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From "Christopher L. Shannon (JIRA)" <>
Subject [jira] [Commented] (AMQ-5748) Add the ability to get Message Size from a Message Store
Date Tue, 28 Apr 2015 13:43:07 GMT


Christopher L. Shannon commented on AMQ-5748:

Hi Gary,

Thanks for taking a look at this and giving me your feedback.  My current use case is to use
this value as a metric, but having producer flow control  based on the destination would be
very useful as well.  Therefore, introducing a new destinationStatistic on top of adding the
method to the store is a really good idea.  There is already a message size statistic but
that seems to be just for what's in memory, so I can create a new statistic backed by the
index as you said.  I can update my pull request later today or tomorrow with the new destinationStatistic.
 Enabling producer flow control based on this new statistic could be done in another JIRA
after this change is finished.

In regards to mKahaDB, I currently am not using it but adding support for it is probably a
good idea.  I figured this could be expanded to other use cases as well, such as the JDBC
store, based on whether there is a demand for it or not.


> Add the ability to get Message Size from a Message Store
> --------------------------------------------------------
>                 Key: AMQ-5748
>                 URL:
>             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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