adding handling EINTR to poll to make it more robust

some system call and signal will interrupt poll,
making event loop stops and fails to react events and keepalive message
from libvirt.
adding handling EINTR to poll to make it more robust
Signed-off-by: NRoyce Lv <lvroyce@linux.vnet.ibm.com>
(cherry picked from commit 5e62ba34)

examples/domain-events/events-python/event-test.py

@@ -178,48 +178,53 @@ class virEventLoopPure:
     def run_once(self):
         sleep = -1
         self.runningPoll = True
-        next = self.next_timeout()
-        debug("Next timeout due at %d" % next)
-        if next > 0:
-            now = int(time.time() * 1000)
-            if now >= next:
-                sleep = 0
-            else:
-                sleep = (next - now) / 1000.0
-
-        debug("Poll with a sleep of %d" % sleep)
-        events = self.poll.poll(sleep)
-
-        # Dispatch any file handle events that occurred
-        for (fd, revents) in events:
-            # See if the events was from the self-pipe
-            # telling us to wakup. if so, then discard
-            # the data just continue
-            if fd == self.pipetrick[0]:
-                self.pendingWakeup = False
-                data = os.read(fd, 1)
-                continue
-
-            h = self.get_handle_by_fd(fd)
-            if h:
-                debug("Dispatch fd %d handle %d events %d" % (fd, h.get_id(), revents))
-                h.dispatch(self.events_from_poll(revents))
-
-        now = int(time.time() * 1000)
-        for t in self.timers:
-            interval = t.get_interval()
-            if interval < 0:
-                continue
+        try:
+            next = self.next_timeout()
+            debug("Next timeout due at %d" % next)
+            if next > 0:
+                now = int(time.time() * 1000)
+                if now >= next:
+                    sleep = 0
+                else:
+                    sleep = (next - now) / 1000.0
+
+            debug("Poll with a sleep of %d" % sleep)
+            events = self.poll.poll(sleep)
+
+            # Dispatch any file handle events that occurred
+            for (fd, revents) in events:
+                # See if the events was from the self-pipe
+                # telling us to wakup. if so, then discard
+                # the data just continue
+                if fd == self.pipetrick[0]:
+                    self.pendingWakeup = False
+                    data = os.read(fd, 1)
+                    continue
+
+                h = self.get_handle_by_fd(fd)
+                if h:
+                    debug("Dispatch fd %d handle %d events %d" % (fd, h.get_id(), revents))
+                    h.dispatch(self.events_from_poll(revents))
 
-            want = t.get_last_fired() + interval
-            # Deduct 20ms, since schedular timeslice
-            # means we could be ever so slightly early
-            if now >= (want-20):
-                debug("Dispatch timer %d now %s want %s" % (t.get_id(), str(now), str(want)))
-                t.set_last_fired(now)
-                t.dispatch()
-
-        self.runningPoll = False
+            now = int(time.time() * 1000)
+            for t in self.timers:
+                interval = t.get_interval()
+                if interval < 0:
+                    continue
+
+                want = t.get_last_fired() + interval
+                # Deduct 20ms, since scheduler timeslice
+                # means we could be ever so slightly early
+                if now >= (want-20):
+                    debug("Dispatch timer %d now %s want %s" % (t.get_id(), str(now), str(want)))
+                    t.set_last_fired(now)
+                    t.dispatch()
+
+        except (os.error, select.error), e:
+            if e.args[0] != errno.EINTR:
+                raise
+        finally:
+            self.runningPoll = False
 
 
     # Actually the event loop forever