Expose promise-ness to filter proper (#28658)

* Expose promise-ness to filter proper

* Make transports able to export promises too

* Add make promise op to transport

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

@@ -233,6 +233,7 @@ class ClientChannel::CallData {
 
 const grpc_channel_filter ClientChannel::kFilterVtable = {
     ClientChannel::CallData::StartTransportStreamOpBatch,
+    nullptr,
     ClientChannel::StartTransportOp,
     sizeof(ClientChannel::CallData),
     ClientChannel::CallData::Init,
@@ -383,6 +384,7 @@ class DynamicTerminationFilter::CallData {
 
 const grpc_channel_filter DynamicTerminationFilter::kFilterVtable = {
     DynamicTerminationFilter::CallData::StartTransportStreamOpBatch,
+    nullptr,
     DynamicTerminationFilter::StartTransportOp,
     sizeof(DynamicTerminationFilter::CallData),
     DynamicTerminationFilter::CallData::Init,

src/core/ext/filters/client_channel/lb_policy/grpclb/client_load_reporting_filter.cc

@@ -132,6 +132,7 @@ static void clr_start_transport_stream_op_batch(
 
 const grpc_channel_filter grpc_client_load_reporting_filter = {
     clr_start_transport_stream_op_batch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(call_data),
     clr_init_call_elem,

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

@@ -2541,6 +2541,7 @@ void RetryFilter::CallData::OnRetryTimerLocked(void* arg,
 
 const grpc_channel_filter kRetryFilterVtable = {
     RetryFilter::CallData::StartTransportStreamOpBatch,
+    nullptr,
     RetryFilter::StartTransportOp,
     sizeof(RetryFilter::CallData),
     RetryFilter::CallData::Init,

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

@@ -123,6 +123,7 @@ void ServiceConfigChannelArgDestroyChannelElem(grpc_channel_element* elem) {
 
 const grpc_channel_filter ServiceConfigChannelArgFilter = {
     grpc_call_next_op,
+    nullptr,
     grpc_channel_next_op,
     sizeof(ServiceConfigChannelArgCallData),
     ServiceConfigChannelArgInitCallElem,

src/core/ext/filters/client_idle/client_idle_filter.cc

@@ -233,6 +233,7 @@ void CallData::Destroy(grpc_call_element* elem,
 
 const grpc_channel_filter grpc_client_idle_filter = {
     grpc_call_next_op,
+    nullptr,
     ChannelData::StartTransportOp,
     sizeof(CallData),
     CallData::Init,

src/core/ext/filters/deadline/deadline_filter.cc

@@ -338,6 +338,7 @@ static void deadline_server_start_transport_stream_op_batch(
 
 const grpc_channel_filter grpc_client_deadline_filter = {
     deadline_client_start_transport_stream_op_batch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(base_call_data),
     deadline_init_call_elem,
@@ -352,6 +353,7 @@ const grpc_channel_filter grpc_client_deadline_filter = {
 
 const grpc_channel_filter grpc_server_deadline_filter = {
     deadline_server_start_transport_stream_op_batch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(server_call_data),
     deadline_init_call_elem,

src/core/ext/filters/fault_injection/fault_injection_filter.cc

@@ -471,6 +471,7 @@ void CallData::HijackedRecvTrailingMetadataReady(void* arg,
 
 extern const grpc_channel_filter FaultInjectionFilterVtable = {
     CallData::StartTransportStreamOpBatch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(CallData),
     CallData::Init,

src/core/ext/filters/http/client/http_client_filter.cc

@@ -505,6 +505,7 @@ static void http_client_destroy_channel_elem(grpc_channel_element* elem) {
 
 const grpc_channel_filter grpc_http_client_filter = {
     http_client_start_transport_stream_op_batch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(call_data),
     http_client_init_call_elem,

src/core/ext/filters/http/message_compress/message_compress_filter.cc

@@ -443,6 +443,7 @@ void CompressDestroyChannelElem(grpc_channel_element* elem) {
 
 const grpc_channel_filter grpc_message_compress_filter = {
     CompressStartTransportStreamOpBatch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(CallData),
     CompressInitCallElem,

src/core/ext/filters/http/message_compress/message_decompress_filter.cc

@@ -365,6 +365,7 @@ void DecompressDestroyChannelElem(grpc_channel_element* elem) {
 
