CHECK(ev->ev_base) so we get a proper message instead of just a SIGSEGV

Summary: CHECK(ev->ev_base) so we get a proper message instead of just a SIGSEGV

Reviewed By: yfeldblum

Differential Revision: D7118625

fbshipit-source-id: 9426ac54fc32e0d34ad36df97708e3f0ae6043a9

folly/io/async/EventBase.cpp

@@ -701,6 +701,9 @@ bool EventBase::scheduleTimeout(AsyncTimeout* obj,
   tv.tv_usec = long((timeout.count() % 1000LL) * 1000LL);
 
   struct event* ev = obj->getEvent();
+
+  DCHECK(ev->ev_base);
+
   if (event_add(ev, &tv) < 0) {
     LOG(ERROR) << "EventBase: failed to schedule timeout: " << strerror(errno);
     return false;