBytes = 5 * 1024 * 1024;
 
 // Parsed RLS LB policy configuration.
-class RlsLbConfig : public LoadBalancingPolicy::Config {
+class RlsLbConfig final : public LoadBalancingPolicy::Config {
  public:
   struct KeyBuilder {
     std::map<std::string /*key*/, std::vector<std::string /*header*/>>
@@ -267,7 +267,7 @@ class RlsLbConfig : public LoadBalancingPolicy::Config {
 };
 
 // RLS LB policy.
-class RlsLb : public LoadBalancingPolicy {
+class RlsLb final : public LoadBalancingPolicy {
  public:
   explicit RlsLb(Args args);
 
@@ -323,7 +323,7 @@ class RlsLb : public LoadBalancingPolicy {
   };
 
   // Wraps a child policy for a given RLS target.
-  class ChildPolicyWrapper : public DualRefCounted<ChildPolicyWrapper> {
+  class ChildPolicyWrapper final : public DualRefCounted<ChildPolicyWrapper> {
    public:
     ChildPolicyWrapper(RefCountedPtr<RlsLb> lb_policy, std::string target);
 
@@ -374,7 +374,7 @@ class RlsLb : public LoadBalancingPolicy {
    private:
     // ChannelControlHelper object that allows the child policy to update state
     // with the wrapper.
-    class ChildPolicyHelper : public DelegatingChannelControlHelper {
+    class ChildPolicyHelper final : public DelegatingChannelControlHelper {
      public:
       explicit ChildPolicyHelper(WeakRefCountedPtr<ChildPolicyWrapper> wrapper)
           : wrapper_(std::move(wrapper)) {}
@@ -415,7 +415,7 @@ class RlsLb : public LoadBalancingPolicy {
 
   // A picker that uses the cache and the request map in the LB policy
   // (synchronized via a mutex) to determine how to route requests.
-  class Picker : public LoadBalancingPolicy::SubchannelPicker {
+  class Picker final : public LoadBalancingPolicy::SubchannelPicker {
    public:
     explicit Picker(RefCountedPtr<RlsLb> lb_policy);
 
@@ -432,11 +432,11 @@ class RlsLb : public LoadBalancingPolicy {
   };
 
   // An LRU cache with adjustable size.
-  class Cache {
+  class Cache final {
    public:
     using Iterator = std::list<RequestKey>::iterator;
 
-    class Entry : public InternallyRefCounted<Entry> {
+    class Entry final : public InternallyRefCounted<Entry> {
      public:
       Entry(RefCountedPtr<RlsLb> lb_policy, const RequestKey& key);
 
@@ -508,7 +508,7 @@ class RlsLb : public LoadBalancingPolicy {
       void MarkUsed() ABSL_EXCLUSIVE_LOCKS_REQUIRED(&RlsLb::mu_);
 
      private:
-      class BackoffTimer : public InternallyRefCounted<BackoffTimer> {
+      class BackoffTimer final : public InternallyRefCounted<BackoffTimer> {
        public:
         BackoffTimer(RefCountedPtr<Entry> entry, Timestamp backoff_time);
 
@@ -607,7 +607,7 @@ class RlsLb : public LoadBalancingPolicy {
 
   // Channel for communicating with the RLS server.
   // Contains throttling logic for RLS requests.
-  class RlsChannel : public InternallyRefCounted<RlsChannel> {
+  class RlsChannel final : public InternallyRefCounted<RlsChannel> {
    public:
     explicit RlsChannel(RefCountedPtr<RlsLb> lb_policy);
 
@@ -637,7 +637,7 @@ class RlsLb : public LoadBalancingPolicy {
    private:
     // Watches the state of the RLS channel. Notifies the LB policy when
     // the channel was previously in TRANSIENT_FAILURE and then becomes READY.
-    class StateWatcher : public AsyncConnectivityStateWatcherInterface {
+    class StateWatcher final : public AsyncConnectivityStateWatcherInterface {
      public:
       explicit StateWatcher(RefCountedPtr<RlsChannel> rls_channel)
           : AsyncConnectivityStateWatcherInterface(
@@ -653,7 +653,7 @@ class RlsLb : public LoadBalancingPolicy {
     };
 
     // Throttle state for RLS requests.
-    class Throttle {
+    class Throttle final {
      public:
       explicit Throttle(
           Duration window_size = kDefaultThrottleWindowSize,
@@ -691,7 +691,7 @@ class RlsLb : public LoadBalancingPolicy {
   };
 
   // A pending RLS request.  Instances will be tracked in request_map_.
-  class RlsRequest : public InternallyRefCounted<RlsRequest> {
+  class RlsRequest final : public InternallyRefCounted<RlsRequest> {
    public:
     // Asynchronously starts a call on rls_channel for key.
     // Stores backoff_state, which will be transferred to the data cache
@@ -2574,7 +2574,7 @@ void RlsLbConfig::JsonPostLoad(const Json& json, const JsonArgs&,
   }
 }
 
-class RlsLbFactory : public LoadBalancingPolicyFactory {
+class RlsLbFactory final : public LoadBalancingPolicyFactory {
  public:
   absl::string_view name() const override { return kRls; }
 

src/core/load_balancing/round_robin/round_robin.cc

@@ -59,7 +59,7 @@ namespace {
 
 constexpr absl::string_view kRoundRobin = "round_robin";
 
-class RoundRobin : public LoadBalancingPolicy {
+class RoundRobin final : public LoadBalancingPolicy {
  public:
   explicit RoundRobin(Args args);
 
@@ -69,7 +69,7 @@ class RoundRobin : public LoadBalancingPolicy {
   void ResetBackoffLocked() override;
 
  private:
-  class RoundRobinEndpointList : public EndpointList {
+  class RoundRobinEndpointList final : public EndpointList {
    public:
     RoundRobinEndpointList(RefCountedPtr<RoundRobin> round_robin,
                            EndpointAddressesIterator* endpoints,
@@ -88,7 +88,7 @@ class RoundRobin : public LoadBalancingPolicy {
     }
 
    private:
-    class RoundRobinEndpoint : public Endpoint {
+    class RoundRobinEndpoint final : public Endpoint {
      public:
       RoundRobinEndpoint(RefCountedPtr<EndpointList> endpoint_list,
                          const EndpointAddresses& addresses,
@@ -135,7 +135,7 @@ class RoundRobin : public LoadBalancingPolicy {
     absl::Status last_failure_;
   };
 
