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, 4 insertions, 0 deletions

diff --git a/src/core/lib/iomgr/iomgr.cc b/src/core/lib/iomgr/iomgr.cc
index eb29973514..a492146857 100644
--- a/src/core/lib/iomgr/iomgr.cc
+++ b/src/core/lib/iomgr/iomgr.cc
@@ -161,6 +161,10 @@ void grpc_iomgr_shutdown_background_closure() {
   grpc_iomgr_platform_shutdown_background_closure();
 }
 
+bool grpc_iomgr_is_any_background_poller_thread() {
+  return grpc_iomgr_platform_is_any_background_poller_thread();
+}
+
 void grpc_iomgr_register_object(grpc_iomgr_object* obj, const char* name) {
   obj->name = gpr_strdup(name);
   gpr_mu_lock(&g_mu);