Fix stepEventLoop timeout handling

- Respect user-provided timeout when timers exist
- Exit loop when epoll_wait times out with no events/timers

Fixes morganstanley#436

lib/hobbes/events/events.C

@@ -1,4 +1,3 @@
-
 #include <hobbes/hobbes.H>
 #include <hobbes/events/events.H>
 #include <hobbes/util/perf.H>
@@ -92,17 +91,21 @@ void registerInterruptHandler(const std::function<void()>& fn) {
 }
 
 bool stepEventLoop(int timeoutMS, const std::function<bool()>& stopFn) {
+  bool status = true;
   while (!stopFn()) {
     if (!timers.empty()) {
       auto next = timers.top().callTime;
       auto timeUntilNext = next - std::chrono::high_resolution_clock::now();
       int millis = std::chrono::duration_cast<std::chrono::milliseconds>(timeUntilNext).count();
-      timeoutMS = std::max(1, millis);
+      if (timeoutMS == -1) {
+        timeoutMS = std::max(1, millis);
+      } else {
+        timeoutMS = std::min(timeoutMS, std::max(1, millis));
+      }
     }
 
     struct epoll_event evts[64];
     int fds = epoll_wait(threadEPollFD(), evts, sizeof(evts)/sizeof(evts[0]), timeoutMS);
-    bool status = true;
     if (fds > 0) {
       for (int fd = 0; fd < fds; ++fd) {
         auto* c = reinterpret_cast<eventcbclosure*>(evts[fd].data.ptr);
@@ -112,6 +115,7 @@ bool stepEventLoop(int timeoutMS, const std::function<bool()>& stopFn) {
     } else if (fds < 0) {
       if (errno != EINTR) {
         status = false;
+        break;
       } else if (epClosures != nullptr) {
         auto f = epClosures->find(-1);
         if (f != epClosures->end()) {
@@ -142,10 +146,12 @@ bool stepEventLoop(int timeoutMS, const std::function<bool()>& stopFn) {
       for (auto& timer : newTimers) {
         timers.push(timer);
       }
+    } else {
+      // No events and no timers, break on timeout
+      break;
     }
-    return status;
   }
-  return false;
+  return status;
 }
 
 void runEventLoop(const std::function<bool()>& stopFn) {