Avoid the thread jump in server callback APIs.

Add a utility function in iomgr to check whether the caller thread is a
worker for any background poller, and keep grpc combiner from offloading
closures to the default executor if the current thread is a worker for
any background poller.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/core/lib/iomgr/iomgr.h b/src/core/lib/iomgr/iomgr.h
index 8ea9289e06..6261aa550c 100644
--- a/src/core/lib/iomgr/iomgr.h
+++ b/src/core/lib/iomgr/iomgr.h
@@ -39,6 +39,9 @@ void grpc_iomgr_shutdown();
  * background poller. */
 void grpc_iomgr_shutdown_background_closure();
 
+/** Returns true if the caller is a worker thread for any background poller. */
+bool grpc_iomgr_is_any_background_poller_thread();
+
 /* Exposed only for testing */
 size_t grpc_iomgr_count_objects_for_testing();