-  class Picker : public SubchannelPicker {
+  class Picker final : public SubchannelPicker {
    public:
     Picker(RoundRobin* parent,
            std::vector<RefCountedPtr<LoadBalancingPolicy::SubchannelPicker>>
@@ -431,12 +431,12 @@ void RoundRobin::RoundRobinEndpointList::
 // factory
 //
 
-class RoundRobinConfig : public LoadBalancingPolicy::Config {
+class RoundRobinConfig final : public LoadBalancingPolicy::Config {
  public:
   absl::string_view name() const override { return kRoundRobin; }
 };
 
-class RoundRobinFactory : public LoadBalancingPolicyFactory {
+class RoundRobinFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/weighted_round_robin/static_stride_scheduler.h

@@ -39,7 +39,7 @@ namespace grpc_core {
 // Construction is O(|weights|).  Picking is O(1) if weights are similar, or
 // O(|weights|) if the mean of the non-zero weights is a small fraction of the
 // max. Stores two bytes per weight.
-class StaticStrideScheduler {
+class StaticStrideScheduler final {
  public:
   // Constructs and returns a new StaticStrideScheduler, or nullopt if all
   // wieghts are zero or |weights| <= 1. All weights must be >=0.

src/core/load_balancing/weighted_round_robin/weighted_round_robin.cc

@@ -118,7 +118,7 @@ const auto kMetricEndpointWeights =
         "{weight}", {kMetricLabelTarget}, {kMetricLabelLocality}, false);
 
 // Config for WRR policy.
-class WeightedRoundRobinConfig : public LoadBalancingPolicy::Config {
+class WeightedRoundRobinConfig final : public LoadBalancingPolicy::Config {
  public:
   WeightedRoundRobinConfig() = default;
 
@@ -179,7 +179,7 @@ class WeightedRoundRobinConfig : public LoadBalancingPolicy::Config {
 };
 
 // WRR LB policy
-class WeightedRoundRobin : public LoadBalancingPolicy {
+class WeightedRoundRobin final : public LoadBalancingPolicy {
  public:
   explicit WeightedRoundRobin(Args args);
 
@@ -190,7 +190,7 @@ class WeightedRoundRobin : public LoadBalancingPolicy {
 
  private:
   // Represents the weight for a given address.
-  class EndpointWeight : public RefCounted<EndpointWeight> {
+  class EndpointWeight final : public RefCounted<EndpointWeight> {
    public:
     EndpointWeight(RefCountedPtr<WeightedRoundRobin> wrr,
                    EndpointAddressSet key)
@@ -216,9 +216,9 @@ class WeightedRoundRobin : public LoadBalancingPolicy {
     Timestamp last_update_time_ ABSL_GUARDED_BY(&mu_) = Timestamp::InfPast();
   };
 
-  class WrrEndpointList : public EndpointList {
+  class WrrEndpointList final : public EndpointList {
    public:
-    class WrrEndpoint : public Endpoint {
+    class WrrEndpoint final : public Endpoint {
      public:
       WrrEndpoint(RefCountedPtr<EndpointList> endpoint_list,
                   const EndpointAddresses& addresses, const ChannelArgs& args,
@@ -232,7 +232,7 @@ class WeightedRoundRobin : public LoadBalancingPolicy {
       RefCountedPtr<EndpointWeight> weight() const { return weight_; }
 
      private:
-      class OobWatcher : public OobBackendMetricWatcher {
+      class OobWatcher final : public OobBackendMetricWatcher {
        public:
         OobWatcher(RefCountedPtr<EndpointWeight> weight,
                    float error_utilization_penalty)
@@ -309,7 +309,7 @@ class WeightedRoundRobin : public LoadBalancingPolicy {
 
   // A picker that performs WRR picks with weights based on
   // endpoint-reported utilization and QPS.
-  class Picker : public SubchannelPicker {
+  class Picker final : public SubchannelPicker {
    public:
     Picker(RefCountedPtr<WeightedRoundRobin> wrr,
            WrrEndpointList* endpoint_list);
@@ -320,7 +320,7 @@ class WeightedRoundRobin : public LoadBalancingPolicy {
 
    private:
     // A call tracker that collects per-call endpoint utilization reports.
-    class SubchannelCallTracker : public SubchannelCallTrackerInterface {
+    class SubchannelCallTracker final : public SubchannelCallTrackerInterface {
      public:
       SubchannelCallTracker(
           RefCountedPtr<EndpointWeight> weight, float error_utilization_penalty,
@@ -997,7 +997,7 @@ void WeightedRoundRobin::WrrEndpointList::
 // factory
 //
 
-class WeightedRoundRobinFactory : public LoadBalancingPolicyFactory {
+class WeightedRoundRobinFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/weighted_target/weighted_target.cc

@@ -83,7 +83,7 @@ constexpr absl::string_view kWeightedTarget = "weighted_target_experimental";
 constexpr Duration kChildRetentionInterval = Duration::Minutes(15);
 
 // Config for weighted_target LB policy.
-class WeightedTargetLbConfig : public LoadBalancingPolicy::Config {
+class WeightedTargetLbConfig final : public LoadBalancingPolicy::Config {
  public:
   struct ChildConfig {
     uint32_t weight;
@@ -115,7 +115,7 @@ class WeightedTargetLbConfig : public LoadBalancingPolicy::Config {
 };
 
 // weighted_target LB policy.
-class WeightedTargetLb : public LoadBalancingPolicy {
+class WeightedTargetLb final : public LoadBalancingPolicy {
  public:
   explicit WeightedTargetLb(Args args);
 
@@ -127,7 +127,7 @@ class WeightedTargetLb : public LoadBalancingPolicy {
  private:
   // Picks a child using stateless WRR and then delegates to that
   // child's picker.
-  class WeightedPicker : public SubchannelPicker {
+  class WeightedPicker final : public SubchannelPicker {
    public:
     // Maintains a weighted list of pickers from each child that is in
     // ready state. The first element in the pair represents the end of a
@@ -151,7 +151,7 @@ class WeightedTargetLb : public LoadBalancingPolicy {
   };
 
