Limit the number of syscalls made by the Eventhandler.

runtime/bin/eventhandler_android.cc

Index: runtime/bin/eventhandler_android.cc
diff --git a/runtime/bin/eventhandler_android.cc b/runtime/bin/eventhandler_android.cc
index 42ff0b094a6fe3a274b9a5592b9865e710c75665..8040e1ef4e2d24d391619eb98ff6c8071eeb3499 100644
--- a/runtime/bin/eventhandler_android.cc
+++ b/runtime/bin/eventhandler_android.cc
@@ -74,6 +74,9 @@ static void UpdateEpollInstance(intptr_t epoll_fd_, SocketData* sd) {
   event.events = sd->GetPollEvents();
   event.data.ptr = sd;
   if (sd->port() != 0 && event.events != 0) {
+    // Only report events once and wait for them to be re-enabled after the
+    // event has been handled by the Dart code.
+    event.events |= EPOLLONESHOT;

[zra, 2013/11/22 22:30:58]

Is this used only in the standalone VM? It isn't breaking the Android Dartium
build, but since EPOLLONESHOT doesn't exit in the NDK, it is breaking the
Android standalone VM build. (Sorry the Android build isn't possible from
build.py, yet. We're working on it. In the meantime maybe it would be best to
add me to CL's with Android changes so I can try them out before they land.)

     int status = 0;
     if (sd->tracked_by_epoll()) {
       status = TEMP_FAILURE_RETRY(epoll_ctl(epoll_fd_,
@@ -342,10 +345,6 @@ void EventHandlerImplementation::HandleEvents(struct epoll_event* events,
       SocketData* sd = reinterpret_cast<SocketData*>(events[i].data.ptr);
       intptr_t event_mask = GetPollEvents(events[i].events, sd);
       if (event_mask != 0) {
-        // Unregister events for the file descriptor. Events will be
-        // registered again when the current event has been handled in
-        // Dart code.
-        RemoveFromEpollInstance(epoll_fd_, sd);
         Dart_Port port = sd->port();
         ASSERT(port != 0);
         DartUtils::PostInt32(port, event_mask);
@@ -401,8 +400,9 @@ void EventHandlerImplementation::Poll(uword args) {
       if (errno != EWOULDBLOCK) {
         perror("Poll failed");
       }
-    } else {
+    } else if (result == 0) {
       handler->HandleTimeout();
+    } else {
       handler->HandleEvents(events, result);
     }
   }