From ecc2bbac3bfd81950d4ea6fce4b7b7003abfd3c1 Mon Sep 17 00:00:00 2001
From: Craig Tiller <ctiller@google.com>
Date: Tue, 2 Jan 2024 10:02:03 -0800
Subject: [PATCH] [call-v3] Move `XdsResolver::ClusterSelectionFilter` to v3
 api (#35419)

Omit experiments due to trivial refactor

Closes #35419

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/35419 from ctiller:xds1 4c639752a03d75d31262ab05ae630afc07cb1cbc
PiperOrigin-RevId: 595144625
---
 .../resolver/xds/xds_resolver.cc              | 30 ++++++++++++++-----
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/src/core/ext/filters/client_channel/resolver/xds/xds_resolver.cc b/src/core/ext/filters/client_channel/resolver/xds/xds_resolver.cc
index 732f07169bc..9cc094f0499 100644
--- a/src/core/ext/filters/client_channel/resolver/xds/xds_resolver.cc
+++ b/src/core/ext/filters/client_channel/resolver/xds/xds_resolver.cc
@@ -312,7 +312,8 @@ class XdsResolver : public Resolver {
     RouteConfigData::RouteEntry* route_;
   };
 
-  class ClusterSelectionFilter : public ChannelFilter {
+  class ClusterSelectionFilter
+      : public ImplementChannelFilter<ClusterSelectionFilter> {
    public:
     const static grpc_channel_filter kFilter;
 
@@ -322,8 +323,15 @@ class XdsResolver : public Resolver {
     }
 
     // Construct a promise for one call.
-    ArenaPromise<ServerMetadataHandle> MakeCallPromise(
-        CallArgs call_args, NextPromiseFactory next_promise_factory) override;
+    class Call {
+     public:
+      void OnClientInitialMetadata(ClientMetadata& md);
+      static const NoInterceptor OnServerInitialMetadata;
+      static const NoInterceptor OnServerTrailingMetadata;
+      static const NoInterceptor OnClientToServerMessage;
+      static const NoInterceptor OnServerToClientMessage;
+      static const NoInterceptor OnFinalize;
+    };
 
    private:
     explicit ClusterSelectionFilter(ChannelFilter::Args filter_args)
@@ -374,6 +382,16 @@ class XdsResolver : public Resolver {
   std::map<absl::string_view, WeakRefCountedPtr<ClusterRef>> cluster_ref_map_;
 };
 
+const NoInterceptor
+    XdsResolver::ClusterSelectionFilter::Call::OnServerInitialMetadata;
+const NoInterceptor
+    XdsResolver::ClusterSelectionFilter::Call::OnServerTrailingMetadata;
+const NoInterceptor
+    XdsResolver::ClusterSelectionFilter::Call::OnClientToServerMessage;
+const NoInterceptor
+    XdsResolver::ClusterSelectionFilter::Call::OnServerToClientMessage;
+const NoInterceptor XdsResolver::ClusterSelectionFilter::Call::OnFinalize;
+
 //
 // XdsResolver::RouteConfigData::RouteListIterator
 //
@@ -835,9 +853,8 @@ const grpc_channel_filter XdsResolver::ClusterSelectionFilter::kFilter =
                            kFilterExaminesServerInitialMetadata>(
         "cluster_selection_filter");
 
-ArenaPromise<ServerMetadataHandle>
-XdsResolver::ClusterSelectionFilter::MakeCallPromise(
-    CallArgs call_args, NextPromiseFactory next_promise_factory) {
+void XdsResolver::ClusterSelectionFilter::Call::OnClientInitialMetadata(
+    ClientMetadata&) {
   auto* service_config_call_data =
       static_cast<ClientChannelServiceConfigCallData*>(
           GetContext<grpc_call_context_element>()
@@ -856,7 +873,6 @@ XdsResolver::ClusterSelectionFilter::MakeCallPromise(
           [cluster = std::move(cluster)]() mutable { cluster.reset(); });
     }
   }
-  return next_promise_factory(std::move(call_args));
 }
 
 //