   // Each WeightedChild holds a ref to its parent WeightedTargetLb.
-  class WeightedChild : public InternallyRefCounted<WeightedChild> {
+  class WeightedChild final : public InternallyRefCounted<WeightedChild> {
    public:
     WeightedChild(RefCountedPtr<WeightedTargetLb> weighted_target_policy,
                   const std::string& name);
@@ -173,7 +173,7 @@ class WeightedTargetLb : public LoadBalancingPolicy {
     RefCountedPtr<SubchannelPicker> picker() const { return picker_; }
 
    private:
-    class Helper : public DelegatingChannelControlHelper {
+    class Helper final : public DelegatingChannelControlHelper {
      public:
       explicit Helper(RefCountedPtr<WeightedChild> weighted_child)
           : weighted_child_(std::move(weighted_child)) {}
@@ -193,7 +193,7 @@ class WeightedTargetLb : public LoadBalancingPolicy {
       RefCountedPtr<WeightedChild> weighted_child_;
     };
 
-    class DelayedRemovalTimer
+    class DelayedRemovalTimer final
         : public InternallyRefCounted<DelayedRemovalTimer> {
      public:
       explicit DelayedRemovalTimer(RefCountedPtr<WeightedChild> weighted_child);
@@ -732,7 +732,7 @@ const JsonLoaderInterface* WeightedTargetLbConfig::JsonLoader(const JsonArgs&) {
   return loader;
 }
 
-class WeightedTargetLbFactory : public LoadBalancingPolicyFactory {
+class WeightedTargetLbFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/xds/cds.cc

@@ -85,7 +85,7 @@ using XdsConfig = XdsDependencyManager::XdsConfig;
 constexpr absl::string_view kCds = "cds_experimental";
 
 // Config for this LB policy.
-class CdsLbConfig : public LoadBalancingPolicy::Config {
+class CdsLbConfig final : public LoadBalancingPolicy::Config {
  public:
   CdsLbConfig() = default;
 
@@ -115,7 +115,7 @@ class CdsLbConfig : public LoadBalancingPolicy::Config {
 };
 
 // CDS LB policy.
-class CdsLb : public LoadBalancingPolicy {
+class CdsLb final : public LoadBalancingPolicy {
  public:
   explicit CdsLb(Args args);
 
@@ -232,7 +232,7 @@ std::string MakeChildPolicyName(absl::string_view cluster,
                       "}");
 }
 
-class PriorityEndpointIterator : public EndpointAddressesIterator {
+class PriorityEndpointIterator final : public EndpointAddressesIterator {
  public:
   PriorityEndpointIterator(
       std::string cluster_name,
@@ -731,7 +731,7 @@ void CdsLb::ReportTransientFailure(absl::Status status) {
 // factory
 //
 
-class CdsLbFactory : public LoadBalancingPolicyFactory {
+class CdsLbFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/xds/xds_cluster_impl.cc

@@ -86,12 +86,12 @@ using XdsConfig = XdsDependencyManager::XdsConfig;
 // global circuit breaker atomic map
 //
 
-class CircuitBreakerCallCounterMap {
+class CircuitBreakerCallCounterMap final {
  public:
   using Key =
       std::pair<std::string /*cluster*/, std::string /*eds_service_name*/>;
 
-  class CallCounter : public RefCounted<CallCounter> {
+  class CallCounter final : public RefCounted<CallCounter> {
    public:
     explicit CallCounter(Key key) : key_(std::move(key)) {}
     ~CallCounter() override;
@@ -152,7 +152,7 @@ CircuitBreakerCallCounterMap::CallCounter::~CallCounter() {
 constexpr absl::string_view kXdsClusterImpl = "xds_cluster_impl_experimental";
 
 // Config for xDS Cluster Impl LB policy.
-class XdsClusterImplLbConfig : public LoadBalancingPolicy::Config {
+class XdsClusterImplLbConfig final : public LoadBalancingPolicy::Config {
  public:
   XdsClusterImplLbConfig() = default;
 
@@ -179,7 +179,7 @@ class XdsClusterImplLbConfig : public LoadBalancingPolicy::Config {
 };
 
 // xDS Cluster Impl LB policy.
-class XdsClusterImplLb : public LoadBalancingPolicy {
+class XdsClusterImplLb final : public LoadBalancingPolicy {
  public:
   XdsClusterImplLb(RefCountedPtr<GrpcXdsClient> xds_client, Args args);
 
@@ -190,7 +190,7 @@ class XdsClusterImplLb : public LoadBalancingPolicy {
   void ResetBackoffLocked() override;
 
  private:
-  class StatsSubchannelWrapper : public DelegatingSubchannel {
+  class StatsSubchannelWrapper final : public DelegatingSubchannel {
    public:
     // If load reporting is enabled and we have an XdsClusterLocalityStats
     // object, that object already contains the locality labels.  We
@@ -235,7 +235,7 @@ class XdsClusterImplLb : public LoadBalancingPolicy {
   };
 
   // A picker that wraps the picker from the child to perform drops.
-  class Picker : public SubchannelPicker {
+  class Picker final : public SubchannelPicker {
    public:
     Picker(XdsClusterImplLb* xds_cluster_impl_lb,
            RefCountedPtr<SubchannelPicker> picker);
@@ -253,7 +253,7 @@ class XdsClusterImplLb : public LoadBalancingPolicy {
     RefCountedPtr<SubchannelPicker> picker_;
   };
 
-  class Helper
+  class Helper final
       : public ParentOwningDelegatingChannelControlHelper<XdsClusterImplLb> {
    public:
     explicit Helper(RefCountedPtr<XdsClusterImplLb> xds_cluster_impl_policy)
@@ -315,7 +315,7 @@ class XdsClusterImplLb : public LoadBalancingPolicy {
 // XdsClusterImplLb::Picker::SubchannelCallTracker
 //
 
-class XdsClusterImplLb::Picker::SubchannelCallTracker
+class XdsClusterImplLb::Picker::SubchannelCallTracker final
     : public LoadBalancingPolicy::SubchannelCallTrackerInterface {
  public:
   SubchannelCallTracker(
@@ -866,7 +866,7 @@ void XdsClusterImplLbConfig::JsonPostLoad(const Json& json, const JsonArgs&,
   }
 }
 
-class XdsClusterImplLbFactory : public LoadBalancingPolicyFactory {
+class XdsClusterImplLbFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/xds/xds_cluster_manager.cc

@@ -75,7 +75,7 @@ constexpr absl::string_view kXdsClusterManager =
     "xds_cluster_manager_experimental";
 
