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https://issues.apache.org/jira/browse/FELIX-1545?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12749503#action_12749503
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Felix Meschberger commented on FELIX-1545:
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In Rev. 809597 implement last modification and last update trackers as simple
counters (instead of System.currentTimeMillis()) :
* last modification time is incremented whenever
Configuration.update(Dictionary) is called
* last update time is set to last modification time after each update of the
Configuration's properties in a ManagedSerive[Factory].
> Configurations may still be delivered more than once (or not at all)
> --------------------------------------------------------------------
>
> Key: FELIX-1545
> URL: https://issues.apache.org/jira/browse/FELIX-1545
> Project: Felix
> Issue Type: Bug
> Components: Configuration Admin
> Affects Versions: configadmin-1.2.4
> Reporter: Felix Meschberger
> Assignee: Felix Meschberger
> Fix For: configadmin-1.2.6
>
>
> Even after "fixing" FELIX-1146 and FELIX-1542 configurations may be delivered
> more than once. Under lab conditions it can even be observed, that
> configuration is not delivered at all.
> After digging into this issue a bit further (and writing test cases), it
> looks like we have three issues:
> (1) The granularity of System.currentTimeMillis() to feed the last
> modification time and last update time fields is to coarse causing false
> positives when testing whether configuration should be supplied or not
> (2) In contrast to service update due to Configuration.update(Dictionary),
> the updates cause by ManagedService[Factory] service registration do not
> observe the last update time field and thus may cause duplicate delivery
> T1: update configuration, schedule update task
> T2: register ManagedService, schedule update task
> T3: run update task from T1 --> ManagedService is registered and updated
> T3: run update task from T1 --> ManagedService is updated because last
> update time flag is ignored
> This last update call should not take place and must be guarded
> (3) After a service update the ManagedService update tasks (handling update
> after ManagedService registration) always sets the last update time flag,
> regardless of whether configuration properties exist or not.
> T1: create (empty) configuration
> T2: register ManagedService, schedule update task
> T1: update configuration, schedule update task
> T3: runs update task from T2, updates ManagedService with null (no
> proeprties) and updates last update time
> (last update time is now higher than last modification time even
> though no properties have been supplied)
> T3: runs update task from T1, but does *not* update ManagedService
> because last update > last modification
> Please note, that the third issue is actually much worse since it prevents
> the ManagedService from getting configuration at all !
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