convert filter - still need to add integration glue to pbf

src/core/lib/security/transport/auth_filters.h

@@ -62,23 +62,56 @@ class ClientAuthFilter final : public ChannelFilter {
   grpc_call_credentials::GetRequestMetadataArgs args_;
 };
 
-class ServerAuthFilter final : public ChannelFilter {
+class ServerAuthFilter final : public ImplementChannelFilter<ServerAuthFilter> {
+ private:
+  ServerAuthFilter(RefCountedPtr<grpc_server_credentials> server_credentials,
+                   RefCountedPtr<grpc_auth_context> auth_context);
+
+  class RunApplicationCode {
+   public:
+    RunApplicationCode(ServerAuthFilter* filter, ClientMetadata& metadata);
+
+    RunApplicationCode(const RunApplicationCode&) = delete;
+    RunApplicationCode& operator=(const RunApplicationCode&) = delete;
+    RunApplicationCode(RunApplicationCode&& other) noexcept
+        : state_(std::exchange(other.state_, nullptr)) {}
+    RunApplicationCode& operator=(RunApplicationCode&& other) noexcept {
+      state_ = std::exchange(other.state_, nullptr);
+      return *this;
+    }
+
+    Poll<absl::Status> operator()();
+
+   private:
+    struct State;
+    State* state_;
+  };
+
  public:
   static const grpc_channel_filter kFilter;
 
   static absl::StatusOr<ServerAuthFilter> Create(const ChannelArgs& args,
                                                  ChannelFilter::Args);
 
-  // Construct a promise for one call.
-  ArenaPromise<ServerMetadataHandle> MakeCallPromise(
-      CallArgs call_args, NextPromiseFactory next_promise_factory) override;
+  class Call {
+   public:
+    explicit Call(ServerAuthFilter* filter);
+    auto OnClientInitialMetadata(ClientMetadata& md, ServerAuthFilter* filter) {
+      return If(
+          filter->server_credentials_ == nullptr ||
+              filter->server_credentials_->auth_metadata_processor().process ==
+                  nullptr,
+          ImmediateOkStatus(),
+          [filter, md = &md]() { return RunApplicationCode(filter, *md); });
+    }
+    static const NoInterceptor OnServerInitialMetadata;
+    static const NoInterceptor OnClientToServerMessage;
+    static const NoInterceptor OnServerToClientMessage;
+    static const NoInterceptor OnServerTrailingMetadata;
+    static const NoInterceptor OnFinalize;
+  };
 
  private:
-  ServerAuthFilter(RefCountedPtr<grpc_server_credentials> server_credentials,
-                   RefCountedPtr<grpc_auth_context> auth_context);
-
-  class RunApplicationCode;
-
   ArenaPromise<absl::StatusOr<CallArgs>> GetCallCredsMetadata(
       CallArgs call_args);
 

src/core/lib/security/transport/server_auth_filter.cc

@@ -114,6 +114,7 @@ grpc_metadata_array MetadataBatchToMetadataArray(
 
 }  // namespace
 
+#if 0
 class ServerAuthFilter::RunApplicationCode {
  public:
   // TODO(ctiller): Allocate state_ into a pool on the arena to reuse this
@@ -204,28 +205,20 @@ class ServerAuthFilter::RunApplicationCode {
 
   State* state_;
 };
+#endif
 
-ArenaPromise<ServerMetadataHandle> ServerAuthFilter::MakeCallPromise(
-    CallArgs call_args, NextPromiseFactory next_promise_factory) {
+ServerAuthFilter::Call::Call(ServerAuthFilter* filter) {
   // Create server security context.  Set its auth context from channel
   // data and save it in the call context.
   grpc_server_security_context* server_ctx =
       grpc_server_security_context_create(GetContext<Arena>());
   server_ctx->auth_context =
-      auth_context_->Ref(DEBUG_LOCATION, "server_auth_filter");
+      filter->auth_context_->Ref(DEBUG_LOCATION, "server_auth_filter");
   grpc_call_context_element& context =
       GetContext<grpc_call_context_element>()[GRPC_CONTEXT_SECURITY];
   if (context.value != nullptr) context.destroy(context.value);
   context.value = server_ctx;
   context.destroy = grpc_server_security_context_destroy;
-
-  if (server_credentials_ == nullptr ||
-      server_credentials_->auth_metadata_processor().process == nullptr) {
-    return next_promise_factory(std::move(call_args));
-  }
-
-  return TrySeq(RunApplicationCode(this, std::move(call_args)),
-                std::move(next_promise_factory));
 }
 
 ServerAuthFilter::ServerAuthFilter(