 // Config for xds_cluster_manager LB policy.
-class XdsClusterManagerLbConfig : public LoadBalancingPolicy::Config {
+class XdsClusterManagerLbConfig final : public LoadBalancingPolicy::Config {
  public:
   struct Child {
     RefCountedPtr<LoadBalancingPolicy::Config> config;
@@ -108,7 +108,7 @@ class XdsClusterManagerLbConfig : public LoadBalancingPolicy::Config {
 };
 
 // xds_cluster_manager LB policy.
-class XdsClusterManagerLb : public LoadBalancingPolicy {
+class XdsClusterManagerLb final : public LoadBalancingPolicy {
  public:
   explicit XdsClusterManagerLb(Args args);
 
@@ -121,7 +121,7 @@ class XdsClusterManagerLb : public LoadBalancingPolicy {
  private:
   // Picks a child using prefix or path matching and then delegates to that
   // child's picker.
-  class ClusterPicker : public SubchannelPicker {
+  class ClusterPicker final : public SubchannelPicker {
    public:
     // Maintains a map of cluster names to pickers.
     using ClusterMap = std::map<std::string /*cluster_name*/,
@@ -139,7 +139,7 @@ class XdsClusterManagerLb : public LoadBalancingPolicy {
   };
 
   // Each ClusterChild holds a ref to its parent XdsClusterManagerLb.
-  class ClusterChild : public InternallyRefCounted<ClusterChild> {
+  class ClusterChild final : public InternallyRefCounted<ClusterChild> {
    public:
     ClusterChild(RefCountedPtr<XdsClusterManagerLb> xds_cluster_manager_policy,
                  const std::string& name);
@@ -162,7 +162,7 @@ class XdsClusterManagerLb : public LoadBalancingPolicy {
     RefCountedPtr<SubchannelPicker> picker() const { return picker_; }
 
    private:
-    class Helper : public DelegatingChannelControlHelper {
+    class Helper final : public DelegatingChannelControlHelper {
      public:
       explicit Helper(RefCountedPtr<ClusterChild> xds_cluster_manager_child)
           : xds_cluster_manager_child_(std::move(xds_cluster_manager_child)) {}
@@ -625,7 +625,7 @@ const JsonLoaderInterface* XdsClusterManagerLbConfig::JsonLoader(
   return loader;
 }
 
-class XdsClusterManagerLbFactory : public LoadBalancingPolicyFactory {
+class XdsClusterManagerLbFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/xds/xds_override_host.cc

@@ -111,7 +111,7 @@ struct PtrLessThan {
 // xds_override_host LB policy
 //
 
-class XdsOverrideHostLb : public LoadBalancingPolicy {
+class XdsOverrideHostLb final : public LoadBalancingPolicy {
  public:
   explicit XdsOverrideHostLb(Args args);
 
@@ -126,7 +126,7 @@ class XdsOverrideHostLb : public LoadBalancingPolicy {
  private:
   class SubchannelEntry;
 
-  class SubchannelWrapper : public DelegatingSubchannel {
+  class SubchannelWrapper final : public DelegatingSubchannel {
    public:
     SubchannelWrapper(RefCountedPtr<SubchannelInterface> subchannel,
                       RefCountedPtr<XdsOverrideHostLb> policy);
@@ -163,7 +163,8 @@ class XdsOverrideHostLb : public LoadBalancingPolicy {
     }
 
    private:
-    class ConnectivityStateWatcher : public ConnectivityStateWatcherInterface {
+    class ConnectivityStateWatcher final
+        : public ConnectivityStateWatcherInterface {
      public:
       explicit ConnectivityStateWatcher(
           WeakRefCountedPtr<SubchannelWrapper> subchannel)
@@ -210,7 +211,7 @@ class XdsOverrideHostLb : public LoadBalancingPolicy {
   // avoid that, any method that may result in releasing a ref to the
   // SubchannelWrapper will instead return that ref to the caller, who is
   // responsible for releasing the ref after releasing the lock.
-  class SubchannelEntry : public RefCounted<SubchannelEntry> {
+  class SubchannelEntry final : public RefCounted<SubchannelEntry> {
    public:
     bool HasOwnedSubchannel() const
         ABSL_EXCLUSIVE_LOCKS_REQUIRED(&XdsOverrideHostLb::mu_) {
@@ -313,7 +314,7 @@ class XdsOverrideHostLb : public LoadBalancingPolicy {
 
   // A picker that wraps the picker from the child for cases when cookie is
   // present.
-  class Picker : public SubchannelPicker {
+  class Picker final : public SubchannelPicker {
    public:
     Picker(RefCountedPtr<XdsOverrideHostLb> xds_override_host_lb,
            RefCountedPtr<SubchannelPicker> picker,
@@ -322,7 +323,7 @@ class XdsOverrideHostLb : public LoadBalancingPolicy {
     PickResult Pick(PickArgs args) override;
 
    private:
-    class SubchannelConnectionRequester {
+    class SubchannelConnectionRequester final {
      public:
       explicit SubchannelConnectionRequester(
           RefCountedPtr<SubchannelWrapper> subchannel)
@@ -348,7 +349,7 @@ class XdsOverrideHostLb : public LoadBalancingPolicy {
       grpc_closure closure_;
     };
 
-    class SubchannelCreationRequester {
+    class SubchannelCreationRequester final {
      public:
       SubchannelCreationRequester(RefCountedPtr<XdsOverrideHostLb> policy,
                                   absl::string_view address)
@@ -383,7 +384,7 @@ class XdsOverrideHostLb : public LoadBalancingPolicy {
     XdsHealthStatusSet override_host_health_status_set_;
   };
 
-  class Helper
+  class Helper final
       : public ParentOwningDelegatingChannelControlHelper<XdsOverrideHostLb> {
    public:
     explicit Helper(RefCountedPtr<XdsOverrideHostLb> xds_override_host_policy)
@@ -397,7 +398,7 @@ class XdsOverrideHostLb : public LoadBalancingPolicy {
                      RefCountedPtr<SubchannelPicker> picker) override;
   };
 
-  class IdleTimer : public InternallyRefCounted<IdleTimer> {
+  class IdleTimer final : public InternallyRefCounted<IdleTimer> {
    public:
     IdleTimer(RefCountedPtr<XdsOverrideHostLb> policy, Duration duration);
 
@@ -729,7 +730,7 @@ XdsHealthStatus GetEndpointHealthStatus(const EndpointAddresses& endpoint) {
 }
 
 // Wraps the endpoint iterator and filters out endpoints in state DRAINING.
-class ChildEndpointIterator : public EndpointAddressesIterator {
+class ChildEndpointIterator final : public EndpointAddressesIterator {
  public:
   explicit ChildEndpointIterator(
       std::shared_ptr<EndpointAddressesIterator> parent_it)
@@ -1251,7 +1252,7 @@ void XdsOverrideHostLb::SubchannelEntry::OnSubchannelWrapperOrphan(
 // factory
 //
 
-class XdsOverrideHostLbFactory : public LoadBalancingPolicyFactory {
+class XdsOverrideHostLbFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/load_balancing/xds/xds_override_host.h

@@ -31,7 +31,7 @@
 namespace grpc_core {
 
 // Config for stateful session LB policy.
-class XdsOverrideHostLbConfig : public LoadBalancingPolicy::Config {
+class XdsOverrideHostLbConfig final : public LoadBalancingPolicy::Config {
  public:
   XdsOverrideHostLbConfig() = default;
 

src/core/load_balancing/xds/xds_wrr_locality.cc

@@ -61,7 +61,7 @@ namespace {
 constexpr absl::string_view kXdsWrrLocality = "xds_wrr_locality_experimental";
 
 // Config for xds_wrr_locality LB policy.
-class XdsWrrLocalityLbConfig : public LoadBalancingPolicy::Config {
+class XdsWrrLocalityLbConfig final : public LoadBalancingPolicy::Config {
  public:
   XdsWrrLocalityLbConfig() = default;
 
@@ -106,7 +106,7 @@ class XdsWrrLocalityLbConfig : public LoadBalancingPolicy::Config {
 };
 
 // xds_wrr_locality LB policy.
-class XdsWrrLocalityLb : public LoadBalancingPolicy {
+class XdsWrrLocalityLb final : public LoadBalancingPolicy {
  public:
   explicit XdsWrrLocalityLb(Args args);
 
@@ -273,7 +273,7 @@ OrphanablePtr<LoadBalancingPolicy> XdsWrrLocalityLb::CreateChildPolicyLocked(
 // factory
 //
 
-class XdsWrrLocalityLbFactory : public LoadBalancingPolicyFactory {
+class XdsWrrLocalityLbFactory final : public LoadBalancingPolicyFactory {
  public:
   OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
       LoadBalancingPolicy::Args args) const override {

src/core/resolver/binder/binder_resolver.cc

@@ -57,7 +57,7 @@
 namespace grpc_core {
 namespace {
 
-class BinderResolver : public Resolver {
+class BinderResolver final : public Resolver {
  public:
   BinderResolver(EndpointAddressesList addresses, ResolverArgs args)
       : result_handler_(std::move(args.result_handler)),
@@ -80,7 +80,7 @@ class BinderResolver : public Resolver {
   ChannelArgs channel_args_;
 };
 
-class BinderResolverFactory : public ResolverFactory {
+class BinderResolverFactory final : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "binder"; }
 

src/core/resolver/dns/c_ares/dns_resolver_ares.cc

@@ -82,7 +82,7 @@ namespace grpc_core {
 
 namespace {
 
-class AresClientChannelDNSResolver : public PollingResolver {
+class AresClientChannelDNSResolver final : public PollingResolver {
  public:
   AresClientChannelDNSResolver(ResolverArgs args,
                                Duration min_time_between_resolutions);
@@ -90,7 +90,8 @@ class AresClientChannelDNSResolver : public PollingResolver {
   OrphanablePtr<Orphanable> StartRequest() override;
 
  private:
-  class AresRequestWrapper : public InternallyRefCounted<AresRequestWrapper> {
+  class AresRequestWrapper final
+      : public InternallyRefCounted<AresRequestWrapper> {
    public:
     explicit AresRequestWrapper(
         RefCountedPtr<AresClientChannelDNSResolver> resolver)
@@ -342,7 +343,7 @@ AresClientChannelDNSResolver::AresRequestWrapper::OnResolvedLocked(
 // Factory
 //
 
-class AresClientChannelDNSResolverFactory : public ResolverFactory {
+class AresClientChannelDNSResolverFactory final : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "dns"; }
 
@@ -365,7 +366,7 @@ class AresClientChannelDNSResolverFactory : public ResolverFactory {
   }
 };
 
-class AresDNSResolver : public DNSResolver {
+class AresDNSResolver final : public DNSResolver {
  public:
   // Abstract class that centralizes common request handling logic via the
   // template method pattern.
@@ -485,7 +486,7 @@ class AresDNSResolver : public DNSResolver {
     grpc_pollset_set* pollset_set_;
   };
 
-  class AresHostnameRequest : public AresRequest {
+  class AresHostnameRequest final : public AresRequest {
    public:
     AresHostnameRequest(
         absl::string_view name, absl::string_view default_port,
@@ -538,7 +539,7 @@ class AresDNSResolver : public DNSResolver {
     std::unique_ptr<EndpointAddressesList> addresses_;
   };
 
-  class AresSRVRequest : public AresRequest {
+  class AresSRVRequest final : public AresRequest {
    public:
     AresSRVRequest(
         absl::string_view name, absl::string_view name_server, Duration timeout,
@@ -586,7 +587,7 @@ class AresDNSResolver : public DNSResolver {
     std::unique_ptr<EndpointAddressesList> balancer_addresses_;
   };
 
-  class AresTXTRequest : public AresRequest {
+  class AresTXTRequest final : public AresRequest {
    public:
     AresTXTRequest(absl::string_view name, absl::string_view name_server,
                    Duration timeout, grpc_pollset_set* interested_parties,

src/core/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc

@@ -51,7 +51,7 @@
 
 namespace grpc_core {
 
-class GrpcPolledFdPosix : public GrpcPolledFd {
+class GrpcPolledFdPosix final : public GrpcPolledFd {
  public:
   GrpcPolledFdPosix(ares_socket_t as, grpc_pollset_set* driver_pollset_set)
       : name_(absl::StrCat("c-ares fd: ", static_cast<int>(as))), as_(as) {
@@ -105,7 +105,7 @@ class GrpcPolledFdPosix : public GrpcPolledFd {
   grpc_pollset_set* driver_pollset_set_ ABSL_GUARDED_BY(&grpc_ares_request::mu);
 };
 
-class GrpcPolledFdFactoryPosix : public GrpcPolledFdFactory {
+class GrpcPolledFdFactoryPosix final : public GrpcPolledFdFactory {
  public:
   ~GrpcPolledFdFactoryPosix() override {
     for (auto& fd : owned_fds_) {

src/core/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc

@@ -70,7 +70,7 @@ namespace {
 // c-ares should read, it must do so by calling SetWSAError() on the
 // WSAErrorContext instance passed to it. A WSAErrorContext must only be
 // instantiated at the top of the virtual socket function callstack.
-class WSAErrorContext {
+class WSAErrorContext final {
  public:
   explicit WSAErrorContext(){};
 
@@ -99,7 +99,7 @@ class WSAErrorContext {
 // from c-ares and are used with the grpc windows poller, and it, e.g.,
 // manufactures virtual socket error codes when it e.g. needs to tell the c-ares
 // library to wait for an async read.
-class GrpcPolledFdWindows : public GrpcPolledFd {
+class GrpcPolledFdWindows final : public GrpcPolledFd {
  public:
   enum WriteState {
     WRITE_IDLE,
@@ -694,7 +694,7 @@ class GrpcPolledFdWindows : public GrpcPolledFd {
   absl::AnyInvocable<void()> on_shutdown_locked_;
 };
 
-class GrpcPolledFdFactoryWindows : public GrpcPolledFdFactory {
+class GrpcPolledFdFactoryWindows final : public GrpcPolledFdFactory {
  public:
   explicit GrpcPolledFdFactoryWindows(Mutex* mu) : mu_(mu) {}
 

src/core/resolver/dns/c_ares/grpc_ares_wrapper.cc

@@ -166,7 +166,7 @@ static void grpc_ares_request_unref_locked(grpc_ares_request* r)
 // organize per-query and per-resolution information in such a way
 // that doesn't involve allocating a number of different data
 // structures.
-class GrpcAresQuery {
+class GrpcAresQuery final {
  public:
   explicit GrpcAresQuery(grpc_ares_request* r, const std::string& name)
       : r_(r), name_(name) {

src/core/resolver/dns/event_engine/event_engine_client_channel_resolver.cc

@@ -92,7 +92,7 @@ TraceFlag grpc_event_engine_client_channel_resolver_trace(
 // ----------------------------------------------------------------------------
 // EventEngineClientChannelDNSResolver
 // ----------------------------------------------------------------------------
-class EventEngineClientChannelDNSResolver : public PollingResolver {
+class EventEngineClientChannelDNSResolver final : public PollingResolver {
  public:
   EventEngineClientChannelDNSResolver(ResolverArgs args,
                                       Duration min_time_between_resolutions);
@@ -102,7 +102,7 @@ class EventEngineClientChannelDNSResolver : public PollingResolver {
   // ----------------------------------------------------------------------------
   // EventEngineDNSRequestWrapper declaration
   // ----------------------------------------------------------------------------
-  class EventEngineDNSRequestWrapper
+  class EventEngineDNSRequestWrapper final
       : public InternallyRefCounted<EventEngineDNSRequestWrapper> {
    public:
     EventEngineDNSRequestWrapper(

src/core/resolver/dns/event_engine/event_engine_client_channel_resolver.h

@@ -23,7 +23,9 @@
 #include "src/core/lib/uri/uri_parser.h"
 
 namespace grpc_core {
-class EventEngineClientChannelDNSResolverFactory : public ResolverFactory {
+
+class EventEngineClientChannelDNSResolverFactory final
+    : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "dns"; }
   bool IsValidUri(const URI& uri) const override;

src/core/resolver/dns/native/dns_resolver.cc

@@ -59,7 +59,7 @@ namespace {
 
 TraceFlag grpc_trace_dns_resolver(false, "dns_resolver");
 
-class NativeClientChannelDNSResolver : public PollingResolver {
+class NativeClientChannelDNSResolver final : public PollingResolver {
  public:
   NativeClientChannelDNSResolver(ResolverArgs args,
                                  Duration min_time_between_resolutions);
@@ -71,7 +71,7 @@ class NativeClientChannelDNSResolver : public PollingResolver {
   // No-op request class, used so that the PollingResolver code knows
   // when there is a request in flight, even if the request is not
   // actually cancellable.
-  class Request : public Orphanable {
+  class Request final : public Orphanable {
    public:
     Request() = default;
 
@@ -145,7 +145,7 @@ void NativeClientChannelDNSResolver::OnResolved(
 // Factory
 //
 
-class NativeClientChannelDNSResolverFactory : public ResolverFactory {
+class NativeClientChannelDNSResolverFactory final : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "dns"; }
 

src/core/resolver/endpoint_addresses.h

@@ -45,7 +45,7 @@ namespace grpc_core {
 // A list of addresses for a given endpoint with an associated set of channel
 // args.  Any args present here will be merged into the channel args when a
 // subchannel is created for each address.
-class EndpointAddresses {
+class EndpointAddresses final {
  public:
   // For backward compatibility.
   // TODO(roth): Remove when callers have been updated.
@@ -102,7 +102,7 @@ struct ResolvedAddressLessThan {
                   const grpc_resolved_address& addr2) const;
 };
 
-class EndpointAddressSet {
+class EndpointAddressSet final {
  public:
   explicit EndpointAddressSet(
       const std::vector<grpc_resolved_address>& addresses)
@@ -128,7 +128,7 @@ class EndpointAddressesIterator {
 };
 
 // Iterator over a fixed list of endpoints.
-class EndpointAddressesListIterator : public EndpointAddressesIterator {
+class EndpointAddressesListIterator final : public EndpointAddressesIterator {
  public:
   explicit EndpointAddressesListIterator(EndpointAddressesList endpoints)
       : endpoints_(std::move(endpoints)) {}
@@ -145,7 +145,7 @@ class EndpointAddressesListIterator : public EndpointAddressesIterator {
 };
 
 // Iterator that returns only a single endpoint.
-class SingleEndpointIterator : public EndpointAddressesIterator {
+class SingleEndpointIterator final : public EndpointAddressesIterator {
  public:
   explicit SingleEndpointIterator(EndpointAddresses endpoint)
       : endpoint_(std::move(endpoint)) {}

src/core/resolver/fake/fake_resolver.cc

@@ -42,7 +42,7 @@ namespace grpc_core {
 
 // This cannot be in an anonymous namespace, because it is a friend of
 // FakeResolverResponseGenerator.
-class FakeResolver : public Resolver {
+class FakeResolver final : public Resolver {
  public:
   explicit FakeResolver(ResolverArgs args);
 
@@ -232,7 +232,7 @@ const grpc_arg_pointer_vtable
 
 namespace {
 
-class FakeResolverFactory : public ResolverFactory {
+class FakeResolverFactory final : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "fake"; }
 

src/core/resolver/fake/fake_resolver.h

@@ -49,7 +49,7 @@ class FakeResolver;
 // instead of RefCounted, but external refs are currently needed to
 // encode this in channel args.  Once channel_args are converted to C++,
 // see if we can find a way to fix this.
-class FakeResolverResponseGenerator
+class FakeResolverResponseGenerator final
     : public RefCounted<FakeResolverResponseGenerator> {
  public:
   static const grpc_arg_pointer_vtable kChannelArgPointerVtable;

src/core/resolver/google_c2p/google_c2p_resolver.cc

@@ -59,7 +59,7 @@ namespace {
 
 const char* kC2PAuthority = "traffic-director-c2p.xds.googleapis.com";
 
-class GoogleCloud2ProdResolver : public Resolver {
+class GoogleCloud2ProdResolver final : public Resolver {
  public:
   explicit GoogleCloud2ProdResolver(ResolverArgs args);
 
@@ -276,7 +276,7 @@ void GoogleCloud2ProdResolver::StartXdsResolver() {
 // Factory
 //
 
-class GoogleCloud2ProdResolverFactory : public ResolverFactory {
+class GoogleCloud2ProdResolverFactory final : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "google-c2p"; }
 
@@ -296,7 +296,8 @@ class GoogleCloud2ProdResolverFactory : public ResolverFactory {
 
 // TODO(apolcyn): remove this class after user code has updated to the
 // stable "google-c2p" URI scheme.
-class ExperimentalGoogleCloud2ProdResolverFactory : public ResolverFactory {
+class ExperimentalGoogleCloud2ProdResolverFactory final
+    : public ResolverFactory {
  public:
   absl::string_view scheme() const override {
     return "google-c2p-experimental";

src/core/resolver/resolver_registry.h

@@ -35,7 +35,7 @@
 
 namespace grpc_core {
 
-class ResolverRegistry {
+class ResolverRegistry final {
  private:
   // Forward declaration needed to use this in Builder.
   struct State {
@@ -47,7 +47,7 @@ class ResolverRegistry {
   /// Methods used to create and populate the ResolverRegistry.
   /// NOT THREAD SAFE -- to be used only during global gRPC
   /// initialization and shutdown.
-  class Builder {
+  class Builder final {
    public:
     Builder();
 

src/core/resolver/sockaddr/sockaddr_resolver.cc

@@ -42,7 +42,7 @@ namespace grpc_core {
 
 namespace {
 
-class SockaddrResolver : public Resolver {
+class SockaddrResolver final : public Resolver {
  public:
   SockaddrResolver(EndpointAddressesList addresses, ResolverArgs args);
 
@@ -110,7 +110,7 @@ OrphanablePtr<Resolver> CreateSockaddrResolver(
                                           std::move(args));
 }
 
-class IPv4ResolverFactory : public ResolverFactory {
+class IPv4ResolverFactory final : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "ipv4"; }
 
@@ -123,7 +123,7 @@ class IPv4ResolverFactory : public ResolverFactory {
   }
 };
 
-class IPv6ResolverFactory : public ResolverFactory {
+class IPv6ResolverFactory final : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "ipv6"; }
 
@@ -137,7 +137,7 @@ class IPv6ResolverFactory : public ResolverFactory {
 };
 
 #ifdef GRPC_HAVE_UNIX_SOCKET
-class UnixResolverFactory : public ResolverFactory {
+class UnixResolverFactory final : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "unix"; }
 
@@ -150,7 +150,7 @@ class UnixResolverFactory : public ResolverFactory {
   }
 };
 
-class UnixAbstractResolverFactory : public ResolverFactory {
+class UnixAbstractResolverFactory final : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "unix-abstract"; }
 
@@ -165,7 +165,7 @@ class UnixAbstractResolverFactory : public ResolverFactory {
 #endif  // GRPC_HAVE_UNIX_SOCKET
 
 #ifdef GRPC_HAVE_VSOCK
-class VSockResolverFactory : public ResolverFactory {
+class VSockResolverFactory final : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "vsock"; }
 

src/core/resolver/xds/xds_dependency_manager.cc

@@ -105,7 +105,7 @@ std::string XdsDependencyManager::XdsConfig::ToString() const {
 // XdsDependencyManager::ListenerWatcher
 //
 
-class XdsDependencyManager::ListenerWatcher
+class XdsDependencyManager::ListenerWatcher final
     : public XdsListenerResourceType::WatcherInterface {
  public:
   explicit ListenerWatcher(RefCountedPtr<XdsDependencyManager> dependency_mgr)
@@ -154,7 +154,7 @@ class XdsDependencyManager::ListenerWatcher
 // XdsDependencyManager::RouteConfigWatcher
 //
 
-class XdsDependencyManager::RouteConfigWatcher
+class XdsDependencyManager::RouteConfigWatcher final
     : public XdsRouteConfigResourceType::WatcherInterface {
  public:
   RouteConfigWatcher(RefCountedPtr<XdsDependencyManager> dependency_mgr,
@@ -206,7 +206,7 @@ class XdsDependencyManager::RouteConfigWatcher
 // XdsDependencyManager::ClusterWatcher
 //
 
-class XdsDependencyManager::ClusterWatcher
+class XdsDependencyManager::ClusterWatcher final
     : public XdsClusterResourceType::WatcherInterface {
  public:
   ClusterWatcher(RefCountedPtr<XdsDependencyManager> dependency_mgr,
@@ -255,7 +255,7 @@ class XdsDependencyManager::ClusterWatcher
 // XdsDependencyManager::EndpointWatcher
 //
 
-class XdsDependencyManager::EndpointWatcher
+class XdsDependencyManager::EndpointWatcher final
     : public XdsEndpointResourceType::WatcherInterface {
  public:
   EndpointWatcher(RefCountedPtr<XdsDependencyManager> dependency_mgr,
@@ -306,7 +306,8 @@ class XdsDependencyManager::EndpointWatcher
 // XdsDependencyManager::DnsResultHandler
 //
 
