Merge pull request #4587 from mitza-oci/master

boottime timers: support one-shot timers with zero delay

dds/DCPS/Timers.cpp

@@ -92,7 +92,14 @@ TimerId schedule(ACE_Reactor* reactor,
   }
   itimerspec ts;
   ts.it_interval = interval.value();
-  ts.it_value = (delay == TimeDuration()) ? interval.value() : delay.value();
+  if (delay == TimeDuration()) {
+    // avoid zeros since that would disarm the timer
+    // if the interval is positive, use that as the initial expiration
+    static const timespec one = {0, 1};
+    ts.it_value = (interval == TimeDuration()) ? one : interval.value();
+  } else {
+    ts.it_value = delay.value();
+  }
   if (timerfd_settime(fd, 0, &ts, 0) == -1) {
     if (log_level >= LogLevel::Notice) {
       ACE_ERROR((LM_NOTICE, "(%P|%t) NOTICE: Timers::schedule: timerfd_settime %m\n"));

tests/unit-tests/dds/DCPS/Timers.cpp

@@ -49,3 +49,18 @@ TEST(dds_DCPS_Timers, test_repeat)
   ASSERT_GT(handler->calls_, 10);
   Timers::cancel(&reactor, id);
 }
+
+TEST(dds_DCPS_Timers, test_immediate)
+{
+  RcHandle<TestEventHandler> handler = make_rch<TestEventHandler>();
+  ACE_Reactor reactor(new ACE_Select_Reactor, true);
+
+  const Timers::TimerId id = Timers::schedule(&reactor, *handler, 0, TimeDuration(), TimeDuration());
+  ASSERT_NE(id, Timers::InvalidTimerId);
+
+  ACE_Time_Value one_sec(1);
+  reactor.handle_events(one_sec);
+
+  ASSERT_EQ(handler->calls_, 1);
+  Timers::cancel(&reactor, id);
+}