Removing instances of exec_ctx being passed around in functions in

src/core. exec_ctx is now a thread_local pointer of type ExecCtx instead of
grpc_exec_ctx which is initialized whenever ExecCtx is instantiated. ExecCtx
also keeps track of the previous exec_ctx so that nesting of exec_ctx is
allowed. This means that there is only one exec_ctx being used at any
time. Also, grpc_exec_ctx_finish is called in the destructor of the
object, and the previous exec_ctx is restored to avoid breaking current
functionality. The code still explicitly calls grpc_exec_ctx_finish
because removing all such instances causes the code to break.

2 files changed, 14 insertions, 21 deletions

diff --git a/src/core/ext/filters/load_reporting/server_load_reporting_filter.cc b/src/core/ext/filters/load_reporting/server_load_reporting_filter.cc
index ca8a3b2a13..6c93d0e821 100644
--- a/src/core/ext/filters/load_reporting/server_load_reporting_filter.cc
+++ b/src/core/ext/filters/load_reporting/server_load_reporting_filter.cc
@@ -54,8 +54,7 @@ typedef struct channel_data {
   intptr_t id; /**< an id unique to the channel */
 } channel_data;
 
-static void on_initial_md_ready(grpc_exec_ctx *exec_ctx, void *user_data,
-                                grpc_error *err) {
+static void on_initial_md_ready(void *user_data, grpc_error *err) {
   grpc_call_element *elem = (grpc_call_element *)user_data;
   call_data *calld = (call_data *)elem->call_data;
 
@@ -73,20 +72,19 @@ static void on_initial_md_ready(grpc_exec_ctx *exec_ctx, void *user_data,
           GRPC_MDVALUE(calld->recv_initial_metadata->idx.named.lb_token->md));
       calld->have_initial_md_string = true;
       grpc_metadata_batch_remove(
-          exec_ctx, calld->recv_initial_metadata,
+          calld->recv_initial_metadata,
           calld->recv_initial_metadata->idx.named.lb_token);
     }
   } else {
     GRPC_ERROR_REF(err);
   }
   calld->ops_recv_initial_metadata_ready->cb(
-      exec_ctx, calld->ops_recv_initial_metadata_ready->cb_arg, err);
+      calld->ops_recv_initial_metadata_ready->cb_arg, err);
   GRPC_ERROR_UNREF(err);
 }
 
 /* Constructor for call_data */
-static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
-                                  grpc_call_element *elem,
+static grpc_error *init_call_elem(grpc_call_element *elem,
                                   const grpc_call_element_args *args) {
   call_data *calld = (call_data *)elem->call_data;
   calld->id = (intptr_t)args->call_stack;
@@ -108,7 +106,7 @@ static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
 }
 
 /* Destructor for call_data */
-static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
+static void destroy_call_elem(grpc_call_element *elem,
                               const grpc_call_final_info *final_info,
                               grpc_closure *ignored) {
   call_data *calld = (call_data *)elem->call_data;
@@ -125,19 +123,18 @@ static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
   */
 
   if (calld->have_initial_md_string) {
-    grpc_slice_unref_internal(exec_ctx, calld->initial_md_string);
+    grpc_slice_unref_internal(calld->initial_md_string);
   }
   if (calld->have_trailing_md_string) {
-    grpc_slice_unref_internal(exec_ctx, calld->trailing_md_string);
+    grpc_slice_unref_internal(calld->trailing_md_string);
   }
   if (calld->have_service_method) {
-    grpc_slice_unref_internal(exec_ctx, calld->service_method);
+    grpc_slice_unref_internal(calld->service_method);
   }
 }
 
 /* Constructor for channel_data */
-static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
-                                     grpc_channel_element *elem,
+static grpc_error *init_channel_elem(grpc_channel_element *elem,
                                      grpc_channel_element_args *args) {
   GPR_ASSERT(!args->is_last);
 
@@ -158,8 +155,7 @@ static grpc_error *init_channel_elem(grpc_exec_ctx *exec_ctx,
 }
 
 /* Destructor for channel data */
-static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
-                                 grpc_channel_element *elem) {
+static void destroy_channel_elem(grpc_channel_element *elem) {
   /* TODO(dgq): do something with the data
   channel_data *chand = elem->channel_data;
   grpc_load_reporting_call_data lr_call_data = {
@@ -173,8 +169,7 @@ static void destroy_channel_elem(grpc_exec_ctx *exec_ctx,
   */
 }
 
-static grpc_filtered_mdelem lr_trailing_md_filter(grpc_exec_ctx *exec_ctx,
-                                                  void *user_data,
+static grpc_filtered_mdelem lr_trailing_md_filter(void *user_data,
                                                   grpc_mdelem md) {
   grpc_call_element *elem = (grpc_call_element *)user_data;
   call_data *calld = (call_data *)elem->call_data;
@@ -186,8 +181,7 @@ static grpc_filtered_mdelem lr_trailing_md_filter(grpc_exec_ctx *exec_ctx,
 }
 
 static void lr_start_transport_stream_op_batch(
-    grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-    grpc_transport_stream_op_batch *op) {
+    grpc_call_element *elem, grpc_transport_stream_op_batch *op) {
   GPR_TIMER_BEGIN("lr_start_transport_stream_op_batch", 0);
   call_data *calld = (call_data *)elem->call_data;
 
@@ -203,12 +197,11 @@ static void lr_start_transport_stream_op_batch(
     GRPC_LOG_IF_ERROR(
         "grpc_metadata_batch_filter",
         grpc_metadata_batch_filter(
-            exec_ctx,
             op->payload->send_trailing_metadata.send_trailing_metadata,
             lr_trailing_md_filter, elem,
             "LR trailing metadata filtering error"));
   }
-  grpc_call_next_op(exec_ctx, elem, op);
+  grpc_call_next_op(elem, op);
 
   GPR_TIMER_END("lr_start_transport_stream_op_batch", 0);
 }
diff --git a/src/core/ext/filters/load_reporting/server_load_reporting_plugin.cc b/src/core/ext/filters/load_reporting/server_load_reporting_plugin.cc
index 223fb3ee8b..6a38b71832 100644
--- a/src/core/ext/filters/load_reporting/server_load_reporting_plugin.cc
+++ b/src/core/ext/filters/load_reporting/server_load_reporting_plugin.cc
@@ -38,7 +38,7 @@ static bool is_load_reporting_enabled(const grpc_channel_args *a) {
 }
 
 static bool maybe_add_server_load_reporting_filter(
-    grpc_exec_ctx *exec_ctx, grpc_channel_stack_builder *builder, void *arg) {
+    grpc_channel_stack_builder *builder, void *arg) {
   const grpc_channel_args *args =
       grpc_channel_stack_builder_get_channel_arguments(builder);
   const grpc_channel_filter *filter = (const grpc_channel_filter *)arg;