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From "Timothy Bish (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AMQ-5748) Add the ability to get Message Size from a Message Store
Date Tue, 28 Apr 2015 20:33:06 GMT

    [ https://issues.apache.org/jira/browse/AMQ-5748?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14517981#comment-14517981
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Timothy Bish commented on AMQ-5748:
-----------------------------------

Have a look at StoredDestinationMarshaller in MessageDatabase.java (1909) for some insights
into handling version updates.  

> Add the ability to get Message Size from a Message Store
> --------------------------------------------------------
>
>                 Key: AMQ-5748
>                 URL: https://issues.apache.org/jira/browse/AMQ-5748
>             Project: ActiveMQ
>          Issue Type: New Feature
>          Components: Broker
>    Affects Versions: 5.11.1
>            Reporter: Christopher L. Shannon
>            Priority: Minor
>
> Currently, the {{MessageStore}} interface supports getting a count for messages ready
to deliver using the {{getMessageCount}} method.  It would also be very useful to be able
to retrieve the message sizes for those counts as well for keeping track of metrics.
> I've created a pull request to address this that adds a {{getMessageSize}} method that
focuses specifically on KahaDB and the Memory store.  The KahaDB store uses the same strategy
as the existing {{getMessageCount}} method, which is to iterate over the index and total up
the size of the messages.  There are unit tests to show the size calculation and a unit test
that shows a store based on version 5 working with the new version (the index is rebuilt)
> One extra issue is that the size was not being serialized to the index (it was not included
in the marshaller) so that required making a slight change and adding a new marshaller for
{{Location}} to store the size in the location index of the store.  Without this change, the
size computation would not work when the broker was restarted since the size was not serialized.
> Note that I wasn't sure the best way to handle the new marshaller and version compatibilities
so I incremented the KahaDB version from 5 to 6. If an old version of the index is loaded,
the index should be detected as corrupted and be rebuilt with the new format.  If there is
a better way to handle this upgrade let me know and the patch can certainly be updated.



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