grpc_wait_or - Waits for any session to end.
  grpc_error_t grpc_wait_or(
                   grpc_sessionid_t *idArray,
                   size_t length,
                   grpc_sessionid_t *idPtr)
  grpc_sessionid_t *idArray  size_t length  grpc_sessionid_t *idPtrThe grpc_wait_or() function sessions waits for any one of the specified sessions to end.
This function is MT-safe unless multiple wait functions wait the same sessions simultaneously.
If successful, GRPC_NO_ERROR is returned. In the case of an error, Error code is returned.
  GRPC_NOT_INITIALIZED  GRPC_INVALID_SESSION_ID  GRPC_SESSION_FAILED  GRPC_TIMEOUT_NP  GRPC_OTHER_ERROR_CODE