Add a trace to list which filters are contained in a channel stack (#28530)

* Add a trace to emit what a channel stack looks like

* Add a trace to emit what a channel stack looks like

* x

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

@@ -964,7 +964,8 @@ void ConnectionDestroy(void* arg, grpc_error_handle /*error*/) {
 
 bool Subchannel::PublishTransportLocked() {
   // Construct channel stack.
-  grpc_channel_stack_builder* builder = grpc_channel_stack_builder_create();
+  grpc_channel_stack_builder* builder =
+      grpc_channel_stack_builder_create("subchannel");
   grpc_channel_stack_builder_set_channel_arguments(
       builder, connecting_result_.channel_args);
   grpc_channel_stack_builder_set_transport(builder,

src/core/lib/channel/channel_stack.cc

@@ -29,6 +29,7 @@
 #include "src/core/lib/gpr/alloc.h"
 
 grpc_core::TraceFlag grpc_trace_channel(false, "channel");
+grpc_core::TraceFlag grpc_trace_channel_stack(false, "channel_stack");
 
 /* Memory layouts.
 
@@ -105,6 +106,13 @@ grpc_error_handle grpc_channel_stack_init(
     const grpc_channel_filter** filters, size_t filter_count,
     const grpc_channel_args* channel_args, grpc_transport* optional_transport,
     const char* name, grpc_channel_stack* stack) {
+  if (grpc_trace_channel_stack.enabled()) {
+    gpr_log(GPR_INFO, "CHANNEL_STACK: init %s", name);
+    for (size_t i = 0; i < filter_count; i++) {
+      gpr_log(GPR_INFO, "CHANNEL_STACK:   filter %s", filters[i]->name);
+    }
+  }
+
   size_t call_size =
       GPR_ROUND_UP_TO_ALIGNMENT_SIZE(sizeof(grpc_call_stack)) +
       GPR_ROUND_UP_TO_ALIGNMENT_SIZE(filter_count * sizeof(grpc_call_element));

src/core/lib/channel/channel_stack_builder.cc

@@ -51,7 +51,8 @@ struct grpc_channel_stack_builder_iterator {
   filter_node* node;
 };
 
-grpc_channel_stack_builder* grpc_channel_stack_builder_create(void) {
+grpc_channel_stack_builder* grpc_channel_stack_builder_create(
+    const char* name) {
   grpc_channel_stack_builder* b =
       grpc_core::Zalloc<grpc_channel_stack_builder>();
   b->begin.filter = nullptr;
@@ -60,6 +61,7 @@ grpc_channel_stack_builder* grpc_channel_stack_builder_create(void) {
   b->begin.prev = &b->end;
   b->end.next = &b->begin;
   b->end.prev = &b->begin;
+  b->name = name;
   return b;
 }
 
@@ -143,12 +145,6 @@ grpc_channel_stack_builder_iterator* grpc_channel_stack_builder_iterator_find(
 bool grpc_channel_stack_builder_move_prev(
     grpc_channel_stack_builder_iterator* iterator);
 
-void grpc_channel_stack_builder_set_name(grpc_channel_stack_builder* builder,
-                                         const char* name) {
-  GPR_ASSERT(builder->name == nullptr);
-  builder->name = name;
-}
-
 void grpc_channel_stack_builder_set_channel_arguments(
     grpc_channel_stack_builder* builder, const grpc_channel_args* args) {
   if (builder->args != nullptr) {

src/core/lib/channel/channel_stack_builder.h

@@ -32,12 +32,9 @@ typedef struct grpc_channel_stack_builder grpc_channel_stack_builder;
 typedef struct grpc_channel_stack_builder_iterator
     grpc_channel_stack_builder_iterator;
 
-/// Create a new channel stack builder
-grpc_channel_stack_builder* grpc_channel_stack_builder_create(void);
-
-/// Assign a name to the channel stack: \a name must be statically allocated
-void grpc_channel_stack_builder_set_name(grpc_channel_stack_builder* builder,
-                                         const char* name);
+/// Create a new channel stack builder.
+/// \a name must be statically allocated.
+grpc_channel_stack_builder* grpc_channel_stack_builder_create(const char* name);
 
