commit 30101b05c6cb9ad2bb90bbb1ef2d7a4b9c145ca5
author yang-g <yangg@google.com> Mon Nov 06 14:35:30 2017 -0800
committer yang-g <yangg@google.com> Mon Nov 06 15:12:52 2017 -0800
tree b6cd67631028aca66c83ad14b6e8821e6ce092f9
parent e5bca395f9bd9e6c017db3fd318ec608b5289341

log GRPC_POLL_STRATEGY when fail to find polling engine
also log reason to skip a polling engine

src/core/lib/iomgr/ev_epollsig_linux.cc

diff --git a/src/core/lib/iomgr/ev_epollsig_linux.cc b/src/core/lib/iomgr/ev_epollsig_linux.cc
index 035bdc4..0473db9 100644
--- a/src/core/lib/iomgr/ev_epollsig_linux.cc
+++ b/src/core/lib/iomgr/ev_epollsig_linux.cc
@@ -1708,16 +1708,20 @@
 
 const grpc_event_engine_vtable *grpc_init_epollsig_linux(
     bool explicit_request) {
+  const char *error_msg = NULL;
   /* If use of signals is disabled, we cannot use epoll engine*/
   if (is_grpc_wakeup_signal_initialized && grpc_wakeup_signal < 0) {
+    gpr_log(GPR_ERROR, "Skipping epollsig because use of signals is disabled.");
     return NULL;
   }
 
   if (!grpc_has_wakeup_fd()) {
+    gpr_log(GPR_ERROR, "Skipping epollsig because of no wakeup fd.");
     return NULL;
   }
 
   if (!is_epoll_available()) {
+    gpr_log(GPR_ERROR, "Skipping epollsig because epoll is unavailable.");
     return NULL;
   }
 
@@ -1725,6 +1729,8 @@
     if (explicit_request) {
       grpc_use_signal(SIGRTMIN + 6);
     } else {
+      gpr_log(GPR_ERROR,
+              "Skipping epollsig because uninitialized wakeup signal.");
       return NULL;
     }
   }
@@ -1750,6 +1756,8 @@
  * NULL */
 const grpc_event_engine_vtable *grpc_init_epollsig_linux(
     bool explicit_request) {
+  gpr_log(GPR_ERROR,
+          "Skipping epollsig becuase GRPC_LINUX_EPOLL is not defined.");
   return NULL;
 }
 #endif /* defined(GRPC_POSIX_SOCKET) */