 const grpc_channel_filter MessageDecompressFilter = {
     DecompressStartTransportStreamOpBatch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(CallData),
     DecompressInitCallElem,

src/core/ext/filters/http/server/http_server_filter.cc

@@ -423,6 +423,7 @@ static void hs_destroy_channel_elem(grpc_channel_element* /*elem*/) {}
 
 const grpc_channel_filter grpc_http_server_filter = {
     hs_start_transport_stream_op_batch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(call_data),
     hs_init_call_elem,

src/core/ext/filters/max_age/max_age_filter.cc

@@ -523,6 +523,7 @@ static void max_age_destroy_channel_elem(grpc_channel_element* elem) {
 
 const grpc_channel_filter grpc_max_age_filter = {
     grpc_call_next_op,
+    nullptr,
     grpc_channel_next_op,
     0, /* sizeof_call_data */
     max_age_init_call_elem,

src/core/ext/filters/message_size/message_size_filter.cc

@@ -330,6 +330,7 @@ static void message_size_destroy_channel_elem(grpc_channel_element* elem) {
 
 const grpc_channel_filter grpc_message_size_filter = {
     message_size_start_transport_stream_op_batch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(call_data),
     message_size_init_call_elem,

src/core/ext/filters/rbac/rbac_filter.cc

@@ -109,6 +109,7 @@ void RbacFilter::CallData::RecvInitialMetadataReady(void* user_data,
 
 const grpc_channel_filter RbacFilter::kFilterVtable = {
     RbacFilter::CallData::StartTransportStreamOpBatch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(RbacFilter::CallData),
     RbacFilter::CallData::Init,

src/core/ext/filters/server_config_selector/server_config_selector_filter.cc

@@ -255,6 +255,7 @@ void CallData::MaybeResumeRecvTrailingMetadataReady() {
 
 const grpc_channel_filter kServerConfigSelectorFilter = {
     CallData::StartTransportStreamOpBatch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(CallData),
     CallData::Init,

src/core/ext/transport/binder/transport/binder_transport.cc

@@ -689,6 +689,7 @@ static grpc_endpoint* get_endpoint(grpc_transport*) {
 static const grpc_transport_vtable vtable = {sizeof(grpc_binder_stream),
                                              "binder",
                                              init_stream,
+                                             nullptr,
                                              set_pollset,
                                              set_pollset_set,
                                              perform_stream_op,

src/core/ext/transport/chttp2/transport/chttp2_transport.cc

@@ -3161,6 +3161,7 @@ static grpc_endpoint* chttp2_get_endpoint(grpc_transport* t) {
 static const grpc_transport_vtable vtable = {sizeof(grpc_chttp2_stream),
                                              "chttp2",
                                              init_stream,
+                                             nullptr,
                                              set_pollset,
                                              set_pollset_set,
                                              perform_stream_op,

src/core/ext/transport/cronet/transport/cronet_transport.cc

@@ -1483,6 +1483,7 @@ static const grpc_transport_vtable grpc_cronet_vtable = {
     sizeof(stream_obj),
     "cronet_http",
     init_stream,
+    nullptr,
     set_pollset_do_nothing,
     set_pollset_set_do_nothing,
     perform_stream_op,

src/core/ext/transport/inproc/inproc_transport.cc

@@ -1212,9 +1212,11 @@ void set_pollset_set(grpc_transport* /*gt*/, grpc_stream* /*gs*/,
 grpc_endpoint* get_endpoint(grpc_transport* /*t*/) { return nullptr; }
 
 const grpc_transport_vtable inproc_vtable = {
-    sizeof(inproc_stream), "inproc",        init_stream,
-    set_pollset,           set_pollset_set, perform_stream_op,
-    perform_transport_op,  destroy_stream,  destroy_transport,
+    sizeof(inproc_stream), "inproc",
+    init_stream,           nullptr,
+    set_pollset,           set_pollset_set,
+    perform_stream_op,     perform_transport_op,
+    destroy_stream,        destroy_transport,
     get_endpoint};
 
