Hoist constant setting out of loop - and shave some ns from call creation

src/core/ext/census/grpc_filter.c

@@ -127,7 +127,7 @@ static void server_start_transport_op(grpc_exec_ctx *exec_ctx,
 
 static grpc_error *client_init_call_elem(grpc_exec_ctx *exec_ctx,
                                          grpc_call_element *elem,
-                                         grpc_call_element_args *args) {
+                                         const grpc_call_element_args *args) {
   call_data *d = elem->call_data;
   GPR_ASSERT(d != NULL);
   memset(d, 0, sizeof(*d));
@@ -146,7 +146,7 @@ static void client_destroy_call_elem(grpc_exec_ctx *exec_ctx,
 
 static grpc_error *server_init_call_elem(grpc_exec_ctx *exec_ctx,
                                          grpc_call_element *elem,
-                                         grpc_call_element_args *args) {
+                                         const grpc_call_element_args *args) {
   call_data *d = elem->call_data;
   GPR_ASSERT(d != NULL);
   memset(d, 0, sizeof(*d));

src/core/ext/client_channel/client_channel.c

@@ -1054,7 +1054,7 @@ static void read_service_config(grpc_exec_ctx *exec_ctx, void *arg,
 /* Constructor for call_data */
 static grpc_error *cc_init_call_elem(grpc_exec_ctx *exec_ctx,
                                      grpc_call_element *elem,
-                                     grpc_call_element_args *args) {
+                                     const grpc_call_element_args *args) {
   channel_data *chand = elem->channel_data;
   call_data *calld = elem->call_data;
   // Initialize data members.

src/core/ext/load_reporting/load_reporting_filter.c

@@ -100,7 +100,7 @@ static void on_initial_md_ready(grpc_exec_ctx *exec_ctx, void *user_data,
 /* Constructor for call_data */
 static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
+                                  const grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   memset(calld, 0, sizeof(call_data));
 

src/core/lib/channel/channel_stack.c

@@ -173,7 +173,6 @@ grpc_error *grpc_call_stack_init(
     grpc_slice path, gpr_timespec start_time, gpr_timespec deadline,
     grpc_call_stack *call_stack) {
   grpc_channel_element *channel_elems = CHANNEL_ELEMS_FROM_STACK(channel_stack);
-  grpc_call_element_args args;
   size_t count = channel_stack->count;
   grpc_call_element *call_elems;
   char *user_data;
@@ -188,13 +187,15 @@ grpc_error *grpc_call_stack_init(
 
   /* init per-filter data */
   grpc_error *first_error = GRPC_ERROR_NONE;
-  args.start_time = start_time;
+  const grpc_call_element_args args = {
+      .start_time = start_time,
+      .call_stack = call_stack,
+      .server_transport_data = transport_server_data,
+      .context = context,
+      .path = path,
+      .deadline = deadline,
+  };
   for (i = 0; i < count; i++) {
-    args.call_stack = call_stack;
-    args.server_transport_data = transport_server_data;
-    args.context = context;
-    args.path = path;
-    args.deadline = deadline;
     call_elems[i].filter = channel_elems[i].filter;
     call_elems[i].channel_data = channel_elems[i].channel_data;
     call_elems[i].call_data = user_data;

src/core/lib/channel/channel_stack.h

@@ -131,7 +131,7 @@ typedef struct {
      argument. */
   grpc_error *(*init_call_elem)(grpc_exec_ctx *exec_ctx,
                                 grpc_call_element *elem,
-                                grpc_call_element_args *args);
+                                const grpc_call_element_args *args);
   void (*set_pollset_or_pollset_set)(grpc_exec_ctx *exec_ctx,
                                      grpc_call_element *elem,
                                      grpc_polling_entity *pollent);

src/core/lib/channel/compress_filter.c

@@ -272,7 +272,7 @@ static void compress_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
 /* Constructor for call_data */
 static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
+                                  const grpc_call_element_args *args) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
 

src/core/lib/channel/connected_channel.c

@@ -83,7 +83,7 @@ static void con_start_transport_op(grpc_exec_ctx *exec_ctx,
 /* Constructor for call_data */
 static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
+                                  const grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   int r = grpc_transport_init_stream(

src/core/lib/channel/deadline_filter.c

@@ -244,7 +244,7 @@ typedef struct server_call_data {
 // Constructor for call_data.  Used for both client and server filters.
 static grpc_error* init_call_elem(grpc_exec_ctx* exec_ctx,
                                   grpc_call_element* elem,
-                                  grpc_call_element_args* args) {
+                                  const grpc_call_element_args* args) {
   // Note: size of call data is different between client and server.
   memset(elem->call_data, 0, elem->filter->sizeof_call_data);
   grpc_deadline_state_init(exec_ctx, elem, args->call_stack);

src/core/lib/channel/http_client_filter.c

@@ -386,7 +386,7 @@ static void hc_start_transport_op(grpc_exec_ctx *exec_ctx,
 /* Constructor for call_data */
 static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
+                                  const grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   calld->on_done_recv_initial_metadata = NULL;
   calld->on_done_recv_trailing_metadata = NULL;

src/core/lib/channel/http_server_filter.c

@@ -343,7 +343,7 @@ static void hs_start_transport_op(grpc_exec_ctx *exec_ctx,
 /* Constructor for call_data */
 static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
+                                  const grpc_call_element_args *args) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   /* initialize members */

src/core/lib/channel/message_size_filter.c

@@ -166,7 +166,7 @@ static void start_transport_stream_op(grpc_exec_ctx* exec_ctx,
 // Constructor for call_data.
 static grpc_error* init_call_elem(grpc_exec_ctx* exec_ctx,
                                   grpc_call_element* elem,
-                                  grpc_call_element_args* args) {
+                                  const grpc_call_element_args* args) {
   channel_data* chand = elem->channel_data;
   call_data* calld = elem->call_data;
   calld->next_recv_message_ready = NULL;

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

@@ -302,7 +302,7 @@ static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
 /* Constructor for call_data */
 static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
+                                  const grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   memset(calld, 0, sizeof(*calld));
   return GRPC_ERROR_NONE;

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

@@ -197,7 +197,7 @@ static void auth_start_transport_op(grpc_exec_ctx *exec_ctx,
 /* Constructor for call_data */
 static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
+                                  const grpc_call_element_args *args) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;

src/core/lib/surface/lame_client.c

@@ -122,7 +122,7 @@ static void lame_start_transport_op(grpc_exec_ctx *exec_ctx,
 
 static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
+                                  const grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   gpr_atm_no_barrier_store(&calld->filled_metadata, 0);
   return GRPC_ERROR_NONE;

src/core/lib/surface/server.c

@@ -879,7 +879,7 @@ static void channel_connectivity_changed(grpc_exec_ctx *exec_ctx, void *cd,
 
 static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
                                   grpc_call_element *elem,
-                                  grpc_call_element_args *args) {
+                                  const grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   memset(calld, 0, sizeof(call_data));

test/cpp/microbenchmarks/bm_call_create.cc

@@ -140,7 +140,7 @@ static void StartTransportOp(grpc_exec_ctx *exec_ctx,
 
 static grpc_error *InitCallElem(grpc_exec_ctx *exec_ctx,
                                 grpc_call_element *elem,
-                                grpc_call_element_args *args) {
+                                const grpc_call_element_args *args) {
   return GRPC_ERROR_NONE;
 }