Detect default metadata using the callout list.

3 files changed, 4 insertions, 10 deletions

diff --git a/src/core/ext/transport/chttp2/transport/writing.c b/src/core/ext/transport/chttp2/transport/writing.c
index 80eb51ff0d..67e3fa44c8 100644
--- a/src/core/ext/transport/chttp2/transport/writing.c
+++ b/src/core/ext/transport/chttp2/transport/writing.c
@@ -154,17 +154,8 @@ static uint32_t target_write_size(grpc_chttp2_transport *t) {
 }
 
 // Returns true if initial_metadata contains only default headers.
-//
-// TODO(roth): The fact that we hard-code these particular headers here
-// is fairly ugly.  Need some better way to know which headers are
-// default, maybe via a bit in the static metadata table?
 static bool is_default_initial_metadata(grpc_metadata_batch *initial_metadata) {
-  int num_default_fields =
-      (initial_metadata->idx.named.status != NULL) +
-      (initial_metadata->idx.named.content_type != NULL) +
-      (initial_metadata->idx.named.grpc_encoding != NULL) +
-      (initial_metadata->idx.named.grpc_accept_encoding != NULL);
-  return (size_t)num_default_fields == initial_metadata->list.count;
+  return initial_metadata->list.static_count == initial_metadata->list.count;
 }
 
 grpc_chttp2_begin_write_result grpc_chttp2_begin_write(
diff --git a/src/core/lib/transport/metadata_batch.c b/src/core/lib/transport/metadata_batch.c
index 8f24b8527c..92cf194e2f 100644
--- a/src/core/lib/transport/metadata_batch.c
+++ b/src/core/lib/transport/metadata_batch.c
@@ -105,6 +105,7 @@ static grpc_error *maybe_link_callout(grpc_metadata_batch *batch,
     return GRPC_ERROR_NONE;
   }
   if (batch->idx.array[idx] == NULL) {
+    ++batch->list.static_count;
     batch->idx.array[idx] = storage;
     return GRPC_ERROR_NONE;
   }
@@ -120,6 +121,7 @@ static void maybe_unlink_callout(grpc_metadata_batch *batch,
   if (idx == GRPC_BATCH_CALLOUTS_COUNT) {
     return;
   }
+  --batch->list.static_count;
   GPR_ASSERT(batch->idx.array[idx] != NULL);
   batch->idx.array[idx] = NULL;
 }
diff --git a/src/core/lib/transport/metadata_batch.h b/src/core/lib/transport/metadata_batch.h
index 1b11a3e252..8834051318 100644
--- a/src/core/lib/transport/metadata_batch.h
+++ b/src/core/lib/transport/metadata_batch.h
@@ -41,6 +41,7 @@ typedef struct grpc_linked_mdelem {
 
 typedef struct grpc_mdelem_list {
   size_t count;
+  size_t static_count;
   grpc_linked_mdelem *head;
   grpc_linked_mdelem *tail;
 } grpc_mdelem_list;