 /// Set the target uri
 void grpc_channel_stack_builder_set_target(grpc_channel_stack_builder* b,

src/core/lib/surface/channel.cc

@@ -46,6 +46,7 @@
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/api_trace.h"
 #include "src/core/lib/surface/call.h"
+#include "src/core/lib/surface/channel_stack_type.h"
 
 /** Cache grpc-status: X mdelems for X = 0..NUM_CACHED_STATUS_ELEMS.
  *  Avoids needing to take a metadata context lock for sending status
@@ -243,7 +244,8 @@ grpc_channel* grpc_channel_create(const char* target,
   // grpc_shutdown() when the channel is actually destroyed, thus
   // ensuring that shutdown is deferred until that point.
   grpc_init();
-  grpc_channel_stack_builder* builder = grpc_channel_stack_builder_create();
+  grpc_channel_stack_builder* builder = grpc_channel_stack_builder_create(
+      grpc_channel_stack_type_string(channel_stack_type));
   const grpc_core::UniquePtr<char> default_authority =
       get_default_authority(input_args);
   grpc_channel_args* args =

test/core/channel/minimal_stack_is_minimal_test.cc

@@ -126,7 +126,8 @@ static int check_stack(const char* file, int line, const char* transport_name,
                        grpc_channel_args* init_args,
                        unsigned channel_stack_type, ...) {
   // create phony channel stack
-  grpc_channel_stack_builder* builder = grpc_channel_stack_builder_create();
+  grpc_channel_stack_builder* builder =
+      grpc_channel_stack_builder_create("test");
   grpc_transport_vtable fake_transport_vtable;
   memset(&fake_transport_vtable, 0, sizeof(grpc_transport_vtable));
   fake_transport_vtable.name = transport_name;

test/core/xds/xds_channel_stack_modifier_test.cc

@@ -79,7 +79,8 @@ TEST(XdsChannelStackModifierTest, XdsHttpFiltersInsertion) {
   grpc_arg arg = channel_stack_modifier->MakeChannelArg();
   // Create a phony grpc_channel_stack_builder object
   grpc_channel_args* args = grpc_channel_args_copy_and_add(nullptr, &arg, 1);
-  grpc_channel_stack_builder* builder = grpc_channel_stack_builder_create();
+  grpc_channel_stack_builder* builder =
+      grpc_channel_stack_builder_create("test");
   grpc_channel_stack_builder_set_channel_arguments(builder, args);
   grpc_channel_args_destroy(args);
   grpc_transport_vtable fake_transport_vtable;
@@ -123,7 +124,8 @@ TEST(XdsChannelStackModifierTest, XdsHttpFiltersInsertionAfterCensus) {
   grpc_arg arg = channel_stack_modifier->MakeChannelArg();
   // Create a phony grpc_channel_stack_builder object
   grpc_channel_args* args = grpc_channel_args_copy_and_add(nullptr, &arg, 1);
-  grpc_channel_stack_builder* builder = grpc_channel_stack_builder_create();
+  grpc_channel_stack_builder* builder =
+      grpc_channel_stack_builder_create("test");
   grpc_channel_stack_builder_set_channel_arguments(builder, args);
   grpc_channel_args_destroy(args);
   grpc_transport_vtable fake_transport_vtable;

test/cpp/microbenchmarks/bm_call_create.cc

@@ -707,8 +707,8 @@ class IsolatedCallFixture : public TrackCounters {
     const grpc_channel_args* args = grpc_core::CoreConfiguration::Get()
                                         .channel_args_preconditioning()
                                         .PreconditionChannelArgs(nullptr);
-    grpc_channel_stack_builder* builder = grpc_channel_stack_builder_create();
-    grpc_channel_stack_builder_set_name(builder, "phony");
+    grpc_channel_stack_builder* builder =
+        grpc_channel_stack_builder_create("phony");
     grpc_channel_stack_builder_set_target(builder, "phony_target");
     grpc_channel_stack_builder_set_channel_arguments(builder, args);
     GPR_ASSERT(grpc_channel_stack_builder_append_filter(