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https://issues.apache.org/jira/browse/NIFI-3567?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Pierre Villard resolved NIFI-3567.
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Resolution: Feedback Received
Apache NiFi 1.x is no longer maintained and no new release is planned on the
1.x release line. Marking as resolved as part of a cleanup operation. Please
open a new one with an updated description if this is still relevant for NiFi
2.x.
> CompoundUpdateMonitor logic flaw
> --------------------------------
>
> Key: NIFI-3567
> URL: https://issues.apache.org/jira/browse/NIFI-3567
> Project: Apache NiFi
> Issue Type: Bug
> Affects Versions: 0.7.1, 1.1.1
> Reporter: Brandon Rhys DeVries
> Priority: Minor
>
> The CompoundUpdateMonitor seems to be fundamentally flawed. When getting
> it's state, it returns a DeferedMonitorAction\[1]. This "lazily" loads the
> state of the monitors it has compounded, essentially meaning the state is
> calculated when equals() is called\[2]\[3].
> In other words, the state isn't calculated until you're comparing the state
> to a new state... at which point the states will evaluate the same. If the
> file hasn't actually changed, the state is now actually (at least partially)
> loaded, so a file change going forward will be detected. However, if a new
> file comes in before equals() has been called the change will not be detected.
> As CompoundUpdateMonitor doesn't appear to actually be used in Apache NiFi, I
> would suggest deprecating it, and removing in a future version. If a need
> for this functionality is present now or in the future, I'd recommend
> creating something such as a BooleanAndUpdateMonitor and
> BooleanOrUpdateMonitor, allowing developers to compose whatever behavior they
> want (instead of the forced AND logic of the CompoundUpdateMonitor). At the
> very least, the DeferedMonitorAction needs to be eliminated.
> \[1]
> https://github.com/apache/nifi/blob/rel/nifi-0.7.1/nifi-commons/nifi-utils/src/main/java/org/apache/nifi/util/file/monitor/CompoundUpdateMonitor.java#L40-L43
> \[2]https://github.com/apache/nifi/blob/rel/nifi-0.7.1/nifi-commons/nifi-utils/src/main/java/org/apache/nifi/util/file/monitor/CompoundUpdateMonitor.java#L87-L88
> \[3]
> https://github.com/apache/nifi/blob/rel/nifi-0.7.1/nifi-commons/nifi-utils/src/main/java/org/apache/nifi/util/file/monitor/CompoundUpdateMonitor.java#L64-L70
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