Revert "[svc-cfg] Move ServiceConfigChannelArgFilter to promises" (#33508)

Reverts grpc/grpc#33473 as it caused an internal test breakage.

BUILD

@@ -3033,14 +3033,12 @@ grpc_cc_library(
         "xds_orca_service_upb",
         "xds_orca_upb",
         "//src/core:arena",
-        "//src/core:arena_promise",
         "//src/core:channel_args",
         "//src/core:channel_fwd",
         "//src/core:channel_init",
         "//src/core:channel_stack_type",
         "//src/core:closure",
         "//src/core:construct_destruct",
-        "//src/core:context",
         "//src/core:delegating_helper",
         "//src/core:dual_ref_counted",
         "//src/core:env",

src/core/ext/filters/client_channel/service_config_channel_arg_filter.cc

@@ -19,8 +19,7 @@
 
 #include <grpc/support/port_platform.h>
 
-#include <functional>
-#include <memory>
+#include <new>
 #include <string>
 #include <utility>
 
@@ -35,12 +34,10 @@
 #include "src/core/lib/channel/channel_fwd.h"
 #include "src/core/lib/channel/channel_stack.h"
 #include "src/core/lib/channel/channel_stack_builder.h"
-#include "src/core/lib/channel/context.h"
-#include "src/core/lib/channel/promise_based_filter.h"
 #include "src/core/lib/config/core_configuration.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
-#include "src/core/lib/promise/arena_promise.h"
-#include "src/core/lib/promise/context.h"
+#include "src/core/lib/iomgr/closure.h"
+#include "src/core/lib/iomgr/error.h"
 #include "src/core/lib/resource_quota/arena.h"
 #include "src/core/lib/service_config/service_config.h"
 #include "src/core/lib/service_config/service_config_call_data.h"
@@ -48,25 +45,20 @@
 #include "src/core/lib/service_config/service_config_parser.h"
 #include "src/core/lib/surface/channel_init.h"
 #include "src/core/lib/surface/channel_stack_type.h"
-#include "src/core/lib/transport/metadata_batch.h"
-#include "src/core/lib/transport/transport.h"
 
 namespace grpc_core {
 
 namespace {
 
-class ServiceConfigChannelArgFilter : public ChannelFilter {
+class ServiceConfigChannelArgChannelData {
  public:
-  static absl::StatusOr<ServiceConfigChannelArgFilter> Create(
-      const ChannelArgs& args, ChannelFilter::Args) {
-    return ServiceConfigChannelArgFilter(args);
-  }
-
-  explicit ServiceConfigChannelArgFilter(const ChannelArgs& args) {
-    auto service_config_str = args.GetOwnedString(GRPC_ARG_SERVICE_CONFIG);
+  explicit ServiceConfigChannelArgChannelData(
+      const grpc_channel_element_args* args) {
+    auto service_config_str =
+        args->channel_args.GetOwnedString(GRPC_ARG_SERVICE_CONFIG);
     if (service_config_str.has_value()) {
-      auto service_config =
-          ServiceConfigImpl::Create(args, *service_config_str);
+      auto service_config = ServiceConfigImpl::Create(
+          args->channel_args, service_config_str->c_str());
       if (!service_config.ok()) {
         gpr_log(GPR_ERROR, "%s", service_config.status().ToString().c_str());
       } else {
@@ -75,34 +67,62 @@ class ServiceConfigChannelArgFilter : public ChannelFilter {
     }
   }
 
-  // Construct a promise for one call.
-  ArenaPromise<ServerMetadataHandle> MakeCallPromise(
-      CallArgs call_args, NextPromiseFactory next_promise_factory) override;
+  RefCountedPtr<ServiceConfig> service_config() const {
+    return service_config_;
+  }
 
  private:
   RefCountedPtr<ServiceConfig> service_config_;
 };
 
-ArenaPromise<ServerMetadataHandle>
-ServiceConfigChannelArgFilter::MakeCallPromise(
-    CallArgs call_args, NextPromiseFactory next_promise_factory) {
+grpc_error_handle ServiceConfigChannelArgInitCallElem(
+    grpc_call_element* elem, const grpc_call_element_args* args) {
+  auto* chand =
+      static_cast<ServiceConfigChannelArgChannelData*>(elem->channel_data);
+  RefCountedPtr<ServiceConfig> service_config = chand->service_config();
   const ServiceConfigParser::ParsedConfigVector* method_configs = nullptr;
-  if (service_config_ != nullptr) {
-    method_configs = service_config_->GetMethodParsedConfigVector(
-        call_args.client_initial_metadata->get_pointer(HttpPathMetadata())
-            ->c_slice());
+  if (service_config != nullptr) {
+    method_configs = service_config->GetMethodParsedConfigVector(args->path);
   }
-  auto* arena = GetContext<Arena>();
-  auto* service_config_call_data = arena->New<ServiceConfigCallData>(
-      arena, GetContext<grpc_call_context_element>());
-  service_config_call_data->SetServiceConfig(service_config_, method_configs);
-  return next_promise_factory(std::move(call_args));
+  auto* service_config_call_data =
+      args->arena->New<ServiceConfigCallData>(args->arena, args->context);
+  service_config_call_data->SetServiceConfig(std::move(service_config),
+                                             method_configs);
+  return absl::OkStatus();
 }
 
-const grpc_channel_filter kServiceConfigChannelArgFilter =
-    MakePromiseBasedFilter<ServiceConfigChannelArgFilter,
-                           FilterEndpoint::kClient>(
-        "service_config_channel_arg");
+void ServiceConfigChannelArgDestroyCallElem(
+    grpc_call_element* /*elem*/, const grpc_call_final_info* /*final_info*/,
+    grpc_closure* /*then_schedule_closure*/) {}
+
+grpc_error_handle ServiceConfigChannelArgInitChannelElem(
+    grpc_channel_element* elem, grpc_channel_element_args* args) {
+  ServiceConfigChannelArgChannelData* chand =
+      static_cast<ServiceConfigChannelArgChannelData*>(elem->channel_data);
+  new (chand) ServiceConfigChannelArgChannelData(args);
+  return absl::OkStatus();
+}
+
+void ServiceConfigChannelArgDestroyChannelElem(grpc_channel_element* elem) {
+  ServiceConfigChannelArgChannelData* chand =
+      static_cast<ServiceConfigChannelArgChannelData*>(elem->channel_data);
+  chand->~ServiceConfigChannelArgChannelData();
+}
+
+const grpc_channel_filter ServiceConfigChannelArgFilter = {
+    grpc_call_next_op,
+    nullptr,
+    grpc_channel_next_op,
+    0,
+    ServiceConfigChannelArgInitCallElem,
+    grpc_call_stack_ignore_set_pollset_or_pollset_set,
+    ServiceConfigChannelArgDestroyCallElem,
+    sizeof(ServiceConfigChannelArgChannelData),
+    ServiceConfigChannelArgInitChannelElem,
+    grpc_channel_stack_no_post_init,
+    ServiceConfigChannelArgDestroyChannelElem,
+    grpc_channel_next_get_info,
+    "service_config_channel_arg"};
 
 }  // namespace
 
@@ -116,7 +136,7 @@ void RegisterServiceConfigChannelArgFilter(
             !channel_args.GetString(GRPC_ARG_SERVICE_CONFIG).has_value()) {
           return true;
         }
-        builder->PrependFilter(&kServiceConfigChannelArgFilter);
+        builder->PrependFilter(&ServiceConfigChannelArgFilter);
         return true;
       });
 }