Fix a race condition in NotificationComponent leading to duplicate notification #10628
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The race is between `NotificationTimerHandler`, which sends a reminder notification after a certain inverval during problem states and `SendNotificationsHandler` which sends out the notifications on state changes. When the timer handler runs just before a state change triggers a notification, the timer handler might pick up that state-change before the send notification handler can set its no_more_notifications flag. In that case a "reminder" notification will be sent out before the initial one, and despite `interval = 0` on the notification object.
Fix the race condition described in the previous commit by not requiring the no_more_notifications flag to skip reminders in case of `interval = 0`.
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Problem
The race is between
NotificationTimerHandler, which sends a reminder notificationafter a certain inverval during problem states and
SendNotificationsHandlerwhichsends out the notifications on state changes.
When the timer handler runs just before a state change triggers a notification, the
timer handler might pick up that state-change before the send notification handler
can set its no_more_notifications flag. In that case a "reminder" notification will
be sent out before the initial one, and despite
interval = 0on the notificationobject.
Solution?
The trivial solution here is to never attempt to send a reminder if
interval <= 0and not wait for the no_more_notifications flag. I'm not entirely sure if there are any negative consequences to that because I don't understand what this flag is even supposed to do. It seems it only gets set in case ofinterval <= 0and only ever used in this one place. I can think of many valid reasons to want to turn off reminders under certain conditions for a while, but this doesn't even do that, since it was an&&-condition, not an||(which it is in the current state of this PR).Fixes #10623.