 /*******************************************************************************

src/core/lib/channel/channel_stack.h

@@ -48,6 +48,8 @@
 
 #include <stddef.h>
 
+#include <functional>
+
 #include <grpc/grpc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/time.h>
@@ -57,6 +59,7 @@
 #include "src/core/lib/iomgr/call_combiner.h"
 #include "src/core/lib/iomgr/polling_entity.h"
 #include "src/core/lib/resource_quota/arena.h"
+#include "src/core/lib/transport/metadata_batch.h"
 #include "src/core/lib/transport/transport.h"
 
 typedef struct grpc_channel_element grpc_channel_element;
@@ -109,6 +112,19 @@ struct grpc_channel_filter {
      See grpc_call_next_op on how to call the next element in the stack */
   void (*start_transport_stream_op_batch)(grpc_call_element* elem,
                                           grpc_transport_stream_op_batch* op);
+  /* Create a promise to execute one call.
+     If this is non-null, it may be used in preference to
+     start_transport_stream_op_batch.
+     If this is used in preference to start_transport_stream_op_batch, the
+     following can be omitted also:
+       - calling init_call_elem, destroy_call_elem, set_pollset_or_pollset_set
+       - allocation of memory for call data
+     There is an on-going migration to move all filters to providing this, and
+     then to drop start_transport_stream_op_batch. */
+  grpc_core::ArenaPromise<grpc_core::TrailingMetadata> (*make_call_promise)(
+      grpc_channel_element* elem,
+      grpc_core::ClientInitialMetadata initial_metadata,
+      grpc_core::NextPromiseFactory next_promise_factory);
   /* Called to handle channel level operations - e.g. new calls, or transport
      closure.
      See grpc_channel_next_op on how to call the next element in the stack */

src/core/lib/channel/connected_channel.cc

@@ -203,6 +203,7 @@ static void connected_channel_get_channel_info(
 
 const grpc_channel_filter grpc_connected_filter = {
     connected_channel_start_transport_stream_op_batch,
+    nullptr,
     connected_channel_start_transport_op,
     sizeof(call_data),
     connected_channel_init_call_elem,

src/core/lib/channel/promise_based_filter.h

@@ -33,59 +33,6 @@
 
 namespace grpc_core {
 
-namespace promise_filter_detail {
-class BaseCallData;
-};
-
-// Small unowned "handle" type to ensure one accessor at a time to metadata.
-// The focus here is to get promises to use the syntax we'd like - we'll
-// probably substitute some other smart pointer later.
-template <typename T>
-class MetadataHandle {
- public:
-  MetadataHandle() = default;
-
-  MetadataHandle(const MetadataHandle&) = delete;
-  MetadataHandle& operator=(const MetadataHandle&) = delete;
-
-  MetadataHandle(MetadataHandle&& other) noexcept : handle_(other.handle_) {
-    other.handle_ = nullptr;
-  }
-  MetadataHandle& operator=(MetadataHandle&& other) noexcept {
-    handle_ = other.handle_;
-    other.handle_ = nullptr;
-    return *this;
-  }
-
-  T* operator->() const { return handle_; }
-  bool has_value() const { return handle_ != nullptr; }
-
-  static MetadataHandle TestOnlyWrap(T* p) { return MetadataHandle(p); }
-
- private:
-  friend class promise_filter_detail::BaseCallData;
-
-  explicit MetadataHandle(T* handle) : handle_(handle) {}
-  T* Unwrap() {
-    T* result = handle_;
-    handle_ = nullptr;
-    return result;
-  }
-
-  T* handle_ = nullptr;
-};
-
-// Trailing metadata type
-// TODO(ctiller): This should be a bespoke instance of MetadataMap<>
-using TrailingMetadata = MetadataHandle<grpc_metadata_batch>;
-
-// Client initial metadata type
-// TODO(ctiller): This should be a bespoke instance of MetadataMap<>
-using ClientInitialMetadata = MetadataHandle<grpc_metadata_batch>;
-
-using NextPromiseFactory =
-    std::function<ArenaPromise<TrailingMetadata>(ClientInitialMetadata)>;
-
 namespace promise_filter_detail {
 
 // Call data shared between all implementations of promise-based filters.
@@ -456,6 +403,13 @@ grpc_channel_filter MakePromiseBasedFilter() {
       [](grpc_call_element* elem, grpc_transport_stream_op_batch* batch) {
         static_cast<CallData*>(elem->call_data)->StartBatch(batch);
       },
+      // make_call_promise
+      [](grpc_channel_element* elem, ClientInitialMetadata initial_metadata,
+         NextPromiseFactory next_promise_factory) {
+        return static_cast<ChannelFilter*>(elem->channel_data)
+            ->MakeCallPromise(std::move(initial_metadata),
+                              std::move(next_promise_factory));
+      },
       // start_transport_op - for now unsupported
       grpc_channel_next_op,
       // sizeof_call_data

src/core/lib/security/authorization/sdk_server_authz_filter.cc

@@ -159,6 +159,7 @@ void SdkServerAuthzFilter::CallData::RecvInitialMetadataReady(
 
 const grpc_channel_filter SdkServerAuthzFilter::kFilterVtable = {
     SdkServerAuthzFilter::CallData::StartTransportStreamOpBatch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(SdkServerAuthzFilter::CallData),
     SdkServerAuthzFilter::CallData::Init,

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

@@ -481,6 +481,7 @@ static void client_auth_destroy_channel_elem(grpc_channel_element* elem) {
 
 const grpc_channel_filter grpc_client_auth_filter = {
     client_auth_start_transport_stream_op_batch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(call_data),
     client_auth_init_call_elem,

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

@@ -324,6 +324,7 @@ static void server_auth_destroy_channel_elem(grpc_channel_element* elem) {
 
 const grpc_channel_filter grpc_server_auth_filter = {
     server_auth_start_transport_stream_op_batch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(call_data),
     server_auth_init_call_elem,

src/core/lib/surface/lame_client.cc

@@ -156,6 +156,7 @@ grpc_arg MakeLameClientErrorArg(grpc_error_handle* error) {
 
 const grpc_channel_filter grpc_lame_filter = {
     grpc_core::lame_start_transport_stream_op_batch,
+    nullptr,
     grpc_core::lame_start_transport_op,
     sizeof(grpc_core::CallData),
     grpc_core::lame_init_call_elem,

src/core/lib/surface/server.cc

@@ -498,6 +498,7 @@ class ChannelBroadcaster {
 
 const grpc_channel_filter Server::kServerTopFilter = {
     Server::CallData::StartTransportStreamOpBatch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(Server::CallData),
     Server::CallData::InitCallElement,

src/core/lib/transport/transport.h

@@ -30,6 +30,7 @@
 #include "src/core/lib/iomgr/polling_entity.h"
 #include "src/core/lib/iomgr/pollset.h"
 #include "src/core/lib/iomgr/pollset_set.h"
+#include "src/core/lib/promise/arena_promise.h"
 #include "src/core/lib/resource_quota/arena.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/transport/byte_stream.h"
@@ -42,6 +43,62 @@
 #define GRPC_PROTOCOL_VERSION_MIN_MAJOR 2
 #define GRPC_PROTOCOL_VERSION_MIN_MINOR 1
 
+namespace grpc_core {
+// TODO(ctiller): eliminate once MetadataHandle is constructable directly.
+namespace promise_filter_detail {
+class BaseCallData;
+}
+
+// Small unowned "handle" type to ensure one accessor at a time to metadata.
+// The focus here is to get promises to use the syntax we'd like - we'll
+// probably substitute some other smart pointer later.
+template <typename T>
+class MetadataHandle {
+ public:
+  MetadataHandle() = default;
+
+  MetadataHandle(const MetadataHandle&) = delete;
+  MetadataHandle& operator=(const MetadataHandle&) = delete;
+
+  MetadataHandle(MetadataHandle&& other) noexcept : handle_(other.handle_) {
+    other.handle_ = nullptr;
+  }
+  MetadataHandle& operator=(MetadataHandle&& other) noexcept {
+    handle_ = other.handle_;
+    other.handle_ = nullptr;
+    return *this;
+  }
+
+  T* operator->() const { return handle_; }
+  bool has_value() const { return handle_ != nullptr; }
+
+  static MetadataHandle TestOnlyWrap(T* p) { return MetadataHandle(p); }
+
+ private:
+  friend class promise_filter_detail::BaseCallData;
+
+  explicit MetadataHandle(T* handle) : handle_(handle) {}
+  T* Unwrap() {
+    T* result = handle_;
+    handle_ = nullptr;
+    return result;
+  }
+
+  T* handle_ = nullptr;
+};
+
+// Trailing metadata type
+// TODO(ctiller): This should be a bespoke instance of MetadataMap<>
+using TrailingMetadata = MetadataHandle<grpc_metadata_batch>;
+
+// Client initial metadata type
+// TODO(ctiller): This should be a bespoke instance of MetadataMap<>
+using ClientInitialMetadata = MetadataHandle<grpc_metadata_batch>;
+
+using NextPromiseFactory =
+    std::function<ArenaPromise<TrailingMetadata>(ClientInitialMetadata)>;
+}  // namespace grpc_core
+
 /* forward declarations */
 
