Merge github.com:grpc/grpc into stats_histo

3 files changed, 48 insertions, 3 deletions

diff --git a/src/core/ext/filters/load_reporting/load_reporting.c b/src/core/ext/filters/load_reporting/load_reporting.c
index 9745763c91..b42aa99cdb 100644
--- a/src/core/ext/filters/load_reporting/load_reporting.c
+++ b/src/core/ext/filters/load_reporting/load_reporting.c
@@ -42,9 +42,15 @@ static bool maybe_add_load_reporting_filter(grpc_exec_ctx *exec_ctx,
                                             void *arg) {
   const grpc_channel_args *args =
       grpc_channel_stack_builder_get_channel_arguments(builder);
-  if (is_load_reporting_enabled(args)) {
-    return grpc_channel_stack_builder_prepend_filter(
-        builder, (const grpc_channel_filter *)arg, NULL, NULL);
+  const grpc_channel_filter *filter = arg;
+  grpc_channel_stack_builder_iterator *it =
+      grpc_channel_stack_builder_iterator_find(builder, filter->name);
+  const bool already_has_load_reporting_filter =
+      !grpc_channel_stack_builder_iterator_is_end(it);
+  grpc_channel_stack_builder_iterator_destroy(it);
+  if (is_load_reporting_enabled(args) && !already_has_load_reporting_filter) {
+    return grpc_channel_stack_builder_prepend_filter(builder, filter, NULL,
+                                                     NULL);
   }
   return true;
 }
diff --git a/src/core/lib/channel/channel_stack_builder.c b/src/core/lib/channel/channel_stack_builder.c
index c369e33073..7f2b8e07ce 100644
--- a/src/core/lib/channel/channel_stack_builder.c
+++ b/src/core/lib/channel/channel_stack_builder.c
@@ -124,6 +124,20 @@ bool grpc_channel_stack_builder_move_prev(
   return true;
 }
 
+grpc_channel_stack_builder_iterator *grpc_channel_stack_builder_iterator_find(
+    grpc_channel_stack_builder *builder, const char *filter_name) {
+  GPR_ASSERT(filter_name != NULL);
+  grpc_channel_stack_builder_iterator *it =
+      grpc_channel_stack_builder_create_iterator_at_first(builder);
+  while (grpc_channel_stack_builder_move_next(it)) {
+    if (grpc_channel_stack_builder_iterator_is_end(it)) break;
+    const char *filter_name_at_it =
+        grpc_channel_stack_builder_iterator_filter_name(it);
+    if (strcmp(filter_name, filter_name_at_it) == 0) break;
+  }
+  return it;
+}
+
 bool grpc_channel_stack_builder_move_prev(
     grpc_channel_stack_builder_iterator *iterator);
 
@@ -169,6 +183,21 @@ bool grpc_channel_stack_builder_append_filter(
   return ok;
 }
 
+bool grpc_channel_stack_builder_remove_filter(
+    grpc_channel_stack_builder *builder, const char *filter_name) {
+  grpc_channel_stack_builder_iterator *it =
+      grpc_channel_stack_builder_iterator_find(builder, filter_name);
+  if (grpc_channel_stack_builder_iterator_is_end(it)) {
+    grpc_channel_stack_builder_iterator_destroy(it);
+    return false;
+  }
+  it->node->prev->next = it->node->next;
+  it->node->next->prev = it->node->prev;
+  gpr_free(it->node);
+  grpc_channel_stack_builder_iterator_destroy(it);
+  return true;
+}
+
 bool grpc_channel_stack_builder_prepend_filter(
     grpc_channel_stack_builder *builder, const grpc_channel_filter *filter,
     grpc_post_filter_create_init_func post_init_func, void *user_data) {
diff --git a/src/core/lib/channel/channel_stack_builder.h b/src/core/lib/channel/channel_stack_builder.h
index d43e427962..fdff2a2b6d 100644
--- a/src/core/lib/channel/channel_stack_builder.h
+++ b/src/core/lib/channel/channel_stack_builder.h
@@ -95,6 +95,11 @@ bool grpc_channel_stack_builder_move_next(
 bool grpc_channel_stack_builder_move_prev(
     grpc_channel_stack_builder_iterator *iterator);
 
+/// Return an iterator at \a filter_name, or at the end of the list if not
+/// found.
+grpc_channel_stack_builder_iterator *grpc_channel_stack_builder_iterator_find(
+    grpc_channel_stack_builder *builder, const char *filter_name);
+
 typedef void (*grpc_post_filter_create_init_func)(
     grpc_channel_stack *channel_stack, grpc_channel_element *elem, void *arg);
 
@@ -132,6 +137,11 @@ bool grpc_channel_stack_builder_append_filter(
     grpc_post_filter_create_init_func post_init_func,
     void *user_data) GRPC_MUST_USE_RESULT;
 
+/// Remove any filter whose name is \a filter_name from \a builder. Returns true
+/// if \a filter_name was not found.
+bool grpc_channel_stack_builder_remove_filter(
+    grpc_channel_stack_builder *builder, const char *filter_name);
+
 /// Terminate iteration and destroy \a iterator
 void grpc_channel_stack_builder_iterator_destroy(
     grpc_channel_stack_builder_iterator *iterator);