Make grpc_exec_ctx_flush return a status indicating if work was performed

src/core/iomgr/exec_ctx.c

@@ -35,16 +35,19 @@
 
 #include <grpc/support/log.h>
 
-void grpc_exec_ctx_flush(grpc_exec_ctx *exec_ctx) {
+int grpc_exec_ctx_flush(grpc_exec_ctx *exec_ctx) {
+  int did_something = 0;
   while (!grpc_closure_list_empty(exec_ctx->closure_list)) {
     grpc_closure *c = exec_ctx->closure_list.head;
     exec_ctx->closure_list.head = exec_ctx->closure_list.tail = NULL;
     while (c != NULL) {
       grpc_closure *next = c->next;
+      did_something = 1;
       c->cb(exec_ctx, c->cb_arg, c->success);
       c = next;
     }
   }
+  return did_something;
 }
 
 void grpc_exec_ctx_finish(grpc_exec_ctx *exec_ctx) {

src/core/iomgr/exec_ctx.h

@@ -61,8 +61,9 @@ struct grpc_exec_ctx {
   { GRPC_CLOSURE_LIST_INIT }
 
 /** Flush any work that has been enqueued onto this grpc_exec_ctx.
- *  Caller must guarantee that no interfering locks are held. */
-void grpc_exec_ctx_flush(grpc_exec_ctx *exec_ctx);
+ *  Caller must guarantee that no interfering locks are held. 
+ *  Returns 1 if work was performed, 0 otherwise. */
+int grpc_exec_ctx_flush(grpc_exec_ctx *exec_ctx);
 /** Finish any pending work for a grpc_exec_ctx. Must be called before
  *  the instance is destroyed, or work may be lost. */
 void grpc_exec_ctx_finish(grpc_exec_ctx *exec_ctx);