 typedef struct grpc_transport grpc_transport;
@@ -353,6 +410,14 @@ typedef struct grpc_transport_op {
   void (*set_accept_stream_fn)(void* user_data, grpc_transport* transport,
                                const void* server_data) = nullptr;
   void* set_accept_stream_user_data = nullptr;
+  /** set the callback for accepting new streams based upon promises;
+      this is a permanent callback, unlike the other one-shot closures.
+      If true, the callback is set to set_make_promise_fn, with its
+      user_data argument set to set_make_promise_data */
+  bool set_make_promise = false;
+  void (*set_make_promise_fn)(void* user_data, grpc_transport* transport,
+                              const void* server_data) = nullptr;
+  void* set_make_promise_user_data = nullptr;
   /** add this transport to a pollset */
   grpc_pollset* bind_pollset = nullptr;
   /** add this transport to a pollset_set */

src/core/lib/transport/transport_impl.h

@@ -36,6 +36,19 @@ typedef struct grpc_transport_vtable {
                      grpc_stream_refcount* refcount, const void* server_data,
                      grpc_core::Arena* arena);
 
+  /* Create a promise to execute one client call.
+     If this is non-null, it may be used in preference to
+     perform_stream_op.
+     If this is used in preference to perform_stream_op, the
+     following can be omitted also:
+       - calling init_stream, destroy_stream, set_pollset, set_pollset_set
+       - allocation of memory for call data (sizeof_stream may be ignored)
+     There is an on-going migration to move all filters to providing this, and
+     then to drop perform_stream_op. */
+  grpc_core::ArenaPromise<grpc_core::TrailingMetadata> (*make_call_promise)(
+      grpc_transport* self, grpc_core::ClientInitialMetadata initial_metadata,
+      grpc_core::NextPromiseFactory next_promise_factory);
+
   /* implementation of grpc_transport_set_pollset */
   void (*set_pollset)(grpc_transport* self, grpc_stream* stream,
                       grpc_pollset* pollset);

src/cpp/common/channel_filter.h

@@ -328,6 +328,7 @@ void RegisterChannelFilter(
   using FilterType = internal::ChannelFilter<ChannelDataType, CallDataType>;
   static const grpc_channel_filter filter = {
       FilterType::StartTransportStreamOpBatch,
+      nullptr,
       FilterType::StartTransportOp,
       FilterType::call_data_size,
       FilterType::InitCallElement,

test/core/channel/channel_stack_builder_test.cc

@@ -75,6 +75,7 @@ TEST(ChannelStackBuilderTest, ReplaceFilter) {
 
 const grpc_channel_filter replacement_filter = {
     grpc_call_next_op,
+    nullptr,
     grpc_channel_next_op,
     0,
     CallInitFunc,
@@ -88,6 +89,7 @@ const grpc_channel_filter replacement_filter = {
 
 const grpc_channel_filter original_filter = {
     grpc_call_next_op,
+    nullptr,
     grpc_channel_next_op,
     0,
     CallInitFunc,

test/core/channel/channel_stack_test.cc

@@ -77,6 +77,7 @@ static void free_call(void* arg, grpc_error_handle /*error*/) {
 static void test_create_channel_stack(void) {
   const grpc_channel_filter filter = {
       call_func,
+      nullptr,
       channel_func,
       sizeof(int),
       call_init_func,

test/core/end2end/tests/filter_causes_close.cc

@@ -235,6 +235,7 @@ static void destroy_channel_elem(grpc_channel_element* /*elem*/) {}
 
 static const grpc_channel_filter test_filter = {
     start_transport_stream_op_batch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(call_data),
     init_call_elem,

