admin: fix monitoring timer after 2 identical consecutive checks

This fixes the bug that with only email notification, monitoring
stopped checking whether backup clusters are lagging after status is
unchanged since the last check (about lagging, what is compared is
the set of lagging backups). Until another event wakes up monitoring.

The code is also simplified in that there's no need for the moment to
have a different timeout between the normal case and a smtp failure.

neo/admin/app.py

@@ -30,7 +30,6 @@ from neo.lib.exception import PrimaryFailure
 from .handler import AdminEventHandler, BackupHandler, MasterEventHandler, \
     UpstreamAdminHandler, NOT_CONNECTED_MESSAGE
 from neo.lib.bootstrap import BootstrapManager
-from neo.lib.logger import INF
 from neo.lib.protocol import \
     CellStates, ClusterStates, Errors, NodeTypes, Packets
 from neo.lib.debug import register as registerLiveDebugger
@@ -167,7 +166,6 @@ class Application(BaseApplication, Monitor):
                 email_from = None
             self.email_from = formataddr(("NEO " + self.name, email_from))
         self.smtp_exc = None
-        self.smtp_retry = INF
         self.notifying = set()
 
         logging.debug('IP address is %s, port is %d', *self.server)
@@ -321,10 +319,9 @@ class Application(BaseApplication, Monitor):
                     backup.monitor_changed = False
                     changed.add(name)
             body = '\n'.join(body)
-        if changed or self.smtp_retry < time():
-            logging.debug('monitor notification')
         email_list = self.email_list
         while email_list: # not a loop
+            if changed or self.smtp_exc:
                 msg = MIMEText(body + (self.smtp_exc or ''))
                 msg['Date'] = formatdate()
                 clusters, x = severity[1:]
@@ -359,17 +356,17 @@ class Application(BaseApplication, Monitor):
                         self.smtp_exc = (
                             "\n\nA notification could not be sent at %s:\n\n%s"
                             % (msg['Date'], x))
-                    retry = self.smtp_retry = time() + 600
                 else:
                     self.smtp_exc = None
-                    self.smtp_retry = INF
+                    # The timeout is only to check whether a backup cluster is
+                    # lagging and for that, the main cluster and at least one
+                    # backup cluster must be operational. Else, remain passive.
                     if not (self.operational and any(monitor.operational
                             for monitor in self.backup_dict.itervalues())):
                         break
-                    retry = time() + 600
                 finally:
                     s.close()
-                self.em.setTimeout(retry, self._notify)
+            self.em.setTimeout(time() + 600, self._notify)
             break
         neoctl = self.asking_monitor_information
         if neoctl: