Pretty print outgoing headers

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

@@ -954,6 +954,16 @@ static void complete_fetch(grpc_exec_ctx *exec_ctx, void *gs,
 
 static void do_nothing(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {}
 
+static void log_metadata(const grpc_metadata_batch *md_batch, uint32_t id,
+                         bool is_client, bool is_initial) {
+  for (grpc_linked_mdelem *md = md_batch->list.head; md != md_batch->list.tail;
+       md = md->next) {
+    gpr_log(GPR_INFO, "HTTP:%d:%s:%s: %s: %s", id, is_initial ? "HDR" : "TRL",
+            is_client ? "CLI" : "SVR", grpc_mdstr_as_c_string(md->md->key),
+            grpc_mdstr_as_c_string(md->md->value));
+  }
+}
+
 static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
                                      grpc_error *error_ignored) {
   GPR_TIMER_BEGIN("perform_stream_op_locked", 0);
@@ -967,6 +977,12 @@ static void perform_stream_op_locked(grpc_exec_ctx *exec_ctx, void *stream_op,
     gpr_log(GPR_DEBUG, "perform_stream_op_locked: %s; on_complete = %p", str,
             op->on_complete);
     gpr_free(str);
+    if (op->send_initial_metadata) {
+      log_metadata(op->send_initial_metadata, s->id, t->is_client, true);
+    }
+    if (op->send_trailing_metadata) {
+      log_metadata(op->send_trailing_metadata, s->id, t->is_client, false);
+    }
   }
 
   grpc_closure *on_complete = op->on_complete;