test/core/end2end/tests/filter_context.cc

@@ -258,6 +258,7 @@ static void destroy_channel_elem(grpc_channel_element* /*elem*/) {}
 
 static const grpc_channel_filter test_filter = {
     start_transport_stream_op_batch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(call_data),
     init_call_elem,

test/core/end2end/tests/filter_init_fails.cc

@@ -442,6 +442,7 @@ static void destroy_channel_elem(grpc_channel_element* /*elem*/) {}
 
 static const grpc_channel_filter test_filter = {
     grpc_call_next_op,
+    nullptr,
     grpc_channel_next_op,
     0,
     init_call_elem,

test/core/end2end/tests/filter_latency.cc

@@ -276,6 +276,7 @@ static void destroy_channel_elem(grpc_channel_element* /*elem*/) {}
 
 static const grpc_channel_filter test_client_filter = {
     grpc_call_next_op,
+    nullptr,
     grpc_channel_next_op,
     0,
     init_call_elem,
@@ -289,6 +290,7 @@ static const grpc_channel_filter test_client_filter = {
 
 static const grpc_channel_filter test_server_filter = {
     grpc_call_next_op,
+    nullptr,
     grpc_channel_next_op,
     0,
     init_call_elem,

test/core/end2end/tests/filter_status_code.cc

@@ -323,6 +323,7 @@ static void destroy_channel_elem(grpc_channel_element* /*elem*/) {}
 
 static const grpc_channel_filter test_client_filter = {
     grpc_call_next_op,
+    nullptr,
     grpc_channel_next_op,
     sizeof(final_status_data),
     init_call_elem,
@@ -336,6 +337,7 @@ static const grpc_channel_filter test_client_filter = {
 
 static const grpc_channel_filter test_server_filter = {
     server_start_transport_stream_op_batch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(final_status_data),
     init_call_elem,

test/core/end2end/tests/retry_cancel_with_multiple_send_batches.cc

@@ -293,6 +293,7 @@ class FailSendOpsFilter {
 
 grpc_channel_filter FailSendOpsFilter::kFilterVtable = {
     CallData::StartTransportStreamOpBatch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(CallData),
     CallData::Init,

test/core/end2end/tests/retry_recv_trailing_metadata_error.cc

@@ -325,6 +325,7 @@ class InjectStatusFilter {
 
 grpc_channel_filter InjectStatusFilter::kFilterVtable = {
     CallData::StartTransportStreamOpBatch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(CallData),
     CallData::Init,

test/core/end2end/tests/retry_send_op_fails.cc

@@ -344,6 +344,7 @@ class FailFirstSendOpFilter {
 
 grpc_channel_filter FailFirstSendOpFilter::kFilterVtable = {
     CallData::StartTransportStreamOpBatch,
+    nullptr,
     grpc_channel_next_op,
     sizeof(CallData),
     CallData::Init,

test/core/xds/xds_channel_stack_modifier_test.cc

@@ -69,11 +69,11 @@ TEST(XdsChannelStackModifierTest, XdsHttpFiltersInsertion) {
   grpc_init();
   // Add 2 test filters to XdsChannelStackModifier
   const grpc_channel_filter test_filter_1 = {
-      nullptr, nullptr, 0,       nullptr, nullptr,     nullptr,
-      0,       nullptr, nullptr, nullptr, kTestFilter1};
+      nullptr, nullptr, nullptr, 0,       nullptr, nullptr,
+      nullptr, 0,       nullptr, nullptr, nullptr, kTestFilter1};
   const grpc_channel_filter test_filter_2 = {
-      nullptr, nullptr, 0,       nullptr, nullptr,     nullptr,
-      0,       nullptr, nullptr, nullptr, kTestFilter2};
+      nullptr, nullptr, nullptr, 0,       nullptr, nullptr,
+      nullptr, 0,       nullptr, nullptr, nullptr, kTestFilter2};
   auto channel_stack_modifier = MakeRefCounted<XdsChannelStackModifier>(
       std::vector<const grpc_channel_filter*>{&test_filter_1, &test_filter_2});
   grpc_arg arg = channel_stack_modifier->MakeChannelArg();
@@ -114,11 +114,11 @@ TEST(XdsChannelStackModifierTest, XdsHttpFiltersInsertionAfterCensus) {
   grpc_init();
   // Add 2 test filters to XdsChannelStackModifier
   const grpc_channel_filter test_filter_1 = {
-      nullptr, nullptr, 0,       nullptr, nullptr,     nullptr,
-      0,       nullptr, nullptr, nullptr, kTestFilter1};
+      nullptr, nullptr, nullptr, 0,       nullptr, nullptr,
+      nullptr, 0,       nullptr, nullptr, nullptr, kTestFilter1};
   const grpc_channel_filter test_filter_2 = {
-      nullptr, nullptr, 0,       nullptr, nullptr,     nullptr,
-      0,       nullptr, nullptr, nullptr, kTestFilter2};
+      nullptr, nullptr, nullptr, 0,       nullptr, nullptr,
+      nullptr, 0,       nullptr, nullptr, nullptr, kTestFilter2};
   auto channel_stack_modifier = MakeRefCounted<XdsChannelStackModifier>(
       std::vector<const grpc_channel_filter*>{&test_filter_1, &test_filter_2});
   grpc_arg arg = channel_stack_modifier->MakeChannelArg();