-class XdsDependencyManager::DnsResultHandler : public Resolver::ResultHandler {
+class XdsDependencyManager::DnsResultHandler final
+    : public Resolver::ResultHandler {
  public:
   DnsResultHandler(RefCountedPtr<XdsDependencyManager> dependency_mgr,
                    std::string name)
@@ -468,7 +469,8 @@ void XdsDependencyManager::OnListenerUpdate(
 
 namespace {
 
-class XdsVirtualHostListIterator : public XdsRouting::VirtualHostListIterator {
+class XdsVirtualHostListIterator final
+    : public XdsRouting::VirtualHostListIterator {
  public:
   explicit XdsVirtualHostListIterator(
       const std::vector<XdsRouteConfigResource::VirtualHost>* virtual_hosts)

src/core/resolver/xds/xds_dependency_manager.h

@@ -35,7 +35,7 @@ namespace grpc_core {
 
 // Watches all xDS resources and handles dependencies between them.
 // Reports updates only when all necessary resources have been obtained.
-class XdsDependencyManager : public RefCounted<XdsDependencyManager>,
+class XdsDependencyManager final : public RefCounted<XdsDependencyManager>,
                                    public Orphanable {
  public:
   struct XdsConfig : public RefCounted<XdsConfig> {
@@ -117,7 +117,7 @@ class XdsDependencyManager : public RefCounted<XdsDependencyManager>,
     virtual void OnResourceDoesNotExist(std::string context) = 0;
   };
 
-  class ClusterSubscription : public DualRefCounted<ClusterSubscription> {
+  class ClusterSubscription final : public DualRefCounted<ClusterSubscription> {
    public:
     ClusterSubscription(absl::string_view cluster_name,
                         RefCountedPtr<XdsDependencyManager> dependency_mgr)

src/core/resolver/xds/xds_resolver.cc

@@ -102,7 +102,7 @@ namespace {
 // XdsResolver
 //
 
-class XdsResolver : public Resolver {
+class XdsResolver final : public Resolver {
  public:
   XdsResolver(ResolverArgs args, std::string data_plane_authority)
       : work_serializer_(std::move(args.work_serializer)),
@@ -135,7 +135,7 @@ class XdsResolver : public Resolver {
   }
 
  private:
-  class XdsWatcher : public XdsDependencyManager::Watcher {
+  class XdsWatcher final : public XdsDependencyManager::Watcher {
    public:
     explicit XdsWatcher(RefCountedPtr<XdsResolver> resolver)
         : resolver_(std::move(resolver)) {}
@@ -163,7 +163,7 @@ class XdsResolver : public Resolver {
   // the cluster by the ConfigSelector.  The ref for each call is held
   // until the call is committed.  When the strong refs go away, we hop
   // back into the WorkSerializer to remove the entry from the map.
-  class ClusterRef : public DualRefCounted<ClusterRef> {
+  class ClusterRef final : public DualRefCounted<ClusterRef> {
    public:
     ClusterRef(RefCountedPtr<XdsResolver> resolver,
                RefCountedPtr<XdsDependencyManager::ClusterSubscription>
@@ -196,7 +196,7 @@ class XdsResolver : public Resolver {
   // XdsConfigSelector. A ref to this map will be taken by each call processed
   // by the XdsConfigSelector, stored in a the call's call attributes, and later
   // unreffed by the ClusterSelection filter.
-  class RouteConfigData : public RefCounted<RouteConfigData> {
+  class RouteConfigData final : public RefCounted<RouteConfigData> {
    public:
     struct RouteEntry {
       struct ClusterWeightState {
@@ -266,7 +266,7 @@ class XdsResolver : public Resolver {
     std::vector<RouteEntry> routes_;
   };
 
-  class XdsConfigSelector : public ConfigSelector {
+  class XdsConfigSelector final : public ConfigSelector {
    public:
     XdsConfigSelector(RefCountedPtr<XdsResolver> resolver,
                       RefCountedPtr<RouteConfigData> route_config_data);
@@ -293,7 +293,7 @@ class XdsResolver : public Resolver {
     std::vector<const grpc_channel_filter*> filters_;
   };
 
-  class XdsRouteStateAttributeImpl : public XdsRouteStateAttribute {
+  class XdsRouteStateAttributeImpl final : public XdsRouteStateAttribute {
    public:
     explicit XdsRouteStateAttributeImpl(
         RefCountedPtr<RouteConfigData> route_config_data,
@@ -312,7 +312,7 @@ class XdsResolver : public Resolver {
     RouteConfigData::RouteEntry* route_;
   };
 
-  class ClusterSelectionFilter
+  class ClusterSelectionFilter final
       : public ImplementChannelFilter<ClusterSelectionFilter> {
    public:
     const static grpc_channel_filter kFilter;
@@ -398,7 +398,7 @@ const NoInterceptor XdsResolver::ClusterSelectionFilter::Call::OnFinalize;
 
 // Implementation of XdsRouting::RouteListIterator for getting the matching
 // route for a request.
-class XdsResolver::RouteConfigData::RouteListIterator
+class XdsResolver::RouteConfigData::RouteListIterator final
     : public XdsRouting::RouteListIterator {
  public:
   explicit RouteListIterator(const RouteConfigData* route_table)
@@ -1097,7 +1097,7 @@ void XdsResolver::MaybeRemoveUnusedClusters() {
 // XdsResolverFactory
 //
 
-class XdsResolverFactory : public ResolverFactory {
+class XdsResolverFactory final : public ResolverFactory {
  public:
   absl::string_view scheme() const override { return "xds"; }
 

src/core/resolver/xds/xds_resolver_attributes.h

@@ -26,7 +26,7 @@
 
 namespace grpc_core {
 
-class XdsClusterAttribute
+class XdsClusterAttribute final
     : public ServiceConfigCallData::CallAttributeInterface {
  public:
   static UniqueTypeName TypeName() {

src/core/service_config/service_config_channel_arg_filter.cc

@@ -54,7 +54,7 @@ namespace grpc_core {
 
 namespace {
 
-class ServiceConfigChannelArgFilter
+class ServiceConfigChannelArgFilter final
     : public ImplementChannelFilter<ServiceConfigChannelArgFilter> {
  public:
   static const grpc_channel_filter kFilter;

src/core/service_config/service_config_parser.h

@@ -68,7 +68,7 @@ class ServiceConfigParser {
   using ServiceConfigParserList = std::vector<std::unique_ptr<Parser>>;
   using ParsedConfigVector = std::vector<std::unique_ptr<ParsedConfig>>;
 
-  class Builder {
+  class Builder final {
    public:
     /// Globally register a service config parser. Each new service config
     /// update will go through all the registered parser. Each parser is