test/cpp/microbenchmarks/bm_call_create.cc

@@ -384,17 +384,13 @@ void DestroyChannelElem(grpc_channel_element* /*elem*/) {}
 void GetChannelInfo(grpc_channel_element* /*elem*/,
                     const grpc_channel_info* /*channel_info*/) {}
 
-static const grpc_channel_filter phony_filter = {StartTransportStreamOp,
-                                                 StartTransportOp,
-                                                 0,
-                                                 InitCallElem,
-                                                 SetPollsetOrPollsetSet,
-                                                 DestroyCallElem,
-                                                 0,
-                                                 InitChannelElem,
-                                                 DestroyChannelElem,
-                                                 GetChannelInfo,
-                                                 "phony_filter"};
+static const grpc_channel_filter phony_filter = {
+    StartTransportStreamOp, nullptr,
+    StartTransportOp,       0,
+    InitCallElem,           SetPollsetOrPollsetSet,
+    DestroyCallElem,        0,
+    InitChannelElem,        DestroyChannelElem,
+    GetChannelInfo,         "phony_filter"};
 
 }  // namespace phony_filter
 
@@ -441,11 +437,17 @@ void Destroy(grpc_transport* /*self*/) {}
 /* implementation of grpc_transport_get_endpoint */
 grpc_endpoint* GetEndpoint(grpc_transport* /*self*/) { return nullptr; }
 
-static const grpc_transport_vtable phony_transport_vtable = {
-    0,          "phony_http2", InitStream,
-    SetPollset, SetPollsetSet, PerformStreamOp,
-    PerformOp,  DestroyStream, Destroy,
-    GetEndpoint};
+static const grpc_transport_vtable phony_transport_vtable = {0,
+                                                             "phony_http2",
+                                                             InitStream,
+                                                             nullptr,
+                                                             SetPollset,
+                                                             SetPollsetSet,
+                                                             PerformStreamOp,
+                                                             PerformOp,
+                                                             DestroyStream,
+                                                             Destroy,
+                                                             GetEndpoint};
 
 static grpc_transport phony_transport = {&phony_transport_vtable};
 
@@ -682,17 +684,12 @@ void GetChannelInfo(grpc_channel_element* /*elem*/,
                     const grpc_channel_info* /*channel_info*/) {}
 
 static const grpc_channel_filter isolated_call_filter = {
-    StartTransportStreamOp,
-    StartTransportOp,
-    sizeof(call_data),
-    InitCallElem,
-    SetPollsetOrPollsetSet,
-    DestroyCallElem,
-    0,
-    InitChannelElem,
-    DestroyChannelElem,
-    GetChannelInfo,
-    "isolated_call_filter"};
+    StartTransportStreamOp, nullptr,
+    StartTransportOp,       sizeof(call_data),
+    InitCallElem,           SetPollsetOrPollsetSet,
+    DestroyCallElem,        0,
+    InitChannelElem,        DestroyChannelElem,
+    GetChannelInfo,         "isolated_call_filter"};
 }  // namespace isolated_call_filter
 
 class IsolatedCallFixture : public TrackCounters {